一种基于星载GNSS接收机的高轨卫星自主导航滤波算法

A Spaceborne GNSS Receiver Based Autonomous Navigation Filter for HEO Satellites

星载GNSS接收机在低轨卫星自主导航和精密定轨等应用领域已经显示了高精度、高自主性、不依赖地面支持等技术优势。对于高轨卫星应用,星载GNSS接收机面临一些新的挑战。由于需要接收来自地球另外一侧的GNSS旁瓣信号,使得用户等效测距误差和几何分布因子恶化,引起标准定位性能下降。特别的,对于只能使用GNSS广播星历的实时自主导航应用,GNSS广播星历引入了非白噪声特性的用户测距误差。其难以被经典的EKF滤波方法平滑,限制了自主导航定位精度。文章研究一种基于星载GNSS接收机的高轨卫星自主导航滤波算法,该算法使用增强扩展卡尔曼滤波器(Augmented EKF)融合轨道动力学模型与GNSS观测数据,并对GNSS广播星历引入的系统性误差进行动态估计以削弱其对最终导航定位的影响。最后,通过仿真平台进行了算法验证。仿真结果显示,使用单GPS可在GEO轨道达到优于10米(3D RMS)的导航定位精度。文章提出的方法达到与国际先进产品同等精度,可用于高轨卫星高精度自主导航。

Spaceborne GNSS receivers have been widely used for LEO satellites navigation and POD applications because of technological advantages,such as high precision,high autonomy and independence on ground stations.But for HEO satellites applications,spaceborne GNSS receivers face some new challenges.Since side-lobe GNSS signals from the other side of the earth have to be used,user equivalent range errors and geometry dilution of precision are considerably degraded.Specially,for those real-time navigation applications which only GNSS broadcast ephemeris is available,non-white noise is introduced into user range errors thanks to broadcast ephemeris error.The autonomous navigation accuracy is limited since the classical EKF can hardly remove this kind of noise.A GNSS based autonomous navigation filter is researched in this article.An augmented EKF is employed to integrate GNSS observations and orbital propagator,and the systematic range errors are estimated along with receiver dynamics in order to weaken their effects on navigation results.Finally,the presented algorithm is verified in simulation platform.The simulation result shows:10 m(3 D RMS)navigation accuracy could be achieved in GEO orbit when only GPS is used.The method proposed in this research has similar accuracy as the leading international products,thus could be used for high-precision autonomous navigation of HEO satellites.