111EquationChapter1Section1摘要随着社会的发展，经济的进步，越来越多的汽车涌上了街头，随之带来交通事故的增多。因此汽车防撞系统受到了跟多人的重视。而由毫米波雷达、激光雷达以及CCD立体视觉系统组成的汽车防撞系统因成本高而无法应用与普通的汽车。超声波测距系统组成的汽车防撞系统，具有成本低、受外界影响小的优点，因此研究大作用距离超声波测距系统组成的汽车防撞系统具有十分重要的意义。本文采用超声换能器组成的超声波测距系统设计实现汽车防撞系统。整个系统包括超声波发射与接收系统，单片机控制器，LED显示部分，扫描驱动部分。关键词：汽车防撞系统超声换能器大作用距离测距系统AbstractWiththedevelopmentofsocialandeconomicprogress,anincreasingnumberofcarsappearonthestreets,whichbringmoreandmoretrafficaccidents.Asaresult,vehiclecollisionavoidancesystemsarepaidgreatattentionto.Butthevehiclecollisionavoidancesystemcomposedofmillimeter-waveradar,laserradarandCCDthree-dimensionalvisualsystemaretooexpensivetobeusedinordinarycars.ThevehiclecollisionavoidancesystemusingUltrasonicRanginghastwogreatadvantages,suchaslowcostandnotsubjecttooutsideinfluence.Sothestudyofvehiclecollisionavoidancesystemcomposedofultrasonicrangingsystemissignificant.Inthispaper,thevehiclecollisionavoidancesystemcontainsultrasonicrangingsystemcomposedofultrasonictransducer.ThesystemconsistsofUltrasoniclaunchingandreceivingsystems,SCMcontroller,LEDdisplaypartandthescanningdriver.Keywords:AutomobilecollisionavoidancesystemUltrasonictransducerLargesensing-rangeDistancemeasurementsystem目录第一章绪论.....................................................................................................................11.1研究背景与课题来源...............................................................................................11.1.1各类车载测距传感器及其性能........................................................................21.1.2课题的提出........................................................................................................21.2汽车防撞系统的现状.............................................................................................41.3超声波测距系统........................................................................................................51.3.1可变阈值与回波包络检波法.............................................................................61.3.2基于互相关函数的时延估计法........................................................................61.3.3谱线分析法与自适应时延估计........................................................................61.4超声波测距与定位技术的发展概况........................................................................71.5主要研究工作及内容................................................................................................7第二章超声波发射与接收电路.....................................................................................92.1大作用距离超声波换能器.......................................................................................92.1.1超声波物理特性与换能器技术指标.................................................................92.2超声波发射电路的设计..........................................................................................112.2.1推挽变换器的工作原理...................................................................................112.2.2推挽变换器的转换效率.................................................................
