| Summary: | 碩士 === 大同大學 === 化學工程研究所 === 91 === Chemical processes are often complex nonlinear system and there are limited available instrumentations to measure all the state variables on-line. When these state variables are to be monitored, controlled or optimized on-line, a nonlinear state observer is required to estimate these immeasurable variables. An observer with acceptable performance shall be designed to ensure a fast decay of the tracking error. In this research, some existing observers were discussed and compared to develop an observer with robust performance in application.
In this study, we found that implementation of the nonlinear state-observer designed by Chen (2001), the convergence of the error dynamics of observer cannot be guaranteed. Therefore, in this research, implementation of nonlinear state-observer designed by Chen (2001) was revised by choosing constant gains policy to achieve the convergence of the error dynamics if the corresponding poles of characteristic equations were maintained in the left half of the complex plane during the estimation. In the meantime, the variable gains policy was adopted to maintain the latest poles located in the left half of the complex plane. The robustness and performance of the designed nonlinear state observer can be obtained. Applications of the developed observer to a series-parallel reaction in a batch reactor for estimating the states were achieved successfully under various situations.
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