Applying an Open Systems Approach to Develop Federations of Legacy Simulations

A System of Systems (SoS) Integrator must be able to assess integrated system performance in order to characterize a system being deployed and to determine the impacts of proposed product improvements and additional functionality. In many cases, the representations of the “as built” system components are legacy simulations developed by industry and program offices. Integrating such legacy simulations into a single federated, modeling and simulation environment is an attractive solution to developing an end-to-end system simulation. This federated approach allows the system integrator to incorporate many different models in the analysis efforts, across multiple infrastructures, increasing accuracy and consistency while helping to reduce redundancy in development efforts. Unfortunately, many legacy simulations have been developed in an evolutionary manner using different software architectures and languages and have been accredited for specific uses. Many are proprietary and have been developed by international partners. The software modifications necessary for inclusion in a federation are therefore difficult and expensive. This paper will describe and demonstrate open system techniques and architectures for minimizing the software changes needed to federate legacy representations into well-known international industry simulation infrastructures, such as the High Level Architecture (HLA), Boeing-developed runtime frameworks, as well as commercial infrastructures such as MatLab Simulink. The approach utilizes Boeing-developed products that allow HLA models to be Federated Object Model (FOM) independent. It also provides well-defined interfaces that can be provided to other programs during simulation development, resulting in minimal integration effort when the new simulation becomes available. The open systems approach is currently being used by the Boeing Company to develop an end-to-end simulation of the ballistic missile defense system.