This document provides an overview of robotics and the basic components of a mobile robot. It defines robotics as a field that mimics human characteristics using concepts from various engineering disciplines. A mobile robot has four main systems - locomotion, control, end actuators, and power. Locomotion options like differential and skid steer drives are described. DC motors are discussed as the most common type of end actuator. The document also outlines the basic parts of a DC motor and power supply systems that can provide power to run robots.

1. A Tutorial on Robotics
 Basic Machine
By: Saumya Ranjan Behura,
Mechatronics Trainee ,CTTC, BBSR

2. What Is “Robotics” ?
 The word robotics is used to collectively define
a field in engineering that covers the mimicking
of various human characteristics
 Sound concepts in many engineering
disciplines is needed for working in this
particular field
 It finds it’s uses in all aspects of our life

3. What A Robot Can Mean ?
 An automatic industrial machine replacing the
human in hazardous work
 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. What Do We Mean Here ?
 Here we are aiming at design and prototyping
of mobile robots capable of controlled
locomotion
 It may be human controlled or automatic
 It must be able to perform certain tasks we set
for it
 The task must be achieved within some given
limitations

5. Type of ROBOT-
1.LEVEL ONE ROBOT (wired robot with 2 dpdt switch).
2.LEVEL TWO ROBOT (Wireless robot with button
control).
3.LEVEL THREE ROBOT (Wireless
autonomous/programmed robot).
4.LEVEL FOUR ROBOT(solar cell and panel 12v )
5.LEVEL FIVE ROBOT(robot war fight)
6.LEVEL SIX ROBOT (Mobile control robot)

6. Basic Parts Of Our Mobile Robot
 Locomotion system
 Control system
 End Actuator
 Power supply system

7. Locomotion System
 As the name suggests a mobile robot must
have a system to make it move
 This system gives our machine the ability to
move forward, backward and take turns
 It may also provide for climbing up and down

8. Locomotion System
 The concept of locomotion invariably needs
rotational motion e.g. a wheel driven by some
power source
 This involves conversion of electrical energy
into mechanical energy, which we can easily
achieve using electrical motors
 The issue is to control these motors to give the
required speed and torque

9. Power, Torque and Speed
 A simple equation: Power is the product of
Torque and Angular velocity
 P = ζ X ω
 This implies that if we want more torque
(pulling capacity) from the same motor we may
have to sacrifice speed and vice versa

10. Another Simple Relation
 The dc motors (tape motors) available have
very high speed of rotation which is generally
not needed. But what they lack is torque output
 For reduction in speed and increase in pulling
capacity we use pulley or gear systems
 These are governed by: ω1 X r1 = ω2 X r2

11. Wheeled Locomotion Systems
 Differential drive
 Ackerman drive (Car type)
 Skid steer drive
 Articulated drive
 Synchronous drive
 Pivot drive
 Dual differential drive

12. Differential Drive
 This is the most commonly used form of
locomotion system used in mobile robots as it’s
the simplest and easiest to implement
 It has a free moving wheel in the front
accompanied with a left and right wheel.The
two wheels are separately powered
 When the wheels move in the same direction
the machine moves in that direction. Turning is
achieved by making the wheels oppose each
other’s motion, thus generating a couple

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. Power Supply System
 Suitable power supply is needed to run the
motors and associated circuitry
 Typical power requirement ranges from 3V to
24V DC
 220V AC supply must be modified to suit the
needs of our machine
 Batteries can also be used to run robots

16. DC Power Supply
D8
D1N4007
Step Down Transformer
D10
D1N4007
Ground
C1
1000uF
230 V AC
+ V
D9
D1N4007
TX1 D7
D1N4007

17. End 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

18. Motors are of various kinds
 AC Motors : Not used much in robotics
 DC Motors : Finds extensive general use
 Stepper Motors : For controlled rotation
 Servo Motors : For controlled rotation

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

20. DC Motor Working
A
-
+
DCMOTOR
12
A
-
+
DCMOTOR
12
VDC
VDC
 Direction of rotation controlled by polarity of
current / voltage
 Speed of rotation controlled by average energy
(power) fed to the motor

21. DC Motor Specifications
 Operating Voltage : Recommended voltage for
powering the motor
 Operating Current : Current drawn at a certain
load on the shaft
 Stall Current : Maximum current drawn, when
motor not allowed to rotate
 Stall Torque : Rotation force needed to hold
the motor in stall condition

22. DC Motor Characteristics
 Free running torque & current are ideally zero
 Increased load implies, increased torque,
current drawn & power consumption
 Power supplied by a motor is the product of
output shaft’s rotational velocity & torque

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

24. DC Motor Characteristics Cont…
 Zero speed at
maximum load
(stall torque)
 Highest speed
while free running
(zero load)
 Highest power at
half speed & half
load
50%
50%
20%
10%
40%
100%
80%
60%
90%
SPEED ------>
POWER
60%
90%
40%
70%
70%
30%
LOAD
20%
30%
100%
80%
10%

25. References
 Working of Gears :
http://www.howstuffworks.com/gear.htm
 Robot Design:
http://www.cs.dartmouth.edu/~robotlab/robotla
b/courses/cs54-2001s/locomotion.html
 Resources shared at: http://10.110.8.219
 Visit http://www.robotixiitkgp.com for details

26. THANK YOU