Model-Based Structured Requirements in SysML

Architecture-centric practices are gaining wide-spread acceptance in systems engineering. This process involves capturing the structure, behavior, and rules and their relationships to create an abstract representation of a system, often termed a model of the system. Central to the rules that govern a system are the requirements that are placed on it, often by various stakeholders. These requirements help guide the system development process of a complex entity. In this paper, we discuss an approach for extending the idea of structured requirements (requirements defined through an orderly structure with specific pieces of content that must be filled in) to SysML through customized stereotypes that help enforce the requirement structure through model-based attributes. This approach helps move requirements modeling and management further into the model-based paradigm from the classical textual definitions. In addition, requirements often are customized by the organization defining them through additional attributes. These additional attributes are added to the model-based structured requirement (MBSR) to create a well-defined organizational requirement stereotype. Several examples of the MBSRs are presented using a notional thrust reverser actuation system (TRAS). Several points are made on how this approach can help support more rigorous requirements modeling, analysis, management, and communication throughout the system development process. Future work will involve automatic generation of the textual requirement statements from the attributes, customized validation rules, and customized classifiers for the various attributes.