The Application of Quantitative Feedback Theory in Smith Predictor Design

• Main Authors: Su-Chun Hsiao, 蕭夙君
• Other Authors: Chyi Hwang
• Format: Others
• Language: zh-TW
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/58967372207761329048

碩士 === 國立中正大學 === 化學工程研究所 === 89 === Time delay, resulting from material and energy transportation lag, measurement delay, etc.,is a common phenomenon in many chemical processes. Another problems in chemical processes were parametric uncertainties. Many design techniques and conventional control algorithms such as PID cannot be directly applied to processes with dominant time delay and uncertainties. However, the Smith predictor is suitable for regulating systems with dominant time delay. The quantitative feedback theory (QFT) is an excellent design technique of uncertain feedback systems having robust stability and robust performance specifications. The crux of the QFT is a transformation of robust stability and robust performance specifications into domains in the complex plane, referred as bounds, which a nominal loop transmission Lo(s) should lie within. In this thesis, applying a branch-and-bound zero inclusion algorithm to obtain templates and solving the corresponding quadratic inequalities, the QFT bounds of Smith predictor was computed by Pivoting procedure to reduce the amount of calculation.An optimization algorithm is proposed for design optimal Smith predictor, which minimizes the asymptotic loop gain of a system subject QFT constraints. The algorithm is simple and can be used to automate the loop-shaping step of the QFT design procedure.