Step revision in hybrid Co-simulation with FMI

Abstract

This paper presents a master algorithm for co-simulation of hybrid systems using the Functional Mock-up Interface (FMI) standard. Our algorithm introduces step revision to achieve an accurate and precise handling of mixtures of continuous-time and discrete-event signals, particularly in the situation where components are unable to accurately extrapolate their input. Step revision provides an efficient means to respect the error bounds of numerical approximation algorithms that operate inside co-simulated FMUs. We first explain the most fundamental issues associated with hybrid co-simulation and analyze them in the framework of FMI. We demonstrate the necessity for step revision to address some of these issues and formally describe a master algorithm that supports it. Finally, we present experimental results obtained through our reference implementation that is part of our publicly available open-source toolchain called FIDE

FMI Go! A simulation runtime environment with a client server architecture over multiple protocols

“…Focusing on FMI compatible efforts, Ptolemy (Ptolemaeus, 2014) is an object oriented peer-to-peer agent based simulation environment and has now FMI (Broman et al, 2013;Cremona et al, 2016) capabilities with an eye on meeting the requirements for discrete-continuous simulations (Zeigler, Praehofer, and Kim, 2000), and DACCOSIM (Galtier et al, 2015) which is most similar to ours. There are others yet but too numerous to list here.…”

Integrating Tools: Co-simulation in UPPAAL Using FMI-FMU

“…Another known problem in modeling and simulation is that of zero-crossing; namely that it is impossible in a simulation setting to detect the exact time when a certain value crosses a zero threshold. As mentioned in [10] this is also a problem in the context of FMI-FMU models. This is a problem that we are aware of, but that our current solution does not try to address.…”

“…In [10] Cremona et al introduce the concept of step revision, similar to that presented in [6], as a method for ensuring the accuracy of modeling a mix of continuous-time and discrete-event systems in an attempt to address the Zero-crossing problem.…”

Approximated Stability Analysis of Bi-modal Hybrid Co-simulation Scenarios

“…We assume that the simulators do not know the exact moment that the plant crosses the surface. This is a reasonable assumption since employing state event location techniques in co-simulation is technically demanding (e.g., it requires the modification of existing simulation tools), has a performance penalty, and there is no standardized interface to communicating switching surfaces between simulators yet (e.g., see [2,7] for proposals).…”