A Case Study in Refinement-Based Modelling of a Resilient Control System

In this paper, we present a case study in modelling a resilient control system in Event-B. We demonstrate how to formally define the basic safety properties and fault tolerance mechanisms, as well as the system modes describing the system behaviour under different execution and fault conditions. Our formal development helps us to identify the diagnosability conditions for resilience, i.e., identify the limitations to be imposed on possible component changes to guarantee its controllability and hence dependability.