Safety patterns – The key to formal specification of safety requirements

Abstract

The use of formal methods increases the trust in the safe operation of software in industrial automation systems. But the use of formal methods in practical software development is rare. One of the reasons lies in the difficulties arising from formal specification of safety requirements by common software engineers who are not experts in logic. In this paper an approach is presented, in which the difficulties are overcame by the use of formal specification patterns. The main advantage in comparison to other approaches is that the specification patterns transfer expert knowledge. Therefore this approach not only helps in using formal methods, it also supports in learning the practical application of formal specification languages for safety requirements specification. The patterns are called ”safety patterns” because they are developed for the formal specification of requirements special in context of safety.