A servo motor is an electro mechanical device that translates electrical signals into precise mechanical movement.

It operates using a closed-loop control system(Visit here for details).

It helps in maintaining accurate position, speed, and torque based on feedback from sensors.

Comprising a motor, feedback mechanism, and control circuit, servo motors excel in precision and versatility.

Servo motors find widespread use in robotics, manufacturing, aerospace, and more.

From controlling robotic limbs to guiding machinery in assembly lines, these motors are integral to modern automation.

Working principle:

The working principle of a servo motor revolves around precise control of position, speed, and torque through a closed-loop control system. It consists of various components working in tandem to achieve accurate motion control.

Components of a Servo Motor:

Motor: Primarily a DC motor, though AC motors are also used. This motor drives the mechanical system and determines the motor’s capability in terms of torque and speed.

Feedback Device: This component provides information about the motor’s current position, speed, or both. Encoders, potentiometers, or resolvers are commonly used as feedback devices. Among these, encoders are prevalent for their high precision in detecting shaft rotation.

Control System: The control circuit interprets feedback data and generates signals to regulate the motor’s performance. It continuously compares the desired output with the actual output. By doing so, adjustments are made as needed to maintain the desired position or speed.

Operational Sequence (or working principle):

Input Signal: The servo motor receives a control signal, usually in the form of a pulse width modulation (PWM) signal or an analogue voltage. Thus, it helps in representing the desired position, speed, or torque.

Feedback Mechanism: As the motor moves, a feedback device, like an encoder, continuously monitors. It tracks the motor’s position or speed. It provides real-time data. This data goes to the control circuit.

Error Calculation: The control circuit compares the actual feedback data with the desired input signal. Any deviation between these two is referred to as an error signal.

Adjustment: Based on this error signal, the control system sends commands to the motor to correct and minimize the error. The motor adjusts its position, speed, or torque accordingly.

Closed-Loop System: This continuous monitoring and adjustment create a closed-loop control system. The cycle of receiving input, comparing it to the feedback, and making adjustments occurs rapidly and continuously. Hence, it ensures that the motor operates precisely as commanded.

Operational Modes of Servo Motors:

Position Control: The motor maintains a specific position based on the input signal. Feedback devices constantly monitor the motor’s position, and the control system makes adjustments to ensure it stays at the desired location.

Velocity Control: In this mode, the servo motor maintains a specific speed. The feedback system measures the motor’s speed, and the control circuit adjusts the motor’s performance to maintain the desired speed.

Torque Control: This mode ensures the motor generates a specific amount of torque. The feedback system measures the torque output. The control system modifies the motor’s behaviour to meet the required torque.

Functions of Servo Motor:

Precise Motion Control:

Servo motors are renowned for their ability to provide accurate and repeatable motion control.

They excel in maintaining specific positions or speeds.

This makes them invaluable in applications requiring high precision.

Such applications include CNC machines, robotic arms, and automated manufacturing processes.

Closed-Loop Control System:

The fundamental function of a servo motor revolves around a closed-loop control system.

This system continuously receives feedback from sensors (such as encoders or potentiometers) to monitor the motor’s actual position or speed.

It compares this information with the desired output.

Then, it adjusts the motor’s behaviour to minimize any discrepancy.

This ensures accuracy in motion control.

Adaptability and Versatility:

Servo motors are versatile and adaptable to various applications.

Motors can work in various modes: position control, velocity control, or torque control.

This versatility helps them to fulfil specific needs in many industries.

This adaptability makes them indispensable in diverse fields, from manufacturing machinery to aerospace systems.

High-Speed Response and Agility:

Servo motors have rapid response times.

They can quickly change direction, speed, or torque based on input signals.

This agility is crucial in applications needing swift and precise movements.

For instance, robotic manipulators rely on this responsiveness for efficiency and safety.

Energy Efficiency:

These motors are recognized for their energy efficiency.

They precisely control motion and consume power only when needed.

This optimization of energy usage helps enhance overall system efficiency and cuts down operational costs.

Integration in Automation Systems:

Servo motors are crucial in industrial automation.

They power conveyor belts, robotic arms, and packaging machinery. They ensure precise movement in various automated systems.

These motors maintain accuracy in complex tasks, streamlining production and enhancing efficiency in manufacturing processes.

Aerospace and Automotive Applications:

In aerospace, servo motors are utilized.

They are used in aircraft control surfaces, for example, in ailerons and flaps.

They ensure precise and responsive manoeuvrability.

In the automotive industry, they play a crucial role.

They are essential in electric power steering systems.

They are also vital for throttle control and other applications.

These applications require accurate and controlled motion.

Consumer Electronics:

Servo motors are used in consumer electronics.

They are found in devices like cameras, printers, and disk drives.

These motors are essential for precise positioning or controlled movement.

They help to achieve optimal performance in these devices.


Servo motors find extensive applications across various industries. It is due to their precise control, adaptability, and ability to maintain specific positions, speeds, or torques. Some notable applications include:


In robotics, servo motors act as the powerhouse behind the precise movement of robot arms, joints, and end-effectors.

They enable robots to perform delicate and accurate tasks, such as assembly, pick-and-place operations, and handling fragile objects.

CNC Machinery:

In CNC machines, servo motors control cutting tool movements.

They ensure accurate and high-speed machining.

These motors allow precise positioning and controlled motion in milling, turning, and other processes.

Industrial Automation:

Servo motors are vital in industrial automation.

They power conveyor belts, packaging machinery, and production lines.

These motors ensure precise movement and positioning of materials or products, boosting efficiency in manufacturing facilities.

Aerospace and Aviation:

In the aerospace industry, servo motors control critical functions such as aircraft control surfaces (flaps, rudders, ailerons), ensuring precise and responsive manoeuvrability.

They also operate mechanisms in landing gears and cabin systems, contributing to the safety and performance of aircraft.

Automotive Systems:

Servo motors are employed in various automotive applications. This includes electric power steering, throttle control, braking systems, and automated transmission systems.

Their precise control enables smoother and more responsive vehicle operation, enhancing safety and driving comfort.

Consumer Electronics:

From cameras and printers to home appliances, servo motors are present in numerous consumer electronics.

They facilitate precise lens movement in cameras for autofocus functionality.

In printers they control paper feed.

They also regulate various mechanisms in home appliances, ensuring smooth and accurate operation.

Medical Devices:

In the medical field, servo motors power equipment such as infusion pumps, robotic surgery systems, and diagnostic devices.

Their precise control and accuracy aid in performing intricate medical procedures and ensure precise diagnostics and treatment.

Renewable Energy:

Servo motors contribute to renewable energy applications, such as solar panel positioning and wind turbine blade adjustments.

They enable efficient tracking of the sun in solar panels.

Moreover, it optimizes the angle of the blades for wind turbines, maximizing energy.


Using a servo motor with an Arduino is a popular and straightforward way to control its movement. Here is a basic overview of how you can connect and control a servo motor using an Arduino:

Components Needed:

Servo Motor: Choose a suitable servo motor compatible with Arduino.

Arduino Board: Any Arduino board would work, such as Arduino Uno, Nano, or Mega.

Jumper Wires: For connecting components.

Power Source: For power source, USB cable or external power supply is needed for the Arduino.

Steps to Control Servo Motor with Arduino:

Wiring Connections:

Connect the servo motor and Arduino as follows:

Servo Motor Signal Pin (usually orange or yellow): Connect to a PWM pin on the Arduino (e.g., pin 9 or 10).

Power (usually red): Connect to an external power source (if needed) or the 5V pin on the Arduino.

Servo Motor Ground (usually brown or black): Connect to the ground (GND) pin on the Arduino.

Arduino Power: Connect the Arduino to a power source (USB or external power supply).

Arduino Code:

Compose a basic Arduino code to manage the servo motor.

The code typically consists of three main functions: `attach () `, `write () `, and `delay () `.

Code Implementation (Arduino IDE):

#include <Servo.h>

Servo myServo;                   // Create a servo object

void setup () {

  myServo.attach(9);           // Attach the servo to pin 9


void loop() {

  myServo.write(90) ;          // Move the servo to 90 degrees

  delay (1000) ;                   // Wait for 1 second

  myServo.write(0) ;           // Move the servo to 0 degrees

  delay(1000) ;                  // Wait for 1 second



`#include <Servo.h>`: This line includes the servo library in your code.

`Servo myServo; `: Creates a servo object named `myServo`.

`myServo.attach (9); `: Attaches the servo to pin 9 on the Arduino.

`myServo.write (90); `: Moves the servo to 90 degrees.

`delay (1000);`: This line pauses the program for 1 second.

The `loop()` function continuously moves the servo back and forth between 0 and 90 degrees with a 1-second delay.

Uploading Code:

Link your Arduino board to your computer using a USB cable.

Open the Arduino IDE, paste the code, and click on the upload button.

Once uploaded, the servo motor should start rotating between 0 and 90 degrees at intervals of one second.


Always power the servo motor using an external power supply if it requires higher current than the Arduino can provide.

Use the appropriate digital pins on the Arduino for signal connection.

Ensure the servo motor and Arduino share a common ground.

This example serves as a basic introduction to controlling a servo motor with an Arduino. You can expand on this by experimenting with different angles, speeds, and incorporating sensor inputs to create more complex servo-controlled projects.

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