What is the Difference Between Servo Motor vs DC Motor

What is DC Motor?

What is DC Motor

A direct current (DC) motor is a type of electric machine that converts electrical energy into mechanical energy. DC motors take electrical power through direct current, and convert this energy into mechanical rotation.
DC motors use magnetic fields that occur from the electrical currents generated, which powers the movement of a rotor fixed within the output shaft. The output torque and speed depends upon both the electrical input and the design of the motor.

What is Servo Motor?

What is Servo Motor?

A servomotor (or servo motor) is a rotary actuator or linear actuator that allows for precise control of angular or linear position, velocity, and acceleration. It consists of a suitable motor coupled to a sensor for position feedback. Servomotors are used in applications such as robotics, CNC machinery, or automated manufacturing.
It also requires a relatively sophisticated controller, often a dedicated module designed specifically for use with servomotors. Servomotors are not a specific class of motor, although the term servomotor is often used to refer to a motor suitable for use in a closed-loop control system.

Comparison between Servo and DC motor

Basic Servo Motor DC Motor
Wire system The Servo motor is three wire system known as power, ground and control. DC motor is two wire system known as power and ground
Assembly It has an assembly of four things DC motor, gearing set, control circuit and a position sensor. DC motor is an individual machine with no assembly.
Rotation  Servo motor does not rotate freely and continuously like DC motor. Its rotation is limited to 180⁰ Movement of DC motor is continuous
Examples They are used in robotic arms, legs or rudder control. DC motor is used in car wheels, fans etc.

Pros and Cons of DC motors:

Pros:

  1. The DC motors are best suitable for the high speed applications.
  2. The DC motors are used in the application, where the continuous rotation is required. Such as, Remote controlled cars, fans, and vibrators etc..,
  3. The DC motor does not require any external circuit for speed control. By reducing the voltage, the speed can be reduced.
  4. The DC motors are available in different voltage levels. And has different variants and speed.
  5. The DC motors can run for longer period of time.

Cons:

  1. The DC motors are not suitable for the application, where the precise angular movement is required.
  2. The DC motors provide less torque without the external gear system attached to it.

Pros and Cons of Servo Motor:

Pros:

  1. The position of servo motors can be controlled more precisely than those of standard DC motors, and they usually have three wires (power, ground & control)
  2. As the servo motors are designed for precise angular movement, they are more suitable for the applications where the angular movement should be accurate. So that, they are more suitable for the robotics application.
  3. The servo motors are available for wide range of torques and angular rotations.
  4. The servo motors can be easily interfaced with the microcontroller for obtain accurate angular rotation.
  5. There are many libraries available for different microcontroller for interfacing the servo motor.

Cons:

  1. The servo motor can just rotate from 0-180 degrees. So that it is not suitable for the applications where continuous rotation is required.
  2. The servo motor need an external circuitry to control the angular rotation.
  3. The servo motor only be rotated electrically, if tired to apply force to rotate externally, then the gear systems inside the servo motors may gets damaged.

Why is servo motor better than DC motor?

As mentioned above the servo motor is mainly built to provide precise angular rotation. But the servo motor is also a kind of DC motor which is specifically designed to work based on the PWM signal. And also the servo motor has high torque as compared to the DC motor. This makes the servo motor more suitable for the application where you want to use any driver for the precise angular rotation.

Is servo motor a DC motor:

this image shows servo motor construction

We can talk about servo motors as an assembly of four things: a DC motor, a gearing set, a control circuit and a position-sensor.

In industry servo motors are known as motors that can be controlled most precisely. Comparing servo with standard DC motors, servos usually have three wires (power, ground and control). Power to servo motors is constantly applied. Servo controller regulates the current draw to drive the motor. These motors are designed for more specific tasks where position needs to be defined.  Moreover servo motors are used for accurate tasks, for example, to move robotic arm or robot leg within a certain range, move camera to certain object and etc.

Although, we must mention that servo motors do not rotate freely like a standard DC motor unless it’s modified for continuous rotation.

Do servo motor use AC or DC:

When it comes to the servo motors which is rated to drive very lower powered application, then the DC servo motors are used. But when used in industries, where high torque is required, there the AC servo motors are preferred more than DC servo motors.

Also Read about Stepper Motors

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