简介：Fishesarefamousfortheirabilitytopositionthemselvesaccuratelyeveninturbulentflows.Thisabilityistheresultofthecoordinatedmovementoffinswhichextendfromthebody.Wehaveembarkedonaresearchprogramdesignedtodevelopanagileandhighefficientbiologicallyinspiredroboticfishbasedontheperformanceofhybridmechanicalfins.Toaccomplishthisgoal,amechanicalray-likefinactuatedbyShapeMemoryAlloy(SMA)isdeveloped,whichcanrealizebothoscillatorylocomotionandundulatorylocomotion.Wefirstgiveabriefintroductiononthemechanicalstructureofourfinandthencarryouttheoreticanalysisonforcegeneration.DetailedinformationofthesetheoreticalresultsislaterrevealedbyComputationalFluidDynamic(CFD),andisfinalvalidatedbyexperiments.Thisroboticfinhaspotentialapplicationasapropulsorforfutureunderwatervehiclesinadditiontobeingavaluablescientificinstrument.

简介：Inthispaper,acarangiformroboticfishwith4-DoF(degreeoffreedom)tailhasbeendeveloped.Theroboticfishhascapabilityofswimmingundertwomodesthatareradiocontrolandautonomousswimming.Experimentswereconductedtoinvestigatetheinfluencesofcharacteristicparametersincludingthefrequency,theamplitude,thewavelength,thephasedif-ferenceandthecoefficientonforwardvelocity.Theexperimentalresultsshownthattheswimmingperformanceoftheroboticfishisaffectedmostlybythecharacteristicparametersobserved.

简介：Biomimeticdesignemploystheprinciplesofnaturetosolveengineeringproblems.Suchdesignswhicharehopedtobequick,efficient,robust,andversatile,havetakenadvantageofoptimizationvianaturalselection.Inthepresentresearch,anenvironment-friendlypropulsionsystemmimickingundulatingfinsofstingraywasbuilt.Anon-conventionalmethodwasconsideredtomodeltheflexibilityofthefinsofstingray.Atwo-degree-of-freedommechanismcomprisedofseverallinkageswasdesignedandconstructedtomimictheactualflexiblefin.Thedrivinglinkageswereusedtoformamechanicalfincon-sistingofseveralfinsegments,whichareabletoproduceundulations,similartothoseproducedbytheactualfins.Owingtothemodularityofthedesignofthemechanicalfin,variousundulatingpatternscanberealized.Somequalitativeobservations,obtainedbyexperiments,predictedthatthethrustsproducedbythemechanicalfinaredifferentamongvariousundulatingpatterns.Tofullyunderstandthisexperimentalphenomenonisveryimportantforbetterperformanceandenergysavingforourbioroboticunderwaterpropulsionsystem.Here,fourbasicundulatingpatternsofthemechanicalfinwereperformedusingtwo-dimensionalunsteadycomputationalfluiddynamics(CFD)method.Anunstructured,grid-based,unsteadyNavier-Stokessolverwithautomaticadaptivere-meshingwasusedtocomputetheunsteadyflowaroundthefinthroughtwentycompletecycles.Thepressuredistributiononfinsurfacewascomputedandintegratedtoprovidefinforceswhichweredecomposedintoliftandthrust.Thepressureforceandfrictionforcewerealsocomputedthroughouttheswimmingcycle.Finally,vortexcontourmapsofthesefourbasicfinundulatingpatternsweredisplayedandcompared.

简介：Thedisadvantagescausedbytheswingofafishbodywereanalyzed.Thecoordinatesystemofatwo-jointrobotfishwasbuilt.Thehydrodynamicanalysisofrobotfishwasdeveloped.Thedynamicsimulationofatwo-jointrobotfishwascarriedoutwiththeADAMSsoftware.Therelationshipbetweentheswingoffishbodyandthemassdistributionofrobotfish,therela-tionshipbetweentheswingoffishbodyandtheswingfrequencyoftail,weregained.Theimpactoftheswingoffishbodyonthekinematicparametersoftailfinwasanalyzed.Threemethodstorestraintheswingoffishbodywerepresentedanddis-cussed.

简介：Poly(vinylalcohol)/hydroxylapatite(PVA/HA)compositehydrogelwaspreparedbyrepeatedfreezingandthawing.Thewaterlosspropertiesoftheresultanthydrogelwereinvestigatedbyusingopticalmicroscope.LongtimeimmersiontestsofPVA/HAcompositehydrogelwerecarriedoutinthedilutedcalfserumsolutiontostudythechangelawsofswellingpropertieswiththefreezing-thawingcyclesandHAcontent.Themicro-morphologiesofPVA/HAcompositehydrogelafterlongtimeimmersionwereobservedbymeansofthehigh-accuracy3Dprofiler.TheresultsshowthattheswellingprocessofPVA/HAcompositehydrogelistheconverseprocessofitswaterloss.LongtimeswellingratiocurvesofPVA/HAcompositehydrogelinthecalfserumsolutionaremanifestedasfourstagesofquickincrease,decrease,slowdecreaseandstablebalance,anditsequilibriumswellingratiodecreaseswiththeincreaseoffreezing-thawingcyclesandHAcontent.ItisrevealedthatthenetworkstructureofthecompositehydrogelimmersedforalongperiodissignificantlyimprovedwiththeincreaseofHAcontent.PerfectnetworkstructuresofPVA/HAcompositehydrogelaswellasfullandequilibriumtissuesafterswellingequilibriumareobtainedwhentheHAcontentis3%andthenumberoffreezing-thawingcyclesis7.

简介：Theheadmounteddisplay(HMD)iswidelyusedinvirtualrealitytechnology.IncommonHMD,however,thebinoculardisparityissettoanequalfixedvalueintheentirerangeofview.SuchHMDsystemshaveseveralshortcomingswhenusedforwideviews.Inthisstudy,inordertorealizeanaturalstereosensationofHMDwithwideview,wemeasurethecharacteristicsofbinocularstereoperceptionandbinocularlightperception.Resultsshowthatboththestereoacuityandlightsensitivitydecreaseastheretina'seccentricityincreasesfromfoveatoperiphery.However,thedecreaseofthestereoacuityismorerapidthanthatofthelightsensitivity.Theseresultssuggestthatthebinoculardisparityattheperipheralfieldshouldbesmall,otherwisedoubleimageswouldbeobservedinsteadofastereoview.Basedontheresultswedeveloparelativebinocularstereoacuitymodelwhichcanbeapplied{orthedesignofHMDsystemswithwideview.