H∞ fuzzy control design for nonlinear systems subject to actuator saturation

This study introduces a fuzzy control design to deal with the nonlinear H-infinity control problem subject to actuator saturation. For the H-infinity robust control scheme, however, the high gain problem is inevitable. Often, very large control inputs in the transiency are required for the H,,, control scheme. In practice, physical capacity of the actuator is limited and the actuator saturation may severely degrade the performance of the closed-loop systems, lead to a large overshoot, induce a limit cycle and even make the otherwise stable closed-loop system unstable. In the proposed H-infinity fuzzy control design, first, the Takagi and Sugeno (T-S) fuzzy model is employed to approximate a nonlinear dynamic system. Next, based on the fuzzy model, an H-infinity fuzzy controller subject to actuator saturation can be obtained under some linear matrix inequality (LMI) constraints.