XNAV算法及其整周模糊度确定方法研究

Development of XNAV Algorithm and Cycle Ambiguity Resolution

X射线脉冲星导航(XNAV)是一种新型的航天器天文导航方法。研究了利用脉冲星脉冲相位观测信息进行导航卫星自主定轨的算法。首先分析了X射线脉冲在卫星和太阳系质心之间的传播时间方程,然后利用卫星与太阳系质心之间的相位差分观测量建立了系统的观测方程;结合导航卫星的轨道动力学特性,采用扩展卡尔曼滤波算法估计卫星的轨道。考虑到卫星轨道动力学预报得到的卫星位置值具有较好的精度,提出直接利用该位置预报值快速确定整周模糊度,并验证了该方法的可行性。数学仿真表明,该导航算法能够精确确定导航卫星在惯性系下的绝对位置。

The X-ray pulsar based navigation （XNAV） is a new celestial navigation concept for the spacecraft. The autonomous orbit determination algorithm using pulse phase difference of X-ray pulsars is investigated for navigation satellite. The transmission time of the X-ray pulse from the satellite to the solar system baryeenter is analyzed. The measurement equation of the satellite position is described with the pulse phase difference between the satellite and the solar system barycenter. The extended Kalman filter, which incorporates the navigation satellite dynamics and the pulse phase-based measurements, is developed to estimate the satellite orbit. Considering that the satellite position predicted by satellite orbit dynamics is accurate, the predicted satellite position is utilized to determine the cycle ambiguities, and this method is tested feasible. Simulation results demonstrate that this navigation algorithm can provide absolute position of the navigation satellite in the Earth centered inertial frame.