Self-sensing control as applied to a PZT stack actuator used as a micropositioner

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 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 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.