Using qualitative models for safety analysis of industrial automation systems

Abstract

Nowadays software enables to control more complex processes, but at the same time it is also responsible for the welfare of humans and environment. A failure in a software program can influence the technical process with unforeseeable consequences. Generally the safety of a computer-controlled system depends on a complex interaction between technical process, controller software and human task. Classic methods for safety analysis mostly are specialized to consider one part of the system and the analysis is a brainstorming procedure. In this paper a model-based approach for safety analysis is discussed. All parts of the computer controlled systems are first described with the help of a qualitative modeling. Then the different qualitative models are combined to a unique model of a computer-controlled system. Based on this model a computer supported safety analysis can be realized. The model enables the analysis of the interaction between the system parts even by considering any multiple failure.