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The joint modeling and simulation system.

Imagine yourself maneuvering in an advanced fighter through hostile territory. As you employ complex maneuvers to evade several enemy aircraft pursuing you, your radar warning equipment indicates you are being tracked by an advanced RF surface-to-air missile (SAM) system. Suddenly, you receive launch warning -- SAMs are airborne and after your jet!

You swivel your seat at the computer workstation where you are running this simulation and switch to a different display mode to analyze each radar pulse received by the tracking radar and observe the effectiveness of countermeasures and maneuvers. The pilots who may have to fly the real mission one day will rely on the data generated and the design decisions you make during this simulation. You're using advanced standard simulation tools being developed now by the Joint Modeling And Simulation System (J-MASS) Program Office.

The state of the modeling and simulation (M&S) art has advanced to the point where we can now create incredibly realistic, extremely detailed models which can augment test and evaluation, support the acquisition process, facilitate intelligence gathering and support detailed engineering.


Within the Air Force Materiel Command's Aeronautical Systems Center at Wright-Patterson AFB, OH, is the office managing the triservice J-MASS program. Under development is a new way to effectively support M&S throughout the Department of Defense.

The program started two years ago; now the initial J-MASS standard architecture and the first models are nearing completion. The program goals include providing the Department of Defense with the structure and software necessary to reduce M&S development and operation costs, increase the performance and credibility of models, increase responsiveness to user requirements and decrease duplication.

The J-MASS program office coordinates the development of the standard architecture and modeling system in response to triservice requirements. A detailed system specification has been completed which documents the extensive requirements generated by triservice working groups over the last two years.


What exactly is this new system? First, J-MASS is a modeling system designed to support engineers, model developers, analysts and decision makers. It implements a series of standards and provides software tools supporting the development, configuration, operation and analysis of models and simulations at varying levels of complexity and detail. In addition, J-MASS provides a library of verified software components for the model designer to use, and J-MASS models are verified and validated before they are placed into this library. Formal configuration management ensures the library retains its integrity. Remember, J-MASS is not a model; it is a system to develop and support models developed in conformance to the basic J-MASS architectural standards.

J-MASS supports models with an object-based design coded in the DOD-standard Ada software language. It is designed to be transportable between different hardware configurations and is built to operate with any workstation using a Posix-compliant Unix operating system.

J-MASS uses an open systems approach. Standards are specified wherever possible, enabling J-MASS software to interface with other standard software. To keep the cost of J-MASS ownership down, a very limited amount of commercial off-the-shelf (COTS) software is being included. COTS software (e.g., an embedded word processor/graphics package) is included only where there is a demonstrated benefit as compared with government-owned or government-developed software.

One of the key parts of J-MASS design is the Software Structural Model (SSM). Based on work from the Software Engineering Institute as well as DARPA, the Software Structural Model defines a template for each object to use. It identifies standard interfaces with the Simulation Support Environment (SSE) and uses information with standard formats. It does not force a modeler to do more work; it simply tells the modeler where to place different attributes of the individual objects, thereby encouraging standardization.

From the perspective of the SSE, objects are processed in the same manner; information is provided to the object when its state is updated and the object provides information back to the SSE. The designer can focus attention on designing the algorithms needed to describe what is being modeled rather than on the style of the model. The J-MASS code generator will be used to transform the algorithms into actual Ada code compliant with the J-MASS software structural model.

One of the benefits of J-MASS will be to allow engineers without extensive software backgrounds to construct detailed models using a concept called "visual programming." This concept will allow the use of standard engineering notation to design a model; the code will flow directly from the engineering.

The ability to readily access existing models and interchange parts can go a long way toward solving current M&S needs. Because models developed under J-MASS have software components that are designed to consistent standards, they can be reused in many new model designs. This approach encourages model developers to focus resources on "new inventions" rather than simply "reinventing the wheel." It supports traditional software verification and validation by giving greater insight into the design of the software while it helps ensure proper documentation. J-MASS defines the style for developers to use, but it doesn't limit their creativity.

Physically, J-MASS includes the SSE and the modeling library as described in Figure 1. The SSE provides the functional support to advanced model developers as well as to model users at lower levels of technical sophistication. The modeling library provides the home for the reusable model components, whole models available to system users, stored scenarios, the environment, geography and other parts of the system.

The SSE supports the modeler in accomplishing any or all of these five basic functions:

* develop model components

* assemble model components into a model

* configure simulation scenarios for execution

* execute the scenario and generate data

* post-processing of the data.

An icon-based user interface assists the J-MASS modeler using clearly laid-out screens. While the ability to develop and assemble models is limited to selected users, the same user-friendly design ensures these tools are responsive to user needs. On-line help and detailed documentation also support the development of models and simulation scenarios.

Develop Model Components

J-MASS models are based on real-world objects or phenomena. The first step in designing a J-MASS system model is to partition the system into its components. Wherever possible, a one-to-one mapping from the physical world to the simulation is maintained. This process continues to the level the modeler needs to provide the detail appropriate to the task. A design engineer may partition a radar system into individual gates and amplifiers in the circuitry, while a systems analyst may decompose the same radar into only the transmitter, processor and receiver. The simulation support environment allows model development to match the needs of the modeler without forcing detail beyond that required.

Assemble Model Components

Once a developer partitions the system into its components, a library of already developed objects can be accessed. Say a design engineer needs a model of a gate. The engineer simply accesses the library, browses through listings and descriptions of the gates in the library and retrieves the one that matches the need. The specific attributes for that object are "tailored" for the specific application. The engineer has now incorporated an object developed and validated by another modeler. The developer has saved time and money and is assured of a quality product because all of the objects in the library have been thoroughly evaluated.

This same process is continued for all of the parts of the system being developed. Usually, in a given simulation, many objects are used over and over in varying configurations but with unique data -- attributes -- to produce very complex models. The model parts are easily connected, since the models are all based on the J-MASS software structural model. J-MASS uses a systems approach to model development.

Configure Simulation Scenarios

Once a model is developed, it can be placed in a simulation scenario. The scenario may be a "one-on-one" simulation where the action of each radar pulse in a system is evaluated or it may be a "few-on-few" simulation where the focus is on system interaction.

J-MASS allows the models in the simulation to be placed in specific physical locations. Terrain is modeled based on data from the Defense Mapping Agency. The appropriate geography, atmosphere, surface cover and other factors are added to the scenario. For mobile models like aircraft, the modeler plans out the route and the initial positions. These scenarios may be stored and retrieved as needed; they can be changed at will to meet a nearly infinite number of "what if" drills.

J-MASS is also being developed to support simulations involving "many-on-many" player interactions. These scenarios will most likely involve lower-detail J-MASS models due to scenario complexity.

Execute the Scenario

During setup, the operator specifies the data required for subsequent analysis. At execution, the scenario is played out and the data are captured in files for subsequent analysis. For the real-time application, data will be available for instant viewing.

Modelers can execute complex scenarios using several different models, knowing that individual models will interact properly because each is designed and built to the same standards!


In the post-processing phase, J-MASS supports an extensive analysis capability. In an emulative radar model, for example, the design engineer can actually trace signals through a circuit. Using "probe" points in the model, much like an oscilloscope, waveforms can be viewed as they propagate through the system as shown in the example in Figure 2. Engineering graphs can be generated as well as tables; maps; traces of actual versus predicted value, position or location; and almost any imaginable representation of the data. It is the post-processing phase where most of the detailed analysis is actually conducted, including report preparation.


Today J-MASS supports non-real-time (slower or faster than real-time) modeling, but on-going work to develop a real-time capability is underway. J-MASS provides modelers with the ability to model at the level of detail needed -- no more or no less.

As an example, for detailed EW analysis, engineers need extremely detailed systems to develop and prove techniques for electronic combat. This may require a level of detail adequate to actually "trace" a signal through a circuit. The J-MASS SAM models available today allow this level of emulative simulation. For analysis requiring less detailed models, dynamic-level J-MASS SAM models are also available. In short, J-MASS supports simulations at varying levels of detail to meet the requirements of modelers across the spectrum.

The J-MASS project has developed a working prototype of the Simulation Support Environment which proves the basic concepts and evolves the J-MASS standards to the point where the first, formal release is nearing completion (release is scheduled for January 1993). High-, medium- and low-fidelity models of several different SAMs are being completed in conformance with the J-MASS standards to prove the modeling architecture, the Simulation Support Environment and the software structural model.

The first version of the tool to support the partitioning task of model development is nearing completion. This tool will support production of object orientated design with assemblies (OODA) drawings used in all J-MASS models. These OODA drawings provide the major input to the J-MASS code generator, now available. Through extensive triservice participation, the software requirements have been well documented and the program office will be continuing accelerated development of J-MASS in FY 1993. A top-level J-MASS schedule is shown in Figure 3.

The initial capability of J-MASS is limited compared to the total system specification, but the work underway now will result in a release in Fall 1993 incorporating a more robust capability for the system. Functionality throughout the SSE will be provided, allowing the user to log on to J-MASS and develop components, assemble them into models, configure a simulation scenario and place players within the scenario, execute the simulation and analyze the results through postprocessing. Thus, the J-MASS capability will continue to increase rapidly.

The program office is developing the ability to allow existing models to be interfaced with J-MASS so the J-MASS tools can be used to enhance their performance. This allows modelers who have made large investments in existing models, called "legacy models," to reap some of the benefits of J-MASS.

In addition to the annual symposium, the J-MASS program office sponsors several government/industry working groups to review the requirements from the modeling community and to ensure J-MASS developers stay attuned to these needs. Moreover, these groups allow for free and open exchange of ideas and current modeling and simulation activity and provide a forum for feedback to the program office. For additional information, contact the J-MASS Program Office, ASC/RWWW, Wright-Patterson AFB, OH 45433 or log onto the J-MASS bulletin board on Tecnet.


To support an engineer's ability to design and build a "virtual prototype" of a proposed system without requiring him to have an extensive software background, J-MASS will provide the visual programming environment mentioned previously, where the model builder can design using standard engineering notation. The electrical engineer, for example, can design a circuit and J-MASS will provide a series of icons representing the parts of the circuit under design. "Behind" each icon will be the required Ada code. The engineer will merely tailor the parts for the specific application and the J-MASS software will link the parts to form the model. Standards such as the software structural model help engineers focus on their specialty and not on the programming aspects of M&S.

Over the next several years it is envisioned there will be robust libraries filled with verified modeling components and full models which have been verified and validated, available to support DOD users from every discipline. On-line, interactive, easily understood documentation will be available. Models developed by several organizations will be operated interactively and the results will be credible. Threat models will reflect the most current intelligence information and will be consistent with the threat models used throughout the test process.


J-MASS supports triservice M&S efforts at many levels of detail and at modeling complexities from one-on-one to more complex scenarios. The J-MASS program is designed to fill the modeling niche supporting the engineering development, acquisition and test and evaluation communities.

Figure 4 shows the relationship between J-MASS and the training and the wargaming simulation systems. This relationship notes the requirements for synergy between the various systems and the overlaps between them. For example, J-MASS model output is structured to provide detailed analysis to support simulations of entire campaigns. These models, which are used to evaluate the interaction of thousands of participants, can only be effective if the information used to describe each participant is accurate. The models developed using J-MASS standards will provide this valid information and can also be structured to support training simulations.


With reduced budgets, increased requirements to thoroughly test every concept and an increased emphasis on virtual prototyping, the Defense Department will be relying more on M&S. The J-MASS program is developing software which will provide the means necessary to satisfy this demand while greatly improving the ability of M&S to meet user requirements. Through triservice participation, a system is evolving which will meet the needs of diverse modelers, analysts and decision makers. Standard methodologies and reusable code will help keep the cost affordable, and the open systems approach will ensure the system is usable by the widest possible audience.

J-MASS is providing the tools for the DOD to improve M&S and realize the potential benefits. In concert with training simulations and wargaming systems, the models developed using J-MASS standards will become the baseline for a new generation of tools for engineering analyses, test and evaluation.

Randy E. Brown is chief of the Lethal SEAD and Simulation Division, Electronic Combat Directorate, Aeronautical Systems Center, Wright-Patterson AFB, OH. A graduate of the Defense Systems Management College, Program Manager Course, Brown holds an Acquisition Professional Development Program Level III certification.

William K. McQuay is chief, EW Requirements Group, Requirements and Effectiveness Evaluation Branch, Electronic Warfare Division, Avionics Directorate, Wright Laboratory, Wright-Patterson AFB, OH. He directs the Electronic Combat Simulation Research Laboratory and is chairman of the J-MASS Architecture Technical Working Group. He has a BS (mathematics) from Towson State College, a master of applied science (operations research) from Southern Methodist University and an MSEng (computer science) from Johns Hopkins University.
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Title Annotation:simulation of military manuevers
Author:Brown, Randy E.; McQuay, William K.
Publication:Journal of Electronic Defense
Date:Sep 1, 1992
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