Modeling Petri nets as local constraint equations for hybrid systems using Modelica™

To model complex mixed continuous/discrete, hybrid, systems, the continuous part can be described by differential and algebraic equations using an object-oriented modeling language such as Modelica. It is shown how a discrete formalism such as Petri nets can be incorporated by describing all components by strictly local equations. This allows a unifying treatment since both the continuous and the discrete part of a system are described by equations. The resulting Petri net library is applied to model the redundancy management control of the elevator subsystem of an aircraft.