Research Of Map Matching In Vehicle Navigation System

As the rapid development of Chinese transport system, new roads and other transport facilities are increasing. As a direction of the transport system development, vehicle navigation system is important for improving the traffic situation. The accuracy of the positioning system is crucial. Accurate routes and the vehicle location displayed on the map could be provided for drivers correctly only if the vehicle location is known accurately.How to provide drivers with real-time, accurate location of vehicles has become the focus of vehicle navigation systems. As a positioning technology, map matching is based on the high-precision road information of an electronic map. It compares the data of vehicle location or track received by the GPS receiver and the data of road information in an electronic map, and finds the road vehicles are driven on and display the vehicle location.The paper is concentrated on map matching in vehicle navigation system. First, on the basis of understanding the vehicle navigation and its modules, the concepts and basic principles of map matching are discussed in detail. After deep analysis of factors of the real-time, the robust and the accuracy of map matching, the common algorithms are studied, and the advantages and disadvantages of them are summed up. These algorithms include the projection, probability and statistics algorithm, the correlation algorithm, the algorithm based on the network topology and the algorithm based on the curve fitting. Then the algorithm of map matching based D-S evidence reasoning is introduced. In this paper, that algorithm is used to complete three courses of map matching, that is, determining the regional of error, choosing the matching section and amending the results of orientation. As for the single decision-making standard in the D-S evidence reasoning, the decision-making of Pignistic probability is introduced to improve the accuracy of road choosing. At the same time, the space topological of roads is introduced to speed up the road searching and improve the accuracy of road choosing. Different methods are designed to complete the matching of the turning sections, the parallel sections, the crossroad sections and the overpass sections. Different approaches are used for different circumstances. In this system, ZH600GPS are used to complete the testing and VISUAL GPS are used to record the information of all sampling points. The special sections with big error, such as the turning sections, the parallel sections and the overpass sections, are simulated in MATLAB 7.0 to verify the effectiveness and rationality of the algorithm. The results show that the algorithm in this paper has high matching accuracy and better adaptability in complex sections.In the end, we summarize the research work of map matching in this paper, and describe the prospect to improve the map match in the future.