33 www.drivesncontrols.com October 2026 PRECISION MOTION n Precision motion: a primer Depending on a user’s requirements, precision can include how consistently, velocity and a multidimensional path can be controlled with minimal deviation. In addition to repeatability (the ability to consistently return to the same position), this includes factors such as minimum incremental motion (often confused with sensor resolution), and accuracy (how closely the actual position matches the intended one). In some applications, following a path based on predefined coordinates and velocity may not be of the highest priority; instead tracking a target precisely based on some external feedback, can be more important. For example, an application may require coupling an optical fibre to a laser diode with 0.02 dB reproducibility. While classical positioning repeatability is important, it is not sufficient to achieve this level of precision. More critical is the performance of the motion controller’s alignment algorithms. The speed at which these algorithms complete the task is also a key consideration. Positioning precision affects process variability. Several factors need to be considered: n the mechanical components (such as bearings, drive screws, material combinations and base plate precision); n the type and presence (or lack of) feedback devices; n the quality and noise levels of the electronics; and n the performance of the motion controller responsible for generating and correcting the motion path. Additional factors that can affect precision and process variability include sensor data accuracy, and other information the system relies on to create or adapt motion. Precision motion control is vital in processes where even minor deviations in accurate, consistent, and dependable motion and positioning performance can cause failure, or poor yield. These include applications such as laser machining and processing, microscopy, photonics, semiconductor manufacturing, aerospace and optics. Obstacles to precision The biggest challenge, of course, is that success in these applications involves more than just precision. Numerous other factors come into play, including the control of ambient and motion-generated vibrations. In general, challenges multiply as precision requirements increase. Mechanical issues, such as friction, backlash, vibration and rumbling noise from bearings, are common. These are best addressed using frictionless air bearings, magnetic bearings, flexures, or frictionless direct-drive motors, such as linear or torque The precision of any motion control system depends on a complex interplay of static and dynamic parameters, including mechanical design, control-loop bandwidths, feedback resolution, thermal stability and environmental influences. Stefan Vorndran, Scott Jordan and Cliff Jolliffe from Physik Instrumente (PI) argue that users need to identify critical performance drivers and ask the right questions early in the design phase. A graphical representation of accuracy and repeatability A motion system using a piezo gripper to align a six-channel fibre array with a silicon integrated electro-optical receiver
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