Discontinuities handled with events in Assimulo

Summary, in English

Often integrating ordinary differential equations or differential algebraic equations (DAE) do not constitute the problem alone. A common complement is finding the root of an algebraic function (an event function) that depends on the states of the problem. This formulation of a model enables the possibility of including discontinuities, an important part of the Functional Mock-up Interface standard which allows hybrid models of differential algebraic equations. The problem of root-finding during integration is however difficult. Both in a theoretical aspect and as a software problem.



An implementation of software for root-finding is done in Assimulo, a Python/Cython wrapper for integrators. The implementation takes the Functional Mock-up Interface standard into consideration. The implementation is made usable for a wide variety of integration algorithms and is also verified and benchmarked with advanced industrial models, showing good indications of being robust and scaling well for large systems.

• Author: Emil Fredriksson; Christian Andersson; Johan Åkesson
• Editor: Hubertus Tummescheit; Karl-Erik Årzén
• Department/s: Mathematics (Faculty of Engineering); Department of Automatic Control
• Publishing year: 2014
• Language: English
• Pages: 827-836
• Publication/Series: Linköping Electronic Conference Proceedings
• Issue: 96
• Full text: - 524 kB; Download statistics
• Links: http://www.ep.liu.se/ecp/096/086/ecp14096086.pdf; http://dx.doi.org/10.3384/ECP14096827
• Document type: Conference paper
• Publisher: Linköping University Electronic Press
• Topic: Mathematics; Control Engineering
• Keywords: Assimulo; FMI; Functional Mock-up Interface; FMU; Discontinuities; Events; Root-finding
• Conference name: 10th International Modelica Conference
• Conference date: 2014-03-10 - 2014-03-12
• Conference place: Lund, Sweden
• Status: Published
• Research group: LCCC
• ISBN/ISSN/Other: ISSN: 1650-3686; ISSN: 1650-3740