Fuzzy control of nonlinear stochastic systems with actuator saturation and performance constraints

This paper discusses the problem of actuator saturation constrained fuzzy controller design for the nonlinear stochastic continuous-time systems with external disturbances. By employing the Takagi-Sugeno fuzzy modeling approach, the nonlinear stochastic system is described by several sub-linear systems and corresponding membership functions. The sub-linear systems are represented by linear stochastic differential equations. For solving the proposed fuzzy control problem, the sufficient conditions are derived via Lyapunov theory and Itô´s formula. Moreover, the H_∞ control scheme is used to constrain the effect of external disturbance on the system. According to the derived sufficient conditions, the asymptotical stability and H_∞ performance for nonlinear stochastic continuous-time system are achieved by the designed fuzzy controller. Finally, a numerical example for the nonlinear dynamic ship system is applied to demonstrate the effectiveness and usefulness of the proposed fuzzy controller design method.