Research On Key Technologies Of Vehicle Navigation System

Vehicle navigation system, which belongs to the research category of the traveler information service fields in Intelligent Transportation System (ITS), is an important ITS application system in great demand.In this dissertation, the basic architecture of vehicle navigation system is built firstly. Vehicle navigation system can be divided into four functional subsystems: digital map database management subsystem, vehicle positioning subsystem, route planning subsystem, and route guidance subsystem, as well as wireless communications subsystem. The functions which each subsystem should be realized as well as the key technologies to ensure the realization of these functions are proposed.In Chapter 2, a brief development history of vehicle navigation system is reviewed and the research status quo is introduced. Based on this, we determine to focus on some key technologies that impact the practicability of vehicle navigation system currently, take the route planning subsystem, which is the weakness of the existing vehicle navigation system, as the core, and mainly study the following three items: the route planning algorithms fitting for vehicle navigation, the representation and storage structure for road network, and the calibration of road weight, where the latter two are the basis of the former one. The above three items, which will be discussed in Chapter 4, Chapter 5, and Chapter 6 respectively, consist of the principal contents of this dissertation.In Chapter 3, the application prospective and the construct mechanism of vehicle navigation system in China are analyzed comparatively deeply.In Chapter 4, the solution to the representation of road network aiming at the route planning of vehicle navigation is given. Especially, the principle to determine node is proposed, i.e., node is a 揹ecision point?or a 揷ontrol point?where the travel route may be changed. The corresponding representation methods for some special or complex cases in urban road network are given. As far as the road network is concerned, the connectivity has two layers of meanings. By means of constructing dual network, the connectivity of road network, including one-way traffic, turn restrictions at intersections, and etc., are completely described. As to the storage structure of road network, two solutions are proposed. One is to store the dual network of road network with the forward star structure, which is a compact network storage structure satisfying the needs of route planning. The other one is to straight store road network with the generalized forward star structure, which can represent turn restrictions and intersection delays.In Chapter 5, the methodologies of calibrating the road weight measured by travel time based on road impedance function model and signalized intersection delay model are proposed, and are realized and verified using a large amount of field data. The methodologies include a series of methods consisting of data collection scenario, data disposal, choosing the appropriate model, model calibration, determining the road weigh, and etc., which are feasible under the infrastructure and technical conditions in the current stage in China, and the real-time factors are also considered. In addition, the solutions are given to the calibration of the weight of other types of nodes, such as interchanges, grade crossings with turn ramp, unsignalized intersections which the main traffic has priority, and entrances/exits of urban expressway.?iii ?In Chapter 6, the experiment scenario and test problems used to verify route planning algorithms for vehicle navigation are designed. Two test problem generation algorithms, which generate large sparse random networks and rectangular grid road networks respectively, are proposed. Using these two algorithms, different kinds of test problems to verify route planning algorithms for vehicle navigation arc generated. In addltin, test problems which reflect the special and complex cases in real road network are constructed manually. On the basis of analyz...