Structure and use of a library for physical systems models

The availability of reusable and sharable models of physical systems will be a major advance in Computer Aided Engineering. Therefore, a generic framework for storing and retrieving public and private model data is needed. Our thesis is that such a framework must be based on a differentiation between three different levels of abstraction, which we define as engineering components, conceptual descriptions in terms of physical processes, and mathematical relations. Our approach is centered around the bond graph language, which provides the conceptual link between components and mathematical relations, a.o., in the field of mechatronics. When constructing a model, a system is decomposed down to an appropriate level of granularity. Each component is associated with one of a number of alternative conceptual descriptions (bond graphs), one of which is to be selected. Concepts (i.e. bond graph elements) in turn are further specified by selection from a number of alternative mathematical relationships. Moreover, previously assembled models based on the generic building blocks can also be stored in the library. In this way, models with different levels of detail and validation status can be assembled. In this paper we describe how this framework supports the modeling process. An example session shows the route a modeler might follow to assemble the model of his/her needs.