servo motor

Definition and How Servo Motor Works

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Servo Motor Is ? Here are the detailed definitions, components, types, functions & how servo motors work on Arduino

Servo motors are a type of device that is quite often used in today’s era. Even servo motors are included in the smart factory industry 4.0 section. This is because the system it has uses the latest technology, so it is very suitable.

Definition of Servo Motor

servo motor


The definition of a servo motor is an electromechanical device designed using a closed-loop (servo) type control system as a drive in a circuit that produces torque and speed based on  the electric current and voltage applied.

Servo motors are available in different types, shapes, and sizes. The term servo was first used in 1859 by Joseph Facort, who implemented a feedback mechanism to help pilot the ship with steam to control the rudder.

These motors are applied to many equipment, ranging from the simplest such as electronic toys to complex ones such as machines in industry.

Servo motor is a type of electric motor that uses a closed loop type system. This system is used to control the speed and acceleration of the electric motor using a fairly high level of accuracy.

In addition, this motor is commonly used to change electrical energy into mechanical energy with the interaction of two permanent magnetic fields.

The motor can also be defined as a rotary actuator or what is called a motor, which is designed using a closed loop type control system (servo). Thus, it can be set to determine as well as ascertain how the angle position of the output shaft is.

Servo motors also act as devices that have components in the form of potentiometers, DC motors, control circuits, and a series of gears. Such a series of gears are attached to the shaft part of the DC motor.

This electronic component will cause the shaft rotation to be slow and the motor torque to increase. The potentiometer has the power to change the resistance, so that when the motor rotates, it will determine the position limit of the shaft rotation.

Servo Motor Function:

  • In General Terms

In general, this motor is used as a component in automation, robotics, semiconductor manufacturing, and CNC machining applications. Some of these components will function properly when using this motor.

  • In Industrial (Commercial) Settings

The function of the servo motor in this case is used as a position monitor while controlling engine speed. Thus, the existing machines can always be in safe control.

Servo Motor Components

servo motor

  • Small DC Motor

A small DC motor has a dynamo that rotates in a magnetic field. The dynamo is formed from the poles, namely the north and south poles, where the magnets will later change locations. When that happens, then the flow reverses to change the south and north poles of the dynamo.

  • Control Set

A control circuit is a circuit that is useful for controlling an electrical equipment or machine. The circuit can also be explained as a circuit where the motor can be controlled simultaneously and sequentially.

  • Commutator

Commutator is a component in the mechanical connector on the motor that is useful for aligning the direction of AC electricity flow to DC. Thus, it still flows in the same direction even if the terrain winding is in a rotating state.

Please note, the voltage that will be generated by the motor or is a current wave with an alternating direction. Then, the commutator will convert into a direct current.

Read also Definition and Functions of PCB (Printed Circuit Board)

Types of Servo Motors

servo motor

There are two types of servo motors that you can use, namely AC servo motors and DC servo motors. AC servo motors are generally used for high current or heavy loads, so they are often applied to industrial machines.

While DC servo motors are usually more suitable for use in smaller applications. Here’s for a full explanation:

  • Motor Servo AC

This type of servo motor is able to handle in the event of high electrical voltage or heavy loads. Therefore, AC motors are very suitable if applied to an industrial machine with the aim of controlling it.

  • Motor Servo DC

In contrast to AC motors, this type actually has the ability to handle voltages with relatively smaller loads and currents. Thus, the motor is suitable to be applied to several small machines as well as on remote controls and cars.

Meanwhile, if distinguished according to its rotary rotation, servo motors have two variants  , namely a 180⁰ servo rotation motor and a 360⁰ continuous servo rotation  motor. Here’s the explanation:

  • Motor servo standard (servo rotation 180⁰)

This type has a limited output shaft rotation of 90⁰ towards the right and 90⁰ towards the left. In other words, the total spin is only semicircular or 180⁰.

  • Motor servo rotation continuous 360⁰

For this one, it has the same properties as the standard servo type, except that the rotation of the shaft is without restriction or in other words it can rotate continuously towards the left or right.

How Servo Motor Works

servo motor

In fact, the way the servo motor works depends on the width of the modulation signal using the control system. The width of the signal will determine the position of the rotation angle on the motor shaft.

For example, the signal width has as much as 1.5 ms which will rotate the shaft towards a position at an angle of 90 degrees. Then, when the system is working with a wide signal below 1, ms, then the shaft moves in a circular direction towards an angle of 0 degrees or opposite the direction in which the clockwork rotates.

Meanwhile, if the signal is above 1.5 ms, the axis will move in a circular towards an angle of 180 degrees or in the same direction as the clockwise rotation. When the signal has been applied, the motor shaft will give a reaction in the form of movement then hold on to the targeted position.

When an external input wants to cause a change in its position, the closed loop reacts to hold it. Nevertheless, the position of the motor cannot last continuously.

So that the PMW signal needs to be repeated every 2 ms so that the position of the motor shaft can always hold it. Thus, it can be concluded that the system used keeps the shaft in an ideal position.

The working principle of servo motor is basically made using DC motor equipped with controler and position sensor so that it can have 0o, 90o, 120o, 180o or 360o movement. Each component in the servo motor above each has a function as a controler, driver, sensor, gearbox and actuator.

The motor in a servo motor is a DC motor that is controlled by the controler, then the component that functions as a sensor is a potentiometer connected to the gearbox system on the servo motor.

Advantages of Servo Motor:

  • Components that do not vibrate and do not resonate when operated.
  • The electrical power generated is proportional to the size and weight of the motor.
  • The use of electric current is proportional to a given load.
  • Resolution and accuracy can be changed easily, namely by simply replacing the encoder used.
  • Does not cause noise / noise when operating even at high speeds.


From the explanation above, you can find out how its performance and function in everyday life, precisely where the application of the motor is.


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