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  • 601.
    von Dewall, Johannes
    et al.
    University of Skövde, School of Engineering Science.
    Johansson-Näslund, Markus
    University of Skövde, School of Engineering Science.
    Hållfasthetssimulering av hydrauliska högtryckskopplingar2018Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Hydraulic FEM ½" high pressure couplings are studied with the purpose of establishing an effective methodology that can be used to predict the strength of the couplings. The methodology consists of finite element analyzes (FEA) and is validated by experimental pressure tests, performed on the FEM ½” couplings pairs.  Using FEA, the couplings solid mechanical behavior and maximum load ability can be viewed virtual, reducing the need for experimental tests and gives the potential for optimized products. The work is performed at Parker Hannifin AB in Skovde.

    Experimental tests are performed on 20 FEM ½” couplings pairs, to understand the solid mechanical behavior of the couplings until failure occurs, and to predict the maximum pressure that can be applied. The experimental structure and performance is based on the method Design of Experiments (DOE). Critical components are identified based on the results from the experimental tests, which are then studied more closely through FEA. The analysis are validated based on the applied material model, and data collected during the experimental tests.

    From the experimental tests it is shown that the components: ball cage, guide and plug housing are the components in which failure occur. In case of failure, two failure modes appear as common, that the ball cage is worn apart and that the guide burst, both types of failure modes occur at a similar pressure. The analysis for the guide and ball cage corresponds with the experimental outcomes. Differences occurs however when looked at the deformations, in which the plug housing shows the largest deviation when compared to the experimental results.

    The usage of FE-models appears to be appropriate for predicting and evaluating the mechanical strengths of the couplings during pressure loads. The analysis are however entirely dependent on the input data, where an incorrect material model generates incorrect results. The relationship is shown for the plug housing, which lack the mechanical properties related to curing processes.

  • 602.
    Vuoluterä, Fredrik
    et al.
    University of Skövde, School of Engineering Science.
    Carlén, Oliver
    University of Skövde, School of Engineering Science.
    Analysis of material flow and simulation-based optimization of transportation system: The combination of simulation and Lean to evaluate and design a transportation system2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The thesis has been performed in cooperation with a Swedish manufacturing company. The manufacturing site of the company is currently implementing a new machine layout in one of its workshops. The new layout will increase the product flow to another workshop on the site. The goal of the thesis was to evaluate the current transportation system and suggest viable alternatives for the future product flow. By means of discrete event simulation these alternative solutions would be modelled and subsequently optimized to determine if their performance is satisfactory. An approximated investment cost of the solutions would also be estimated.

    By performing a literature review and creating a frame of reference, a set of relevant methodologies were selected to provide a foundation to the project. Following these methodologies, the current state of transportation was identified and mapped using Value Stream Mapping. Necessary data from the current flow was identified and collected from the company computer systems. This data was deemed partly inaccurate and further verification was needed. To this end, a combination of Genchi Genbutsu, assistance from onsite engineers and a time study was used to verify the unreliable data points. The data sets from the time study and the company data which was deemed valid were represented by statistical distributions to provide input for the simulation models.

    Two possible solutions were picked for evaluation, an automated guided vehicle system and a tow train system. With the help of onsite personnel, a Kaizen Event was performed in which new possible routing for the future flow was evaluated. A set of simulation models portraying the automated guided vehicle system and the tow train system were developed with the aid of simulation software. The results from these models showed a low utilization of both systems. A new set of models were developed, which included all the product flows between the workshops. The new flows were modelled as generic pallets with the arrival distribution based on historical production data. This set of models were then subject for optimization with regard to the work in process and lead time of the system. The results from the optimization indicates the possibility to reduce the overall work in process by reducing certain buffer sizes while still maintaining the required throughput. These solutions were not deemed to be ready for implementation due to the low utilization of the transportation systems. The authors instead recommend expanding the scope of the system and including other product flows to reach a high utilization.

  • 603.
    Walander, Tomas
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Chalmers University of Technology.
    Influences of temperature, fatigue and mixed mode loading on the cohesive properties of adhesive layers2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns some aspects that have influence on the strength of adhesive layers. The strength is determined by the stress deformation-relation of the layer. This relation is also referred to as cohesive law. The aspects having influence on the cohesive laws that are studied in this work are temperature, fatigue, multi-axial fatigue and mixed mode loading.

    For each aspect, a model is developed that can be used to describe the influence of the aspects on the cohesive laws numerically, e.g. by using the finite element method. These models are shown to give good agreement with the experimental results when performing simulations that aims at reproducing the experiments. For the aspect of temperature, a FE-model is suggested that can be used to simulate the mechanical behaviour in pure mode loadings at any temperature within the evaluated temperature span. Also, a damage law for modelling high cycle fatigue in a bonded structure in multi-axial loading is presented. Lastly, a new experimental set-up is presented for evaluating strength of adhesives during mixed mode loading. The set-up enables loading with a constant mode-mix ratio and by the experimental results, a potential model for describing the mechanical behaviour of the evaluated adhesive is presented.

  • 604.
    Walander, Tomas
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Eklind, Alexander
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Carlberger, Thomas
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fatigue damage of adhesive layers: experiments and models2014In: Procedia Materials Science, ISSN 2211-8128, Vol. 3, p. 829-834Article in journal (Refereed)
    Abstract [en]

    Mode I fatigue crack growth at load levels close to the threshold is studied with the aim of improving the understanding of the fatigue properties. We also aim at identifying a suitable damage evolution law for large-scale simulation of built-up structures. A fatigue test rig is designed where up to six specimens are tested simultaneously. Each specimen is evaluated separately indicating the specimen-to-specimen variation in fatigue properties. A rubber-based and a PUR-based adhesive are tested. The two adhesives represent adhesives with very different material properties; the rubber adhesive is a stiff structural adhesive and the PUR adhesive is a soft modular adhesive. The experiments are first evaluated using a traditional Paris’ law approach. Inspired by an existing damage evolution law, a modified damage evolution law is developed based on only three parameters. The law is implemented as a user material in Abaqus and the parameters are identified. The results from simulations show a very good ability to reproduce the experimental data. With this model of fatigue damage, a zone of damage evolves at the crack tip. The extension of this zone depends on the stiffness of the adherends; stiffer adherends leads to a larger damage zone. This means that the rate of crack growth depends on the stiffness of the adherends. Thus, not only the state at the crack tip governs the rate of crack growth. This is in contrast to the results of a model based on Paris’ law where only the state at the crack tip, through the energy release rate, governs the rate of crack growth. This indicates that the threshold value of the energy release rate may depend on the stiffness of the adherends.

  • 605.
    Walander, Tomas
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Eklind, Alexander
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Carlberger, Thomas
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Stigh, Ulf
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Rietz, Andreas
    Scania STC, Södertälje, Sweden.
    Prediction of mixed-mode cohesive fatigue strength of adhesively bonded structure using Mode I data2016In: International Journal of Adhesion and Adhesives, ISSN 0143-7496, E-ISSN 1879-0127, Vol. 66, p. 15-25Article in journal (Refereed)
    Abstract [en]

    A cohesive zone model is presented for analyzing the fatigue life of an adhesive joint in the range of 104–106 load cycles. The parameters of the model are derived from Mode I double cantilever beam experiments. Fatigue experiments with adhesively joined components from the automotive industry are performed, and the results from the experiments are compared to the results of simulations. The error in the predicted fatigue strength is of the same order as the statistical deviation of the fatigue experiments, indicating that the simulation method produces acceptable predictions of the fatigue strength for applications in e.g. early product development.

  • 606.
    Wallin Johansson, Daniel
    University of Skövde, School of Engineering Science.
    KARTLÄGGNING AV VÄRDEFLÖDEOCH IDENTIFIERING AV SLÖSERIERFÖR ÄGGPRODUKTION2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Dava Foods in Skara has been the industry for this final year project where they processing egg in different conditions. For this project has the process where they manufacture protein drinks as they sold to the stores been in focus. The main goals for the project were to bring a value streaming map of the current state of the production and suggest improvements based on this map. The second goal was to find which types of wastes that occur and find improvements.

    To create an understanding of the existing process, an analysis was made where the stream was observed. Observations and interviews were used to collect data for the project. The analysis of the exciting process has been based on for the implementation stage.

    During the implementation stage was different tools used to collect data. PDCA has been a tool where was followed during the whole project. The value streaming map has been a central tool which was used to bring out a value streaming map. To collect the times which was needed for the value streaming map a stopwatch was used.

    The project result in different improvement proposal where many of the proposals included was to automate the processes. One solution was to change the operator against a robot cell which would streamline the process which would result in a lower throughput. Change machine was another solution where many stops occur. A full automation concept was suggested to combine these two suggestions, where both a robot and a machine was bought. The last suggestion of the value streaming map was about to just produces one product at a time. Within the wastes were three suggestions given where maintenance was the best solution to reduce the wastes. To determine which one of the suggestions was the best solution a pick chart was used to priority how hard the suggestion was and benefit.

    The conclusion was to purchasing the machine where stops frequently occur. This suggestion would create a higher efficiency in the production at the same time where the condition about price would give the best solution. Improvements of maintenance would also result as the best solution to increase the efficiency for the current machines and reduce the number of stops.

  • 607.
    Wang, Jiacheng
    et al.
    University of Skövde, School of Engineering Science.
    Domingos, Luzaisso
    University of Skövde, School of Engineering Science.
    Developing of Data Logging System for Flow Test Station in Industrial Laboratory2016Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    CEJN is a leading transnational company with long history and professional background providing high-tech quick connect products in global market. The headquarters of the com-pany in Skövde, Sweden, is the birthplace and core location of the entire corporation. In the headquarters, the engineer tests their products at their flow test laboratory. In the laboratory, there are flow test stations for all product ranges. Within them, the most basic are flow test benches for air, water and hydraulic oil products. The flow test benches are aim to test the products under International/Swedish standard conditions to determine the performance.

    This project is aimed in upgrading the test benches by engineering both hardware and soft-ware, to achieve higher level of automation of the data logging system used in the lab. All three test benches were designed and installed following requirements in corresponding in-ternational standards. The principles of testing are similar, but they are not developed from the same era, and the automation level of each test bench differs. As a result, the need of up-grading in the benches is different.

    In the laboratory, the recorded test results are reorganized and processed by a report genera-tor developed on Microsoft Excel. The Excel report generator is used for organize test results, calibrate the deviation of the instruments, calculate the flow coefficient of the product, gener-ate performance diagrams of the products, generate test reports for different purpose of use, and save the test data and results on the server of the company.

    Above all, an upgrade of the data logging system for the three flow test benches was needed. Depending on the conditions of each test bench, the project is implemented and designed the following three parts:

    • A hardware upgrading (flow rate computer) for the air flow test benchA new signal indicating device for replacing the old flow rate computer is purchased from Italy by the company. The new instrument contains filter function to stabilize the flow rate value.

    • A software upgrading (Excel report generator) for all the test benchesVisual Basic for Applications (VBA) programming language is used for developing functions such as data communication, signal decoding and user interface developing in Excel.

    • Develop of an automated data visualizing system for the air flow test benchData communication from the new instrument to a PC through serial port and Mod-bus RTU interface is established. The data visualizing function is compiled in the Ex-cel report generator for the air flow test, realized by VBA programming.

  • 608.
    Wang, Lihui
    et al.
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Mohammed, Abdullah
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Wang, Xi Vincent
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Schmidt, Bernard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Energy-efficient robot applications towards sustainable manufacturing2018In: International journal of computer integrated manufacturing (Print), ISSN 0951-192X, E-ISSN 1362-3052, Vol. 31, no 8, p. 692-700Article in journal (Refereed)
    Abstract [en]

    The cloud technology provides sustainable solutions to the modern industrial robotic cells. Within the context, the objective of this research is to minimise the energy consumption of robots during assembly in a cloud environment. Given a robot path and based on the inverse kinematics and dynamics of the robot from the cloud, a set of feasible configurations of the robot can be derived, followed by calculating the desirable forces and torques on the joints and links of the robot. Energy consumption is then calculated for each feasible configuration along the path. The ones with the lowest energy consumption are chosen. Since the energy-efficient robot configurations lead to reduced overall energy consumption, this approach becomes instrumental and can be applied to energy-efficient robotic assembly. This cloud-based energy-efficient approach for robotic applications can largely enhance the current practice as demonstrated by the results of three case studies, leading towards sustainable manufacturing.

  • 609.
    Wang, Lihui
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. KTH Royal Institute of Technology, Stockholm, Sweden.
    Mohammed, Abdullah
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Wang, Xi Vincent
    KTH Royal Institute of Technology, Stockholm, Sweden.
    Schmidt, Bernard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Recent Advancements of Smart Manufacturing: An Example of Energy-Efficient Robot2016In: Proceedings of the 26th International Conference on Flexible Automation and Intelligent Manufacturing, 2016, p. 884-892Conference paper (Refereed)
    Abstract [en]

    The cloud technology provides sustainable solutions to the modern industrial robotic cells. Within the context, the objective of this research is to minimise the energy consumption of robots during assembly in a cloud environment. Given a trajectory and based on the inverse kinematics and dynamics of a robot from the cloud, a set of feasible configurations of the robot can be derived, followed by calculating the desirable forces and torques on the joints and links of the robot. Energy consumption is then calculated for each feasible configuration along the trajectory. The ones with the lowest energy consumption are chosen. Since the energy-efficient robot configurations lead to reduced overall energy consumption, this approach becomes instrumental and can be applied to energy-efficient robotic assembly.

  • 610.
    Wang, Lihui
    et al.
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Production Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Schmidt, Bernard
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Givehchi, Mohammad
    Department of Production Engineering, Royal Institute of Technology, Stockholm, Sweden.
    Adamson, Göran
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Robotic Assembly Planning and Control with Enhanced Adaptability through Function Blocks2015In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 77, no 1-4, p. 705-715Article in journal (Refereed)
    Abstract [en]

    Manufacturing companies today need to maintain a high level of flexibility and adaptability to deal with uncertainties on dynamic shop floors, including e.g. cutting tool shortage, part supply interruption, urgent job insertion or delay, and machine unavailability. Such uncertainties are characteristic in component assembly operations. Addressing the problem, we propose a new method using function blocks to achieve much improved adaptability in assembly planning and robot control. In this paper, we propose to use event-driven function blocks for robotic assembly, aiming to plan trajectory and execute assembly tasks in real-time. It is envisioned that this approach will achieve better adaptability if applied to real-world applications.

  • 611.
    Wang, Lihui
    et al.
    Department of Production Engineering, KTH Royal Institute of Technology, Sweden.
    Wang, Wei
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Department of Production Engineering, KTH Royal Institute of Technology, Sweden.
    Liu, Dawei
    AVIC Chengdu Aircraft Industrial (Group) Ltd. Co., China.
    Dynamic feature based adaptive process planning for energy-efficient NC machining2017In: CIRP annals, ISSN 0007-8506, E-ISSN 1726-0604, Vol. 66, no 1, p. 441-444Article in journal (Refereed)
    Abstract [en]

    This paper presents a dynamic feature based adaptive process planning approach that can optimise machining cost, machining time and energy consumption simultaneously. The material removal volume of a dynamic feature is refined into non-overlapping volumes removed respectively by a single machining operation in which unified cutting mode is performed. Benefitting from this refinement, energy consumption is estimated analytically based on instantaneous cutting force as a function of real cutting parameters. Moreover, the cutting parameters assigned to each machining operation are optimised effectively in the unified cutting mode. This novel approach enhances the energy efficiency of NC machining through process planning.

  • 612.
    Wang, Wei
    et al.
    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.
    Sánchez de Ocãna Torroba, Adrian
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Improved Human-Robot Collaboration Through Simulation-Based Optimization2019In: Advances in Manufacturing Technology XXXIII: Proceedings of the 17th International Conference on Manufacturing Research, incorporating the 34th National Conference on Manufacturing Research, 10–12 September 2019, Queen’s University, Belfast, UK / [ed] Yan Jin, Mark Price, Amsterdam: IOS Press, 2019, Vol. 9, p. 153-158, article id 10.3233/ATDE190027Conference paper (Refereed)
    Abstract [en]

    In order to pursue the dream combination of human flexibility and robot automation, human robot collaboration (HRC) is increasingly being investigated through academic research and industrial scenarios. HRC involves several challenges ranging from safety and comfort of the human to process efficiency and cost of robot operation. Achieving the right balance between these aspects is critical to implementing a safe, profitable and sustainable HRC environment. In this paper,we propose the use of simulation-based optimization (SBO) for assembly task allocation and scheduling for a HRC working cell in which an industrial robot assists a human worker. The list of product assembly operations are classified according to the capability of human worker and robot, and the sequencing constraints on them are the initial inputs of the method. The operators’ ergonomic load scores and cycletime of the assembly process are achieved by simulation. The optimized solutions are sorted to find the trade-offs between ergonomics and cycle time. We demonstratethe feasibility of the proposed approach through an industrial case study.

  • 613.
    Werner, Elin
    University of Skövde, School of Engineering Science.
    Materialanalys & optimering av hydrauliska högtryckskopplingar med hjälp av simuleringar2018Independent thesis Basic level (professional degree), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Optimizing the burst pressure with finite element analysis is done on the FEM ½” coupling at Parker Hannifin AB. The critical components which is the ball cage, guide and plug housing are in focus. A more accurate material analysis is done to make a more real-based data of the material in the coupling.  

    After being in contact with the company that performs the hardening of the component, the entire plug housing is assumed to be hardened. For more information about material data, static pressure test is performed on a coupling. The measured strains from the tests are compared to the strains in the simulations. The tensile strength and hardness coefficient on the guide and ball cage can be adjusted slightly from the tests, but the result has several uncertainties. 

    The number of balls can be reduced, numbers of balls between 15 and 12 are investigated at request from the company. Analysis of how hardening of the material for the guide is done and hardening of the surface for the plug housing. 

    The smallest deformation occurs when hardening the guide. The ball cage clearly demonstrated minor deformations and stresses as the number of balls is reduced from 15 to 12 balls in the coupling. To reduce the burst pressure on the plug housing, it is recommended to harden the surface with a 27 % harder surface than the current. Due to estimated values of material data on hardened surface, more information is needed to determine the thickness needed on the surface of the hardening when having 12 balls in the coupling. 

  • 614.
    Wiemann, Marcus
    University of Skövde, School of Engineering Science.
    Implementering av människa-robot samarbetscell i en labbmiljö: Implementation av människa-robot samarbete2019Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In a previous final year project, a study was carried out on how a robotic collaborative cell would work in a laboratory environment. In Arvid Bobergs "HRC Implementation in laboratory environment" the cell would be developed on behalf of Eurofins to work with chemical and microbiological analyses in agriculture, food and environment. To verify the suggested solutions, an implementation would need to be designed in a physical environment.

    The main purpose of the project was to develop a collaborative cell that would perform tasks in a lab environment. For this purpose, a station, work operations and components have been developed and implemented at ASSAR. The station has been programmed to showcase the possibilities the robot has to offer in a collaborative cell with the help of ABB Robot Studio and online programming. The choice of the robot was if possible, to make use of ABB's YuMi robot. This is because it was the robot that the pre-study that the work is based on used in its model and built its theory on and because the work of the feasibility study is the foundation of this project.

    The implementation of the station has been completed in steps to be able to test different structure and obtain a better understanding of the robot's characteristics and what it is capable to perform in relation to range and flexibility. To create the more advanced features of the program was used offline programming in ABB Robot Studio combined with the help of online programming. The functions become too advanced to write in a TeachPendant because there will be long lines of code to create the advanced functions that the robot uses to perform its tasks.

    The work at ASSAR has led to several different solutions being developed and thought over until a concept has been chosen and implemented at ASSAR. This in the form of a collaborative cell that showcases various functions to perform tasks in a lab environment using the YuMi robot from ABB and a worktable created during the project.

    The project has achieved several goals for the work, but some have not been achieved, because of delays that have arisen during the course of the project. The delays have made the workflow change and the result that the author has tried to achieve has changed to develop a collaborative cell and give a result to the project.

  • 615.
    Wiktorsson, Magnus
    et al.
    KTH Royal Insitute of Technology, Dept of Sustainable Production Development, Södertälje, Sweden.
    Noh, Sang Do
    Sungkyunkwan University, Dept of Industrial Engineering, Suwon, South Korea.
    Bellgran, Monica
    KTH Royal Insitute of Technology, Dept of Sustainable Production Development, Södertälje, Sweden.
    Hanson, Lars
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre. Scania CV, Global Industrial Development, Södertälje, Sweden.
    Smart Factories: South Korean and Swedish examples on manufacturing settings2018In: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, p. 471-478Article in journal (Refereed)
    Abstract [en]

    What constitutes a company's capabilities to develop a Smart Factory? South Korean and Swedish perspectives are here illustrated by company examples of smart factory solutions and related strategic aspects of their digitalization. It is concluded that the "smart-factory-capability" of a manufacturing company is integrated with its corporate production systems and includes perspectives on application areas, value adding processes as well as enabling technologies. It is furthermore challenged by the transformational inabilities of legacy systems. By its concrete examples is use and financial benefits, the paper contributes to the definition of the smart factory and its corresponding development scheme. 

  • 616.
    Winzig, Manuel
    University of Skövde, School of Engineering Science.
    Modelling and optimisation of a production system including Human-Automation collaboration2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis is part of the ManuWork project. ManuWork is led by the European Union trying to cope with recent emerging challenges in the field of automation engineering. One of these challenges is to satisfy customer demands of high product variability and product specification. This urges production lines to become highly flexible while being efficient at the same time. To solve this problem, one approach is to introduce human-automation collaboration to warrant both, efficiency and flexibility. This work supports this goal by developing a simulation model including human-automation collaboration to find out its benefits and requirements. The first step was performing a literature review on the state of the art of the theory of line balancing. It was also investigated how today’s optimisation methods solve complex line balancing problems. Based on this, a simulation model of a production line of a Swedish manufacturer was built in the simulation software FACTS. This simulation model was then complemented by various features step by step. Besides the human-automation collaboration, the final model also contains influences like human task time deviation, machine disruption, buffer size and worker performance. The production system was then studied in detail using simulation software. By conducting a simulation study information about the system’s behaviour was obtained. The influence of the system’s features on the critical parameters throughput, work in process and lead time was studied. The behaviour of the human-automation collaboration was studied in-depth. It was shown what requirements are to be met to realise a beneficial implementation and quantified which improvements can be expected by an implementation. At the end, the project is concluded, and an outlook on possible future researches is given.

  • 617.
    Wolak, Peter
    et al.
    University of Skövde, School of Engineering Science.
    Johansson, Mattias
    University of Skövde, School of Engineering Science.
    Buffer optimisation of a packaging line using Volvo GTO's flow simulation methodology2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    With the rapid development of computers and their proven usability in manufacturing environments, simulation-based optimisation has become a recognised tool for proposing near-optimal results related to manufacturing system design and improvement. As a world-leading manufacturer within their field, Volvo GTO in Skövde, Sweden is constantly seeking internal development and has in recent years discovered the possibilities provided by flow simulation. The main aim of this thesis is to provide an optimal buffer size of a new post-assembly and packaging line (Konpack) yet to be constructed. A by-product of the flow simulation optimisation project in form of a flow simulation process evaluation was also requested.

    The simulation project started with a pre-study including the development of the frame of reference and an analysis of the literature focused on merging Lean philosophy with simulation-based optimisation. The simulation model was built based on both historical and estimated data. The optimisation results showed different buffer size alternatives depending on the throughput to be achieved, these are discussed, and near-optimal solutions presented for decision-making. Additionally, four experiments were carried out, both contributing to the model’s credibility as well as providing new and valuable insight to the stakeholders. The conclusions drawn from the optimisation and experiments indicate that Konpack will be able to meet the established throughput goals, provided that the suggested near-optimal solutions are considered. The experiments also unanimously point to the fact that Konpack has a built-in overcapacity, utilizable by optimising certain suggested input parameters.

    Additionally, an evaluation of the completeness of the standard simulation process employed by Volvo GTO is provided, concluding that no major changes are needed. Nevertheless, there is always room for improvement. Hence, future work regarding the flow simulation process at Volvo GTO is proposed.

  • 618.
    Wänerberger, Alexander
    et al.
    University of Skövde, School of Engineering Science.
    Said, Sayyed Hamid
    University of Skövde, School of Engineering Science.
    Lagerstyrning och prognostisering av råmateriallagret2014Independent thesis Basic level (university diploma), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Production to customer order usually requires keeping a supply warehouse. Increased customer demands for short lead-times require that materials must be in stock. This result in increasing stock levels in a company leads to more capital tied up and simultaneously leads to poorer yields. To avoid keeping a large storage warehouse whilst keeping a good service requires an effective inventory control.

    The purpose of this project is to find out how the demand looks like in the current situation of the company and to develop an appropriate forecasting method and calculation model against a certain pace for inventory control. The methods mentioned in this work are the ABC analysis, calculation of safety stock and forecasting methods.

    The results from this work will answer the objectives of the project aims. A variety of analyzes and experiments shall be used to investigate what type of forecasting method that the company should use. The methods and theories raised in the report also aims to be used by similar companies. The aim of the selected forecasting method is also to lead to a better base, from which better forecast precision is one part in order to improve the inventory management. This has, as far as possible, been put in relation to the working methods used in the company today. Some of the work has been to find out how much demand changes during the lead times, i.e. from the ordering of raw material until the material is in the raw material stock. This has also been used to compare forecasting methods against the present approach.

    Because the company wants to expand its production, a calculation model has also been developed. This model indicates the inventory level to a desired pace, i.e. demand level.

  • 619.
    Xia, Johnny
    University of Skövde, School of Engineering Science.
    A NEW STUDY OF UNBALANCED PRODUCTION LINE WITH OPTIMIZATION2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This project is a continuous research of a topic well-known in the literature, namely, the performance study of unbalanced unpaced production system. In the literature, there were many studies that investigated the statistical outputs of an unbalanced production line using simulation. This project focuses on researching the outputs like average buffer level and idle time that are rarely studied in previous research by using optimization tools from discrete event simulation software FACTS.The models used in the article (Shaaban & McNamara, 2009) have been used as a guideline during the development of the simulation models for this project. Two simulation models were created, each using different discrete event simulation software, namely FACTS analyzer and Plant simulation. Those simulation models fulfills its role in verification & validation stage, with their statistical outputs compared to each other and with Shaaban and McNamara’s results. After verification & validation comes optimization of those simulation models, by using optimization tools from FACTS.The research area expanded during the optimization phase. Originally Shaaban et.al analyzed unbalanced production line with one fixed value of coefficient of variation. In order to expand the view on the properties of an unbalanced production line, three more coefficient variation were added with total of four in this project. As a result, 12 optimization results were created at the end of this project. Each optimization has 30 000 iterations to ensure its convergence.The first step of analysis is done by locating all Pareto-optimal solutions with optimization tools in FACTS. The raw data of all solutions are later transferred and converted into EXCEL files. Using scatter graph and putting all outputs against each other in EXCEL, it creates visual graph that can be used to analyze and to investigate interesting behavior in an unbalanced production line.The analysis on the optimization results showed several interesting behaviors from production line with different settings. One being that if a production line possess worse coefficient of variation than its competition. By raising the inter-stage buffer level of the production line with inferior coefficient of variation, it can achieve the same level, if not greater outputs than its competitor who possess better coefficient of variation. The other interesting behavior are optimization results with highest outputs in regard of either idle time or average buffer level, with deep analyzation using optimization tools from FACTS. Certain operation time pattern and inter-stage buffer pattern could be observed from those results.

  • 620.
    Yousefi, Milad
    et al.
    Department of Production and Transportation Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
    Yousefi, Moslem
    Department of Mechanical Engineering, Islamic Azad University, Roudehen Branch, Roudehen, Iran.
    Fathi, Masood
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Fogliatto, Flavio
    Department of Production and Transportation Engineering, Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil.
    Patient visit forecasting in an emergency department using a deep neural network approach2019In: Kybernetes, ISSN 0368-492X, E-ISSN 1758-7883Article in journal (Refereed)
    Abstract [en]

    This study aims to investigate factors affecting daily demand in an emergency department (ED) and to provide a forecasting tool in a public hospital for horizons of up to 7 days.In this study, first the important factors to influence the demand in EDs were extracted from literature then the relevant factors to our study are selected. Then a deep neural network is applied for constructing a reliable predictor.Although many statistical approaches have been proposed for tackling this issue, better forecasts are viable through employing the abilities of machine learning algorithms. Results indicate that the proposed approach outperforms statistical alternatives available in the literature such as multiple linear regression (MLR), autoregressive integrated moving average (ARIMA), support vector regression (SVR), generalized linear models (GLM), generalized estimating equations (GEE), seasonal ARIMA (SARIMA) and combined ARIMA and linear regression (LR) (ARIMA-LR).We applied this study in a single ED to forecast the patient visits. Applying the same method in different EDs may give us a better understanding of the performance of the model. The same approach can be applied in any other demand forecasting after some minor modifications.To the best of our knowledge, this is the first study to propose the use of long short-term memory (LSTM) for constructing a predictor of the number of patient visits in EDs.

  • 621.
    Zhang, Xiaoyang
    et al.
    Faculty of Engineering, Environment and Computing, Coventry University, Coventry, United Kingdom.
    Lu, Xin
    Faculty of Engineering, Environment and Computing, Coventry University, Coventry, United Kingdom.
    Wang, Sheng
    Faculty of Engineering, Environment and Computing, Coventry University, Coventry, United Kingdom.
    Wang, Wei
    University of Skövde, School of Engineering Science. University of Skövde, The Virtual Systems Research Centre.
    Li, Weidong
    Faculty of Engineering, Environment and Computing, Coventry University, Coventry, United Kingdom.
    A multi-sensor based online tool condition monitoring system for milling process2018In: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, p. 1136-1141Article in journal (Refereed)
    Abstract [en]

    Tool condition monitoring has been considered as one of the key enabling technologies for manufacturing optimization. Due to the high cost and limited system openness, the relevant developed systems have not been widely adopted by industries, especially Small and Medium-sized Enterprises. In this research, a cost-effective, wireless communication enabled, multi-sensor based tool condition monitoring system has been developed. Various sensor data, such as vibration, cutting force and power data, as well as actual machining parameters, have been collected to support efficient tool condition monitoring and life estimation. The effectiveness of the developed system has been validated via machining cases. The system can be extended to wide manufacturing applications.

  • 622.
    Águila Rodríguez, Guillermo
    et al.
    University of Skövde, School of Engineering Science.
    del Álamo Alcalde, Adrián
    University of Skövde, School of Engineering Science.
    Identification of machine tools´ locations2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The scope of this thesis will be focused on the machine FORMA Z1 which is one ofthe most functional amongst the sort of machines currently available in the market. Itprovides faster tool changes besides a huge variety of tool layouts with the possibility ofmaking a product with one only set up. Furthermore, the combi-beam rotation capability,together with dual sets of tools, give to the machine an exceptional competence.Through this project, some of the shortcomings in the usability of the machine are evaluatedto be able to give an accurate solution to provide it of extra functionalities, thusacquiring better efficiency during the performance. This solution consists of the developmentof a device which will aid the operator during the tool arrangement of the machine.The solution includes a platform with a laser that will point out where the operator mustplace the corresponding tool. The system will know where to locate it because the realmachine would generate an XML file which would contain all necessary data. All thisdata will be read by a computer and send it to the microcontroller that will control allthe system.The solution proposed improves the throughput and reduces the time needed in the bendingprocess increasing the facility in the process of bending metal sheet. However, thereare some disadvantages on the implementation of this device. The new machine wouldbe more expensive and the software would be changed to include the new system and theprogram that reads the XML document.

  • 623.
    Öberg, Daniel
    University of Skövde, School of Engineering Science.
    Utveckling av ett cykelskåp anpassat för stadsmiljö2019Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The project began as an open question in collaboration with a consulting company in product development to develop a more secure parking for bicycles. Therefore, a comprehensive feasibility study was performed to evaluate the bicycle values and to see potential development opportunities for different types of bicycle parking. Blidsberg mekaniska is a company that manufactures bicycle parking and other types of outdoor environment products. They were involved in the work and wanted to expand their range with a new bike box. The designprocess started with a marketreasearch with the aim to analyze cycle parks in a pre-study. During the pre-study demands was researched and formed a requirement specification. The creative work in the development of a new cycle park was helped by many creative methods that generated many concepts that later was compared in a matrix. The final concept was able to compete with the existing solutions. The result was a combination of already existing solutions. The bicycle locker does not take up more space than is necessary for most bicycles to fit in. The bicycle locker is modularly adapted and can therefore be placed more space efficiently in different places. A light indication on the handle indicates whether the bicycle locker is free or occupied and opened with a tag that is scanned on a RFID-reader.

  • 624.
    Öhnström, Magnus
    et al.
    University of Skövde, School of Engineering Science.
    Göhlin, Victor
    University of Skövde, School of Engineering Science.
    Förbättring av passivdämpande hörselskydd2017Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Magnus Öhnström and Victor Göhlin are two design engineer students from the University of Skövde. To obtain their bachelor in engineering they have completed a study for Hellberg Safety to improve the sound dampening effect in their passive earmuffs. The goal is a standard shell that can be optimized for different grades of sound dampening. In order to obtain knowledge a pilot study was performed. This included an analysis of one of the major competitor’s products. In order to reach the goal, the shell, absorber and cushion had to be examined. Modifications made were evaluated with an Acoustic Test Fixture (ATF) located in Hellbergs sound lab. Different modifications were combined, evaluated and sent to Germany for further evaluation. From the given results parts of the shell were further developed.

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