Adaptive self-sensing control of flexible structures by using a piezoelectric actuator

A self-sensing actuator is known to be effective for the vibration control of flexible structures. Currently, a self-sensing piezoelectric actuator is implemented by using a tuned bridge circuit. This circuit easily becomes unbalanced because of the variation in the piezoelectric capacitance, which is sensitive to ambient temperature. If the bridge circuit is unbalanced, the closed-loop system becomes unstable. In this paper, two different methods are proposed for realizing an adaptive self-sensing control. The first method uses an observer to estimate the unknown capacitance value and implement the direct velocity feedback control. The second method uses a bridge circuit and a band pass filter to estimate the capacitance directly. The results of numerical simulations illustrate that the both methods proposed in this paper are very effective for the piezoelectric capacitance estimation and closed-loop system stabilization.