Study On Embedded On-board Information Equipment

The traffic congestion has become the bottleneck, which restricts the development of the urban city all over the world. It not only causes the enormous losing, but also builds the traffic accident, environment pollution, and energy waste. Up till now, the Intelligent Transportation Systems (ITS), which mainly use the information technology, are considered as one of the best ways to solve the traffic problems of the urban city. As the key component of ITS, the Urban Traffic Flow Guidance System can relieve the congestion, reduce the accident rate and environment pollution, increase the efficiency of the transportation, with the assistance of the real-time traffic information. The on-board information equipment is the key part of the traffic flow guidance system. With the on-board information equipment, the driver can avoid the traffic congestion based on the real-time traffic information and the optimal path. From other point of view, the usage of the on-board equipment promotes the traffic flow assignment once more, which achieves the final aim of the traffic flow guidance system. Based on the national tenth five years key scientific and technological difficulties to be tackled "R&D of ITS Key Technology and Demo Project"-item eight "R&D of On-board Information Equipment", this paper mainly study the key theory and implemental technology of the on-board information equipment. In chapter one, after the analysis on the reasons of the traffic jam, some ways to solve the problem, such as road and transportation infrastructure constructing, traffic control and traffic flow guidance, were summarized by the paper. The urban traffic flow guidance system is universally accepted as one of the best ways to reduce the traffic jam. According to different guidance mode, the guidance system can be divided into two classes: central guidance system and distributed guidance system. In this chapter, the two different guidance systems and some of the typical foreign traffic flow guidance are described. Then the history and R&D situation of the on-board information equipment were analyzed, and finally the study significance and contents of this paper were illuminated. The basic theory of geographic information system, gird E-map and vector E-map were stated briefly in chapter two. The geographic characteristic of the urban traffic and the necessity of using vector E-map in the on-board equipment were mainly discussed. In the condition of complex traffic environment, such as viaduct, interchange and so on, the planar vector E-map can not describe these real structures, so the 3D GIS is applied to assist route guidance in this chapter. Based on Multgen Creator, the real-time model of Chang Chun Xi Jie Fang Interchange was built. Based on the integrated consideration of the route planning, route guidance and map matching, the vector E-map was layered, abstracted and reduced error, meanwhile, the traffic limiting information, such as one-way street and turning limit, was classified and stored in the E-map. Finally in this chapter, the designing and making standard of special guidance E-map was summarized. In chapter three, the process of route planning was abstracted in the math field; some common algorithms; the reason on not direct usage of these algorithms on the on-board equipment were summed up. After the analysis of the computational capability of the hardware and the demands of the real-time guidance, the necessity of the real-time and dynamic algorithm was discussed. Based on the introduction of TC-B route planning method, the disadvantages of this method were analyzed, and the improved two-layer searching and region combining algorithm was presented. In the algorithm, the traffic limiting information was considered as one of the most important facts to influence the actual using effect of the on-board information equipment. With the study on the influence on the route guidance, the strategy of the TC-B method was discussed and the equation of the turning judgment was deduced. Finally, the implement methods of the route tracking, the offset path guidance and the 3D path guidance were created. In chapter four, on the one hand, the function analysis and planning was made, with the contrast of the foreign on-board equipment. It was divided into several function models, for example, E-map management model; GPS data receiving...