Stick-slip actuation of electrostatic stepper micropositioners for data storage-the μwalker

This paper is about the μWalker, an electrostatic stepper motor mainly intended for positioning the data probes with respect to the storage medium in a data storage device. It can deliver forces up to 1.7 mN for ranges as large as 140 μm. Controlling the stick-slip effects at the sliding surfaces is of central importance for reliable operation. A model is introduced to estimate the operating voltage of the actuator plate, which is an essential part of the μWalker. Several methods to obtain displacements smaller than one nominal step (≈ 50 nm) are discussed, as well as how to increase the step repeatability and accuracy.