Research on autonomous navigation algorithm for spacecraft based on X-ray pulsars

An autonomous X-ray pulsars navigation algorithm based on the extended Kalman filter (EKF) is proposed for spacecraft in order to realize 100m position accuracy. The measurement equation of spacecraft position is described with the TOA difference between spacecraft and the solar system barycenter. Then, the EKF, which incorporates spacecraft dynamics and TOA measurements, is developed to estimate spacecraft orbit. Simulation results demonstrate that this navigation algorithm is more accurate as the information contained in the satellite orbit model can be used when the EKF is adopted. 100m position accuracy can be achieved with pulsar orientation errors, 0.001″, and timing errors, 0.1µ s. Analysis and study show that this method represents high position accuracy, good convergence speed and stability with respect to previous method of least square and maximum likelihood.