Analysis and synthesis of the behaviour of complex programmable electronic systems in conditions of failure

This paper introduces a new method for safety analysis which modifies, automates and integrates a number of classical safety analysis techniques to address some of the problems currently encountered in complex safety assessments. The method enables the analysis of a complex programmable electronic system from the functional level through to low levels of its hardware and software implementation. In the course of the assessment, the method integrates design and safety analysis and harmonises hardware safety analysis with the hazard analysis of software architectures. It also introduces an algorithm for the synthesis of fault trees, which mechanises and simplifies a large and traditionally problematic part of the assessment, the development of fault trees. In this paper, we present the method and discuss its application on a prototypical distributed brake-by-wire system for cars. We argue that the method can help us rationalise and simplify an inherently creative and difficult task and therefore gain a consistent and meaningful picture of how a complex programmable system behaves in conditions of failure.