| Summary: | 碩士 === 國立成功大學 === 機械工程學系碩博士班 === 94 === Magnetic servo levitation(MSL) is currently being investigated as an alternative to drive fast-tool servo systems. Due to the strongly nonlinear system dynamics, system performance is easily affected by parameter uncertainties and external disturbances. This thesis concerns the precision positioning and vibration suppression of an electromagnetically driven duffing nonlinear system using both open-loop command shaping and closed-loop robust control approaches. Command shaping is an effective technique for suppressing motion-induced residual vibration of lightly damped systems. However, due to its open-loop feature, the steady state behavior may not be well controlled due to the influences of external disturbances. An other suppression method is closed-loop control. In the first part of this thesis, a scheme to integrate the command shaping with feedback control is proposed. By command shaping, systems can fast reach their target positions while the feedback control ensures the robustness against environment disturbance. This scheme is verified using an electromagnetically driven fixed-fixed beam. The experimental results indicate that the proposed scheme can effectively reduce the rising time and suppress the residual vibration excited by external disturbance, but the system performance may be influenced by system parameters uncertainties. In the second part of this thesis, we applied three schemes including command shaping, sliding control and a scheme to integrate the command shaping with sliding control on tracking an electromagnetically driven duffing nonlinear system. The sliding controller consists of two parts：the nominal control part that linearizes the nonlinear dynamics, and the robust control part that provides robust performance against the system uncertainties. For the command shaping and sliding control integration scheme, by command shaping, systems can fast reach their target positions while the sliding control ensures the robustness against environment disturbance and system uncertainties. The simulation and experimental results indicates that the proposed scheme can successfully reduce the rising time and suppress the residual vibration excited by system uncertainties and external disturbance. In the future, the proposed method can be applied not only on electromagnetically driven fast-tool servo systems but also on the next generation magnetic bearing suspended wafer scanner for lithography process. Or, by system analogy, it can also be applied to electrostatically actuated MEMS structures.
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