简介:摘 要:汽车驻车手柄机构是实现整车驻车性能的重要组成部分,不仅涉及整车安全且对用户体验有较大影响。本文通过分析某车型机械驻车手柄与副仪表板干涉案例,阐述如何利用三坐标数据、数模模拟装配、CAE应力分析等工具找到故障产生的潜在原因,提出合理解决方案最终实现问题解决,提升整车驻车性能并改善用户体验。
简介:ConventionalSyntheticApertureRadar(SAR)systemscannotobtainhigh-resolutionandwide-swathilluminationareaduetothewell-knownminimumantennaareaconstraint.SinglePhaseCenterMultiBeam(SPCMB)techniquecanovercomethislimitationbyaddingspatialsamplingthroughmultiplereceiversinazimuthdirection.Unfortunately,thisapproachwillleadtoanincreaseofazimuthambiguities(interbeamambiguities),becauseeachreceivebeam’smainlobeoverlapswiththeotherones’sidelobes.ThispaperprovesthatthefrontpartofSPCMBSARsystemscanbeconsideredtobeahybridfilterbank.Therefore,theazimuthsignalcanbereconstructedandtheinterbeamam-biguitiescanbeeffectivelysuppressedbyawell-designedhybridfilterbank.
简介:ToperformthegroundtestofaspaceborneSyntheticApertureRadar(SAR)system,anechosimulatorwiththecharacteristicsofmultimode,multi-assemblage,andrealtimeisproposedinthispaper.Ahardwareplatformofthereal-timeechosimulatorbasedontheVPXbusisdesigned.Withthisplatform,real-timemulti-pointechogenerationandscenariotargetsechogenerationcanbeachievedbythereal-timesignalprocessinginFieldProgrammableGateArray(FPGA),utilizingtheparameterscalculatedbytheindustrycomputers.Furthermore,thisplatformcanoutputdifferentsignalsifitisexpandedtomulti-channels,makingitpossiblefortheassignmentofechogenerationandtestindifferentspaceborneSARmodes.ThetestresultswiththeactualSARsystemshowthatthisplatformcansatisfythesystemrequirementsandisnowusedinpractice.
简介:Fusionofsyntheticapertureradar(SAR)andforwardlookinginfrared(FLIR)imagesisanimportantsubjectforaerospaceandsensorsurveillance.ThispaperpresentsaschemetoachieveanaturalcolorimagebasedonthecontoursfeatureofSARandthetargetregionfeatureofFLIRsothattheoverallscenerecognitionandsituationalawarenesscanbeimproved.TheSARandFLIRimagesarefirstdecomposedintosteerablepyramids,andthecontourmapsintheSARimageandtheregionmapsintheFLIRimagearecalculated.Thecontourandregionfeaturesarefusedateachlevelofthesteerablepyramids.Acolorimageisthenformedbytransferringdaytimecolortothemonochromicimagebyusingthenaturalcolortransfertechnique.ExperimentalresultsshowthattheproposedmethodiseffectiveinprovidingacolorfusionofSARandFLIRimages.
简介:AnewfilteringmethodforSARdatade-noisingusingwaveletsupportvectorregression(WSVR)isdeveloped.OnthebasisofthegreyscaledistributioncharacterofSARimagery,thelogarithmicSARimageasanoisepollutedsignalistakenandthenoisemodelassumptioninlogarithmicdomainwithGaussiannoiseandimpactnoiseisproposed.Basedonthebetterperformanceofsupportvectorregression(SVR)forcomplexsignalapproximationandthewaveletforsignaldetailexpression,thewaveletkernelfunctionischosenassupportvectorkernelfunction.ThenthelogarithmicSARimageisregressedwithWSVR.Furthermoretheregressiondistanceisusedasajudgmentindexofthenoisetype.Accordingtothejudgmentofnoisetypeeverypixelcanbeadaptivelyde-noisedwithdifferentfilters.Throughanapproximationexperimentforaone-dimensionalcomplexsignal,thefeasibilityofSARdataregressionbasedonWSVRisconfirmed.AfterwardtheSARimageistreatedasatwo-dimensionalcontinuoussignalandfilteredbyanSVRwithwaveletkernelfunction.Theresultsshowthatthemethodproposedherereducestheradarspecklenoiseeffectivelywhilemaintainingedgefeaturesanddetailswell.
简介:对ATI技术进行改进,提出了一种机栽双通道SAR加权ATI地面慢速运动目标检测方法。该方法将DPCA技术和ATI技术的优点结合起来,利用DPCA技术得到加权值对ATI干涉结果进行加权处理,提出了一种新的动目标检测方法。计算机仿真结果表明,该改进方法与ATI方法相比能够有效减少虚假目标的数目,并能够检测到弱目标;与DPCA方法相比,它能够检测到DPCA方法由于对消过大而无法检测到的速度更慢的目标。
简介:提出了一种基于压缩感知(CS,compressivesensing)的SAR对多舰船目标的成像算法。通过将多舰船目标成像转换为在某种基下具有稀疏表示的信号重建问题,从而满足CS理论对信号恢复重构的要求,获得比传统成像方法更高的方位分辨率。实测数据的处理验证了该算法的有效性。
简介:基于SAR图像的舰船目标自动检测是海洋监视应用的重要方面,但随着SAR成像能力和图像分辨率的提高,传统的CFAR检测方法已不能满足舰船目标自动检测的要求。针对中高分辨率SAR图像中舰船目标自动检测问题,提出一种基于像素筛选G0分布的SAR图像舰船目标快速检测方法,该方法首先根据像素灰度值出现频率选取阈值对杂波像素进行筛选,然后通过抽样定理对图像进行降分辨率处理,最后再在经过像素筛选的降分辨率图像中实现基于G0分布的自适应CFAR检测。NASA/JPLAIR-SAR实测数据的实验结果表明,该方法不仅能有效减少中高分辨率SAR图像舰船目标自动检测的虚警,而且能显著提高检测效率。
简介:天线外定标是实现星载SAR天线方向图在轨测试的主要手段。天线方向图的准确测量,对星载SAR图像的应用具有重要作用。分布目标辐射定标在星载SAR天线方向图测试中受到广泛重视。亚马逊热带雨林的后向散射系数呈现大面积的均匀性和稳定性,故成为分布目标定标最主要的定标场。该文在分布目标定标原理的基础上,对基于亚马逊热带雨林的星载SAR天线方向图测量算法进行了研究,提出了采用K.Pearson统计量非参数假设检验的一致性处理算法,并采用Levenberg-Marquard算法(LM算法)估计俯仰向天线方向图模型参数。仿真数据验证了算法的可靠性和准确性。
简介:Movingshipsproduceasetofwavesof"V'patternontheocean.ThesewavescanoftenbeseenbySyntheticApertureRadar(SAR).Thedetectionofthesewakescanprovideimportantinformationforsurveillanceofshipping,suchasshiptravelingdirectionandspeed.AnovelapproachtothedetectionofshipwakesinSARimagesbasedonfrequencydomainisprovidedinthisletter.ComparedwithtraditionalRadon-basedapproaches,computationisreducedby20%-40%withoutlosingnearlyanyofdetectionperformance.ThetestingresultsusingrealdataandsimulationofsyntheticSARimagestestthealgorithm'sfeasibilityandrobustness.
简介:Inthispaper,inordertoimprovetheaccuracyoftheSyntheticApertureRadar(SAR)satelliteattitudeusingGlobalPositioningSystem(GPS)wide-bandcarrierphase,theSARsatelliteattitudekinematicvectorandKalmanfilterareintroduced.IntroducingthestatevariablefunctionofGPSattitudedeterminationalgorithminSARsatellitebymeansofkinematicvectoranddescribingtheobservationfunctionbytheGPSwide-bandcarrierphase,thepaperusestheKalmanfilteralgorithmtoobtiantheattitudevariablesofSARsatellite.ComparedthesimulationresultsofKalmanfilteralgorithmwiththeleastsquarealgorithmandexplicitsolution,itisindicatedthattheKalmanfilteralgorithmisthebest.