A SURVEY OF PETRI-NET METHODS FOR CONTROLLED DISCRETE-EVENT SYSTEMS

This paper surveys recent research on the application of Petri net mod els to the analysis and synthesis of controllers for discrete event sy stems. Petri nets have been used extensively in applications such as a utomated manufacturing, and there exists a large body of tools for qua litative and quantitative analysis of Petri nets. The goal of Petri ne t research in discrete event systems is to exploit the structural prop erties of Petri net models in computationally efficient algorithms for computing controls. We present an overview of the various models and problems formulated in the literature focusing on two particular model s, the controlled Petri nets and the labeled nets. We describe two bas ic approaches for controller synthesis, based on state feedback and ev ent feedback. We also discuss two efficient techniques for the on-line computation of the control law, namely the linear integer programming approach which takes advantage of the linear structure of the Petri n et state transition equation, and path-based algorithms which take adv antage of the graphical structure of Petri net models. Extensions to t imed models are briefly described. The paper concludes with a discussi on of directions for future research.