北斗卫星偏航姿态调整期间的精密轨道确定

Yaw attitude control model of BDS satellites is significantly different from that of GPS/GLONASS/Galileo. For BDS IGSO and MEO satellites, the shift of attitude models is accompanied by dramatic degradation of the accuracy of orbit determination, undermining the availability of BDS satellites. It is shown in relevant study that the variation of satellite yaw attitude leads to the variation of non-gravitational forces subjected. However, the current solar radiation pressure models employed in precise orbit determination of navigation satellites are merely applicable for the scenario of normal attitude, which results in remarkable degradation of orbit accuracy during yaw maneuver. Aiming at the demand of precise orbit determination for multi-GNSS, the regularity of yaw attitude control for BDS satellites, as well as the theory and method for refining non-gravitational force models, is to be studied intensively. Based on the theoretical research, breakthroughs are expected in key technologies and software system is to be developed. By processing massive BDS/GNSS data, models for high precision yaw attitude control and non-gravitational forces will be established, to improve the accuracies of orbit determination and prediction for satellites under both yaw-fixed mode and eclipse mode. The achievements will not only provide important references in improving the present performance of BDS, but also in turn deepen our thoughts in the features of the other GNSS non-gravitational forces and sharpen our edge in precise data processing for multi-GNSS.

北斗卫星的偏航姿态控制模式较GPS/GLONASS/Galileo有显著差异，北斗IGSO和MEO卫星在其姿态模式切换期间的卫星轨道确定精度大幅下降，显著降低了目前北斗卫星的可用性。相关研究显示，卫星偏航姿态变化将引起非保守力发生变化，而当前导航卫星精密定轨中所采用的光压力模型仅适用于正常姿态下卫星精密定轨，致使姿态偏航控制期间，卫星轨道确定精度显著降低。本项目面向多卫星导航系统精密轨道确定需求，重点研究北斗导航卫星偏航姿态控制规律及非保守力模型精化的理论和方法；在理论研究的基础上突破关键技术，研制软件系统；并通过大量BDS/GNSS数据处理，建立高精度卫星偏航姿态控制及卫星非保守力模型，提高零偏模式下卫星和蚀卫星轨道确定和预报精度。研究成果不仅可作为提升目前北斗导航系统性能的重要参考，而且反过来增进我们对其它GNSS卫星非保守力特性的认识，从而促进多GNSS系统的数据精密处理能力的提升。

导航卫星偏航姿态同时影响观测值几何改正和卫星所受保守力，进而影响其精密轨道和钟差。北斗卫星的偏航姿态控制模式较其他全球卫星导航系统存在明显差异，北斗IGSO和MEO卫星在其姿态模式切换期间的卫星轨道确定精度大幅下降，显著降低了目前北斗卫星的可用性。相关研究显示，卫星偏航姿态变化将引起非保守力发生变化，而当前导航卫星精密定轨中所采用的光压力模型仅适用于正常姿态下卫星精密定轨，致使姿态偏航控制期间，卫星轨道确定精度显著降低。针对上述问题，项目组从制约北斗/GNSS精密定轨的姿态、光压等因素出发，系统研究并发展了相关的理论、方法和关键技术，提出了相应的模型算法，将北斗二号IGSO/MEO零偏期间定轨精度从米级提升至分米级。该项目成果直接应用于武汉大学IGS/MGEX和iGMAS分析中心发布的产品中，服务于高精度GNSS相关应用。项目组已发表相关SCI论文11篇，获软件著作权2项；培养已毕业博士7人，硕士4人。项目组获得省部级一等奖2项，项目负责人2019年入选中组部“万人计划”科技创新领军人才。