Gardell G. Gefke, Craig R. Carignan, Brian J. Roberts, and J. Corde Lane

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Ranger Telerobotic Shuttle Experiment Status
Report
Gardell G. Gefke, Craig R. Carignan, Brian J.
Roberts, and J. Corde Lane University of
Maryland Space Systems Laboratory http//www.ssl.u
md.edu/
Intelligent Systems and Advanced Manufacturing
Conference Telemanipulators and Telepresence
Technologies VIII 28 October 2001
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Space Systems Laboratory

• 25 years of experience in space systems research
• A part of the Aerospace Engineering Department at
  University of Maryland
• People
• 4 full time faculty
• 12 research and technical staff
• 18 graduate students
• 28 undergraduate students
• Facilities
• Neutral Buoyancy Research Facility (25 ft deep x
  50 ft in diameter)
• About 150 tests a year
• Only neutral buoyancy facility dedicated to basic
  research and only one in world located on a
  university campus
• Fabrication capabilities include rapid prototype
  machine, CNC mill and lathe for prototype and
  flight hardware
• Class 100,000 controlled work area for flight
  integration
• Basic tenet is to involve students in every
  aspect of research

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What are the Unknowns in Space Robotics?
Flexible Connections to Work Site?
Capabilities and Limitations?
Human Workload Issues?
Multi-arm Control and Operations?
Control Station Design?
Interaction with Non-robot Compatible Interfaces?
ManipulatorDesign?
Hazard Detection and Avoidance?
Utility of InterchangeableEnd Effectors?
Development, Production, and Operating Costs?
Ground-based Simulation Technologies?
Effects and Mitigation of Time Delays?
Ground Control?
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Ranger Class Satellite Servicers

• Ranger Telerobotic Flight eXperiment (RTFX)
• Free-flight satellite servicer designed in 1993
  neutral buoyancy vehicle operational since 1995
• Robotic prototype testbed for satellite
  inspection, maintenance, refueling, and orbit
  adjustment

• Demonstrated robotic tasks in neutral buoyancy
• Robotic compatible ORU replacement
• Complete end-to-end connect and disconnect of
  electrical connector
• Adaptive control for free-flight operation and
  station keeping
• Two-arm coordinated motion
• Coordinated multi-location control
• Night operations

• With potential Shuttle launch opportunity, RTFX
  evolved into Ranger Telerobotic Shuttle
  eXperiment in 1996

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Ranger Telerobotic Shuttle eXperiment (RTSX)

• Demonstration of dexterous robotic on-orbit
  satellite servicing
• Robot attached to a Spacelab pallet within the
  cargo bay of the orbiter
• Task ranging from simple calibration to complex
  dexterous operations not originally intended for
  robotic servicing
• Uses interchangeable end effectors designed for
  different tasks
• Controlled from orbiter and from the ground
• A joint project between NASAs Office of Space
  Science (Code S) and the University of Maryland
  Space Systems Laboratory
• Key team members
• UMD - project management, robot, task elements,
  ground control station
• Payload Systems, Inc. - safety, payload
  integration, flight control station
• Veridian - system engineering and integration,
  environmental testing
• NASA/JSC - environmental testing

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Rangers Place in Space Robotics
How the Operator Interacts with the Robot
How the Robot Interacts with the Worksite
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Robot Characteristics

• Body
• Internal main computers and power distribution
• External end effector storage and anchor for
  launch restraints

• Head 12? cube
• Four manipulators
• Two dexterous manipulators (5.5? in diameter 48?
  long)
• 8 DOF (R-P-R-P-R-P-Y-R)
• 30 lb of force and 30 ft-lbf of torque at end
  point
• Video manipulator (55? long)
• 7 DOF (R-P-R-P-R-P-R)
• Stereo video camera at distal end
• Positioning leg (75? long)
• 6 DOF (R-P-R-P-R-P)

1500 lbs weight 14? length from base on SLP to
outstretched arm tip

• 25 lb of force and 200 ft-lbf of torque can
  withstand 250 lbf at full extension while braked

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Robot Stowed Configuration
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Task Suite

• Fiduciary tasks
• Static force compliance task (spring plate)
• Dynamic force-compliant control over complex
  trajectory (contour task)
• High-precision endpoint control (peg-in-hole
  task)

• Robotic ORU task
• Remote Power Controller Module insertion/removal

• Robotic assistance of EVA
• Articulating Portable Foot Restraint setup/tear
  down

• EVA ORU task
• HST Electronics Control Unit insertion/removal

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End Effectors
Microconical End Effector
Bare Bolt Drive
Right Angle Drive
EVA Handrail Gripper
Tether Loop Gripper
SPAR Gripper
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Operating Modalities
Video Displays (3)

• Flight Control Station (FCS)
• Single console
• Selectable time delay
• No time delay
• Induced time delay
• Ground Control Station
• Multiple consoles
• Communication time delay for all operations
• Multiple user interfaces
• FCS equivalent interface
• Advanced control station interfaces (3-axis
  joysticks, 3-D position trackers, mechanical
  mini-masters, and force balls)

Keyboard, Monitor, Graphics Display
2x3 DOF Hand Controllers
CPU (Silicon Graphics O2)
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Ranger Neutral Buoyancy Vehicles

• Neutral Buoyancy Vehicle I (RNBV I)
• Free-flight prototype vehicle operational since
  1995
• Used to simulate RTSX tasks and provide
  preliminary data until RNBVII becomes operational
• RNBV II is a fully-functional, powered
  engineering test unit for the RTSX flight robot.
  It is used for

• Supporting development, verification,
  operational, and scientific objectives of the
  RTSX mission
• Flight crew training
• Developing advanced scripts
• Refining hardware
• Modifying control algorithms
• Verifying boundary management and computer
  control of hazards
• Correlating space and neutral buoyancy operations

• An articulated non-powered mock-up is used for
  hardware refinement and contingency EVA training

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Graphical Simulation
Task Simulation
GUI Development
Worksite Analysis
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Simulation Correlation Strategy
EVA/EVR Correlation
All On-Orbit Operations Performed Pre/Post Flight
with RTSX Neutral Buoyancy Vehicle for Flight/NB
Simulation Correlation
Simulation Correlation
Simulation Correlation
EVA/EVR Correlation
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Computer Control of Hazards

• Human response is inadequate to respond to the
  robots speed, complex motions, and multiple
  degrees of freedom

• Onboard boundary management algorithms keep robot
  from exceeding safe operational envelope
  regardless of commanded input

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Program Status

• 1995 RNBV I operations began at the NBRF
• 1996 Ranger TSX development began
• June 1999 Ranger TSX critical design review
• December 1999 Space Shuttle Program Phase 2
  Payload Safety Review
• April 2000 EVA mock-up began operation (62 hours
  of underwater test time on 45 separate dives to
  date)
• October 2001 Prototype positioning leg pitch
  joint and dexterous arm wrist began testing
• Today RNBV II is being integrated 75 of the
  flight robot is procured
• January 2002 RNBV II operations planned to begin
• Ranger TSX is 1 cargo bay payload for NASAs
  Office of Space Science and 2 on Space Shuttle
  Programs cargo bay priority list

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Results of a Successful Ranger TSX Mission
Demonstration of DexterousRobotic Capabilities
Pathfinder for FlightTesting of Advanced Robotics
Understanding of Human Factorsof Complex
Telerobot Control
Dexterous Robotics forAdvanced Space Science
Precursor for Low-CostFree-Flying Servicing
Vehicles
Lead-in to CooperativeEVA/Robotic Work Sites