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    25 April 2012, Volume 32 Issue 2 Previous Issue    Next Issue
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    Method of Autonomous Celestial Navigation Based on UKF and Information Fusion
    LUO Nan, XU Lu-Ping, ZHANG Hua
    2012, 32 (2):  1-9.  doi: 10.3780/j.issn.1000-758X.2012.02.001
    Abstract ( 2130 )   PDF (568KB) ( 1695 )   Save
     X -ray pulsars navigation uses the time of arrival (TOA) of the X-ray pulse radiation to resolve the position. Star sensor based navigation uses the angle between line of sight to the star and the center of earth to resolve the position. The mechanisms of the two navigation systems are different from each other. An information fusion celestial utonomous navigation method was proposed by hybriding the pulsars TOA and elevation angle of star sensor measurement. And the simulation experiments based on unscented Kalman filter (UKF) using real orbit parameters were carried out. A hard-in-loop simulation system which uses the laser quantum to emulate the X-ray quantum of pulsars was designed to test the method. The results show that, comparing to the methods based on pulsars or star sensor only, the estimation accuracy of position and velocity of the proposed method can increase 52.7%, 43.6%, 82.2% and 70.5% respectively, and its performance is better than extended Kalman filter (EKF) information fusion method.
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     BudgetAnalysisandSimulationofInter-satelliteLinkinWalker-δConstellation
    HAN Song-Hui, GUI Qing-Ming, LI Jian-Wen, DU Yuan-Lu
    2012, 32 (2):  10-16.  doi: 10.3780/j.issn.1000-758X.2012.02.002
    Abstract ( 2382 )   PDF (449KB) ( 1282 )   Save
    There is a need for more discussion on the other transmission loss and a reasonable transmission power of inter-satellite link (ISL). Firstly, the criteriafor ISL establishment were given under the agreement of short average distance and small range of ISL azimuth, elevation angleanddistance.Secondly,  the budget of the ISL, the free spacepropagationlossandothertransmissionlosswerediscussed,andthereferencevalueor the formulaofthesetransmissionlosseswasgivenlater.Furthermore,areasonabletransmissionpowerwas given bythe probabilisticknowledgeundertheconditionthatthemathematicalexpectationofthepracticaldatawasequaltotherateddataofthetransferrate.Then,thevarianceformulaofthedatatransmissionratewasderived.Finally,therangesofazimuth,elevationangleanddistanceofISLintheWalker27/3/1constellationwereanalyzedbysimulation.Theimpactofdifferentcarrierfrequenciesanddataratesonthetransmissionpowerwerediscussed,andareasonabletransmissionpowerwasalsodetermined.
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    Research on CO2 Adsorption Characteristics of Hydrophobic ZSM-5 Adsorbent
    WANG Xi-Qin, LI Kai, LUAN Zhi-Qiang, YE Ping-Wei
    2012, 32 (2):  17-21.  doi: 10.3780/j.issn.1000-758X.2012.02.003
    Abstract ( 1755 )   PDF (292KB) ( 1529 )   Save
    ThetraditionalCO2removalmethodwith 5A zeolite molecular sieve will lose efficacy because of the strong affinity with the water vapor.Ahydrophobic ZSM-5 adsorbent was preparedbyamixtureofZSM5,silicasol,waterandadditives,followedbyprocessesofextrusion,dryingandthenhydrophobicmodification.Thestructuresandpropertiesoftheadsorbentwere analyzed by N2, H2O/CO2adsorptionisothermsandXRDanalysismethods.Thepreparedadsorbenthasmultilevelpore structure,highBETspecificsurfacearea(296m2/g) andbetterCO2adsorptionperformance,aswell asexcellenthydrophobicity, and the H2O equilibriumadsorptioncapacityisabout1% of weightevenundertheconditionof90%relativehumidity.
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     AbsoluteErrorSelectionCriteriaofUnconstrainedModefor FlexibleManipulatorDynamicsModelDimensionReduction
    QI Nai-Ming, ZHAO Bao-Shan, ZHAO Zhi-Gang, WANG Li-Ping
    2012, 32 (2):  22-28.  doi: 10.3780/j.issn.1000-758X.2012.02.004
    Abstract ( 1735 )   PDF (347KB) ( 1417 )   Save
    Theunconstrainedmodedynamicsdimensionreductionmethodsonlyconsiderthestructuralparameterswithoutanalyzingtheimpactofthecontrolforce.DuetoanycontrolforcecanbeequivalenttothesuperpositionofaninfinitenumberofsinusoidalforcebyFourieranalysismethod,anunconstrainedmodeselectioncriteriaundersinusoidalforcebasedontheabsoluteerrorwaspresented.Theelasticdeformationofflexiblemanipulatorwasmodeledbyusingthefiniteelement(FE)method.ThedynamicsmodelofflexiblemanipulatorwasdeducedbyusingtheLagrangeapproach.Thesolutionofunconstrainedmodewasusedfordimensionreductionofthedynamicsequations.Thedimensionreductionofthedynamicsequationsandtheoriginaldynamicsequationswerecompared.Numericalsimulationsdemonstratethecorrectnessoftheproposedapproach.
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    ConfigurationParameterAnalysisforADAM-typeArticulatedMast
    LI Biao, LIU Zhi-Quan, CHENG Gang, DING Feng
    2012, 32 (2):  29-34.  doi: 10.3780/j.issn.1000-758X.2012.02.005
    Abstract ( 1971 )   PDF (405KB) ( 1518 )   Save
    TheconfigurationofADAM-typearticulatedmastwasdescribed,andmain configuration parameterswerechosen. FiniteelementmodelsoftheADAM-typemastwerebuiltupbyANSYS.Usingthesemodels,modeanalysiswascarriedout.By comparingtheanalysisresultswithexperimentresults,thecorrectnessofthefiniteelementmodelswasvalidated.Theeffectsofbaylength,canisterradius,crosssectionsideandpreloadofthediagonalcablesontheperformanceofthemastwereanalyzed.Theanalysisresultsshowthattheperformancecanbeimprovedbyincreasingthebaylength.Thebendingstiffnessandmassofthemastwillbepromotedasthecanisterradiusincreases.Thepreloadsofthediagonalcablesshouldbeselectedbetweentheallowableminimumvalueandthevaluecorrespondingtothesituationwhentheballsocketsobtainmaximumstiffness.Theseconclusionscouldbeappliedinmastengineeringdesign.
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    Space Target Recognition Based on Improved Kernel FCM
    WANG Xiao-Xue, YANG Yong-Sheng, JING Zhong-Liang
    2012, 32 (2):  35-42.  doi: 10.3780/j.issn.1000-758X.2012.02.006
    Abstract ( 2079 )   PDF (426KB) ( 1439 )   Save
    A recognitionsystemwaspresentedtoaccomplishspacetargetclassification.Firstly,Imagefeaturevectorswereextractedaccordingtoinvariantregionmoments,shapeandimagedescriptorsofspaceobjects.Andthen,clusteringalgorithmisappliedtotheclassifyspacetarget.AnimprovedkernelclusteringalgorithmbasedonVoronoidistancewasproposedwhichhadacrispermembershipfunctionandwasrobustfornoiseandoutliers.Experimentsshowthattheimprovedkernelfuzzyclusteringalgorithmismoreaccurateandvalidthanthatoftheconventionalmethods.
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    StartupandOperatingCharacteristics ofCapillaryWickEvaporator
    LI Jin-Wang, ZOU Yong, CHENG Lin
    2012, 32 (2):  43-47.  doi: 10.3780/j.issn.1000-758X.2012.02.007
    Abstract ( 1782 )   PDF (336KB) ( 1492 )   Save
    Theeffectsofporouswickporosityandheatsourcepoweronstartupand operatingcharacteristicsofcapillarywick evaporator(justlikealoopheatpipewithoutlinkingthevaporline)wasinvestigated.Theexperimentwascarriedoutwithout mixingtheeffectoftheworkingfluidandthecondenser.Theresultshowsthatthetemperatureoftheevaporatorwill fluctuateinsomecasesduringthestartupofthesystem.Theheatsourcepowerwhichmakesthetemperaturefluctuated decreasinglywiththeincreasingporosityoftheporouswick.Whenporouswickisthesame,temperatureiseasierto fluctuateanditwillbemuchseriouswith the biggerheatsourcepower.Thereasonforthetemperaturefluctuationisthatthe porosity of porous wick does notmatchwiththeoutsideparameters,suchastheheatcoursepower.
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    ConvolutiveBlindSeparationAlgorithmBasedonSatelliteCommunicationAnti-jamming
    WEN Yuan-Yuan, CHEN Hao
    2012, 32 (2):  48-54.  doi: 10.3780/j.issn.1000-758X.2012.02.008
    Abstract ( 1691 )   PDF (392KB) ( 1440 )   Save
     Aimingattheproblemofsatellitecommunicationsignalandjammingblindseparationinnoisyenvironment,anewalgorithmforconvolutivemixtureblindsourceseparation (BSS)byexploitingthehouseholdertransformationtorealizethejointdiagonalizationofhighordercumulantandoperationinthefrequencydomainwasproposed.Comparedwiththeclassicalmethods,simulationresultsshowthattheproposedalgorithmhaslowercomputationalcomplexityandbetterseparationperformance.Whensignal to noiseratio (SNR)isgreaterthan10dB,thenovelalgorithmofanti-jammingcanrealizetheseparationofcommunicationsignalsandthejamming,andhasgoodseparationperformance.
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    MultipleFaultDiagnosisAlgorithmUnderLargeFalse-alarmRateTests 
    ZHANG Sen, YU Deng-Yun, WANG Jiu-Long
    2012, 32 (2):  55-61.  doi: 10.3780/j.issn.1000-758X.2012.02.009
    Abstract ( 1830 )   PDF (440KB) ( 1208 )   Save
     Multiplefaultdiagnosisunderunreliabletestsusingthemultisignalmodelwasstudied.TheoptimalmultiplefaultdiagnosisproblemisNPcomplete,sosuboptimalalgorithmwasusedforlargescalesystemdiagnosis.Agoodfaultestimationunderlowfalsepositiveratewasobtainedbythesubgradientoptimizationmethod.Butifthesizeofthegraphisbigandthefalsealarmrateishigh,thisalgorithmwill notbeabletoeliminatetheinfluenceoffalsepositive,andtheresultingestimationwouldcovereveryfailedtestinsteadoffindingthetruefaultpositionofthesystem.Anewkindofdiscriminatefunctionconsideringbothfalseandtruepositivetestswasused,andanimprovedgeneticalgorithmwasproposedtosearchthefailurecomponents.Simulationresultsshowthatthenewmethodisfasterthansubgradientoptimizationandhasahighercorrectisolationratewhenintercurrentfaultsarefew.
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     Quasi-cycleLDPCConstructionMethod BasedonProtographExpansion 
    GONG Xian-Feng, TAO Xiao-Feng, QIU Le-De
    2012, 32 (2):  62-67.  doi: 10.3780/j.issn.1000-758X.2012.02.010
    Abstract ( 2667 )   PDF (334KB) ( 1522 )   Save
    Theperformanceoflowdensityparitycheckcode(LDPC)basedonprotopraphexpansiongreatlydependsontheexpansionmethod.AnewQC-LDPCconstructionmethodwasproposed.Twomainstepsintheparitycheckmatrixconstructionincludethemulti-edgeseliminationofprotographandquasi-cycleexpansion.Thefirststepmakelocalgirthmaximumundertheconstraintofedgepermutation.Inthesecondstep,optimumshiftvaluesofthepermutationmatriceswereobtainedbysearchingtheclosedloopswithinthespecifiedlengthandcomparingthelengthandapproximatecycleextrinsicmessagedegree(ACE)ofcycles,aimingatreducingsmallcycleswithlowconnectivitywhichwasharmfultothecodeperformance.Forprotographwithoutmulti-edges,theonlystepwasthequasicycleexpansion.Asprovedbysimulation,theconstructedQC-LDPChasexcellentperformanceinbothdecodingthresholdanderrorflooraspects.
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    MultipleSpacecraftsOn-orbitServiceTaskAllocationBasedonDPSO
    ZHANG Qi-Xin, SUN Fu-Chun, XU Bin, LIU Hua-Ping
    2012, 32 (2):  68-76.  doi: 10.3780/j.issn.1000-758X.2012.02.011
    Abstract ( 1919 )   PDF (500KB) ( 1081 )   Save
    Inordertosolvemulticonstrainedon-orbitservicetaskallocationforspacecraft,theprogrammingofon-orbitservicetaskallocationforon-orbitsatelliteswasstudied.Basedontheanalysisofthekeyfactorsincludingtargetsatellitevalue,servicespacecraftlossandenergy-timeconsumption,anon-orbitservicingmulti-spacecrafttaskallocationmodelwasformulated.Adiscreteparticleswarmoptimization (DPSO) algorithmwasproposedforon-orbitservicespacecraftcooperativetaskallocationproblems.Anewparticlepositionandnewupdatestrategyfortheparticlespeedweredeveloped.ThesimulationresultsshowthattheproposedDPSOalgorithmadmitsbetterconvergence,optimizationcapability,andcansolvetheon-orbitservicespacecraftcooperativetaskallocationeffectively.
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    CoordinatedManeuverofSpacecraftFormationBasedonLine-of-sightMeasurement 
    ZHANG Wei, FENG Xiao-Hui, DENG Zhong-Min
    2012, 32 (2):  77-83.  doi: 10.3780/j.issn.1000-758X.2012.02.012
    Abstract ( 1724 )   PDF (323KB) ( 1184 )   Save
     Basedontheline-of-sightmeasurement,acooperativecontrolmethodforleaderlessformationflightispresented.Line-of-sightvectormeasurementisgeneratedwheneachsatelliteinaformationtracksitsneighboringspacecraft.Thefirstmemberoftheformationtracksthedesiredorbitaccordingtothecommandfromahighlevelcontroller.Achainformationisgenerated.Distancesbetweenline-of-sightmeasurementsaretakenasfeedbackoftheformationcontroller.Therelativeperturbationequationsareprovidedtomakesurethatmodelinguncertaintiesandperturbationsareconsideredinthecontrolstrategy.Cyclicformationcontrolisperformedviaslidingmodecontroller.Simulationresultsshowthattheproposedcontrolmethodcanbeusedforsatelliteformationmaintenanceandmaneuver.
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