TECHNICAL ARTICLE Bond Graphs: The Right Choice for Educating Students in Modeling Continuous-Time Physical Systems

This paper describes a modeling technique that, better than alternative approaches, teaches the student to develop from the start valid models of physical continuous-time processes. Several examples of state-space models are presented that look very plausible, give seemingly plausible results, and yet are physically wrong. These examples may serve to illustrate the potential dangers behind state-space descriptions used as a modeling tool. It is our conviction that model validation should be integrated with model building, and should not be an afterthought. The bond graph modeling technique enables us to describe physical systems in terms that are much closer to physical reality than state-space modeling. Thereby many of the standard pitfalls in making models are avoided right from the beginning. Bad (i.e., non-physical) models have no chance of being created in the first place