【正文】 本科學(xué)生畢業(yè) 設(shè)計(jì) 基于超聲波的汽車防撞系統(tǒng)設(shè)計(jì) 系部名稱： 汽車 與交通工程學(xué)院 專業(yè)班級： 車輛工程 B067班 學(xué)生姓名： 齊國棟 指導(dǎo)教師： 呂德剛 職 稱： 講師 黑 龍 江 工 程 學(xué) 院 二 ○一○ 年 六 月 The Graduation Design for Bachelor39。s Degree The Design of The Automotive Anticollision Systen Based on The Ultrasonic Department： Automotive Engineering Specialty： Vehicle Engineering Class:B067 The Student39。s Name: Qi Guodong Supervisor： Lv Degang Titles： Lecturer Heilongjiang Institute of Technology 202206Harbin 黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì) I 摘 要 近年來我國高速公路追尾碰撞事故頻繁發(fā)生，而車載追尾碰撞預(yù)警系統(tǒng)在解決高速公路行車安全中具有良好的前景，因此引起了研究人員的廣泛關(guān)注。 根據(jù)超聲波測量距離系統(tǒng) ， 給出了汽車測距防撞報(bào)警系統(tǒng)的設(shè)計(jì)。該系統(tǒng)能在汽車行駛以及倒車過程中自動(dòng)檢測 ， 出汽車與最近障礙物之間的距離 ( 或行車中的車距 ) 并通過 L E D 顯示出來， 當(dāng)?shù)竭_(dá)極限距離時(shí) ． 系統(tǒng)能發(fā)出聲光報(bào)警． 進(jìn)而提醒司機(jī)雌防撞車。 在公路、街道、停車場、車庫等擁擠、狹窄的地方倒車時(shí)，駕駛員既要前瞻，又要后顧，稍微不小心就會(huì)發(fā)生追尾事故。據(jù)相關(guān)調(diào)查統(tǒng)計(jì)， 15％的汽車碰撞事故是因倒車時(shí)汽車的后視能力不良造成的。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?yán)走_(dá)便成為近些年來的研究熱點(diǎn)。安全避免障礙物的前提是快速、準(zhǔn)確地測量障礙物與汽車之間的距離。為此，設(shè)計(jì)了以單片機(jī)為核心，利用超聲波實(shí)現(xiàn)無接觸測距的倒車?yán)走_(dá)系統(tǒng)。 超聲波一般指頻率在 20 kHz 以上的機(jī)械波，具有穿透性強(qiáng)，衰 減小，反射能力強(qiáng)等特點(diǎn)。工作時(shí)，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(gè)短脈沖。最后由信號處理裝置對接收的信號依據(jù)時(shí)間差進(jìn)行處理，自動(dòng)計(jì)算出車與障礙物之間的距離。超聲波測距原理簡單，成本低，制作方便，但其傳輸速度受天氣影響較大，不能精確測距；另外，超聲波能量與距離的平方成正比衰減，因此，距離越遠(yuǎn)，靈敏度越低，從而使超聲波測距方式只適用于較短距離。目前，國內(nèi)外一般的超聲波測距儀，其理想的測量距離為 4～ 5 m，因此大都用于汽車倒車?yán)走_(dá)等近距離測距中本文根據(jù)聲波在空氣中傳播反射原理，以超聲波換 能器為接口部件，介紹了基于 STC89C52 單片機(jī)的超聲波測距器。該設(shè)計(jì)由超聲波發(fā)射模塊、信號接收模塊、單片機(jī)處理模塊、數(shù)碼顯示以及聲光告警顯示模塊等部分組成，文中詳細(xì)介紹了測距器的硬件組成、檢測原理、方法以及軟件結(jié)構(gòu)。超聲波發(fā)射模塊中采用 555 定時(shí)器構(gòu)成的時(shí)基電路，接收電路使用 SONY 公司的 CX20226A 紅外檢測專用芯片，該芯片常用于 38kHz 的檢波電路，文中通過對芯片內(nèi)部電路的仔細(xì)分析，設(shè)計(jì)出能夠成功對 40kHz 超聲波檢波的硬件電路，并且增益可調(diào)，與傳統(tǒng)超聲波檢波電路相比，電路變得精簡，調(diào)試變得相對容易 。測距器使用數(shù)碼管顯示目標(biāo)物的距離。 關(guān)鍵詞： 汽車防撞報(bào)警系統(tǒng)； 單片機(jī)； STC89C52； 超聲波；測距 黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì) II ABSTRACT The accident of automobile rearend collision has taken place frequently in recent years， and rearend collision warning system has good use in improving expressway traffic safety， so the warning system has been paid more attention in the world. The vehicle collision avoidance alarm apparatus system was introdued according to the ultrasonic measurement distance’s system . The system can automaticanlly xeamine the distance between the back and the nearest obstacle ( or the distance among cars ) whicwould be demonstarted through LED that when it arrives the limit distance ,the systemb can send out the warning and reminds the driver for preventing the vehicle colliding . The experimental results showed that , the system illustrates a good prospect of application and xetension Highways, streets, parking, garage and other crowded places narrow reverse, the driver should not only forward but also looking back, a little rearend careless accidents can occur. According to related statistics, 15% of motor vehicle collisions when the vehicle is reversing, as the capacity of the latter caused by after the increase of motor vehicles as the ability to detect obstacles on the development of the rear of the car reversing radar has bee the research hotspot in recent years. Security to avoid obstacles on the premise that the rapid and accurate measurement of obstructions and the distance between motor vehicles. To this end, the design of a singlechip microputer as the core, the use of ultrasonic ranging to achieve noncontact reversing radar system. Generally refers to ultrasonic frequencies above 20 kHz mechanical waves, with perating, and attenuation of small, reflecting the ability and so on. Work, the ultrasonic transmitter continuously emits a series of consecutive pulses to the measurement of logic circuits to provide a short pulse. Finally, signal processing devices based on the received signal for processing the time difference, automatic calculation of turnout and the distance between obstacles. Ultrasonic Ranging simple, low cost, easy production, but the transmission speed by a larger weather can not be precise range。 In addition, the ultrasonic energy and the attenuation is directly proportional to the square of the distance, the farther the distance, the lower sensitivity and thus Ultrasonic Ranging way so that only apply to a shorter distance. At present, ultrasonic range finder at home and abroad in general, the ideal distance of the measurement 4 ~ 5 m, thus 黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì) III reversing radar are used in cars, such as close range in this paper, according to the spread of sound waves in air reflection to ultrasonic transducer interface ponents, based on MCU STC89C52 ultrasonic rangefinder. Designed by the ultrasonic transmitter module, receiver module, singlechip processing module, a digital display and alarm sound and light display module, such as parts, the text in detail the range of hardware devices, detection theory, methods and software architecture. The use of ultrasonic transmitter module consisting of 555 timebase timer circuit, receiving circuit using the SONY pany dedicated CX20226A infrared detecting chip, the chip used in the detector circuit 38kHz, the text of the chip through the careful analysis of the internal circuit design can successfully 40kHz ultrasonic detection of hardware circuitry and adjustable gain, and pared to conventional ultrasonic detection circuit, the circuit has bee streamlined and easier to debug. The use of digital rangefinder display the distance between objects. Key words： Automotive anticollision alarm system。 Singlechip。 STC89C52。 Silent Wave。 Measure Distance 黑龍江工程學(xué)院本科生畢業(yè)設(shè)計(jì) 目 錄 摘 要 .......