基于拟欧拉角描述的上面级姿态控制律设计

上面级在多星部署过程中将涉及大角度姿态机动问题,卫星释放所引起的质心横移将给上面级姿态控制带来困难。根据系统质心的横移情况,在上面级体坐标系中确定矢量喷管的平衡位置,进而确定出矢量喷管指向指令方向时的上面级姿态。调制姿态四元数可以得到描述上面级姿态偏差的拟欧拉角及相应的拟欧拉角速度,在拟欧拉角描述的上面级姿态运动模型的基础上,选择合适的滑模面,构造变结构控制律。仿真结果表明,该控制律可对上面级姿态进行控制,进而实现对矢量喷管指向的间接控制,喷管摆角的限幅不会影响姿态控制的过程。

The Attitude Control Law Design Based on Qausi-Euler-Angle Scheme in the Upper Stage

The large-angle maneuver problem is concerned in the process of multi-satellite deployment.The centroid offset during the deployment can bring difficulties to the control law design.With the corresponding knowledge of the offset of the center of mass,the equilibrium position of the vectoring nozzle can be determined and the corresponding attitude of the upper stage with the nozzle points along the command direction can be determined as well.The quasi Euler angle vector and quasi Euler angular velocity vector are yielded by modulating attitude quaternion,which describe the difference and the rate of the current and the desired attitudes.Based on the quasi-Euler-angles-based attitude motion model in upper stage,when a proper sliding mode surface is specified,a variable structure control scheme is proposed.The simulation results show that the attitude of the upper stage and further the pointing of the vectoring nozzle can be perfectly controlled by using the proposed control scheme.In addition,the attitude control process can not be significantly influenced under the definition of the bounds of the deflected angles.