文档介绍：超声波自动测距系统设计
摘要
近年来,随着汽车产业的迅速发展和人们生活水平的不断提高,我国的汽车数量正逐年增加。同时汽车驾驶人员中非职业汽车驾驶人员的比例也逐年增加。在公路、街道、停车场、车库等拥挤、狭窄的地方倒车时,驾驶员既要前瞻又要后顾,稍微不小心就会发生追尾事故。据相关调查统计,15%的汽车碰撞事故是因倒车时汽车的后视能力不良造成的。因此,增加汽车的后视能力,研制汽车后部探测障碍物的倒车雷达便成为近些年来的研究热点。安全避免障碍物的前提是快速、准确地测量障碍物与汽车之间的距离。为此,设计了以AT89C51单片机为核心利用超声波自动测距系统提醒驾驶员在倒车时有效的避开可能对倒车造成危害的障碍物和行人,从而有效避免由于倒车造成的汽车碰撞或擦伤的经济损失和人身安全问题,具有较强的实用性。超声波是频率高于20000赫兹的声波,它方向性好,穿透能力强,易于获得较集中的声能。超声波的波长比一般声波要短,能透过不透明物质。本文在分析超声波测距系统原理的基础上,指出了设计测距仪的思路和所需考虑的问题,给出了实现超声波测距方案的软、硬件设计系统框图。
关键词:超声波,测距,倒车雷达,AT98C51单片机

DESING OF AN AUTOMATIC RANGING SYSTEM BASED ON ULTRASONIC
ABSTRACT
In recent years, with the development of automobile industry and the improvement of people's living standard, the number of cars is increasing year by year. At the same time, drivers without driving license are increasing. When reversing in the road, streets, parking, garage where is crowded and narrow, driver should be circumspect to avoid rear-end collision. According to related statistics, 15% of motor vehicle collisions are cause by the poor of motor vehicles rear view capability. Therefore, car reversing radar system e a hot research topic in recent years. Accurate measurement between the obstacle and the car can avoid obstacles. Therefore, the design that AT89C51 microcontroller is the core of the ultrasonic ranging system can remind the driver to avoid obstacles and pedestrians. This method can reduce the economic losses and improve the personal safety. Ultrasound is the sound waves which frequencies above 20,000 Hz. It has good direction, strong rating ability and the ability to obtain more focused acoustic energy. Ultrasonic wavelength is shorter than the average acoustic. And it can rate opaque material. Based on the analysis of the principle of ultrasonic ranging system, we points out the range finder design ideas and issues to be considered. we gives the realization of software and hardware design block diagram of ultrasonic ranging scheme.
KEY WORDS:Ultrasonic, Ranging, Reversing rad