Adaptive Fault-Tolerant Control of High-Order Nonlinear Delay Systems Under Unknown Dead-Zone Fault and Unknown Control Coefficients and Its Application

Abstract

This work addresses the fault-tolerant control (FTC) problem of the high-order nonlinear systems (HONSs). The HONSs under study are jointly affected by the unknown time delays, unknown asymmetric dead-zone fault, and unknown control coefficients. Based on the designed Lyapunov-Krasovskii functional (LKF), the unknown time-delay nonlinear terms of the system are effectively compensated. Through the introduction of suitable Nussbaum gain function (NGF), the issue stemming from unknown control coefficients is solved. Meanwhile, the approximation problem of unknown nonlinear dynamics is effectively tackled based on the application of radial basis function neural network (RBFNN). Furthermore, a NN-based adaptive fault-tolerant tracking control scheme is developed and adaptive control laws for some unknown parameters are formulated. The key feature of this control scheme is to ensure that the tracking error asymptotically converges to a small neighborhood of zero, while keeping all signals of the closed-loop system are semi-globally uniformly and ultimately bounded (SGUUB). Ultimately, the validity of the controller proposed in this work is testified through given examples.