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A servomechanism, or servo, is a device used to provide control of a desired operation through the use of feedback. An example of a servomechanism is a home furnace controlled by a thermostat. Image File history File links Download high resolution version (300x630, 47 KB)small servomechanism as used for radio controled models small electric motor position feedback potentiometer reduction gear actuator scan, upload MH 13:51, July 23, 2005 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this...
Image File history File links Download high resolution version (300x630, 47 KB)small servomechanism as used for radio controled models small electric motor position feedback potentiometer reduction gear actuator scan, upload MH 13:51, July 23, 2005 (UTC) File history Legend: (cur) = this is the current file, (del) = delete this...
For other kinds of motors, see motor. ...
It has been suggested that Determining emf of primary cells using potentiometer be merged into this article or section. ...
Spur gears found on a piece of farm equipment A gear is a wheel with teeth around its circumference, the purpose of the teeth being to mesh with similar teeth on another mechanical device -- possibly another gear wheel -- so that force can be transmitted between the two devices in a...
An actuator is a mechanical device for moving or controlling a mechanism or system. ...
It has been suggested that this article or section be merged with Feedback loop. ...
A common type of servo provides position control. Servos are commonly electrical or partially electronic in nature, using an electric motor as the primary means of creating mechanical force. Other types of servos use hydraulics, pneumatics, or magnetic principles. Usually, servos 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 sort of transducer at the output. Any difference between the actual and wanted values (an "error signal") is amplified and used to drive the system in the direction necessary to reduce or eliminate the error. An entire science known as control theory has been developed on this type of system. For other kinds of motors, see motor. ...
In physics, force is anything that can cause a massive body to accelerate. ...
Table of Hydraulics and Hydrostatics, from the 1728 Cyclopaedia. ...
Table of Pneumaticks, 1728 Cyclopaedia This article is about the tool. ...
In physics, magnetism is a phenomenon by which materials exert an attractive or repulsive force on other materials. ...
This article does not cite any references or sources. ...
A transducer is a device, usually electrical or electronic, that converts one type of energy to another. ...
In engineering and mathematics, control theory deals with the behavior of dynamical systems. ...
Servos are found in many applications. They operate the throttle of engines that use a cruise control. CNC machines use servos to make the motion axes of a machine tool follow the desired tool path. Fly-by-wire systems in aircraft use servos to actuate the control surfaces that control the aircraft. Radio-controlled models use RC servos for the same purpose. Many autofocus cameras also use a servomechanism to accurately move the lens, and thus adjust the focus. In an engine, the throttle is the mechanism by which the engines power is increased or decreased. ...
Cruise control (sometimes known as speed control or Autocruise) is a system to automatically control the speed of an automobile. ...
A CNC Turning Center A CNC Milling Machine The abbreviation CNC stands for computer numerical control, and refers specifically to a computer controller that reads G-code instructions and drives the machine tool, a powered mechanical device typically used to fabricate metal components by the selective removal of metal. ...
A machine tool is a powered mechanical device, typically used to fabricate metal components of machines by machining, which is the selective removal of metal. ...
A flight control system consists of the flight control surfaces, the respective cockpit controls, connecting linkage, and necessary operating mechanisms to control aircraft in flight The basic fundamentals of aircraft controls has been explained in aeronautics. ...
“Flying Machine†redirects here. ...
1:10 scale radio controlled car (Saab Sonett) A radio-controlled model (or RC model) is a model that is steerable with the use of radio control. ...
RC servos are position controlled DC motors typically employed in radio-controlled models. ...
Typical servos give a rotary (angular) output. Linear types are common as well, using a screw thread or a linear motor to give linear motion. Look up screw in Wiktionary, the free dictionary. ...
A linear motor is essentially a multi-phase alternating current (AC) electric motor that has had its stator unrolled so that instead of producing a torque (rotation) it produces a linear force along its length. ...
Another device commonly referred to as a servo is used in automobiles to amplify the steering or braking force applied by the driver. In this form this device is not a true servo, but rather a mechanical amplifier. “Car†and “Cars†redirect here. ...
Power steering is a system for reducing the steering effort on cars by using an external power source to assist in turning the wheels. ...
This article needs additional references or sources for verification. ...
In physics, force is anything that can cause a massive body to accelerate. ...
For the British rock band of the same name, see Amplifier (band). ...
In industrial machines, servos are used to perform complex motion.
RC servos
RC servos are servos typically employed in industrial robotics, automation, and radio-controlled models. They are also used to provide actuation for various mechanical systems such as the steering of a car, the flaps on a plane, or the rudder of a boat. Robotics is the science and technology of robots, their design, manufacture, and application. ...
This article does not cite any references or sources. ...
1:10 scale radio controlled car (Saab Sonett) A radio-controlled model (or RC model) is a model that is steerable with the use of radio control. ...
RC servos are comprised of a DC motor mechanically linked to a potentiometer. Pulse-width modulation (PWM) signals sent to the servo are translated into position commands by electronics inside the servo. When the servo is commanded to rotate, the DC motor is powered until the potentiometer reaches the value corresponding to the commanded position that it's ordered. Pulse-width modulation of a signal or power source involves the modulation of its duty cycle, to either convey information over a communications channel or control the amount of power sent to a load. ...
Due to their affordability, reliability, and simplicity of control by modern microprocessors, servo motors are often used in small-scale robotics applications.
The servo is controlled by three wires: ground (black/orange), power (red) and control (brown/other colour) and will move based on the pulses sent over the control wire. This wiring sequence is not true for all servos, for example the S03NXF Std. Servo is wired as brown(negative), red (positive) and orange (signal). The pulses sent over the control wire set the angle of the servo horn. The servo expects a pulse every 20 ms in order to gain correct information about the angle. The width of the servo pulse dictates the range of the servo's angular motion.
A servo pulse of 1.5 ms width will set the servo to its "neutral" position, or 90°. For example a servo pulse of 1.25 ms could set the servo to 0° and a pulse of 1.75 ms could set the servo to 180°. The physical limits and timings of the servo hardware varies between brands and models, but a general servo's angular motion will travel somewhere in the range of 180° - 210° and the neutral position is almost always at 1.5ms.
Servo motors are often powered from nickel-cadmium battery packs common to most RC devices. Voltage ratings vary from product to product, but most servos are operated at 4.8 V DC or 6.0 V DC (a 4 or 5 cell battery). The nickel-cadmium battery (commonly abbreviated NiCd and pronounced nye-cad) is a popular type of rechargeable battery for portable electronics and toys using the metals nickel (Ni) and cadmium (Cd) as the active chemicals. ...
Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...
See also A synchro is a type of rotary electrical transformer that is used for measuring the angle of a rotating machine such as an antenna platform. ...
Motion control is a sub-field of automation, in which the position and/or velocity of machines are controlled using some type of device such as a hydraulic pump, linear actuator, or an electric motor, generally a servo. ...
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