Research On Algorithms For Improving Positioning Precision In Beidou Satellite Navigation System

With the continuous progress of navigation technology,the positioning algorithm of Beidou Satellite Navigation System has always been the focus of scientific researchers.The advantages and disadvantages of the algorithm directly affect the final positioning accuracy.In order to improve the positioning accuracy in BDS,this paper conducted theoretical research and experimental analysis on the positioning algorithm.First,On the mature technology of global satellite navigation system is introduced.According to the principle of pseudorange positioning system mathematical model is established,and describes how to use the navigation message to the parameters in the calculation model of the three-dimensional coordinate of the satellite system mathematical formulas and use all kinds of error correction model of pseudorange observation,finally through th e computer simulation to get satellite coordinates and pseudorange data before and after correction,the correction of pseudorange observation error decreased 7.30m.Then focus on the two classic algorithms th at are most widely used in navigation:Least Squares(LS)and Extended Kalman Filtering(EKF).In view of the fact that LS cannot solve the problem of credibility in pseudorange observations,the concept of weight is added to pseudorange observations,and a new weighted least square(WLS)method is proposed.Experimental simulation shows th at WLS positioning The accuracy is better than traditional LS,and the average positioning accuracy is improved by 1.503m.The experimental simulation of EKF found that its accuracy after positioning was higher than WLS,and the average positioning accuracy was improved by 2.208m.Finally,an algorithm combining WLS and EKF is proposed to reduce the influence of initial values on EKF and suppress the filter divergence that occurs during long-term continuous positioning.The LS and WLS positioning results are used as the initial values of EKF for experimental simulation and comparison,which proves that the combination of WLS and EKF enables EKF to enter a stable state faster.When using EKF for continuous long-term positioning,the error of the EKF positioning result is much larger than the error of the WLS positioning result at a certain moment,and the filter divergence phenomenon occurs.At this time,the WLS positioning result is adaptively adopted to suppress the filter divergence.The simulation results show that this method effectively solves the effect of the initial value of EKF on the positioning results,and at the same time it well solves the divergence phenomenon of EKF long-term continuous calculation.