Output-feedback H∞ control of discrete-time switching fuzzy systems

This paper suggests a new H_∞ output-feedback controller for discrete-time switching fuzzy systems, which have high- and low-level weighting functions, namely, crisp switching-region weighting functions and local fuzzy weighting functions. Based on a new piecewise fuzzy weighting-dependent Lyapunov function (PFWLF) consisting of current-time states and a set of one-step-past local fuzzy weighting-dependent Lyapunov matrices, the new controller directly uses the current-time information on the high-level weighting functions as well as the current-time and the one-step-past information on the low-level weighting functions. This resulting controller is formulated in terms of parametric linear matrix inequalities (PLMIs), which are local fuzzy weighting-dependent conditions.