A short lesson

Understand
feedback loops.

How a system measures a result and adjusts its next action.

By the end: identify the target, measurement, and correction.

A closed loop

Target

What we want

Measure

What happened

Compare

Find the gap

Adjust

Act on the gap

Repeat as the result changes.

The idea

Feedback connects the result to the next action.

Target

Choose the goal

Set the state you want the system to reach or maintain.

Measurement

Observe the result

Use a signal that tells you where the system is now.

Correction

Adjust the action

Compare the signal with the target and respond to the gap.

Closed loopThe result is measured again, so the next action can change.
Worked example

A thermostat corrects a temperature gap.

Target

21°C

The desired room temperature.

Measurement

18°C

The sensor reports a room colder than the target.

Correction

Turn heating on

The controller calls for heat; later measurements determine the next action.

A simplified thermostat example. Real systems can also use thresholds and other controls.

Your turn

Find the three parts of this greenhouse loop.

Scenario

A greenhouse should stay near 24°C.

A sensor reports 29°C. The controller opens a vent, then measures the temperature again.

Practice question

What is the target?
What is measured?
What is the correction?

Explain why measuring again closes the loop.

Answer & recap

The measurement tells the controller what to do next.

Target

Near 24°C

The desired temperature for this example.

Measurement

29°C

The sensor's reading of the current state.

Correction

Open the vent

An action intended to lower the temperature; measure again to see the result.

RememberA target without a measurement gives the system no feedback to act on.