基于约束运动理论的航天员舱外救生中的姿态运动控制

An Attitude Control Method Based on Constrained Motion Theory for Extravehicular Activity Rescue by Astronaut

航天员舱外救生或作业时相对母体航天器经常要进行大角度姿态机动或姿态保持,利用欧拉四元数描述姿态无奇异性且冗余度小。然而航天员舱外调姿时通常含有一定的约束或是沿着某种预定轨迹,而且欧拉四元数在计算过程中可能发散。基于Udwadia和Kalaba提出的约束运动理论,分析了航天员和航天器的相对姿态的描述方法,直接用四元数对航天员的姿态进行动力学建模,将四元数2范数为1的约束加入到动力学方程里。利用该约束运动理论推导和仿真了航天员姿态欧拉角奇异时的姿态跟踪控制方法。该控制方法对航天员肢体变化引起的转动惯量等参数的改变具有鲁棒性,能通过平衡解稳定参数的选取方便地对控制系统的性能进行调节,且计算量小。

Attitude maneuvering is essential for the astronaut during extravehicular rescue or operation. However the extrave- hicular astronaut is often limited by some constraint or trajectory requirement. The Udwadia and Kalaba＇ s constrained motion theo ry was used to model the attitude motion mentioned above. The relative attitude relation between the astronaut and the spacecraft was developed via quateruion operation. An explicit tracking control method was introduced to design the attitude control systems of extravehicular rescue aid equipment. From the simulation, conclusion can be made that this explicit control method is robust to parameters uncertainty of the system such as the moment of inertial variance due to astronaut＇ s limb disturbance, as well as that its simplicity implies its capability for real-time control.