Robust Position Control of Linear Piezoelectric Motor Drive Systems

The friction and load variation are the main uncertainties in the linear piezoelectric motor system. Only the viscous friction is considered in previous work, but it is quite different with the practical condition. Highly nonlinear friction in the system is measured and compensated by a radial basis function (RBF) network. A discrete-time sliding mode controller, which is insensitive to the perturbed state matrix and input matrix and disturbances, is proposed for LPM drive system. Furthermore, three free design parameters are optimized to achieve better transient performance by genetic algorithm and one online mass estimator is adopted to extend the robustness. The simulation and experiment results show that the proposed controller has a stronger robustness than PID controller.