Supervisory Control Technique For An Assembly Workstation As A Dynamic Discrete Event System

This paper proposes a control problem statement in the framework of supervisory control technique for the assembly workstations. A desired behaviour of an assembly workstation is analysed. The behaviour of such a workstation is cyclic and some linguistic properties are established. In this paper, it is proposed an algorithm for the computation of the supremal controllable language of the closed system desired language. Copyright © 2001 IFAC

Survey on assembly sequencing: a combinatorial and geometrical perspective

A systematic overview on the subject of assembly sequencing is presented. Sequencing lies at the core of assembly planning, and variants include finding a feasible sequence—respecting the precedence constraints between the assembly operations—, or determining an optimal one according to one or several operational criteria. The different ways of representing the space of feasible assembly sequences are described, as well as the search and optimization algorithms that can be used. Geometry plays a fundamental role in devising the precedence constraints between assembly operations, and this is the subject of the second part of the survey, which treats also motion in contact in the context of the actual performance of assembly operations.Peer ReviewedPostprint (author’s final draft

Disassembly Planning and Costing Through Petri Net Approach

In the current consumer oriented environment, many new products appear in the market almost on a daily basis. Lured by advertisements and tempted by new product features, customers are constantly purchasing newer products. Acquiring newer products for often leads to throwing out older ones, but it is a totally different story for manufacturers. They need to consider the best way to reuse a product both for economic purposes and for environmental protection. Considerations for them often include: how to minimize total disassembly cost, how to achieve the lowest total disassembly time at each processing step, and how to sort valuable parts from hazardous parts as early as possible during the disassembly procedure. In this paper, we use a Disassembly Petri-Net (DPN) to generate the Disassembly Process Plan (DPP). This plan is a sequence of disassembly tasks from the initial stage of the whole product to the final stage where each part is separated from the other parts. This disassembly plan is very valuable for product recycling or remanufacturing. Prior to having the DPN, we apply an algorithm to generate a Disassembly Precedence Matrix (DPM) helped by the construction steps involved in SolidWorks™, a solid model software used to create the part in the first place. From the DPN, we find all feasible paths and generate the corresponding costs of disassembly based upon tool changes, changes in direction of the movement and individual part characteristics (e.g. hazardous components and recycle component). Cost data was extracted from previously published studies by Boothroyd et al. to obtain the handling time and disassembly time. Afterwards, we developed the optimal or near-optimal DPP for the best time and cost based disassembly options. In summary, this paper presents a systematic method to disassemble a part into its individual components and provides a cost figure for doing so. This is in contrast with many studies reported in the literature in that they concentrate either on a measure of disassembly complexity, or even if cost is presumably the driving force, their costs are arbitrary costs based on pre-selected values for such things as tool change penalty, disassembly direction change penalty or penalty for delaying removal of hazardous materials. In this paper, we are using disassembly times based on experimental work and/or industrial experience. Given the correct labor rate, our cost evaluation indeed yields a realistic cost value

Modeling, design and scheduling of computer integrated manufacturing and demanufacturing systems

This doctoral dissertation work aims to provide a discrete-event system-based methodology for design, implementation, and operation of flexible and agile manufacturing and demanufacturing systems. After a review of the current academic and industrial activities in these fields, a Virtual Production Lines (VPLs) design methodology is proposed to facilitate a Manufacturing Execution System integrated with a shop floor system. A case study on a back-end semiconductor line is performed to demonstrate that the proposed methodology is effective to increase system throughput and decrease tardiness. An adaptive algorithm is proposed to deal with the machine failure and maintenance. To minimize the environmental impacts caused by end-of-life or faulty products, this research addresses the fundamental design and implementation issues of an integrated flexible demanufacturing system (IFDS). In virtue of the success of the VPL design and differences between disassembly and assembly, a systematic approach is developed for disassembly line design. This thesis presents a novel disassembly planning and demanufacturing scheduling method for such a system. Case studies on the disassembly of personal computers are performed illustrating how the proposed approaches work

전략적 제품개발을 위한 아키텍처 관점의 접근법

학위논문 (박사)-- 서울대학교 대학원 : 협동과정 기술경영·경제·정책전공, 2014. 2. 홍유석.While traditional design research has concentrated on creativity from a clean sheet, however in practice many design projects have been conducted by the modification or incremental development of existing systems to meet new requirements and regulations. Indeed, Ab initio designing is rare, while many new product developments proceed by modifying existing products. Radical design, which begins from white paper, requires new knowledge that carries higher uncertainty and an increased risk of market failure, compared with existing knowledge. Although many enterprises expect more success from radical innovations, most new products only improve or modify existing products. Therefore, minimizing novelty to reduce risk and cost, by using tried and tested solutions and carried-over components, is a key objective. In many industries, more formal procedures for specifying tight and complex requirements are changing the nature of decision making in design processes. The present thesis defines incremental design as a process of modifying or redesigning an existing system while carrying over core competencies in order to meet the required incremental changes and propose the methodologies to established effective strategies for the incremental design. In order to success in incremental product development, it is primary to comprehensively understand the existing products architecture. On the foundation of the understanding, determination of the design targets and effective realization on physical domain should be systemically conducted. The product architecture is defined as the scheme by which the function of a product is allocated to physical components. Therefore, in the incremental design, the existing products architecture could be a design constraint for a new product. For determining design targets on the early stage of product development process, the proposed methodology figures out the interrelationships among functional elements, which specify the products tasks, and based on this, determines the consistent set of specifications that make a product satisfy new requirements. The determined specifications are implemented or realized with physical components on the physical domain. When the existing system incorporates new components in incremental design, reduced changes should be necessarily accompanied. Therefore, efficient rearrangement of the existing components with incorporating new components should be a key design strategy in incremental design. In order to determine a consistent set of design targets in incremental design, the proposed methodology defines the product architecture with specifications on the functional design domain and identifies the specifications that makes customers utility maximizethe design targets are specified with specifications. The methodology was practically developed based on new vehicle planning project, because it traditionally has been conducted in incremental manner, which relies solely on qualitative benchmarking analysis and intuitive human decisions. It has tried to capture the interplay between the important factors in preliminary vehicle design such as functional product architecture (design feasibility constraints), market demands, and economic conditions. The main contribution of the proposed research could read as showing how design information embedded in real data can be utilized in vehicle planning and determine a consistent set of design targets by coordinating those design information on moderate level. The determined design targets are implemented with physical components. When a new product is developed as based on an existing system but with new components, changing not only the components but also the entire architecture on physical domain is unavoidable. Therefore, this thesis proposes a methodology to re-architect an existing system that has modular architecture when new technologies are to be infused via a set of new components. The proposed method explicitly recognizes the existing system, as the foundation of the new system, focuses on the transformation of the existing architecture into the optimal architecture of the new system. Vast amount of prior research on designing modular systems or building product platforms have proposed numerous methodologies to determine the optimal architecture for developing new products, implicitly acknowledging the existence of the previous design. Although it is imperative to determine the goal of the new architecture, the paths of transformation, from the existing to the optimal architecture for a new system, can be exceedingly variedfurthermore, the optimal architecture itself should depend on the transformation path selected to meet the new requirements. Therefore, the method proposed in this paper models the transformation of an existing architecture by reflecting required changes. The present study determined the optimal architecture by consideration of the relevant transformation characteristics.Chapter 1. Introduction 1 1.1. Incremental design 1 1.2. Role of Product Architecture in Incremental design 5 1.3. Design strategies on the existing architecture 10 1.4. Structure of Thesis 12 Chapter 2. Literature Review 14 2.1 Determination of design targets on the early stage of development process 14 2.2 Product architecture 16 2.3 Architectural investigation in incremental design 19 Chapter 3. Data-driven Optimized Vehicle-level Engineering Specification 24 3.1. Introduction 25 3.2. Research overview 28 3.2.1 Data set 28 3.2.2 Design information and their interplay 30 3.3. Proposed approach: models and procedures 34 3.3.1 Building design constraints 34 3.3.2 Maximizing customer utility based on customer preferences 46 3.4 Model Validation 54 Chapter 4. Re-architecting modular systems in incremental design 57 4.1. Introduction 58 4.2. Methodology: Re-architecting through incremental design 61 4.2.1. Re-architecting Operators in Incremental Design 63 4.2.2. Determining optimal re-architecting strategy in incremental design 66 4.3. Case study: Hydrogen-fueled internal combustion engines 78 4.4. Summary 88 Chapter 5. A genetic algorithm for re-architecting in incremental design 90 5.1. Introduction 91 5.2. Surmounting combinational explosion of re-architecting problem 94 5.3. Module-configuration based encoding scheme 97 5.4. DSM utilized architectural fitness 100 5.5. Infeasible chromosome repair 107 5.5.1. Solution feasibility operator 108 5.5.2. Re-architecting feasibility operator 109 5.6. Bidirectional evolutionary algorithm 111 5.7. Application to hydrogen-fueled internal combustion engine 115 5.8. Summary 125 Chapter 6. Conclusions and Future Works 127 Bibliography 139 Appendix A 149Docto

End-of-Life Efficient Disassembly of Complex Structures Using Product and Process Focused Approach

RÉSUMÉ Le démantèlement durable des avions, contenant un nombre élevé de composants métalliques et non métalliques, devient, de nos jours, un problème de plus en plus urgent dans l’industrie aéronautique. Le désassemblage de la structure, en tant que principale tâche de cette procédure, a toujours été un défi considérable que ce soit en matière d’efforts requis qu’en termes de valeur économique apportée. Ce processus est, depuis toujours, apparu comme un service couteux et pas forcément écologique. La revue de la littérature indique que le désassemblage semi-destructif a des bénéfices significatifs contrairement à la destruction totale voir la non-destruction des appareils. Malgré un grand champ d’applications, à l’heure actuelle, il n’existe aucun moyen d’évaluer, indépendamment d’estimations subjectives, quantitativement l’effort nécessaire pour appliquer une telle méthode sur des structures métalliques complexes telles que celles d’un avion. Le but de cette thèse est donc, de développer une échelle d’évaluation à multiples variables afin de déterminer la performance de chaque opération avant de commencer le travail matériel. Ce modèle serait capable d’évaluer la facilité de désassembler la structure, et ce de manière quantitative, incorporant les aspects relatifs au produit ainsi qu’au procédé. Dans chacune de ces deux catégories (c’est à dire produit et procédé), différents facteurs déterminants, peuvent amener à un résultat économique, environnemental et /ou social décevant, s’ils ne sont pas pris en considération. C’est pourquoi cette méthode explore divers facteurs tels que le temps, la difficulté, la compatibilité des matériaux utilisés dans les pièces/modules de la structure afin que la stratégie choisie corresponde aux objectifs techniques, économiques, et environnementaux. Dans cette étude de cas, un stabilisateur horizontal provenant d’un appareil Bombardier CRJ series a été sélectionné afin d’évaluer la pertinence et l’efficacité de l’approche proposée. La partie expérimentale s’est appuyée sur des travaux pratiques de désassemblage établis sur une période de plus de deux ans, des analyses des documents de maintenance appartenant à cet avion, ainsi que des entretiens avec des spécialistes de ce domaine. Les résultats ont démontré que l’approche proposée est à la fois facilement réalisable, plus rapide et permet une meilleure récupération des matériaux en comparaison avec d’autres méthodes. Enfin, avec de tels avantages, ce procédé apporte une importante contribution dans le domaine du désassemblage de la structure puisqu'il est aisément exploitable par les sites de désassemblage, pour les fabricants et propriétaires d'avions.----------ABSTRACT Sustainable decommissioning of aircraft with a high content of metallic and non-metallic components is becoming an urgent issue in today’s aviation industry. Airframe disassembly, as a principal step in this procedure, has always been a challenge in terms of the required effort and regained values. This process has historically appeared to be economically costly, socially unviable, and not necessarily environmentally benign. Literature indicates that, unlike entirely destructive and totally non-destructive techniques, semi-destructive disassembly may bring significant benefits. However, despite their use in a wide variety of applications, there are currently no feasible solutions on how to measure the associated physical difficulties and required efforts without any dependencies on expert views or filling out spreadsheet-like forms. The purpose of this dissertation is then to develop a multiple-variable model in order to determine the performance of each disassembly operation prior to the physical work. The model could accurately evaluate the disassembly easiness of an airframe quantitatively incorporating both product and process features. There are various driving factors in each of these categories (i.e., process and product features) that failing to appropriately address them could result in either significant economic loss, environmental and/or social inconvenience. The methodology used in this study is one of the first investigations in this field, known as a Multivariable Disassembly Evaluator (MDE). It explores 1- time; 2- difficulty; and 3- material compatibility of the airframe parts/modules to ensure that the defined disassembly strategies meet technical, economic and environmental objectives. A horizontal stabilizer of Bombardier CRJ series was selected as a case study to provide a detailed vision of disassembly evaluating the suitability and effectiveness of the proposed approach. The experimental investigations are based upon the real disassembly works for over two years, aircraft maintenance documentation analysis and discussions with technical domain specialists. The findings demonstrated that the proposed method is easier to fulfil, faster and allows the user to gain more recovery than other current approaches. These advantages should make an important contribution to the field of airframe disassembly since they can be readily used by disassembly sites, aircraft owners and manufacturers

Outils d'aide à la décision pour la sélection des filières de valorisation des produits de la déconstruction des systèmes en fin de vie : application au domaine aéronautique

Dans un contexte de développement durable, les enjeux de la dernière phase du cycle de vie d'un système, la phase de retrait de service, se sont accrus ces dernières années. Les systèmes en fin de vie doivent être déconstruits afin d'être revalorisés pour répondre aux différentes exigences environnementales. Cette responsabilité incombe au concepteur qui doit définir le sous-système support de la phase de retrait de service : le système de déconstruction. Sa principale fonction est la réalisation de l'activité de déconstruction dans l'objectif de favoriser en aval le recyclage de la matière des constituants du système en fin de vie et/ou leur recyclage fonctionnel. Les stratégies de déconstruction doivent répondre à l'ensemble des problèmes de décision posés lors de la phase de retrait de service d'un système. Il s'agit notamment de sélectionner les constituants valorisables suivant des critères techniques, économiques et environnementaux puis de définir et optimiser le système de déconstruction permettant l'obtention de ces produits. La solution obtenue définie ce que nous avons appelé une trajectoire de déconstruction. Nos travaux portent sur la modélisation et l'optimisation de ces trajectoires. Nos développements s'articulent en quatre phases. Etat de l'art et démarche de définition d'une trajectoire. Dans cette phase, une structure de démarche de définition de trajectoires de déconstruction est proposée puis instrumentée. Les modèles généralement utilisés dans ce cadre sont de type déterministe et ne permettent pas de prendre en compte et de gérer les incertitudes inhérentes au processus de déconstruction (état dégradé du système en fin de vie et de ses constituants, demandes en produits issus de la déconstruction, dates de fin de vie des systèmes, …). Pour déterminer une solution robuste de déconstruction d'un système en fin de vie, l'aide à la décision proposée doit intégrer des incertitudes de nature diverse tout en facilitant leur gestion et leurs mises à jour. Incertitudes en déconstruction. Sur la base de ce constat, l'ensemble d'incertitudes couramment mises en jeu dans l'optimisation des trajectoires est identifié et caractérisé. Les méthodes probabilistes apparaissent comme des approches privilégiées pour intégrer ces incertitudes dans une démarche d'aide la décision. Les réseaux bayésiens et leur extension aux diagrammes d'influence sont proposés pour répondre à différents problèmes de décision posés lors de la définition d'une trajectoire de déconstruction. Ils servent de support au développement d'un outil d'aide à la décision. Modélisation de trajectoires de déconstruction : principes et approche statique d'optimisation. Après avoir présenté ses principes de modélisation, l'outil est développé dans une approche de détermination d'une trajectoire de déconstruction d'un système en fin de vie donné. La trajectoire obtenue fixe la profondeur de déconstruction, les options de revalorisation, les séquences et les modes de déconstruction suivant des critères économiques et environnementaux tout en permettant de gérer différents types d'incertitude. L'utilisation de critères économiques est ici privilégiée. Un exemple d'application sur un système aéronautique est développé pour illustrer les principes de modélisation. Approche dynamique pour l'optimisation d'une trajectoire de déconstruction. Le champ d'application de l'outil d'aide à la décision est étendu en intégrant une dimension temporelle à la modélisation du problème à l'aide des réseaux bayésiens dynamiques. Les trajectoires de déconstruction peuvent ainsi être établies sur des horizons couvrant les arrivées de plusieurs systèmes en fin de vie en présence d'incertitudes. Le modèle permet de déterminer des politiques de déconstruction pour chaque opération identifiée dans la trajectoire en fonction de différents paramètres liés à la gestion des demandes et des arrivées ou encore au processus d'obtention de ces produits. Le décideur peut ainsi adapter l'outil à différents contextes de détermination de trajectoire de déconstruction de systèmes en fin de vie