Abstract:

In view of the shortcoming that the data of the lunar back, cannot be directly measured and it leads to the low accuracy of the gravitational field, we propose an autonomous lunar gravitational field determination method based on dual satellite formation. Considering the effect of the lunar gravitational field on the relative position of satellite formation, the proposal adopts the extend Kalman filter (EKF) algorithm to handle the measurement data of satellite distance, and uses the difference between the measured data and the predicted data to modify the predicted status so as to obtain the estimate value of the status, thus realizing autonomous precise orbit determinations and determining the lunar gravitational field. The resulting system can achieve an orbital position accuracy of 5.04 m, an orbital velocity accuracy of 6.07×10-3 m/s, a gravity accuracy of 3.47×107 m3/s2 and the coefficient of a lunar perturbation accuracy of 9.14×10-8 in the time period of approximately 7 430 seconds. Simulation results verify the effectiveness of the program and improve the existing model of the lunar gravitational field to a certain extent. It can provide more technical information for the “Chang E Project” of China.

Key words: satellite formation;gravitational field;J2 perturbation;relative position;extend Kalman filter;lunar