Research On Modeling And Simulation Method Of Hybrid System Based On Petri Nets

Hybrid dynamic system is a kind of system which has the characteristics of discrete and continuous dynamic behavior that interacts with each other. Research on the hybrid system is no longer restricted to a particular subject area. Researchers from control science, computer science, mathematics and even the system biology community with different background have met the same special challenges brought by hybrid systems. Among the variety research areas, modeling and simulation of hybrid system have always occupied a key position. Petri nets have been applied to many different fields, with its simple and compact graphical representation, strong expression ability, and solid mathematical foundation. As an extension of the standard Petri nets, the hybrid Petri nets inherit the strengths of Petri nets, and it has become an important research method of hybrid system.Firstly, the structure characteristics and definition of the hybrid system are pointed out. Different modeling methods for hybrid systems are summarized, what’s more, the advantages and disadvantages of different modeling methods are compared, the conditions of mutual transformation is presented as well. Special phenomenon caused by the hybrid system as well as the key problem in the simulation of hybrid system that deserves special attention is revealed by an example.Secondly, a hybrid Petri nets modeling and simulation method is used to study a class of hybrid system. On the base of the standard Petri nets, this paper introduces the definition, enabling and firing conditions of the hybrid Petri nets, points out that conflicts between different transitions are critical problem that to be dealt with. At the same time, a conflict resolution method has been proposed. Based on the basic evolution rules of hybrid Petri nets, a simulation algorithm of hybrid Petri nets is designed. On the base of the hybrid Petri nets simulation algorithm and MATLAB GUI simulation engine, a hybrid Petri nets simulation tool is designed. This simulation tool support different kinds of arc types, as well as endows the transitions more abundant characteristics. Furthermore, it has expanded the expression ability of the hybrid Petri nets, thus has a certain practicality.Finally, the application of hybrid Petri nets in a class of typical hybrid systems, the air traffic control system, is discussed. A hierarchical hybrid Petri nets model is established for the key entities in the air traffic control system. The flight path of the aircraft taking off and landing is simulated and analyzed, thus lay the foundation for the study of the collision free of the aircraft.In summary, this paper studies the application of hybrid Petri nets in modeling and simulation of hybrid systems. A simulation algorithm of hybrid Petri nets is proposed. A hybrid Petri nets simulation tool is designed, which is easy to expand. The modeling and simulation method of hybrid Petri nets is applied to the air traffic control system, which extends the application field of hybrid Petri nets.