The Language of Interaction

This article discusses various features and applications of bond graphs in mechanical electrical industry. A ‘bond’ represents the energy exchange among subsystems. The product of two variables, effort and flow, represents this power. With bond graphs, all subsystems can be represented with a mere nine elements. The physics of some elements require that the list expands to include multiport versions of energy dissipation, storage, and transfer. When subsystems composed of sensors and actuators are connected, an overall system model evolves. This overall model represents the dynamics of the entire system. With bond graphs, causality is indicated by a perpendicular stroke at the end of a bond. Thus, assigning causality is a straightforward task. Bond graphs dealt with mixed energy domain systems as well. Analogies among various systems, such as equivalent electrical circuits for mechanical vibratory systems, were never complete because each field had unique features. Bond graphs use analogous power and energy variables in all energy domains, but allow the distinctive features of the separate fields to be represented.