北斗系统地固系自主定轨算法

为避免传统惯性系自主定轨算法中的多次坐标转换，针对地固系分布式自主定轨算法原理及其中的关键技术开展研究。给出在地固系中进行自主星历生成的总体框图，推导了地固系自主定轨算法的基本方程，提出一种新的以地固系位置速度为状态量的状态转移矩阵解析计算方法并分析其计算量，证明了地固系自主定轨算法可以进一步降低定轨算法复杂度，且无需上注地球定向参数进行坐标转换。使用仿真数据和真实在轨测量数据的测试结果表明，提出的地固系分布式自主定轨算法与传统算法定轨精度相当，说明了所提算法的可行性，验证了星载自主定轨原型软件的有效性。

The Autonomous Orbit Determination Algorithm in Earth Centered Earth Fixed Reference Frame of Beidou System

This paper focuses on the principle and key technologies of the autonomous orbit determination algorithm in the Earth-centered Earth-fixed (ECEF) reference frame, aiming at avoiding the coordinate transformations in the Earth-centered inertial (ECI) reference frame. The framework of the autonomous ephemeris generation in ECEF reference frame is given, and the fundamental equation of the autonomous orbit determination algorithm in the ECEF reference frame is derived. Then, an analytical calculation method of the state transition matrix, which takes the position and velocity of the satellite in the ECEF reference frame as the state vector, is put forward and its computation load is analyzed. It is proved that the proposed autonomous orbit determination algorithm in the ECEF reference frame can decrease the complexity of the orbit determination algorithm, and it doesn’t need the Earth orientation parameters (EOP) for coordinate transformation. The test results based on the simulation data and onboard measurement data show that the proposed algorithm in the ECEF reference frame can achieve the same performance as the traditional algorithm. This proves the feasibility of the proposed algorithm and verifies the effectiveness of the onboard autonomous orbit determination prototype software.