Dahmann further unwinded the “trapeze model” in the SE guide for SoS to an intuitive time-sequenced “wave model” that is well recognized by the acquisition and SoS community. SE Guide for SoS and Defense Acquisition Guidebook (DAG) provided useful guidance on streamlining the evolutionary acquisition process. Department of Defense (DoD) has made a significant effort to address the complexity of SoS evolution management from the Systems Engineering (SE) perspective for enhancing defense acquisition success. Evolution is often considered as a major challenge in the SoS area due to its complexity and difficulty resulting from the SoS characteristics including system autonomy, system diversity, complicated interactions, uncertainties, and dynamicity. The change of the command and control structure in the defense community from hierarchy to multidomain illustrates a typical evolution process that is challenging to manage. Over time, new systems can be added, current systems can be replaced or removed, and the interdependency network can switch to a more efficient structure.
Compared to traditional monolithic systems, an SoS appears more dynamic and evolutionary because it is almost impossible to have a complete and fully formed SoS.
Integrated defense system is a typical combat SoS consisting of various kinds of platforms, aircraft, sensors, weapons, and so on. In these problems, multiple heterogeneous, geographically distributed systems interact and collaborate for an overarching purpose while maintaining managerial and operational independence. System-of-Systems (SoS) problems have received increased attention in the aerospace industry in recent years with the advancement of communication and information technologies. The entire framework also sheds light on bridging the DoDAF-based conceptual models and other mathematical optimization methods. The effectiveness of using ADP in supporting evolution to achieve a near-optimal solution that can maximize the SoS capability over time is illustrated by comparing ADP solution to other alternative solutions. Using a surface warfare SoS as an example, this paper demonstrates and explains the procedures of developing DoDAF models, mapping DoDAF models to ADP elements, formulating ADP formulation, and generating evolutionary decisions. The Department of Defense Architecture Framework (DoDAF) models using Systems Modeling Language (SysML) are used as MBSE artifacts to connect with ADP modeling elements through DoDAF metamodels to increase information traceability and reduce unnecessary information loss. The conceptual models provide a common architectural representation to improve communication between various decision makers while the dynamic optimization method suggests evolution planning decisions from the analytical perspective. This paper follows the principle of Model-Based Systems Engineering (MBSE) and develops a holistic framework integrating MBSE conceptual representations and approximate dynamic programming (ADP) to support the SoS evolution.
This requires effective evolution management at the SoS architectural level with adequate support of process, methods, and tools. System of Systems (SoS) is designed to deliver value to participant stakeholders in a dynamic and uncertain environment where new systems are added and current systems are removed continuously and on their own volition.