输入有界的挠性航天器姿态跟踪滑模控制

Adaptive sliding mode control for attitude tracking of flexible spacecraft with bounded inputs

摘要:

针对三轴稳定挠性航天器输入受限的姿态跟踪问题,设计了一类滑模自适应姿态跟踪控制器,它能确保闭环系统在一定条件下具有全局渐近稳定性,且满足控制输入有界的要求;同时,该控制方案是一种模型独立的控制方法,不依赖于航天器结构参数及模态阶数,而且通过引入参数自适应控制律,使得控制器的设计也不依赖于参数不确定性和外部干扰力矩的界函数,具有较强的鲁棒性和工程实用性.最后根据给定的挠性航天器参数进行了数值仿真研究,结果表明在转动惯量存在较大不确定性和外部干扰的情况下,系统具有很好动态性能和有效地抑制控制输入饱和问题,表明所设计的控制方案有效可行,并具有一定潜在的工程应用前景.

Abstract:

This paper deals with the trajectory tracking for a flexible spacecraft subjected to bounded control input under parameter uncertainties and external disturbances.A simplified adaptive sliding mode control system is designed for the attitude tracking control and vibration suppression of flexible spacecraft,with the degree of sharpness of the control permitted to vary with time according to a set of user-defined parameters.The associated stability proof is constructive and accomplished by the development of a Lyapunov function candidate.It is shown that global stability of the overall system is guaranteed with explicitly accounting for the bounded control input and even in the presence of bounded disturbances and parametric uncertainty.Although control smoothness is preserved at all times,it is important to note that the results of this paper that are derived with respect to bounded control input place no additional restrictions on the body inertias and make no other small-angle assumptions.The closed-loop performance of the new control solution derived here is evaluated extensively through numerical simulations,in which the flexible dynamics is treated as additional disturbance acting on the rigid structure.