Improved Piezoelectric Self-sensing Actuation

Self-sensing actuation allows a single piezoelectric (PZT) element to be simultaneously used as both a sensor and an actuator. A specially designed electric circuit, referred to as a bridge circuit, is required to realize the concept. However, precise equilibrium of the bridge circuit is extremely difficult to obtain because of the continuous changes in environmental conditions. In this study, the effects of an unbalanced bridge circuit are analytically and experimentally evaluated in an attempt to quantify the variations in the PZT capacitance in terms of performances in vibration testing and control. Once the dynamic characteristics of self-sensing actuation are identified and understood, methods for improving the system’s performance are developed by utilizing capacitors in series and in parallel with the PZT patch. The analytical and experimental results clearly indicate that the new design scheme increases the stability of the system. However, the increase in stability comes at the cost of the increase in the power required for the control system.