1 Motors & Motor Controllers ECE 450. 2 AC or DC Motors AC –Few robots use AC except in factories...

1

Motors & Motor Controllers

ECE 450

2

AC or DC Motors

• AC– Few robots use AC except in factories– Most of those that use AC first convert to DC

• DC– Dominates in robotics– Must be bidirectional

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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

Brushes

Stator (permanent magnets)

The most common. Toys, battery powered tools, electric machines.

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Brush DC Motors

Identify:• Stator• Rotor• Brushes• Commentator• Permanent Magnets• Armature• Field

http://mot-sps.com/motor/tutorial/blac.html

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.

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Brush DC MotorHow does it work?

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Pulse Width Modulation(PWM)

Centered PWM

9

Brushless DC Motor


Identify:• Permanent Magnets• Rotor• Brushes• Commentator• Armature• Field

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Brushless DC Motor

1. Laminated steel stack

2. Winding

3. Shaft

4. Permanent Magnets

Less common. Higher efficiency, less friction, less electrical noise. Requires electronic driver.

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Brushless DC MotorHow does it work?

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DC Servo Motor

http://www.societyofrobots.com/actuators_servos.shtml

A DC Servo Motor is a DC Motor withGears and Electronics with limited angular rotation (typically 90, 180 or 360º)

Why the addition of gears?• Nylon• Karbonite• Metal

Why electronics?• Digital• Analog

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DC Servo Motor

http://www.seattlerobotics.org/guide/servos.html

2.00 ms

1.50 ms

1.00 ms

0.50 ms

0.00 ms

0

1

2.00 ms

1.50 ms

1.00 ms

0.50 ms

0.00 ms

0

1

2.00 ms

1.50 ms

1.00 ms

0.50 ms

0.00 ms

0

1

1.50 ms: Neutral

1.00 ms: 0 degrees

2.00 ms: 180 degrees

Req

uir

es c

on

stan

t p

uls

ing

(

50

tim

es /

sec

on

d)

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DC Servo MotorWiring to Microcontroller

Servo motors have three wires: power, ground, and signal.

1. The ground wire is typically black or brown and should be connected to a ground .

2. The power wire is typically red, and should be connected to the voltage source.

3. The signal pin is typically yellow, orange or white and should be connected to the microcontroller

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Stepper Motors

http://www.stepperworld.com/Tutorials/pgUnipolarTutorial.htm* An 8 lead stepper is wound like a unipolar stepper, but the leads are not joined to common internally to the motor.

Unipolar* Bipolar

Very common. Required driver. Very strong, when not rotating. Easy to control rotor position.

The stepper motor rotates in set angles for each pulse received. Typicalangles are turns 30º, 15º and 7.5º.

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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.

http://www.anaheimautomation.com/intro.htmhttp://arduino.cc/en/Reference/StepperUnipolarCircuit

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Stepper Motor

Very common. Required driver. Very strong, when not rotating. Easy to control rotor position.

Full Step Half Step


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1

1

1

Full-Step Stepper Motor

1

19

Half-Step Stepper Motor

1

1

1

1

1

20

Using an Atmel Tiny2313 and SN754410 H-Bridge

http://www.instructables.com/id/Drive-a-Stepper-Motor-with-an-AVR-Microprocessor/

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Motor DriversSimple, 1- dc motor (brushes), on/off driver

D11N5817

(Schottky)M

M1DC Brush

+9 V

Q12222A(NPN) R1

1 k

On: to +9 VOff: to GND or

disconnected

B

E

C

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Transistors

NPN Bipolar Transistor

PNP Bipolar TransistorC

B

E

C

B

E

http://www.kilowattclassroom.com/Archive/AN0007.pdf

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DC Brushed Motor DriversSimple, 1-motor, on/off driver

D11N5817

(Schottky)M

M1DC Brush

+9 V

Q22907A(PNP)

R21 k On: to GND or

disconnected Off: to +9 V

B

C

E

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Motor DriversClassic Bipolar H-Bridge


disconnected


disconnected

On: to GND or disconnected

Off: to +9 V

On: to GND or disconnected

Off: to +9 V

D11N5817

(Schottky)

M

M1DC Brush

+9 V

Q22907A(PNP)

R21 k

B

C

E

R11 k

D21N5817

(Schottky)

Q12222A(NPN)

+9 V

Q42907A(PNP)

R41 k

B

C

E

R31 k

Q32222A(NPN)

D31N5817

(Schottky)

D41N5817

(Schottky)

B

E

C

B

E

C

Taken from Intermediate Robot Building by David Cook

Terminal 1

Terminal 2

Terminal 3

Terminal 4

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Motor DriversClassic Bipolar H-Bridge

D11N5817

(Schottky)

M

M1DC Brush

Q22907A(PNP)

R21 k

B

C

E

R11 k

D21N5817

(Schottky)

Q12222A(NPN)

Q42907A(PNP)

R41 k

B

C

E

R31 k

Q32222A(NPN)

D31N5817

(Schottky)

D41N5817

(Schottky)

B

E

C

B

E

C

4427

1

2

3

4

8

7

6

5

NC

GND

IN A

IN B

NC

VDD

OUT A

OUT B

+9 V

from microcontroller


GND


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Motor DriversTypical H-Bridge Motor Driver

MM1

DC Brush

OUT B

+5 VDC

Disconnected or from microcontroller

From microcontroller

SN

754410

1

2

3

4

ENABLE A&B

OUTPUT A

INPUT A

GND

5

6

7

8

GND

INPUT B

OUTPUT B

VMOTOR

VLOGIC

OUTPUT C

INPUT C

GND

GND

INPUT D

OUTPUT D

ENABLE C&D

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15

14

13

12

11

10

9

M


M2DC Brush

Disconnected or from microcontroller



0.1 F220 F

+4.5 to +36 VDC

0.1 F220 F


1 Motors & Motor Controllers ECE 450. 2 AC or DC Motors AC –Few robots use AC except in factories...

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