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 condu ctive plates. This induced charge indicates the deformation of the pie zo. Since the relationship between the deformation of the piezo and th e induced charge has less hysteresis, the displacement of the piezo ca n be measured by observing the induced charge. In the case of step res ponse, the displacement of the piezo can be controlled by the feedback of the induced charge as well as by a feedback of the displacement wi th other measuring instruments. This method can be used at a high driv ing frequency as the piezo is driven with a voltage source which has a low output impedance.