Research On Route-planning Algorithm And Design Of Sytem In Intelligent Transportation System

Along with the quick development of economy, theconflict between the quick increase in the amount of vehicles and the slowconstruction of roads becomes from bad to worse, and it restricts thecontinuable development of the society and economy badly, therefore thetransportation management department applies the modern computertechnique, communications technique, information technique and intelligentcontrol technique to the modern transportation, and a new-styletransportation system appears, we call it Intelligent TransportationSystem( ITS for short ). ITS plays a good role in the improvement oftransportation status.Vehicle Orientation and Navigation Sytem ( or Intelligent VehicleSystem ) is a main application system in the implement of ITS, androute-planning is an important component part of Vehicle Orientation andNavigation Sytem ( VONS for short ), the quality of route-planning affectsthe cost of travelling. The route-planning in VONS is a process in which aroute or some routes between origination point and destination point can beoffered for the drivers before driving or in the process of driving, andprovides a navigation for the drivers'driving. In the process of driving, themost concerned thing for the driver is how to find a most rational andoptimal route as soon as possible. So two things which the experts andscholars in the research of route-planning concern about are :â‘ realtime ofroute-planning algorithm andâ‘¡rationality and optimality ofroute-planning.This thesis talks about some research work which was done by theauthor in route-planning. The work is mainly composed of two parts. Thefirst part is about route-planning algorithm research within a restrictedsearching area, and the second part is about the design and realization of"route-planning prototype system in the city of Xi'an" Three improved algorithms are proposed by the author according to theexisting route-planning algorithms within a restricted searching area in thepart of route-planning algorithm research within a restricted searching area.They are a shortest route-planning algorithm within a dynamic restrictedsearching area, a hierarchical optimal route-planning algorithm within arestricted searching area and a multi-scale optimal route-planning algorithmwithin a restricted searching area. The shortest route-planning algorithmwithin a dynamic restricted searching area applies in the route-planning in arelatively regular road network. According to the topology structure of roadnetwork, this algorithm restricts the searching area between rectangle areawhose diagonal is the line between origination point and destination pointand the area of the ellipse's external tangent rectangle whose focuses areorigination point and destination point, and this algorithm can enhance theefficiency of route-planning in a relatively regular road network greatly.According to the hiberarchy character of roads the hierarchical optimalroute-planning algorithm within a restricted searching area divides theroads into several layers, and restricts the searching area when searching onevery layer reasonably, consequently this algorithm enhances the efficiencyof route-planning, and most of roads of the planned route are on muchhigher road network, this accords with the desire of drivers that drive onmuch better roads, and this has much higher rationality. According to themulti-scale character of road network the multi-scale optimalroute-planning algorithm within a restricted searching area restricts thesearching area when searching on road network of every scale reasonably, inthe condition of the countrywide basic multi-scale relief map database hasalready built, this algorithm does not need to build the multi-scale roadnetwork renewedly, so it has actual significance.We use the method of software engineering in the design andrealization of "route-planning prototype system in the city of Xi'an". In thebase of requirement analysis we consider the management of the GIS data,the structure of the system, work flow and the design of the system interfaceadequately. We store the GIS data in the database Oracle, and the securityand efficiency of database in the management of the GIS data exhibit adequately. The simple friendly interface makes it very convenient when theusers plan a route.The research work in this thesis is in the support of the national naturalscience foundation.