基于X射线脉冲星的航天器自主导航算法分析

摘要

Pulsar can be used as time standard because of its very stable rotation. The astromctric parameters and astrophysical parameters such as the space position, proper motion, distance, rotation period and its derivative of many pulsars can be measured accurately.Pulsars can provide time signal and space position coordinate, so spacecraft can realize autonomous navigation by pulsar navigation system fixed on spacecraft. Firstly, spacecraft position is predicted based on orbital dynamical equations of spacecraft. Secondly, the difference between the observed time of arrival (TOA) on spacecraft and the predicted TOA with the model is calculated. Thirdly, the estimated position error is calculated by using Kalman filter and the position of spacecraft is modified. Finally, the influence of initial position error, the measured precision of TOA of pulse and the number of pulsars on navigation precision is analyzed.%脉冲星自转非常稳定,可以用作时间标准,许多脉冲星的空间位置、自行、距离、自转周期及其导数等天体测量参数和天体物理参数都能被精确测定.由于脉冲星能够同时提供时间信号和空间位置坐标,安装在航天器上的脉冲星导航系统能够实现航天器的自主导航.首先根据航天器轨道动力学方程预测航天器的位置,再通过航天器上观测的脉冲到达时间和预报的脉冲到达时间之差,应用Kalman滤波计算航天器位置估计的误差,从而对航天器的位置进行修正.最后,分析初始误差、脉冲到达时间测量精度、脉冲星个数对导航精度的影响.