Browsing by Author "Rodrigues, Nelson"
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- Adaptation of functional inspection test plan in a production line using a multi-agent systemPublication . Rodrigues, Nelson; Leitão, Paulo; Foehr, Matthias; Turrin, Claudio; Pagani, Arnaldo; Decesari, RobertoThe multi-agent systems technology is a proper approach to implement distributed manufacturing systems exhibiting adaptation and flexibility. This paper proposes a multi-agent based solution for the adaptation of the functional test plan in a production line producing washing machines, aiming to increase the process productivity and product quality. The global adaptation mechanism is embedded on the multiagent system infrastructure, allowing the optimized selection of tests based on the correlation of the quality data gathered along the production line. The proposed approach was developed and installed on a real production line producing washing machines under the European Seventh Framework Programme GRACE project.
- Adaptive multi-agent system for a washing machine production linePublication . Rodrigues, Nelson; Pereira, Arnaldo; Leitão, PauloThis paper describes the implementation of a multi-agent system in a real industrial washing machine production line aiming to integrate process and quality control, allowing the establishment of feedback control loops to support adaptation facing condition changes. For this purpose, the agent-based solution was implemented using the JADE framework, being the shared knowledge structured using a proper ontology, edited and validated in Protégé and posteriorly integrated in the multi-agent system. The solution was intensively tested using historical real production data and it is now being installed in the real production line. The preliminary results confirm the initial expectations in terms of improvement of process performance and product quality.
- Adaptive services reconfiguration in manufacturing environments using a multi-agent system approachPublication . Rodrigues, Nelson; Leitão, Paulo; Oliveira, EugénioThe era of mass customization of goods forces manufacturing systems to promote agility, flexibility and responsiveness, leading to complex and unpredictable systems. Such challenges have an impact in terms of the system responsiveness and adaptation, production costs, product quality, etc. In order to improve those aspects, some flexible control manufacturing paradigms were proposed offering elasticity to change available skills and provide new services. However, the understanding of when and how to (self-) reconfigure the system aiming to perform a fast changeover, is a crucial issue. This work proposes a self-organizing multi-agent system approach for an efficient and on the fly reconfiguration of services in the manufacturing domain. Besides self-organizing techniques, other dimensions, e.g., “social-based” trust and QoS metrics, are used to ensure a constant QoS in an agile production system. The insertion of intelligent agents facilitates the improvement of strategies that perform the service reconfiguration, and in addition, permits to understand when and how self-reconfiguration takes place in order to allow a continuous improvement of the system performance. Additionally, this work addresses solutions for real industrial applications, being aligned with some characteristics of the Industrie 4.0 initiative, namely the distributed intelligence and self-* methods, e.g. self-adaptation, self-organization and self-configuration
- An agent-based approach for the dynamic and decentralized service reconfiguration in collaborative production scenariosPublication . Rodrigues, Nelson; Leitão, Paulo; Oliveira, EugénioFuture industrial systems endorse the implementation of innovative paradigms addressing the continuous flexibility, reconfiguration, and evolution to face the volatility of dynamic markets demanding complex and customized products. Smart manufacturing relies on the capability to adapt and evolve to face changes, particularly by identifying, on-the-fly, opportunities to reconfigure its behavior and functionalities and offer new and more adapted services. This paper introduces an agent-based approach for service reconfiguration that allows the identification of the opportunities for reconfiguration in a pro-active and dynamic manner, and the implementation on-the-fly of the best strategies for the service reconfiguration that will lead to a better production efficiency. The developed prototype for a flexible manufacturing system case study allowed to verify the feasibility of greedy local service reconfiguration for competitive and collaborative industrial automation situations.
- Data collection for global monitoring and trend analysis in the GRACE multi-agent systemPublication . Pereira, Arnaldo; Rodrigues, Nelson; Leitão, PauloMulti-agent systems (MAS) paradigm is a suitable approach to implement distributed manufacturing systems addressing the emergent requirements of flexibility, robustness and responsiveness. In such systems, the distributed agents have a local view of the system environment being the global data collection a complex and critical issue to provide the functionalities of the ISA-95 standard, such as dynamic scheduling, maintenance management and quality assurance. This paper describes the data collection mechanisms in a multiagent system that supports the global monitoring over the time and the trend analysis to perform self-adaptation and selfoptimization. The proposed approach was developed and tested in an industrial washing machines production line.
- Decentralized and on-the-fly agent-based service reconfiguration in manufacturing systemsPublication . Rodrigues, Nelson; Oliveira, Eugénio; Leitão, PauloIntelligent manufacturing systems rely on the capability to adapt and evolve to face the volatility of dynamic markets. The complexity of these systems increases with the demand of more customized and quality products, which requires more agile and flexible methods to support the dynamic and on-the-fly system reconfiguration aiming to respond quickly to product changes, by offering more efficient services. In this service-oriented manufacturing context, where process functionalities are modelled as services (e.g., quality control, welding and transportation), the dynamic reconfiguration of the services structure (e.g., in terms of quality, processing time and provided features) assumes a critical role to achieve the referred requirements. Despite the current research efforts, the service reconfiguration approaches usually use reactive event triggers, with decisions coming from a centralized decision-maker and performed manually. This means a lack of dynamic and run-time reconfiguration flexibility by discovering opportunities and needs to change, and, thus, exploring possible actions leading to new and appropriate system configurations. To overcome the mentioned issues, it is essential to provide solutions that answer to when and how to reconfigure a manufacturing system in an integrated, automatic and dynamic manner. For this purpose, this paper introduces an agent-based approach for service reconfiguration in manufacturing systems that allows the identification of opportunities in a pro-active and dynamic manner, and the on-the-fly implementation of new configuration solutions leading to a better production efficiency. The experimental results, using a flexible manufacturing system case study, allowed to verify the feasibility and benefits of the proposed agent-based service reconfiguration solution for competitive and collaborative industrial automation scenarios.
- Deployment of multi-agent systems for industrial applicationsPublication . Pereira, Arnaldo; Rodrigues, Nelson; Leitão, PauloMulti-agent system (MAS) is being pointed out as a suitable technology to develop systems that demand flexibility, robustness and re-configurability. Consequently, a significant effort has been noticed to apply MAS to industrial domains exhibiting these characteristics, like manufacturing and smart grids. In spite of the adequacy of the MAS principles to solve the industrial requirements, the truly deployment of MAS for industrial applications is far to be solved. This paper discusses the current challenges for the deployment of MAS in the context of industrial applications, mainly focusing the integration of agents with physical equipment and the ability to run agents directly in industrial or low cost controllers. An experimental MAS solution for a smart grid case study was deployed aiming to support the discussion.
- Development of an ontology for a multi-agent system controlling a production linePublication . Rodrigues, Nelson; Leitão, PauloNowadays, the industry is very demanding in terms of customized high quality products at lower costs. Furthermore, the customers intention of having the product as soon as possible, and companies having the restriction of time, which in this case is a crucial variable, also increases the nal product cost. For this reason, it becomes unacceptable the development of solutions based on centralized implementations, which do not provide robustness, exibility and recon gurability. Therefore, the implementation of multi-agent based solutions ful l the described requirements leading to a more exible, robust and agile system. This work presents the development of an important issue concerning the cooperation between the distributed agents, since one of them only has a partial view of the system. In this way the ontologies are crucial to guarantee a common structure of the knowledge exchanged among the agents. The objective of this work is the development of an ontology integrating process and quality levels to be used to represent the knowledge exchanged in a multi-agent system solution for a production line producing washing machines. Consequently, the agents exchanging shared knowledge will support better and more accurate decisions. The contribution of this work comprises the implementation of a multi-agent system, the appropriate ontology formulation as well as its implementation, which makes the integration of an industrial production line more versatile and more customized. Naturally, with this project, it is created a recon gurable and highly interoperable system. Hoje em dia, a indústria é muito exigente em termos de produtos personalizados de alta qualidade a custos baixos. Além disso, a intenção dos clientes é ter o produto logo que possível, assim as empresas têm uma limitação de tempo, que neste caso é uma variável importante, também aumenta o custo do produto nal. Por esta razão, torna-se inaceitável o desenvolvimento de soluções baseadas em implementa ções centralizadas, que não proporcionam a exibilidade, robustez e recon gurabilidade. Portanto, a implementação de soluções baseadas em multi-agente cumprem os requisitos descritos levando a um sistema mais exível, robusto e ágil. Este trabalho representa o desenvolvimento de uma questão importante relativa à coopera ção entre os agentes distribuídos, uma vez que apenas um deles tem uma visão parcial do sistema. Desta forma, as ontologias são cruciais para garantir uma estrutura comum de conhecimento trocadas entre os agentes. O objectivo deste trabalho é o desenvolvimento de uma ontologia da integração de processos e qualidade a serem utilizados para representar o conhecimento trocado em uma solução de sistema multi-agente para uma linha de produção de máquinas de lavar. Consequentemente, os agentes trocam conhecimento compartilhado que irão suportar decisões melhores e mais precisas. A contribuição deste trabalho consiste na implementação de um sistema multi-agente, a adequada formulação da ontologia, bem como a sua implementação, o que torna a integração de uma linha de produção industrial mais versátil e mais personalizada. Naturalmente, com este projecto, é criado um sistema recon gurável e altamente interoperável.
- Dynamic composition of service oriented multi-agent system in self-organized environmentsPublication . Rodrigues, Nelson; Leitão, Paulo; Oliveira, EugénioThe increasing relevance of complex systems in dynamic environments has received special attention from researchers during the last decade. Due to the need of a flexible and quick response to the clients' requirements, such systems become an important challenge. In this paper, self-organizing mechanisms capable to compose services in an automatic, flexible and decentralized manner are presented, mostly in which their adaptive behavior is concerned. Due to the distributed approach, we also investigate the adaptation regarding the structure of each entity. We thus propose an innovative self-learning mechanism that allows the distributed entities to learn structural relations allowing the system's evolution. This hypothesis were explored and validated by implementing a multi-agent system, in accordance with trust mechanisms to improve the interaction of agents. The achieved results show the correct agent's states in which the agents must evolve and self-organize, improving the system benefits band increasing the organization performance.
- Dynamic service reconfiguration with multi-agent systemsPublication . Rodrigues, Nelson; Leitão, Paulo; Oliveira, Eugénio; Rodrigues N.Most modern manufacturing systems rely on constantly seeking new solutions to better fulfil their manufacturing objectives. As reported in today’s manufacturing literature, dynamic service reconfiguration is one solution that permits to endorse continuous service reconfiguration, flexibility and evolvable systems. In spite of the current research efforts, real reconfiguration solutions are still lacking automated tools that support dynamic and runtime reconfigurations by discovering new adaptation needs and opportunities and, thus, explore possible actions leading to new system configurations. To overcome these issues, it is essential to provide solutions that answer to the “when” and “what” to reconfigure questions. Most of the service changes triggers rely on reactive events, where decisions come from a centralized decision-maker and are performed manually. Based on these facts a service-oriented multi-agent systems architecture is described aiming at actively promoting service reconfiguration (e.g., improvement of the service’s properties and/or update the services’ catalogue) to cope with the unexpected and unpredictable condition changes. This paper describes the processes that decide which service reconfiguration should be applied to each circumstance. The developed prototype for a flexible manufacturing system case study allowed verifying the feasibility of the proposed dynamic service reconfiguration solution in different scenarios.
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