Displacement control of piezoelectric element by feedback of induced charge

This paper deals with a displacement control method of a piezoelectric actuator (piezo). When voltage is applied to conductive plates which are attached on both ends of a piezo, charges are induced on the conductive plates. This induced charge indicates the deformation of the piezo. Since the relationship between the deformation of the piezo and the induced charge has less hysteresis, the displacement of the piezo can be measured by observing the induced charge. In the case of step response, the displacement of the piezo can be controlled by the feedback of the induced charge as well as by a feedback of the displacement with other measuring instruments. This method can be used at a high driving frequency as the piezo is driven with a voltage source which has a low output impedance.