【正文】 se is a typical. Therefore, to increase the ability of the car after depending on and developing the back of my car detection of radar bee obstacles back research topic in recent years. In this paper the reverse radar warning system design is mainly directed against the car back to the rear of the car and people can39。系統(tǒng)設計中采用了模塊設計思想，簡化了調試工作量，最終很好完成了超聲波測距倒車雷達系統(tǒng)的硬件設計、軟件設計及系統(tǒng)調試。本文介紹了基于 AT89C51 單片機的超聲波測距器，其由超聲波發(fā)射模塊、信號接收模塊、單片機處理模塊、數碼顯示以及聲光告警顯示模塊等部分組成。工作時，超聲波發(fā)射器不斷發(fā)射出一系列連續(xù)脈沖，給測量邏輯電路提供一個短脈沖。本文設計的倒車雷達預警系統(tǒng)主要是針對汽車倒車時人無法目測到車尾與障礙物體的距離而設計開發(fā)的。倒車時，駕駛員疲于前瞻后顧，很容易就發(fā)生追尾等碰撞事故。遼寧科技大學本科生畢業(yè)設計（論文） 第 I 頁 基于單片機的超聲波倒車雷達系統(tǒng)設計 摘要 隨著我國汽車產業(yè)的高速發(fā)展，我國開始進入私家車時代，汽車的數量逐年增加，造成公路、街道、停車場、車庫等越來越擁擠。汽車駕駛員越來越擔心車的安全了，其中倒車就是一個典型。因此，增加汽車的后視能力，研制汽車后部探測障礙物的倒車雷達便成為近些年來的研究熱點。該系統(tǒng)將微計算機技術與超聲波的測距技術、傳感器技術等相結合，可檢測到汽 車倒車中，其障礙物與汽車的距離，通過 LED 數碼管顯示距離，并根據障礙物與車尾距離遠近實時發(fā)出報警等級。最后由信號處理裝置對接收的信號依據時間差進行處理，自動計算出車與障礙物之間的距離。文中運用理論分析、計算機仿真等研究手段，完成了倒車測距儀硬件和軟件的設計，并在測距算法上進行了改進，使測距速度更 快。 關鍵詞： 汽車倒車測距儀；超聲波； AT89C51 遼寧科技大學本科生畢業(yè)設計（論文） 第 II 頁 DESIGN OF ULTRASONIC VEHICLE REVERING SYSTEM WITH ULTRASONIC BASEDON MCU Abstract With the rapid development of China39。t visual obstacle the distance of the object and the design and development. This system makes the bination of the puter technology and the ultrasonic ranging technology, the sensor technology, etc. It can detect the car back to the obstacles and the automobile distance, through the LED shows distance,and according to the obstacle and thetailstock which far and near sends out realtime warning work, ultrasonic transmitters continuously launch a series of continuous pulse, to logic circuit provides a short pulses. Finally by signal processing device of received signal processing according to the time, calculating the distance between the car and the obstacles automatically. This paper introduces the ultrasonic range finde r based on AT89C51. It consists of ultrasound module, the signal receiving module, SCM processing module, digital display and sound and light alarm display module paper using theoretical analysis, puter simulation research tools, and pleted the reverse rangefinderdesign of hardware and is something improved in the measure programme for measure quickly. A modular design concept was used at the process of 遼寧科技大學本科生畢業(yè)設計（論文） 第 III 頁 designing the system, it simplifies the debugging workload. Ultimately, hardware design, software design and system debugging about the ARR was pleted very well. KEY WORDS： Automobile Reversing range finder； Ultrasonic Computer Simulation； AT89C51 遼寧科技大學本科生畢業(yè)設計（論文） 第 IV 頁 目 錄 1 緒論 .......................................................................................................................... 1 選題背景 ............................................................................................................. 1 設計意義 ............................................................................................................. 1 目前國內倒車雷達的發(fā)展概況 ......................................................................... 1 當前存在的問題 ................................................................................................. 3 2 總體設計方案 ....................................................................................................... 4 模塊構建 ............................................................................................................. 4 超聲波測距原理 ................................................................................................. 5 超聲波特點 ......................................................................................................... 5 系統(tǒng)方案選擇 ..................................................................................................... 7 超聲波傳感器 ..................................................................................................... 8 超聲波傳感器的原理及結構 ....................................................................... 8 超聲波傳感器的頻率特性 ....................................................................... 10 3 系統(tǒng)的硬件設計 ................................................................................................ 12 系統(tǒng)總體方案設計 ............................................................................................ 12 AT89C51 單片機簡介 ........................................................................................ 12 電源部分的設計 ............................................................................................... 16 控制電路 ........................................................................................................... 17 溫度補償電路 ................................................................................................... 17 超聲波發(fā)射和接收電路 ................................................................................... 19 超聲波發(fā)射部分 ......................................................................................... 19 超聲波接收電路 ......................................................................................... 20 LED 顯示模塊 ................................................................................................... 23 語音實時播報電路 ........................................................................................... 23 4 系統(tǒng)軟件設計 ..................................................................................................... 26 遼寧科技大學本科生畢業(yè)設計（論文） 第 V 頁 軟件設計要求 ................................................................................................... 27 超聲波測距算法設計 ....................................................................................... 27 主程序 ...............................................................................................