Modeling and Simulation: Its Growing Importance
Modeling and Simulation (M&S) is a critical capability employed in developing and using complex systems. M&S supports the entire product life cycle, from initial concept development to design, integration, test and evaluation, deployment and sustainment, and future evolution. Since there is substantial variation in the purpose, type, fidelity and complexity of analyses performed across the program life cycle, Raytheon’s M&S portfolio offers a wide spectrum of tools, from spreadsheet-level to detailed high fidelity simulations.
The ultimate objective of an M&S activity is to provide the basis for making technical and programmatic decisions. From early concept studies (Is the idea feasible?), through test and evaluation (Does the system meet its requirements in real world environments?), the system development process is all about making sound data-driven decisions. Obtaining this information by testing the actual system is generally impractical because the data are usually needed before the system has been built, and is too expensive because the range of threat and environmental parameters would necessitate an enormous quantity of testing. Thus, a strong M&S capability is needed to provide the data to inform the system development process.
The fidelity and pedigree of simulations and their associated models must be appropriate for the depth and breadth of the studies being done. Figure 1 illustrates the range of tool fidelities and how they are applied to programs based upon the system maturity (or Technology Readiness Level [TRL1]) and analysis objectives. Several of the simulation analytical tools discussed in this issue are represented here. Lower-fidelity analytical tools, such as the Operations Analysis Toolkit (OpsTool) shown in Figure 2, are generally preferred for initial system conceptual or architectural studies because they permit a broad range of alternatives to be studied relatively quickly and because the system parameters are not yet known to a precision that would justify a higher-fidelity simulation. As the system design matures, higher-fidelity, forward-time digital simulations replace analytical tools and more generic simulations to support algorithm development and detailed performance predictions. The all-digital simulations are eventually supplemented by software/ hardware-in-the-loop (SIL/HWIL) simulations to support system verification and validation and pre-flight preparation (Figure 3). At all stages of development, immersive virtual simulation provides a realistic environment for concept of operations (CONOPS) definition and evaluation, operator training, and tactics, techniques and procedures (TTP) development and refinement.
Traditionally, distinct simulation tools were used for different parts of the development process. Early analyses using low-fidelity desktop tools would give way to detailed simulations as the design progressed. Eventually SIL and HWIL environments would be created, which might or might not have some commonality with the digital simulation. All of these were often custom tools created specifically for each program. This resulted in duplication of effort, high cost and potential difficulty in reconciling results from different simulations. Also, simulation efforts often involved a tradeoff of fidelity and breadth; individual systems used very high-fidelity simulations, but that fidelity was often reduced when applied to the analyses of more complicated systems of systems (SoS). Today, we apply a more integrated approach that is based on rapidly configurable simulations that can grow in fidelity as a system design matures from its initial trade studies through SIL/HWIL testing. An additional benefit of this approach is the ability to integrate multiple simulations into high-fidelity SoS testbeds. Additionally, Raytheon exploits the explosion of computing technology to support high-fidelity target and environment simulations as well as immersive visualization environments to facilitate concept of operations (CONOPS) development and training. In this issue of Technology Today we illustrate these trends by highlighting some of the M&S tools and initiatives currently ongoing at Raytheon.
Rapidly Configurable, Modular Simulation Environments
To minimize systems engineering cost as well as to speed the development process, we need to avoid starting from scratch when developing system simulations. genSIM, discussed in the article “Using the genSim Family of Simulations for System Design,” provides a framework for rapid, low cost, low risk simulation development. genSIM supports the entire life cycle, permitting increased fidelity as a design matures from initial concept studies through HWIL testing. Two examples of simulation environments tailored to specific technology areas are described in the articles “Interoperability Analysis of RF Systems” and “Cyber Analysis Modeling Evaluation for Operations (CAMEO) — Countering the Cyberthreat.” The former discusses the Communication System Engineering Toolset (COMSET), which provides a simulation environment and process that facilitates the analyses of RF systems in complex spectral environments. COMSET supports single system performance evaluation and interoperability analysis of multiple RF systems located on the same or separate platforms. CAMEO is a toolset for analyzing cyberthreats and the efficacy of countermeasures. Recognizing the dynamic nature of today’s cyberthreat, CAMEO allows active defense measures such as cyber maneuver and random reconstitution to be assessed.
Full Life-Cycle Simulation Support
As previously mentioned, simulation fidelity typically grows as the system matures. While initial studies often rely on analytical tools, forward-time simulations are necessary for assessing complex interactions (such as the scheduling and resource loading of a multifunction radar). These simulations will rely on lower-fidelity representations of the system since the detailed design is not complete and thus high-fidelity representations are not necessarily appropriate. As the system development progresses, the simulation fidelity can and must increase. That said, it is undesirable to throw away the initial low-fidelity simulation and start all over with a higher-fidelity one later in the process. What is needed are tools that support system simulation efforts and can keep pace with the product development, by increasing simulation fidelity as the system matures. One such tool is described in the article “Raytheon Air and Missile Simulation: A Selectable Fidelity Tool for Radar and Systems Analysis.” RAMS, employed for the analysis of radar performance and algorithm development, uses a modular architecture that permits the replacement of generic modules with higher-fidelity system-specific ones as the design matures. RAMS supports a range of simulation needs — from early concept evaluation through system-level end-to-end performance assessments and detailed waveform and processing development — simply by plugging in the appropriate models.
System of Systems (SoS) Testbeds
The ability to integrate multiple system simulations, either co-located or distributed, to explore and evaluate the capability of higher-level systems of systems is a critical enabler for exploiting the breadth of Raytheon’s products and maximizing value for our customers. This ability optimizes collaboration both among Raytheon’s global businesses and with government and industry partners. The article “System-of-Systems Testbeds” highlights three examples of SoS testbed environments currently in use at Raytheon. These include the AerospaceGround Integration (AGI) Testbed that supports analyses of airborne and space platforms, the Joint Force Interoperability and Requirements Evaluation SupraCenter (JFIRES) that supports the integration of air and missile defense systems (Figure 4), and the Air Dominance Test Bed (ADTB) used for weapon system kill-chain analyses.
Visualization and Training
The ability to integrate the user into a simulation environment is valuable during the development and evaluation of operational concepts and for providing immersive training for the operator. “Virtual Environments: Creating Immersive Simulations and Trainers” describes how Raytheon is leveraging video gaming technology to provide realistic 3-D visualization of modern warfare. This not only supports operator training, but allows the effects of actual human behavior to be included in the evaluation of real systems. “Embedded Training in the Modern Command and Control Environment” discusses Sculpt™, a powerful tool for designing, controlling and modifying training scenarios in order to maximize training flexibility and effectiveness. Sculpt enables the trainers to create realistic and relevant scenarios, and to modify them in real time in response to the operators’ actions.
Simulation fidelity (both all-digital and HWIL) is only as good as the simulated threats and environments being used. As processing algorithms become more sophisticated, sensitivity to the subtle characteristics of a target and environment increases.
Furthermore, the desire to reduce live testing through more extensive use of simulation necessarily requires the highest possible threat and environment modeling fidelity. This puts a premium on the ability to generate, in hard real time, high-fidelity input signals with the precision necessary to adequately exercise advanced processing and algorithms. “Radar Digital Signal Injection System (RDSIS)” describes a simulation driver developed for the X-Band family of radars to inject high-fidelity time domain in-phase and quadrature (I&Q) radar returns into the signal processor, permitting closed-loop evaluation of the entire signal and data processing chain. In addition to stand-alone radar testing and algorithm development, RDSIS is used to drive the radars during Ballistic Missile Defense System level testing.
The generation of complex high-fidelity radio frequency (RF), electro-optical (EO) or infrared (IR) input scenes and sensor images in real-time requires significant computing throughput. “Accelerating Simulations Through the Use of General Purpose Graphical Processing Units,” a sidebar to the genSim article, discusses the use of general purpose graphics processing units (GPUs) for this purpose, exploiting the massively parallel computing approach which these processors excel at.
To best leverage the breadth of its products, Raytheon relies on the collaboration of engineers in geographically disparate locations. In particular, the ability to share system and simulation data at appropriate classification levels between locations in order to facilitate SoS analyses is vitally important. “Enterprise Modeling and Simulation (EMS): Enhancing Cross-Company Collaboration to Improve the Quality of Solutions that Raytheon can Offer Our Customers” discusses Raytheon’s EMS efforts which have implemented companywide data sharing networks that allow engineers to collaborate more efficiently.
M&S supports more than system performance evaluation. “Phased Array Availability Modeling and Simulation: Techniques for Efficient and Effective Performance Modeling” illustrates the application of M&S to the life cycle cost arena by integrating the logistics and availability models for X-Band phased array radars. The article describes tools and methods used to estimate and assess system reliability and availability to facilitate tradeoffs between component reliability, maintenance schedules and sparing quantities to most cost effectively meet system availability requirements.
This issue provides a mere sampling of the extensive M&S capabilities Raytheon engineers apply every day to the development, test and evaluation, and operation and sustainment of complex systems. From initial concept development through fielding and sustainment, our M&S technologies provide value to our customers by ensuring our products meet their expectations and by reducing the need for expensive live testing.
1TRL is a measure used to assess the maturity of evolving technologies.
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