The Observer-Based Fuzzy H_∞ Controller of Nonlinear Systems

The observer-based H_∞ control problem is investigated for a class of complex nonlinear systems with unavailable states and time delays, and under uncertainties. Takagi-Sugeno (T-S) models are used to approximate the nonlinear systems, and a fuzzy observer is designed to estimate the system states, with which a fuzzy controller is designed to guarantee the stability of the fuzzy system. A compensator based on fuzzy logic systems is introduced to eliminate the approximating error and the uncertainties. Thus, the output-feedback controller is designed to ensure that the closed-loop system is Uniformly ultimately bounded (UUB) and satisfies the desired H_∞ performance. In this method, it is not necessary for the approximating error and uncertainties to satisfy the constraint conditions. A simulation example demonstrates the effectiveness of the proposed control scheme.