Hybrid Cosimulation: It's About Time
David Broman, Fabio Cremona, Marten Lohstroh, Edward A. Lee, Michael Masin, Stavros Tripakis

Citation
David Broman, Fabio Cremona, Marten Lohstroh, Edward A. Lee, Michael Masin, Stavros Tripakis. "Hybrid Cosimulation: It's About Time". Software and Systems Modeling, November 2017.

Abstract
Model-based design methodologies are commonly used in industry when developing complex cyber-physical systems. There exist many different languages, tools, and formalisms for model-based design, each with its strengths and weaknesses. Instead of accepting some weaknesses of a particular tool, an alternative is to embrace the heterogeneity, and to develop tool integration platforms and proto-cols that utilize the strengths from different environments. A fairly recent attempt in this direction is the Functional Mock-up Interface (FMI) standard that includes support for co-simulation. Although this standard has reached acceptance within the industry, it provides only limited support for simulating systems that mix continuous and discrete behavior. In particular, the way the standard requires that time be represented using floating-point numbers makes it impossible to compose components together that are based on both discrete-events and continuous dynamics. In this article, we analyze different alternatives for representing time in hybrid co-simulation. Specifically, we discuss how superdense time can be represented by using integers, and how the choice of time resolution can be agreed upon between the master algorithm and components within a model. We propose a concrete extension to the FMI standard for supporting hybrid co-simulation that includes integer time, automatic choice of time resolution, and the use of absent signals. In particular, we explain how such extension can be designed and implemented using a so called wrapper approach that makes it possible to add the capabilities of hybrid co-simulation to existing simulation environments.

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Citation formats

• HTML

  David Broman, Fabio Cremona, Marten Lohstroh, Edward A. Lee,
  Michael Masin, Stavros Tripakis. <a
  href="http://www.terraswarm.org/pubs/744.html"
  >Hybrid Cosimulation: It's About Time</a>,
  <i>Software and Systems Modeling</i>, November
  2017.

• Plain text

  David Broman, Fabio Cremona, Marten Lohstroh, Edward A. Lee,
  Michael Masin, Stavros Tripakis. "Hybrid Cosimulation:
  It's About Time". <i>Software and Systems
  Modeling</i>, November 2017.

• BibTeX

  @article{BromanCremonaLohstrohLeeMasinTripakis17_HybridCosimulationItsAboutTime,
      author = {David Broman and Fabio Cremona and Marten Lohstroh
                and Edward A. Lee and Michael Masin and Stavros
                Tripakis},
      title = {Hybrid Cosimulation: It's About Time},
      journal = {Software and Systems Modeling},
      month = {November},
      year = {2017},
      abstract = {Model-based design methodologies are commonly used
                in industry when developing complex cyber-physical
                systems. There exist many different languages,
                tools, and formalisms for model-based design, each
                with its strengths and weaknesses. Instead of
                accepting some weaknesses of a particular tool, an
                alternative is to embrace the heterogeneity, and
                to develop tool integration platforms and
                proto-cols that utilize the strengths from
                different environments. A fairly recent attempt in
                this direction is the Functional Mock-up Interface
                (FMI) standard that includes support for
                co-simulation. Although this standard has reached
                acceptance within the industry, it provides only
                limited support for simulating systems that mix
                continuous and discrete behavior. In particular,
                the way the standard requires that time be
                represented using floating-point numbers makes it
                impossible to compose components together that are
                based on both discrete-events and continuous
                dynamics. In this article, we analyze different
                alternatives for representing time in hybrid
                co-simulation. Specifically, we discuss how
                superdense time can be represented by using
                integers, and how the choice of time resolution
                can be agreed upon between the master algorithm
                and components within a model. We propose a
                concrete extension to the FMI standard for
                supporting hybrid co-simulation that includes
                integer time, automatic choice of time resolution,
                and the use of absent signals. In particular, we
                explain how such extension can be designed and
                implemented using a so called wrapper approach
                that makes it possible to add the capabilities of
                hybrid co-simulation to existing simulation
                environments.},
      URL = {http://terraswarm.org/pubs/744.html}
  }
  

Posted by Elizabeth Coyne on 29 Feb 2016.
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