Fixed‐Time Adaptive Tracking Event‐Based Control for Uncertain Stochastic Nonlinear Systems With Output Constraints

ABSTRACT This paper focuses on an adaptive fixed‐time tracking control problem for nonstrict‐feedback stochastic nonlinear systems with unknown control coefficients and output constraints. To overcome this problem, this article introduces a unified system transformation function to facilitate the transition of the system from constrained to unconstrained states. Subsequently, a fuzzy approximation principle is utilized for handling unknown terms in the transformed system, while Nussbaum functions are employed to manage unknown control directions. Then, combined with the backstepping technique, an adaptive fixed‐time tracking controller is designed with an event‐triggered mechanism, which not only achieves the convergence of tracking errors within a limited time independent of initial states, but also conserves resources. Under the proposed tracking controller, practical fixed‐time stability can be ensured for the closed‐loop system. Finally, two simulation examples demonstrate the efficacy of the proposed scheme.