Negative feedback

Negative feedback is a regulatory process in which a system’s output reduces the signals that produced it, tending to oppose deviations from a set point.

Feedback loop: A process in which a system’s outputs influence its future inputs or state. Negative feedback is one direction a feedback loop can take: its output suppresses its initiating signals.
Thermoregulation: The regulation of an organism’s body temperature through heat production, retention, and loss. Sweating and shivering counteract temperature changes through negative feedback.
Positive feedback: A feedback process in which outputs strengthen the signals that produced them. Unlike negative feedback, it amplifies deviations rather than counteracting them.
Input–output model: A representation of a system in terms of the inputs it receives and the outputs it produces. Feedback requires an output that can influence the system’s later input or control signal.
Overshoot (control theory): A response that passes beyond a target before settling toward it. Strong or delayed corrective feedback can carry a system past its set point.
Set point: A target or reference value against which a regulated variable is compared. The feedback response often reduces the difference between the regulated variable and its target.
Blood glucose regulation: The physiological control of glucose concentration in the blood. Insulin and glucagon act in opposing feedback responses to changes in blood glucose.
Feedforward control: Control that responds to measured or anticipated disturbances before their effects appear in the output. It acts on disturbances without waiting for the output error that negative feedback uses.
Error signal: The difference between a desired value and a measured value in a control system. A controller can use the error’s sign and size to determine corrective action.
Settling time: The time a system’s response takes to remain within a specified range of its final value. It measures how quickly a negatively fed-back system stabilizes after a disturbance.

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