Fault Trees and Reliability Engineering

Fault trees are a prominent model in reliability engineering. They help express the occurence of a top-level failure in terms of faults in the system. We have studied the quantitative analysis of Fault Trees, in particular of an extension of Fault Trees called Dynamic Fault Trees. Dynamic Fault Trees allow for complex and order-dependent combinations of faults to be expressed capturing e.g. different failure rates of unused spare components

Semantics

The semantics of DFTs are rather intricate as they are formed by independently developed elements with local semantics. Often, their interplay yields subtle quircks. [1]. We think that the best way to explain DFT semantics is using Petri nets. The semantic framework we developed supersedes various existing semantics given to fault trees by varying some parameters of the semantics [2]

Analysis

We improved the state-of-the-art in the quantitative analysis of Dynamic Fault Trees using techniques from probabilistic model checking [3]. Earlier, we already showed that a model transformation on these fault trees allows for speed ups of one or more orders of magnitude [4].

Case study

Besides applying the results above to benchmarks from the literature, we used our tools to analyse various dependability metrics for the core EE part of a vehicle guidance system [5].

References

1. Sebastian Junges, Dennis Guck, Joost-Pieter Katoen, and Mariëlle Stoelinga, “Uncovering Dynamic Fault Trees,” in DSN, 2016.
   
2. Sebastian Junges, Joost-Pieter Katoen, Mariëlle Stoelinga, and Matthias Volk, “One Net Fits All - A Unifying Semantics of Dynamic Fault Trees Using GSPNs,” in Petri Nets, 2018.
   
3. Matthias Volk, Sebastian Junges, and Joost-Pieter Katoen, “Fast Dynamic Fault Tree Analysis by Model Checking Techniques,” IEEE Trans. Industrial Informatics, no. 1, 2018.
   
4. Sebastian Junges, Dennis Guck, Joost-Pieter Katoen, Arend Rensink, and Mariëlle Stoelinga, “Fault trees on a diet: automated reduction by graph rewriting,” Formal Asp. Comput., no. 4, 2017.
   
5. Majdi Ghadhab, Sebastian Junges, Joost-Pieter Katoen, Matthias Kuntz, and Matthias Volk, “Safety analysis for vehicle guidance systems with dynamic fault trees,” Rel. Eng. and Sys. Safety, 2019.