Research On Navigation Satellite Autonomous Orbit Determination Based On Ground Anchor Stations

With the development of the satellite navigation system, navigation satellite autonomousorbit determination is of great significance to improve the viability of the satellite navigationsystem and orbit determination accuracy. For our Beidou Satellite Navigation System, thedevelopment of autonomous orbit determination techniques can effectively make up for orbitdetermination defects due to China’s difficult to establish a globally distributed ground trackingstations. In this paper, for satellite autonomous orbit determination, study focusing on the theoryand method of satellite autonomous orbit determination based on ground anchor stations, verifyand evaluate the performance of it through simulation, and draw the relevant conclusions. Themain works as follows:1. The overview of research on the satellite autonomous orbit technology domestic andinternational is made. The brief introduction to the development of the technology of GPSsatellite autonomous orbit determination is made. The significance of developing the technologyof autonomous orbit determination from the trends of global satellite navigation system and theactual needs of the construction projects in China is made.2. The theory and method of autonomous orbit determination based on inter-satelliteranging is summarized. The concept, the theoretical basis, the workflow and the processing modeof autonomous orbit determination are discussed. The inter-satellite ranging equation and itslinearization are deduced. The mathematical model of autonomous orbit determination of thewhole network based on inter-satellite ranging is given, and the factors affecting the autonomousorbit determination accuracy is analyzed.3. For the constellation overall rotation and its related problems, it is analyzed specifically.Obtained By software simulation analysis，the main reason for the constellation of overallrotation is the change in satellite orbit ascending node. The partial derivative expressions of thedistance between satellites to orbital elements are deduced, according to the expressions, wedraw a conclusion that the orbit ascending node cannot be observed by inter-satellite ranging andit would cause the normal equation coefficient matrix rank deficient in autonomous orbitdetermination calculating.4. The theory of satellite autonomous orbit determination based on ground anchors isanalyzed. The principle of autonomous orbit determination based on ground anchors is described,by deducing the partial derivative expression of the satellite-to-station distance to satellite orbitascending node, it is proved that the orbit ascending node can be observed by satellite-to-stationranging, and the constellation overall rotation is controlled, the normal equation coefficientmatrix rank deficient problem is solved. By analyzing the partial derivative expression of the satellite-to-station distance to satellite orbit ascending node, it can be obtained that the groundanchor station location’s latitude is an important factor to the correction level ofsatellite-to-station distance to satellite orbit ascending node.5. The autonomous orbit determination distributed algorithm based on extended Kalmanfilter is studied. High-level matrix inversion is avoided by distributed processing，and thespaceborne processor computation is reduced,it can be conducive to the real-time autonomousorbit determination. Based on the extended Kalman filter, the observed variance is increased avalue by observation error covariance matrix to absorb other satellite state associatedmeasurement error, the extended Kalman filter algorithm based on increasing the observedvariance is deduced. And the robust estimation theory is applied to the autonomous orbitdetermination algorithm; the robust filtering algorithm in distributed processing mode ofautonomous orbit determination is also studied.6. The autonomous orbit determination based on ground anchor stations is realized bysimulation. According to the experimental results, verify the effective feasibility of autonomousorbit determination method based on ground anchor stations. And the influence of the anchorstation location and quantity, the ranging noise and ranging frequency on autonomous orbitdetermination accuracy are analyzed through simulation. Finally, verify the validity of the robustfilter in autonomous orbit determination algorithm.