Feature: Components for motor control
Modern motion control feedback devices deliver the biggest gains
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By George Yundt, Chief Engineer, Servo Technology at Kollmorgen and Jiří Duroň, Product Line Manager at Kollmorgen Whether you’re specifying a new servo
hen it comes to the world of motion control, it’s easy to take the feedback device
for granted. Aſter all, it’s a small part of the system, typically tucked inside the motor housing out of sight and out of mind. However, the impact this seemingly minor component has on system accuracy, performance, reliability and ease of integration is hard to overstate. Today’s servo systems depend on
accurate, consistent feedback to maintain position and control speed and execute complex motion profiles. But not all feedback devices are created equal. Traditional encoders or resolvers still do the job in many applications, but application requirements increasingly need devices that go beyond the basics. Design engineers also want faster integration and shorter testing time. Modernising your feedback device can mean reducing wiring, simplifying setup, or eliminating long-standing compromises on resolution, accuracy and smoothness of motion.
system or looking to simplify an existing design, it’s worth asking: What do you actually need your feedback device to do, and what is possible?
What are you really looking for? Most engineers don’t start out looking for a feedback device. Tey’re looking for performance, reliability and a system that behaves the way it’s supposed to, every time. Tat means starting with the right questions – not “Which sensing technology is best?” but “What performance does my application need to achieve?” At the most basic level, your feedback
device needs to deliver the resolution and accuracy required to drive the motion loop effectively. Too little, and you’ll see ripples in motion, jitter in position holds, vibration in the machine, or just plain inaccurate positioning. Too much, and you might be paying for more capability than needed. Mechanics connecting to a motor shaſt can only so accurately connect to the part of the machine doing the work which is where the motion really matters. Other considerations quickly come into
36 November 2025
www.electronicsworld.co.uk
focus, such as the motion’s smoothness, the signal’s noise, its bandwidth and so on. Fortunately, these are fairly straightforward questions, and most engineers know how to weigh them up. However, modern feedback devices also bring in another category of features that extend beyond the basic specs and simplify the machine as a whole. Tis is where many of today’s biggest gains are being made. Tey include: Simple cabling: Servo systems used to rely on dedicated feedback cables, sometimes requiring 13 or more wires just for feedback. Tat meant bigger cabinets, more connectors, tighter bends through cable trays, and more hands-on work during installation. Modern single-cable feedback systems
simplify all of that. By taking the motor power cable and just adding two wires for feedback data to fit everything into a single cable, they reduce effort and cut install time. Single cable can make a major difference on compact machines where space is tight, and shrink machine build time. Built-in motor ID: Many modern feedback devices now include onboard memory that stores the motor’s ID, specs and, even,
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