Feature

A motor guide for precision engineering

When to use a servo motor and the advantages of an accurate precision closed-loop stepper motor are explored by Paul Jepson, New Business Analyst, Oriental Motor (UK).

04/01/2022 16:18:03

Font size:

Traditional servo motors have been a key technology in automation for a long time now. They have been the go-to option if an application requires high speeds and high torque, and/or positional accuracy. There is, however, a more recent introduction: a closed-loop
stepper motor. This has all the performance benefits of a servo system, but with the added advantage of incredible positional accuracy, without the need for a proportional-integral-derivative (PID) loop in the driver of the motor to monitor its position.

Traditional servo motors are based
on brushless DC (BLDC) technology. There are usually 10 to 16 poles on the motor’s rotor, so each pole covers several degrees of rotation (i.e., 36 degrees per pole for 10-pole motors and 22.5 degrees per pole for 16-pole models).

If an accurate
position, or set point, is required, the position is controlled by a PID loop, which constantly checks the position that the servo motor is in, compares it to the command position, and manipulates the motor position to stay as close to the command position
as possible. It has been likened to a circus performer standing on a giant ball; the performer’s head and torso may look stationary but their feet are constantly moving to make little corrections to keep him or her steady.

Read the full article in DPA's January issue

Written By Sophia Bell

Sophia Bell is the Group Editor of DPA, Connectivity, and PBSI. She joined the team in 2020 as Assistant Editor after achieving a First-Class Honours BA in English Literature and Film Studies from the University of East Anglia. In her current role, she leads the editorial strategy, driving digital growth and ensuring each title continues to deliver trusted, relevant insight for engineering and manufacturing professionals.