<title>Self-sensing control as applied to a PZT stack actuator used as a micropositioner</title>

Abstract

Recently, more attention has been focused on improving open-loop performance characteristics of smart actuator materials. The impetus in pursuing this course of research is reducing the need for oftentimes costly and obtrusive independent sensors used for feedback to the actuator. Self-sensing actuation is a control technique that can be applied to many smart materials including piezoceramics. It involves extracting a sensing signal from the actuating material by use of a bridge circuit, then properly feeding this signal back to improve the actuator's performance. The research presented in this paper is concerned with the feasibility of applying this technique to a soft PZT stacked actuator used as a micropositioner. The result of applying this control technique was a reduction of the micropositioner's decay time from over 1 ms to under 0.3 ms. A major contributor to the success of this research was the insertion of a nonlinear capacitive element in the self-sensing bridge which negated the nonlinear effects of the PZT stack thus enabling an increase in the self-sensing signal to noise ratio.