INCOSE MBSE Workshop Presentation


Even though it was intended to be a compact language specifically tailored to the needs of the systems engineering discipline, SysML is still criticized as being too complex and too hard to learn for general deployment among systems engineers.   Through teaching and deploying SysML over several years, the author has uncovered several recurring conceptual stumbling blocks that have contributed to this perception, especially among those who are new to system modeling.  Many of these conceptual issues stem from attempting to use too much of the language at once, or by not fully understanding the concepts that the language is intended to codify.  When students take on each of these concepts piecemeal, however, the stumbling blocks can be easily overcome.

This paper will review the motivation behind the development of SysML, and address a few of these stumbling blocks.  It will use example SysML diagrams to illustrate a basic “starter set” of system modeling concepts.  It will then discuss the use of models vs. diagrams and the meaning of diagram frames, definition vs. use of a model element, distinguishing composition from containment, and the modeling of functionality vs. model execution.  It will also discuss reconciling activity models with a functional hierarchy/decomposition, benefits of parametric models, and the need for value types, units and dimensions.  In each case, a simple example will be provided using SysML graphic notation.

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