Automatic Translator from System Dynamics to Modelica with Application to Socio-Bio-Physical Systems

Abstract

System Dynamics is a modelling paradigm that has been applied to a wide range of systems, from economic to physical and from managerial to ecological. The main strength of the paradigm is its ease of use. A System Dynamics modeller does not need to focus on equations; instead, models are expressed in terms of stocks and flows. Modelica, on the other hand, is an equation-based modelling language capable of multi-domain modelling using equations. It gives the user more freedom but requires more mathematical focus and skills. Therefore, a unification of equation-based modelling and the System Dynamics paradigm is seen as highly beneficial. Advantages include the ability for System Dynamics modellers to use the tools available in the Modelica ecosystem. Furthermore, it allows the integration of System Dynamics models into Modelica models. To achieve this goal, we developed an XMILE-to-Modelica translator that maps System Dynamics models represented in the XMILE standard exchange format to Modelica models. We also applied a Modelica-to-Julia translator to demonstrate the generality of the approach.We translated several models to test the correctness of the translator. In particular, the Earth System Climate Interpretable Model (ESCIMO) was translated from its original version in the Vensim toolkit into the OpenModelica toolkit, and a correct validation was obtained by comparing simulation results between simulators. Our work improves tool interoperability and further demonstrates the feasibility of using Modelica as a unified, standard language to integrate models created using System Dynamics, including large and complex socio-biophysical systems.