Citation
David Broman, Christopher Brooks, Lev Greenberg, Edward A. Lee, Michael Masin, Stavros Tripakis, Michael Wetter. "Determinate Composition of FMUs for Co-Simulation". 13th International Conference on Embedded Software (EMSOFT), Montreal, 29, September, 2013.

Abstract
In this paper, we explain how to achieve deterministic execution of FMUs (Functional Mockup Units) under the FMI (Functional Mockup Interface) standard. In particular, we focus on co-simulation, where an FMU either contains its own internal simulation algorithm or serves as a gateway to a simulation tool. We give conditions on the design of FMUs and master algorithms (which orchestrate the execution of FMUs) to achieve deterministic co-simulation. We show that with the current version of the standard, these conditions demand capabilities from FMUs that are optional in the standard and rarely provided by an FMU in practice. When FMUs lacking these required capabilities are used to compose a model, many basic modeling capabilities become unachievable, including simple discrete-event simulation and variable-step-size numerical integration algorithms. We propose a small extension to the standard and a policy for designing FMUs that enables deterministic execution for a much broader class of models. The extension enables a master algorithm to query an FMU for the time of events that are expected in the future. We show that a model can be executed deterministically if all FMUs in the model are either memoryless or implement one of rollback or step-size prediction. We show further that such a model can contain at most one "legacy" FMU that is not memoryless and provides neither rollback nor step-size prediction.

Electronic downloads

• http://www.eecs.berkeley.edu/Pubs/TechRpts/2013/EECS-2013-153.html. (Prepublication Technical Report Version.)
• http://dl.acm.org/citation.cfm?id=2555756. (Published in Proceedings of the Eleventh ACM International Conference on Embedded Software (EMSOFT13).)

• HTML

  David Broman, Christopher Brooks, Lev Greenberg, Edward A.
  Lee, Michael Masin, Stavros Tripakis, Michael Wetter. <a
  href="http://chess.eecs.berkeley.edu/pubs/1002.html"
  >Determinate Composition of FMUs for
  Co-Simulation</a>, 13th International Conference on
  Embedded Software (EMSOFT), Montreal, 29, September, 2013.

• Plain text

  David Broman, Christopher Brooks, Lev Greenberg, Edward A.
  Lee, Michael Masin, Stavros Tripakis, Michael Wetter.
  "Determinate Composition of FMUs for
  Co-Simulation". 13th International Conference on
  Embedded Software (EMSOFT), Montreal, 29, September, 2013.

• BibTeX

  @inproceedings{BromanBrooksGreenbergLeeMasinTripakisWetter13_DeterminateCompositionOfFMUsForCoSimulation,
      author = {David Broman and Christopher Brooks and Lev
                Greenberg and Edward A. Lee and Michael Masin and
                Stavros Tripakis and Michael Wetter},
      title = {Determinate Composition of FMUs for Co-Simulation},
      booktitle = {13th International Conference on Embedded Software
                (EMSOFT), Montreal},
      day = {29},
      month = {September},
      year = {2013},
      abstract = {In this paper, we explain how to achieve
                deterministic execution of FMUs (Functional Mockup
                Units) under the FMI (Functional Mockup Interface)
                standard. In particular, we focus on
                co-simulation, where an FMU either contains its
                own internal simulation algorithm or serves as a
                gateway to a simulation tool. We give conditions
                on the design of FMUs and master algorithms (which
                orchestrate the execution of FMUs) to achieve
                deterministic co-simulation. We show that with the
                current version of the standard, these conditions
                demand capabilities from FMUs that are optional in
                the standard and rarely provided by an FMU in
                practice. When FMUs lacking these required
                capabilities are used to compose a model, many
                basic modeling capabilities become unachievable,
                including simple discrete-event simulation and
                variable-step-size numerical integration
                algorithms. We propose a small extension to the
                standard and a policy for designing FMUs that
                enables deterministic execution for a much broader
                class of models. The extension enables a master
                algorithm to query an FMU for the time of events
                that are expected in the future. We show that a
                model can be executed deterministically if all
                FMUs in the model are either memoryless or
                implement one of rollback or step-size prediction.
                We show further that such a model can contain at
                most one "legacy" FMU that is not memoryless and
                provides neither rollback nor step-size
                prediction. },
      URL = {http://chess.eecs.berkeley.edu/pubs/1002.html}
  }
  

Posted by David Broman on 12 Aug 2013.
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