Research On INS-aided GNSS Vector Tracking In Complex Electromagnetic Environment

With the rapid development of navigation technology,the performance of navigation system in precision,reliability and integrity is required more and more highly.And in practical application,the vehicle is more and more under the environment of high dynamic and complex electromagnetic.The most widely used two kinds of navigation system are INS(Inertial Navigation System)and GNSS(Global Navigation Satellite System)at present,and they have their own advantages and disadvantages.INS/GNSS integrated navigation system can combine their advantages so that the navigation system has a high positioning accuracy and can be continuous positioning in the strong electromagnetic environment.The integrated navigation system is divided into loosely,tightly and ultra-tightly integrated(or deeply coupled)system according to the level of data fusion between two subsystems.This paper researches on INS-aided-GNSS vector tracking.Firstly this paper discusses the background and research status at home and abroad about our subject and analysis the future development trend.At the following of introducing about the three kinds of integrated navigation structures,we analyze their characteristics and the difference between them.We further divide the ultra-tight integrated system into the centralized filter structure and cascade filter structure based on the difference of flow of information between GNSS subsystem and navigation filter.Considering that the centralized filter structure require higher speed of signal processing in practical application,this paper designs the INS-aided-GNSS vector tracking system based on centralized filter structure.We propose a method to derive this system’s discretization transfer function,and give the expression of loop bandwidth for INS-aided-GNSS tracking loop.The influence of C/N0 on the bandwidth of INS-aided-GNSS vector tracking loop is analyzed by simulation method.Finally,we analyze the performance of the INS-aided-GNSS tracking loop,and the tracking error model is provided.Furthermore,we analyze the influence of C/N0,LOS and the precision of IMU on tracking error.To verify the feasibility of tracking loop we designed before and its satisfactory performance,a dynamic simulation system based on Matlab language is built.Analysis of the experiment results shows that the model of INS-aidedGNSS vector tracking designed in this paper is feasible and that the carrier frequency errors and code phase errors from discriminators are smaller.On the other hand,in the experiment in which there is electromagnetic interference,INS-aided-GNSS vector tracking loop shows the better tolerance property of electromagnetic interference.In a word,these simulation experiments all indicate that INS-aid-GNSS vector tracking has much better performance.