基于运动学和简化动力学的SWARM卫星精密定轨研究

基于运动学和简化动力学方法，使用星载GPS观测数据，对SWARM卫星进行精密定轨，将轨道结果与ESA发布的事后科学轨道进行作差分析。结果表明：运动学轨道径向、切向和法向7 d平均RMS均小于3 cm，定轨精度达到cm级；简化动力学轨道径向平均RMS在0.65 cm左右，切向和法向在1.3 cm左右，高于预期要求。此外，使用IGS快速星历对SWARM卫星进行定轨，其精度与精密定轨精度近似相等，而在SWARM卫星近实时定轨研究中，使用IGS超快速星历确定的运动学轨道3D-RMS为9.68 cm，简化动力学轨道3D-RMS为3.61 cm，低于IGS快速星历的定轨精度。

Precise Orbit Determination Research of SWARM Satellites Based on Kinematic and Reduced-Dynamic Methods

In this paper, based on kinematic method and reduced-dynamic method, using on-board GPS observation data, the precise orbits of SWARM are implemented. The orbit accuracy is assessed using the post-scientific orbit released by ESA. The results show that the seven-day average RMS values of radial, along-track and cross-track directions of kinematic orbits are all less than 3 cm, and the accuracy of orbit determination reaches the centimeter level. The radial RMS of reduced-dynamic orbits is about 0.65 cm and the along-track and cross-track directions are about 1.3 cm, which are better than expected. In addition, the fast orbital precision of SWARM, based on fast ephemeris released by IGS, is approximately equal to that of precise orbit determination. However, in the near real-time orbit determination of SWARM satellite, the 3D-RMS of kinematic orbit determined by ultra-fast ephemeris is 9.68 cm, and the 3D-RMS of reduced-dynamic orbit is 3.61 cm. The accuracy of the orbit is lower than the fast ephemeris results.