Suboptimal Output Feedback Control Design for T-S FuzzySystems with Persistent Bounded Disturbances and ImmeasurablePremise Variables

This paper is concerned with the problem of suboptimal outputfeedback steady-state L -gain control design for nonlinear systemsunder the effects of persistent bounded disturbances. The initialnonlinear system is approximated by a suitable T-S fuzzy model. Itis assumed that the information of premise variables in the T-Sfuzzy model is not accessible through the measurement equations.In contrast to the existing results in the literature, the controller inthis paper does not have an observer-based structure. Moreover, itis not in the form of a Parallel Distributed Compensation (PDC)control laws. In this paper, the T-S fuzzy model is first transformedto an equivalent linear uncertain system. The control problem isthen formulated in the form of a single robust steady-state L -gaincontrol law for the uncertain system. The single controller can beeasily found by a search over the solutions of two Linear MatrixInequalities (LMIs). However, four positive scalars should bedetermined in advance. Hence, a particular numerical method isdeveloped to find the feasible solutions. Moreover, the numericalmethod can be easily extended to find the suboptimal control law.One illustrative example shows the effectiveness of the obtainedresults.

کلیدواژه ها:

L -gain control ، T-S fuzzy systems ، Persistent boundeddisturbances ، Immeasurable premise variables ، Robust control