Editing Servomechanism (section)

{{Short description|Control system for the motion of a mechanical system}}
{{Expert needed|engineering
| date = September 2013
| reason = The article is about a broad subject area in engineering and needs major revision in addition to academic and text book references
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{{redirect|Servomechanisms|the company|Servomechanisms Inc.}}
In [[mechanical engineering|mechanical]] and [[control engineering]], a '''servomechanism''' (also called '''servo system''', or simply '''servo''') is a [[control system]] for the position and its [[time derivative]]s, 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.<ref name=":0">{{Cite book |last1=Escudier |first1=Marcel |url=http://www.oxfordreference.com/view/10.1093/acref/9780198832102.001.0001/acref-9780198832102 |title=A Dictionary of Mechanical Engineering |last2=Atkins |first2=Tony |date=2019 |publisher=Oxford University Press |isbn=978-0-19-883210-2 |edition=2 |language=en |doi=10.1093/acref/9780198832102.001.0001}}</ref> In closed-loop control, error-sensing [[negative feedback]] is used to correct the action of the mechanism.<ref>[http://www.baldor.com/pdf/manuals/1205-394.pdf Baldor Electric Company – Servo Control Facts]. Accessed 25 September 2013</ref> In displacement-controlled applications, it usually includes a built-in [[encoder (position)|encoder]] or other position feedback mechanism to ensure the output is achieving the desired effect.<ref>[http://www.anaheimautomation.com/manuals/forms/servo-motor-guide.php Anaheim Automation: Servo Motor Guide]. Accessed 25 September 2013</ref> Following a specified motion trajectory is called '''servoing''',<ref>Clarence W. de Silva. Mechatronics: An Integrated Approach (2005). CRC Press. p. 787.</ref> where "servo" is used as a [[verb]]. The ''servo'' prefix originates from the [[Latin]] word ''servus'' meaning slave.<ref name=":0" /> 

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.<ref>[http://www.businessdictionary.com/definition/servomechanism.html BusinessDictionary.com definition] {{Webarchive|url=https://web.archive.org/web/20170327015407/http://www.businessdictionary.com/definition/servomechanism.html |date=2017-03-27 }}. Accessed 25 September 2013</ref> 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.