Research On GPS/BDS/Galileo/INS Integrated Positioning And Integrity Monitoring Algorithm

GNSS dynamic positioning can reduce the accuracy or even can not get the positioning results in the complicated urban environment.GNSS/INS integrated navigation technology can overcome the above shortcomings and improve the accuracy and continuity of GNSS positioning.Compared with the loosely coupled navigation,the tightly coupled navigation is not limited by the number of satellites,and more satisfies the user's high-precision positioning needs.In addition,the integrity monitoring of integrated navigation can improve the reliability of GNSS positioning and the ability to distinguish faults.This paper mainly studies the GPS/BDS/Galileo relative positioning data processing,GPS/BDS/Galileo/INS loosely coupled algorithm,GPS/BDS/Galileo/INS tightly coupled algorithm and GNSS/INS receiver autonomous integrity monitoring algorithm.The main content and results are as follows:(1)The theoretical basis of GPS/BDS/Galileo relative positioning data processing is introduced,three GPS/BDS/Galileo relative positioning mathematical models are given,and the least square estimation and Kalman filter algorithm Estimation methods are emphatically explained,then the mathematical model of short-baseline relative positioning is studied.Experimental results show that GPS/BDS/Galileo positioning availability,ambiguity fixation success rate and positioning accuracy are better than single system,and this advantage is more obvious in restricted environments.(2)The related content of GPS/BDS/Galileo/INS loosely coupled algorithm is studied,four commonly used INS coordinate systems and their conversions are given,and the attitude,velocity,and position update algorithms in the "East-North-Up" coordinate system are derived.Based on the above update algorithms,the strapdown inertial navigation error equation is derived,and then the GPS/BDS/Galileo/INS loosely coupled positioning model is given.Experimental results show that the position and speed accuracy of GPS/BDS/Galileo/INS loosely coupled solution is better than GPS/BDS/Galileo relative positioning.(3)The related content of the GPS/BDS/Galileo/INS tightly coupled algorithm is studied,the extended Kalman filter and the Kalman filter test are introduced,the principle of INS-assisted GPS/BDS/Galileo ambiguity fixation is explained,a fixed ambiguity improvement strategy that takes into account the correlation of double-difference observations is proposed,and the GPS/BDS/Galileo ambiguity fixation principle is explained,the BDS/Galileo/INS tightly coupled positioning model is given.The experimental results show that in terms of internal coincidence accuracy,the position,velocity and attitude accuracy of the self-compiled program tightly coupled solution is higher,the ambiguity fixation rate is significantly improved;from the perspective of the external coincidence accuracy,the position and velocity results of the self-compiled algorithm tightly coupled solution have a small gap with IE reference value,while the result of attitude result has a gap with IE reference value.(4)The receiver autonomous integrity monitoring algorithm of GNSS/INS is studied,the theory of receiver autonomous integrity monitoring is introduced into the GNSS/INS integrated navigation system,the dynamic model and state vector in integrity monitoring algorithm are deduced,and the process of INS-assisted GNSS integrity monitoring is explained.The experimental results show that the tightly coupled navigatiom of GPS/GLONASS/Galileo/INS has higher accuracy of position,velocity and attitude calculation compared with the tightly coupled navigatiom of GPS/INS and GPS/GLONASS/INS,the MDB convergence time is shorter and the MDB value is smaller,and the correlation coefficient between the two satellites is smaller;the three tightly coupled modes all pass the EKF measurement value,the state value w test and the variance factor test.