基于GPS伪距的微小卫星定轨技术研究

Research on Orbit Determination of Micro-satellite Using GPS Pseudo-range

高可靠、高精度、低成本的全自主导航是现代微小卫星定轨领域的发展方向,GPS以其在成本、精度、功耗等方面的独特优势,在低轨航天器上得到应用。论文采用GPS伪距作为观测量,在可见星较少的情况下仍可得到观测信息,较GPS直接输出提高了导航精度,并能进一步降低硬件成本。还引入了衰减记忆滤波算法,通过调节协方差矩阵,削弱了历史量测信息对当前数据融合的贡献,从而减小了轨道摄动对定轨精度的影响。仿真结果表明当导航星数目较少时,该算法仍可实现信息融合,且显著提高了定位精度。

The trends of developing micro-satellites are high reliable, high accuracy, completely autonomous and low cost. GPS has been applied in low earth orbit spacecraft, because it has the advantages of low cost, high accuracy and low power consumption. The GPS pseudo-range was used as measurement values, and the measurement still could be obtained even when the GPS visible stars were few. The orbit accuracy was improved and the cost was reduced. The memory attenuated extended Kalman filter （MAEKF） was presented. Through adjusting covariance matrix, the application of historic data in the new data was reduced, so the influence of orbit perturbation on orbit accuracy was reduced. The simulation reslts show that the MAEKF is better than extended Kalman filter （EKF） in accuracy. When visible GPS stars are few, it still can realize information fusion.