【正文】 rstand the cause of the low accuracy of the measurement. Firstly, the transmission speed of the acoustic wave in the air will change with the temperature. The distance and the actual distance calculated by the average velocity may have some error. The second is because the ultrasonic belongs to one kind of wave, so the diffraction characteristic of wave is of the wave. This will make the ultrasonic wave not reflected, that is not due to the wave of the object returned, but directly received the emitter due to diffraction phenomenon and changed the direction of the transmission of that part of the ultrasonic. This is the result of a blind measurement of the blind, in the measurement of the error caused by the error read while the measurement failed. Therefore, as long as adding temperature 華北科技學(xué)院畢業(yè)設(shè)計(jì)（論文） V pensation circuit, by a temperature sensor to measure temperature, the actual temperature into the calculation, can effectively avoid the error of the first kind。 Secondly, adding dual parator circuit, can effectively avoid the second type of error. The system is controlled by the AT89C52 microcontroller count as well as the transmitter and receiver of ultrasonic wave. The whole circuit uses the idea of modular design, including the display circuit, ultrasonic circuit, ultrasonic receiving circuit, temperature pensation circuit, etc.. The display circuit is mainly posed of LED digital tube, and the dynamic display is adopted. That is, all the digital control of the section of the line in parallel, through the control of the selected signal to control the light of the digital tube. Secondly, transmit circuit for ultrasonic signal which is transmitted by the main gate, and the ultrasonic probe. There are also used for ultrasonic receiving circuit, the echo filtering amplification, shaping, and finally into the microcontroller. Other circuit also includes a temperature measurement circuit for measuring the temperature of the environment, mainly by a chip directly read environmental temperature, into the microcontroller, then through query well in advance of the thermometer, current measurement environment in the actual sound velocity through this table can be, substituted into the formula for calculating the distance. The program design mainly includes: the main program, the temperature pensation procedure, the launch subroutine, the receiving subroutine and so on. Main program at system boot time will be initialized, then immediately began to temperature measurement, to obtain the temperature value and lookup table and start transmitting circuit and the beginning of time, waiting for the echo signal, and processing and filtering software began to work the peak search and calculate the distance. Temperature measurement child program is mainly according to the temperature and speed table lookup table to obtain the current velocity and substituted into the formula were calculated. The process of the realization includes the reset procedure, the sending matched ROM mands, the temperature conversion mand, etc. The realization of the measurement distance subroutine is the measurement of time, which is the core of the system. After the timer initialization, the time will start. In summary, ultrasonic probe signal through AT89C52 analysis and a series of processing and finally realize the full functionality of the high precision ultrasonic ranging system, also shows that the design of the system to meet the 基于單片機(jī)的高精度超聲波測(cè)距系統(tǒng)的設(shè)計(jì) VI actual demand, this topic research has a certain value. Worthy of note is that in order to reduce the blind spot of the measurement of the system, the dual parator circuit to deal with different distance signal (remote part of 3cm50cm close part and 50cm400cm), making precision further improved. The system has higher design precision, can be used in the reverse radar of the car, and can also be used in the intelligent robot distance identification system or other distance 3cm500cm, the precision 1cm system. Keywords: single chip microputer, high accuracy, ultrasonic, rangin華北科技學(xué)院畢業(yè)設(shè)計(jì)（論文） 第 1 頁(yè) 共 48 頁(yè) １ 緒論 超聲 波測(cè)距系統(tǒng)作為一種經(jīng)典的非接觸式測(cè)量技術(shù)，包含了電子，材料，物理等學(xué)科的知識(shí)理論，其應(yīng)用領(lǐng)域也十分的廣泛。 超聲波作為聲波的一種，有著和聲波同樣的性質(zhì)：它的產(chǎn)生來(lái)源于振動(dòng)，另外，在不同物體中的傳的速度也是不一樣的。超聲波測(cè)距傳感器在粉塵多，光線暗或有其他電磁干擾的情況下，性能幾乎不受影響，所以，現(xiàn)代社會(huì)中，許多地方都可以用到。例如：建筑施工測(cè)量，智能機(jī)器人，汽車倒車?yán)走_(dá)，油箱液位測(cè)量等。 1． 1 系統(tǒng)設(shè)計(jì)背景 在過(guò)去許多科學(xué)家的研究基礎(chǔ)之上，我們已經(jīng)知道用許多種不同的方法來(lái)測(cè)距，不再局限于傳統(tǒng)的簡(jiǎn)單的接觸式測(cè) 量器具，我們今天的電子技術(shù)正以飛一般的速度向前推動(dòng)著大量非接觸式測(cè)距儀的發(fā)展。近幾十年以來(lái)，關(guān)于非接觸式測(cè)量系統(tǒng)的研究包含以下幾類：激光，微波，紅外線及超聲波。這其中，激光的測(cè)量精度較高，但其有個(gè)很大的缺點(diǎn)，就是極易受到周圍環(huán)境的影響，而且激光測(cè)距系統(tǒng)后期的檢測(cè)和維護(hù)成本較高，所以會(huì)產(chǎn)生較高的費(fèi)用，很難推廣到日常生活和工作中去，一般用于高端專業(yè)領(lǐng)域，如軍事類。而對(duì)于微波雷達(dá)測(cè)距來(lái)說(shuō)，電路部分的制作成本就非常之高，也只用于專業(yè)領(lǐng)域，如軍事和工業(yè)類。紅外線測(cè)距雖然造價(jià)便宜，但其不能達(dá)到高精度，且方向性不好。另外 ，紅外線傳播速度為 3 108米 /秒，速度之快，相較于超聲波在普通情況下的速度來(lái)說(shuō)，紅外線是超聲波的八十多萬(wàn)倍。因此，利用超聲波測(cè)距能大大增加時(shí)間（同樣的距離下），使得測(cè)量更容易，誤差更小。 超聲波測(cè)距系統(tǒng)的優(yōu)勢(shì)在于： (1)可以用于空氣中，液面下和固體內(nèi)等傳播介質(zhì)中測(cè)量，應(yīng)用靈活； (2)不易受光影響，在黑暗及煙霧環(huán)境下都可使用，不易受電磁場(chǎng)影響，使人可以遠(yuǎn)離這些惡劣工作環(huán)境； (3)制作起來(lái)不復(fù)雜，該成品預(yù)計(jì)價(jià)格不貴，而且體積不大，還非常容易集成； 由于超聲波測(cè)距系統(tǒng)具有以上這些特點(diǎn)而被廣泛的應(yīng)用。隨著現(xiàn) 代電子技術(shù)的發(fā)展，超聲波測(cè)距技術(shù)在汽車制作，國(guó)防安全，工業(yè)制造及日常生活中都隨處可見(jiàn)。目前的系統(tǒng)主要采用單片機(jī)微核心，結(jié)合溫度補(bǔ)償電路等模塊組成，由于計(jì)時(shí)的精確度和電基于單片機(jī)的高精度超聲波測(cè)距系統(tǒng)的設(shè)計(jì) 第 2 頁(yè) 共 48 頁(yè) 路的影響，現(xiàn)有超聲波的測(cè)量區(qū)間大致在 米到 20米之內(nèi)，誤差為毫米級(jí)，存在幾十厘米的盲區(qū)。綜上，超聲波測(cè)距系統(tǒng)應(yīng)用廣泛，為了滿足未來(lái)技術(shù)參數(shù)的精度需求，我們需要在高精度方向做出深入研究，解決這個(gè)技術(shù)難題以面對(duì)更加高的市場(chǎng)需求 ,因此這項(xiàng)技術(shù)的研究將有重大的意義。 1． 2 國(guó)內(nèi)外研究現(xiàn)狀 首先，從國(guó)外來(lái)看，最先的研究記錄是 18世紀(jì) 70年代的科學(xué)家高爾頓所做的氣哨實(shí)驗(yàn)，這是我們?nèi)藗冇惺芬詠?lái)的第一次通過(guò)實(shí)驗(yàn)產(chǎn)生的高頻聲波，后來(lái)的 30 年內(nèi)，超聲波的概念仍舊很少有人知道，再加上那時(shí)的技術(shù)方面的達(dá)不到要求，對(duì)超聲波的研究產(chǎn)生了難以逾越的鴻溝。直到第一次世界大戰(zhàn)爆發(fā)，期間關(guān)于超聲波的研究漸漸地被人們所看重。一個(gè)叫做朗之萬(wàn)的德國(guó)科學(xué)家用了晶體傳感器對(duì)超聲波進(jìn)行發(fā)射和接收，這項(xiàng)研究是在水下進(jìn)行的，且只能接頻率相對(duì)較低的超聲波。這項(xiàng)研究可以用來(lái)進(jìn)行水下通訊，另外，也可用于檢測(cè)水下物體，如水下潛艇，用于軍事領(lǐng)域。 而后，超聲波的應(yīng)用領(lǐng)域的研究也在逐漸擴(kuò)大， 到了 1928 年， Sokolve 首先提出了關(guān)于超聲波探傷的研究，即利用超聲波的特性來(lái)檢查金屬器件是否存在裂痕或者缺損。又過(guò)了兩年，另外一個(gè)科學(xué)家穆?tīng)柡郎@取了一個(gè)德國(guó)專利，這個(gè)專利是針對(duì)超聲波檢查方法的，這讓我們又看到超聲波的研究進(jìn)了一步。 1935 年， Sokolve 發(fā)表了一篇論文，詳細(xì)的介紹了他的研究結(jié)果。就是在液體的實(shí)驗(yàn)槽里進(jìn)行穿透測(cè)試，并記錄了穿過(guò)實(shí)驗(yàn)物的超聲能量。因?yàn)樵谝后w之中實(shí)驗(yàn)會(huì)很容易得觀察到波紋。德國(guó)的貝格曼在他的書(shū)《超聲波》中，比較完整的介紹了大量的超聲波的資料。這是早期的比較系統(tǒng)的資料之一，一 直被奉為經(jīng)典。 關(guān)于探傷儀的研究，最早出現(xiàn)于 Firsetone 和 Sprole 的論文中。這是超聲波的應(yīng)用最廣的一面。根據(jù)此研究基礎(chǔ)