172:
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25:
478:, allowing elaborate mechanisms between the control room and the engine to be greatly simplified. Steam steering engines had the characteristics of a modern servomechanism: an input, an output, an error signal, and a means for amplifying the error signal used for negative feedback to drive the error towards zero. The Ragonnet
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type 2 servos: under steady-state conditions they produce a constant value of the output with null error signal. A constant rate of change of the reference implies a null error in tracking the reference. A constant rate of acceleration of the reference implies a constant error in tracking the
401:
are not considered to be servomotors, although they too are used to construct larger servomechanisms. Stepper motors have inherent angular positioning, owing to their construction, and this is generally used in an open-loop manner without feedback. They are generally used for medium-precision
405:
RC servos are used to provide actuation for various mechanical systems such as the steering of a car, the control surfaces on a plane, or the rudder of a boat. Due to their affordability, reliability, and simplicity of control by microprocessors, they are often used in small-scale
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at the output. Any difference between the actual and wanted values (an "error signal") is amplified (and converted) and used to drive the system in the direction necessary to reduce or eliminate the error. This procedure is one widely used application of
414:(PWM) signals to the servo. The electronics inside the servo translate the width of the pulse into a position. When the servo is commanded to rotate, the motor is powered until the potentiometer reaches the value corresponding to the commanded position.
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to form a servomechanism. This assembly may in turn form part of another servomechanism. A potentiometer provides a simple analog signal to indicate position, while an encoder provides position and usually speed feedback, which by the use of a
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type 1 servos: under steady-state conditions they produce a constant value of the output with null error signal, but a constant rate of change of the reference implies a constant error in tracking the reference;
299:
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Servomotors are used for both high-end and low-end applications. On the high end are precision industrial components that use a rotary encoder. On the low end are inexpensive
199:. They operate on the principle of negative feedback, where the control input is compared to the actual position of the mechanical system as measured by some type of
280:
has a magnetic servo system with sub-micrometer positioning accuracy. In industrial machines, servos are used to perform complex motion, in many applications.
154:
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
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allow more precise control of position and thus faster achievement of a stable position (for a given motor power). Potentiometers are subject to
753:
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or other position feedback mechanism to ensure the output is achieving the desired effect. Following a specified motion trajectory is called
150:
or error-correction signals help control mechanical position, speed, attitude or any other measurable variables. For example, an automotive
528:
in 1928 and began using RPC to control searchlights in the early 1930s. During WW2 RPC was used to control gun mounts and gun directors.
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38:
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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550:" or the slavemotor, first used by J. J. L. Farcot in 1868 to describe hydraulic and steam engines for use in ship steering.
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Power-assisted ship steering systems were early users of servomechanisms to ensure the rudder moved to the desired position.
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G. W. Younkin, Industrial Servo
Control Systems – Fundamentals and Applications – Second Edition, Taylor and Francis, 2007.
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is used to correct the action of the mechanism. In displacement-controlled applications, it usually includes a built-in
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type 0 servos: under steady-state conditions they produce a constant value of the output with a constant error signal;
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41:
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which use a free-running motor and a simple potentiometer position sensor with an embedded controller. The term
914:
256:, satellite-tracking antennas, remote control airplanes, automatic navigation systems on boats and planes, and
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and "positioner". This is a servo which ensures the valve opens to the desired position regardless of friction
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mechanism was a general purpose air or steam-powered servo amplifier for linear motion patented in 1909.
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may deserve equal credit for the feedback concept, with several patents between 1862 and 1868.
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634:. London: Peter Peregrinus Ltd. On behalf of the Institution of Electrical Engineers.
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indicates the capability of the servo to follow rapid changes in the commanded input.
802:
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Clarence W. de Silva. Mechatronics: An
Integrated Approach (2005). CRC Press. p. 787.
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is most often used to describe the inexpensive devices that employ a potentiometer.
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was developed to control engine speed for maneuvering aircraft. Fuel controls for
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uses mechanical governors; another early application was to govern the speed of
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Modern servomechanisms use solid state power amplifiers, usually built from
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when the temperature changes whereas encoders are more stable and accurate.
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is an earlier example of automatic control, but since it does not have an
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computer. The Royal Navy began experimenting with Remote Power
Control (
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Servos can be classified by means of their feedback control systems:
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uses closed-loop feedback, which classifies it as a servomechanism.
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and improve dynamic response. In closed-loop control, error-sensing
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generally refers to a high-end industrial component while the term
311:
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applications. A standard RC receiver (or a microcontroller) sends
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cameras also use a servomechanism to accurately move the lens. A
268:
which use servos to actuate the aircraft's control surfaces, and
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is generally considered the first powered feedback system. The
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engines employ either hydromechanical or electronic governing.
208:. Typical servos can give a rotary (angular) or linear output.
771:"How to drive a servo motor & its industrial applications"
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136:
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The origin of the word is believed to come from the French "
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832:
Eugine L. Ragonnet, Controlling
Mechanism for Locomotives,
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321:, and the black object on top of the motor is the optical
557:. More complex control systems use proportional control,
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Electrical servomechanisms were used as early as 1888 in
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The first feedback position control device was the ship
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Positioning servomechanisms were first used in military
61:"Servomechanisms" redirects here. For the company, see
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Electrical servomechanisms require a power amplifier.
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The term correctly applies only to systems where the
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is a specific type of motor that is combined with a
873:
Rane Pro Audio
Reference definition of "servo-loop"
463:was a pioneer. His patented design was used on the
452:, it is not usually considered a servomechanism.
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561:, and state space control, which are studied in
314:. The black section at the bottom contains the
272:which use RC servos for the same purpose. Many
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878:Seattle Robotics Society's "What is a Servo?"
718:Baldor Electric Company – Servo Control Facts
252:equipment. Today servomechanisms are used in
34:needs attention from an expert in Engineering
798:A History of Control Engineering, 1800–1930
868:Ontario News "pioneer in servo technology"
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632:A History of Control Engineering 1930–1955
474:The telemotor was invented around 1872 by
260:-gun control systems. Other examples are
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689:(2 ed.). Oxford University Press.
683:Escudier, Marcel; Atkins, Tony (2019).
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220:is another type of servomechanism. The
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686:A Dictionary of Mechanical Engineering
44:may be able to help recruit an expert.
730:Anaheim Automation: Servo Motor Guide
695:10.1093/acref/9780198832102.001.0001
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539:devices. Small servos may use power
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500:saw the development of electrical
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890:different types of servo motors"
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183:A common type of servo provides
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307:The grey/green cylinder is the
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795:Bennett, Stuart (1986-01-01).
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177:valve with pneumatic actuator
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512:amplifiers were used in the
228:. Prior to World War II the
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602:Fractional horsepower motor
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504:servomechanisms, using an
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333:Small R/C servo mechanism.
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91:for the position and its
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508:as the power amplifier.
230:constant speed propeller
653:Engineering Cybernetics
387:radio-controlled models
270:radio-controlled models
254:automatic machine tools
187:. Commonly, servos are
42:WikiProject Engineering
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412:pulse-width modulation
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103:. It often includes a
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569:Types of performances
563:modern control theory
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340:2. position feedback
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294:servo (radio control)
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630:Bennett, S. (1993).
385:(RC servos) used in
383:radio control servos
216:Speed control via a
63:Servomechanisms Inc.
834:U.S. Patent 930,225
516:tape drive for the
461:John McFarlane Gray
109:closed-loop control
73:control engineering
883:2007-07-11 at the
822:Andrew Betts Brown
756:2017-03-27 at the
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113:steady-state error
808:978-0-86341-047-5
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559:PID control
541:transistors
510:Vacuum tube
487:Elisha Gray
302:Industrial
264:systems in
262:fly-by-wire
234:gas turbine
107:, and uses
899:Categories
780:31 January
667:References
661:HathiTrust
584:reference.
431:James Watt
391:servomotor
359:servomotor
309:brush-type
304:servomotor
290:Servomotor
284:Servomotor
201:transducer
111:to reduce
105:servomotor
95:, such as
69:mechanical
537:thyristor
506:amplidyne
467:in 1866.
446:amplifier
316:planetary
274:autofocus
197:pneumatic
193:hydraulic
881:Archived
754:Archived
596:See also
518:UNIVAC I
514:UNISERVO
438:governor
408:robotics
312:DC motor
266:aircraft
218:governor
189:electric
148:feedback
125:servoing
97:velocity
651:(1954)
617:Synchro
418:History
121:encoder
99:, of a
87:) is a
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533:MOSFET
240:Others
141:servus
131:. The
524:) on
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365:or a
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137:Latin
133:servo
85:servo
803:ISBN
782:2023
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636:ISBN
588:The
450:gain
347:gear
292:and
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129:verb
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71:and
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