Ranger Telerobotics Program Brian Roberts University of Maryland Space Systems Laboratory http://www.ssl.umd.edu/ On-Orbit Servicing Workshop 14 November 2001 1

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

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

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?

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

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

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

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

“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

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

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

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

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

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

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)

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

Graphical Simulation Task Simulation GUI Development Worksite Analysis

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

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

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

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

Backup Slides

Robot Stowed Configuration 95

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

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