Extracting models from ISO 26262 for reusable safety assurance

As more and more complex software is deployed in safety-critical embedded systems, the challenge of assessing the safety of those systems according to the relevant standards is becoming greater. Due to the extensive manual work required, validating compliance of these systems with safety standards is an expensive and time-consuming activity; furthermore, as products evolve, re-assessment may become necessary. Therefore, obtaining reusable assurance data for safety assessment or re-assessment is very desirable. In this paper, we propose a model-based approach for assuring compliance with safety standards to facilitate reuse in the assessment, qualification and certification processes, using the automotive safety standard ISO 26262 as a specific example. Three different modeling techniques are described: A structure model is introduced to describe the overall structure of the standard; a rule-based technique is used for extracting the conceptual model from it; and a mapping to the software and systems process engineering metamodel provides a description of its processes. Finally, validation in the context of a concrete use case in the FP7 project OPENCOSS shows that the resulting models of our approach resemble the industrial models, but that they, inevitably, require the fine-tuning of domain experts.