简介:Toimprovethereliabilityandaccuracyoftheglobalpositioningsystem(GPS)/microelectromechanicalsystem(MEMS)inertialnavigationsystem(INS)integratednavigationsystem,thispaperproposestwodifferentmethods.Basedonwaveletthresholddenoisingandfunctionalcoefficientautoregressive(FAR)modeling,acombineddataprocessingmethodispresentedforMEMSinertialsensor,andGPSattitudeinformationisalsointroducedtoimprovetheestimationaccuracyofMEMSinertialsensorerrors.ThenthepositioningaccuracyduringGPSsignalshortoutageisenhanced.ToimprovethepositioningaccuracywhenaGPSsignalisblockedforlongtimeandsolvetheproblemofthetraditionaladaptiveneuro-fuzzyinferencesystem(ANFIS)methodwithpoordynamicadaptationandlargecalculationamount,aself-constructiveANFIS(SCANFIS)combinedwiththeextendedKalmanfilter(EKF)isproposedforMEMS-INSerrorsmodelingandpredicting.Experimentalroadtestresultsvalidatetheefficiencyoftheproposedmethods.
简介:Globalpositioningsystem(GPS)forvehicleapplicationsintheurbanareaischallengedbylowsignalintensity.ThecarrierloopbasedonfastFouriertransform(FFT)canobtainahighsignaltonoiseratio(SNR)gainbyincreasingtheobservationtime.However,thisleadstoamajorproblemthattheaccelerationcannotbeignored.TheperformanceoftheFFT-basedloopwilldeclinewiththeaccelerationincreasing.ThispaperdiscussestheeffectofthedynamiconFFTfirst.ThenahighperformancecarriertrackingloopforweakGPSL5signalsisproposed.Itcombinesdiscretechirp-Fouriertransform(DCFT)andthephasefittingmethodtoestimateDopplerfrequencyandDopplerratesimultaneously.First,asequenceofintegrationresultsisusedtoperformDCFTtoestimatecoarseDopplerfrequencyandDopplerrate.Second,thephaseofthesequenceiscalculatedandusedtoperformlinearfitting.Bythephasefittingmethod,thefineDopplerfrequencyandDopplerratecanbeestimated.ThecomputationcostissmallbecausetheintegrationresultsareusedandthephasefittingmethodneedsonlycoarseestimatesofDopplerfrequencyandDopplerrate.ComparedwithFFTandDCFT,theprecisionofthephasefittingmethodisnotlimitedbytheresolution.Thustheproposedloopcangethighprecisionandlowcarriertonoiseratio(C/N0)trackingthreshold.Simulationresultsshowthisloophasagreatimprovementthanconventionalloopsforurbanweak-signalapplications.
简介:Inthispaper,inordertoimprovetheaccuracyoftheSyntheticApertureRadar(SAR)satelliteattitudeusingGlobalPositioningSystem(GPS)wide-bandcarrierphase,theSARsatelliteattitudekinematicvectorandKalmanfilterareintroduced.IntroducingthestatevariablefunctionofGPSattitudedeterminationalgorithminSARsatellitebymeansofkinematicvectoranddescribingtheobservationfunctionbytheGPSwide-bandcarrierphase,thepaperusestheKalmanfilteralgorithmtoobtiantheattitudevariablesofSARsatellite.ComparedthesimulationresultsofKalmanfilteralgorithmwiththeleastsquarealgorithmandexplicitsolution,itisindicatedthattheKalmanfilteralgorithmisthebest.