The car navigation system includes three parts: car navigation terminal, digital map, and navigation platform. Among them, the digital map and navigation platform are all served in the background, and the software and hardware environment can be free from any restrictions; the car navigation terminal (VNT) is not, because the harsh working environment and limited software and hardware conditions bring great research and development work challenge. The navigation platform is responsible for collecting, analyzing and processing (including data fusion) various road traffic geographic information collected by the traffic information collection system, and downloading it to special nodes and vehicles through communication systems (such as wireless paging). The traffic information collection system includes a fixed traffic information detection system (video, microwave, coil, laser and other traffic detectors) and a dynamic traffic detector (taking a taxi as an example. It is equipped with a car navigation system and can also be used as a vehicle). This kind of traffic information detector communicates with its center through a trunked communication network). The communication system includes two ways of wired and wireless communication, responsible for the information exchange between the vehicle and the navigation platform (integrated information platform, traffic management center), so as to achieve the information exchange between the vehicle and the road network. VNS is mainly composed of vehicle positioning module, multimedia navigation electronic map, vehicle communication module and other in-vehicle equipment. Multimedia navigation electronic maps provide the system with a variety of traffic geographic information such as geographic features, road locations, traffic rules, and infrastructure. It is based on GIS to operate and query electronic maps, including providing electronic map display, browsing, zooming and information retrieval services. The vehicle positioning module is composed of a positioning sensor and a data processor, which can provide real-time and continuous vehicle position information. In order to display the positioning information on the electronic map more accurately, map matching is required. Map matching compares the location output of the positioning with the road location information provided by the map database, and determines the current driving section of the vehicle and the exact location in the road section through an appropriate pattern matching and recognition process.

​

If the accuracy of the electronic map is very high, it will improve the overall positioning accuracy of the system and provide a reliable guarantee for route guidance. The car navigation terminal is installed with an operating system, multimedia electronic maps, geographic information systems and related software systems. They are responsible for receiving and processing information, making route planning, and helping the driver choose a suitable travel route before or during the trip. The planning results need to be realized by the route guidance function. Route guidance is a process that helps the driver to drive along a predetermined route to reach the destination smoothly. It generates appropriate real-time driving instructions, such as voice prompts, graphic displays, etc., based on the road information in the map database and the current vehicle position provided by the positioning module and the map module. In addition, in the car navigation terminal, the human-computer interaction module composed of the display, the controller and the related software system is an important part. It provides an interactive interface between the user and the vehicle-mounted terminal. The user inputs the map display, information query, route planning and other operation instructions into the terminal. The controller also uses the electronic map as the background of the vehicle location, optimal route planning results, Information required by users, such as real-time driving guidance instructions, is presented in multimedia methods such as voice prompts and visual graphics. Map matching and path planning are two important technologies of vehicle navigation terminals (VNT), a good map matching method.

It can greatly improve the positioning accuracy of the system, and the pros and cons of the path planning algorithm directly affect the navigation function of the product.