Modeling of Hydraulic Systems for Hardware-in-the-Loop Simulation: A Methodology Proposal

The present paper proposes a methodology to organize model libraries of electro-hydraulic components. This methodology holds in the association of an object oriented modeling, equation based, language for model structure description, with a graphical formalism suitable for the dynamic behavior description of reactive hybrid systems. That is, a recent general purpose language for physical modeling, called Modelica, is used to develop object-oriented libraries of models for different physical domains; the hierarchical description of the dynamic behavior of each model is obtained by means of the Statecharts formalism. With the method proposed, complex models are built by model interconnection schemes; it is possible to organize the models for different complexity levels adapting them for distinct simulations (real-time or off-line), by refining their behavior using the Statecharts graphical formalism. The developed hydraulic models, once compiled into C-code, are assembled as a whole application, and executed by a digital signal processing card (DSP). The simulation task is based on hardware-in-the-loop techniques in such a way that the “virtual” hydraulic application is controlled by real hardware.