Brief paper - Optimal output feedback H∞-tracking control design for Takagi and Sugeno fuzzy systems with immeasurable premise variables

This study is concerned with the problem of output feedback H_∞-tracking control design for Takagi and Sugeno (T-S) fuzzy systems with immeasurable premise variables. In most of the existing results in the area of fuzzy H_∞-tracking control design, it is assumed that the information of premise variables is accessible through the measurement equations. This assumption reduces the practical applications of these results. On the other hand, there exist some recent results for control of T-S fuzzy systems with immeasurable premise variables in the literature. By combining this approach with our previous scheme in the area of fuzzy H_∞-tracking control, the authors succeed to design a single controller which leads to the stability of the closed-loop system and guarantees the required H_∞ tracking error norm to some reference and bounded signals. This single controller can be found by a search over the solutions of two linear matrix inequalities. The authors also offer a simple numerical method to find the optimal H_∞-tracking control law. One particular example is given to illustrate the effectiveness of the obtained results.