Modelica—A language for equation-based physical modeling and high performance simulation
- Peter Fritzson
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A new language called Modelica for hierarchical physical modeling is developed through an international effort. Modelica 1.0 [http:// www.Dynasim.se/Modelica] was announced in September 1997. It is an object-oriented language for modeling of physical systems for the purpose of efficient simulation. The language unifies and generalizes previous object-oriented modeling languages and techniques.
Compared to the widespread simulation languages available today this language offers two important advances: 1) non-causal modeling based on differential and algebraic equations; 2) multidomain modeling capability, i.e. it is possible to combine electrical, mechanical, thermodynamic, hydraulic etc. model components within the same application model.
A class in Modelica may contain variables (i.e. instances of other classes), equations and local class definitions. The multi-domain capability is partly based on a notion of connectors, which are classes just like any other entity in Modelica.
Simulation models can be developed using a graphical editor for connection diagrams. Connections are established just by drawing lines between objects picked from a class library. The Modelica model is translated into a set of constants, variables and equations. Equations are sorted and converted to assignment statements when possible. Strongly connected sets of equations are solved by calling a symbolic and/or numeric solver. The C/C++ code generated from Modelica models is quite efficient.
High performance parallel simulation code can be obtained either at the coarse-grained level by identifying fairly independent submodels which are simulated in parallel, or at the fine-grained level by parallelizing on clustered expression nodes in the equation graph. Preliminary results using the coarse-grained approach have been obtained in an application on simulating an autonomous aircraft watching car traffic.
- Mats Andersson: Object-Oriented Modeling and Simulation of Hybrid Systems. Ph.D. thesis ISRN LUTFD2/TFRT-1043-SE, Department of Automatic Control, Lund Institute of Technology, Lund, Sweden, December 1994.
- Hilding Elmqvist, Dag Brück, and Martin Otter: Dymola—User’s Manual. Dynasim AB, Research Park Ideon, Lund, Sweden, 1996, http://www.Dynasim.se
- Hilding Elmqvist, Sven-Erik Mattsson: Modelica— The Next Generation Modeling Language—An International Design Effort. In Proceedings of First World Congress of System Simulation, Singapore, September 1–3 1997.
- Peter Fritzson, Lars Viklund, Dag Fritzson, Johan Herber. High-Level Mathematical Modelling and Programming, IEEE Software, 12(4):77–87, July 1995, http://www.ida.liu.se/labs/pelab/omath CrossRef
- Peter Fritzson, Vadim Engelson. Modelica—A Unified Object-Oriented Language for System Modeling and Simulation, In Proceedings of ECOOP-98, Brussels, July 1998, LNCS 1445, Springer Verlag.
- Dag Fritzson, Patrik Nordling. Solving Ordinary Differential Equations on Parallel Computers Applied to Dynamic Rolling Bearing Simulation. In Parallel Programming and Applications, P. Fritzson, L. Finmo, eds., IOS Press, 1995
- A.C. Hindmarsh. ODEPACK, A Systematized Collection of ODE Solvers, Scientific Computing, R. S. Stepleman et al. (eds.), North-Holland, Amsterdam, 1983 (Vol. 1 of IMACS Transactions on Scientific Computation), pp. 55–64, also http://www.netlib.org/odepack/index.html
- Modelica Home Page. http://www.Dynasim.se/Modelica
- ObjectMath Home Page. http://www.ida.liu.se/labs/pelab/omath
- Martin Otter, C. Schlegel, and Hilding Elmqvist. Modeling and Real-time Simulation of an Automatic Gearbox using Modelica. In Proceedings of ESS’97— European Simulation Symposium, Passau, Oct. 19–23, 1997.
- Clemens Szyperski. Component Software—Beyond Object-Oriented Programming. Addison-Wesley, 1997.
- Modelica—A language for equation-based physical modeling and high performance simulation
- Book Title
- Applied Parallel Computing Large Scale Scientific and Industrial Problems
- Book Subtitle
- 4th International Workshop, PARA’98 Umeå, Sweden, June 14–17, 1998 Proceedings
- pp 149-160
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- Lecture Notes in Computer Science
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- Springer Berlin Heidelberg
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