基于單片機的汽車防撞裝置的設計

摘要
隨著我國高速公路建設的快速發(fā)展，高速公路上汽車碰撞事故頻繁發(fā)生，給國家和人民帶來重大損失。為避免高速公路上的汽車碰撞事故，本文設計了基于單片機的汽車防撞裝置，對本車前方路面情況進行持續(xù)監(jiān)視，在有險情發(fā)生前，及時發(fā)出報警信號，讓司機有足夠時間采取正確措施避免汽車碰撞事故。
根據(jù)所要實現(xiàn)的基本功能，對比當前采用的四種常用測距方法，最終選用紅外激光測距原理，建立了系統(tǒng)方案。對如何正確判別正前方目標、柵欄進行了分析，并以此為基礎，進行系統(tǒng)所需的電源、信息采集、鍵盤/顯示、語音報警等應用電路設計。為了使裝置正常工作，電源電路將+12V電壓變換后，給裝置中數(shù)字電路提供+5V電源電壓，給模擬電路提供 6V電源電壓；為保障測距精度，裝置采用高速激光器驅(qū)動電路和由兩級高速運算放大器構(gòu)成的探測放大電路。裝置里的鍵盤/顯示電路，采用串行智能鍵盤顯示控制芯片HD7279A，電路簡單、應用方便，減少對系統(tǒng)軟硬件資源的占用。

關鍵詞 ：汽車防撞； 激光測距； 單片機；語音報警
 
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
 
目錄
1緒論 1
1.1 課題研究的意義 1
1.2 國內(nèi)外研究現(xiàn)狀 2
1.3 本文研究的主要工作 5
2 激光測距原理 6
2.1 原理概述 6
2.2 影響測距精度的因素 6
2.3測距誤差分析 7
2.4 紅外激光波長的選擇 7
3 硬件電路設計 9
3.1 主控單元設計 9
3.1.1單片機介紹 9
3.1.2單片機系統(tǒng)的設計要求 10
3.1.3單片機系統(tǒng)總體方案設計 10
3.2 電源電路設計 12
3.2.1 TDA2030介紹 12
3.2.2 LM2940介紹 13
3.2.3 LM336性能特點 13
3.3 半導體激光器驅(qū)動電路設計 14
3.4 探測放大電路設計 17
3.5 計數(shù)觸發(fā)電路設計 19
3.6 測距計數(shù)電路 20
3.7 本車速度測量電路設計 22
3.8 鍵盤及顯示電路設計 25
3.9 報警電路設計 27
3.9.1 MAX4608的原理 27
3.9.2 555工作原理 27
3.9.3報警電路工作原理 28
4 軟件設計 30
4.1 主程序設計 30
4.2 距離計算處理子程序 32
4.3 速度計算子程序 34
4.4 顯示和鍵盤掃描子程序 35
4.5 閾值比較和報警模塊設計 36
結(jié)論 38
參考文獻 39
致謝 40
附錄 41