← IGCSE Computer Science Paper 1

Automated systems in industry

Sensors send readings to a microprocessor, which controls actuators like motors, valves and robotic arms to run a production line or chemical plant with little human control.

Part of: IGCSE Computer Science 0478 — 6.1 Automated Systems — Module 28

Understanding Automated systems in industry in IGCSE Computer Science Paper 1

What it does: The sensor gives the input, the microprocessor makes the decision and the motor is the actuator that moves the conveyor. The temperature reading is compared with a stored limit and the heater actuator is switched off, which keeps the plant safe with little human control. Actuators make things move or change, for example robotic arms, motors and valves. A pressure sensor is an input device. An automated system needs sensors to gather data, a microprocessor to decide, and actuators to act. Humans are only needed for oversight.

Common mistakes: The temperature must be read from the temperature sensor, not from the cooling valve. A valve is an actuator, so it is set, not read. It should be temp ← READ(tempSensor). A level sensor only provides input to the microprocessor, so the program must READ from it. It cannot be written to. It should be level ← READ(levelSensor).

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Learning
Duo
In a chemical plant, which device measures the temperature of a reactor and sends the reading to the microprocessor?
A temperature sensorA motor
Matches
IF level >= 100 THEN sensor_close_valve
↓
A sensor cannot close a valve. Sensors only send readings. The microprocessor decides and an actuator (the valve) does the action.
Applying
Meanings
Term
Automated system in industry
Meaning
Sensors send readings to a microprocessor, which controls actuators like motors, valves and robotic arms to run a production line or chemical plant with little human control.
Practice
WHILE TRUE DO
Testing
Gaps
IF temperature 80 THEN
Check Answer
Spots
1temp ← READ(coolingValve)
2IF temp > 80 THEN

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Quick Questions

1. In a chemical plant, which device measures the temperature of a reactor and sends the reading to the microprocessor?
A. A temperature sensor ✓
B. A motor
A sensor is an input device that captures data. A motor is an actuator, so it produces movement and does not measure anything.
2. A level sensor in a tank reads FULL. What should the microprocessor do next?
A. Signal the actuator to open the filling valve wider
B. Signal the actuator to close the filling valve ✓
The microprocessor compares the reading with the stored value. The tank is full, so it makes the valve actuator close to stop the overflow.
3. On a production line, what does an infra-red sensor do?
A. Moves the item along the belt
B. Detects when an item passes or is in position ✓
The sensor only detects the item and sends the data to the microprocessor. A motor, which is an actuator, moves the belt.
4. Which of these is an actuator in an automated factory?
A. A robotic arm ✓
B. A pressure sensor
Actuators make things move or change, for example robotic arms, motors and valves. A pressure sensor is an input device.
5. Pressure in a chemical plant pipe rises above the safe limit. Which sequence is correct?
A. Pressure sensor, then microprocessor, then actuator opens a release valve ✓
B. Actuator, then microprocessor, then pressure sensor
The order is always sensor (input), then microprocessor (process), then actuator (output). The microprocessor decides what the actuator does.

Match the Pairs

IF pressure > 8 THEN open_valve → The microprocessor compares the pressure sensor reading with a stored limit and opens a valve to release pressure in a chemical plant
IF level >= 100 THEN close_valve → The level sensor shows the tank is full, so the microprocessor closes the filling valve to stop the liquid
An infra-red sensor on a production line detects an item and the microprocessor starts a motor on the conveyor belt → IF item_detected THEN start_motor
A temperature sensor in a chemical plant is read repeatedly so the microprocessor can switch the heater off when it is too hot → IF temp > 90 THEN heater_off
IF level >= 100 THEN sensor_close_valve → A sensor cannot close a valve. Sensors only send readings. The microprocessor decides and an actuator (the valve) does the action.
IF robot_arm_moved THEN read_temperature → The robotic arm is an actuator, so it is an output device. It does not take readings. A sensor should send the data and the microprocessor should control the arm.

Key Term

Automated system in industry
Sensors send readings to a microprocessor, which controls actuators like motors, valves and robotic arms to run a production line or chemical plant with little human control.

Fill in the Blanks

1. IF temperature > 80 THEN SWITCH_ON coolingPump ENDIF
Hint: Type the comparison operator that means the chemical plant reading is higher than the limit.
2. WHILE level < 100 DO OPEN fillValve ENDWHILE
Hint: Type the command that lets liquid flow through the valve while the tank is not yet full.
3. IF proximitySensor < 5 THEN STOP conveyorMotor ENDIF
Hint: Type the name of the actuator that moves the items along the production line.
4. IF pressure > maxPressure THEN OPEN releaseValve ENDIF
Hint: Type the variable holding the stored value that the sensor reading is compared with.
5. IF partInPlace THEN MOVE roboticArm TO weldPoint ENDIF
Hint: Type the actuator that the microprocessor tells to move once the sensor detects the part.

Spot the Error

Question 1
A temp ← READ(coolingValve)
B IF temp > 80 THEN
C SET(coolingValve, OPEN)
D ENDIF
Line A — The temperature must be read from the temperature sensor, not from the cooling valve. A valve is an actuator, so it is set, not read. It should be temp ← READ(tempSensor).
Question 2
A level ← WRITE(levelSensor)
B WHILE level < 100
C SET(fillValve, OPEN)
D level ← READ(levelSensor)
E ENDWHILE
F SET(fillValve, CLOSED)
Line A — A level sensor only provides input to the microprocessor, so the program must READ from it. It cannot be written to. It should be level ← READ(levelSensor).
Question 3
A WHILE lineRunning = TRUE
B item ← READ(irSensor)
C IF item ← TRUE THEN
D SET(robotArm, PICK)
E ENDIF
F ENDWHILE
Line C — The arrow ← assigns a value. A condition needs the comparison operator =. It should be IF item = TRUE THEN, so the arm picks only when the infra-red sensor detects an item.
Question 4
A pressure ← READ(pressSensor)
B IF pressure < 200 THEN
C SET(reliefValve, OPEN)
D SET(alarm, ON)
E ENDIF
Line B — The wrong comparison operator would open the relief valve when the pressure is safely low. The check should be pressure > 200, so the valve opens when the pressure is too high.
Question 5
A dist ← READ(proximitySensor)
B IF dist < 5 THEN
C SET(proximitySensor, OFF)
D ELSE
E SET(beltMotor, ON)
F ENDIF
Line C — A proximity sensor is an input device, so it cannot be switched by the program. The actuator that stops the belt is the motor. It should be SET(beltMotor, OFF).

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