The following presentation was given as part of the COMPUTE seminar series and is available as video on YouTube.

Speaker: K. J. Åström (Automatic Control, LTH)

Title: Modelling and Simulation - from Physics to Languages and Software

Abstract: The lecture gives a broad overview of modelling and simulation from the perspective of computing and control. Vannevar Bush built the mechanical differential analyser to simulate power systems. Analog computing developed rapidly because of the advances in electronics. It was widely used for simulation both in industry and academia by the 1950s. The initial efforts to exploit digital computing for simulation were based on emulation of analogue computers. The tedious effort to go from physics to a working analogue simulation was simplified significantly by introducing modelling languages. Languages were first developed for specific areas and later extended to broader physical domains. Hilding Elmqvist developed the language Dymola for multi-domain physical modelling in his 1978 PhD dissertation at the Department of Automatic Control at LTH. The key idea was to cut a system into subsystem and use object orientation to structure the subsystems. The behaviour of the subsystems was expressed by physics in its basic form of balance and constitutive equations. Symbolic and numeric computing was used to transform the model to code suitable for optimization and simulation. Toyota’s use of Dymola in the development of Toyota Prius in 1996 was a major industrial breakthrough. The formation of Modelica Association (Modelica.org), a nonprofit organization for open standards and software for physical modelling, was a major advance. Modelica is now widely used in automotive, aerospace and other industries. Funding for Modelica projects in the period 2007-2022 is more than 100 M€. There are regular Modelica Conferences since 1996. In 2020 there are conferences both in Japan and the USA. There are regular design meetings since 1996, the 100th meeting was held in Lund in 1919. There are three companies in Lund devoted to Modelica, Dassault Systèmes (formerly Dynasim), Modelon and Mogram.