Extended Production Planning of Reconfigurable Manufacturing Systems by Means of Simulation-based Optimization

Reconfigurable manufacturing systems (RMS) are capable of adjusting their operating point to the requirements of current customer demand with high degrees of freedom. In light of recent events, such as the covid crisis or the chip crisis, this reconfigurability proves to be crucial for efficient manufacturing of goods. Reconfigurability aims thereby not only at adjust production capacities but also for fast integration of new product variants or technologies. However, the operation of such systems is linked to high efforts concerning manual work in production planning and control. Simulation-based optimization provides the possibility to automate processes in production planning and control with the advantage of relying on mostly existing models such as material flow simulations. This paper studies the capabilities of the meta heuristics evolutionary algorithm, linear annealing and tabu search to automate the search for optimal production reconfiguration strategies. Two distinct use cases are regarded: an increase of customer demand and the introduction of a previously unknown product variant. A parametrized material flow simulation is used as function approximator for the optimizers, whereby the production system's structure as well as logic are target variables of the optimizers. The analysis shows that meta-heuristics find good solutions in a short time with only little manual configuration needed. Thus, metaheuristics illustrate the potential to automate the production planning of RMS. However, the results indicate that the performance of the three meta-heuristics considering optimization quality and speed differs strongly

CFD modeling in Industry 4.0: New perspectives for smart factories

Abstract Industrial market is becoming increasingly competitive and companies need even more advanced resources to advantage over competitors. As an example, simulation is part of Industry 4.0 technologies and a key tool for lay out re-configuration, in order to realize a flexible product customization but also to optimize manufacturing processes. For these reasons Computational Fluid Dynamics (CFD) simulation can determine a competitive advantage for smart factories in the light of possibilities offered by new technologies. The research is focused on a conceptual solution to integrate CFD simulation with technologies of the Industry 4.0, in order to open new opportunities for companies in terms of in terms of growth and competitiveness

A general inspection and opportunistic replacement policy for one-component systems of variable quality

We model the influence of opportunities in a hybrid inspection and replacement policy. The base policy has two phases: an initial inspection phase in which the system is replaced if found defective; and a later wear-out phase that terminates with replacement and during which there is no inspection. The efficacy of inspection is modelled using the delay time concept. Onto this base model, we introduce events that arise at random and offer opportunities for cost-efficient replacement, and we investigate the efficacy of additional opportunistic replacements within the policy. Furthermore, replacements are considered to be heterogeneous and of variable quality. This is a natural policy for heterogeneous systems. Our analysis suggests that a policy extension that allows opportunities to be utilised offers benefit, in terms of cost-efficiency. This benefit is significant compared to those offered by age-based inspection or preventive replacement. In addition, opportunistic replacement may simplify maintenance planning

Integrated Assessment of Assembly fixtures Re-configurability

The needs of consumers are changing over time. As a result, the manufacturers are looking for new methods to adapt effectively and efficiently to market changes. These involve supplying customers with a variety of products in a reasonable time with decreasing the cost. Reconfigurable fixtures are an important means for dealing with increased product variety and shorter life cycles, as they help change between the product variants effectively and decrease the time and resources required to introduce new product variants. In this thesis, an integrated method to assess the reconfigurability of assembly fixtures is developed. This assessment is based on four core reconfigurability characteristics: scalability, modularity, convertibility, and customized flexibility. A clear definition of the scalability of the reconfigurable assembly fixtures was developed. A mathematical model for each characteristic of reconfigurable assembly fixtures was developed. Their indices were determined then combined using a radar plot to assess the reconfigurability of the reconfigurable assembly fixture. Welding tack fixture is chosen as a case study in this thesis. Two redesign recommendations were proposed. The results showed the most appropriate design with highest reconfigurability index because it was designed to produce the same number of product variants with less reconfiguration time, cost, effort, and complexity. The significance of research in this thesis is to help in the design stage of the assembly fixture by comparing different configurations for the assembly fixture to choose the best one and suggesting some changes for the assembly fixture design and configuration. This is essential to minimize the number of fixtures to be produced when the new part component/ variant is introduced

Sistema de control reconfigurable y sostenible para aplicación en sistemas de manufactura flexibles

Dado el continuo y acelerado crecimiento de la economía global, la producción mundial se ha visto afectada por un incremento significativo de recursos y energía. Este incremento ha traído diversos avances tecnológicos y digitales en el sector industrial que han evolucionado el área de sistemas de control reconfigurables. Específicamente, esta nueva tecnología ha surgido para dar respuesta a la volatilidad de sistemas de manufactura y satisfacer niveles adecuados de efectividad y reactividad. Sin embargo, los sistemas enfrentan el reto de generar un balance entre sus indicadores. En las últimas décadas, se ha visto la necesidad de incluir la sostenibilidad como una nueva métrica de eficiencia para los sistemas de manufactura. Igualmente, existe la necesidad mundial de incorporar la sostenibilidad en las operaciones industriales y se evidencia una falta de estudios en la integración entre productividad y sostenibilidad. Por esta razón, este trabajo de investigación propone un sistema de control con una arquitectura que hace el balance de eficiencia y efectividad entre indicadores de productividad y sostenibilidad. Dicho sistema propuesto consta de una arquitectura compuesta por distintos tipos de entidades. Así mismo, la propuesta también incluye un mecanismo de reconfiguración compuesto por tres módulos. Para mostrar los beneficios del sistema propuesto, se presenta la validación mediante la realización de experimentos en un ambiente simulado haciendo uso del software basado en agentes denominado Netlogo. Se evalúa la aplicación en un sistema de manufactura real ubicado en Francia. Como resultados, se evidencia que sí es posible integrar eficiencia y efectividad en un sistema de control. Esto mejora el desempeño de la energía hasta en un 69% y el del tiempo en 30%.Given the continuous and accelerated growth of the global economy, world production has been affected by a significant increase in resources and energy. This increase has brought several technological and digital advances in the industrial sector that have evolved the area of reconfigurable control systems. Specifically, this new technology has emerged to respond to the volatility of manufacturing systems and meet adequate levels of accuracy and reactivity. However, these systems lack of generating a balance between their indicators. In recent decades, the need to include sustainability as a new efficiency metric for manufacturing systems has grown. Similarly, there is a worldwide need to incorporate sustainability in industrial operations and there is a lack of studies on the integration between productivity and sustainability. For this reason, this work proposes a control system with an architecture that balances efficiency and effectiveness between productivity and sustainability indicators. This proposed system consists of an architecture composed of different types of entities. Likewise, the proposal also includes a reconfiguration mechanism composed of three modules. To show the benefits of the proposed system, validation is presented by conducting experiments in a simulated environment using an agent-based software known as Netlogo. The application is evaluated in a real manufacturing system located in France As a result, it is evident that it is possible to integrate efficiency and effectiveness into a control. This improves energy efficiency by up to 69% and processing time by 30%.Magíster en Ingeniería IndustrialMaestrí

Factories of the Future

Engineering; Industrial engineering; Production engineerin

Achieving Autonomic Computing through the Use of Variability Models at Run-time

Increasingly, software needs to dynamically adapt its behavior at run-time in response to changing conditions in the supporting computing infrastructure and in the surrounding physical environment. Adaptability is emerging as a necessary underlying capability, particularly for highly dynamic systems such as context-aware or ubiquitous systems. By automating tasks such as installation, adaptation, or healing, Autonomic Computing envisions computing environments that evolve without the need for human intervention. Even though there is a fair amount of work on architectures and their theoretical design, Autonomic Computing was criticised as being a \hype topic" because very little of it has been implemented fully. Furthermore, given that the autonomic system must change states at runtime and that some of those states may emerge and are much less deterministic, there is a great challenge to provide new guidelines, techniques and tools to help autonomic system development. This thesis shows that building up on the central ideas of Model Driven Development (Models as rst-order citizens) and Software Product Lines (Variability Management) can play a signi cant role as we move towards implementing the key self-management properties associated with autonomic computing. The presented approach encompass systems that are capable of modifying their own behavior with respect to changes in their operating environment, by using variability models as if they were the policies that drive the system's autonomic recon guration at runtime. Under a set of recon guration commands, the components that make up the architecture dynamically cooperate to change the con guration of the architecture to a new con guration. This work also provides the implementation of a Model-Based Recon guration Engine (MoRE) to blend the above ideas. Given a context event, MoRE queries the variability models to determine how the system should evolve, and then it provides the mechanisms for modifying the system.Cetina Englada, C. (2010). Achieving Autonomic Computing through the Use of Variability Models at Run-time [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7484Palanci

Delay-time modelling of a critical system subject to random inspections

We model the inspection-maintenance of a critical system in which the execution of inspections is random. The models we develop are interesting because they mimic realities in which production is prioritised over maintenance, so that inspections might be impeded or they might be opportunistic. Random maintenance has been modelled by others but there is little in the literature that relates to inspection of a critical system. We suppose that the critical system can be good, defective or failed, and that failure impacts on production, so that a failure is immediately revealed, but a defect does not. A defect, if revealed at inspection, is a trigger for replacement. We compare the cost and reliability of random inspections with scheduled periodic inspections and discuss the implications for practice. Our results indicate that inspections that are performed opportunistically rather than scheduled periodically may offer an economic advantage provided opportunities are sufficiently frequent and convenient. A hybrid inspection and replacement policy, with inspections subject to impediments, is robust to departure from its inspection schedule. Keywords: Maintenance; reliability; random inspection; production; qualit

Factories of the Future

Engineering; Industrial engineering; Production engineerin