Les ateliers flexibles représentent pour les industriels un réel atout face à la concurrence et à l'imprévisibilité du marché. La mise en place et la gestion de ces catégories d'ateliers de production est souvent complexe, difficile et coûteuse. Ce travail de thèse, propose un outil d'aide à la décision permettant d'accompagner les industriels dans l'acquisition et la gestion d'ateliers flexibles de production. Cet outil s'appuie sur un modèle de simulation basé sur les Réseaux de Pétri Colorés Hiérarchiques. En effet, la simulation permet d'observer les variations des paramètres du système et de déterminer ses critères de performance. Les objectifs de cet outil sont de permettre la modélisation, la simulation et l'évaluation des systèmes de production en prenant en compte plusieurs contraintes rencontrées dans les systèmes industriels. Nous avons utilisé ce simulateur pour tester et valider une solution au problème d'acheminement des produits au cours de la production. Le choix des Réseaux de Pétri(RdP), au détriment des modèles analytiques, se justifie par le fait qu'ils offrent une représentation graphique permettant une description des processus plus simplifiée que des modèles analytiques. Au-delà de la modélisation et la simulation, les RdP permettent de vérifier les blocages d'un système. Parmi les modèles que nous avons développés nous pouvons citer : les modèles des machines, des stocks, des ressources de transport et des produits dans un système de production flexible. Nous avons insisté sur la modélisation des produits, des machines et du système de transport qui représentent le coeur des problématiques de flexibilité. Nous avons validé ces modèles sur un cas réel à savoir la chaîne de production du CESI de Rouen. Ensuite pour résoudre le problème du transport, nous avons proposé et déployé une méthode d'aide à la décision basée sur l'entropie et le classement de règles de dispatching. Cette méthode permet de définir, en fonction de l'état actuel, un ordre de priorité entre les règles de dispatching. Nous avons comparé cette nouvelle méthode à la méthode classique où l'importance des règles de priorité est définie préalablement, avant la phase de production. Notre proposition a donné des résultats intéressants que nous avons exposés et discutés. / Flexible Manufacturing Systems are real opportunity for industrials to face the comptetion and the unpredictability of the market. The management implementation of this kind of manufacturing systems are complex difficult and expensive.In this thesis work, we propose a decision making tool for managing Flexible Manufacturing Systems. The latter is based on a simulation model with Hierarchical Colored Petri Nets. The simulation allows the observation of the parameters variation of a system, and the determination of performance criteria. The objectives of this tool are to enable the modeling, simulation and evaluation of production systems taking into account most of the constraints encountered in industrial systems. We used this simulator to test and validate a solution to the problem of routing products during production. The choice of Petri nets (PN) to the detriment of analytical models is justified by the fact that Petri Nets with its graphical representation allows a simplified description of processes as analytical models , Petri Nets can be used for simulation, and with simulation we can predict the behaviour of a systems during a production phase. Petri Nets allow, beyond modeling and simulation to prevent the dead locks of systems. These are the reasons why we use Petri Nets to develop our models. Among the models that we have developed we can mention : machine, stocks, transportation resources and products models. We insisted on product and machine modelling which are in the center of flexibility issues. In order to study the routing problem, We defined models to represent the transport activity. We validated these models on a real case namely the production chain of CESI of Rouen. Then to solve the routing problem, we developed a decision making method based on entropy and dispacthing rules. This method allows to modify the dispatching rules weight in function of the state of the manufacturing systems during the production (size of stocks; machine failure). We compared this method with an another one where the weight of dispatching rules are unchanged during the production phase. We obtained interesting result that we have presented and discussed.

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No description available.

A Flexible Manufacturing System (FMS) is an integrated system consisting of several automated work centers interconnected by an automated material handling system. An integrated scheduling methodology is required to schedule all FMS sub-systems. The overall objective of this research was to develop a scheduling methodology to integrate job sequencing and Automatic Guided Vehicle System dispatching within a FMS environment. To develop the new scheduling methodology, the currently used AGVS controller decision set was examined and expanded. The expanded decision set gives the AGVS controller more options to choose from when scheduling the AGVS. The developed integrated scheduling methodology contains four steps. The first step determines which job is to be processed next by each work center based on job sequencing heuristics. The second step determines which work center is to be serviced next by the AGVS based on the estimated time till the work center is forced to stop production. The third step determines which specific job is to be serviced next by the AGVS by combining the work centers' processing orders and the work center servicing priorities. The fourth step decides which AGV is to transport the job requiring immediate service. Based on the preliminary study of a fictitious FMS, the new scheduling methodology showed a statistically significant increase in total job throughput, and a significant decrease in average flow time. Work center utilization also increased. A slight increase in unloaded AGV travel time was found, but was outweighed by the other benefits. / Master of Science

There are a large number of Group Technology (GT) based cell formation techniques in the literature, but their applications rare. It is hypothesized that the reason behind the lack of applications of these techniques in practice, is "fear of the unknown”. There have been a very limited number of attempts to determine the performance of any of the cell formation techniques. This thesis attempts to demonstrate a method to determine the performance of cell formation techniques by measuring the physical performance of the manufacturing cell. The methodology involves a manual evaluative approach to determine the cell performance from the data given for the system. The methodology presents selection of important Performance Measures (PMs), data requirement for the measurement of PMs and cell formation technique analysis. The performance measures to determine the performance of these techniques were selected according to their importance to the productivity of the manufacturing cell and their significance among GT principles. The cell formation techniques selected to demonstrate the method are Rank Order Clustering algorithm (ROC) and Production Flow Analysis (PFA). Using ROC and PFA, part families and machines groups were formed creating cell layouts. From the given data, performance measure values were calculated for a functional layout as well as ROC and PFA layouts. Performance of ROC and PFA layouts were compared to each other and to the functional layout. Results from the example show that performance improvement can be achieved by the two cell formation techniques in all the performance measures category except in flexibility. Performance of ROC and PFA are the same in the categories of setup time, machine utilization. and flexibility. The reason being, similar machine groupings and part families were achieved by both techniques for this example. Material handling performance and flexibility are dependent largely on machine grouping, whereas setup time is dependent on part families. Machine utilization and work-in-process are dependent on machine groups as well as part families. It appears PFA would have better performance in cases of complex problems having large number of machines and parts due to its comprehensiveness and ability to group machines according to the parts’ processing similarities. The advantage of ROC is mainly in its ease of application and rather elegant way of handling bottleneck machines and exceptional parts. Due to the lack of flexibility in GT layouts, system design and operation planning should be done carefully. / Master of Science

No description available.

Electroactive polymers are a class of materials capable of reallocating their shape in response to an electric field while also having the ability to harvest electrical energy when the materials are mechanically deformed. Electroactive polymers can therefore be used as sensors, actuators, and energy harvesters. The parameters for manufacturing flexible electroactive polymers are complex and rate limiting due to number of steps, their necessity, and time intensity of each step. Successful additive manufacturing processes for electroactive polymers will allow for scalability and flexibility beyond current limitations, advancing the field, opening additional manufacturing possibilities, and increasing output. The goal for this research was to use additive manufacturing techniques to print conductive and dielectric substrates for building flexible circuits and sensors. Printing flexible conductive layers and substrates together allows for added creativity in design and application.

A necessidade de aumento de produção, da redução de custos e do aumento da qualidade de bens de consumo, tem motivado a constante evolução dos sistemas de produção, migrando os tradicionais sistemas de produção para os modernos e complexos sistemas de manufatura, onde a performance depende da eficiência dos equipamentos e do controle do processo. Por outro lado, a eficiência dos equipamentos depende de sua confiabilidade e manutenabilidade. Neste trabalho a análise de performance é avaliada com o uso de Rede de Petri p-t-Temporizada e através de simulações, incluindo a avaliação da confiabilidade do processo pela análise da otimização da saída do sistema, isto é, quantidade de itens produzidos. Nesta abordagem, uma lógica linear foi desenvolvida e validada utilizando-se uma comparação de resultados das classes de estados do algoritmo proposto com a ferramenta de simulação Tina para um modelo de um esquema produtor consumidor. Apresenta-se um estudo de caso na indústria automotiva, consistindo na análise dos problemas reais enfrentados em uma fábrica de carrocerias, com o uso da Rede de Petri p-t-Temporizada. / The necessity of growing in production, with reduction of costs and improvement in the quality of consumption good, has motivated the constant evolution of production systems, transforming traditional production systems into the modern and complex manufacturing systems, where the performance depends on the efficiency of the equipment and process control. On the other hand, the equipment efficiency depends of their reliability and maintainability. In this work it is proposed a performance evaluation and analysis with the use of p-t- Timed Petri Nets using simulations, including process reliability analysis of the system through the throughput optimization, i.e., produced amount of goods. In this approach, a linear logic statement was developed and validated using a comparison of results of classes of states between the Tina simulation environment and the algorithm considered for a model of a producing consuming system. A case study in the automotive industry is presented, consisting of the analysis of the real problems found in a body shop plant, with the use of Timed Petri Net.

Well-behaved SNC covers well-behaved and various classes of FC (free-choice) and is not included in AC (asymmetric choice). An SNC allows internal choices and concurrency and hence is powerful for irodeling. Any SNC is bounded and its liveness conditions are simple. An integrated algorithm, has been presented for verification of a net being SNC and its liveness with polynomial time complexity. Scholars often need to verify properties on nets appearing in literatures. Verification by CAD tool is less desirable than that by hand due to the extra efforts to input the model aid learn to use the tool. We propose to manually search the maximum SNC component followed by locating bad siphons in an incremental manner. We then apply Lautenback's Maridng Condition (MC) for liveness to berify the property of liveness. But there are two drawbacks associated with the above MC. First, it guarantees only deadlock-freeness, and not necessary liveness. We have identified the structure cause for this and developed its livess conditions correspondingly. Second a net may be live even if the MC is not satisfied. We have identified the structure cause for this. The MC has been readjusted based on our proposed new theorey.

Today's manufacturing environment is characterized by competition and continuous change in product and process requirements. The concept of "design for manufacturability" integrates product specifications with manufacturing capabilities by considering the design and manufacturing phases as an integrated system, evaluating the combined system during the design phase of a product , and adjusting the design for maximum efficiency and production economics. This research focuses on one aspect of design for manufacturability, that of process technology evaluation for a specified product design. The objective of the proposed system developed in this study is to evaluate technology alternatives for manufacturing a specified part design and to identify the best combination of product-process characteristics that would minimize production costs within the constraints set by the product's functional requirements and available processing technology. The research objectives are accomplished by developing a simulation based analysis system. The user inputs product specifications through structural screens. The system maintains data bases of work and tool materials, and machining operations. Based on user input, the system then extracts appropriate information from these data bases, and analyzes of the production system in terms of production economics, and other operational measures such as throughput times and work-in-process inventories. Sensitivity analysis may then be performed to explore tradeoffs in design and production parameters. The system is completely integrated, and a user with no prior experience of either simulation or data base technology can use the system effectively. / Graduation date: 1992