面向精密位置服务的低轨卫星轨道预报精度分析

Accuracy analysis of LEO satellites orbit prediction for precise position service

LEO卫星精密轨道预报是LEO导航增强系统中重要的技术环节之一,本文使用多种算法来实现不同任务需求下的轨道预报。对于在地面处理系统实现的LEO轨道预报,算法1采用定轨预报同时处理的策略,算法2将离散轨道点进行动力学拟合再进行积分外推。GRACE-C卫星预报5、10、15 min的URE平均精度分别为5.25、5.67、6.25 cm;HY2A卫星为7.83、8.69、9.66 cm;SWARM-A卫星为8.88、9.22、9.63 cm;SWARM-B卫星为8.49、8.98、9.63 cm。对于计算条件受限的LEO星上轨道预报,本文利用单个轨道点及简单动力学模型进行轨道积分外推的算法。该算法主要考虑地球中心引力及非球形引力摄动,因此地球重力场阶次对轨道预报精度产生较大影响。平均高度为500 km的LEO卫星选取60阶重力场,高度为1000 km的LEO卫星选取30阶重力场,可实现预报10 min轨道优于10 cm的预报精度。

Precise orbit prediction of low earth orbit(LEO)satellites is one of the important technologies for LEO navigation enhancement system.In this paper,we use a variety of algorithms to realize orbit prediction under different mission requirements.For LEO orbit prediction on ground,algorithm 1 processes orbit determination and prediction simultaneously.In algorithm 2,the discrete orbit points are fitted dynamically and then orbit integral is extrapolated.The average predicted user range error(URE)accuracy of GRACE-C satellite in 5,10 and 15 minutes is 5.25,5.67,6.25 cm,that of HY2A satellite is 7.83,8.69,9.66 cm,that of SWARM-A satellite is 8.88,9.22,9.63 cm,and that of SWARM-B satellite is 8.49,8.98,9.63 cm.For LEO orbit prediction on board with limited calculation conditions,an orbit integral extrapolation algorithm with a single orbit point and simple dynamic models is used.Because this method mainly considers the perturbation of the Earth's central gravity and non-spherical gravity,the order of the Earth's gravity field has a significant impact on the accuracy of orbit prediction.60 order gravity field is selected for LEO satellite with an average height of 500 km and 30 order gravity field is selected for LEO satellite with an average height of 1000 km,which can realize the prediction accuracy of about 10 cm for 10 min arc length.