Automatic Synthesis of Static Fault Trees from System Models

Abstract

Fault tree analysis (FTA) is a traditional reliability analysis technique. In practice, the manual development of fault trees could be costly and error-prone, especially in the case of fault tolerant systems due to the inherent complexities such as various dependencies and interactions among components. Some dynamic fault tree gates, such as Functional Dependency (FDEP) and Priority AND (PAND), are proposed to model the functional and sequential dependencies, respectively. Unfortunately, the potential semantic troubles and limitations of these gates have not been well studied before. In this paper, we describe a framework to automatically generate static fault trees from system models specified with SysML. A reliability configuration model (RCM) and a static fault tree model (SFTM) are proposed to embed system configuration information needed for reliability analysis and error mechanism for fault tree generation, respectively. In the SFTM, the static representations of functional and sequential dependencies with standard Boolean AND and OR gates are proposed, which can avoid the problems of the dynamic FDEP and PAND gates and can reduce the cost of analysis based on a combinatorial model. A fault-tolerant parallel processor (FTTP) example is used to demonstrate our approach.