This paper documents the implementation of a hybrid bond graph [Mosterman1997,Mosterman & Biswas1998] modeling and simulation environment, HYBRSIM, implemented in Java. Continuous simulation is based on graph propagation in a bond graph model which allows for a flexible treatment of models that undergo configuration changes. The discrete event part is implemented as local finite state machines.
Compared to other physical system simulation tools, HYBRSIM handles complex hybrid phenomena. For example, it supports variable causality models to allows run-time state vector reconfiguration and inherently enforces conservation laws to compute new state vector values. Additionally, HYBRSIM supports two types of event iteration based on time scale and parameter abstraction by specifying switching variables in terms of a priori and a posteriori values. Presently, event iteration because of parameter abstraction is not supported by other physical system simulation tools. In future, the simulation environment may be extended to include other transition functions such as chattering [Mosterman, Zhao, & Biswas1998].