2. What is a Robot? Electro-mechanical device. Performs Various tasks.
May be human controlled or automated.
It finds it’s uses in all aspects of our life.

3. How a Robot Can Help ?
An automatic industrial machine replacing the human in hazardous work environment.
An automatic mobile sweeper machine at a modern home.
An automatic toy car for a child to play with.
A machine removing mines in a war field all by itself and many more…

4. Basic Parts of a Robot Mechanical system Power supply system Actuators
Sensory devices for feedback
Sensor Data processing unit
Control system

5. Mechanical Systems

6. Mechanical System The most basic and important part of the robot.
It comprises of chassis, motors, wheels and their placement.
This system decides the locomotion of the robot.

7. Wheeled Locomotion Systems
Differential drive
Car type drive
Skid steer drive
Synchronous drive
Pivot drive

8. Differential Drive
This is the most commonly used form of locomotion system used in robots as it’s the simplest and easiest to implement.
It has free moving wheel(s) in the front accompanied with a left and right wheel. The two wheels are driven by different motors.

9. Differential Drive Cont…

10. Differential Drive: An Analysis
Simplicity and ease of use makes it the most preferred system by beginners
Independent drives makes it difficult for straight line motion. The differences in motors and frictional profile of the two wheels cause them to move with slight turning effect
The above drawback must be countered with appropriate feedback system. Suitable for human controlled remote robots

11. Car Type Drive
It is characterized by a pair of driving wheels and a separate pair of steering wheels.
The translation and rotation are interlinked, hence this system faces severe path planning problem.

12. Car Type Drive Cont…

13. Skid Steer Drive A close relative of the differential drive system.
It is mostly used in tracked machines e.g. tanks. Also finds application in some four / six wheeled robots
The left and right wheels are driven independently.
Steering is accomplished by actuating each side at a different rate or in a different direction, causing the wheels or tracks to slip, or skid, on the ground.

14. Skid Steer Drive Cont…

15. Synchronous Drive
As the name suggests, it uses synchronous rotation of its wheels to achieve motion & turns
It is made up of a system of motors. One set of which drive the wheels and the other set turns the wheels in a synchronous fashion
The two sets can be directly mechanically coupled as they always move in the same direction with same speed

16. Synchronous Drive Cont…

17. Pivot Drive The most unique type of Locomotion system
It is composed of a four wheeled chassis and a platform that can be raised or lowered

18. Pivot Drive Cont…
The wheels are driven by a motor for translation motion in a straight line
For rotation one motor is needed to lower/raise the platform & another to rotate the chassis around the platform
This system can guarantee perfect straight line motion as well as accurate in – place turns to a desired heading

19. Power Systems

20. Power Supply System Suitable power source is needed to run the robots.
Robots are most suitably powered by batteries.
The weight and energy capacity of the batteries may become the determinative factor of its performance.

21. Actuators

22. Actuators
They convert the electrical energy into meaningful mechanical work
Mechanical output can be rotational or linear (straight line)
Motors provide rotational motion
Electromagnets provide linear motion

23. Motors are of various kinds
AC Motors : Not used much in robotics
Stepper Motors : For controlled rotation
DC Motors : Finds extensive general use
Servo Motors : DC motor with in built feedback & error compensation

24. Stepper Motors Used for measured rotation.
Can be held at a particular position of the shaft.
Ideal for many autonomous robots requiring higher precision.

25. Stepper Motor Working
1000
0100
0010
0001
Stepping Sequences for Single Coil Excitation
Only one coil is active at a given instant of time

26. Single Coil Excitation

27. Stepper Motor Working Cont…
1100
0110
0011
1001
Stepping Sequences for Double Coil Excitation
Two coils active at any given instant of time

28. Double Coil Excitation

29. Problems with Stepper Motors
Very low torque to weight ratio
Torque decreases with increase in the stepping frequency
For sufficiently high stepping speed the stepper motor may skip steps due to overshoot

30. DC Motors
As the name suggests, a motor which uses a DC (Direct Current) power
Can run in both directions
Speed Controllable

31. DC Motor Characteristics
DC Motors are high–speed, low-torque devices.
Using gears, the high speed of the motor is traded off into torque

32. DC Motor Drivers These are current amplifying circuits.
A low current control signal is converted into a proportionally higher current signal that can drive the motor

33. DC Motor Direction Control
Power Transistor Switches
VCC S1 S2 M 1 2 S3 S4
H – Bridge Circuit Diagram

34. H – Bridge Working S1 S2 S3 S4 Current Direction Effect 1 1 to 2
1 to 2
Motor spins forward
2 to 1
Motor spins backward -
Braking Occurs

35. Electronic Direction Control
H – Bridge Circuit Diagram

36. Control Systems

37. Open Loop Control System
Desired Action
Controller
Controller
Actuator
Actuator
There is no error correction. No way to check if the actuator was able to take the desired action
Simple system to design, not very reliable
Requires regular calibration of the system

38. Closed Loop Control System
Desired Action
Controller
Actuator
Feedback

39. Example : An Air conditioner
Room Temp
Cooling Device
Desired Temp.
Controller
Temperature Sensor

40. Sensors

41. Sensors Analogous to human sensory organs
Eyes, ears, nose, tongue, skin
Sensors help the robot knowing its surroundings better
Improves its actions and decision making ability
Provides feedback control

42. Examples
Light Dependent Resistor
Thermistor
IR Photo Sensor

43. Line Follower

44. Line Follower
A line follower is a robot capable of tracking a line drawn on a surface
Optical sensors capture the line position at the front end of the robot
The robot is steered to keep it always over the line
Click to view

45. Optical Reflectors

46. Sensor Interfacing

47. Project DCE AUV

48. Delhi College of Engineering

49. Description Tasks and Arena

50. CONSTITUTION Mechanical Design Power 50 Embedded Control Systems
Electronics
Programming
Power
Mechanical Design
Power
Embedded
Control Systems 50

51. The Vehicle

52. Test and Performance

56. Thank You