Analysis Model Ananalysis wasconducted usingSPADE (Simple coordinate Partitioning Algorithm basedDynamics of finiteElements) developed byNTT[11][12]. SPADE cananalyze thedeployment behavior ofelastic structures. Theanalysis modeloftheplanartrusswasmadeasshowninFigure5.Wemadetheanalysis modelbasedonthedeployment driveforcemeasured bymicrogravitytesting. Thesuspension system and gravityforcewereconsidered topredictthedeployment driveforcemeasured bythegroundtesting. Experimental Results Difference between theexperimental andanalysis results Figure6showstheexperimental resultobtained byground testing. Theanalysis resultisalsoplottedto showprediction accuracy. Thereisapproximately 10%difference between the,experimental andthe analysis results. Thereasons forthedifference arethought tobeerrorsinthesuspension position, the counter weightandthecenterofgravityoftheplanartruss.Intheseground tests,themeasurement errorof thesuspension position islessthan1%andthemeasurement errorofthecounter weightislessthan0.1%. Therefore, weassumed theerroroftheanalysis modelforthesuspension position andthecounter weight issmallcompared totheerrorofthecenterofgravityoftheplanartruss.Accordingly, weconsidered the accuracy oftheexperimental resultwasmainlydetermined bytheerrorinestimating thecenterofthe gravityofplanartruss[7]. Toconfirm thishypothesis, were-measured theposition ofthepulleyandthesuspension cable.Thepulley andthesuspension cableareshown inFigure7.Though thereweresomedifferences between the suspension cableandthecenterofthepulley,theyoccupied thesameposition intheanalysis model.The differences were0.015minthegravitydirection and0.012minthehorizontal direction. Wealsomeasured thetension ofthesuspension cable,whenwepulledorloosened thesuspension (:ablewiththecounter weightononeend.Thesetestswereperformed fortwokindsofcounter weights (Wl,W2).Thefriction between thepulleyandthesuspension cablewascalculated bydividing thedifference ofthetensions between pulling andloosening by2.Thefriction was0.002kg inbothcounter weights. Therefore we subtracted 0.002kgfromthecounter weightintheanalysis modelofthestowing motion. Figure8shows theresultoftheanalysis modelwhenthesuspension position andthecounter weightwerechanged. The difference between theexperimental andanalysis resultsdecreased by0.05N,whichisonly0.5%ofthe deployment driveforce.Itisclarified thattheerrorofthedeployment driveforceisnotstrongly influenced by theaccuracy oftheanalysis modelforthesuspension position andthecounter weight. Next,wemustpayattention tothemassproperty. Theyaretotalweight, thecenterofgravity, andinertial moment. Totalweightwasmeasured within0.1%andinertialmoment wasassumed tobenegligible. The centerofgravityisuncertain. Therefore thecenterofgravityshould bemeasured. Theweightoftherib structure without thesuspension cablewasmeasured toverifythecenterofgravityoftheplanartruss.The measured valuewascompared totheanalysis valueasshowninTable2.Thedifference ofweightinthe experimental andanalysis models isapproximately 0.02kgeventhoughtheweights oftheanalysis model corresponded toeachbeam.Theresultoftherevised analysis modelisshowninFigure9.Thismodelwas revised intermsofnotonlythecenterofgravitybutalsothesuspension position andthecounter weight. In Figure9,thedeployment driveforcecorresponds totheexperimental result.Thisquantitatively provesthat theaccuracy oftheexperimental resultismainlydetermined bytheerrorofthecenterofgravityofthe planartruss.Theerrorofthedeployment driveforce,thedifference between theexperimental andanalysis values, isapproximately 10%forthesimplestructure whoseDIV=I,butitisapproximately 3%ifthemass properties arecalculated indetail.Inactualdeployment tests,itisverydifficult toestimate thetruemass properties oflargedeployable structures duringdeployment. Therefore, weusedtheformeranalysis model toclarifytherelationship between DIVandtheevaluation erroroftheground testing. Evaluation error Theevaluation errorofthegroundtestingisshowninFigure10.Line(A)showstheanalysis basedonthe deployment driveforcemeasured bymicrogravitytesting. Line(B)showstheanalysis basedonthe deployment driveforcemeasured bygroundtesting. Forline(B),thedeployment driveforcewasupdated bythegroundtestingresult,meansthatthespringforceoftheanalysis modelwaschanged tominimize the difference between theexperimental andanalysis resultsintheground testing. Theevaluation errorofthe ground testing cancalculated bydividing thedifference between deployment driveforceupdated bythe ground testing resultandtruevalue(deployment driveforcemeasured bymicrogravitytesting) bytrue NASA/C P--2002-211506 355