摘要随着的发展人们的生活质量越来越高，许多事物都追求方便、高效，测距在计算机、机器人等工业化的发展中都应用广泛。因为超声波是一种纵向机械波所以是直线传播并且符合反射和折射的特性。超声波传感器结构简单、体积小、经济并且方便集成化。利用超声波以一定速度定向传播等特性设计的超声波测距主要应用在建筑施工现场测量、倒车提醒等防撞系统、移动机器人定位等。超声波测距具有可靠性、精度可控、应用广、高效等优点。FPGA是现场可编程门阵列，I/O口多、能够并行运算、集成度高。常用的门电路或者是复杂组合逻辑电路都能用简单的程序实现。利用FPGA能简便控制时序的特点本文对超声波的特性设计了基于FPGA的测距系统,通过FPGA中的全局的时钟分频信号处理对超声波信号的收发有准确的控制。在一定的工作环境下，通过测量超声波往返时间已知超声波的传播速度就能计算出来与目标物的距离。关键词：超声波测距；FPGA；分频AbstractWiththedevelopmentofpeople'squalityoflifeisgettinghigherandhigher,manythingsarepursuingconvenienceandefficiency,rangingiswidelyusedinthedevelopmentofcomputer,robotandotherindustrialization.Becauseultrasoundisalongitudinalmechanicalwave,itpropagatesinastraightlineandconformstothecharacteristicsofreflectionandrefraction.Theultrasonicsensorissimpleinstructure,smallinsize,economicalandeasytointegrate.Ultrasoundranging,whichisdesignedwiththecharacteristicsofdirectionalpropagationofultrasoundatacertainspeed,ismainlyusedinanti-collisionsystemssuchasbuildingconstructionsitemeasurement,reversewarning,mobilerobotpositioningandsoon.Ultrasoundranginghastheadvantagesofreliability,controllableaccuracy,wideapplicationandhighefficiency..FPGAisafieldprogrammablegatearraywithmanyI/Oports,paralleloperationandhighintegration.,parallelcomputing,andhighintegration.Commonlyusedgatecircuitsorcomplexcombinationallogiccircuitscanbeimplementedwithsimpleprograms.ThispaperdesignsadistancemeasurementsystembasedonFPGA,whichcancontrolthetimesequenceconvenientlybyusingthecharacteristicsofFPGA.ItcancontrolthesendingandreceivingoftheultrasonicsignalaccuratelythroughtheglobalclockfrequencydivisionsignalprocessingintheFPGA.,thedistancefromthetargetcanbecalculatedbymeasuringthetimeofultrasonicroundtripandthespeedofultrasonicpropagation.Keywords:Ultrasonicranging,FPGA，Frequencydivision目录摘要Abstract第1章绪论...........................................................................................................................11.1研究目的与意义.......................................................................................................11.2国内外研究现状.......................................................................................................11.2.1无损检测技术.................................................................................................11.2.2定位和避障.....................................................................................................21.2.3回波处理方法.................................................................................................21.2.3超声波发射脉冲.............................................................................................3第2章超声波原理和超声波传感器...................................................................................32.1超声波原理...............................................................................................................32.2超声波传感器.....................................................................................
