servomotor
noun
ser·vo·mo·tor ˈsər-vō-ˌmō-tər 
: a power-driven mechanism that supplements a primary control operated by a comparatively feeble force (as in a servomechanism)
Example Sentences
Recent Examples on the Web The component, known as a servomotor, combines an engine with a sensor that enables precise control of the position and speed of a drone. 
Dion Nissenbaum, WSJ, 6 Oct. 2021 An electronic signal tells the ETM the exact position of your gas pedal, and the ETM then operates a servomotor to open and close the throttle. Star Tribune, 4 June 2021 The servomotors use special low-temperature lubricant, and Navmar fitted EPDM weather seal gasketing to all access hatches, ports, and panels to prevent accumulating moisture and ice. David Hambling, Popular Mechanics, 13 July 2017 Its customizable cylinder, which can handle up to 150 pounds, contains a GPS unit and servomotor for steering the parachute to a drop site up to 2 miles away. Bob Parks, WIRED, 20 Oct. 2008
Dion Nissenbaum, WSJ, 6 Oct. 2021 An electronic signal tells the ETM the exact position of your gas pedal, and the ETM then operates a servomotor to open and close the throttle. Star Tribune, 4 June 2021 The servomotors use special low-temperature lubricant, and Navmar fitted EPDM weather seal gasketing to all access hatches, ports, and panels to prevent accumulating moisture and ice. David Hambling, Popular Mechanics, 13 July 2017 Its customizable cylinder, which can handle up to 150 pounds, contains a GPS unit and servomotor for steering the parachute to a drop site up to 2 miles away. Bob Parks, WIRED, 20 Oct. 2008 Word History
Etymology
borrowed from French servo-moteur, from Latin servus "slave" + French -o- -o- + moteur motor entry 1 — more at serve entry 1
Note: The term was apparently the coinage of the French engineer and inventor Joseph Farcot (1824-1908), who introduced such a mechanism in the 1860's. In the publication Le servo-moteur ou moteur asservi (Paris, 1873), Farcot states "Nous avons cru qu'il était nécessaire de donner un nom nouveau et caractéristique à cet engin nouveau et l'avons appelé servo-moteur ou moteur asservi" (p. 4). ("We thought that it was necessary to give a new and distinguishing name to this new engine, and we have called it 'servo-motor' or 'subjugated motor.'")
First Known Use
1889, in the meaning defined above