简介:Vehicleanti-collisiontechniqueisahottopicintheresearchareaofIntelligentTransportSystem.Theresearchonprecedingvehiclesdetectionandthedistancemeasurement,whicharethekeytechniques,makesgreatcontributionstosafe-driving.Thispaperpresentsamethodwhichcanbeusedtodetectprecedingvehiclesandgetthedistancebetweenowncarandthecarahead.Firstly,anadaptivethresholdmethodisusedtogetshadowfeature,andashadow!areamergingapproachisusedtodealwiththedistortionoftheshadowborder.Regionofinterest(ROI)isobtainedusingshadowfeature.ThenintheROI,symmetryfeatureisanalyzedtoverifywhethertherearevehiclesandtolocatethevehicles.Finally,usingmonocularvisiondistancemeasurementbasedoncamerainteriorparametersandgeometricalreasoning,wegetthedistancebetweenowncarandtheprecedingone.Experimentalresultsshowthattheproposedmethodcandetecttheprecedingvehicleeffectivelyandgetthedistancebetweenvehiclesaccurately.
简介:Atpresentwhatarethekeypointsfocusedintheresearchofloop-delayestimationforthedigitalpredistorterintheradiofrequency(RF)poweramplifiersystemisreducingitscomplexityofengineeringrealizationandimprovinganti-jammingabilityandcomputationalspeed.Besides,openingupitsapplicationscopeshouldbecontained.Forthesetargets,anovelmethodincludingintegerloopdelayestimationandfractionalpartisproposed.Theintegerpartappliesamplitude-differencesummationfunctionandthefractionaloneadoptsthemethodoffiniteimpulseresponse(FIR)linearinterpolation.Thealgorithmfindswideapplications.Whatismore,stronganti-jammingabilityandlowcomplexityarealsoitsmerits.Simulationresultssupporttheaboveopinion.Digitalpredistortion(DPD)systembasedonthisalgorithmachievesgoodperformance.
简介:UsingTime-VaryingAR(TVAR)modelandadaptivenotchfilterisanewmethodforthenon-stationaryjammersuppressioninDirectSequenceSpreadSpectrum(DSSS).TheperformanceofTVARmodelforInstantaneousFrequency(IF)estimationwillbeaffectedbysomefactorssuchasbasisfunctions.Focusingonthisproblem,theoptimalbasisfunctionofTVARmodelfortheIFestimationoftheLFMsignalisobtainedinthispaper.Besidesthedepthandwidthofnotching,thephasepropertiesofnotchfilteraffecttheSignal-to-Interferenceplus-NoiseRatio(SINR)ofcorrelationoutputtothenarrowbandjammersuppressioninDSSS,inresponsetotheproblemtheclosedsolutionofcorrelationoutputSINRimprovementhasbeenderivedwhenasinglefrequencyjammerpassesthroughdirectIIRnotchfilter,anditsperformancehasbeencomparedwiththoseoffivecoefficientFIRfilters.Later,anovelmethodforLFMjammersuppressionbasedonFourierbasisTVARmodelanddirectIIRnotchfilterisproposed.Thesimulationresultsshowtheeffectivenessoftheproposedmethod.
简介:Toeliminatethealiasingthatappearedduringthemeasurementofmulti-componentsnonstationarysignals,anovelkindofanti-aliasingalgorithmbasedontheshorttimeFouriertransform(STFT)isbroughtforward.Firstthephysicalessenceofaliasingthatoccursisanalyzed;secondtheinterpolationalgorithmmodelissetupbasedontheHammingwindow;thenthefastimplementationofthealgorithmusingtheNewtoniterationmethodisgiven.Usingthenumericalsimulationthefeasibilityofalgorithmisvalidated.Finally,theelectricalcircuitexperimentshowsthepracticalityofthealgorithmintheelectricalengineering.
简介:Tosolvetheflightsafetyproblemcausedbynonlinearinstabilities(categoryIIpilotinducedoscillations,PIOs)oftheclosed-looppilot-vehiclesystemwithrate-limitingactuator,theantiwindup(AW)compensationmethodtoavoidcategoryIIPIOsisinvestigated.Firstly,theAWcompensationmethodoriginallyusedforcontrollinginputmagnitudelimitedsystemisintroduced,thenthismethodisextendedforcontrollinginputrate-limitingsystemthroughacirclecriteriontheorem.Secondly,theestablishmentoftheAWcompensatoristransformedintothesolvingoflinearmatrixinequalities.Finally,anAWcompensatorestablishmentalgorithmfortheclosed-looppilot-vehiclesystemwiththerate-limitingactuatorisobtained.TheeffectivenessoftheAWcompensationmethodtoavoidcategoryIIPIOsisvalidatedbytime-domainsimulations,andcomparedwithrate-limitedfeedback(RLF)commandratecompensationmethod.TheresultsshowthattheAWcompensationmethodcaneffectivelysuppresscategoryIIPIOsandmaintainthenominalperformancewhentheclosed-looppilot-vehiclesystemisnormal.Unlikethecommandratecompensatorwhichworksuponsystemuninterruptedly,theAWcompensationmethodaffectstheclosed-looppilot-vehiclesystemonlywhentherate-limitingofactuatorisactivated,soitisanovelPIOavoidancemethod.