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Analysis and Synthesis of feedback system with saturation: an LPV-based approach.

A number of physical systems are subject to input saturation. The saturation nonlinearity of control input often leads to significant deterioration of control performance or instability of the closed-loop system if the nonlinearity is not taken into account at the controller design stage; this phenomenon is called windup. Hence, it is very important to develop analysis and controller synthesis methods explicitly taking account of the nonlinear structure. A typical approach to the analysis and synthesis of saturating control system is to employ the robust stability theory such as the small-gain, circle and Popov criteria. However, this approach often leads to a conservative result since it neglects the detailed structure of the nonlinearity by regarding it as sector-bounded uncertainty. In this talk, we will present a novel approach to this kind of problem based on the linear parameter-varying (LPV) system representation. The LPV technique expresses a nonlinear system as a linear system whose coefficients depend on a certain time-varying parameter called a scheduling parameter. Since the LPV system representation allows us to make use of information on the nonlinearity through the scheduling parameter, we can obtain less conservative results than the previous robustness-based approach.
Type of Seminar:
Public Seminar
Prof. Kiyotsugu Takaba
Department of Applied Mathematics and Physics Graduate School of Informatics, Kyoto University-Japan (visiting Mathematics Institute, University of Groningen,NL, until Feb. 2001).
Nov 28, 2000   17:00

ETL K 25, Physikstrasse 3, 8006 Zurich
Contact Person:

Prof. Toru Kawabe
No downloadable files available.
Biographical Sketch:
Kiyotsugu Takaba received B.Eng. degree in applied mathematics and physics, M.Eng. degree in applied systems science and Dr.Eng. degree in applied mathematics all from Kyoto University in 1989, 1991 and 1996, respectively. Since 1991, he has been with the Department of Applied Mathematics and Physics in Kyoto University, where he is presently an Associate Professor. Since April 2000, he has been visiting the Mathematics Institute, University of Groningen in the Netherlands. His research interest includes robust and optimal control of implicit sytems, feedback systems with saturation, and the behavior-based system theory.