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Feedback helps a system stay on target — Engineering, 7–10 years

A system can measure what is happening, compare it with a target and make a useful change.

Checking and adjusting

Feedback means using information about the result to decide what to do next. A system checks how close it is to a target, then changes its action if needed. This is different from doing one fixed action and never looking at what happened.

Why feedback was needed

A machine or person cannot make a perfect choice once and expect conditions never to change. Rooms warm and cool, water levels rise and fall, and a robot’s wheels may meet different surfaces. Engineers added measuring parts and control rules so systems could notice changes and correct themselves instead of drifting away from the goal.

Keeping a room near 20 °C

Set the target temperature to 20 °C. A sensor reads 17 °C, so the heater switches on; later it reads 20 °C, so the heater switches off. If the room falls to 19 °C, it turns on again. The measurement is feedback because it guides the next action.

The reasonable mistake

It is reasonable to think that measuring is enough: once you know the temperature, you know the problem. But information changes nothing unless the system uses it to act. Feedback needs a measurement, a target for comparison and a response connected to that comparison.

Feedback outside school

A robot vacuum can detect a wall and change direction. A toilet cistern stops filling when a float reaches the right level, and a camera adjusts focus when its picture is blurry. In each case, the system senses a result and uses it to alter what it does next.

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