1. A Tutorial on Robotics
Deepak Kumar
CSE(evening shift)
Section: N2
Roll no: 115343

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. Basic Parts Of Our Mobile Robot
 Locomotion system
 Sensory devices for feedback
 Sensor Data processing unit
 Control system
 End actuators
 Power supply system

6. 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

7. 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

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

9. 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
 The above concept will be discussed shortly

10. Using Pulleys
r2
r1 Belt
ω1
ω2
Belt
Motor
Wheel
ω1r1 = ω2r2 => ω2 = ω1r1 / r2
τ1ω1 = τ2ω2 => τ2 = τ1ω1 / ω2 => τ2 = τ1r2 / r1
Thus we get reduction in speed and increased torque. Hence
our machine is able to cross over obstacles easily and also
pull more load

11. Multi Pulley Systems
Motor Intermediate Pulley Wheel
r2
r1 r1 ω2
ω1
r2 ω3
ω1r1 = ω3r2 => ω3 = ω1r1 / r2
τ1ω1 = τ3ω3 => τ3 = τ1ω1 / ω3 => τ3 = τ1r2 / r1
ω3r1 = ω2r2 => ω2 = ω3r1 / r2
τ2ω2 = τ3ω3 => τ2 = τ3ω3 / ω2 => τ2 = τ3r2 / r1 => τ2 = τ1r22 / r12
Hence for n pulley system => τ = τ r n / r n

12. Features of Pulley System
 Simple and easy to use
 Flexible rubber belts make the job easier
 Maximum torque restricted by friction limits
 Very high torque system cannot be achieved

13. Geared Systems
 Gears are the most common form of torque
increment devices, found in almost all
mechanical machines
 The concept of reducing the rotation speed to
increase torque is known as ‘Gear Reduction’
 A high speed motor with low torque is used to
drive heavier loads at lower speeds
 They have much more efficiency than pulleys
 The maximum torque capability is not limited
by friction but material strength

14. Uses of Gear Systems
 ‘Gear Reduction’ to increase torque / decrease
speed of rotation
 Alter the direction of rotation axis
 Synchronization to two axes
 Reversal of direction of rotation

15. Types of Gears
 Spur Gears
 Helical Gears
 Bevel Gears
 Worm Gears
 Rack and Pinion Gears

16. Spur Gears
 Very common kind of
Gear
 Used primarily for
gear reduction
 Reduction ratio is the
ratio of teeth in the
driver gear and the
driven gear

17. Helical Gears
 These gears have
better grip on each
other than the spur
gears
 Can also be used for
changing the axis
direction

18. Bevel Gears
 Mostly used for
altering the direction
of the rotation axis
 The gear reduction
can be achieved by
different number of
teeth in the gears

19. Worm Wheel Mechanism
 Used for very high
gear reduction
 The wheel is driven
by the worm
screw.One rotation of
the worm causes the
wheel to advance
one tooth

20. Rack & Pinion Mechanism
 Used for converting
rotational motion into
linear motion

21. 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

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

23. Simple Current Direction Reversal
MG3 DC MOTOR U5
2 1 NC1
A
COM1
-
+
V3
NO1
V DC
NC2
COM2
NO2
A
S1
B
Relay_DPDT_nb