Positioning of piezo-driven xy table systems using fuzzy mixed H/sup 2//H/sup /spl infin// optimization-based decentralized model reference control

In this paper, the positioning of a piezo-driven xy table system via a fuzzy mixed H/sup 2//H/sup /spl infin// optimization-based decentralized model reference control is developed. Each subsystem contained 6 linear pulse transfer function systems (LPTFSs). The reference model for every LPTFS was first designed to shape the response of the closed-loop of the ith subsystem. Then the H/sup 2/ - norm of the output error and weighted control input of the jth LPTFS was minimized to obtain a control. The H/sup /spl infin// - norm of weighted sensitivity between output disturbance and output error of the jth LPTFS was minimized to attenuate its effect. In addition, a nonlinear control based on output error for every LPTFS was also established to improve robust performance. The experiments of piezo-driven xy table system confirmed the usefulness of the proposed control.