Feedback

For other uses, including Audio feedback, see Feedback (disambiguation)

Feedback in electronic engineering

The processing and control of feedback is engineered into many electronic devices and may also be embedded in other technologies.

Related Topics:
Electronic - Technologies

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The most common general-purpose controller is a proportional-integral-derivative (PID) controller. Each term of the PID controller copes with time. The proportional term handles the present state of the system, the integral term handles its past, and the derivative or slope term tries to predict and handle the future.

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If the signal is inverted on its way round the control loop, the system is said to have negative feedback; otherwise, the feedback is said to be positive. Negative feedback is often deliberately introduced to increase the stability and accuracy of a system, as in the feedback amplifier invented by Harold Stephen Black. This scheme can fail if the input changes faster than the system can respond to it. When this happens, the negative feedback signal begins to act as positive feedback, causing the output to oscillate or hunt. Positive feedback is usually an unwanted consequence of system behaviour.

Related Topics:
Stability - Feedback amplifier - Harold Stephen Black - Oscillate

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With mechanical devices, hunting can be severe enough to destroy the device.

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Harry Nyquist was an electrical engineer who contributed the Nyquist plot for determining the stability of feedback systems.

Related Topics:
Harry Nyquist - Nyquist plot

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