IPG_CarMaker Reference Manual

CarMaker

®

Cover

Reference Manual Version 2.1

2

The information in this document is furnished for informational use only, may be revised from time to time, and should not be construed as a commitment by IPG Automotive GmbH. IPG Automotive GmbH assumes no responsibility or liability for any errors or inaccuracies that may appear in this document. This document contains proprietary and copyrighted information and may not be copied, reproduced, translated, or reduced to any electronic medium without prior consent, in writing, from IPG Automotive GmbH. © 1999 - 2006 by IPG Automotive GmbH – www.ipg-automotive.com All rights reserved. FailSafeTester, IPG-CAR, IPG-CONTROL, IPG-DRIVER, IPG-ENGINE, IPG-GRAPH, IPGKINEMATICS, IPG-LOCK, IPG-MOTORCYCLE, IPG-MOVIE, IPG-ROAD, IPG-ROADDATA, IPG-TIRE, IPG-TRAILER, IPG-TRUCK are trademarks of IPG Automotive GmbH. CarMaker, TruckMaker, MotorcycleMaker, MESA VERDE are registered trademarks of IPG Automotive GmbH. All other product names are trademarks of their respective companies.

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Contents

1

Introduction

9

1.1

General Remarks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

1.2

CarMaker Axis Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

1.3

CarMaker Geometry Input . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Conventions defining CarMaker Objects . . . . . . . . . . . . . . . . . . 12 Guidelines defining CarMaker Objects . . . . . . . . . . . . . . . . . . . 12

1.4

CarMaker Naming Conventions . . . . . . . . . . . . . . . . . . . . . . . . 14 CarMaker Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Classification of Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Meaning of Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

1.5

CarMaker Directory Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 18

1.6

About Parameter Files and Datasets . . . . . . . . . . . . . . . . . . . . 20 Database Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 FileIdent, Description and FileCreator . . . . . . . . . . . . . . . . . . . 20 Model Kind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 CarMaker Configuration Files . . . . . . . . . . . . . . . . . . . . . . . . . . 21

1.7

‘SimParameters’ File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Application Parameters of CarMaker/HIL . . . . . . . . . . . . . . . . . 22 CarMaker Environment Parameters . . . . . . . . . . . . . . . . . . . . . 23 Data Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Maneuver Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 Start of test run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

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End of test run . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

2

1.8

‘ECUParameters’ File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27

1.9

‘OutputQuantities’ File . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28

1.10

General Parameters for TestRun Files . . . . . . . . . . . . . . . . . . . 29

1.11

Software Interfaces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Driving Maneuvers

32

2.1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.2

Longitudinal Dynamics Maneuvers . . . . . . . . . . . . . . . . . . . . . . 34 Speed Control (VelControl) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

2.3

Lateral Dynamics Maneuvers . . . . . . . . . . . . . . . . . . . . . . . . . . 35

2.4

Special Maneuvers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 The first Mini Maneuver (Duration 0 Seconds) . . . . . . . . . . . . . 36 The last Mini Maneuver (Duration 0 Seconds) . . . . . . . . . . . . . 36

2.5

3

User Accessible Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Vehicle Body 3.1

38

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 Configuration of the vehicle model . . . . . . . . . . . . . . . . . . . . . . 39 Finding the equilibrium state . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 Vehicle Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Interaction with other modules . . . . . . . . . . . . . . . . . . . . . . . . . 40

3.2

General Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

3.3

Mass Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

3.4

4

5

User Accessible Quantities for Vehicle Body . . . . . . . . . . . . . . 45

Suspension Force Elements

46

4.1

External Suspension Forces . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

4.2

Springs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48

4.3

Dampers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

4.4

Buffers / Bumpers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53

4.5

Suspension Roll Stabilizer / Anti-Roll Bar . . . . . . . . . . . . . . . . . 57

Suspension Kinematics and Compliance 5.1

60

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60 Describing Kinematics with Generalized Coordinates . . . . . . . 65 Brief Introduction to the Measurement Procedure of K&C parameters

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68 5.2

Kinematics and Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . 70

5.3

Kinematics Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 “Linear” and “Linear2D” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 “MapNL” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 “SetZero” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76

5.4

Compliance Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77 “CoeffConstFr1” and “CoeffConstFr2” . . . . . . . . . . . . . . . . . . . . 77 “SetZero” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 “CoeffLin1DFr1” and “CoeffLin1DFr2” . . . . . . . . . . . . . . . . . . . . 80 “DisplaceLinFr1” and “DisplaceLinFr2” . . . . . . . . . . . . . . . . . . . 81 Example: Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83

6

Aerodynamics

84

6.1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 84

6.2

General Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86

6.3

Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 ‘Coeff6x1’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87

7

Steering System 7.1

88

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 Steer by Angle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90 Steer by Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91

7.2

Steering System Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . 92 General Steering System Parameters . . . . . . . . . . . . . . . . . . . . 92 Steering System ’Classic’ Parameters . . . . . . . . . . . . . . . . . . . 92

8

7.3

User Accessible Quantities for Steering Systems . . . . . . . . . . . 93

7.4

Steering System Software Interface . . . . . . . . . . . . . . . . . . . . . 94

PowerTrain 8.1

95

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95 Interface Powertrain – Vehicle . . . . . . . . . . . . . . . . . . . . . . . . . . 95 PowerTrain Subsystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96 Interfaces of Powertrain Subsystems . . . . . . . . . . . . . . . . . . . . 97 General Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98

8.2

Powertrain ’Generic’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 General Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Model ‘Generic’ Differential Parameters . . . . . . . . . . . . . . . . . 105

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Model ‘Generic’ Coupling Parameters . . . . . . . . . . . . . . . . . . 108 8.3

Engine Torque . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110 Engine Torque Model ‘Mapping’ . . . . . . . . . . . . . . . . . . . . . . . 111 Engine Torque Model ‘Linear’ . . . . . . . . . . . . . . . . . . . . . . . . . 117 Engine Torque Model ‘DVA’ . . . . . . . . . . . . . . . . . . . . . . . . . . . 118 Engine Model Software Interfaces . . . . . . . . . . . . . . . . . . . . . 119

8.4

Clutch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120 Clutch Model ‘Manual’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 Clutch Model ‘Converter’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Clutch Model ‘DVA’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 127

8.5

Gear Box . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 GearBox Model ‘Manual’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 129 GearBox Model ‘DVA’ . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130

9

8.6

User Accessible Quantities for PowerTrain . . . . . . . . . . . . . . . 131

8.7

Powertrain Software Interface . . . . . . . . . . . . . . . . . . . . . . . . . 132

Brake System 9.1

135

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Brake Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 136

9.2

Brake System Software Interface . . . . . . . . . . . . . . . . . . . . . . 137

9.3

General Brake System Parameters . . . . . . . . . . . . . . . . . . . . . 138

9.4

User Accessible Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . 140 General User Accessible Quantities for Brake Systems

9.5

. . . . 140

Brake System PresDistrib . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 142 Brake System PresDistrib Parameters . . . . . . . . . . . . . . . . . . 143

9.6

Brake System HydESP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 Brake circuit configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 147 Brake booster . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 149 Master Cylinder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 Wheel brakes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158 Volume elements in general . . . . . . . . . . . . . . . . . . . . . . . . . . 160 Wheel brake cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161 Low pressure accumulator . . . . . . . . . . . . . . . . . . . . . . . . . . . 163 Attenuators (damper chambers) and line volumes . . . . . . . . . 164 Hydraulic pump (return pump) . . . . . . . . . . . . . . . . . . . . . . . . 165 Valves and Connecting Lines in General . . . . . . . . . . . . . . . . 168 Solenoid valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170

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Proportional Solenoid Valves . . . . . . . . . . . . . . . . . . . . . . . . . 172 Dynamic Solenoid Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 174 Inlet Valves with check valve . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Pilot valve with check valve and pressure limiting valve . . . . . 179 Suction valve . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181 Check Valve of the Low Pressure Accumulator . . . . . . . . . . . 182 User Accessible Quantities for Brake Module ‘HydESP’ . . . . 186

10

Tire

188

10.1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 188 Tire Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 190 Tire load (normal force) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 191 Tire Model Computations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

10.2

General Tire Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193

10.3

Tire Model RT-Tire . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 194 Rolling Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 196 Importing Tire Measurements . . . . . . . . . . . . . . . . . . . . . . . . . 196

10.4

Tire Model Magic Formula . . . . . . . . . . . . . . . . . . . . . . . . . . . 197 The basics of Magic Formula . . . . . . . . . . . . . . . . . . . . . . . . . 197 Tire Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Scale factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 200 Effective tire rolling radius . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 Slip computation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 206 Longitudinal force (pure longitudinal slip): . . . . . . . . . . . . . . . . 207 Lateral force (pure side slip): . . . . . . . . . . . . . . . . . . . . . . . . . . 210 Aligning Torque (pure side slip) . . . . . . . . . . . . . . . . . . . . . . . . 213 Longitudinal Force (combined slip) . . . . . . . . . . . . . . . . . . . . . 218 Lateral force (combined slip) . . . . . . . . . . . . . . . . . . . . . . . . . . 220 Aligning Torque (combined slip) . . . . . . . . . . . . . . . . . . . . . . . 223 Overturning Couple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 Rolling Resistance Moment . . . . . . . . . . . . . . . . . . . . . . . . . . 226 Transient Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 227 Gyroscopic couple . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 228 Friction coefficient . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 230

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Trailer Model

232

11.1

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 232

11.2

General Trailer Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

11.3

Mass Geometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234

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Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 234 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 11.4

Suspension Force Elements . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Spring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Damper . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Stabilizer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

11.5

Suspension Kinematics and Compliance . . . . . . . . . . . . . . . . 239 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Sleeve Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 239 Crank Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 240 Semi Trailing Arm Axle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 241 General Suspension Model Parameters . . . . . . . . . . . . . . . . . 242 Additional Parameters for Suspension Model “Sleeve” . . . . . . 243 Additional Parameters for Suspension Model “Crank” . . . . . . 243 Additional Parameters for Suspension Model “SemiTrailingArm” . . 244 Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 245

11.6

Hitch . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Additional Parameters for Hitch “Ball” . . . . . . . . . . . . . . . . . . . 249 Additional Parameters for Hitch “Trapez” . . . . . . . . . . . . . . . . 249 Additional Parameters for Hitch “BallFric” . . . . . . . . . . . . . . . . 250 Additional Parameters for Hitch “BallDamp” . . . . . . . . . . . . . . 250

11.7

Brake System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 251 Additional Parameters for Brake Model “Overrun” . . . . . . . . . 251 Additional Parameters for Brake Model “Overrun1” . . . . . . . . 252

11.8

Aerodynamics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253

11.9

User Accessible Quantities for Trailer . . . . . . . . . . . . . . . . . . . 254 General User Accessible Quantities: Trailer . . . . . . . . . . . . . . 254

12

User Accessible Quantities 12.1

General User Accessible Quantities

257 . . . . . . . . . . . . . . . . . . . 258

User Accessible Quantities: Driving Maneuvers 12.2

. . . . . . . . . . 259

User Accessible Quantities for Vehicle Body . . . . . . . . . . . . . 260 User Accessible Quantities: Vehicle . . . . . . . . . . . . . . . . . . . . 260 User Accessible Quantities: Car (for unexperienced users) . . 261

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User Accessible Quantities: Car 12.3

. . . . . . . . . . . . . . . . . . . . . . 262

User Accessible Quantities: Power Train . . . . . . . . . . . . . . . . . 268 User Accessible Quantities for PowerTrain

. . . . . . . . . . . . . . 268

User Accessible Quantities for PowerTrain ‘Generic’ . . . . . . . 268 User Accessible Quantities for Module ‘Engine’ . . . . . . . . . . . 269 User Accessible Quantities for Module ‘Clutch’ . . . . . . . . . . . 269 User Accessible Quantities for Module ‘GearBox’ . . . . . . . . . 270 12.4

User Accessible Quantities: Steering Systems . . . . . . . . . . . . 271 General User Accessible Quantities: Steering Systems

12.5

. . . . 271

User Accessible Quantities: Brake System . . . . . . . . . . . . . . . 272 General User Accessible Quantities for Brake Systems

. . . . 272

User Accessible Quantities for Brake Module ‘HydESP’ . . . . 274 12.6

User Accessible Quantities: Trailer . . . . . . . . . . . . . . . . . . . . . 275 General User Accessible Quantities: Trailer . . . . . . . . . . . . . . 275

12.7

A

B

UAQ´s changed from CM 2.0 to CM 2.1 . . . . . . . . . . . . . . . . . 278

Appendix

281

Mini-Maneuver Command Language

282

A.1

Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 282

A.2

Driving Maneuver Commands . . . . . . . . . . . . . . . . . . . . . . . . . 284

A.3

Direct Variable Access Commands . . . . . . . . . . . . . . . . . . . . . 285

A.4

Action Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 287

A.5

Logging Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 288

A.6

FailSafeTester Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . 290

Traffic-Obstacles B.1

291

Parameters and Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . 294 Motion of an Obstacle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 296 Output Quantities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 298

B.2

Functions, Types and Variables . . . . . . . . . . . . . . . . . . . . . . . 299 Obsts_New() - create a new obstacle management . . . . . . 300 Obsts_ObstclNew() - create an new obstacle . . . . . . . . . . 300 Obsts_iGetObstcl() - get obstacle from infofile . . . . . . . . 300 Obsts_ObstclAdd() - add a new obstacle . . . . . . . . . . . . 300 Obsts_ObstclGetInfo()-getsinformationaboutdefinedobstacle 301 Obsts_ObstclDelete() - delete an obstacle . . . . . . . . . . . 301 Obsts_EndOfInput() - no additional obstacles . . . . . . . . 301 Obsts_ObstVecNew() - get a obstacle output vector . . . . . 302

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Obsts_Calc() - calculate the obstacle module . . . . . . . . . . 303 Obsts_GetObstsAbs() - get absolute obstacle states . . . . 303 Obsts_GetObstsRel() - get relative obstacle states . . . . . 304 Obsts_ObstVecDelete() - free obstacle output vector . . . 304 Obsts_Delete() - free obstacle management . . . . . . . . . . 304 Example: Using Obstalces “by Hand” . . . . . . . . . . . . . . . . . . . 305 B.3

CarMaker Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 Variables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 306 Obstacles_Init() - initailizes obstacle module . . . . . . . . . 306 Obstacles_New() - create obstalces . . . . . . . . . . . . . . . . . 306 Obstacles_Calc () - calculate obstacles . . . . . . . . . . . . . 306 Obstacles_Delete () - delete obstacles . . . . . . . . . . . . . 306 Obstacles_Cleanup() - cleanup obstacle module . . . . . . 307 Examples: Using Obstacles by CarMaker . . . . . . . . . . . . . . . . 308

B.4

C

IPG-MOVIE C.1

D

310

312

Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 312

Road-Obstacles and Markers E.1

309

IPG-MOVIE-INFO – Meta Information in Geometry Files . . . . 310

Start Conditions D.1

E

Obstacle Utility obstutil . . . . . . . . . . . .

313

Description of Road-Obstacles . . . . . . . . . . . . . . . . . . . . . . . . 313 Cylinders . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 314 Beams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 315 Waves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 316 Cones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 317

E.2

Description of Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 318 Pylons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 319 Velocity Signs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 320 SideWind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 321

E.3

CarMaker Reference Manual

Description of Digitized Road . . . . . . . . . . . . . . . . . . . . . . . . . 322

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General Remarks

Chapter 1

Introduction

This is the CarMaker Reference Manual. It contains definitive informations about the usage of the different tools and modules bundled in the CarMaker software package.

1.1

General Remarks CarMaker tries to keep as close as possible to conventions and naming of ISO 8855 1991, modified (or US English DIN 70000). This applies amongst other issues to axis systems, kinematics of the sprung mass, forces and moments, suspension, vehicle response and wheels and tires. All parameters and quantities are specified in SI-quantities unless otherwise stated: Table 1.1: SI Units used with CarMaker Quantity

Name

Symbol

Time

second

s

Length

meter

m

Angle

radian (one turn = 2*π)

rad

Mass

kilogram

kg

Inertia

kilogram meter sqared

kg*m2

Force

newton

N

Torque

newton meter

Nm

Stiffness

newton per meter

N/m

Rotational Stiffness

newton meter per radian

Nm/rad

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CarMaker Axis Systems

1.2

CarMaker Axis Systems In the virtual world of CarMaker different axis systems for different purposes are used. They are used to simplify calculation and parametrization for CarMaker objects (including signals and variables) and to be able to represent different points of views for CarMaker objects.

y

z

z

Fr1 Mntrl f ( q 0, q 1 )

Fr2 y x

Mntrr f (t) z

f ( q 0, q 1 )

z

Fr2

Fr2

f ( q 0, q 1 )

y

Mntfl

x

z

Fr2

z

Mntfr

y x

x

f ( q 0, q 1 ) y x

y

Fr0 x Figure 1.1: CarMaker Coordinate systems

Frame Fr0 The CarMaker inertial axis system is called Fr0 (pronounced: frame zero). This is the earth fixed origin of the ‘virtual world’. Fr0 is defined as follows: •

(O) is the origin, (X), (Y), (Z) are the 3 axis.

•

(O, X, Y) is the horizontal driving plane (road).

•

(Z) is directed upwards (mathematically: ( X ) × ( Y ) ).

•

The position of any point, if not mentioned explicitly otherwise, is expressed in Fr0.

Frame Fr1 Moving objects in the virtual world are based on their own accompanied axis system which is called Fr1. This axis system is fixed to the moving object. This means that the axis system performs all movements of the attached object like translations and rotations. Fr1 is defined as follows: •

(X) points in forward driving direction.

•

(Y) points to the left.

•

(Z) is directed upwards (mathematically: ( X ) × ( Y ) ).

•

In case of a vehicle no part of the outer skin is situated behind the (O, Y, Z)-plane. At least one point of the outer skin has a vanishing X-coordinate. (see section 1.3)

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CarMaker Axis Systems

•

In case of a trailer no part of the outer skin is situated before the (O, Y, Z)-plane. (see section 1.3)

Frame Fr2 (carrier axis system) For every wheel there is a mountpoint (Mnt) defined within the Fr1 system. This is the center of reference of a Fr2 axis system attached to this mount-point. Mount-points are pure translations (X,Y,Z) from the Fr1 axis system. They are fixed to the Fr1 system. There are functional dependencies (suspension kinematics and compliance) how Fr2 is orientated relatively to its mount-point. There are two generalized coordinates (q 0,q 1) for the movement of each Fr2 axis system. Usually q 0 stands for compression and q 1 for steer influence. Fr2 is defined as follows: •

Rules apply to any of the wheel carriers

•

(O) is the center of the wheel. It is in the wheel plane.

•

(X) points in forward driving direction.

•

(Y) is along the wheel spin axis. Vector points to the left.

•

(Z) is directed upwards (mathematically: ( X ) × ( Y ) ).

•

Initially (all coordinates of Fr2 are zero) Fr2 is parallel to Fr1.

•

(O, X, Z) is the wheel plane.

Frame FrX The frame FrX (pronounced: cross frame) represents a road surface axis system. The (O, X, Y) -plane approximately describes the current orientation of the road surface. Like Fr1 this is a accompanied axis system as well and moves uniformly to Fr1. FrX is defined as follows: •

(O) is located in the middle between the two road surface contact points of the rear wheels.

•

(X) is orientated from (O) to the middle of the two road surface points of the front wheels.

•

(Y) is orientated along the connection from the rear left to the rear right road surface contact point.

•

(Z) is oriented upwards (mathematically: ( X ) × ( Y ) ).

Frame FrD The FrD (pronounced: design-frame) is a parallel axis system to Fr1 with different origin. It is used to specify geometry input coordinates which are based on a different origin than Fr1 without recomputing them. See section 1.3.2 ’Guidelines defining CarMaker Objects’ on page 12. FrD is defined as follows: •

(O) is arbitrary

•

(X) is parallel to Fr1 (X) axis.

•

(Y) is parallel to Fr1 (Y) axis.

•

(Z) is parallel to Fr1 (Z) axis.

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CarMaker Geometry Input

1.3

CarMaker Geometry Input To define new objects (vehicles, trailers) a good understanding of the CarMaker principles and conventions is needed to obtain the expected results. The information provided in this section is very useful for this task.

1.3.1

Conventions defining CarMaker Objects As a convention CarMaker objects have to be defined with their origin of Fr1 at designated positions. This is important because CarMaker assumes the origin at those designated places for every object. The following table shows the conventions where the origin for which objects has to be:. Table 1.2: Origins of CarMaker Fr1 Objects

1.3.2

Type of Fr1

Origin

Vehicle

Origin for the vehicles Fr1 is the hindmost point of the vehicle projected on road level.

Trailer

Origin for the trailers Fr1 is the hitch point (foremost point) of the trailer projected on road level. (Trailer objects have negative X-coordinates).

Guidelines defining CarMaker Objects To define a new CarMaker object geometry data has to be provided. Geometry data e. g. is needed for body mass, mount-points for (carrier-)frames, and additional loads (inclusive trimloads and engine mass).

loads

engine

trimloads

Fr2FrontLeft vehicle body

Fr2RearLeft MntRearRight

Fr2RearRight

CoM

FrD

MntFrontRight

Fr2FrontRight

r1 in F

orig

Fr1 Fr0 Figure 1.2: CarMaker geometry input for a vehicle

The position and orientation of any point/frame is given in design configuration (‘drawing sheet of the designer of the car’). As shown in Figure 1.2 the axis FrD (called design-frame) is a parallel axis system to Fr1 with different origin. The configurations specified in FrD must be linked to the Fr1 by a vector pointing to the origin of Fr1 (expressed in FrD coordinates).

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CarMaker Geometry Input

In the special case where FrD ≡ Fr1 the link vector is the zero vector. Design configuration not necessarily has to be equilibrium configuration!

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CarMaker Naming Conventions

1.4

CarMaker Naming Conventions To ensure maximum readability, it is tried to keep the notation as consistent and self-explanatory as possible.

1.4.1

CarMaker Subsystems The following rules to name CarMaker subsystems apply: Model Abbrev.

CarMaker Reference Manual

Description

Ambient

Ambient constants

Brake

Brake subsystem

Car

Car subsystem

DM

Maneuver control subsystem (DrivMan)

FST

FailSaveTester

IO

IO subsystem

Log

Log subsystem

PT

Powertrain subsystem

Sensor

Vehicle body sensors

Steer

Steering subsystem

TC

Task commands (Minimaneuvers)

TCPU

Monitoring of CPU time consumption

Time

CarMaker timer

Tr

Trailer subsystem

Vhcl

Vehicle means subset of Car, Motorcycle, Truck subsystem

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CarMaker Naming Conventions

1.4.2

Classification of Quantities With the following classifications groups of quantities are denoted. Those groups denote points of interests like the center of mass of components or single components and their significant quantities. The letters

CarMaker Reference Manual

... in general stand for

Aero

Aerodynamic related quantities

Buffer, Buf

Suspension buffer/bumper related quantities

C

Carrier related quantities

Camber

Camber (wheel) related quantities

Clutch

Clutch related quantities

Con

Quantities related to connected body: center of mass of the rigid vehicle body including vehicle body, engine, trimloads and loads

Damp

Damper (shock absorber) related quantities

DL

Driveline related quantities

Engine

Engine related quantities

Fr0, Fr1, Fr2, FrX

Quantities related to this Frame (= axis system)

Gearbox

Gearbox related quantities

Gen

Quantities related to the generalized body: center of mass of generalized body including all masses of the connected body including masses of wheel carriers and wheels. (“Car.Gen”, “Tr.Gen”)

Gen

Powertrain Generic related quantities (“PT.Gen”)

Hitch

Trailer hitch related quantities

HydESP

HydESP brake model related quantities (“Brake.HydESP”)

Jack

Jack related quantities

Load

Extra loads of the vehicle

PoI

Point of interest related quantities

Spring

Suspension spring related quantities

Stabi

Anti-Roll-Bar stabilisator related quantities

Steer

Steer subsystem related quantities

Valve

Brake hydraulic valves related quantities

Virtual

Virtual forces and torques related quantities

W

Wheel related quantities

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CarMaker Naming Conventions

1.4.3

Meaning of Abbreviations CarMaker uses the following abbreviations for the naming of quantities. The letters

CarMaker Reference Manual

... in general stand for

0, 1, 2, 3,..

Numbering

_0, _1, _2

Postfix for quantity expressed in Fr0, Fr1, Fr2

_ext

External

_tot

Total

a

Acceleration

Align

Aligning movement

Axle

Suspension left, right, front, back

C

Center

Diff

Differential

Distance, Dist

Distance

DL

Driveline

F

Front

FL, FR, RL, RR

Front left, front right, rear left, rear right

Frc

Force

Hori

projection of a quantity to the O,X,Y plane

l

Length

l

Lateral

LongSlip

Long slip (tangential) of wheel

Man

Maneuver

MC

Master brake cylinder

muRoad

Friction coefficient

No

Number

P

Tire contact point with track

p

Pressure

q

Flow (hydraulic)

q, q0, q1

Generalized coordinates

r

Rotation

R

Rear

Radius

Radius

Rate

Angular velocity

res

Resultant

rot

Rotation angle

rotv

Rotation angle velocity

Slip

Slip (lateral) of wheel

Spd

Speed

SS, SideSlip

Side slip of vehicle

SW

Switch

t

Translation

T

Tire

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CarMaker Naming Conventions

The letters

CarMaker Reference Manual

... in general stand for

T

Temperature

T, Time

Time

tau

Angle of attack of wind

Trq

Torque

v, vel

Velocity

WB

Wheel brake

x, y, z

Coordinate directions

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CarMaker Directory Structure

1.5

CarMaker Directory Structure Project Directory Below is the directory structure of a typical project directory. Listing 1.1: | |-bin Real-time program, user specific | GUIs, like e. g. Instruments | |-doc Online Docu to simulator | |-src Development environment |-Data Data basis | | | |- Vehicle Vehicle data | |- Chassis Kinematics and Compiance of axles | | | |-Config Configuration of the test bed: ECUParameters, SimParameters, | | OutputQuantities | | | |-Misc Misc., e.g. parameters for the hydraulic | | | |-Pic Views of vehicles (for GUI) | |-Road Measured road definitions (RoadData) | |-TestScript ScriptControl test-scripts | |-TestRun Test runs | |-Tire Tire data | |-Trailer Trailer data | |-Movie Animation, movie | Vehicle and road geometry files | |-SimInput Data for Input_From_File |-SimOutput Results of simulations | |-Offline | |-rt1 | | |-Log | | |-YYYYMMDD

•

The bin directory contains the CarMaker executable or executables. It might also contain custom applications or tools that were created specifically for the project.

•

The doc directory would contain documentation that would apply to the project. CarMaker documentation, e.g this document, does not reside in the doc directory but is included in the CarMaker installation directory along with library files and most of the CIT applications.

•

The src directory includes the C source files that can be modified by the user. By making changes to the source files new CarMaker executables can be built that would incorporate modifications and additional functionality needed for a particular project.

•

The data directory includes all the vehicle parameter files, user and IPG defined testruns, configuration data, and other data used by CarMaker.

•

The movie directory includes files needed for IPG-MOVIE. For example, if a custom car body is used in the animation then the file would be here.

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CarMaker Directory Structure

•

The SimInput directory contains simulation data files that are used when CarMaker runs by using file input.

•

The SimOutput directory contains the simulation results that are optionally saved when a testrun is performed.

Installation Directory It also might be useful to show the CarMaker installation directory, i.e. where the CarMaker tools have been installed, along with the CarMaker libraries and documentation. Shown below is an example of the installation directory of the LynxOS or realtime version of CarMaker, installed in the unix environment. Listing 1.2: | |-bin Programs like Instruments, | User interface HIL | |-doc Online documentation |-Examples Example projects and files |-GUI Graphical User Interface scripts, executables, etc. |-include Include-files |-lib Libraries |-lynx_rt LynxOS runtime environment |-Matlab Support package for Matlab/Simulink |-Setup Template and definition files

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About Parameter Files and Datasets

1.6

About Parameter Files and Datasets The CarMaker application needs parameter files and datasets. For this purpose CarMaker uses keyword oriented parameter files called Infofiles. They are plain ascii text files but a specific syntax is used.

1.6.1

Database Syntax Infofiles use keywords which can be followed by

1.6.2

•

a ‘=’ character and several values up to the end of line,

•

a ‘:’ character and a multi line entry in the following lines. Each line must start with a character.

FileIdent, Description and FileCreator To recognize any changes and incompatibilities of parameters format and norm (e. g. using a new CarMaker version with out of date datasets) a identification key for each file is used. The identification key shows the model class, the submodel class and the current version. This identification key is called “FileIdent” and has to be specified in the first line of a parameter file.

FileIdentt = CarMaker-KindString [ VersionId ]

Syntax

CarMaker-[-]



Example Current FileIdents

Tire, Brake, Car, TestRun,... Optional, for submodels with referenced parameters, e.g. separate files for brake model parameters or engine torque diagram. Version of parameter file, whole-numbered, positive

FileIdent = CarMaker-PowerTrain.ET-4WD 2

Currently Carmaker supports the following Fileidents: Infofile

FileIdent

TestRun

CarMaker-TestRun

TestSeries

CarMaker-TestSeries

Tire

CarMaker-Tire-

Car

CarMaker-Car

Suspension (kinematics CarMaker-SuspMapping and compliance)

CarMaker Reference Manual

Trailer

CarMaker-Trailer

Brake

CarMaker-Brake-

ECUParameters

CarMaker-ECUParameters

SimParameters

CarMaker-SimParameters

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About Parameter Files and Datasets

Description :

DescriptionText

Description, displayed in parameter browsers

FileCreator =

String

This entry answers the question: Which tool creates this parameter set? How can it be characterized?

1.6.3

Model Kind The kind key is used to specify a submodel (e. g. a specific powertrain model). Prefix.Kind = KindStr [ VersionId ] KindStr is the characteristic name of submodel, or variation of submodel. VersionId is optional. It is used to support different versions of parameter sets for the same model (compatibility, parameter convertion etc.). Example

1.6.4

PowerTrain.ET.Kind = Mapping 2

CarMaker Configuration Files CarMaker knows the following configuration files: File

Purpose

SimParameters

All parameters influencing the simulation flow.

ECUParameters

Parameters and calibration settings for ECU´s used with a test stand.

OutputQuantities

Specifies list of quantities for saving results in CarMaker.

The files are searched in the sub directory Data/Config/[.hostname]. Example

Data/Config/SimParameters Data/Config/ECUParameters.rt1

If a file with hostname matches it has priority over a file without a specific hostname.

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‘SimParameters’ File

1.7

‘SimParameters’ File In SimParameters all “global” (test run, vehicle, ... independent) simulation specific parameters are given in different subsections decribed below.

1.7.1

Application Parameters of CarMaker/HIL

Cycle.dtLimitHigh = DeltaT Optional. Default 0.002 s.

Cycle.dtLimitLow = DeltaT Optional. Default 0.0001 s.

Cycle.tCTViolationWarn = DeltaT Optional. Default 0.0015 s.

Cycle.tCTViolationErr = DeltaT Optional. Default 0.003 s.

Cycle.maxtCTViolation = DeltaT Optional.

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‘SimParameters’ File

1.7.2

CarMaker Environment Parameters

FirstInit.TestRun = TestRunName Test-run to initialize the application the first time, before a test run is started. Default: ““ to use internal defaults.

TestRunEnd.DVA_ReleaseAll = DoIt At the end of a test run, all active direct variable write access can be closed. Default: 0, don’t release all, keep write access active.

1.7.3

Data Storage

DStore.dtFile = deltaT Optional. Time step between two data vectors for storage. Default 0.02 s.

DStore.OutQuantFName = OutQuantFilename Optional, Configuration file for selecting quantities to be written to file. Filename relative to Data/Config/. Default “OutputQuantities”.

DStore.OutSubDir = DirectoryName Optional. Directory to store simulation results. If DirectoryName is empty, the directory name is created by current date, formatted as . Default ““.

DStore.OutFNameWithTime = WithTime Optional. Append simulation start time to the result file name. Default 1.

DStore.BufSize_kB = Size_in_kBytes Size of data collecting buffer.

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‘SimParameters’ File

1.7.4

Maneuver Control

DrivMan.Engine.AutoStart = AutoStart Optional, default 1.

DrivMan.Engine.tWaitAfterEngineOn =deltaT Optional, default 2.0 s, see also section ’PowerTrain.ET.tWaitAfterEngineOn = deltaT’.

Road.VhclStartPos_TrailerMin =

MinStartPos_m

Optional, default 10 m. Minimal vehicle road start coordinat when driving with a trailer. Get Idle

DrivMan.GetIdle.Brake = DrivMan.GetIdle.Brake.d_dt =

Activation Velocity

Optional, default Activation=0, Velocity=1000.

DrivMan.GetIdle.BrakePark = Activation DrivMan.GetIdle.BrakePark.d_dt = Velocity Optional, default Activation=0, Velocity=1000.

DrivMan.GetIdle.BrakeLever = DrivMan.GetIdle.BrakeLever.d_dt =

Activation Velocity

Optional, default Activation=0, Velocity=1000.

DrivMan.GetIdle.Brake.vVhcl_BrakeEnd =

MaxVhclVelocity

Optional, default 0.1 m/s. Vehicle velocity to end braking while state GetIdle.

DrivMan.GetIdle.dSteerAngledt =

SteerAngleVelocity_deg/s

Optional, default 45 deg. Steer angle velocity to center steering system.

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‘SimParameters’ File

DrivMan.GetIdle.SelectorCtrl =

SelectorCtrl

Optional, default 0. Is Idle

DrivMan.IsIdle.Brake =

Activation

Optional, default 0.0.

DrivMan.IsIdle.BrakeLever =

Activation

Optional, default 0.0.

DrivMan.IsIdle.BrakePark =

Activation

Optional, default 0.0.

DrivMan.IsIdle.SelectorCtrl =

Position

Optional, default 0.

DrivMan.IsIdle.SetNeutral =

SetNeutral

Optional, default 1. Set gear box to neutral position. Shifting

DrivMan.AutoShift.dtDontShift =

delatT

Optional, default 0.2 s.

DrivMan.AutoShift.GasReduction = Reduction Optional, default 0.8.

DrivMan.AutoShift.dt_declutch =

DeltaT

Optional, deafult 0.1 s.

DrivMan.AutoShift.dt_keepclutch = DeltaT Optional, default 0.1 s.

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‘SimParameters’ File

DrivMan.AutoShift. dt_enclutch=

DeltaT

Optional, default 0.5 s.

DrivMan.VelCtrl.tClutchRelease =

value

Optional, default 1.0 s.

1.7.5

Start of test run

SimStart.TimeLimit =

TimeLimit

Maximal duration of state SimStart. Default: 60 s

DrivMan.Start.ExtInp_SteerVel =

SteerVelMax_deg

Used for external inputs maneuvers to build up the steering angle at start of input.

1.7.6

End of test run

GetIdle.TimeLimit =

TimeLimit

Optional. Default 200 s.

GetIdle.Skip =

Skip

Optional. Default: 0 for HIL, 1 for non-HIL.

GetIdle.Kl15Off =

SwitchOff

Optional. Default: 0 for HIL, 1 for non-HIL.

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‘ECUParameters’ File

1.8

‘ECUParameters’ File In ECUParameters all Input/Output, hardware or ECU specific parameters are stored in this parameter set: •

Signal conditioning

•

FailSafeTester configuration, see Programmers Guide section 12.3 ’Configuring the FailSafeTester’ on page 283

•

et al.

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‘OutputQuantities’ File

1.9

‘OutputQuantities’ File This file keeps a simple list with all quantity names (one per line spelled like they can be looked up in IPG Control). All quantities denoted in this file are stored by the CarMaker´s Storage of Results functionality. It is possible to use only one ‘*’ wildcard per pattern.

Example

Brake.Trq_FL Brake.Trq_* Car.*FL

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General Parameters for TestRun Files

1.10

General Parameters for TestRun Files These Parameters can be specified in a CarMaker TestRun file. They apply for all sub models.

Ambient.Temperature = Temperature_K Optional. Ambient temperature in degree Kelvin. Default 293.15 K.

Ambient.AirDensity = value Optional. Air density in kg/m3. Default 1.205

Ambient.AirPressure = value Optional. Air pressure in bar. Default 1.024 bar.

Ambient.AirHumidity = value Optional. Air humidity (no dimension 0..1). Default 0.2

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Software Interfaces

1.11

Software Interfaces The vehicle model uses the model manager to “handle models”. This means: For a submodel of the car – for example steering system, brake system, tire, engine, ... – more than one implementation (or model) can be available in the simulation program. The model to be used in a testrun is selected by an identifier string in a parameter file, for example “Brake.Kind = HydESP” in the vehicle parameter set to select the brake model “HydESP”. 1: 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: 12: 13: 14: 15: 16: 17: 18: 19:

int Brake_Register_HydESP (void) { tModelClassDescr m; /* clear model class description structure */ memset (&m, 0, sizeof(m)); /* assign model interface m.Brake.VersionId = m.Brake.CompatVersionId = m.Brake.New = m.Brake.Calc = m.Brake.Delete = m.Brake.DeclQuants =

functions */ ThisVersionId; CompatVersionId; Brake_HydESP_New; Brake_HydESP_Calc; Brake_HydESP_Delete; Brake_HydESP_DeclQuants;

/* register the model, kind string and interface functions */ return Model_Register (ModelClass_Brake, "HydESP", &m); } Listing 1.3:

The model manager supports the following car submodels, called model classes:c 1: typedef enum { 2: ModelClass_PTEngine, 3: ModelClass_PTClutch, 4: ModelClass_PTGearBox, 5: ModelClass_PTDriveLine, 6: ModelClass_PowerTrain, 7: ModelClass_PTGenCoupling, 8: ModelClass_Steering, 9: ModelClass_Brake, 10: ModelClass_Tire, 11: 12: } tModelClass; Listing 1.4: Model Classes

The model manager is initialized at program start with 1: int 2: Model_Init (void);

Models are registered at program start, before the first simulation starts with 3: int 4: Model_Register ( 5: tModelClass 6: const char 7: tModelClassDescr 8: );

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ModelClass, *KindStr, *MD

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Software Interfaces

The model manager is cleaned up before program exits with 9: int 10: Model_Cleanup (void);

Example: Registration and usage of a brake model The registration function for the brake model with kind key “HydESP” is called once at program start. What CarMaker does to start a submodel (example for a brake model): •

Look for a model with the corresponding kind string.

•

If the model is found by Model_LookUp() the New() function is called to create an initialized model.

•

If the initialization was successful, the DelcQuants() function is called to update the quantities in CarMaker´s data dictionary.

•

The functions Calc() and Delete() are stored to calculate the model and to delete the model parameters before create a new model at the beginning of next simulation 11: 12: 13: 14: 15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26: 27: 28: 29: 30: 31:

CarMaker Reference Manual

tModelClassDescr*md; const char *ModelKind; ModelKind = iGetStr(Inf, KindKey); if ((md=Model_LookUp(ModelClass_Brake, ModelKind)) == NULL) { LogErrF (EC_Init, "Brake: Unknown kind ’%s’",KindKey); goto ErrorReturn; } brake.param = md->Brake.New(inf, ““); if (brake.param == NULL) goto ErrorReturn; if (md->Brake.DeclQuants != NULL) md->Brake.DeclQuants (brake.param);

brake.md.Brake.Calc = brake.md.Brake.Delete =

md->Brake.Calc; md->Brake.Delete;

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Overview

Chapter 2

Driving Maneuvers

2.1

Overview The CarMaker testrun is build by one or more maneuver steps, called “mini maneuvers”. The mini maneuver events are composed by •

longitudinal dynamics actions: accelerating, braking, gear shifting, ...

•

lateral dynamics actions: steering

•

additional actions, defined by a list of mini maneuver commands

Parameters The driving maneuvers and driving behavior can be configured •

in the test run (test run specific)

•

in the vehicle model parameter set (vehicle specific in)

•

in the SimParameters parameter set (global).

A prefix is build up for each mini maneuver by the string “DrivMan.”, followed by the mini maneuver number. The keys of all parameters for each maneuver starts with this prefix. DrivMan.. ...

TestRun Data Set

DrivMan.nDMan =

NumberOfMiniMan

This entry defines the number of minimaneuvers of this test run. The first maneuver is the maneuver 0 (zero).

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Overview

Vehicle Data Set

PowerTrain.ET.tWaitAfterEngineOn =

deltaT

Optional. Overwrites parameter DrivMan.Engine.tWaitAfterEngineOn from file SimParameters (see section ’DrivMan.Engine.tWaitAfterEngineOn = deltaT’).

DrivMan.nShift :

GearNo_nUp_nDown_table

Optional. Configures the auto shifting module of the speed controller. Each line contains the following values: •

Gear number GearNo, positive for forward, negative for backward gears

•

engine speed to shift up, unit rpm.

•

engine speed to shift down, unit rpm.

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Longitudinal Dynamics Maneuvers

2.2

Longitudinal Dynamics Maneuvers The following maneuvers are available:

2.2.1

•

Drive with IPG-DRIVER

•

Drive speed profile

•

Manual Control: Gas, Brake, BrakeLever (motorcycle), BrakePark, Clutch, Gear

•

Speed Control (VelControl)

Speed Control (VelControl)

Pre.Long = VelControl Vel_km/h TolVel_m/s Sensity PremEnd

Special Meaning!

Pre.Long =

VelControl StartVel_kmh

GearNo

In case of •

first maneuver in the test run

•

duration time is set to 0.0

this maneuver has a special meaning. It defines longitudinal starting conditions. In the GUI: Entry fieled “Speed” gives vehicle starting speed, “Max. Deviation” gives the gear number.

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Lateral Dynamics Maneuvers

2.3

Lateral Dynamics Maneuvers The following maneuvers are available: •

Drive the course with IPG-DRIVER

•

Sinus steering

•

Steer step

•

Simple steer control

Steering Maneuvers A smooth transition mode was added for Sinus and Steer Step. The mode can be enabled with a checkbox in the CarMaker GUI’s Maneuver dialog, under Lateral Dynamics.

Steer Step

Sinus

Steer Step

Sinus

Smooth Transition

Smooth Transition

During a simulation, mini-maneuver commands can be changed on the fly. An example application of this new feature would be to use ScriptControl (the corresponding SetMiniManCmd command is available with this release) to access the FailSafeTester with very precise timing by using the appropriate mini-maneuver commands for FST control.

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Special Maneuvers

2.4

Special Maneuvers

2.4.1

The first Mini Maneuver (Duration 0 Seconds) If the first mini maneuver (number 0) has the duration 0 seconds, it has a special meaning: Instead of defining a real driving maneuver it defines the test run starting conditions. The following configuration is possible:

2.4.2

•

Speed control (VelControl): start velocity, gear number (entry field “Max. Deviation”)

•

Steer step: steering angle (entry field “Amplitude”)

The last Mini Maneuver (Duration 0 Seconds) If the last mini maneuver has the duration 0 seconds, it has a special meaning: This maneuver is called at the end of the test run even if the test run is stopped before (by user, by an error, ...).

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User Accessible Quantities

2.5

User Accessible Quantities Please refer to section 12.1.1 ’User Accessible Quantities: Driving Maneuvers’.

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Overview

Chapter 3

Vehicle Body

3.1

Overview The simulated vehicle is a multi body system which is characterized through different bodies. They are generated and optimized with MESA VERDE. Description of the bodies: Body

Parts of the body

vehicle’s body

All sprung masses beside engine, trimloads and vehicle loads.

engine

Engine as a separate mass (easily changeable motorization).

trimloads

Constant loads to be added up to vehicle’s curb load.

vehicle loads

Additional loads to define a certain load case, e.g. measuring equipment, luggage... (changeable from GUI).

wheel suspension - front left - front right - rear left - rear right

All unsprung masses without the wheel, like link, wheel carrier, suspension leg, wishbone mount...

wheel - front left - front right - rear left - rear right

All rotating masses, like tire, rim, bearing, brake drum/disc...

External and internal forces/torques and constraints are determined by: •

Suspension Force Elements

•

Aerodynamics

•

Kinematics and Compliance

•

Tire forces/torques

•

User defined virtual forces and torques

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Overview

Additionally the vehicle model supports the feature to calculate body fixed sensors for acceleration, velocity, rotational acceleration and rotational velocity.

3.1.1

Configuration of the vehicle model To obtain the typical behavior of a certain type of vehicle the multi body system is extensively parameterizable. The parameters are selected in a way that all type of vehicles, from a small compact car up to a big SUV can be simulated by only changing the set of parameters. There is no need to change the structure of the multi body system (the underlying equations).

3.1.2

Finding the equilibrium state By pressing the start button and after initialization the vehicle starts at steady state. This is called the start-off configuration. This means the vehicle is in equilibrium state respecting all internal and external forces/torques (no acceleration, but nonzero velocities, in general). Parameters for the vehicle configuration are given in design configuration. The expression design configuration does not only refer to geometric quantities, but includes all other design parameters (masses, spring-stiffnesses, ...) as specified by the car-manufacturer. A design configuration usually is not a configuration of static equilibrium!

Procedure

Design Configuration

mq-equilibrium multiple steps mq-equilibrium Static equilibrium Aerodynamics, VehicleLoads, TrimLoads

mq-equilibrium Steady state Start-off configuration

Figure 3.1: Finding steady state for the vehicle model

For computation coordinates q and parameters p are distinguished. Parameters are time invariant, coordinates are not. Parameters need not be geometrical, but also include masses, stiffnesses, etc. The design configuration has the coordinates and parameters ( q d, p d ) . To find the steady state position of the vehicle a procedure called Modify-q-equilibrium (mq-equilibrium) is used. Mq-equilibrium modifies some of the coordinates q such that: •

Parameters p obtain prescribed values.

•

The configuration is an equilibrium configuration.However, at this stage no additional charges (trimloads, vehicle loads) are added to the system.

( q d, p d )

CarMaker Reference Manual

p = p0 ⇒ ( q e, p e ) modify q

(EQ 1)

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Overview

The start-off configuration is a configuration that matches the initial conditions of a particular test-run. It differs from a nominal configuration (static equilibrium) by taking into account: •

Trim-loads, vehicle loads

•

Start-off (or initial) driving velocity.

•

Aerodynamics.

The start-off configuration is obtained from the nominal configuration by modifying q , keeping p fixed:

( q e, p e )

3.1.3

keep p const ( q s, p s ) . ⇒ modify q

(EQ 2)

Vehicle Interface The vehicle body is the central model. It consists of the Mesa Verde multibody vehicle model along with predefined interfaces to other modules. The vehicle body interface is defined in Vehicle.h. Alternative vehicle models have to fill this interface with life.

3.1.4

Interaction with other modules The vehicle body module interferes with other modules from the vehicle library.

Brake System

Powertrain

Vehicle Body

Trailer

Steer System Tire

Interface Figure 3.2: Modules interfering with the vehicle body

Each module has an interface to the vehicle body module. By this interfaces parameters and coordinates of the vehicle body are modified.

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General Parameters

3.2

General Parameters RefPointInputSystem =

x

y

z

This parameter specifies the origin of the Fr1 (in FrD coordinates). The coordinates XYZ point from the origin of FrD to the origin of Fr1. (see section 1.2 ’CarMaker Axis Systems’). Example

RefPointInputSystem =

-2.0 0.0 0.0

This means that the origin of Fr1 is 2 m behind (in vehicles longitudinal direction) FrD.

Hitch.pos =

x

y

z

Hitch (trailer coupling device) position at the vehicle expressed in FrD coordinates. Example

Hitch.pos = 0.0 0.0 0.3

Virtual.PoA =

x

y

z

The virtual force/torque attacks the vehicle body in Virtual.PoA. Virtual.PoA is decomposed in FrD. Default position is the center of mass of vehicle body (see page 43).

Virtual.PoA_1 =

x

y

z

Point of attack of the virtual force/torque. Virtual.PoA_1 is decomposed in Fr1. Virtual.PoA_1 overwrites Virtual.PoA.

Picture.PicFName =

FName

File name of the Tcl/Tk Picture you see in the main HIL application. The file is searched in the Data/Pic folder. Unimportant for simulation results. Example

Picture.PicFName = VW_NewBeetle.tcl

Movie.Skin.FName = Example

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FName

Picture.PicFName = VW_NewBeetle.obj

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General Parameters

Vehicle.OuterSkin =

rll.x

rll.y

rll.z

fur.x fur.y fur.z

Vehicles outer skin box, defined by the points rear lower left (rll) and front upper right (fur). Example

Vehicle.OuterSkin =-0.1 0.85 0.2 4.05 -0.85 1.6

Jack.fl.pos = Jack.fr.pos = Jack.rl.pos = Jack.rr.pos =

x x x x

y y y y

z z z z

Optional. Jack positions at vehicle chassis.

SimParamFName =

FName

Optional. Name of the file containing simulation parameters. File is searched in /Data/Config. Default SimParameters or SimParameters.. The usage of the parameters ECUParamFName and SimParamFName may lead to inconsistencies with IO initialization. For experts only!

ECUParamFName =

FName

Optional. Name of the file containing parameters of Electronic Control Units (ECU) IO-Signal calibrations. File is searched in /Data/Config. Default ECUParameters or ECUParameters.. The usage of the parameters ECUParamFName and SimParamFName may lead to inconsistencies with IO initialization. For experts only!

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Mass Geometry

3.3

Mass Geometry

3.3.1

Overview The representation of the distribution of mass in a material system is called mass geometry. Inertia properties are associated with the vehicle-body, each of the four wheel carriers and each wheels. Additional body loads are modeled via additional masses and inertias as well. Three parameters have to be specified to define a mass element: •

The mass value of the body to define.

•

The center of mass (CoM) of each body is defined. The center of mass is a geometrical point. The three scalar quantities are the position vector of CoM decomposed relative to the origin of the definition frame.

•

The inertia tensor (= second moments of mass = moments of inertia) is a symmetric second-order tensor, which is specified by six scalar quantities I = A B C D E F (Frequently the off-diagonal elements (D, E, F) of the inertia tensor are neglected):

∫

A F E F B D = E D C

2

( y + z 2 ) dm

–

symmetry

∫

xy dm

–

∫

2

( z + x 2 ) dm

–

symmetry

xz dm

∫

yz dm

(EQ 3)

Body

Body

symmetry

∫

Body

Body

Body

∫

2

( x + y 2 ) dm

Body

3.3.2 Parameters

Parameters The following parameters are required for this model:

Body.pos Body.mass Body.I The vehicle body without engine. Its center of mass is placed in the design frame at Body.Pos. The vehicle body has the mass Body.mass and the inertia tensor Body.I. The elements of the inertia tensor are given in the order A B C D E F. It is sufficient to give the elements A B C (main diagonal elements) only. A vehicle body with inertia A=360 kg*m2, B=800 kg*m2, C=1800 kg*m2: Body.mass = Body.Pos = Body.I =

375.0 1.5 0.0 0.45 360 800 1800

Engine.pos Engine.mass Engine.I The engine body. The engine is fixed on the Body of the vehicle. For details, see vehicle body.

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Mass Geometry

WheelCarrier.fl.pos WheelCarrier.fl.mass WheelCarrier.fl.I Wheel carrier front left. Represents all unsprung mass in the suspension (except the wheel).

WheelCarrier.fr.pos WheelCarrier.fr.mass WheelCarrier.fl.r Wheel carrier front right. For details, see wheel carrier front left.

WheelCarrier.rl.pos WheelCarrier.rl.mass WheelCarrier.rl.I Wheel carrier rear left. For details, see wheel carrier front left.

WheelCarrier.rr.pos WheelCarrier.rr.mass WheelCarrier.rr.I Wheel carrier rear right. For details, see wheel carrier front left.

Wheel.fl.pos Wheel.fl.mass Wheel.fl.I Wheel front left. The wheel and all other rotating components (parts of the brake, ...) .

Wheel.fr.pos Wheel.fr.mass Wheel.fl.r Wheel front right. For details, see wheel front left.

Wheel.rl.pos Wheel.rl.mass Wheel.rl.I Wheel rear left. For details, see wheel front left.

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User Accessible Quantities for Vehicle Body

Wheel.rr.pos Wheel.rr.mass Wheel.rr.I Wheel rear right. For details, see wheel front left.

TrimLoad..pos TrimLoad..mass TrimLoad..I Bodies to trim mass contribution to that of a reference vehicle. Trim loads are fixed to vehicle body. := 0, 1, 2, ... Do not confuse TrimLoads with test run specific additional charges you may want to put on your vehicle.

3.4

User Accessible Quantities for Vehicle Body Please refer to section 12.2 ’User Accessible Quantities for Vehicle Body’.

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Chapter 4

Suspension Force Elements

The contribution of each suspension force element results in the wheel contact force. Four types of force elements are modeled: •

the suspension spring (Spring),

•

the suspension damper (DampPull, DampPush),

•

the suspension buffer (BufPull, BufPush) and

•

the stabilizer or anti-roll bar or stabilizer bar (Stabi).

spring damper buffer push wheel center stabilizer compression tz z x y

buffer pull

Figure 4.1: Force elements shown at left wheel

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External Suspension Forces

4.1

External Suspension Forces External suspension forces are added to the forces generated by the CarMaker build in models for spring/bumpers, damper and stabilizer: F SpringTot = F Spring + F SpringExt

(EQ 4)

F DampTot = F Damp + F DampExt F StabiTot = F Stabi + F StabiExt There is multiple usage for external suspension forces (according to (EQ 4)): •

Replace suspension forces by external forces. This is used when a custom suspension model (e. g. simulink model) should replace the CarMaker built in model for some or all suspension forces. The original forces have to be set to zero by the “amplify” parameters (.XXX.Amplify = 0).

•

Add forces to forces calculated by the built in model. This can be used to simulate forces from a active suspension device which are superpositioned to the conventional forces.

ExtSuspFrcs.FName = FileName or ExtSuspFrcs.Kind = ModelKind The model is selected by the Kind entry ModelKind. Instead of using the Kind key, an external parameter set can be referenced by its filename FileName. FileName is the path relative to the miscellaneous directory.

General Remarks •

Suspension models has to be registered by CarMakers model management mechanism. Each model needs -

a unique kind key to reference exactly this model from the pool of suspension models.

-

interface functions to initialize, calculate and delete a model instance

•

All parameters other than (*.FName and *.Kind) are model specific. Their keys has to start with the prefix "ExtSuspFrcs."

•

Known from earlier CarMaker version (before 2.1) the amplify parameters *.Spring_ext.Amplify, *.Damp_ext.Amplify, *.Stabi_ext.Amplify doesn’t exist any longer. If they are needed they have to be implemented in the suspension model itselfe.

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Springs

4.2

Springs This module simulates a conventional spring suspension. It calculates the spring component force F Spring . As shown in Figure 4.3 there is a relation between the deflection of the wheel and the spring. There is a translation between the forces F z and F Spring and between the travel of the wheel t z and the spring x∗ .

FS

pri

ng

x

tz

FZ

x0 x*

Figure 4.3: Calculation of spring forces

When the suspension gets compressed the spring length x is decreasing and the resulting spring force is increasing. To accommodate this the following calculation is applied: *

F Spring = amp ⋅ f ( x ) *

x = –( x – x0 )

.

(EQ 5)

The factor amp in (EQ 5) can be used to modify the the spring forces by a given factor. Usually this is for test purposes only and the factor should remain set to one. The quantity x 0 is called relaxed (or unstretched) length of the spring. The resultant spring force depends on the difference between the relaxed length x 0 and the actual length x . The actual length is the current distance between lower and upper attachment point of the spring.

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Springs

According to (EQ 5) the calculation of x∗ needs the actual spring length x . It is obtained from the suspension kinematics module according to Figure 4.4. q represents the generalized coordinates of the suspension.

q

suspension kinematics module

F q, Spring

spring component

x

f (q) ∂x ----∂q

F Spring

F = f ( x∗ )

Figure 4.4: Transformation of spring deflections and forces

If no spring length is parametrized, minus wheel compression tz is used.

Parameters SuspF means front axle, SuspR means rear axle

*.Spring.Amplify = Factor Spring amplification factor Factor.

*Spring.l0 = UnstrechedLength Unstretched (i.e. force free) length UnstrechedLength of the spring.

*.Spring:

DataTable *

This characteristic translates compression ( x from (EQ 5)) to spring force.

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Dampers

4.3

Dampers This module simulates a suspension damper. It calculates the force F Damp . The suspension dampers force F Damp depends on the velocity x˙ . Different characteristics are taken into account by defining different functions for “pull” ( x˙ > 0 ) and “push” ( x˙ ≤ 0 ).

FD

am p

x

tz

FZ

x˙

Figure 4.5: Calculation of damper forces

A increasing length x of the damper leads to a positive velocity x˙ . F Damp ( x˙ ) = amp ⋅ F DampPull ( x˙ )

x˙ > 0

F Damp ( x˙ ) = amp ⋅ F DampPush ( x˙ )

x˙ ≤ 0

.

(EQ 6)

The amp factor in (EQ 6) can be used to to modify the results of the calculation by a given factor. Usually this is for test purposes only and the factor should remain set to one. The dampers pull/push characteristics are defined seperately. Pull is when the damper is getting longer, push is when the damper is getting shorter.

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Dampers

The velocity x˙ is calculated by differentiation of the damper length x . It is obtained from the suspension kinematics module according to Figure 4.6. q represents the generalized coordinates of the suspension. suspension kinematics module

q

f (q)

F q, Damp

∂x ----∂q

damper component

x˙

push or pull?

F = f ( x˙ )

F Damp

Figure 4.6: Transformation of damper deflections and forces

If no damper length is parametrized, minus wheel compression tz is used.

All characteristics have to be defined in first quadrant. CarMaker takes care of the correct signs.

F definition in 1st quadrant

x˙ Figure 4.7: Definition of damper push and pull characteristics

Parameters

*.Damp_Push.Amplify = Factor Damper push force amplification factor Factor (see (EQ 6)).

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Dampers

*.Damp_Push:

DataTable

This characteristic translates compression velocitiy x˙ to damper push force. It has to be defined in first quadrant (positive velocities, positive forces). F Damp ( 0 ) = 0 should be obeyed. The table has two columns, velocity in m/s in the first, the damper forces in N the second. Example

SuspF.Damp_Push: 0 0 0.05 90 0.13 140 0.26 250 0.39 330 0.52 410 1.04 790

*.Damp_Push.Amplify = Factor Damper push force amplification factor Factor (see (EQ 6)).

*.Damp_Push:

DataTable

This characteristic translates extention velocitiy x˙ to damper pull force. It has to be defined in first quadrant (positive velocities, positive forces). F Damp ( 0 ) = 0 should be obeyed. The table has two columns, velocity in m/s in the first, the damper forces in N the second.

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Buffers / Bumpers

4.4

Buffers / Bumpers This module simulates suspension push/pull buffers. F BufPull is the force of the lower bumpstop, F BufPush is the force of the upper bump-stop.

tz x 0Push

FBufPush

t z0Push

buffer push

x 0Pull

t z0Pull FBufPull

buffer pull

Figure 4.8: Buffer elements shown at left wheel

The suspension buffers forces F BufPull , F BufPush depend on the buffer compression x : F BufPush = amp ⋅ f ( x∗ )

*

x = x 0, Push – x

F BufPull = 0

(EQ 7)

*

x 0

*

x = x – x 0, Pull *

x 0

.

(EQ 8)

x 0, Push , x 0, Pull are the relaxed (or unstretched) length of the upper/lower bump-stop. For the calculation of the buffer forces according to (EQ 7) and (EQ 8) the actual buffer compression x is needed. It is obtained from the suspension kinematics module according to Figure 4.9. q represents the generalized coordinates of the suspension.

q

F q, Buf

suspension kinematics module

f (q) ∂x ----∂q

buffer component

x

F Buf

push or pull?

F = f ( x∗ )

Figure 4.9: Transformation of buffers deflections and forces

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Buffers / Bumpers

If no buffer length is parametrized, minus wheel compression tz is used.

The following figure illustrates the calculation of the buffer compression from the non-linear kinematics file:

tz

max ( t z )

values not important for calculation of buffers

x 0, Pull

t z0, Push push buffer compression

p u l l b u f fe r compression

x 0, Push

max ( x Push )

max ( x Pull )

Push buffer active

x

t z0, Pull min ( t z )

Pull buffer active

Figure 4.10: Calculating the buffer length out of kinematic data

The two paramters t z0, Push and t z0, Pull have correspponding buffer compression zero offset values x 0, Push and x 0, Pull .The absolut values are unimportant since there is always the difference calculated from the current compression value to its zero offset. Of importance is that the gradient of the compression curve is always negative, so that according to (EQ 7) and (EQ 8) a positive buffer compression is calculated. Values given between x 0, Push and x 0, Pull are ignored from CarMaker and therefore are not important. The amp factor in (EQ 7) and (EQ 8) can be used to to modify the results of the calculation function by a given factor. Usually this is for test purposes only and the factor should remain set to one. The buffers pull/push characteristics are defined seperately.

Parameters SuspF means front axle, SuspR means rear axle

SuspF.Buf_Push.Amplify SuspR.Buf_Push.Amplify Push Buffer amplification factor. Example

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SuspF.Buf_Push.Amplify = 1.0

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Buffers / Bumpers

SuspF.Buf_Push.tz0 SuspR.Buf_Push.tz0

Syntax Susp.Buf_Push.tz0 = val

Unit: m

Push buffer position (defines ride clearance). According to (EQ 7) and Figure 4.8 the push buffer only acts for vertical displacements tz (of wheel carrier) greater than tz0(=x0Push). Example

SuspF.Buf_Push.tz0 = 0.055 SuspR.Buf_Push.tz0 = 0.055

SuspF.Buf_Push SuspR.Buf_Push This characteristic translates buffer compression x to buffer push force. It has to be to be defined in first quadrant. Syntax

Infofile table mapping with 2 columns

Example

SuspF.Buf_Pushl: 0.002 0.004 0.006 0.008 0.010 0.012 0.015

32.0 88.0 167.0 269.0 393.0 596.0 1085.0

SuspF.Buf_Pull.Amplify SuspR.Buf_Pull.Amplify Pull buffer amplification factor. Example

SuspF.Buf_Pull.Amplify = 1.0

SuspF.Buf_Pull.tz0 SuspR.Buf_Pull.tz0 Pull buffer mount position (defines rebound clearance). According to (EQ 8) and Figure 4.10 the pull buffer only acts for vertical displacements tz (of wheel carrier) smaller than tz0(=x0Pull). Example

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SuspF.Buf_Pull.tz0 = -0.09

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Buffers / Bumpers

SuspF.Buf_Pull SuspR.Buf_Pull This characteristic translates buffer compression x to buffer pull force. It has to be to be defined in first quadrant.. Syntax

Infofile table mapping with 2 columns

Example

SuspF.Buf_Push: 0.002 0.004 0.006 0.008 0.010 0.012 0.015

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32.0 88.0 167.0 269.0 393.0 596.0 1085.0

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Suspension Roll Stabilizer / Anti-Roll Bar

4.5

Suspension Roll Stabilizer / Anti-Roll Bar This module simulates a roll stabilizer (stabi). A force F Stabi acts if there is a difference between the right t zr and the left t zl wheel compression.

F Stabi2Susp, r

tz F Stabi, l t zl

αl F Stabi2Susp, l

xl αr

stabilizer

xr

t zr

F Stabi, r

Figure 4.11: Roll stabilizer principal

In general, according to Figure 4.11, the wheel compression ratio is not equal to the stabilizer deflection difference ( t∗ ≠ x∗ ). The stabilizer deflection difference x∗ can be defined either by a deflection length difference (EQ 9) or by a deflection angle difference (EQ 10): t∗ = t zr – t zl x∗ = x r – x l

,

(EQ 9)

t∗ = t zr – t zl x∗ = α r – α l

.

(EQ 10)

The constant c Stabi has to fit to the selected definition of x∗ . The forces F Stabi,l,r calculate to: F Stabi , l = amp ⋅ f ( x∗ ) = amp ⋅ c Stabi ⋅ x∗ F Stabi , r = – F Stabi , l

,

(EQ 11)

with the amplification factor amp. Under normal circumstances the amplification factor should be set to 1 (only for testing and scaling).

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Suspension Roll Stabilizer / Anti-Roll Bar

The forces are transformed in direction of the wheel deflection as follows: ∂x l F Stabi2Susp, l = F Stabi , l ⋅ ------∂q l ∂x r F Stabi2Susp,r = F Stabi , r ⋅ ------∂q r

.

(EQ 12)

For the calculation of the stabilizer forces according to (EQ 11) the actual stabilizer deflection difference x∗ is needed. It is obtained from the suspension kinematics module according to Figure 4.12. q represents the generalized coordinates of the suspension.

q

suspension kinematics module

x zr , x zl

f (q)

F q, Stabi, l

or

α zr, α zl

∂x ----∂q

F q, Stabi, r

stabilizer component

F Stabi, l, F Stabi, r

F = f ( x∗ )

Figure 4.12: Transformation of stabilizers deflections and forces

If no stabi length is parametrized, minus wheel compression tz is used.

Parameters SuspF means front axle, SuspR means rear axle

SuspF.Stabi.Amplify = SuspR.Stabi.Amplify =

value value

Stabilizer amplification factor Example

SuspF.Stabi.Amplify = 1.0

SuspF.Stabi. = SuspR.Stabi =

value value

Stabilizer “spring” c Stabi rate (see (EQ 11)). •

alt

∗

In literature often a reciprocal compression with x = x r = x l is used for definition of c Stabi . This definition deviates to the definition of x∗ in (EQ 9): x∗ x∗ = ------ . 2

alt

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(EQ 13)

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Suspension Roll Stabilizer / Anti-Roll Bar alt

Stabilizer constants cStabi determined by this alternative definition have to be converted to the CarMaker definition of c Stabi : alt

cStabi c Stabi = -------------2 •

(EQ 14)

Depending on the definition of x∗ (length difference (EQ 9) or angle difference (EQ 10)) the unit of c Stabi changes to: x∗ defined as

unit of c Stabi

length difference (EQ 9)

N⁄m

angle difference (EQ 10)

N ⁄ rad

Example

SuspF.Stabi.c = 15000.0

In this case the unit is N ⁄ m .

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Overview

Chapter 5

Suspension Kinematics and Compliance

5.1

Overview Kinematics describes the spacial movements of a wheel due to compression and steer action. Two cases of kinematics are distinguished: •

Suspension kinematics (due to pure wheel compression).

•

Steering kinematics (due to pure steer actions).

In reality a superposition of those two isolated cases exists. Compliance describes the spacial movements of a wheel due to wheel forces which cause elastic deformations of the wheel suspension. Because of the complex construction of a vehicle suspension forces and torques can produce movements of the wheel in other directions than in their effective direction. Movements are described through coordinates in a axis system. The center of this axis system is the wheel center. Coordinates for translations and rotations of this axis system are used.

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Overview

Primary and Secondary Coordinates of the Suspension

kinematics primary coordinates

compliance

secondary coordinates

external forces

•

Wheel compression

•

Toe angle

•

Side force

•

Steering

•

Camber angle

•

Longitudinal force

•

Spin angle

•

Aligning torque

•

Wheel track

•

Camber torque

•

Wheel base

•

Spin torque

•

Wheel compression

Figure 5.1: Kinematics and Compliance

Figure 5.1 shows the context of kinematics and compliance. Wheel compression and steer actions are called primary coordinates of a wheel. A change in the primary coordinates has an effect on the secondary coordinates. Kinematics is defined as force free movements of the wheel suspension and is measured as a function of the primary coordinates. Contrary to the kinematics the compliance investigates in change of secondary coordinates as a result of external forces act upon the wheel. External forces (and torques) can arise from the wheel contact point the brakes and the power transmission. They are transferred to the wheel carrier. These forces yield to changes of the secondary coordinates of the wheel because of elasticities of the suspension. To describe the position of the wheel usually terms from the vehicle dynamics vernacular are used (like in the middle section of Figure 5.1). For parametrization of wheel suspensions CarMaker uses more general, simulation technical terms. The spacial movements of a wheel carrier in CarMaker is equal to the movements of the wheel carrier axis system Fr2 (see section 2.2 ’CarMaker Axis Systems’). The following figures explain the relations of the different viewpoints and their conversions:

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Toe Angle / Rotation r z : positive toe angle

+

+ –rz

+r z driving direction

+

x rz

y left wheel

right wheel

top view

Figure 5.2: Definition of the tow angle and rotation r z

A positive toe angle at the right wheel carrier equals a positive rotation r z of the Fr2 axis system. Camber Angle / Rotation r x : negative camber angle

-

-

rear view

+r x

–rx

+

z rx

y left wheel

right wheel

Figure 5.3: Definition of camber angle and rotation r x

A positive camber angle at the right wheel carrier equals a positive rotation r x of the Fr2 axis system.

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Overview

Spin Angle / Rotation r y : positive spin angle

+

+r y

z ry

x

driving direction Figure 5.4: Definition of spin angle rotation r y

A positive spin angle equals a positive rotation r y of the Fr2 axis system. Translation t y :

z

+ y +t y left wheel

ty

–ty right wheel

Figure 5.5: Definition of wheel track and translation t y :

The translations t y of left and right wheel are parametrized independently. The change of wheel track is a result of both, the change of the left and the right wheel.

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Overview

Translation t x :

driving direction

z

+ x

wheel base

tx

–tx

+t x front wheel

back wheel

Figure 5.6: Definition of wheel base and translation t x

The translations t x of front and back wheel are parametrized independently. The change of wheel base is a result of both, the change of the front and the back wheel. Wheel compression / Translation t z :

z

+ positive compression

tz

y negative compression

Figure 5.7: Definition of wheel compression and translation t z

Positive wheel compression is defined in upward direction. Usually translation t z = 0 equals the wheel position in vehicles design configuration.

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Overview

5.1.1

Describing Kinematics with Generalized Coordinates CarMaker uses generalized coordinates to describe kinematic movements. Basically generalized coordinates q i are independent coordinates to describe a system with i degrees of freedom. i = 6N – k N k

(EQ 15)

number of bodies number of holonomic constraints

Requirements for generalized coordinates are: •

All states of a system can be described with one set of generalized coordinates respecting all holonomic constraints.

•

No holonomic constraints exist for generalized coordinates.

The last statement especially means that one coordinate can have any value without affecting the value of another coordinate.

Applied to the kinematics e. g. of a front axle this means that usually two generalized coordinates exist to describe the kinematic movements of this axle. This is already implied in Figure 5.1 as: •

A generalized coordinate q 0 to describe the degree of freedom for wheel compression.

•

A generalized coordinate q 1 to describe the degree of freedom for the steer influence.

CarMaker gives no restrictions for the choice of the generalized coordinates q 0, q 1 . In other words the user is responsible to choose generalized coordinates that fulfil the requirements mentioned above.

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Conceptual Overview of Kinematics Calculation This section describes the internal procedure how CarMaker calculates kinematic movements with the user defined kinematic characteristics.

q 0, q˙ 0

q 1, q˙ 1

parameters for suspension kinematics determine values from given kinematics characteristics for q 0, q 1 transl.: p = x, y, z rot. angles: ϕ 1, ϕ 2, ϕ 3 comp. length: x Spring, x Damp, x Buf, x Stabi

joint definition (“Free ZXY”) transform rotation angles ϕ 1, ϕ 2, ϕ 3 to transformation matrix A with specified rotation sequence.

assignation of position / orientation and free direction of motion ∂A ∂p r i = ------t i = ------∂q i ∂q i

calculation of generalized forces ∂x Buf ∂x Stabi ∂x Damp ∂x Spring Q i = t i F Ext + r i T Ext + F Spring ---------------- + F Damp ---------------- + F Buif ------------ + F Stabi -------------∂q i ∂q i ∂q i ∂q i

Solver M ⋅ q˙˙i = Q i + Q i∗ ( q i, q˙ i )

q 0, q˙ 0

q 1, q˙ 1

Figure 5.8: Kinematics calculation

The first box in Figure 5.8 shows the quantities acquired from the user defined characteristics for the given generalized coordinates q 0, q 1 . The vector p represents the three translation offsets and the rotation angles ϕ 1, ϕ 2, ϕ 3 specify three cardan angles. Additionally the component lengths of spring, damper, buffers and stabilizer are acquired. With the second step the cardan angles ϕ 1, ϕ 2, ϕ 3 are transformed by the joint definition to the transformation matrix A . A specific rotation sequence (e. g. ‘ZXY’) is provoked by the joint definition. For calculation of the generalized forces the free directions of motion in directions of q 0, q 1 are needed. This is done with the third step by partial differentiation of p and A . In the fourth step for each generalized coordinate a generalized force is computed. External forces and torques are respected in direction of the free direction of motion t i and r i for each coordinate. External forces and torques result from tires, brakes, gravity, etc. Also the internal forces of spring, damper, buffers and stabilizers are respected pro rata in the direction of the generalized coordinate.

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As a final step the solver computes and integrates the generalized accelerations q˙˙0, q˙˙1 . Beside the generalized forces Q i pseudo forces Q i∗ resulting from coriolis forces are taken into account. These pseudo forces Q i∗ depend form q i, q˙ i instead from q˙˙i .

Choosing Generalized Coordinates After dealing with the basics of kinematics definitions in CarMaker this section tries to give practical hints about how to choose appropriate generalized coordinates. Front Axle

For a front axle a generalized coordinate q 0 is needed to describe the degree of freedom for wheel compression and a generalized coordinate q 1 is needed to describe the degree of freedom for the steer influence. A good recommendation is: Generalized Coordinate

Description

q0

Wheel compression t z, 0 for steer angle zero (driving direction straight forward usually equals to q 1 = 0 ).

q1

The rack displacement.

The reason why q 0 is chosen as t z, 0 for steer angle zero is based on the fact that the steer influence changes the compression of the two controlled wheels. This effect is called selfalignment due to lift of the suspension subframe. Such a definition for q 0 is necessary because of the self-alignment the wheel compression t z depends from both coordinates q 0 and q 1 . With the definition above the requirements for generalized coordinates are fulfilled. Both coordinates are independent. Rear Axle

Two cases are distinguished for a rear axle: •

Dependent rear axle: The orientation of one wheel also depends on the compression of the other wheel (e. g. twist-beam rear axle). Good choice:

Generalized Coordinate

Description

q0

Wheel compression t z .

q1

Wheel compression t∗ z of the opposite wheel.

•

Independent rear axle: The orientation of one wheel only depends on the compression of this wheel. (e. g. independent rear suspension). Good choice:

Generalized Coordinate

Description

q0

Wheel compression t z .

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Overview

5.1.2

Brief Introduction to the Measurement Procedure of K&C parameters In practice often K&C test rigs or likewise simulations are used to measure the required K&C parameters. This chapter gives a brief introduction how to measure a vehicle to obtain data that suits to the CarMaker K&C data files. The following table shows terms and abbreviations used to describe the measurement procedure. Name

Definition

Reference System

As reference system a axis system similar to the CarMaker Fr0 axis system is used (See section 1.2). The Vehicle is symmetrically aligned, nose pointing to increasing values of the X-axis.

Static Equilibrium Means equilibrium position of the (empty) vehicle on even Configuration (SEC) ground. The body is not fixed relative to the reference frame. The suspension travel must be symmetrical (left/right). The SEC compression can be measured. Wheel Travel

Translation of wheel center in Z-direction.

Compression Travel

Travel from SEC to max. compression (wheel carrier near to body) = up to metal-to metal position, in general

Rebound Travel

Travel from SEC to max. decompression (wheel carrier far away from body)

Wheel Load (Fz)

Vertical force acting from environment onto wheel carrier, positive if directed upwards. Forces are applied (point of attack) to the wheel center or the tyre/road contact point (=tire patch). The point of attack must be documented.

SWA

Steering wheel angle

Deflection Procedure (DP)

The expression deflection procedure is used synonymously for the following test sequence:

Wheel Replacement System

CarMaker Reference Manual

•

Start from SEC.

•

Slowly increase Fz (= compress suspension) up to wheel load max. value (e.g. 10000 N) = compression travel.

•

Slowly decrease Fz (=decompress suspension, rebound) up to wheel load min value (e.g. 100 N) = rebound travel.

•

Go back to SEC.

•

Compression and rebound speed should be slow and identical in both direction (thereby eliminating velocity depended effects)

•

Front axle: Keep steering rack fixed (eliminate them, if possible effects coming from steering compliance, steering backlash, ...).

•

No horizontal (Fx, Fy) force (ground to tyre) is transmitted.

•

No torque (Mx, My, Mz) (ground to tyre) is transmitted.

•

Wheels are rigidly fixed to wheel carrier (braking conditions).

Set of artificial wheels replacing real wheels during measurements. Advantage: Higher forces (Fy, Fz) during elastokinematic measurements (no slip). More exact, in general Measurements are therefore preferably done with wheel replacement system

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The following lists describes two procedures to be accomplished to acquire the required data for the CarMaker K&C characteristics: Kinematics measurement procedure

Elastokinematics measurement procedure (front & rear)

•

Find static equilibrium configuration (SEC)

•

Determine absolute kinematic quantities (i.e. relative to Fr0) in SEC.

•

Rigidly fix vehicle body in SEC relative to Fr0. Vehicle body remains clamped and restrained during K&C measurements.

•

For Front axles: -

Do DP (left & right symmetrical) keeping steering rack fixed, SWA = 0 (straightforward driving)

-

Do DP (left & right asymmetrical), 50mm compression and rebound are sufficient, SWA = 0 (straightforward driving)

-

Do DP (left & right symmetrical) while changing SWA = min value, -200, -100, -60, 40, -20, -10, 0, 10, 20, 40, 60, 100, 200, max value [deg]. In order to increase the model quality: A finer SWA-graduation is possible/useful.

-

Determine steering reduction ratio: Fix (relative to Fr0) Wheel Carrier in SEC. Starting from min value, increase SWA in steps of 5[deg] (around zero position) and 10 [deg] (for steering wheel angles > 30[deg]) up to max. value (lock to lock steering). Measure kinematic quantities.

•

For independent rear axles: Do DP (left & right symmetrical)

•

For Twist-beam rear axles (dependent rear axle): -

Fix rear right wheel carrier relative to Fr0 in SEC, do DP with rear-left wheel carrier

-

Increase (up to max. compression) in steps of 5-25mm rear right wheel carrier and fix it (relative to Fr0), do DP with rear left wheel carrier

-

Decrease (up to max rebound) in steps of 5-25 mm rear right wheel carrier and fix it (relative to Fr0), do DP with rear left wheel carrier

•

Fix vehicle body in SEC.

•

Block wheels (wheel carrier rigidly fixed to wheel)

•

Longitudinal compliance (longitudinal acceleration and Braking compliance)

•

•

-

Apply horizontal forces Fx = -6000N, - 5000N, -4000N, ... , 0N, 1000 N, .... , 6000 N at front left and rear left wheel

-

Measure kinematic quantities

-

Forces are applied at wheel center or at ground-tyre contact point. The specific case must be documented

Lateral compliance: -

Apply horizontal forces Fy = -6000N, - 5000N, -4000N, ... , 0N, 1000 N, .... , 6000 N at front left and rear left wheel

-

Measure kinematic quantities

-

Forces are applied at wheel center or at ground/tyre contact point. The specific case must be documented

Aligning torque compliance -

Apply vertical torque Mz = -200 Nm, -100 Nm, 0Nm, 100 Nm, 200 Nm at front left and rear left wheel

-

Measure kinematic quantities

-

Torque is applied at wheel center or at ground/tyre contact point. The specific case must be documented

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Kinematics and Compliance

5.2

Kinematics and Compliance The suspension is connected to the vehicle body by a translational and rotational kinematic joint (rotation sequence: Z–X–Y ).

∑

∑

t = K in ( q 0, q 1 ) + Com ( q 0, q 1, F, … ) r i j

(EQ 16)

The suspension kinematics and compliance can be defined by a number of models or parameter sets, which are calculated in the order of there definition. An additional outward shift of the wheel can be defined in the tire parameter set, see section 10.2 ’General Tire Parameters’. Parameters

The following parameters are required for suspension kinematics and suspension compliance: All model parameters have a prefix, depending on the corresponding suspension and the number of the model definition. The prefix can be an empty string or a string, ending with a dot ("SuspF.", "SuspF.Kin.3." for kinematics, "SuspR.Com.2." for compliance).

SuspKey.KnC.N =

N

The kinematics or compliance definition consists of N superimposed models, see (EQ 16). The suspension is selected by SuspKey which can be SuspF or SuspR. The string KnC is Kin for kinematics or Com for compliance. It is an optional entry, the default is 1.

SuspKey.KnC.i.FName = SuspKey.KnC.i.Kind =

FileName or ModelKind

The i-th model is selected by the Kind entry ModelKind. Instead of using the Kind key, an external parameter set can be referenced by filename FileName. The reference to an external parmeter set is supported only on toplevel and in case of only one model at toplevel, not in a parameter set referenced iself. FileName is the path relative to the suspension kinematics directory.

SuspKey.KnC.i.ValidSide =

ValidSide

The i-th model is valid for ValidSide. If suspension side and ValidSide doesn’t match, this model is skipped for this suspension side. ValidSide is exactly one of left, left+right and right. It’s an optional entry, the default is left+right.

SuspKey.KnC.i.InputSide =

InputSide

The i-th model is defined by parameters for the suspension on side ValidSide.

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Kinematics and Compliance

The model parameters for the actual suspension side has to be deduced from the input parameters for side InputSide. InputSide is exactly one of left, left+right and right. It is an optional entry, the default is left.

SuspKey.KnC.i.L.param = SuspKey.KnC.i.R.param =

... ...

Parameters for the left suspension starts with “L.”, for the right with “R.”.

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Kinematics Models

5.3

Kinematics Models All model parameters have a prefix, depending on the corresponding suspension and the number of the model definition. The prefix can be an empty string or a string, ending with a dot ("SuspF.", "SuspF.Kin.3." for kinematics, "SuspR.Com.2." for compliance).

5.3.1 Description

“Linear” and “Linear2D” Linear kinematics uses linear equations to describe the kinematic movements for translations and rotations of the wheel (-carrier). Depending on the number of generalized coordinates the model ‘Linear’ is used for one or the model ‘Linear2D’ is used for two generalized coordinates.

a

dk 1 dq 1 c Off

dk c 1 = -------1dq 1

q 0, q 1 dk 0 dq 0

dk c 0 = -------0dq 0

Figure 5.9: Kinematics ‘linear2D’ for coordinates q 0, q 1

This means (steered) front axles use the model ‘Linear2D’ because they have two degrees of freedom which influence the kinematics of the wheel carrier. Independent rear suspensions use the model ’Linear’ because the kinematics only depends on the wheel compression of the considered wheel carrier. For instance, for a twist beam rear axle, where kinematics also depends on the compression of the opposite wheel carrier, the model ‘Linear2D’ has to be used. A simple linear equation is used for each coordinate. a ( q 0 ) = c Off + c 0 ⋅ q 0

(EQ 17)

The model ‘Linear2D’ uses a superposition of two linear equations one for each generalized coordinate. a ( q 0, q 1 ) = c Off + c 0 ⋅ q 0 + c 1 ⋅ q 1

(EQ 18)

with: a

c Off

CarMaker Reference Manual

one of 3 translations ( t x, t y, t z ) in frame Fr1 or 3 cardan rotation angles ( r x, r y, r z ) with a rotation sequence Z–X–Y or 4 component lengths ( l Spring, l Damp, l Buf, l Stabi ) offset for q 0, q 1 = 0

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c0 c1

Parameters

gradient depending on compression q 0 gradient depending on compression or steering coordinate q 1

The following parameters are required for this model. The asterix “*“ is an abbreviation for the suspension, for kinematics or compliance, for the model number and the paramter side, see section 5.2 ’Kinematics and Compliance’ on page 70. All Kinematics parameters are optional. This means CarMaker will not complain about missing parameters. Due to the fact that all defaults are zero CarMaker probably will complain about a non functional vehicle.

*.tx = *.ty = *.tz =

tx0 ty0 tz0

dtx/dq0 dty/dq0 dtz/dq0

dtx/dq1 dty/dq1 dtz/dq1

Optional. Wheel (-carrier) translations. Translation is calculated by the offset and two racios dependending on the generalized coordinates of the suspensions (see (EQ 17)). Defaults: 0 0 0 and for tz 0 1 0. Units: m m/q0 m/q1.

*.rx = *.ry = *.rz =

rx0 ry0 rz0

drx/dq0 dry/dq0 drz/dq0

drx/dq1 dry/dq1 drz/dq1

Wheel (-carrier) rotations. Rotation depends on the generalized coordinates of the suspension (see (EQ 17)). Defaults: 0 0 0. Units: rad rad/q0 rad/q1.

*.lSpring = *.lDamp = *.lBuf = *.lStabi =

lSpring0 lDamp0 lBuf0 lStabi0

dlSpring/dq0 dlDamp/dq0 dlBuf/dq0 dlStabi/dq0

dlSpring/dq1 dlDamp/dq1 dlBuf/dq1 dlStabi/dq1

Deflection or length of the force elements spring, damper, buffer and roll stabilizer depending on generalized coordinates. Remark: For the roll stabilizer the units of this coordinate and the units of the roll stiffness has to fit together. Defaults: 0 -1 0. Units: m m/q0 m/q0.

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Kinematics Models

5.3.2 Description

“MapNL” Nonlinear 1-dimensional (1D) or 2-dimensional (2D) mapping, depending on suspension DOFs.

t = c self ( q0 ) r self

t = c self ( q0, q1 ) r self

or

(EQ 19)

High fidelity K&C uses lookup-tables to describe the spacial movements of the wheel. This implies huge amounts of data for each degree of freedom. Location and Activation

The K&C parameter files are stored under /Data/Chassis. The high fidelity K&C Parameters are activated in the vehicle file (see section 5.1 ’Overview’.

Units

All quantities, if not explicitly mentioned otherwise are SI-Units. Particularly the following quantities are used in the K&C parameter files. Table 5.1: SI Units used with CarMaker High Fidelity K&C Parameters

Table Concept

Parameters

Quantity

Name

Symbol

Time

second

s

Length

meter

m

Angle

radian (one turn = 2*π)

rad

Mass

kilogram

kg

Force

newton

N

Torque

newton meter

Nm

Stiffness

newton per meter

N/m

Rotational Stiffness

newton meter per radian

Nm/rad

The characteristics for high fidelity kinematics are stored in a specific indexed table format. Characteristics can be one or two dimensional depending on the number of generalized quantities. The vectors Arg 0 ) and vector Arg 1 ) hold the values of all sample points for the following two dimensional lookup table. Which values are given for each sample point is specified in a list. The following parameters are required for this model:

*.Arg =

NameDoF0

[ NameDoF1 ]

Define the dimension of kinematics mapping, one keyword for 1D, two names for 2D. The first name NameDoF0 can be “comp”. The second name NameDoF0 can be an empty string (for 1D), “comp” or “steer”.

*.Arg0 = *.Arg0.Fac2SI =

min ... max Fac2SI

Values of first kinematics degree of freedom (DOF). All values are multiplied with Fac2SI. Default is Fac2SI=1.0.

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*.Arg1 = *.Arg1.Fac2SI =

min ... max Fac2SI

Values of second kinematics degree of freedom. All values are multiplied with Fac2SI. Default is Fac2SI=1.0.

*.Data.Name =

DataNameList

List of suspension coordinates to be modified by compliance effects. The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz, lSpring, lDamp, lBuf, lStabi. Unknown keys are skipped and the values from the corresponding column in the data table are ignored. Typically unknown or commented out keys should start with a "%" charscter.

*.Data.Offset = *.Data.dArg0 = *.Data.dArg1 = *.Data.Fac2SI =

OffsetList dData_dArg0_List dData_dArg1_List Fac2SI_List

Each data coordinate can have an offset, one or two linear gradients depending on the number of DOFs. All values are multiplied with their factor Fac2SI from Fac2SI_List. The calculation of a suspension coordinate is done by the formula:

dData dData value = Data + Offset + ----------------- ⋅ Arg0 + ----------------- ⋅ Arg1 dArg1 dArg0

*.Data:

(EQ 20)

TableWithValues

Values for the selected coordinates from DataNameList. Ordering: Each line contains the number of values, which are defined in DataNameList. The first DOF is kept constant, the second is varied first. Example: The compression is kept constant while steering is varied. Than the same for the next compression and so on.

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5.3.3 Description

“SetZero” Model to suppress previous displacements for selected quantities

t = 0 r Parameters

(EQ 21)

The following parameters are required for this model:

*.Data.Name =

DataNameList

The suspension displacements by kinematics effects of the selected quantities are set to zero. The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz, lSpring, lDamp, lBuf, lStabi.

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Compliance Models

5.4

Compliance Models All model parameters have a prefix, depending on the corresponding suspension and the number of the model definition. The prefix can be an empty string or a string, ending with a dot ("SuspF.", "SuspF.Kin.3." for kinematics, "SuspR.Com.2." for compliance).

5.4.1 Description

“CoeffConstFr1” and “CoeffConstFr2” The compliance displacement is based on a linear, constant coefficients for the forces, attacking the actual and the opposite suspension. In model “CoeffConstFr1” the forces are decomposed in frame Fr1. In model “CoeffConstFr2” the forces are decomposed in frame Fr2. The model “CoeffConst” is for compatibility to CarMaker 2.0 only. It will be removed soon! The frame in which the compliance forces are decomposed depends on a global configuration parameter Car.SuspElastoKin_FrcTrqFr1 in SimParameters. The default is frame Fr2. Changes relative to CarMaker 2.0: Parameter are now component orientated. This means displacement for this suspension based on forces attacking the suspension itself, opposit or elsewhere. In CarMaker 2.0 the parameters are force orientated.

´

Parameters

t = c W ⋅ W self + c W ⋅ W opp self opp r self

(EQ 22)

The following parameters are required for this model:

*.Data.Name =

DataNameList

The suspension displacements by compliance effects of the selected quantities. The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz. Remark: Usually it is meaningful to leave out forces in z direction and tz movements.

*.Frc.x = *.Frc.y = *.Frc.z = *.FrcOpp.x = *.FrcOpp.y = *.FrcOpp.z =

Values Values Values Values Values Values

Compliance coefficients depending on forces (along x, y, z axis) to the actual (*.Frc.*) or the opposite (*.FrcOpp.*) suspension. Point of attack is the wheel center.

*.Frc.Fac2SI = *.Trq.Fac2SI =

Fac2SI_List Fac2SI_List

All coefficients are multiplied by the factors from Fac2SI_List, from *.Frc.Fac2SI for forces and from *.Trq.Fac2SI for torques.

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Compliance Models

*.Trq.x = *.Trq.y = *.Trq.z = *.TrqOpp.x = *.TrqOpp.y = *.TrqOpp.z =

Values Values Values Values Values Values

Compliance coefficients depending on torques (arround x, y, z axis) to the actual (*.Frc.*) or the opposite (*.FrcOpp.*) suspension. The torques each are reduced to the wheel center.

*.FrcDamp = *.FrcOppDamp =

Values Values

Compliance coefficients depending on the damper force to the actual (*.Frc.*) or the opposite (*.FrcOpp.*) suspension.

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5.4.2 Description

“SetZero” Model to suppress previous displacements for selected quantities

t = 0 r self Parameters

(EQ 23)

The following parameters are required for this model:

*.Data.Names =

DataNamesList

The suspension displacements by compliance effects of the selected quantities are set to zero. The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz, lSpring, lDamp, lBuf, lStabi. Unknown keys are skipped and the values from the corresponding column in the data table are ignored. Typically unknown or commented out keys should start with a "%" charscter.

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5.4.3 Description

“CoeffLin1DFr1” and “CoeffLin1DFr2” The compliance displacement is based on a linear, compression depending coefficients for the forces, attacking the actual and the opposite suspension. In model “CoeffLin1DFr1” the forces are decomposed in frame Fr1. In model “CoeffLin1DFr2” the forces are decomposed in frame Fr2.

Parameters

The following parameters are required for this model:

*.Arg0 = *.Arg0.Fac2SI =

min ... max Fac2SI

Values of first degree of freedom (DOF), suspension compression. All values are multiplied with Fac2SI. Default is Fac2SI = 1.0.

*.Data.Name = DataNameList The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz, lSpring, lDamp, lBuf, lStabi. Unknown keys are skipped and the values from the corresponding column in the data table are ignored. Unknown or commented out keys typically should start with a "%" charscter.

*.Frc.Fac2SI = *.Trq.Fac2SI =

Fac2SI_List Fac2SI_List

All coefficients are multiplied by the factors from Fac2SI_List, from *.Frc.Fac2SI for forces and from *.Trq.Fac2SI for torques.

*.Frc.x.Data : *.Frc.y.Data : *.Frc.z.Data : *.Trq.x.Data : *.Trq.y.Data : *.Trq.z.Data :

TableWithValues TableWithValues TableWithValues TableWithValues TableWithValues TableWithValues

Compliance coefficients for the selected coordinates from DataNameList depending on forces (along x, y, z axis) or torques (arround x, y, z axis) to the actual suspension. Point of attack is the wheel center. The table starts with values for the first element of Arg0 end ends with values for the last one.

*.FrcDamp.Data :

TableWithValues

Compliance coefficients depending on the damper force to the actual (*.Frc.*) suspension.

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5.4.4 Description

“DisplaceLinFr1” and “DisplaceLinFr2” The compliance displacement is described by displacement maps. The displacement maps depends on the forces, attacking the actual suspension. In model “DisplaceLinFr1” the forces are decomposed in frame Fr1. In model “DisplaceLinFr2” the forces are decomposed in frame Fr2.

Parameters

The following parameters are required for this model:

*.Arg = ArgName The quantity, the displacement relationship depends on, is selected by ArgName. Known keys are Frc.x, Frc.y, Frc.z, Trq.x, Trq.y, Trq,z, FrcDamp. The forces (along x, y, z axis) or torques (arround x, y, z axis) attacks the actual suspension in the wheel center.

*.Arg0 = *.Arg0.Fac2SI =

min ... max Fac2SI

Values of the function argument. All values are multiplied with Fac2SI. Default is Fac2SI=1.0.

*.Data.Name =

DataNameList

The quantities are selected by the blank seperated list DataNameList of the keys tx, ty, tz, rx, ry, rz, lSpring, lDamp, lBuf, lStabi. Unknown keys are skipped and the values from the corresponding column in the data table are ignored. Typically unknown or commented out keys should start with a "%" character.

*.Data :

TableWithValues

displacement values for the coordinates from DataNameList. The table starts with values for the first element of Arg0 end ends with values for the last one.

*.Data.Fac2SI =

Fac2SI_List

All data columns are multiplied by the factors from Fac2SI_List.

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Example

This parameter set is for the front axle and for the left suspension only. The compliance depends on Frc.x, given in unit "kN". It defines compliance effects for suspension coordinates ty and rz, both given in SI units. SuspF.Com.0.Kind = SuspF.Com.0.ValidSide = SuspF.Com.0.InputSide = SuspF.Com.0.L.Arg = SuspF.Com.0.L.Arg0 = SuspF.Com.0.L.Arg0.Fac2SI = SuspF.Com.0.L.Data.Name = SuspF.Com.0.L.Data.Fac2SI = SuspF.Com.0.L.Data: 0.000 0.000 0.001 0.006 0.002 0.011 0.004 0.015 0.008 0.018 0.016 0.020 0.032 0.021 0.032 0.021

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"DisplaceLinFr1" left left Frc.x 0.0 1.0 2.0 3.0 4.0 4.5 4.6 4.7 1.0e3 ty rz 1.0 1.32456

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5.4.5

Example: Compliance SuspF.Com.N = 5 #--- "basic" compliance parameters by Model 0 SuspF.Com.0.Kind = CoeffconstFr1 SuspF.Com.0.ValidSide =left+right SuspF.Com.0.InputSide =left SuspF.Com.0.L.Data.Name =tx ty tz ry SuspF.Com.0..... #--- "extended", detailed parameters by Models 1, 2, ... # parametrisation for right suspension based on parameters for # a left suspension. Left parameters are "transfered" to right. # SuspF.Com.1.Kind = DisplaceLinFr1 SuspF.Com.1.ValidSide =left+right # Model 1 is used for left and right SuspF.Com.1.InputSide =left # parameters are given only for left # right by projection left->right SuspF.Com.1.L.Arg = Frc.x SuspF.Com.1.L.....

SuspF.Com.2.Kind = SuspF.Com.2.ValidSide SuspF.Com.2.InputSide SuspF.Com.2.L.Arg = SuspF.Com.2.L.....

DisplaceLinFr1 =left =left Frc.y

SuspF.Com.3.Kind = SuspF.Com.3.ValidSide SuspF.Com.3.InputSide SuspF.Com.3.R.Arg = SuspF.Com.3.R.....

DisplaceLinFr1 =right =right Frc.y

SuspF.Com.4.Kind = SuspF.Com.4.ValidSide SuspF.Com.4.InputSide SuspF.Com.4.L.Arg = SuspF.Com.4.L..... SuspF.Com.4.R.Arg = SuspF.Com.4.R.....

DisplaceLinFr1 =left+right =left+right Trq.z

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Overview

Chapter 6

Aerodynamics

6.1

Overview CarMaker takes into account forces and torques due to external wind loads. All data is conform with the SAE norm J1594.

L

L

RM z

PM S

b/2

y

x

D

z

b

l/2 l

y S YM

VF VS

τ

x

D

V∞

Figure 6.1: CarMaker aerodynamics axis system based on SAE J1594

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Overview

According to this norm the SAE Road Vehicle Aerodynamics commission defined the following frame (SAE-frame): •

X: positive forward

•

Y: positive right

•

Z: positive downward

•

The origin of the SAE-frame usually in the wheel contact plane at the intersection point of the symmetry lines of track base and wheel base (in design configuration).

Aerodynamic forces and torques depend on: •

Relative wind speed between wind and vehicle ( V ∞ ).

•

Angle of attack of wind τ ( τ is given in degrees) -

τ = 0, if the wind is coming from front

-

τ > 0, if the wind is slightly coming from front left.

CarMaker incorporates wind loads as 3 forces and 3 torques on the vehicle body: ρ 2 F D = – F x = --- c D Av ∞ 2

ρ 2 F S = F y = --- c Av ∞ 2 S

ρ 2 F L = – F z = --- c Av ∞ 2 L

(EQ 24)

with drag force (positive rearward) drag coefficient (no dimension) side force (positive to right) side force coefficient (no dimension) lift force (positive upward) lift coefficient (no dimension) ambient air density vehicle reference area relative wind speed

FD cD FS cS FL cL ρ A v∞

ρ 2 M RM = M x = --- c lAv ∞ 2 RM

ρ 2 M PM = M y = --- c lAv ∞ 2 PM

ρ 2 M YM = M z = --- c lAv ∞ 2 YM

(EQ 25)

with M RM c RM M PM c PM M YM c YM l ρ A v∞

CarMaker Reference Manual

rolling moment (positive right side down) rolling coefficient (no dimension) pitching moment (positive nose up) pitching coefficient (no dimension) yawing moment (positive nose right) yawing coefficient (no dimension) wheel base used as reference length ambient air density vehicle reference area relative wind speed

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General Parameters

6.2

General Parameters The air density is a global parameter and not specified in this section.

AeroMarker.pos =

x

y

z

This coordinate specified in FrD axis system (see section 1.2 ’CarMaker Axis Systems’) determines the impact of external wind loads. This means when this virtual point reaches the distance of a wind machine the wind takes effect.

Aero.Kind =

KindStr

This parameter specifies the aerodynamic calculation model. Example

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Aero.Kind = Coeff6x1

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Models

6.3

Models

6.3.1

‘Coeff6x1’

Aero.pos =

x

y

z

Specifies the position of origin of the SAE-frame expressed in the FrD axis system (see section 1.2 ’CarMaker Axis Systems’).

Aero.Ax =

Area

The vehicle reference area Area [m^2] is the projected frontal area including tires and underbody parts.

TableWithValues

Aero.Coeff :

this characteristic specifies the 3 force coefficients (EQ 24) and the 3 torque coefficients (EQ 25) depending on the angle of attack of the wind τ (given in degrees!). The tau-mapping should cover the whole field of angles, ranging from tau = -180 [deg] to tau = +180 [deg].. Syntax

Example

Table mapping with 7 columns c D cS cL

c RM

c PM

c YM

Aero.mapping: -180 -90 0 90 180

0.0 -0.2 0.0 0.2 0.0

-0.01 0.0 -0.03 0.0 -0.01

0.0 0.0 0.0 0.0 0.0

Aero.lReference =

-0.4 0.0 0.2 0.0 -0.4

0.0 -1.7 0.0 1.7 0.0

0.1 0.9 0.1 0.9 0.1

Length

Optional reference length. The default value for cars is the wheel base, for trailers the hitch length.

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Overview

Chapter 7

Steering System

7.1

Overview

Vehicle (Suspension)

Steer Model

Steer Interface

Steer Interface

DrivMan

Driver

The task of a steer system is to define the driver’s “steer influence” to the (front-) suspension. The steering system has an interface that serves two parts. One part is the designated to the driving maneuver module (DrivMan simulates human interactions with the vehicle), the other part interferes to the vehicles suspension module.

Figure 7.1: Interface of the steering system

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Overview

Basically steering systems for CarMaker are distinguished by the type of input (control) signals used. The control signal is the output of the driving maneuver module and is an input requirement of the steer system. Input requirement Description (Steer by...)

Angle

The steering wheel angle is used as input to the steer model. No mass dynamic effects are regarded. This means that the update to new values of steer angles happens infinitely fast (no differential equation).

Torque

Input is the steering torque from the driving maneuver module. A differential equation has to be used to calculate the steering wheel angle. Mass dynamic effects should be regarded by the model. Infinitively fast changes of steering wheel angles are not possible.

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Overview

Steer by Angle q L, q˙ L, ( q˙˙L )

Vehicle Suspension Left

FL mL ( qL )

Steer Model Angle

qL = qR = σH ⋅ iq → σ H ˙q L = q˙ R = σ˙ H ⋅ i q → σ H ˙˙ H ⋅ i q → σ q˙˙L = q˙˙R = σ H T H,S = i σ → q ⋅ ( F L + F R ) H

q R, q˙ R, ( q˙˙R )

FR mR ( qR )

˙˙ H σ H, σ˙ H, σ

T H,S +

Vehicle Suspension Right

7.1.1

+

Figure 7.2: Principal of Steer by Angle Models

Figure 7.2 shows the basic functionality of a steer by angle model. The steering wheel angle σ H and its derivatives are inputs to the steer model. The steering wheel angle is translated to the generalized quantity q = q L = q R . The same way for the derivatives. The translation is defined as follows:

q˙ 1 i q → σ ( σ H ) = ------------------------------- = ------H iσ → q ( σH ) σ˙ H H

(EQ 26)

(EQ 26) clarifies that the translation might depend on the steering wheel angle. Such a variable steer translation is commonly used with modern steer systems. Because there is no differential equation calculated only the static steering wheel torque T H, S is returned by the model. The inputs of the two masses are not regarded by the steer model (they have no effect on the steer system).

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Overview

7.1.2

Steer by Torque q L, q˙ L, ( q˙˙L )

Steer Model Torque

q R, q˙ R, ( q˙˙R )

m ( L, H, R ) ⋅ q˙˙L = F ( L, H, R )

mL ( qL )

m ( R, H, L ) ⋅ q˙˙R = F ( R, H, L ) ˙˙ H = F ( H, L, R ) m ( H , L, R ) ⋅ σ ˙˙ H σ H, σ˙ H, σ

TH +

FR mR ( qR )

Vehicle Suspension Right

Vehicle Suspension Left

FL

+

Figure 7.3: Principal of Steer by Torque Models

A steer by torque model is characterized by the input of the steering wheel torque to the steer model and that the steer angle and velocity and acceleration is returned by the steer model. In this case differential equations as depicted in Figure 7.2 have to be calculated. If a stiff rack steering system is modeled the generalized steer coordinates reduce to one q Steer = q L = q R . Then the differential equations can be written as ( m L + m R + m H ) ⋅ q˙˙Steer = F L + F R + F H .

(EQ 27)

The acceleration of the steering wheel is determined from ˙˙ H = i q → σH ⋅ q Steer . σ

(EQ 28)

This simple approach of steer by torque model can be extended by detailed models with steering boosters or with extra functionality like active steering mechanisms.

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Steering System Parameters

7.2

Steering System Parameters

7.2.1

General Steering System Parameters

Steering.Kind =

KindStr

Specify the steering model to be used. The CarMaker steering model library provides the following models: Steering.Kind

Description

Classic

Standard steer by angle model.

Example

7.2.2

Steering.Kind = Classic

Steering System ’Classic’ Parameters The standard steering system of CarMaker is of the kind steer by angle (see section 7.1.1).

tie rods

Suspension Left

Suspension Right

q = qL = qR

σH

rack

+

iσ → q ( σH ) H

Figure 7.5: Steer system classic

This model simulates a simple rack steering system. The whole steering system is assumed to be stiff. The generalized coordinates on the left and the right side are equal q Steer = q L = q R . The rack position ( q Steer ) is calculated with the steering gear ratio: σH q Steer = -------------------------i σH → q ( σ H )

Steering.Rack2StWhl =

(EQ 29)

value

Steering Gear Ratio: StWhlAngle [rad] = Rack2StWhl [rad/m] * RackTranslation [m]. Example

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Steering.Rack2StWhl = 100

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User Accessible Quantities for Steering Systems

7.3

User Accessible Quantities for Steering Systems Please refer to section 12.4 ’User Accessible Quantities: Steering Systems’.

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Steering System Software Interface

7.4

Steering System Software Interface •

Models can be registered to CarMaker with an individual identification string.

•

To select and activate a model, its identification string is must to be specified in the vehicle parameter set.

Inputs to the System •

SteerByAngle/SteerByTorque

•

Steering wheel angle, angle velocity (if the model is steer by angle type)

•

Steering wheel toque (not used by steer by angle models).

•

Suspension forces to tie rod translation (left and right)

•

Suspension inertias to tie rod translation (left and right)

Outputs of the System •

General steer coordinate (tie rod translation) and derivatives (left and right)

•

Steering wheel torque required for static conditions (no accelerations).

•

Steering wheel angle, angle velocity (if the model is steer by torque type)

Interface structure to the steering calculation function typedef struct tSteerIF { tSteerBy SteerBy;/* use position or angle(in) * * as steer input /* double Ang;/* steer angle (in/out)*/ double AngVel; double AngAcc; double Trq;/* steer torque(in) * * acting on steering wheel */ double TrqStatic; /* steer torque, required for * static conditions (no acceleration)*/

(out) *

struct tSteerIFLR { /*** Input Quantities: (Car/Driver to Steering) */ doubleFrc; /* force (external to steer system) */ doubleInert; /* inertia (external to steer system) */ /*** Output Ouantities: (Steering to Car/Driver) double q, qp, qpp;/* tie rod translation

*/ */

double iSteer2q;/* ratio (out) * * steer rotation to rack translation */ } L, R; /* left, right */ } tSteerIF;

Calculation Function int (*Eval) (void *MP, tSteerIF *IF, double dt);

CarMaker Reference Manual

/* Modellparameter /* Interface structure /* time step

*/ */ */

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Overview

Chapter 8

PowerTrain

8.1

Overview The powertrain which acts as a global system within the CarMaker VVE is divided into a number of subsystems with well defined interfaces. In the following the basic concept of the subsystems and interfaces is described.

8.1.1

Interface Powertrain – Vehicle This interface is responsible for the global embedding of the whole powertrain within the CarMaker VVE. As shown in Figure 8.1: the various subsystems can get input signals from ECUs or from other CarMaker modules (e. g. interaction form virtual control elements of the vehicle).

ECU Signals

ECU Signals

ECU Signals

ECU Signals

P o w e r T r a i n Engine

Clutch

Accelerator Pedal Starter activated Ignition on/off

Clutch Pedal

Gearbox

Gear Selector

D r i v M a n

T Support2Vehicle q, q˙ Wheel

T Brake2Wheel T Tire2Wheel

V e h i c l e

The interface of input/output quantities interacting with the Vehicle-Model is very compact. The powertrain is not interchanging many signals.

Figure 8.1: The Powertrain – Vehicle Interface

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Overview

To observe and to drive the vehicle, additional output signals like the engine speed are needed and provided from the corresponding powertrain submodules.

8.1.2

PowerTrain Subsystems The powertrain model determines the distribution of drive torque to the wheels. The powertrain module can be combined with several subsystems. A Powertrain typically consists of the following subsystems: Model

Description

Engine

The ‘‘origin of all motion´´

Clutch

The agent between producer and consumer of driving energy

Gearbox

The converter of drive torque

There are different ways to look at powertrain submodules. One is the structural view how powertrain modules are configured and connected to a complete system. This is shown in Figure 8.2. PowerTrain

PowerTrain ‘Generic’ Model Library GenFront E

GenRear E

C GB

C GB

Gen2p2Front E

Gen2p2Rear

C GB

E

Engine

E1

C GB

Gen4WD E

C GB

Custom Model 1 E

Clutch

E2

C1

Custom

Custom

Custom

Engine 2

Clutch 2

E

C GB

Gearbox

C2

Engine 1

C GB

Custom Model 2

PowerTrain Components Library

Custom

GB1 Custom

Gearbox 1 Gearbox 2

Figure 8.2: PowerTrain structural view

The topmost layer is the selected powertrain model. Here a specific powertrain model is selected which is the central computation unit for the whole powertrain. This means the binding of all components and the interfacing to the Vehicle-Model and the DrivMan-Model is done within this model. The driveline is computed with this central unit. A powertrain library called powertrain ‘Generic’ is provided with CarMaker for the most common used powertrain versions. But there is a possibility to add custom models for special needs to the ones offered from the library. The Powertrain models have interfaces to other components needed to obtain a complete powertrain. There are interfaces to the components Engine, Clutch and Gearbox form the next layer in Figure 8.2. Similar to the Powertrain models a library called PowerTrain Com-

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Overview

ponents Library is included with CarMaker and offers models for each individual component. At this level it is also possible to add custom models to extend the library with components for special needs. As visible in Figure 8.2 the integration of custom models is seamless. As long as the specified interface of each module is regarded custom modules can be mixed with standard modules as desired.

8.1.3

Interfaces of Powertrain Subsystems The standard powertrains provided with the powertrain ‘Generic’ library are modeled as rigid systems with five degrees of freedom. There are four wheels and the engine potentially rotating with different speeds. There has to be a differential equation for each degree of freedom in such a model. In general rotation speeds are calculated by integration of the moment-balance:

∑T

1 q˙˙x = ----------J Pro j˙

(EQ 30)

x

J Proj is the projected inertia of all connected parts reassessed by transmissions. These calculations beside others are done in the Powertrain-Module which acts as a master unit for all other powertrain submodules (see Figure 8.3).

Another way to look at powertrain submodules is concerned with the interfacing between the powertrain modules themselves and the Vehicle-Model. Table 8.1: lists the types of quantities being exchanged between powertrain subsystems and the Vehicle-Model. Table 8.1: Notation

q

rotation angle

q˙

angular velocity

T from → to

torque from system to system

i

transmission

Figure 8.3 shows each powertrain subsystem and describes the required quantities exchanged between the different submodules: ECU Signals

ECU Signals

ECU Signals

T Clutch2Gearbox T Engine Engine

Clutch q, q˙ Engine

q, q˙ Gearbox

Accelerator Pedal Clutch Pedal Starter activated Ignition on/off

ECU Signals

T Support2Vehicle T Gearbox2DL q, q˙ Wheel iGearbox PowertrainGearbox Computation T Brake q, q˙ Driveshaft T Tire

Gear Selector

Figure 8.3: The PowerTrain Module Interfaces

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Overview

Driveline Model The driveline model transfers the torque from the gearbox output to all driven wheels. The calculation of wheel speeds and other rotation speeds is done in the computation part of this master module. ECU Signals

T GearBox2Driveline Driveline

Gearbox q, q˙ Driveshaft

ΣT i

Integration of rotation speeds ˙ q i, q i

T Support2Vehicle q, q˙ Wheel T Brake T Tire

Figure 8.4: Driveline Mode

8.1.4

General Parameters

Location

Parameters for configuring a powertrain are found in the parameter file for a specific vehicle under /Data/Vehicle/ The following parameters are used globally no matter which specific subsystem is selected. They are mandatory for all configurations and therefore listed as global parameters.

PowerTrain.Kind =

KindStr

With this parameter a powertrain model is selected. The powertrain library provides the following models: PowerTrain.Kind

Description

GenFront

standard front drive vehicle

GenRear

standard rear drive vehicle

Gen2p2Front

front driven vehicle with rear axle hanged on

Gen2p2Rear

rear driven vehicle with front axle hanged on

Gen4WD

four wheel drive vehicle

... Example

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PowerTrain.Kind = GenFront PowerTrain.Kind = MyPowertrain

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Powertrain ’Generic’

8.2

Powertrain ’Generic’

8.2.1

Overview This section describes the available powertrain modules provided with the ‘Generic’ library. The models of this library are highly configurable and should meet the needs of the most common configurations.

Supported configurations PowerTrain.Kind

Description

GenFront

standard front drive vehicle

GenRear

standard rear drive vehicle

Gen2p2Front

front driven vehicle with rear axle hanged on

Gen2p2Rear

rear driven vehicle with front axle hanged on

Gen4WD

four wheel drive vehicle

Basically powertrain configurations are distinguished by the number of driven wheels and in addition to this by the number of differential gears used. Figure 8.5 gives an overview of the available configurations:

Front Drive:

GenFront

Gen2p2Front

Rear Drive: Gen4WD GenRear

Gen2p2Rear

Figure 8.5: Configurations overview

The standard front and rear drive configurations use one differential gear to distribute the torque from the drive shaft to the wheels (either at the front or at the rear axle). The 4WD configuration uses one differential gear for every axle and a center differential gear for distributing torque to the front and rear axle. The hanged on configurations also have differential gears for front and rear axle but use a coupling for transferring torque to the hanged on axle. This means that with opened center coupling this configuration acts like a standard front or rear drive.

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Supported coupling configurations In addition to this there are several possibilities to add different types of couplings between different shafts of the differential gears in the drive line: left2right

in2left

in2right

Front:

i

Center:

i

front2rear

in2front

hangon

in2rear

Rear:

left2right

in2left

in2right

Figure 8.6: Configuration possibilities for powertrain couplings

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There are several types of couplings for different purposes available. They can be configured for each individual coupling shown in Figure 8.6: Visco Coupling

As a matter of principle a visco coupling is only able to transfer torque if there is a rotation speed difference between both sides of the coupling. This is because a fluid is used for torque transmission like in a hydrodynamic torque converter (Föttinger-Coupling). This means there is no state where a visco coupling is sticking, there has to be slip for torque transmission. For simulation purposes a torque characteristic as a function of rotating speed difference is used. The coupling torque is calculated by: T = f ( ∆ω˙ )

(EQ 31)

A typical characteristic may look like in Figure 8.7

transferred torque

T

0

∆ω˙

rotation speed difference

Figure 8.7: Typical characteristic for a visco coupling

Torque Sensing Coupling

The coupling torque (locking torque) depends on the torque difference between the two coupled shafts. The torque sensing coupling is only useful for the mount positions left2right and front2rear. Figure 8.8 displays the mount position left2right.

TCage

TLow

THigh

TLock Figure 8.8: Principal torque sensing coupling

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With torque sensing couplings there are two common characteristic values. The torque bias and locking ratio are defined as: T High TB = -----------T Low

(EQ 32)

T Lock LR = -----------T Cage

(EQ 33)

1

If T Lock = 0 then T High = T Low = --- T Cage applies for a standard differential gear. If T Lock 2 exists the torques calculate to: 1 T Low = --- ( T Cage – T Lock ) 2 1 T High = --- ( T Cage + T Lock ) 2

(EQ 34)

With (EQ 32), (EQ 33) and (EQ 34) a relationship between torque bias and locking ratio can be determined: TB – 1 LR = ----------------TB + 1

(EQ 35)

The CarMaker implementation of a torque sensing coupling uses a torque bias value as input for each the driven ( T Cage ≥ 0 ) and undriven ( T Cage < 0 ) case. Locked Coupling

This is not a real coupling. It acts like a rigid connection between input and output shaft. It is useful for simulating a locked differential or testing purposes. No matter which mount position is chosen the differential is lock in either case. There are no parameters needed for this coupling.

DVA Locked

With this coupling the locking torque for the configured couplings can be given via modification of DVA quantities.

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8.2.2

General Parameters

PowerTrain.Kind =

KindStr

With this parameter a powertrain model is selected. The powertrain ‘Generic’ library provides the following models: PowerTrain.Kind

Description

GenFront

standard front drive vehicle

GenRear

standard rear drive vehicle

Gen2p2Front

front driven vehicle with rear axle hanged on

Gen2p2Rear

rear driven vehicle with front axle hanged on

Gen4WD

four wheel drive vehicle

Example

PowerTrain.Kind = GenRear

PowerTrain.ET.Kind = PowerTrain.Clutch.Kind = PowerTrain.GearBox.Kind =

ETKindStr ClutchKindStr GearBoxKindStr

Selecting powertrain ’Generic’ sub models, see section 8.3 ’Engine Torque’ on page 110, see section 8.4 ’Clutch’ on page 120 and see section 8.5 ’Gear Box’ on page 128.

Inertias

PowerTrain.Engine.I =

value

PowerTrain.Clutch.I_in =

value

All parts of the clutch which should be added up to the engine mass substitute.

PowerTrain.Clutch.I_out =

value

All parts of the clutch which should be added up to the wheel mass substitute if the transmission is in gear.

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PowerTrain.GearBox.I_in =

value

All parts of the gearbox which are not added up to the wheel mass substitute. Measured when transmission is in neutral.

PowerTrain.GearBox.I_out = value All parts of the gearbox which are added up to the wheel mass substitute. Measured when transmission is in neutral.

PowerTrain.DriveLine.I_in =

value

Inertia of the rotating diveline elements like shafts and joints.

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8.2.3

Model ‘Generic’ Differential Parameters Differential Models ‘Front’ or ‘Rear’ Depending on the powertrain configuration a differential gear is used either for front or rear or both axles. ‘F’ means front, ‘R’ means rear.

PowerTrain.DL.FDiff.I_in = PowerTrain.DL.RDiff.I_in =

value value

Inertia of the input shaft

PowerTrain.DL.FDiff.I_out = PowerTrain.DL.RDiff.I_out =

value value

Inertia of the output shaft

PowerTrain.DL.FDiff.I_Cage = value PowerTrain.DL.RDiff.I_Cage = value Optional. Inertia of the differential cage. Default: 0

PowerTrain.DL.FDiff.i = PowerTrain.DL.RDiff.i =

value value

Transmission ratio from input shaft to cage. Example

PowerTrain.DL.FDiff.i = 3.5

PowerTrain.DL.FDiff.Cpl.Kind = PowerTrain.DL.RDiff.Cpl.Kind=

KindStr KindStr

Optional. Select a coupling model. Default: no coupling is used. Possible values are: Visco, TrqSensing, Locked, DVA_Locked

PowerTrain.DL.FDiff.Cpl.Mounting = PowerTrain.DL.RDiff.Cpl.Mounting=

MountPos MountPos

Optional. Select mounting position. Possible values are: left2right, in2left, in2right Default: left2right.

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PowerTrain.DL.FDiff.Cpl.k PowerTrain.DL.RDiff.Cpl.k Optional. Stiffness used for numerical stability when switching from stick to slip. Default: 10

Differential Model ‘Central’ A center differential is only available for Model ‘Gen4WD’.

PowerTrain.DL.CDiff.I_in =

value

Inertia of the input shaft

PowerTrain.DL.CDiff.I_out_front =

value

Inertia of the front output shaft

PowerTrain.DL.CDiff.I_out_rear =

value

Inertia of the rear output shaft

PowerTrain.DL.CFDiff.I_Cage =

value

Optional. Inertia of the differential cage. Default: 0

PowerTrain.DL.CDiff.i_in2cent =

value

Transmission ratio from input shaft to cage of the center differential. Example

PowerTrain.DL.CDiff.i_in2cent = 1.0

PowerTrain.DL.CDiff.TrqRatio_front =

value

Selects the torque distribution between front and rear axle. This paramter specifies how the percentage of the input torque which is transfered to the front axle (the remaining torque goes to the rear axle). The input range is from 0..1 excluding both extremal values. Example

PowerTrain.DL.CDiff.TrqRatio_front = 0.7

This means that 70% of the input torque is transfered to the front axle and 30 % to the rear axle.

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PowerTrain.DL.CDiff.Cpl.Kind =

KindStr

Select a coupling model. Possible values are: Visco, TrqSensing, Locked, DVA_Locked

PowerTrain.DL.CDiff.Cpl.Mounting =

MountPos

Optional. Select mounting position. Possible values are: front2rear, in2rear, in2front Default: front2rear.

PowerTrain.DL.CDiff.Cpl.k =

value

Optional. Stiffness used for numerical stability when switching from stick to slip. Default: 10

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8.2.4

Model ‘Generic’ Coupling Parameters Coupling Model ‘Visco’ ‘F’ means front, ‘R’ means rear, ‘C’ means center.

PowerTrain.DL.FDiff.Cpl.Trq_Amplify = value PowerTrain.DL.RDiff.Cpl.Trq_Amplify = value PowerTrain.DL.CDiff.Cpl.Trq_Amplify = value PowerTrain.DL.HangOn.Cpl.Trq_Amplify =value Amplifies the determined value by a given factor

PowerTrain.DL.FDiff.Cpl.Trq_drotv = PowerTrain.DL.RDiff.Cpl.Trq_drotv = PowerTrain.DL.CDiff.Cpl.Trq_drotv = PowerTrain.DL.HangOn.Cpl.Trq_drotv =

value value value value

Characteristic for coupling torque as a function of the rotation speed difference: T = f ( ∆ω˙ ) . ! Syntax

Infofile table mapping with 2 columns

Coupling Model ‘Locked’ No parameters are necessary!

Coupling Model ‘TrqSensing’

PowerTrain.DL.FDiff.Cpl.TrqBias_Driven = PowerTrain.DL.RDiff.Cpl.TrqBias_Driven = PowerTrain.DL.CDiff.Cpl.TrqBias_Driven =

value value value

Specify torque bias value for drive case driven. Value has to be >= 1. Example

PowerTrain.DL.FDiff.Cpl.TrqSensing.TrqBias_Driven = 1.3

PowerTrain.DL.FDiff.Cpl.TrqBias_Dragged = PowerTrain.DL.RDiff.Cpl.TrqBias_Dragged = PowerTrain.DL.CDiff.Cpl.TrqBias_Dragged =

value value value

Specify torque bias value for drive case dragged. Value has to be >= 1. Example

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PowerTrain.DL.FDiff.Cpl.TrqSensing.TrqBias_Dragged = 1.2

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Coupling Model ‘DVA_Locked’ No extra parameters needed for coupling model ‘DVA_Locked’! The coupling torque can be set by accessing DVA variables (See section 12.3.2 on page 268).

Coupling Model for Configurations ’Gen2p2Front’ and ’Gen2p2Rear’ One axle is driven, the other one is hanged on. It is parametrized with basic parameters, extended by a hang on coupling.

PowerTrain.DL.HangOn.I_in =

value

Inertia of the input shaft

PowerTrain.DL.HangOn.I_out =

value

Inertia of the output shaft

PowerTrain.DL.HangOn.i =

value

Transmission ratio between gearbox and hangon coupling Example

PowerTrain.DL.Hangon.i = 1.0

PowerTrain.DL.HangOn.Cpl.Kind = KindStr Select a coupling model. Possible values are: Visco, Locked, DVA_Locked

PowerTrain.DL.HangOn.rotv_open =

value

Only for configuration Gen2p2Front! Optional. With this parameter it is possible to implement a disconnect unit for the rear axle. When the vehicle is dragged and the rotation speed is above the specified value the disconnect unit applies. Default: 1e38 (this means no disconnect unit is installed) Example

PowerTrain.DL.HangOn.rotv_open = 100

PowerTrain.DL.HangOn.Cpl.k =

value

Optional. Stiffness used for numerical stability when switching from stick to slip. Default: 10.

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Engine Torque

8.3

Engine Torque Overview The engine model is primarily concerned with engine torque. It provides the torque to the clutch input. shaft. The engine rotation itself is calculated externally by the powertrain module. ECU Signals

q, q˙ Engine

T Engine Engine

Clutch

Accelerator Pedal Starter activated Ignition on/off Figure 8.10: Engine Model

As shown in Figure 8.10 the main task of the engine model is to act as a torque source. The output T Engine of the engine model can be calculated with different approaches. This is why several subsystem types for the engine model are distinguished.

PowerTrain.ET.Kind =

KindStr

Selection of the engine subsystem to use. The powertrain components library provides the following engine torque models: Engine Torque Model

Description

Mapping

Characteristics are used to determine the engine torque

Linear

Simple engine torque model, independent from engine speed

DVA

Engine torque is modified via DVA access

... Example

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PowerTrain.ET.Kind = Mapping

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Engine Torque

8.3.1

Engine Torque Model ‘Mapping’ This engine torque model uses characteristics to describe the behavior of the engine torque depending on engine speed and throttle position.

Guidelines for configuring the engine torque map A measured standard engine torque map usually does not cover parts below minimal and above maximal engine speed. For the usage with CarMaker it is essential that there are values given above and below those boundaries.

torque [Nm]

Figure 8.11 shows an engine torque map ‘prepared’ for the usage with CarMaker with extended boundaries. The standard speed range of this engine is 500 to 7000 rpm. Above 7000 rpm usually the throttle cutoff applies. This is realized through ramping down the full load characteristics to zero at 8000 rpm and extrapolating the drag load characteristic to 8000 rpm. Interim values for throttle positions should be equally spaced between full and drag load. 200

150

100

50

0

-50

-100 0

1000

2000

3000

4000

5000

6000

7000

8000

rotation speed [rpm] Gas Pedal:

0%

CarMaker Model Check

10%

20%

30%

40%

50%

60%

70%

80%

90%

Engine Torque Wed May 26 11:58:32 AM CEST 2004, Page 1

Figure 8.11: Sample engine torque map

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Engine Torque

The engine idle speed is designated to be approximately 900 rpm. In reality the engine has an idle speed controller to keep the engine running at the desired idle speed. To accomplish this behavior with CarMaker the drag load characteristic should have an area of positive torque values between 600 and 900 rpm.

TEngine / Nm 10 0

1000

nEngine / rpm

-10

Figure 8.12: Drag load characteristic to set up engine idle speed

Figure 8.12 shows a cutout of the engine idle speed characteristic to establish a idle speed of approximately 900 rpm. Due to the zero crossing of the torque characteristics at 900 rpm higher speeds are slowed down due to negative torque and lower speeds are increased by the small amount of positive torque. Like in reality the engine stalls due to negative torque below 600 rpm. For other throttle values a smooth fading should be used (like in Figure 8.11).

Parameters

PowerTrain.ET.Mapping.Kind =

KindStr

This model supports two subsystems to be selected. PowerTrain.ET.Kind

Description

linear2D

A two dimensional engine characteristic map is used. Depends on engine speed and (driver-)gas.

DragFullLoad

Two characteristic lines are used. One for full throttle and one for minimal throttle (depending from engine speed)

PowerTrain.ET.nIdle =

value

Optional. If not defined the engine idle speed is determined out of the given characteristics. This is only an informational parameter for the engine model. It is not determined to set the engine idle speed. This is done by modifying the engine drag characteristic. See section on page 110.

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PowerTrain.ET.Starter.Trq =

value

Optional. Default starter torque is 10Nm.

PowerTrain.ET.Starter.rotvOff =

value

Optional. Turn off engine speed of the starter. If not given determined out of the given characteristics.

PowerTrain.ET.TrqKl15Off =

value

Optional. Engine drag with ignition off. Default -80Nm.

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Additional Parameters for Mapping Kind ‘linear2D’ If linear2d is selected with PowerTrain.ET.Kind the following parameters have to be specified:

PowerTrain.ET.Mapping.Amplify = value Optional. Amplifies the output of the engine characteristic by a given factor. Default: 1.

PowerTrain.ET.Mapping.Data :

value

Two dimensional characteristic for the engine torque mapping. Specifies blocks for equal speed and vary gas from min to max. Syntax

Example

CarMaker Reference Manual

Infofile table mapping with 3 columns PowerTrain.ET.Mapping.Data: 500 0.0 500 0.5 500 1 ..... 1000 0.0 1000 0.5 1000 1 ....



-90 -70 -50 0 80 150

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Additional Parameters for Mapping Kind ‘DragFullLoad’ If DragFullLoad is selected with PowerTrain.ET.Kind the following parameters have to be specified:

PowerTrain.ET.Exponent =

value

Transition from full load to drag load characteristic with a exponential function depending on throttle position. •

gas = 0 ... 1.0

•

Exponent = 1 → linear

•

Exponent > 1→ parabolic

•

Exponent < 1 → root shaped

x = TDrag ⋅ ( 1.0 – gas

Exponent

) + TFull ⋅ gas

Exponent

PowerTrain.ET.DragPower.Amplify =value Optional. Amplifies the output of the engine characteristic by a given factor. Default: 1.

PowerTrain.ET.DragPower =

value

Drag power characteristic. Syntax

Infofile table mapping with 2 columns [rpm] [Nm]

Example

PowerTrain.ET.DragPower: 500.0 -10.0 600.0 0.0 700.0 5.0 800.0 0.0 1000.0 -10.0 2000.0 -20.0 3000.0 -30.0 4000.0 -40.0 5000.0 -50.0 6000.0 -60.0 7000.0 -70.0 8000.0 -80.0

PowerTrain.ET.FullLoadPower.Amplify = value Optional. Amplifies the output of the engine characteristic by a given factor. Default: 1.

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PowerTrain.ET.FullLoadPower Full load power characteristic. Syntax

Infofile table mapping with 2 columns [rpm] [Nm]

Example

PowerTrain.ET.FullLoadPower: 500.0 1000.0 2000.0 3000.0 4000.0 4500.0 5000.0 6000.0 7000.0 8000.0

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10.0 140.0 155.0 165.0 180.0 185.0 182.0 168.0 130.0 0.0

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8.3.2

Engine Torque Model ‘Linear’

PowerTrain.ET.nIdle =

value

Optional. Default engine idle speed: 1200rpm

PowerTrain.ET.Starter.Trq =

value

Optional. Default starter torque is 15Nm.

PowerTrain.ET.Starter.rotvOff =

value

Optional. Turn off engine speed of the starter. If not given determined out of the given characteristics.

PowerTrain.ET.TrqKl15Off =

value

Optional. Engine drag with ignition off. Default -80Nm.

PowerTrain.ET.SpeedRange =

rotv_min

rotv_max

Optional. Specifies the minimal and maximal Engine Speed. Below and above those speeds the engine torque is regulated down. A ramp function is used. Example

PowerTrain.ET.SpeedRange = 500 8000

PowerTrain.ET.PowerRatio =

value

This specifies the maximum engine torque with full throttle. It is independently of the engine speed. The engine speed is calculated by Trq = PowerRatio ⋅ Gas . Example

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PowerTrain.ET.PowerRatio = 300

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8.3.3

Engine Torque Model ‘DVA’ This is a simple engine torque model. The engine torque only depends on the gas pedal position. There is no dependency on the rotation speed of the engine (as for a usual engine). Parameters

PowerTrain.ET.Trq_Ext2A =

value

The engine output torque directly depends on the driver gas pedal position (standardized) and is calculated by: EngineTrq = PowerTrain.ET.Trq_Ext2A * Gas

(EQ 36)

Default value: 100 Nm The name of the UAQ you can overwrite by a DVA write is "PT.Engine.DVA.Trq_Ext2A". Example

PowerTrain.ET.Trq_Ext2A = 100

PowerTrain.ET.TrqKl15Off =

value

Optional. Engine drag with ignition off. Default -80Nm.

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8.3.4

Engine Model Software Interfaces Engine Controller Usually vehicle dynamic controllers communicate with the engine controller. One reason is to make modifications to the present engine torque in order to increase driving stability. In an CarMaker/HIL approach without a having a real engine controller a functionality has to be implemented as a model that simulates the intervention of the vehicle dynamic controller to the engine torque. This is realized in CarMaker with a user code function (usually in module User.c) Listing 8.1: Usage of user code function EngineControl in User.c 1: 2: 3: 4: 5: 6: 7: 8: 9: 10: 11: 12: 13: 14: 15: 16: 17: 18: 19: 20: 21: 22: 23: 24: 25: 26: 27: 28: 29: 30: 31: 32: 33: 1:

tatic void EngineControl (void); int User_TestRun_Start (void) { ... /* activate an engine control software module */ Vehicle.EngineControl = EngineControl; ... } /* ** ** ** ** ** ** ** ** ** ** */

EngineControl () Simulation model for an engine control ECU Modify the engine torque (PowerTrain.Engine.Trq), in most cases based on an static engine torque characteristic. Call: - called after EngineTrq model (PowerTrain.Engine.Trq is assigned with the output of EngineTrq model) - pay attention to realtime condition

static void EngineControl (void) { if (ConnectedIO == MyIO) { ... /* Modify engine torque */ ... PowerTrain.Engine.Trq = MyModifiedTorque; }

Line 1 defines a static function EngineControl in module User.c . In order to make CarMaker to call this function in every simulation step its pointer has to be liked to the variable Vehicle.EngineControl. This is done in the function User_TestRun_Start. The finally modified engine torque has to be assigned at the end of EngineControl to the variable PowerTrain.Engine.Trq.

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Clutch

8.4

Clutch Overview The clutch calculates the torque transfer from the engine to the gearbox input shaft considering the clutch pedal or ECU signals. ECU Signals T Clutch2GearBox

T Engine Engine

Gearbox

Clutch q, q˙ Engine

q, q˙ Gearbox Clutch Pedal

Figure 8.13: Clutch Model

PowerTrain.Clutch.Kind =

KindStr

Selection of the clutch subsystem to use. The powertrain components library provides the following submodels: Powertrain.Clutch.Kind

Description

Converter

torque converter model usually used in combination with automatic transmissions

Manual

manual clutch model usually hand-operated by the driver

DVA

Clutch torque is modified via DVA access

... Example

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PowerTrain.Clutch.Kind = Manual

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Clutch

8.4.1

Clutch Model ‘Manual’ A manual clutch in reality consists of two plates a friction plate and a contact pressure plate. The transmissible torque depends of the contact pressure and the speed difference between the two plates. In a real time environment with fixed step integrators modeling a technical system like a clutch is a challenging task. With conventional methods usually problems occur when transiting from slip to the singularity stick and vice versa. For a better computation stability the modeling approach of the clutch in this powertrain is sightly more complex.

T ω, ω˙ input plate

Engine

output plate

T In2Fp T Fp2In

ω Out, ω˙ Out

Gearbox

⇒

{ {

⇒

ω In, ω˙ In

friction plate ω Fp, ω˙ Fp

Case: open

Case: closed

Figure 8.14: Structure of Clutch Model Manual

Figure 8.14 shows the non physical approach of this model which uses three plates for transmitting the torque from the engine to the gearbox. The plates form engine side to gearbox side are called “input-”, “friction-” and “output-plate”. The “input-” and the “friction-plate” form a system with pure friction which is used to cover the case clutch is opened respectively is slipping. The remaining two plates form the counterpart for the closed clutch where a spring loaded force element is added to the friction part. Both parts of this clutch system contribute their moment to the resulting clutch moment which is transmitted through the clutch: T In2Out = T fIn2Fp + T kdFp2Out

(EQ 37)

To determine how much every system is contributing (or which case applies the most at one stage) a weighting function is used. Internally a normalized pedal position within ConnectPos and DisconnectPos is used. Below ConnectPos no torque is transmitted and above DisconnectPos the clutch is fully closed. PedalPos Norm = x ( PedalPos – ConnectPos )

(EQ 38)

The factor x in (EQ 38) is estimated so that the range [0 .. 1] is adhered. A simple weighting function is derived from the normalized pedal position: λ = PedalPos Norm

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(EQ 39)

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Clutch

•

Calculation of the case “clutch open”: ∆ω˙ In2Fp = ω˙ Fp – ω˙ In

(EQ 40)

T fmax = ( 1.0 – λ ) ⋅ Trq_max_fric

(EQ 41)

T fmax is the maximum transmittable torque for the case clutch open. The real transmit-

ted torque calculates to:

T fIn2FP = min ( T fmax , d_fric ⋅ – ω˙ In2Fp ) •

(EQ 42)

Calculation of the case “clutch closed”: This case makes the assumption that the speed of the “input-” and the “friction plate” are equal ω˙ Fp ≡ ω˙ In . This also means that following (EQ 40) and (EQ 42) T fIn2Fp calculates to zero and only this part is contributing the torque transmission. ∆ω˙ Fp2Out = ω˙ Out – ω˙ In

(EQ 43)

∆ω Fp2Out = ω Out – ω Fp

(EQ 44)

T kdmax = ( 1.0 – λ ) ⋅ Trq_max

(EQ 45)

With

the transmitted torque calculates to: T kdFp2Out = min ( T kdmax , k_FP ⋅ – ω FP2Out + d_FP ⋅ – ω˙ Fp2Out )

(EQ 46)

Parameters

PowerTrain.Clutch.ConnectPos =

value

Optional. At this clutch pedal position the clutch starts transferring torque. Default: 0.3 [0 .. 1]. Example

PowerTrain.Clutch.ConnectPos = 0.3

PowerTrain.Clutch.DisconnectPos =

value

Optional. At this clutch pedal position the clutch starts slipping when opening. Default: 0.7 [0 .. 1] Example

PowerTrain.Clutch.DisconnectPos = 0.7

PowerTrain.Clutch.Trq_max =

value

Optional. Sets maximum transmissible torque equally for both cases, clutch is slipping and clutch is closed Example

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PowerTrain.Clutch.Trq_max = 300

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Clutch

Alternatively the maximum transmissible torque can be set independently with the following two parameters.

PowerTrain.Clutch.Trq_max_fric = value Optional. Maximum transmissible torque when clutch is slipping.Default: 300. Example

PowerTrain.Clutch.Trq_max_fric = 300

PowerTrain.Clutch.Trq_max_kd =

Syntax

value

PowerTrain.Clutch.Trq_max_kd = val [Nm] optional, default 300 Nm

Maximum transmissible torque when clutch is closed. Example

PowerTrain.Clutch.Trq_max_kd = 300

PowerTrain.Clutch.d_fric =

Syntax Info

value

PowerTrain.Clutch.d_fric = val [–] optional, default 0.0175

Optional, unit: Nm/deg. Friction coefficient for the case clutch is slipping. Example

PowerTrain.Clutch.d_fric = 0.0175

PowerTrain.Clutch.k_FP =

value

Optional, unit: Nm/deg; default: 1.6667 Nm/deg. Spring constant for the case clutch is closed. Example

PowerTrain.Clutch.k_FP = 1.6667

PowerTrain.Clutch.d_FP =

value

Optional, unit: Nm s/deg. Friction coefficient for the case clutch is closed. Default: 0.1167 Example

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PowerTrain.Clutch.d_FP = 0.1167

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Clutch

8.4.2

Clutch Model ‘Converter’ A hydrodynamic torque converter or Föttinger-Converter is able to reduce rotation speed and translate torque. The input and output torque TIn,Out of the converter is calculated with the speed ratio dependent converter factors kIn, kOut and the input speed ωIn. 2

T In = k In ω In

k In, k Out = f ( s )

mit

2

T Out = k Out ω Out

ω Out s = ----------ω In (EQ 47)

The relation between the converter output- and the input-torque is often described with the torque ratio µ. T Out k Out µ = ---------- = ---------T In k In

(EQ 48)

So, two characteristics kIn (s) and µ (s) respectively kOut(s) are used to represent the transmission behavior of the converter. Those characteristics use the following parameter names in CarMaker input files: kIn µ

PowerTrain.Clutch.k_E PowerTrain.Clutch.mue

converter factor kIn (Nms2)

Figure 8.15 shows a typical gradient of the converter factor kIn over the speed ratio nOut/nIn:

1.7 e-3

1 e-4 0

rotation speed ratio nOut /nIn

1 0.98

Figure 8.15: converter factor kIn as a function of the rotation speed ratio

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Clutch

As depicted in Figure 8.16 the maximum torque ratio (usually 1.9 to 2.5) for the driveway reduces with increasing rotation speed ratios. Above a certain speed ratio the torque ratio remains constantly shortly below 1 (because of losses). This case is called clutch mode.

torque ratio m = Tout/Tin

2.3

0.98

0

rotation speed ratio nout/nin

0.88

1

Figure 8.16: torque ratio as a function of the rotation speed ratio

Parameters

PowerTrain.Clutch.Adjust =

value

For principal adaption of converter characteristics. This factor is multiplied with PowerTrain.Clutch.k_E. This parameter needs to be 1 to obtain the given characteristic! Otherwise the characteristic for PowerTrain.Clutch.k_E is altered by this factor

Example

PowerTrain.Clutch.Adjust = 1.0

PowerTrain.Clutch.k_E =

Table

Characteristic for the input torque conversion factor.! Syntax

Infofile table mapping with 2 columns

Example

PowerTrain.Clutch.k_E: 0.0 3.3e-4 0.3 3.2e-4 0.6 3.0e-4 0.9 2.2e-4 0.95 1.8e-4 0.975 1.2e-4 0.995 1.7e-5 1.0 0

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Clutch

PowerTrain.Clutch.mue : =

Table

Torque ratio characteristic. Syntax

Infofile table mapping with 2 columns

Example

PowerTrain.Clutch.mue: 0.0 2.1 0.8 0.98 0.9 0.98 1.0 0.98

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Clutch

8.4.3

Clutch Model ‘DVA’ This model is not a conventional clutch model. The transmissible torque is not determined by the rotations speed difference of the clutches input and output shaft and the pedal actuation. T Clutch2Gearbox DVA

PT.Clutch.DVA.Trq_A2B

Gearbox

Clutch q, q˙ Gerarbox

Figure 8.17: Clutch Model DVA

The user can specify a torque by modifying a DVA variable. T Clutch2Gerbox = PT.Clutch.DVA.Trq_A2B

(EQ 49)

This model decouples the engine model since only the user specified torque is transferred to the gearbox input shaft.

Parameters This model has no parameters.

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Gear Box

8.5

Gear Box Overview The primarily task of the gearbox subsystem is the transmission of rotation speed and torque from the input- to the output-shaft according to Figure 8.18. ECU Signals T Gearbox2DL iGearBox

T Clutch2GearBox Clutch

Driveline

Gearbox q, q˙ Driveshaft

q, q˙ Gearbox Gear Selector

Figure 8.18: Gearbox Model

PowerTrain.GearBox.Kind =

KindStr

Selection of the gearbox subsystem to use. The powertrain components library provides the following gearbox models: Powertrain.GearBox.Kind

Description

Manual

currently only a manual transmission is available

DVA

Transmission ratio is modified via DVA access

... Example

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PowerTrain.GearBox.Kind = Manual

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Gear Box

8.5.1

GearBox Model ‘Manual’ The selection of the gear ratio with the manual transmission model is done by user requirements or the driver model (IPG-DRIVER). The transmission of torque is calculated by this simple approach: T Out = i G ⋅ M In

(EQ 50)

The change from one gear ratio to another has to proceed in a certain time period because it is impossible to accelerate the transmission input inertia unlimited. This synchronization process is modeled through a constant gear change duration (parameterizable). The transmission rate is adjusted continuously during this procedure.

PowerTrain.GearBox.iForwardGears =

GearRatioList

State the transmission ratio for every single forward gear. Example

PowerTrain.GearBox.iForwardGears = 3.4 1.9 1.35 1.05 0.8

PowerTrain.GearBox.iBackwardGears =

GearRatioList

State the transmission ratio for every single backward gear. Example

PowerTrain.GearBox.iBackwardGears = -4.0

PowerTrain.GearBox.nFit =

value

OPtional. This defines the number of cycle times (or milliseconds) used for the synchronization process. Default: 50 Example

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PowerTrain.GearBox.nFit = 50

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Gear Box

8.5.2

GearBox Model ‘DVA’ This model is not a conventional gearbox model. The transmission is not determined by the selected gear ratio. PT.GearBox.DVA.i

T Gearbox2DL iGearbox

T Clutch2Gearbox Clutch

Driveline

Gearbox q, q˙ Gearbox

q, q˙ Driveshaft

Figure 8.19: Gearbox Model DVA

The user can specify a transmission ratio by modifying a DVA variable: T Clutch2Gerbox = PT.GearBox.DVA.i

(EQ 51)

Parameters This model has no parameters.

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User Accessible Quantities for PowerTrain

8.6

User Accessible Quantities for PowerTrain Please refer to section 12.3 ’User Accessible Quantities: Power Train’

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Powertrain Software Interface

8.7

Powertrain Software Interface The powertrain uses the global data structure PowerTrain to exchange signals form one subsystem to the other and to enable the user to observe the powertrain. Figure 8.20: gives a structural overview for the exchanged quantities. Inputs needed come from subsystems DrivMan (simulation of the vehicles virtual control elements), Car and Brake.

Inputs

Outputs

DrivMan DrivMan.Gas DrivMan.Clutch DrivMan.GearNo DrivMan.StarterCtrl DrivMan.Ignition

Engine PowerTrain.Engine_on PowerTrain.Engine_rotv

Car Car.Trq_T2W

Wheel PowerTrain.W.rotv PowerTrain.W.rot PowerTrain.W.Trq_B2W

GearBox PowerTrain.GearBox_rotv_in

PowerTrain

PowerTrain PowerTrain.Trq2Bdy1 Brake Brake.Trq_

Legend =FL/FR/RL/RR Figure 8.20: Inputs and Outputs of the Power Train

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Powertrain Software Interface

Listing 2.3 shows the framework of the powertrain data structure from header file PowerTrain.h. For further details please refer to this file. Listing 8.2: Interface Data Structure struct tPowerTrain { struct tPTEngine { } Engine; struct tPTClutch { } Clutch; struct tPTGearBox { } GearBox; struct tPTDriveLine { } DriveLine; struct tPTWheel { } WFL, WFR, WRL, WRR; double

Trq_Supp2Bdy1[3];

}; struct tPowerTrain PowerTrain;

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Overview

Chapter 9

Brake System

9.1

Overview CarMaker offers for every purpose an appropriate brake system model. There are different interests for using a specific brake system model. A simple brake model is sufficient if the main interest of investigation is not concerned with the brake system and no electronic brake controller is used. It is good for driving maneuvers with simple braking tasks. If the interest is based on the brake system itself or if a brake ECU has to be satisfied there is a high resolution brake model available which is exclusively parameterizable. The aim is to represent the real braking system as closely as possible in combination with real time computing constraints.

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Overview

9.1.1

Brake Interface Internally CarMaker uses an interface structure for exchanging signals with the brake model. Inputs from different CarMaker modules are grouped in the interface structure (for details see header file Brake.h or section 9.2 on page 137). Figure 9.1 shows the input quantities to the interface structure.

DrivMan.Brake Trq[4]

IO.HydValve[12] IO.PumpIsOn IO.BooSignal

Brake Model Calculation The user selected Brake Model is calculated with this function

Brake Interface Struct (Output-Quantities)

Brake Interface Struct (Input-Quantities)

DrivMan.BrakePark

pWB[4]

Pump

return volt.

ExtInp_IF.PactUnit.Value Ambient.Temperature Figure 9.1: Structure of Brake Interface

The box in the middle shows the changeable brake model which can be a simple or a high resolution brake model from the CarMaker brake library or any customer specific brake model which satisfies the brake interface structure. The input from the interaction controls of the brake system are provided from the DrivMan module and displayed DrivMan.x quantities. For a brake ECU in the Loop the information about valve positions and other output of the brake ECU is needed as input into the brake model. Those signals are acquired from the CarMaker IO module and shown as the IO.x input signals in Figure 9.1 For special purposes, e. g. control the master cylinder pressure with data records from an external input file, there is a separate input for the pressure of the master cylinder (ExtInp_IF.PactUnit.Value). For several reasons the environment temperature is needed for some calculations within brake models. this is why there is a separate input for the ambient temperature (Ambient.Temperature). In terms of embedding the brake model within the CarMaker vehicle environment only the estimated brake torque for each wheel are needed as output values. But there are a number of other output quantities as indicated by the arrows characterizing the output quantities (for details see header fileBrake.h or section 9.2 on page 137). Depending on the brake model used not all output quantities are calculated and therefore not updated.

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Brake System Software Interface

9.2

Brake System Software Interface Listing 9.1: Interface structure to the brake system calculation function 2: /*** Brake Interface: Interface to the brake calculation function 3: 4: typedef struct tBrakeIF { 5: 6: /*** Input Quantities: */ 7: int Use_pMCInput; /* use pressure input instead of force 8: 9: double Pedal;/* brake pedal actuation */ 10: double Park;/* park brake actuation */ 11: double pMC_in; /* optional input: Master cylinder pressure 12: 13: double V[16]; /* relative Valve signals [0..1] 14: * 0-3: Inlet FL/FR/RL/RR, opened if 0 15: * 4-7: Outlet FL/FR/RL/RR, closed if 0 16: * 8: Pilot Valve FR/RL, opened if 0 17: * 9: Pilot Valve FL/RR, opened if 0 18: * 10: Suction Valve FR/RL, closed if 0 19: * 11: Suction Valve FL/RR, closed if 0 20: int PumpIsOn; /* hydraulic pump 21: double BooSignal; /* booster input signal 22: 23: double T_env; /* Temperature of the environment [K] 24: 25: /*** Output Ouantities: */ 26: double pMC; /* pressure actuation unit (master cylinder) [bar] 27: double pWB[4]; /* pressures wheel brakes FL/FR/RL/RR [bar] 28: double Trq_WB[4]; /* wheel brake torques FL/FR/RL/RR [Nm] 29: double Trq_PB[4]; /* parking brake torques 30: double Trq_ext[4]; /* external (or additional) brake torques 31: double Trq_tot[4]; /* total brake toques (used for wheel rotation) 32: 33: int Rel_SW; /* booster release switch 34: double PuRetVolt; /* induced voltage of the hydraulic pump 35: 36: double PedFrc; /* force on the brake pedal 37: double PedTravel; /* travel of the brake pedal [mm] 38: double PistTravel; /* travel of the master cylinder [mm] 39: double DiaphTravel; /* travel of the booster diaphragm 40: 41: /*** Optional Input/Output Quantities: */ 42: double OptDblIO[8];/* HydESP: [0] := pump pwm control */ 43: long OptLngIO[4]; 44: void *OptPtrIO; 45: 46: } tBrakeIF; 47:

*/

*/

*/ * * * * * * */ */ */ */

*/ */ */ */ */ */ */ */ */ */ */ */

Calculation Function int (*Eval) (void *BP, tBrakeIF *IF, double dt);

CarMaker Reference Manual

/* Modellparameter/Instanzpointer /* Interface structure /* time step

*/ */ */

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General Brake System Parameters

9.3

General Brake System Parameters The parameters explained here apply for all brake models and are stored in the vehicle data file.

Selection of the Brake Model

Brake.Kind =

KindStr

Specifies which brake model is used. Used if brake parameters are specified in the Vehicle Data File. Possible values are: Brake.Kind

Description

PresDistrib

simple brake model, for details see section 9.5 on page 142

HydESP

high resolution brake model, for details see section 9.6 on page 144

Example

Brake.Kind = HydESP

Brake.FName =

FName

This references a brake model from a file including all other (not listed here) brake parameters. The file is read from the subdirectory Data/Misc. The model type is determined from the FileIdent parameter (should be the first line in the external file). Currently this is only available for the model HydESP (FileIdent = CarMaker-Brake-HydESP 3). If Brake.FName is specified the parameter Brake.Kind is not taken into account.

Example

Brake.FName = HydESP_DemoParam

Brake.Torque.Amplify =

ValueList

Multiplies the specific brake torque of the wheel, which has been calculated by the brake model with this factor [-]. Four factors in the order front left, front right, rear left, rear right. Example

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Brake.TorqueAmplify = 1.0 1.0 1.0 1.0

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General Brake System Parameters

Parking Brake CarMaker distinguishes between brake and parking brake. The parking brake model is not contained in the changeable brake module selected with Brake.Kind or Brake.FName and remains for all models the same. It is implemented as a fixed system within the CarMakers car model.

Brake.Park.Trq_max =

ValueList

Maximum parking brake torque at each wheel [Nm]. Four values in the order front left, front right, rear left, rear right. Example

Brake.HandTorque.Value = 0 0 1000 1000

In this example the parking brake acts only on the rear wheels.

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User Accessible Quantities

9.4

User Accessible Quantities

9.4.1

General User Accessible Quantities for Brake Systems Name

Unit

Booster activation signal (0..1)

Brake.BooSignal

Brake.DiaphTravel

Info

m

Travel of the booster diaphragm Brake pedal actuation (0..1)

Brake.Pedal Brake.PedFrc

N

Force applied on brake pedal

Brake.PedTravel

m

Brake pedal travel

Brake.PistTravel

m

Travel of brake piston Park brake actuation (0..1)

Brake.Park

Brake.pMC

bar

Master cylinder pressure

Brake.pMC_in

bar

Input of master cylinder pressure to hydraulic model if input mode ‘Use_pMCInput’ ist selected in the brake interface. Hydraulic pump activated

Brake.PumpIsOn Brake.PuRetVolt

V

Hydraulic pump return voltage

Brake.pWB_FL

bar

Brake pressure front left

Brake.pWB_FR

bar

Brake pressure front right

Brake.pWB_RL

bar

Brake pressure rear left

Brake.pWB_RR

bar

Brake pressure rear right Brake booster release switch actuated

Brake.Rel_SW

Brake.T_env

K

Environment temperature for brake

Brake.Trq_FL

Nm

Brake torque front left

Brake.Trq_FR

Nm

Brake torque front right

Brake.Trq_RL

Nm

Brake torque rear left

Brake.Trq_RR

Nm

Brake torque rear right

Brake.Trq_PB_FL

Nm

Brake torque of park brake front left

Brake.Trq_PB_FR

Nm

Brake torque of park brake front right

Brake.Trq_PB_RL

Nm

Brake torque of park brake rear left

Brake.Trq_PB_RR

Nm

Brake torque of park brake rear right

Brake.Trq_FL_ext

Nm

External brake torque front left

Brake.Trq_FR_ext

Nm

External brake torque front right

Brake.Trq_RL_ext

Nm

External brake torque rear left

Brake.Trq_RR _ext

Nm

External brake torque rear right

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User Accessible Quantities

Name

Unit

Info

Brake.Trq_FL_tot

Nm

Total brake torque (trq+trq_park+ trq_ext) front left

Brake.Trq_FR_tot

Nm

Total brake torque (trq+trq_park+ trq_ext) front right

Brake.Trq_RL_tot

Nm

Total brake torque rear left (trq+trq_park+ trq_ext)

Brake.Trq_RR _tot

Nm

Total brake torque rear right (trq+trq_park+ trq_ext)

Brake.Valve_In_FL

Valve activity for inlet valve front left (0..1)

Brake.Valve_In_FR

Valve activity for inlet valve front right (0..1)

Brake.Valve_In_RL

Valve activity for inlet valve rear left (0..1)

Brake.Valve_In_RR

Valve activity for inlet valve rear right (0..1)

Brake.Valve_Out_FL

Valve activity for outlet valve front left (0..1)

Brake.Valve_Out_FR

Valve activity for outlet valve front right (0..1)

Brake.Valve_Out_RL

Valve activity for outlet valve rear left (0..1)

Brake.Valve_Out_RR

Valve activity for outlet valve rear right (0..1)

Brake.Valve_PV_0

Valve activity for pilot valve 0

Brake.Valve_PV_1

Valve activity for pilot valve 1

Brake.Valve_SV_0

Valve activity for suction valve 0

Brake.Valve_SV_1

Valve activity for suction valve 1

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9.5

Brake System PresDistrib

9.5.1

Overview This is a simple brake model which acts like a conventional one circuit brake.

Tfr

masterbrakecylinder

brake pedal

Trr force or position

pMC

Trl

Tfl

Figure 9.2: principle of brake model ‘PresDistrib

A master brake pressure is build proportional to the input value of the brake pedal. p MC = PF2pMC ⋅ F ped

(EQ 52)

p MC = PP2pMC ⋅ x ped

(EQ 53)

or

The braking torque for each individual wheel is calculated by T i = p MC ⋅ pWB2Trq i with i = fl, fr, rl, rr p MC F ped x ped Ti PF2pMC PP2pMC pWB2Trq i

CarMaker Reference Manual

(EQ 54)

pressure of master brake cylinder brake pedal force brake pedal position brake torque at wheel i conversion factor from brake pedal force to master brake cylinder pressure conversion factor from brake pedal position to master brake cylinder pressure conversion factor from master brake cylinder pressure to wheel brake torque

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9.5.2

Brake System PresDistrib Parameters

Brake.pMC_based_on This parameter specifies how the master brake pressure is determined. Brake.pMC_Based_on

Description

PedalPos

Master brake pressure depends on brake pedal position (Default).

PedalForce

Master brake pressure depends on brake pedal force.

The Brake pressure in the master cylinder is proportional to either pedal position or pedal force. Example

Brake.pMC_based_on = PedalPos

Brake.PedalPos2pMC This parameter is valid if ‘PedalPos’ is selected with Brake.pMC_Based_on. This factor determines the master brake cylinder pressure according to (EQ 53) [bar].

Brake.PedalForce2pMC This parameter is valid if ‘PedalForce’ is selected with Brake.pMC_Based_on. This factor determines the master brake cylinder pressure according to (EQ 52) [bar].

Brake.pWB2Trq Ratio wheel pressure to brake torque, see (EQ 54) [-]. Specify 4 values for fl, fr, rl, rr wheel. Example

CarMaker Reference Manual

Brake.pWB2Trq =

16.0

16.0

7.0

7.0

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9.6

Brake System HydESP

9.6.1

Overview Structure of the braking system A standard car braking system consists of two brake circuits, each one applying two wheel brakes. Also this model can be used with two different brake-circuit configurations: In the diagonal (X-pattern) system, each brake circuit applies on a front wheel brake and a rear wheel brake on the opposite side. In the system with separate circuits for the front and rear axle (II-pattern), each circuit applies the brakes on one axle. The two circuits are called primary and secondary circuit. In reality as well as in the model the two circuits are identical. The following picture shows a brake system with ESP. Only the primary circuit and only one wheel brake is shown.

brake booster

drive signal brake booster

master cylinder brake pedal

to secondary circuit

pilot valve suction valve

hydraulic pump line volume

attenuator or line volume

low pressure accumulator outlet valve from outlet valve second wheel brake

inlet valve

to inlet valve second wheel brake wheel brake cylinder

Figure 9.3: ESP Braking System

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Interface of the model The HydESP model has interfaces to signals of the driver, the brake ECU and the vehicle. The following lists name the input and output used and generated by the brake model. Inputs

Outputs

•

normalized brake pedal actuation [0..1]

•

drive signals for the solenoid valves: digital or analog [0..1]

•

pump on/off (digital)

•

brake booster drive signal

•

pressure master cylinder

•

pressures wheel brake cylinders

•

brake torques

•

return voltage of the hydraulic pump

•

state of the booster release switch

•

travel of the master cylinder piston

•

travel of the brake pedal

Functional Description Figure 9.3 shows the simplified model of a ESP controlled brake system. The following is a brief description of such a system and how it features are modeled. The brake force applied to the brake pedal by the driver is mechanically transformed into a input force of the brake booster. The brake booster itself amplifies the input force and passes its output to the pistons of the master brake cylinder. There the piston rod force is translated into a master cylinder pressure. The master cylinder has two hydraulic connectors one for each brake circuit. It is assumed that the master cylinder pressure is equal for both brake circuits. The hydraulic part is modeled as a system of alternating volume and connection elements (connecting lines including valves, hydraulic pumps, etc.). This means that from every volume element there is a flow of brake fluid through connection elements to another volume element (depicted in Figure 9.4).

Volume Element 1

Volume Element 2

p 1, V 1

p 2, V 2

Volume Element 3 p 3, V 3

Figure 9.4: Hydraulic model with alternating volume and connection elements

Each volume element is characterized with the state variables pressure and volume. The system tries to equalize pressure differences with a flow from the high pressure to the low pressure volume element. The flow rate is limited by the hydraulic resistance which is a attribute of the connection element. The hydraulic resistance is a combination of the resisCarMaker Reference Manual

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tance of the connecting line and the current resistance of the valves (which often is a function of time and/or pressure difference). In case of a hydraulic pump this is reversed and the pump transports fluid from the low pressure side to the high pressure side. As a counterpart to the master brake cylinder the wheel brake cylinder transforms its current pressure into a brake lining force. This force is transformed into a brake torque by the wheel brake itself. The goal of the system of valves, pumps, connection lines and volume elements in case of a ESP system is to control the brake torque of each single wheel by regulating the pressure of its wheel brake cylinder. This is done by opening and closing the inlet and outlet valves for a certain amount of time to increase or decrease the brake pressure. To hold the current pressure inlet and outlet valves remain closed at the same time. The hydraulic pump is used to pump fluid back from the low pressure accumulator (where brake fluid is temporarily stored) to the reservoir of the master brake cylinder. In special operation modes of the system when the driver is not actuating the brake pedal the pump is used to generate pressure for autonomous brake interventions. For those operation modes of a ESP system two more controlled valves are needed for each brake circuit (named suction and pilot valves in Figure 9.3). See technical literature for more information how the suction and pilot valves are used and how specific actions are operated. ABS systems have basically the same structure as ESP systems but the suction and pilot valves are omitted. They are not needed because ABS systems do not perform autonomous brake interventions.

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9.6.2

Brake circuit configuration

CircuitConfig Optional. This parameter specifies the brake circuit configuration X- vs. II-pattern. (X-pattern = diagonal split, II-pattern = one circuit for one axle). Default: X-pattern. CircuitConfig

Brake Circuit Index

Brake Circuit

Description

X

0

FR/RL

Diagonal split.

1

FL/RR

0

FL/FR

1

RL/RR

II

Example

Parallel (front/rear) split.

CircuitConfig = X

Brake pedal The brake force applied to the brake pedal by the driver is mechanically transformed into a piston rod input force of the brake booster. piston travel

F BooIn

l1 l2

brake pedal

F Pedal

PedalActuation

Pedal2PedalFrc

[ 0..1 ]

pedal travel Figure 9.5: Mechanical amplification of drivers brake force

F BooIn = ratio ⋅ F Pedal

(EQ 55)

Pedal.ratio The pedal ratio amplifies the force of the brake pedal [-]. The resulting force is the input of the brake system. Example

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Pedal.ratio = 3.0

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Brake.Pedal2PedalFrc Optional. This parameters defines the relation between driver brake pedal actuation and brake pedal force F Pedal . Therefore a linear equation is used: F Pedal = PedalActuation ⋅ Pedal2PedalFrc

(EQ 56)

The force [N] defines the maximum brake force with full pedal actuation [1]. Default: 300 N. Example

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Brake.Pedal2PedalFrc = 500

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9.6.3

Brake booster The brake booster amplifies the input force at the piston rod proportionally up to a certain limit. Above this limit there is no more amplification of force.

p MC

F BooOut

p MC

master cylinder

F BooIn

brake booster

Figure 9.6: Amplification of brake actuation force by the brake booster.

The output force of the brake booster F BooOut equals a pressure of the master cylinder. This relation can be calculated with (EQ 60) of the master brake cylinder. Many parameters of the brake booster expect master cylinder pressures as input values instead of booster output forces. See the particular description of these parameters.

Figure 9.7 shows the relation between the input force of the brake booster and the corresponding master cylinder pressure. Before any pressure is build up the precharge force F 0 of the springs in the master cylinder has to be overcome. The following straight is the amplification range of the brake booster: F BooOut = ratio ⋅ F BooIn

(EQ 57)

The amplification ratio is higher than one. When a specific output force (or an corresponding master cylinder) is exceeded the amplification ratio becomes one for any further increase of input force. This pressure is called the booster run out pressure. The corresponding force can be calculated with (EQ 60).

p MC p runout

no amplification of force (ratio=1)

amplification of force (ratio>1)

F0

F runout

F BooIn

Figure 9.7: Brake booster output pressure characteristic

The following brake booster types are provided with this hydraulic model:

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Boo.type Optional. Boo.type determines the type of booster or precharge pump used. Some brake systems additionally use an electric drive of the booster in order to create a brake pressure even if there is no pedal force (e.g. brake assist, ACC). See booster models TargetPressure and PressureGradient. Boo.type

Description

none

Default: No brake booster is used. (Amplification ratio is always one).

Mechanical

Classic mechanical brake booster.

TargetPressure

Booster with pressure proportional to input signal or precharge pump.

PressureGradient

Booster with pressure gradient dp/dt = f(input signal)

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Brake Booster “Mechanical” See Figure 9.7: for explanation of this booster model.

Boo.ampli Amplification ratio when the brake booster is in amplification range [-]. See (EQ 57). Example

Boo.ampli = 7

Boo.runOut Specifies the booster run-out pressure [bar]. Above the run-out pressure the booster amplification is one (no amplification). Example

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Boo.runOut = 90

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Brake Booster “TargetPressure” “TargetPressure” is a model of a controlled system consisting of the mechanical booster and the simulated dynamic behavior of a booster-ECU. Internally this model distinguishes two forces: •

A “interactive” booster force by amplification of the drivers input force like the booster model “mechanical”.

•

A “automatic” booster force which is initiated by the standardized drive signal. The drive signal which is a input quantity of the HydESP brake interface has to be controlled by user code (can be a simulated or real ECU). The output force is proportional to the drive signal (0..1) without any driver interaction necessary for this. The dynamic behavior is calculated within this model. The dynamics of the force increase is modeled by a delay and a exponential saturation function. Additionally a force threshold value for the release switch must be given. The release switch is operated when the piston rod force (driver interaction) exceeds the given threshold force.

The effective booster force calculates as follows: F BooOut = max ( F Boo interactive, F Boo automatic )

(EQ 58)

For the “interactive” case see Figure 9.7: , the “automatic” case is shown in the following illustration:

[p, 0..1]

booster activation signal

p T arg et

booster pressure

t Boo.Delay

Boo.63Prcnt

Figure 9.8: Pressure rise controlled by booster ECU (case “automatic” booster force)

Boo.ampli Amplification ratio when the brake booster is in amplification range [-]. See (EQ 57). Example

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Boo.ampli = 7

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Boo.runOut Specifies the booster run-out pressure [bar]. Above the run-out pressure the booster amplification is one (no amplification). Example

Boo.runOut = 90

Boo.delay Delay between signal and pressure rise [s]. Example

Boo.delay = 0.01

Boo.63Prcnt Time constant for pressure rise [s]. After t = Boo.Delay + Boo.63Pcnt , booster pressure has reached 63% of the target value. Example

Boo.63Prcnt = 0.01

Boo.sign2press This parameter determines the output (target) pressure when booster ECU is active [bar/ 1]. The range of the drive signal is 0..1. p T arg et = Boo.sign2press ⋅ DriveSignal

Example

Boo.sign2press = 1

Boo.relF Pedal force applied by driver to open the release switch [N]. Example

CarMaker Reference Manual

Boo.relF = 10

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Brake Booster “PressureGradient” “PressureGradient” is a booster model similar to the model “Target Pressure”. The difference is that the drive signal is interpreted in a different way. Like the booster model “Target Pressure” two forces are distinguished: •

A “interactive” booster force by amplification of the drivers input force like the booster model “mechanical”.

•

A “automatic” booster force is initiated by the standardized drive signal of the booster ECU which is a input quantity of the HydESP brake interface. Here the gradient of pressure increase/decrease is a function of the activation signal. The pressure can not exceed a maximum pressure. In this booster model the release switch is operated when the “interactive” pedal force exceeds the force generated by the “automatic” booster force.

In case of an autonomous intervention parallel to a pedal force, the resulting pressure is the maximum of the two pressures: F Booster = max (F Booster manual,F Booster ECU)

(EQ 59)

Input signal

[p, 0..1] Boo.PMax

pressure fall Booster Pressure

pressure rise

t Figure 9.9: Pressure rise with booster model PressureGradient

Boo.ampli Amplification ratio when the brake booster is in amplification range [-]. See (EQ 57). Example

Boo.ampli = 7

Boo.runOut Specifies the booster run-out pressure [bar]. Above the run-out pressure the booster amplification is one (no amplification). Example

CarMaker Reference Manual

Boo.runOut = 90

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Boo.pMax Maximum pressure difference the booster is able to produce in “automatic” mode (this means booster pressure is controlled by the ECU) [bar]. Example

Boo.pMax = 90

Boo.pGrad.mapping Relation of booster activation signal [0..1] to gradient of pressure rise/fall [bar/s]. . Syntax

Infofile table mapping with 2 columns

Example

Boo.pGrad.mapping: 0.0 -1000.0 0.15 -1000.0 0.3 0.0 0.4 0.0 0.8 400.0 1.0 400.0 1.1 400.0

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9.6.4

Master Cylinder The master cylinder transforms the output force of the brake booster to a brake pressure.

Reservoir

Spring

Compensation Bores

p MC

p MC

Brake Circuit 2

F BooOut

Brake Circuit 1

Figure 9.10: Master Brake Cylinder

F BooOut – F MC, 0 – c MC ⋅ x MC p MC = ----------------------------------------------------------------- for x MC > x CompBore A MC

(EQ 60)

with p MC F BooOut A MC F MC, 0 c MC x MC x CompBore

Master cylinder pressure Brake booster output force Area of master cylinder. Precharge of the springs in MC. Spring constant of the MC springs. Piston travel. Piston travel to close compensation bore.

The pressure generated in the primary circuit is equal to the one in the secondary circuit. When the force is zero, the piston is at the backside stop. The compensation bores are open in this position and lead to a pressure equalization with the compensating reservoir (=atmospheric pressure). Once the force becomes superior to the precharge of the springs, the piston moves forward and closes the compensation bores. The whole brake system is now a closed system and the further movements of the piston are determined by the system’s elasticity.

MC.area Area of the piston [cm2] Example

CarMaker Reference Manual

MC.area = 4.5

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157 Brake System HydESP

MC.xCompBore Piston travel to close compensation bore [mm] Example

MC.xCompBore = 2

MC.springConst df N ------ of the spring(s) ---- . dx m

Example

MC.springConst = 1000

MC.springLoad Precharge of the spring(s) [N]. Example

CarMaker Reference Manual

MC.springLoad = 100

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9.6.5

Wheel brakes The following calculation can be applied to disk or drum brakes because it is very general. Figure 9.11: explains the requested parameters. brake lining

F Brake

r Brake

T Brake

disk or drum brake Figure 9.11: Schematic view of wheel brakes

The pressure in the brake cylinder is transformed into a brake torque as follows: T Brake = F Brake ⋅ r Brake = p Brake ⋅ A BC ⋅ a Brake lining ⋅ r Brake

(EQ 61)

with p Brake Brake pressure T Brake Brake torque. A BC Area of brake cylinder. a Brake lining Brake lining ratio. F Brake Brake force acting at the brake linings. r Brake Effective brake radius transforming force

into torque. The brake lining ratio describes the relation between brake pressure and resulting wheel brake torque. For disc brakes, its value usually is the coulomb number multiplied by 2. (factor 2 because there are brake linings on both sides of the disc). Optionally, a characteristic can be given: a Brake lining = f ( p Brake )

(EQ 62)

The given pairs of values are interpolated linearly. The brake radius is the effective radius to calculate the brake torque out of the brake force. For the following parameters applies: ‘f’ means front or ‘r’ means rear.

Pist_f.area Pist_r.area Total effective area of the ensemble of brake cylinders of one side (outboard or inboard) of brake pistons of a single brake [cm2]. Example

CarMaker Reference Manual

Pist_f.area = 23.0

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Pist_f.rBrake Pist_r.rBrake Effective brake radius (Brake Force -> Brake Torque) [m]. Example

Pist_f.rBrake = 0.1

For the following parameters applies: ‘fl’, ‘fr’ means front left/right, or ‘rl’, ‘rr’ means rear left/ right.

Pist_fl.ratio Pist_fr.ratio Pist_rl.ratio Pist_rr.ratio Ratio of braking force to actuating force [-]. This parameter takes into account the influence of the internal transmission ratio of the brake as well as the Coulomb friction coefficient. Frequently: 2*Coulomb (factor 2 comes from inboard + outboard brake linings) The ratio must be given for each brake of the four brakes. Example

Pist_fl.ratio = 0.7

Pist_fl.ratio.mapping Pist_fr.ratio.mapping Pist_rl.ratio.mapping Pist_rr.ratio.mapping Optional, instead of Pist_.ratio. Ratio [-] of braking force to actuating force as a function of the applied brake pressure [bar]. . Syntax

Infofile table mapping with 2 columns

Example

Pist_fl.ratio.mapping: 0 50 100 150 200

CarMaker Reference Manual

0.7 0.71 0.72 0.74 0.8

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9.6.6

Volume elements in general Volume elements have inputs and outputs. The resulting liquid volume leads to a certain pressure in the volume element. This relation is described by a function: p = f ( absorbed liquid volume ) .

(EQ 63)

By definition, the liquid volume of the filled elements at athmospheric pressure is equal to zero.

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9.6.7

Wheel brake cylinders The brake cylinders are modeled by the relationship: p = f ( liquid volume ) .

(EQ 64)

The parameters given must describe the sum of the elasticity of the brake cylinder itself as well as of the line between inlet/outlet valve and brake. The characteristic is parametrized by 3 to 20 points (p, V) as shown in the following diagram. Above and below the given points, the curve is extrapolated linearly. p p3

p2 p1 p0 v0

v1

v2

v3

V

Figure 9.12: Pressure Volume Characteristic

For the following parameters applies: ‘f’ means front or ‘r’ means rear.

Cyl_f.pv.mapping Cyl_r.pv.mapping Vector of pressure values [bar] corresponding to volume values [cm3]. It is the volume of brake fluid absorbed by the cylinder at a given pressure. It is crucial that the supporting points for the pressure rise strictly monotonic. . Syntax

Infofile table mapping with 2 columns

Example

Cyl_f.pv.mapping: 0 5 10 15 20 25 40 60 80 80 200

CarMaker Reference Manual

0.00 0.20 0.39 0.56 0.72 0.87 1.28 1.75 2.15 2.15 3.84

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Example

CarMaker Reference Manual

Cyl_f.pv.mapping: 0

0.00

Cyl_r.pv.mapping: 0 5 10 15 20 25 40 60 80 200

0.00 0.09 0.16 0.25 0.31 0.38 0.55 0.75 0.91 1.69

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9.6.8

Low pressure accumulator The low pressure accumulator accumulates the liquid coming out of the outlet valves before it is pumped back in the brake circuit. It usually consists of a cylinder with a piston loaded by a spring. The relation between the absorbed liquid and the resulting pressure is modeled by the following characteristic (the gradients below pMin and above pMax are hard-coded). p

pMax pMin vMax

v

Figure 9.13: Pressures in low pressure accumulator

LPA.vMax Maximum Volume of pressure accumulator [cm3]. Example

LPA.vMax = 5.0

LPA.pMin Pressure below which the volume is minimal [bar]. Example

LPA.pMin = 1.0

LPA.pMax Pressure above which the volume is maximal [bar]. Example

CarMaker Reference Manual

LPA.pMax = 5.0

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9.6.9

Attenuators (damper chambers) and line volumes The discrete modeling of the hydraulic system makes it necessary to alternate between apertures (flow elements) and volume elements. Therefore volume elements are positioned between pilot valve, inlet valve and the high pressure side of the pump as well as between low pressure accumulator check valve, suction valve and suction side of the pump. Those elements represent line volumes or attenuator chambers. They are modeled by proportional characteristics:

p dp2dv 1 v Figure 9.14: Proportional characteristics of attenuators and line volumes

In real brake systems, those line volumes are very small. Nonetheless for numerical reasons, those elements should not be parametrized too stiff, even if the value given doesn’t represent the real physical value.

Att.dp2dv The attenuator is situated at the high pressure side of the pump. For numerical reasons, its value should not be too high [bar/cm3]. p = dp2dv ⋅ v

Example

(EQ 65)

Att.dp2dv = 300.0

SuppL.dp2dv The suction line volume is situated at the low pressure side of the hydraulic pump. For numerical reasons, the value given should not be too high [bar/cm3]. p = dp2dv ⋅ v

Example

CarMaker Reference Manual

(EQ 66)

SuppL.dp2dv = 50.0

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9.6.10

Hydraulic pump (return pump) The pumps for both circuits are driven by the same motor. The static and dynamic characteristic of the pump can be parametrized. •

Static characteristic: -

The flow is proportional to the rotational velocity. The rotational velocity of the pump decreases with increasing pressure differences. This leads to the following relation: q ( ∆p ) = q max – c loss ⋅ ∆p

(EQ 67)

Alternatively a flow-characteristic can be specified. q ( ∆p ) = f (∆p,pump activation) -

Cavitation on the suction side. If the relative pressure on the suction side of the pump approaches -1 bar (absolute pressure 0 bar), the flow approaches to zero. This relation is modeled by a exponential saturation function starting at a limit "edge" pressure and a second pressure at which 63% of the full flow are reached:

p

–p

edge -----------------------  p 63 – p edge  q∗ = q 1 – e    

•

(EQ 68)

(EQ 69)

Dynamic characteristic: t

– -n q τ ---------- = ---------- = 1 – e n max q max

(EQ 70)

When the pump is switched on, the full rotational speed (as well as the full flow) is not reached immediately, but it increases with an exponential saturation function. This function can be parametrized by the time constant τ Full at which 63% of the full flow is reached. After switching off the pump, the rotational speed (as well as the flow) decreases exponentially with a time constant τ Zero to be given. The rotation speed of the hydraulic pump is a relative speed because it is meassured from the voltage ratio of the pump ( current voltage ⁄ maximal voltage ). It is not possible for the hyrdaulic model to calculate a absolut pump speed.

Usually brake ECUs measure the return voltage generated by the pump to detect pump engine faults. As the pump is a volumetric pump, its rotational speed is approximately proportional to the flow (which is evaluated by the equation or tables above). The model evaluates this voltage as follows: q U Ret = ----------U genVmax q max

(EQ 71)

with U genVmax q max

Maximum generated return voltage of the pump (at a pressure difference of 0 bar with no cavitation on the suction side). Flow at pressure difference 0 bar.

Alternatively a characteristic can be specified.

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All Paramaters specified for the hydraulic pump apply to a single brake cricuit (e. g. q max applies per cirquit and is not the total flow of both cirquits). But both cirquits are parametized with the same parameter (they are symetrical).

Pump.qMax Optional instead of Pump.Flow.mapping. Maximum delivery of pump. At 0 bar pressure 3 difference [ cm ⁄ ( s ⋅ bar ) ] . Example

Pump.qMax = 5.0

Pump.cLoss Optional instead of Pump.Flow.mapping. Loss Coefficient of pump. With increase of ∆p delivery efficiency will decrease. Small Pump.cLoss values are equivalent to a high efficiency 3 characteristic of the pump [ cm ⁄ ( s ⋅ bar ) ] . Example

Pump.cLoss = 0.01

Pump.Flow.mapping.Kind Optional. Determines the type of input for the characteristic Pump.Flow.mapping.: Pump.Flow.mapping.Kind

Description

Standard

Default. One dimensional input characteristic depending on activation signal expected.

PressureSignal

Two dimensional input characteristic depending an activation signal and pressure difference expected.

Example

Pump.Flow.mapping.Kind = PressureSignal

To obtain reasonable results for a hydraulic pump (flow depends on activation signal/supply voltage and pressure difference) the parameter Pump.Flow.mapping.Kind should be set to ‘PressureSignal’.

Pump.Flow.mapping Optional instead of Pump.qMax and Pump.cLoss. This characteristic holds lines with the pressure difference at the hydraulic pump [bar] the activation of the pump [0..1] and the resulting 3 delivery flow [ cm ⁄ s ] of the pump. It is assumed that Pump.Flow.mapping.Kind is set to ‘PressureSignal’! . Syntax

CarMaker Reference Manual

Infofile table mapping with 3 columns



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167 Brake System HydESP

Example

Pump.Flow.mapping: 0.0 0.0 0.0 0.0 50.0 50.0 50.0 50.0 100.0 100.0 100.0 100.0 200.0 200.0 200.0 200.0

0.0 0.25 0.5 1.0 0.0 0.25 0.5 1.0 0.0 0.25 0.5 1.0 0.0 0.25 0.5 1.0

0.0 6.4 6.8 7.0 0.0 5.3 6.1 6.6 0.0 4.0 5.3 6.3 0.0 1.8 3.6 5.1

Pump.Full Time constant τ Full when Pump is accelerating [s]. See (EQ 70). Example

Pump.Full = 0.1

Pump.Zero Time constant τ Zero when pump is deccelerating [s]. See (EQ 70). Example

Pump.Zero = 0.1

Pump.pEdge Only for pressures higher than p edge the Hydraulic pump works. Below p edge no fluid is pumped [bar]. Example

Pump.pEdge = -0.8

Pump.p63Prcnt At this pressure the pump operates at 63% of its full delivery capacity [bar]. Example

CarMaker Reference Manual

Pump.p63Prcnt = -0.5

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Pump.genVmax Optional. Generated voltage of the pump at maximum rotational speed [V], see (EQ 71). Default: 8.0 V. Example

9.6.11

Pump.genVmax = 8.0

Valves and Connecting Lines in General Pipe

Valve

dPipe

p1, V1

Pipe

p2, V2

dValve

Q

Q

l

Figure 9.15: Modeling of hydraulic valves and connecting lines

Applied to this model is that a valve with its corresponding pipe is always situated between two hydraulic reservoirs with the state variables pressure and volume. The pressure difference ∆p = p 1 – p 2

(EQ 72)

Q = Q Pipe = Q Valve = f (∆p,...)

(EQ 73)

is tried to be equalized by a flow

through the pipe and the valve aperture. The complete pressure difference ∆p calculates to: ∆p = ∆p Valve + ∆p Pipe

(EQ 74)

To solve this equation relations for the pressure portions of the flow of ∆p Valve and ∆p Pipe are needed: It is assumed that the flow through the pipe is always laminar and through the valve aperture always turbulent. •

Laminar flow through a pipe: 2

Ad Pipe Q Pipe = ---------------- ∆p = q Pipe ∆p 32lρν

(EQ 75)

with ∆p A d ρ ν q Pipe

CarMaker Reference Manual

pressure gradient (= pin- pout) cross section area of the pipe diameter pipe density kinematic viscosity flow coefficient pipe

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q Pipe can be calculated out of geometrical data using the following equation: 4

πd Pipe q Pipe = ----------------128lρν

(EQ 76)

The value of the parameter q Pipe has to be specified in: 3

3

m cm –6 [ q Pipe ] = --------------- = 10 ⋅ --------------s ⋅ bar s ⋅ bar •

(EQ 77)

Turbulent flow through a valve: 2 Q Valve = αA --- ∆p ⋅ sgn ∆p = q Valve ρ

∆p ⋅ sgn ∆p

(EQ 78)

with ∆p α A ρ q Valve

pressure gradient (= pin- pout) coefficient depending on the geometry of the aperture aperture area density flow coefficient valve aperture

q Valve can be calculated out of geometrical data using the following equation: 2

πd Valve 2 q Valve = α ----------------- --4 ρ

(EQ 79)

The value of the parameter q Valve has to be specified in: 3

3

m cm –6 [ q Valve ] = --------------- = 10 ⋅ --------------s bar s bar

(EQ 80)

Combining (EQ 73), (EQ 74), (EQ 75) and (EQ 78) leads to: Q 2 Q ∆p ( Q ) =  -------------- + ---------- q Valve q Pipe

(EQ 81)

This relation between pressure difference and flow is valid for all modeled valves. Variations are characterized through q Valve and q Pipe .

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9.6.12

Solenoid valves The solenoid valves are controlled by the power of the magnetic field through the magnetic coils. Basically two different kind of solenoid valves are distinguished: •

Digital valves have activation signals that normally either completely open (full activation) or completely close (zero activation) a valve.

•

Proportional valves also have activation signals other than zero or full activation. An activation between zero and full may lead to intermediate opening states of the valve. SignalConditioning

analog RawSignal

MeasureSignal

CAL Activation Signal

MeasureSignal

Magnetic

Sensor

or digital Activation Signal (0 or 1)

HydESP Hydraulic Model

Target Valve Position HydESP Brake Interface

SignalAcquisition

Valve Dynamics ⇒ actual valve pos.

Flow Rate through Valve

t➞∞

f (act,∆p)

f ( ∆p )

f (∆p,...)

∆p: Pressure Difference at Valve p1 = f ( V 1 ) p2 = f ( V 2 )

∆p = p 1 – p 2

Integration of Flow V 1 = V 1 – ∫ Q ( 1 ⇒ 2 ) dt V 2 = V 2 + ∫ Q ( 1 ⇒ 2 ) dt

Figure 9.16: From detection to calculation of a hydraulic valve

The interface between the ECU and the simulated hydraulic block is at the magnetic coil. Figure 9.16 shows the process from sensing the valve position up to the calculation of the volume transferred through the valve and the connected pipe. There are two possibilities for the acquisition of the valve activation signals. For proportional valves the acquiring method has to be analog in order to capture intermediate valve positions. A raw signal captured from the sensor is converted by a calibration function into the measure signal (typically it is the voltage output signal of a hall sensor). After that the measure signal has to be converted into a standardized valve activation signal. This is the input signal for each solenoid valve to the brake interface. The same standardized activation signal is delivered from the digital valve acquisition. It is the digital signal itself which is characterized by the states zero and one. An alternative method for capturing digital valves is to use the analog signal acquisition. The signal conditioning part is used to define a threshold for valve activity. After the activation signal of each valve is stored in the brake interface structure the calculation process within the brake model can be initiated. The intermediate state (without dynamics, t ➞ ∞) of a proportional valve is a function of the activation signal and the pressure difference of the valve. This is called the target valve position. Because there is no pressure dependency for digital valves this function is a one to one relation of the activation signal.

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The time response (so to speak when the target valve position is reached) is calculated by the valve dynamics function. The opening time and closing time for the valve can be specified. As well, the opening/closing times are functions of the pressure difference. The result is the standardized actual valve position. The actual valve position is input for the flow rate calculation of the valve/pipe system. In this context it is considered as a relative valve opening. The relative valve opening αrel [0..1] is defined as: q valve α rel = -------------------q valve, max

(EQ 82)

q valve, max is the maximum flow rate which is reached with a fully opened valve (actual valve position = 1). The calculation of the flow is done by (EQ 81) considering (EQ 82).

With the knowledge of the actual flow through the valve/pipe system the volume change of the two bounding reservoirs can be calculated by integration of flow. This is shown in Figure 9.16 at the lower part of the HydESP section. The pressure difference of the valve is a central part for the calculation. It can be positive or negative. Here, the pressure difference is defined to be positive if the input pressure is higher than the output pressure, with the following definitions of inputs and outputs:

CarMaker Reference Manual

valve

input side

output side

inlet valve

pressure side pump

wheel brake

outlet valve

wheel brake

low pressure accumulator

pilot valve

pressure side pump

master cylinder

suction valve

master cylinder

suction side pump

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9.6.13

Proportional Solenoid Valves All solenoid valves can be proportional or digital valves. For the proportional valves a transfer mapping characteristic has to be specified to obtain the relative opening of the valve depending on the activation signal and the current pressure difference at the valve. A relative opening of 1 means that the valve is completely opened, 0 means completely closed. This is important because there are valves that are closed when activated (activation signal 1 results in a relative opening of 0), or opened when activated (activation signal 1 results in a relative opening of 1)

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Inlet_f.transfer.mapping.Kind Inlet_r.transfer.mapping.Kind Outlet_f.transfer.mapping.Kind Outlet_r.transfer.mapping.Kind PV.transfer.mapping.Kind SV.transfer.mapping.Kind Optional. Determines the Inlet_.transfer.mapping.:

type

of

input

fo r

the

characteristic

.transfer.mapping.Kind

Description

Standard

Default. One dimensional input characteristic depending on activation signal expected.

PressureSignal

Two dimensional input characteristic depending an activation signal and pressure difference expected.

Inlet_f.transfer.mapping: Inlet_r.transfer.mapping: Outlet_f.transfer.mapping: Outlet_r.transfer.mapping: PV.transfer.mapping: SV.transfer.mapping: Optional. Used to calculate the target valve position of the valve. See Figure 9.16. Syntax depending on Inlet_.transfer.mapping.Kind (see above): •

Standard:

Characteristic specifying values for relative valve opening [0..1] depending on valve activation signal [0..1].. Syntax

Infofile table mapping with 2 columns

Example

Inlet_.transfer.mapping: 0.0 1.0 0.5 0.6 1.0 1.0

•

PressureSignal: Characteristic specifying values for relative valve opening [0..1] depending on pressure difference [bar] and valve activation signal [0..1].

Syntax

Example

CarMaker Reference Manual

Infofile table mapping with 3 columns



Inlet_f.transfer.mapping.Kind = PressureSignal Inlet_f.transfer.mapping: 0.0 0.3 1.0 0.0 0.5 0.0 100 0.5 1.0 100 0.8 0.0

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Dynamic Solenoid Valves All solenoid valves no matter if they are proportional or digital can have a different dynamic behavior depending on the current pressure difference at the valve. At higher pressures valves usually open faster and close slower. This behavior is specified with the following parameters:

Inlet_f.deltaT.mapping: Inlet_r.deltaT.mapping: Outlet_f.deltaT.mapping: Outlet_r.deltaT.mapping: PV.deltaT.mapping: SV.deltaT.mapping: Optional. Used to calculate valve dynamics and the actual valve position. Characteristic specifying values for opening time [s] and closing time [s] of the valve depending on the pressure difference at the valve [bar]. The durations specify the time for open a completely closed valve and vice versa. Syntax

Example

CarMaker Reference Manual

Infofile table mapping with 3 columns IInlet_f.deltaT.mapping: 100 0.002 200 0.001 0 0.01



0.01 0.01 0.01

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Inlet Valves with check valve The inlet valve (or supply valve) is situated before the wheel brake. A check valve is positioned parallel to the inlet valve. It is opened if the pressure in the wheel brake becomes higher than on the inlet side. When not driven, inlet valves are opened (flow through valve is possible). Usually, inlet valves are digital or proportional 2/2-valves. But there are also systems with valves that have a variable aperture. Those valves have a small and a big aperture, the switching between them is done by a mechanical system depending on the pressure difference: aperture size

lower threshold

upper threshold

big

small

p Sm2Gr

p Gr2Sm

∆p

Figure 9.17: Switching between different aperture sizes

pressure difference

switch to

lower than lower threshold

big aperture

higher than upper threshold

small aperture

For the following parameters applies: ‘f’ means front or ‘r’ means rear.

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For valves with unswitched apertures:

Inlet_f.qOri Inlet_r.qOri Flow coefficient of valve without switched apertures (‘Ori’ = Orifice = Aperture) 3 [ cm ⁄ ( s ⋅ bar ) ] . Example

Inlet_f.qOri = 4.0

For valves with switched apertures:

Inlet_f.qOriGr Inlet_r.qOriGr Flow coefficient of valve when switched to big aperture (‘Ori’ = Orifice = Aperture) 3 [ cm ⁄ ( s ⋅ bar ) ] . Example

Inlet_f.qOriGr = 4.0

Inlet_f.qOriSm Inlet_r.qOriSm Flow coefficient of valve when switched to small aperture (‘Ori’ = Orifice = Aperture) 3 [ cm ⁄ ( s ⋅ bar ) ] . Example

Inlet_f.qOriGr = 2.8

Inlet_f.pSm2Gr Inlet_r.pSm2Gr Limit pressure below which valve switches from “small” to “big” aperture [bar]. See Figure 9.17. Example

Inlet_f.pSm2Gr = 14.0

Inlet_f.pGr2Sm Inlet_r.pGr2Sm Limit pressure above which valve switches from “big” to “small” aperture [bar]. See Figure 9.17. Example

CarMaker Reference Manual

Inlet_f.pGr2Sm = 18.0

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For all inlet valves:

Inlet_f.qPipe Inlet_r.qPipe 3

Optional. Overall flow coefficient of pipe in front and behind the valve [ cm ⁄ ( s ⋅ bar ) ] . Default: 106. Example

Inlet_f.qPipe = 10000

Inlet check valves:

InCheckV_f.qOri InCheckV_r.qOri Flow coefficient of check valve situated beside inlet valve (‘Ori’ = Orifice = Aperture) 3 [ cm ⁄ ( s ⋅ bar ) ] . Example

InCheckV_f.qOri = 6.0

InCheckV_f.qPipe InCheckV_r.qPipe 3

Optional. Overall flow coefficient of pipe of check valve [ cm ⁄ ( s ⋅ bar ) ] . Usually this is the same as Inlet_.qPipe. Default: 106. Example

InCheckV_f.qPipe = 20000

Outlet Valves The outlet valves (or: discharge valves) are situated behind the wheel brake. When not driven, the outlet valves are closed.

Outlet_f.qOri Outlet_r.qOri 3

Flow coefficient of outlet valve (‘Ori’ = Orifice = Aperture) [ cm ⁄ ( s ⋅ bar ) ] . Example

CarMaker Reference Manual

Outlet_f.qOri = 4.0

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Outlet_f.qPipe Outlet_r.qPipe 3

Optional. Overall flow coefficient of pipe before and after the outlet valve [ cm ⁄ ( s ⋅ bar ) ] . Default: 106. Example

CarMaker Reference Manual

Outlet_f.qPipe = 100000

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9.6.16

Pilot valve with check valve and pressure limiting valve The pilot valves are used to separate the brake circuit from the master cylinder. This allows the system autonomously to generate a brake pressure in the circuit. When not driven, the pilot valves are open. A check valve is positioned parallel to the pilot valve. It opens if the pressure in the master cylinder is higher than the one in the circuit. A pressure limiting valve is positioned parallel to the pilot valve as well. It opens if the pressure in the brake circuit is higher than the pressure limit. In this case, the flow is calculated as follows: Q PLim = q PLimValve ⋅

∆p – p Limit ⋅ sgn ∆p

(EQ 83)

The pressure limiting valve is then modeled by the relationship 2 Q Q ∆p ( Q PLim ) = p Open +  ------------------------ + --------------------- q PLimValve q PLimPipe

(EQ 84)

Pure ABS systems don’t have pilot valves. For ABS systems use a relatively high value for the flow coefficient. Be careful with too high values and check numerical stability.

PV.qOri 3

Flow coefficient of pilot valve (‘Ori’ = Orifice = Aperture) [ cm ⁄ ( s ⋅ bar ) ] . Example

PV.qOri = 5.0

PV.qPipe 3

Optional. Overall flow coefficient of pipe before and after the pilot valve [ cm ⁄ ( s ⋅ bar ) ] . Default: 106. Example

PV.qPipe = 20000

PLim.qOri 3

Flow coefficient of pressure limiting valve (‘Ori’ = Orifice = Aperture) [ cm ⁄ ( s ⋅ bar ) ] . Example

PLim.qOri = 5.0

PLim.qPipe Optional. Overall flow coefficient of pipe before and after the pressure limiting valve 3 [ cm ⁄ ( s ⋅ bar ) ] . Usually set to the same value as PV.qPipe. Default: 106. Example

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PLim.qPipe = 20000

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PLim.pOpen At a pressure difference superior to PLim.pOpen, the pressure limiting valve opens [bar]. Example

PLim.pOpen = 180.0

PVcheckV.qOri 3

Flow coefficient of check valve (‘Ori’ = Orifice = Aperture) [ cm ⁄ ( s ⋅ bar ) ] . Example

PVcheckV.qOri = 5.0

PVcheckV.qPipe 3

Optional. Overall flow coefficient of pipe before and after the check valve [ cm ⁄ ( s ⋅ bar ) ] . Usually set to the same value as PV.qPipe. Default:106. Example

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PVcheckV.qPipe = 20000

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9.6.17

Suction valve In case of an autonomous brake pressure generation, this valve enables the hydraulic pump to take liquid out of the master cylinder. When not driven, they are closed. The suction valve is situated between the master cylinder and the low pressure side of the hydraulic pump. Pure ABS systems don have suction valves. For ABS systems use a relatively high value for the flow coefficient. Be careful with too high values and check numerical stability.

SV.qOri 3

Flow coefficient of suction valve (‘Ori’ = Orifice = Aperture) [ cm ⁄ ( s ⋅ bar ) ] . Example

SV.qOri = 10.0

SV.qPipe 3

Optional. Overall flow coefficient of pipe before and after the suction valve [ cm ⁄ ( s ⋅ bar ) ] . Default: 106. Example

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SV.qPipe = 20000

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9.6.18

Check Valve of the Low Pressure Accumulator This valve is situated between the low pressure accumulator and the low pressure side of the hydraulic pump. The purpose of this valve is to inhibit the flow trough the suction valve to the low pressure accumulator. It opens when the pressure on the low pressure accumulator side is higher then the one on the hydraulic pump side.

LPAcheckV.qOri Flow coefficient of low pressure accumulator check valve (‘Ori’ = Orifice = Aperture) 3 [ cm ⁄ ( s ⋅ bar ) ] . Example

LPAcheckV.qOri = 6.0

LPAcheckV.qPipe Optional. Overall flow coefficient of pipe before and after the low pressure accumulator 3 check valve [ cm ⁄ ( s ⋅ bar ) ] . Default: 106. Example

LPAcheckV.qPipe = 20000

Temperature of the Brake Fluid In consequence of a temperature change of the hydraulic fluid the mass density ρ and the kinematic viscosity ν of the fluid change as well. Apparently the equations (EQ 75) and (EQ 78) show the following relations: 1 1 q valve ∼ ------- and q pipe ∼ ------ . ρν ρ

(EQ 85)

This means that parameter values for q valve and q pipe specified in the hydraulic dataset are only valid for a specific reference temperature T Ref which usually equals the ’normal’ operation temperature.

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Investigations about the significance of the relations ρ ( T ) and ν ( T ) point out clearly that there is a negligible temperature influence of the mass density and a significant temperature dependence of the kinematic viscosity. This means that a change of temperature is only relevant for the flow coefficients of the hydraulic pipes.

Figure 9.19: Change of kinematic viscosity and mass density of hydraulic fluid as a function of temperature

The flow parameters of the lines are specified by the user for a specific reference temperature. If the brake should operate at a temperature that differs from the reference temperature, the operating temperature can be changed to an alternative value (input from brake interface). The flow characteristics are then adapted automatically by the brake model with the given characteristics for the hydraulic fluid. In order to parametrize the properties of the brake fluid, kinematic viscosities for two different temperatures have to be given. Those two points are then used by the model to determine the coefficients in its viscosity function. The hydraulic model uses the following approach to scale the flow coefficients to the specific operating temperature. A factor ν Ref nf = -------νT

(EQ 86)

with nf v Ref νT

CarMaker Reference Manual

Scaling factor, Kinematic viscosity of brake fluid at reference temperature, Kinematic viscosity of brake fluid at the specified operating temperature of the brake,

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is used to recalculate the flow coefficients to ν Ref q pipe, T = nf ⋅ q pipe = --------- ⋅ q pipe νT

(EQ 87)

To calculate the kinematic viscosities the following approach is used, log ( log ν ) = c ⋅ T + k ,

(EQ 88)

with the coefficients c, k of the linear equation on the right side: ( log ( log ν 2 ) ) – ( log ( log ν 1 ) ) c = ----------------------------------------------------------------------T2 – T1

k = ( log ( log ν 1 ) ) – c ⋅ T 1 .

(EQ 89)

The reference kinematic viscosity is the viscosity according to (EQ 88) for the temperature T Ref :

ν Ref = 10

10

c ⋅ T Ref + k

.

(EQ 90)

Fluid.Ref.Temp Optional. Reference temperature. Temperature of the hydraulic fluid at which the specified flow coefficients are valid. Dimension: K. Default: no default value, temperature dependency of the brake fluid is switched on by specifying this parameter. Fluid.Ref.Temp = 293 If the parameter Fluid.Ref.Temp is specified the following 4 parameters are mandatory.

The viscosity of the brake liquid has to be indicated for two temperatures:

Fluid.P1.Temp Temperature T 1 to determine linear equation according to (EQ 88) [K]. Example

Fluid.P1.Temp = 233

Fluid.P1.nue Viscosity ν 1 to determine linear equation according to (EQ 88) [mm2/s]. Example

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Fluid.P1.nue = 1150

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Fluid.P2.Temp Temperature T 2 to determine linear equation according to (EQ 88) [K]. Example

Fluid.P2.Temp = 273

Fluid.P2.nue Viscosity ν 2 to determine linear equation according to (EQ 88) [mm2/s]. Example

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Fluid.P2.nue = 40

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9.6.19

User Accessible Quantities for Brake Module ‘HydESP’ Name

Unit

Info

Brake.HydESP.Att_0.p

bar

Pressure of Attenuator 0

Brake.HydESP.Att_1.p

bar

Pressure of Attenuator 1

Brake.HydESP.LPA_0.p

bar

Pressure of low pressure accumulator 0

Brake.HydESP.LPA_1.p

bar

Pressure of low pressure accumulator 1

Brake.HydESP.SuppL_0.p

bar

Pressure of supply line 0

Brake.HydESP.Cyl_p_FL

bar

Pressure of brake cylinder front left

Brake.HydESP.Cyl_p_FR

bar

Pressure of brake cylinder front right

Brake.HydESP.Cyl_p_RL

bar

Pressure of brake cylinder rear left

Brake.HydESP.Cyl_p_RR

bar

Pressure of brake cylinder rear right

m

3

Volume of brake cylinder front left

m

3

Volume of brake cylinder front righ

m

3

Volume of brake cylinder rear left

Brake.HydESP.Cyl_v_RR

m

3

Volume of brake cylinder rear right

Brake.HydESP.SuppL_1.p

bar

Pressure of supply line 1

Brake.HydESP.nPump

1/s

Rotation speed of hydraulic pump engine

Brake.HydESP.qIN_FL

m ⁄s

Brake.HydESP.Cyl_v_FL Brake.HydESP.Cyl_v_FR Brake.HydESP.Cyl_v_RL

Brake.HydESP.qIN_FR Brake.HydESP.qIN_RL

3

Volume flow through inlet valve front left

3

Volume flow through inlet valve front right

3

Volume flow through inlet valve rear left

3

m ⁄s m ⁄s

Brake.HydESP.qIN_RR

m ⁄s

Volume flow through inlet valve rear right

Brake.HydESP.qOUT_FL

m ⁄s

3

Volume flow through outlet valve front left

3

Volume flow through outlet valve front right

3

Volume flow through outlet valve rear left

3

Volume flow through outlet valve rear right

Brake.HydESP.qOUT_FR Brake.HydESP.qOUT_RL

m ⁄s m ⁄s

Brake.HydESP.qOUT_RR

m ⁄s

Brake.HydESP.qPV_0

m ⁄s

3

Volume flow through pilot valve 0 see section ’CircuitConfig’

Brake.HydESP.qPV_1

m ⁄s

3

Volume flow through pilot valve 1 see section ’CircuitConfig’

Brake.HydESP.qPu_0

m ⁄s

3

Volume flow through hydraulic pump 0

3

Volume flow through hydraulic pump 1

Brake.HydESP.qPu_1

m ⁄s

Brake.HydESP.qSV_0

m ⁄s

3

Volume flow through suction valve 0

3

Volume flow through suction valve 1

Brake.HydESP.qSV_1

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Overview

Chapter 10

Tire

10.1

Overview The quality of a vehicle dynamics simulation is heavily influenced by the capabilities of the tire model. This chapter describes the basic outline of tire models used with CarMaker.

Axis system for the tire-road contact point

z x y

C

Fr2 z x y

z x

P

FrH Fz

y

Fr0

Figure 10.1: Tire Axis system FrH

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Overview

There are two points of interest concerning a tire model, the wheel center C and the tireroad contact point P. The axis system Fr2 which origins in C is explained in section 1.2 ’CarMaker Axis Systems’. Furthermore there is a axis system FrH which has its origin in the tire-road contact point. FrH is defined as follows: •

Rules apply to any tire of the vehicle

•

(O) is located on the intersecting line of the tire vertical plane and the tangential plane of the road. It is defined as the point of the shortest distance min ( CP ) on the intersecting line.

•

(X) points in forward direction of the intersecting line between tire vertical plane and tangential plane of the road.

•

(Y) points to the left side rectangular to (X) in the tangential plane of the road.

•

(Z) points in direction of the normal vector of the tangential plane of the road (mathematically: ( X ) × ( Y ) ).

CarMaker supports tire models formulated for the tire-road contact point. The duty of the tire model is to calculate the tire response forces and torques. Basically the tire forces and torques are functions of: F, T = f ( F z, α, s, γ , µ, ... )

(EQ 91)

with Fz α s γ µ

CarMaker Reference Manual

Normal force in tire contact point Side slip angle Longitudinal slip Camber angle Friction coefficient between tire and road

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Overview

10.1.1

Tire Interface all parameters are related to FrH

Inputs

v

Outputs

(P)

v Belt

F

(P)

(P)

Fz

Tire Model

γ µ

T

(P)

(P)

Figure 10.2: Structure of Tire Interface

A CarMaker tire model is provided from the vehicle model with the inputs depicted in Figure 10.2. Beside the ones explained with Figure 10.1 they are: v

(P)

v Belt

Velocity vector in the tire-road contact point Velocity of the tire belt in the tire-road contact point

The outputs of the tire model are according to Figure 10.1: (P)

F (P) T

CarMaker Reference Manual

Tire forces in the tire-road contact point Torques in the tire-road contact point

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Overview

10.1.2

Tire load (normal force) The tire load is calculated by the vehicle model and is direct input to the tire model. This section explains how the tire normal force is calculated. vertical damping

C(t)

vertical stiffness

CP ( t )

l(t)

R0

Fz P ( t ) P0

Figure 10.3: Calculation of tire normal load

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Overview

10.1.3

Tire Model Computations The job of the tire model is to deduce the parameters of (EQ 91) out of the inputs of the tire interface. This means that the parameters side slip angle and longitudinal slip, which are not specified directly, have to be calculated by the tire model.This has to be done by a relation: α, s = f ( v

(P)

, v Belt )

(EQ 92)

The computation of internal models is explained in the sections below corresponding to the tire models offered by CarMaker.

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General Tire Parameters

10.2

General Tire Parameters The parameters explained here apply to (various) tire models. All tire parameters are stored in a separate tire date file.

General

FileIdent = CarMaker-Tire-* The first parameter has to be the FileIdent parameters which specifies the type and version of tire model to be used. See chapter 1.6.2 for details. FileIdent

Version

Description

RTTire

2,3

RealTime version of IPG-TIRE

MF52

3

Pacejka’s Magic Formula

Example

CarMaker-Tire-RTTire 3

FileCreator =

Comment

Optional. String containing formless informations about the file creator.

Description:

Text

Description contains formal informations of tire details, e. g. tire dimensions, inflation pressure, conditions of measurement, etc.

Carrier.mass = Carrier.I =

Mass InertiaTensor

Optional. Part in wheel carrier mass. The support for this parameters depends on the vehicle model. The place of this body is taken from the vehicle parameter set.

Wheel.mass = Wheel.I =

Mass InertiaTensor

Optional. Part in wheel mass. The support for this parameters depends on the vehicle model. The place of this body is taken from the vehicle parameter set.

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Tire Model RT-Tire

10.3

Tire Model RT-Tire Tire Model RT-Tire is a modified version of IPG-TIRE. This version is optimized for computation speed and designed for using in realtime systems.

Visualization

AspectRatio Optional. Represents ratio between rim radius and witdth [-].

NomWidth Optional. Nomimal width of the tire [m].

NomRadius Optional. Nominal radius of tire used for the animation tool IPG-MOVIE [m].

RimRadius Optional. Nominal radius of rim used for the animation tool IPG-MOVIE [m].

FLoadMax Optional. Maximum animated load force of tire. Used to scale the tire force vectors in the animation tool IPG-MOVIE [N]. Model Ident

muRoad Friction conditions during tire measurement [-].

BinFName File name with relative path to Data/Tire directory. Tire force and torque mappings may be stored in a binary file located in this directory.

Kinematics and Load Force

KinRollRadius Kinematic tire radius (also known as static tire radius) [m].

Radial.Stiffness Radial/vertical stiffness of tire [N/m].

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Tire Model RT-Tire

Radial.Damping Radial/vertical damping coefficient of tire [N/m/s].

Dynamics

LongFrc.Length SideFrc.Length AlignTrq.Length Relaxation lengths. [m]

Stand Still

vMinSlip vMinAlpha Optional. Boundary for switching between stand still model and normal computation [m/s].

StandStill.cLong = StandStill.cSide =

Stiffness Stiffness

Optional. Stiffness for stand stil model [-]. Additional Internal Parameters

LongFrc.Stiffness = SideFrc.Stiffness = AlignTrq.Stiffness =

Factor Factor Factor

Optional. Scaling factors[-].

InclinAngle2Alpha Optional. Camber influence to side slip angle. The actual camber value multiplied by this factor is added to the side slip angle value [-].

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Tire Model RT-Tire

10.3.1 Roll Resistance

Rolling Resistance RollResist.Kind =

KindStr

The following roll resistance models are known: Torque of force influence based on Load or velocity.There KindStr are: KindStr

Description

TrqLoad

A torque along wheel spin axis, against rotation based on load force.

TrqVelocity

A torque along wheel spin axis, against rotation based on translation velocity.

FLoad

A force along FrH x axis, against translation based on load force.

FVelocity

A force along FrH x axis, against translation based on translation velocity.

To disable roll resistance write none or an empty string.

RollResist.Factor Kind dependent Factor. Input is scaled by Factor to get the roll resistance output [-].

10.3.2

Importing Tire Measurements The supported input file format is the Tydex format. The Tydex file can be imported by tireutil TydexFileName.tdx The following Tydex model parameters are supported:

ITVS = ITVD = ITRLLO = ITRLLA = ITSSCLO = ITSSCLA = ITRORETL =

CarMaker Reference Manual

RadialTireStiffness_N/m RadialDamping_N/m/s RelaxationLengthLong_m RelaxationLengthLateral_m StandStillCoeffLong StandStillCoeffLateral RollResistFactor_Trq/Load

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Tire Model Magic Formula

10.4

Tire Model Magic Formula

10.4.1

The basics of Magic Formula When possible “original” Pacejka’s variable and parameter names are used. For background information, you can use publications on Pacjeka tire modeling, magic formula or in Hans B. Pacejka book “Tyre and Vehicle Dynamics” published in november 2002. The general form of the formula reads: y ( x ) = D sin [ C atan { Bx – E ( Bx – atan Bx ) } ]

(EQ 93)

with Y ( X ) = y ( x ) + SV x = X + SH

where: Y ( X ) : could be either F x or F y or possibly M z (in this case the sine function is replaced by a cosine function.

The variables represents as follows: B : stiffness factor C : shape factor D : peak value E : curvature factor S H : horizontal shift S V : vertical shift

y

Y

xm SH

D

ya x X

SV

atan(BCD) Figure 10.4: Curve produced by the original sine version of the Magic Formula

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Tire Model Magic Formula

The Magic Formula y ( x ) typically produces a curve that passes through the origin x = y = 0 , reaches a maximum and tends to a horizontal asymptote. To allow the curve to have an offset with respect to origin, two parameters for shifting ( S H and S V )have been introduced The MagicFormula model equation contains non-dimensional parameters p , q , r and s and additional scaling factors λ . These parameters are used to parametrize a special tire behavior. The effect of having a tire with different nominal load can be approximated by using a scaling factor: ′

F zo = λ Fzo F zo

(EQ 94)

Further, we introduce the normalized change in vertical load ′

F z – F zo d f z = -----------------′ F zo

CarMaker Reference Manual

(EQ 95)

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Tire Model Magic Formula

10.4.2 General

Tire Description AdamsPropertyFile =

PropertyFile

Optional. Link to an ADAMS® tire property file. Its path is relative to directory Data/Tire. Supported Formats: MF_05 Caution. All parameters listed below can be used to redefine a tire property. This means parameters from AdamsPropertyFile have lower priority than or will be overwritten by parameters given in the tire data set directly. This feature is very useful if you are tuning a measured tire data set.

Dimensions and Visualization

Range.FZMAX Optional. Maximum load force of tire. Used to scale the tire force vectors in the animation tool IPG-MOVIE. If this parameter is missing the value from 2*Vertical.FNOMIN is used [N].

Dim.UNLOADED_RADIUS Free tire radius also used for the animation tool IPG-MOVIE [m].

Dim.WIDTH Tire width also used for the animation tool IPG-MOVIE [m].

Dim.RIM_RADIUS Rim radius also used for the animation tool IPG-MOVIE [m].

Dim.RIM_WIDTH Rim width also used for the animation tool IPG-MOVIE [m].

Vertical.VERTICAL_STIFFNESS Radial/vertical stiffness of tire [N/m].

Vertical.VERTICAL_DAMPING Radial/vertical damping coefficient of tire [N/m/s].

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Tire Model Magic Formula

10.4.3 Scale

Scale factors Scale.LFZ0 Optional. Scale factor of nominal load [-]. Default: 1.

Scale.LCX Optional. Scale factor of F x shape factor [-]. Default: 1.

Scale.LMUX Optional. Scale factor of F x peak friction coefficient [-]. Default: 1.

Scale.LEX Optional. Scale factor of F x curvature factor [-]. Default: 1.

Scale.LKX Optional. Scale factor of F x slip stiffness [-]. Default: 1.

Scale.LHX Optional. Scale factor of F x horizontal shift [-]. Default: 1.

Scale.LVX Optional. Scale factor of F x vertical shift [-]. Default: 1.

Scale.LGAX Optional. Scale factor of camber for F x [-].Default: 1.

Scale.LCY Optional. Scale factor of F y shape factor [-]. Default: 1.

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Scale.LMUY Optional. Scale factor of F y peak friction coefficient [-]. Default: 1.

Scale.LEY Optional. Scale factor of F y curvature factor [-]. Default: 1.

Scale.LKY Optional. Scale factor of F y cornering stiffness [-]. Default: 1.

Scale.LHY Optional. Scale factor of F y horizontal shift [-]. Default: 1.

Scale.LVY Optional. Scale factor of F y vertical shift [-]. Default: 1.

Scale.LGAY Optional. Scale factor of camber for F y [-].Default: 1.

Scale.LTR Optional. Scale factor of peak of pneumatic trail [-]. Default: 1.

Scale.LRES Optional. Scale factor for offset of residual torque [-]. Default: 1.

Scale.LGAZ Optional. Scale factor of camber for M z [-].Default: 1.

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Scale.LMX Optional. Scale factor of overturning couple [-]. Default: 1.

Scale.LVMX Optional. Scale factor of M x vertical shift [-]. Default: 1.

Scale.LMY Optional. Scale factor of rolling resistance torque [-]. Default: 1.

Scale.LXAL Optional. Scale factor of α influence on F x [-]. Default: 1.

Scale.LYKA Optional. Scale factor of κ influence on F y [-]. Default: 1.

Scale.LVYKA Optional. Scale factor of κ induced F y [-]. Default: 1.

Scale.LS Optional. Scale factor of moment arm of F x [-]. Default: 1.

Scale.LSGKP Optional. Scale factor of relaxation length of F x [-]. Default: 1.

Scale.LSGAL Optional. Scale factor of relaxation length of F y [-]. Default: 1.

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Tire Model Magic Formula

Scale.LGYR Optional. Scale factor of gyroscopic torque [-]. Default: 1. Example

A l l p a ra m e t e r s a r e t a ke n f r o m t h e r e fe r e n c e d A DA M S ® t i r e p r o p e r t y f i l e DT_Pacejca.tir, in the directory Data/Tire/Pacejka. The vertical stiffness from the referenced file is overwritten: The value 400000 N/m is used instead. FileIdent =CarMaker-Tire-MF52 2 Description: ADAMS Pacejka parameter set AdamsPropertyFile =Pacejka/DT_Pacejka.tir Vertical.VERTICAL_STIFFNESS = 400000

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Tire Model Magic Formula

10.4.4

Effective tire rolling radius The effective rolling radius is defined for a wheel the tire of which is uniform and rolls freely at constant speed over an even horizontal surface.It reads: V R e = ------x Ω

R0

(EQ 96)

Ω Vx

C

Re

S

Figure 10.5: Effective rolling radius

In general the effective rolling radius will change with tire deflection ρ . Assuming the tire has a constant vertical stiffness C z , the deflection is calculated with: F ρ = -----zCz

(EQ 97)

The effective rolling radius is estimated by the Magic Formula (A3.7) which reads:

Effective rolling radius

R e = R 0 – ρ Fz0 ( Fρ d + D atan ( Bρ d ) )

(EQ 98)

F z0 ρ Fz0 = ------Cz

(EQ 99)

ρ ρ d = --------ρ Fz0

(EQ 100)

Vertical.BREFF Low load stiffness of effective rolling radius [-].

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Tire Model Magic Formula

Vertical.DREFF Peak value of effective rolling radius [-].

Vertical.FREFF High load stiffness of effective rolling radius [-].

Vertical.FNOMIN Nominal wheel load [N].

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10.4.5

Slip computation

VCx VCy

Vsx α Vsy

V

VS Figure 10.6: Slip computation

The longitudinal slip speed is defined as: V sx = V Cx – ΩR e

(EQ 101)

which results in a definition of longitudinal slip: V sx κ = – --------V Cx

(EQ 102)

V sy = V y

(EQ 103)

The lateral slip speed is defined as:

which results in a definition of lateral slip: V sy tan α = -----------V Cx

(EQ 104)

V sy α = atan -----------V Cx

(EQ 105)

V r = Re Ω

(EQ 106)

and a definition of side slip angle:

The rolling speed becomes:

In case the complete model including transient properties is used, the transient tire quanti′ ′ ties κ and α (see (EQ 194), (EQ 195)) are used instead of the wheel slip quantities κ and α.

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10.4.6

Longitudinal force (pure longitudinal slip): F xo = D x sin [ C x atan { B x κ x – E x ( B x κ x – atan ( B x κ x ) ) } ] + S Vx

(EQ 107)

κ x = κ + S Hx

(EQ 108)

C x = p Cx1 ⋅ λ Cx

( > 0)

(EQ 109)

( > 0)

Dx = µx ⋅ Fz ⋅ ζ1 *

µ x = ( p Dx1 + p Dx2 d f z ) ⋅ λ µx

(EQ 110)

( > 0)

(EQ 111)

2

E x = ( p Ex1 + p Ex2 d f z + p Ex3 d f z ) ⋅ { 1 – p Ex4 sgn ( κ x ) } ⋅ λ Ex ( ≤ 1 )

(EQ 112)

K xκ = F z ⋅ ( p Kx1 + p Kx2 d f z ) ⋅ exp ( p Kx3 d f z ) ⋅ λ Kxκ

(EQ 113)

K xk B x = ----------------------------( Cx Dx + εx )

(EQ 114)

S Hx = ( p Hx1 + p Hx2 d f z ) ⋅ λ Hx

(EQ 115) ′

S Vx = F z ⋅ ( p Vx1 + p Vx2 d f z ) ⋅ λ Vx ⋅ λ µx ⋅ ζ 1

(EQ 116)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: •

The (EQ 111) changes to 2

µ x = ( p Dx1 + p Dx2 d f z ) ⋅ ( 1 – p Dx3 γ x ) ⋅ λ µx ( > 0 )

(EQ 117)

γ x = γ ⋅ λ γx

(EQ 118)

with

Longitudinal (pure slip)

′

•

In (EQ 116) λ µx instead of λ µx

•

in (EQ 110) and (EQ 116) ζ 1 is set to one.

used.

Long.PCX1 Shape factor for longitudinal force [-].

Long.PDX1 Longitudinal friction µ x at F znom [-].

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Long.PDX2 Variation of friction µ x with load [-].

Long.PDX3 Variation of friction µ x with camber [-].

Long.PEX1 Longitudinal curvature at F znom [-].

Long.PEX2 Variation of curvature with load [-].

Long.PEX3 Variation of curvature with load squared [-].

Long.PEX4 Factor in curvature while driving [-].

Long.PKX1 Longitudinal slip stiffness at F znom [-].

Long.PKX2 Variation of slip stiffness with load [-].

Long.PKX3 Exponent in slip stiffness with load [-].

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Long.PHX1 Horizontal shift at F znom [-].

Long.PHX2 Variation of shift with load [-].

Long.PVX1 Vertical shift at F znom [-].

Long.PVX2 Variation of shift with load [-].

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10.4.7

Lateral force (pure side slip): F yo = D y sin [ C y atan { B y α y – E y ( B y α y – atan ( B y α y ) ) } ] + S Vy *

(EQ 119)

α y = α + S Hy

(EQ 120)

C y = p Cy1 ⋅ λ Cy

(EQ 121)

Dy = µy ⋅ Fz ⋅ ζ2

(EQ 122) *2

*

µ y = ( p Dy1 + p Dy2 d f z ) ⋅ ( 1 – p Dy3 γ ) ⋅ λ µy *

E y = ( p Ey1 + p Ey2 d f z ) ⋅ { 1 – ( p Ey3 + p Ey4 γ ) sgn ( α y ) } ⋅ λ Ey

(EQ 123)

( ≤ 1)

   Fz  ′ K yαo = p Ky1 F zo sin  2 atan  -----------------⋅ λ Kyα ′     p Ky2 F zo  *

(EQ 124)

(EQ 125)

2

K yα = K yαo ⋅ ( 1 – p Ky3 γ ) ⋅ ζ 3

(EQ 126)

K yα B y = ----------------------------( Cy Dy + εy )

(EQ 127)

S Hy = ( p Hy1 + p Hy2 d f z ) ⋅ λ Hy + p Hy3 γ y ⋅ λ Kyγ ⋅ ζ 0 + ζ 4 – 1

(EQ 128)

*

′

S Vy = F z ⋅ { ( p Vy1 + p Vy2 d f z ) ⋅ λ Vy + ( p Vy3 + p Vy4 d f z )γ ⋅ λ Kyγ } ⋅ λ µy ⋅ ζ 2

(EQ 129)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: *

*

•

In (EQ 120) α instead of α used. α shall be used only in case of very large slip angles (normally never measured).

•

In (EQ 123), (EQ 124) and (EQ 129) γ y instead of γ used.

•

In (EQ 122), (EQ 126), (EQ 128) and (EQ 129) ζ 0 , ζ 2 , ζ 3 , ζ 4 and λ Kyγ are set to one.

•

The equation (EQ 126) changes to

*

   Fz  ′ K yα = p Ky1 F zo sin  2 atan  -----------------⋅ ( 1 – p Ky3 γ y ) ⋅ λ Kyα . ′     p Ky2 F zo 

(EQ 130)

with γ y = γ ⋅ λ γy *

•

In (EQ 123) λ µy instead of λ µy

•

In (EQ 129) λ µy instead of λ µx used and

CarMaker Reference Manual

(EQ 131)

used.

′

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Tire Model Magic Formula

•

The equation(EQ 128) changes to S Hy = ( p Hy1 + p Hy2 df ) ⋅ λ Hy + p Hy3 γ y

Lateral (pure slip)

(EQ 132)

Lat.PCY1 Shape factor for lateral forces [-].

Lat.PDY1 Lateral friction µ y [-].

Lat.PDY2 Variation of friction µ y with load [-].

Lat.PDY3 Variation of friction µ y with squared camber [-].

Lat.PEY1 Lateral curvature at Fznom F znom [-].

Lat.PEY2 Variation of curvature with load [-].

Lat.PEY3 Zero order camber dependency of curvature [-].

Lat.PEY4 Variation of curvature with camber [-].

Lat.PKY1 Maximum value of stiffness at F znom [-].

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Lat.PKY2 Load at which K fy reaches maximum value [-].

Lat.PKY3 K Fz

fy - with camber [-]. Variation of ----------nom

Lat.PHY1 Horizontal shift at F znom [-].

Lat.PHY2 Variation of horizontal shift with load [-].

Lat.PHY3 Variation of horizontal shift with camber [-].

Lat.PVY1 Vertical shift at F znom .

Lat.PVY2 Variation of vertical shift with load [-].

Lat.PVY3 Variation of vertical shift with camber [-].

Lat.PVY4 Variation of vertical shift with camber and load [-].

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Tire Model Magic Formula

10.4.8

Aligning Torque (pure side slip) ′

M zo = M zo + M zro

(EQ 133)

′

M zo = – t o ⋅ F yo

(EQ 134) ′

t o = t ( α t ) = D t cos ( [ C t atan { B t α t – E t ( B t α t – atan ( B t α t ) ) } ] ⋅ cos α )

(EQ 135)

*

α t = α + S Ht

(EQ 136)

S Ht = q Hz1 + q Hz2 d f z + ( q Hz3 + q Hz4 d f z )γ

*

(EQ 137)

M zro = M zr ( α r ) = D r cos [ C r atan ( B r α r ) ]

(EQ 138)

*

α r = α + S Hf ( = α f )

(EQ 139)

S Vy S Hf = S Hy + -------′ K yα

(EQ 140)

′

K yα = K yα + ε K

(EQ 141)

2 λ Kyα 2 * * B t = ( q Bz1 + q Bz2 d f z + q Bz3 d f z ) ⋅ ( 1 + q Bz5 γ + q Bz6 γ ) ⋅ ---------* λ µy

(EQ 142)

C t = q Cz1

(EQ 143)

 Ro  - ⋅ ( q Dz1 + q dz2 df ) ⋅ λ t ⋅ sgn V cx D to = F z ⋅  -----′   F zo

(EQ 144)

*

*

2

D t = D to ⋅ ( 1 + q Dz3 γ + q Dz4 γ ) ⋅ ζ 5

(EQ 145)

 2  * 2 E t = ( q Ez1 + q Ez2 d f z + q Ez3 d f z )  1 + ( q Ez4 + q Ez5 γ ) --- atan ( B t C t α t )  π     λ Ky B r =  q Bz9 ⋅ ------- + q Bz10 B y C y ⋅ ζ 6 *   λ µy *

cos α ⋅

* λ µy sgn V cx

(EQ 146)

(EQ 147)

D r = F z R o { ( q BDz6 + q Dz7 d f z )λ Mr ζ 2 + ( q Dz8 + q Dz9 d f z )γ λ Kzy ζ 0 } ′

( ≤ 1)

(EQ 148)

+ ζ8 – 1

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: •

′

′

V VC

Cx In (EQ 135) cos α instead of cos α used. cos α = --------- shall be used

only in case of very large slip angles (normally never measured). •

*

*

In (EQ 136) and (EQ 139) α instead of α used. α shall be used only in case of very large slip angles (normally never measured)

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•

The (EQ 138) changes to: M zro = M zr ( α r ) = D r cos [ atan ( B r α r ) ] cos ( α )

•

(EQ 149)

The equation (EQ 142) changes to: λ Kyα 2 B t = ( q Bz1 + q Bz2 d f z + q Bz3 d f z ) ⋅ ( 1 + q Bz4 γ z + q Bz5 γ z ) ⋅ ----------λ µy

(EQ 150)

γ z = γ ⋅ λ γz

(EQ 151)

with

•

The equation (EQ 145) changes to: 2

D t = D to ⋅ ( 1 + q Dz3 γ z + q Dz4 γ ) ⋅ ζ 5 •

(EQ 152)

The equation (EQ 148) changes to: D r = F z R o ( { ( q Dz6 + q Dz7 d f z )λ Mr ζ 2 + ( q Dz8 + q Dz9 d f z )γ z λ Kzy ζ 0 } ⋅ λ µy )

Aligning torque (pure slip)

(EQ 153)

*

•

In (EQ 137) and (EQ 142)and (EQ 145) and (EQ 146) γ z instead of γ used

•

In (EQ 144) sgn V Cx not used in the simulation.

•

In (EQ 145) γ z instead of γ

•

In (EQ 142) and (EQ 147) λ µx instead of λ µy

•

In (EQ 152), (EQ 147) and (EQ 153) ζ 5 , ζ 6 , ζ 2 , ζ 8 and λ Kzy ,are set to one.

*

used. *

used.

Align.QBZ1 Trail slope factor for trail at F znom [-].

Align.QBZ2 Variation of slope with load [-].

Align.QBZ3 Variation of slope with load squared [-].

Align.QBZ4 Variation of slope with camber [-].

Align.QBZ5 Variation of slope with absolute camber [-].

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Tire Model Magic Formula

Align.QBZ9 Slope factor of residual torque [-].

Align.QBZ10 Slope factor of residual torque [-].

Align.QCZ1 Shape factor for pneumatic trail [-].

Align.QDZ1 Peak trail [-].

Align.QDZ2 Variation of peak trail with load [-].

Align.QDZ3 Variation of peak trail with camber [-].

Align.QDZ4 Variation of peak trail with camber squared [-].

Align.QDZ6 Peak residual torque [-].

Align.QDZ7 Variation of peak residual torque factor with load [-].

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Tire Model Magic Formula

Align.QDZ8 Variation of peak residual torque factor with camber [-].

Align.QDZ9 Variation of peak residual torque factor with camber and load [-].

Align.QEZ1 Trail curvature at F znom [-].

Align.QEZ2 Variation of curvature with load [-].

Align.QEZ3 Variation of curvature with load squared [-].

Align.QEZ4 Variation of curvature with sgn ( α t ) [-].

Align.QEZ5 Variation of curvature with camber and sgn ( α t ) [-].

Align.QHZ1 Trail horizontal shift at F znom [-].

Align.QHZ2 Variation of shift with load [-].

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Tire Model Magic Formula

Align.QHZ3 Variation of shift with camber [-]-

Align.QHZ4 Variation of shift with camber and load [-].

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Tire Model Magic Formula

10.4.9

Longitudinal Force (combined slip) F x = G xα ⋅ F xo cos [ C xα atan { B xα α S – E xα ( B xα α S – atan ( B xα α S ) ) } ] G xα = -----------------------------------------------------------------------------------------------------------------------------------G xαo

(EQ 154)

( > 0)

G xαo = cos [ C xα atan { B xα S Hxα – E xα ( B xα S Hxα – atan ( B xα S Hxα ) ) } ] *

(EQ 155)

(EQ 156)

α S = α + S Hxα

(EQ 157)

B xα = r Bx1 cos ( [ atan ( r Bx2 κ ) ] ⋅ λ xα )

(EQ 158)

C xα = r Cx1

(EQ 159)

E xα = r Ex1 + r Ex2 d f z

(EQ 160)

S Hxα = r Hx1

(EQ 161)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: •

Longitudinal (combine)

*

*

In (EQ 120) α instead of α used. α shall be used only in case of very large slip angles (normally never measured)

Long.RBX1 Slope factor for combined slip reduction [-].

Long.RBX2 Variation of slope F x reduction with κ [-].

Long.RCX1 Shape factor for combined slip F x reduction [-].

Long.REX1 Optional. Curvature factor of combined F x [-]. Default: 0.

Long.PEX2 Optional. Curvature factor of combined F x with load [-].Default: 0.

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Tire Model Magic Formula

Long.PHX1 Shift factor for combined slip F x reduction.

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Tire Model Magic Formula

10.4.10 Lateral force (combined slip) F y = G yκ ⋅ F yo + S Vyκ

(EQ 162)

cos [ C yκ atan { B yκ κ S – E yκ ( B yκ κ S – atan ( B yκ κ S ) ) } ] G xκ = ---------------------------------------------------------------------------------------------------------------------------------G yκo

(EQ 163)

G yκo = cos [ C yκ atan { B yκ S Hyκ – E yκ ( B yκ S Hyκ – atan ( B yκ S Hyκ ) ) } ]

(EQ 164)

κ S = κ + S Hyκ

(EQ 165)

*

B yκ = r By1 cos [ atan { r By2 ( α – r By3 ) } ] ⋅ λ yκ

(EQ 166)

C yκ = r Cy1

(EQ 167)

( ≥ 1)

E yκ = r Ey1 + r Ey2 d f z

(EQ 168)

S Hyκ = r Hy1 + r Hy2 d f z

(EQ 169)

S Vyκ = D Vyκ sin [ r Vy5 atan ( r Vy6 κ ) ]

(EQ 170)

*

*

D Vyκ = µ y F z ⋅ ( r Vy1 + r Vy2 d f z + r Vy3 γ ) ⋅ cos ( [ atan ( r Vy4 α ) ] ⋅ ζ 2 )

(EQ 171)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: *

*

•

In (EQ 166) and (EQ 171) α instead of α used i. α shall be used only in case of very large slip angles (normally never measured)

•

In (EQ 171) γ z instead of γ used.

•

(EQ 170) changes to

*

S Vyκ = D Vyκ sin [ r Vy5 atan ( r Vy6 κ ) ]λ Vyκ •

Lateral (combined slip)

(EQ 172)

In (EQ 171) ζ 2 and is set to one.

Lat.RBY1 Slope factor for combined F y reduction [-].

Lat.RBY2 Variation of slope F y reduction with alpha [-].

Lat.RBY3 Shift term for alpha in slope F y reduction [-].

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Tire Model Magic Formula

Lat.RCY1 Shape factor for combined F y reduction [-].

Lat.REY1 Optional. Curvature factor of combined F y [-]. Default: 0.

Lat.REY2 Optional. Curvature factor of combined F y with load [-].Default: 0.

Lat.RHY1 Shift factor for combined F y reduction [-].

Lat.RHY2 Optional. Shift factor for combined F y reduction with load [-]. Default: 0.

Lat.RVY1 κ induced side force at F z

nom

[-].

Lat.RVY2 Variation of κ induced side force with load [-].

Lat.RVY3 Variation of κ induced side force with camber [-].

Lat.RVY4 Variation of κ induced side force with α [-].

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Tire Model Magic Formula

Lat.RVY5 Variation of κ induced side force with κ [-].

Lat.RVY6 Variation of κ induced side force with atan ( κ ) [-].

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Tire Model Magic Formula

10.4.11 Aligning Torque (combined slip) ′

M z = M z + M zr + s ⋅ F x ′

(EQ 173)

′

Mz = –( t ⋅ Fy )

(EQ 174) ′

t = t ( α t, eq ) = D t cos ( [ C t atan { B t α t, eq – E t ( B t α t, eq – atan ( B t α t, eq ) ) } ] ⋅ cos α ) ′

(EQ 175)

F y = F y – S Vyκ

(EQ 176)

M zr = M zr ( α r, eq ) = D r cos [ C r atan ( B r α r, eq ) ]

(EQ 177)

 Fy   * - + ( s sz3 + s sz4 d f z )γ  ⋅ λ s s = R o ⋅  s sz1 + s sz2  -----′   F zo  

(EQ 178)

α t, eg =

 K xκ 2 2 2 - κ ⋅ sgn ( α t ) α t +  -------′   K yα

(EQ 179)

α r, eg =

 K xκ 2 2 2 - κ ⋅ sgn ( α r ) α r +  -------′   K yα

(EQ 180)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: •

The (EQ 177) changes to M zr = M zr ( α r, eq ) = D r cos [ atan ( B r α r, eq ) ] ⋅ cos α

•

′

′

V VC

Cx In (EQ 175) cos ( α ) instead of cos α used. cos α = --------- shall be used only in case of

very large slip angles (normally never measured)

Aligning Torque (combined slip)

(EQ 181)

*

•

In (EQ 178) γ z instead of γ used.

•

The (EQ 179) and (EQ 180) change to  K xκ 2 2 2 - + κ ⋅ sgn ( α t ) α t, eg = atan tan α t +  -------′   K yα

(EQ 182)

 K xκ 2 2 2 - + κ ⋅ sgn ( α r ) α r, eg = atan tan α r +  -------′   K yα

(EQ 183)

Align.SSZ1 s Ro

Nominal value of ------ effect of F x on M z [-].

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Tire Model Magic Formula

Align.SSZ2 s Ro

F Fz

y Variation of distance ------ with ----------- [-]. nom

Align.SSZ3 s Ro

Variation of distance ------ with camber [-].

Align.SSZ4 s Ro

Variation of distance ------ with load and camber [-].

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Tire Model Magic Formula

10.4.12 Overturning Couple  Fy  * - ⋅ λ Mx M x = F z R o ⋅  q sx1 – q Sx2 γ + q sx3 -----′   F zo

(EQ 184)

At the request of several customers, who claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formulae above: •

The (EQ 184) changes to    Fy  - λ M x = F z R o  q sx1 λ VMx +  – q Sx2 γ + q sx3 -----′  Mx    F zo

Overturning Couple

(EQ 185)

OverTurn.QSX1 Lateral force induced overturning couple [-].

OverTurn.QSX2 Camber induced overturning couple [-].

OverTurn.QSX3 F y induced overturning couple [-]. (EQ 186)

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Tire Model Magic Formula

10.4.13 Rolling Resistance Moment Fx  Vr  - ⋅ λ My M y = – F z R o ⋅  q sy1 atan  ------ + q sy2 -----′   V o F zo  

(EQ 187)

At the request of several customers to claim conformity to ADAMS implementation of MF TIRE 5.2, the tire model includes minor differences to the formula above: •

The (EQ 187) changes to Fx Vx 4   Vx M y = – F z R o ⋅  q sy1 + q 2sy ------- + q Sy3 --------+ q Sy4  ----------  ⋅ λ My  V ref  F zo V ref  

(EQ 188)

where V ref means measurement speed. If q sy1 and q sy2 are both zero, then the following formula is used: M y = R o ( S Vx + K x ⋅ S Hx ) Roll Resistance Moment

(EQ 189)

Roll.QSY1 Rolling resistance torque coefficient [-].

Roll.QSY2 Rolling resistance torque depending on F x [-].

Roll.QSY3 Optional. Rolling resistance torque depending on speed [-].Default: 0.

Roll.QSY4 4

Optional. Rolling resistance torque depending on speed [-]. Default: 0.

Roll.LONGVL Optional. Measurement speed. Default:10 [m/s].

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10.4.14 Transient Behavior For transient effects slip speeds instead of α and κ are used. First-order lags for tire longitudinal and lateral deformations u and v are introduced through relaxation length σ k and κa : du σ κ ------ + V Cx u = – σ κ V Sx dt

(EQ 190)

dv σ α ------ + V Cx v = σ α V Sy dt

(EQ 191)

These differential equations are based on the assumption that the contact point is not slidding.The relaxation lengths are only functions of vertical load and camber angle: Ro - ⋅ λ σκ σ κ = F z ⋅ ( p Tx1 + p Tx2 d f z ) ⋅ exp ( – p Tx3 d f z ) ⋅ -----′ F zo

(EQ 192)

 Fz  - ⋅ ( 1 – p Ky3 γ ) ⋅ R o λ Fzo λ σα σ α = p Ty1 sin 2 atan  ----------------′   p Ty2 F zo 

(EQ 193)

′

′

The practical tire deformation quantities κ and α are subsequently used instead of arguments κ and α in the equations (EQ 154), (EQ 162), (EQ 173), (EQ 185) and (EQ 188).They are defined as follows: u ′ κ = ------ sgn ( V Cx ) σκ

(EQ 194)

v ′ tan α = -----σα

(EQ 195)

Starting from (EQ 190) and (EQ 191) the transient behavior could be described with a low pass filter. The time constant reads: σκ T = --------Vx

(EQ 196)

σα T = --------Vx

(EQ 197)

for the longitudinal action and

for lateral action.

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Tire Model Magic Formula

10.4.15 Gyroscopic couple Due to the tire inertia acting about the vertical axis an offset is added to the aligning torque computed with equation (EQ 173): dv M z, gyr = c gyr m Belt V rl ------ cos [ atan ( B r α r, eq ) ] dt

(EQ 198)

c gyr = q Tz1 ⋅ λ gyr

(EQ 199)

cos [ atan ( B r α r, eq ) ] = 1

(EQ 200)

with parameter

and

for pure cornering condition. The total aligning torque becomes now: ′

M z = M z + M z, gyr Gyroscopic couple

(EQ 201)

Align.PTX1 Relaxation length at F znom [-].

Align.PTX2 Variation of relaxation length with load [-].

Align.PTX3 Variation of relaxation length with exponent of load [-].

Align.TY1 Peak value of relaxation length [-].

Align.TY2 Shape factor for relaxation length [-].

Align.QTZ1 Gyroscopic torque constant [-].

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Align.MBELT Belt mass of the wheel [Kg].

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Tire Model Magic Formula

10.4.16 Friction coefficient If the tire parameters have been detemined at friction conditions which differ from the actual friction condition at road, an effective friction coefficient will be used for the tire computation. For normal conditions the friction coefficient is assumed to be one at measurement conditions. If not, the exact conditions could be specified with the scale factors λ µx and λ µy .With the actual friction condition for the road patch the effective friction value used for the computation reads: µ Road µ eff x, y = -----------λ µx, y

(EQ 202)

This value is used instead of λ µx respectivelly λ µy in (EQ 116), (EQ 117), (EQ 123), (EQ 129), (EQ 148), (EQ 150) and (EQ 153).

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Overview

Chapter 11

Trailer Model

11.1

Overview Like the vehicle model the trailer model is a MESA VERDE multi body model consisting of the vehicle body, 2 or 4 wheel carriers, 2 or 4 wheels and a additional load mass. This trailer model suits passenger towing vehicles and therefore only supports trailers with single or twin axle.

h COM, v lf

hh

h COM, t

lr l

x COM, t lo

l db

Figure 11.1: Common measures for a vehicle with trailer

Relevant quantities are: h COM, v h COM, t hh l lf lr lo l db x COM, t

CarMaker Reference Manual

height of towing vehicles COM height of trailers COM height of hitch wheel base of towing vehicle distance between COM and front axle distance between COM and rear axle hitch overhang drawbar length distance between COM and axle

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General Trailer Parameters

11.2

General Trailer Parameters RefPointInputSystem =

x

y

z

This parameter specifies the origin of the Fr1 (in FrD coordinates). The coordinates XYZ point from the origin of FrD to the origin of Fr1. (see section 1.2 ’CarMaker Axis Systems’).

BucklingAngle_max =

Angle

Optional. This parameter specifies the maximum buckling angle Angle [deg] which is tolerated without issuing an error message. Higher angles lead to an abortion of the current testrun.

nAxle =

NumberOfAxles

Number of trailer axles. Possible values: 1, 2

Tire. =

TireParameterSet

Specifies the parameters of tire to use for wheel front left (i=0), front right (i=1), rear left (i=2) and rear right (i=3). TireParameterSet is the name of a tire parameter set out of directory Data/Tire.

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Mass Geometry

11.3

Mass Geometry

11.3.1

Overview The representation of the distribution of mass in a material system is called mass geometry. Inertia properties are associated with the trailer-body, each of the two/four wheel carriers and each wheel. Additional body loads are modeled via additional masses and inertias as well. Three parameters have to be specified to define a mass element: •

The mass value of the body to define.

•

The center of mass (CoM) of each body is defined. The center of mass is a geometrical point. The three scalar quantities are the position vector of CoM decomposed relative to the origin of the definition frame.

•

The inertia tensor (= second moments of mass = moments of inertia) is a symmetric second-order tensor, which is specified by six scalar quantities I = A B C D E F (Frequently the off-diagonal elements (D, E, F) of the inertia tensor are neglected):

∫

A F E F B D = E D C

2

( y + z 2 ) dm

–

symmetry

∫

xy dm

–

∫

2

( z + x 2 ) dm

–

symmetry

xz dm

∫

yz dm

(EQ 203)

Body

Body

symmetry

∫

Body

Body

Body

∫

2

( x + y 2 ) dm

Body

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Mass Geometry

11.3.2

Parameters

Body.pos = Body.mass = Body.I =

x y Mass ...

z

Trailer body with total mass Body.mass [kg]. Position of the center of mass (CoM) Body.pos is given in FrD (design configuration axis system). Inertia tensor Body.I at the CoM decomposed in the basis of the FrD. The elements of the inertia tensor (section 3.1 ’Overview’)

TrimLoad..pos = TrimLoad..mass = TrimLoad..I =

x y Mass ...

z

Bodies to trim mass contribution to that of a reference vehicle. Trim loads are fixed to vehicle body. := 0, 1, 2, ... Do not confuse TrimLoads with test run specific additional charges you may want to put on your vehicle.

WheelCarrier.fl.pos WheelCarrier.fl.mass WheelCarrier.fl.I Wheel carrier front left. Represents all unsprung mass in the suspension (except the wheel).

WheelCarrier.fr.pos WheelCarrier.fr.mass WheelCarrier.fl.r Wheel carrier front right. For details, see wheel carrier front left.

WheelCarrier.rl.pos WheelCarrier.rl.mass WheelCarrier.rl.I Wheel carrier rear left. For details, see wheel carrier front left.

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Mass Geometry

WheelCarrier.rr.pos WheelCarrier.rr.mass WheelCarrier.rr.I Wheel carrier rear right. For details, see wheel carrier front left.

Wheel.fl.pos Wheel.fl.mass Wheel.fl.I Wheel front left. The wheel and all other rotating components (parts of the brake, ...) .

Wheel.fr.pos Wheel.fr.mass Wheel.fl.r Wheel front right. For details, see wheel front left.

Wheel.rl.pos Wheel.rl.mass Wheel.rl.I Wheel rear left. For details, see wheel front left.

Wheel.rr.pos Wheel.rr.mass Wheel.rr.I Wheel rear right. For details, see wheel front left.

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Suspension Force Elements

11.4

Suspension Force Elements SuspF means front axle, SuspR means rear axle. With a single axle the parameters for SuspR can be omitted.

11.4.1

Spring

SuspF.cAmplify = SuspR.cAmplify =

factor factor

Spring amplification factor. Values given by the spring force model is multiplied with this factor (output value).

SuspPos.c =

dFrc/dq

Spring constant [N/m] of specified wheel.

11.4.2

Damper

SuspF.kAmplify = factor SuspR.kAmplify = factor Damper amplification factor factor. Values given by the damper force model (compression and rebound) is multiplied with this factor (output value).

SuspF.kPush = SuspR.kPush =

dFrc/dqp dFrc/dqp

Damper constant for compression damping. Dimension: Ns/m.

SuspF.kPull = SuspR.kPull =

dFrc/dqp dFrc/dqp

Damper constant dFrc/dqp [Ns/m]for rebound damping.

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Suspension Force Elements

11.4.3

Stabilizer

SuspF.cStAmplify = SuspR.cStAmplify =

factor factor

Stabilizer amplification factor factor. Values given by the stabilizer force model is multiplied with this factor (output value).

SuspF.cSt = SuspR.cSt =

dFrc/dq dFrc/dq

Stabilizer constant dFrc/dq for specified axle.

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Suspension Kinematics and Compliance

11.5

Suspension Kinematics and Compliance

11.5.1

Overview Three types of common trailer suspensions can be selected: •

Sleeve axle

•

Crank axle

•

Semi-Trailing Arm axle

Additional to the suspension kinematics, suspension force elements (spring, damper and stabilizer) and a simple nonlinear compliance is supported.

11.5.2

Sleeve Axle The simplest model of a suspension is the sleeve axle.

z

x

y

Figure 11.4: Model of a sleeve axle

It is characterized through a straight translation of the wheel carrier. In Figure 11.4 the translation in z coordinate direction is shown. There is no modification of toe or camber whilst compression.

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11.5.3

Crank Axle The most commonly used suspension for passenger cars trailers is the crank axle. The crank axle has a rotating axis of the crank arms perpendicular to the trailers roll axis. The wheel carriers are connected at the end of the crank arms. The COM of the wheel carriers moves on a orbit around the y axis of Figure 11.6.

z

x

y ry

l Figure 11.6: Principal of a crank axle

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11.5.4

Semi Trailing Arm Axle The semi trailing arm axle uses the same principal as the crank axle. The difference is that the rotating axis is not along the y-axis like depicted in Figure 11.8. Through this different orientation the wheel practises a camber change.

z

y x ry

l Figure 11.8: Principal of a semi trailing axle

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11.5.5

General Suspension Model Parameters SuspF means front axle, SuspR means rear axle.

Susp.Kind =

SuspensionKind

Type SuspensionKind of suspension (for both axles). Possible options are: Susp.Kind

Description

Sleeve

Kinematics of a sleeve axle is used

Crank

Kinematics of a crank axle is used

SemiTrailingArm

Kinematics of a semi trailing arm axle is used

z

z x

definition of positive camber angle

x definition of positive toe angle

y

y

y

y

Figure 11.10: Sign conventions for camber- and toe-angle

SuspF.InclinationL = SuspR.InclinationL =

InclinAngle InclinAngle

Camber angle InclinAngle [rad] of left wheel in design configuration FrD. Positive sign means the distance on the upper side of the wheel is longer then on the bottom side.

SuspF.InclinationR = SuspR.InclinationR =

InclinAngle InclinAngle

Camber angle InclinAngle [rad] of left wheel in design configuration FrD.

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SuspF.ToeL = SuspR.ToeL =

ToeAngle ToeAngle

Toe angle ToeAngle [rad] of left wheel carrier in design configuration FrD. Positive sign means toe-in, negative sign means toe-out.

SuspF.ToeR = SuspR.ToeR =

ToeAngle ToeAngle

Toe angle ToeAngle [rad] of right wheel carrier in design configuration FrD. Positive sign means toe-in, negative sign means toe-out.

11.5.6

Additional Parameters for Suspension Model “Sleeve” No additional parameters are needed.

11.5.7

Additional Parameters for Suspension Model “Crank” SuspF means front axle, SuspR means rear axle.

SuspF.lCrank = SuspR.lCrank =

length length

Crank length [m].

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Suspension Kinematics and Compliance

11.5.8

Additional Parameters for Suspension Model “SemiTrailingArm” Two points specify the rotation axle of each wheel carrier. The points must not be identical. The FrD axis system is used (see section 1.2 ’CarMaker Axis Systems’). SuspF means front axle, SuspR means rear axle, L means left, R means right.

SuspF.AxlePosL.1 = SuspF.AxlePosR.1 = SuspR.AxlePosL.1 = SuspR.AxlePosR.1 =

x x x x

y y y y

z z z z

First point for wheel carrier rotation axle.

SuspF.AxlePosL.2 = SuspF.AxlePosR.2 = SuspR.AxlePosL.2 = SuspR.AxlePosR.2 =

x x x x

y y y y

z z z z

Second point for wheel carrier rotation axle.

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11.5.9

Compliance ty x

Tz y

rx

rz

Tx F T y y

Fy T y y

Fx

z

Tx

Tz F T y y y

Fz

x

Tz

Fx Tx

Figure 11.12: Trailer compliance

Susp.ElastoActive =

active

Use compliance (elasto kinematics) for trailer. To activate compliance kinematics use active=1, to deactivate use active=0.

Elasto.FrontLeft.ty = Elasto.FrontRight.ty = Elasto.RearLeft.ty = Elasto.RearRight.ty =

dty/dFx dty/dFy dty/dFz dty/dTx dty/dTy dty/dTz ... ... ...

This parameter specifies the compliance vector for the wheel travel direction t y . The six coefficients of this vector form elasticities of six forces and torques acting on the wheel carrier. Usually there is no compliance beside the wheel compression for a force F z . Therefore m m this parameter usually is set to zero. Dimensions: ---- for forces, --------- for torques. N

Nm

Remark: The acting forces are decomposed in carrier frame Fr2.

Elasto.FrontLeft.rx = Elasto.FrontRight.rx = Elasto.RearLeft.rx = Elasto.RearRight.rx =

drx/dFx drx/dFy drx/dFz drx/dTx drx/drx drx/dTz ... ... ...

This parameter specifies the compliance vector for the wheel rotation r x . The six coefficients of this vector form elasticities of six forces and torques acting on the wheel carrier. Usually there is no compliance beside the wheel compression for a force F z . Therefore this rad rad parameter usually is set to zero. Dimensions: -------- for forces, --------- for torques. N

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Nm

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Remark: The acting forces are decomposed in carrier frame Fr2.

Elasto.FrontLeft.rz = Elasto.FrontRight.rz = Elasto.RearLeft.rz = Elasto.RearRight.rz =

drz/dFx drz/dFy drz/dFz drz/dTx drz/drz drz/dTz ... ... ...

This parameter specifies the compliance vector for the wheel rotation r z . The six coefficients of this vector form elasticities of six forces and torques acting on the wheel carrier. Usually there is no compliance beside the wheel compression for a force F z . Therefore this rad rad parameter usually is set to zero. Dimensions: -------- for forces, --------- for torques. N

Nm

Remark: The acting forces are decomposed in carrier frame Fr2.

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Hitch

11.6

Hitch

11.6.1

Overview The trailer model is connected to the towing vehicle by a virtual spring-damper-system. The point of contact is in the middle of the coupling device. The parameters are determined automatically depending on the masses of the vehicles. The parameters are chosen in a way that even with huge coupling forces the relative travel of the coupling contact points is about a few millimeters and numerical stability is ensured. To ensure stabilization of the trailer different hitch improvements have been developed. The CarMaker trailer model supports the following hitch types: •

No stabilization, normal ball joint

•

Four joint hitch

•

Ball joint hitch with friction damper

•

Ball joint with buckling angle dependent hydraulic damping

Parameters

Hitch.Kind =

KindStr

Specifies the type of hitch stabilization model to use. Possible values are: Hitch.Kind

Description

Ball

no stabilization, normal ball joint

Trapez

four joint hitch

BallFric

ball joint hitch with friction damper

BallDamp

ball joint with buckling angle dependent hydraulic damping

Example

Hitch.pos =

Hitch.Kind = BallFric

x

y

z

Center position of the trailers hitch. Coordinates are specified in trailers FrD axis system.

Hitch.c =

dFrc/dq

Optional. Overwrite the internally computed spring constant for trailer hitch. With this parameter not real values for the trailers hitch spring constant should be used rather then values that ensure numerical stability. Default: a default is computed internally by the masses of towing vehicle and trailer.

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Hitch

Hitch.k =

dFrc/dqp

Optional. Overwrite the internally computed damper constant for trailer hitch. With this parameter not real values for the trailers hitch damper constant should be used rather then values that ensure numerical stability. Default: a default is computed internally by a ratio of spring constant to damper constant.

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Hitch

11.6.2

Additional Parameters for Hitch “Ball” No additional parameters needed.

11.6.3

Additional Parameters for Hitch “Trapez” δ A

ab a a0 d

x b1

b2

y B

b b0 r

Figure 11.14: Trapetz hitch

Hitch.Trapez.ab =

length

Length of the trapezoid in direction of vehicles roll axle. See Figure 11.14.

Hitch.Trapez.b1 =

length

Short width of trapez. See Figure 11.14.

Hitch.Trapez.b2 =

length

Long width of trapez. See Figure 11.14.

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Hitch

11.6.4

Additional Parameters for Hitch “BallFric”

Hitch.Fric.Adjust =

factor

Adaption parameter for calculation of stick-slip behavior. For this calculation trailer mass is altered by this factor. Use 1.0 as standard parameter. Example

Hitch.Fric.Adjust = 1.0

Hitch.Fric.myH =

mu

Static friction coefficient between ball-shaped hitch head and frictions elements.

Hitch.Fric.myG =

mu

Sliding friction coefficient between ball-shaped hitch head and frictions elements.

Hitch.Fric.FNorm =

FrcNorm

Normal force preloading the frictions elements against ball-shaped head. Example

11.6.5

Hitch.Fric.FNorm = 2000

Additional Parameters for Hitch “BallDamp”

Hitch.DampKonst =

dFrc/dqp

Damper constant dFrc/dqp [Ns/rad] (equal in all directions of space). Example

CarMaker Reference Manual

Hitch.DampKonst = 50

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Brake System

11.7

Brake System

11.7.1

Overview The brake system of a passenger cars trailer consists of a overrun device, a transmission device and the wheel brakes.

11.7.2

Parameters

Brake.Kind =

KindStr

Type of brake system used. Possible options: Brake.Kind

Description

““

Trailer without brake system

Overrun

Overrun brake, brake torque proportional to drawbar force

Overrun1

Overrun brake, brake torque based on friction

Brake.Ratio Ratio of the sum of all brake forces on all wheels to the force of the trailer hitch. In EWG directive 71/320 “brake systems” a ratio of 5 is compulsory. Example

Brake.Ratio = 5

Brake.Fmin =

value

Operating threshold of the overrun brake. Dimension: N Example

11.7.3

Brake.Fmin = 200

Additional Parameters for Brake Model “Overrun”

Brake.Delay =

value

Time delay for brake force rise. A first order delay element is used. Too small values may lead to instabilities, too high values are not realistic. Dimension: s. Example

CarMaker Reference Manual

Brake.Delay = 0.4

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Brake System

11.7.4

Additional Parameters for Brake Model “Overrun1”

Brake.Fric.Adjust =

value

Adaption parameter for calculation of stick-slip behavior. For this calculation trailer mass is altered by this factor. Use 1.0 as standard parameter.

Brake.Fric.myH =

value

Static friction coefficient between brake pads and brake drum (brake disk). Example

Brake.Fric.myH = 0.55

Brake.Fric.myG =

value

Sliding friction coefficient between brake pads and brake drum (brake disk). Example

CarMaker Reference Manual

Brake.Fric.myG = 0.45

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Aerodynamics

11.8

Aerodynamics The trailer uses the same aerodynamic model as the towing vehicle. For general description see section 6.3.1 ’‘Coeff6x1’’.

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User Accessible Quantities for Trailer

11.9

User Accessible Quantities for Trailer

11.9.1

General User Accessible Quantities: Trailer Name

Frame

Unit

Info True (1) if trailermodel is active (driving with trailer)

Tr.Active Tr.Aero.Frc_1.x Tr.Aero.Frc_1.y Tr.Aero.Frc_1.z

Fr1

Tr.Aero.Trq_1.x Tr.Aero.Trq_1.y Tr.Aero.Trq_1.z

Fr1

Tr.Aero.tau_1

Fr1

rad

Angle of incidence

Tr.Aero.tau2_1

Fr1

rad

Angle of incidence (shifted by 2π)

Tr.Aero.vres_1.x Tr.Aero.vres_1.y Tr.Aero.vres_1.z

Fr1

m/s

Wind velocity

Tr.C.tx Tr.C.ty Tr.C.tz

Fr1

m

Translation carrier reference point front left (used for animation) = FL, FR, RL, RR

rad

Rotation carrier front left (used for animation) = FL, FR, RL, RR

Tr.C.rx Tr.C.ry Tr.C.rz

m

Aerodynamic force acting on trailer

Aerodynamic torque

Tr.C.C.t_0.x Tr.C.C.t_0.y Tr.C.C.t_0.z

Fr0

m

wheel center C

Tr.C.P.t_0.x Tr.C.P.t_0.y Tr.C.P.t_0.z

Fr0

m

wheel road contact point P

Tr.Con.ax Tr.Con.ay Tr.Con.az

Fr0

m/s^2

Center of mass, translational acceleration

Tr.Con.ax_1 Tr.Con.ay_1 Tr.Con.az_1

Fr1

m/s^2

Center of mass, translational acceleration

Tr.Con.tx Tr.Con.ty Tr.Con.tz

Fr0

m

Center of mass, translational position

Tr.Con.vx Tr.Con.vy Tr.Con.vz

Fr0

m/s

Center of mass, translational velocity

Tr.CoM.vx_1 Tr.CoM.vy_1 Tr.CoM.vz_1

Fr1

m/s

Center of mass, translational velocity

Tr.Fr1.ax Tr.Fr1.ay Tr.Fr1.az

Fr0

m/s^2

Translational acceleration

Tr.Fr1.rx Tr.Fr1.ry Tr.Fr1.rz

CarMaker Reference Manual

Trailer rotation angles, Cardan angles, whereby Tr.rz = Tr.Yaw.ry = Car.Pitch and Car.rz = Car.Roll (DIN 70000, 2.2.1.1 - 3)

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Name

Frame

Unit

Info

Tr.Fr1.tx Tr.Fr1.ty Tr.Fr1.tz

Fr0

m

Translational position

Tr.Fr1.vx Tr.Fr1.vy Tr.Fr1.vz

Fr0

m/s

Translational velocity

Tr.Fx Tr.Fy Tr.Fz

FrH

N

longitudinal, lateral and vertical ground reaction force at wheel/road contact point

Tr.Hitch.Frc2Tr.x Tr.Hitch.Frc2Tr.y Tr.Hitch.Frc2Tr.z

Fr0

Hitch force from external (car) to trailer

Tr.Hitch.Frc2Tr.x_1 Tr.Hitch.Frc2Tr.y_1 Tr.Hitch.Frc2Tr.z_1

Fr1

Hitch force from external (car) to trailer

Tr.Hitch.Trq2Tr.x Tr.Hitch.Trq2Tr.y Tr.Hitch.Trq2Tr.z

Fr0

Hitch torque from external (car) to trailer

Tr.Hitch.Trq2Tr.x_1 Tr.Hitch.Trq2Tr.y_1 Tr.Hitch.Trq2Tr.z_1

Fr1

Hitch torque from external (car) to trailer

Tr.Hitch.tx Tr.Hitch.ty Tr.Hitch.tz

Fr0

Hitch translational position

Tr.Hitch.vx Tr.Hitch.vy Tr.Hitch.vz

Fr0

Hitch translational velocity

kg

Mass of load, := 0, 1, 2

m

Position of i-th load, i= 0..2

Tr.LongSlip

–

Longitudinal slip

Tr.Pitch

rad

Trailer pitch angle (DIN 70000, 2.2.1.1) Positive, if front goes down and rear of trailer comes up.

Tr.Roll

rad

Trailer roll angle (DIN 70000, 2.2.1.3) Positive, if right side goes down and left side comes up.

Tr.SideSlipAngle

rad

Sideslip angle (DIN 70000, 2.2.1.4)

Tr.SideSlipAngle2

rad

Sideslip angle with an offset of 2*PI

Tr.SideSlipAngleVel

rad/s

Sideslip angle velocity (DIN 70000, 2.2.1.4)

Tr.Load..mass Tr.Load..tx Tr.Load..ty Tr.Load..tz

Fr1

simulation phase

Tr.SimPhase Tr.TrqBrake

Nm

Brake torque o

Tr.Virtual.Frc_0.x Tr.Virtual.Frc_0.y Tr.Virtual.Frc_0.z

Fr0

N

Virtual force acting to trailer body from external

Tr.Virtual.Frc_1.x Tr.Virtual.Frc_1.y Tr.Virtual.Frc_1.z

Fr1

N

Virtual force acting to trailer body from external

Tr.Virtual.Trq_0.x Tr.Virtual.Trq_0.y Tr.Virtual.Trq_0.z

Fr0

Nm

Virtual torque acting to trailer body from external

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User Accessible Quantities for Trailer

Name

Frame

Info

Nm

Virtual torque acting to trailer body from external

Tr.W.rot

rad

Wheel rotation angle around wheel spin axis

Tr.WheelSpd_

rad/s

Rotational wheel velocity

Tr.Yaw

rad

yaw angle (DIN 70000, 2.2.1.1) Angle between Xaxis of trailer and X-axis of earth fixed system. Positive for positive rotation around Z-axis.

Tr.YawVel

rad/s

yaw angle velocity (DIN 70000, 2.2.2.1)

Tr.alHori

m/s^2

horizontal lateral acceleration

Tr.atHori

m/s^2

horizontal tangential acceleration

m/s^2

acceleration

Tr.dr_z_0

rad

Yaw angle difference between trailer and tractor

Tr.drv_z_0

rad/s

Yaw angle velocity difference between trailer and tractor

Tr.sRoad

m

Trailer road coordinate

Tr.Virtual.Trq_1.x Tr.Virtual.Trq_1.y Tr.Virtual.Trq_1.z

Tr.ax Tr.ay Tr.az

Tr.tx Tr.ty Tr.tz

Fr1

Unit

Fr1

Fr0

m/s

Tr.v Tr.vx Tr.vy Tr.vz

CarMaker Reference Manual

m

Fr1

Wheel velocity (based on wheel rotation and wheel radius)

m/s

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Chapter 12V

User Accessible Quantities

For a better understanding of the naming conventions of UAQ´s please refer to section 1.4 ’CarMaker Naming Conventions’.

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General User Accessible Quantities

12.1

General User Accessible Quantities Name

Unit

Info

Ambient.AirDensity

kg/m3

Air density of the environment.

Ambient.AirHumidity

-

Air humidity of the environment.

Ambient.AirPressure

bar

Air pressure of the environment.

Ambient.Temperature

K

Temperature of the environment.

Ambient.WindVel_ext.x Ambient.WindVel_ext.y Ambient.WindVel_ext.z

m/s

Global wind direction vector of the environment.

CycleNo

-

Number of calculation cycle from the start of the application.

DeltaT

s

Complete duration of calculation cycle

Time

s

Simulation-time of the current testrun. Time starts after initialization process is finished. This time may be accelerated or delayed during non-realtime simulations.

Time.Global

s

Simulation-time since start of the application. This time may be accelerated or delayed during non-realtime simulations.

Time.WC

s

“Wall-clock-time”. This is the real elapsed time during the start of the application. In non-realtime simulations this time may differ from Time.Global

TCPU.AposEvalSend

s

Time-consumption for function AposEvalSend of the current calculation cycle.

TCPU.AposPoll

s

Time-consumption for function AposPoll of the current calculation cycle.

TCPU.Brake

s

Time-consumption for calculation of the Brake module during the current calculation cycle.

TCPU.DrivMan

s

Time-consumption for calculation of the DrivMan module during the current calculation cycle.

TCPU.In

s

Time-consumption for calculation of the IO_In module during the current calculation cycle.

TCPU.Out

s

Time-consumption for calculation of the IO_Out module during the current calculation cycle.

TCPU.PowerTrain

s

Time-consumption for calculation of the PowerTrain module during the current calculation cycle.

TCPU.Total

s

Total time-consumption for calculation of the current cycle. This should not be confused with DeltaT

TCPU.Trailer

s

Time-consumption for calculation of the Trailer module during the current calculation cycle.

TCPU.User

s

Time-consumption for calculation of the User module during the current calculation cycle.

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General User Accessible Quantities

Name

12.1.1

Unit

TCPU.Vehicle

s

TC.Clock

s

TC.Count

s

Info Time-consumption for calculation of the Vehicle module during the current calculation cycle.

User Accessible Quantities: Driving Maneuvers Name

Unit

Info

DM.Brake

brake/decelerator activity (0..1)

DM.BrakePark

park brake activity (0..1)

DM.BrakeLever

brake lever activity (0..1), (only for motorcycles)

DM.Clutch

clutch activity (0..1)

DM.Gas

gas/throttle/accelrator activity (0..1)

DM.GearNo

gear number

DM.GearNo.Trgt DM.Handbrake DM.LaneOffset

outdated name for DM.BrakePark m

DM.Lap.No

lateral lane offset for IPG-DRIVER lap number (racing mode)

DM.Lap.Time

s

lap time (racing mode)

DM.ManDist

m

mini maneuver distance

DM.ManNo DM.ManTime

mini maneuver number s

mini maneuver time

DM.SelectorCtrl DM.Shifting DM.SpeedTrap.Dist

active gear shift m

DM.SpeedTrap.Id DM.SpeedTrap.Time

s

DM.StarterCtrl DM.Steer.Ang

rad

steering angle

DM.Steer.AngAcc

rad/s^2

steering angle acceleration

DM.Steer.AngVel

rad/s

steering angle velocity

DM.Steer.Trq

Nm

steering torque

DM.ax.Trgt

m/s^2

target acceleration

DM.v.Trgt

m/s

target velocity

DM.vdelta.Trgt

m/s

target velocity deviation

DM.SteerBy

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User Accessible Quantities for Vehicle Body

12.2

User Accessible Quantities for Vehicle Body

12.2.1

User Accessible Quantities: Vehicle Name

Frame

Unit

Info

Vhcl.Distance

m

Distance the vehicle (center of mass) traveled since start of simulation50

Vhcl.Engine.on

-

Flag gets true (1) when engine is running.

Vhcl.Engine.rotv

rad/s

Engine speed.

Vhcl.GearBox.rotv_in

rad/s

Input speed of gearbox.

Vhcl.Hitch.x Vhcl.Hitch.y Vhcl.Hitch.z

m

Hitch position.

Vhcl.LongSlip

-

Vhcl.PoI.ax_1 Vhcl.PoI.ay_1 Vhcl.PoI.az_1

Fr1

m/s^2

Point of Interest??

Vhcl.PoI.vx Vhcl.PoI.vy Vhcl.PoI.vz

Fr0

m/s

Velocity vector for PoI

Vhcl.PoI.vx_1 Vhcl.PoI.vy_1 Vhcl.PoI.vz_1

Fr1

m/s

Velocity vector for PoI

Vhcl.PoI.x Vhcl.PoI.y Vhcl.PoI.z

m

Vhcl.Roll

rad

Vhcl.RollAcc

rad/s^2

Vhcl.RollVel

rad/s

Vhcl.SideSlip

rad

Vhcl.Steer.Acc

rad/s^2

Vhcl.Steer.Ang

rad

Vhcl.Steer.Vel

rad/s

Vhcl.Wind.vx Vhcl.Wind.vy Vhcl.Wind.vz

m/s

Vhcl.Yaw

rad

Vhcl.YawAcc

rad/s^2

Vhcl.YawRate

rad/s

Vhcl.sRoad

m

Vhcl.sRoadAero

m

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User Accessible Quantities for Vehicle Body

12.2.2

User Accessible Quantities: Car (for unexperienced users) Name

Frame

Unit

Info

Car.tx Car.ty Car.tz

Fr0

m

Translational position of vehicles connected body.

Car.vx Car.vy Car.vz

Fr1

m/s

Translational velocity of vehicle connected body.

Car.ax Car.ay Car.az

Fr1

m/s^2

Translational acceleration of vehicle connected body.

Car.v

m/s

Velocity

Car.alHori

m/s^2

Centripetal acceleration (in horizontal plane), Car.alHori is perpendicular to Car.v and to Z-axis (DIN 70000, 2.1.2.4).

Car.atHori

m/s^2

Tangential acceleration (in horizontal plane), Car.atHori is parallel to Car.v and per pendicular to Z-axis (DIN 70000, 2.1.2.5).

these are aliases for “Car.Con....”

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12.2.3

User Accessible Quantities: Car Name

Frame

Unit

Info

:= FL, FR, RL, RR Car.Aero.Frc_1.x Car.Aero.Frc_1.y Car.Aero.Frc_1.z

Fr1

Car.Aero.tau2_1

Fr1

Car.Aero.tau_1

Fr1

N

aerodynamics forces

Car.Aero.tau_1 + pi rad

angle of wind direction – Car.Aero.vyres Car.Aero.tau = atan ------------------------------------------– Car.Aero.vxres

Car.Aero.Trq_1.x Car.Aero.Trq_1.y Car.Aero.Trq_1.z

Fr1

Nm

aerodynamics torques at Car.Aero.Pos

Car.Aero.vres_1.x Car.Aero.vres_1.y Car.Aero.vres_1.z

Fr1

m/s

horizontal components of resultant wind flow between vehicle and surroundings

N

buffer force

m

buffer length

Car.Buffer.Frc Car.Buffer.l

Fr1

Car.C.C.t_0.x Car.C.C.t_0.y Car.C.C.t_0.z

m

Car.C.C.v_0.x Car.C.C.v_0.y Car.C.C.v_0.z

m/s

Car.C.GenFrc0

N

Car.C.GenFrc1

N

Car.C.GenInert0

kg

Car.C.GenInert1

kg

Car.C.P.t_0.x Car.C.P.t_0.y Car.C.P.t_0.z Car.C.a_0.x Car.C.a_0.y Car.C.a_0.z

Fr0

m/s^2

Car.C_rx Car.C_ry Car.C_rz

Fr1 [ZXY]

rad

rotation carrier front left (used for animation)

Car.C_tx Car.C_ty Car.C_tz

Fr1

m

translation carrier reference point front left (used for animation)

Car.C.rx_kin Car.C.ry_kin Car.C.rz_kin

Fr1 [ZXY]

rad

by kinematics

m

by kinematics

Car.C.tx_kin Car.C.ty_kin Car.C.tz_kin

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Name Car.C.rx_com Car.C.ry_com Car.C.rz_com

Frame Fr1 [ZXY]

Unit

Info

rad

by compliance

m

by compliance

rad

extra, offset

Car.C.tx_ext Car.C.ty_ext Car.C.tz_ext

m

extra, offset

Car.Camber

rad

camber angle (DIN 70000, 4.1.4) Inclination of the wheel plane towards the vehicle’s longitudinal plane. Positive, if the top of the wheel is inclined towards the outside of the vehicle

Car.Con.alHori

m/s^2

centripetal acceleration (in horizontal plane), Car.alHori is perpendicular to Car.v and to Z-axis (DIN 70000, 2.1.2.4)

Car.Con.atHori

m/s^2

tangential acceleration (in horizontal plane), Car.atHori is parallel to Car.v and perpendicular to Z-axis (DIN 70000, 2.1.2.5)

Car.C.tx_com Car.C.ty_com Car.C.tz_com Car.C.rx_ext Car.C.ry_ext Car.C.rz_ext

Fr1 [ZXY]

Car.Con.ax Car.Con.ax Car.Con.ax

Fr0

translational acceleration of vehicle connected body

Car.Con.ax_1 Car.Con.ay_1 Car.Con.az_1

Fr1

translational acceleration of vehicle connected body

Car.Con.tx Car.Con.tx Car.Con.tx

Fr0

m

translational position of vehicle connected body

Car.Con.v

m/s

velocity

Car.Con.vHori

m/s

horizontal vehicle velocity (DIN 70000, 2.1.1.4) Car.vHori =

Car.Con.vx_1 Car.Con.vy_1 Car.Con.vz_1

m/s

translational velocity of vehicle connected body

Car.Damp.Frc Car.Damp.Frc_ext Car.Damp.Frc_tot

N

damper force, internal, external, total

Car.Damp.l

m

damper length

Car.Damp.v

m/s

damper velocity

m

driving distance since last test run start)

Car.Distance

Fr1

2 2 Car.vx + Car.vy

Fr0

Car.Distance =

∫ Car.v dt t

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Name

Frame

Unit m/s^2

Info

Car.Fr1.ax Car.Fr1.ay Car.Fr1.az

Fr0

vehicle acceleration

Car.Fr1.rx Car.Fr1.ry Car.Fr1.rz

Fr0 rad [Z-XY]

vehicle rotation angles, Cardan angles (DIN 70000, 2.2.1.1 - 3)

Car.Fr1.tx Car.Fr1.ty Car.Fr1.tz

Fr0

m

vehicle position

Car.Fr1.vx Car.Fr1.vy Car.Fr1.vz

Fr0

m/s

translational velocity of vehicle reference point

Car.Fx Car.Fy Car.Fz

FrH

N

longitudinal, lateral and vertical ground reaction force at wheel/road contact point

Car.Gen.ax Car.Gen.ay Car.Gen.az

Fr0

m/s^2

acceleration of generalized vehicle body

Car.Gen.ax_1 Car.Gen.ay_1 Car.Gen.az_1

Fr1

m/s^2

acceleration of generalized vehicle body

Car.Gen.tx Car.Gen.ty Car.Gen.tz

Fr0

m

position of generalized vehicle body

Car.Gen.vx_1 Car.Gen.vy_1 Car.Gen.vz_1

Fr1

m/s

velocity of generalized vehicle body

Car.Hitch.Frc2Car.x Car.Hitch.Frc2Car.y Car.Hitch.Frc2Car.z

Fr0

trailer hitch force and torque acting on car

Car.Hitch.Trq2Car.x Car.Hitch.Trq2Car.y Car.Hitch.Trq2Car.z

trailer hitch force and torque acting on car

Car.Hitch.tx Car.Hitch.ty Car.Hitch.tz

Fr0

m

trailer hitch position (hitch center reference point)

Car.Hitch.vx Car.Hitch.vy Car.Hitch.vz

Fr0

m/s

trailer hitch velocity (hitch center reference point)

Car.InclinAngle

Fr1

rad

inclination angle Angle between Z-axis and wheel plane. Positive for positive rotation around Xaxis of the wheel.

Car.Jack.Fz

N

Car.Jack.tz= 0

B.2.5

Error O.k., obstacle added number of the added obstacle

Obsts_ObstclGetInfo()

- gets information about defined

obstacle Synopsis

#include int Obsts_ObstclGetInfo ( tObsts *Obsts, int No, tObstcl *Obst )

Description

Returns parameters of obstacle number No. Attention: Information about the driving maneuvers is not returned! Always Obst.nMan is set to 0 and Obst.Man to NULL.

Return values -1 0

Error O.k., desired obstacle exits, information is assigned to Obst

B.2.6

Obsts_ObstclDelete()

Synopsis

#include

- delete an obstacle

void Obsts_ObstacleDelete { tObstcl *Obst )

Description

Frees all memory associated by the obstacle Obst. This has nothing to do with the obstacle management!

B.2.7

Obsts_EndOfInput()

Synopsis

#include

- no additional obstacles

int Obsts_EndOfInput ( const tObsts *Obsts struct tRoad *road )

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Description

Stops adding new obstacles to the obstacle management. After that time, the number of obstacles is constant. Nothing can be added or changed. Creates all internals for defined obstacles. Prepares Obst_Calc() •

Call only once per simulation.

•

Call before simulation loop starts.

Return values -3 -2 -1 >= 0

B.2.8

Obsts_ObstVecNew()

Synopsis

#include

Licence expired for Obstacles/ACC module No road defined Error O.k. number of defined obstacles

- get a obstacle output vector

int Obst_ObstVecNew ( const tObsts *Obsts, tObstVec **ObstVec )

Description

To get any information of the actual state of all obstacles, an obstacle output vector is needed. •

Call once after Obsts_EndOfInput()

•

Call before simulation loop starts

Return values -1 >= 0

CarMaker Reference Manual

Error Number of defined obstacles dimension of obstacle output vector

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B.2.9

Obsts_Calc()

- calculate the obstacle module

Synopsis

#include int Obsts_Calc ( const tObsts /*const*/ struct tRoad /*const*/ double /*const*/ double )

Description

*Obsts, *road T SsRoad

Calculate the absolute state of all obstacles for time T and road position SsRoad of the sensor: •

appearance/visibility

•

position and orientation

•

velocity, acceleration

SsRoad is ignored if negative. Return values -1 0

Error O.k.

B.2.10

Obsts_GetObstsAbs()

Synopsis

#include

- get absolute obstacle states

int Obsts_GetObstsAbs ( tObst *Obsts, tObstVec *ObstVec, )

Description

Calculates the absolute values of the obstacle output vector ObstVec. The relative values can be calculated by Obsts_GetObstsRel() after that. •

Call after Obsts_Calc()

•

Call each simulation step

Return values -1 0

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Error O.k.

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B.2.11

Obsts_GetObstsRel()

Synopsis

#include

- get relative obstacle states

int Obst_CalcObstsRel ( tObst *Obsts, tObstVec *ObstVec, tObstSensIF *IF )

Description

Calculates the relative values of the obstacle output vector ObstVec respective to the given state (position, velocity, acceleration, orientation). The transformation matrix TraMat is the matrix to transform a vector defined in a local frame to the inertial system (inertial. = TraMat * local). •

Call after Obsts_Calc().

•

Call each simulation step

Return values -1 0

Error O.k.

B.2.12

Obsts_ObstVecDelete()

Synopsis

#include

- free obstacle output vector

void Obst_ObstVecDelete ( const tObstVec *ObstVec )

Description

Frees all memory allocated by Obsts_ObstVecNew(), referenced by the pointer ObstVec. •

Call once after Obsts_EndOfInput()

•

Call before simulation loop starts

Return values NULL != NULL

Error handle to an output vector with an element for each defined obstacle

B.2.13

Obsts_Delete()

- free obstacle management

Synopsis

#include void Obsts_Delete ( const tObst *Obsts )

Description

Frees all memory allocated for the obstacle management, referenced by the pointer Obsts. The set of obstacles doesn’t exist any longer. •

Call only once per simulation, after the simulation loop is finished.

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B.2.14

Example: Using Obstalces “by Hand” #include “infoc.h” #include “Obstacles.h” tErrorMsg *perrors; extern VehicleAbsSensor(); extern tRoad *Road; /* initialized external! */ int i, nObstacles = 0; tObsts *Obsts = NULL; tObstVec *ObstVec = NULL; tInfos *inf = InfoNew(); struct Sens { double Pos[3], Vel[3], Acc[3]; doubel Omega[3], Alpha[3], TraMat[3][3]; } Sens; /*** initialisation */ InfoRead (&perrors, inf, “obstacles.info”); nObstacles = iGetLong(inf, “nObstacles”); Obsts = Obsts_New(); for (i=0; i < nObstacles; i++) { tObstcl *obst; char key[32]; sprintf (key, “Obstacle.%d“, i); obst = Obsts_iGetObstcl(inf, key); if (obst == NULL) continue; Obsts_ObstclAdd (Obsts, obst); Obsts_ObstclDelete (obst); } InfoDelete (inf); nObstacles = Obsts_EndOfInput(Obsts,Road); i = Obsts_ObstVecNew(Obsts, &ObstVec); /*** simulation loop */ for (t=0; t