带有饱和受限的挠性卫星变结构姿态容错控制

针对挠性卫星在飞行过程中存在推力器故障、控制输入饱和受限以及外部干扰的姿态控制问题,提出了一类基于变结构控制的鲁棒容错控制设计方法.该设计在继承变结构控制的优点的同时,显式地引入推力器输出的饱和幅值,以确保控制输出在其要求界的范围内.同时,充分利用星上推力器的硬件冗余以实现对部分推力器故障的容错,这种思想的引入使得所设计的控制器对故障具有很强的自适应能力,而且对设计者而言,推力器故障信息不需要进行在线的检测和分离.最后,将该控制器应用于某型卫星姿态调节控制,仿真结果表明该控制器能有效地抑制外部干扰、挠性结构的振动和推力器故障的约束,在实现姿态调节的同时,保证其控制输出满足饱和受限界的要求,具有较好的控制性能.

Variable-structure fault-tolerant attitude control for flexible satellite with input saturation

The variable-structure fault-tolerant attitude control system is investigated for an orbiting three-axis stabilized flexible satellite with redundant thrusters. In this system the thruster failures, the control-input saturation and external disturbances are explicitly considered simultaneously. In the proposed controller, a single parameter is dynamically adjusted, independent of the fault detection and mechanism isolation; only the remaining active thrusters are required to be able to produce a sufficient combined force to maintain the satellite in operation for performing the given tasks. By explicitly considering the saturation magnitude of the available control input to the thruster, we develop a direct relation between this magnitude and those of the desired trajectories and disturbances in continuous control. Lyapunov stability analysis shows that the closed-loop system is stable; and the effect of the external disturbances and faults can be reduced by appropriately choosing the design parameters. Numerical examples show that the proposed control algorithms are robust to external disturbances, and are able to handle thruster failures under a limited value of saturation.