Simulation of Discontinuities in Physical System Models Based on Conservation Principles

Abstract

Bond graphs are a powerful and elegant formalism for modeling the continuous dynamics of physical systems.Hybrid bond graphs augment traditional bond graphs by a variable causality switching element to facilitate models with mixed continuous/discrete, hybrid, behavior. This paper describes an experimental hybrid bond graph simulator, HYBRSIM that handles (i) dynamic reconfiguration of the state vector, and (ii) recomputing state variable values based on conservation principles when additional constraints become active. Simulation applies graph propagation as opposed to explicit equation generation. One discrete state change may cause a number of further instantaneous state changes. HYBRSIM supports the two basic types of event iteration caused by parameter and time scale abstraction.