航天器轨道动力学模型及瞄准提前量误差分析

Orbit-Dynamics Model of Spacecrafts and Error Analysis of Ahead-Point

为提高地面激光瞄准系统对运动目标的瞄准精度,研究了目标的运动特性,并对不同提前量算法的计算精度进行分析。从航天器和天体的运动规律出发,建立一种基于双行根数(TLE)星历表的地平坐标系下的航天器轨道动力学模型,研究了航天器在地平坐标系下斜距、角度、角速度、角加速度的变化规律;根据理论轨道数据,分析了激光瞄准系统的一、二阶瞄准提前量的变化规律;针对实际非时间连续系统,分别用后向差分法和中心差分法对提前量进行误差分析。研究结果表明,目标的角速度、角加速度及急动度等高阶项均对瞄准提前量有直接影响,中心差分提前量算法更具优势。

In order to improve the pointing precision of the laser-pointing system to moving objects, the motion characteristics of moving targets and the calculation precision of different ahead-point algorithms are studied. According to the movement rules of spacecrafts and celestial bodies, the orbit-dynamics model of the spacecraft is built in the horizontal coordinate system based on the two-line-element （TLE） ephemeris, and the change rules of slant-range, angle, angular speed and angular acceleration are studied. According to the theoretical orbital data, the change rules of the lst-order and the 2nd-order ahead-points of the laser-pointing system are analyzed. As for the actual non-time-continuous system, the error analysis of ahead-point with backward-difference method and central- difference method is carried out, respectively. The result shows that the angular speed, the angular acceleration and the jerk and other high-order terms of objects have all direct effects on the ahead-point, and the central-difference method is more advantageous.