Control loop — sensor, microprocessor, actuator
A computer-controlled system repeats a three-part cycle with no direct human input. The sensor measures a physical quantity — light, proximity, pressure, temperature, position — and sends the reading as data. The microprocessor compares it with stored/preset data and decides what happens next. The actuator (e.g. a motor or robot arm) turns that signal into physical movement. The loop repeats continuously, so the system reacts in real time.
Robotics and autonomous vehicles
Robotics in manufacture. A robot is a reprogrammable computer-controlled machine used for welding, spray-painting, pick-and-place, camera inspection. On a production line robots and sensors act in sequence, so every unit gets identical steps and consistent output. Autonomous vehicles run the same loop: proximity sensors, cameras and GPS feed the microprocessor, which checks the route and safe-driving rules; actuators work the steering, brakes and accelerator.
Computer control vs humans — five features
Both sides are examinable — learn five features you can argue either way. Accuracy — consistent, since it never tires. Continuous operation — runs 24 hours a day: no breaks, holidays or sick leave. Cost — no ongoing wages, but a high initial cost to buy and program. Safety — works in extreme heat, toxic fumes or heavy lifting with no risk to anyone. Flexibility — only a human can use judgement in an unplanned situation the system was never programmed for.
Drawn from real examiner reports.
"It works by itself" defines nothing
"A machine that works by itself", or "a system controlled by a computer", scores nothing — neither says how. The mark-scheme answer names all three parts and the job each does: a sensor measures the quantity, the microprocessor compares the reading with stored data and decides, and an actuator carries out the physical action.
A one-sided point is not a comparison
Asked to compare a computer-controlled system with a human doing the same job, "robots do not need paying" is only half the mark-scheme point. A real comparison links both sides in one sentence: "a robot needs no salary, whereas a human must be paid wages, so running costs fall over time." Give both halves, not just the machine's side.
Robots vs humans / sensors vs humans need a clear comparison — accuracy, no salary, job loss (s22 P12 Q11 / w22 P12 Q8)
"Robots take jobs" is not enough
On employment effects, candidates stop at job losses or more leisure time. Name the actual consequence instead: workers face unemployment, need retraining for a more technical role such as programming or maintaining the system, or find their roles de-skilled and gone. Productivity change is creditable too.
Job loss and more leisure commonly given; few gave training, productivity or de-skilling (w22 P11 Q13 / w22 P12 Q13)
Never split a discuss with a line
Ruling the page into an "advantages" column and a "disadvantages" column, each holding unrelated points, prevents a true comparison and caps the marks available. Examiners want matched pairs on the same feature — speed against speed, cost against cost — written as continuous prose, not as two separate lists.
An advantage is not a benefit
A benefit just states something good: "the line gives consistent output." An advantage compares it with the alternative: "more consistent than a human worker, who tires over a shift." If the command word is advantage, disadvantage, compare or discuss, the sentence must contain a comparative.
Sensor, actuator, robot, whole line
Four things that get blurred. A sensor only measures. An actuator only moves or acts. A robot is the complete computer-controlled machine, containing sensors, a microprocessor and one or more actuators. Production-line control is the whole sequence of stations — often several robots plus sensors — working in order, not a single machine.
Percentage change: divide by the OLD
Percentage change is (new - old) divided by the old value, times 100 — so divide by the original figure, never the new one. A negative result means a decrease. Finish by stating the direction, "a 40% decrease in assembly time", because a bare number never says whether the time rose or fell.
Explain? Then write "because"
A bare advantage — "a robot is faster", "it is more accurate" — is only half an explain or discuss answer. Start the second half with because: "more accurate because it does not lose concentration over a long shift".
Compare feature by feature
Pick one feature and give BOTH sides of it in a single sentence — accuracy against accuracy, cost against cost — then move on to the next feature. Two or three fully matched pairs score better than six one-sided statements.
Name the specific sensor
"It uses sensors" is too vague. Name the sensor and its job: a proximity/distance sensor for how close an obstacle is, a camera for road markings and signs, GPS for location. Do not skip the microprocessor's compare-with-stored-data step either.
End a discuss with a judgement
A discuss question is level-marked, so an unresolved list of points caps your mark. After the matched pairs, state a conclusion tied to the scenario — for example, automate the highly repetitive stages but keep human workers where varied materials need judgement.
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