Microsatellite Autonomous Orbit Propagation Method Based on SGP4 Model and GPS Data

With the development of aerospace technology, it is possible nowadays to develop orbit propagation algorithms for microsatellite autonomous flight. In recent years, global positioning system (GPS) is widely used in microsatellites' real-time orbit determination. However, due to the limitation of the on-board computation power, it is necessary to select an appropriate method for autonomous orbit propagation. The SGP4 analytical model has the characteristics of moderate forecast accuracy and little computational complexity. It can recursively obtain the microsatellite's position and velocity states based on the given initial parameters. In order to improve the autonomous flight ability of low earth orbit (LEO) microsatellites, an autonomous orbit propagation method is proposed based on SGP4 model and GPS data in this paper. The GPS data is used to obtain the microsatellite's initial TLE parameters based on the Downhill Simplex Method (also called Nelder-Mead Method). Then, the GPS real-time data is used to design an epoch state Kalman filter correcting TLE parameters. The simulation results are performed to demonstrate the proposed algorithm.