| Summary: | 碩士 === 國立交通大學 === 機械工程系所 === 98 === Significantly the dead-time has a great influence on the stability of systems, which make the process more difficult to control. Therefore, this thesis presents a discrete dead-time compensator to improve the performance and capability of disturbance rejection for dead-time systems. It applied predictive DOB and Smith predictor structure to compensate output delay and input disturbance for stable and integrating plants. The proposed structure consists of two parts: the inner loop and the outer loop. Firstly the PDOB can be designed to reject any kind of deterministic disturbances, including step disturbance, ramp disturbance and sine disturbance. Also, the property of DOB structure can approach the real plant to the nominal plant. The PDOB based on DOB structure has an additional predictive filter, which eliminate the time delay of estimated disturbance. Because of the property enhances disturbance rejection performance of traditional DOB for dead-time systems especially for periodic disturbance. Secondly, the Smith predictor structure is capable to suppress the effects of time delay. Seeing that the stability is influenced by the model mismatch and model mismatch will always exist in the process. In this thesis, we propose a robust controller which compensates the effect of time delay and reject deterministic disturbance to satisfy the robust stability.
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