Colored Petri Nets For Modeling Of Discrete Systems

This book offers a practical approach to modeling real-world discrete systems and performing analysis. The theory behind the book is the Colored Petri nets, and the tool used for simulations is general-purpose Petri net simulator (GPenSIM). The theory part is kept to a minimum, and more explanation is given to the GPenSIM functions and how they can be used for modeling, simulation, and performance analysis. Real-world industrial systems possess a large number of resources. Modeling these systems with Petri nets would become a problem as they result in huge Petri net models. This book offers a unique solution to this problem by moving resources away from the Petri net model and treating them as variables in the background. Also, the theory and practice put forward in the book help cost estimation of the systems (e.g., manufacturing subsystems).

This book offers a new Modular Petri Net as a solution to the vast Petri net models. It presents some approaches centering around modules (known as “Petri modules”). The goal of this book is to introduce a methodology in which Petri nets are moved to a new level. In this new level, large Petri net models are made of Petri modules, which are independent and run on different computers. This book also contains the literature study on modular Petri nets and definitions for the newer Petri modules. Also, algorithms for extracting Petri modules, and algorithms for connecting Petri modules, and applications are given in this book. Besides, the ideas and algorithms given in this book are implemented in the software General-purpose Petri Net Simulator (GPenSIM). Hence, with the use of this book the readers/users would be able to know that real-life discrete event systems could be modeled, analyzed, and performance-optimized with GPenSIM.

Discrete-event dynamic systems (DEDs) permeate our world. They are of great importance in modern manufacturing processes, transportation and various forms of computer and communications networking. This book begins with the mathematical basics required for the study of DEDs and moves on to present various tools used in their modeling and control. Industrial examples illustrate the concepts and methods discussed, making this book an invaluable aid for students embarking on further courses in control, manufacturing engineering or computer studies.

The world is full of events which cause, end or affect other events. The study of these events, from a system point of view, is very important. Such systems are called discrete event dynamic systems and are of a subject of immense interest in a variety of disciplines, which range from telecommunication systems and transport systems to manufacturing systems and beyond. There has always been an intense need to formulate methods for modelling and analysis of discrete event dynamic systems. Petri net is a method which is based on a well-founded mathematical theory and has a wide application. This book is a collection of recent advances in theoretical and practical applications of the Petri net method and can be useful for both academia and industry related practitioners.

Provides a tutorial on Grafcet and Petri Nets and how they are linked. The concepts are introduced with the aid of examples that progressively become more difficult. Grafcet, which became an international standard in 1987, is a French tool inspired by Petri Nets to specify logic control.

Petri nets do not designate a single modeling formalism. In fact, newcomers to the field confess sometimes to be a little puzzled by the diversity of formalisms that are recognized under this "umbrella". Disregarding some extensions to the theoretical modeling capabilities, and looking at the level of abstraction of the formalisms, Condition/Event, Elementary, Place/Transition, Predicate/Transition, Colored, Object Oriented... net systems are frequently encountered in the literature. On the other side, provided with appropriate interpretative extensions, Controled Net Systems, Marking Diagrams (the Petri net generalization of State Diagrams), or the many-many variants in which time can be explicitly incorporated -Time(d), Deterministic, (Generalized) Stochastic, Fuzzy...- are defined. This represents another way to define practical formalisms that can be obtained by the "cro- product" of the two mentioned dimensions. Thus Petri nets constitute a modeling paradigm, understandable in a broad sense as "the total pattern of perceiving, conceptualising, acting, validating and valuing associated with a particular image of reality that prevails in a science or a branch of science" (Thomas S. Kuhn).

This book presents for the first time a methodology that combines the power of a modelling formalism such as colored petri nets with the flexibility of a discrete event program such as SIMIO. Industrial practitioners have seen the growth of simulation as a methodology for tacking problems in which variability is the common denominator. Practically all industrial systems, from manufacturing to aviation are considered stochastic systems. Different modelling techniques have been developed as well as mathematical techniques for formalizing the cause-effect relationships in industrial and complex systems. The methodology in this book illustrates how complexity in modelling can be tackled by the use of coloured petri nets, while at the same time the variability present in systems is integrated in a robust fashion. The book can be used as a concise guide for developing robust models, which are able to efficiently simulate the cause-effect relationships present in complex industrial systems without losing the simulation power of discrete-event simulation. In addition SIMIO’s capabilities allows integration of features that are becoming more and more important for the success of projects such as animation, virtual reality, and geographical information systems (GIS).

Petri Net Synthesis for Discrete Event Control of Manufacturing Systems develops two essential resource-sharing concepts: parallel and sequential mutual exclusions and theoretical results in Petri synthesis. A parallel mutual exclusion (PME) is defined to model a resource shared by independent distributed processes, and a sequential mutual exclusion is a sequential composition of PMEs, modeling a resource shared by sequentially-related processes. A hybrid synthesis methodology for Petri net models and controllers is proposed using top-down, modular, and bottom-up design ideas and the mutual exclusion theory. An aggregate Petri net model is refined by replacing places and /or transitions with basic design modules which are mathematically and graphically described. Petri net design methods are presented for such buffers as automatic storage and retrieval systems. Using the proposed method synthesizes both Petri net structure and feasible initial markings, guaranteeing that resulting Petri nets have desirable system properties such as freedom from deadlock and cyclic behavior. A Petri net controller is extended to error recovery for automated manufacturing systems. The theory can guarantee that the desired system properties achieved by the original design will be preserved when the controller is augmented to deal with an error in the prescribed methods. Control code has been directly generated from Petri net definitions. The algorithm and implementation details are given for a flexible manufacturing system. Using the approach presented in Petri Net Synthesis for Discrete Event Control of Manufacturing Systems, engineers and research workers can develop their own discrete event control applications and experiments.