摘要:随着我国高速公路的快速发展，私家车拥有量的急剧增加，交通事故随之频发。在这些交通事故中，汽车追尾事故是最普遍、最严重的交通事故之一。严重的汽车追尾事故给国家和个人带来巨大的财产损失，因此研究防止汽车追尾技术系统有重要的意义。目前对防止汽车追尾技术的研究报导较多，各种各样的汽车追尾预警装置也渐进入市场，但是这些预警装置还存在反应速度不灵敏，或者预警不准确等缺点，所以对防止汽车追尾技术系统的研究必须从汽车发生追尾现象的物理机制和预警系统的可靠性出发，深入探讨汽车追尾现象的物理原理，研究防止汽车追尾预警系统的安全可靠性。

目前大部分防止汽车追尾系统测车距的方式都是超声波测距或激光测距，然而这种两测距方式各有优缺点，超声波测距能在可见度较小的情况下进行，但系统的响应速度慢；激光测距方式系统的响应速度快，但是由于激光的波长较短，所以激光测距方式受天气的影响较大，因此单纯的测距方式难于提高预警系统的可靠性。基于已有防止汽车追尾系统的优缺点，论文提出了测距方式和测速方式相结合的预警方式，从而提高预警系统的可靠性。论文基于发生汽车追尾现象的物理原理，分析了发生汽车追尾现象中汽车速度、加速度以及车距等物理量间的相互关系；讨论了防止汽车追尾技术系统中激光测量车距的原理以及多普勒效应测量前面车辆速度的原理；利用单片机，设计出可靠、合理的智能防止汽车追尾系统。本论文的结论有益于新型的汽车追尾系统的研究与开发。

关键词：多普勒效应，汽车追尾，预警

Abstract:With the rapid development of China's highways, private car ownership, a sharp increase in traffic accidents resulting frequent. In these accidents, the most common rear-end accident, one of the most serious traffic accidents. Serious rear-end accident to the state and individuals huge losses, so the research system to prevent rear-end technology has important significance. Current research to prevent rear-end technology more reports, a variety of rear-end early warning devices are slowly entering the market, but these early warning devices are still insensitive reaction rate, or the shortcomings of early warning is not accurate, so to prevent rear-end technology System must occur from automobile rear-end behavior of the physical mechanisms and the reliability of early warning systems starting to study the physics of rear-end phenomenon, research to prevent rear-end collision warning system safety and reliability.

At present most of the system to prevent rear-end vehicle distance measuring means are ultrasonic ranging or laser ranging, however, its advantages and disadvantages of this two-way ranging, ultrasonic distance visibility less in circumstances, but the system slow response; laser ranging system, fast response mode, but the shorter the wavelength of the laser, the laser ranging method influenced by the weather, so a simple way of locating hard to improve the reliability of early warning systems. Based on existing strengths and weaknesses of the system to prevent rear-end, the paper put forward ranging approach and warning that combines the speed mode, thereby enhancing the reliability of early warning systems. Paper, based on a car rear-end behavior of the physical principles of the occurrence of rear-end behavior in the vehicle speed, acceleration, and cars from the interaction between physical quantities such as; discussed the technical system to prevent rear-end vehicle distance measurement principle of laser and the Doppler effect the principle of measuring the speed the vehicle in front; use of SCM, design a reliable, reasonably intelligent system to prevent rear-end. The thesis concludes benefit of new research and development of rear-end system.

Keywords: Doppler effect， car rear-end collision，warning