Research On UWB/IMU/GPS Integrated Cooperative Positioning Method In ITS

To realize relative positioning in the Vehicular Ad-hoc Network(VANET)has become a vital premise for the development of emerging intelligent transportation systems,which can provide positioning information for vehicle safety applications,such as vehicle collision avoidance and speed warning.The primary method to realize relative positioning among vehicles was to use mercantile grade Global Positioning System(GPS)receivers.However,the positioning accuracy achieved by the mercantile grade GPS receivers can't meet the practical requirements of the vehicle safety applications.And in the low GPS coverage area,GPS positioning performance will decline or even failure.Currently,Cooperative Positioning(CP)can be used for making the performance of relative positioning among vehicles more accurate in VANET.Considering the advantages of Ultra-wideband(UWB)technology in distance measurement and location,and the application of UWB technology for ranging and positioning become more mature,a vehicle cooperative positioning method based on UWB/GPS is proposed firstly.And then focuses on the research and analysis of the relative positioning between vehicles by using the UWB/GPS tightly-couple cooperative positioning method.The experimental results show that the relative positioning performance of the vehicles obtained by this method is obviously better than that of the vehicle location method based on GPS double difference.Secondly,a new UWB/IMU/GPS tightly-couple vehicle cooperative positioning method is proposed to solve the problem that the GPS receives can't obtain enough GPS signals in low GPS coverage area.The information sharing between vehicles is realized by UWB ranging communication module,and the relative position estimation of vehicles is realized by information fusion of GPS measurement results,IMU measurement values and UWB-based vehicle ranging results.In the experiment,the method is studied from two aspects: full GPS coverage and low GPS coverage,and experimental results show that the UWB/IMU/GPS tightly-couple cooperative positioning method can effectively improve the relative positioning performance between vehicles in VANET.