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  • 101.
    Högberg, Dan
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bohlin, Robert
    Fraunhofer-Chalmers Centre.
    Carlson, Johan S.
    Fraunhofer-Chalmers Centre.
    Creating and shaping the DHM tool IMMA for ergonomic product and production design2016In: International Journal of the Digital Human, ISSN 2046-3375, Vol. 1, no 2, p. 132-152Article in journal (Refereed)
    Abstract [en]

    The history, status and outlook of the research and development actions associated with the creation of the digital human modelling tool intelligently moving manikins (IMMA) are described. The underlying fundamental concepts are described and research and development results so far are illustrated or referred to. Two case studies illustrating use of IMMA on industry-based problems are described. The paper also covers reflections on conceptions for prospective DHM tool developments from a general perspective, relating to areas of ergonomics and design methodology, as well as describing some of the plans for further developments and applications of the IMMA tool. These may be of assistance when identifying challenges for future research and development of DHM tools that are used in product and production design processes in industry.

  • 102.
    Högberg, Dan
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ruiz Castro, Pamela
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Mårdberg, Peter
    University of Skövde, School of Engineering Science. Fraunhofer-Chalmers Centre, Gothenburg.
    Delfs, Niclas
    Fraunhofer-Chalmers Centre, Gothenburg.
    Nurbo, Pernilla
    Volvo Car Corporation, Gothenburg.
    Fragoso, Paulo
    Scania CV, Södertälje.
    Andersson, Lina
    Volvo Trucks, Gothenburg.
    Brolin, Erik
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    DHM Based Test Procedure Concept for Proactive Ergonomics Assessments in the Vehicle Interior Design Process2018In: Proceedings of the 20th Congress of the International Ergonomics Association (IEA 2018): Volume V: Human Simulation and Virtual Environments / [ed] Sebastiano BagnaraRiccardo TartagliaSara AlbolinoThomas AlexanderYushi Fujita, Cham, Switzerland: Springer, 2018, Vol. 822, p. 314-323Conference paper (Refereed)
    Abstract [en]

    The development of a digital human modelling (DHM) based test procedure concept for the assessment of physical ergonomics conditions in virtual phases of the vehicle interior design process is illustrated and discussed. The objective of the test procedure is to be a valuable tool for ergonomic evaluations and decision support along the design process, so that ergonomic issues can be dealt with in an efficient, objective and proactive manner. The test procedure is devised to support companies in having stable and objective processes, in accordance with lean product development (LPD) philosophies. The overall structure and fundamental functionality of the test procedure concept is explained by a simplified use case, utilizing the DHM tool IPS IMMA to: define manikin families and manikin tasks; predict manikin motions; and visualize simulations and ergonomics evaluation outcomes.

  • 103.
    Högberg, Fredrik
    et al.
    University of Skövde, School of Technology and Society.
    Chavez, Nathalie
    University of Skövde, School of Technology and Society.
    Effektivisering av material- och informationsflödet: En fallstudie på SKF2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
  • 104.
    Irazu, Aitor
    et al.
    University of Skövde, School of Engineering Science.
    Uranga, Maider
    University of Skövde, School of Engineering Science.
    Design optimisation of a mechanism used to handle heavy objects2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This paper presents a design optimisation of a mechanism used to lift and turn heavy objects, in this case, a specific gear that weights 3000 kg. The objective pursued during the development of the project was to reduce the weight of the mechanism, and thus, make it more cost-efficient, as well as to improve the clamping system to secure that the heavy objects are safely handled. The method followed was to first identify the critical parts in cooperation with the client. Then, the corresponding analysis has been developed for each of those parts, by minimising the mass of two of them, and by selecting and dimensioning the guideways for the clamping motion in the other case. The key results obtained from these analyses were that the weight of one of the parts was reduced by 50 %, the clamping system was improved and that the stress analysis shows that the maximum stress is far below acceptable levels. Hence, it is concluded that it was possible to optimise the mechanism and reduce the weight, improving the handling of heavy objects.

  • 105.
    Iriondo, Aitor
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Oscarsson, Jan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Jeusfeld, Manfred A.
    University of Skövde, School of Informatics. University of Skövde, The Informatics Research Centre.
    Simulation Data Management in a Product Lifecycle Management Context2017In: Advances in Manufacturing Technology XXXI: Proceedings of the 15th International Conference on Manufacturing Research, Incorporating the 32nd National Conference on Manufacturing Research, September 5–7, 2017, University of Greenwich, UK / [ed] James Gao, Mohammed El Souri, Simeon Keates, Amsterdam: IOS Press, 2017, p. 476-481Conference paper (Refereed)
    Abstract [en]

    Reuse of virtual engineering models and simulations improves engineering efficiency. Reuse requires preserving the information provenance. This paper suggests a framework based on the 7W data provenance model to be part of simulation data management implemented in product lifecycle management systems. The resulting provenance framework is based on a case study in which a product was re-engineered using finite element analysis.

  • 106.
    Iriondo Pascual, Aitor
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Kolbeinsson, Ari
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ruiz Castro, Pamela
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Mahdavian, Nafise
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV, Södertalje, Sweden.
    Proposal of an Intuitive Interface Structure for Ergonomics Evaluation Software2018In: Proceedings of the 20th Congress of the International Ergonomics Association (IEA 2018): Volume VIII: Ergonomics and Human Factors in Manufacturing, Agriculture, Building and Construction, Sustainable Development and Mining / [ed] Sebastiano Bagnara, Riccardo Tartaglia, Sara Albolino, Thomas Alexander, Yushi Fujita, Cham: Springer, 2018, Vol. 825, p. 289-300Conference paper (Refereed)
    Abstract [en]

    Nowadays, different technologies and software for ergonomics evaluations are gaining greater relevance in the field of ergonomics and production development. The tools allow users such as ergonomists and engineers to perform assessments of ergonomic conditions of work, both related to work simulated in digital human modelling (DHM) tools or based on recordings of work performed by real operators. Regardless of approach, there are many dimensions of data that needs to be processed and presented to the users.

    The users may have a range of different expectations and purposes from reading the data. Examples of situations are to: judge and compare different design solutions; analyse data in relation to anthropometric differences among subjects; investigate different body regions; assess data based on different time perspectives; and to perform assessments according to different types of ergonomics evaluation methods. The range of different expectations and purposes from reading the data increases the complexity of creating an interface that considers all the necessary tools and functions that the users require, while at the same time offer high usability.

    This paper focuses on the structural design of a flexible and intuitive interface for an ergonomics evaluation software that possesses the required tools and functions to analyse work situations from different perspectives, where the data input can be either from DHM tools or from real operators while performing work. 

  • 107.
    Iriondo Pascual, Aitor
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Brolin, Erik
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV, Södertälje, Sweden.
    Application of Multi-objective Optimization on Ergonomics in Production: A Case Study2020In: Advances in Additive Manufacturing, Modeling Systems and 3D Prototyping: Proceedings of the AHFE 2019 International Conference on Additive Manufacturing, Modeling Systems and 3D Prototyping, July 24-28, 2019, Washington D.C., USA / [ed] Massimo Di Nicolantonio, Emilio Rossi, Thomas Alexander, Springer, 2020, p. 584-594Conference paper (Refereed)
    Abstract [en]

    Taking a holistic perspective is central in production development, aiming to optimize ergonomics and overall production system performance. Hence, there is a need for tools and methods that can support production companies to identify the production system alternatives that are optimal regarding both ergonomics and production efficiency. The paper presents a devised case study where multi-objective optimization is applied, as a step to towards the development of such an optimization tool. The overall objective in the case study is to find the best order in which an operator performs manual tasks during a workday, considering ergonomics and production system efficiency simultaneously. More specifically, reducing the risk of injury from lifting tasks and improving the throughput are selected as the two optimization objectives. An optimization tool is developed, which communicates with a digital human modelling tool to simulate work tasks and assess ergonomics. 

  • 108.
    Johansson, Mikael
    et al.
    University of Skövde, School of Engineering Science.
    Persson, Anton
    University of Skövde, School of Engineering Science.
    HALVAUTOMATISERING OCH BEREDNING AV PARTITILLVERKNING2017Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Ett examensarbete har utförts på ett företag där trädetaljer tillverkas. Arbetet gick ut på att förbättra processen vid tillverkning av glaspartier. Företaget är ledande i Skandinavien beträffande sina träprodukter. Tillverkningen sker till stor grad av helautomatiserad produktion men har fortfarande några manuella stationer kvar. Företaget omsätter omkring 450 miljoner kronor per år och har cirka 70 anställda.

    Syftet med examensarbetet var att förbättra processen vid produktion av glaspartier för att reducera den totala operationstiden och minska interna kvalitetsförluster. Huvudmålen var att reducera interna kvalitetsförluster med 10 % samt att reducera operationstiderna med 15 %. För att uppnå målen valdes verktygen go to gemba, frekvensstudie, tidsstudie samt spagettidiagram för att hitta olika slöserier i produktionen och kartlägga operationstiderna. Metod valdes genom att läsa på om de olika verktygen och jämföra dem mot andra verktyg i den teoretiska referensramen.

    Det visade sig att det fanns en del slöserier i processen. Framför allt en hel del onödiga rörelser för både material och för operatörer. Det fanns också många olika lager som varierade i väntetid för det bearbetade materialet under flödet samt en hel del manuellt arbete som företaget helst ville bygga bort. Vid undersökning av nuläget sågs det också att företaget saknade ett standardiserat arbete samt ett 5S arbete i flödet av glaspartier.

    Genom en summering av nuläget kunde ett förbättringsförslag läggas fram. En del av förbättringsförslaget var att bygga bort det manuella arbetet genom att införskaffa en maskin som byggs in i den automatiserade karmlinan. Det leder till mindre kvalitetsförluster, men också färre lager eftersom glaspartitillverkningen kommer att ske i karmlinan. En annan del av förbättringsförslaget var att bygga in slutmonteringen i den befintliga karmlinan där andra liknande produkter redan tillverkades. Som nuläget såg ut var slutmonteringen en separat process vid sidan av karmlinan. Det gjorde att produkterna lades på vagnar och ställdes på ett lager för att sedan ha en lång väntetid innan de monterades. Genom att bygga in slutmonteringen i karmlinan kommer företaget att montera glaspartierna i karmlinan utan onödiga lager. Ett sista förbättringsförslag var att implementera 5s och standardiserat arbetssätt över hela tillverkningen av glaspartier. Det troliga utfallet av förbättringsförslagen beräknades på reducerad operationstid med 59 % och reducerade interna kvalitetsförluster med 80 %

  • 109.
    Johansson, Ulrika
    University of Skövde, School of Technology and Society.
    Logistisk tillämpning idag: en historisk återblick2007Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    In the rate of changes condition of the market in shape of increasing competitiveness situation, local as global, this leads to that logistics has to be developed in the same rate. Logistics has been developed from the military and after the war, logistics was figurative to the companies transport- and store problems. After this, logistics had been divided up into four different time phases (the seventies to the 21:th century). All these time phases have together develop the spectacle and focus of the logistics today. Afterward further developing of the logistics approach to Supply Chain Management (SCM) and afterward SCM, Demand Chain Management (DCM) was developed in aim to secure that the right products were manufactured on the basis of the end customers real requirement and wishes.

    This paper is taking the aim and problem formulation as a starting point. The problem formulation that I will answer is:

     DCM, a new concept or the Emperor New Clothes?

    The aim with this paper is that I will examine how the historical developing has lead to the spectacle and application of logistics today. Further is the aim to see which difference and likeness the concept SCM and DCM has, in order to see if there is a further time phase of the logistics development that is in approaching. The aim is also to see how DCM practically can be applying. To be able to reach the aim of this paper, a qualitative procedure has been applied. Further I have done literary studies of theory around chosen problem area and I have done an interview.

    Empirical information has been collected by Electrolux AB, which are a world’s leader within manufacturing domestic appliance and corresponding equipment for professional user. The reason why Electrolux were chosen was because they were an early adopter of DCM.

    On the basis of the theory that was studyed around chosen problems area and the empirical information that has analysed, I have draught some conclusion to be able to answer the papers problem area and aim. Some of the conclusion I draught is that the historical development and the four time phrases that it includes, is that the four time phrases successive has formed the methods and tools that SCM constitute of. This developing has taken place under the years of the forties century until today, which makes SCM the result of a historical development rather then as a result of new revelationary ideas. Further I draught the conclusion that SCM should be implemented before DCM. I draught the conclusions that Electrolux apply DCM in a way that they has succeed too apply the theory that is described about DCM, but Electrolux has made an own interpretation of the concept. Via implement the analysis around the papers problem area and aim I consider that DCM is a variant of SCM, where the tool consumer insight is applying. On the basis of this I draught the conclusion that there isn’t sufficient that separate DCM from SCM to be able to approaching that DCM is a new time phrase in the logistical development.

  • 110.
    Karlsson, Daniel
    et al.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre. Production Engineering, Componenta, Nossebro, Sweden.
    Linnéusson, Gary
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre. Production Engineering, Arkivator AB, Falköping, Sweden.
    Systemic change management: An opportunity for manufacturing organizations2008In: Proceedings of the 18th International Conference on Flexible Automation and Intelligent Manufacturing: FAIM 2008 / [ed] Leo J. de Vin, 2008, Vol. 1, p. 654-659Conference paper (Refereed)
    Abstract [en]

    This paper examines potential opportunities at two SMEs (small to medium-sized enterprises) to improve the decision making process for change in their manufacturing organizations. Present procedures of the decision making process for manufacturing system development have been studied by applying feedback systems thinking. A framework for systemic change management is proposed utilizing a bottom-up perspective to acknowledge individual competence and creativity. In conclusion applying system principles facilitates an environment for proactive developments towards a learning organization.

  • 111.
    Karlsson, Ingemar
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    An interactive decision support system using simulation-based optimization and knowledge extraction2018Doctoral thesis, monograph (Other academic)
    Abstract [en]

    The use of simulation to improve existing manufacturing systems is not new, but simulation can also be used increase the understanding of production systems that have not yet been built. The power of simulation models can be further enhanced by using simulation-based optimization, in which an optimization algorithm tries to find optimal solutions, given certain objectives. However, extracting knowledge from the data resulting from simulation experiments and simulation-based optimization is a complex task. Therefore, tools are needed to assist users in this task. These tools can be visual, like diagrams, or can be generated by data mining. The process of running a study using simulation-based optimization to extract knowledge is a manual task that can in part be automated using existing tools, but to the author’s knowledge there is no software that implements the complete process. This work aims to develop a novel decision support system to support the generic decision process when using simulation and simulation-based optimization. The first step in setting up such a system is to understand how industry currently uses simulation and simulation-based optimization in manufacturing operations. Thus a questionnaire was distributed to manufacturing companies and organizations. The results showed that these techniques are being used, but that companies want more help with the analysis of the results as well as an automated guide in the decision process. This work proposes a system that supports a generic decision process by providing a tool with which a user can define a workflow in their organization, using simulation-based optimization as one component. The decision support system then provides tools for extracting knowledge in the form of diagrams and performs data mining for automated analysis. Data mining is part of the workflow as a tool for extracting knowledge after an optimization, as well as a tool for guiding optimization to suit the users’ preferences. The decision support system also provides for visualization of simulation models and optimization results using augmented reality. A head-mounted display helps users to see the results and model behaviors in 3D. This technology also makes it possible for users to collaborate, both in the same location and remotely. These visual and automatic analysis tools are shown to be effective in several application studies of real-world production scenarios in which data mining has been used to extract important knowledge that would be hard to obtain manually. Together with the automated workflow and efficient visualization of simulation and optimization results in augmented reality, the decision support system is believed to be an effective tool for extracting knowledge for general production systems design and analysis.

  • 112.
    Karlsson, Ingemar
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Combining augmented reality and simulation-based optimization for decision support in manufacturing2017In: Proceedings of the 2017 Winter Simulation Conference / [ed] W. K. V. Chan, A. D’Ambrogio, G. Zacharewicz, N. Mustafee, G. Wainer, and E. Page, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 3988-3999Conference paper (Refereed)
    Abstract [en]

    Although the idea of using Augmented Reality and simulation within manufacturing is not a new one, the improvement of hardware enhances the emergence of new areas. For manufacturing organizations, simulation is an important tool used to analyze and understand their manufacturing systems; however, simulation models can be complex. Nonetheless, using Augmented Reality to display the simulation results and analysis can increase the understanding of the model and the modeled system. This paper introduces a decision support system, IDSS-AR, which uses simulation and Augmented Reality to show a simulation model in 3D. The decision support system uses Microsoft HoloLens, which is a head-worn hardware for Augmented Reality. A prototype of IDSS-AR has been evaluated with a simulation model depicting a real manufacturing system on which a bottleneck detection method has been applied. The bottleneck information is shown on the simulation model, increasing the possibility of realizing interactions between the bottlenecks. 

  • 113.
    Karlsson, Ingemar
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bandaru, Sunith
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    An interactive decision support system using simulation-based optimization and data mining2015In: Proceedings of the 2015 Winter Simulation Conference / [ed] L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti, IEEE Press, 2015, p. 2112-2123Conference paper (Refereed)
    Abstract [en]

    This paper describes a decision support system (DSS) built on knowledge extraction using simulation-based optimization and data mining. The paper starts with a requirements analysis based on a survey conducted with a number of industrial companies about their practices of using simulations for decision support.Based upon the analysis, a new, interactive DSS that can fulfill the industrial requirements, is proposed.The design of the cloud-based system architecture of the DSS is then described. To show the functionality and potential of the proposed DSS, an application study has been performed for the optimal design of a hypothetical but realistic flexible production cell. How important knowledge with respect to different preferences of the decision maker can be generated as rules, using the new Flexible Pattern Mining algorithm provided in the DSS, will be revealed by the results of this application study.

  • 114.
    Kedbäck, Miranda
    University of Skövde, School of Engineering Science.
    Exploring Dynamic Complexity in the Symbiosis of Operations and Maintenance Functions: A Simulation-Based Optimisation Study2018Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Maintenance, the process of preserving the condition of the equipment and performance in a production facility, stands for a considerable large cost in the budget of manufacturing organisations and is strongly affected by short-term philosophy. Therefore, both the long-term and short-term consequences of maintenance strategies need to be examined and analysed. The aim with this research is to investigate the dynamic complexity between the requirements from operations on the performance of maintenance, to illustrate the challenge of trading long-term and short-term requirements and benefits. These aspects have been studied through system dynamics (SD) modelling, simulation-based optimisation (SBO) and multi-objective optimisation (MOO). In order to illustrate the analysed problems, a state-of-the-art literature review has been created and two different scenarios have been evaluated. The scenarios are to investigate both the effects of more or less planned maintenance and the implication of a stock-and-flow structure for hiring and retirements of maintenance resources. A conceptual base model, created in previous research, has been applied and developed in order to meet the objectives.

    From the performed experiments, it can be confirmed that with the use of SD simulation trends and consequences over longer periods of time are truly visualised. In the first scenario, the results indicate that a short-term maintenance management strategy is unprofitable over time. The simulation also reveals that improvement strategies and proactive work can revolutionise capability and profit over time, even if these strategies initially generate a higher cost. In the second scenario, where the effects of a major retirement are visualised, the results confirm that the company needs to act proactively in order to avoid great financial losses. Employee and average skill losses cause long-term negative effects on the capability and availability. The optimisation that has been performed, with the hiring rate as the main variable and the objectives of maximising availability, minimising the direct cost and minimising the indirect cost, has generated feasible solutions on the Pareto front.

    In conclusion, the results from the experiments identify the behaviours and causal relationships in a maintenance system in symbiosis with operations. With the long-term goal of generating less reactive workload on the maintenance function, there are many benefits to obtain. The charted delays and causal relationships in the system indicate multi-level consequences, where a management approach should benefit financially from emphasising the importance of acting proactively and directing resources to improvement strategy work.

  • 115.
    Kedbäck, Miranda
    et al.
    University of Skövde, School of Engineering Science.
    Ekdahl, Stellan
    University of Skövde, School of Engineering Science.
    Arbetsstandard, tidsunderlag och förbättringsarbete vid manuella arbetsstationer2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Brodit AB is a company located in Karlsborg, which manufactures holders for technical communication devices for mounting in vehicles. The manual manufacturing, where bending and assembly takes place, lacks a method for standardisation, a base for time scheduling, a base for manpower planning and a method for continuous improvements. The aim of this bachelor thesis was to develop a base for standardised work, time scheduling and manpower planning as well as a method for continuous improvements. To reach these aims a number of sub targets needed to be reached, which were to sustain an analysis of the current situation through observations and time studies, develop standard data for work tasks, divide the tasks into value adding work, non-value adding work and necessary non-value adding work, develop a suggestion to an improved work standard and develop a method for continuous improvements.

    To reinforce choices of methods and conclusions, a number of engineering areas have been studied. Based on the theoretical frame of references, a number of methods for the empirical study were formed.  The study was conducted of observations according to genchi genbutsu, grouping of work tasks, time motion studies performed with a time watch and SAM analysis, calculation of standard data times, evaluation of value adding-, non-value adding- and necessary non-value adding work, SMED analysis and spaghetti diagrams.

    The result of the empirical study was a base for time scheduling with calculated standard times for each work task, where every work task was evaluated as value adding, non-value adding or necessary non-value adding. Based on this, a base for manpower planning can be compiled. The compilation of standard data times as well as the SAM analysis resulted in cycle times far shorter than the cycle times measured in current production. Also, the setup times appeared to be long and irregular with several unnecessary work tasks performed. The result of the spaghetti diagrams also shows unnecessary movements. The conclusion of this is that non-value adding work tasks occurs in the process, that the work is performed in different ways which causes waste in the process and that the work performance rating is below 100 %. With a standardised way of work as well as eliminated non-value adding work tasks, the production could be increased with 60 %; alternatively, the manpower could be decreased with two workers. With the compiled improvement suggestions implemented, the cycle time at the bending working stations could be decreased with at least 50 % and the total setup time could be decreased with at least 57 %.

    A method for continuous improvements has been developed, based on a PDCA cycle. With improved conditions on each working station and a standardised way to work, possible improvements can be achieved in reduced setup times, reduced cycle times as well as the implementation of a culture of continuous improvements. 

  • 116.
    Keyvani, Ali
    et al.
    Product and Production Development Dep., Chalmers University of Technology, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    Industrial Development, Scania CV, Södertälje, Sweden.
    Lämkull, Dan
    Virtual Methods & IT, Volvo Car Corporation, Gothenburg, Sweden.
    Delfs, Niclas
    Fraunhofer Chalmers Research Centre, Gothenburg, Sweden.
    Rhen, Ida-Märta
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Örtengren, Roland
    Product and Production Development Dep., Chalmers University of Technology, Gothenburg, Sweden.
    Ergonomic Risk Assessment of a Manikin’s Wrist Movements - a Test Study in Manual Assembly2013Conference paper (Refereed)
    Abstract [en]

    Use of digital human modeling (DHM) tools enables early assessment of ergonomic risks in the production development process. This early risk assessment can indicate needs for preventive actions in order to decrease risks for work-related musculoskeletal disorders. A method for the assessment of physical workload has been developed, for the analysis of wrist joint data produced by a DHM tool. The method is tested in a simulation model of an actual manual assembly station in industry where it is assumed that physical workload problems exist. The results show that the method can be successfully applied on an industrial case. In addition, presumptive risks and possible diagnoses are predicted based on the similarity of the simulated task’s motions with motions from other known work class profiles stored in a database based on epidemiological research.

  • 117.
    Kjellén, Linus
    et al.
    University of Skövde, School of Engineering Science.
    Björnell, Jonna
    University of Skövde, School of Engineering Science.
    Ställtids- och kassationsreducering, svarvning2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [sv]

    Ett examensarbete är utfört på ett tillverkande företag med cirka 140 stycken anställda och utför skärande bearbetning i stål, aluminium och gjutjärn till bland annat bil-, telekom och övrig verkstadsindustri. Produktsortimentet består till största delen av kopplingar till ramlager, medbringare, fyrhjulsdrifter och robotkomponenter. Företaget har en svarvgrupp med tre stycken CNC-svarvar som har problem med långa omställningstider och det upptar en stor del av produktionstiden. Det försvårar för svarvgruppen att leverera produkter i tid, i samband med omställningarna förekommer även en stor mängd kassationer som orsakar kostnader och som även är en bidragande orsak till de långa omställningstiderna.

    Syftet och huvudmålen var att reducera omställningstiden med 30 %, minska kassationer vid omställning med 30 % och att ta fram lämplig metod för ställtidsreducering. För att uppnå syftet och huvudmålen valdes metoden Single Minute Exchange of Die (SMED) som är en metod för att reducera omställningstid. Valet gjordes utifrån en litteraturstudie där metoden visat sig vara resultatrik i liknande fallstudier.

    Med användning av videodokumentation, spagettidiagram och kassationsdokument kunde nuläget fastställas i svarvgruppen. Orsakerna till den långa omställningstiden och kassationerna varierade, en stor anledning till deras långa omställningstider var att de genomförde alla aktiviteter under den inre omställningen. En annan anledning var att svarvgruppen saknade ett standardiserat arbetssätt samt struktur och framförhållning i arbetet.

    Utifrån nulägesanalysen utvecklades förbättringsförslag som implementerades inför en pilotstudie som kunde frambringa ett resultat. Omställningen kunde reduceras med 38 % och kassationer i samband med omställning reducerades med 50 %. Resultatet av studien visar även att metoden är lämplig för fortsatt arbete med ställtidsreducering för svarvgruppen. Genom implementering av SMED metoden har omställningstiden och kassationerna reducerats, vilket medför en ökad flexibilitet eftersom det finns en större förmåga att snabbt genomföra en omställning från en produkt till en annan och snabbare bemöta kundernas efterfrågan.

  • 118.
    Krantz, Johan
    et al.
    University of Skövde, School of Engineering Science.
    Krantz, Stefan
    University of Skövde, School of Engineering Science.
    Förslag på utformning av Kitt- och Sekvensering inför nästa generations motor: På Volvo Cars i Skövde2016Independent thesis Basic level (university diploma), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Volvo Cars Skövde will in year 2018 implement a new engine model in Skövde plant, which will lead to a greatly increased variety of the articles in the material facade at the production line when the engine variants increases. However, the current material facade will not be able to cope with the future increase of articles. Therefore, design proposals for the handling of the material by using kit- and sequence picking externally from the production line have been proposed. Hence, handling these operations externally may lead to an efficient material flow, but also enables handling more articles when the engine variants increase.

    The main objective of the project was to develop proposals on how workplace design for a kit- and sequence picking station may look like, and how the flow of material should be handled to and from these stations. To implement this, a form of a PDCA-method has been used to structure the work. Relevant literature on the theory and studies in similar areas has been reviewed to gather knowledge in this area. Successful methods used in other studies, i.e. interviews, observations and benchmarking, were also used in this project to collect data.

    The results based on the collected data generated, present different layout suggestions of a kit- and sequence picking station, with regard to quality assurance and efficiency of the picking patterns, ergonomics, reliability of delivery and the total area required for these picking stations. It will also manage the flow of materials to and from these stations that should be handled in an efficient way. Prototype sketches of proposed way of transport and aid for the material handling have been developed for the company, which will be a base for continued work before the implementation of the next generation engine in year 2018. 

  • 119.
    Kärmander, Adam
    et al.
    University of Skövde, School of Engineering Science.
    Nori, Daniel
    University of Skövde, School of Engineering Science.
    Produktionstekniskt förbättringsarbete hos Dava Foods: Förbättrande av en maskin2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete har utförts på Dava Foods i Skara. Det är ett företag där hönsägg i olika kvaliteter bearbetas. Där finns en äggknäckningsprocess som består av två maskiner. Organisationen har problem med maskinen som har till uppgift att separera brickor och ägg. Den stannar alltför ofta och därför har företaget bett om hjälp.

    Syftet med arbetet var att ta reda på vilka orsaker som ligger bakom stoppen och att ge förbättringsförslag för att förhindra framtida oönskade stopp. Observationer och intervjuer genomfördes för att få en bättre förståelse för hur maskinen fungerar. Därefter utfördes fyra stopptidsanalyser för att dokumentera stilleståndstider och för att det skulle vara möjligt att se vad som får maskinen att stanna. Metoden 5 x varför användes för att hitta rotorsakerna till problemen. Förbättringsförslag gavs utifrån de rotorsaker som identifierades och även utifrån egna tankar och idéer. Dessa förslag placerades även in i två PICK-charts så att organisationen eventuellt kan välja att implementera några av dessa i framtiden.

    Arbetet resulterade i 12 unika förbättringsförslag. 2 av dessa hade med brickornas material att göra. Det ena förslaget innebar att endast använda plastbrickor och det andra var en blandning av plast- och pappersbrickor. Ytterligare ett förslag var brickor med 5x5 ägg, vilket innebär att brickan ska ha plats för 5 ägg på bredden och 5 på längden. Tre förbättringsförslag hade med människor att göra. Dessa handlade om att operatören ska försöka vara mer noggrann med avståndet mellan brickor på första rullbandet, att människor ska vara försiktiga vid transport och hantering av äggen samt att det ska vara tre personer som arbetar vid maskinen. Några mer omfattande förbättringsförslag var ett längre första rullband, en robot vid första rullbandet, en bättre funktion som separerar brickor, en ny maskin och en annan layout. Det föreslogs även att minska hastigheten på den så kallade cylindern.

    Slutsatsen är att det finns tre förbättringsförslag som verkligen bör övervägas. Dessa är användning av plastbrickor istället för pappersbrickor, införskaffande av en ny maskin samt tre personer som arbetar vid maskinen. Om plastbrickor används istället för pappersbrickor så hade det blivit mycket mindre stopp. Detta gäller även för en ny maskin som kan hantera både plast- och pappersbrickor. Om tre personer arbetar vid maskinen så kan den tredje personen ha som arbetsuppgift att upptäcka och åtgärda fel innan dessa får maskinen att stanna.

  • 120.
    Land, Niklas
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Torgny, Almgren
    GKN Aerospace Sweden AB, Trollhättan, Sweden.
    Vallhagen, Johan
    Volvo Group Trucks Operations, AB Volvo, Gothenburg, Sweden.
    Virtual Human-Robot Collaboration: The Industry's Perspective on Potential Applications and Benefits2019In: Advances in Manufacturing Technology XXXIII: Proceedings of the 17th International Conference on Manufacturing Research, incorporating the 34th National Conference on Manufacturing Research, September 10–12, 2019, Queen’s University Belfast, UK / [ed] Yan Jin, Mark Price, Amsterdam: IOS Press, 2019, Vol. 9, p. 161-166Conference paper (Refereed)
    Abstract [en]

    Two keystones of Industry 4.0 are the increased use of autonomous robots and advanced simulation software. Human-Robot Collaboration (HRC) combines the strengths of humans and robots, opening up application areas that previously could not be automated. However, the realization of HRC on industrial shop floors is held back by several challenges: safety, trust, the need for intuitive interfaces, and design methods. This study investigates the automotive industry’s perspective on relevant application areas and potential benefits of HRC. The data were collected through a survey of 185 participants from a variety of working roles in the automotive industry. The results of the study indicate that participants from the automotive industry consider that the areas best suited to the implementation of collaborative robots are material handling, assembly, and quality control, with potential benefits in ergonomics, efficiency, and quality. The results can be used for the development of a future virtual HRC simulation model.

  • 121.
    Larsson, Carina
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Communicating performance measures: Supporting continuous improvement in manufacturing companies2017Licentiate thesis, comprehensive summary (Other academic)
    Abstract [en]

    Manufacturing enterprises are a key driver of economic growth (Eurostat, 2016). Implementing continuous improvement (CI) is commonly used to increase competitiveness (Hyland et al., 2007), but despite the well-known theory of CI, many manufacturing companies fail in implementing it (Bhasin, 2012; Nordin et al., 2012; Tiwari et al., 2007).

    An identified critical success factor in CI implementation is the evaluation of performance, including the performance evaluation system itself, the linkage between targets at different company levels, and continual evaluation of performance (Bakås et al., 2011; Scherrer-Rathje et al., 2009; Ukko et al., 2009). Another critical success factor in CI implementation is the communication of performance measures (Bakås et al., 2011; Ukko et al., 2009).

    This research explores the communication of performance measures. The aim is to support CI by improving the communication of performance measures, and to this end, this thesis concentrates on identifying the main challenges in the communication of performance measures supporting CI. The research scope is manufacturing companies in general, and manufacturing SMEs in particular. The relevant literature concerning the communication of performance measures in manufacturing companies is identified and summarized. Also, current practice is explored, focusing on how performance measures are communicated in manufacturing companies, and whether and how the communication supports CI. This has been done to identify divergences between current practice and theory. Finally, theory and empirical findings are synthesized to identify some of the main challenges to be addressed in order to succeed in CI.

    The main task is to support CI efforts in manufacturing SMEs, eliminating the identified divergences in the communication of performance measures by adapting these measures to these manufacturing SMEs. These challenges can be summarized as follows: 

    - using both financial performance measures as well as objective and subjective, non-financial performance measures  - aligning performance measures with strategy and targets  - integrating all performance measure communication, as related to both daily performance and CI, in the same communication loop.  - forming two-way communication channels between managers and operators  - aligning oral and written communication channels  - exploring how information systems can facilitate the communication of performance measures  - using and optimizing the visual communication of performance measures

  • 122.
    Larsson, Carina
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. University of Jönköping.
    Säfsten, Kristina
    University of Jönköping.
    Visual communication of performance meaures supporting continuous improvement: Challenges and opportunities for manufacturing SMEs2016Conference paper (Refereed)
    Abstract [en]

    This paper provides a holistic view of visual communication of performance measures supporting continuous improvement in manufacturing SMEs. This is done by a theoretical part with a literature review, and an empirical part with case studies, including both the managers’ and the operators’ perspectives, and by focusing on manufacturing SMEs. The paper identifies five challenges and one opportunity in visual communication that SMEs perceive when using visual communication of performance measures, supporting continuous improvement.

  • 123.
    Larsson, Carina
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. School of Engineering, Jönköping University.
    Säfsten, Kristina
    School of Engineering, Jönköping University.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Performance measurement communication supporting lean production in SMEs2014In: Performance management: Designing the high-performing organization, 2014, p. 714-725Conference paper (Refereed)
    Abstract [en]

    Purpose

    The aim of this paper is to provide an overview of the current status of performance measurement communication to support lean production in SMEs.

    Design/methodology/approach

    The paper is based on theoretical and empirical studies. A literature review of existing research in performance measurement communication, focusing on lean production in SMEs, was carried out. The empirical part is based on interviews with both managers and operators in SMEs in the south of Sweden working with lean production. Twenty-four interviews in eight companies / plants were carried out.

    Findings

    The paper provides a structured overview of current research in performance measurement communication. Performance measurement communication was categorised into three parts, which taken together could support lean production implementation in SMEs. It can be concluded that, although all existing research in performance measurement and communication, there is no operational guideline of how to communicate performance measurement. From the interviews it can be seen that the companies have improved their performance measurement communication during the lean production implementation, but that there is no common way of communicating performance measurements in SMEs.

  • 124.
    Larsson, Carina
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Säfsten, Kristina
    Högskolan i Jönköping.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Performance measurement follow-up supporting continuous improvements in manufacturing companies: a systematic review2015In: 22nd EurOMA conference: Operations management for sustainable competitiveness / [ed] Gerald Reiner, 2015Conference paper (Refereed)
    Abstract [en]

    Performance measurement has been paid a lot of attention. This paper provides a systematic review of existing research in performance measurement follow-up, which so far has been less treated. The paper suggests a categorization of the follow-up phase into the performance measurement system, input to and output from the system, and operational activities. It is concluded that there is a lack of research concerning the operational activities in the follow-up phase. It is also concluded that most of the research concerning follow-up of performance measurement does not support continuous improvement explicitly, but concerns performance measurement follow-up in general.

  • 125.
    Lidberg, Simon
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Evaluating the impact of changes on a global supply chain using an iterative approach in a proof-of-concept model2018In: Advances in Manufacturing Technology XXXII: Proceedings of the 16th International Conference on Manufacturing Research, incorporating the 33rd National Conference on Manufacturing Research, September 11–13, 2018, University of Skövde, Sweden / [ed] Peter Thorvald, Keith Case, Amsterdam: IOS Press, 2018, p. 467-472Conference paper (Refereed)
    Abstract [en]

    Analyzing networks of supply-chains, where each chain is comprised of several actors with different purposes and performance measures, is a difficult task. There exists a large potential in optimizing supply-chains for many companies and therefore the supply-chain optimization problem is of great interest to study. To be able to optimize the supply-chain on a global scale, fast models are needed to reduce computational time. Previous research has been made into the aggregation of factories, but the technique has not been tested against supply-chain problems. When evaluating the configuration of factories and their inter-transportation on a global scale, new insights can be gained about which parameters are important and how the aggregation fits to a supply-chain problem. The paper presents an interactive proof-of-concept model enabling testing of supply chain concepts by users and decision makers.

  • 126.
    Lidberg, Simon
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Optimizing real-world factory flows using aggregated discrete event simulation modelling: Creating decision-support through simulation-based optimization and knowledge-extraction2019In: Flexible Services and Manufacturing Journal, ISSN 1936-6582, E-ISSN 1936-6590Article in journal (Refereed)
    Abstract [en]

    Reacting quickly to changing market demands and new variants by improving and adapting industrial systems is an important business advantage. Changes to systems are costly; especially when those systems are already in place. Resources invested should be targeted so that the results of the improvements are maximized. One method allowing this is the combination of discrete event simulation, aggregated models, multi-objective optimization, and data-mining shown in this article. A real-world optimization case study of an industrial problem is conducted resulting in lowering the storage levels, reducing lead time, and lowering batch sizes, showing the potential of optimizing on the factory level. Furthermore, a base for decision-support is presented, generating clusters from the optimization results. These clusters are then used as targets for a decision tree algorithm, creating rules for reaching different solutions for a decision-maker to choose from. Thereby allowing decisions to be driven by data, and not by intuition. 

  • 127.
    Lidberg, Simon
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Skövde, Sweden.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Frantzén, Marcus
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Applying Aggregated Line Modeling Techniques to Optimize Real World Manufacturing Systems2018In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, p. 89-96Article in journal (Refereed)
    Abstract [en]

    The application of discrete event simulation methodology in the analysis of higher level manufacturing systems has been limited due to model complexity and the lack of aggregation techniques for manufacturing lines. Recent research has introduced new aggregation methods preparing for new approaches in the analysis of higher level manufacturing systems or networks. In this paper one of the new aggregated line modeling techniques is successfully applied on a real world manufacturing system, solving a real-world problem. The results demonstrate that the aggregation technique is adequate to be applied in plant wide models. Furthermore, in this particular case, there is a potential to reduce storage levels by over 25 %, through leveling the production flow, without compromising deliveries to customers.

  • 128.
    Lidberg, Simon
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Using Aggregated Discrete Event Simulation Models and Multi-Objective Optimization to Improve Real-World Factories2018In: Proceedings of the 2018 Winter Simulation Conference / [ed] M. Rabe, A. A. Juan, N. Mustafee, A. Skoogh, S. Jain, B. Johansson, IEEE, 2018, p. 2015-2024Conference paper (Refereed)
    Abstract [en]

    Improving production line performance and identifying bottlenecks using simulation-based optimization has been shown to be an effective approach. Nevertheless, for larger production systems which are consisted of multiple production lines, using simulation-based optimization can be too computationally expensive, due to the complexity of the models. Previous research has shown promising techniques for aggregating production line data into computationally efficient modules, which enables the simulation of higher-level systems, i.e., factories. This paper shows how a real-world factory flow can be optimized by applying the previously mentioned aggregation techniques in combination with multi-objective optimization using an experimental approach. The particular case studied in this paper reveals potential reductions of storage levels by over 30 %, lead time reductions by 67 %, and batch sizes reduced by more than 50 % while maintaining the delivery precision of the industrial system.

  • 129.
    Lind, Carl Mikael
    et al.
    Unit of Occupational Medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Sandsjö, Leif
    Faculty of Caring Science, Work Life and Social Welfare, University of Borås, Sweden / Design & Human Factors, Department of Industrial and Materials Science, Chalmers University of Technology, Gothenburg, Sweden.
    Mahdavian, Nafise
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV, Södertälje, Sweden.
    Olivares, Jozé Antonio Diaz
    Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Yang, Liyun
    Unit of Occupational Medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Forsman, Mikael
    Unit of Occupational Medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Prevention of Work: Related Musculoskeletal Disorders Using Smart Workwear – The Smart Workwear Consortium2019In: Human Systems Engineering and Design: Proceedings of the 1st International Conference on Human Systems Engineering and Design (IHSED2018): Future Trends and Applications, October 25-27, 2018, CHU-Université de Reims Champagne-Ardenne, France / [ed] Tareq Ahram, Waldemar Karwowski, Redha Taiar, Springer, 2019, Vol. 876, p. 477-483Conference paper (Refereed)
    Abstract [en]

    Adverse work-related physical exposures such as repetitive movements and awkward postures have negative health effects and lead to large financial costs. To address these problems, a multi-disciplinary consortium was formed with the aim of developing an ambulatory system for recording and analyzing risks for musculoskeletal disorders utilizing textile integrated sensors as part of the regular workwear. This paper presents the consortium, the Smart Workwear System, and a case study illustrating its potential to decrease adverse biomechanical exposure by promoting improved work technique. 

  • 130.
    Lingman, Simon
    et al.
    University of Skövde, School of Engineering Science.
    Einemo Swahn, Dennis
    University of Skövde, School of Engineering Science.
    Utveckla förbättringsunderlag och utöka utnyttjandegraden för en maskincell2019Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Detta examensarbete är utfört på RPC Superfos i Mullsjö och företaget tillverkar plastförpackningar till livsmedelsprodukter runtom i världen. RPC Superfos har ett uppsatt mål att det sammanlagda TAK/OEE-värdet för samtliga maskiner inte skall understiga 76,4 %. I dagsläget ligger många av maskincellerna på ett TAK/OEE-värde över målet, medan vissa ligger under 50 % vilket innebär att målet inte uppnås. Den maskincell som omfattas för projektet har lägst TAK/OEE-värde av samtliga maskinceller i fabriken. Syftet har varit att undersöka varför denna maskin inte uppnår företagets mål med ett TAK/OEE värde på 76,4 %. Efter att ha analyserat data över maskincellens stopp konstaterades att den bidragande orsaken till det låga TAK/OEE-värdet beror på ställtiden. Utifrån detta konstaterande har flera arbetsmetoder som frekvensstudier, intervjuer, SMED och spaghettidiagram använts för att presentera förbättringsförslag. Just ställtiden har valts som ett delmål för att fortsätta processen och genom en överenskommelse med företaget valdes att försöka reducera ställtiden från mediantiden 12h till 7h och detta skulle motsvara 42 % av den totala ställtiden på maskincellen. Metodvalen som tidigare nämnts beskrivs i referensramen och detta har gynnat det fortsatta arbetet med att försöka reducera ställtiden och därmed öka tillgängligheten för maskincellen. Under sju omställningar användes Genchi Genbutsu som arbetsmetod för att skapa en ökad förståelse över processen. Under samtliga omställningarsamlades data in med arbetsmetoden frekvensstudie där ställarnas aktiviteter kategoriserades för att identifiera beläggningen för varje aktivitet. Slutligen användes arbetsmetoden spaghettidiagram för att analysera och dokumentera ställarnas rörelser. 19 förbättringsförslag presenterades för personal på RPC Superfos, 10 utav förbättringsförslagen användes under en avslutande omställning. Resultatet från den avslutande omställningen jämfördes emot mediantiden för en omställning. Resultatet blev att omställningen tog 5 timmar, 10 minuter och 14 sekunder, vilket innebär en procentuell minskning av omställningstiden med 57,5%

  • 131.
    Linnéusson, Gary
    University of Skövde, School of Technology and Society.
    Literature Review on System Dynamics and Simulation2006Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This report is a literature review of System Dynamics (SD) and simulation, with enough information so the receiver can form a mental model of his own of what SD is.

    It started in the 1950s by Jay W. Forrester at the Massachusetts Institute of Technology, a devoted man that through his career always sought for practical applications of theory and gained skills. The key in why this new way of approaching problems in complex systems was its strength in capturing the dynamics, through the use of a computer to run a modeled system for a set of time and experimenting on which variables to modify or rearrange. SD methodology uses the theory of information feedbacks (i.e. closed loop structures), and the structure is based on the decision making processes or policies that interrelate in ways in the system. The model is valid if it shows the same dynamic behavior as the real system.

    In the report you will find some history and background to SD and the contents of the methodology, some application areas and two models; of which simulation is performed, one made by Jay Forrester and one very simple made by Gary Linnéusson.

    Main purpose with this review was to find out if SD could serve as a tool for simulating organizational development. If it can, further research on how will be part of a doctoral study project within CAPE, an Industrial Graduate School in Advanced Production Engineering. This due to that Arkivator Falköping AB is interested in to conduct an attendee in that School which would research on: "developing a method that would support management in decisions to develop their organization". The result of this review shows that SD can be a tool to treat that issue, one of very few tools that consider interrelations and interactions within organizational systems.

  • 132.
    Linnéusson, Gary
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Towards strategic development of maintenance and its effects on production performance: A hybrid simulation-based optimization framework2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Managing maintenance in manufacturing within an economical short-termism framework and taking the consequential long-term cost effects into account is hard. The increasing complexity of managing maintenance and its impact on the business results calls for more advanced methods to support long-term development through effective activities in the production system environment. This problem-based design science research has evolved into the novel concept of a hybrid simulation-based optimization (SBO) framework which integrates multi-objective optimization (MOO) with system dynamics (SD) and discrete-event simulation (DES) respectively. The objective is to support managers in their decision-making on the strategic and operational levels for prioritizing activities to develop maintenance and production performance.

    To exemplify the hybrid SBO framework this research presents an SD model for the study of the dynamic behaviors of maintenance performance and costs, which aims to illuminate insights for the support of the long-term strategic development of maintenance practices. The model promotes a system view of maintenance costs that includes the dynamic consequential costs as the combined result of several interacting maintenance levels throughout the constituent feedback structures. These levels range from the applied combination of maintenance methodologies to the resulting proactiveness in production, such as the ratio between planned and unplanned downtime, in continuous change based on the rate of improvements arising from root-cause analyses of breakdowns. The model creation and validation process have been supported by two large maintenance organizations operating in the Swedish automotive industry. Experimental results show that intended changes can have both short-term and longterm consequences, and that the system may show both obvious and hidden dynamic behavioral effects.

    The application of MOO distinguishes this work from previous research efforts that have mixed SD and DES. It presents a unique methodology to support more quantitative and objective-driven decision making in maintenance management, in which the outcome of an SD+MOO strategy selection process forms the basis for performance improvements on the operations level. This is achieved by framing the potential gains in operations in the DES+MOO study, as a result of the applied strategy in the SD model. All in all, this hybrid SBO framework allows pinpointing maintenance activities based on the analysis of the feedback behavior that generates less reactive load on the maintenance organization.

  • 133.
    Linnéusson, Gary
    et al.
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre. Production Engineering and Production Preparation, Arkivator AB, Falköping, Sweden .
    Jägstam, Mats
    University of Skövde, School of Technology and Society. University of Skövde, The Virtual Systems Research Centre.
    Näsström, C.
    Production Engineering and Production Preparation, Arkivator AB, Falköping, Sweden.
    Cutting Tool Management: A Dynamic Assessment of Opportunities for Improvement2008In: Proceedings of the 18th International Conference on Flexible Automation and Intelligent Manufacturing: FAIM 2008 / [ed] Leo J. de Vin, 2008, Vol. 2, p. 1084-1091Conference paper (Refereed)
    Abstract [en]

    Lack of time due to daily problems in need of attention restrains proper assessments of improvement opportunities. There is neither proper support at hand to deal with the dynamic complexity of human activity and systems in use. This paper explores if system dynamics simulation can be used to model tooling problems on a management problem level at a manufacturer and evaluates its use. System dynamics is a methodology designed to aid understanding of dynamically complex problems and increases decision making impact. The results focus on the achieved models which prove to have sense behaviour despite lack of thorough data. In conclusion the applied method provides with an analysis of complex problem situations applicable for a decision support, otherwise performed through good guessing. Main characteristics from reality have been included in model and an experimental laboratory to test future policies on achieved.

  • 134.
    Linnéusson, Gary
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    A hybrid simulation-based optimization framework for supporting strategic maintenance to improve production performance2020In: European Journal of Operational Research, ISSN 0377-2217, E-ISSN 1872-6860, Vol. 281, no 2, p. 402-414Article in journal (Refereed)
    Abstract [en]

    Managing maintenance and its impact on business results is increasingly complex, calling for more advanced operational research methodologies to address the challenge of sustainable decision-making. This problem-based research has identified a framework of methods to supplement the operations research/management science literature by contributing a hybrid simulation-based optimization framework (HSBOF), extending previously reported research.

    Overall, it is the application of multi-objective optimization (MOO) with system dynamics (SD) and discrete-event simulation (DES) respectively which allows maintenance activities to be pinpointed in the production system based on analyzes generating less reactive work load on the maintenance organization. Therefore, the application of the HSBOF informs practice by a multiphase process, where each phase builds knowledge, starting with exploring feedback behaviors to why certain near-optimal maintenance behaviors arise, forming the basis of potential performance improvements, subsequently optimized using DES+MOO in a standard software, prioritizing the sequence of improvements in the production system for maintenance to implement.

    Studying literature on related hybridizations using optimization the proposed work can be considered novel, being based on SD+MOO industrial cases and their application to a DES+MOO software.

  • 135.
    Linnéusson, Gary
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Justifying Maintenance Studying System Behavior: A Multipurpose Approach Using Multi-objective Optimization2017In: 35th International Conference of the System Dynamics Society 2017: Cambridge, Massachusetts, USA 16 - 20 July 2017 / [ed] J. Sterman, N. Repenning, Curran Associates, Inc., 2017, Vol. 2, p. 1061-1081Conference paper (Refereed)
    Abstract [en]

    Industrial maintenance includes rich internaldynamic complexity on how to deliver value. While the technical development hasprovided with applicable solutions in terms of reliability and condition basedmonitoring, managing maintenance is still an act of balancing, trying to pleasethe short-termism from the economic requirements and simultaneously address thenecessity of strategic and long-term thinking. By presenting an analysis tojustify maintenance studying system behavior, this paper exemplifies thecontribution of the combined approach of a system dynamics maintenanceperformance model and multi-objective optimization. The paper reveals howinsights from the investigation, of the near optimal Pareto-front solutions inthe objective space, can be drawn using visualization of performance ofselected parameters. According to our analysis, there is no return back to thesingle use of system dynamics; the contribution to the analysis of exploringsystem behavior, from applying multi-objective optimization, is extensive.However, for the practical application, the combined approach is not areplacement – but a complement. Where the interpretation of the visualizedPareto-fronts strongly benefits from the understanding of the model dynamics, inwhich important nonlinearities and delays can be revealed, and thus facilitateon the selected strategical path for implementation.

  • 136.
    Linnéusson, Gary
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Jönköping University, School of Engineering, Sweden.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Quantitative analysis of a conceptual system dynamics maintenance performance model using multi-objective optimisation2018In: Journal of Simulation, ISSN 1747-7778, E-ISSN 1747-7786, Vol. 12, no 2, p. 171-189Article in journal (Refereed)
  • 137.
    Linnéusson, Gary
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Ng, Amos H. C.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Jönköping University, Sweden.
    Aslam, Tehseen
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Relating strategic time horizons and proactiveness in equipment maintenance: a simulation-based optimization study2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 1293-1298Article in journal (Refereed)
    Abstract [en]

    Identifying sustainable strategies to develop maintenance performance within the short-termism framework is indeed challenging. It requires reinforcing long-term capabilities while managing short-term requirements. This study explores differently applied time horizons when optimizing the tradeoff between conflicting objectives, in maintenance performance, which are: maximize availability, minimize maintenance costs, and minimize maintenance consequence costs. The study has applied multi-objective optimization on a maintenance performance system dynamics model that contains feedback structures that explains reactive and proactive maintenance behavior on a general level. The quantified results provide insights on how different time frames are conditional to enable more or less proactive maintenance behavior in servicing production.

  • 138.
    Liu, Yu
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Strand, Mattias
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    A Review of Simulation Based Life Cycle Assessment in Manufacturing Industry2018In: Advances in Manufacturing Technology XXXII: Proceedings of the 16th International Conference on Manufacturing Research, incorporating the 33rd National Conference on Manufacturing Research, September 11 – 13, 2018, Skövde, Sweden / [ed] Peter Thorvald, Keith Case, Amsterdam, Berlin, Washington,DC: IOS Press, 2018, Vol. 8, p. 381-386Conference paper (Refereed)
    Abstract [en]

    The manufacturing industry has a duty to minimize their environmental impact and more and more legislations include environmental impact evaluations from a life cycle perspective to avoid burden shift. Current manufacturing industry increase their use of computer-based simulations for optimizing production processes. In recent years, a number of studies have been published, combining simulations with life cycle assessments (LCA), to evaluate and minimize the environmental impact of production activities, as part of improving the production processes. Still, current knowledge concerning simulations for LCA is rather scattered. Therefore, this paper reviews relevant literature covering simulation based LCA for production development. The results of the review and cross comparison of papers are structured following the 6 categories in line with the ISO standard definition of LCA (goal formulation, scope definition, environmental impact assessment, data quality, level of modelling details, and model validation) and report the strengths and constraints of the reviewed studies. 

  • 139.
    Liu, Yu
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Syberfeldt, Anna
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Strand, Mattias
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Review of simulation-based life cycle assessment in manufacturing industry2019In: Production & Manufacturing Research, ISSN 2169-3277, Vol. 7, no 1, p. 490-502Article in journal (Refereed)
    Abstract [en]

    The manufacturing industry has a duty to minimize its environmental impact, and an increasing body of legislation mandates environmental impact evaluations from a life cycle perspective to prevent burden shift. The manufacturing industry is increasing its use of computer-based simulations to optimize production processes. In recent years, several published studies have combined simulations with life cycle assessments (LCAs) to evaluate and minimize the environmental impact of production activities. Still, current knowledge of simulations conducted for LCAs is rather disjointed. This paper accordingly reviews the literature covering simulation-based LCAs of production processes. The results of the review and cross-comparison of papers are structured in terms of seven elements in line with the ISO standard definition of LCA and report the strengths and limitations of the reviewed studies. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.

  • 140.
    Mahdavian, Nafise
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Development and Evaluation of Digital Ergonomics Tools to Assess Human Work in Real and Virtual Environments: Based on case studies of manual assembly in Swedish automotive companies2018Report (Other academic)
    Abstract [en]

    ‘Digital ergonomics tools’ is a term used in this research proposal to refer to tools that are used to assess human work in real and virtual environments, where ‘digital’ refers to the use of technology such as computers, sensors, simulation, and data processing, to achieve desired functionality and usability. Digital ergonomics tools are considered as part of the ‘digital factory’. In essence the digital factory is an advanced computer model that either represents a non-yet existing factory, or an existing factory. When the factory is realised, there is an information flow between the real and the digital factory. The digital factory can be used to be informed about status of running production, and to support product and manufacturing development activities to test different design scenarios in the digital model before realising the selected solutions in the real factory. Hence, the digital factory approach assists designers, engineers, ergonomists, and managers to get a better understanding of the current status of the factory, and offers a digital model for testing and deciding upon different design alternatives. In an ergonomics context, such status checks can be related to assessing current ergonomics loads of the work force, or related to ensuring appropriate ergonomics when workstations are introduced or modified due to new product type introductions. However, there is a need to develop and evaluate digital ergonomics tools that has the desired functionality and usability to be integrated in to the digital factory concept. This proposed research addresses those needs.

    The research contributes to advance knowledge about technology and methods for the assessment of human work in real and virtual environments. The research will be carried out in association with development and evaluation research projects in the area of digital ergonomics tools, such as digital human modelling (DHM) tools and smart workwear. Simulation and experiment based strategies will be used to gather data and extract new knowledge. The studies will be carried out both in simulation and laboratory environments at the University, as well as in case studies in manual assembly in Swedish automotive companies.

  • 141.
    Mahdavian, Nafise
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Lind, Carl Mikael
    Unit of Occupational medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Diaz Olivares, Jose Antonio
    Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Iriondo Pascual, Aitor
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Brolin, Erik
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Yang, Liyun
    Unit of Occupational medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Forsman, Mikael
    Unit of Occupational medicine, Karolinska Institutet, Stockholm, Sweden / Division of Ergonomics, KTH Royal Institute of Technology, Huddinge, Sweden.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV, Södertälje, Sweden.
    Effect of Giving Feedback on Postural Working Techniques2018In: Advances in Manufacturing Technology XXXII: Proceedings of the 16th International Conference on Manufacturing Research, incorporating the 33rd National Conference on Manufacturing Research, September 11–13, 2018, University of Skövde, Sweden / [ed] Peter Thorvald, Keith Case, Amsterdam, Netherlands: IOS Press, 2018, p. 247-252Conference paper (Refereed)
    Abstract [en]

    Working postures and movements affect work efficiency and musculoskeletal health. To reduce the biomechanical exposure in physically demanding settings, working techniques may be improved by giving instant ergonomic feedback to the operator. This study investigates if feedback can be used to decrease adverse postures and movements in assembly work. A prototype solution of a smart textile workwear was used on a trainee assembly line. Posture and movement signals of 24 trainee operators were sampled via the workwear, transferred to a tablet for analyses and used to provide feedback suggesting improvements of work technique. Two modes of feedback were tested. Every participant’s work technique was measured before and after receiving the feedback and the results were compared. For upper arm elevation angle ≥60, behaviour change is indicated, supporting a positive work technique change, and indicated a future usefulness of technical automatic feedback for operators.

  • 142.
    Marcus, Hesselgren
    et al.
    University of Skövde, School of Engineering Science.
    Vestberg, Victor
    University of Skövde, School of Engineering Science.
    Reducering av ställtider: Verktygshantering2018Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This final year project has been carried out at a legomanufacturing company and they work, among other things, with cutting-edge processing which this work has focused on. The production type at the company is usually called HVLV production. This means that the products they produce are often made for the first time and that the recurring work are few. Which results in long lead-times.

    The purpose of this final year project was to identify which activities that the operators spent the most time on and then select a focus area. Furthermore, map the selected focus area "setup", with time studies and spaghetti charts to define more specific goals. Reduce the number of tool-related activities that occur in a setup by 50%, reduce movements between machine and setup-location by 75% and reduce the search of tools during a setup by 50%. This were the goals that lay as a foundation for the final year project. To achieve these goals, some suggested improvements were made. A number of tools that always will be used in the machines, so-called standardtools were selected and implemented. Related tool lists with relevant information about the tools and their design have also been created in order to facilitate the operators work. The tools were selected with flexibility in focus to fit the HVLV production. This were made through comparing purchase price, the most purchased tools from their largest tool supplier, processing times and the operators own experience. Based on the standard tools a routine was made which the operators should follow, from programming until the operator is ready to start the machine.

    A review of previous work was made to see in what extent the selected standardtools could be used. This showed that 40% of the previously reviewed work could have been manufactured using only the selected standardtools. Furthermore, a theoretical comparison with previous mapping showed that with the standardtools and routine, the number of tool-related activities could be reduced by approximately 40%. This mostly due to the elimination of uncertainties regarding which tools and toolholders that were located in the machines. This also eliminated the search of tools where the target was 50% reduction. According to the mapping of the setups the operator made more transportations to the machine than the number of tools that were to be set. If the operators follow the routine and use the tool carrier, only one transportation to the machine is required after all the tools are set. This results in a great reduction of movements to and from the machine. The result shows that about 90% of the movements in one of the mapped setups had been reduced.

  • 143.
    Mattsson, Sandra
    et al.
    Chalmers University of Technology.
    Fast-Berglund, Åsa
    Chalmers University of Technology.
    Li, Dan
    Chalmers University of Technology.
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Forming a cognitive automation strategy for Operator 4.0 in complex assembly2018In: Computers & industrial engineering, ISSN 0360-8352, E-ISSN 1879-0550Article in journal (Refereed)
    Abstract [en]

    Due to today’s technological advances in the area of Industry 4.0, having a strategy for cognitive automation solutions is crucial. Operator 4.0, will have handle and manage different work tasks ranging from learning new tasks to solving difficult problems and initiate changes. To support the operator moving between these tasks a strategy for the design of cognitive automation solutions is needed. The suggested strategy has three steps: 1) select assembly phases, 2) choose level of cognitive automation carrier and 3) suggest cognitive automation content. It is important that the operator is part of the design and that the solution supports movement between the phases learning, operational and disruptive phases. The strategy could support manufacturing companies meeting challenges regarding social sustainability e.g. stress, attractive workplaces and demography changes as well as system transparency and complexity.

  • 144.
    Mattsson, Sandra
    et al.
    Chalmers University of Technology, Gothenburg, Sweden.
    Fast-Berglund, Åsa
    Chalmers University of Technology, Gothenburg, Sweden.
    Thorvald, Peter
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    A Relationship Between Operator Performance and Arousal in Assembly2016In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 44, p. 32-37Article in journal (Refereed)
    Abstract [en]

    In order to meet the challenges of future complex systems, manufacturing companies need to better understand how social sustainability affects the operator. One way of studying this is to investigate the possible relationships between operator performance and emotion in an assembly experiment. 60 participants took part in an experiment to investigate the relationships between operator performance and objective and subjective arousal. Results showed a weak relationship between operator performance and objective arousal but no significant relationship was found between performance and subjective arousal. The relationships indicate that further studies on operator emotion could be important to better assembly performance. A tool for doing this might be the Qsensor used in this experiment (measure of objective arousal). More studies are needed to further investigate found relationship and if objective emotion measures can be used to predict performance at assembly workstations.

  • 145.
    Mårdberg, Peter
    et al.
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Carlson, Johan S.
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Bohlin, Robert
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Delfs, Niclas
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Gustafsson, Stefan
    Fraunhofer-Chalmers Research Centre for Industrial Mathematics, Gothenburg, Sweden.
    Högberg, Dan
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Sweden.
    Using a formal high-level language and an automated manikin to automatically generate assembly instructions2014In: International Journal of Human Factors Modelling and Simulation, ISSN 1742-5549, Vol. 4, no 3/4, p. 233-249Article in journal (Refereed)
    Abstract [en]

    This paper presents an approach to automatically generate predetermined motion time system (PMTS) based assembly instruction lists from simulations within digital human modelling (DHM) software. A formal high-level instruction language is used to instruct an automated manikin to perform assembly operations. The manikin, the language and the assembled objects are composed into a discrete model. In a post-computational step, the model is used to construct PMTS instruction lists by mapping the manikin motions, assembled objects and the language instructions onto a set of PMTS keywords. The described approach is implemented in the DHM software IMMA and tested on industrial cases of manual assembly in the automotive industry.

  • 146.
    Nackfors, Glenn
    University of Skövde, School of Engineering Science.
    Factory optimization using DES2016Independent thesis Advanced level (degree of Master (One Year)), 15 credits / 22,5 HE creditsStudent thesis
    Abstract [en]

    Discrete Event Simulation (DES) has been a powerful tool for modeling and optimization of production lines for many years. Developing detailed models may be very time consuming and might also be computationally costly to execute, especially if optimization techniques are to be applied. Aggregation techniques, simplifying a detailed system into fewer objects, can be an effective method to reduce the required computational resources as well as a way to shorten the development time. An aggregated model can be used to identify the main constraints in a system, dimensioning inter-line buffers, and focus development activities on the critical issues from a system performance perspective.

    An aggregated model of a real-world plant wide production system has already been developed in the discrete event simulation software FACTS Analyzer. Due to the limitations of FACTS Analyzer this model was instead rebuilt using the discrete event simulation software Plant Simulation which, while less user friendly, has much more configuration options. This model is then validated against the FACTS Analyzer model to ensure accurate results that can be implemented on a real life system.

    In addition some typical optimization experiments are carried out on the Plant Simulation model and the results analyzed. The first of these optimizations alters the buffer sizes to find the minimum amount of buffer capacity needed to get the minimum lead time while maintaining the highest possible throughput. The second optimization uses the same parameters but also adds alteration of the batch size. Both of these optimizations shows that it is possible to get better results with lower settings on both the buffer capacity and batch size then the default value.

    At the end of the report the project is evaluated and conclusions are drawn on what can be improved in the model, such as adding more streamlined updating of variant sequence.  Additionally future experiments that can be interesting to look at is specified based upon the results from the project.  

  • 147.
    Nackfors, Glenn
    et al.
    University of Skövde, School of Engineering Science.
    Hodo, Damir
    University of Skövde, School of Engineering Science.
    Utveckling av ett standardiserat operatörsobjekt i plant simulation2015Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis work in automation technology at 30 credits is conducted at Volvo Cars Cooperation (VCC) in collaboration with the University of Skövde.

    With the current staffing method VCC are experiencing difficulties achieving an optimal utilization of operators as there has been difficult to ascertain how much work an operator can handle. Operators are an often overlooked part of simulation studies because they are complex to model. The completed thesis consists of developing a standardized operator object in the simulation software Plant Simulation, developed by Siemens. Using this object, it will be easier to staff optimally with respect to the number of work areas, operator skills and how many operators that are required for the given work areas.

    The existing VCC Plant Simulation library already has an object for operators. This operator object was used as the basis for the development of the new operator object. When developing the new object, data collection was made in form of both qualitative and quantitative data to find out what functionality the new object needed. The existing object was evaluated against the functionality requirements to determine what were needed to be added, removed or modified. Five main areas were considered important to develop: (1) operators that can work across two or more work areas, (2) walking time for operators, (3) learning effect, (4) the learning curve for operators and (5) operators who work on different shifts. The learning curve was only partly developed, but the other four areas were fully implemented.

    In order to test and analyze the object, three experiments were carried out using different case studies, where one of these cases studies was a real production line. The experimental design was jointly created with the VCC reference group and the University of Skövde. The main objectives of the experiments were to reduce the number of operators and increase throughput per hour. The result of the optimisation of the real production line showed that a significantly smaller staffing could be achieved without a major effect on the throughput.

    The results of the project were that a standardized operator object was developed according to the specifications and objectives set for the project. This object provides the ability to quickly and easily implement operators in a simulation model. To verify the applicability of the operator object, it was successfully imported and used for simulation-based optimisation in three different simulation models. The operator object also contains functionalities that provide more realistic operators, such as the walk time to the operations, operators that can work across several work areas and competence for operators as well as learning.

    The results of this project involve a simpler implementation of more realistic operators and thus lead to more realistic simulation models. 

  • 148.
    Ng, Amos H. C.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden.
    Pehrsson, Leif
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Volvo Car Corporation, Sweden.
    What Does Multi-Objective Optimization Have to Do with Bottleneck Improvement of Production Systems?2014In: Proceedings of The 6th International Swedish Production Symposium 2014 / [ed] Johan Stahre, Björn Johansson & Mats Björkman, 2014Conference paper (Refereed)
    Abstract [en]

    Bottleneck is a common term used to describe the process/operation/person that constrains the performance of the whole system. Since Goldratt introduced his theory of constraint, not many will argue about the importance of identifying and then improving the bottleneck, in order to improve the performance of the entire system. Nevertheless, there exist various definitions of bottleneck, which make bottleneck identification and improvement not a straightforward task in practice. The theory introduced by Production Systems Engineering (PSE) that the bottleneck of a production line is where the infinitesimal improvement can lead to the largest improvement of the average throughput, has provided an inspirational and rigorous way to understand the nature of bottleneck. This is because it conceptually puts bottleneck identification and improvement into a single task. Nevertheless, it is said that a procedure to evaluate how the efficiency increase of each machine would affect the total performance of a line is hardly possible in most practical situations. But is this true?In this paper, we argue how multi-objective optimization fits nicely into the theory introduced by PSE and hence how it can be developed into a practical bottleneck improvement methodology. Numerical results from a real-world application study on a highly complex machining line are provided to justify the practical applicability of this new methodology.

  • 149.
    Ng, Amos H. C.
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Shaaban, Sabry
    Department of Strategy, ESC La Rochelle, La Rochelle, France.
    Bernedixen, Jacob
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Studying unbalanced workload and buffer allocation of production systems using multi-objective optimisation2017In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 55, no 24, p. 7435-7451Article in journal (Refereed)
    Abstract [en]

    Numerous studies have investigated the effects of unbalanced service times and inter-station buffer sizes on the efficiency of discrete part, unpaced production lines. There are two main disadvantages of many of these studies: (1) only some predetermined degree of imbalance and patterns of imbalance have been evaluated against the perfectly balanced configuration, making it hard to form a general conclusion on these factors; (2) only a single objective has been set as the target, which neglects the fact that different patterns of imbalance may outperform with respect to different performance measures. Therefore, the aim of this study is to introduce a new approach to investigate the performance of unpaced production lines by using multiple-objective optimisation. It has been found by equipping multi-objective optimisation with an efficient, equality constraints handling technique, both the optimal pattern and degree of imbalance, as well as the optimal relationship among these factors and the performance measures of a production system can be sought and analysed with some single optimisation runs. The results have illustrated that some very interesting relationships among the key performance measures studied, including system throughput, work-in-process and average buffer level, could only be observed within a truly multi-objective optimisation context. While these results may not be generalised to apply to any production lines, the genericity of the proposed simulation-based approach is believed to be applicable to study any real-world, complex production lines.

  • 150. Ng, Amos H. C.
    et al.
    Urenda Moris, Matias
    Svensson, Jacob
    Multi-Objective Simulation Optimization for Production Systems Design using FACTS Analyser2008In: Proceedings of the 2nd Swedish Production Symposium, 2008, p. 101-109Conference paper (Refereed)
    Abstract [en]

    This paper proposes a new general method for supporting production systems design within the context of Multi-objective Simulation Optimisation. Under this framework, different Production Control Mechanisms can be compared based on their optimal settings, which will be illustrated with a pedagogical simple flow line as well as an engines assembly line in automotive industry. Results from these case studies have provided significant insight into the importance of applying MOSO for Multi-Criteria Decision Making in general production systems design. At the same time, it also outlines the concept of applying significant dominance to handle uncertainty from stochastic simulation output, which has been implemented into a Web-based DES system called FACTS Analyser, specifically designed for conceptual factory design, analysis and optimisation.

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