【正文】 本科生畢業(yè)論文 超聲波測(cè)距系統(tǒng)的設(shè)計(jì) 畢業(yè)論文誠(chéng)信聲明 本人鄭重聲明： 所呈交的畢業(yè)論文《 超聲波 測(cè)距系統(tǒng)的設(shè)計(jì) 》是本人在指導(dǎo)老師的指導(dǎo)下，獨(dú)立研究、寫(xiě)作的成果。論文中所引用是他人的無(wú)論以何種方式發(fā)布的文字、研究成果，均在論文中以明確方式標(biāo)明。 本聲明的法律結(jié)果由本人獨(dú)自承擔(dān)。 作 者 簽 名： 指導(dǎo)教師簽名： 年 月 日 I 摘 要 超聲波是指頻率在 20kHz 以上的聲波，它屬于機(jī)械波。超聲波也遵循一般機(jī)械波在彈性介質(zhì)中的傳播規(guī)律，如在介質(zhì)的分界面處發(fā)生反射和折射現(xiàn)象，在進(jìn)入介質(zhì)后被介質(zhì)吸收而發(fā)生衰減等。正是因?yàn)榫哂羞@些性質(zhì)，使得超聲波可以用于距離的測(cè)量中。隨著科技水平的不斷提高，超聲波測(cè)距技術(shù)被廣泛應(yīng)用于人們?nèi)粘９ぷ骱蜕钪小? 系統(tǒng)的設(shè)計(jì)主要包括兩部分，即硬件電路和軟件程序。硬件電路主要包括發(fā)射電路、接收電 路、單片機(jī)電路、電源電路和顯示電路，另外還有 LCD 控制電路和復(fù)位電路等。我采用 以 AT89S51 單片機(jī)為核心的低成本、高精度、微型化數(shù)字顯示超聲波測(cè)距儀的硬件電路。 整個(gè)電路采用模塊化設(shè)計(jì)，由信號(hào)發(fā)射和接收、供電、溫度測(cè)量、顯示等模塊組成。發(fā)射探頭的信號(hào)經(jīng)放大和檢波后發(fā)射出去，單片機(jī)的計(jì)時(shí)器開(kāi)始計(jì)時(shí)，超聲波被發(fā)射后按原路返回，在經(jīng)過(guò)放大帶通濾波整形等環(huán)節(jié) ,然后被單片機(jī)接收，計(jì)數(shù)器停止工作并得到時(shí)間。溫度測(cè)量后送到單片機(jī)，通過(guò)程序?qū)λ俣冗M(jìn)行校正， 結(jié)合兩者實(shí)現(xiàn) 超聲波測(cè)距 的功能。軟件程序由主程序、發(fā)射子程序、接收子 程序、預(yù)置子程序、顯示子程序等模塊組成。它控制單片機(jī)進(jìn)行數(shù)據(jù)發(fā)送與接收，在一定溫度下對(duì)超聲波速度的校正，還有實(shí)現(xiàn)數(shù)據(jù)正確顯示在 LCD 上。另外程序控制單片機(jī)消除各探頭對(duì)發(fā)射和接收超聲波的影響。相關(guān)部分附有硬件電路圖、程序流程圖。 實(shí)際的環(huán)境對(duì)超聲波有很大的影響，如外部電磁干擾電源干擾信道干擾等等，空氣的溫度對(duì)超聲波的速度影響也很大。此外供電電源也會(huì)使測(cè)量差生很大的誤差。在設(shè)計(jì)的過(guò)程中考慮了這些因素，并給出了一些解決方案。 【 關(guān)鍵詞 】 ： AT89S51 超聲波 測(cè)距 II Abstract Is the frequency at 20kHz ultrasonic sound waves above , it is a mechanical wave . Also follow the general mechanical ultrasonic wave propagation in elastic media , such as reflection and refraction at the interface media into the media after the decay occurs , such as dielectric absorption . It is because of these properties , so that ultrasound can be used to measure the distance . With increasing levels of technology , ultrasonic ranging technology is widely used among people39。s daily work and of the system consists of two parts , namely hardware and software programs. The hardware circuit includes a transmitter circuit, a receiver circuit, the microcontroller circuit, a power supply circuit and a display circuit , in addition to the LCD control circuit and a reset circuit. I used to AT89S51 core, lowcost, highprecision, miniaturized ultrasonic rangefinder digital display hardware circuits. The entire circuit is modular in design , the signal transmission and reception , power , temperature measurement and display module. Signal amplification and detection probe launch after launch out MCU timer is started , the original way back after the ultrasound was launched , after amplification bandpass filtering plastic and other sectors, then the microcontroller receives the counter to stop working and get the time . After the temperature measurement to the microcontroller, the speed through the process of correcting a bination of both to achieve Ultrasonic Ranging function. Software program from the main program , launch subroutine receives subroutine , preset routines, subroutines and other display modules . It controls the microcontroller for data transmission and reception , at a certain temperature correction of ultrasonic velocity , as well as data on the LCD display correctly . Another procedure controls the microcontroller to eliminate the influence of the probe for transmitting and receiving ultrasonic waves . Acpanied by the relevant part of the hardware schematics, program flow . The actual environment of great influence on the ultrasonic wave , such as an external electromagic interference power interference channel interference , etc., the temperature of the air is also a great influence on the speed of the ultrasonic wave . Besides measuring the power supply also make great error of poor students . Redesign process to consider these factors , and gives some solutions. 【 Key words】 ： AT89S51 Ultrasonic wave Ranging III 目 錄 一、緒論 .............................................................................................................................. 1 課題研究的背景及意義 ............................................................................................ 1 超聲檢測(cè)在國(guó)內(nèi)發(fā)展綜述 ........................................................................................ 1 本文主要研究?jī)?nèi)容 .................................................................................................... 2 二、 超聲波測(cè)距原理與方法 ............................................................................................ 4 超聲波簡(jiǎn)介 ................................................................................................................ 4 超聲波的三種形式 ............................................................................................ 4 超聲波的物理性質(zhì) ............................................................................................ 4 超聲波對(duì)聲場(chǎng)產(chǎn)生的作用 ................................................................................ 4 超聲波傳感器介紹 .................................................................................................... 5 超聲波的測(cè)距原理及結(jié)構(gòu) ................................................................................ 5 超聲波傳感器選擇 ............................................................................................. 7 超聲波測(cè)距的原理 ............................................................................................. 7 發(fā)射脈沖波形 ..................................................................................................... 8 本章小結(jié) .................................................................................................................... 9 三、 系統(tǒng)硬件設(shè)計(jì) ........................................................................................................ 10 發(fā)射電路設(shè)計(jì) .........................................................................................................10 發(fā)射電路設(shè)計(jì)方案 ........................................................................................... 11 發(fā)射電路方案 ................................................................................................... 11 超聲波發(fā)射器的注意事項(xiàng) ................