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].

1998-11-13