Servo Motors: Working, Controlling, and Applications

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Servo motors are self-contained electric modules that are often deployed in a closed-loop mechanical system. Depending upon the applications, they can help system operators maintain control over the speed and position of other parts. Servo motors require careful maintenance and repair to ensure their optimal working order.

It consists of a regular motor component integrated with a potentiometer and control circuit. When servo motors are positioned in a mechanical system, it receives electrical signals, which dictate the movement of its attached components. These components are often used in industrial and commercial sectors, which require high-precision and accuracy. Typical industrial applications include elevators, airplanes, robots, in-line manufacturing systems, and food and beverage processing lines.

Working of Servo Motors

Critical components of servo motors are:

  • Motor
  • Control circuit
  • Potentiometer

In a mechanical system, the motor is attached to the desired system component, which allows it to change speed and position when prompted by the system operator or pre-programmed automation software.

As the motor rotates the components, the potentiometer experiences a change in its resistance. The change occurred is then communicated to the control circuit, which determined the proceedings of the motor concerning speed and direction.

Servo motors also use a signal wire to create a potential control, where a signal wire can read if the potential equipment is near the desired position or not. Depending upon the equipment’s location for its end-result, it may initiate three types of reactions:

  • Speeding up the equipment’s movement to reach the desired position quicker
  • Slowing down the equipment as it nears the desired position
  • Disconnecting the power when the equipment is in its right place

Typically, servo motors are of two types – DC and AC servo motors. The classification also depends upon the type of commutation and synchronous or asynchronous rotation of the rotor and field.

Controlling a Servo Motor

Servo entails an error-sensing feedback control that is utilized to rectify the performance of a system. It often requires a generally sophisticated controller, which is a dedicated module designed specifically for use with servo motors. Such controllers allow precise control of an angular position whose speed is lowered by gears. These motors generally have a revolution cut off of 90 – 180 degrees. However, few servo motors also have a revolution cut off of 360 degrees. They do not continuously rotate as the rotation is fixed between angles. 

A servo motor is typically controlled by regulating its position using Pulse Width Modulation Technique. The pulse width, which is applied to the motor, is altered and sent for a fixed time.

The pulse width helps determine the angular position of the servo motor.


  • If any heavy load is placed on the motor, the driver will increase the current to the motor coil as it attempts rotation.
  • High-speed operations are possible


  • Generally, higher costs are involved
  • While stopping the motor operation, it starts moving back and forth, which produces vibrations, which, if not controlled, can cause unnecessary problems.

Applications of Servo Motors

Servo motors consist of large and multiple industrial applications for controlling purposes and functions. Servo motors for machines are effectively deployed to optimize the operations of powerful machines and also provide motor protection under certain conditions. 

  • Servo motors are effectively used in machine tools, industrial automation, packaging, material handling, print converting, assembly lines, CNC machines, automated manufacturing, and robotics applications.
  • Used in radio-controlled airplanes for regulating position and movement of elevators
  • Used in robots for smooth switching and accurate positioning
  • Used in the aerospace industry to maintain hydraulic fluid in various hydraulic systems
  • Servo motors are used in radio-controlled toys
  • Used in electronic devices like CD or DVD players where the motor sets the tray in motion
  • Servo motors are also used for maintaining vehicle speed in automobiles

Servo motors can handle complex tasks of internal systems that require frequent repair and maintenance. Those who need assistance in troubleshooting or repairing their servo motor systems make sure to get in touch with professionals. Servo motors have different industrial and commercial setup. Exploring and researching different products and their applications is the best way to decide what suits your requirements. You can also contact professionals of the field for selecting the best type of servo motors.

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