摘要
倒车雷达是汽车泊车或者倒车时的安全辅助装置。该系统能够在汽车低速倒车的过程中，识别出车体后部的障碍物，并能够测量汽车与障碍物之间的距离。在车辆与障碍物发生碰撞之前，发出语音警报，提醒司机刹车。
针对汽车行业中倒车雷达现状，本文提出了一种以ARM9处理器ARM920T和Linux操作系统为软硬件平台的数据采集方案、超声波发射接收装置、语音报警模块等多模块设计，完成了对倒车系统复杂情况的判断、测距、语音报警等功能。从测试的准确行，可观性、稳定性上对可视倒车雷达系统的组成取得了新的突破。
本系统采用超声波换能器产生超声波，当超声波碰到障碍物后因阻挡而被反射，系统通过CSB40R接收，然后通过超声波的发射和接收之间的时间差而测出距离；通过语音报警系统通知司机具体的距离及危险程度。该系统的有效运用可使我们更好的避免交通事故，有效的利用高端科技为日常生活服务。
关键词：嵌入式系统; 超声波;ARM9;Linux操作系统;语音报警
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Abstract
With the development of the technology of the electronic,auto,embed and information in recent years,the embed system has been widely applied in each field.Thanks to the progress of the computer,communication and automation,especially the improvement of the embed technology,selecting a embed operating system will be a very effective thing that will improve the capability and the empolder rate,which will supply a support platform for the modernization and informatization of the industry.
In connection with the current situation of reversing radar,the paper puts forward a design of modules which is based on ARM9 processor named ARM920T and the Linux control system,which has all the functions including:ultrasonic send/incept module,alarm module of sound etc.The system call complete the functions of judgement,measure distance,audio alert and so on.The reversing radar breaks through in terms of veracity,observability,stability.
In order to produce the ultrasound the system adopts the device of ultrasonic transducer which has the feature of echoing when the ultrasonic touching the barrier.The reflected wave will be taken over by CSB40R,then ARM can test the time from sending to receiving,from which the controller call measure the distance from barrier to car.According to the judgement the controller can also alarm the driver of the distance from the barrier to the car with the dangerous circumstances.If the controller system is used effectively,it can better serve our daly life,for example it carl reduce the traffic accidents drastically.
The practicability and the actualization are emphasized in the research course.With respect to hardwares,we choose the common ones.And we also have done much work in improving and verifying the gordian technique.The practical results show that the reversing radar system with accuracy test and dependable performance will play an important role in reversing without barrier.
Keywords:Embedded System;ultrasonic;ARM9;Linux OS;Audio Alert
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目录
1 绪论 ......................................................................................................... 1 1.1课题研究的背景 ............................................................................ 1 1.2课题研究的价值和意义 ................................................................ 2 1.3 倒车雷达的发展现状和趋势 ....................................................... 2 1.3.1 倒车雷达的发展现状 .......................................................... 2 2 倒车雷达系统总体设计和关键技术 .................................................... 4 2.1 倒车雷达系统的设计思想和目标 ............................................... 4 2.2 倒车雷达系统的结构 ................................................................... 5 2.3 倒车雷达系统的关键技术 ........................................................... 6 2.3.1 超声波测距技术 .................................................................. 6 2.3.2 嵌入式系统 .......................................................................... 8 2.3.3 Linux操作系统 ................................................................... 11 3 倒车雷达系统硬件电路的设计与实现 .............................................. 13 3.1 倒车雷达系统硬件总体设计 ..................................................... 13 3.2 倒车雷达系统的硬件具体实现 ................................................. 13 3.2.1 核心板 ................................................................................ 13 3.2.2 核心板的电源电路图 ........................................................ 18 3.2.3 时钟电路及复位电路设计 ................................................ 18 3.2.4 超声波发生电路 ................................................................ 19 3.2.5 超声波接收电路 ................................................................ 22
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3.2.6 语音报警系统电路 ............................................................ 25 3.3 硬件系统的PCB板的设计原则 ................................................ 27 4 软件设计及调试 .................................................................................. 28 4.1 嵌入式Linux系统软件开发要经过5个步骤 .......................... 29 4.1.1编译和移植Boot loader ...................................................... 29 4.1.3 移植置裁剪Linux内核驱动程序的编写添加................. 29 4.1.4 文件系统(Ramdisk)的安装 ............................................... 31 4.1.5 用户空间(User)程序的开发 .............................................. 31 4.2 系统软件总体设计思路 ............................................................. 31 4.3 Linux的USB驱动程序 .............................................................. 33 4.3.1 驱动程序支持的设备 ........................................................ 34 4.3.2 注册USB驱动程序 ........................................................... 34 4.3.3 探测与断开 ........................................................................ 35 4.3.4 提交和控制urb .................................................................. 37 4.3.5 驱动模块的编译、配置和使用 ........................................ 39 4.4 超声波发射和接收部分的软件 ................................................. 39 5 总结与展望........................................................................................... 41 5.1 系统的工程实践 ......................................................................... 41 5.2 系统的创新点 ............................................................................. 42 5.3 课题展望 ..................................................................................... 42 参考文献 ................................................................................................... 43 致谢 ........................................................................................................... 46
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