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I am studying about basic of motors and i came across two terms

Is there any difference between two terms servos and servo motors? or they both exactly same??

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In common usage, the term “servo” is an abbreviation of “servo motor”, particularly when referring to the low-cost lightweight servo motors originally used in radio control models ("RC servos"), which have de-facto-standard control signals and sizes.

More formally, “servo” is an abbreviation of “servomechanism”, which is a control system that uses negative feedback to steer the system to the target accurately. A servomechanism involving a motor does not necessarily seek a target position; for example a cruise control or governor controls speed. Servomechanisms can also control non-mechanical states.


A servo motor is not a distinct type of motor in the way “induction”, “brushless” and such are; you can turn any motor into a servo motor by adding a sensor to detect its position or speed, and connecting this combination to a controller. The controller may or may not be considered part of the "servo motor" itself; in particular, in industrial controls the controller is likely to be a separate unit.


In most cases, if you see the word “servo” and you're not reading about control systems, it will be referring to a servo motor, but it may occasionally refer to a different control system; use context to determine whether it makes sense that there's a motor involved.

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    \$\begingroup\$ I have seen steam-powered servos in the engine room of a steam riverboat on the Mississippi river. The actuator was of course, a steam piston and cylinder arrangement, and the negative feedback was provided by a mechanical linkage operating a valve. \$\endgroup\$ – Solomon Slow Aug 29 at 13:58
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    \$\begingroup\$ 'Servo' normally means servomechanism; if a motor is part of a servomechanism it would be called a servo motor \$\endgroup\$ – Chu Aug 29 at 15:57
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    \$\begingroup\$ Except that if you buy a "servo motor" from a hobby robotics place you get a RC servo, which is a motor, geartrain, and amplifier. If you buy a "servo motor" from an industrial supply house, you get just a motor that happens to be optimized for servo applications. They're very different things, with, unfortunately, the same name. \$\endgroup\$ – TimWescott Aug 29 at 16:14
  • \$\begingroup\$ @TimWescott Thanks, I've tried to incorporate that information. \$\endgroup\$ – Kevin Reid Aug 29 at 16:27
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The terms are often used interchangeably, but servo motors are a subset of servos. Any control system that has an actuator and a feedback sensor designed to implement closed loop control is a servo. A servo could control rotational positional, linear positional, thermal, chemical ph, pressure, optical brightness or color, etc.

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In the radio control world and in industry, "servo" means "servomechanism", means some gizmo that gets commands and drives the output to a commanded position. In the radio control world since about the mid 1970's, the command has been a pulse whose width varies between 1ms and 2ms, and that occurs at a rate of 50-60Hz.

In the hobby robotics world, "servo motor" means an RC servo.

In industry about 20 years ago, "servo motor" meant just a motor which was optimized for use in a servomechanism -- meaning that low friction, low cogging torque, and general good behavior was more important than a super high power to weight (or power to size) ratio. It is, most emphatically, a different thing than a "servo motor" than you'd by from Bob's Hobby Robot Factory.

More recently in industry, there are "smart servo motors", or more properly "servo motor with integrated drive" which get power and a speed (not position) command, and that command is not in the form of a 1 to 2 millisecond pulse that repeats at 50Hz.

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