Control system

A control system monitors a process or machine and adjusts its inputs to drive its behavior toward a desired state. It may operate with or without feedback.

Feedback: Information about a system’s output that is returned to influence its subsequent behavior. Feedback lets the system compare actual behavior with its target and correct deviations.
Control theory: The mathematical study of how systems can be guided toward desired behavior through inputs and feedback. Control theory supplies the main analytical framework for designing control systems.
Thermostat: A device that regulates temperature by switching or modulating heating or cooling equipment. A thermostat is a familiar feedback controller with a temperature target.
Open-loop control: Control in which actions are chosen without using measurements of the system’s output. It contrasts with feedback control because it cannot correct output errors during operation.
Controller: A component that computes control actions from reference values and measured system behavior. The controller turns measured error into commands for the process.
System dynamics: The study of how a system’s state changes over time in response to inputs and internal interactions. A controller must account for how the process evolves after each input.
Cruise control: An automotive system that adjusts engine power to maintain a selected vehicle speed. It regulates speed despite changing road grade and other disturbances.
Closed-loop control: Control that uses measured output to adjust inputs in response to deviations from a target. It is the feedback-based architecture most commonly associated with regulation.
Actuator: A device that converts a control signal into physical action on a system. Actuators apply the controller’s commands to the process.
Stability theory: The mathematical study of whether systems remain near or return to an equilibrium after disturbances. Stability determines whether corrective action settles the system or makes deviations grow.

Linked from 6 pages