基于多星座信息的高轨航天器自适应自主导航方法

Adaptive autonomous navigation method of high Earth-orbit spacecraft based on multi-constellation information

采用四类星座系统确定高轨航天器的轨道,以解决目前应用单模或双模定位系统导航时可见性、可靠性和可用性低的问题。分析了星座卫星的可见性与兼容性,并基于加权几何精度因子(Weighted Geometric Dilution of Precision,WGDOP)实现选星。采用星座/惯性紧组合的方式,针对各星座系统存在时间同步差异的问题,将各个星座系统的时钟同步误差作为导航系统的状态变量进行实时估计,实现软同步;针对高轨航天器接收到的导航卫星信号微弱、量测噪声的不确定性大的问题,对滤波器中的量测噪声方差阵进行在线自适应调整。数学仿真表明,在系统的量测噪声具有较大的不确定性,不能准确建立量测误差模型时,采用改进的自适应滤波算法,与扩展卡尔曼滤波(Extended Kalman Filter,EKF)相比,导航精度可提高一倍。

An adaptive autonomous navigation method for high earth orbit spacecraft is proposed by using four constellation systems to overcome the shortcomings of low visibility, liability and usability of single mode or dual-mode positioning systems. Firstly, based on the analysis of visibility and compatibility of constellation satellites, the satellite selection is realized by utilizing weighted geometric dilution of precision (WGDOP) algorithm. Secondly, considering the fact that there exists a non-synchronization phenomenon in the constellation systems, the synchronization error of each constellation system is estimated in real time as state variables of the navigation system with constellation/INS tightly coupled integration, which achieves soft synchronization. Thirdly, the measurement noise variance matrix of the designed filter is adjusted adaptively to solve the problem of weakness of the received satellites signal and the strong uncertainty of the measurement noise of the high orbit spacecraft. Finally, simulation results are provided, which illustrate that compared with extended Kalman filter(EKF), the navigation accuracy can be enhanced by 50% using the proposed adaptive filtering algorithm when there exists strong uncertainty in the measurement noise and unable to set up the precise model of measurement error.