简介:在假定目标RCS起伏为高斯形状频谱特性的前提下,将高斯白噪声通过一个高斯谱特性的低通滤波器来模拟目标RCS起伏特性。首先用康斯坦尼兹法设计了低通滤波器,并根据地杂波等效速度的不同,得到一组不同的滤波器响应,进而实现了背景RCS起伏程度不同的地杂波的模拟。然后以该地杂波为背景,采用ATI方法进行动目标检测,分析了地面背景RCS起伏特性对动目标检测性能的影响。计算机仿真结果表明:在一定的虚警概率下,当不考虑接收机噪声时,随着RCS起伏加剧,动目标径向最小可检测速度增大。最后得到结论:用基于ATI方法进行动目标检测时,若不考虑雷达接收机噪声,则地面背景RCS起伏特性是影响最小径向可检测速度的主要因素。
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。