Model-based development of a safety concept

The safety concept of a safety-critical system is the specification of the safety requirements necessary to achieve the safety goals. The state-of-the-art development of the safety concept is an iterative process between an analytic and a constructive engineering task. In the analytic part, engineers evaluate the relation between internal failures and the violation of the safety goals. In the constructive part, the engineers select safety measures in order to prevent internal failures from violating the safety goals. In this article, we present an approach for the model-based development of a functional safety concept. The approach is based on a common model for functional and for safety aspects. The functional components in the model comprise a so-called Failure View for modeling the relation between failures and a so-called Safety Concept View for modeling the refinement relation between safety requirements. The general idea of the approach is to derive the safety requirements and their relation from the failures and their relations. We show how the general idea is implemented in order to deal with the complex selection of safety measures and the systematic derivation of safety requirements.