Fuzzy controller design and stability analysis for ship´s lift-feedback-fin stabilizer

A Takagi-Sugeno (T-S) fuzzy model of ship´s lift-feedback-fin stabilizer control systems is established. Based on character analysis of fuzzy control systems with standard fuzzy partition inputs, a new sufficient condition is proved which guarantees the stability of closed-loop T-S fuzzy control systems via Lyapunov direct method. This approach requires only finding a common positive-definite matrix in each maximal overlapped-rule group. The conservatism and difficulty of the former stability analysis methods can be reduced by the new approach. The systematic design method of fuzzy controllers is proposed and applied to the fuzzy controller design of ship´s lift-feed back-fin stabilizers by using the method of parallel distributed compensation (PDC). The simulation results of a ship´s lift- feedback-fin stabilizer control system show that these methods are effective.