Modeling nonlinear behavior in a piezoelectric actuator

A piezoelectric tube actuator is employed as a sample positioning device in Nanocut, a cutting instrument conceived to study the mechanics of nanometric cutting. Extension of functionality of the instrument as a nanometric machine tool motivates the search for an accurate model of the actuator for implementing feedback control. A simple nonlinear model describing longitudinal expansion of the piezoelectric tube actuator is presented in this paper. The model derivation is based on a non-formal analogy with nonlinear viscoelastic materials under uniaxial extension, for which the responses to a step input are similar to the piezoelectric cube. Suitability of the model structure far arbitrary inputs is tested by cross-verification between time and frequency domains. Two parameter estimation procedures an examined and the results of the experimental work for characterization, estimation and validation an presented. (C) 2001 Elsevier Science Inc. All rights reserved.