14. Semi-formal Modeling of Multi-technological Systems II: SysML Beyond the Requirements Diagram

The chapter introduces semi-formal graphical system modeling language (SysML) diagrams sufficient for modeling and tracing safety requirements. It builds on the previous chapter on the modeling and tracing of safety requirements using the unified modeling language (UML). The introduced minimum set of SysML diagrams and graphical diagram elements are sufficient to document system knowledge, to analyze system safety, and for requirements modeling and tracing. Being a multi-domain semi-formal language for systems and requirements specification, systems engineering and requirements tracing, it is argued that SysML is less abstract than UML while containing further diagrams that are well suited for efficient engineering graphical requirements modeling, in particular, the SysML requirements diagram (req). It is used together with the SysML block definition diagram (bdd), the SysML internal block diagram (ibd), the SysML activity diagram (act), the SysML use case diagram (uc), the SysML state machine diagram (stm), and the SysML sequence diagram (sd). For each diagram, typical applications and examples including figures are given how to use it for modeling safety requirements. The diagram types, bdd, ibd, stm, and act, are already sufficient for modeling most types of technical safety requirements when using a state machine approach that considers the structure and behavior of the socio-technical system. It is shown how this can be contextualized with the diagram types, uc and sd, to cover system application cases. The chapter provides examples mainly in the domain of embedded systems.