What is a servo motor? Its types, construction, working, advantages, disadvantages & Applications

A servo motor is a type of rotary actuator that is used to precisely control the position, speed, and acceleration of a mechanical system. It consists of a motor, a feedback device (usually an encoder), and a control system. The control system receives a command signal, compares it to the actual position feedback, and adjusts the motor’s movement accordingly.

Types of Servo Motor:

  1. DC Servo Motor: These motors use a DC power source and are commonly used in small-scale applications that require precise control.
  2. AC Servo Motor: These motors use an AC power source and are typically used in industrial applications that require high torque and accuracy.
  3. Brushed Servo Motor: These motors have a brushed commutation system, which requires regular maintenance due to the brushes wearing out over time.
  4. Brushless Servo Motor: These motors use electronic commutation and do not have brushes, resulting in reduced maintenance requirements and increased reliability.

Construction of a Servo Motor:

A servo motor consists of the following components:

  1. Stator: The stator is the stationary part of the motor and includes the motor windings.
  2. Rotor: The rotor is the rotating part of the motor and is connected to the load being controlled.
  3. Feedback Device: Typically an encoder is used to provide position feedback to the control system.
  4. Control System: The control system includes a microcontroller or a dedicated servo drive that receives the command signal and adjusts the motor’s movement based on the feedback.

Working of a Servo Motor:

When a command signal is received, the control system compares it to the position feedback from the encoder. If there is a deviation between the desired position and the actual position, the control system adjusts the motor’s speed and direction to minimize the error. This closed-loop control mechanism ensures accurate positioning of the motor shaft.

Advantages of Servo Motor:

  1. Precision: Servo motors offer high precision and accuracy in controlling position, speed, and acceleration.
  2. Speed and Torque: They provide high torque at low speeds, making them suitable for applications requiring quick starts, stops, and reversals.
  3. Dynamic Response: Servo motors have a fast dynamic response, enabling them to quickly adjust to changes in the command signal.
  4. Closed-Loop Control: The feedback system in servo motors ensures accurate positioning and reduces the chances of errors.
  5. Versatility: Servo motors can be used in various applications, including robotics, CNC machines, automation systems, and more.

Disadvantages of Servo Motor:

  1. Cost: Servo motors are generally more expensive than other types of motors, making them less suitable for cost-sensitive applications.
  2. Complexity: The control system of servo motors requires additional components and programming, increasing the complexity of the overall system.
  3. Maintenance: Brushed servo motors require regular maintenance due to the brushes wearing out, which can add to the overall cost and effort.
  4. Size and Weight: Servo motors are typically larger and heavier compared to other motor types, which may not be suitable for space-constrained applications


  1. Robotics: Servo motors are extensively used in robotic systems to control the movement of robot arms, grippers, and joints. They provide accurate positioning and smooth motion, allowing robots to perform tasks with precision.
  2. CNC Machines: Servo motors are a crucial component in computer numerical control (CNC) machines. They control the movement of axes, such as the X, Y, and Z axes in milling machines or lathes, ensuring precise positioning and rapid response to commands.
  3. Industrial Automation: Servo motors find wide applications in industrial automation systems, such as conveyor belts, packaging machines, assembly lines, and industrial robots. They provide precise control over the motion and positioning of components and enable high-speed and accurate operations.
  4. Camera Systems: Servo motors are used in camera systems, including pan-tilt-zoom (PTZ) cameras, gimbals, and camera sliders. They allow for smooth and precise movement of the camera, enabling tracking, panning, tilting, and zooming functions.
  5. Aerospace and Aviation: Servo motors play a vital role in aerospace and aviation applications. They are used in aircraft control surfaces, such as ailerons, elevators, and rudders, to ensure accurate and responsive control of the aircraft’s movement.
  6. Automotive Industry: Servo motors are employed in various automotive applications, including electric power steering systems, throttle control, brake systems, and automatic transmission control. They provide precise control and enhance the overall performance and safety of vehicles.
  7. Medical Equipment: Servo motors are utilized in medical devices and equipment, such as surgical robots, prosthetic limbs, infusion pumps, and diagnostic equipment. They enable precise and controlled movements for improved accuracy and patient safety.
  8. 3D Printing: Servo motors are used in 3D printers to control the movement of the print head, extruders, and build platform. They ensure accurate positioning and layer-by-layer deposition of the printing material.

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