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In mechanical and control engineering, a servomechanism (also called servo system, or simply servo) is a control system for the position and its time derivatives, such as velocity, of a mechanical system. It often includes a servomotor, and uses closed-loop control to reduce steady-state error and improve dynamic response.[1] In closed-loop control, error-sensing negative feedback is used to correct the action of the mechanism.[2] In displacement-controlled applications, it usually includes a built-in encoder or other position feedback mechanism to ensure the output is achieving the desired effect.[3] Following a specified motion trajectory is called servoing,[4] where "servo" is used as a verb. The servo prefix originates from the Latin word servus meaning slave.[1]
The term correctly applies only to systems where the feedback or error-correction signals help control mechanical position, speed, attitude or any other measurable variables.[5] For example, an automotive power window control is not a servomechanism, as there is no automatic feedback that controls position—the operator does this by observation. By contrast a car's cruise control uses closed-loop feedback, which classifies it as a servomechanism.
- ^ a b Escudier, Marcel; Atkins, Tony (2019). A Dictionary of Mechanical Engineering (2 ed.). Oxford University Press. doi:10.1093/acref/9780198832102.001.0001. ISBN 978-0-19-883210-2.
- ^ Baldor Electric Company – Servo Control Facts. Accessed 25 September 2013
- ^ Anaheim Automation: Servo Motor Guide. Accessed 25 September 2013
- ^ Clarence W. de Silva. Mechatronics: An Integrated Approach (2005). CRC Press. p. 787.
- ^ BusinessDictionary.com definition Archived 2017-03-27 at the Wayback Machine. Accessed 25 September 2013