Injecting Formal Verification in FMI-Based Co-simulations of Cyber-Physical Systems

Abstract

Model-based design tools supporting the Functional Mockup Interface (FMI) standard, often employ specification languages ideal for modelling specific domain problems without capturing the overall behavior of a Cyber-Physical System (CPS). These tools tend to handle some important CPS characteristics implicitly, such as network communication handshakes. At the same time, formal verification although a powerful approach, is still decoupled to FMI co-simulation processes, as it can easily lead to infeasible explorations due to state space explosion of continuous or discrete representations. In this paper we exploit co-modelling and co-simulation concepts combined with the injection of formal verification results indirectly in a model-based design workflow that will enable verification engineering benefits in a heterogeneous, multidisciplinary design process for CPSs. We demonstrate the approach using a Heating, Ventilation and Air Conditioning (HVAC) case study where communication delays may affect the CPS system's analysis. We model discrete events based on the Vienna Development Method Real-Time dialect, Continuous Time phenomena using Modelica, and communications using PROMELA. Results are considered and inspected both at the level of constituent models and the overall co-simulation.

Features of Integrated Model-Based Co-modelling and Co-simulation Technology

“…CPS SysML profile has been demonstrated in Modelio 11 . FMI-conformant constituent models have been produced in Overture from VDM-RT, and the Continuous-Time (CT) formalisms 20-sim and OpenModelica [23] 12 . A graphical front-end for the entire INTO-CPS tool chain called the INTO-CPS Application has been developed based on the cross-platform Electron technology [14].…”

“…In the INTO-CPS project we start from the view that disciplines such as software, mechatronic and control engineering have evolved notations and theories that are tailored to their needs, and that it is undesirable to suppress this diversity by enforcing uniform general-purpose models [16,31] Our goal is to achieve a practical integration of diverse formalisms at the semantic level, and to realise the benefits in integrated tool chains. In order to demonstrate that the technology works industrially it has been applied in very different application domains (e.g., [17,30,19,12,34,38]).…”

Maestro: The INTO-CPS co-simulation framework

“…The development of Maestro was therefore driven by requirements from industry. To ensure that Maestro successfully satisfied the needs of industry, it was applied by industry partners in different domains such as automotive, railways, maritime, building automation, and agriculture (e.g., [4,5,6,7,8,9]). In order to illustrate the majority of the tool, this paper features a small case study where a Line-Following Robot (LFR) is used, which is representative of the mentioned challenges.…”