1. Ranger Telerobotics Program
Brian Roberts
University of Maryland
Space Systems Laboratory
On-Orbit Servicing Workshop
14 November 2001 1

2. Space Systems Laboratory
25 years of experience in space systems research
Focus is to develop and test complete systems capable of performing complex space tasks end-to-end
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 maximize involvement of students in every level of research activities

3. SSL Assets for On-Orbit Servicing
Development and testing of multiple complete robotic systems capable of performing complex space tasks end-to-end:
Docking
Assembly
Inspection
Maintenance
Facility for evaluating systems in a simulated 6 degree-of-freedom (DOF) microgravity environment
Expertise:
Autonomous control of multiple robotic systems
Design of dexterous robotic manipulators
Adaptive control techniques for vehicle dynamics
Use of interchangeable end effectors
Investigation of satellite missions benefiting most from robotic servicing

4. 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?
Manipulator Design?
Hazard Detection and Avoidance?
Utility of Interchangeable End Effectors?
Development, Production, and Operating Costs?
Ground-based Simulation Technologies?
Effects and Mitigation of Time Delays?
Ground Control?

5. Multimode Proximity Operations Device (MPOD)
System to evaluate controls associated with robotic docking
Full 6 DOF mobility base
Full state feedback through an on-board sensor suite, including an acoustic-based sensor system
Probe-drogue docking system
Operational since 1986
Achievements:
Autonomous approach and docking
Maneuvering and berthing of large masses
Application of nonlinear adaptive neural network control system

6. Supplemental Camera and Maneuvering Platform
Supplemental Camera and Maneuvering Platform (SCAMP) is a free-flying camera platform
6 DOF mobility base
Stereo video and close-up color cameras
Originally used to observe neutral buoyancy operations
Evolved to evaluate robotic inspection
Operational since 1992
Achievements:
Used routinely to observe robotic and non-robotic neutral buoyancy operations
Demonstrated visual survey and inspection

7. SCAMP Space Simulation Vehicle (SSV)
Continuation of SCAMP’s evolution into a high fidelity neutral buoyancy simulation of 6 DOF space flight dynamics
Uses onboard sensors (3-axis gyros, accelerometers, magnetometers, and a 3-D acoustic positioning system) to accurately calculate its position, attitude, and translational and rotational velocities
Robot is positioned to a specified location, determined by a mathematical computer simulation
Operational since 1997
Achievements:
Cancellation of water drag effects for flight dynamics
Model-referenced vehicle flight control
Adaptive control of unknown docked payloads
Autonomous docking
Different methods of trajectory planning are being investigated

8. Beam Assembly Teleoperator (BAT)
Free-flying robotic system to demonstrate assembly of an existing space structure not robot friendly:
6 DOF mobility base
5 DOF dexterous assembly manipulator
Two pairs of stereo monochrome video cameras
Non-articulated grappling arm for grasping the structure under assembly
Specialized manipulator for performing the coarse alignment task for the long struts of the truss assembly
Operational since 1984
Achievements:
Combination of simple 1 DOF arm with dexterous 5 DOF manipulator proved to be a useful approach for assembly of a tetrahedral structure
Demonstrated utility of small dexterous manipulator to augment larger, less dexterous manipulator
Assisted in the change out of spacecraft batteries of Hubble Space Telescope

9. “Ranger” Class 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

10. 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 NASA’s 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 3

11. Ranger’s Place in Space Robotics
How the Operator Interacts with the Robot
How the Robot Interacts with the Worksite

12. 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)
25 lb of force and 200 ft-lbf of torque; can withstand 250 lbf at full extension while braked
~1500 lbs weight; 14 length from base on SLP to outstretched arm tip

13. Task Suite Fiduciary tasks Robotic ORU task Robotic assistance of EVA
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
Non-robotic ORU task
HST Electronics Control Unit insertion/removal

14. Microconical End Effector
End Effectors
Microconical End Effector
Bare Bolt Drive
Right Angle Drive
Tether Loop Gripper
EVA Handrail Gripper
SPAR Gripper

15. Operating Modalities Flight Control Station (FCS)
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)

16. 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:
Refining hardware
Modifying control algorithms and developing advanced scripts
Verifying boundary management and computer control of hazards
Correlating space and neutral buoyancy operations
Supporting development, verification, operational, and scientific objectives of the RTSX mission
Flight crew training
An articulated non-powered mock-up is used for hardware refinement and contingency EVA training

17. Graphical Simulation
Task Simulation
GUI Development
Worksite Analysis

18. 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

19. Arm Evolution Roboticus Dexterus Roboticus Videus Roboticus Grapplus
BAT Dexterous Arm (5 DOF)
BAT Tilt & Pan Unit (2 DOF)
BAT Grapple Arm (0 DOF)
ca. 1984
ca. 1984
ca. 1984
Ranger Dexterous Arm Mark 1 (7 DOF)
Ranger Grapple Arm (7 DOF)
ca. 1994
ca. 1996
Ranger Dexterous Arm Mark 2 (8 DOF)
Ranger Video Arm (7 DOF)
Ranger Positioning Leg (6 DOF)
ca. 1996
ca. 1996
ca. 1998

20. 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: Mock-up began operation (62 hours of underwater test time on 45 separate dives to date)
October 2001: Prototype positioning leg pitch joint and Mark 2 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 NASA’s Office of Space Science and #2 on Space Shuttle Program’s cargo bay priority list

21. SSL Assets for On-Orbit Servicing
Development and testing of multiple complete robotic systems capable of performing complex space tasks end-to-end:
Docking: MPOD and Ranger TFX
Assembly: BAT and Ranger
Inspection: SCAMP
Maintenance: Ranger
Facility for evaluating systems in a simulated 6 DOF microgravity environment
Expertise:
Autonomous control of multiple robotic systems
Design of dexterous robotic manipulators
Adaptive control techniques for vehicle dynamics
Use of interchangeable end effectors
Investigation of satellite missions benefiting most from robotic servicing

22. Backup Slides

23. Robot Stowed Configuration95

24. Computer Control of Hazards
Human response is inadequate to respond to the robot’s speed, complex motions, and multiple degrees of freedom
Onboard boundary management algorithms keep robot from exceeding safe operational envelope regardless of commanded input

25. Results of a Successful Ranger TSX Mission
Demonstration of Dexterous Robotic Capabilities
Understanding of Human Factors of Complex Telerobot Control
Pathfinder for Flight Testing of Advanced Robotics
Precursor for Low-Cost Free-Flying Servicing Vehicles
Lead-in to Cooperative EVA/Robotic Work Sites
Dexterous Robotics for Advanced Space Science