Autonomous orbit and attitude determination including time prediction based on XNAV and ultraviolet sensor

In order to improve the autonomous navigation ability of deep space spacecraft, the X-ray detector and ultraviolet sensor were applied simultaneously. The attitude angles and errors of time of pulse arrival of pulsars were measured by X-ray detector, and simultaneously the central body's barycenter line-of-sight vector, distance between spacecraft and the barycenter, and the attitude angles were measured by ultraviolet sensor. The state of the integrated navigation system includes position and velocity vectors in inertial coordinate system, attitude angles and clock error. The Federated Extended Kalman Filter (FEKF) was applied to estimate the state of the navigation system. Simulation results in Mars orbit demonstrate that this method can fulfill orbit determination, attitude determination and clock time prediction simultaneously. Moreover, this integrated navigation system can provide high navigation precision and predict clock time effectively.