基于迭代学习观测器的航天器姿态主动容错控制

针对含有外部扰动和执行器故障的一类航天器姿态控制系统,本文提出基于迭代学习观测器的主动容错控制方案.首先,建立了含有外部扰动和执行器故障的航天器姿态控制系统的运动学和动力学模型.其次,为了提高观测器的故障估计精度,在传统迭代学习观测器设计基础上引入上一时刻状态估计误差信息,文章提出一种改进型学习估计算法.进一步,基于滑模控制和指定时间稳定理论,利用学习观测器的故障估计信息设计指定时间主动容错控制器.与现有的航天器主动容错控制方案相比,本文所提出的算法的优势在于可以使故障系统的姿态能在指定时间跟踪上指令信号.基于Lyapunov方法,本文从理论上证明了改进型学习观测器和姿态容错控制系统的稳定性.最后,通过数值仿真,说明了所提容错控制方案的有效性和可行性.

Active fault-tolerant attitude control of spacecraft based on iterative learning observer

This article proposes an active fault-tolerant control strategy based on iterative learning observer for a kind of spacecraft subjects to external disturbance and actuator faults. Firstly, the kinematics and dynamics models of spacecraft attitude control system with external disturbances and actuator faults are established. Based on the traditional iterative learning observer design, a improved learning algorithm is designed to accurately estimate the comprehensive fault value of the system by introducing state estimation error information in the previous time. Furthermore, based on the sliding mode control and predefined-time stable theory, an active fault-tolerant controller is designed by using the fault estimation information. Compared with the existing active fault-tolerant control schemes for spacecraft, the advantage of the proposed algorithm is that the attitude of the faulty system can track the command signal at the predefined time. Through Lyapunov method, the stability of attitude control system is proved theoretically. Finally, numerical simulations show the effectiveness and feasibility of the proposed scheme.