Research On Key Techniques Of SINS/BDS Integrated Navigation System With Astronomy And Pressure Assisted

The Aerospace Vehicle has characteristics of flight such as hypersonic,maneuvering and longrange long-haul.The bad flight environment and arduous task of Aerospace Vehicle impose particular high requirements on the autonomy,reliability and accuracy of its navigation system.China's Beidou Navigation System has been initially established and is expected to achieve the grand goal of covering the whole world by 2020.This has enabled our country to get rid of dependence on GPS or other satellite navigation systems,which has important strategic significance to national defense security.Beidou Navigation System has high precision,but vulnerable to electromagnetic interference and deception,and easily can not be used during the war.The inertial navigation system has the advantages of high precision in a short time,free from electromagnetic interference and full autonomy,and the combination with the Beidou navigation system can restrain the inertial navigation system from gradually diverging with time and becomes the main navigation means of the future aircraft in China.In this paper,aiming at the high demand of navigation system for spacecraft during the special missions,the theory and implementation of SINS/BDS integrated navigation system with CNS and Pressure assistance are carried out.SINS/BDS tight integrated navigation system has no strict requirements for the number of visible BDS's satellites relative to loose integrated navigation system,and easy to implement relative to the deep method.Based on this advantage of SINS/BDS tight integrated navigation system,the error model of SINS/BDS integrated navigation system is analyzed,and the state equation and measurement equation of integrated navigation system are established.The simulation results show that the proposed error model and the combination model are correct and reasonable.During the ASV's dynamic flight,the number of BDS's visible satellites dynamically changes,and the measurement information is susceptible to interference and deceit,resulting in the quality of the BDS ephemeris information is unstable.According to the instability and fraudulent characteristics of BDS ephemeris information,the research of SINS/BDS integrated navigation system adaptive filtering algorithm and fault detection algorithm are carried out.Based on the number of visible BDS satellites and the satellite geometry,the real-time adjustment of the Kalman filter's pseudorange and pseudorange rate measure noise matrix value is used to the to achieve the adaptive effect.The traditional chi-square fault detection method can only detect system failure and can not identify the faulty satellite.Therefore,based on the traditional chi-square fault detection,this paper uses the dynamic characteristics of the new message to identify the faulty satellites and eliminate them,so that the health stars can still assist the SINS for high-precision navigation.The simulation results show that the fault detection algorithm and the adaptive filtering algorithm studied in this paper can greatly improve the stability and accuracy of the navigation system.In the harsh flight environment,the SINS/BDS integrated navigation system's attitude accuracy and high accuracy can not meet the high requirements of ASV's navigation system.In order to further improve the accuracy and stability of the navigation system,this paper proposes an auxiliary scheme of CNS and Pressure assisted SINS/BDS tight integrated navigation system.Using astronomical information to assist the attitude information of the system,the pressure altitude information is used to improve the stability of the altitude channel.The specific schemes of astronomical assistance,air pressure assistance,astronomy and air pressure assistance are given respectively,and the simulation and analysis of the proposed auxiliary scheme are carried out.The results show that the introduction of astronomical information has greatly improved attitude accuracy of ASV,and the information of pressure altitude can significantly improve the altitude instability of the integrated navigation system.Based on the above theoretical algorithm research,this paper develops a prototype of integrated navigation system based on Qt Creator that can be cross-platform ported.The hardware part of the integrated navigation prototype consists of navigation computer,Beidou software receiver,MTI-700 inertial element and so on.The part of software adopts multi-thread concurrency mode to work,and can cross-platform transplant between Windows system and Linux system platform,which improves the cutoff of the system,reduces the coupling between different work modules,and easy to maintain the system development.The navigation prototype can visually display raw data and navigation data of the sensor,and has network communication functions,two-dimensional trajectory display functions and map calling functions.Finally,real-time dynamic experiments on the developed navigation prototypes are carried out.The experimental results show that the navigation prototype can work steadily for a long time and can output high-precision navigation information continuously,which provides a useful reference for the engineering realization of the theoretical contents studied in this paper.