简介:AconceptofSpecificStructureEfficiency(SSE)wasproposedthatcanbeusedinthelightweighteffectevaluationofstructures.Themainproceduresofbionicstructuredesignwereintroducedsystematically.Theparameterrelationshipbetweenhollowstemofplantandtheminimumweightwasdeducedindetail.InordertoimproveSSEofpylons,thestructuralcharacteristicsofhollowstemwereinvestigatedandextracted.Bionicpylonwasdesignedbasedonanalogousbiologicalstructuralcharacteristics.Usingfiniteelementmethodbasedsimulation,thedisplacementsandstressesinthebionicpylonwerecomparedwiththoseoftheconventionalpylon.ResultsshowthattheSSEofbionicpylonisimprovedobviously.Static,dynamicandelectromagnetismtestswerecarriedoutonconventionalandbionicpylons.Theweight,stress,displacementandRadarCrossSection(RCS)ofbothpylonsweremeasured.ExperimentalresultsillustratethattheSSEofbionicpylonismarkedlyimprovedthatspecificstrengthefficiencyandspecificstiffnessefficiencyofbionicpylonareincreasedby52.9%and43.6%respectively.TheRCSofbionicpylonisreducedsignificantly.
简介:Reactioncontrolsystem(RCS)isapowerfulandefficientactuatorforspacevehiclesattitudecontrol,whichistypicallycharacterizedasapulsedunilateraleffectoronlywithtwostates(off/on).Alongwithinevitableinternaluncertaintiesandexternaldisturbancesinpractice,thisinherentnonlinearcharacteralwayshindersspacevehiclesautopilotfrompursuingprecisetrackingperformance.Comparedtomostofpre-existingmethodologiesthatpassivelysuppresstheuncertaintiesanddisturbances,adesignbasedonpredictivefunctionalcontrol(PFC)andgeneralizedextendedstateobserver(GESO)isfirstlyproposedforthree-axisRCScontrolsystemtoactivelyrejectthatwithnorequirementforadditionalfuelconsumption.ToobtainahighfidelitypredictivemodelonwhichtheperformanceofPFCgreatlydepends,thenonlinearcouplingmultiple-inputmultiple-output(MIMO)flightdynamicsmodelisparameterizedasastate-dependentcoefficientform.Andbasedonthat,aMIMOPFCalgorithminstatespacedomainforaplantofarbitraryordersisdeducedinthispaper.Theinternaluncertaintiesandexternaldisturbancesarelumpedasatotaldisturbance,whichisestimatedandcancelledtimelytofurtherenhancetherobustness.Thecontinuouscontrolcommandsynthesisedbyabovecontroller-rejectortandemisfinallymodulatedbypulsewidthpulsefrequencymodulator(PWPF)toon-offsignalstomeetRCSrequirement.Therobustnessandfeasibilityoftheproposeddesignarevalidatedbyaseriesofperformancecomparisonsimulationswithsomeprominentmethodsinthepresenceofsignificantperturbationsanddisturbances,aswellasmeasurementnoise.
简介:摘要:雷达目标检测、目标跟踪、目标识别、威胁评估、雷达的最大作用距离估计等方面,RCS都是极其重要的基本参数,本文以某飞机模型为研究对象,通过计算和分析构建了该目标的静态RCS数据库,在此基础上,通过动目标姿态轨迹数据生成或飞行实测数据、推导了雷达站心坐标系与目标坐标系之间的转换关系,得到了目标动态RCS仿真数据。该方法对雷达目标动态特性的仿真研究具有重要的参考价值。