执行器故障的挠性航天器姿态滑模容错控制

Sliding Mode Fault Tolerant Attitude Control for Flexible Spacecraft Under Actuator Fault

针对挠性航天器执行器卡死与失效故障的姿态稳定控制问题,提出一种改进型滑模容错控制策略。与传统的滑模控制相比,该方法能削弱传统滑模控制中抖振现象对姿态控制精度的影响,且它采用自适应技术在线估计系统中的不确定参数,从而保证控制性能对外部干扰、不确定甚至时变转动惯量具有良好的鲁棒性。该控制器并不需要任何在线或离线的故障信息,能够完全独立于地面站的支持。基于Lyapunov方法从理论上证明了该控制器不但能有效地处理执行器故障,而且保证闭环系统的全局一致最终有界稳定,实现对姿态的高精度控制。最后将所提出的方法应用于某型挠性航天器的姿态稳定任务中,仿真结果验证了该方法的有效性。

A modified sliding mode fault tolerant controller is developed for flexible spacecraft attitude stabilization control with consideration of loss of actuator effectiveness fault and actuator stuck fault.In contrast to the traditional sliding mode control,the proposed control law can avoid the chattering effect that may affect the resolution of attitude control.System uncertainties are estimated on-line by using an adaptive technique to guarantee that the proposed controller possess great robustness against external disturbances as well as uncertain and even time-varying inertia parameters.Moreover,the engineering application of the developed control law does not require any on-line or off-line knowledge of the actuator faults or the support of ground stations.The Lyapunov stability analysis shows that the resulting closed-loop attitude system is globally,uniformly and ultimately bounded with high attitude accuracy,and that the possible actuator faults are successfully compensated.Numerical simulation results of an application to a flexible spacecraft are also presented to verify the effectiveness of the control law thus derived.