Research On High Precision Positioning Technology Based On Freeflow Toll Collection System Of Expressway

The existing toll modes of expressway in China mainly include manual toll,manual semi-automatic toll and electronic non-stop toll.At present,ETC charging models are being vigorously promoted nationwide,but ETC charging still has technical problems such as path ambiguity and adjacent channel interference.In order to solve this kind of problem,China began to study freeway toll collection system based on Beidou high-precision positioning technology,which can realize accurate tracking and positioning of vehicles and deduct tolls.For the free flow toll collection system of expressways based on Beidou high-precision positioning technology,an important prerequisite for its effective functioning is the accurate continuous positioning of free flow vehicles.This paper mainly studies the application of Beidou high-precision positioning,BDS/INS integrated navigation and other high-precision positioning technologies in the free flow toll system of expressways.This article mainly completes the following tasks:(1)According to the application requirements of Beidou free-flow toll system and indepth research on Beidou high-precision positioning technology,network RTK technology is selected to be used in free-flow terminals to achieve centimeter-level positioning of freeflow vehicles.In addition,this article conducts research and design on the important infrastructure for network RTK technology implementation,namely the Beidou free-flow CORS system.(2)Network RTK positioning technology has high positioning accuracy,but in the occluded environment,there is a problem of discontinuous positioning interruption.In view of this problem,this article conducts a detailed study of the BDS/INS integrated navigation and positioning,selects the BDS/INS loose combination method,and then based on the extended Kalman filtering algorithm and output correction,designs a BDS/INS integrated navigation uninterrupted positioning system suitable for the free-flow toll collection environment of Beidou expressway in this paper.It has been verified that the system can guarantees continuous,lane-level vehicle positioning during the short-term loss of RTK signals.(3)Based on the above network RTK technology and BDS/INS integrated navigation uninterrupted positioning technology,the software and hardware design of the free-flow terminal is included,including hardware design and program design for connecting the Beidou free-flow CORS system.At the same time,combined with the high-resolution map of the free flow toll station on the highway,the vehicle position recognition algorithm is designed to obtain the vehicle's position information in the free-flow toll station and uploaded to the cloud platform to request a lift.(4)Test and analyze the positioning performance and function of the free-flow terminal.The results show that when a free-flow vehicle passes the Beidou free-flow test lane at a speed of 50km/h and a maximum speed of 60km/h,it can achieve a lane-level positioning accuracy with error less than 0.4m.With the high-precision map of the toll station area,lanes can be successfully identified and the function of requesting lifts can be successfully performed,the correct rate of charging can reach 100%.