轨道外推器辅助下的高轨GNSS抗差定位算法

Robust GNSS Positioning Algorithm for High Orbit with Orbit Propagator Assistance

高轨卫星定轨一般使用基于地基的无线电、激光测量等方式,该方式通常存在测量时效性差、测量站点全球布站困难等问题。随着航天任务的逐步增多,卫星自主定轨重要性正在逐渐凸显,若卫星使用全球卫星导航系统(GNSS)进行定轨,将为其在轨自主运行提供便利。然而,高轨卫星搭载的GNSS接收机需要接收来自地球对侧的导航卫星信号,导致用户接收的信号强度极低,可用卫星数量少,且几何构型较差。本文针对高轨GNSS用户接收信号易被污染,使观测量出现粗差,导致定位解算结果缺乏鲁棒性的问题,提出了一种轨道外推器辅助下的高轨GNSS抗差定位算法。该算法基于传统GNSS与轨道外推器(OP)组合定位算法,针对高轨用户观测量的粗差进行抗差设计,提出了基于轨道外推器的预测结果对抗差定位算法中残差矢量和残差进行标准化的方法。本文对上述算法进行了仿真验证,在未添加粗差、GNSS信号仅受热噪声影响的条件下,传统GNSS/OP联合定位算法和轨道外推器辅助下的高轨GNSS抗差定位算法的定位精度分别为42.91 m和42.14 m;对观测量添加300 m粗差时,传统GNSS/OP组合定位算法定位精度为69.55 m,而轨道外推器辅助下的高轨GNSS抗差定位算法定位精度则为41.92 m。仿真结果表明,在对观测量添加不同粗差的情况下,添加粗差越大,轨道外推器辅助下的高轨GNSS抗差定位算法剔除粗差的效果越强,当添加300 m粗差时,轨道外推器辅助下的高轨GNSS抗差定位算法得到的定位精度与未添加粗差时基本相同,带有粗差的观测量被剔除,定位精度相比于传统GNSS/OP算法提升明显。因此,当部分观测量出现粗差时,轨道外推器辅助下的高轨GNSS抗差定位算法能够剔除带有粗差的观测量,提升定位精度。

Traditional methods of high-orbit determination relied on ground-based radio and laser measurements,which have significant limitations such as the delay in measurement processing and the logistical challenges of establishing measurement stations globally.Owing to the increasing number of space missions,the autonomy of satellite orbit deter-mination has attracted considerable attention.The use of global navigation satellite systems(GNSSs)for orbit determi-nation presents a promising solution by facilitating autonomous operations in orbit.However,high-orbit satellites,be-cause of their distant positions,encounter specific challenges when using GNSS,with the primary challenge being that these satellites need to receive signals from navigation satellites positioned on the opposite side of the Earth.This require-ment significantly weakens the received signal strength,reduces the number of available satellites,and results in poor geometric dilution precision,thereby complicating the orbit determination process.This study specifically addresses the susceptibility of high-orbit GNSS users'received signals to contamination,which could introduce gross errors into obser-vation data,undermining the robustness and accuracy of positioning solutions.To address this issue,we propose an in-novative high-orbit GNSS-robust positioning algorithm that leverages an orbit propagator(OP)for assistance.This algo-rithm is built upon the traditional GNSS and OP combined positioning method but introduces a novel approach to ro-bustly address gross errors in the observation data of high-orbit users.The proposed technique involved normalizing the residual vector and residuals within the positioning algorithm based on predictions from the orbit propagator.The effi-cacy of this proposed algorithm was rigorously evaluated through a series of simulations.In scenarios devoid of inten-tional gross errors,where GNSS signals were only influenced by thermal noise,the traditional GNSS/OP combined po-sitioning algorithm achieved a positioning accuracy of 41.92 m,whereas the robust GNSS positioning algorithm for high orbit with orbit propagator assistance demonstrated an accuracy of 42.14 m.The simulation further explored the per-formance under conditions where gross errors of 300 m were artificially introduced into the observation data.Under these conditions,the traditional GNSS/OP algorithm exhibited deteriorating positioning accuracies of 69.55 m.By contrast,the ro-bust GNSS positioning algorithm for high orbit with orbit propagator assistance achieved accuracies of 42.17 m.The simula-tion results indicate that,when different magnitudes of gross errors are added to the observations,the larger the gross er-ror added,the stronger the ability of the robust GNSS positioning algorithm for high orbit with orbit propagator assis-tance to eliminate gross errors.Remarkably,when a 300 m gross error was added,the robust GNSS positioning algo-rithm for high orbit with orbit propagator assistance achieved a positioning accuracy similar to that without the addition of gross errors.The observations with gross errors were eliminated,resulting in significantly improved positioning accu-racy compared with that of the traditional GNSS/OP algorithm.Consequently,this advanced algorithm significantly en-hances the robustness and reliability of high-orbit satellite positioning,marking a substantial improvement over the tradi-tional method.Thus,the robust GNSS positioning algorithm for high orbit with OP assistance provides a modern solu-tion to the challenges faced in high-orbit satellite navigation.By effectively addressing the issues of signal contamination and gross errors,the algorithm ensures enhanced positioning accuracy and operational reliability for high-orbit satellites.This result is crucial for the expanding landscape of space missions and the increasing demand for satellite autonomy.