Research On Ground-based Pseudolite With Independent Networking And Inertial Navigation Integrated System

The ground-based pseudolite system with independent networking can provide high-precision and high-frequency navigation and positioning information.However,due to the influence of environment,when the number of visible pseudolite is less than 4 due to the occlusion of pseudolite signals,the user receiver cannot work normally.Inertial navigation system(INS)is a passive and autonomous navigation system which is not affected by the external environment.However,due to its working principle,navigation and positioning errors will accumulate with time,so pure INS usually cannot work alone for a long time.The integrated system of ground-based pseudolite and inertial navigation can solve the above problems well,it can not only make up for the problem of inertial navigation system error accumulation,but also provide navigation and positioning results continuously by inertial navigation in a short period when pseudolite receiver cannot locate and solve due to some problems.Therefore,the integrated system of ground-based pseudolite with independent network and inertial navigation is studied in this paper.The main research results of this paper are as follows:(1)Based on the in-depth study of the principles of INS,the velocity solution,attitude solution and position solution model of the system are constructed by using Matlab/Simulink.Through the simulation analysis of the system error through the model,the correctness of the INS theory and algorithm is verified by the simulation results,and the characteristic that the pure inertial navigation system errors will accumulate with time is obtained.(2)Briefly introduces the positioning principles and system composition of the ground-based pseudolite system with independent network,analyzes and studies the four main problems in the error source of the ground-based pseudolite system,such as near-far effect,multipath effect,base stations layout position and time synchronization,and the actual base station layout and positioning test are carried out in Xiamen Hairun wharf.Through the test,it is concluded that the ground-based pseudolite system with independent networking has high precision and high data update frequency,but the positioning results are seriously affected by the environment.(3)According to the advantages and disadvantages of INS and ground-based pseudolite system with independent networking,the application of Kalman filter in integrated navigation is studied.A loose combination Kalman filter model with position and velocity as observation variables is established.The simulation results show that the integrated navigation system can effectively suppress the divergence of navigation parameter errors in INS and achieve good results.In order to increase the reliability of the system,an integrated navigation mode selection method is proposed.The method will analyze and study the measurement information of INS and pseudolite system before entering Kalman filter to judge whether the navigation information is reliable and which navigation mode to enter.