Improvement of scanning accuracy of PZT piezoelectric actuators by feed-forward model-reference control

Abstract

For ultraprecision, three-dimensional surface metrology such as atomic force microscopy, PZT ceramic actuators are popularly used to scan a testpiece in the lateral directions while its vertical dimension is traced by a measuring probe. In this type of scanning microscopy, the measuring accuracy in lateral dimensions is critically limited by hysteresis errors in PZT ceramics when operated by simple open-loop control. We describe a feed-forward control method to effectively reduce scanning errors by using deterministic hysteresis path models. Experimental results prove that this method can enhance scanning accuracy by an order of 10 as compared with conventional open-loop scanning.