杨元喜, 任夏. 自主卫星导航的空间基准维持[J]. 武汉大学学报 ( 信息科学版), 2018, 43(12): 1780-1787. DOI: 10.13203/j.whugis20180169
引用本文: 杨元喜, 任夏. 自主卫星导航的空间基准维持[J]. 武汉大学学报 ( 信息科学版), 2018, 43(12): 1780-1787. DOI: 10.13203/j.whugis20180169
YANG Yuanxi, REN Xia. Maintenance of Space Datum for Autonomous Satellite Navigation[J]. Geomatics and Information Science of Wuhan University, 2018, 43(12): 1780-1787. DOI: 10.13203/j.whugis20180169
Citation: YANG Yuanxi, REN Xia. Maintenance of Space Datum for Autonomous Satellite Navigation[J]. Geomatics and Information Science of Wuhan University, 2018, 43(12): 1780-1787. DOI: 10.13203/j.whugis20180169

自主卫星导航的空间基准维持

Maintenance of Space Datum for Autonomous Satellite Navigation

  • 摘要: 基于星间测距的自主定轨必然存在星座的整体旋转和漂移,即存在星座空间基准的衰减问题,因此,卫星星座的空间基准维持是自主定轨的主要目标,也是自主定轨的核心问题之一。重点讨论卫星自主定轨中的空间基准维持方法,系统分析星地观测、星间/星地组合观测和星间观测3种观测模式下的卫星轨道参数估计方法,及其对应的空间基准维持方式;提出卫星自主定轨强基准和弱基准概念。强基准是指在星地观测或星间/星地组合观测条件下,强化地面高精度基准站坐标的定轨方式,此时卫星星座基准与地面跟踪站基准一致;弱基准是指在仅有星间链路观测条件下,采用卫星轨道信息先验弱约束的定轨方式,即弱基准是以先验轨道所对应的卫星星座的几何重心建立的。强基准充分利用了星间、星地观测网中的各类信息,计算结果可靠且精度稳定,而弱基准虽然缺少地面观测信息,但先验卫星轨道同样是基于地面跟踪网精密定轨得到的,对卫星空间基准的维持同样可靠,且定轨计算更为简单。采用北斗试验星实测数据,分别开展无基准、弱基准和强基准支持下的自主定轨试验,试验结果表明,弱基准中仅对卫星轨道倾角和升交点赤经进行先验弱约束即可抵偿卫星星座的旋转和漂移,但定轨精度略低于强基准支持下的定轨精度。在无地面跟踪系统支持的特定环境下,建议采用弱基准方法,实现真正意义上的自主定轨。

     

    Abstract: Autonomous orbit determination (AOD) based on inter-satellite link (ISL) measurements may lead to the dilution of constellation datum performing constellation rotation and drift. Thus, the maintenance of constellation space datum is the main purpose and one of the core problems of AOD. This paper mainly discusses the maintenance of coordinate system for satellite AOD, and systematically analyzes the estimation method of satellite orbit parameters and the maintenance of the datum under different observation modes using ground-satellite link (GSL) measurements, combined measurements (GSL and ISL measurements), and ISL measurements, respectively. The concepts of "strong datum" and "weak datum" are proposed. The "strong datum" means that the datum of satellite constellation provided by AOD method aligns to the datum of the exis-ting datum of ground stations with good precision using GSLs or combined measurements (ISLs and GSLs). The "weak datum" means that the ISL-only measurements are employed in AOD method but the parameter estimation is constrained with a priori orbit information, and the satellite constellation datum is consistent to the geometric gravity center of the constellation corresponding to satellite a priori orbits. The "strong datum" uses all kinds of observations in inter-satellite and ground-satellite observation networks. The result is stable and reliable. The "weak datum" maintains space datum reliably without ground-based observations, but with a priori satellite orbits which is achieved through precise orbit determination based on ground tracking network. The computation for the "weak datum" is much easier than that of the "strong datum". With observations of the demonstration constellation of global BeiDou satellite navigation system, AOD is conducted with different datum including no datum, "weak datum" and "strong datum". The results show that, for the "weak datum", the constellation rotation can be compensated with a priori orbit inclination angle and the right ascension of ascending node constraints. However, the AOD precision is worse than that of "strong datum". When no ground tracking system can be used, "weak datum" is recommended to realize the real AOD.

     

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