Fixed‐time fuzzy adaptive robust H∞ control for nonstrict‐feedback nonlinear systems with input saturation and output constraints

Abstract

SummaryThis paper focuses on the design of fixed‐time fuzzy adaptive robust control of nonlinear systems in a nonstrict‐feedback form that includes output constraints, input saturation, and external disturbance. Fuzzy systems have been utilized to deal with uncertainties and non‐linearity in the system dynamic model. By introducing novel control and adaptive rules, there is no need to approximate the input saturation function with the hyperbolic tangent function. A Barrier Lyapunov Function (BLF) ensures that systems outputs do not violate the defined constraints. By combining the backstepping and BLF method, asymptotic convergence of tracking error signal to zero in fixed‐time is proved. At the same time, index is also met in dealing with the disturbance effects. Finally, the simulation results of the proposed control method in two examples confirm its effectiveness.