Research On Long-term Orbit Determination For Navigation Constellation Supported By Ground Base Or Spatial Orientation Base

Long-term autonomous orbit determination for navigation constellation is one of the key techniquesof CNSS (Compass navigation satellite system). Although the method for autonomous orbitdetermination of navigation constellation based on cross-link range turns out to be an effective one toupgrade the capacity of autonomous orbit determination. The cross-link range observation can notdetermine the rotation and translation of the entire constellation. As a result, the accuracy ofautonomous orbit determination is reduced with time.In this paper we focous on the long-term orbit determination for navigation constellation and usetwo approaches to solve this problem. One is to measure rotation and translation of the entireconstellation by means of inter-satellite photographic observations, which can realize long-termautonomous orbit determination for navigation constellation. In this way, a spatial orientation base isbrought to the entire constellation by using a star sensor to observe the other satellite in constellationand the background stars from one satellite. The other is to use a few ground stations to bring thenavigation constellation and ground into connection, which can realize long-term semi-autonomousorbit determination for navigation constellation. In this method only1~3ground stations is used in theorbit determination for navigation constellation which accords to the geographical conditions ofChina.At last, we use GPS navigation constellation to verify our method and the true IGS ephemeris isused to do simulation which is more meaningful both in theory and practice. In our simulation, EKFalgorithm is used in the procession of data processing. Besides, we purpose a type of hybridsimulation system direct against inter-satellite orientation observation using star simulator and starsensor, which can provide inter-satellite orientation observation information with high precision forthe autonomous orbit determination for navigation constellation. The simulation results show thatboth the two approaches can overcome the the defect of entire constellation rotation and translationrelative to the inertial reference frame effectively. Accoring to the practical application in engineering,the first approach needs the support of the star sensor with high-precision, while the second approachis more suitable for the national conditions of China and is of important practical significance.