Properties modelling as design by contract for cyber-physical systems: an example in the smart grid domain

The development of a cyber-physical system (CPS) is strongly related to the requirements elicitation and their fulfilment. Requirements represent the agreement, among the actors involved in the development process of a system (e.g., stakeholders, engineers), of what it is expected to be delivered. As they are neither computable nor verifiable, because typically expressed textually, their misunderstanding could lead to delay or even the failure of the overall system development. In this context, the exploitation of the properties modelling (PM) approach combined with the simulation is proposed to enable assessable requirements. In particular, PM is adopted for expressing requirements as computable and verifiable components, whereas simulation techniques are exploited for supporting their automatic verification and to evaluate their level of fulfilment. The simulation model along with the results gathered from the properties' evaluation represent the contract (design-by-contract) on which the actors can agree before the realisation of an actual CPS. The proposal is tested in the smart grid domain.