The Algorithm And Application Of Vehicle Navigation System In Sub-meter Based On BDS And GPS

With the coverage of BeiDou Satellite Navigation System(BDS)in Asia-Pacific region and the rapid development of the third generation BDS,the influence of BDS in the global positioning system is increasing,its promotion in civilian industry of China has matured.At present,satellite navigation and positioning have entered the era of multi-frequency and multi-system integration.Multi-system positioning is beneficial to increase the number of observable satellites,improve positioning accuracy,and can better cope with complex environments.However,how to integrate the space and time between different systems is one of the keys to combine.Intelligent Transportation System(ITS)is one of the most effective solutions to the current problems such as traffic jams,traffic accidents,environmental pollution and energy consumption.The vehicle navigation system is an important part of ITS and provides precise position and speed information for ITS.Therefore,using BDS to provide position and speed information for vehicle navigation system will be beneficial to BDS’s market promotion in the field of transportation.In view of the above problems,the main contents and achievements of this paper are as follows:1.The fundamental theoty of BDS/GPS combined positioning is clarified in detail.The comparison between the time system and the coordinate system is made,and the two systems are unified in time and space.The basic no-difference observation model,the single-difference observation model and the double-difference observation model of the intergration are deduced,and the sources of error and specific solutions to the satellite positioning process are analyzed.2.Researching on the key technologies in real-time dynamic positioning.According to the characteristics of embedded real-time operating system,μC/OS-Ⅱ is selected as the operating system of the development board.The practical application of the system is studied and the data transmission mode is designed.In this paper,the least squares method,the Kalman filtering and phase smoothed pseudorange are proposed,and the formula is deduced in detail.At last,the reliability of the algorithm is verified by the measured data.3.The components of the hardware in the vehicle navigation system is researched.The structure,function and characteristics of GNSS module and GPRS module are studied,then the hardware configuration is designed to meet the vehical navigation positioning.According to the structure characteristics and protocols of real-time differential data,the decoding process is designed,and the BDS observations is used for the analysis.4.Develeping the BDS/GPS pseudo-distance differential calculation software(RTD)and testing the development board platform.On the basis of comprehending and mastering the needs and purposes of software and hardware design,a software is developed with receiving satellite data,decoding,positioning and storing results in real time,and we collect data in the vehical experiment by this development board platform.The results of experiments show that the horizontal error is 0.80m in static experiment and 0.93m in dynamic experiment,which proves that the development board can basically meet the positioning accuracy of the vehicle navigation system.