Research On Fault Accommodation For Spacecraft Attitude Systems With Actuator Faults

With the continuous development of science and technology,modern spacecraft presents a trend of increasingly complex structures and gradually improved functions,so that modern spacecraft can realize increasingly complex spatial tasks.At the same time,due to the harsh working environment of the spacecraft,the mechanical and electrical components of the spacecraft are prone to aging,making the actuator prone to failure.Therefore,it is of great research and application value to ensure that the attitude of the spacecraft can remain stable in the presence of actuator failure.This paper intends to conduct an in-depth study on the fault regulation technology of modern spacecraft actuator failure,aiming to find a new method for autonomous fault-tolerant control when the spacecraft actuator failure occurs.The main contributions of this paper are as follows:(1)The spacecraft's actuators are first divided into two groups: the fault group and the health group,and it is assumed that only the actuators in the fault group can fail.Based on the prior art,the torque generated by the actuator in the fault group is estimated and compensated in the design process of the fault-tolerant control law.The fault-tolerant controller is designed for the actuator in the health group to ensure the closed-loop attitude system of the spacecraft.All state variables can eventually converge to the neighborhood near the origin.Finally,the simulation is carried out using Matlab software to prove the effectiveness of the method.(2)Design a fault estimation algorithm based on adaptive technology to accurately estimate the time-varying actuator LOS fault and the bias fault simultaneously.Combining non-singular fast terminal sliding mode technology with fault estimation observer to design FTC law,such that the spacecraft attitude control system still has good dynamic performance even in the presence of actuator fault,actuator saturation and external disturbance.Finally,numerical simulation is carried out,and the superiority of the designed scheme is shown by simulation comparison.(3)Based on sliding mode control and adaptive control technology,a fault diagnosis scheme is designed,including a fault detection observer and a fault estimation observer to detect the time when the fault occurs and obtain the amplitude of the actuator fault after the fault occurs.Using the non-singular fast terminal sliding mode technology and the actuator fault information obtained from the observer to design the active FTC method to compensate the negative effects caused by the actuator fault,and the necessary simulation verification and comparison results are given.