H∞ Fuzzy Control Design for Nonlinear Systems Subject to Actuator Saturation

This study introduces a fuzzy control design to deal with the nonlinear H_infin control problem subject to actuator saturation. For the H_infin robust control scheme, however, the high gain problem is inevitable. Often, very large control inputs in the transiency are required for the H_infin 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_infin 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_infin fuzzy controller subject to actuator saturation can be obtained under some linear matrix inequality (LMI) constraints.