输入饱和的充液航天器抗干扰有限时间滑模控制

研究三轴稳定充液航天器姿态控制过程中存在外部未知干扰、参数不确定和输入饱和的问题,提出一种抗干扰有限时间滑模控制的姿态机动控制方法.将部分充液贮箱内液体燃料晃动等效为球摆模型,采用动量矩守恒定律推导出充液航天器耦合动力学方程.首先,设计有限时间积分滑模干扰观测器,保证控制系统中集总干扰可以在有限时间内被估计;然后,基于所设计的干扰观测器,提出一种抗干扰有限时间快速终端滑模控制策略,并且证明在该控制律的作用下闭环系统的状态是有限时间稳定的,而且收敛到指定的快速终端滑模面上.此外,通过引入辅助变量补偿控制输入超调量,克服输入饱和的约束.仿真结果验证了该控制策略的有效性和鲁棒性.

Anti-disturbance finite-time sliding mode control for liquid-filled spacecraft with input saturation

In this paper, the problem of attitude control for three-axis stabilized liquid-filled spacecrafts with unknown external disturbance, uncertain parameters and input saturation is studied, and an attitude maneuver control method based on anti-disturbance finite-time sliding mode control is proposed. The sloshing of liquid fuel in a partially liquid-filled tank is equivalent to a spherical pendulum model, and the coupled dynamic equation of a liquid-filled spacecraft is derived by using the conservation law of momentum moment. A finite-time integral sliding mode disturbance observer is designed firstly to ensure that the lumped disturbances in the control system can be estimated in finite time. Then, based on the designed disturbance observer, an anti-disturbance finite-time fast terminal sliding control strategy is presented, and it is proved that the state of the closed-loop system is finite-time stable under the control law, and converges to the specified fast terminal sliding mode surface. Moreover, input saturation constraint is overcome by introducing auxiliary variables to compensate for overshooting. The simulation results show the effectiveness and robustness of the control strategy.