The Key Technology Of Highway Driving Assistant System In Foggy Days Based On Ultrasonic And GPS

With a great increase of income in China, car, as a traffic tool, is increasingly used by people in daily life. Consequently, the problem of safety caused by driving is concerned by people gradually. In foggy days, highways are used to be shut down. In this way, the rate of traffic accident is definitely reduced. However, the waste of national property emerges at the same time. Thus, thinking out of a way that can both decreases the waste and guarantees traffic safety is what the traffic control department most concerns. With the development of micro-electronic technology and computer science, embedded system is applies in more and more fields, including the field of traffic control department. Ultrasonic, as a measure instrument, is reliable and relatively cheap. Besides, with the use of digital modulation technology in signal sending, the performance of noise immunity and safety will also be enhanced. Working with GPS, the driving assistance system will be more volatile, and can offer traffic information, for instance, highway exit, to drivers simultaneously.Under this background, the author designs a plan based on ultrasonic and GPS driving assistant system in foggy weather in which the embedded Linux system, the embedded CPU S3C2440 of Samsung, the self-invented ultrasonic digital identification range finder module, and the GPS module are used. The following parts are achieved in this thesis:1. According to the need of driving assistance system, an ultrasonic digital identification module with frequency shift keying is designed. The module is controlled by microprocessor. And the software includes two parts. In the first, the communication protocol is designed and the ultrasonic is send with communication protocol. In the second part, the signal is demodulated with the use of finite state machine, and the demodulated data is compared with original data. Also the task of distance measuring by digital reorganization is achieved finally.2. In this paper, the protocol of GPS is analyzed, and the algorithm for GPS message picking is designed. Meanwhile, with the picked information, the position and speed of car are revealed.3. Combined with ultrasonic digital identification module and GPS module, the highway driving assistance system is designed. Two ultrasonic digital identification modules are used in forward and left side path-find separately. GPS is used for positioning and measure speed. All modules are communicating with asynchronous serial port with ARM9 embedded microprocessor S3C2440. The system is scheduled with embedded linux operation system. Finally, information with QT user interfaces is outputted by this driving assistance system.