Systems Approach, Control and Programmable Components
Using block diagrams, logic and feedback to reason about open-loop, closed-loop and programmable product behaviour.
How to prepare for the GCSE Design and Technology written exam
Move from requirement to evidence, technical principle, comparison and justified decision. Use current board materials separately for the NEA and for full timed-paper rehearsal.
Core concepts
Concept 1
A systems approach divides a product or process into functional blocks with defined inputs, processes, outputs and connections.
Exam cue: Label information or energy crossing each boundary in a system diagram.
Concept 2
Open-loop control acts without measuring the result, while closed-loop control uses feedback to compare actual behaviour with a target.
Exam cue: Identify the measured output, target and corrective action in a feedback loop.
Concept 3
Programmable components can embed conditional, timed and repeated behaviour, improving customisation while creating software, security, energy and reliability considerations.
Exam cue: Trace a simple control rule through normal and boundary input conditions.
Risk pitfalls and guardrails
Calling any repeated process closed-loop control.
Guardrail: Do not substitute one board's specialist route or current product claim for the multi-board core, and do not turn written process knowledge into NEA or practical submission material.
Assuming programmability automatically makes a system intelligent.
Guardrail: Do not substitute one board's specialist route or current product claim for the multi-board core, and do not turn written process knowledge into NEA or practical submission material.
Ignoring failure states, latency or sensor error.
Guardrail: Do not substitute one board's specialist route or current product claim for the multi-board core, and do not turn written process knowledge into NEA or practical submission material.
Memory anchors
Input-process-output
A model tracing information or energy into, through and out of a system.
Open-loop control
Control that does not use measured output to correct its action.
Closed-loop control
Control that uses feedback to compare output with a target and adjust.
Feedback
Information about actual output returned to influence subsequent control.
Programmable component
A device whose stored instructions determine or customise system behaviour.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
What are the three basic stages in a simple control system?
In a thermostatic fan, what is the input?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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