Bond Graph Modelling of Physical Systems

Smith, Lorcan Stuart Peter Stillwell (1993) Bond Graph Modelling of Physical Systems. PhD thesis, University of Glasgow.

Abstract

This thesis describes new methods for creating and analysing bond graph models of continuous physical systems. The concept of a core model representation is central to this research, since it is shown that the need to generate and maintain a range of models discourages the widespread use of modelling. Mathematical models appropriate to specific applications are not, in general, sufficiently comprehensive to be used as the core model representation, whereas all the models of interest for analysis and simulation may be derived from a bond graph model. Hierarchical model representations are shown to be an aid to reducing complexity, and thus the bond graph methodologies, which are developed, fully support hierarchical models. A new bond graph algorithm for identifying and solving algebraic loops is described, and extended to provide a steady-state model of the system. The new algorithm is shown to systematically create a differential algebraic equation (DAE) model of the system. Bond graph causality is shown to be a powerful analytical concept, but classical causal propagation algorithms have limitations which are discussed. These limitations are overcome by a novel computable causality approach, and its bicausal bond graph representation. The computable causality algorithm is used for resolving algebraic loops, and handling of modulations. The new concepts of unilateral bonds and bicausal bond graphs generalise the classical causality notation to permit physically unrealisable (but computationally useful) bond graph causalities. The computable causality algorithm provides a systematic method for deriving generalised state equation (or DAE) mathematical models from bicausal bond graphs. Practical applications of the new bond graph techniques are demonstrated through the analysis of four real physical systems as case studies. The implementation and operation of a DOS-based tool which uses bond graphs as the core model representation is described.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Additional Information: Adviser: P J Gawthrop
• Keywords: Computer engineering
• Date of Award: 1993
• Depositing User: Enlighten Team
• Unique ID: glathesis:1993-74811
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 27 Sep 2019 16:03
• Last Modified: 27 Sep 2019 16:03
• URI: https://theses.gla.ac.uk/id/eprint/74811