RAATSS, an extensible Matlab® toolbox for the evaluation of repairable dynamic fault trees

In recent years, a new generation of dynamic modeling tools for reliability evaluation of complex systems has been developed. At first, state-space methodologies were successfully used to model systems characterized by interdependencies that cannot be handled by traditional combinatorial techniques. Afterwards, more descriptive methodologies (like DFT, DRBD, BDMP, etc.) have been proposed in order to enrich the intuitiveness of combinatorial methods with the capabilities to model dynamic dependencies. However, despite the promises of researchers and the efforts of end-users, the diffusion of such procedures into the industrial world has not been impressive: risk assessment procedures were not as straight as earlier and, what is worse, it has become difficult to understand the effects of such dynamism. In this paper, we focus on the Dynamic Fault Tree (DFT) methodology and present a tool based on a novel formalism, the Adaptive Transitions System (ATS). Starting from the state of the art, a set of standardized rules are drawn in order to frame the behaviors of the dynamic gates of DFT with repairable components. These rules were used as specification to design a basic library for the resolution of extended, repairable DFT. The designed tool may result of great interest because it is written in Matlab® code and can be easily extended. Moreover, this work introduces some novel concept addressed to the DFT modeling and provide a basic hint of the ATS capabilities to describe complex system interdependencies.