Gryphon EC Final Report

Robotics Introductory Laboratory Session (MECH 4002Y) 1) What are the dimensions (centre to centre) of the different links of the mechanical structure of the robot? ELBOW

SHOULDER 

1

Robotics Introductory Laboratory Session (MECH 4002Y) WAIST

2) What is the drive mechanism used for each link? Explain the relevancy of the type(s) of mechanism on the Gryphon robot.

The driving mechanism used are the belt and gear 

Belt

drive is best suited when the centre distance is large (i.e in the shoulder and elbow part), and

over small distances gears are more practical (that connect the gripper with the elbow). For precise performance and accurate timing over a large distance flat belt are required, which will tend to slip and will not prove satisfactorily. So, as solution to this, the belt is used and fitted to the toothed flywheel (found in the elbow and shoulder).achieve smoother movements. 2

Robotics Introductory Laboratory Session (MECH 4002Y) The stepper motor can divide a full rotation into a large number of steps, thus position can be controlled precisely without and small displacement can be achieved which the stepper motor. The gearing system use is a bevel gear, which found at the connection of the elbow and the end effector. It is used for smooth transmission at high rotational speed.

3) What are the types of degree of freedom as used on the Robot, and what is the range of each degree of freedom?

The degrees of freedom are linear and rotary. These comprises the 5 axis as describe in the diagram below

Degree of freedom

Range

Axis

Angular

Axis

0

1

Axis

centre from top of base 185 mm

Axis

1 axle to column centre 50mm

Angular Arm

Axis2

Arm

0

movement 165

length between axle centers 225mm

Angular

3

0

movement 270

movement 3000

length between axle canters 225mm

Robotics Introductory Laboratory Session (MECH 4002Y) Axis3

Angular

movement 2900

Axis

Angular

movement 290

4

4)

0

Plot accurately the minimum and maximum working envelope of the robot.

The diagrams below show the working envelope

4

Robotics Introductory Laboratory Session (MECH 4002Y)

5) What are the internal sensors used to monitor the displacement and/or velocity of  the robot? Explain the importance of these sensors.

The internal sensors used are encoders. The encoder is a sensor attached to a rotating object (such as a wheel or motor) to measure rotation.

By

measuring rotation your robot can do things such as determine displacement,

velocity, acceleration, or the angle of a rotating sensor.

5

Robotics Introductory Laboratory Session (MECH 4002Y)

Light

sensor 

Encoder

A

disk 

typical encoder uses optical sensor(s), a moving mechanical component, and a special reflector 

to provide a series of electrical pulses to your microcontroller. These pulses can be used as part of a PID feedback control system to determine translation distance, rotational velocity, and/or  angle of a moving robot or robot part.

6

Robotics Introductory Laboratory Session (MECH 4002Y) 6)

Draw a schematic diagram to show the mechanical structure of the end effector.

7) What drive mechanism is used to actuate the end effector? Explain its advantages and limitations.

The drive mechanism to actuate the end effector is pneumatic.

Advantages y

Pneumatics components are relatively inexpensive and the medium (air) is free (unlimited quantity).

y

Compressed air is a fast working medium.

y

Air

can be easily transported in pipelines over long distances. 7

Robotics Introductory Laboratory Session (MECH 4002Y) Limitations

y

y

When

pneumatic equipments are o n, they are noisy.

 No variation of speed and strength o f the gripper.

8) What is the maximum payload that can be safely held by the end effector?

The maximum payload for the end effecter is 1 Kg.

9)

Calculate

the applied load to raise the payload.

Payload = 1kg A pplied

load (Fx) = ?

For Equilibrium (ref to above diag) Moment on left hand side = Moment on right hand side 9.81 x 0.44 Fx

8

=

Fx x 0.26

=

16.60 N

Robotics Introductory Laboratory Session (MECH 4002Y) 10) Describe the external sensors available for interfacing the robot and the other peripheral devices such as the indexing table, and the conveyor.

The external sensors are optical proximity sensor and limit switch. Optical Proximity Sensor 

Proximity switch that responds to light signals and delivers an electrical signal. The switching distance can be adjusted by means of a potentiometer. The proximity switch has a P NP output and is designed as a normally-open contact.

A

yellow

LED

indicates the status. The switch is

 protected against polarity reversal, overload and sho rt circuit.´  Limit switch

The limit switch has two mode of operation, the normally close and the normally open mode. For  the normally open mode, a 5V signal is sent when the switch closes while a 5V signal is sent when the switch opens. The limit switch has a spring mounted contact with which a small strip of  metal makes contact. These sensors are used to detect the presence of objects, send the signal to the control which will in turn process it and execute the proper requirements such as stopping the co nveyor or start. 9

Robotics Introductory Laboratory Session (MECH 4002Y) 11) Briefly explain the functioning of the WA LLI software. WALLI

:-

Work-cell Amalgamated Logical Linguistic Instructions

WALLI

is a software that enable the user to interact with the Gryphon

Ec

robot and number of 

 peripheral devices such as conveyor, indexing tables, and sensors via a PC. The screen below shows an example of data which is being sent to the robot

Inserting

and activating peripherals can be done through the program.

 by clicking on it, it may be incremented by the scroll bar.

When

Alternatively

the data is selected

new data may be simply

typed in as part of the work-cell when a simulator, teach pendant or control panel is being used the data on the screen is updated to the new position.

Each

device can be control precisely and

 perform to specific position desired.

12) What are the different modes of programming the robot? Outline the advantages and limitations of each mode of programming. Teach pendant 

Advantages y

Quick and direct interaction with the robot

y

Must monitor the robot closely to avoid from hitting with obstacles in the surrounding

y

Speed can be control

y

It

can be used to delicate and hazardous environments 10

Robotics Introductory Laboratory Session (MECH 4002Y) Limitations

y

y

Positioning of the robot to a specific location is quite a difficult task   No repeatability

 Simul ator 

Advantages y

y

Easy

to manipulate

 No predefine movement (where the user position the simulator, the robot also follows the

exact sequence) Limitations

y

y

Cannot use the gripper   No repeatability (irreversible)

C om puter

(WALLI software)

Advantages y

Once

the sequence is programmed in the software, the robot can p erform alone

y

Can add various devices (conveyor, sensors, and indexing table) and can make them to

operate in order of preference. y

High degree of accuracy and repeatability

y

Work

y

Speed can be varied

can be stopped and saved to continue later 

Limitations

y

Careful inputs must be typed to avoid from hitting obstacles

y

To use WALLI software alone to reach a specific spot is a difficult task  11

Robotics Introductory Laboratory Session (MECH 4002Y) 13) Explain the safety aspects to be taken into consideration when working with a robotic system. y

Always

y

Assure

that only personnel working with the ro bot must have access in the working zone

y

Assure

that proper configurations are made be fore switching the robot on

y

switch of the system when not in use

 Never remain below the gripper if it is holding load

y

R egular

maintenance must be made

y

I mmediately

immediately.

12

switch off the robot on hearing abnormal sound and case must be reported