Integrated navigation based on pulsar in libration point orbit

Libration point orbit is playing more and more significant role in deep space exploration. X-ray pulsar-based navigation (XNAV) is a novel and promising autonomous navigation method. However, there are only a few research papers concerning how to employ XNAV in libration orbit, especially the application of integrated navigation based on XNAV. The libration orbit is unstable. It is a new research topic for us to delve deeper. To improve the autonomous navigation performance in halo orbit, an integrated navigation method was proposed. The dynamic model of halo orbit was presented. Two-level differential correction method was introduced. The measurement models of the XNAV and the ultraviolet sensor were analyzed. The federated unscented kalman filter based on UD factorization was adopted to estimate the state of the system. The clock error correction was included in the filter. The simulation results show that the proposed integrated navigation is feasible in halo orbit of Earth-Moon system, and can provide better performance in comparison with XNAV or ultraviolet sensor-based navigation. Not only can the integrated navigation obtain a highly accurate spacecraft position, but also it can restrain clock drift.