倒车辅助系统设计.docx
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倒车辅助系统设计
哈尔滨工业大学华德应用技术学院毕业设计
目录
摘要·························································································I
Abstract·················································································II
第1章绪论·············································································1
1.1课题研究的背景和意义·····················································1
1.2国内外倒车雷达发展现状··················································1
第2章主要元器件介绍······························································3
2.1单片机AT89C51介绍························································3
2.1.1AT89C51的功能描述················································3
2.1.2AT89C51的主要特性················································4
2.2超声波传感器·································································5
2.2.1什么是超声波·························································5
2.2.2超声波传感器特性···················································5
2.2.3压电式超声波传感器················································8
2.2.4超声波传感器应用···················································9
第3章倒车雷达原理································································10
3.1超声波测距原理·····························································10
3.2总体设计方案································································11
第4章单元电路说明································································14
4.1超声波发射电路····························································14
4.2超声波接收电路····························································14
4.3电源电路·····································································14
4.4语音播报及外围电路······················································15
4.5报警电路·····································································15
4.6单片机复位电路设计······················································16
第5章系统软件设计································································18
5.1系统程序总框图····························································18
5.2主要编程设计·······························································18
第6章调试············································································22
第7章误差分析······································································24
结论····················································································26
致谢····················································································27
参考文献················································································28
1
哈尔滨工业大学华德应用技术学院毕业设计
摘要
倒车雷达是汽车泊车或者倒车时的安全辅助装置，能以声音或者更为
直观的显示告知驾驶员周围障碍物的情况，解除了驾驶员泊车、倒车和起
动车辆时前后左右探视所引起的困扰，并帮助驾驶员扫除了视野死角和视
线模糊的缺陷，提高驾驶的安全性。
本设计利用ATMEL公司的AT89C51
单片机、超声波传感器测距实现超声波倒车雷达。
关键词：
单片机
测距
超声波
倒车雷达
2
哈尔滨工业大学华德应用技术学院毕业设计
Abstract
Back-draftradaristhesafetyandassistantdeviceswhenparkingor
reversingavehicle,itcantelldriverscircsaboutthearoundbarrierwithvoice
oramoreintuitivedisplay,releasethesurroundedvisitpuzzlefromdrivers
whenparking,reversingandstartvehicles,andtohelpdriverscleanoffdead
endsandthelimitationofvisionblur,improvethesecurityofdriving.Itis
usedthatsingle-chiptehnologyultrasonicrangingandsensortechnologyinthe
system..UsingSingleChipAT89C51ofATMELandUltrasonicSensor
measuredistancetoachieveUltrasonicBack-draftRadar.
KeyWords：
MCU
radar
measuringdistance
ultrasonicsensor
back-draft
3
哈尔滨工业大学华德应用技术学院毕业设计
1.1
第1章
课题研究的背景及意义
绪
论
随着国民经济的不断发展和道路交通状况的不断改善，我国汽车
保有量不断增加。
但随着汽车数量的不断增加，一系列后续问题也随
之产生。
尤其是交通安全问题。
据统计，由于车后盲区所导致的事故
在中国约占30%，因此增强汽车的后视能力是十分必要的。
据调差了解，
绝大部分驾驶员都希望有一双能够发现汽车尾部障碍物的“后视眼”
以增强倒车时的安全性，基于以上原因，汽车倒车雷达应运而生。
倒车雷达全称叫做“倒车防撞雷达”，也可以叫做“泊车辅助装
置”，是汽车泊车安全的辅助装置。
能以声音或显示告知驾驶员车后
的情况，解决了驾驶员倒车或启动汽车时前后左右探视引起的麻烦，
并帮助驾驶员解决由视觉误差引起的缺陷，提高驾驶安全性。
倒车雷
达的原理与普通雷达一样，是根据蝙蝠在黑夜里高速飞行而不会与任
何障碍物相撞的原理设计开发的。
通过感应装置发出超声波来判断前
方是否有障碍物，以及障碍物的距离、大小、形状等信息。
只不过由
于倒车雷达的体积大小和实用性的限制，目前其主要功能仅为判断障
碍物与车的距离，并作出提示。
司机在倒车时，倒车雷达也启动，在
控制器的控制下，由车尾保险杠的探头发送超声波，遇到障碍物，产
生回波信号。
传感器接收到回波信号后，通过控制器进行数据处理，
从而计算出车体与障碍物之间的距离，判断出障碍物的位置。
再由显
示设备显示并由报警装置发出警示。
从而使司机倒车时不至于撞到障
碍物。
1.2国内外倒车雷达的发展情况
经过多年发展，倒车辅助系统已经过六代技术改良。
无论是结构外观
还是技术性能都有了长足的进步。
“倒车请注意”！
想必不少人还记得这种声音，这就是倒车雷达的第
4
哈尔滨工业大学华德应用技术学院毕业设计
一代产品，现在只有小部分商用车还在使用。
只要司机挂上倒档，它就会
响起，提醒周围的人注意。
从某种意义上说，它对司机并没有直接的帮助，
不是真正的倒车雷达。
第二代“轰鸣器”这是倒车雷达系统的真正开始。
倒车时，如果车后
1.8米~1.5米处有障碍物，轰鸣器就会开始工作。
轰鸣声越急，表示车辆
离障碍物越近。
在第二代基础之上，人们又研究出了数码波段显示的倒车辅助系统。
可以显示车后障碍物离车体的距离。
如果是物体，在1.8米开始显示；如
果是人，在0.9米左右的距离开始显示。
这一代产品有两种显示方式，数
码显示产品显示距离数字，而波段显示产品由三种颜色来区别：
绿色代表
安全距离，表示障碍物离车体距离有0.8米以上；黄色代表警告距离，表
示离障碍物的距离只有0.6~0.8米；红色代表危险距离，表示离障碍物只
有不到0.6米的距离，你必须停止倒车。
第四代产品又有了一个质的飞跃，特别是荧屏显示开始出现动态显示
系统。
不用挂倒档，只要发动汽车，显示器上就会出现汽车图案以及车辆
周围障碍物的距离。
第五代产品结合了前四代的优点，采用了最新仿生超声雷达技术，配
以高速电脑控制，可全天候准确地测知2米以内的障碍物，并以不同等级
的声音提示和直观的显示提醒驾驶员。
魔幻镜倒车雷达把后视镜、倒车雷
达、免提电话、温度显示和车内空气污染显示等多项功能整合在一起，并
设计了语音功能，是目前市面上最先进的倒车雷达系统。
第六代产品就是无线倒车雷达，全新无线液晶倒车雷达，融无线连接、
倒车雷达、彩色液晶显示、BP警示音、于一体。
由于普通倒车雷达安装
时，从车后雷达主
升级会员 