Automatic control

Automatic control is the research area and theoretical base for mechanization and automation, employing methods from mathematics and engineering. See also control theory. A central concept is that of the system which is to be controlled, such as a rudder, propeller or an entire ballistic missile. The systems studied within automatic control are mostly the linear systems.

Automatic control systems are composed of three components:

Sensor(s), which measure some physical state such as temperature or liquid level.
Responder(s), which may be simple electrical or mechanical systems or complex special purpose digital controllers or general purpose computers.
Actuator(s), which effect a response to the sensor(s) under the command of the responder, for example, by controlling a gas flow to a burner in a heating system or electricity to a motor in a refrigerator or pump.

A regulator such as a thermostat is a typical example of a device studied in automatic control.