Parsing and Validation of Modelica Models Utilising Fault Diagnosis
Models have become an indispensable tool within most industrial
sectors and are used to reduce costs, enhance the performance of a
system etc. The computer support within modelling is extensive,
whereof the programming language Modelica is eminent, especially for
multi-domain models. Dymola, a commercial program, is built on
Modelica and is foremost used for simulation purposes, but many
applications for which models are useful are not supported by
Dymola. Instead other tools, e.g., Matlab, could be used to exploit the
full potential of a model, which means that it first would be needed
to be translated. This master’s thesis examines one of the possible
ways to accomplish this. Specifically the possibility to translate
Modelica-models via an xml file, generated by Dymola, is examined. The
structure and content of this file is explored, and based thereupon a
software is implemented in Python, which successfully translates the
models constituting the base for this thesis. Specifically the method
was developed on a model of a sub-system of Saab 39 Gripen air-plane.
Besides porting models between different languages, it is of great
interest to determine how well a model describes the system on which
it is based. Hence a new method for model validation is developed
using the Matlab Fault Diagnosis Toolbox, which also determines the
Matlab syntax of the Modelica trans- lation. The novelty with the
developed method, compared to traditional model validation methods, is
that it is equation based. It is meant to point out specifically
which equations are poorly fitted to validation data. On a simple
example model the method was successfully used to isolate a poorly
fitted equation. This is accomplished by introducing faults to the
equations and generating residuals, based on sets of over-determined
equations. As a measure of the modelling error the estimation error
of the simulated residuals is used, which are weighted together
depending on the fault properties of the residuals.
Karin Lockowandt
2017
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Senast uppdaterad: 2021-11-10
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