A mobile remote manipulator system has been identified as a necessary device for space station. A conceptual design for an MRMS is presented which features (1) tracks on the MRMS and guide pins only on the truss structure, (2) a push/pull drive mechanism which rotates to permit movement in four directions, and (3) spacecrane and mobile foot restraint manipulators (or arms). Operational and design features of the MRMS elements are described and illustrated. Concepts are also presented which permit rotating the operational plane of the MRMS through 90 deg. Such a system has been found to have great utility for initial space station construction, maintenance and repair, and to provide a construction capability for future station growth or large spacecraft assembly and/or servicing

Bush, H. G.

Jensen, J. K.

Mikulas, M. M., Jr.

Wallsom, R. E.

English

NASA Technical Reports Server

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NASA Technical Memorandum 86262 NASA-TM-86262 19840020825
CONCEPTUALDESIGNOFA MOBILEREMQ_E0 -_,.-_-,,-'-'.,- _.,.a,-,,-'..:.,. . .:.,..__._'-"MANIPULATORSYSTEM _ _" _'_;"_"_"" ' -,-"-"-
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HAROLDG, BUSH
MARTIN M, MIKULAS, JR,
RICHARDE, WALLSOM,
J, KERMIT JENSEN
JULY1984
OCT19'0,,84
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HAMP.TONtVIRGINIA
NahonalAeronauticsand
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Langley Research Center
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CONCEPTUALDESIGN OF A MOBILE REMOTE MANIPULATORSYSTEM
Harold G. Bush, Martin M. Mikulas,Jr.,
Richard E. Wallsomand J. KermitJensen
July 1984
• Space station studieshave identifiedthe need for a mobile remote manipulator
s__vstem(MRMS). Such a logisticsor utilitydevice is envisionedto be outfitted
with a spacecranecapability(i.e.,-shuttleRMS), and probablyastronautfoot
restraintpositioningarms. The system is requiredduring initialstationcon-
structionactivitiesto positionastronautsfor EVA functions,to transportmodules
and/or payloads from the Shuttle cargo bay and positionthem for attachmentto the
truss structure. Subsequentto the initialspace stationconstructionactivities,
a mobile remotemanipulatorsystem is considerednecessaryfor maintenanceor
repairactivities,and to providea constructioncapabilityfor future station
growth or large spacecraftassemblyand servicing. The mobile platformwhich
possessesthe capabilitiesdescribedabove will be referredto as an MRMS in
subsequentparagraphs.
MRMS MOBILITYREQUIREMENTS
The square bay truss structureof the space stationconfigurationsshown in
reference1 suggeststhe need for an MRMS which can move in two orthogonaldirec-
tions. This capabilitypermitsmovement (1) along the space stationkeel struc-
ture.betweenthe modules and the solar array supportstructure,and (2) perpen-
dicularlyalong the solar array supportbooms. An MRMS with only unidirectional
mobility theoreticallycould be rail mountedto accomplishthis functionbut would
probablyneed to be detached and reattachedto additionalorthogonalrails to
move in a perpendiculardirection--anoperationaldrawbackwhich probablyshould
be avoided. Mounting rails onto the space stationtruss structureintroduces
additionalmass and significantdesign complexitywhich also must be considered.
The lower mass alternativeof positioningrails on the MRMS (insteadof the
truss) which "ride"on the truss hard points is possible. However,endless
tracks (chainsor belts)which providemobility in this case must completely
span two (2) truss bays to ensure stabilityof the MRMS during motion. Such an
arrangementavoids the increasedmass and complexityof rails attachedto the
truss structureand provides for a "smooth,"continuousunidirectionalmotion
capability. However,movement in a perpendiculardirectionis not enhanced,
and the undesirablefeatureof an MRMS which must be two (2) bays in length is
introduced. A two-bay-longMRMS presentsShuttle packagingproblemsand degrades
maneuverabilityand, therefore,usefulnessfor maintenanceand construction
activities,particularlyin close proximityto the modularhabitats or surface
attached equipment.
A roboticwalker ("spider")conceptuallycould serve as an MRMS and accomp-
lish the necessaryfunctions,but would requireextensivedevelopmentof a
device which is not consideredstate-of-the-art.
REFERENCEMRMS DESIGN
A conceptualdesign for a bidirectionalMRMS which is only one-bay square
and avoids a truss mounted rail system is illustratedin figure 1. This design,
which is amodification of a two bay long device describedin reference1, consists
of three basic elements or layers. The bottom or track layer consists of a square
track arrangementwhich rides on structuralguide pins attachedto the truss nodes.
The four (4) tracks are arrangedin a single plane and connectedat the corners
by "switches"which can be alignedto permitmotion over the guide pins in either
of two orthogonaldirections(see figure 2). The track layer does not rotate
4
relativeto the truss structure. The four corner switchesrotate 90o but only
when centeredover the guide pins.
3The centralelementconsistsof a push/pulldrive mechanismwhich also has
360° rotationcapability(see figure 3). This featurepermitsplatformmovement
in four directionsby either a push or pull operationand greatlyenhancesmaneuver-
abilitywithout requiringadditionalstructurefor translation. It also permits
- changingmovement directionwithout rotatingthe logisticsplatform (e.g.,-attached
payloads). The push/pullmotion is envisionedto be poweredby an electricstepper
motor through a rack and pinion drive. Mounted on the drawbarends are "drive"
rods which are alignedwith, and electricallyinsertedinto, the nodal guide pins
and locked. The switchesare alignedappropriatelyand the drawbar is actuated
to push or pull the MRMS in the desired direction. The drawbarextendsto span a
complete bay, such that four point supportof the MRMS is maintainedat all times.
Translationof the MRMS is accomplishedby operationof the push/pulldrive
mechanismto move the platformlongitudinallyin an "inch-worm"fashion. This
sequenceof events is illustratedin the upper half of figure 4. Transersetrans-
lation involvesuse of the pivoting,as well as push/pullfeatureof the mechanism,
and is illustratedin the lower half of figure 4. Sketch (A) shows the MRMS
pivoting 900 from the directionof travel. Sketch (B) shows a translationto
constructan adjacenttruss cell which is in the next row. Sketch (C) shows the
MRMS slidingonto the cell just constructed. Sketch (D) shows a 90o rotation
into a positionparallel,but on an adjacentrow, to the original. Sketches (E)
and (F) show longitudinalmotion and constructionof added cells to completea
platform. The corner switch illustratedin figure 5 shows the open top mechanism
featurewhich permitsthe drawbarto lock onto a guide pin which is also occupied
by a track switch.
The top elementof the MRMS is the logisticsplatformwhich is envisioned
to rotatewith respectto either the track or drive elements (see figure 6).
This platformwould serve to transportpayloads and cargo over the space station
surface. A centralfeatureof this elementwould be the capabilityto operate
a transposedShuttleRMS, which is shown in figure 6 mounted on a moving carriage.
Also shown in figure 6 are mobile foot restraint(MFR) positioningarms. Pressure
suitedastronautsattachedto the MFR's are positionedwithin their work envelope
by the movable positioningarms in a manner similarto reference2. The MFR arms
should not be consideredto be miniatureversionsof the ShuttleRMS, with its
precedentsettingprecisioncontrolrequirements. Rather, each MFR arm should
be controllableby the astronautwho can adjust its positionin a manner similar
to a utility servicemanoperatinga "cherrypicker"bucket. The degreesof
freedom requiredby the MFR arms are determinedby the extent to which EVA is
utilized to performvarious future space stationfunctions.
The MRMS should have a self contained,rechargeablepower supply which does
not requireumbilicalsor power rails. Controlof all featuresof the MRMS should
reside with the EVA astronaut(s)to avoid hardlineor RS controllinks to a central
station. Transportcradlesor similardevicesmust be providedto supportpayloads
being moved about the space stationsurfaceby the MRMS.
MRMS PLANE CHANGE CONCEPT
The proposedMRMS can operateover both the "top" or "bottom"surfacesof
the referenceconfiguration,if required,using the rotary joints and solar array
boom rotationas a turntableto translatebetweenthe two parallelsurfaces.
For generalityand versatility,however, it is desiredto operatethe MRMS in a
plane which is perpendicularto these parallelsurfaces. Two (2) concepts for
rotatingthe operationalplane of the MRMS 900 from its originalpositionare
shown in Figures7a and 7b. The concept shown in Figure 7a uses a tiltingframe
approach to rotatethe MRMS 90° and enable translationand operationonto a per-
pendicularplane. The tiltingmechanismis envisionedto be self-containedand
installedas a truss cell unit into a beam or along a platformedge. This unit
should be capable of rotating900 in both the "left" or "right"hand directions.
A second approachis illustratedin Figure 7b which is operationallymore
4
complex but mechanicallysimplerand probablymore compactthan that of Figure 7a.
This conceptconsistsof a planar guide pin frame which is attachedto the
originalstructureat the center<ofan elementwhich replacesa truss strut. A
center sectionof this elementcontainsa "T" fittingwhich has two perpendicular
rotationaldegreesof freedom. Operationally,the MRMS translateslaterally
onto the attached guide pin frame. The MRMS and frame are then rotated 1800
around the frame centerlineattachmentas shown in Figure 7b into an "upside
down position." The MRMS and frame are then rotated900 around the strut element
centerlineto a positionwhich permitsthe MRMS to translateonto the plane which
is perpendicularto its originaloperationalplane.
' Two devices,such as those just discussedor anotherappropriatedesign,
?
placed in oppositefaces of the truss structurewould permitmore rapid and
convenienttranslationof the MRMS between "top" and "bottom"surfacesof the
station ratherthan interruptingthe rotationof the solar wing for this purpose.
CONCLUDINGREMARKS
A conceptualdesign for a m_obiler_emotem_anipulators_ystemhas been presented.
This conceptdoes not requirecontinuousrails for mobility (only guide pins at
truss hardpoints)and is very compactbeing only one bay square. The MRMS proposed
is highly maneuverablebeing able to move in any directionalong the orthogonal
" guide pin array under completecontrolat all times. The proposedconceptwould
o greatlyenhancethe safetyand operationalcapabilitiesof astronautsperforming
EVA functionssuch as structuralassembly,payloadtransportand attachment,
6space stationmaintenance,repairor modification,and future spacecraftcon-
structionsas servicing.
The MRMS drive system conceptualdesign presentedis a reasonablysimple
mechanicaldevice which can be designedto exhibit high reliability. The Shuttle
RMS is a developedsystem,whi'chonly needs minor modificationto permit its
installationand operationfrom a mobile base. The MFR positioningarms are not
envisionedto need the precisioncontrolcapabilityof the RMS. Developmentally
all componentsof the proposedMRMS either exist, or are considered to be completely
state-of-the-artdesignsrequiringminimal development--featureswhich should
enhance reliabilityand minimizecosts.
REFERENCES
1. Mikulas,Martin M., Jr.; Bush, Harold G.; Wallsom,Richard E.; Dorsey,
John T.; and Rhodes,Marvin D.: A Manned-MachineSpace StationConstruction
Concept. NASA TM 85762, February 1984.
2. Heard, Walter L., Jr.; Bush, Harold G.; Wal]som,Richard E.; and Jensen, J.
Kermit: A Mobile Work StationConceptfor MechanicallyAid Astronaut
Assembly of Large Space Trusses. NASA TP 2108, March 1983.
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SHU
ROTATINGLOGISTICSPLATFORM
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i
PUSH/PULLDRAWBAR
FOOTRESTRAINT
POSITIONINGARMS
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CORNERSWITCH(4).""'_-"_.-.__' _ "_---:............ . ....
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Figure1.- MobileRemoteManipulatorSystemElements(ExplodedView)
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GUIDE PIN ENGAGENENT NECHANISM
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. Figure 3.- Push/Pull Drive System Arrangement
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LONGITUDINAL
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Figure 4.- MobileRemote ManipulatorSystem Translation
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TRUSSGUIDEPIN
Figure5.- CornerSwitch,GuidePin,and DriveRod_rrangement.
SHUTTLERMS
CARRIAGE /-'- LOGISTICSPLATFORM
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MOBILEFOOTRESTRAINTS
MFR POSITIONINGARM
Figure 6.- Remote Manipulator and MFRPositioning Arm Arrangement
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(A) (B) (C)
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1. Report No. 2. Government AccessionNo. 3. Recipient's'CatalogNo.
NASATM-86262
4. Title and Subtitle S. Report Date
Conceptual Design of a Mobile Remote Manipulator July 1984
System 6. PerformingOrganizationCode501-53-43-01
7. Author(s) 8. Performing Organ;zation Report No.
Harold G. Bush, Martin M. Mikulas, Jr., Richard E.
Wallsom, and J. Kermit Jensen 1o.WorkUnitNo.
9. PerformingOrganizationName and Address
NASALangley Research Center 11. Contractor Grant No:
Hampton, VA 23665
13. Type of Report and Period Covered
12. Sponsoring Agency Name and Address
Technical Memorandum
National Aeronautics and Space Administration 14.SponsoringAgency
Washington, DC 20546
15. Supplementary Notes
Harold G. Bush and Martin M. Mikulas, Jr., NASALangley Research Center, Hampton, VA
Richard E. Wallsom and J. Kermit Jensen, Kentron International, Inc., Hampton, VA
16. Abstract
A mobile remote manipulator s_ystem has been identified as a necessary device for
space station. A conceptual design for an MRMSis presented which features (a)
tracks on the MRMSand guide pins only on the truss structure, (b) a push/pull
drive mechanism which rotates to permit movement in four directions, and (c)
spacecrane and mobile foot restraint manipulators (or arms). Operational and
design features of the MRMSelements are described and illustrated. Concepts
are also presented which permit rotating the operational plane of the MRMS
through 90v. Such a system has been found to have great utility for initial
space station construction, maintenance and repair, and to provide a construction
capability for future station growth or large spacecraft assembly and/or servicing.
i
17. Key Words (Suggested by Author(s)) 18. Distribution Statement
Space Structure
Space Station Unclassified - Unlimited
Manipulator
Subject Category 18
t9. Security _auif. (of thisreport) 20. SecurityClauif. (of this pege) 21. No. of Pages 22. Dice
Unclassified Unclassified 15 A02
.-,o5 ForsalebytheNationalTechnicalInformationService.Springfield.Virginia22161




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