RECENT ADVANCES IN PRECISION POSITIONING SYSTEMS Stefan Vorndran and Scott Jordan, Physik Instrumente LP
Motion drive and control technologies are advancing rapidly, giving engineers access to an expanding spectrum of options to leverage previously unattainable performance and form factors.
R
apidly evolving production processes have driven needs for motion control systems that provide higher accuracy, speed, resolution and repeatability. The motion industry has responded with an expanding palette of technologies including new types of mechanisms, novel position and force feedback technologies, and groundbreaking electromechanical actuation technologies. Together, these are enabling broadly revolutionary new mechanisms and form factors that, in turn, propel fresh ideas for manufacturing. Applications include mission-critical deployments in automation, laser processing, optical inspection, photonics alignment, semiconductor metrology, and medical device and micromachining applications. Today’s broadening spectrum of industrial and research applications has yielded a similarly wide variety of motion technologies — more than a single article can review comprehensively. But it means that designers and motion control engineers in scores of industries have access to precision motorised positioning systems that fit or even enable their applications. These systems provide very few limitations on travel, precision, repeatability and speed.
36 WHAT'S NEW IN PROCESS TECHNOLOGY - AUGUST 2017
Motorised linear actuators A linear actuator is a high-precision positioning device that creates motion in one degree of freedom and typically does not include a guiding system for the payload. For this article we are interested in electrically driven units, though of course micrometer-driven are common, along with screw-driven, pneumatic and hydraulic variants for lower-precision applications.
Piezoelectric actuators These actuators can achieve extremely fine positioning resolution and there are several types.
Piezo stack actuators These are layered structures of specialised ceramic interleaved with metallic electrodes. The piezoceramic has the unique property of expanding in a controllable manner with the application of an electric field. These actuators provide short travel ranges (about 1% of their length), subnanometre precision, high forces and submillisecond response. These are the mainstay of today’s advanced
www.ProcessOnline.com.au