简介:Wingmotionofadragonflyinthemaneuveringflight,whichwasmeasuredbyWangetal.[1]wasinvestigated.Equationsofmotionforamaneuveringflightofaninsectwerederived.Theseequationswereappliedforanalyzingthemaneuveringflight.Inertialforcesandmomentsactingonabodyandwingswereestimatedbyusingtheseequationsandthemeasuredmotionsofthebodyandthewings.Theresultsindicatedthefollowingcharacteristicsofthisflight:(1)Thephasedifferenceinflappingmotionbetweenthetwoforewingsandtwohindwings,andthephasedifferencebetweentheflappingmotionandthefeatheringmotionofthefourwingsareequaltothoseinasteadyforwardflightwiththemaximumefficiency.(2)Thecamberchangeandthefeatheringmotionweremainlycontrolledbymusclesatthewingbases.
简介:Acouplingframeofspeedgainandmaintainwassuggestedtoassesstheflightperformanceofhypersoniccruisevehicles(HCV).Theoptimalcruisespeedwasobtainedbyanalyzingtheflightperformancemeasuredbytheratioofinitialboostmasstogeneralizedpayload.TheperformanceofHCVsbasedonrocketsandair-breathingramjetswasstudiedandcomparedtothatofaminimum-energyballistictrajectoryunderacertainflightdistance.Itisconcludedthatrocket-basedHCVsflyingattheoptimalspeedar...
简介:Wedescribethedesignoffourornithoptersranginginwingspanfrom10cmto40cm,andinweightfrom5gto45g.Thecontrollabilityandpowersupplyaretwomajorconsiderations,sowecomparetheefficiencyandcharacteristicsbetweendif-ferenttypesofsubsystemssuchasgearboxandtailshape.Ourcurrentornithopterisradio-controlledwithinbuiltvisualsensingandcapableoftakeoffandlanding.Wealsoconcentrateonitswingefficiencybasedondesigninspiredbyarealinsectwingandconsiderthataspectsofinsectflightsuchasdelayedstallandwakecaptureareessentialatsuchsmallsize.Mostimportantly,theadvanceratio,controlledeitherbyenlargingthewingbeatamplitudeorraisingthewingbeatfrequency,isthemostsignificantfactorinanornithopterwhichmimicsaninsect.
简介:Unmannedaerialvehicles(UAVs)mayplayanimportantroleindatacollectionandoffloadinginvastareasdeployingwirelesssensornetworks,andtheUAV’sactionstrategyhasavitalinfluenceonachievingapplicabilityandcomputationalcomplexity.Dynamicprogramming(DP)hasagoodapplicationinthepathplanningofUAV,butthereareproblemsintheapplicabilityofspecialterrainenvironmentandthecomplexityofthealgorithm.BasedontheanalysisofDP,thispaperproposesahierarchicaldirectionalDP(DDP)algorithmbasedondirectiondeterminationandhierarchicalmodel.WecompareourmethodswithQ-learningandDPalgorithmbyexperiments,andtheresultsshowthatourmethodcanimprovetheterrainapplicability,meanwhilegreatlyreducethecomputationalcomplexity.
简介:在水下滑翔机是最近的创新类型自治在水下车辆(AUV)在海洋探索和观察使用了。他们调整快活潜水并且回到海洋表面。在高度的变化期间,他们使用力量由他们的翅膀开发了向前移动的水动力学。他们的班机被改变他们的重心和他们的快活的位置调整他们的修剪和脚跟角度控制。为更好的飞行控制,水动力学行为的理解和飞行力学在水下滑翔机是必要的。A6-DOF运动模拟器被结合为这个目的一个不稳定的潜在的流动模型。在一些特定的盒子中,数字学习证明一种不恰当的stabilizer尺寸能引起相反驾驶的行为。模拟器能被用来改进自动飞行控制。它能也被用于设备的水动力学设计优化。
简介:Aerodynamicforcesandpowerrequirementsinforwardflightinabumblebee(Bombusterrestris)werestudiedusingthemethodofcomputationalfluiddynamics.Actualwingkinematicdataoffreeflightwereusedinthestudy(thespeedrangesfrom0m/sto4.5m/s;advanceratiorangesfrom0-0.66).Thebumblebeeemploysthedelayedstallmechanismandthefastpitching-uprotationmechanismtoproduceverticalforceandthrust.Theleading-edgevortexdoesnotshedinthetranslatoryphaseofthehalf-strokesandismuchmoreconcentratedthanthatofthefruitflyinapreviousstudy.Athoveringandlow-speedflight,theverticalforceisproducedbyboththehalf-strokesandiscontributedbywinglift;atmediumandhighspeeds,theverticalforceismainlyproducedduringthedownstrokeandiscontributedbybothwingliftandwingdrag.Atallspeedsthethrustismainlyproducedintheupstrokeandiscontributedbywingdrag.Thepowerrequirementatlowtomediumspeedsisnotverydifferentfromthatofhoveringandisrelativelylargeatthehighestspeed(advanceratio0.66),i.e.thepowercurveisJshaped.Exceptatthehighestflightspeed,storingenergyelasticallycansavepowerupto20%-30%.Atthehighestspeed,becauseofthelargeincreaseofaerodynamictorqueandtheslightdecreaseofinertialtorque(duetothesmallerstrokeamplitudeandstrokefrequencyused),thepowerrequirementisdominatedbyaerodynamicpowerandtheeffectofelasticstorageofenergyonpowerrequirementislimited.
简介:象kinematics一样的形态学是在flapping飞行的性能的一个批评决定因素。在bio-flyers的气体动力学上理解结构的特点的效果,有在翼尖的1,2,和4表现象徘回一样正弦曲线kinematics的方面比率(AR)的三个矩形的翅膀基于雷纳兹数字5300试验性地被调查。沿着翅膀跨度的部分切割上的流动结构被比较。更强壮的K-H不稳定性与更高的方面比率在翅膀的前缘旋涡上被发现。旋涡爆炸仅仅出现在high-aspect-ratio翅膀的外部spanwise地点上。在high-aspect-ratio翅膀上爆炸的旋涡也许是为什么的原因之一bio-flyers通常有low-aspect-ratio翅膀。除了当旋涡爆炸发生时,定量分析在更高的方面比率翅膀上展出前缘旋涡(LEV)的更大的无尺寸的循环。沿着跨度的AR1和AR2的平均无尺寸的发行量几乎在50%跨度等于无尺寸的发行量。流动结构和发行量分析证明正弦曲线kinematics与在类似的研究使用的简化flappingkinematics相比压制LEV的故障。在在当前的Re范围,全面流动结构不对雷纳兹敏感的AR4表演的雷纳兹数字效果结果数。
简介:Anovelrobustfaultdiagnosisscheme,whichpossessesfaultestimatecapabilityaswellasfaultdiagnosisproperty,isproposed.Theschemeisdevelopedbasedonasuitablecombinationoftheadaptivemultiplemodel(AMM)andunknowninputobserver(UIO).ThemainideaoftheproposedschemestemsfromthefactthattheactuatorLock-in-Placefaultisunknown(whenandwheretheactuatorgetslockedareunknown),andmultiplemodelsareusedtodescribedifferentfaultscenarios,thenabankofunknowninputobserversaredesignedtoimplementthedisturbancede-coupling.AccordingtoLyapunovtheory,proofoftherobustnessofthenewlydevelopedschemeinthepresenceoffaultsanddisturbancesisderived.Numericalsimulationresultsonanaircraftexampleshowsatisfactoryperformanceoftheproposedalgorithm.