Displacement Monitoring of Stacked Piezoelectric Actuator by Observing Induced Charge

This paper deals with condition monitoring of a piezoelectric actuator using induced charge for precision positioning. When conductive plates are attached on each end of the piezoelectric actuator to which voltage is applied, charges induced in plates are proportional to internal charge, which indicates piezoelectric actuator displacement. The induced charge indicates piezoelectric actuator deformation. Because the relationship between deformation and induced charge has low hysteresis, displacement is measured by observing the induced charge, possible at high driving frequency because the piezoelectric actuator is driven with a voltage source with a low output impedance. The induced charge corresponds to the internal charge and displacement in experiments. A static load to the piezoelectric actuator is also detected. © 2008 Fuji Technology Press Ltd.