Motion Control of Piezoelectric Tripod Platform via Feedforward Hysteresis Compensation

Abstract

In this study, a precise motion control strategy for a piezoelectric tripod manipulator integrated with compliant mechanisms based on feedforward hysteresis compensation and feedback control is reported. The piezoelectric tripod platform is designed with three piezoelectric legs to produce large transverse stroke and angular motions with three degrees‐of‐freedom (3‐DOF). The piezoelectric actuation legs, which are made with four piezoelectric stack actuators and reverse‐type compliant mechanisms, have highly nonlinear inherent hysteresis, resulting in critical difficulties of accurate motion control. To properly compensate inherent hysteresis of the present 3‐DOF tripod manipulator stemming from interaction between piezoelectric stack actuators and compliant amplification mechanisms, a feedforward hysteresis control is successfully implemented with a third‐order rate‐dependent polynomial fit. Present results reveal that the feedforward compensator based on the rate‐dependent hysteresis model and feedback control integrated with rate‐independent compensator can be successfully applied to the motion control of the piezoelectric 3‐DOF tripod manipulator with severe inherent hysteresis.