对地指向偏差为约束的卫星平稳对日定向方法

传统以对地指向偏差为约束的对日定向方法在星-日、星-地连线的夹角达到极值后，卫星期望姿态会发生大幅度快速翻转，导致较大的峰值功耗和寿命损伤。针对该现象，提出了一种可使期望姿态平稳变化的以对地指向偏差为约束的对日定向方法，将卫星的期望姿态设置为绕一基准姿态周期性地旋转。在不显著牺牲对日定向效能的同时，既确保卫星期望对地轴与对地方向的夹角小于约束角，又使得卫星姿态总体平稳变化。数值仿真表明:所提出的平稳对日定向方法能够大幅降低卫星期望角速度的峰值，同时能够满足对日指向和对地指向的需求。 

A smooth Sun-pointing guidance method for satellites constrained by deviation of Earth-pointing

Under traditional Sun-pointing guidance method constrained by the deviation of Earth-pointing, the expected attitude of the satellite would rapidly flip when the angle between the satellite-Sun line and the satellite-Earth line reaches the extreme value, leading to the large peak power consumption and lifetime damage. Aimed at this problem, this paper provides a novel Sun-pointing method constrained by the deviation of Earth-pointing, which can make the expected attitude change smoothly. By this method, the expected attitude of the satellite is set to rotate periodically around a reference attitude. The deviation of Earth-pointing is kept less than the constraint angle with the attitude moving smoothly, while the effectiveness of Sun-pointing is not evidently reduced. Numerical simulation results show that the proposed method can greatly reduce the peak angular velocity of the satellite, and can meet the requirements of both Sun-pointing and Earth-pointing.