1. Motors & Motor Controllers
ECE 450

2. AC or DC Motors AC DC Few robots use AC except in factories
Most of those that use AC first convert to DC DC
Dominates in robotics
Must be bidirectional

3. DC Motor Types Continuous-duty (run continuously when power supplied)
Brushed
Brushless
Servo
Intermittent-duty (power must be pulsed to run continuously)
Stepper Motors

4. Motor Specifications Operating voltage Current draw Speed Torque
Stalling or Running Torque

5. DC Motor: Brush Motors
The most common. Toys, battery powered tools, electric machines.
Stator (permanent magnets)
Brushes

6. Brush DC Motors Identify: Stator Rotor Brushes Commentator
Permanent Magnets
Armature
Field
Electrical Engineering Terms:
Armature: The power-producing component of an alternator, generator, dynamo or motor. The armature can be on either the rotor or the stator.
Field: The magnetic field component of an alternator, generator, dynamo or motor. The field can be on either the rotor or the stator and can be either an electromagnet or a permanent magnet.

7. Brush DC Motor How does it work?

8. Pulse Width Modulation
(PWM)
Centered PWM

9. Brushless DC Motor Identify: Permanent Magnets Rotor Brushes
Commentator
Armature
Field

10. Brushless DC Motor Laminated steel stack Winding Shaft
Permanent Magnets
Less common. Higher efficiency, less friction, less electrical noise. Requires electronic driver.

11. Brushless DC Motor How does it work?

12. DC Servo Motor A DC Servo Motor is a DC Motor with
Gears and Electronics with limited
angular rotation (typically 90, 180 or 360º)
Why the addition of gears?
Nylon
Karbonite
Metal
Why electronics?
Digital
Analog

13. Requires constant pulsing ( 50 times / second)
DC Servo Motor
2.00 ms
1.50 ms
1.00 ms
0.50 ms
0.00 ms 1
1.50 ms: Neutral
1.00 ms: 0 degrees
2.00 ms: 180 degrees
Requires constant pulsing ( 50 times / second)

14. DC Servo Motor Wiring to Microcontroller
Servo motors have three wires: power, ground, and signal.
The ground wire is typically black or brown and should be connected to a ground .
The power wire is typically red, and should be connected to the voltage source.
The signal pin is typically yellow, orange or white and should be connected to the microcontroller

15. Stepper Motors
Very common. Required driver. Very strong, when not rotating. Easy to control rotor position.
Unipolar*
Bipolar
The stepper motor rotates in set angles for each pulse received. Typical angles are turns 30º, 15º and 7.5º.
* An 8 lead stepper is wound like a unipolar stepper, but the leads are not joined to common internally to the motor.

16. Stepper Motor Controllers
With the appropriate logic, step motors can be bi-directional, synchronous, provide rapid acceleration, stopping, and reversal, and will interface easily with other digital mechanisms. They are further characterized as having low rotor moment of inertia, no drift, and a noncumulative positioning error.
Generally step motors are operated without feedback in an open-loop fashion and sometimes match the performance of more expensive DC Servo Systems. The only inaccuracy associated with a step motor is a noncumulative positioning error measured in % of step angle.

17. Stepper Motor Full Step Half Step
Very common. Required driver. Very strong, when not rotating. Easy to control rotor position.
Full Step
Half Step

18. Full-Step Stepper Motor1 1 1 1

19. Half-Step Stepper Motor1 1 1 1 1

20. Using an Atmel Tiny2313 and SN754410 H-Bridge

21. Motor Drivers Simple, 1- dc motor (brushes), on/off driver
DC Brush D1
1N5817
(Schottky) M C Q1
2222A
(NPN) B
On: to +9 V
Off: to GND or disconnected R1
1 k E

22. Transistors PNP Bipolar Transistor NPN Bipolar Transistor C B E C B E

23. DC Brushed Motor Drivers Simple, 1-motor, on/off driver
1 k E Q2
2907A
(PNP)
On: to GND or disconnected
Off: to +9 V B C M1
DC Brush M D1
1N5817
(Schottky)

24. Motor Drivers Classic Bipolar H-Bridge
On: to GND or disconnected
Off: to +9 V
On: to GND or disconnected
Off: to +9 V D1
1N5817
(Schottky) M M1
DC Brush
+9 V Q2
2907A
(PNP) R2
1 k B C E R1 D2 Q1
2222A
(NPN) Q4 R4 R3 Q3 D3 D4
Terminal 4
Terminal 2
Terminal 3
Terminal 1
On: to +9 V
Off: to GND or disconnected
On: to +9 V
Off: to GND or disconnected
Taken from Intermediate Robot Building by David Cook

25. Motor Drivers Classic Bipolar H-Bridge
1 k E R2
1 k D4
1N5817
(Schottky) D2
1N5817
(Schottky) E B B Q4
2907A
(PNP) C C
from microcontroller
4427 1 2 3 4 8 7 6 5 NC
GND
IN A
IN B
VDD
OUT A
OUT B Q2
2907A
(PNP) M
GND Q3
2222A
(NPN) Q1
2222A
(NPN)
from microcontroller M1
DC Brush R3
1 k C D1
1N5817
(Schottky) C R1
1 k D3
1N5817
(Schottky) B B E E
Taken from Intermediate Robot Building by David Cook

26. Motor Drivers Typical H-Bridge Motor Driver
DC Brush
OUT B
+5 VDC
Disconnected or
from microcontroller
From microcontroller
SN754410 1 2 3 4
ENABLE A&B
OUTPUT A
INPUT A
GND 5 6 7 8
INPUT B
OUTPUT B
VMOTOR
VLOGIC
OUTPUT C
INPUT C
INPUT D
OUTPUT D
ENABLE C&D 16 15 14 13 12 11 10 9
from microcontroller M2
0.1 F
220 F
+4.5 to +36 VDC
Taken from Intermediate Robot Building by David Cook