Adaptive NFTSM-Based Fault Tolerant Control for a Class of Nonlinear System With Actuator Fault and Saturation

Moshu Qian,Zhong Zheng,Peng Cheng

doi:10.1109/access.2019.2932275

Moshu Qian, Zhong Zheng + Show 1 more

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https://doi.org/10.1109/access.2019.2932275

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Abstract

In this paper, an adaptive fault-tolerant control (FTC) strategy is proposed for a class of nonlinear systems in the presence of actuator fault, actuator saturation, and unknown external disturbance. The mathematical model of a second-order nonlinear system with actuator fault is first given, and a fault estimation observer is designed to estimate the occurred time-varying actuator fault. On this basis, the adaptive FTC strategy is proposed using both nonsingular fast terminal sliding mode (NFTSM) and radial basis function neural networks (RBFNNs) techniques to compensate for the negative effects caused by time-varying actuator fault and external disturbance. Another adaptive FTC scheme is further presented under actuator saturation case, and the Lyapunov stability analysis demonstrates that the designed FTC approach could guarantee that the trajectory of sliding mode dynamics could converge to a small neighborhood of the origin within a finite time. Compared with some existing results, the FTC approach proposed in this paper has better fault acceptability. Finally, the proposed adaptive FTC approach is applied to the attitude control of rigid spacecraft, and the simulation results illustrate the advantages of the designed control scheme.

Highlights

With the rapid development of modern aerospace technology, it has made the increasing demands on reliability and safety of automatic control system [1]
In [6], a fault-tolerant control (FTC) approach is proposed for a rigid spacecraft attitude system in actuator fault and angular velocity constraint case, which guarantees that the attitude angles of spacecraft could track the desired commands
In this study, a fault estimation observer-based adaptive FTC approach is proposed for a class of second order nonlinear system using nonsingular fast terminal sliding mode control technique

Summary

Introduction

With the rapid development of modern aerospace technology, it has made the increasing demands on reliability and safety of automatic control system [1]. An extended state observer is designed in [4] to estimate the synthetic uncertainties caused by actuator fault and model deviation in rigid spacecraft. Attitude system, and the designed FTC approach ensures the stability of the closed loop attitude system by utilizing adaptive robust sliding mode technique. In [5], the active FTC problem is investigated for a class of uncertain nonlinear system using integral sliding mode control technique, and the closed loop system under the designed FTC scheme could tolerate some allowable unknown actuator faults. A novel fuzzy adaptive descriptor observer is designed in [7] to estimate the system state and unknown fault, a nonlinear dynamic output feedback controller is designed to stabilize the faulty nonlinear system with nonlinear dynamic and mismatched disturbance.

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Results

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