Research On Constellation Autonomous Navigation Method And Its Accuracy Analysis

With the improvement of Beidou satellite navigation system, there is an urgent demand to realize the constellation autonomous navigation in order to enhance the ability of autonomous operation and meet the requirement of solving the limits of regional monitoring station network.In this paper, the paper analyzes the impact of satellite ephemeris error on positioning precision starting from the error sources of satellite navigation and positioning. On one hand, Ephemeris error comes from constellation autonomous orbit determination method. On the other hand, it is originated in earth orientation parameter error during coordinate transformation. To solve such problems, this paper focuses on the method of constellation autonomous orbit determination based on X-ray pulsars relative observations and forecasting method of earth orientation parameters. The main contents of this paper include as follows,Firstly, the paper introduces the theory and precision analysis for satellite navigation and positioning. Time and coordinates systems are defined, and coordinate transformation model from ECI(earth centered inertial system) to ECEF(earth centered earth fixed system) is introduced; Pseudo-range single point positioning model and algorithm are introduced, then the influence of satellite ephemeris error on positioning precision is analyzed through simulation.Secondly, an approach of constellation autonomous orbit determination via X-ray pulsars observations is studied. The paper introduces the principle and model of autonomous orbit determination for satellite constellation, and combines two-way ranging of satellite link with relative orbit determination based on pulsars. The paper computes the relative time delay of the pulse signals reaching two satellites based on waveform by cross-correlation algorithm and maximum likelihood method. Relative navigation is are realized by simulation using proposed orbit determination method.Thirdly, the paper studies a forecasting method of earth orientation parameters. The earth orientation parameters and the data processing method are presented. The prediction approach is introduced, including Least-Square prediction and time series analysis model, and presents the algorithm for model computation. The results show that the prediction accuracy is better than the least square method of time series analysis, which are simulated using experimental data. The prediction error of the earth orientation parameters of satellite ephemeris is analyzed based on the orbit dynamics model and coordinate transformation model.Lastly, the paper designs constellation autonomous navigation software for precision analysis and assessment. Satellite navigation orientation system is divided into two modules, i.e. user and space segments. These two modules are divided into several sub-modules, and each sub-module is required to implement a specified function defined by flow design. A joint simulation is performed to analyze the influence on the positioning accuracy of the satellite ephemeris error, in order to verify performance of constellation autonomous navigation method.