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ID:34566491
大小:1.29 MB
页数:14页
时间:2019-03-08
《AAS_98-063_HIGH_FIDELITY_MATHEMATICAL_MODELING_OF_REACTION_WHEEL_PERFORMANCE.pdf》由会员上传分享,免费在线阅读,更多相关内容在学术论文-天天文库。
1、-AAS98-063IDGHFIDELITYMAmEMATICALMODELINGOFREACTIONWHEELPERFORMANCEBillBialke*Ac~uratemathematicalmodelsofcomponentsareanessentialelementofattitudecontrolsystemdesign,analysis,andsimulation.Thispaperpres~ntsadetailedmathematicalmodelofareactionwheel,cont
2、ainingrelationshipsforpredictingreactiontorquesanddragtorques,powerconsumptionanddisturbances.PerformancecoefficientsareincludedforITHACO'sTypeAandTypeBreactionwheels.Disturbancesfromreactionwheelscontributetospacecraftpointingjitterandpotentiallygenerat
3、emicrophonicsinpayloadinstruments.Definitionsandquantitativeexamplesareprovidedforthevarioustypesofreactionwheeldisturbancesduetosourcessuchasflywheelimbalance,bearingstiction,bearingtorquenoiseandmotortorquerippleandcogging.INTRODUCTIONReactionwheelsare
4、momentumexchangedeviceswhichprovidereactiontorquetoaspacecraftandstoreangularmomentum.Mathematicalmodelingofthesedevicescancons.istmerelyofanapplicationofNewton'slaws'.butadditionaltermsareincludedheremtoassessperformancebeyondthenominalspeedrange,andasa
5、fun~tJOnoftemperatureandbusvoltage.Inaddition,reactionwheeldisturbancetermsarederivedforassessingspacecraftjitter..Areactionwheelconsistsofarotatingflywheel,typicallysuspendedon?allbeanngs,anddrivenbyaninternalbrushlessDCmotor:Ac~tawayviewofatypicalITHAc
6、areactionwheelisshowninFigure1.Amotordnverdeliverscommutatedcurrenttothemotorproportionaltoaninputvoltagecommandedbytheuser.Figure1CutawayViewofITHACOReactionWheel-------------ITHACOSpaceSystems.Inc.,950DanbyRoad.Suite100.Ithaca.NewYork14850.483NEARLYIDE
7、ALREACTIONWHEELAfundamentalblockdiagramofanearlyidealreactionwheelisshowninFigure2.Thesoleinputisatorquecommandvoltagewhichcontrolsmotorcurrent,andthusmotortorque.Frictiontorqueistheonlylosswhichissubtractedfromthemotortorque.Anidealreactionwheelwouldhav
8、enofrictiontorque,thusthediagramrepresentsa'nearly'idealwheel.ReactionTorquet------~rzTorqueCommandVolttlgeFigure2NearlyIdealReactionWheelBlockDiagramTheangularmomentumstoredintheflywheel,Hz,istheproductoftheflywheelinerti
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