Conference article

Enforcing Reliability of Discrete-Time Models in Modelica

Sébastien Furic
LMS Imagine, France

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Published in: Proceedings of the 8th International Modelica Conference; March 20th-22nd; Technical Univeristy; Dresden; Germany

Linköping Electronic Conference Proceedings 63:71, p. 638-649

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Published: 2011-06-30

ISBN: 978-91-7393-096-3

ISSN: 1650-3686 (print), 1650-3740 (online)


Modelica models involving discrete-time aspects may lead to surprising results due to the way events are currently handled in the language. Indeed; simultaneity is interpreted as synchronism and; as a consequence; two unrelated sources of events may interfere in unexpected ways.

In this paper; we present minimal examples of models that exhibit unexpected or surprising results; then we explain the general causes of such behaviors and propose to introduce the notion of clock in the language to solve the issues. In contrast to [1] and [2]; we focus here on models resulting from the composition of other models: we aim at showing that the current discrete-time theoretical model of Modelica is not robust with respect to model composition. For the final user; it means that it is generally not possible to build reliable models involving discrete-time aspects by simply connecting generic library models: manual adjustments are often required to obtain the expected behavior.


Discrete-time modeling; clock calculus


[1] R. Nikoukhah; Activation Inheritance in Modelica; EOOLT; 2008

[2] R. Nikoukhah; S. Furic; Synchronous and Asynchronous Events in Modelica: Proposal for an Improved Hybrid Model; 6th international Modelica conference; 2008

[3] A. Benveniste; P. Le Guernic; and C. Jacquemot; Programming with events and relations: the Signal language and its semantics; 1991

[4] S. Bliudze.; D. Krob; Modelling of Complex Systems: Systems as dataflow machines; 2009

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