Observer-Based Output Feedback Control for Discrete-Time T-S Fuzzy Systems With Partly Immeasurable Premise Variables

This paper is concerned with the observer-based output feedback control problem for Takagi and Sugeno fuzzy systems with partly immeasurable premise variables. By using measurable premise variables and estimations of immeasurable premise variables of fuzzy models as the premise variables of fuzzy controllers, a new fuzzy control scheme is proposed. Further by constructing a set-theoretic description of fuzzy systems, the equivalence class theory in set theory is applied for designing fuzzy controllers, then the partly measurable premise variables are effectively used in the proposed conditions. In the existing fuzzy control schemes, the fuzzy weight functions are unaccessible on line due to the partly immeasurable premise variables, so that the partly measurable premise variables cannot be directly used, which might introduce some conservatism. Different from the existing results, the new condition can make better use of measurable premise variables via the proposed control scheme. A numerical example is given to illustrate the effectiveness of the proposed method.