Search

The adoption of digital technologies in manufacturing enables intelligent dynamic control approaches, at the cost of increased design complexity. In this paper, ontologies and delta-lenses are exploited to enable multi-scale models of a manufacturing system to map digital models at different scales and let data flow according to the level of fidelity. A workflow is designed to assess the capability of models with a lower level of details to approximate the behaviour of the original system, through the application of a hybrid delta-lens. The approach is illustrated with a user case and applied to an industrial case, aiming at deciding the positions of sensors in an assembly line. [ABSTRACT FROM AUTHOR]

Product customization is becoming a competitiveness factor in most markets. It implies manufacturing small and varied batches in mixed-product assembly lines and frequently supplying parts to production lines in small quantities with high efficiency. The in-plant milk-run is a specific tool used in this context. This paper proposes an industry-validated design method for human-driven milk-runs, based on improving surface productivity. A mathematical model is defined for relating mizusumashi work time to the milk-run period and finding its minimum value. This research is particularly useful in factories with high cost per m2 supplying high-volume parts. [ABSTRACT FROM AUTHOR]

Human-robot collaboration represents a significant evolutionary step in manufacturing. A crucial point is to establish a proper task assignment to combine robot productivity with human flexibility. In this regard, this paper proposes a genetic algorithm to approach the Assembly Line Balancing Problem (ALBP) in the case of human-robot collaborative work. The aim is the minimization of: i) the assembly line cost, evaluated according to the number of workers and equipment on the line, including collaborative robots, ii) the number of skilled workers on the line, iii) the energy load variance among workers, based on their energy expenditures and thus on their physical capabilities and on the level of collaboration with robots. [ABSTRACT FROM AUTHOR]

When designing production lines, a series of complex, interdependent phases need to be considered. These phases include the facility layout design, the allocation of tasks to available resources, the workload balancing as well as the validation of the proposed design against demand. This paper addresses all these phases in an integrated way, with the aim of reducing the overall time required to finalise the layout and production line design, while improving the overall performance of the manufacturing system under process and demand uncertainty, utilising a sophisticated, simulation-based software framework. The proposed approach is demonstrated using a realistic case scenario. [ABSTRACT FROM AUTHOR]

The paper proposes a generic approach to assembly planning where individual tasks, with detailed technological content specified by features, must be combined into an optimal assembly plan subject to technological and geometric constraints. To cope with the complexity and variety of the constraints that refer to the overall assembly process, Benders decomposition is applied. The macro-level master problem looks for the optimal sequencing and resource assignment of the tasks, while sub-problem modules ensure plan feasibility on the micro-level from aspects of technology, fixturing, tooling, and collision. Constraints are also dynamically generated for the master problem. The approach is demonstrated in automotive assembly. [ABSTRACT FROM AUTHOR]

This paper discusses a flexible assembly cell, including a dual arm robot in cooperation with humans for assembly tasks typically performed by operators. The robot performs these tasks both in isolation and cooperation with the human. Sensor data are used for programming the robot’s motion and controlling the program’s execution in a fenceless setup. Safety is ensured with the use of 3D sensing devices, while the tasks’ coordination is managed by the so-called station controller. The programming approach combines both offline and on-line methods, in an intuitive manner. The proposed assembly cell is demonstrated in an automotive industry case. [ABSTRACT FROM AUTHOR]

Automotive suppliers are facing the challenge of continuously adapting their production targets to variable demand requirements due to the frequent introduction of new model variants, materials and assembly technologies. In this context, the profitable management of the product, process and system co-evolution is of paramount importance for the company competitiveness. In this paper, a methodology for the design and reconfiguration management of modular assembly systems is proposed. It addresses the selection of the technological modules, their integration in the assembly cell, and the reconfiguration policies to handle volume and lot size variability. The results are demonstrated in a real automotive case study. [ABSTRACT FROM AUTHOR]

Introducing a synchronized flow by batching customized orders has proven an approach well-suited to enhancing the performance of individual production. Thus a new class of companies can benefit from concepts, such as the pull-principle, which as of yet has been exclusive to series-production. A critical step in this context is the allocation of orders with varying processing-sequences to a given network of production-lines. In this paper a multi-objective branch-and-bound approach is presented, which provides a set of Pareto-optimal allocations per order, taking logistic-effort and throughput-time into consideration. The presented optimization is validated and its effect on real-world production-performance is evaluated. [ABSTRACT FROM AUTHOR]

Production of complex and large-dimensioned goods in small lot sizes is a demanding task. In order to react to varying customer demand and changing product specifications assembly tasks are executed manually by skilled workers that provide an adequate level of flexibility. Although the task of controlling these assembly processes gets more complex, only little support is given to foreman and production planers in this regard. Existing procedures focus on production planning rather than control of processes. Thus, an assembly control procedure is developed that enables the integration of workers in control of paced assembly processes and a situation specific reallocation of personnel. Foreman and production planers are relieved from time consuming tasks of operational assembly control. The paper describes the approach and experimental results of its application. [ABSTRACT FROM AUTHOR]

Remote laser welding (RLW) has received increased attention in the recent years due to its benefits in terms of processing speed, lower investment, cost per stitch, and process flexibility. However, its potential in automotive assembly remains under exploited, mainly due to challenges involving system, process and fixture design, and part variation challenges. In this paper, an integrated rapid deployment framework for RLW process is proposed to improve ‘ right-first-time ’ implementation of RLW in assembly systems. It enables closed-loop optimization of system layout, task assignment, fixture layout, process parameters, robot path planning and programming as an interlinked iterative approach. The results are demonstrated in an automotive door assembly pilot study. [ABSTRACT FROM AUTHOR]

This paper proposes a novel methodology to optimize heterogeneous design tasks with competing parameters. It is based on the principle of design parameter sensitivity, taking into account the notion of robustness at an early phase of process design. The aim is to improve the quality of the assembly system in order to make it less sensitive to variations/changes of design parameters. The methodology is based on the development of: (i) analytical design task function; (ii) inner- and outer-sensitivity; (iii) design parameter sensitivity; and (iv) decision making module. The methodology is demonstrated using results involving an automotive door assembly. [ABSTRACT FROM AUTHOR]

Abstract: Due to the increasing pressure on high precision manufacturing and the development of on-line measurement technologies, selective and adaptive assembly systems have attracted increasing interest in emerging sectors such as micro-production, biomedical and e-mobility industry. Selective assembly allows producing high precision assemblies from low precision components, at the cost of increasing the complexity of the system. This paper presents an integrated quality and production logistics model to profitably manage this trade-off. Results show that improved performance is achieved towards existing solutions, which deal only with quality aspects. The industrial benefits are shown through application to real manufacturing contexts. [Copyright &y& Elsevier]

Abstract: Managing changes and disturbances resulted by fluctuating order streams and diverse product portfolios requires efficient capacity management decisions and production planning strategies. High volume products can be produced cost efficiently on dedicated assembly lines, while the assembly of low runners is more efficient on reconfigurable lines. In the paper a hierarchical planning decision workflow is introduced to assign the products to dedicated and reconfigurable lines, and to optimize the system configuration and the production plan of the reconfigurable system in an integrated way. The proposed solution is demonstrated through the results of an industrial case study. [Copyright &y& Elsevier]

Abstract: This paper proposes an approach to the design and operation of assembly systems that include mobile robots. It is based on a semantic model representing the robot/resource skills along with the operations that a resource has to execute. The method is implemented in a system capable of generating the assignment of operations to the proper robotic resources. Collision free paths can be generated for the assembly system robots with the help of simulation. The method is presented in a case study from the automotive industry. [Copyright &y& Elsevier]

Abstract: A disassembly process is usually characterized by a high level of uncertainty due to the quality of End-of-Life products. This paper presents an efficient approach for designing disassembly lines with the objective to maximize the line profit. Task times are assumed to be random variables with known probability distributions. An AND/OR graph is used to model the precedence relationships among tasks and subassemblies and the disassembly alternatives. A Monte Carlo sampling based exact solution method is developed to deal with uncertainties. Results of experiments on problem instances are presented. [Copyright &y& Elsevier]

Abstract: A main reason for the high costs of lithium-ion cells is the complexity of the assembly process. Especially, creating the cell stack is an inefficient process due to an immature handling and aligning of the limp electrodes and separators. This paper focuses therefore on the methodical development of a functionally integrated assembly module that combines cutting and handling of electrode sheets to increase stacking accuracy, process reliability and productivity. Based on an analysis of requirements and functions, a technical solution has been identified and will be illustrated. At the end, the realized module is described and its performance is proven by experimental validation. [Copyright &y& Elsevier]

Abstract: In an advanced production line including cold surface hardening, martensitic transformation in metastable austenites as workpiece material was achieved by deep rolling. The deep rolling process replaces energy- and cost-intensive heat treatments. Cryogenic deep rolling is a novel approach to combine two different sources of energy (thermal and mechanical effects) and thereby allows for application of more stable microstructures. This comes along with advantages regarding soft machining and the stability of the core material during a component''s functional loading. This paper presents the theoretical background, suitable parameters, and the resulting surface integrity of cryogenic deep rolled components and gives clear recommendations for industrial application. [Copyright &y& Elsevier]

Abstract: Design verification in the digital domain, using model-based principles, is a key research objective to address the industrial requirement for reduced physical testing and prototyping. For complex assemblies, the verification of design and the associated production methods is currently fragmented, prolonged and sub-optimal, as it uses digital and physical verification stages that are deployed in a sequential manner using multiple systems. This paper describes a novel, hybrid design verification methodology that integrates model-based variability analysis with measurement data of assemblies, in order to reduce simulation uncertainty and allow early design verification from the perspective of satisfying key assembly criteria. [Copyright &y& Elsevier]

Abstract: Dual-arm robots provide efficient approach for automated execution of complex assembly operations. With bimanual-manipulation, a dual-arm robot can simultaneously control relative motion and interaction of assembly counterparts in a dexterous human-like manner. This requires, however, sophisticated programming and control algorithms for arms cooperation. This paper addresses the development of an advanced industrial dual-arm robot system with novel capabilities, such as easy and rapid commissioning, compliance control of bimanual interaction in all assembly process phases, as well as intuitive planning and programming. The robot can be leased and easily integrated in assembly environment sharing the same workspace with human workers. [Copyright &y& Elsevier]

Abstract: This paper presents a method implemented in a web based tool able to generate job rotation schedules for human based assembly systems. Through a user friendly web interface, production engineers can represent an assembly line, the tasks to be performed for each product, and the operator''s characteristics. An intelligent search algorithm is used for generating alternative solutions to the scheduling problem. Multiple criteria decision making is used for evaluating the job rotation schedule alternatives, according to criteria deriving from industrial assembly line requirements. The tool is tested on a truck assembly case study and can provide high quality solutions. [Copyright &y& Elsevier]

Abstract: Augmented reality has been applied to develop augmented assembly systems. However, most reported studies used pre-defined assembly information; AR is predominantly used to display information and interactions between users and the augmented environment are limited. This paper presents 3D bare-hand interaction in an augmented assembly environment to manipulate and assemble virtual components. A hybrid method based on constraint analysis is presented, which interprets users’ manual assembly intents robustly without the need for auxiliary CAD information. Algorithms for assembly constraint recognition, assembly tool operations and assembly sequence evaluation have been formulated. An augmented assembly system has been developed in this research. [Copyright &y& Elsevier]

Abstract: Flexibility and changeability of assembly processes require a close cooperation between the worker and the automated assembly system. The interaction between human and robots improves the efficiency of individual complex assembly processes, particularly when a robot serves as an intelligent assistant. The paper gives a survey about forms of human–machine cooperation in assembly and available technologies that support the cooperation. Organizational and economic aspects of cooperative assembly including efficient component supply and logistics are also discussed. [Copyright &y& Elsevier]

Abstract: The productivity associated with commonly available disassembly methods today seldomly makes disassembly the preferred end-of-life solution for massive take back product streams. Systematic reuse of parts or components, or recycling of pure material fractions are often not achievable in an economically sustainable way. In this paper a case-based review of current disassembly practices is used to analyse the factors influencing disassembly feasibility. Data mining techniques were used to identify major factors influencing the profitability of disassembly operations. Case characteristics such as involvement of the product manufacturer in the end-of-life treatment and continuous ownership are some of the important dimensions. Economic models demonstrate that the efficiency of disassembly operations should be increased an order of magnitude to assure the competitiveness of ecologically preferred, disassembly oriented end-of-life scenarios for large waste of electric and electronic equipment (WEEE) streams. Technological means available to increase the productivity of the disassembly operations are summarized. Automated disassembly techniques can contribute to the robustness of the process, but do not allow to overcome the efficiency gap if not combined with appropriate product design measures. Innovative, reversible joints, collectively activated by external trigger signals, form a promising approach to low cost, mass disassembly in this context. A short overview of the state-of-the-art in the development of such self-disassembling joints is included. [Copyright &y& Elsevier]

Abstract: Mixed-model assembly systems and modular supply chains are enablers to high product variety. However, as variety gets very high, the assembly and supply processes can become very complex. In assembly systems, the complexity may cause human errors and in turn impacts system performance. The complexity also impacts supply chain configuration and inventory control policy. This paper proposes a unified measure and models of complexity to assist in designing systems with robust performances. Complexity is defined as an entropy function of product variety and models are developed to describe the complexity propagation in multi-stage assembly systems and multi-echelon supply chains. Applications of the models are presented for complexity mitigation. [Copyright &y& Elsevier]

Abstract: Flexibility and changeability of assembly processes require a close interlinkage between the worker and the automated assembly system. The interaction between human and robot improves complex assembly processes, particularly when a robot can be guided by a worker and the robot provides power assistance to the worker. The close physical contact and the direct coupling of forces of human and robot necessitate a stable and robust interaction control. This paper describes a framework developed for a robustly stable control design for interactive robots serving as intelligent assist systems for flexible and highly adaptable assembly. [Copyright &y& Elsevier]

Abstract: This paper proposes a design synthesis framework for dimensional management in multistage assembly systems which integrate the critical design tasks: (1) Tolerance Optimization; (2) Multi-Fixture Layout Design; and, (3) Part-to-part Joint Design. The proposed framework is based on the development of: (1) a new hybrid Design Structure Matrix which integrates design tasks with design configurations of Key Control Characteristics, and which has the capability to model and analyze the interdependencies among design tasks and constraints; and (2) Task Flow Chain which represents the hierarchy of design tasks and is used to generate the sequence of design tasks. The proposed methodology is illustrated and validated in the process of designing configurations for automotive underbody subassembly. [Copyright &y& Elsevier]

Abstract: This paper presents a methodology that integrates the assembly Product Design and Planning (PDP) activities with the Workplace Design and Planning (WDP) activities to improve the efficiency and quality of assembly design and planning at the early design stage. This methodology is implemented in an augmented reality (AR) assembly environment, where engineers can design and plan a product assembly and its assembly sequence through manipulating virtual prototypes in a real assembly workplace. In this AR environment, WDP information are fed back to the designers and engineers in real-time to aid them in making better decisions in assembly design and planning. [Copyright &y& Elsevier]

Abstract: In times of shortened innovation cycles, increasing product variation and demands for faster delivery, the flexibility of production systems is crucial for success. Hybrid workplaces, dynamically configurable for both human workers and robots, help to increase the flexibility. The robot kinematics employed, the available sensors, and the grasping conditions involved in the assembly process mainly determine the changeover effort of a workplace. In this paper, different concepts for hybrid workplaces are introduced and compared with respect to investment costs and configuration effort. Concept application and evaluation are illustrated by final assembly of flat screen monitors. [Copyright &y& Elsevier]