In this tutorial some of the basic mechanism for robotics has been described.

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