A Nonlinear Charge Controller With Tunable Precision for Highly Linear Operation of Piezoelectric Stack Actuators

Piezoelectric stack actuators, which have been widely used in precise positioning applications, suffer from the well-known hysteresis effect. Although numerous approaches such as sensor-based control and feedforward control have been proved to be effective, the resulting high cost and system complexity limit their use in industry. In this paper, the design and validation of a nonlinear charge controller (NCC) is presented for achieving highly linear operation of the actuator in a sensorless way, without modeling hysteretic nonlinearity. In the proposed scheme, the output voltage of traditional linear charge controller (LCC), which contains information of hysteresis, has been processed and utilized as feedback signals. As a result, controller outputs with tunable nonlinearity have been achieved, aiming to improve the observed overcompensation effect. Experimental results show that the dynamic tracking performance of the NCC is superior to LCC approach. The positioning error has been reduced to 0.4% of the travel range, corresponding to a nonlinearity reduction of 97%.