Generation of functional mockup units for transactional cyber-physical virtual platforms

Abstract

Modeling Cyber-Physical Systems requires aggregating semantics and languages tailored to different specific domains, while simulating these systems requires integrating different tools and technologies. Academy and Industry are working to define standard interfaces allowing to facilitate such integration. The Functional Mockup Interface (FMI) standard is one of the most promising tools produced by this effort. It allows to easily export and integrate heterogeneous models. However, the standard still shows some weaknesses. In particular, it still does not provide a proper support for describing discrete-event systems. In this chapter we analyze the current standard and its recently proposed extensions. In particular, we focus on its shortcomings when dealing with discrete models. Then, we present a systematic approach exploiting the features of the current standards to mitigate such limitations. The approach is based on two concepts: (1) exposing the internal time of each component and (2) exploiting the newly exposed information to implement temporal decoupling. The combination of these two concepts allows to optimize the coordination algorithms by reducing the number of synchronization points, thus moving the simulation from cycle- to transaction-accurate. The impact of these optimizations is measured on a set of benchmarks having different tread-offs of computation and control. Finally, we analyze some possible improvements that may be integrated in the future updates of the standard.