Conceptual Modelling of Hybrid Systems

Complex systems comprising hardware, software, facilities and personnel are gaining more and more importance. Such systems are hybrid, as some components are characterised by continuous behaviour, whereas the behaviour of others is discrete. In this paper we present a concise conceptual model that is capable to capture structure and behaviour of such systems. We show that structural modelling can be based on well-known concepts of the entity-relationship model requiring only some extensions to constraints. We further show that behavioural modelling requires only a careful separation of synchronous and asynchronous interaction and high-level means for the integration of continuous functions. We show that all these concepts can be captured by defining a semantics in hybrid Event-B. The paper illustrates the modelling method by a sophisticated industrial example of a hemodialysis machine.