Automatic Pneumatic Bumper System for Four Wheeler

AUTOMATIC PNEUMATIC BUMPER AND BRAKING SYSTEM FOR FOUR WHEELER SYNOPSIS The technology of pneumatics has gained tremendous importance in the field of workplace rationalization and automation from old-fashioned timber works and coal mines to modern machine shops and space robots. It is therefore important that technicians and engineers should have a good knowledge of pneumatic system, air operated valves and accessories. The aim is to design and develop a control system based

intelligent electronically

controlled automotive bumper activation and automatic braking system is called “AUTOMATIC PNEUMATIC BUMPER AND BRAKING SYSTEM”.

This system is consists of IR transmitter and

Receiver circuit, Control Unit, Pneumatic bumper system and pneumatic braking system. The IR sensor is used to detect the obstacle. There is any obstacle closer to the vehicle (with in 3-4 feet), the control signal is given to the bumper activation system and also pneumatic braking system simultaneously. The pneumatic bumper and braking system is used to product the man and vehicle. This bumper and braking activation system is only activated the vehicle speed above 30-40 km per hour. This vehicle speed is sensed by the proximity sensor and this signal is given to the control unit and pneumatic bumper and braking activation system.

INTRODUCTION We have pleasure in introducing our new project “AUTOMATIC PNEUMATIC BUMPER AND BRAKING SYSTEM”, which is fully equipped by IR sensors circuit and Pneumatic bumper and braking activation circuit.

It is a genuine project which is fully equipped and designed for Automobile vehicles. This forms an integral part of best quality. This product underwent strenuous test in our Automobile vehicles and it is good.

BLOCK DIAGRAM

WHEEL SPEED SENSING ARRANGEMENT

POWER SUPPLY

IR TRANSMITTER

CONTROL UNIT

IR RECEIVER

FLOW CONTROL VANVE

SOLINOID VALVE

PNEUMATIC CYLINDER -1 AIR TANK (COMPRESSOR) PNEUMATIC CYLINDER -2

BRAKING ARRANGEMENT

BUMPER ANGEMENT

WORKING OPERATION The vehicle speed is sensed by the proximity sensor. The vehicle speed is above the 30-40 Km per hour, the control unit will activate the IR sensor Unit. The IR TRANSMITTER circuit is to transmite the Infra-Red rays. If any obstacle is there in a path, the Infra-Red rays reflected. This reflected Infra-Red rays are received by the receiver circuit is called “IR RECEIVER”. The IR receiver circuir receives the reflected IR rays and giving the control signal to the control circuit. The control circuit is used to activate the solenoid valve. If the solenoid valve is activated, the compressed air passes to the Pneumatic Cylinder. The compressed air activates the pneumatic cylinder and moves the piston rod. If the piston moves forward, then the bumper arrangement and braking arrangements are activated. The piston speed is varied by adjesting the valve is called “FLOW CONTROL VALVE”. In our project, we have to apply this arrangement in one wheel as a model. The compressed air is drawn from the compressor in our project. The compressed air is flow through the Polyurethene tube to the flow control valve. The flow control valve is connected to the solenoid valve as mentioned in the diagram.

APPLICATIONS • For automobile application • Industrial application • Four wheeler application • Two wheeler applications

ADVANTAGES • Free from wear adjustment. • Less power consumption • It gives simplified very operation. • Installation is simplified very much. • To minimize the accident • Safe the vehicle and human being

DISADVANTAGES • Additional cost is required to install this arrangement in the vehicle.

LITERATURE SURVEY

SAFETY SYSTEM:

The aim is to design and develop a control system based on pneumatic breaking system of an intelligent electronically controlled automotive braking system. Based on this model, control strategies such as an 'antilock braking system' (ABS) and improved maneuverability via individual wheel braking are to be developed and evaluated.

There have been considerable advances in modern vehicle braking systems in recent years. For example, electronically controlled ABS for emergency braking, electronically controlled hydraulically actuated individual brake-by-wire (BBW) systems for saloon cars and electronically controlled pneumatically actuated systems for heavy goods vehicles. The work of recent years shall form the basis of a system design approach to be implemented. The novelty of the proposed research programmed shall lie in the design and evaluation of control systems for achieving individual wheel motion control facilitated by BBW. In the case of BBW the brake pedal is detached from the hydraulic system and replaced by a 'brake pedal simulator'. The simulator provides an electrical signal for the electronic control system.

Preliminary modeling and simulation work considers a quarter cars initially followed by a natural progression to the half car and full four wheel station cases. The model is to be constructed in modular form thus allowing the replacement / interchange of the various blocks and their associated technologies. Upon completion of the full vehicle braking model, sensitivity analyses will be carried out. Once the preliminary simulation model has been thoroughly benchmarked and existing control system strategies evaluated, an audit of the technology used is to take place and this will provide a basis for comparison of iterative technologies / techniques.

The final phase of the new modern vehicle shall include:

•

Development of improved ABS control systems

•

Development and assessment of an electro-hydraulic-BBW (EH-BBW) system

•

Individual wheel braking combined with traction control

•

Assessing sensor failure and fault tolerant control system design

•

Preliminary studies into an electrically actuated system

•

Re-engineering using simplified models.

PNEUMATICS

The word ‘pneuma’ comes from Greek and means breather wind. The word pneumatics is the study of air movement and its phenomena is derived from the word pneuma. Today pneumatics is mainly understood to means the application of air as a working medium in industry especially the driving and controlling of machines and equipment.

Pneumatics has for some considerable time between used for carrying out the simplest mechanical tasks in more recent times has played a more important role in the development of pneumatic technology for automation. Pneumatic systems operate on a supply of compressed air which must be made available in sufficient quantity and at a pressure to suit the capacity of the system. When the pneumatic system is being adopted for the first time, however it wills indeed the necessary to deal with the question of compressed air supply.

The key part of any facility for supply of compressed air is by means using reciprocating compressor. A compressor is a machine that takes in air, gas at a certain pressure and delivered the air at a high pressure.

Compressor capacity is the actual quantity of air compressed and delivered and the volume expressed is that of the air at intake conditions namely at atmosphere pressure and normal ambient temperature.

The compressibility of the air was first investigated by Robert Boyle in 1962 and that found that the product of pressure and volume of a particular quantity of gas. The usual written as PV = C

(or) PıVı = P2V2

In this equation the pressure is the absolute pressured which for free is about 14.7 Psi and is of courage capable of maintaining a column of mercury, nearly 30 inches high in an ordinary barometer. Any gas can be used in pneumatic system but air is the mostly used system now a days.

TYPES OF BRAKING The brakes for automotive use may be classified according the following considerations.

1.

PURPOSE

2.

LOCATION

3.

CONSTRUCTION

4.

METHOD OF ACTUATION

5.

EXTRA BRAKING EFFORT

IR SENSOR

SENSORS A sensor is a transducer used to make a measurement of a physical variable. Any sensor requires calibration in order to be useful as a measuring device. Calibration is the procedure by which the relationship between the measured variable and the converted output signal is established.

Care should be taken in the choice of sensory devices for particular tasks. The operating characteristics of each device should be closely matched to the task for which it is being utilized.

Different sensors can be used in different ways to sense same

conditions and the same sensors can be used in different ways to sense different conditions.

TYPES OF SENSOR: Passive sensors detect the reflected or emitted electro-magnetic radiation from natural sources, while active sensors detect reflected responses from objects which are irradiated from artificially generated energy sources, such as radar. Each is divided further in to non-scanning and scanning systems.

SELECTION OF PNEUMATICS: Mechanization is broadly defined as the replacement of manual effort by mechanical power. Pneumatics is an attractive medium for low cost mechanization particularly for sequential or repetitive operations. Many factories and plants already have a compressed air system, which is capable of providing both the power or energy requirements and the control system (although equally pneumatic control systems may be economic and can be advantageously applied to other forms of power).

The main advantages of an all-pneumatic system are usually economy and simplicity, the latter reducing maintenance to a low level. It can also have out standing advantages in terms of safety.

i.

Single acting Pneumatic cylinder

ii.

Solenoid valve

iii.

Flow control value

iv.

Connectors

1) PNEUMATIC SINGLE ACTING CYLINDER:

Pneumatic cylinder consist of

A) PISTON

B) CYLINDER

The cylinder is a Single acting cylinder one, which means that the air pressure operates forward and spring returns backward. The air from the compressor is passed through the regulator which controls the pressure to required amount by adjusting its knob.

A pressure gauge is attached to the regulator for showing the line pressure. Then the compressed air is passed through the single acting 3/2 solenoid valve for supplying the air to one side of the cylinder.

One hose take the output of the directional Control (Solenoid) valve and they are attached to one end of the cylinder by means of connectors. One of the outputs from the directional control valve is taken to the flow control valve from taken to the cylinder. The hose is attached to each component of pneumatic system only by connectors.

CYLINDER TECHNICAL DATA: Piston Rod: M.S. hard Chrome plated Seals: Nitrile (Buna – N) Elastomer End Covers:

Cast iron graded fine grained from 25mm to 300mm Piston: -Aluminium. Media: -Air. Temperature Range: 0^c to 85^c

2. SOLENOID VALVE WITH CONTROL UNIT:

The directional valve is one of the important parts of a pneumatic system. Commonly known as DCV, this valve is used to control the direction of air flow in the pneumatic system. The directional valve does this by changing the position of its internal movable parts.

This valve was selected for speedy operation and to reduce the manual effort and also for the modification of the machine into automatic machine by means of using a solenoid valve. A solenoid is an electrical device that converts electrical energy into straight line motion and force. These are also used to operate a mechanical operation which in turn operates the valve mechanism. Solenoids may be push type or pull type.

The push type solenoid is one in which the plunger is pushed when the solenoid is energized electrically. The pull type solenoid is one is which the plunger is pulled when the solenoid is energized.

The name of the parts of the solenoid should be learned so that they can be recognized when called upon to make repairs, to do service work or to install them.

Parts of a Solenoid Valve 1. Coil The solenoid coil is made of copper wire. The layers of wire are separated by insulating layer. The entire solenoid coil is covered with an varnish that is not affected by solvents, moisture, cutting oil or often fluids. Coils are rated in various voltages such as 115 volts AC, 230 volts AC, 460 volts AC, 575 Volts AC, 6 Volts DC, 12 Volts DC, 24 Volts DC, 115 Volts DC & 230 Volts DC. They are designed for such frequencies as 50 Hz to 60 Hz.

2. Frame The solenoid frame serves several purposes. Since it is made of laminated sheets, it is magnetized when the current passes through the coil. The magnetized coil attracts the metal plunger to move. The frame has provisions for attaching the mounting. They are usually bolted or welded to the frame. The frame has provisions for receivers, the

plunger. The wear strips are mounted to the solenoid frame, and are made of materials such as metal or impregnated less fiber cloth.

3. Solenoid Plunger The Solenoid plunger is the mover mechanism of the solenoid. The plunger is made of steel laminations which are riveted together under high pressure, so that there will be no movement of the lamination with respect to one another. At the top of the plunger a pin hole is placed for making a connection to some device.

The solenoid plunger is moved by a magnetic force in one direction and is usually returned by spring action. Solenoid operated valves are usually provided with cover over either the solenoid or the entire valve. This protects the solenoid from dirt and other foreign matter, and protects the actuator. In many applications it is necessary to use explosion proof solenoids.

WORKING OF 3/2 SINGLE ACTING SOLENOID (OR) CUT OFF VALVE:

The control valve is used to control the flow direction is called cut off valve or solenoid valve. This solenoid cut off valve is controlled by the emergency push button. The 3/2 Single acting solenoid valve is having one inlet port, one outlet port and one exhaust port. The solenoid valve consists of electromagnetic coil, stem and spring. The

air enters to the pneumatic single acting solenoid valve when the push button is in ON position.

Technical Data: Size

: ¼”

Pressure

: 0 to 7 kg / cm2

Media

: Air

Type

:

Applied Voltage

: 230V A.C

Frequency

: 50 Hz

3/2

3. FLOW CONTROL VALVE: 1. Technical Data: Size

: ¼”

Pressure

: 0 to 10 kg / cm2

Media

: Air (b) Purpose:

This valve is used to speed up the piston movement and also it acts as an one – way restriction valve which means that the air can pass through only one way and it can’t return back. By using this valve the time consumption is reduced because of the faster movement of the piston.

4. IR SENSOR UNIT:-

The IR transmitter and IR receiver circuit is used to sense the obstacle. It is fixed to the back side of the frame stand with a suitable arrangement. The pneumatic cylinder is controlled by the flow control valve, single acting solenoid valve and control unit.

IR TRANSMITTER CIRCUIT:

+Vcc R4 (47Ω) 3

T1 (BD140) 1

2 C3 (100µ/25V) R2 (47Ω) R5 L1

4.7Ω IR LED

150K 1

8

2

7

IC 555 3

6

4

5

C2 0.01pF

R1 1.5K

C1 0.1pF

IR RECEIVER CIRCUIT:

1K +12V RELAY R12 (680Ω)

R1 (4.7K)

RL1 L3 (LED)

D2 1N4007

R10 4.7K

C3 (100µ) R7 (100K)

D1 (1N 4007) T5 (BC547B)

R9 (4.7K)

R8

T3 BC 557

T4 (BC 547B)

L1 (IR SENSOR) L2 (IR SENSOR)

C2 (100µ) 4.7K

R3 R2 4.7K

C4 (0.1pF)

C1 (0.01 pF)

T2 (BC549C) 120Ω

R13 120Ω

C8 (47 pF) R5 T1 (BC 549C)

R11 22K

C7 22µF (50V)

R6 2.2K

C5 (0.1pF)

AT NORMAL CONDITION:

The IR transmitter sensor is transmitting the infrared rays with the help of 555 IC timer circuit. These infrared rays are received by the IR receiver sensor. The Transistor T1, T2 and T3 are used as an amplifier section. At normal condition Transistor T5 is OFF condition. At that time relay is OFF, so that the vehicle running continuously.

AT OBSTACLE CONDITION:

At Obstacle conditions the IR transmitter and IR receiver, the resistance across the Transmitter and receiver is high due to the non-conductivity of the IR waves. So the output of transistor T5 goes from OFF condition to ON stage. In that time the relay is ON position. In that time, the solenoid valve is on so that the vehicle stops.

CONTROL UNIT -89C52

In our project 89C52 Microcontroller is used as a control unit.

INTRODUCTION ABOUT MICRO CONTROLLER:

A microcontroller consists of a powerful CPU tightly coupled with memory (RAM, ROM or EPROM), various I/O features such as serial port(s), parallel port(s), Timer/Counter(s), Interrupt controller, Data Acquisition interfaces-Analog to Digital Converter (ADC), Digital to Analog Converter (DAC), everything integrated onto a single silicon chip.

It does not mean that any micro controller should have above said features on-chip. Depending on the need and area of application for which it is designed, the on-chip features present in it may or may not include all the individual sections said above. Any micro computer system requires memory to store a sequence of instructions making up a program, parallel port or serial port for communicating with an external system, timer/counter for control purposes like generating time delays, baud rate for the serial port, apart from the controlling unit called the Central Processing Unit.

MEMORY ASSOCIATED WITH AT-89C52:

PROGRAM MEMORY:

A program memory is a block of memory, which can be used to store a sequence of program codes (by using special EPROM / PROM programmers). It can only be read from and not written into, under normal operating conditions.

There can be up to 64 k bytes of program memory in AT-89C52. in ROM and EPROM versions of the MCS-351 family of devices, the lower 4K are provided on-chip whereas in ROM fewer versions, all program memory is external.

In ROM and EPROM versions of this device, if the special control signals EA (External Access enable) is strapped off Vcc, and then program fetches to addresses 0000 to 0FFF are directed to the internal ROM. The program fetch will be from external memory, where EA* is grounded.

After reset, the CPU begins execution from address location 0000 of the program memory.

Figure shows a map of the AT-89C52-program memory

FFFF 60K Bytes Internal 1000

FFFF OR

64 K Bytes External

0FFF 4 K Bytes Internal

0000

0000

DATA MEMORY:

Data memory is the Read/Write memory. Hence, it can be both read from and written into. AT-89C52 has got 128 bytes of internal data memory and 64K of external data memory.

FF 80

SFRS DIRECT ADDRESS SING ONLY

7F DIRECT AND INDIRECT ADDRESS 00 ING

FFFF AND 0000

64 K Bytes External

INTERNAL DATA MEMORY:

Internal data memory addresses are one byte wide, which includes 128 bytes of on-chip RAM plus a number of special Function Registers. The 128 bytes of RAM can be accessed either by direct addressing (MOV data address) or by indirect addressing (MOV @Ri).

The lowest 32bytes (00-1F) of on-chip RAM are grouped into 4 banks of 8 registers each. Program instructions call out these registers as R0 through R7 > Bits 3 and 4 (PSW.3 and PSW.4) in register program status word (PSW) select which register bank is n use. This allows more efficient use of code space, since register instructions are shorter than instructions that use direct addressing.

Reset initializes the stack pointer register to 7 and its incremented once to start from locating 08, which is register R0 of second register bank. Hence, in order to use more than one register bank, the stack pointer should be initialized to a different location of RAM if it is not used for data storage.

The next 16 bytes (20-2F) from a block of bit addressable memory space, which can also byte addressed.

Bytes 30 through 7F are available to the user as data RAM. However, is the stack pointer has been initialized to this area, enough number of bytes should be left a side to prevent stack overflow.

I/O STRUCTURE OF AT-89C52:

AT-89C52 has four 8-bit parallel ports (hence 8*4=32 I/O lines are available). All four parallel ports are bi-directional. Each line consists of a latch, an output driver and an input buffer.

The four ports are named as port 0 (po), port 1 (p1), port 2 (p2) and port 3(p3). They are bit addressable and has to be represented in the form PX.Y is i.e. bit Y of port X while using bit addressing mode. PX.0 is the LSB (least significant Bit) of port x and px.7 is the MSB (Most Significant Bit) of that port.

Out of the four ports, port 0 and port 2 are used in accesses to external memory. All the port 3 pins are multifunctional. Port 3 is an 8-bit bidirectional with internal pullups.

Port pin

Alternate Functions

P3.0

RXD (Serial input port)

P3.1

TXD (Serial output port)

P3.2

INTO (External Interrupt 0)

P3.3

INT1 (External Interrupt 1)

P3.4

T0 (Timer 0 External input)

P3.5

T1 (Timer 1 External Input)

P3.6

WR (External Data memory write strobe)

P3.7

RD (External Data memory Read Strobe)

PORT 0: Port 0 is an 8-bit open drain bi-directional I/O port. It is also the multiplexed low order address and data bus during access to external memory.

It also receives the instruction bytes during EPROM programming and outputs instruction bytes during program verification. (External pull-ups are required during verification). Port 0 can sink (and operation and source) eight LS TTL input.

PORT 1: Port 1 is an 8-bit bi-directional with internal pull-ups. It receives the low order address byte during EPROM program verification. The port-1 output buffers can sink/source four LS TTL inputs.

PORT 2: Port 2 is an 8-bit bi-directional with external pull-ups. It emits the high order address byte during accesses to external memory. It also receives, these high-order address bits during EPROM programming Verification. Port 2 can sink/source four LS TTL inputs.

RST: While the oscillator is running a high on this pin for two machine cycles resets the device. A small external pull down resistor (8.2k) from RST to Vss permits power on reset when a capacitor (10 micro frequencies) also connected from this pin to Vcc.

ALE/PROG: Address latch enable is the output for latching low byte of the address, during access 10 external memory. ALE is activated at a constant rate of 1/6 the oscillator frequency except during an external data memory access at which time one ALE pulse is skipped. ALE can sink/source eight LS TTL inputs. This pin is also the program pulse input (PROG) during EPROM programming.

PSEN: Program Store Enable is the read strobe to external program memory. PSEN is activated twice each machine cycle, during fetches form external program memory. PSEN is not activated during fetches from internal program memory. PSEN can sink/source 8 LS TTL inputs.

EA/Vpp: When external access enable (EA) is held high, the AT-89C52 execute out of internal program memory (Unless the program counter exceeds OFF (H)). When EA is held low, the AT-89C52 H executes only out of external program memory. This pin also receives the 21 Volts programming. Supply Voltage (Vpp) during EPROM programming. This pin should not be floated during normal.

XTAL1: It is inputs to the inverting amplifier that forms the oscillator. XTAL1 should be grounded when an external oscillator is used.

XTAL 2: It is Outputs to the inverting amplifier that forms the oscillator, and input to the internal clock generator, receives the external oscillator signal when an external oscillator is used.

Vss

-

Circuit ground potential

Vcc

-

Supply Voltage during Programming Verification and

normal Operation.

TIMERS/COUNTERS: AT-89C52 has two 16-bit timer/counter 0, and timer/counter 1. They can be configured in any of the four operating modes, which are selected by bit-pars (m1, 0) in register TMOD (Timer/counter Mode control). Modes 0, 1 and 2 are the same for the timer/counters. Mode 3 is different. 1

FEATURES OF AT-89C52:

40

2

39

3

38

4 37 Now a days an 8-bit AT-89C52/8031/8751 and 16 bit 8097 micro controllers 5 36 available in the form of kits. Its special features are summarized as:6 35 •

4k Bytes of 7Flash

34

8 •

128 Bytes of RAM 9

•

32 I/O lines

33 32

10

31

11

30

•

A five vector12two level interrupt architecture. 29

•

13 A full duplex serial port 14

•

28 27

On chip Oscillator and clock circuitry. 26 15

16 PIN DIAGRAM OF AT89C52: 17 18

25 24

PDIP

23

19

22

20

21

P1.0

Vcc

P1.1

P 0.0(AD 0)

P1.2

P 0.1 (AD 1)

P1.3

P 0.2 (AD 2) PORT 0 DRIVERS

P1.4 P1.5 RAM P1.6

RAM ADDR RESISTOR

B REGISTER

PORT 0 LATCH

PORT 2 DRIVERS

P 0.3 (AD 3)

PORT 2 LATCH

P 0.4 (AD 4) FLASH P 0.5 (AD 5)

P1.7

P 0.6 (AD 6)

RST

P 0.7 (AD 7) STACK POINTER

(R X D) P3.0 ACC

EA / VPP

(T X D) P3.1

ALE/PROG

(INT 0) P3.2

PSEN

(INT 1) P3.32 TMP

P2.7 (A 15) BUFFER

TMP 1

(T 0) P3.4

P2.6 (A 14)

(T1) P3.5

P2.5 (A 13)

(WR) P3.6

P2.4

12) INTERRUPT SERIAL PORT AND TIMER BLOCKS P2.3

(RD) P3.7 XTAL 2

TIMING AND CONTROL

INSTRUCT -ION REGISTER

PSW

PC INCREME (AN-TER

(A 11) PROGRAM

P2.2 (A 10) COUNTER

XTAL 1

P2.1 (A 9)

GND

P2.0 (A 8)

PLCC PORT 1 LATCH

Vcc

PROGRAM ADDRESS REGISTER

P 0. 0 – P 0 . 7

P2.0 – P2.7

OSC

PORT 1 DRIVERS

PORT 3 LATCH

PORT 3 DRIVERS

DPTR

GND

ALU

PSEN ALE/ PROG EA/Vpp RST

P1.0 – P1.7

P3.0 – P3.7