简介:Theaddedmasscoefficientandthewaterlevelindexformulasforthesame-phaseandanti-phasevibrationofrectangularliquidtanks'bulkheadswerederivedbasedondrymodetheory.Threefluid-structureinteractionnumericalmethodsincludingFluidFEMandFluidBEMwereusedinthiscase.ThecomparisonofnumericalandtheoreticalresultsbythepresentmethodshowsthatANSYS/FluidS0ismorecredible,theNASTRAN/VirtualMassMethodismoresuitableforengineeringcalculationsandresultsofthesame-phasevibrationbythepresentmethodismoreaccurate.
简介:S-surfacecontrolhasproventobeaneffectivemeansformotioncontrolofunderwaterautonomousvehicles(AUV).Howevertherearestillproblemsmaintainingsteadyprecisionofcourseduetotheconstantneedtoadjustparameters,especiallywheretherearedisturbingcurrents.Thusanintelligentintegralwasintroducedtoimproveprecision.AnexpertS-surfacecontrolwasdevelopedtotunetheparameterson-line,basedontheexpertsystem,itprovidesS-surfacecontrolaccordingtopracticalexperienceandcontrolknowledge.Topreventcontroloutputover-compensation,afuzzyneuralnetworkwasincludedtoadjusttheproductionrulestotheknowledgebase.ExperimentswereconductedonanAUVsimulationplatform,andtheresultsshowthattheexpertS-surfacecontrollerperformsbetterthananS-surfacecontrollerinenvironmentswithcurrents,producinggoodsteadyprecisionofcourseinarobustway.
简介:Arraycalibrationisimportantinengineeringpractice.Inthispaper,fastcalibrationmethodsforaULA'sgainandphaseerrorsbothinfarandnearfieldsareproposed.Inthefarfield,usingasinglesoundsourcewithoutexactorientation,thismethodhorizontallyrotatesthearrayexactlyonce,performseigenvaluedecompositionforthecovariancematrixofreceiveddata,thencomputesthegainandphaseerroraccordingtotheformulas.Inthenearfield,usingthesamesinglesoundsource,itisnecessarytorotatethearrayhorizontallyatmostthreetimes,buildequationsaccordingtogeometricrelations,thensolvethem.Usingtheformulaproposedinthispaper,sphericalwavesaremodifiedintoplanewaves.Theneigenvaluesdecompositionisperformed.Thesetwocalibrationmethodswereshowntobevalidbysimulationandarefast,accurateandeasytouse.Finally,ananalysisoffactorsinfluencingestimationprecisionisgiven.
简介:Oceanographicsurvey,orothersimilarapplicationsshouldbetheapplicationsofmultipleAUVs.Inthispaper,theskill&simulationbasedhybridcontrolarchitecture(S2BHCA)asthecontroller'sdesignreferencewasproposed.Itisamulti-robotcooperationorientedintelligentcontrolarchitecturebasedonhybridideas.TheS2BHCAattemptstoincorporatethevirtuesofthereactivecontrollerandofthedeliberativecontrollerbyintroducingtheconceptofthe"skill".Theadditionalonlinetasksimulationabilityforcooperationissupported,too.Asanapplication,amultipleAUVcontrolsystemwasdevelopedwiththree"skills"fortheMCMmissionincludingtwodifferentcooperativetasks.Thesimulationandtheseatrialsshowthatsimpletaskexpression,fastreactionandbettercooperationsupportcanbeachievedbyrealizingtheAUVcontrollerbasedontheS2BHCA.