| Summary: | 碩士 === 逢甲大學 === 自動控制工程所 === 90 === This thesis is intended to investigate the tracking control of a nano-positioner driving by a piezo-actuator. The performance of a PI controller in tracking control is not satisfied because it presents large phase error in tracking high frequency signals. In this thesis, two tracking controller design methodologies are proposed to improve the performance of the PI controller. Firstly, the hysteresis compensation method for Zero Phase Error Tracking Controller is studied, and, then the CMAC tracking control is investigated. The ZPETC can achieve zero phase error performance in the tracking of linear control system, however, the performance is degraded by the hysteresis effect of the piezoelectric actuator. For this reason, this article will adapt the delay compensation way黃嘉全 to improve the problem of phase error caused from the delay by reducing the influence of delay effect and enabling the system more similar to linear system.
The CMAC control structure has been widely used in the tracking control of robot arms, and successfully applied to a nano-positioner as well. In many reference articles, the advantages of CMAC controller are presented, while the potential risks of using CMAC controller are rarely mentioned. This study focuses on the practical implementation of the CMAC control of a nano-positioner. It was found, for some controller parameter settings, the tracking error was reducing in the beginning, whereas the system became unstable eventually. Also, the nano-positioner was subjected to sporadic jitter caused by the discontinuous output of the CMAC controller, this result was not shown in the previous literatures. The problem can be avoided by using a higher-order CMAC controller, which has smooth output.
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