航天器
How many spacecrafts are orbiting the moon? 有多少航天器繞月球軌道飛行？
The rotation dynamic and quaternion kinetic equations of spacecrafts were educed according to the principles of variable-structure control. 根據滑動模態(tài)變結構控制原理，導出了航天器三軸動力學和四元數姿態(tài)運動學方程。
