ai-aerospace/ams_data_full_2000-2020 huggingface dataset:
Status TheEngineering Modelcanister hasbeendesigned, built,tested,andintegrated intotheSRC.System leveltestingisinprogress. TheFlightModelcanister willbebuiltandtestedduringtheyear2000with delivery tothespacecraft scheduled formidJuly2000.Launch isscheduled forJanuary 2001. Acknowledgements Theworkdescribed inthispaperwasperformed bytheJetPropulsion Laboratory, California Institute of Technology, undercontract withtheNational Aeronautics andSpaceAdministration. Theauthorgratefully acknowledges thecontributions oftheJPLGenesis mechanical designteam:Glenn Aveni,JimBaughman, GusForsberg, GaryHaggart, TedIskenderian, MikeJohnson, KevinKramer, Don Lewis,PaulMacNeal, VirgilMireles, PabloNarvaez, FrankRamirez, DavidRosing, BruceScardina, Don Sevilla, AndyStone,George Sweeney, andRobertTroy. Thespacecraft andtheSRCaredesigned andbuiltbyLockheed MartinSpaceSystems Company - Denver Operations. TheConcentrator, Electron Monitor, andIonMonitor areprovided byLosAlamos National Laboratory. TheADMwasdelivered byAmerican Technology Consortium, andCDAInterCorp furnished thegearmotors. 205
CoverDrive Mechanism .........-7Cover LockRingDrive _mMechanism Figure3.LockRing Assembly TheEngineering Modelintegrated canister intheclosed configuration ismounted onitsvibration testfixture. LockRingDI MechanismDeployable Arrays Populated withCollectors ADM Flanges _ FixedSaddle LockRing Assembly Concentrator ArrayLatch Actuator Block ArrayLatch CoverDrive Crank Mechanism ArrayLatch Mechanism Moving Figure4.TheEngineering Modelintegrated canister isshown intheopenconfiguration. 207
Push-off Block Flexure Shorting ___Block Figure 5aand5b.Adetailed viewoftheLockRingAssembly isshown. Thefigureontheright hastheLockRingremoved forclarity. Ramp Canister Seal Lower Bearing PadCover Flexure _ Canister Canister Interior "TrackRoller Interior showntilteddownward inunloaded state [ Cover Flanc Lock JRing Base =" Flan_  Spacers ,.Kick_ Ring Figure6aand6b.LockRingAssembly sections through thetrackrollers intheleftviewand through theradialbearing intherightview 208
m RollerContacting Push-off Cover BlockDuringUnlocking ,.;:=:===::::k _ush-off Flexure _ //l_ @_ jI_IOCK FirstRollerContact _ _ ,_ (NoSealCompression). \Ii I_-------_ ----_ocked __ _ J Unlocked Position_ _ Ramp _ JPosition _seF,an0e _:_"_--2__,anoe _yL. ----- .o er 4- --Bearing--'Q_ --Pad KickRing_-Tus_-o.Reaction Pad Figure7.LockRingAssembly operation ShearPin _-Hard StopsTrack _ller Figure8aand8b.TheLockRingDriveMechanism usesapinionandsectorgeartrain to movetheLockRingtoitslocked andunlocked positions. 209
BearingThermal Cover ingAssembly CoverFlange SealAssembly Pinion Gear Gear Segment (Fixedto LockRing) Figure9.Track RollerIBaseFlange LowerBearing Pad \(Canister Interior) \ \ \ LockRingDriveMechanism cross-section 80/ Predicted 70-] Ramp Locking _J Changes Torque 60| Slope\ J ActualLocking50-! SealFully _ / T/9rque  Compressed k, _ / Actual 40 FirstRoUer _ ,_.OJ / Unlocking 30 Contact o,!_ ., Torque 10 0:-_e_•-_-.. , , , ¢./ 0 2 4 6 8 10 12 UNLOCKED LOCKED Position (deg) Figure10.LockRingMechanism operation 210
_verArm Flexures TorqueTube StopArmon DriveHub Figure11aand11b.TheCoverDriveMechanism opensandcloses thecanister cover.  ArmsAttached OI _toCanister Cover ..._._'I- (Torque TubeNotShown' Brackets Attached Canister Base (Support PlatesNotShown) GearmotorO Figure 12.0 b= 0 Bearing O Preload Spring_ r_ TheCoverDriveMechanism cross-sectionCable Spool 211
A E Zv crI,.. O I--80 70 6O 5O 4O 3O 2O 10 0 -10 -20ActualOpening • ActualOpeningTorque m1G / Torque during"NoOpen" "_, _l H.lld,. J¢" Functional Test \ / ttllllllhllllldi, \ Stalling / _l_WllllliLi, Predicted Opening _ Against the T,_._:_.-.,,-----,-...................____ ,........ ., I I I I I I 0 10 20 30 40 50 60 CLOSED Time(s) OPEN70 Figure 13.CoverDriveMechanism operation Figure14.TheCoverDriveMechanism isreinstalled intheJSCClass10 cleanroom aftercleaning. 212
Landsat 7SolarArrayTesting Experiences DanielHelfrich" Abstract Thispapercoverstheextensive Landsat 7solararrayflightqualification testingeffort.Detailsofthe mechanical designofthesolararrayanditsretention/release system arepresented. Atesting chronology isprovided beginning withtheonsetofproblems encountered atthesubsystem leveland carrying through thethirdandfinalpowered-spacecraft ground deployment test.Designfixesandother changes areexplained inthesameorderastheybecame necessary toflight-qualify thearray.Some interesting lessons learned areincluded alongwithkeyreferences. Introduction TheLandsat 7Spacecraft Landsat 7(L7),depicted belowinFigure1,waslaunched inAprilof1999intoa705-km sun-synchronous orbit.Asingle,huge,visible/infrared imager calledtheEnhanced Thematic Mapper Plus(ETM+) isthe soleL7instrument, occupying theentireforward (-Y)endofthespacecraft. ETM+provides landand near-shore oceanimagery downto15-meter resolution foraverydiverse usercommunity. The spacecraft wasbuiltunderNASAcontract NAS5-32633 byLockheed MartinSpaceSystems Company (LMSSC) located inValleyForge,PA.Acomprehensive description ofthespacecraft anditsmission is available onthewebatURL:_.gsfc.nasa.aov. Figure1.Landsat 7Spacecraft andFullyDeployed SolarArray "NASAGoddard SpaceFlightCenter, Greenbelt, MD Proceedings ofthe34_Aerospace Mechanisms Symposium, Goddard SpaceFlightCenter,May10-12,2000 213
OnApril28,1998,thefirstpowered-spacecraft deployment includingthefiringoflivecablecutterswas attempted beforealargeaudience. Thearrayreleased onlypartially duetoRRSproblems thathad caused insufficient cablepreload andhadresulted ininadequate extraction ofsomeofthecables. The RRSwasmanually released afterafullinspection ofthefailedhardware, allowing numerous failed manual deployment attempts several dayslater,whichdemonstrated theepoxyfloorwasstillaproblem. Individual hingelinesweretestedonagranitetablewithinaweekjusttoshowthosecomponents were working properly andwouldn't needtobereworked. Morecorrective actions ontheRRSandthe deployment MGSEwerealsoimplemented aspartofamulti-facetted failurerecovery effort. WithmanyissuesfromtheAprildeployment failureclosed, onAugust 24,1998,thesolararraywas successfully deployed offthespacecraft andbecame fullyqualified forflight.Butthattestrevealed yet another flawintheshockabsorber mechanism, requiring evenmoretestingonthebenchandathird pyrotechnic deployment onDecember 8,1998.Thisfinalfulldeployment wascompletely nominal and laidtoresttheremaining concerns aboutthedesignoftheRRS. Landsat 7SolarArrayRestraint/Release System General Characteristics TheS/AusedonL7hadsixstainless steelwirecablestorestrain ittothespacecraft; eachcableis chopped intotwopiecesbypyrotechnically drivencablecutters. Eachcablewasreallyacustom assembly, fabricated byBrown&Perkins, Inc.,consisting oftwodifferent threaded endfittingsswaged ontoa5.5-ram (7/32")diameter, 7x16wireropecable. Thepyrotechnic cablecutterusedintheRRSisaHi-Shear Corporation product specifically builtand testedforLMSSC. Ithasbeenusedonnumerous programs withintheUS.Anexplosive charge drivesa chiselintoananvilwithinacylindrical housing 19mm(0.75in)indiameter. Itwasalsousedonthe4-mm (5/32")diameter restraint cablesinL7'sthree(3)X-bandantenna gimbals. Inbothapplications, two cuttersareprovided foreachcable;thesecond, redundant, outboard cutteristhebackup ifthefirstcutter failstofire. Figure2showstheRRShardware incross-section. Unlabeled ontheright(outboard) sideofthefigure arethefoursolararraypanelsandthecup-cone fittingsthrough whichthecablefits.Theassembly on theleftofthosefourpanelsmounts withfourboltstotheinsideofthebodyofthespacecraft, theedgeof whichisapproximated bytheheavydashed line. p.,u..ycu,Tr,-_ /_-ORD._CC C..LE-, \ i// I stop,u_-_ gj,.  mLf UbSHAFTJ ENDADAPT SOLDER EJ FRICTIO_[:ANTI-ROTAT IONSPACER  TENSIONING NUT LSPLIT WASHER Figure 2.Cross-sectional viewofRestraint/Release System 215
Functional Details Figure3depicts thefunctional designoftheshockabsorber mechanism. Atthemoment ofcutting, substantial strainenergyisreleased andtheouterportionofthecutcableshootsrapidlyoutwards. In fact,adequate preload inthecableisessential forthisself-extraction ofthecable.Butthecablemust remainconstrained totheouterpaneltoprevent thecablefromflyingawayintospaceandbecoming orbitaldebris. Atleast25mm(1in)oftravelisrequired. Friction isusedtodissipate thekineticenergyofthecablesoitwon'tdeliveralargeshockpulsetothe outerpanelattheendofthecable's travelthrough thepanelfitting.Enough shockintheouterpanel couldcausethesiliconsolarcellsmounted outtheretocrackandthereby degrade thepoweroutputof thesolararray.Friction between thecablefitting's frictionshaftandasplitwasher captured intheouter paneldissipates theenergyreleased whenthecableischopped bytheprimary cutterandthepreload is suddenly released. Fulltravelisimportant totheoverallreliability oftheRRS.Without fulltravel,thesplayed endofthecut cablewillremaininthepathoftheredundant cablecutter. Insuchasituation, firingtheredundant cutter canentrapthecableandprevent thearrayfromreleasing. Thisveryproblem aroseduringthefailed powered spacecraft deployment attempted inApril1998.Firingsomeoftheredundant cablecutters beforealltheprimary cuttershadbeenfiredentrapped several already cutcablesandprevented the deployment fromproceeding normally. Thisfiringsequence wassubsequently revised forflight. Oult)oatdSo]_A_q_yPtm¢! SAStowed Confieuradon Figure3.ShockAbsorber Functional Diagram 216
straingaugesandacomputer-based datasystemtomonitorthem,accelerometers onthespacecrafttied intoamulti-channel high-speed datacollectionsystem,localRFintercomheadsetsforkeytest personnel,andthreeVHSvideocameras.Aftereverythingwascheckedoutandeveryonewassynchedup,thecountdown beganandthespacecraftsoftwareoperatedjustasifitwereinflight.Atthe appropriate time,shortlyaftersimulatedseparationfromtheupperstageofthebooster,thepyroswere firedinthecorners-first sequence. Thearraypanelspoppedoutaboutacentimeter(0.4in),butthatwas alltheymoved.Thetestwasabortedatthatpoint. Closeupinspections ofthejammedhardwareinitiallyindicatedseveralpossiblecausesforthefailureof thecablestoreleasefully.Onethingbecameclear:firingtheredundantcablescuttershadjammed someofthecableseventhoughtheyhadbeenfullyseveredbytheprimarycablecutters.Butafull inspectionwasthwartedbecauseaccesstoallthehardwarewasnotpossiblewiththearraysstillheld closetothespacecraftandwiththeRRScablesthemselves entrapped. Beforeunjamming thehardware, numerousmeasurements weretakenoftheconfiguration justasitwastopreventthelossofany potentialevidence. Meetingswereheldfrequentlyoverthenextseveraldays,givingeveryonepresenttheopportunity to considerthemountingevidence,suggestandstudypossiblecausesforthefailure,anddevelop deliberateplansonhowtoproceed.Theentrappedcableswereremovedfromthehardwareonebyone, measuringtheforcerequiredtopullthemfree.Itwasdecidedthatthetestshouldberesumedwithan attemptatamanualreleaseofthearray. AtestplanwasquicklypulledtogetherandtheGSEwassetupinrecordtime.Buttheteam'shopesfor asmoothdeployment werejustasquicklycrushed.Numerousfailedmanualdeployment attemptsover thenexttwodaysrevealedthefloorwasstillaproblem.Thenumerousorientations intowhichthesolar arraydeployedwereplottedontopofamapofthefloorcontours.TwosuchplotsareshowninFigure4. Thesoliddarklinesshowthefinalpositionsoffourdeployments ofthearrayassembly. Notetherelative smoothness oftheupperrightofthefloorthatisduetothefillingthatwasattempted previously. \ Figure4.SolarArrayDeployment Maps Acomplex failurerecovery planevolved overthedaysandweeksfollowing thefaileddeployment. Simultaneous activity inquiteafewtechnical areaswasrequired toresolve alltheissuesinatimely manner. 219
GranitQ Deployment TableExpansion Atradestudybeganshortlyafterthefailureoftheepoxyfloortosupportthefullmanualdeployments. As muchfillingandsandinghadalreadybeendoneasseemed practical, sootheralternatives werebrought upforconsideration. Besides addingnewgraniteblockstotheexistinggranitetableandrepouring an epoxysurfaceovertheoldone,optionsconsidered included machining theexistingfloor,transferring an existingdeployment tablefromtheEastWindsor facility,andlayingoutinexpensive honeycomb panels overtheexistingfloororonsetsofindividually adjustable jackstandsashadbeendonesuccessfully for TRMMdeployment tests.Withthegreatest confidence heldfortheexpanded granitetable,andwithout substantial costsavingspresented bytheotheroptions,thedecision wasmadetoobtainthreenew granitetablestoadjointheexistingtableyieldingasurfacewithenoughareatomeetthedeployment test objectives. OnJuly22,1998,thesolararraywasmanually deployed ontheexpanded granitetable provingitseffectiveness forwhenthenextpyro-initiated deployment testcouldbeperformed. RRSProblems LiveOn OnAugust24,1998,thesolararraywassuccessfully deployed offofthespacecraft inasecond deployment testoftheentiresystem. Withthatsuccess, thearraydeployment systembecame fully qualified forflight,butunfortunately thetestrevealed yetanotherflawintheshockabsorber mechanism. Fullextraction ofthecableswasnotachieved atallsixrestraints, nullifying thebenefitoftheredundant cablecutters,asprevious testingshowedthecableshadtofullyextractorbecome entrapped uponthe firingoftheredundant cutters. Evenmoretestingonthebenchandsomeadditional designchanges wererequired beforethesixshockabsorber mechanisms couldtrulybeconsidered singlefaulttolerant andtherebyflight-worthy. Itwasfoundinbenchteststhattherewasfrictional variability thatcouldcausegreaterenergytoss(and lessextraction) thanexpected. Increasing thepreloadwasnotperceived asthebestwaytoensurefull extraction, sothatroutewasnottraveled. Threefinalmodifications asshowninFigure5were implemented onthebenchandincorporated intotheflightdesigntoreducefrictional variability: 1.Stepping downthediameter ofthefrictionshaftforthefirstinchoftravel,reducing itsroleinthe energydissipation tohelpensuremaximum travelthroughthesplitwasher. 2.Addingashorttaperbetween thestepped-down diameter andfulldiameter regions. 3.Addinganelastomeric O-ringattheendoftraveltoabsorbimpactshock. 4.Addinganelastomeric O-ringtokeepthestopwasherinbetteralignment. Friction Shaft Retention CableStop SolarArrayOutboard Panel Washer --_ TaperStopNut AS3582-013 O-Ring AS3582 -022 O-RingSplit Washer Figure5.FinalDesignofShockAbsorber Mechanism 221
Lessons Learned Asseeninthetailoring oftheRestraint/Release System toLandsat 7,isitunwisetochange critical functional dimensions suchasthoseintheshockabsorber mechanism. Ifyoumustdosoasan element ofthedesign, document suchseemingly unimportant thingsasbenchtestprocedures and knowndesignlimitsandbesuretorecordthemintheassembly drawing. Itisessential toindicate keyfunctional dimensions assuchsotheywon'tbetreated lightly. Keepinmindthatfrictionis present whenyoudon'twantit,anddisappears whenyoudot Testing deployables earlyinsatellite I&Tcanuncover problems beforetheyaffectthecriticalpath.If thechoicehadbeenmadetodefertheLandsat 7S/Adeployment testuntillaterintheI&Tflow, shipment couldhaveeasilybeenshiftedoutintime,ultimately leading toaslipped launchdate. Testg-negation MGSEaheadoftimeandevensobereadyforproblems, especially whentakinga newapproach. Don'tignoreorbrushoffseemingly minorcheckout issueswithMGSEunlessthereis morethanenough timetocorrect unforeseen problems whenitsusedthefirsttime.Ifyoucheckout MGSEwayaheadoftime,makeadequate planstofullyprotecttheMGSEwhileit'sinstorage. •Loadwashers canbeaveryhelpfulelement forassurance ofcablepreload. Don'tusenuttorque onlywhenpreload isascriticalasitwasinthisapplication. Usingarigidgranite deployment surface (evenifitiscomprised ofseveral largegraniteblockswith seams) beatsacheapepoxyfloor.Inaddition, elevated surfaces areeasiertocleanandstay cleaner. Conclusion Ascanbeseenfromthemonumental effortexpended togetthefrictionforceintheshockabsorber mechanism justright,itcanbeunwisetorelyonfrictioninmechanisms. Todissipate energy, other approaches suchascrushable honeycomb shouldbeconsidered. Thethirdpyrotechnic deployment of theLandsat 7solararrayoccurred onDec.8,1998.Thisfinalfulldeployment wascompletely nominal andlaidtoresttheremaining concerns abouttheL7RRS. Manyhoursofproblem solving, brainstorming ofnewideas,andhardware re-testing wereconsumed in theflightqualification testingoftheLandsat 7solararrayanditsrestraint/release system. Ittookthe concerted teamwork ofbothprimecontractor andgovernment engineers toget thejobdoneaswellascommunicate theprogress oftherecovery effortsback toNASAGoddard SpaceFlightCenter. Inresolving thenumerous testingproblems thatarose,theimportance ofwell- {estedMGSEwasre-enforced intheminds ofallinvolved, anditishopedthat thispaperextends thatmessage tomanymoreintheaerospace mechanisms community. Finally, itshouldneverbeforgotten thatheritage hardware isoften takenforgranted andthatitrequires special consideration unlessitistrulyan exactcopyofwhatwaspreviously usedanditwillbeapplied verysimilarly. Epilog TheLandsat 7spacecraft waslaunched onaDelta7920-10 booster fromVAFB SpaceLaunch Complex #2(SLC-2) at11:35am(1935Z) onApril15,1999. Thesolararrayreleased correctly approximately 12minutes lateranddeployed successfully. Thedeployment timewasestimated at40seconds, +20seconds, basedonaroughplotof ACStelemetry ofthespacecraft attitude rates.Todate,thesolararrayperformance hasbeenflawless, bothmechanically andelectrically. 222
Acknowledgements Theauthorwishestorecognize theoutstanding technical effortsofMr.HughMcMenamin, LMSSC, under theverycapable management ofMr.RobertLeRoy. AlsoatLMSSC, Mr.NealShepard contributed his expertise acrosstheboardandlefttheauthorinaweofhisabilitytocutthrough thenoiseandchurnout newknowledge onasteadybasis.Finally, forhisabilitytoanalyze asituation andquicklygettotheroot ofanymechanical problem hewaspresented with,theauthorgratefully acknowledges thetalentsofMr. Charles TelekiofSwales Aerospace. Thesuccess ofthesolararrayon-orbit speaks tothevalueadded bythemembers oftheentireteamoftechnical managers, engineers, andtechnicians whobrought the flightqualification ofthearraytoasuccessful conclusion. References (Allreferences areavailablefromtheEOSLibraryatGSFC,(301)286-5641, orfromtheauthor.) "Critical Design Review Package forElectrical PowerSubsystem, SolarArrayAssembly" CDRL-A059, 5 May1995.(EOSLibrary# 6200) "FirstSolarArrayManual Deployment", LMMS PIRU-S/C-L7-1195-SYS RevA,NealShepard, 2 February 1998.(EOSLibrary# 9482) "Design andDevelopment ofanImproved Landsat 7SolarArrayRetention System", LMMSPIRU-S/CL7-1340-SYS, NealShepard andHughMcMenamin, 24March1999.(EOSLibrary# 11421) "Landsat 7Failure Modes andEffectsAnalysis -SolarArrayPanelDeployment System (PDS)", LMMS PIRU-S/C-L7-0158-SYS Rev.A,G.SmithandR.Haffery, 18April1995.(EOSLibrary# 5883) "Landsat 7SolarArrayPyroRelease Anomaly Review" presented toNASAGSFCCode300,DRAFT, 29 June1998.(Available fromtheauthor.) "L7PDSRestraint CableDevelopment TestResults" LMMSPIRU-S/C-LT-1144-MECH, TonyKull,13 March1997.(EOSLibrary# 9503) "Landsat 7SolarArrayAttachment Loads", LMMSPIRU-S/C-L7-1275-SYS,J. Ferraro, 27July1998. (EOSLibrary# 10866) "Updated Results ofSolarArrayPanelDeployment Analysis", LMMSPIRU-S/C-L7-0119-EPS, C.K.Lo, 19January 1995.(EOSLibrary# 6452) "SolarArrayRetention CableDevelopment Testing", LMMSPIRU-S/C-L7-0389-MECH, C.K.Loand R.Coscia, 8November 1994.(EOSLibrary# 7300) "CableCutter, Ordnance Activated Device (OAD)" LMMS Dwg#23023463, Issued5May1995.(EOS Library# 10592) 223
Deployment Dynamics ofSolarArrays withaLink-in-Slot Hinge/Latch Mechanism WalterK.Daniel"andG.Michael Bidinger" Abstract Asolararraymechanism withbothhingeandlatchcharacteristics hasbeendesigned, developed, tested, andflowninorbit.Dynamics analysis ofthislink-in-slot deviceshowed thatnoover-deployment tookplace whenthedynamic coefficient offrictionwashigherthan0.4.Themechanism designhasbeenverified in ground-based deployment testsandproveninflight. Introduction OrbitalSciences Corporation hasdeveloped andpatented acombination hinge/latch mechanism forsolar arraysthathasbeenusedonflightprograms. Thedeviceallowsforsecurestowing offoldedarraysand highstiffness whenopened. Panelscanover-deploy andrebound duringdeployment soanalysis was performed tounderstand thedynamics. Loadsduringdeployments werealsostudied. Hinge/Latch Mechanism Design Eachhinge/latch mechanism hasthreetypesofcomponents: twohousings, onelink,andfourpistons. Thehousings areattached tothetwobodiesthatwillbeconnected bythedevice(body-panel orpanelpanel). Eachhousing contains twospring-loaded pistonsthatpullthelinkintoaslot.Thelinkisconnected withapintothepistonsallowing rotation ofthetwobodieswhenthelinkisnotcaptured inthehousing. Adrawing ofthemechanism intheinitialposition is:showinFigure1.Notethatthepistons andhousing on oneendofthelinkhavebeenomitted forclarity.Thelinkisperpendicular tothehousing axisandisin contact withtheend.Thedeployed configuration ofthemechanism isshowninFigure2.Thelinkaxisis nowaligned withthehousing axisandthepistons haveretracted sothatthelinkisincontact withboth sidesofthehousing. Figure1.Mechanism inInitialPosition "Mechanical Dynamics, Inc.,Austin,TX "OrbitalSciences Corporation, Germantown, MD Proceedings ofthe34_Aerospace Mechanisms Symposium, Goddard SpaceFlightCenter,MayI0-12,2000 225
Figure2.Mechanism inDeployed Position Thehousings areembedded insolarpanelsforuseinflightarrays. Avarietyoflinkdesigns havebeenused including straight andangledones.Anadvantage ofthedesignisthatlinksbetween stowed panelsarein contact withtheattached housings resulting inasecureassembly forlaunch. Analysis ofDynamics Mechanical Systems Simulation technology wasusedtoanalyze thehinge/latch andsOlararray deployment dynamics. Thegoalwastocorrelate ananalytical modelwithgroundtestingresultsthenuse themodeltopredicton-orbit behavior ofthemechanisms. ThetoolusedwasADAMS fromMechanical Dynamics, Inc[Reference 1]. Amodelofonehinge/latch connecting twopanelswasdeveloped. Itcontains sevenrigidparts:twopanels, twohousings, twopistons, andonelink.Thepanelsarerepresentative ofthoseusedinvarious arTay configurations andare55.9cmby28cmandweigh2.3kg.Onepanelisattached togroundandtheother panelisfreetodeploy. Eachpistonisconnected toitshousing withatranslational joint;notethatonlyone pistonisnecessary inthisrigidmodeltorepresent thetwopistons inthemechanism. Thelinkisattached toeachpistonwitharevolute joint.Figure3isanimageoftheADAMS model. Figure3.ADAMS ModelofMechanism 226