Actuators

Question 1

Actuator Definition

Answer 1

Control systems which are responsible for transforming the output of a microprocessor or control system into a controlling action on a machine or device

Question 2

Types of Motion

Answer 2

Linear: Linear Motion
Rotary/Circular: Rotary Motion

Question 3

DC motors

Answer 3

Easily controlled
Ideal for speed control and when positions in required
Consists of Stator (stationary) and Rotor

Question 4

DC Types

Answer 4

Brushed, Brushless and Servo

Question 5

Brushed

Answer 5

Cheap, small and easily controlled
The stator is the electromagnet, permanent magnets give the motor better speed/torque
The commutator changes direction

Question 6

Brushless

Answer 6

Smaller, expensive, better torque/speed, more efficient and longer operating life

Question 7

Servo

Answer 7

A brushed motor with some form of positional feedback control connected to the rotor shaft

Question 8

H-bridges

Answer 8

Electronically switches polarity of voltage applied to a load. Allows DC motors run in 2 directions.

Question 9

PWM

Answer 9

adjust the average value of the voltage by turning it on and off

Question 10

AC Motors

Answer 10

Outside stator having coils supplied with alternating current to produce a rotating magnetic field
Inside rotor attached to the output shaft producing a second rotating magnetic field

Question 11

AC Motor Classes

Answer 11

Stators:
Single Phase: Lowe power system, not self starting
Polyphase: High Power, self starting, smoother easy to change direction

Rotors:
Induction: Rotors are conductive
Synchronous: Rotors are permanent magnets used when precise speed is needed

Question 12

Stepper Motor

Answer 12

Convert a pulsed digital input into a discrete incremental mechanical movement

Question 13

Solenoids

Answer 13

Coil with current producing a magnetic field. Movement of armature contracts a return spring which then allows the armature to return to its original position when the current ceases

Question 14

Stepper Motor Types

Answer 14

Variable Reluctance: High step resolution, but hard to get large torque with small motors
Permanent Magnet Stepper: Low power consumption and low step resolution
Hybrid Stepper: Versatile

Question 15

Unipolar and Bipolar Stepper

Answer 15

Unipolar: One winding, each section of the winding is switched on for each direction of the magnetic field - constantly changing direction
Bipolar: Two windings and thus four leads, each winding can carry a positive/negative or no current - weaker since only one at a time