Model-Based Assurance for Justifying Automotive Functional Safety

With the growing complexity of, and reliance on, safety-related electrical/electronic (E/E) systems in the automotive sector, the development of an explicit safety case is highly recommended to provide assurance to the different stakeholders interested in automotive functional safety. The production of a safety case is explicitly mandated by the draft automotive functional safety standard ISO26262. A safety case should consider all organisational and technical factors that may contribute to safety. For example, it should provide assurance for the safe behaviours of a particular system as well as assurance for the process by which this system is developed, operated and maintained. In this paper, we address one component of the overall safety case, namely the assurance of the functional safety concept. In particular, we examine how model-driven development and assessment can provide a basis for the systematic generation of functional safety requirements. We demonstrate how an automotive safety case can be structurally and traceably developed, justifying why and how the defined functional safety requirements can adequately mitigate the risk of the identified hazards to an acceptable level. A case study is also presented throughout this paper, discussing examples and lessons learnt from the development of a safety case for an air suspension system.