This segment of the program is focussed on the development of space robotics for eventual application to on-orbit satellite servicing by free-flying servicing robots. The purpose of this segment of the program is to focus the development of component technologies into applications and environments which will demonstrate their utility and additional capability when incorporated into operational systems. These technologies include virtual reality telepresence, advanced display technologies, proximity sensing for perception technologies, and robotic flaw detection. The target applications include such tasks as repair of free-flying small satellites, and ground-based control of robotic servicers. Each of these areas have been identified by the potential space robotics user community as applications where space robotics will be necessary to satisfy their planned requirements. This user community includes the External Work System and anticipated commercial space system developers.
Ranger Telerobotic Flight Experiment
Ranger Automated Visual Inspection System
Telepresence / VR Control of Free Flying Robots
Dexterous Arm Control for Ranger Flight Experiment
Free Flying Camera Robots For Enhanced EVA Performance
External Work System
Space Operations
Ranger Telerobotic Flight ExperimentIn June 1992, the decision was made to actively pursue the development of the Ranger Telerobotic Flight Experiment (TFX), as proposed by the University of Maryland Space Systems Laboratory. This project includes the development of neutral buoyancy and flight prototypes for a class of low-cost expendable telerobots designed for research and servicing in space, beyond the space station orbit. The vehicle will be equipped with four manipulators: two 7-DOF arms for bilateral dexterous manipulation; a 7-DOF manipulator for grappling at the local worksite; and a 6-DOF arm for positioning a pair of stereo video cameras giving primary feedback to the remote operator. A second stereo camera pair mounted on the vehicle centerline will provide a stable visual reference for free-flight maneuvering, and ultimately feed a vision system for autonomous vehicle docking.
Much of the design and construction of the Ranger Neutral Buoyancy Vehicle was completed in FY 93. In FY 94, the manipulators were assembled and integrated onto the completed mobility base. In FY95, the Ranger NB vehicle was outfitted with upgraded manipulator electronics and operated in the UMd Neutral Buoyancy Research Facility. The completed Ranger NB vehicle, while providing telerobotic operational data, will also be used to develop and verify algorithms, software, and experiment designs for the space flight experiment.
The Ranger TFX spacecraft design is strongly coupled to the Ranger NBV design. In FY94, several system trades were performed to determine the overall scope and configuration of the TFX vehicle. In FY95, preliminary design of the spacecraft subsystems was performed and long-lead items were identified. In FY96, component acquisition and subsystem construction will be performed, leading up to system integration and test in FY97. The TFX mission is planned for flight early in FY98.
Focus and Directions:
FY 1994: Complete and test the neutral buoyancy version of Ranger; complete Phase A and B studies on the Ranger Telerobotic Flight Experiment (TFX)
FY1995 Collect engineering data from Ranger NBV in the UMd Neutral Buoyancy Research Facility; continue detailed design and long-lead item procurement for Ranger TFX
FY1996 Collect operational data from Ranger NBV for correlation with Ranger TFX flight data; construct and test Ranger TFX subsystems
FY1997 Perform mission operations training and continue operational data collection using Ranger NBV; integrate Ranger TFX systems and perform integrated test and verification of TFX vehicle in preparation for FY98 launch
FY1998 Launch Ranger TFX and collect operational data for correlation with Ranger NBV data; analyze data collected from Ranger NBV and TFX operations
Additional information and specifics associated with the focus and direction of the flight experiment can be found in the Integrated Design Review documentation.
Point of Contact:
Dave Akin
(301) 405-1138
dakin@ssl.umd.edu
Ranger Automated Visual Inspection SystemAutomated robotic inspection of space platforms such as Space Station is expected to be an important element to offload time consuming inspection activities from astronauts. Jet Propulsion Laboratory recently developed such a remote surface inspection (RSI) system demonstrated successfully on the ground in a constrained lab environment. The system, however, needs further evaluations/enhancements to be robust for practical use in space applications. The objectives of this task are to 1) evaluate and enhance the existing JPL automated surface inspection technology and 2) apply this technology to the Ranger TFX mission Phase 3 Visual Inspection Task to assess/validate the telerobotic automated inspection capability in real space operation lighting conditions. The inspection taskboards will be three-dimensional with different surface textures, and will be used for both ground-based pre-flight and actual Ranger flight tests.
The automated inspection software package will be evaluated and enhanced to be robust under 1) varying ambient sunlighting and under 2) varying image mis-registrations. At present, we will assume that only on/off controllable continuous lighting will be available for the actual Ranger flight, which will achieve about 80% of our evaluation/validation goals relative to the flight inspection test equipped with electronic shuttering/strobe lighting. The image registration problem is not affected by the absence of electronic shuttering/strobe lighting. Actual video images collected under varying sunlight angles (including shadowed or dark portions of the orbit) can still determine the quality of the automated inspection algorithm quantitatively below a certain level of sunlight illumination. Further, simulated strobe lighting can be added to the video images collected during the actual Ranger flight to evaluate the dynamic working range of the automated visual inspection algorithm. University of Maryland may later opt to add electronic shuttering/strobe lighting.
Focus and Directions:
FY 1996: Evaluate/enhance the existing automated inspection software package. Design a Ranger inspection board mockup and build two (one for JPL test and the other for Ranger delivery). Define onboard and ground-site requirements for the Ranger flight inspection experiment in coordination with the University of Maryland Ranger TFX team. Define inspection scenario, and develop inspection task software including user interface and command sequences consisting of arm motion control, light on/off, and image captures. Deliver a taskboard mockup, inspection task software, and inspection scenario to the University of Maryland Ranger Program for Neutral Buoyance test by June 1996.
FY 1997: Deliver a revised inspection taskboard for the Ranger flight by December 1996. Complete the development of an enhanced automated inspection software package and perform ground baseline pre-flight tests by June 1997. Analyze, on the ground, actual inspection experiments in the flight and post-flight operations. Document the results.
Point of Contact:
Won S. Kim
(818) 354-5047
wonsoo@telerobotics.jpl.nasa.gov
Telepresence / VR Control of Free-Flying RobotsThe objective of this research task is to add a telepresence/virtual reality control interface to a free-flying robot. This interface will initially provide advanced teleoperation and supervisory control capability to the Ranger NB (Space Systems Laboratory, Univ. of Md.) by augmenting existing control stations. Subsequent work will provide telepresence/virtual reality control capability to the Ranger TFX telerobotic flight experiment.
The Ranger NB vehicle is an extremely complex telerobot, offering 32 degrees-of-freedom for operator control. To productively use this system, it will be critical for operators to have an effective control interface. In particular, the interface must provide support to the operator for visualizing the workspace, for efficiently displaying vehicle state, and for handling system latencies such as communications delay. In addition, the interface must enable higher human performance while reducing operator fatigue and stress. One approach which appears to satisfy these requirements is the telepresence/virtual reality control interface.
During the past three years, the Intelligent Mechanisms Group (IMG) has been developing control interfaces utilizing telepresence and virtual reality technology. These interfaces seek to provide robotic systems with high-fidelity telepresence capabilities and allow users to more easily interact with remote devices. By utilizing real-time interactive computer graphics, stereoscopic video and stereoscopic displays, telepresence/virtual reality interfaces enable users to efficiently manage and visualize complex systems. As a result, such interfaces can dramatically improve human teleoperation performance, particularly in the presence of time-delays.
Approach:
Our approach is to provide for a transfer of control interface technology from the Ames' IMG to the U.Md. SSL. This transfer will involve the augmentation of existing SSL operator stations with telepresence and virtual environment subsystems. Specifically, the IMG will provide technology developed at ARC which utilizes real-time interactive computer graphics and stereoscopic video displays. The work will be conducted in a two phase project.
In the first phase, a telepresence/virtual reality interface will be developed for the Ranger NB system. This interface will provide the operator with real-time visualization of the Ranger NB system state and worksite. The focus of this phase will be to directly enhance the capability and to improve the performance of human operators in a research environment.
In the second phase, refinements to the telepresence/virtual reality interface will be developed to support the Ranger TFX flight experiment. These refinements will include the development of orbital dynamic vehicle models and predictive displays for handling system latencies in the presence of communications delays. We expect that the control interface project will have a minimal impact on the SSL's on-going Ranger NB and Ranger TFX development process. The initial work will be performed at ARC and leverage existing IMG resources and personnel. This will be followed by integration with Ranger subsystems, which will be conducted jointly by the IMG and the SSL.
Task Milestones:
October 1 93 Installed Telepresence/VR Control Station Hardware at ARC
August 1994 Completed Integration of Telepresence/VR Control Station Software at ARC
October 1994 Installation of Prototype Telepresence/VR Control Station Software at SSL for Ranger NB Roll-Out
January 1995 Perform NB Human Factors Study of Traditional vs. VR Control Station
September 1995 Completion of Ranger TFX dynamic simulation model integrated into VR Control Station
October 1995: Finish hardware implementation of control chair. Holodeck implementation and testing dependant on hardware delivery (expected early november); Initial implementation and test of operator interface protocols.
November 1995: Implement first cut of symbol table from Ranger NBV, Develop simple simulator for telemetry streams and test of symbol table.
December 1995: Continue VEVI integration of symbol table from Control Station, continue test and development.
January 1996: Physical integration of VEVI Command Chair at UM Control Station; finish integration of VEVI to use command symbol table, this will make VEVI both an input and output device.
March 1996: Ranger NBV simple task testing - ex free-flight to grapple, peg-in-hole, task components of ORU changeout
July 1996: VEVI support of Ranger NBV End-to-End testing - full tasks, ex. performing ORU changeout from begining to end.
September 1996: VEVI support of TFX Mission Operations Development - develop and simulate full mission task scripts, just as they would occur for TFX
FY 1997 Operator control station for Ranger during the flight experiment
FY 1998 Network observer station for Ranger during the flight experiment
Point of Contact:
Laurent Piguet
(415) 604-6063
piguet@artemis.arc.nasa.gov
Ranger Dexterous Arm ControlThe goal of this task is to augment the operational capabilities of the dexterous arms in the Ranger Flight Experiment. These new capabilities will be developed within the framework of Configuration Control, which has been developed at JPL and selected for implementation on the Ranger arms.
Approach:
Develop the capability of on-line collision detection and avoidance for the Ranger dexterous arms. This capability does not currently exist in the Ranger baseline control system, and erroneous operator commands can cause collision between the dexterous arms and the camera and grapple arms, the base, or the task board. The performance improvement due to this added capability will be measured in two ways. First, it will enable a broader range of tasks to be executed safely, such as collision-free reach inside a constricted space or opening. Second, it will cause a reduction in the Ranger operation time by 50%, since several possible motions with potential collision are not executed. Finally, this capability will increase the safety of the Ranger during the operation of the arms, a feature which is vital to the success of the Ranger mission.
Provide the ground operator a software tool for proper placement of the Ranger base. This algorithm will ensure that both dexterous arms reach the task site and the useful workspace volume is maximized. The algorithm will take into account the fact that the Ranger base is attached to the task site by the grapple arm. At present, the placement of the Ranger base is done by the ground operator in an iterative trial-and-error fashion. The performance improvement due to this added capability is expected to be a reduction by 30% of the Ranger operation time.
Conduct proof-of-concept experiments to demonstrate the collision detection/ avoidance and optimal base placement capabilities. The RSI Laboratory at JPL is equipped with two mobile RRC arms which have very similar kinematics to the Ranger arms, as well as a similar real-time computing platform. This facility will be used for final testing of the JPL algorithms before implementation on the Ranger flight and ground computers.
The above capabilities will considerably enhance the robustness and reliability of the Ranger arm control system, and will significantly expand the range of tasks that can be accomplished in the Ranger Flight Experiment. A series of technology experiments are planned to demonstrate the collision detection/ avoidance and base placement capabilities on the wet-Ranger while operating in the Neutral Buoyancy Tank at SSL.
Focus and Directions:
FY 1995: Develop and implement the collision detection/avoidance capability for the Ranger to enable robust and reliable task execution. Perform proof-of- concept graphical simulations on the Silicon Graphics IRIS Workstation at JPL using the kinematic model of the Ranger 7-DOF arms. Deliver the JPL-developed software modules to the Ranger Project.
FY 1996: Develop and implement the optimal base placement capability for the Ranger to enable execution of single-arm and dual-arm tasks. Conduct a series of technology demonstrations at JPL to validate the collision detection/avoidance and optimal base placement capabilities experimentally. Quantify the operational improvement of the Ranger with the augmented capabilities of automated collision avoidance and base placement. Deliver the software modules to the Ranger Project.
Point of Contact:
Homayoun Seraji
(818)354-4839
seraji@telerobotics.jpl.nasa.gov
Free Flying Camera Robots For Enhanced EVA PerformanceMany Space Station operations will occur outside of direct line-of-sight of the habitated modules. Due to cost reduction exercises, the number and placement of mounting sites for external video cameras on Space Station will be highly constrained. Since many Space Station servicing tasks will be performed EVA, this implies that highly complex EVA operations may well take place without any capability for monitoring inside the modules or on earth. These operations could be significantly enhanced if a free-flying camera platform were available to send the desired images back. This same device could also be used to increase the performance of the robotic elements of the Mobile Work Station, by providing auxiliary views to remote operators on the station or on the ground.
This effort, performed by a team of the University of Maryland and the Johnson Space Center, will focus on the external operations, realistic trajectories, and crew interfaces. The Supplemental Camera and Mobility Platform (SCAMP) will be enhanced by upgrading the video camera to a stereo pair, and by adding sensors for the 3DAPS navigation system. Flight control software will be upgraded to incorporate this new sensor data, which will allow autonomous station-keeping or tracking of dynamic targets. Also under the initial efforts, an inexpensive, low-fidelity simulation of the Space Station pre-integrated truss will be developed for the Neutral Buoyancy Research Facility. During this time, JSC will be developing algorithms for realistic flight trajectories, and will develop a crew interface for SCAMP, based on existing training environments (Space Shuttle and Space Station mockups, and the IGOAL virtual reality laboratory).
In initial tests, the University of Maryland NBRF will simulate the space station environment, with test subjects wearing the MARS suit simulators developed in the prior year under internal funding of the University of Maryland. Operators at JSC, including flight crew, will control SCAMP over the Internet to monitor test operations, with video return to JSC over a satellite link with compressed Internet video as a backup option. The outcome of these tests will be to demonstrate the safety aspects and monitoring capabilities of a free-flying platform, and to develop a constituency for this type of telerobot among the operational community.
In following tests, SCAMP and its derivative vehicles will be used in neutral buoyancy simulations to monitor operational EVAs, particularly Space Station development EVA simulations. These tests will incorporate University of Maryland software for autonomous dynamic tracking and predefined view angles, and will provide additional impetus for development of an operational flight unit. The ultimate goal of this research will be to demonstrate free-flying robotics in a high-fidelity neutral buoyancy environment, with the vehicle behaving dynamically as if it were in space, and incorporating advanced levels of autonomy to minimize operator workload.
Focus and Directions:
FY 1996:
Demonstrate SCAMP operation in the JSC WETF
Perform technology developments for upgrades to SCAMP, including stereo video, position sensing and tracking, and advanced thruster design
Develop trajectory algorithms for predicting free-flight dynamics in the space environment
FY 1997:
Develop advanced SCAMP vehicle incorporating new technologies
Control SCAMP in testing at NBRF from control station(s) at JSC
Demonstrate operational potential of free-flight vehicles in support of space station operations
FY 1998:
Verify realistic flight dynamics for advanced SCAMP in extended test operations
Test advanced free-flying vehicle in neutral buoyancy
(Potential) delivery of advanced SCAMP to JSC for routine neutral buoyancy operations
Point of Contact:
Dave Akin
(301) 405-1138
dakin@ssl.umd.edu
Space OperationsThe development of new technologies for space telerobotics brings with it a concomitant requirement for understanding the impact of that technology on the operational capabilities of the eventual telerobotic system. Addressing this area of space telerobotic operations is the primary focus of the University of Maryland Space Systems Laboratory (SSL). During its initial years of operation at the Massachusetts Institute of Technology, the SSL pioneered the development of analytical models for neutral buoyancy simulation, and performed extensive tests on extraÐvehicular operations, leading to the Experimental Assembly of Structures in EVA (EASE) tests on STS 61-B in late 1985.
Since that time, the SSL has focused primarily on space telerobotic operations, with emphasis on neutral buoyancy simulations of integrated EVA/telerobotic work sites. The Beam Assembly Teleoperator (BAT) has performed structural assembly of both EASE and Space Station truss structures, as well as tests of Hubble Space Telescope servicing, both alone and in conjunction with EVA subjects. The Multimode Proximity Operations Device (MPOD) has performed a number of tasks relevant for orbital maneuvering vehicleÐclass spacecraft, and has demonstrated the utility of manned astronaut support vehicles for extended EVA capabilities. The Apparatus for Space TeleRobotics Operations (ASTRO) has been used to research three-dimensional positioning and station keeping systems. The Stewart Platform Augmented Manipulator (SPAM) replicates the functionality of the Space Shuttle Remote Manipulator System, with improvements in fine end-point positioning based on the Stewart Platform wrist. The Supplemental Camera and Maneuvering Platform (SCAMP) provides operator-controllable external video views, and has been used for tests of single-operator control of multiple free-flying telerobots.
Focus and Directions:
FY94 Collect data base on advanced telerobotic operations using neutral buoyancy; develop an advanced work site simulation for quantifying performance of integrated telerobotic operations; test EVA/telerobotic cooperative tasks at NASA Marshall Neutral Buoyancy Simulator
FY95 Operate existing telerobotic systems to collect data base on advanced telerobotic operations in neutral buoyancy; develop an advanced work site simulation for integrated telerobotic operations; test EVA/telerobotic cooperative tasks at NASA Marshall Neutral Buoyancy Simulator
FY96 Utilize Ranger technology for rapid prototyping and operations testing of advances concepts for telerobotic and EVA/telerobotic space operations
FY97 Use results from Ranger flight experiment and Ranger NBV to develop extensive data base on telerobotic performance in space operations tasks
Point of Contact:
Dave Akin
(301) 405-1138
dakin@ssl.umd.edu
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