基于分段趋近律的航天器对地凝视姿态滑模控制

为了提高航天器对地凝视条件下姿态控制精度和鲁棒性,设计了一种基于分段趋近律的姿态滑模控制器。首先,根据航天器轨道参数和目标点地理坐标计算出对地凝视期望姿态。然后,针对当前分段趋近律参数设计不灵活、实际应用存在抖振的缺陷,通过在第二段的幂次趋近律中增添一项线性项,设计了一种全新的分段趋近律。理论证明了该趋近律能有效克服抖振问题;并能在有限时间收敛到滑模面。进而,基于此趋近律设计了一种适用于航天器对地凝视的姿态滑模控制器。仿真实验结果表明,控制器可以获得0.01°的姿态凝视控制精度,在姿态跟踪过程中无抖振现象;并且对外界干扰具有一定的鲁棒性,从而验证了控制器的有效性。

Sliding mode control of spacecraft staring image attitude based on segment reaching law

This brief designs a sliding mode controller based on piecewise reaching law in order to improve the accuracy and robustness of spacecraft staring image attitude control. Firstly, the expected staring image attitude is calculated according to the orbit parameters of spacecraft and the geographic coordinates of target. Then, aiming at the inflexibility of the current segment reaching law parameters and the existence of chattering defects in practical applications, a new segment reaching law is designed by adding a linear term to the power reaching law of the second segment. It proves that the new reaching law can solve the chattering problem in sliding mode control and converge to the sliding mode surface in finite time. Then, an attitude sliding mode controller for spacecraft staring imaging is designed based on the reaching law. The simulation results show that the controller can achieve 0.01 degree of attitude control precision, without chattering phenomenon during the attitude tracking process, and is robust to the external disturbances, which verifies the effectiveness of the controller.