Nonsingular fixed‐time adaptive neural terminal sliding mode control for a class of uncertain second‐order nonlinear systems

Abstract

In this article, the fixed‐time adaptive neural tracking control for a class of second‐order uncertain nonlinear systems is investigated. First, a novel fast fixed‐time stable (FTS) autonomous system with the switched nonlinear term is constructed. Compared with the traditional FTS system (FTSS), the state of the proposed fast FTS system has a faster convergence rate for arbitrary initial state. Then, a fixed‐time terminal sliding mode control (FTSMC) scheme is developed based on the novel fast FTSS, and the tracking error of the closed‐loop system is verified to converge to the origin within a fixed time. The proposed FTSMC scheme not only realizes the upper bound of the settling time independent of the initial conditions but also completely avoids the singularity problem by introducing the switching sliding mode surface. Moreover, an adaptive neural FTSMC scheme is developed for the general uncertain nonlinear systems with the help of the approximation capabilities of neural networks (NNs). The feasibility of the presented control strategy is examined by the simulation of a single‐link robot system.