U-Map: A Reference Map for Safe Handling of Runtime Uncertainties

“Uncertainty is certain” – a well-stablished fact that challenges design and engineering of dynamic systems. Cyber Physical Systems (CPSs) must function and perform tasks safely in real world contexts that might not be engineered specifically for them. These dynamic contexts are often accompanied by the pervasive presence of uncertainty. The dynamic nature of such systems as well as their ever-growing complexity further complicate safety assurance and require a paradigm shift towards more effective runtime safety assurance techniques. Many of the present runtime safety assurance techniques consider certain dynamic aspects of the system and its context, but not the uncertainty aspects completely. This paper presents results from an ongoing research to effectively handle runtime uncertainties in a model-based approach to assure system safety. In this paper, we propose a reference map called Uncertainty Map (U-Map) that can be used during system design to handle runtime uncertainties and apply it to a case study. The U-Map consists of an exhaustive set of possible uncertainties that are mapped to sets of potentially resulting hazards as well as possible runtime mitigation measures. It is intended to facilitate the identification of uncertainty-induced hazards during early design and contribute to the safe handling of runtime uncertainties.