Editing Machine (section)

== Controllers ==
Controllers combine [[sensor]]s, [[logic]], and [[actuator]]s to maintain the performance of components of a machine. Perhaps the best known is the [[centrifugal governor|flyball governor]] for a steam engine. Examples of these devices range from a [[thermostat]] that as temperature rises opens a valve to cooling water to speed controllers such as the [[cruise control]] system in an automobile. The [[programmable logic controller]] replaced relays and specialized control mechanisms with a programmable computer. [[Servomotor]]s that accurately position a shaft in response to an electrical command are the actuators that make [[robot|robotic systems]] possible.