Dynamic Fault Tree Generation for Safety-Critical Systems Within a Systems Engineering Approach

Abstract

Systems are getting increasingly complex and challenging to design. For safety-critical systems, the integration between model-based systems engineering and model-based safety assessment to improve the choice of the system architecture since the early design stage becomes a necessity. One of the integration solutions is to generate fault trees (FTs), either static or dynamic, directly from the system description. In this paper, we are particularly interested in the generation of the dynamic fault trees (DFTs) of the systems that contain redundancies, which is widely used in safety-critical systems to enhance their reliability. The goal of this paper is, first, to propose a redundancy profile and, second, to automatically generate the DFTs from system models. Since errors are propagated via input and output ports of the components, the generation process starts with a depth-first search graph traversal through the systems modeling language internal block diagram of the system. This diagram is considered as a multidirected graph in order to detect the external inputs, the nonredundant components, the switch components, and the redundant components of the system. Then, the redundancy information incorporated in the system model is used to generate the appropriate combinations of the FT. This FT is represented in a suitable format that can be studied using FT analysis tools, for both qualitative and quantitative safety analyses.