Now showing 1 - 10 of 13
  • Publication
    Capacity management of modular assembly systems
    ( 2017)
    Gyulai, D.
    ;
    Monostori, L.
    Companies handling large product portfolio often face challenges that stem from market dynamics. Therefore, in production management, efficient planning approaches are required that are able to cope with the variability of the order stream to maintain the desired rate of production. Modular assembly systems offer a flexible approach to react to these changes, however, there is no all-encompassing methodology yet to support long and medium term capacity management of these systems. The paper introduces a novel method for the management of product variety in assembly systems, by applying a new conceptual framework that supports the periodic revision of the capacity allocation and determines the proper system configuration. The framework has a hierarchical structure to support the capacity and production planning of the modular assembly systems both on the long and medium term horizons. On the higher level, a system configuration problem is solved to assign the product families to dedicated, flexible or reconfigurable resources, considering the uncertainty of the demand volumes. The lower level in the hierarchy ensures the cost optimal production planning of the system by optimizing the lot sizes as well as the required number of resources. The efficiency of the proposed methodology is demonstrated through the results of an industrial case study from the automotive sector.
  • Publication
    Artificial neural network based tool condition monitoring in micro mechanical peck drilling using thrust force signals
    ( 2017)
    Patra, K.
    ;
    Jha, A.K.
    ;
    Szalay, T.
    ;
    Ranjan, J.
    ;
    Monostori, L.
    Micro scale machining process monitoring is one of the key issues in highly precision manufacturing. Monitoring of machining operation not only reduces the need of expert operators but also reduces the chances of unexpected tool breakage which may damage the work piece. In the present study, the tool wear of the micro drill and thrust force have been studied during the peck drilling operation of AISI P20 tool steel workpiece. Variations of tool wear with drilled hole number at different cutting conditions were investigated. Similarly, the variations of thrust force during different steps of peck drilling were investigated with the increasing number of holes at different feed and cutting speed values. Artificial neural network (ANN) model was developed to fuse thrust force, cutting speed, spindle speed and feed parameters to predict the drilled hole number. It has been shown that the error of hole number prediction using a neural network model is less than that using a r egression model. The prediction of drilled hole number for new test data using ANN model is also in good agreement to experimentally obtained drilled hole number.
  • Publication
    Simulation model study for manufacturing effectiveness evaluation in crowdsourced manufacturing
    ( 2017)
    Kaihara, T.
    ;
    Katsumura, Y.
    ;
    Suginishi, Y.
    ;
    Kadar, B.
    Crowdsourced manufacturing, a new type of manufacturing in which companies share their manufacturing resources depending on their demand and capacity, is discussed in one of the main ideas of Industry 4.0 concept. According to this, companies share their resource information and can find an outsourcing company when they need specific or extra resources. In this study, we have developed a simulation model of crowdsourced manufacturing with a resource model and an agent-based negotiation algorithm to evaluate manufacturing effectiveness based on delivery and machine usage. According to a combination and balance of business style, the delivery rate changes with the saturation point which depends on resource commonality.
  • Publication
    Decomposition approach to optimal feature-based assembly planning
    ( 2017)
    Kardos, C.
    ;
    Kovacs, A.
    ;
    Vancza, J.
    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.
  • Publication
    Performance measurement in flow lines â Key to performance improvement
    ( 2016)
    Stricker, N.
    ;
    Pfeiffer, A.
    ;
    Moser, E.
    ;
    Kádár, B.
    ;
    Lanza, G.
    Key Performance Indicators (KPIs) are frequently used for measuring a production systemsâ performance. The selection of KPIs should lead to a set being as small as possible but taking into account all relevant aspects of the system. This paper provides an analytical approach to determine the set of relevant KPIs for specific production lines, allowing for a transparent and complete performance measurement. An LP was formulated for the proposed KPI model and a significant reduction of the number of KPIs used could be realized. The analytical model was tested in a real industrial application.
  • Publication
    Cyber-physical systems in manufacturing
    ( 2016)
    Monostori, László
    ;
    Kádár, Botond
    ;
    ;
    Kondoh, Shinsuke
    ;
    Kumara, Soundar R.
    ;
    Reinhart, Gunther
    ;
    ;
    Schuh, Günther
    ;
    Sihn, Wilfried
    ;
    Ueda, Kanji
    One of the most significant advances in the development of computer science, information and communication technologies is represented by the cyber-physical systems (CPS). They are systems of collaborating computational entities which are in intensive connection with the surrounding physical world and its on-going processes, providing and using, at the same time, data-accessing and data-processing services available on the Internet. Cyber-physical production systems (CPPS), relying on the latest, and the foreseeable further developments of computer science, information and communication technologies on one hand, and of manufacturing science and technology, on the other, may lead to the 4th industrial revolution, frequently noted as Industrie 4.0. The paper underlines that there are significant roots in general - and in particular to the CIRP community - which point towards CPPS. Expectations towards research in and implementation of CPS and CPPS are outlined and some case studies are introduced. Related new R&D challenges are highlighted.
  • Publication
    Design and management of reconfigurable assembly lines in the automotive industry
    ( 2016)
    Colledani, M.
    ;
    Gyulai, D.
    ;
    Monostori, L.
    ;
    Urgo, M.
    ;
    Unglert, J.
    ;
    Houten, F. van
    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.
  • Publication
    Optimized joint motion planning for redundant industrial robots
    ( 2016)
    Erös, G.
    ;
    Kovács, A.
    ;
    Váncza, J.
    The paper presents a model and solution method for optimized robot joint motion planning of redundant industrial robots that execute a set of tasks in a complex work environment, in face of various technological and geometric constraints. The approach aims at directly exploiting redundancy to optimize a given performance measure, e.g., cycle time. Alternative configurations along the path are captured in a graph model, whereas bi-directional transition between task and configuration spaces facilitates generating relevant, collision-free configurations only. Re-parametrization of the trajectory warrants compliance with the robot's kinematic constraints. Successful application of the method is demonstrated in remote laser welding.
  • Publication
    Supporting multi-level and robust production planning and execution
    ( 2015)
    Stricker, N.
    ;
    Pfeiffer, A.
    ;
    Moser, E.
    ;
    Kádár, B.
    ;
    Lanza, G.
    ;
    Monostori, L.
    Operating current production systems influenced by the factors of increasing dynamics and volatility poses a need for robustness. Among different enablers for robustness the appropriate ones for specific production systems have to be identified and evaluated. In this cooperative paper multi-objective decision support models will be presented evaluating the best enablers for the levels of production network, plant and shop-floor. The suggested models for the stabilization of the production system's performance under volatile environment use analytical and simulation based approaches on the regarded levels.
  • Publication
    Design and assessment of quality control loops for stable business processes
    ( 2012)
    Schmitt, Robert
    ;
    Monostori, László
    ;
    Glöckner, Henrik
    ;
    Viharos, Zsolt János
    Due to their open and dynamic character, business processes in lack of adequate feedback mechanisms tend to become unstable in case of unanticipated disturbances or target adjustments. In order to face this challenge and to ensure entrepreneurial quality the implementation of quality control loops is proposed, whose design is derived from cybernetics. The paper discusses requirements for the characteristics of quality control loops and presents a new approach for their assessment implemented in software. The developed tool also serves as a knowledge exchange platform since it provides an opportunity for exchanging standardized control loop elements.