1. Different Types of Robots
Robot Arms (Fixed Robots)
Mobile Robots
Humanoid Robots
Legged Robots
Wheel Robots
3 wheels
2 Driver wheels, 1 Caster
1 Driver wheel, 2 Casters
4 wheels
Casters make diverse problems in the control of the robot

2. Wheel Robot Main Components
Mechanics
Wheels
Driver Motor (s)
Power Transmission System
Electronics
Controller Board
Needing feedback from environment
Sensors
We are now discussing some of the above topics

3. Different Types of Motors
DC Motors
You can simply control it
AC Motors
It’s difficult to be controlled but it can be used in high power applications
Servo Motors
You have complete control on the shaft angle

4. Different Types of Feed Back
Sensors
IR Sensors
Pressure Sensors
Light Sensors
Temperature Sensors
Encoder

5. What is Encoder

6. Why do we use Power Transmission Systems?
To reduce Angular Velocity
To increase Torque
P = (T . w) = cte.
Different Transmission Systems
Gear
Hard manufacturing
and adjustment
Pulley
So w => T

7. Gear
Gears are used to change the speed and force of the motor. You can use gears to:
Speed up or slow down your robot.
Make your robot stronger or weaker.
There are many different types of gears
Spur Gear
Bevel Gear
Worm Gear
Rack & Pinion

8. Gear
Spur gears are wheels with teeth

9. Gear
Bevel gears mesh at right angles, so they change the direction of rotation.

10. Gear
Worm gears look like screws. They have many special properties.

11. Gear
Rack & pinion gears turn rotational motion into straight-line motion.
                                  

12. Where does all this “torque” come from?
Consider a pair of gears that are meshed together. F
A torque on this axle... t
…produces a force at the tooth. r
The moment arm is the radius of the gear.
Remember: t = F x r

13. The force from the small gear’s tooth pushes against
the large gear’s tooth. This creates an equal (and opposite)
force in the large gear. This is Newton’s 3rd Law. F
…and produces a
larger torque on this axle. r t
The force acts through this larger moment arm...

14. Analyzing the forces...
t1 = F1 x r1
t2 = F2 x r2
F1 = t1 / r1
F2 = t2 / r2
F1 = - F2
t1 / r1 = -t2 / r2
-t2 / t1 = r2 / r1
F1 = -F2 t2 r2 t1 r1
The ratio of torques is the ratio of the gear radii.
This is the gear ratio!

15. Idler Gear
An idler gear is a gear that is inserted between two other gears. Idler gears do not affect the gear ratio between the input and output gears. The gear ratio would be computed just the same if there were no idler gear.

16. Idler Gear
Recall that when using spur gears, the output axle rotates in the opposite direction as the input axle.
You can also use idler gears to change the spacing between the input and output axles
Remember, idler gears do not change the gear ratio

17. Gear The gear ratio of this gear box is 75 to 1
That means the last axle rotates 75 times slower than
the first axle. It also means the last axle has 75 times
the torque as the first axle.

18. Try this experiment.
Have one person turn
this wheel.
And have another person
try to hold on to this wheel.

19. Gears can increase the torque (and force) that they exert
on something. This is known as mechanical advantage.
torque increases
BUT, it comes at a price. Do you know what it is?

20. Belt Drives Uses friction to transmit power Velocity Ratio:2 1 C w2 w1 D2 D1
Velocity Ratio:
D1.w1=D2.w2

21. Belt Drive Basics DR DN Size Size Center Distance Motor Nameplate
(center shaft to center shaft)
Shaft Size
for DR, can use NEMA frame
Motor Nameplate
Take-up/Installation Allowance

22. Ratio always greater than 1
Belt Drive Basics
Speed Ratio = 2.5 R N
Speed-Up
Speed-Down
10”
1750 rpm 4”
700 rpm
4375 rpm
Ratio always greater than 1

23. How to assemble our Robot
Here is our package

24. How to assemble our Robot1 2 3

25. How to assemble our Robot
Bottom view of the robot

26. How to assemble our Robot
Sensor board assembly

27. If you have any further help please contact us at:
Please take a look at our website at:
Robot.schoolnet.ir
If you have any further help please contact us at: