XNAV/UVNAV/SINS integrated navigation system in spacecraft orbital maneuver

In view that the navigation solution of XNAV(X-ray pulsar-based navigation and timing) has low precision and is even divergent when applying XNAV independently in orbital maneuver, an integrated navigation system was proposed based on XNAV, ultraviolet-sensor-based navigation(UVNAV) and strapdown inertial navigation system(SINS). The position vector, velocity vector, attitude quaternions, and instrument errors of spacecraft in inertial coordinate system are taken as the state variables of SINS. The time of pulse arrival was detected by a X-ray detector. The line-of-sight vector, distance and attitude of the spacecraft relative to the barycenter of central body were measured by the ultraviolet sensor. An extended Kalman filter was applied to estimate the states of the navigation system. The simulation results show the feasibility of the integrated navigation system. This method can solve the problem of bad results, such as position error is too large(up to 10 ⁷m) when XNAV is applied independently in orbital maneuver. Moreover, the navigation precision of this integrated system is high, and the orbit determination accuracy of 100 m can be acquired in all stages of orbital maneuver.