Autonomous Navigation and Control in Halo Orbit Based on XNAV

Objective To improve the independent capacity of the halo orbit spacecraft,we propose an autonomousnavigation and control system based on the X-ray pulsar-based navigation(XNAV)principle.XNAVtheory is applied in the construction of a measurement equation.The full ephemeris dynamical modelis adopted in the establishment of the system state equation.We use the two-level differential correc-tion method to obtain a nominal halo orbit in the inertial coordinate system.Based on the differentialcorrection method,the halo orbit spacecraft is controlled using the navigation results from XNAV andthe small thrust propeller.A numerical simulation is carried out in the Earth-Moon L2halo orbit.Theresults demonstrate that the proposed method can accomplish autonomous navigation and control taskseffectively and the spacecraft can be maintained in the nominal orbit.