Actuator

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Date:

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Quick Questions

Shade in the A or B circle for each question.

1. Which statement describes an actuator?

A An input device that measures a physical quantity

B An output device that turns a control signal into physical action

2. A microprocessor sends a signal to a motor to make a robot arm move. What is the motor acting as?

A A sensor

B An actuator

3. Which of these is an example of an actuator?

A A valve that opens to let water flow

B A pH probe in a fish tank

4. What does an actuator receive from the processor?

A A control signal

B Raw measurements of the environment

5. The processor works in digital. An actuator often needs an analogue signal. What must happen?

A The digital signal is converted (DAC) so the actuator can use it

B The actuator converts the sensor data back into readings

Match the Pairs

Draw a line connecting each item on the left to its match on the right.

Left column		Right column
1actuator		AA sensor is an input device that captures data. The actuator is the heater, which carries out the action.
2motor.turn(ON)		BThe processor sends a signal that makes a motor actuator start turning
3A processor decides a valve must open, so it sends a signal to the valve actuator		CIF level > 90 THEN valve.open()
4The processor's digital signal is converted so the actuator can use it, such as switching a heater on		DThe direction is wrong. An actuator receives a control signal from the processor, it does not send data to it.
5A temperature sensor is an actuator because it makes the heater switch on		EAn output device that turns a control signal from a processor into physical movement or action
6An actuator sends data to the processor so it can decide what to do next		FIF temp < 18 THEN heater.on()

Definitions

actuator

Fill in the Blanks

Complete each line of code by filling in the missing parts.

IF temperature _ 20 THEN heater ← ON ENDIF

IF level < 30 THEN _____ ← OPEN ENDIF

value ← 180 signal ← ___(value) motor ← signal

_____ distance > 10 motor ← FORWARD ENDWHILE

IF temp > 30 THEN _____ ← ON ENDIF

Spot the Error

Shade in the letter of the line that contains an error.

Question 1

A temp ← READ(TempSensor)

B IF temp < 18 THEN

C SEND ON TO TempSensor

D ENDIF

Question 2

A WHILE running = TRUE

B dist ← READ(ProxSensor)

C IF dist < 10 THEN

D SEND STOP FROM motor

E ENDIF

F ENDWHILE

Question 3

A level ← READ(LevelSensor)

B WHILE level < 90

C SEND OPEN TO valve

D level ← level + 1

E ENDWHILE

Question 4

A speed ← 128

B signal ← DAC(speed)

C SEND signal TO keyboard

D OUTPUT "Motor on"

Question 5

A SEND STOP TO motor

B WAIT 10

C SEND STOP TO motor

Answer Key

Actuator

Section A: Quick Questions

B — An output device that turns a control signal into physical action

B — An actuator

A — A valve that opens to let water flow

A — A control signal

A — The digital signal is converted (DAC) so the actuator can use it

Section B: Match the Pairs

actuator → An output device that turns a control signal from a processor into physical movement or action

motor.turn(ON) → The processor sends a signal that makes a motor actuator start turning

A processor decides a valve must open, so it sends a signal to the valve actuator → IF level > 90 THEN valve.open()

The processor's digital signal is converted so the actuator can use it, such as switching a heater on → IF temp < 18 THEN heater.on()

A temperature sensor is an actuator because it makes the heater switch on → A sensor is an input device that captures data. The actuator is the heater, which carries out the action.

An actuator sends data to the processor so it can decide what to do next → The direction is wrong. An actuator receives a control signal from the processor, it does not send data to it.

Section C: Definitions

actuator — An output device that turns a control signal from a processor into physical action, such as a motor turning, a valve opening or a heater switching on, in control systems and robots.

Section D: Fill in the Blanks

IF temperature < 20 THEN
heater ← ON
ENDIF

IF level < 30 THEN
valve ← OPEN
ENDIF

value ← 180
signal ← DAC(value)
motor ← signal

WHILE distance > 10
motor ← FORWARD
ENDWHILE

IF temp > 30 THEN
relay ← ON
ENDIF

Section E: Spot the Error

C — The control signal must go to the actuator. The heater is the actuator. A temperature sensor is an input device and cannot be switched on. It should be SEND ON TO heater.

D — An actuator receives signals from the processor, so the command is sent TO the motor. It should be SEND STOP TO motor.

D — The level must be read from the sensor each time round the loop. The valve actuator opens or closes based on real data. It should be level ← READ(LevelSensor).

C — The converted signal must be sent to an actuator, such as the motor. A keyboard is an input device. It should be SEND signal TO motor.

A — The motor must be told to START before it turns. Sending STOP first means the actuator never moves. It should be SEND START TO motor.