Dependencies Within Model-Based Safety Analysis

SUMMARY & CONCLUSIONSMost, if not all, safety-critical systems developed are cyber-physical systems (CPS), defined by the presence of a physical component and connectedness to other systems, with a clear trend towards inclusion of over-the-air update capabilities. From a certification standpoint, every change to the system, even in software, should lead to an evaluation of its safety impact. Model-based system engineering offers the possibility of connecting domain-specific models used in the development of the CPS with relevant safety analysis models. The goal is to automate the evaluation of the impact of changes. Changes, however, can only be propagated if the dependencies of the specific model in which the change is introduced are accurately represented. These are difficult to model, as formal descriptions only exist for a subset of dependencies, and some have been completely neglected in model-based systems engineering. Our work provides an overview of the various shapes that dependencies take within model-based safety analysis. The importance of modeling these dependencies is shown in an illustrative example, in which an FMEA, SysML, and Lifecycle model are investigated.