VLAB - Virtual Simulation Laboratory of the Future
by Pat Kaspar |
Issue 4, January 1998 Welcome to the on-line version of NASA's Insights Magazine.
Insights is published by the High Performance Computing and Communications (HPCC) Program Office. To receive a hard copy of Insights or request an address change contact Judy Conlon or write to: NASA HPCC Insights, Mail Stop 269-3, Moffett Field, California 94035-1000, USA
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NASA's Russell Sansom authored the computer interface software that allows Houston engineers full immersion in simulations conducted at the world's largest aeronautics motion simulator (cover photo) via NREN. |
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How do you cut costly aerospace design time to keep America on the cutting-edge of a highly competitive global market? NASA addresses that question by aggressively integrating simulation, wind tunnel testing and computational fluid dynamics into the aircraft design cycle, with Ames Research Center (ARC) simulators playing a central role. In the past, researchers have had to travel to ARC to use the simulation laboratory, SimLab. Now, due to advances in high-performance networking, they can avoid costly, time-consuming travel and participate collaboratively in tests from their own desktops by using "VLAB," a Virtual Laboratory. Remote participation in VLAB simulations is made possible by the high-speed, high-performance NASA Research and Education Network (NREN), part of NASA's High Performance Computing and Communications (HPCC) Program. ARC simulators are high-fidelity, research-oriented facilities that allow industry to repeat design steps with piloted simulations. The ARC Vertical Motion Simulator (VMS) has the world's largest motion basis (40 feet wide by 60 feet tall) and has been used for shuttle, high-speed transport and tilt-rotor simulations. The VLAB provides researchers with a collaborative environment in which they can share actual research data. "Our goal," said Chris Sweeney, senior simulation engineer at the VMS, "is to allow you to do the same research you could do if you were in the lab. VLAB was developed in house using a combination of off-the-shelf technology and custom simulation code in use at the VMS. It provides two-way communications, sound, video, data files, real-time animation of the simulator cab in motion and the ability to move around in the lab as if you were there." The initial successful demonstration of VLAB over an ARC local area network (LAN) proved the concept of a virtual lab. A proposal was then made to demonstrate VLAB over a wide area network (WAN) connecting ARC with Johnson Space Center (JSC) in Houston, Texas. In order to work in a distributed environment, the VLAB required reliable, high-speed, wide area connectivity to support the client/server connection, along with digital audio, MPEG-2, audio/video conferencing and whiteboarding. That was the challenge presented to NREN in spring 1997. By integrating advanced communications systems and high-performance networking to allow researchers to collaborate in real time, NREN provides a capability which is not possible using today's Internet. "Engineers have to be able to see what is happening in near real-time so they can react to it," said Ken Freeman, NREN engineering manager. "The technical challenge was to provide a network with latency (delay) low enough to handle the video component, MPEG2, because MPEG picture quality is sensitive to latency and jitter. We needed consistent bandwidth between ARC and JSC." The first demonstration of the VLAB system via the NREN wide area network communications link was successfully conducted in June 1997 when engineers at JSC participated in VMS Space Shuttle landing simulations.
Early contact with NREN managers convinced NASA's Chris Sweeney and Steve Cowart (below) that NREN could provide the speed and bandwidth needed for data transfer between Houston engineers and the Ames Research Center simulator. "With VLAB you can participate as well as just watch," said Steve Cowart, VLAB project lead and manager of the Systems Maintenance and Operational Group at SimLab. "This collaborative tool is especially useful and broadly applicable." The remote researcher's "lab" is an exact copy of the SimLab Control Room. One monitor shows the same "out-the-window" view that the pilot sees as he lands the shuttle. Another provides two-way videoconferencing, a whiteboard for messages or images, and remote data file access. The central screen is an "active" 3-D model of the Control Room. Researchers can select items and arrange their screens to display, for example, the pilot's Heads Up Display, strip charts, the cab and motion system, a schematic of the shuttle as it lands or all of these. A joy stick allows them to "move" around in the room and even "step back" to see a 3-D version of the entire VMS including the building interior, the control room and the movement of the cab. Russell Sansom authored the computer interface software that allows full immersion in the simulation. His fascinating 3-D "sticky cursor," which looks like a green laser beam coming from the bottom of the screen, allows researchers to select various boxes. "It's connected to the sides of the screen by lines that help anchor it," said Sansom, "and it 'sticks' to objects that can be selected."
The SimLab team had been working on VLAB for several months prior to the JSC demonstration when Fred Schmitz, Director of Aeronautics, offered support if they would deliver a complete demonstration with JSC in six months. "We used code we had already developed but added an immersion element so the remote user could share in the experience of being in the SimLab," said Cowart. "Flight simulation is virtual reality, and simulations are already remote by nature, even if they are in close proximity physically to the Control Room. SimLab uses a local network at SimLab. What we did was to stretch that out over the NREN wide area network to the VLAB client at JSC. "To meet the deadline we worked everything in parallel," continued Cowart, "especially the question of how we were going to get the data back and forth. Our network team looked first within ARC to see who could provide the speed and bandwidth we needed. Our first meeting with the NREN team was very positive. Christine Falsetti, NREN project manager, was already familiar with the project and agreed to partner with us. NREN's readiness to support us was critical in getting the project going. "We needed guaranteed bandwidth, as 'guaranteed' as possible, and real-time participation. The researcher at the remote end can't be made to wait to see what's happening. At first we used video technology also for audio, but the software required the researcher to be attached to the computer with a wired headset, a very user-hostile situation. Our solution was to use a pair of products from ASTi and Telex which enabled us to provide sound using remote wireless headsets at both ends. "Simulations play a central role in the aircraft design cycle," said Cowart. "We want to use this technology to help reduce the time it takes to develop aircraft. It's less expensive to evaluate design steps if the pilot's assessment is part of the process," he said. "When you combine simulation with computational fluid dynamics and wind tunnel testing, you can make better decisions earlier in the process. VLAB is now a proven research tool that allows remote users to participate and manage the simulation, and to configure their screens the way they desire. Future versions will improve the collaborative feel of VLAB by integrating virtual reality helmets and enhanced input/output elements. You can extrapolate this technology to any kind of product." NREN engineers also learned from the demonstration. "It clearly showed that MPEG cannot be run over low-performance networks," said Freeman. "We learned that this type of video application is very sensitive to competing traffic on the network. We have to be able to guard against latency and jitter in order to provide the quality of service required." Remote engineers can't yet give the shuttle a flat tire at the push of a button, but they can request changes in the parameters of the shuttle landing, using VLAB, which are then carried out by SimLab personnel. "The JSC demonstration was a huge success and generated a lot of interest," said Cowart. "We're under tremendous pressure to broaden the application of VLAB today, but we have to balance those pressures with the need to proceed according to plan." "Build it and they will come" no longer applies to today's networking world. Scientists and network engineers must work together to meet the research challenges of the future. The technologies and methodologies employed in VLAB will be applicable generally to remote access, virtual laboratories offering immersive environments, and interoperable facilities, and will provide broad access to national facilities by U.S. industry. VLAB will provide convenient access to national simulation resources that will enable industry to improve its design process, yielding aeronautical products with a true competitive edge. NREN has already helped scientists collaborate on echocardiography over great distances, it has made it possible for researchers to operate rovers remotely on Mars and in the Chilean desert, and it proved critical to VLAB's success - collaborative simulation has arrived for NASA. For more information see:
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