Apply automated control to a real scenario
Select inputs, decisions and outputs for a practical automated system.
This sequence follows Cambridge IGCSE Computer Science 0478, 2026–2028 syllabus Version 6. It covers subject content sections 6.1–6.3 only. The separately published 2029–2031 syllabus is not mapped here. Practice is original, self-checked and does not award an official Cambridge grade. Full timed papers and human subject-teacher review remain outstanding.
Before you begin
- No programming language is required. Be comfortable with place value and multiplication; each lesson introduces the computer-science notation it uses.
Work on paper. Try each question before revealing help, and explain why your method works.
Quick readiness check
Which device can measure temperature?
What you will learn
- Identify a sensor for a scenario
- State how a microprocessor uses a threshold
- Choose a suitable actuator response
Translate a real need into system steps
Start by identifying the condition to measure and choose a sensor that can measure it. The microprocessor compares the reading with a stored rule or threshold, then sends a command to the actuator.
Apply and check the rule
A good design states what input triggers an action and what the output changes. For example, a greenhouse controller measures temperature, compares it with a safe range and activates a fan or heater. Clear rules prevent vague explanations such as “the computer controls it”.
Pause and explain
A fan should turn on when a room becomes too warm. Which device should provide the input?
Worked example
An automatic door should open when a person approaches. Identify the input, processing and output.
Show the worked solution
- A proximity sensor detects a nearby person.
- The microprocessor checks whether the reading passes the opening threshold.
- A motor actuator moves the door.
Answer Proximity sensor → processor checks the distance threshold → motor opens the door.
Try a topic test
Choose Easy, Normal or Difficult. Save your answers and open worked review after finishing.
Test this topic →From guided practice to a new situation
Write your answer and reasoning first. Use a hint only if you are stuck. The model solution is for self-checking; your written work is not automatically marked.
Describe how an automatic greenhouse fan can respond to high temperature.
Give me a hint
Specify input, comparison and output.
Compare my reasoning
- A temperature sensor measures the air.
- The processor compares the reading with the maximum target.
- A motor actuator turns the fan on if the target is exceeded.
Sensor reads temperature; processor checks it against the maximum; fan motor starts when it is too high.
Look for these in your work
- Suitable input
- Threshold decision
- Output action
A flood-warning system needs to alert residents when a river rises. Name one sensor input and one suitable output.
Give me a hint
Measure the physical level and communicate the decision.
Compare my reasoning
- A water-level sensor measures river height.
- The processor compares it with the warning threshold.
- An alarm or message system alerts residents.
Use a water-level sensor and activate an alarm or message when the reading exceeds the warning level.
Look for these in your work
- Input
- Threshold
- Alert output
A weather station's rain sensor sends an input, but the processor only turns on a local light. Explain why the output may not satisfy a flood-warning requirement and suggest a better response.
Give me a hint
Match the actuator to who needs the information.
Compare my reasoning
- A local light may not reach residents or emergency staff.
- The controller should compare rainfall or water level with a defined warning rule.
- It could activate a siren or send an alert to a monitored service.
The light may not communicate the warning to people who need it. Use a defined threshold and an audible or networked alert suitable for residents and staff.
Look for these in your work
- Output limitation
- Rule
- Improved response
Common mistakes
- Naming an output without explaining the decision rule
- Choosing a sensor that does not measure the condition in the scenario
What can you explain now?
What should a good automated-control answer include?
Compare with the explanation
Input, processing rule and output
These identify the measured condition, decision and physical response.
After trying it yourself, choose your next review. This is your self-assessment.
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Make it stick
How do you choose the sensor and actuator for an automated scenario?
If you needed the solution, close it and solve the problem again from a blank page. A correct answer is stronger when you can explain the reason for each step.