Abstract:

The X-ray pulsar navigation system (XNAV) is a nonlinear system. It is difficult to obtain the statistical characteristics of the process noise accurately. The improper assumption of XNAV leads to poor performance of the filter estimation. A multi-information fusion navigation method based on the adaptive divided difference filter (ADDF) is proposed. In order to reduce the navigation error, based on the traditional pulsar timing observation, the star elevation angle and the incremental phase between the two moments are appended to enhance the XNAV together. First of all, the time observation , incremental phase and star elevation model are established respectively. Then, this measurement model is integrated into the spacecraft orbit dynamics to build the ADDF filter model. Finally, the proposed method is verified by simulation. Under the condition of the same initial state and initial noise error, the experimental results show that the multi-information fusion algorithm can reduce the estimated value of navigation position error to about 200 m. Compared with the conventional X-ray pulsar navigation algorithm, the accuracy of position estimation and velocity estimation are increased by more than 70% and 40% respectively. Moreover, The performance of ADDF is better than that of the unscented Kalman filter.

Key words: X-ray pulsar, Adaptive divided difference filter(ADDF), Time of arrival, Information fusion