基于学习观测器的航天器指定时间跟踪控制

Predefined-time tracking control of spacecraft based on learning observer

针对一类含有外部扰动和执行器故障的刚体航天器姿态控制系统,提出一种基于自适应学习观测器的指定时间容错控制器的设计方案.首先,系统性地给出一种改进型自适应学习观测器设计方案,基于自适应学习观测器框架,设计航天器姿态系统的学习观测器实现对系统的综合扰动值估计;然后,利用综合扰动的估计信息和滑模控制理论设计指定时间容错跟踪控制器,使得系统的姿态角能够在指定时间跟踪指令信号,系统的收敛时间可通过容错控制器的参数预先设置,且与系统的初始状态值无关;接着,基于Lyapunov稳定性理论验证含有故障的姿态控制系统能够在指定时间内稳定;最后,通过数值仿真,与已有的观测器和有限时间控制方案进行对比,表明所提出方案的有效性和可行性.

This paper investigates a predefined-time tracking control strategy based on a learning observer for a kind of spacecraft subjects to external disturbance and actuator faults.First,a general systematic scheme of an improved adaptive learning observer is proposed.Based on the adaptive learning observer framework,a learning observer for spacecraft attitude system is designed to estimate the lumped disturbance in the system.Then,the disturbance estimation information is used to design the predefined-time tracking controller,so that the attitude angle of the system can track the command signal at the predefined time.The convergence time of the system can be preset by the parameters of the fault-tolerant controller and is independent of the initial state value of the system.Through the Lyapunov stability theory analysis,it is concluded that the designed fault-tolerant controller can ensure the predefined-time stability of the system.Finally,through numerical simulation and compared with the existing observer and finite time control schemes,the proposed scheme is proved to be effective and feasible.