水下机器人

26•IEEEROBOTICS&AUTOMATIONMAGAZINE•SEpTEMBER20131070-9932/13/$31.00©2013IEEEAutonomousUnderwaterBiorobotsTareqAssaf,CesareStefanini,andPaoloDarioThisarticledescribesanewdesignforwirelesspowertransferinautonomousunderwaterrobots.Theaimistoproposeasolutionforbatterychargingbytakingintoaccountthemorphologicalanddimensionalconstraintsofrobotsrequiringsmallandlow-weightinternalmodules.Aninnovativedesignispresentedforinductivepowertransfersuitableforawiderangeofapplications.Thesystemisconceptuallyequivalenttoatransformerinwhichthecorecanbeseparatedintotwopartsduringoperation,oneforeachcoil.Inductivepowertransferisselectedtohaveasystemtoeasilyandreliablychargedifferentkindsofunderwaterrobots.Thesecondarycoilanditsmagneticcorearedesignedtobeplacedinsideabioinspiredrobot;theweight,dimensions,andpoweroutputforbatterychargingareoptimized.Theshapeofthesecondarymagneticcoresectionishollowtohousethecontrolelectronicsandsensors.Theprimarycoilisthepowerinductor,whichisplacedinadockingunitoutsidetherobot.Experimentalresultsarealsoreported.ProjectLAMPETRATheframeworkforthedevelopmentofthedevicedescribedinthisarticleistheprojectLife-LikeArtifactsforMotor-PosturalExperimentsandDevelopmentofNewControlTechnologiesInspiredbyRapidAnimallocomotion(LAMPETRA),athree-year(2008–2010)collaborativeAWirelessSystemforPowerTransferPhotocourtesyoftareqassaf,cesarestefanini,andPaolodarioDateofpublication:1August2013DigitalObjectIdentifier10.1109/MRA.2012.220157727september2013•IeeerObOtICs&AUtOmAtIONmAGAZINe•researchprojectfundedundertheSeventhEUframeworkprogram,themeICT-2007.8.3-FETproactive3,“Bio-ICTConvergence,”aimedatconsolidatingmultidisciplinaryBio-ICTresearchcarriedoutbyarecentlyestablishedscientificcommunity.ItinvolvesfourEuropeancountries:Italy,Swe-den,France,andSwitzerland.TheobjectiveoftheprojectLAMPETRAistodeveloplampreyandsalamanderbioin-spiredartifactsastoolsforneuroscientificstudiesongoal-directedlocomotion.Thepartnershavealreadydevelopedearlyprototypes:alamprey-likeartifactbyScuolaSuperioreSant’Anna—Pisa(SSSA)[1],[2]andasalamander-likeartifact[3],[4]bytheBiologicallyInspiredRoboticsGroup-Lausanne—Switzerland(EPFL).Inthelampreyprototype(SSSA),bothpowersupplyandcon-trolwerewired.Thisarticlefocusesontheadoptionofon-boardbatteriestoenhancefreelocomotion.Italsoaddressestheon-boardintegrationofcontrolelectronicsandsensors.Inthisarticle,awirelesssolutionforbatterychargingisdescribed,asanumberofconstraintsareprovidedbytheartifact.Therobotiscoveredbyasmooththinwaterproofskinlayer,whichissupposedtobedeli-catelytouchedduringachargingprocesscarriedoutthroughanon-contactpowertransfer.Inaddition,issuessuchasbodyflexibilityandspaceforinternalelectronicsmeanthattherehastobeabulkminiatur-ization(axialandtransversal)oftheon-boardpowerreceivingmodule.Thedeviceintroducedinthisarticleisatransformer-basedsystemthatcantransferelectricenergyfromaburrow-likedockingstationtotherobot,forfeedingthroughbatterycharging.StateoftheArtDockingandPowerTransferSystemDespitethewiderangeoftheories,methodologies,anddevicesforwirelesspowertransferdescribedintheliterature,wefocusonthosesolutionsadoptedinthefieldofoceanicexplorationforautonomousunderwatervehicles(AUVs).Shape,dimensions,andenergyrequestschangecasebycase,andtheworkingprinciplesofthechargingsystemscanbegroupedintothreeclasses:directelectriccontact,electrome-chanicgenerators,andinductivetransfer[5],[6].Inthefirsttype,energyisusuallytransferredtoelectriccontactspoweringanon-boardisolatedtransformer.Thecontactscanbedamagedbyoxidationandmechanicalstressorbyotherinteractionswiththeenvironment,andtheyarealsoacriticalintermsofwaterproofing.Thesecondsystem(electromechanicgenerators)canbeappliedtovehiclesthatusepropellersandarelesssuitableforbioinspiredrobotsthatperformswimmingbybodydeformation.Theelectricenergyistransferredfromthedockingstationtotherobotbyarotatingshaft.AmotorinthedockingstationturnstheshaftthatiscoupledtoageneratorortoanalternatorintheAUV.Conceptually,thethirdsystem(inductivetransfer)isatransformerwherethecorecanbesplitintotwoparts.Itexploitsanalternatingelectromagneticfieldtotransfertheenergyfromaprimarycoil,placedinthedockingstation,toasecondarycoil,intheAUV.Thepoweristransferredacrosstheair/watergapbetweenthetwocoils.Atransformer-basedsystemwasthere-foreselectedasthebestsolutionforthegivenapplication.DesignRobotOverviewTheprototypeofthelamprey-likeartifactissupposedtobeautono-mous,notonlyintermsofbehaviorbutalsoconcerningenergyandmobility.Tomeettheserequire-ments,therobotisequippedwith12vertebras,fouractivesegments,sixLipobatteries,andalargenumberofsensors,suchasvision,vestibular,andlightsensors(Figure1).Becauseofthecriticaldimensionsoftherobot,itwasnecessarytofindsolu-tionstodifferentintegrationissuestoincludeallthecomponentsonboard.AscanbeseeninFigure2,therobotcanbedividedintothreemainparts:thehead,thesegments,andthetail.Thetailprovidesasignificantcontributiontothepropulsion.Itisapassiveelementthattransmitsthelocomotionwavetothewaterwithhighefficiency.Thesegmentsareactuatedbynovelmuscle-likeactuator