Manufacturing industries rely on automated manufacturing systems to improve the efficiency, quality and flexibility of production. Such systems typically consist of a variety of manufacturing machinery and control hardware, e.g. CNC machine tools, robots, PCs, Programmable Logic Controllers (PLCs) etc., which operate concurrently. The cost of developing and implementing an automated manufacturing system is high, and is particularly so if the control system is found to be unreliable or unsafe during operation. Distributed Control Systems are generally used to control complex concurrent systems,At present the methods used to develop DCSs tend to follow a sequence of steps, viz. a statement of the requirements of the DCS, a functional specification of the DCS, the design of the DCS, generation of the software code for the DCS, implementation of the software. This step approach is inadequate because of the dissimilarity of techniques used to represent each step, which leads to difficulties in ensuring equivalence between the final implementation of the DCS and the initial requirements, which in turn leads to errors in the final software. To overcome this, work has been conducted to unify the specification, design, and software coding phases of the DCS development procedure by ensuring formal equivalencies between them. One particular outcome of such previous work is a tool named Petri Net - Occam Methodology, developed by Dr. P. Gray, which produces dependable Occam code for DCSs. Gray's methodology produces readable designs, directly from the specification of systems, in a graphical but formal way, and results in a Petri Net graph which is equivalent to the final Occam code. However, his methodology is not for a complete DCS but only for one containing Transputers. The PLC is widely used in industry and an integral part of DCSs for Automated Manufacture. This research has developed a methodology, named PNPLC, which produces dependable PLC control programs, in a graphical but formal way, directly from a system's specification. It uses the same tool, Petri Nets, for both designing and simulating the control system, and specifies rules which ensure the correct design, simulation and encoding of PLC programs. The PN designs are a one-to-one equivalent to PLC code and can be directly translated into Ladder Diagrams. Therefore if the simulation shows the design to be correct, the final software will be correct. PNPLC works as a stand alone tool for developing dependable PLC control programs, and also unifies with Gray's methodology to produce a complete tool for developing a resilient DCS containing Transputers and PLCs. The unification of the two methodologies is also reported in this thesis. The research work presented in this thesis contributes to knowledge in the field of DCS development. Recommendations for further work regarding the applicability of the unified methodology on a wide scale industrial basis are also given.

Published Article / RFID can work in conjunction with sensors in material handling especially on a conveyor belt. A dozen different graded tagged products can be picked up by the RFID system in real-time and transported to respective chutes into automatic guided vehicles (AGV) for transportation to specific storage locations. The development of this system is now at an advanced stage. Our predictions to date show that the application of RFID in material handling in a manufacturing environment can assist in the fast flow of components throughout the assembly line beyond what available systems can do.

An important consideration in discrete event dynamic systems control theory is the selection of a suitable modeling formalism that can capture the complex characteristics of the system and the capability to automatically synthesize a controller based on the system model. Net condition event systems are well suited for modeling complex discrete event dynamic systems owing to their input and output structure, which effectively captures the behavior of the physical devices to be monitored and/or controlled. To date, net condition event systems control models have not been extensively applied to highly automated manufacturing systems and there are few guidelines on how to automatically generate Programmable Logic Controller programming languages from net condition event systems models. This research automatically converted net condition event systems control models into Programmable Logic Controller programming language and evaluated the applicability of the proposed methodology in highly automated manufacturing systems using HAS-200 as a test bed.

Le contrôle de systèmes industriels à cause de l’automatisation et la réduction de nombre des opérateurs devient un enjeu crucial. Les systèmes de production automatisés (AMS) sont d’autant plus touchés car une défaillance du programme de contrôle peut réduire considérablement la productivité voire entraîner l’arrêt du système de production. Pour certains de ces systèmes où le partage des ressources est pondérant, la notion de blocage partiel ou global est fréquente et la validation avant implantation est préférable pour réduire les risques.En raison de la capacité des réseaux de Petri à décrire aisément l’exécution concurrente des processus et le partage des ressources, de nombreuses méthodes de vérification d’absence de blocage et de synthèse de contrôleurs basées sur la théorie structurelle ou le graphe d’accessibilité des réseaux de Petri ont été proposées au cours des deux dernières décennies.Traditionnellement, une méthode de prévention de blocage est évaluée selon trois critères de performance: la complexité structurelle, la permissivité comportementale, et la complexité de calcul. Les méthodes fondées sur l’espace d’état aboutissent généralement à un contrôle maximal permissif mais souffrent de l'explosion combinatoire de l'espace d'états. En revanche, les méthodes de synthèse de contrôleurs fondées sur l’analyse structurelle évitent le problème de l’explosion de l’espace d’état mais aboutissent à des superviseurs pouvant restreindre considérablement les comportements admissibles du système. De plus si la théorie structurelle de contrôle de siphons pour la synthèse des superviseurs est mature dans le cas des réseaux de Petri ordinaires, elle est en développement pour les réseaux de Petri généralises. Par ailleurs, la plupart des travaux existants partent du principe que les ressources sont constamment disponibles. Or l’indisponibilité de ressources est en réalité un phénomène ordinaire. Il serait donc judicieux de développer une politique de vérification de blocage qui soit efficace tout en considérant des ressources non fiables.Cette thèse vise principalement à faire face aux limitations mentionnées ci-dessus. Nos principales contributions à la fois théoriques et algorithmiques sont les suivantes.Premièrement, après avoir revisité les conditions de contrôlabilité des siphons (cs–propriété) et précisé les limitations de la max cs- propriété et max’ cs- propriété, nous définissons la max’’ cs-propriété et nous démontrons que cette nouvelle propriété est une condition non seulement suffisante mais aussi nécessaire pour la vivacité de la classe des GS3PR (Generalized Systems of SimpleSequential Processes with Resources).Par la suite nous montrons comment le problème de la vérification de cette propriété et donc la vivacité des GS3PR peut se ramener à la résolution d’un programme linéaire en nombre entiers.Dans une seconde partie, nous proposons une classe de réseaux de Petri appelée M-Nets dotée d’une forte capacité de modélisation des systèmes de production automatisés. En combinant la théorie du contrôle siphon avec la théorie des régions, nous développons une méthode de prévention de blocage ayant un bon compromis entre l'optimalité du comportement et la complexité de calcul. De plus, nous proposons une méthode de synthèse d'un contrôleur maximal permissif pour une sous-classe de réseaux notée b-nets.Enfin, nous proposons dans cette thèse une méthode de conception d’un superviseur de systèmes de production automatisés où les ressources ne sont pas toutes fiables et particulièrement efficace pour la classe des S3PR (Systems of Simple Sequential Processes with Resources). / Because of automation and reduction of the number of operators, the control of industrial systems is becoming a critical issue. For automated manufacturing systems (AMS) where resource sharing is preponderant, the notion of partial or total blocking is frequent and validation before implementation is preferable to reduce the risks.Due to the easy and concise description of the concurrent execution of processes and the resource sharing by Petri nets, many methods to verify deadlock-freeness and to synthesize controllers using structural theory or reachability graph have been proposed over the past two decades.Traditionally, a deadlock control policy can be evaluated by three performance criteria : structural complexity, behavioral permissiveness, and computational complexity. Generally, deadlock control policies based on the state space analysis can approach the maximal permissive behavior, but suffer from the state explosionproblem. On the contrary deadlock control policies based on the structural analysis of Petri nets avoid in general the state explosion problem successfully, but cannot lead to the maximally or near maximally permissive controller. Morover, the current Deadlock control theory based on siphons is fairly mature for ordinary Petri nets,while for generalized Petri nets, it is presently at an early stage.On the other hand, most deadlock control policies based on Petri nets for AMS proceed on the premise that the resources in a system under consideration are reliable. Actually, resource failures are inevitable and common in most AMS, which may also cause processes to halt. Therefore, it is judicious to develop an effective and robust deadlock control policy considering unreliable resources.This thesis aims to cope with the limitations mentioned above. Our main theoretical and algorithmic contributions are the following. Firstly, after revisiting the controllability conditions of siphons and limitations of max and max' controlled-siphon properties, we define the max'' cs property and we prove that this new cs-property is not only sufficient but also a necessary liveness condition forgeneralized systems of simple sequential processes with resources (GS3PR). Moreover, we show how the checking of this property and hence liveness of GS3PR nets can be translaled into resolution of an integer programming (IP) model.Secondly, we propose a class of manufacturing-oriented Petri nets, M-nets for short, with strong modeling capability. Combining siphon control and the theory of regions, we develop a deadlock prevention method that makes a good trade-off between behavioral optimality and computational tractability Moreover, this thesis proposes a maximally permissive control policy for a subclass of Petri nets (calledBéta-nets) based on the token distribution pattern of unmarked siphons.Finally, we propose a designs method for robust liveness-enforcingsupervisors for AMS with unreliable resources appropriate in particular for systems of simple sequential processes with resources(S3PR)

Nos travaux portent sur l'analyse des systèmes de production automatisée à l'aide de réseaux de Petri. Le problème posé est de savoir si un système peut se bloquer complètement ou partiellement et si besoin de calculer un contrôleur garantissant son bon fonctionnement. Les systèmes de production se modélisent naturellement à l'aide d'une sous-classe des réseaux de Petri, les S3PRs. Ce modèle a été très largement étudie par le passe conduisant à des méthodes basées uniquement sur la structure du modèle. Dans ce travail, nous généralisons ces travaux aux modèles des WS3PR, une extension des S3PR ou la réalisation d'une active nécessite non par une ressource mais plusieurs ressources d'un même type et pour lesquels nous proposons des techniques originales combinant des éléments de Théorie des graphes et de théorie des nombres, améliorant même les méthodes du passe sur le modèle simple des S3PR.On présente une caractérisation fine de la vivacité d'un tel modèle basée la notion d'attente circulaire. Une attente circulaire peut être vue comme une composante connexe du sous graphe réduit aux transitions et aux places ressources du modèle. Puis nous démontrons que la non vivacité d'un WS3PR est équivalente a l'existence d' ≪ un blocage circulaire dans une attente circulaire ≫. Ce résultat généralise finement la caractérisation de la vivacité d'un S3PR. Apres avoir introduit la notion de ≪ circuits du graphe de ressources ≫ (WSDC), on construit une méthode de contrôle de ces verrous garantissant la vivacité du modèle d'autant plus efficace qu'une méthode de décomposition du réseau est proposée. Enfin, une traduction de traduit la condition de vivacité des WS3PR sous la forme d'un programme linéaire en nombres entiers est établie et des expérimentations ont démontré l'intérêt de la méthode pour contrôle de systèmes l'allocation des ressources. / As an indispensable component of contemporary advanced manufacturing systems, flexible manufacturing systems (FMSs) possess flexibility and agility that traditional manufacturing systems lack. An FMS usually consists of picking and placing robots, machining centers, logistic systems, and advanced control systems. Some of them can be recognized as its shared resources, which result in its flexibility but may lead to its deadlocks. As a classic problem in resource allocation systems, deadlocks may arise in a fully automated FMS and bring about a series of disturbing issues, from degraded and deteriorated system productivity and performance to low utilization of some critical and expensive resources and even long system downtime. Therefore, the analysis of and solution to deadlock problems are imperative for both a theoretical investigation and practical application of FMSs. Deadlock-freedom means that concurrent produc-tion processes in an FMS will never stagnate. Furthermore, liveness, another significant behavioral property, means that every production process can always be finished. Liveness implies deadlock-freedom, but not vice versa. The liveness-enforcement is a higher requirement than deadlock-freedom.From the perspective of the behavioral logic, the thesis focuses on the intrinsicallylive structures and deadlock control of generalized Petri nets modeling flexible manufacturing systems. Being different from the existing siphon-based methods, a concept of intrinsically live structures becomes the starting point to design, analyze, and optimize a series of novel deadlock control and liveness-enforcing methods in the work.The characteristics and essence of intrinsically live structures are identified and derived from subclasses of generalized Petri nets modeling FMSs with complex resource usage styles. In addition, the numerical relationship between initial markings and weights of connecting arcs is investigated and used to design restrictions that ensure the intrinsical liveness of global or local structures.With the structural theory, graph theory, and number theory, the thesis work achieves the goals of deadlock control and liveness-enforcement.The proposed methods are superior over the traditional siphon-based oneswith a lower computational complexity (or a higher computational efficiency),a lower structural complexity, and a better behavioral permissiveness of the controlled system.

Le contrôle de systèmes industriels à cause de l’automatisation et la réduction de nombre des opérateurs devient un enjeu crucial. Les systèmes de production automatisés (AMS) sont d’autant plus touchés car une défaillance du programme de contrôle peut réduire considérablement la productivité voire entraîner l’arrêt du système de production. Pour certains de ces systèmes où le partage des ressources est pondérant, la notion de blocage partiel ou global est fréquente et la validation avant implantation est préférable pour réduire les risques.En raison de la capacité des réseaux de Petri à décrire aisément l’exécution concurrente des processus et le partage des ressources, de nombreuses méthodes de vérification d’absence de blocage et de synthèse de contrôleurs basées sur la théorie structurelle ou le graphe d’accessibilité des réseaux de Petri ont été proposées au cours des deux dernières décennies.Traditionnellement, une méthode de prévention de blocage est évaluée selon trois critères de performance: la complexité structurelle, la permissivité comportementale, et la complexité de calcul. Les méthodes fondées sur l’espace d’état aboutissent généralement à un contrôle maximal permissif mais souffrent de l'explosion combinatoire de l'espace d'états. En revanche, les méthodes de synthèse de contrôleurs fondées sur l’analyse structurelle évitent le problème de l’explosion de l’espace d’état mais aboutissent à des superviseurs pouvant restreindre considérablement les comportements admissibles du système. De plus si la théorie structurelle de contrôle de siphons pour la synthèse des superviseurs est mature dans le cas des réseaux de Petri ordinaires, elle est en développement pour les réseaux de Petri généralises. Par ailleurs, la plupart des travaux existants partent du principe que les ressources sont constamment disponibles. Or l’indisponibilité de ressources est en réalité un phénomène ordinaire. Il serait donc judicieux de développer une politique de vérification de blocage qui soit efficace tout en considérant des ressources non fiables.Cette thèse vise principalement à faire face aux limitations mentionnées ci-dessus. Nos principales contributions à la fois théoriques et algorithmiques sont les suivantes.Premièrement, après avoir revisité les conditions de contrôlabilité des siphons (cs–propriété) et précisé les limitations de la max cs- propriété et max’ cs- propriété, nous définissons la max’’ cs-propriété et nous démontrons que cette nouvelle propriété est une condition non seulement suffisante mais aussi nécessaire pour la vivacité de la classe des GS3PR (Generalized Systems of SimpleSequential Processes with Resources).Par la suite nous montrons comment le problème de la vérification de cette propriété et donc la vivacité des GS3PR peut se ramener à la résolution d’un programme linéaire en nombre entiers.Dans une seconde partie, nous proposons une classe de réseaux de Petri appelée M-Nets dotée d’une forte capacité de modélisation des systèmes de production automatisés. En combinant la théorie du contrôle siphon avec la théorie des régions, nous développons une méthode de prévention de blocage ayant un bon compromis entre l'optimalité du comportement et la complexité de calcul. De plus, nous proposons une méthode de synthèse d'un contrôleur maximal permissif pour une sous-classe de réseaux notée b-nets.Enfin, nous proposons dans cette thèse une méthode de conception d’un superviseur de systèmes de production automatisés où les ressources ne sont pas toutes fiables et particulièrement efficace pour la classe des S3PR (Systems of Simple Sequential Processes with Resources). / Because of automation and reduction of the number of operators, the control of industrial systems is becoming a critical issue. For automated manufacturing systems (AMS) where resource sharing is preponderant, the notion of partial or total blocking is frequent and validation before implementation is preferable to reduce the risks.Due to the easy and concise description of the concurrent execution of processes and the resource sharing by Petri nets, many methods to verify deadlock-freeness and to synthesize controllers using structural theory or reachability graph have been proposed over the past two decades.Traditionally, a deadlock control policy can be evaluated by three performance criteria : structural complexity, behavioral permissiveness, and computational complexity. Generally, deadlock control policies based on the state space analysis can approach the maximal permissive behavior, but suffer from the state explosionproblem. On the contrary deadlock control policies based on the structural analysis of Petri nets avoid in general the state explosion problem successfully, but cannot lead to the maximally or near maximally permissive controller. Morover, the current Deadlock control theory based on siphons is fairly mature for ordinary Petri nets,while for generalized Petri nets, it is presently at an early stage.On the other hand, most deadlock control policies based on Petri nets for AMS proceed on the premise that the resources in a system under consideration are reliable. Actually, resource failures are inevitable and common in most AMS, which may also cause processes to halt. Therefore, it is judicious to develop an effective and robust deadlock control policy considering unreliable resources.This thesis aims to cope with the limitations mentioned above. Our main theoretical and algorithmic contributions are the following. Firstly, after revisiting the controllability conditions of siphons and limitations of max and max' controlled-siphon properties, we define the max'' cs property and we prove that this new cs-property is not only sufficient but also a necessary liveness condition forgeneralized systems of simple sequential processes with resources (GS3PR). Moreover, we show how the checking of this property and hence liveness of GS3PR nets can be translaled into resolution of an integer programming (IP) model.Secondly, we propose a class of manufacturing-oriented Petri nets, M-nets for short, with strong modeling capability. Combining siphon control and the theory of regions, we develop a deadlock prevention method that makes a good trade-off between behavioral optimality and computational tractability Moreover, this thesis proposes a maximally permissive control policy for a subclass of Petri nets (calledBéta-nets) based on the token distribution pattern of unmarked siphons.Finally, we propose a designs method for robust liveness-enforcingsupervisors for AMS with unreliable resources appropriate in particular for systems of simple sequential processes with resources(S3PR)

Made available in DSpace on 2016-06-02T19:06:03Z (GMT). No. of bitstreams: 1 4911.pdf: 4490259 bytes, checksum: 94cfbdb804ef2f55cb81e1163b1c6ad4 (MD5) Previous issue date: 2011-07-01 / Universidade Federal de Sao Carlos / Resources sharing is one of the main characteristics of Automated Manufacturing Systems (SMA), this characteristic can be a synonym of advantages but on the other hand it may lead to the problem of deadlock. Several papers have suggested methods and techniques to reduce or eliminate the occurrence of deadlocks in SMA systems. The deadlock resolution strategies suggested in the literature can be classified into the following types: deadlock detection and recovery, deadlock prevention and deadlock avoidance. This work proposes a resolution method for the control of automated manufacturing systems using colored Petri nets, the main goal of the proposed method is to provide a deadlock-free production controller. To model, simulate and implement the technique in a production controller a dedicated software is used to model the Petri Nets. Initially, a model using Colored Petri Nets is proposed, then changes in the model are introduced in order to eliminate the deadlocks, resulting in a Colored Petri net control model of the SMA. Finally the model is implemented in the scenario of a Flexible Manufacturing System for testing and validation of the method. / O Compartilhamento de recursos é uma das principais características dos Sistemas de Manufatura Automatizados (SMA), esta característica pode ser um sinônimo de vantagens, mas por outro lado pode levar ao problema de deadlock. Diversos trabalhos têm sugerido métodos e técnicas para reduzir ou eliminar a ocorrência de deadlocks em SMA. As estratégias de resolução de deadlock sugerido na literatura podem ser classificados nos seguintes tipos: detecção e recuperação de deadlocks, prevenção de deadlocks e de deadlock. Este trabalho propõe um método de resolução para o controle de sistemas de manufatura automatizados utilizando redes de Petri coloridas, o principal objetivo do método proposto é obter um controlador da produção livre de deadlocks. Para modelar, simular e implementar a técnica em um controlador de produção um software dedicado é usado para modelar a rede de Petri. Inicialmente, um modelo usando Redes de Petri Coloridas é proposto, então mudanças são introduzidas, a fim de eliminar os deadlocks, resultando em um modelo de rede de Petri de um SMA livre de deadlock. Finalmente o modelo é implementado no cenário de um Sistema de Manufatura Flexível para testes e validação do método.

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aus dem Inhalt: „Im Vergleich zur automatisierten Fertigung anderer industrieller Branchen ist das Bauen mit Beton noch immer stark durch handwerkliche Tätigkeiten geprägt. Dazu kommt, dass die endgültigen Eigenschaften von Betonbauteilen stark von den Umgebungsbedingungen während der Herstellung abhängig sind. Dieser Zustand führt zu Ungenauigkeiten und Unsicherheiten bei der Bauwerkserstellung, welche in einem wenig effizienten Materialeinsatz und Störungen im Bauprozess resultieren. Lange Bauzeiten und Wartezeiten bei Störungen sind die Folgen....” / from the content: „Compared to the automated production of other industrial sectors, construction with concrete is still strongly characterized by craftsmanship. In addition, the final properties of concrete components are strongly dependent on the environmental conditions during production. This leads to inaccuracies and uncertainties during construction, which result in inefficient use of materials and disruptions in the construction process. Long construction times and waiting periods in the case of disruptions are the consequences....”

Made available in DSpace on 2016-06-02T19:05:32Z (GMT). No. of bitstreams: 1 2127.pdf: 1371924 bytes, checksum: 9875e1d607356e12cb2a118b33474a4e (MD5) Previous issue date: 2008-09-12 / The production scheduling problem of products with simultaneous use of machines and transportation systems in manufacturing systems invloves the system modeling task and the application of a technique to solve it. This scheduling type is characterized by the great amount of possible solutions and several researches indicates the Adaptive Genetic Algorithms as search method to solve this problem, where these algorithms have the capacity of globally explore the search space and to find good solutions quickly. In this dissertation, it is proposed a method that uses an adaptive genetic algorithm to solve this scheduling problem. The aim of this dissertation is to obtain good scheduling of product production, in order to reach good makespan values and response obtaining time. The makespan values are obtained by adaptive genetic algorithm and the response obtaining time is the processing time of the adaptive genetic algorithm. The results were validated in small and large scenerios and compared with the results of two other approaches. These results are presented and discussed in this dissertation. / O problema da programação da produção de produtos com uso simultâneo de máquinas e sistemas de transporte em sistemas de manufatura envolvem questões como a modelagem do problema e a técnica utilizada para resolvê-lo. Este tipo de programação é caracterizado pela grande quantidade de soluções possíveis, em que várias pesquisas apontam para o uso de Algoritmos Genéticos Adaptativos como método de busca, uma vez que estes algoritmos possuem a capacidade de percorrer de forma global o espaço da busca, a fim de encontrar boas soluções rapidamente. Neste trabalho, é proposto um método com uso de um algoritmo genético adaptativo para resolver este tipo de problema de programação. O objetivo deste trabalho é obter uma boa programação da produção de produtos, a fim de atingir um bom compromisso entre valores de makespan e de tempo de obtenção da resposta. Os valores de makespan são obtidos a partir da aplicação do algoritmo genético adaptativo e o tempo de obtenção da resposta é referente ao tempo de processamento do algoritmo genético adaptativo. Os resultados deste trabalho foram validados para cenários pe quenos e grandes e comparados com os resultados de outras duas abordagens. Estes resultados são apresentados e discutidos neste trabalho.