Discontinuities in a bond graph framework

Abstract

In modeling dynamic systems, depending on the admissible macroscopic time scale to be used it is common to neglect some fast transients and to assume a virtually instantaneous change from one state to another. For instance, for hydraulic check valves or electrical transistors it is often convenient to consider them as switches. On the other hand, there is still an ongoing discussion on how to represent the abstraction of discontinuities most suitably in a bond graph framework. In this paper an approach proposed in (W. Borutzky, J. Broenink and K. C. Wijbrans, “Graphical Description of Physical System Models Containing Discontinuities”, Proc. 1993 European Simulation Multiconference, Lyon, France, 7–9 June 1993, pp. 203–207) is used for developing a model of a particular example of a real-world hydraulic-mechanical system in which check valves of a rectifier bridge and the limitation of spool displacement in a control valve give rise to consider a partly discontinuous description, while the rest of the model is continuous. The system is represented both by means of a small Petri net and a set of three bond graph models each corresponding to a major mode of operation. For validation the model was coded manually in ACSL. Some simulation results are included.