Distributed production planning and control agent based system

A model of an Agent based Production Planning and Control (PPC) system able to be dynamically adaptable to local and distributed utilization of production resources and materials is presented. The PPC system is based on the selection of resources to deal with one order of different quantities of one product each time. In this way it is build one scheduling solution for that particular order. The production resources are selected and scheduled using a multiagent system supported by an implementation of the Smith Contract Net, using Java Spaces technology. The multiagent system is based on three main agents: Client, Resource and Manager. These agents negotiate the final product, and the correspondent components, requested by the client. An order for each product (component) triggers a process of dynamic design of a production system to fulfill that particular order. This system exists till the end of the order

Process control and configuration of a reconfigurable production system using a multi-agent software system

Thesis (M. Tech. (Information Technology)) -- Central University of technology, Free State, 2011Traditional designs for component-handling platforms are rigidly linked to the product being produced. Control and monitoring methods for these platforms consist of various proprietary hardware controllers containing the control logic for the production process. Should the configuration of the component handling platform change, the controllers need to be taken offline and reprogrammed to take the changes into account. The current thinking in component-handling system design is the notion of re-configurability. Reconfigurability means that with minimum or no downtime the system can be adapted to produce another product type or overcome a device failure. The re-configurable component handling platform is built-up from groups of independent devices. These groups or cells are each responsible for some aspect of the overall production process. By moving or swopping different versions of these cells within the component-handling platform, re-configurability is achieved. Such a dynamic system requires a flexible communications platform and high-level software control architecture to accommodate the reconfigurable nature of the system. This work represents the design and testing of the core of a re-configurable production control software platform. Multiple software components work together to control and monitor a re-configurable component handling platform. The design and implementation of a production database, production ontology, communications architecture and the core multi-agent control application linking all these components together is presented

Intelligent maintenance management in a reconfigurable manufacturing environment using multi-agent systems

Thesis (M. Tech.) -- Central University of Technology, Free State, 2010Traditional corrective maintenance is both costly and ineffective. In some situations it is more cost effective to replace a device than to maintain it; however it is far more likely that the cost of the device far outweighs the cost of performing routine maintenance. These device related costs coupled with the profit loss due to reduced production levels, makes this reactive maintenance approach unacceptably inefficient in many situations. Blind predictive maintenance without considering the actual physical state of the hardware is an improvement, but is still far from ideal. Simply maintaining devices on a schedule without taking into account the operational hours and workload can be a costly mistake. The inefficiencies associated with these approaches have contributed to the development of proactive maintenance strategies. These approaches take the device health state into account. For this reason, proactive maintenance strategies are inherently more efficient compared to the aforementioned traditional approaches. Predicting the health degradation of devices allows for easier anticipation of the required maintenance resources and costs. Maintenance can also be scheduled to accommodate production needs. This work represents the design and simulation of an intelligent maintenance management system that incorporates device health prognosis with maintenance schedule generation. The simulation scenario provided prognostic data to be used to schedule devices for maintenance. A production rule engine was provided with a feasible starting schedule. This schedule was then improved and the process was determined by adhering to a set of criteria. Benchmarks were conducted to show the benefit of optimising the starting schedule and the results were presented as proof. Improving on existing maintenance approaches will result in several benefits for an organisation. Eliminating the need to address unexpected failures or perform maintenance prematurely will ensure that the relevant resources are available when they are required. This will in turn reduce the expenditure related to wasted maintenance resources without compromising the health of devices or systems in the organisation

Mobile Robots

The objective of this book is to cover advances of mobile robotics and related technologies applied for multi robot systems' design and development. Design of control system is a complex issue, requiring the application of information technologies to link the robots into a single network. Human robot interface becomes a demanding task, especially when we try to use sophisticated methods for brain signal processing. Generated electrophysiological signals can be used to command different devices, such as cars, wheelchair or even video games. A number of developments in navigation and path planning, including parallel programming, can be observed. Cooperative path planning, formation control of multi robotic agents, communication and distance measurement between agents are shown. Training of the mobile robot operators is very difficult task also because of several factors related to different task execution. The presented improvement is related to environment model generation based on autonomous mobile robot observations

Sistemas distribuídos de produção em ambiente de produção simultânea

Novos paradigmas de produção emergem na economia global, aparentemente baseados em três tendências principais. Estas tendências são: aumento da dinâmica de reconfiguração dos sistemas de produção, distribuição dos recursos do sistema de produção, e virtualidade dos sistemas, i.e. sistemas que são configurados em termos organizacionais, sem alteração da implantação física dos equipamentos. A primeira tendência deve-se ao aumento de requisitos do produto, nomeadamente ao nível da qualidade, variedade e entrega. A segunda tendência resulta de uma necessidade de melhoria do desempenho do sistema de produção, e a terceira, deve-se à impossibilidade de agrupamento físico de recursos de produção distribuídos globalmente e às possibilidades oferecidas pelos sistemas de comunicação existentes. Com base nas referidas tendências surgem novos requisitos de projecto e operação de sistemas de produção. Podem-se seleccionar alguns destes requisitos, resumidos da seguinte forma: aumento da reconfigurabilidade do sistema baseada em recursos de produção distribuídos e na entrega rápida dos produtos encomendados. Com base nestes requisitos, apresenta-se uma definição e desenvolve-se um modelo de Sistema Distribuído de Produção (SDP), denominado MSDP. Neste modelo existe uma relação estreita entre a estrutura genérica do sistema distribuído de produção e a estrutura de transformações de estado do produto encomendado. Desenvolve-se ainda um modelo conceptual baseado em agentes de software do MSDP, e uma representação formal do modelo com base em Redes de Petri e em mecanismos de modelação apresentados por Lecompte, Deschamps and Bourrières (2000). O modelo formal desenvolvido é aplicado a várias configurações de sistemas, relacionadas com a estrutura de algum produto encomendado. Esta aplicação permite verificar a possibilidade de utilização do modelo para representar diferentes SDPs e para estudar o comportamento de SDPs de acordo com a filosofia de Produção Simultânea. Esta filosofia tem como principal objectivo a redução do prazo de entrega de encomendas através da redução do tempo de percurso de fabrico de cada encomenda. O estudo realizado neste trabalho permite concluir que o modelo pode ser utilizado para projecto e avaliação de sistemas distribuídos de produção dedicados a cada encomenda. Além disso, verificou-se que se obtêm ganhos importantes de tempo de percurso de fabrico e de qualidade de serviço de produção para pequenos graus de simultaneidade. Isto foi avaliado para algumas estruturas, por aplicação de estratégias de Produção Simultânea baseada na utilização de recursos de produção alternativos e na partição de encomendas. Como esperado, o melhor desempenho obtém-se para a partição máxima, i.e. partições em lotes de processamento de uma unidade. No entanto, na maioria dos casos testados, a maior parte do ganho verifica-se para pequenos graus de partição. Estes resultados foram obtidos num enquadramento de experimentação que não considerou nem custos de transporte e preparação nem de posse. Baseado nos resultados obtidos e no facto dos dois primeiros custos aumentarem com o aumento da partição e os custos de posse tenderem a diminuir com esse aumento, para tirar vantagem efectiva da Produção Simultânea, devem adoptar-se graus de partição moderados.Apparently, a new paradigm of production is emerging in the new and global economy based on three main tendencies. Such tendencies are: increasing dynamics of manufacturing systems reconfiguration, distribution of the manufacturing resources of a production system, and virtuality of systems, i.e. systems that are configured only on organizational and control terms, not on physical rearrangement of facilities. The first tendency is due to increasing product demand requirements, namely quality, variety and delivery. The second, resulting from a need for enhancement of production performance and, the third, is due to the unfeasibility of physically grouping and rearranging world wide distributed production facilities and due to capabilities offered by world wide communication and logistic systems. Based on the referred tendencies new requirements arise for production systems design and operation. Some can be selected and synthesized as: increased ability for system reconfiguration based on distributed resources and fast delivery of each product ordered. Based on such requirements a definition of Distributed Production Systems (SDP) is put forward together with a model, the MSDP model, of such systems. Such model is closely related with the processing structure of an ordered product to be manufactured. Based on the MSDP model, a formal representation is developed using Petri Nets and modelling mechanisms put forward by Lecompte, Deschamps and Bourrières (2000), and an agent based conceptual model is presented. The formal representation of the model is applied to a variety of systems configuration instances according with the product ordered. The application aim is twofold: first, testing the model suitability for representing and reconfiguring different SDP and, second, for studying the behaviour of SDP, under the Simultaneous Manufacturing philosophy. This philosophy aims at minimizing time delivery of orders through maximum reduction of production flow time of each production order. The study carried out in this work lead to the conclusion that the model is suitable for representation, design and evaluation of distributed production systems dedicated to each product order. Further, a small degree of simultaneous manufacturing was proved enough to achieve important gains in order flow time reduction and quality of the manufacturing service. This was evaluated, for a few system configurations with strategies to simultaneous manufacturing based on simultaneous allocation of order manufacturing requirements to replicated machines, i.e. manufacturing resources, and also based on order splitting at a few different levels. As expected, the best values of performance were obtained under maximum order splitting, i.e. under split batches of size one. However, in most cases tested, the lion share of benefits from splitting was obtained for small degrees of it. These results were obtained under a framework for experiments that did not take into account neither handling and set-up costs nor holding costs. Based on the findings reported and onto the fact that the first two costs increase with order splitting and that holding costs tend to decrease with it, then, it was concluded that, to take effective advantageous of simultaneous manufacturing, moderate degrees of order splitting should be adopted

Projecto dinâmico de sistemas de produção orientados ao produto

Tese de Doutoramento em Engenharia de Produção e SistemasLeanness e agilidade são necessidades importantes das empresas de manufactura na era actual da economia global num mercado intensamente concorrencial, de grande variabilidade e perturbação. De uma forma resumida pode-se dizer que as respostas estratégicas a estas necessidades, no âmbito da produção, são a Produção Lean e a Produção Ágil. A primeira aponta para que o sistema seja convenientemente ajustado às necessidades de produção, numa lógica sincronizada de produção desde a transformação das matérias primas até à distribuição do produto ao cliente, evitando toda a espécie de desperdícios e, portanto, explorando o que se tem designado por produção JIT. A Produção Ágil requer que os sistemas de produção tenham agilidade para rapidamente responderem às variações das necessidades de produção resultantes das variações da procura, i.e. quantidade e variedade de produto. Aparentemente ambas as estratégias confluem num objectivo comum, nomeadamente a resposta rápida da produção às variações da procura através de um ajustamento dinâmico e adequado à variação consequente das necessidades de produção. Nesta tese propõe-se que esse ajustamento seja realizado recorrendo aos Sistemas de Produção Orientados ao Produto (SPOP) que, no essencial, podem ser definidos como sistemas reconfiguráveis formados por conjuntos interligados e complementares de células de produção reconfiguráveis, destinados a, de forma coordenada e sincronizada, fabricar os componentes de um produto ou família de produtos similares, e realizar a sua montagem para entrega rápida ao cliente. A agilidade resulta do requisito de reconfiguração dinâmica dos SPOP face à variação da procura. Devido à complexidade de projecto de SPOP, propõe-se uma metodologia de apoio ao seu projecto e reconfiguração, designada de metodologia GCD por abranger três níveis de concepção, nomeadamente o estratégico, designado de Genérico, o Conceptual e o Detalhado. A metodologia guia o projectista através destas três fases, enquadradas por um conjunto de actividades de projecto sucessivas e interrelacionadas, e sugerindo métodos que podem ser usados para levar a cabo cada actividade. Uma recolha importante de métodos é feita neste contexto. Demonstra-se a utilização da metodologia através de um exemplo de aplicação de projecto de SPOP. Este trabalho baseou-se numa variedade de conceitos conhecidos da literatura e outros propostos e inerentes à metodologia GCD. Portanto uma contribuição ontológica no domínio da investigação é também apresentada sendo de realçar os conceitos de configurações conceptuais, configurações de postos de trabalho, configurações operacionais e modos operatórios de células de produção. No sentido de facilitar a utilização da metodologia é proposto um Sistema assistido por computador de Apoio ao Projecto de SPOP, o SAP_SPOP, e é dada uma contribuição para o desenvolvimento de um seu protótipo. Este sistema está estruturado em três componentes fundamentais: uma base de dados, uma base de métodos e um motor de projecto, designado de SPOP designer. Este inclui um módulo facilitador da interacção entre os elementos do sistema, e o utilizador com as bases de dados e de métodos, facilitando também o acesso a métodos que podem estar residentes na máquina, i.e. computador, do sistema ou distribuídos por vários servidores e acessíveis via Internet ou intranets. Sempre que haja necessidade de projectar SPOP e obter rapidamente soluções de configurações de SPOP o sistema poderá ser usado promovendo o processo de projecto e reconfiguração frequente do SPOP para melhorar a produtividade de empresas industriais através de melhores sistemas de produção.Leanness and agility are important requirements of manufacturing companies in the actual era of global economy and highly competitive variable markets. In a simplified view, it may be said that Lean Production and Agile Production are the strategic answers to these requirements. The first requires a good production systems fit to production requirements from raw materials to finished product delivery, aiming at minimizing waste of every kind and therefore exploring what has been known as JIT Production. The second calls for production systems agility for adaptation to variable production requirements derived from continuous changing on product demand variety and quantity. Apparently, both strategies focus on a common objective, namely that of quick manufacturing response to variable market requirements through a dynamic and suitable fit of the manufacturing system to the corresponding changing production requirements. This thesis suggests that such fit can be achieved through Product Oriented Manufacturing Systems (POMS) which in simple terms may be defined as reconfigurable manufacturing systems formed from sets of interlinked reconfigurable manufacturing cells for coordinated and synchronized fabrication of components and assembly of a product or a family of similar products to quick delivery to customers. Due to POMS design complexity it is proposed a design and reconfiguration methodology for POMS, referred as the GCD methodology because it deals with system design at three planning levels or phases, namely the strategic, referred as Generic, the Conceptual and the Detailed. The methodology guides the designer through these three phases, involving a set of interlinked successive design activities suggesting methods that may be used by a POMS designer to carry out each design activity. A set of important methods were collected for this. The use of the methodology is demonstrated through a POMS design application example. This work had to draw upon important concepts established in the literature and also put forward new ones, contributing, this way, for the ontological development of the scientific domain of the investigation. In particular it must be emphasized the concepts of conceptual and operational cells and also those of cell operating modes. In order to give a better utility to the methodology and facilitate de POMS design task a computer aided design systems for POMS, the CADS_POMS, has been proposed and specified, and a prototype of it developed. The system is structured around three main components a database, a methods’ design base and the SPOP designer. This intervenes in the interaction between CADS-POMS design components and is fundamental for design activities too be carried. The methods used for supporting the design activities can be either resident in the CADS_POMS or accessed, via Internet for example, from distributed servers where they are implemented. Whenever there is a need for POMS design and quickly obtain POMS configurations solutions the system can be used. This promotes the frequent POMS design and reconfiguration process in order to improve the productivity of the industrial companies through better production systems

A multi-agent based cell controller

Indexado ISIThis paper discusses the opportunity to use multiagents technology in automation and distributed manufacturing systems and the expected improvements. To support the discussion, it is described a manufacturing cell control application developed using the multi-agent technology, and the results are compared with other control application developed in the past by some of the authors, using a traditional approach, for the same flexible manufacturing cell