Research On Lane Level Route Guidance Methods For Dynamic Vehicle Navigation System

With the development of economy and the improvement of living level, traffic congession has become a serious problem that restricted the city's development. In 2006, the traffic congession led loses of 350 billion yuan in China, which was 1.7% of GDP. Meanwhile, the traffic congession induces traffic incident, and increases pollution. In our country, the annual number of death due to traffic incident is over 100 thousends, it is the same as one person deied every 5 minutes, which is 20 times higher than USA in the item of mortality rate per ten thousand cars. A study shows that there are six kinds of pollutants related directly or indirectly to the emission of vehicle from the nine factors of air pollution. We know that there are many factors can lead to traffic congession, and insufficiency of road capacity and the excessive growth of vehicles are the two key factors among them. Today, the vehiclel increasing rate is about 20%, the increasing rate of urban road network can not fulfill the demand of vehicle increasing rate. So if we only ues the method of enhancing the new roads construction, we can not solve the problem of urban traffic congession at all.The intelligent transportation systems were known as the best method to solve the problem of traffic congession all over the world. By the use of ITS, we can decease traffic congession and oil burning, and improve traffic safey. In China, the study on ITS began at the late 19th century, the navigation devices sold on the market are mainly with simple functions by the comparation with the navigation devices overseas, they belong to the second generation of navigation product. For the use of 2D e-map and abstraction of road network, the navigation devices almost can not guide the route to the lane level, which will lead the attention distracted from driving. So it is easy to cause traffic incident. In the third generation, most navigation devices load 3D e-map, the road network is indicated as the real world, the road segment includes: lanes, road markings, road signs, vehicle type restriction, speed limited, and etc. In order to guide the vehicle according with the real traffic condition, the guidance indication should specify to the lane level. It is valuable and theoretical to study on the lane level guidance method for improving safety, practicability and advantage of the vehicle navigation system.The lane level guidance method was mainly researched in this paper, the main content include: lane level guidance method based on 2D e-map and lane level guidance method based on 3D e-map. The followings are the main methods:(1) Lane level navigation e-map technologyThe lane level navigation e-map is different with the common navigation e-map; the lane is used as the minmum traffic element. The design of data organization and network topology should base on the demand of lane guidance. By the consideration of international navigation e-map standerd and Chinese actual conditions, the lane level navigation e-map was studied by the ways of road network abstract and traffic information indication. The increasing updating and dynamic topology technology for the e-map was also studied in this paper. Meanwhile, for the development trend of the third generation navigation device, the design method of 3D navigation e-map was studied in this paper, especially the modeling method of complex traffic environment. A 3D e-map was built by the data from XiJiefang interchange of ChangChun China.(2) High accurate vehicle locating technologyGPS is one of the widest used locating technologies all over the world, the 3D coordinates, speed and direction of the moving object can be delivered from GPS receiver. But as we known that the accuracy of GPS receiver is inflaunced by many environmental factors, such as tunnel, high buildings, and avenue, for the lack of satellite's signals, the GPS receiver would fail to get the loacation with high accuracy. GPS accuracy can be significantly improved with additional data, possibly from multiple sources, and especially from multiple receivers. In this paper, a non-linear GPS/DR data fusion algorithm based on an improved ensemble Kalman Filter. In order to improve the accuracy of vehicle locating more, the combination of GPS and DR data fusion technology and virtual differential GPS technology was presented. The accuracy of vehicle locating was improved form 20 meters to 3 meters by the use of the methods presented in this paper.(3) Lane level map matching technologyFor the errors in navigation e-map and locating devices, it should cause bias if we use the raw GPS coordinats to display the vehicle's location on e-map. Map matching technology is the perfect method to slove the problem, so in this paper, a new map matching method was presented by the consideration of the inflaunced factors. The map matching method includes two steps, road level matching and lane level matching. The collision detection technology and height aiding technology were implemented in the process of lane level matching to ensure the precision and stablilty of lane level map matching.(4) Lane level optimal path algorithmLane level optimal path algorithm is one of the factors that inflaunce the practicality of lane level guidance. Lane level optimal path algorithm is much more complex than the common optimal path algorithm for many reasons, such as computational complexity and traffic information complexity. In order to ensure the real time of lane level guidance, two effective optimal path algorithms were present by the methods of road network optimization and data structure design. Based on the real road network of Changchun City, the algorithms were tested, and the hardware and software interface of lane level route guidance was designed and developed.In this paper, there are seven chapters. Chapter one and two include background, significance, research methods and some basic theory of vehicle navigation system. The key technologies include lane level navigation e-map technology, GPS/DR data fusion technology, VDGPS technology, lane level map matching technology and lane level optimal path algorithm from chapter three to chapter six. Chapter seven is the summery of the paper.The aim of this paper is to implement the function of lane level route guidance, many relted key technologies were studied, and all of the key technologies were integrated and implemented throught lane level guidance route software. The methods present in this paper were proved useful and advanced by the experiment.