Fixed‐Time Adaptive Tracking Control for High‐Order Nonlinear Systems With Asymmetric Output Constraints

Abstract

ABSTRACT This article proposes a fixed‐time adaptive tracking control strategy for a class of high‐order non‐strict feedback nonlinear systems with asymmetric output constraints. The key technique of this strategy is to guarantee that the output of the system does not break the pre‐set constraints through the barrier Lyapunov function (BLF) while approximating any unknown nonlinear term through the fuzzy logic systems (FLSs). We design a fixed‐time fuzzy adaptive controller to ensure that the closed‐loop error signal converges to a tunable neighborhood near zero in a fixed‐time instant. Compared with the existing results, the fixed‐time adaptive control is realized and the semi‐global fixed‐time stability of the closed‐loop system is proved theoretically. Finally, the effectiveness of the proposed scheme is verified by a numerical simulation.