Hybrid Systems Modeling Approach with Petri Nets


The purpose of this paper is to present the achievement of the Hybrid Petri Nets techniques used for modeling and behavioral analysis of a class of hybrid systems. In our sense, a dynamic hybrid system contains at least two distinct subsystems which interact: a continuous subsystem (linear, or not) and a discrete subsystem with a finite number of states. In this context, after a brief introduction to the basic elements of Hybrid Petri Nets modeling, two hybrid systems, consisting of liquid level control of one and two interconnected tanks were analyzed in different specific scenarios. The analysis starts with the synthesis of a Hybrid Petri Net model for each system, followed by their refinement and validation by simulation of their behavioral properties, in order to achieve and implement a command – control structure (the sequential controller) of the process. For the models synthesis and for their validation, Modified Hybrid Petri Nets were used. Such structure is a extinction of the classical topology of a generalized Hybrid Petri Nets model, achieved by assignation to every continuous transition a firing speed as a algebraic relation whose variables depend of different marking of continuous places, arbitrary or not. The synthesis of the models and their validation was obtained using Visual Object Net++ tool. images