Servo Motor vs Stepper Motor - Which One is Better or Worse?

 

Figure 1 drylin® E Electric Motor

Selecting the right electric motor is important to get the most efficient and effective motion control. However there are some major differences between the two most commonly used motor: stepper motor and servo motor that needs to be addressed to before you choose one for your application. Below are the main differences between stepper and servo motors, shared by our low-cost automation expert.

What is a Stepper Motor?

A stepper motor, as the name suggest, moves in forms of step. It is a type of electric motor that divides a full rotation into a number of equal steps. You can refer to the picture below. Imagine yourself looking at the shaft, and the rotation in a 360o. A common stepper motor step is 1.8o, to move a full revolution, you need to take 200 steps. Each step is controlled by a pulse from a driver, and depending on the capability of the driver, the steps can also be further broken down into finer steps, which are called microstep. This enhances the movement of the motor to have a smoother rotation and an even more precise movement.

Figure 2 Step in Stepper Motor Overview

What is a Servo Motor?

A general definition of servo motor is any motor that works in a close loop system. Meaning there will be a feedback system in place to ensure that the movement of the motor is always in check, hence, enabling the controller to react as soon as something amiss were to happen during its operation. Because of this , there can be many different types of motors that can be considered a servo motor, as long as it works in a close loop system, hence, giving the servo motor many possibilities.

Difference between them?

If budget maybe a concern and you requires some form of accuracy in your system, a stepper motor might be something cheap without running a close loop system to get some form of accuracy. The problem with stepper motors (especially if it’s not run in close loop), is some chances of experiencing missteps, meaning, your accuracy will be compromised.

In a servo system, there is always constant feedback, hence if something like a misstep were to happen, the close loop system will detect this and the controller will compensate this and correct the mistake. Servo motor is also more efficient than stepper motor although it comes at a higher cost.

igus® is the manufacturer of drylin® E electric motor used for automation and robotic industry. Click here to learn more about drylin E electric motor (stepper motor, servo drive, etc).