Performance comparison and modeling of PZN, PMN, and PZT stacked actuators in a levered flexure mechanism

This article presents a theoretical and experimental assessment of a translation stage design based on a piezoelectric actuator and levering mechanism. This mechanism incorporates stacked piezoelectric actuators of dimensions 5×5×5 mm3 with each stack made from ten plates of 0.5 mm thickness pushing against a symmetric lever design with an ideal amplification of 6.05:1. Three different stacks made from PZN, PMN, and PZT were tested in a nominally similar mechanism to produce displacements of 101, 104, and 33 μm, respectively. Because of their different elastic moduli, the fundamental resonances with each respective device were 670, 729, and 759 Hz. Lagrange analysis of a lumped model of the mechanism is used to estimate the fundamental mode natural frequency of the system while a model for “lost motion” is also presented. This system has been assembled and evaluated experimentally to assess the validity of the models. In general, these models are shown to provide a reasonable estimate of the mechanism performance in terms of lost motion while predicting higher values for the fundamental frequency. The deviations from the model are consistent with the uncertainties associated with rigid body assumptions and the unknown compliances of assembly interfaces and suggest directions for future research in the modeling of such systems.