Beginner Guide for Servo Motor

Beginner Guide for Servo Motor

When you find automatic machinery or robotics equipment, there is a big chance that among its components, there is a servo motor. The various servo motor has become an important part of today’s machinery, from factory machines, robots and many more. Many types were also created to facilitate those functions, such as low voltage servos, industrial servo motor and many more. Then, we come to a question. Why the servo motor is widely used in different equipment? 

What is the Servo Motor?

To understand the widely used of servo motor, you must understand what servo motor is. In short, the servo motor is an automatic device that can detect the error occurrence and fix it automatically.

The result is the motion produced by using this motor will be much smoother and stable than other motor types. This motor receives that feedback and keeps the motion in the correct direction.

Servo motor can use different energy sources, which are DC and AC. Moreover, it also can be made into brushless DC motor which is perfect for low voltage needs.

However, this motor can’t work alone. It needs other accessories and components to make it work perfectly, such as position sensors and digital encoders. This way the controlling purpose can be easily done and operate.

Servo Motor Important Elements

We can find different types of servo motors. However, mostly, they consist of three main elements, which are motor, control board, and encoder. Every element’s function in this motor connected.

Firstly, the motor will create a movement by using the gears in the motor system. This function will move the encoder and output shaft. This system will move the device that uses a servo motor.

The encoder then will send the motion condition to the control board to see whether it’s correct movement or not. If the control board detects the error in the motion, such as an incorrect angle or torque, it will activate the servo motor.

The servo motor that works based on the feedback from the motion then fixes this condition into the correct setting. Therefore, the motion will be much stable than the motion system without servo motor in it.

How to Choose Servo Motor

Mostly, we choose servo motor based on the voltage it needs to operate or the horsepower it can produce. Low voltage means a better motor and saves more energy. More horsepower means that it can produce more power for the motion. However, that’s not enough. When you choose servo motor, consider the inertia ratio, speed and torque it can produce at a specific speed that you want.

–        Inertia ratio

There are two parts you need to consider here, which is the load inertia and motor inertia. You can easily find the information about motor inertia, as it always printed on the specification sheet of the servo motor. Load inertia; however, need some complicated calculation and comparison between every component in the system where you will use the servo motor. 

To find the best servo motor for your system, make sure you know the ratio between the motor and load inertia. 5:1 is the common ratio on many applications. The lower ratio will give you better performance. So, if you can find the lowest one, that’s the perfect motor for your system. The motor with a higher inertia ratio won’t give you good performance.

–        Speed and torque

You can find more about the speed and torque of the servo motor by looking at the specification sheet from the manufacturer. It comes in a curve. And, in this curve, two areas divide how the servo motor functioned. Those areas are the continuous and intermittent areas.

What you are looking for is the servo motor where your system speed and torque goes in the continuous area curve. It means that the motor can produce speed and torque continuously without overheating the equipment.

However, if it falls into the intermittent area, it can only work in a limited time before its overheating. It needs more control to make it work perfectly.


Servo motor, especially low voltage servos, is an important part of the machinery system. As we explained above, you can make big changes and optimize the system with this motor. So, choose and use them.

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