A Trajectory Tracking of Piezo-Driven X-Y Table System Using Fuzzy T-S Model-Based Variable Structure Decentralized Control

Based on a preload design and a suitable feedback gain for the piezo-driven x-y table system (PD-XY-TS), the system response was improved. It was called "enhanced piezo-driven x-y table system (EPD-XY-TS)". Each subsystem of the EPD-XY-TS was then approximated by a weighted combination of L linear pulse transfer function systems (LPTFSs). For every nominal LPTFS of the ith subsystem, a dead-beat to its switching surface was first designed. The output disturbance of the mth LPTFS included the interconnections coming from the other subsystems, the approximation error of the ith subsystem, and the interactions resulting from the other LPTFSs. In general, this output disturbance was not small and contains various frequencies. In this situation, the H^infin-norm of the weighted sensitivity function between the mth switching surface and its corresponding output disturbance was minimized. In addition, an appropriate selection of the weighted function could reject the corresponding mode of the output disturbance. Although the effect of the output disturbance is attenuated and partially rejected, a better performance could be improved by a switching control. Finally, the compared experiments of the trajectory tracking of the piezo-driven x-y table were carried out to confirm the practicality of the proposed control