基于单片机的汽车防撞装置的设计.rar

基于单片机的汽车防撞装置的设计

摘要
随着我国高速公路建设的快速发展，高速公路上汽车碰撞事故频繁发生，给国家和人民带来重大损失。为避免高速公路上的汽车碰撞事故，本文设计了基于单片机的汽车防撞装置，对本车前方路面情况进行持续监视，在有险情发生前，及时发出报警信号，让司机有足够时间采取正确措施避免汽车碰撞事故。
根据所要实现的基本功能，对比当前采用的四种常用测距方法，最终选用红外激光测距原理，建立了系统方案。对如何正确判别正前方目标、栅栏进行了分析，并以此为基础，进行系统所需的电源、信息采集、键盘/显示、语音报警等应用电路设计。为了使装置正常工作，电源电路将+12V电压变换后，给装置中数字电路提供+5V电源电压，给模拟电路提供 6V电源电压；为保障测距精度，装置采用高速激光器驱动电路和由两级高速运算放大器构成的探测放大电路。装置里的键盘/显示电路，采用串行智能键盘显示控制芯片HD7279A，电路简单、应用方便，减少对系统软硬件资源的占用。

关键词 ：汽车防撞； 激光测距； 单片机；语音报警
 
ABSTRACT
With the development of highway's building in our country, the car-collision on highway takes place frequently, which brings numerous losses to the property of the country and the people. To avoid car collisions on highway, based on single-chip automotive anti-collision device is introduced in this paper. The conditions of the road in front of the car can be kept watch on by this system continuously. Before the dangerous circumstance happen, a warning signal will be sent to the driver by the system in time, which can make the driver have enough time to take effective measures and avoid collisions.
According the basic function of this system , after contrasting the four familiar methods of distance measuring, finally build up a system project with the theory of red laser-based distance measuring. After analyze how to distinguish from the front target and fencing, design some application circuits, such as the power supply, information collection, keyboard/display, man sound alarm etc. To make the system work normally, power supply voltage of +12V circuit will be transformed to the device in digital circuits to provide +5V power supply voltage, analog circuits to provide power supply voltage 6V; To ensure the precision of distance measuring, the high-speed laser driving circuit and the detect-amplifying circuit constituted by two class, high-speed operational amplifiers are used in Auto adaptive cruise-control system. The serial intelligence keyboard／display control chip HD7279A is used in keyboard／display circuit of this system, which is simply and application convenience and reduce the resource consumption of software and hardware.

Keywords：Vehicle anti-collision； Laser-based distance measuring；SCM；  Voice-alert
 
目录
1绪论 1
1.1 课题研究的意义 1
1.2 国内外研究现状 2
1.3 本文研究的主要工作 5
2 激光测距原理 6
2.1 原理概述 6
2.2 影响测距精度的因素 6
2.3测距误差分析 7
2.4 红外激光波长的选择 7
3 硬件电路设计 9
3.1 主控单元设计 9
3.1.1单片机介绍 9
3.1.2单片机系统的设计要求 10
3.1.3单片机系统总体方案设计 10
3.2 电源电路设计 12
3.2.1 TDA2030介绍 12
3.2.2 LM2940介绍 13
3.2.3 LM336性能特点 13
3.3 半导体激光器驱动电路设计 14
3.4 探测放大电路设计 17
3.5 计数触发电路设计 19
3.6 测距计数电路 20
3.7 本车速度测量电路设计 22
3.8 键盘及显示电路设计 25
3.9 报警电路设计 27
3.9.1 MAX4608的原理 27
3.9.2 555工作原理 27
3.9.3报警电路工作原理 28
4 软件设计 30
4.1 主程序设计 30
4.2 距离计算处理子程序 32
4.3 速度计算子程序 34
4.4 显示和键盘扫描子程序 35
4.5 阈值比较和报警模块设计 36
结论 38
参考文献 39
致谢 40
附录 41