A Cognitive Technology Approach to the Verification of Safety Critical Control Software

Abstract A large part of real time and computer control applications are safety related. Hence, the software involved must be rigorously verified, i.e., safety licensed, which is extremely critical, since it is far from being as dependable as hardware. This task, however, is very difficult and not satisfactorily solved, yet. In this paper, the intrinsic problems and fundamental principles of safety licensing software are worked out. The importance of the human element in this process is emphasised. Striving for simplicity, the use of two software development paradigms especially suitable for safety critical control systems and trustworthy verification, viz., cause effect tables and function block diagrams, is advocated for. The presented approaches deviate from classical techniques by enforcing the re-use of pre-engineered and a priori verified off-the-shelf application oriented standard software function modules, and by employing diagrammatic and graphical programming paradigms. The methods effectively cope with complexity by simplification, and meet the need of society for safe and dependable computerised automation systems.