Modeling and Simulation of Hybrid Systems Using a Special Class of Timed Petri Net ABOLFAZL JALILVAND 1 , SOHRAB KHANMOHAMMADI 2 , FEREIDOON SHABANI NIA 3 1 Department of Electrical Engineering Islamic Azad University of Abhar 2 Faculty of Electrical and Computer Engineering University of Tabriz 3 Faculty of Electrical and Electronics Engineering Shiraz University IRAN Abstract: Dynamic systems with a mix of continuous and discrete components called hybrid systems frequently arise in engineering applications. By modeling these different components using differential equations and discrete events, it is possible to represent a wide range of phenomena present in physical and technological systems. Since many of these applications are safety critical, it is important to use reliable methods to simulate hybrid systems. This paper deals with modeling and simulation of hybrid systems using an extended form of timed Petri net. The proposed method is used for modeling of an illustrative hybrid system example. The simulation results are obtained by a modified Petri net toolbox. Key-Words: Hybrid systems, Timed Petri nets, Discrete Event, Modeling, Simulation. 1 Introduction Hybrid systems have emerged as a technique for modeling and analyzing a class of autonomous control systems containing both continuous-state and discrete event dynamics [1-3]. Many physical systems are hybrid in the sense that they have barriers or limitations. Inside the limitations they are modeled with differential/difference equations. A natural way to model these systems is to use a mixture of differential/difference equations and inequalities. Other systems have switches and relays that can be naturally modeled as hybrid systems. These hybrid models appear in many areas. Typical examples are manufacturing systems, transportation systems, flight control, communication networks, missile guidance, process control, robotics, path planning, traffic control and so on [4-9]. The application of hybrid modeling and control can be an interesting approach to improve plant performance, efficiency, safety and reliability. In general, a hybrid system can be in one of several modes of operation, whereby in each mode the behavior of the system can be described by a system of differential/difference equations (Fig. 1). The system switches from one mode to another due to the occurrence of events [1]. ) , , ( 4 4 . 4 t u x f x = ) , , ( 4 4 t u x g y = ) , , ( . t u x f x N N N = ) , , ( t u x g y N N = ) , , ( 4 4 . 4 t u x f x = ) , , ( 4 4 t u x g y = ) , , ( 1 1 . 1 t u x f x = ) , , ( 1 1 t u x g y = ) , , ( 3 3 . 3 t u x f x = ) , , ( 3 3 t u x g y = ) , , ( 2 2 . 2 t u x f x = ) , , ( 2 2 t u x g y = Fig. 1: A schematic representation of a hybrid system with N modes. In one formulation of hybrid systems the continuous state plant is supervised by a discrete event controller [10-12]. Such a hybrid system consists of three main components: a plant, a discrete event controller and an interface. The continuous process to be controlled, together with any continuous controller, is identified as plant and