Servo Motor

A servo motor is a simple electric motor controlled by servomechanism. When a motor is used as a controlled device and is connected to a servomechanism, it is referred to as a DC Servo Motor. The controlled motor is known as an AC Servo Motor if AC powers it.

servo motor

What is a Servo Motor?

:small_blue_diamond: A servo motor is a type of motor that has a high degree of precision in rotation. Servo motors often have a control circuit that provides feedback on the current position of the motor shaft; this feedback allows them to rotate with great precision. A servo motor is used when you wish to spin an object at a specified angle or distance. It consists of nothing more than a simple motor connected to a servo mechanism.

:small_blue_diamond: A DC servo motor is powered by a DC power supply, whereas an AC power supply powers an AC servo motor. For the sake of this tutorial, we shall discuss the operation of a DC servo motor. There are many more varieties of servo motors based on the type of gear arrangement and operating characteristics in addition to these primary classifications. A gear arrangement on a servo motor allows us to produce a very high torque servo motor in a tiny and lightweight package. They are employed in various applications, including toy cars, RC helicopters and planes, robotics, and so on, because of their characteristics.

:small_blue_diamond: Servo motors are measured in kilogrammes per centimetre (kg/cm), with most hobby servo motors rated at 3kg/cm, 6kg/cm, or 12kg/cm. This kg/cm value indicates how much weight a servo motor can raise over a certain distance. Consider the following scenario: If the load is suspended 1cm from the motor’s shaft, a 6kg/cm Servo motor should be able to lift 6kg; the greater the distance, the lower the weight-bearing capacity. An electrical pulse determines a servo motor’s position, and its circuitry is located beside the motor.


Servo motors are a type of motor that rotates with a high level of precision. Toy automobiles, RC helicopters, and planes are just a few of the things they’re used for. An electrical pulse determines the position of a servo motor, and electronics are situated next to the motor.

Theory of Servo Motors

:small_blue_diamond: A unique form of electric motor application is when the motor’s rotation is required for only a specific angle. For these applications, we need some unique motors with unique arrangements that cause the motor to revolve at a specific angle for a given electrical input (signal). The use of a servo motor is necessary for this.

:small_blue_diamond: A servo motor is typically a simple DC motor with added servomechanism to regulate specified angular rotation (a typical closed-loop feedback control system). Servo systems are frequently employed in industrial applications nowadays.

:small_blue_diamond: Servo motors are also extensively employed to regulate the direction of motion in remote-controlled toy automobiles. They are also widely utilised as the motor that moves the tray of a CD or DVD player. Aside from this, we witness hundreds of servo motor applications in our everyday lives.

:small_blue_diamond: The key benefit of utilising a servo is that it gives angular accuracy, meaning it will only rotate as far as we want it to before stopping and waiting for the next signal. The servo motor differs from a typical electric motor in that it begins to rotate as soon as power is applied and continues until the power is turned off. We can’t regulate how fast an electrical motor rotates, but we can control how fast it rotates and switch it on and off. Many novice Arduino starting kits feature small servo motors, which are simple to operate in small electronics projects.


A servo motor is a simple DC motor with a servomechanism that can rotate at a specific angle. The main advantage of using a servo is that it provides angular precision, which means that it will only rotate as far as we want it to before halting and waiting for the next signal.

How do servo motors work?

:small_blue_diamond: Servo motors have been used in a variety of applications for a long time. They’re small in size, yet they’re powerful and energy-efficient. Thanks to their features, they can be used to control remote-controlled or radio-controlled toy cars, robots, and aeroplanes. Industrial applications, robotics, in-line manufacturing, pharmaceutics, and food services all use servo motors. How, on the other hand, do the little guys operate?

:small_blue_diamond: The servo circuitry is integrated into the motor unit and has a positionable shaft, which is commonly gear-driven. The motor is controlled by an electronic signal that regulates how far the shaft can move.


Toy cars, robots, and planes can all be controlled with servo motors. They’re little, but they’re extreme and energy-efficient. They’re used in various applications, including industrial applications, robotics, in-line production, pharmaceutics, and food services.

What is contained within the Servo?

:small_blue_diamond: Take a look under the hood of the Servo to completely comprehend how it functions. A little DC motor, a potentiometer, and a control circuit make up the inside setup. Gears connect the motor to the control wheel. The resistance of the potentiometer changes as the motor turns, allowing the control circuit to accurately determine how much movement there is and in which direction.

:small_blue_diamond: When the motor shaft reaches the desired position, the power to the motor is turned off. If this is not the case, the motor is turned in the proper direction. Electrical pulses are supplied through the signal wire to send the desired position. The speed of the motor is proportional to the distance between its current and desired positions.

:small_blue_diamond: As a result, if the motor is close to the intended location, it will turn slowly, and if it is not, it will turn quickly. Proportional control is the term for this. This means the motor will only work as hard as it needs to complete the task at hand, making it a very efficient little guy.

Specification of AC Servo Motors

Type GSM62AE
Voltage 230V
Power 100W
Speed 50 rpm
Moment of inertia (J) 0.052 kg.cm2
Friction coefficient (B) 0.01875
GB ratio 36
Radius of the output shaft 0.0175m


Take a look behind the Servo’s hood to get a better understanding of how it operates. The inner arrangement consists of a small DC motor, a potentiometer, and a control circuit. The power to the motor is shut off when the motor shaft reaches the required position.

What controls the Servo?

:small_blue_diamond: Three wires come out of every engine. Two of them will be utilised for supply (positive and negative) and one for the signal sent from the MCU.

:small_blue_diamond: The control wires offer PWM (Pulse with Modulation), which is used to drive the servo motor. There are three types of pulses: minimum, maximal, and repetition rate. From its neutral position, the servo motor may turn 90 degrees in either direction. Every 20 milliseconds (ms), the servo motor expects to see a pulse, and the length of the pulse determines how far the motor turns. A 1.5ms pulse, for example, will spin the motor to 90°. If the pulse is shorter than 1.5ms, the shaft will move to 0°, and if it is more significant than 1.5ms, the Servo will turn to 180°.

:small_blue_diamond: The duration of the applied pulse regulates the angle of rotation of a servo motor to its Control PIN, which operates on the PWM (Pulse width modulation) principle. Servo motors are made comprised of a DC motor and certain gears that are controlled by a variable resistor (potentiometer). Gears transform the high-speed force of a DC motor into torque.

:small_blue_diamond: We know that WORK= FORCE X DISTANCE and that in a DC motor, the force is smaller and the distance (speed) is more significant, whereas in a servo, the force is more and the distance is shorter. The Servo’s output shaft is attached to the potentiometer, used to compute the angle and stop the DC motor at the desired angle.

:small_blue_diamond: Servo motors can rotate from 0 to 180 degrees, but they can reach up to 210 degrees depending on the manufacturer. This degree of rotation can be regulated by sending a proper-width electrical pulse to the Control pin. Every 20 milliseconds, the Servo examines the pulse. The Servo may be rotated to 0 degrees with a 1 ms (1 millisecond) pulse, 90 degrees (neutral position) with a 1.5 ms pulse, and 180 degrees with a 2 ms pulse.

:small_blue_diamond: All servo motors connect directly to your +5V supply rails, but we must consider the amount of current they consume. If you plan to utilise more than two servo motors, an appropriate servo shield should be created.


A DC motor and particular gears are used in servo motors, controlled by a variable resistor (potentiometer). The duration of a pulse to a servo motor’s Control PIN, which operates on the PWM (Pulse width modulation) principle, controls the rotation angle. Servo motors can rotate in any direction between 0 and 210 degrees. Sending a proper-width electrical pulse to the Control pin can control the degree of rotation. If you’re going to use more than two servo motors, you’ll need to make a servo shield.

Different Servo Motor Types

:small_blue_diamond: AC and DC servo motors are the two types of servo motors. AC servos are employed in industrial machinery because they can sustain bigger current surges. DC servos are not designed to withstand substantial current surges and are best suited to smaller applications.

:small_blue_diamond: DC motors are generally less expensive than their AC counterparts. These servo motors are also designed specifically for continuous rotation, making it simple to begin your robot going. There are two ball bearings for reduced friction and easy access to the rest-point adjustment potentiometer on the output shaft.


These servo motors are made for continuous rotation, making it simple to get your robot up and running. In general, DC motors are less expensive than their AC equivalents. The output shaft has two ball bearings for reduced friction and easy access to the rest-point adjustment potentiometer.

Applications for Servo Motors

:small_blue_diamond: In radio-controlled aeroplanes, servos are used to control surfaces such as elevators, rudders, walking robots, and controlling grippers. Servo motors are tiny, feature built-in control electronics, and have a high power-to-size ratio.

:small_blue_diamond: The tools are designed for use in more challenging areas, such as food services and pharmaceuticals, where the possibility for corrosion is greater due to being washed at high pressures and temperatures repeatedly to maintain tight hygiene requirements. Servos are also employed in in-line production, where precision work with high repetition is required.

:small_blue_diamond: Of course, you don’t need to understand how a servo works to use one, but like with most electronics, the more you learn, the more opportunities for new projects and possibilities open up. Where will servo motors take you, whether you’re a hobbyist constructing robots, an engineer designing industrial systems, or just curious?


Servo motors are little motors with built-in control circuitry that can be controlled. Servos are used to position control surfaces like elevators and rudders in radio-controlled planes. They’re also used in in-line production, where high-repetition precise work is essential.

Servo Motor Interfacing with Microcontrollers

:small_blue_diamond: Interacting with hobbies It’s pretty simple to use servo motors like the s90 servo motor with a microcontroller. Three wires come out of a servo. Two of them will be utilised for supply (positive and negative) and one for the signal sent from the MCU. An MG995 Metal Gear Servo Motor is extensively used in RC cars, humanoid bots, and other robotic applications.

:small_blue_diamond: Your servo motor’s colour coding may differ, so see the datasheet for your specific model.

:small_blue_diamond: All servo motors connect directly to your +5V supply rails, but we must be cautious of the amount of current they consume. If you want to utilise more than two servo motors, an appropriate servo shield should be created.


Servo motors connect directly to your +5V supply rails, however, the amount of current they consume must be considered. If you wish to use more than two servo motors, you’ll need to build a servo shield. The colour coding on your servo motor may differ, so check the datasheet for your exact type.

Frequently Asked Questions

Following are some frequently asked questions related to servo motors.

1. What is the purpose of a servo motor?

Servo motors, or “servos,” are electronic devices having rotary or linear actuators that precisely rotate and push elements of a machine. Servos are primarily used to control angular or linear position, velocity, and acceleration.

2. How do you distinguish between a motor and a servo motor?

Servo motors, unlike DC motors, do not rotate freely and constantly. Its spin is limited to 1800 revolutions per minute, whereas the DC motor rotates indefinitely. Robotic arms, legs, rudder control systems, and toy automobiles require servo motors. DC motors are utilised in fans, automotive wheels, and other applications.

3. Why is it called a servo motor?

The phrase “servo motor” refers to a specific type of linear or rotary actuator. The phrase servo motor is derived from servomechanism, which denotes that the motor’s motion is constantly monitored and controlled.

4. How do servo motors work?

A servo motor is an electromechanical device that uses current and voltage to produce torque and velocity. A servo motor is part of a closed-loop system that provides torque and velocity as directed by a servo controller and is closed by a feedback device.

5. What is a sewing machine servo motor?

A new Servo motor can breathe fresh life into older sewing machines powered by clutch motors. In contrast to clutch motors that operate continuously, the Workhorse Servo Motor only runs when your foot is on the pedal. Servo motors are therefore more energy-efficient and quieter than clutch motors.

6. What are the advantages of using DC motors like servo motors?

DC motors are simple to control, even though they are significantly less complex than servo motors. Reverse the leads to change directions, and change the voltage to change the speed. These motors are both simple to drive, but the difference in complexity affects the control resolution.

7. Is it possible for a servo motor to rotate 360 degrees?

The length of a pulse determines the servo motor’s location. The Servo’s endpoints might vary, and many only rotate through roughly 170 degrees. ‘Continuous’ servos, which can rotate 360 degrees, are also available.

8. What are the benefits of Servo?

Servo motors are widely utilised in a variety of sectors and offer the following benefits: high efficiency. They have a high output power for their size. At more incredible speeds, there is more consistent torque.

9. Is a servo motor an induction motor?

Electric motors are a type of electromechanical device that converts electrical energy to mechanical energy. In some applications, pure torque is required to drive a mechanism, whereas, in others, the mechanism’s location and rotational speed must be controlled.

10. Does a servo motor require a driver?

The encoder signal (if present) closes the feedback loop with the CPU or driver, and servo motors can be driven with DC or AC electricity. The following diagram depicts the fundamental architecture of a servo motor and its controller/driver. A block diagram shows how to use a motor controller IC to drive a servo motor.


A servo motor is a rotary or linear actuator that can precisely control angular or linear position, velocity, and acceleration. It is made comprised of an appropriate motor and a position feedback sensor. Servomotors are utilised in robotics, CNC machines, and automated manufacturing, among other uses.

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