【正文】 ret Ranging in front of singlechip termination circuit input port, single chip implementation of the above procedure, the port in a 40kHz pulse output signal, after amplification transistor T, the drive to launch the first ultrasonic UCM4 0T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port and , the working principle and circuit in front of the same location. Reception and processing of ultrasonic Used to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the opamp amplification。 nop。 output 40kHz square wave nop。s starting point to the moment when it surpasses the threshold changes with the intensity of the echo. As a consequence, a considerable error may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be cons idered as belonging to a nearer object. principle of ultrasonic distance measurement 沈陽(yáng)理工大學(xué)學(xué)士學(xué)位論文 38 Ultrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received by the receiver immediately stop the clock. Ultrasound in the air as the propagation velocity of 340m / s, according to the timer records the time t, we can calculate the distance between the launch distance barrier (s), that is: s = 340t / 2 3 Ultrasonic Ranging System for the Second Circuit Design System is characterized by singlechip microputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, singlechip selection of 8751, economictouse, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 2. 沈陽(yáng)理工大學(xué)學(xué)士學(xué)位論文 39 Figure 1 circuit principle diagram 40 kHz ultrasonic pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the singlechip implementation of the following procedures to generate. puzel: mov 14h, 12h。s arrival is based on thresholding the received signal with a fixed reference. The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the object39。s lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core ponent of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder. 2 A principle of ultrasonic distance measurement The principle of piezoelectric ultrasonic generator Piezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate. When it39。 還有許許多多給予我學(xué)業(yè)上鼓勵(lì)和幫助的朋友，在此無(wú)法一一列舉，在此也一并表示忠心地感謝！ 沈陽(yáng)理工大學(xué)學(xué)士學(xué)位論文 36 參考文獻(xiàn) [1] 李勇 .《車(chē)載單片機(jī)與車(chē)載網(wǎng)絡(luò)技術(shù)》 .第一版 .電子工業(yè)出版社 ， 2021 年 ： P57 [2] 王懿川 .《 基于單片機(jī)控制的超聲波測(cè)距報(bào)警系統(tǒng)》 .上海計(jì)量測(cè)試 ， 2021 年第5 期 ： P45~P47 [3] 陳明計(jì) .《單片機(jī)應(yīng)用設(shè)計(jì)基礎(chǔ)》 .第一版 .北京航空航天大學(xué)出版社 ， 2021 年 ：P89~P90 [4] 胡佳文 .《 51 系列單片機(jī)原理及設(shè)計(jì)實(shí)例》 .北京航空航天大學(xué)出版社 ， 2021 年 ：P79 [5] 周潤(rùn)景 .《單片機(jī)設(shè)計(jì)分析與制作》 .機(jī)械工業(yè)出版社 ， 2021 年 ： P123~P124 [6] 陳濤 .《單片機(jī)應(yīng)用及 C51 程序設(shè)計(jì)》 .第二版 . 機(jī)械工業(yè)出版社 ， 2021 年 ：P93 [7] 龔運(yùn)新 .《單片機(jī)接口 C 語(yǔ)言開(kāi)發(fā)技術(shù)》 .第一版 .清華大學(xué)出版社 ， 2021 年 ：P234~P235 沈陽(yáng)理工大學(xué)學(xué)士學(xué)位論文 37 附錄 A 英文文獻(xiàn) Ultrasonic ranging system design Publication title: Sensor Review. Bradford: 1993. Vol. 13 ABSTRACT： Ultrasonic ranging technology has wide using worth in many fields， such as the industrial locale， vehicle navigation and sonar engineering． Now it has been used in level measurement， selfguided autonomous vehicles, fieldwork robots automotive navigation， air and underwater target detection， identification， location and so on． So there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging system in hand， satisfy the request of the engineering personnel for the ranging precision， the bound and the usage， a portable ultrasonic ranging system based on the single chip processor was developed． Keywords： Ultrasound r， Ranging System， Single Chip Processor 1 Introductive With the development of science and technology, the improvement of people39。同時(shí)，我還要感謝我的寢室同學(xué)和身邊的朋友，正是在這樣一個(gè)團(tuán)結(jié)友愛(ài)、相互促進(jìn)的環(huán)境中，在和他們的相互幫助和啟發(fā)中，才有我今天的小小收獲。在我畢業(yè)論文寫(xiě)作期間，各位老師給我提供了種種專(zhuān)業(yè)知識(shí)上的指導(dǎo)和日常生活上的關(guān)懷，沒(méi)有您 們這樣的幫助和關(guān)懷，我不會(huì)這么順利的完成畢業(yè)設(shè)計(jì)，借此機(jī)會(huì)向您們 表示由衷的感激。包括溫度對(duì)聲速的影響由于時(shí)間和技術(shù)原因未能設(shè)計(jì)出來(lái)。測(cè)量距離較近，測(cè)量距離較大時(shí)，顯示的數(shù)據(jù)就會(huì)有較大的誤差。 本系統(tǒng) 設(shè)計(jì) 過(guò)程中，由于時(shí)間和能 力等多方面的原因， 本 系統(tǒng)還存在一些不足之處，有待進(jìn)一步改進(jìn)和提高。 （ 3）完成了超聲波測(cè)距雷達(dá) 軟件設(shè)計(jì)，并且調(diào)試通過(guò)， 基本實(shí)現(xiàn)了系統(tǒng)的設(shè)計(jì)目標(biāo)， 最終完成程序燒錄。 主要 研究 工作包括 : （ 1）根據(jù)文 獻(xiàn)資料了解國(guó)內(nèi)超聲波傳感器的研究現(xiàn)狀，理解各種測(cè)距原理，了解超聲波的相關(guān)知識(shí)。 沈陽(yáng)理工大學(xué)學(xué)士學(xué)位論文 34 結(jié) 論 本文針對(duì) 基于單片機(jī)超聲波倒車(chē)?yán)走_(dá)進(jìn)行了設(shè)計(jì)，提出設(shè)計(jì)方案素 。t2s2聲速可以用聲速儀測(cè)量，以驗(yàn)證理論計(jì)算的準(zhǔn)確性。有文獻(xiàn)表明，按下式計(jì)算聲速可以達(dá)到較高的精度： 在空氣中 ， tC ?? m/s； 在海水中 ， C=1450+若采用外部硬件計(jì)時(shí)電路，則計(jì)數(shù)頻率可直接引用單片機(jī)的晶振頻率，時(shí)間量化誤差更小。 (3)提高計(jì)時(shí)精度，減少時(shí)間量化誤差 如采用芯片計(jì)時(shí)器，計(jì)時(shí)器的計(jì)數(shù)頻率越高，則時(shí)間量化誤差造成的測(cè)距誤差就越小。其提高測(cè)距精度的措施下 ： (1)合理選擇超聲波工作頻率、脈寬及脈沖發(fā)射周期 據(jù)經(jīng)驗(yàn)，超聲 測(cè)距的工作頻率選擇 f=40kHz 較為合適：發(fā)射脈