An error driven control system in which the control signal to the actuators is proportional to the difference between a command signal from the process variable being controlled.
Control of a particular step of a multistep process, induced by the presence or absence of a product of one of the later steps. A thermostat regulating the flow of heating oil to a furnace in a home is a negative feedback control device.
An equalization circuit or control used to help eliminate unwanted program feedback or "howling".