Integrated navigation based on pulsar and sun sensor in sun-earth Halo orbit

To improve the performance of autonomous navigation in the Halo orbits, an integrated navigation system based on X-ray pulsars and sun sensor was proposed. For X-ray pulsar-based navigation (XNAV), the X-ray pulse time of arrival could be measured by the X-ray detector. The sun sensor was used to obtain the line-of-sight vector towards sun. The full ephemeris dynamics model of the Halo orbit in sun-earth system was established. The nominal Halo orbit in the earth-centric inertial coordinate system was calculated using two-level differential correction method. The state of the navigation system was estimated via the federated unscented Kalman filter (UKF) based on UD factorization. Several perturbation factors were discussed in the simulation. Simulation results show that the proposed integrated navigation scheme is feasible in sun-earth Halo orbit. Compared with the XNAV navigation, the navigation accuracy is improved.