Modular Accessibility Ramp

7/27/2019 Modular Accessibility Ramp

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MAE494:DesignProjectFinalReport

DESIGNOFMODULARRAMPFORWHEELCHAIR

ACCESSIBILITY

Group 7: Alexander GrenningDaniel Lawrence Robert CrabtreeMatt Schwenzfeier Matt Schwartz


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TableofContents

1.ProblemDescription.3

1.1ProblemStatement.4

2.CustomerRequirements5

2.1ListofCustomerRequirements.5 2.2DiscussionofMostCriticalRequirements.6

3.EngineeringSpecifications7

3.1ListofEngineeringSpecifications....7

3.2DiscussionofCriticalEngineeringSpecifications..8

4.ConceptualDesign.9

4.1ConceptGeneration(Divergence)..9

4.2ConceptSelection(Convergence).10

4.3DiscussionofConceptualDesign10

5.EmbodimentDesign.....11

5.1DescriptionofMajorSubsystems/Components....11 5.2CriticalTechnicalChallengestobesolvedinDetailedDesign.....12

6.DetailedDesign....16

6.1ProductFunctionality.18

6.2DesignofTrackSections..18

6.3DesignofFoldingPlatform.19

6.4PerformanceAnalysis...20

6.5CostAnalysis.22

6.6SafetyAnalysis.23

6.7DiscussionofFinalDesign..23

7.TestingandRefinement.24 7.1TestApproachandFindingsforFunctionalityandFeasibility..26

7.2TestApproachandFindingsforTolerancingandMachinability.27

7.3TestApproachandFindingsofAssembly28

7.4ImpactofPrototypingFindingsonourDesign.28

8.Production........29

8.1ProductionofthePlatform29

8.2ProductionoftheTrackSections..29

8.3ProductionoftheTrackConnections29

8.4Assembly30

9.Conclusion..30 9.1AssessmentofSuccess.30

9.2OpportunitiesforFutureDevelopment..31

10.References33


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Appendix....34

A.1CustomerRequirements......34

A.2EngineeringSpecifications......35

A.3HouseofQuality........38

A.4ConceptGenerations........39

A.5ConceptSelection........41

A.6EvolvedArchitecture......42

A.7LargerCADModels......43

A.8AnalysisDocuments........45


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1.ProblemDescription

Handicappedpersonsarefacedwiththeproblemofmobilityonadailybasis.Aneverydaytriptothe

storeornightouttoafavoriterestaurantisnotsoeverydayforahandicappedperson.Stairwaysandwalkways

havebeenpredominantlydesignedforthoseofuswhohavetheabilitytofreelywalkaroundanduseourlegs;not

forthoserequiredtouseawheelchairorothermobilityaidingdevice.Handicappedpersonsarerequiredtoadapt

andchangetheirwayoflifeduetotheirdisabilityandinabilitytoeasilymovefromplacetoplace.Themost

commonproblemfacedbythosewhoarerequiredtousemobilityequipmentisgettingupanddownstairs/angled

planes.Homes,buildings,andeverydaypathwaysarecommonplacesthatlimitahandicappedpersons

capabilitiesduetothefrequentuseofstairsinthoselocations.Somenumbersonhandicappedpersonsaccording

tothedatacollectedinthe2010U.S.Census(http://www.census.gov/prod/2012pubs/p70-131.pdf)areasfollows:

56.7millionpeoplehavesometypeofdisabilityintheU.S.whichequatestoabout18.7%ofthepopulationoroneineveryfivepeople.Thatnumberisextremelyclosetotheestimatedvaluediscussed

aboutprovidedbytheUniversityatBuffalo.

30.55millionpeopleages15andolderhaveadisabilitythatgivesthemtroublewalkingorusingstairs.Specifically,22.262millionpeoplehavetroubleusingstairs.

Asyoucansee,thenumberofpeoplethataredisabledinourcountryissignificant.Thesenumbersprovethat

thereexistsalargepopulationofpeoplethathavetodealwithmobilityissuesonadailybasis.Figure1below

showsthedistributionofthosewhouseaccessibilityaidscurrentlyonthemarket.

Figure1Distributionofthosewhouseaccessibilityaidsthroughouttheirhome.

http://dsc.ucsf.edu/pub_listing.php?pub_type=ReportReport#14

Asshownabove,thosewhoarephysicallydisabledarecurrentlyforcedtoliveinhomesandplacesthatcan

accommodatetheirneeds.Thiscanbecomeastruggleasmostpeoplewhosufferfromimmobilizingdisabilitiesare

notbornwiththeissue.Thosewhoarenotbornwiththedisabilitymaybeforcedtomovehomesandor

restructuretheirhome.Theserestrictionsforcepeopletochangethewaytheyhavebeenlivingtheirlifesimply

becausethereisnowayforthemtogetupanddownstairs,oraroundsociety.

Therearecurrentlymanydifferenttypesoframpsandliftsonthemarketbutthereisyettoexistaportable

andversatilerampthatcanbeusedwithease.Theportablerampscostaround$1000butcanonlycoverasmall

amountofstairsbecausetheytakeaslightangletoincreasetheusercomfortwhengoinguptherampwhich


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restrictstheheightcoveredduetoforceissues.Theyareeasilyportablebutcannotbeusedinlargestairsituations

duetotheanglerestrictions.Also,apersonmustphysicallymustthehandicappedpersonuptheramp.Theother

groupiselevatorswhichcostaround$5000butneedtobeattachedtothestairsandarenotportable.They

automaticallycarrysomeoneupthestairsbutcanonlybeusedononesetofstairs.Creatingasystemthatisboth

portable,butversatileandcoversallstairheightswhilemaintainalowcostisessential.

1.1ProblemStatement

Theinformationpreviouslydiscussedleadstotheintroductionofourproblemstatement:

Addresstheneedtomakethephysicallydisabledanactivepartofsocietybycreatingalightweight,versatile,

rampingsolutionforeverydayuse.Thedesignmustbeportable,easytosetup,andreliable.

ObjectivesforProblem:

Designasolutiontoaidthosewhouseawheelchairorpowerchair Designmustbeabletohandlemoststairheightswithonecollectivesystem Maintainalowcostforthesystembetweencostofportablerampandelevatorsystems Systemmustbeportableandeasytotransport(aslightweightaspossible) Designmustbeuserfriendly(easytoassemble)andcomfortablefortheuser/operator Solutionmustbesafe,strong,andreliable

ConstraintsforProblem:

#ofpersonsrequiredforset-up Balancebetweenweightandstrengthofmaterials Usesecure/reliabledesigncomponentswhilemaintaininglowcost VariationsbetweenstairsandsizesTodeterminethesuccessofourproject,anumberoffactorswillbeconsideredandmeasuredthroughboth

prototypetestingandanalyticalmodels.Thesemeasuresinclude:

Prototypingcriticalsectionsofourdesigntoprovefunctionalityaswellasintegritywewillprototypeourmostcriticalsection(trackconnections)toprovewecanholdtolerancesandeasilyassemblethem

together.Wewillbuildascalemodeloftherampandtracksoutofwoodtoprovefunctionality.

Measuringeaseofassemblyallowingfriendsandunbiasedpersonstotestourequipmentwilltellushoweasyourtracksconnecttogetherandfunction.

MeasuringVersatilitywewillmeasurehowmanystairsthedesigncanconfinetobycombiningcertaintracksandanalyzinglengthsandconfigurations.

MeasuringProofofConceptusingthemodeloftherampandtrack,wewillbeabletoconveyourideatothosewhorequiretheuseofasystemlikethisaswellasthosewhowouldneedtohelpoperate.This

willprovidenecessaryfeedbackontheoverallconcept.


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FEAanalysisperformtestingonthestrengthoftracksectionstoensuretheywillbeabletowithstandtheforcesthatwillbegeneratedaswellasallowustodetermineifmaterialchoiceswillbesufficient.

Theremainderofthisreportwilloutlineourdesignprocessusedtodevelopasolutiontotheproblem

discussedabove.Wewilldiscusssectionssuchascustomerrequirements,engineeringspecifications,concept

generation,detaileddesign,prototypingandtesting,etc.Thesesectionswillprovideanoverviewtothestepswe

tooktodesignoursolutionandwaysinwhichwerefinedourdesign.

2.CustomerRequirements

Torepresentcriticalend-usersandothersaffectedduringthelifecycleofoursystem,weconsideredthe

followinggroupstodevelopcustomerrequirements:

Consumers-PeoplewithDisabilities(C) FamiliesofthosewithDisabilities(F) InsuranceCompanies(I) NationalGovernment(G) EnvironmentalProtectionAgency(E) BusinessesandMunicipalBuildings(B)

(TheletterinparenthesiscorrespondtothecustomerrequirementstheybelongtoinTable1andAppendixA.1)

Weinterviewedactualhandicappedpersonsandthosewhousethecurrentdevicestobetterunderstand

problemstheyhavewillcurrentsystemsaswellaschangestheywouldliketoseemade.Theemphasisofthese

customergroupsisontheindividualconsumerssincesomanypeopleintheUnitedStatesrequiretheuseof

mobilitydevices.Consumersaretheoneswhoactuallypurchasethesystemandusethedesign.

2.1ListofCustomerRequirements

Wewereabletocomeupwithalistofcustomerrequirements,showninTable1,wethoughttobe

importantthroughtheinformationgainedbyinterviewsandresearch.Thetablehaseachcustomerrequirement

alongwithitscorrespondingimportance.Afullexplanationofeachcustomerrequirementcanbefoundin

AppendixA.1.

CustomerRequirement Importance

Reliable(C,F,I,B) 9.5Safe(C,F,I,G,B) 9.5

Easytosetup(C,F,B) 8.8

UserFriendly(C,F) 8.5

Versatile(C,F,B) 7.8

MeetsRegulations(C,F,G) 7.5


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CostEffective(C,F,I,B) 6.0

Efficient(C,F,B) 5.0

WeatherResistant(C,F) 4.0

SafePowerSource(C,F,E,B) 3.8

EnvironmentallyFriendly(G,E) 3.5

Table1-Customerrequirementcriteriaandrespectiverankindecreasingimportance

2.2DiscussionofMostCriticalRequirements

Thoughtherearemultiplecustomerrequirements,wefocusedprimarilyon6ofthembecausethey

seemedtobethemostimportantandsignificantfactorsindesigningasuccessfulsolution.

Reliable(C,F,I,B)Thedesignmustbereliablebecausetheuserisgoingtowantthesolutiontowork

witheasewhenneeded.Thereshouldnotbeissueswiththedesignnotcooperatingwhentheuser(s)arereadyto

operate.Areliabledesignequatestoahighqualitysystemwhichinturncreatesasuccessfulsolution.

Safe(C,F,I,G,B)Thedesignmustbesafebecausetheuserisgoingtowanttouseaproductthatwith

safelygetthemfrompointAtopointB.Safetyisoftheutmostimportancebecauseasolutionthatlackssafetywill

notsellandwillcarryalongabadrep.Adesignthatisnotsafecouldresultinfurtherinjuryandharmwhichis

theoppositeofwhatourproblemsolutionis.

Easytosetup(C,F,B)Thedesignmustbeeasytosetupbecausethepersonthatissettingthesystem

upwillnotwanttospendalotoftimeconfiguringandconnectingmanypiecesthatrequireintricateconnections.

Simplerisbetterandmakesthedesignmoreappealingbyrequiringlessworkandtimetosetup.

UserFriendly(C,F)Thedesignhastobeuserfriendlybecausetheuserwillwantsomethingthatis

intuitiveandeasytounderstand.Acomplexsystemwithcomplexdirectionswillrequiremoretimeandworkto

operatewhichwillnotbeappealing.

Versatile(C,F,B)Thedesignmustbeversatileasthatisoneourmainsellingpoints.Theversatilityof

ourdesignwillallowustoshowthemanysituationsinwhichthissystemissuperiortoothers.Theuserswillprefer

asystemthatpossessestheabilitytobeusedinmostsituations.

CostEffective(C,F,I,B)Thedesignmustbecosteffectiveasaconsumerwillnotwanttospendatonof

moneythattheymaynothaveonaproductwhenthereareothersinthemarketwithsemi-similarfunctions.

Moneyisalwaysadrivingpointofanyproductandsolutionandthesmallerthecost,themoreappealingthe

system.

Customerrequirementsareamajordrivingfactorinthedesignprocess.Oursolutionisdesignedforthe

customersandtheneedstheyrequire.Next,anothermajordesignprocessfactorwillbediscussed;engineering

specifications.


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3.EngineeringSpecifications

Todevelopourengineeringspecifications,weusedthelistofcustomerrequirementsinTable1and

identified20engineeringspecifications.UsingtheHouseofQuality,AppendixA.3,relationshipstocustomer

requirementswereidentifiedtosupportcalculationoftherelativeimportanceofeachengineeringspecification.

3.1ListofEngineeringSpecifications

Table2showsthelistofengineeringspecificationsalongwiththerelativeimportanceofeach

specification.TheseimportancesarederivedfromtheHouseofQualityshownAppendixA.3.

EngineeringSpecifications Importance(1-10)

NumberofStepstoAssemble(~5) 8

RangeofElevationChange(~10-12Stairs) 8

TimetoAssemble(~5Minutes) 8

Reliability(~0FailuresperYear) 7

NumberofStepstoOperate(~2) 7

WeightCapacity(~650lbs.) 7

WeightofSystem(~100lbs.) 6

PriceofSystem(~$2,500) 6

NumberofStairRiseConfigurations(~MaximizeUnabletoPinpointValue) 5

MaterialStrength(~60MPa) 5

ForceRequiredtoOperate(~0lbs.) 5

NumberofSafetyFeatures(~MaximizeUnabletoPinpointValue) 5

NumberofCodesFollowed(~MaximizeUnabletoPinpointValue) 5

PowerUsed(


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3.2DiscussionofCriticalEngineeringSpecifications

Basedonrelativeweights,thereare7engineeringspecificationsthatwewillfocusonduetotheir

relationshiptotheproblemandimportancebasedontheintentofthedesign.

NumberofStepstoAssembleForobviousreasons,thenumberofstepstoassembledirectlyinfluencestheeaseofsetuprequirement.Thenumberofstepsrequiredforanyproducttobereadytouseshould

beminimizedtoeasetheburdenonthecustomer,oroperator.

RangeofElevationChangeInordertobetteraccommodateasmanyhandicapconditions,andenvironmentalsettingsaspossible,themaximizationofelevationchangewouldbenecessary.Notonlydo

wewanttobeabletocoverasmanystairsaspossible,butinadditionwewanttobeabletoadjustfor

anynumberofstairs.Forexample,ourgoalcouldbetoascendat.

TimetoAssembleThedirectcorrelationbetweennumberofstepstoassembleandtimetoassembleisalsointuitive.Itispossiblethatthenumberofstepstoassemblecanremainlow,whilethetimeto

assembleishigh,thereforeitwasnecessarytoimplementthedurationofassemblyaswell.

ReliabilityFromasafety,cost,andreliabilityperspective;thenumberoffailureswhichthisproductexhibitsshouldofcoursebeminimized.Beingthattheproductisintendedtobemobileandnotfixedin

onelocationmakesdesignforreliabilityadifficulttask.Wewillaimforsixsigmareliabilityasafailurein

thissystemcouldbedeadlyfortheuser.

WeightCapacityMoreoftenthannottheweightofsomeonewithlimitedmobilitywillbegreaterthansomeonewhocanconvenientlymovearoundandburncalories.Itisforthisreasonthatweightcapacity

willbetakenseriously,withtheappropriatefactorofsafetyinmind.Wehaveestimatedausingthe

weightofaheavymotorizedwheelchairaswellasaheavyuserthattheweightcapacitywillneedtobe

around600poundsbeforeafactorofsafetyisconsidered.

WeightofSystemAgain,forportability,theunitwillhavetoweighaslittleaspossible.Thepersonwillbeabletorollthesystemwhenintransporthoweverthesystemwillhavetobeliftedintoavehiclefor

longdistancetraveling.Wedonotwantweighttobeafactorthatlimitsourcustomerrange.

PriceofSystemEventhoughinsurancecompanieswillbecoveringalargepartofthisdevice,forpeoplewithdisabilitiesandtheirfamilies,theburdenofpayingforthedeviceshouldbeascosteffectiveas

possible.Thedifficultypresentedinthisestimationisthelackofdirectcompetitionourproducthas.We

arecreatingaproductwithnosimilarcompetitorsonwhichtobaseaprice.

(AcompletedescriptionandlistofallengineeringspecificationscanbefoundinAppendixA.2)

Fromtheroofofthehouseofquality,wefoundthatthereweremanycorrelationsbetweenthe

engineeringspecifications.Wefoundtheretobeverystrongcorrelationsbetweenmaterialstrengthandweight

capacity,numberofstepstoassembleandassemblytime,numberofsafetyfeaturesandnumberofcodes

followed,reliabilityandmaintenancetimerequired,reliabilityandnumberofrustresistantparts,andlastly


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numberofstepstooperatealongwithtimerequiredtooperate.Itwasalsofoundthatthespecificationsof

materialstrengthaswellasreliabilitygenerallyhadalotofpositivecorrelationstootherspecifications,while

characteristicssuchasrangeofelevationandnumberofstairriseconfigurationshadanextremelylargenumberof

negativecorrelationswithrespecttootherengineeringspecs.Thesecorrelationsplayedanimportantrolein

decidingwhatweneedtomaximize,minimize,andhowmuchwillthataffectothercharacteristicsrelatedtoits

field.

Engineeringspecificationsputavaluetoourcustomerrequirementsandmakethemeasierto

understand.Thespecificationsarethespecificvaluesinwhichwewillaimtotryandhitasfarascharacteristic

values.Next,webegangeneratingconceptsandpossiblesolutionstotheproblemstatedabove.

4.ConceptualDesign

Theconceptualdesignphaseinvolvedbothidentificationofpotentialconceptsandselectionofasingle

concepttofocusonforthesemester.Eachaspectisdetailedhere.Acompletelistofallconceptscanbefoundin

AppendixA.4.

4.1ConceptGeneration(Divergence)

Todevelopconcepts,ourgroupusedthegallerymethod.Thisstagewasdoneasagroupovera2hour

period.Wewereabletogenerate38concepts.SeveralofthoseconceptsareshowninFigures2-6.Largerimages

ofsomeconceptsalongwiththeirdescriptioncanbefoundinAppendixA.4.

Figure2Pulley/CableRampSystemFigure3ExtendableRampFigure4LegoRampDesign

Figure5TanksTracksonBottomofWheelchairFigure6AdaptableWheels


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4.2ConceptSelection(Convergence)

Toselectasingleconceptourgroupfolloweda4stageprocessbasedonfeasibility,voting,andaformal

decisionmatrix.

4.2.1FeasibilityAnalysis

Webegantonarrowourconceptsdownbyperformingfeasibilityanalysisasagroupwherewelookat

howfeasibleeachalternativeactuallywas.Thisallowedustogetthenumberofconceptsdownto24concepts.

4.2.2VotingProcess

Nextwecollectivelyvotedontheremaining24concepts.Eachgroupmemberwasgiven15votesin

roundonetodistributeontheconcepts.Amaximumof5votesperideawasestablished.Allowingmorethanone

voteperideaallowedforsomememberstoshowmoresupportforideastheythoughtwerebetter.Wefollowed

thatupwithasecondroundofvotingwhereeachgroupmemberwasgiven9votesandcouldplaceamaximumof

3votesperidea.Thesetworoundsofvotinghelpedusnarrowthefielddowntoourtopfiveideas.

4.2.3DecisionMatrix

Lastly,wetookthesefiveconceptsandplacedthemintoadecisionmatrix.Thismatrixcanbefoundin

AppendixA.5.WeusedourtopeightengineeringspecificationsfromtheHouseofQualitytobetterrankthetop

five.Wechosethetopeightbecausetheyweretheonesthatmostappliedtoourintendeddesign.Thedecision

matrixresultedinthetopchoicebeingtheLegorampdesign,closelyfollowedbytheextendablerampandtank

tracks.Theresultswereveryclosefromthematrixandwewerenotsureifweweresetononeconcept.Wedecidedthatwewouldmoveforwardbycombiningdifferentaspectsofeachconcepttodesignthebestsolution.

Combiningaspectswelikedfromeachconceptallowedustotaketheadvantagesfromeachideaandcombine

themtogether.WehaddecidedonahybridconceptthatwouldlaterbecalledtheModularRampSystem.

4.3DiscussionofConceptualDesign

Throughourconceptgeneratingprocess,wewereabletosuccessfullygeneratemanydifferentideas.

Fromtheseideas,wewereabletousevarioustoolstonarrowtheconceptsdowntoanumberinwhichwecould

useadecisionmatrixon.Theseconceptsallseemedtosolvetheproblemweintendedonsolvingbecausethey

are,intheory,wouldgetthehandicappedpersonfromA(onesideofstairs)toB(othersideofstairs).Wewere

abletodecideondesigningafoldingrampsystemthatwasportablewithconnectingtracksofdifferentlengths

andmechanicallypowered.Thisdesigncombinedaspectsofafewofourconceptswhichgaveusabetteroverall

designconcept.Thedesignwillallowustobuildalightweight,cost-effective,andeffectivesystemtohelpthe

physicallydisabledgetupanddownstairs.


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5.EmbodimentDesign

Beforedevelopingadetaileddesign,weestablishapreliminarysystemlayoutwhichinFigure7.An

explodedviewofoursystemisshowninFigure8.

Figure7-PreliminarysystemlayoutFigure8Explodedviewofsystemlayout

5.1DescriptionofMajorSubsystems/Components

WebeganourinitialmodelingbackinMAE451.Wewereabletomakesubstantialimprovementsfromourdesign

throughoutthissemester.Whenwebegantoputthoughtintoloadingandfunctionality,werealizedourdesign

neededtoimprove.First,thetrackschangedfromaU-Shapetoarollercoastertypedesigninwhichweusedtrack

rollerstoensuretherampcouldnotfallbackwards,wentupstraight,anddidnotslideoff.Thetrackconnections

changedaswell.Wemadethetrackavailableindifferentlengthssothatmultiplesectionscanbecombinedto

accommodatedifferentstairheights.Thetracksarenowconnectedusingamaleandfemalepartconnectedwitha

pintoprovideaneasymethodofsetup.Also,webroughttheconceptofaplatformintothedesign.Theplatform

addsseveraladvantagestothedesign.First,theplatformallowsthesystemtooperatewithalltypesofwheel

chairdesigns,regardlessoftrackwidthbetweenthetires.Also,theplatformfoldsupatthebottomoftherampto

allowthewheelchairtoloadatverylowangle.Theplatformthenispulledintohorizontalpositionatwhichthe

usercanbepulledupthestaircase.Thewinchisnowconnectedtothetopoftheplatformtoremovetheneedfor

apulleyandalsofreeupsomespacesothatwedonothavetoworryaboutthecablegettinginthewayonthe

bottom.Thisreducescost,complexity,andsetuptime.Thewinchisnowcontainedonthebottomoftheplatform

inahubtoallowforeasyoperationandstoragewhichalsocontainstherechargeablebatteries.Thismakesit

easiertoturnthewinchonandoffaswellasremovestheneedforadditionalpartsonthebottomconsole.The

topandbottomconsolesarenowdesignedsothattheplatformneveractuallycomesoutofthetrack.This


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provideseasypackingandhelpstherampfoldup.Lastly,weaddedwhatwerefertoaslandinggear,ora

damper.Thisisarackandpinionsystemwillhelptheramponthewaydownwhilecollapsingandprovideaback

forcethatwillabsorbsomeoftheforcewhiletherampcollapses.

5.2CriticalTechnicalChallengestobeSolvedinDetailedDesign

5.2.1DesignforAssembly

Theassemblydesignphaseforthedevelopmentofthemodularrampsystemwascriticaltothesuccessof

thisproject.Theabilitytobeassembledanddisassembledquicklyandefficientlyfortheoperationalassemblywas

theforemostconcern.Preliminaryassemblyofvariouscomponentsbythemanufacturerwouldofcoursebe

important,buttimewouldnotbeashighofanimportance.

OperationalAssembly

TrackAssembly

Assemblyoftheindividualtracksectionswhicharetobeavailableinvaryinglengthswillbeaccomplished

throughtheinterfacingoftwolargeconnectingpieceswithmaleandfemalesides.Theseconnectionpointswere

placedontheoutersideofeachtracksectioninordertolowertheriskofinterferingwithstairgeometryandor

platformmovement.Uponslidingthisconnectiontogetherapincanbeinsertedverticallyintothemalepart

extrudingjustbeyondthelimitofthefemaleconnector(seeFigure9).Tolerancesforthesepartsshouldbe

accuratetoabout+/-0.005whichwebelievewillallowforatightenoughfittopreventflexingofthe

connections,butwillstillbeeasytoslidetogetherinanefficientmanner.

Figure9TrackConnectionPoint;AssembledView


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PlatformAssembly

Theproposeddesignfortheplatformwhichwillholdboththemobilitydeviceandthedisabledperson

containsseveralcomponents.Thetopplatformcomponentisattachedtothevertical,lowersupportbya

stationarypinhingewhichwillnotberemovedbytheoperator.Configuredtotheundersideoftheplatformisa

winchandbatterycombinationwhichwillalsonotberemovedbytheoperator.Theonlyassemblyrequiredfor

theplatformisforthefrontandbackrollerstobeinsertedintothetracksectionspreviouslyconfigured,in

additiontoconnectingthewinchcabletothetopmodule,whichwillbediscussedbelow.SeeFigure10below;

whichgivesavisualrepresentationoftheplatformassemblyasawhole.

Figure10Platformassembly:assembledviewofboththehorizontalandverticalsupport,placedinthetracks.

WheelchairInterfaceAssembly

Afterthemobilitydevicehasbeenloadedontotheplatformitwillstrappedontotheplatformbyratchet

straps.Oncethewinchhaspulledtheplatformtothetopofthestaircaseitcanbeunloadedbydisconnecting

thesetethers,effectivelycreatingasimple,efficientmeansofinterfacingtheusertotheproduct.

Top&BottomConsoleAssembly

Connectingthetopandbottomconsolestotheindividualtracksectionsisnearlythesameasconnecting

theindividualtracksegmentstogether.Inthesamemanner,thisassemblywillrequiretheinsertionofalocking

pinfollowingthematingofthetwosegments.


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ManufacturingAssembly

Platform

Thewinchandbatterysetupswillhavetobeattachedtotheplatformduringmanufacturing.Theflapon

theleadingedgeoftheplatformtoaidintheloadingofthewheelchairwillalsohavetobeattachedpriorto

shipmenttotheenduser.Connectingthehorizontalandverticalsupportstogetherwithasteelbearingpinwillbe

thefinalassemblyprocessrequiredfortheplatform.

TrackConnection

Thetrackassemblywillbemanufacturedaftertheinterfacebetweenthemaleandfemaleconnectorshas

beenestablished.Priortothis,thetrackcomponentsareidentical,andamaleandafemalepiecemustbe

attachedusingeightscrewsapiecetoensureasecurefitbetweenthetrackandthemale/femaleparts.Afterall

thescrewshavebeenthreaded,alockingpinwillbeusedtosecuretheconnectionbetweenthemaleandfemale

component.Thelockingpinfreedomwillalsoprovidevariabilityinthemale/femalesectionlengthsdependingon

theusersneeds.

Top&BottomConsole

Thetopandbottomconsolewillbeattachedinasimilarmannertothetrackconnections.These

componentswilluseeightscrewsapiecetothreadandestablishthemaleandfemaleparts,thenalockingpinwill

beplacedintoholdthesecomponentsinplace.Theonlydifferenceisthatinsteadofhavingfreedomwhereeach

trackconnectingpinisplaced,thesemodulesmustbeplacedinafashionsothatthebottomconsoleisconnected

tothefirstpieceoftrack,andthetopconsoleisattachedafterthelastpieceoftrack.

5.2.2DesignforVariability

Rampassemblymethod-usessectionsnumbered1-4(correspondingtonumberofstairs)o Piecescanattachinanyordero Canbeusedfor1-10stairsintheregularpackageo Highercapacitywithspecialorder

UpperandLowerconsoleallowforvariationinstairangleo Ourproductisdesignedtofollowbuildingcodesforthesteepestallowablestairs

Decreasingtheangleofthestairswillsimplyleantheuserforwardslightly,maintainingcomfortandsafety

Flexibleangleofconsoleallowsforsomevariationinstairdimensions Productdesignforworstcasescenario

o Productdimensions,weightcapacity,andstrengthdesignedfortheheaviest,largestwheelchairs


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o Factoryofsafetyof2ensuresthatourproductwillnotonlymeetthe99%percentilebutextendtoeventheworstcasescenarios

Widthandshapeofwheelchairnonfactoro Platformdesignallowsforwheelchairofanywidthasopposedtosetwidthtrackso Alltypesofwheelchairswillbesafeandsecure

Winchisconnectedtoplatform,nottothewheelchairframe Safetystrapshaveratchetdesigntosecuretoanywhereontheframe

5.2.3DesignforManufacturing

Theabilitytomanufacturetheproductanditspartsisanessentialpartofdesign.Ifyouarenotphysically

abletoproducethepartsneeded,youareunabletocontinueonwiththedesignprocess.Theabilitytokeepcosts

downwhenmanufacturingtheproductcanincreaseprofitstremendously.Thewinch,battery,pulley,pins,etc.are

alloutsourcedandnotseparatelymanufacturedin-house.Byoutsourcingcertaincomponents,weareabletocut

downonourcost,time,andeffortspentonadditionaldesigns,specificallyforthewinch,battery,pulleysystem,

pins,andotherparts.Whileengineeringspecificpartssuchasthewinchandbatterytobeidealforourdesign

wouldberational,theseoutsourcedpartswillbemorethansufficientforourprototypeneeds.

Althoughafairnumberofpartsarebeingoutsourced,thereisstillalargeneedforinhouse

manufacturing,specializedforthedesignofthetopmodule,bottommodule,andrampsections.Stockpartswill

beusedtohelpcutcostsandminimizethenumberofpartsmanufacturedin-house.Therampwillbeinjection

moldedoutofHDPEallowingforhighstrengthandversatilityasstockpredrilledholesmakeiteasyfor

attachment.TheHDPEwillgiveusalightweightadvantagewiththeramp.Thetopandbottommoduleswillbe

madeoutofaluminumstockandwillalsorequireamilledholeononeface,sothattheplatformcaneasilyslide

frombottomtotop.Ourmanufacturingprocessiskeptverysimpleasallboltsandpinsarethesame,making

everyholeplacementuniformtominimizeerrors.


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6.DetailedDesign

Figure11OverallAssembly;NumbersCorrespondtoBOMFigure12WheelinTrack

Figure13LowerSectionFigure14TrackConnection

**PicturesofourdesignevolutionmaybefoundinappendixsectionA.6withmoredesignphotosinA.7**


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Console Part# Description Quantity TotalPrice Location

Tracks 1.01in.AluminumHollowBarStock

2x2x241 204.00

MetalsDepot:

T3214

1.02 TrackRoller 4 107.44McMaster:

6461K19 1.03

AluminumFlatBarStock

1x2x81 95.12

MetalsDepot:

F412

Console 2.013/4inAluminumHollowTubeStock

61 11.16

McMaster:

1658T51

2.021/4in.AluminumHollowBarStock

2x2x61 56.68

MetalsDepot:

T3214

Platform 3.01 HDPEBase 1 56.60

3.02 1/8in.AluminumHollowBarStock1x1x10

1 25.70 MetalsDepot:T3118

3.03 RatchetStrap 4 62.88McMaster:

29925T23

3.04SteelDiameterSolidRoundStock

4ft.1 5.72

MetalsDepot:

R112

Powertrain 4.01 Winch(2000lbCapacity) 1 69.99NorthernTool:

14190

4.02 12VBattery(30Ah) 2 201.49AtBatt:

24379

4.03 2.533Amp14AWGWire 1 0.93McMaster:

7587K973

Misc. M.01

LockingPins,10total:

6fortracks,2perconsole

1/4Diameter,1.8Usable

10 19.50McMaster:

98404A138

M.02

LongBolts,80totalneeded:

64fortracks,16forconsole

8-32,1.125long

2 11.86McMaster:

92196A200

M.03ShortBolts,80totalneeded:64fortracks,16forconsole

8-32,1.5usable

1 4.51McMaster:

92196A194

M.04

U-Bolt,3totalneeded:

1forpowertraincage,1fortop

console,1forfrontedgeofplatform

3 7.62McMaster:

3035T11

Table3BillofMaterials


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6.1ProductFunctionality

RAMPASSEMBLY

Tracksectionsmustfirstbeconnectedtoapredeterminedlengthdependingonthestaircaseheight Tracksectionsareconnectedviaquickconnectpinthroughmale/femalepartsattachedtothetrack

sections

PLATFORMCONNECTION/LOADING

Platformrollersslideintothetracksectionsandplatformfoldstoallowforeasyloading Platformlocksinanascendingpositionwhichprovidestheriderwithalevelplatformsurfacetoprevent

sliding/rollingoff

ASCENDINGTHESTAIRCASE

Uponcommandfromthewinchremote,thewinchpullstheplatformupthestaircaseandresultsintheabovedescribedfoldingoftheplatformusingaseriesofsafetylockstopreventtheplatformfrom

unfoldingduringoperation

UNLOADING

Aftertheplatformhasbeenraisedtothetopofthestaircase,unloadingisassimpleasdisconnectinganyrestraints,androllingtherideroff

DISASSEMBLY

Platformreturnedtoloadingposition,removedfromtracks Tracksdisassembledandstored

6.2DesignofTrackSections

Thefollowingfactorswereconsideredinthedesignofthetracksections:

Weight Strength EaseofAssembly Dimensions Cost Manufacturability


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MaterialSelection

Inordertooptimizetheinfluentialfactorsabovewithregardstomaterialselectionthe

proposedmaterialforthetracksectionswasaluminum.Aluminumiscommonlyavailable,easyto

machine,andlightweight.Withayieldstrengthofabout55MPaaluminumsstrength,ifdesigned

efficientlywillprovideexcellentmaterialpropertiesforthetracksections.

WeightOfPart

Density(wolframalpha.com):0.09754lb/in3

Volume(typicalstaircase:13in.lengthsection):19.5in3

SingleTrackSectionWeight:1.90lbor0.17lb/in.

WeightofAssembledTrack([email protected].):27.20lb

6.3DesignofFoldingPlatform

Figure15Transparentplatformstructureshowninthefoldedloadingposition

Theplatformdesigniscriticaltotheoperationofthemodularrampsystem.Thefollowingarethe

maindesignattributesconsideredinthedesignoftheplatform.


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Theplatformshouldfolduptoallowthehandicappedpersontoeasilyrollupontothehorizontalsupport

Astheplatformraises,thehandicappedpersonshouldbeinalevelpositiontopreventanyfeelingoftippingbackwards/forwards

Duringoperation,whenthetrackcomponentsareallassembled,theplatformshouldremainheldintothetrackstoallowtheunittofoldupcorrectly,andsothatitmayre-ascendthestairs

ifnecessary

MaterialSelection

Aswiththetracksectionsdescribedabove,weightshouldbeminimizedforthefoldingplatform,

whilemaintainingstrength,functionality,anddurability.HDPEwasselectedfortheplatformsinceits

strengthtoweightratioisexcellentwithayieldstrengthof20-25MPaandadensityof0.0344in3

(wolframalpha.com).HDPEisoftenusedinthepackagingindustry,andhasbeenaprovenloadbearingmaterialusedinthemanufactureofpalletsforshipping/transportofproducts.

ApproximatevolumerequiredforinjectionmoldedHDPEplatform:0.920ft3

6.4PerformanceAnalysis

TrackConnectionFEA-Displacement&StressAnalysis

Todeterminewhetherourtrackprofiledesign,andmaterialselectionwasexceedinglyadequate

fortheapplicationweperformedseveralsimulationsonthesolidmodelofthetracksection.Notethat

thesupportsintheactualapplicationwillbespacedapartbythehypotenuseofthestairrise/runwhich

istypicallyabout13in.

DisplacementAnalysisParameters

WeightofOccupant&MobilityDevice:650lb

Weightoneachwheel:163lb

FactorofSafety:2

Load:325lb

YieldStress:55MPa

DisplacementResult:0.17mm

StressResult:38MPa


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Figure16Stresssimulationonsingletracksectionsupportedatstaircontactpoints.

Figure17Displacementsimulationonsingletracksectionsupportedatstaircontactpoints.


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Winch

Fromaperformanceview,thewinchwillneedtohavethefollowingcapacities(seeappendixA.8forelectro-

mechanicalpowercalculations):

Lifttheplatformandloadtoadesiredheight,upto12feet Performtheliftingoperationwithinadesiredtimeconstraint,lessthan4minutes Withstandseveraloperationsfollowingonechargecycle

6.5CostAnalysis

Duringthedesignphase,onetopicthatcontinuedtocomeupasimportantwastheoverallcostofthe

unitwewerecreating.Thereareothersystemslikeours,howevernoneareasversatile,andcostupwardsof

$5,000.Ourgoalwastocreateabetterproductforsubstantiallyless,tomakeitcommerciallyviable.Thiswas

achievedthroughacoupleofcleverideas.

CommonParts

Byimplementingcommonparts,thereisnotonlyasignificantcostsavingsadvantageduetobulk

purchasing,butproductionismademucheasierthroughtheuseofcommontools,andmanufacturingsteps.

ConnectingPins

Therewilltypicallybe8-10pinsusedtoconnecttogetherthemodularrampsystempriortooperation.

Thesamediameterandlengthpinswillbeusedtoconnectthetracksectionstogetherinadditiontothetopand

bottommodules.

SocketHeadCapScrews

Thesocketheadcapscrewswhichholdthemale/femalecomponentstothetracksectionsaresocket

headcapscrews.Eventhoughthedimensionsofthemaleandfemalepartsareunique,thefastenerswillbethe

samelengthandsize.Allowingforeasierassembly,andlowerpurchasecost.

Powertrain

Thewinchwedecidedupon(http://imgur.com/IyRlsI3)tooksometimetofind.Thisonewaschosen

becauseofitsverylowcost,andlowamperagedemandonthebatteries(30ampsforanaverageload).This

meantthatinsteadof3batteries,wearesaving$100byusingtwo,whichstillgive10-12usespercharge(50min.

ofchargetime)


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6.6SafetyAnalysis

Productsafetywasconsideredfortheentiresystem,butwasstressedinthefollowingsubsystems:

TrackSections/Consoles

Theplacementofthetracksfollowsthecontourofstairstoavoidflexure Thethicknessofthealuminumtracksismorethanstrongenoughtosupportthemaximumloadofthe

passengerandwheelchair

Thetrackgeometrypreventstheplatformfromoverturning Thetracksectionsandconsolesarelinedwithgalvanizedrubberforincreasedgrip

Platform

Theplatformcollapsesdowntoasmallangleof9degreesforwhentheymountanddismountatthebottom

Theplatformstartsatanangleof9degrees,andhasagradualandsmoothtransitiontoreachthehorizontalposition

Theplatformwilllockandkeepthepassengeronalevelsurfaceuntiltheycandismountatthetop.Winch

Thewinchhasaperformanceloadof2000lbs Theintegrityoftheconnectiontotheplatformisadequate

6.7DiscussionofFinalDesign

Theoutcomeoftheentiredesignprocesshasproducedaconciseandeffectivesolutiontotheproblemstatement.

Theentiresystemhasbeenfunctionallyoutlinedabove,withcertaincriticalcomponentsbeingdefinedinamore

detailedmanner.Afterfinalizingthedesignforthemodularrampsystem,severalcomponentsweredeterminedto

bemostimportanttoprototypeandtest.

Prototyping&Testing

Arepresentationoftheplatform/tracksshouldbedevelopedtoprovetheessentialfunctionalityofthesystem(i.e.Makeaprototypewhichfoldsandcanberaisedontracksectionswiththetopoftheplatform

beingleveltotheground).

Anassemblyofthetrackconnectionsthemselvesshouldbemadetoprovetheperformanceofnotonlythepredefinedtolerances,butalsothefunctionality,easeofassembly,andstrength.

7.TestingandRefinement


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Inordertoexploreseveralkeycriticalissuesinourdesign,weprototypedourtwomajorsubsystems.Our

approachtoprototypingforeachsubsystemwasdecideduponbasedonthekeyconcernsforthatsubsystem

itself.Wedecidedonprototypingthetwomajorsubsystemsbasedontheabilityofthosesubsystems,when

testedandprovenindividually,tocollectivelyproveboththefeasibilityaswellastheintegrityofourdesign.

Thefirstsubsystemweprototypedisthelargestandmostvisibleportionofourdesign,andarguablythe

mostimportant.Inourdesignoftheplatform,weoriginallyusedaluminumframingwithasteelsheetmetal

coveringtokeepthematerialsinthedesignsimple.Lateinthedesignprocess,whenrevisitingourgoaltomake

thissystemasportableaspossible,ourgroupdecidedtochangetheplatformmaterialtohigh-density

polyethylene(HDPE).Sincethisprocessrequiresatremendousupfrontcostinthedesignandproductionofa

moldfortheplatform,weoptedtodesignthisportionoftheproductoutofwood.Buildingtheplatformoutof

woodallowedusacoupleofkeyadvantages:

Fullscalemodel Maintainsaccurateassessmentoffunctionality Exactdimensionsallowformorerealisticinterpretationoftheprocessitself Reducesprototypecostbythousandsofdollars Givescustomergroupstheabilitytoviewtheentireprocessforapproval/recommendations

Figure18Platformprototypeintesting


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Oursecondsubsystemthatweprototypedisnotnecessarilythemostnoticeablepartoftheproject,

howevertoourgroupthispartisthekeytoourwholedesign.Thetrackconnectionsarethekeytomakingour

productthecompact,portabledesignwesetouttodesign.Bysuccessfullyprovingourtrackconnectionsare

simple,easytooperate,andsafe,weareabletoprovethemajorconceptofourdesign.Asaresultofthedecision

tomaketheplatformoutofreducedcostmaterials,itnolongermadesensetoprototypethetracksintheir

entirety.Weinsteadchosetomanufactureatrackconnectionwithsmallportionsoftrack.Ourtrackand

connectionpiecesweretobeprototypedtoexactdimensionsusingtheexactmaterialswechoseinourdesign

process.Thisallowedustheadvantagestoview:

Abilitytomachinetoourdesiredtolerances Simplicityofthedesign Strengthofthedesign Functionalityoftheconnections Manufacturabilityofthematerialsweselected

Figure193-Dmodel(left)andactualprototype(right)withexactmaterialsanddimensioning

Usingthecombinationofthesetwoprototypes,wewereabletotestseveralaspectsofourdesign.This

includesthefunctionality,tolerancingandmachinability,easeofassembly,andfeasibility.

7.1TestApproachandFindingsforFunctionalityandFeasibility

Thetestapproachforfunctionalityandfeasibilityincludedbothprototypesaswellassomerelianceon

FEAanalysis.Iamincludingtheproofofintegrityofthetrackdesigninfunctionalityasthedesignwasproven

thoughtheuseofFEAanalysis.Infurthertesting,strengthtestswouldhavebeenperformedonthetracksections

aswellastheconnections,howeverthisisdestructivetestingandwouldruinourabilitytodisplaytheprototype.

Platformprototype


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Provingouruniquefoldingplatformdesigniseffectiveandveryuseful Showingthatourdesignsizeandstairangleiseffectiveforhomeuse Showingthatbyaddingminorcomponents(winch,landinggear,ext)littlephysicaleffortisrequired

Tracksectionprototype

Provingthatourvaryinglengthtracksectiondesignwillfittogetherflawlessly Byprovingthatthesectionsfittogetherweremoveanydoubtoffunctionalityofthetracksections

FEAanalysis

TheFEAanalysisusedafactorofsafetyandaworstcasescenariotoproveourtracksectionswillbemorethanstrongenough

Combinesthestrengthanddeflectionanalysiswiththeproofoffeasibilityfromthetracksectionstoshoweffectiveness

Figure20Strengthtestontracksectionatanestimated1400pounds,fourtimesthemaximumloadfromplatformwith

factorofsafetywithnofailure


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7.2TestApproachandFindingsforTolerancingandMachinability

Thetestapproachfortolerancingandmachinabilityagainincludesthepartialuseofbothprototypes.The

platformprototypeislimitedinsofarasthematerialsarenotwhatareusedinourdesign,howeverwewerestill

abletoachievesomevaluabletakeawaysasfarasdimensioningisconcerned.

Platformprototype

Evenwithlessaccuratedimensioning,materials,andmachiningprocesses,theplatformprototyperemainedfunctional

MachinabilityofourplatformispurelyreliantontheabilitytocreateanaccuratemoldTracksectionprototype

Tolerancesremainedeffectiveevenwhenmachiningisdonewithlowertolerancemachines MachiningwouldhavebeenpreferredontheCNCforhighestaccuracy Stillabletomachineaccuratelybutinmuchlargertimetable

7.3TestApproachandFindingsforEaseofAssembly

Thetestforeaseofassemblyisverysimpleforourprototyping.Almosttheentiretyoftheassembly

processoccursinthesettingupofthetracks.Theplatformdesigncomesinoncepieceasisandbecomesportable

byfoldingup,sothebulkofassemblyoccursinthetracksetup.


Connectionprototypeprovestheeaseofuseofthisdesign Allpinconnectorsareidenticaltoavoidpartconfusion Simpleprocess

o Countnumberofstairso Selectcorrectcombinationoftracksectionstoascendstairso Connecttrackpiecesfrombottomofstaircaseworkingtowardstopo Securetracksectionswithspringloadedpins

7.4ImpactofPrototypingFindingsonourDesign

Validationforourdesignwasprovidedbasedonourfindingsfromprototyping.Whilethegreatmajority

ofourdesignprocesswasasuccess,therearecertainlysomespecificplaceswewouldliketoimprove.


Redesignwouldincludeslimmingofprofiletoreduceweighto DuetoFEAstrengthanddeflectionanalysisprovingcurrentdesignprovidesmorestrengththan

needed


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o Reducingtheweightnotonlylessensmaterialcostbutalsomakesthesystemevenmoreportable-amajorcustomerrequirement

Platformprototype

Redesignwouldincludehydraulic,regulatinglegso Hydrauliclegswouldbeincludedtokeeptheplatformhorizontalatalltimeso Currentdesigniseffectivebutintroducessomeplatformanglesthatwewouldliketoalleviateo Afterloadingatsmallanglewewouldprefertomaintainhorizontalplatformorientation

Emergencyshutoffadditiono Intestingfoundthattheforceoftheplatformbeingpulledupstairswouldbeverygreato Foreignobjects,children,orpetscouldgetinpathofplatformo Emergencyshutoffuponcontactwithforeignobjectwouldaddsafetyforthosearoundthe

productaswellasthehandicappedindividual

Redesignwouldincludetheabilityoftheplatformtomaneuveraroundcornersinstaircaseso Currentdesignonlygoesupstraightstaircasesduetodesigntimeconstraintso Wouldrequiredisassemblingandreassemblingonthenextsetofstairso Incorporationsofhydrauliclegscouldallowforsimpletransitioningaroundcorners

8.Production

Fromtheinformationgatheredthroughoutthedetaileddesignandprototypingprocesses,webelievethe

bestmethodofproductionwouldbetohavemostofthemanufacturingoutsourcedwithpiecessuchasthemetal

stockandthesocketcapscrewstobebroughtinfromasupplier.TheassemblywouldbedoneinhouseaswellasthemoldingoftheHDPEplatform.Obviouslythescopeofeconomicswouldapplytotheproduction,howeverthis

systemisforasmallerpercentageofthepopulationsolargescaleproductionisnotnecessary.Thesubsections

listedbelowdescribethemethodofproductionforcriticalcomponentsofthedesign.

8.1ProductionofthePlatform

TheplatformismadeofHDPEandmanufacturedbyinjectionmoldingandthereforehasalargeinitial

costduetothecostofthemoldandtooling.Estimatedcostofthemoldwouldbeinthevicinityof$100,000,

howevertheexpectedlifeoftheSPIClass103moldisover200,000cyclesandoncepaidforwoulddrastically

increasetheprofitmarginofproduction.

8.2ProductionoftheTrackSections

Thetracksaremadefrom6061aluminumhollowbarstock,andbyuseofaCNCarecutintotheproper

shapeaswellasgivenafinishededge.Therewouldbetwocutsdownthelengthofthestockandachamferto


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finishtheend.Therewouldbeatotalof160holesdrilledandtappedto8-32forthetrackconnections.Finallythe

sectionswouldbecuttotheproperlengthsandshippedtoourassemblyfacility.Thetwo12footsectionswould

takelessthan2hourstocompleteandwouldcostapproximately$100dependingonthelocalshoppricesand

contractnegotiation.

8.3ProductionoftheTrackConnections

ThetrackconnectionswouldbemadeusingaCNCmachinesimilartothatofthetracksections.These

piecesaremuchsimplerhoweverandwouldtakelessthananhourtocompletethe10connectionsperunit.The

sectionsbeginasa1x2solid6061aluminumbarstockandarecutdownthelengthofthestocktoachievethe

finalshape.Therewouldbeatotalof160holesdrilled,butnottappedtoallowforthesocketheadscrewsto

connectthetrackswiththetrackconnections.Theexpectedcostis$50,consistingof10piecesperunit.Inthe

futureifitiseconomicallyviable,apurchaseofaCNCmachinetodothemanufacturingofthetracksand

connectionswouldbeconsidered.

8.4Assembly

Thesystemconsistsofnumerouscomponentsthatmustbeassembled,andthisisthemosttime

consumingportionofproduction.Duetothehighcost,anautomatedprocesstoattachtheconnectionstothe

trackswasunabletobeutilized,however,analternativeandlessexpensivemethodofquicklyfasteningthetwo

piecesmustbedeveloped.Apossiblesolutionhasbeenestablishedandwouldconsistofamodifiedflooring

screwdriverthatutilizesanautofeedsystem.Thiswoulddrasticallyreducethetimerequiredtoassembleand

thereforereducethecostofassembly.

Theunitwouldbeshippedinitsportablestatebutwouldrequiresomeassemblybeforeitisreadytoshipto

thecustomer.Themajorityofproductionisoutsourced,butastheassemblywouldbedoneinhousetheassembly

processiswelldefined.BelowaretherequiredstepstopreparetheModularRampSystemforshipment:

1. Mountthetrackconnectionstothetracksectionsandupperandlowerconsole2. Connectlateralsupporttolegsofplatform3. Connecttrackrollerstolegsandplatform4. Connectlegstoplatform5. Mounttiedownstrapstotopofplatform6. Mounteyehooktoundersideofplatform7. Wirebatteriesinseriesandconnecttowinch8. Mountpowertraininhousing9. Mounteyehooktopowertrainhousing


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10. Mountpowertrainhousingtobottomofplatform

Theassemblyprocesswouldrequiretwotrainedindividualsandtimeofassemblywouldbeintheneighborhood

of1.5hours.Thisisaninitialestimateandwithpracticeandmodificationtotheassemblyprocesscouldbe

streamlined.Uponcompletionofthesesteps,theproductioniscompletedandisreadytobedistributedtothe

consumer.

9.Conclusion

Fromoureffortthissemester,wewereabletodevelopasolutionmakingthephysicallydisabledamore

activepartofsociety.Theremainderofthissectionassessesthelevelofsuccessandopportunitiesforfuturework.

9.1AssessmentofSuccess

Thissemester,wewereabletoaddresstheneedtomakethephysicallydisabledamoreactivepartof

society,bydevelopingamodularrampsystem.Thedesignissafe,efficient,andhasitsownuniqueadvantagesto

thecurrentmarket.Ifproducedonthefullscale,ourdesignwouldbealightweight,versatile,rampingsystemfor

everydayusebyahandicappedperson.Ouroverallassessmentofsuccesscanbemeasuredbythecriteriaofour

finaldesigns:easeofuse,versatility,proofofconcept,andfiniteelementanalysis.Wewereunabletoconstructa

fullprototypeofexactmaterialsasitwasestimatedtocostanupwardsof$2,500.Therefore,aprototypemade

outofwoodwascreatedtoshowfullfunctionalityofthedesign,andatracksectionmadefrompropermaterials

wascreatedtoproveeaseofassembly,andcalculationsforsupport.

Withtheprototype,wewereabletotestourassemblyofthetrackconnectionswithmultiplepeoplewho

hadnopreviousknowledgeoftheprojectsscope.Ourassemblywaseasyandintuitiveenoughthatanyperson

wouldbeabletoputittogether,andacclaimedtobeasimpleandeffectivesolutiontoourgivenproblem.

Optimaleaseofassemblyandimplementationiscritical,asitwilleffectivelyincreasethepotentialcustomerbase.

Versatilitywasalsoanimportantfactorintheoveralldesign,andwasshownintheprototypebyprovingthe

functionalityofthetrackconnections.Withthedifferenttrackconnections,awiderangeofvaryingstaircase

heightsisachievable.Byusinga1-2-3-4systemoftrackconnections,whereeachlengthoftrackisequaltoa

specificnumberofstairlengths(eachnumberdefinedasamultipleofthehypotenusetocoveronestep)any

configurationofuptotenstairsisobtainable.

Ourdesignwasalsosuccessfulthroughourproofofconcept.Oneofourinitialgoalswastobeableto

conveyourideainasimplisticandvisualmanner,whichcanbemeasuredbytheacceptanceofthedesignbythe

handicappedindividualsandtheirassistant.Ourdesignmustbesomethingthattheseindividualsfeelcomfortable

using,andtrustenoughtoplacethemselvesonandtouse.Afteralloftheindividualsourdesignwasshownto,

andwiththefeedbackwereceivedfromthepostersessionpresentation,asawholeourdesignwasverywell


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received.Eventhoughourinitialprototypewasmadeoflowtolerancingmaterials,andmanufacturedinawood

shop,thefunctionalityofthedesignwasconveyedasatrustworthysolutiontotheproblemstatementthus

protectingtheintegrityofourconcept.Withafullyfunctioningmodelusingthepropermaterialspertainingtoour

design,thisleveloftrustwouldincreasesignificantly.

9.2OpportunitiesforFutureDevelopment

Thereareafewissuesweranintothatwewouldfixifthisprojectweretopanout.Thefiniteelement

analysiswasperformedonthetracksectionstodeterminetheirstrength,andiftheamountandtypeofmaterial

wouldbeafeasibleamountforadequatesupport.FEAanalysiswasonlyperformedonthetracksectionsasthey

weredeterminedtobethepointatwhichthedesignwouldbemostlikelytobreakorbuckletotheloadofweight

fromtheplatformplushandicappersonandwheelchair.Withthisanalysisitwascalculatedthatevenwithafactor

ofsafetyof2forourgivenload,thestrengthofthesectionswaswellbelowtheyieldstrengthofthematerial.This

analysisshowsthatthereisevenroomtoremovesomeofthetracklengthmaterialcrosssection,tomakeitmore

lightweight,andstillbestrongenoughtofunctionsufficientlyundertheyieldstrength.Allofthesecriteriafor

successwereconveyedasanobtainablemeasurementwhenthedesignbegan,andallofthesemetricsweremet

throughtheprototype.Withthissaid,weconsidertheprojectasawholetobeagreatsuccessthroughits

demonstration,butaswithanyengineeringdesign,thereisalwaysroomforimprovement.

Aspreviouslydiscussed,therearemultipleopportunitiesforimprovementinourdesign,ifwewereto

continueintothefutureanddevelopitfurther.Firstly,tofurtherprotecttheintegrityofourdesign,wewouldlike

toadjustportionsoftherampitself.Whenvideofootageoftherampinactionwastakentraversingastairwell,it

wasseenthattherewasalargeforwardleaningangleintheplatforminitstransitionstagefromloadingtobecomingahorizontalplatform.Forfuturedevelopmentwewouldliketopreventthiswiththeadditionof

hydraulictelescopinglegs,toadjustthisangle,andensurethattheuserisalwaysbroughttoacomfortable

horizontalangle,andavoidthedangerofsittingataforwardangle.

Anotherimprovementwewouldliketomakewouldbetoadjustourdesigntobeabletotraversestair

wellsthatrise,turn,acertaindirection,andthenriseagain.Assettinguptherampanditsentiretytwiceto

traverseastairwellwouldbeanuisance,wewouldliketodevelopawaytochangethetopmodules,toaccount

forspecifictypesofstairs.Inthismannertheusercansetupthetrackstoturnatacertainmedian,andcontinue

upwardsinonesmoothandfluidmotion.

Oneconceptthatislackinginourdesignisasafetyshutoffmechanismbuiltintothesystem.Ourcurrent

winchhasnowayoftellingiftheforceitisapplyingisadangerousamount,andintheeventthatsomethingwas

caughtwithinthetracklength,thewinchwouldcontinuetopullupwards,makingcertainscenariosextremely

hazardous.Wewouldlikethewinchsystemtoshutoffonceaspecificallyhighamountofforce,sothatinthe

eventsomethinggetsstuckinthetracksandisinterferingwiththesystemsmovement,thewinchwillstoppulling

toensurethesafetyoftheuser.


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Anotheraddedfeaturetoourdesignwouldincludeadampersystemhousedonthebottomofthe

platform,forthesolepurposeofasmoothertransition,andlessoscillationfeltbytheuserwhilstontheplatform.

Alsowithonlyourprototype,therewasnorealtestingperformedonourdesign.Withameansofcreatingourfull

modelwewouldperformthreepointbendingtests,destructivetests,andmanyotherteststobeabletoanalyze

ourdesignandrefineitaccordingly.

Lastly,wewouldlikeourdesigntobeefficientlycompactable,andasportableaspossible.Conceivablywe

wouldlikethedesigntotransformintoasuitcasetypedevice,wheretherampswheelswillbeusedtodragthe

systemaround,theplatformwouldcollapseintothebodyofthesuitcase,andallneededtracklengthsections

couldbeheldunderneaththeplatform.Thiswouldmakeitextremelyeasytomovearound,asthesystemasa

wholewillbefairlyheavy,andarduoustocarrybyhand.

Continuingwiththesedevelopmentsforourdesignwouldyieldasafeandsuccessfullydesignedproduct.

Withthecompletionofamethodofmanufacturingefficiently,thisdesigncouldconceivablybemarketready

withinayear.Thistimemeasurementisassumingthisproductisbeingsoldfromanestablishedbusinessentity,

whichhasalreadyprovidedameansofinvestorsandhasaccommodatedallotherbusinessarrangements.

10.References

UCSFDisabilityStatisticsCenterPublicationListing.11Oct.2012.DisabilityStatisticsCenter.24Feb.2013

.

AmericanswithDisabilities:2010p70-131.pdf.15July2012.AmericansWithDisabilities:2010.28Jan.2013

.

AccessLists&Ramps/HomeElevators/Stairlifts/WheelchairLifts.19Mar.2013.AccessLifts&RampsInc.Home

Elevators.3Feb.2013.

Powerwheelchairrangetestingandenergyconsumptionduringfatiguetestingcooper.3Oct.1995.Department

ofVeteranAffairs.5Feb.2013.

WolframlAlpha:ComputationalKnowledgeEngine.29Mar.2013.WolframAlpha.7Mar.2013

.

McMaster-Carr.11Feb.2013.McMaster-Carr.19Mar.2013.

PortableGenerators,PressureWashers,PowerTools,WelderslNorthernTool+Equipment.13Dec.2012.

NorthernTool+Equipment.18Mar.2013.


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MetalsDepotBuyMetalOnline!Steel,Aluminum,Stainless,Brass.9Aug.2012.MetalsDepot.17Mar.2013

.

Batteries,BatteryCharger,PowerSupplieslAtBatt.com.19Nov.2012.Atbatt.com.18Mar.2013

.

A.1CustomerRequirements

ListofCustomerRequirements:

1. Efficient(C,F,B)a. Theproductshouldbeefficient,meaningitshoulduseminimalpower/efforttoachievealarge

goal.

2. Easytosetup(C,F,B)a. Theproductcreatedmustbequickandsimpletosetup.Astimeisaveryimportantfactorofthis

customerrequirement,considerationofthenumberofstepsandtoolsrequiredtosetitupmust

beweighed.

3. Versatile(C,F,B)a. Astheproductwillbeusedonavarietyofstairs,itneedstobeabletoaccommodateatleastthe

mostpopularstyles,butalsoaccountfordifferentsurfaces(carpet/wood/cement),heightsand

individualstairsizes.

4. Safe(C,F,I,G,B)a. Customerswhowillbeusingthisproductwillrequireittobesafeforoperation.Thecustomer

couldbeofanyageandweight,andthechairtheyusecouldbeuptoseveralhundredpounds.

Theproductneedstosafelytransporttheoperatorandchairamultitudeoftimes.

5. CostEffective(C,F,I,B)


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a. Whetheritisaprivatecustomer,ahospitaloraninsurancecompanypayingfortheproduct,itneedstobereasonablypricedinordertobeviableforawidespreadnumberofconsumer

groups.

6. Reliable(C,F,I,B)a. Aproduct,whichisnotreliable,isnotagoodproduct.Bysmartdesign,wecancreateaproduct

withminimalmaintenanceandwithsixsigmastandardsofoperation;wecanguaranteeagood

reliableproduct.

7. WeatherResistant(C,F)a. Astheproductwillbeusedinavarietyofconditionsbothindoorsandoutdoorsaswellasona

varietyofsurfaces,theproductmustbeabletowithstandalargetemperaturerange,havelittle

ornorustspotsorotherfailurepointsduetoweather.Considerationshouldalsobemadefor

waterproofingelectronicmotorsandbatteries(ifapplicable).

8. UserFriendly(C,F)a. Operationshouldntbeoverlycomplicatedorconfusing.Itshouldbeeasytolearnand

rememberhowtooperatethesystem.Thenumberofstepstooperateshouldbeminimalas

wellastheinputforceoftheuserandtheoveralltimeneededtosetup,use,deconstruct,and

stow.

9. MeetsRegulations(C,F,G)a. Thesystemwilllikelybelookedatbyorganizationsthatregulatethesafetyandfailurerateof

theproduct.Thiscouldbeprivateinsurancedecidingwhetherornottocoverthepremiumto

purchasetheproduct,orafederalsetofregulationssetbytheADA.

10. EnvironmentallyFriendly(G,E)a. Withanever-growingconsciencefortheplanet,customerswilllikelyrequire(orappreciate)the

materialschosenforthesystemtoberecyclableaftertheproductlifespanhaspassed.

11. SafePowerSource(C,F,E,B)a. Ifthesystemisdesignedtoexpandwithamotor,attentionshouldbemadetothesourceof

power.Mostlikelyitwouldbeanelectricmotor,whichifpossiblecouldbepoweredby

renewableenergy.

A.2EngineeringSpecifications

CustomerRequirements EngineeringSpecifications Goal

EfficientPowerused Min

Materialspecificstrength Max

Easytosetup Numberofstepstoassemble Min


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Forcerequiredtoassemble Min

Timerequiredtoassemble Min

Versatile Rangeofdistanceriseavailable Max

Safe Weightcapacity 600lb.

CostEffective Consumerprice Min

Reliable Reliability Max

PortableWeight Min

Volumeofproductwhencollapsed Min

WeatherResistant Numberofwaterproofparts Max

UserFriendlyForcerequiredtooperate Min

Timerequiredtooperate Min

MeetsRegulations Numberofcodesfollowed Max

RecyclableMaterials Numberofrecyclablematerials Max

TableA.1-CustomerRequirementsandCorrespondingEngineeringSpecificationswithproposedbenchmarks

TheEngineeringSpecificationsintroducedintheabovechartareexpandeduponanddiscussedingreater

detailbelowinordertobetterunderstandtheirsignificancetotheproblem,andtheimplicationsoftheir

respectivebenchmarks.

1. PowerUsed(~>5Amphperuse)a. Toimproveefficiency,thepowerconsumptionshouldbeminimized,particularlysincethisunitis

intendedtobeasmobile/portableaspossible.Fortheunittobeoperatedoutsideawayfrom

otherbuildings,itwouldhavetooperateonDCpowerfromabatterysupply.

2. MaterialSpecificStrength(~60MPa)a. Rigidityoftheproductisahighpriorityinthisdesignproblemsinceitwillinvolvetransporting

theuserfromoneelevationtoanother.Thereasonspecificstrengthisconsideredistoaccount

forthefactthatwearedealingwithaportablesystem,soitisessentialtoconsidertheweightof

theproductevenwhileoptimizingthematerialstrengthrequired.

3. NumberofStepstoAssemble(~5)a. Forobviousreasons,thenumberofstepstoassembledirectlyinfluencestheeaseofsetup

requirement.Thenumberofstepsrequiredforanyproducttobereadytouseshouldbe

minimizedtoeasetheburdenonthecustomer,oroperator.4. ForceRequiredAssembling(~10lbs.)

a. Toensurethisproductissimpletouseforallcustomergroups,includingthosewhomaybeelderly,theforcerequiredtoassembletheproductisanessentialspecification.Byminimizing

theforcerequiredtoassembletheproductwesimultaneouslyexpandourpotentialcustomer

range.


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5. TimetoAssemble(~5min.)a. Thedirectcorrelationbetweennumberofstepstoassembleandtimetoassembleisalso

intuitive.Itispossiblethatthenumberofstepstoassemblecanremainlow,whilethetimeto

assembleishigh,thereforeitwasnecessarytoimplementthedurationofassemblyaswell.

6. RangeofStairsAscended(~1-10stairsstandard)a. Inordertobetteraccommodateasmanyhandicapconditions,andenvironmentalsettingsas

possible,themaximizationofelevationchangewouldbenecessary.Notonlydowewanttobe

abletocoverasmanystairsaspossible,butinadditionwewanttobeabletoadjustforany

numberofstairs.Forexample,ourgoalcouldbetoascendatleast10stairswiththissystem.To

us,thesystemwillnowneedtobecapableofascendinganynumberofstairsfrom1to10.

7. WeightCapacity(~650lbs.)a. Moreoftenthannottheweightofsomeonewithlimitedmobilitywillbegreaterthansomeone

whocanconvenientlymovearoundandburncalories.Itisforthisreasonthatweightcapacity

willbetakenseriously,withtheappropriatefactorofsafetyinmind.Wehaveestimatedausing

theweightofaheavymotorizedwheelchairaswellasaheavyuserthattheweightcapacitywill

needtobearound600poundsbeforeafactorofsafetyisconsidered.

8. ConsumerPrice($2,500)a. Eventhoughinsurancecompanieswillbecoveringalargepartofthisdevice,forpeoplewith

disabilitiesandtheirfamilies,theburdenofpayingforthedeviceshouldbeascosteffectiveas

possible.Thedifficultypresentedinthisestimationisthelackofdirectcompetitionourproduct

has.Wearecreatingaproductwithnosimilarcompetitorsonwhichtobaseaprice.

9. Reliability(~0)a. Fromasafety,cost,andreliabilityperspective;thenumberoffailureswhichthisproductexhibits

shouldofcoursebeminimized.Beingthattheproductisintendedtobemobileandnotfixedin

onelocationmakesdesignforreliabilityadifficulttask.Wewillaimforsixsigmareliabilityasa

failureinthissystemcouldbedeadlyfortheuser.

10. Weight(~100lbs.)a. Again,forportability,theunitwillhavetoweighaslittleaspossible.Thepersonwillbeableto

rollthesystemwhenintransporthoweverthesystemwillhavetobeliftedintoavehicleforlong

distancetraveling.Wedonotwantweighttobeafactorthatlimitsourcustomerrange.

11. VolumeofProductWhenCollapsed(~3ft^3)a. Inadditiontoweightbeingafactorinportability,thevolumewhichtheunitoccupieswhenitis

beingtransportedshouldbeminimized.Thiswillallowtheproducttobestoredinevensmaller

vehicles,andincreasetheconvenienceofmovingaroundpeoplewithdisabilities.

12. NumberofWaterProofParts(~AllParts)


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a. Obviouslythisproductwillnotbesubmergedduringoperationorstorage,butifitisexposedtowater,especiallyinoutdoorconditions,itshouldnottakeonmoistureinitsinternal

components.Allvitalpartsshouldbewaterprooforattheveryleastwaterresistant.

13. ForceRequiredtoOperate(~0lbs.)a. Anotherimportantconsiderationforthisproductbeinguserfriendlywouldbethatlittleforceis

neededtooperate.Thisstemsfromamajorfactorinmostsimpleramps.Theassistantwould

historicallyberesponsibleforphysicallypushingthehandicappedindividualuptheramp.We

wanttominimizethisrequirementinordertocontinuetoincreaseourcustomerrange.

14. TimeRequiredtoOperate(~2min.)a. Reducingthetimerequiredtomovetheperson,ortimerequiredtooperate,improvesthis

productsuserfriendliness.Aproductwhichtakesfartoolongtooperatewouldbeinconvenient

totheuser,andpeoplesurroundingtheenvironmentinwhichthisproductisbeingused.In

manycasesthissystemwilloccupytheentirewidthofthestaircase,sothefasterthesystemcan

beusedthefasternormaloperationcanresume.

15. MaterialsRecyclableAfterProductLife(~33%)Maximizea. Inaperfectlysustainableworld,ourproductwouldbedesignedwith100%recyclablematerial.

Unfortunatelythisisnotalwayspossiblesincematerialstrengthismoreimportantforthis

product,butwillbeourultimategoal.

A.3HouseofQuality


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FigureA.1HouseofQuality

A.4ConceptGeneration

DesignAlternatives

1. Attachable,lightweight,portableramptobackofwheelchair2. Triangularstairwedges3. Airbagliftsystem4. Hydraulicliftsystemthatgoesstraightupandfoldsbridgeopen5. Rocketpropelledwheelchairsystem6. Portableelevator7. Pulley/cablepullsystemforwheelchair8. Tanktracksonbottomofwheelchair9. Spiderinspiredwalksystem10. Stairsrotateintorampwithgrip11. Escalatorrampsystem12. Smartmaterialheatactuatedsystem13. Largesphericalwheelsthatcancompressformoresurfaceareacontact14. Ramppulledoutoftopstairsimilartomovingtrucks15. Stairsdesignedwithstepsandflatsectionsforwalkingandwheelchairuse16. Handcranksystemwithfavorablegearratio17. Attachmentthatallowsforridinguphandrails18. Wheelsthatadapttostairs19. Wheelaxlewalksupstairs20. Allterrainwheelchair21. Extendablerampsimilartoladders,winchconnectstochairandpullsupwheelchair22. Starshapeswheels23. Skisonfrontofwheelchair24. Automatedhandcart25. Windingrampsforlesssteepgradient26. Exoskeletonwheelchair27. MagLevliftsystem


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28. Gyroscopicwheelchair(bubbledesign)29. Wheelchairwithlegstopullup30. Legocombinablerampsystem31. Lightweightcompositecollapsibleramp32. Scissorliftinstalledintochair33. Platformpulleyliftsystem34. Craneliftdevice35. Airbagfrictionreductionsystem(airhockeytable)36. Rotationalliftsystemthatswingsplatformuptotop(thinktwisterride)37. Spiralrampsystemthatendswithbridgetotop38. Pneumatichandairpumptopropelblockupstairs

TableA.2ListofAllGeneratedConcepts

FigureA.2Pulley/CableSystem(#1Below)FigureA.3Tanktracks

FigureA.4AdaptableWheelsFigureA.5ExtendableRamp


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FigureA.6LegoRampDesign

Belowisadescriptionofourtopfiveconcepts.Thefiguresabovecorrespondtothedescriptionsbelowinthesameorder.

1. Pulley/CablePullSystemwithSkis(FigureA.2)-Thissystemdevelopedasacombinationofseveralideasinthegallerymethodprocess.Thewheelchairitselfwilllockintoskishapedplanksandbepulledupthestairsbyahandcrank

pulleysystem.Thisisveryportableandsimple,butmaynotbeassafeandstableasthetraditionalrampsystem.In

addition,thissystemwouldrequiresomeonetomechanicallycrankthelift,anddependingonthequalityofthecrank

thiscouldbeaverystrenuoustask.Alsotobeconsidered,thecrankwouldneedtolockintothestairsinsomeway.

2. Tanktracksonbottomofwheelchair(FigureA.3)-Thisdesignalternativebeganasaveryfarfetchedidea,howeverasithascontinuedtoprogressthroughtheroundsithasbecomeagroupfavorite.Theadvantageofthisdesignis

thatitwouldbeattachedtothechairatalltimesandloweratthepushofabuttontoclimbthestairs.Thetank

tracksprovidegreatstabilityandwouldgivetheabilitytoclimbanynumberofstairs.Theconcernisthatitwouldbe

veryheavyandexpensivetomakeaswellaspronetomechanicalfailureandwouldrequireamotionbasedbalance

system.Thiswouldundoubtedlyprovidethemostfreedomofanyofthedevicesasthetanktrackswouldbesteered

justasthewheelsare.Thisallowsforturninginanydirectionandthemostcontrolofanydeviceonourlists.

3. AdaptableWheels(FigureA.4)-Thisdesignendedupembodyingseveralsimilarideasthatconcernwheelsthatactuallyadapttothestairs.Themajorconceptinthisideaistohaveawheelwhichcouldbeexpandedintoaspoke

likewheel.Thespokeswouldformtheshapeofastarandwouldbecontainedwithinthewheelframewhilenotin

use.Thisstarshapedextensionofthewheelscatcheseachstairflushasthechairprogressesupthestairs.This

designwouldrequireamotionbasedbalancesystemtoleanthechairforwardsduringtheascendingandtilt

backwardsduringthedescending.Thisdesignissimplephysicallybutwouldbeveryinvolvedfromaprogramming

prospective.

4. ExtendableRamp(FigureA.5)-Followingtheideaforextendableladders,theserampswouldbecondensableandextendouttothedesiredlengthatwhichtheywouldlockout.Thisdesignwouldalsoincludeawinchthatwould

connectontheplaneoftherampstopullthewheelchairuptothenextlevel.Theconcernwithsimplerampssuchas

thisisthedistancetheycancoverwithoutadditionalsupportaswellasalimitintheangletherampcanascendat.

5. Legorampdesign(FigureA.6)-Thisdesignismeanttobetheultimateinadaptabledesign.Thebasisofthisdesignisitsmultilengthcapabilities.Thedesignallowsformanydifferentlengthsegmentsoframptobesoldinthepackage

sothatrampsofseveraldifferentlengthscouldbeconstructed.Throughourresearch,wehavefoundthatthe

presentdayportablerampscomeinarigidonelengthsystem.Inaddition,weimaginethisdesignhavingawinchand

pulleysystemtoallowthewheelchairtoclimbsteeperinclinesthanthecurrentmaximumofaround1:4.Evenat

previouslyattainableinclines,thewinchdesignwillservetotakethestressoffoftheuserandadditionalpeople

helpingtheuser.


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A.5ConceptSelection

FigureA.7DecisionMatrix

FigureA.8DecisionMatrixOutput

A.6EvolvedArchitecture

165

170

175

180

185

190

195

200

A B C D E

WeightedTotals

Alternaves(A-E)

DECISIONMATRIXOUTPUT


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FigureA.9ExplodedDesignfromMAE451FigureA.10OverallDesignfromMAE451

FigureA.11Week1ModifiedDesignShownonFigureA.12Week1ModifiedTrackDesign

StairCase

FigureA.13Update3ModifiedTrackConnectionsFigureA.14Update3ModifiedWheeldesign

A.7LargerCADModels

FigureA.15PlatforminOpenedPositionFigureA.16PlatforminLoweredPosition


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FigureA.17BottomConsoleinstalled

FigureA.18TopConsoleInstalled

FigureA.19TopViewFigureA.20OverallDesign


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A.8AnalysisDocuments

FigureA.21StairAngleCalculations


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FigureA.22WeightCalculations

FigureA.23ElectroPowerCalculations


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FigureA.24WeightofHDPE

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