Realization Of Route Information Function In Car Navigation Systems

In modern society, with the development of socioeconomic and the popularity of cars, phenomenon of traffic jams is growing increasingly, which not only brings inconvenience for people traveling, but also affects the rapid development of socioeconomic. Urban traffic congestion has become a constraining bottleneck for the development of medium and large cities at home and abroad, which not only caused serious economic losses, but also brought in traffic accidents, environmental pollution and energy waste. Sometimes drivers just need to reach the only destination, in order to save time and vehicles fuel, they want to find a shortest path from all that can be connected to reach the destination, which is the shortest optimal path.For modern people, the Global Positioning System GPS is no longer a strange term. The GPS system was initially established for military purposes, but soon received a great deal of development in the civilian aspects. Applying GPS to vehicle navigation through commercial communications satellites turns into a vehicle-mounted navigation system (Also known as car navigation systems, can be abbreviated as CIPS). On the other hand, the traditional map is often not able to keep pace with the changes of the streets, and also difficult to recognize, which often makes people unable to obtain accurate driving instructions. So, the satellite navigation system becomes priceless which takes advantage of high-altitude satellite signals to navigate and position accurately and timely.Car navigation system is the arisen driving auxiliary equipment in recent years. As long as motorists enter the destination in car navigation system, the system will automatically calculate the most appropriate route according to the electronic map, and remind motorists drive in accordance with the calculation of routes during the driving process. Throughout the driving process, the drivers will be able to reach their destination quickly doing not have to take into account the routes.Car navigation system obtains data to determine vehicle speed and position through the wheel sensors, magnetic sensors and yaw sensors. Wheel sensors record the speed of the wheels, the generated pulse signal is used to occasionally calculate driving distance and the changes of direction. Through the voltage pulse inducted from the sensor excitation winding, magnetic sensors measure the size of the horizontal component of the geomagnetic field along the way and compare it with the size of the magnetic field of the starting point to provide compensation data on the computer. The storage capacity of electronic map can store all data of driving area, and by constant comparison of car on-board computer and storage road network data, the system can correct positioning error to determine the optimal driving path.In order to correctly process the road information sent by satellite for the driver to choose the most appropriate path, it needs to firstly make mathematical treatment such as calculus to road information, then calculate the length and compare them, and finally give the optimal path. In this paper, Floyed algorithm is selected to calculate the optimal path. And combine with car navigation systems applied in the current market, route selection and real-time intelligence capabilities was simulated in the JAVA environment.Human-computer interface is an indispensable and most important component of the car navigation system. Today, in the car navigation system, human-computer interface is "touch screen", "touch screen" is probably used hardware in human-computer interface products, is an input device alternative to some of the mouse and keyboard functions, installed on the front screen. Generally speaking vehicle car navigation system will default the current position of the car to the starting point, after users click the "touch screen" to enter a destination, based on map information stored in the electronic map, navigation system can automatically calculate the most appropriate path. The human-computer interface is a part of car navigation system, which is closely linked to route intelligence capability; it informs the best path chosen by the system to drivers. Firstly, the user inputs commands via the keyboard, after being treated by single chip microcomputer, the commands are sent to the main system, at the same time, the corresponding information are displayed on the monitor through OSD of the dedicated chip; Then, users can operate on the menu according to the monitor information, so the interaction between man and machine is formed. In this paper, the functions of human-machine interface is independently achieved by transplantingμC/OS-Ⅱto MSP430F149.The latest trend of car navigation systems is using Bluetooth wireless technology to receive signals sent from Car GPS. In this way, vehicle system only needs to receive and process satellite signals, and the display device is responsible for the storage of map and the overlap of location. So, if you have had a handheld computer, it only need to purchase a signal receiver and mapping software that Pocket PC has done as a multi-purpose machine. In fact, many mobile phones already have function of GPS, if coupled with the overlapping function of map, it can become a mobile navigation system.In most of the car navigation systems, the visual display system is used to be interface of man-machine communication. Others provide voice system that allows people to dialogue directly with the navigation system, and use voice to remind the driver when to turn, when to exit highway. Some car navigation systems can also have different language shows, that some of them can tell you the local speed limit, traffic and your average speed, and estimate your time reaching the destination.