2. Actuators: The Family
Actuators
Rotational Linear
DC Motors Stepper Motors Pneumatics Artificial
Muscles
Geared RC Servo Unipolar Bipolar
www.thinklabs.in
3. DC Motor
Backbone of major
actuators in robotics
Available in various
shapes, sizes and
ratings
Easy to use
www.thinklabs.in
4. Geared Motors
A DC motor with a gear
head on its output shaft
Principle of gear
reduction used
Amplifies torque and
reduces speed
Absolutely necessary
Available in wide range
of gear reduction ratios
[ My summer dream collection ;-) ]
www.thinklabs.in
6. The Right Geared Motor
How to select the right motor for your robot?
Its all about Speed & Torque
For small robots, speeds of 60 – 150rpm is ideal
and torque in the range of 2Kgcm
Gear reduction ratio can approximate torque
All depends on the DC motor used, bigger,
meaner, the better
www.thinklabs.in
7. Motor Drivers
Motor Motor
Logic block
Driver
Motor
Power Supply
Basic Block Diagram of a Motor Controller
www.thinklabs.in
9. RELAYS V/S BJTS
Relays BJTs (Solid State)
• Has a high power • Power rating is
rating. smaller than relays.
• High power • Very small power
consumption. consumption.
• Slower in response. • Fast response.
• May produce noise • Immune to noise.
at the output.
• Size?? • Size??
www.thinklabs.in
11. Motor Drivers: Solid State
Drivers built using Transistors
Fast, Efficient and Small
Also available in Integrated Packages
Ideal for our needs !!
www.thinklabs.in
12. Motor Drivers: Solid Sate
Basic Motor Driver (ON/OFF) using a BJT
www.thinklabs.in
14. Motor Drivers: Solid Sate
Basic Motor Driver (ON/OFF) using a BJT
www.thinklabs.in
15. Motor Drivers : Bi-Directional
But how about changing the motor direction as
well??
www.thinklabs.in
16. Motor Drivers : H-Bridge
H Bridge / Full Bridge
H Bridge is capable of
driving a DC motor in both
the directions.
Based on the switch
states, direction of the
motor can be changed.
www.thinklabs.in
17. H-Bridge Case 1
Case 1:
When switch S2 and S3
are closed, current will
flow from right to left
of the motor.
Now, the motor will
rotate in one direction,
say Clockwise.
www.thinklabs.in
18. H-Bridge Case 2
Case 2:
When switch S1 and S4
are closed, current will
flow from left to right of
the motor.
Now, the motor will
rotate in another
direction, ie., Counter
Clockwise.
www.thinklabs.in
26. H Bridges: Integrated Circuits
Darlington pairs available in IC packages : ULN
XX
H Bridges available in IC packages : L298,
L293D, LMD1800 and many more…
www.thinklabs.in
