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25 October 2012, Volume 32 Issue 5 Previous Issue    Next Issue

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Adaptive Artificial Potential Function Guidance for Dynamic Obstacle Avoidance of Spacecraft GAO Peng, LUO Jian-Jun 2012, 32 (5):  1-8.  doi: 10.3780/j.issn.1000-758X.2012.05.001 Abstract ( 1756 )   PDF (431KB) ( 1430 )   Save Toavoidthedynamicobstaclesduringspacecraftautonomousproximityoperations,afuelsavingandhighaccuracyadaptiveartificialpotentialfunctionguidancemethodfordynamicobstaclesavoidancewaspresented.AsforthesituationthattheGaussianrepulsivepotentialfunctionwasnonzeroatthedesiredposition,acorrectiontermwasmultipliedtoeliminate deviationfromtheequilibriumpoint.Theguidancelawofavoidingdynamicobstacleswasdeducedbasedonthatofthestaticobstaclesavoidance.Then,accordingtotherelationshipbetweenvelocityandgravitygradient,thenegativefeedbackcontrolwasdesignedtomakethegravitygradientadapttothevarianceofvelocity,andtheadaptiveartificialpotentialfunctionguidancelawfordynamicobstaclesavoidancewasobtainedeventually.Toverifythecorrectnessandeffectivenessoftheguidancelaw,aseriesofnumericalsimulationsusingtheprecisemathematicalmodelwerecarriedout.Thesimulationresultsshowthatthecorrectedpotentialfunctioncaneffectivelyimprovetheconvergentprecision;andtheadaptiveartificialpotentialfunctionguidancelawmakesthecontrolpulsesmorereasonable,withsaving30%ofthetotaldeltaV,andistwodegreesmoreaccuratethanthetraditionalartificialpotentialfunctionguidancelaw. Related Articles | Metrics

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Adaptive Attitude Control of Spacecraft with Variable Speed Control Moment Gyroscopes TIAN Lin, XU Shi-Jie 2012, 32 (5):  9-16.  doi: 10.3780/j.issn.1000-758X.2012.05.002 Abstract ( 1837 )   PDF (453KB) ( 1477 )   Save Spacecraft precise attitude control is easily affected by system parameter errors. Adaptive control can estimate parameters reasonably and make the model based controller design more easily. Adaptive parameters are sorted into three groups includingspacecraft main body inertia, VSCMGs gimbal androtor inertia, and their dynamic friction coefficients. The detailed spacecraft attitude dynamics model considering VSCMGs gimbal and rotor friction was transformed according to the parameter groups. The attitude controller, VSCMGs steering law and parameters adaptive updating law were developed by Lyapunov method. Weight matrix was imported into the steering law to relief the gyroscopes singularity problem. Theory analysis and numerical simulation prove that the closed loop control system is global uniformly and ultimately bounded stable. Parameters adaptive updating can effectively reduce angular velocity tracking errors and make attitude quaternion errors converging faster. Parameter estimates can not accurately converge to their real values, but they are all within acceptable scopes. Related Articles | Metrics

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DesignofKu/KaDualbandSharedApertureMicrostripArrayAntenna LIU Yang, DONG Tao, WANG Xin 2012, 32 (5):  17-20.  doi: 10.3780/j.issn.1000-758X.2012.05.003 Abstract ( 2042 )   PDF (322KB) ( 1769 )   Save AnovelKu/Kadualbandsharedaperturemicrostriparrayantennawasproposed.Theantennaelementswereplacedonasinglelayertokeepthestructurecompact.TheKu-bandelementswerefedattheedgesbymicrostriplines,whiletheKa-bandwascoupledfedbyL-shapedaperturesinthegroundplanetorealizecircularpolarization.Thesimulatedandmeasuredresultsdemonstratethefeasibilityoftheproposeddesign.Thesimulatedimpedancebandwidthoftheantennais2.2%forKu-bandand4.3%forKa-bandrespectively,andmeasuredresultsare2.1%and3.4%respectively.TheantennastructureisapplicableforKu/Kadualbandsatellitecommunication. Related Articles | Metrics

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DynamicsInfluenceFactorsAnalysisonTwo-axis-positionMechanismofSatelliteAntennaswithJointClearance PAN Dong, WANG Xing-Gui, ZHAO Yang 2012, 32 (5):  21-26.  doi: 10.3780/j.issn.1000-758X.2012.05.004 Abstract ( 1615 )   PDF (396KB) ( 1618 )   Save iththehighdemandforpointingaccuracyofthesatelliteantenna,thejointclearanceisinevitableduetotheexistenceofthekinematicpairinthetwoaxispositionmechanism.Soitisparticularlyimportanttostudytheinfluenceofthejointclearancetosatelliteantennamechanism.Thetwoaxispositionmechanismwastakenasresearchobject,thecontact dynamicsmodeloftheclearancejointwasestablishedbyapplyingthenonlinearspringdampmodel,andthefrictioneffectwasconsideredbyapplyingtheCoulombfrictionmodel.Thelawthatthedynamiccharacteristicoftwoaxisposition mechanismaffectedbythefactorswasanalyzedbythedynamicsimulationofthevirtualprototype,suchasthesizeofthejointclearanceandthedrivingtorqueintheclearance.Theresultsshowthatlargejointclearanceanddrivingtorquewillreducethepositioningaccuracyandmakethesystemunstable.Itisagoodwaytoincreasethepositioningaccuracythroughoptimizingthestructureofthesatelliteantennamechanism. Related Articles | Metrics

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ControlPropertyoftheSpacecraftAttitudeUnderactuatedbyWheels GUI Hai-Chao, XU Shi-Jie, JIN Lei, ZHANG Jun 2012, 32 (5):  27-33.  doi: 10.3780/j.issn.1000-758X.2012.05.005 Abstract ( 1748 )   PDF (452KB) ( 1200 )   Save Smalltimelocalcontrollability(STLC)andstabilizabilityofthespacecraftattitudeunderactuatedbyreactionwheels(RWs)wereinvestigatedwiththewheelspeedsascontrolinputs.Firstly,withthewheelspeedsbeingtreatedasinputs,theconservationconstraintofthetotalangularmomentumofthespacecraftandRWswasdirectlybroughtintothedynamicsofthesystem.ThennonlinearcontrollabilityandstabilizabilitytheorywereutilizedtoanalyzethecontrolpropertyofthisdynamicswithoneandtwoRWsrespectively.TheresultsshowthattheSTLCofthespacecraftattitudeispossibleonlywhentwononcoaxialRWsareavailable.Simultaneously,thesystemcannotbeasymptoticallystabilizedbyatimeinvariantsmoothfeedback,butitstillcanbeasymptoticallystabilizedatleastbyapiecewisecontinuousfeedback.Accordingly,anonsmoothcontrollawbasedonquaternionwasconstructedtostabilizethespacecraftattitudewithwheelspeedsunderthesaturationlimits,whichnotonlyconfirmsthetheoreticaloutcomesbutalsoispracticallyuseful. Related Articles | Metrics

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ModelingMethodforOscillatorFlickerNoiseinKalmanbasedGPSTrackingLoop JIN Tian, WANG Li-Hua, HUANG Bing-Sheng 2012, 32 (5):  34-39.  doi: 10.3780/j.issn.1000-758X.2012.05.006 Abstract ( 2162 )   PDF (340KB) ( 1822 )   Save FrequencydriftcausedbyoscillatorwillpollutecarrierphaseandDopplerfrequencyinGPSreceiver.Therefore,itisnecessarytomodeltheoscillatorerrorinthetrackingsystem.TheflickernoiseerrorofoscillatorcannotbeexactlymodeledinKalmansystem,whichcauseserrorsinthemodeloftraditionalKalmanbasedtrackingloop.Tosolvetheseproblems,thefrequencydomainmodelandnoisecovarianceofoscillatorwereanalyzed,andamethodofexactlymodellingtheflickernoiseintheKalmanbasedtrackingloopwasproposed.RealGPSsatellitedatawasprocessedbyusingthenewoscillatormodeltoverifythevalidity. Related Articles | Metrics

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LEOSpacecraftOrbitAnomalyDetectionBasedonPredictionDispersion ZHANG Tao-Tao, BAI Xian-Zong, HAO Jia, CHEN Lei 2012, 32 (5):  40-46.  doi: 10.3780/j.issn.1000-758X.2012.05.007 Abstract ( 1804 )   PDF (430KB) ( 1580 )   Save detectionmethodbasedonpredictiondispersionwaspresentedtodealwithLEOspacecraftorbitanomalycausedbymaneuvers,collisions,andatmosphericenvironment.Thesemimajoraxisandinclinationwereselectedasorbitcharacteristicparameters.PredictionvaluesoforbitcharacteristicparameterscanbeachievedbyorbitextrapolationbasedonSGP4modelsecularterm.Afterdatasmoothingprocess,predictiondispersionsequencecanbeobtainedbycalculatingthedifferencebetweenpredictionandcatalogvaluesofthecharacteristicparameters.TheorbitanomalywasdetectedthroughthepredictiondispersiondatabasedonMahalanobisdistance.ThedetectionresultsofTerrain2010isconsistentwiththemaneuverhistorypublishedbyNASA,whichindicatethatthemethodpresentedinthispapercandetectthetimes,epochandtypeoforbitanomalyandcanbewidelyappliedtothespacesurveillanceandspacesituationalawareness. Related Articles | Metrics

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ImprovedHaloOrbitControlMethodBasedonPoleAssignment CHAO Ning, LUO Xiao-Ying, LI Yan-Jun 2012, 32 (5):  47-53.  doi: 10.3780/j.issn.1000-758X.2012.05.008 Abstract ( 1722 )   PDF (424KB) ( 1305 )   Save Basedonsmalldeviationtheory,theno-perturbation3-bodydynamicequationswerelinearizedandtheerrorlinearmodelwas deduced.Basedonthepoleassignmenttheoryoflinearsystem,stationkeepingforperturbedhaloorbitnearL1pointinEarth-MoonsystemwasachievedthroughdesigningtheclosedlooppoleassignmentstatefeedbackmatrixKbychoosing standardorbitstatevectorasclosedlooptargetpole.Aimedatthecontrolerrorcausedbysinglecontrollevelofthreeaxis in  K ,adesignmethodofvariablefeedbackmatrixKcoefficient(VKC)consideringthescaleoforbitinjectionwasproposed.TheexperimentsshowthattheVKCmethodwhichimprovedcontroleffectoforiginalcontrolmethodanddecreasedtrackingvariancesumunderdifferenterrorlevelsisavailable. Related Articles | Metrics

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SpaceEnvironmentSynergisticEffectonSpacecraft SHEN Zi-Cai, QIU Jia-Wen, DING Yi-Gang, LIU Yu-Ming, ZHAO Chun-Qing 2012, 32 (5):  54-60.  doi: 10.3780/j.issn.1000-758X.2012.05.009 Abstract ( 1841 )   PDF (555KB) ( 1359 )   Save Thenecessityofstudyonsynergisticeffectofspaceenvironmentsisanalyzed.Somesynergisticeffectssuchaselectron, protonandultraviolet,atomicoxygenandultraviolet,atomicoxygenandspacedebris,discharginginducedbyspacedebrisand contaminationinducedbyspaceenvironmentwerediscussed.Thepresentstateandperspectivesofstudyonsynergisticeffects werediscussedandproposed.Someadvicesandcountermeasuresofsystemicstudyonmechanism,simulation,testmethod,forecastingtechniqueweregiven. Related Articles | Metrics

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OptimizationofEarthMarsLowThrustTrajectoryBasedonArtificialImmuneAlgorithm PENG Kun, XU Shi-Jie, GUO Lin-Li, WANG Ping 2012, 32 (5):  61-68.  doi: 10.3780/j.issn.1000-758X.2012.05.010 Abstract ( 1857 )   PDF (424KB) ( 1520 )   Save TheEarth-Marslow-thrusttrajectorywasoptimizedbyArtificialImmuneAlgorithm.Firstly,thesystemmodelofEarthMarslowthrusttrajectorywasestablishedandnormalized.Secondly,theoptimizationproblemoflowthrusttrajectorywasconvertedintoa nonlinearprogrammingviaparameterizationandpenaltyfunction.Finally,aGAIA(GuidingArtificialImmuneAlgorithm)was proposed tosolvethisoptimizationproblem.SimulationresultsshowthattheGAIAhasfastconvergencerateandhighoptimization precision.Moreover,GAIAalgorithmavoidsmanyshortcomings,suchasinitialvaluesensitivity,illconditionedgradientandlocal convergence.TheeffectivenessofGAIAforlowthrusttrajectoryoptimizationisvalidated. Related Articles | Metrics

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OrbitMaintenanceTechnologyandImplementforHJ-1 A/BConstellation LIU Long-Fei, WANG Xing-Ling, BAI Zhao-Guang, TAN Tian, YU Gang 2012, 32 (5):  69-75.  doi: 10.3780/j.issn.1000-758X.2012.05.011 Abstract ( 1611 )   PDF (363KB) ( 1715 )   Save InordertomaintaintheformationofHJ-1A/Bconstellation,ensureCCDcamerascoverChina′sterritoryorrevisittheglobalin 48hours,andmeetthedemandsofChina′sdisastermonitoringandglobalterrestrialobserving,anorbitmaintenancestrategy consideringbothgroundtrackandconstellationphasewasdeveloped.Duringtheprocessofdisasterreductionandenvironment protection,revisitandcoveragecharacteristicsaremorecriticalthanstrictgroundtrackmaintenance,sotheorbitmaintenancestrategymainlyconsidertheconstellationphase.Itreducestheorbitmaintenancetimeandoperationrisk,savesthefuel,benefitslifespanofHJ-1A/B.Inthelast3moreyears,theorbitmaintenanceworkwasfullycompletedthroughonlytwice operations. Related Articles | Metrics

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RoutingAlgorithmforNavigationConstellationBasedonEvolvingGraphModel WANG Yan, LIU Bo, YU Wan-Rong, ZHAO Bao-Kang 2012, 32 (5):  76-83.  doi: 10.3780/j.issn.1000-758X.2012.05.012 Abstract ( 1929 )   PDF (466KB) ( 1711 )   Save Fornavigationconstellationequippedwithdirectionalantennaswhichperformsdeterministiclinkscheduling,inter-satelliteroutingprobleminnotfully-connectedconstellationwasstudied.Firstly,thedynamictopologyofnavigationconstellationwasmodeledbasedontheevolvinggraphtheory,andthecorrespondingdatastructurewasgivenlater.Secondly,aroutingalgorithmtocomputetheearliestjourneywasproposed,thenthestepsandthecomplexityofthealgorithmwerediscussed.Finally,theaveragetimecostandaveragehopsofearliestjourneywereshownbysimulationundergivenparameters.Theimpactof startingtimeonearliestjourneywasalsodiscussed. Related Articles | Metrics