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Connecting the Dots
GTRI helps create new networking standard By Gary Goettling |
Soldiers and pilots who can train together on networked simulators not only learn how to handle military situations, they develop the teamwork that's essential for a successful mission.
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But F-16 pilots operating a simulated mission in an anechoic chamber in Maryland might not be network compatible for a simultaneous mission simulation with an enemy air defense system in Houston and a test control group in New Mexico. Likewise, NATO member nations might have difficulty with allied forces training using various nations' warfighting systems simulations.
The solution is a common, high-level network architecture for an array of simulators widely differing in age, purpose and technological complexity. The U.S. Defense Department began work on this new standard in the mid-1990s under the auspices of the Defense Modeling and Simulation Office and a consortium of government, industry and academic researchers.
Among those involved are Georgia Tech Research Institute (GTRI) engineers, who began supporting the development of the new High Level Architecture standard four years ago. It is challenging work, in part because the development of High Level Architecture (HLA) — a general purpose architecture for simulation reuse and interoperability — is dependent upon a host of ever-changing technologies, says Senior Research Engineer Margaret Loper. She is one of 12 members of the Distributed Simulation Systems (DSS) research team, a part of the Information Technology and Telecommunications Laboratory at GTRI.
Distributed simulation is a technology area that has grown increasingly reliable and realistic because of the evolution of all the technologies that go into it, Loper explains.
"You can run very powerful, realistic-looking simulations on a PC, whereas 10 years ago you had to have a very high-end Silicon Graphics machine to be able to do it," Loper says. "So the networking simulations are just one part of the picture. You also have to deal with all the advances in graphics and visual systems, hardware platforms, communication networks, artificial intelligence and behavior modeling. The list goes on and on."
GTRI's responsibilities in the development of technologies that support HLA embrace several major initiatives.
High Level Architecture Testing and Support
Searching the Web for information can be maddening. Sometimes even the most careful entry of key words into a search engine can return hundreds of hits with no apparent relevance. Imagine the frustration when the search is for information in a highly specialized field such as modeling and simulation.
WebBook is a Georgia Tech Research Institute (GTRI) initiative to build an on-line library of modeling and simulation knowledge. More importantly, its authors are testing new ways to electronically organize information to make online research in other subjects far more productive, as well.
Content and functionality — those are the chief concerns of the WebBook project, says GTRI researcher Andrew Old. He heads a group that has built a WebBook prototype and is working on a production-quality Web site.
"Our goal is to meet a need in the modeling and simulation community for access to comprehensive reference material," he says. "A lot of advanced research information has not been captured in an organized fashion, and even established fundamental concepts are not always easy to find. It's good there's so much information out on the Web, but all that information also makes it difficult to find specific answers."
Old and his team elected to build a database-driven Web site to store all the modeling and simulation material they could gather. The site is interactive in that experts can submit information to fill gaps in the overall body of information, and they can add new research reports to the database.
The tricky part is figuring out a way to organize and index the information so it's readily accessible to experts and non-experts alike. To start, WebBook data is divided into text blocks or articles of up to 2,000 words each. Each article is defined by a set of attributes or keywords linked explicitly to other articles with the same keywords. Or articles can be linked implicitly by keywords that are similar or related, but not exactly the same.
WebBook users enter the appropriate terms into a search engine that selects matching articles and presents them as an electronic book.
"Articles can be organized in a different ways to create these taxonomies or books that can be geared to different types of users," Old says. "So, for example, if you're new to the world of modeling and simulation, there's a book geared toward you with the basic concepts you need to know.
"A lot of times, people don't quite know what to search for specifically," Old adds. "If we can present these articles as a book, then they don't necessarily need to know — they can just browse through the book."
The implicit article links will help users narrow or broaden their searches without starting over. "They give the user the ability to navigate to another article or find out about the existence of that article even if they're not in the same book," he says.
In addition, WebBook gives users the option of selecting additional articles on a subject in either greater or lesser detail, depending on the specificity of their needs.
Although WebBook will be devoted to modeling and simulation, its methodology could be widely applied.
"You can plug in any type of content to serve any community you want," Old says. "The basic idea is simple: It's getting the right information to people in the easiest format possible."
For more information, you may contact Andrew Old, Information Technology and Telecommunications Laboratory, Georgia Tech Research Institute, Atlanta, GA 30332-0800. (Telephone: 404-894-7256) (E-mail:
andrew.old@gtri.gatech.edu)
— Gary Goettling
Federation Verification Tool
"Once you bring your simulations together and you've got them talking, sending data back and forth using the HLA, how do you verify that all the simulations are really doing what they're supposed to be doing?" says Loper, in framing the task before the GTRI researchers.
Typically, a network of simulators is employed to model a large, complex scenario. The scenario's accuracy depends upon the proper interaction among the individual simulators in the network.
"Each simulation has its own set of rules and responsibilities about what it's supposed to do — whether it's modeling aircraft or tanks, where and when it's supposed to move, what it's supposed to fire at and under what conditions," Loper says. "The federation verification tool runs while the simulations are interacting. It knows what each simulation is responsible for, and it verifies that each one is doing what it is supposed to do. If there's a problem, the tool can pinpoint the simulation that may be causing others problems in the network."
Advanced Simulation Technology Thrust
Dr. Richard M. Fujimoto of the Georgia Tech College of Computing accomplished the first part of the task by devising architecture specifications that allow simulations with different needs to share a time-management reference. The project's next phase involves developing the next generation of time-management algorithms that will allow disparate simulations to effectively work together.
High Level Architecture Simulation Interface
This project has resulted in the development of a software tool, the Distributed Simulation Interface Framework (DSIF), which is being used to migrate simulations to HLA.
MIMI HLA Model Migration
MIMI, which stands for the Mobilization and Deployment Capability Assurance Project (MADCAP) Integration Management Initiative, is a model used by the U.S. Army Forces Command to plan the mobilization of soldiers for military contingencies. GTRI used the DSIF tool to build a software interface between MIMI and the HLA.
"Now that MIMI supports the HLA standards, the model, which was previously used only in stand-alone mode, can be linked with other DoD simulations for training, analysis or acquisition," says DSS researcher David Roberts.
Human Behavior Modeling and
"This project is a good example of how the HLA can make a difference," Roberts explains. "Simulations that were developed for different reasons can now be brought together into one environment for training and new concept development."
GTRI's original role in the HLA project was development of the test process, procedures and tools for determining whether a particular simulation complies with HLA. A professor from the College of Computing was also assigned the task of designing and documenting time-management services for the HLA interface.
in a Haystack
On-line search tool organizes information into electronic books.
Another testing project, this effort focuses on testing a group of networked simulations called a federation.
When it comes to getting simulations to work together, timing is everything. The trick is to develop time-management specifications that eventually will allow synchronization of simulations varying greatly in internal architecture, function and purpose. The specifications would even address the need to track time — some simulations are more time-management reliant than others.
With the advent of the HLA, existing simulations can be called legacy systems because they were not designed to operate in the new HLA environment. So GTRI is now developing interfaces, tools and procedures to allow legacy systems to migrate or connect to HLA.
In another project, GTRI researchers have drawn upon their work in HLA to bring an operational legacy simulation into an HLA environment.
One of the new research areas for the DSS group combines its HLA experience with research conducted in Georgia Tech's School of Industrial and Systems Engineering by Dr. Christine Mitchell. DSS researchers are building a model of the decision-making process used by a military squad leader operating in an urban environment. This model will help evaluate the information requirements needed to design computer displays helpful to the soldier. Using HLA, this model of the soldier can be integrated with other simulations to evaluate requirements in a realistic simulated environment in real-world military exercises.
For more information on the Distributed Simulations Systems group and their HLA research, point your Web browser to
http://dss.gtri.gatech.edu. You may also contact Margaret Loper, Information Technology and Telecommunications Laboratory, Georgia Tech Research Institute, Atlanta, GA 30332-0832. (Telephone: 404-894-4663)
(E-mail:
margaret.loper@gtri.gatech.edu); or David Roberts at the same address.
(Telephone: 404-894-3135)
(E-mail: david.roberts@gtri.gatech.edu)
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