Developing Safe Control Systems using Patterns for Assurance

Abstract—The Safe Control Systems (SaCS) method is a pattern-based method supporting the development of concep-tual designs for safety critical systems. A pattern language offers support for the method by six different kinds of basic patterns, operators for combining patterns, and a graphical notation for visualising a pattern composition. Intended users of SaCS are system developers, safety engineers and HW/SW engineers. The method has so far been applied in two cases within different industrial domains. This paper demonstrates and presents experiences from the application of SaCS within the railway domain. We consider an interlocking system that controls the appliances of a railway station. We argue that SaCS effectively supports the establishment of requirements, a design satisfying the requirements, and an outline of a safety demonstration for the design. Keywords-conceptual design; pattern language; development processes; safety; I