汽车倒车测距仪的设计外文翻译
汽车倒车测距仪的设计
汽车倒车测距仪的设计目录摘要 (2)Abstract (2)第一章绪论 (3)1. 1 研究背景 (3)1. 2 发展概况和当前存在的问题 (4)1. 2. 1 发展概况 (4)1. 2. 2 当前存在的问题 (4)1. 3 本设计的主要内容和目的 (5)第二章系统方案相关理论 (6)2. 1 汽车倒车超声波测距系统主要功能的概述 (6)2. 2 汽车倒车超声波测距系统的原理 (7)2. 3 超声波测距系统的主要技术指标 (9)第三章硬件设计及调试 (10)3. 1 系统装置的硬件组成 (10)3. 1. 1 单片机控制系统 (10)3. 1. 2 超声波发射电路 (11)3. 1. 3 超声波接受电路 (11)3. 1. 4 LED液晶显示电路 (13)3. 2 焊接 (14)3. 3 调试过程及方法 (14)第四章软件设计及调试 (16)4. 1 系统软件设计整体介绍 (16)4. 2 系统的程序 (17)4. 3 软件调试简介 (24)第五章总结 (25)致谢 (26)参考文献 (27)汽车倒车测距仪摘要随着科学技术的快速发展，超声波在传感器中的应用也越来越广。
但就目前技术水平来说，人们可以具体利用的传感技术还十分有限，因此，这是一个正在蓬勃发展而又有无限前景的技术及产业领域。
而本文介绍的是一种可应用于倒车测距仪的超声波测距系统。
本系统采用STC89C52单片机为核心，结合发射和接受模块以及液晶显示构成整个的测距系统，该系统能够在汽车以较低的速度进行倒车的过程中，识别出车后部的障碍物，并能够测量车与障碍物之间的距离，在车辆与障碍物发生碰撞前，发出声光报警，提醒司机刹车。
倒车测距仪是用来探测车身和周围的障碍物并显示其距离，以帮助驾驶员安全倒车或停车的辅助电子设备，对驾驶员倒车的安全起到了很大作用。
因此本系统的设计具有广泛的运用价值和意义。
关键词：传感技术超声波测距运用价值AbstractWith the rapid development of science and technology, in the application of ultrasonic sensors is more and more widely. But so far the technical level, the specific use range finder technology is limited, so, it is a vigorous development and infinite prospect areas of technology and industry. And this paper is a kind of can be applied to reverse the ranger ultrasonic ranging system. The system uses the STC89C52 microcontroller as the core, combining the launch and accept modules and liquid crystal display constitute the whole range finder system, This system can be identify obstacles at the back of the car and able to measure the distance between the car and the obstacles,and before the car run into obstacles,it can give out sound and light alarm signal, remind the driver brakes,when the car reversing with a low speed ,.Reverse rangefinder is an assist electronic equipment what can used to detect the body and the surrounding obstacles and show the distance, to help the driver safety reversing or parking,It plays a large role when the drive reversing So the design of system hasbroad application value and meaning.Keyword：sensor technology ultrasonic ranging use Value第一章绪论1. 1 研究背景信息高度发达、生活快节奏的现代社会中，电子信息技术的应用随处可见，在生活中已投入使用的有：电视机、手机、电脑、先进的工业控制系统、通信雷达系统和卫星遥感系统，甚至是汽车倒车、无人侦查飞机等无一例外的不使用到电子信息技术。
汽车倒车测距仪
题目：汽车倒车测距仪目录1、课程设计目的及内容要求----------------32、设计思路及原理----------------------------33、电路设计原理图----------------------------44、程序清单及流程图-------------------------95、问题分析及解决方法----------------------146、心得体会-------------------------------------15一、设计内容及要求1、设计一个微机控制的汽车倒车测距仪，能测量并显示车辆后部障碍物离车辆的距离，同时用间歇的“嘟嘟”声发出警报，“嘟嘟”声间隙随障碍物距离缩短而缩短，驾驶员不但可以直接观察到检测的距离，还可以凭听觉判断车后障碍物离车辆距离的远近；①开机后先显示“———”，并有开机指示灯。
②CPU发射超声波1ms，然后显示60ms；即1ms+60ms为一个工作周期，等待回波，在次周期内完成一次探测。
③根据距离远近发出报警声并显示距离。
障碍物距离小于1m，距离值变化5cm更换显示，否则不更换；距离在1m以上，新值与原显示值之差大于10cm更换，否则不更换。
④用三LED位数码管显示障碍物距离2、硬件电路原理图和软件框图；3 编写控制程序，写出设计任务书（总结报告）。
4设计任务：（1）、选用8088和适当的存储器及接口芯片完成相应的功能。
（2）、用LED显示器显示电子锁的当前状态。
（3）、画出详细的硬件连接图。
（4）、给出程序设计思路、画出软件流程图。
（5）、给出地址分配表。
（6）、给出所有程序清单并加上必要注释。
（7）、完成设计说明书（列出参考文献，所用器件型号）。
二、设计原理超声波测距原理：利用发射超声波的装置向着某一方向发射一束超声波，再利用计时器计算超声波发出以及遇到障碍物反射回来的时间差来测量距离。
由声音在空气中的传播速度v=340m/s及匀速运动位移关系式：s=vt可计得声音往返距离s，则s/2就是单程距离。
毕业设计论文 外文文献翻译 超声波测距 中英文对照
毕业设计论文外文文献翻译超声波测距中英文对照The Circuit Design of UltrasonicRanging System超声波测距系统的电路设计Ultrasonic Distance Meter超声波测距仪姓名:专业: 测控技术与仪器学号: 2007071071指导教师姓名,职称,:The Circuit Design of Ultrasonic Ranging SystemThis article described the three directions (before, left, right) ultrasonic ranging system is to understand the front of the robot, left and right environment to provide a movement away from the information. (Similar to GPS Positioning System)A principle of ultrasonic distance measurement1, the principle of piezoelectric ultrasonic generatorPiezoelectric ultrasonic generator is the use of piezoelectriccrystal resonators to work. Ultrasonic generator, the internal structure as shown in Figure 1, it has two piezoelectric chip and a resonance plate. When it's two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibrationresonance, ultrasound is generated. Conversely, if the two are notinter-electrode voltage, when the board received ultrasonic resonance,it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver.2, the principle of ultrasonic distance measurementUltrasonic 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 Ultrasonic Ranging System for the Second Circuit DesignSystem is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip selection of 8751, economic-to-use, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 2. Draw only the front range of the circuit wiring diagram, left and right in front of Ranging circuits and the same circuit, it is omitted.1,40 kHz ultrasonic pulse generated with the launchRanging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, whichby the single-chip implementation of the following procedures to generate.puzel: mov 14h, # 12h; ultrasonic firing continued 200mshere: cpl p1.0; output 40kHz square wavenop;nop;nop;djnz 14h, here;retRanging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a40kHz pulse output signal, after amplification transistor T, the drive to launch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location.2, reception and processing of ultrasonicUsed to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltage-controlledoscillator center frequency of f0 = 1/1.1R8C3, capacitor C4 determine their target bandwidth. R8-conditioning in the launch of the carrier frequency on the LM567 input signal is greater than 25mV, the outputfrom the high jump 8 feet into a low-level, as interrupt request signals to the single-chip processing.Ranging in front of single-chip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port single-chip, whilesingle-chip P1.3 and P1. 4 received input IC3A, interrupted by the process to identify the source of inquiry to deal with, interruptpriority level for the first left right after. Part of the source codeis as follows:receive1: push pswpush accclr ex1; related external interrupt 1jnb p1.1, right; P1.1 pin to 0, ranging from right to interrupt service routine circuitjnb p1.2, left; P1.2 pin to 0, to the left ranging circuit interrupt service routinereturn: SETB EX1; open external interrupt 1pop accpop pswretiright: ...; right location entrance circuit interrupt serviceroutineAjmp Returnleft: ...; left Ranging entrance circuit interrupt service routineAjmp Return4, the calculation of ultrasonic propagation timeWhen you start firing at the same time start the single-chipcircuitry within the timer T0, the use of timer counting function records the time and the launch of ultrasonic reflected wave received time. When you receive the ultrasonic reflected wave, the receivercircuit outputs a negative jump in the end of INT0 or INT1 interrupt request generates a signal, single-chip microcomputer in response to external interrupt request, the implementation of the external interrupt service subroutine, read the time difference, calculating the distance . Some of its source code is as follows:RECEIVE0: PUSH PSWPUSH ACCCLR EX0; related external interrupt 0MOV R7, TH0; read the time valueMOV R6, TL0?CLR CMOV A, R6SUBB A, # 0BBH; calculate the time differenceMOV 31H, A; storage resultsMOV A, R7SUBB A, # 3CHMOV 30H, ASETB EX0; open external interrupt 0POP ACCPOP PSWRETIFourth, the ultrasonic ranging system software designSoftware is divided into two parts, the main program and interrupt service routine, shown in Figure 3 (a) (b) (c) below. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control.Interrupt service routines from time to time to complete three ofthe rotation direction of ultrasonic launch, the main external interrupt service subroutine to read the value of completion time, distance calculation, the results of the output and so on.V. CONCLUSIONSRequired measuring range of 30cm ~ 200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility. Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error. Therefore, it can be used not only for mobile robot can be used in other detection systems.Thoughts: As for why the receiver do not have the transistoramplifier circuit, because the magnification well, CX20106 integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequency.超声波测距系统的电路设计本文所介绍的三方向(前、左、右)超声波测距系统，就是为机器人了解其前方、左侧和右侧的环境而提供一个运动距离信息。
汽车检测站设计外文翻译
郑州科技学院本科毕业设计(论文)题目汽车检测站设计姓名专业09交通运输学号指导教师郑州科技学院机械工程学院二O一三年五月原文一2.1 Common System ConfigurationsAll chassis dynamometers have several key features in common. Most importantly, a means of absorbing the power output from the test vehicle’s engine is needed to allow different loads to be applied for a variety of testing procedures. Energy is transmitted to this power absorber via a direct connection to the vehicle’s wheel hubs, or through a set of rollers, which are rotated by the wheels of the test vehicle. Flywheels and/or a motoring capability may also be included if vehicle inertia is to be simulated. Descriptions of inertia simulation and the modelling of various vehicle forces are included in Chapter 3. Systems that incorporate a set of large rollers (one roller for each driven wheel) are more common in applications requiring long term running of the vehicle, in which tyre overheating can occur. Hub dynamometers are best suited to engine tuning applications which demand rapid response and minimal set-up time between tests. A common and versatile dynamometer layout consists of a single DC or AC machine mounted outside the rollers and on the same axis, as shown in Figure 2.1..Output power is most commonly absorbed by hydraulic or electric machines—also known as dynamometers—which dissipate power either as heat or electrical energy.A single unit that can perform both motoring (power output) and generating (power absorption) functions is a common feature in commercially available chassis dynamometers.All but the simplest of garage tuning dynamometers include the capacity to measure the equivalent road speed and tractive force applied at the vehicle’s wheels. Chassis dynamometers for in-depth driving cycle and vehicle mapping tests customarily incorporate many different measuring devices, which are sampled and recorded by a computer-controlled data acquisition system. Common features of interest during a dynamometer test include the exhaust emissions (such as CO, CO2, NOX and unburnt hydrocarbons), vehicle cooling water and oil temperatures, and of course tractive force and power output. Fuel consumption and air inlet flowrates may also be recorded for combustion powered vehicles, and these often require adjustment to the standard engine intake equipment. Where the system is controlled by a computer, processing power and user interfaces vary greatly. The simplest forms may consist only of a data logging function which saves information for later viewing, while more sophisticated systems incorporate digital control of the dynamometer, prompts and feedback to the operator, as well as the recording and graphical display of data. Rates of screen update, data sampling, and control signal output are dependent mostly upon the processing speed of the control computer and its associated electronics.译文一2.1常用的系统配置所有的底盘测功机有几个关键的共同特点。
毕业设计——超声波倒车测距系统设计
4.2程序编译系统简介....................................................21
第一章
本设计的超声波倒车雷达系统是以MCS-51系列的AT89C2051单片机应用为核心，基本完成了倒车雷达控制系统的基本功能，其主要由超声波发送模块和超声波接收模块组成，同时连接语音电路和显示电路，并在整个设计过程中考虑温度对超声波的影响，系统完善的解决“倒车难”的问题。
Testing(hardware design)
总计毕业设计（论文）41页
表 格3个
插图24幅
摘要
近年来，我国的汽车数量进一步增加。在公路、街道、停车场、车库等拥挤、狭窄的地方倒车时，驾驶员既要前瞻，又要后顾，稍微不小心就会发生追尾事故。因此，增加汽车的后视能力，研制汽车后部探测障碍物的倒车雷达便成为近些年来的研究热点。为此，设计了以单片机为控制核心，利用超声波检测实现无接触测距的倒车雷达系统。工作时，超声波发射器不断发射出一系列连续脉冲，给测量逻辑电路提供一个短脉冲。最后由信号处理装置对接收的信号依据时间差进行处理，自动计算出车与障碍物之间的距离。目前，国内外一般的超声波倒车雷达系统，其理想的测量距离为1m～5 m，因此大都用于汽车倒车雷达等近距离测距中。本文根据超声波在空气中传播反射原理，以超声波换能器为接口部件，设计了基于AT89C2051单片机控制的超声波倒车雷达系统。该设计由超声波发射模块、信号接收模块、多路通道选择模块、单片机处理模块及声光告警显示模块等部分组成，文中详细介绍了超声波倒车雷达的硬件组成、检测原理、测量方法以及软件结构。超声波接收电路使用SONY公司的CX20106红外检测专用芯片，该芯片常用于38kHz的检波电路，文中通过对芯片内部电路的仔细分析，设计出能够成功对40kHz超声波检波的硬件电路。
汽车倒车测距仪
石家庄铁道大学毕业设计汽车倒车测距仪的设计与实现The Design of Auto Reverse Rangefinder完成日期 2012 年 05 月 25 日毕业设计成绩单毕业设计任务书题目汽车倒车测距仪设计和实现一、主要内容单片机STC89系列利用超声波测距模块对障碍物距离检测,对超过阈值的距离报警动作。
二、基本要求1．单片机完成超声波测距。
2．实现根据不同的距离信息进行不同样式的报警。
3．使用Keil C编程,实现相关逻辑控制。
4．电路原理图设计，Protel印刷电路图设计。
5．提出系统设计框图，提出相应的解决方案。
三、主要技术指标（或研究方法）1．电压直流5V，工作电流小于500mA。
2．完成主要功能。
3．电路原理图。
4．使用说明书撰写。
四、应收集的资料及参考文献C语言开发。
关于STC89系列相关单片机开发文档。
相关传感和显示器件使用手册和接口电路。
五、进度计划第1周：开题，并完成开题报告。
第2-8 周：资料收集，文献阅读，系统设计，电路实现，程序仿真。
第9-14周：系统综合调试完成，撰写设计说明书。
第15-16周：准备参加答辩。
教研室主任签字时间年月日毕业设计开题报告题目汽车倒车测距仪设计和实现一、背景和意义安全是围绕汽车的永恒主题。
随着公路交通特别是高速公路交通的飞速发展，交通事故特别是恶性交通事故呈不断上升趋势，交通安全越来越受到广泛关注，因此世界各国在研究只能车辆自主导航技术的同时，投入大量的人力物力，致力于提高汽车行驶安全性。
随着我国经济飞速发展，越来越多的人拥有了自己的汽车，同时由泊车和倒车所引发的事故也越来越多。
因此，有助于驾驶员泊车和倒车的倒车倒车测距仪应运而生。
二、课题研究内容单片机STC89系列利用超声波测距模块对障碍物距离检测。
对超过阈值的距离报警动作。
三、课题预期目的本研究包括超声波发射和接受、液晶显示和语音播报等模块，在倒车时，汽车在智能控制器的控制下，由车尾部的超声波发生器探头发送超声波信号，当遇到障碍物时，产生回波信号，探头接受到回波信号后井控制器进行数据处理并计算出车体与障碍物之间的实际距离，然后通过显示或语音设备提示给驾驶员。
基于超声波倒车雷达 外文翻译
外文翻译毕业设计题目：超声波倒车雷达预警原文1：DISTANCE MEASURING AND MONITORING DEVICE EQUIPPED AUTOMOBILE REVERSE RADAR译文1：距离测量和监控设备装备汽车反向雷达原文2：ULTRASONIC SENSOR ASSEMBLY FOR AVEHICLE REVERSING RADAR译文2DISTANCE MEASURING AND MONITORING DEVICE EQUIPPED AUTOMOBILE REVERSE RADAR(原文1)This design relates to an automobile commutating radar, an ultrasonic sensor comprising the radar. The ordinary car commutation radar is usually installed in the rear bumper of a car. The vehicle has a commutation radar sensor, a ceramic chip in the polarization electric field, due to the reverse piezoelectric vibration of the aluminum housing and transmitting an ultrasonic signal, and receiving the reflected ultrasonic signal into an effective distance. Therefore, a driver will know that this situation is reversed in the rear of the vehicle do not have to stop looking for the front of the vehicle.A good ultrasonic sensor ultrasonic signal should be sent to a central area, produced a strong reaction in order to achieve a sensitive detection. The distance along the line of its axis with reference to Figure 5, a conventional ultrasonic sensor sensitive areas, the reception sensitivity in a test has 250 cm, and a sensitive, including 60 degree angle in the above 2 (X) cm. Thus, the conventional sensor performance has a low accuracyIn some vehicles, the most traditional ultrasonic sensor mounted in the front and rear bumpers. Vehicles of a monitor in a dashboard display, ultrasonic sensor detects an obstacle. However, with the conventional ultrasonic sensor has a sensitive wide angle, they must be installed in the end of the bumper to prevent the ultrasonic signals interfere with each other. However, the distance in each ultrasonic sensor is so large is still very low detection accuracy.In addition, when parking the vehicle, ultrasonic sensors often detect other vehicles parked next to the vehicle as an obstacle, so the driver may be a false alarm.Accordingly, the present design provides an improved ultrasonic sensors to reduce or eliminate the above problems.Summary of the designThe main purpose is to provide the design of an ultrasonic sensor sensitive to the radar has high precision long distance and a little sensitive to the angle of the car for. Other objectives, advantages and novel features of the design will become more apparent from the following detailed description together when an ultrasonic transducer assembly of the vehicle the commutation radar has an ultrasonic sensor and the two wires. A sleeve is received by the rubbermaterial and has a chamber sensor. A tapered opening that is defined in a front chamber. A wave guide cone is provided to open and close to the sensor in the center of the tapered. By using the sensor assembly, automotive radar there is a reversal of precision long detection distance in a concentrated area.The reference to the diagram, an ultrasonic sensor assembly for a car reversing radar, in accordance with the design consists of a sensor, a set, a guided wave cone, and a housing (ultrasonic sensor has a structure like traditional sensors, and two wires extending from sensors.Sleeve, usually made of rubber, there is one which is defined as the receiving sensor. A tapered shape of the opening is defined at the front and an opening formed on the lower side to prevent the ultrasonic signal reflected from the ground to cause false alarms. A flange formed on the rear of the sleeve.The definition channel for receiving signals. A rear cover is provided on the rear side of the space to encapsulate the sensor and the sleeve inside.In the assembled state shown in Figure 2, the guide wave cone installed you like bracket combination conical opening of the center of the casing and highlights. The heating wire extends the bracket backward and exit back cover. The sleeve is placed in the housing flange butt shoulder wires and heating wire extends from the back cover of the diaphragm. A pad, made of a resin or other soft material, is provided between the sleeve is An ci back cover, so the sleeve and the sensor housing can be stably received.Figure 4 illustrates a detector effect Contrast sensor and unguided wave cone, wherein the solid line illustrates the sensor wave guide cone, and the conflict lines described sensor without the guided wave taper. As shown in Figure 4, at a test frequency of about 40 kHz (35 kHz), gift of design of the sensor can be provided to an ultrasonic signal with a Federation higher than traditional sensors. Therefore, the design of detection better than traditional sensors作者：Joan Smith；Mike Howard ；国籍：USA出处：United States Patent距离测量和监控设备装备汽车反向雷达(译文1)本设计涉及一种汽车换向雷达,用一个超声波传感器组成该雷达。
汽车倒车测距仪的设计
编号：审定成绩：设计（论文）题目：汽车倒车测距仪的设计摘要随着我国经济的飞速发展，汽车的需求量急剧增加，现在家家户户拥有汽车已经成为现实。
但是随着汽车数量的增加，其引发的事故也不断的在增加。
倒车引发的汽车事故也占不小的比重，而倒车时车尾存在的盲区是其主导因素，因此解决倒车盲区是安全驾驶必须要解决的问题。
本设计采用以STC89C52单片机为核心的低成本、高精度、微型化数字显示超声波测距仪的硬件电路和软件设计方法。
整个电路采用模块化设计，由主程序、预置子程序、发射子程序、接收子程序、显示子程序等模块组成。
各探头的信号经单片机综合分析处理，实现超声波测距仪的各种功能。
在此基础上设计了系统的总体方案，最后通过硬件和软件实现了各个功能模块。
相关部分附有硬件电路图、程序流程图。
该设计通过模块的组合和软件的控制，实现了设计要求的功能，本设计在使用上面方便，成本较低，可设置最小距离，不但完成了这些功能，还达到了汽车倒车的安全指标。
【关键词】STC89C52 超声波测距仪蜂鸣器LCDABSTRACTWith the rapid development of our economy,the demand for cars has increased dramatically, and now each and every family has a car has become a reality. But with the increasing number of cars, the accidents are increasing.Reversing rear blind spot is the dominant factor and finally solved reverse dead zones be safe driving have to resolve this problem.At the core of the design using STC89C52 low-cost, high accuracy, Micro figures show that the ultrasonic range finder hardware and software design methods. Modular de-sign of the whole circuit from the main program, pre subroutine fired subroutine receive subroutine. Display subroutine modules form. SCM comprehensive analysis of the probe signal processing, and the ultrasonic range finder function. The overall system design, hardware and software are presented.The design of the control modules and software, achieve the design requirements of function. The design is easy to use, low cost and feasible to set the minimum distance. These features are not only finished, also reached the Auto reverse safety indicators.【Key words】STC89C52 Ultrasonic rangefinder Buzzer LCD目录前言 (1)一、研究背景 (1)二、研究现状 (1)三、研究方法 (2)四、本研究的主要内容与论文组织结构 (2)五、本设计研究的意义 (4)第一章主要原器件介绍 (5)第一节STC89C52单片机 (5)第二节HY-SRF05超声波模块 (9)第三节LCD1602 (11)第四节其他的电子元件介绍 (14)第五节本章小结 (15)第二章倒车系统方案的设计 (16)第一节系统整体方案 (16)第二节最小系统的设计 (17)第三节显示报警模块的设计 (18)第四节超声波测距设计 (18)第五节本章小结 (19)第三章系统硬件设计 (20)第一节超声波测距模块 (20)第二节LCD1602显示模块设计 (22)第三节LED灯和蜂鸣器的硬件设计 (22)第四节本章小结 (23)第四章系统的软件设计 (24)第一节主程序设计 (24)第二节LCD1602显示程序的设计 (26)第三节蜂鸣器分段报警程序 (27)第四节本章小结 (29)第五章系统的调试 (30)第一节硬件的调试 (30)第二节软件的调试 (30)第三节本章小结 (31)结论 (32)致谢 (33)参考文献 (34)附录 (36)一、英文原文： (36)二、英文翻译: (40)三、工程电路图 (43)四、程序 (45)前言一、研究背景随着我国经济的建设、社会的进步、人们生活水平的提高，汽车已经与老百姓的生活密不可分，已不再是奢侈品。
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汽车倒车测距仪的设计赵文龙1 苑鸿骥1 万卫强1 许光泞1 万泽亮2(1. 南昌航空工业学院测控工程系江西南昌330034 ;2. 江铃汽车集团公司江西南昌330001)摘要本文介绍了汽车倒车测距仪的功能确定、测距原理、设计方法及技术实现,介绍了汽车与障碍物间距离测量的信号处理方法。
论述了如何有效地测出并实时地显示出汽车与障碍物的距离,规定了各种不同的报警类型,对于相关类测量系统设计有一定的参考意义。
关键词超声单片机测距信号调理中图分类号TB551文献标识码:A前言随着汽车产业的发展和人们生活水平的不断提高,汽车的数量逐年增加,例如1999 年,我国的汽车年产量已突破了180 万辆,造成公路、街道、停车场、车库等越来越拥挤不堪。
汽车驾驶员越来越为车的安全担心了,其中倒车就是一个典型,在繁忙、拥挤、狭窄的地方倒车时,驾驶员即得“瞻前”,又要“顾后”,往往一不小心,就会与汽车尾部障碍物发生碰撞事件。
经过调查,对绝大部分非职业汽车驾驶员都希望有一种能发现汽车尾部障碍物的“后视眼”———倒车测距仪,因此我们设计了一种经济实惠的汽车倒车测距仪,可以解决驾驶员的“后顾之忧”。
1 汽车倒车测距仪的功能指标确定经过对许多汽车驾驶员的调查,确定主要功能指标如下:(1) 最大测距5. 00 米,最小测距0. 35 米,实时数字显示测得距离,显示分辨率0. 01 米;(2) 超过5. 00 米为溢出,仅显示小数点,当距离小于0. 35 米时,显示为0. 00 ,表示很危险;(3) 灯光报警:当距离小于0. 60 米时,报警指示灯亮;(4) 声音报警:当距离小于1. 20 米时蜂鸣器发出间隔频率为1 Hz 的Bi ⋯Bi ⋯声,当距离小于0. 90米时蜂鸣器发出间隔频率为2 Hz 的Bi ⋯Bi ⋯声,当距离小于0. 60 米时蜂鸣器发出间隔频率为5 Hz 的Bi ⋯Bi ⋯声,当距离小于0. 35 米时蜂鸣器连续发出BiBiBi 声。
2 测距原理根据声音传播过程中遇到障碍物会发生反射这一原理可以测量距离,超声波测距也是这个原理,即用超声脉冲发射和接收其回波之间的时间差来计算距离,计算公式如下:V = 331. 5 + 0. 607 T式中:V ———超声波在空气中传播速度,其单位为米/ 秒,T ———环境温度,单位为℃。
D = V ×Δt/ 2 = V ×(t1 - t0) / 2式中:D ———被测距离,单位为米,Δt ———超声脉冲发射与接收其回波的时间差,单位为秒,t1 ———超声回波接收时刻,t0 ———超声脉冲发射时刻。
利用单片机的定时器/ 计数器可以较方便地实现该测距原理,设单片机的T0 端为起始发射同步定时器(确定起点t0) ,单片机的T1 端为回波测量定时器(确定起点t1) ,单片机的P1. 0 (称F 端) 输出窄脉冲串,各端工作波形如图1 所示。
测量出t1 和t0 ,就可以算出障碍物和超声探头之间的距离。
3 技术实现3. 1 系统框图说明系统框图如图2 所示,采用AT89C2051 单片机作为智能处理部件,配有各种接口电路可实现实时时间差采样、距离运算、显示及声光报警等功能。
由于系统的一项重要任务是测量超声脉冲发射与其回波的时间间隔,故单片机与超声信号处理部分的连接端的工作时序是关键,而超声信号处理部分主要由超声脉冲发射、超声回波接收两部分构成,超声信号处理部分的工作受单片机控制的,那么单片机是怎样控制超声信号处理电路呢?图1 测量原理时序图图2 系统框图单片机需要和超声信号处理电路共同完成测量过程,一次测量的全过程定为38. 5 毫秒(见图1 所示) 。
首先通过T0 端给超声信号处理电路发出一个1. 8 毫秒的同步负脉冲信号,超声信号处理电路开始新一轮的测量过程。
单片机将此时刻定为初始时刻t0 ,而且T0 端在低电平期间还控制超声信号处理部分工作在超声脉冲发射状态。
单片机在T0 端给出同步负脉冲的同时,还通过F 端向超声信号处理电路发出16 个40 KHz 的方波(需0. 4 毫秒) ,该信号经驱动后耦合到换能器最终发射出超声脉冲串。
在T0 端的负脉冲结束时,超声信号处理部分自动转变为超声回波接收状态。
超声波在空气中传播时不会折返,仅当超声波遇障碍物后才被反射,当返回的超声波通过换能器时会转换成电压信号,如果在气温为20 ℃时,超声脉冲6. 615 米内的遇障碍产生的回波有一定强度(声压) ,经过特定电路处理后,能够在38. 5 毫秒之内获得一个触发脉冲,单片机的定时器T1 记录下该脉冲下降沿时刻t1 ,单片机根据初始时刻t0 (也称发射时刻) 和接收时刻t1 就可以算出,该距离的一半即为所测距离。
当介于6. 615 米和6. 924 米之间的障碍物产生的回波仍然有一定的强度时,应由T0 端低电平控制不允许产生触发脉冲,而超过6. 924 米以外的障碍物产生的回波的声压,应该低于允许触发的阈值,这样可以确保本次测量发出的超声脉冲不会影响到下一个测量周期的计时。
再说,由于要求的最大测距为5. 00 米,当计算出的距离超过5. 00 米时,仅显示溢出标志,不显示距离,为了确保计算的合理性,每次在发完16 个40KHz 的方波后,才启动上一个测量周期的距离计算、显示及报警处理,对上一个测量周期内未能产生对定时器T1 的触发,则按距离溢出处理。
倘若计算出的距离小于某个报警阈值,则处理相应的报警,测距在安全距离,则关闭报警。
如把超声探头安装在汽车尾部,就可测量出汽车与障碍物之间的距离。
3. 2 系统的超声信号处理部分由于汽车尾部较宽,为了有效地探测出车尾与障碍物间的距离,应在汽车尾部安装多个超声换能器,根据一般需求装2～3 个较合适,我们把倒车测距仪设计成3 个测量通道。
为了安装方便和减小系统体积,我们选用发射和接收合为一体的空气探头(换能器) 。
实际显示的汽车与障碍物之间的距离是3 个探头与障碍物之间的距离的最小值。
考虑倒车测距仪有3 个测量通道,对3 个探头采用扫描工作法,可以共用一个信号处理电路,达到降低成本的目的。
3. 2. 1 超声脉冲发射电路该部分的方框图如图3 所示,由单片机产生的40 KHz 方波电压能量有限,不能有效地推动空气探头工作,为了获得足够的能量,必须先经过反相驱动器前置驱动,再经一级发送驱动后发射出去。
通过三路模拟传输开关来控制信号送哪一个探头的发送驱动器输入端。
三路模拟传输开关需要一个3 进制脉冲分配器来控制,而脉冲分配器由单片机的T0 端信号反相后触发的。
3. 2. 2 超声回波接收电路超声波碰到障碍物会发生透射和反射,其中反射到探头的超声波被换能器变成电压信号。
由于超声波在空气中衰减较严重,探头接收到的反射波很微弱,故换能器输出的电压信号也很微弱,所以先对该电压信号进行放大,即设置了一个限幅的前置放大环节。
由于发射和接收用同一个换能器,发射时的大幅值电压脉冲会影响前置放大器的正常工作, 故这个环节除放大作用外,还有限幅作用,限幅就是为了避免大幅值的发射电压无约束地回馈到后面的电路。
图3 超声脉冲发射电路框图由于有多个探头和限幅前置放大环节组成多个接收通道,各通道电子器件参数存在差异而造成各通道不平衡,会影响测量精度。
因此,接下来就要设置一个平衡调节环节。
反射波被探头转换成电压信号后经前置放大和平衡调节环节,再通过模拟传输开关,其电压幅度还较小,又设置了二级放大器。
为了消除发射电压回馈到信号处理电路而引起单片机误计时,此时需要一个可控滤波器,它由单片机的T0 端控制,它对发射电压回馈的信号进行旁路,而对回波的接受信号无权处理,100 %向后传输。
为了减少噪声的干扰,系统中少不了带通放大装置。
反射波的强弱,与距离有很大关系。
在测量范围内的电路应有足够的增益,设置增益可调放大环节是必要的。
经上述处理的信号不能直接作为单片机内定时器T1 的触发信号,必须先包格检波,再钳位比较,这样才能形成定时器T1 的触发信号。
钳位比较器的阈值电压是变化的(由单片机的T0 端控制) ,再一次避免了因发射电压回馈信号而引起单片机误计时。
超声波接收电路框图如图4 所示。
图4 超声回波接收电路框图4 系统达到的技术指标设计工作完成后,根据电路的功能、电子器件的体积及安装位置关系,将系统电路制成两块电路板,单片机控制电路及显示报警部分做成一块电路板(显示板) ,安装在驾驶员前面;超声电压源驱动及信息处理部分做成另一块电路板(发射接受板) ,安装在汽车后部;两板之间通过一根六芯电缆相连。
3个超声探头各通过一条三芯电缆与发射接受板相连,实物照片如图5 所示。
在实验室内,气温约为20 ℃时,通过钢皮卷尺与倒车测距仪对照测量,测得数据如下表所:测量距离是以厘米为分辨率的3 位数字显示,其中,绝大部分倒车测量的数据满足±1 厘米的测量精度(在20 ℃左右) ,少部分数据的误差也在±2厘米的范围内,并且实现了提出的汽车倒车测距仪的功能及参数的要求。
达到了设计的目的。
图5 汽车倒车测距仪的实物照片尚待解决的问题是,环境气温影响测量的精度,例如, 环境气温为40 ℃时, 超声波传播的速度是355. 78 米/ 秒,环境气温为零下10 ℃时,超声波传播的速度是325. 43 米/ 秒,两者之比为1. 0933 ,实际用车场合的温度是:夏天的气温比40 ℃还高,冬天的气温比零下10 ℃还低。
超声波传播的速度的快慢之比可以达到10 %以上,故要实现较精确的测距,还需增加温度补偿。
参考文献〔1〕吴正毅,测试技术与测试信号处理〔M〕,北京:清华大学出版社,1995 ;〔2〕方佩敏,新编传感器原理·应用·电路详解〔M〕,北京:电子工业出版社,1994 ; 〔3〕王福瑞等,单片微机测控系统设计大全〔M〕,北京:北京航空航天大学出版社,1998 ; 〔4〕赵文龙,高精度可编程流量积算仪的设计〔J〕,南昌航空工业学院学报1998,15(1) :41～46 。
The Design of Telemeter for Motor Move BackwardZhao Wenlong Yuan Hongji Wan Weiqiang Xu Guangnign Wan Zeliang(Dept . of Measuring & Controlling Engineering ,Nanchang Institute of Aeronautical Technology ,Nanchang ,P. R. China 330034)Abstract : The function confirmation ,meterage distance principle ,design means and technique implementation of telemeter which is for motor move backward ate introduced. The method of signal processing of the measured distance between the motor and the obstruction ,and method to effectively measure and real time display ,the distance between the motor and the obstruction are discussed. All of the different alarm types are prescribed. They are signify ,cant for correlative kind designs of measure system.Key words : Ultrasonic ;Monolithic processor ;Meterage distance ;Signal option. CLC：TB551 Document code：APrefaceWith the auto industry development and people's living standards continue to provideHigh number of cars increases every year, for example, in 1999, China's automobile Annual output has exceeded 1.8 million, resulting in roads, streets, parking lots,Garage more and more crowded. More and more car drivers car security concerns, among them the reverse is a typical, busy, crowded,Reversing the narrow places, the driver that was "forward looking" and also "taking care of after ", often accidentally, it will collide with the car rear obstacle collision event.After an investigation, the majority of non-occupational car drivers have hope there is a hope to find car rear obstacle "post as the eye" --- back car range finder, so we designed an affordable car down car range finder, to resolve the driver's "worries."1 car parking range finder to determine the function of indicatorsAfter a survey of many car drivers to determine the main features indicators are as follows:(1) The maximum distance 5.00 m, the minimum distance 0.35 meters, real-time figures show that the measured distance, display resolution of 0.01 m;(2) over 5.00 meters for the overflow, only the decimal point, when the distanceless than 0.35 meters, the display is 0.00, indicating very dangerous;(3) Light Alarm: When the distance is less than 0.60 m, the alarm indicatorlights;(4) Sound the alarm: When the distance is less than 1.20 m when the buzzer made a frequency of 1 Hz intervals of Bi ⋯Bi ⋯sound, when the distance is less than 0.90M interval of the buzzer frequency 2 Hz of the Bi ⋯Bi ⋯sound, when distance of less than 0.60 m interval of the buzzer when the frequency of 5 Hz of Bi ⋯Bi ⋯sound,When the distance is less than 0.35 m when the buzzer sent straight BiBiBi sound。