The goal of the project is to design an underwater ROV ... · The goal of the project is to design an underwater ROV that has high maneuverability and ease of use all while being

ThegoaloftheprojectistodesignanunderwaterROVthathashighmaneuverabilityandeaseofuseallwhilebeingcostefficient.OurgoalsweretodecreasethecostoftheseunderwaterR.O.Vswhiles>llmaintainingitsfullfunc>onality,andimplementtheabilityfortheR.O.Vtoselfstabilizewhileallowing360°viewingviaanonboardcamera.Ideally,wewouldliketoimplementacombina>onofaaccelerometerandgyroscopesystem(IMU)tostabilizetheR.O.V,whileallowing360°viewing,whichisafeaturethatmostotherdesignslacked.If>meallowswewouldliketotryandimplementtheabilitytohoverinplaceaswell,doingthiswouldallowtheR.O.Vtoremainatafixedloca>onwhiletheuserthencontrolledthecameratoviewtheirsurroundings.Inaddi>on,designedandimplementedanintui>veusercontrolsystemthatallowsforeasymaneuverabilityoftheR.O.V.Theusercontrollingthevehicleremotelyshouldn’tneedextensivetrainingtoeffec>velyoperatetheR.O.V.Knowingthis,weplantouseapreexis>ngwiredcontroller,morespecificallyanXbox360.Thisallowedustofocuslessonthedesignofthecontrollerandmoreonperfec>ngtheresponsivenessoftheR.O.Vtotheuserinputwithminimaldelay.

Ballastsystem:Theballastsystemiscompressedairsemi-closedloopsystem.Compressedairisheldinaonegallontankthatisfilledtoapproximately100psi.Thetankisconnectedtoaballvalvewhichwillbeusedasasafetyshutoff,incaseofvalveortankfailure.Aregulatorimmediatelyfollowsthevalve,tobringthe100psifromthetankdownto5-15psi.AVertheregulator,thefirstsolenoidisconnectedwhichisusedtofilltheballastwhenopened,causingtheR.O.Vtofloat.Asecondsolenoidopens,allowingairoutoftheballasttankandcausingtheR.O.Vtosink.MotorsandProps:Themotorsusedinthesystemarebrushlessmotors,duetotheiralreadywaterproofstate.FourTurnigyD2830motorswillbeplacedineachcornerofthesystem,andtwoHobbykingST3508motorswillbeplacedonthesideoftheR.O.V.Four3-BladeD52xD5x13boatpropellerswereusedfortheTurnigyD2830.3-BladepropellersfortheHobbykingST3508motorsweredesignedaspartofourengineeringdesignaspect.CADrendersofthepropsandadaptersareseeninfigureChassis&Buoyancy:InordertoremainneutrallybuoyantandavoidmomentsbeingputontheR.O.Vfromunbalancedweights,arectangularPVCchassiswasdesigned.Thechassiswasbuiltfrom1”PVCpipeand90°elbows.Inthecaseoffreshwater(theTrinitypool),calcula>onsshowedthat~6.5-7lbsofballastwouldneedtobeaddedtobringthechassistoaneutrallybuoyantstate.ComponentsBox&Waterproofing:TheR.O.Velectronicsarelocatedonboardthesystem,allowingustoonlyneedasingle2-wiretetherforcommunica>ontothePi.PVCdeckingmaterialwaschosenduetoitbeinglightweight,affordableandnon-porous.Thematerialwascuttoformaboxofthefollowingdimensions:0.419x0.254x0.127m.Oneofthesidesoftheboxwasdesignedtobeabletoberemoved,foreasyaccesstotheinsideelectronics.APVCscrewcapfifngwascementedinplacetoallowaccessforthebagerychargingcables.Holesweredrilledonbothsidesofthebox,toallowashortpieceof1”-diameterPVCtobecementedontothebox.Theseholesallowedthewirestoberoutedfromthemotor,ballastandethernetintotheraspberrypi.

UnderwaterR.O.Vsarenotnewtechnology,howevermostarelarge,industrialsystemstetheredtoships.ManyofthecurrentportableR.O.Vdesignsares>llintheprototypephaseandmostoftheseR.O.Vdesignsaretailoredforpurelyleisure.Thecurrentdesignsavailabletendtobeexpensive,pricesrangingfrom$1,500-$3,000.DesignsliketheFathomoneandGladiusUnderwaterDronerelysolelyonmotorstocontrolhowdeeptheR.O.Vis,andprovidednoisolatedmo>oncontrolofthecamera.Ballastsystemsaremostcommonlyseeninsubmarines.Submarinehaveballasttanksthatcanbealternatelyfilledwithwaterorair,allowingittocontrolbuoyancy.Whenthesubmarineisonthesurfacetheballasttanksarefilledwithair,loweringthesubmarinesdensityandallowingittofloat.Conversely,theballasttanksarefloodedwithwater,increasingtheoveralldensity,allowingthesubmarinetosink.

Conclusion+FutureWork:Duetowaterproofingfailures,theR.O.Vwasnotsubmergedkeepinginmindelectricalsafetyconcerns.Ideally,IP68waterproofmilitaryconnectorswouldhavebeenusedtoroutethenecessarywiresintothebox.Duetofinancialand>merestraintstheseIP68militaryconnectorswerenotabletobeused.Thedifferentcomponentsweretestedindividually,andsuccessfullyintegratedintoonesystemcontrolledbytheXbox360remote.Theballastsystemdesignwillallowbegercontrolofdepth,asopposedtothecommerciallyavailabledesigns.Theincorporatedcamerasystemallowstheusertopanand>lttheviewwithagreatdegreeoffreedom,withouthavingtomovetheR.O.V.BecauseoursystemisbasedonanopensourcesoVware,itwillallowforfutureimprovementsandadd-ons.Movingforward,wehopeanotherseniorcapstoneteamcancon>nueourworkontheR.O.V.Immediatechangesincludecompletewaterproofingofthecomponentsbox.Addi>onally,bulkingupthefeaturesoftheR.O.Vtomakeitamoreversa>lesystemasidefromleisureexploringissomethingtolookinto.Forexampleaddingawi-fibuoyallowingittobetether-less,orincorpora>ngmeasurementtoolslikepHlevels,orabnormali>esinthewater:suchashighCO2levels.

IMUControlsystem:Aniner>alnaviga>onsystem(INS)wasimplemented.Foroursystem,aniner>almeasurementunit(IMU)wasused,asitisthesmallestandmostcost-efficientsolu>onanditallowsforthebestinterfacingwithourPi.TheIMUprovidesfeedback,givingandusouractualorienta>on.AnerrorsignalwouldbegeneratedaVercomparingourdesiredorienta>ontotheactual.Usingthiserror,oursystemwouldproduceanoutputtostabilizetheR.O.V.

Figure7.IMUcontrolsystemblockdiagramRaspberryPiInterface:TheprocessingboardchosenwastheRaspberryPiModel3B.ForthepurposeofthisROV,theprogramminglanguagefavoredwasPython,duetotheAPIfortheXbox360controllerna>velyrunningonPythonandhavingalargeamountofonlinesupport.TheRaspberryPihasanonboardGPU(GraphicsProcessingUnit)whichwasvitalfordisplayingvideofeedfromthecamera.Withtheuseofitsbuilt-inWi-Fi,theRaspberryPiwouldalsoallowforsomefutureimprovements,suchasanun-tetheredsystem,withoutrewiring.PowerDeliverySystem:TheR.O.V.’spowerdeliverysystemincludesaninternalpowersourceoftwoLi-Pobagerieswasused.WeusedtwoGensAce11.1V,1550mAh/17.2Whbageries.Accordingtopreliminarycalcula>ons,runningallsixmotorsatonceatfullthrust(worst-casescenario)shouldprovideabageryrun->meof7-8minutes,whichisrespectablewhencomparedtotherun->meofcommercialairdrones.

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Pitch PID Controller

Roll PID Controller

Yaw PID Controller

Throttle Input PωM_in (Right Trigger)

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Figure2.CADmodelofthepropellersdesignedfortheHobbykingST3508motors

Figure1.CADmodelofthechassisdesign,showingthemotorplacements

Figure3.CADmodelofthecomponentsbox

Figure4.R.O.Vcontrollerlayout,usingXbox360remote

TrinityCollegeEngineeringDepartmentDepartmentTechnician:AndrewMusulinOurAdvisor:ProfessorHuang

Figure5.Electricalcomponentslaidoutonacrylicboard

Figure6.CompletedR.O.V.