Technology Today

2013 Issue 1

Using the genSim Family of Simulations for System Design

For more than a decade, Raytheon has been working on an integrated suite of tools geared to support simulation development through the entire product life cycle. These tools are genSim, genIR and genRF, and they offer users and customers a flexible, reliable, cost-effective and proven solution to their simulation and modeling needs. Each of these tools incorporates “gen” in their names to reflect the design goal of being a “general-purpose” simulation capability that is adaptable to programs across many product lines. The use of genSim, genRF and genIR has helped reduce the risk and number of expensive field tests by allowing system components and software, such as today’s cutting-edge signal processing algorithms, to be matured and extensively tested in simulated environments prior to field testing.

genSim Provides the Simulation Infrastructure

At Raytheon, program simulation development usually begins with an infrastructure and a set of core tools that can be leveraged to quickly develop simulations at low cost and risk. For nearly ten years, programs have used genSim (Figure 1) as the base simulation architecture to provide the infrastructure and tools required for rapid weapon system digital simulation development.

As an advanced, off-the-shelf simulation framework solution, genSim supports the complete life cycle, from simulations that perform initial trade studies through hardware-in-the-loop simulations that support program flight tests. To provide such a range of capabilities, genSim combines a complete six-degrees-of-freedom (6-DOF) simulation with a rich development environment. Using the genSim architecture, engineers can quickly and efficiently stand up simulation capabilities, add program-specific modules and/or increase fidelity by expanding existing modules. An existing collaborative user base and multiple model repositories enable model reuse and agile support.

Figure 1: genSim provides the simulation framework and truth models. Programs insert
their specific hardware and software models as needed.

genSim uses an object-oriented, module-interchangeable framework, which provides a means to test multiple levels of fidelity for individual modules or entire systems. It supports integration with third-party models, operational flight software interoperability via genSoft and distributed simulation implementations for multicore processing environments. genSim also provides real-time synchronization and timing analysis capabilities that are required for computer-in-the-loop and hardware-in-the-loop simulation environments.

Leveraging capability originating since 2002 from successful genSim simulations developed for the Mid-Range Munition (MRM) and the Miniature Air Launched Decoy (MALD), the Small Diameter Bomb (SDB) program has generated a series of genSim-based simulations for multiple purposes, from the all-software Integrated Flight Simulation to the real-time Computer-in-the-Loop simulation that employs selected flight test hardware. SDB also incorporates form-factored flight software in the simulation using genSoft™. This genSim/genSoft-based approach allows for seamless integration of the embedded flight software during missile buildup, which will have significant utility as SDB embarks on its flight test program to demonstrate the capability of the tactical design.

genRF Models Radio Frequency (RF) Systems

The General-Purpose Radio Frequency Signal Generator (genRF) is a signal generation model that represents the performance and characteristics of an RF system in a simulated environment. genRF provides a common set of modules and capabilities so that users can configure the model environment to match a particular radar system (Figure 2).

Figure 2. Driven by user inputs, genRF models scene interaction and sensor effects to
provide users with raw and/or processed signal data as output to be used to develop
and test signal processing and other system software.

By allowing for variable configurations and fidelity modes, genRF is capable of supporting scene generation and sensor modeling throughout the product development life cycle. Users are able to simulate a variety of scenarios and effects, including self-defined waveforms, geometries of interest, electronic warfare environments and specific hardware components.

genRF provides a multitude of RF simulation and analysis capabilities, enabling users to develop and assess performance on a variety of different RF system designs and algorithms. Integrated into genSim, genRF provides simulation capabilities ranging from initial trade studies through to system hardware testing.

genRF can provide rapid results using effects-based models, and it can also use time-domain models to supply data that includes pulse-to-pulse motion effects. When simulation run-time becomes a concern, genRF offers a General Purpose Graphical Processing Unit (GPGPU, see Accelerating Simulations Through the Use of General Purpose Graphical Processing Units (GPGPUs)) accelerated implementation that can reduce data generation times by an order of magnitude or more. Additional configuration parameters allow users to modify their scenario setup, providing the ability to perform system trades on different hardware and software components and to assess performance in different terrain, clutter and countermeasure environments. The tool has been integrated into multiple genSim-based integrated flight simulations, and it can be used in a single-point, stand-alone mode. Users can leverage and extend genRF’s built-in telemetry system and analysis scripts to meet individual processing needs.

Among the recent genRF development efforts are the real-time simulation capabilities used to enhance support for computer and hardware-in-the-loop environments and to improve flight simulation throughput.

Technology demonstrations utilizing genRF and genIR (described in the next section) have proved the capability to simultaneously simulate both RF and infrared (IR) sensor data for multimodal sensor applications. The ability to support stand-alone analysis, integrated flight simulation and system hardware testing makes genRF a perfect fit for Raytheon’s external and internal customer radar analysis needs.

genIR Models Infrared (IR) Systems

The General Purpose Infrared Sensor Model (genIR) is a next-generation imaging sensor model developed for use in closed-loop digital simulations. Using physics-based models in combination with laboratory measurements and/or statistical models, the genIR architecture provides a unified way of modeling infrared cooled and uncooled sensor camera optics and video hardware. genIR exists as a user-configurable package designed by subject matter experts in electro-optics (EO) technology, using best practices of simulation software design. genIR benefits from an active user and developer community continuously adding to its model knowledge base.

Figure 3. The simplified genIR pipeline block diagram shows the modularity of genIR,
which supports stand-alone and embedded digital simulations.

genIR consists of object-oriented C++ software modules that model the EO/IR missile seeker and surveillance sensors from programs across Raytheon. As shown in Figure 3 the model architecture contains physics-based modules aggregated into processing pipelines that work together to accurately model imaging infrared seeker optics and the electronics front-end for IR hardware. genIR is a proven technology used today in major programs, independent research and development efforts, signal processing algorithm development, and other modeling and simulation activities. Its highly configurable modules make it a perfect choice for engineers seeking to model specific EO/IR sensor behavior in their analyses. genIR provides an extensive pedigree through verification and validation efforts performed in multiple programs, which include comparisons with theoretical calculations, captive flight tests and free flight data.

genIR is designed to be compatible with genSim and other simulation frameworks, as well as being capable of running in stand-alone mode. Many programs have substantially lowered their design and development costs by leveraging this technology, and many others are currently investigating its applicability. genIR supports the complete life-cycle process, including sensor pre-design, algorithm development and software- and computer-in-the-loop performance testing (Figure 4).

Figure 4. genIR supports many different use cases for complete lifecycle support.
Future Applications

The genSim family of simulations is poised to expand into additional system design activities, such as cost modeling and reliability, in order to support robust and affordable system solutions. While future developments of genRF and genIR will increase model capability, genSim development will focus on new features requested by the growing user base. We are also looking to apply our software and analysis tools to broader system design challenges in the other Raytheon businesses.

C. Russell Hanson, Anibal Morales,
Edward Romic and Juan Carlos Salcedo

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