his.sePublikasjoner
Endre søk
Begrens søket
1234567 51 - 100 of 657
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 51.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Multi-objective Optimization and Analysis of the Inventory Management Model2014Inngår i: Proceedings of the 2014 Summer Simulation Multiconference, Society for Computer Simulation International , 2014, Vol. 46, s. 99-106Konferansepaper (Fagfellevurdert)
  • 52.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Karlsson, Ingemar
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Integrating system dynamics and multi-objective optimisation for manufacturing supply chain analysis2014Inngår i: International Journal of Manufacturing Research, ISSN 1750-0605, Vol. 9, nr 1, s. 27-57Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to address the dilemma of supply chain management (SCM) within a truly Pareto-based multi-objective context. This is done by introducing an integration of system dynamics and multi-objective optimisation. An extended version of the well-known pedagogical SCMproblem, the Beer Game, originally developed at MIT since the 1960s, has been used as the illustrative example. As will be discussed in the paper, the integrated multi-objective optimisation and system dynamics model has been shown to be very useful for revealing how the parameters in the Beer Game affect the optimality of the three common SCM objectives, namely, the minimisation of inventory cost, backlog cost, and the bullwhip effect.

  • 53.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Karlsson, Ingemar
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Integrating System Dynamics and Multi-Objective Optimization for Manufacturing Supply Chain Analysis2012Inngår i: Proceedings of the 5th Swedish Production symposium (SPS'12), 2012, s. 433-441Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to address the dilemma of Supply Chain Management (SCM) within a truly Pareto-based multi-objective context. This is done by introducing an integration of System Dynamics and Multi-Objective Optimization. Specifically, the paper contrasts local optimization with global optimization for SCM in which optimal trade-off solutions in the entity level, i.e. optimizing the supply chain from the perspectives of individual (local) entities. e.g., supplier, factory, distributor and retailer, are collected and compared to those obtained from an overall supply chain level (global) optimization. An extended version of the well-known pedagogical SCM problem, the Beer Game, originally developed at MIT since the 1960s, has been used as the illustrative example. As will be discussed in the paper, the integrated multi-objective optimization and system dynamics model has been shown to be very useful for revealing that how the parameters in the Beer Game affect the optimality of the three common SCM objectives, namely, the minimization of inventory, backlog, and the bullwhip effect.

  • 54.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H.C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Strategy evaluation using system dynamics and multi-objective optimization for an internal supply chain2015Inngår i: 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, Piscataway, NJ, USA: IEEE Press, 2015, s. 2033-2044Konferansepaper (Fagfellevurdert)
    Abstract [en]

    System dynamics, which is an approach built on information feedbacks and delays in the model in order to understand the dynamical behavior of a system, has successfully been implemented for supply chain management problems for many years. However, research within in multi-objective optimization of supply chain problems modelled through system dynamics has been scares. Supply chain decision making is much more complex than treating it as a single objective optimization problem due to the fact that supply chains are subjected to the multiple performance measures when optimizing its process. This paper presents an industrial application study utilizing the simulation based optimization framework by combining system dynamics simulation and multi-objective optimization. The industrial study depicts a conceptual system dynamics model for internal logistics system with the aim to evaluate the effects of different material flow control strategies by minimizing total system work-on-process as wells as total delivery delay.

  • 55.
    Aslam, Tehseen
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Syberfeldt, Anna
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Pehrsson, Leif
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Volvo Car Engine, Manufacturing Research and Concepts, Skövde, Sweden.
    Urenda-Moris, Mathias
    Uppsala University, Ångströmlaboratoriet, Uppsala, Sweden.
    Towards an industrial testbed for holistic virtual production development2018Inngår i: 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, s. 369-374Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Virtual production development is adopted by many companies in the production industry and digital models and virtual tools are utilized for strategic, tactical and operational decisions in almost every stage of the value chain. This paper suggest a testbed concept that aims the production industry to adopt a virtual production development process with integrated tool chains that enables holistic optimizations, all the way from the overall supply chain performance down to individual equipment/devices. The testbed, which is fully virtual, provides a mean for development and testing of integrated digital models and virtual tools, including both technical and methodological aspects.

  • 56.
    Asplund, Anna
    et al.
    Högskolan i Skövde, Forskningscentrum för Informationsteknologi. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Persson, Anne
    Högskolan i Skövde, Forskningscentrum för Informationsteknologi. Högskolan i Skövde, Institutionen för kommunikation och information.
    Hilletofth, Per
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    E-procurement beyond the buyer cost perspective2010Inngår i: Proceedings of the 22nd NOFOMA Conference: Logistics and Supply Chain Management in a Globalised Economy / [ed] Jan Stentoft Arlbjørn, University of Southern Denmark , 2010, s. 483-498Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Purpose: The objective of this paper is to provide and argue for a comprehensive view of e-procurement that involves both the buyer and suppliers and that goes beyond looking at mere cost reductions on the buyer side. More specifically, the paper describes benefits and barriers of implementing e-procurement solutions for both buyers and suppliers.

    Design/methodology/approach: This paper reports on a literature review combined with a case study. The case is a public organization in Sweden, which prepares to implement an e-procurement solution. Interviews were also conducted with a selection of suppliers to the case organization.

    Findings: In e-procurement literature, drivers and barriers are often viewed only from the perspective of a buying organization. Benefits are mainly cost-related for the buying organization, while barriers often include suppliers. It is proposed that benefits and barriers should include both buyers and suppliers. The literature review and the case study findings form the basis for further investigation into this problem area.

    Research limitations/implications: This study focuses on a public organization in Sweden. Yet, it could have implications for many public or private organizations considering implementing e-procurement systems.

    Practical implications: This research suggest that organizations to a greater extent should take the supplier´s side into account when implementing e-procurement solutions.

    Originality/Value: The study highlights a full cycle view on e-procurement taking both buyer and supplier into account.

  • 57.
    Ayani, Mikel
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ganebäck, Maria
    Projektengagemang Industri & Energi Sverige AB, El & Automation, Skövde, Sweden.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Digital Twin: Applying emulation for machine reconditioning2018Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 72, s. 243-248Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Old machine reconditioning projects extend the life length of machines with reduced investments, however they frequently involve complex challenges. Due to the lack of technical documentation and the fact that the machines are running in production, they can require a reverse engineering phase and extremely short commissioning times. Recently, emulation software has become a key tool to create Digital Twins and carry out virtual commissioning of new manufacturing systems, reducing the commissioning time and increasing its final quality. This paper presents an industrial application study in which an emulation model is used to support a reconditioning project and where the benefits gained in the working process are highlighted.

  • 58.
    Ayani, Mikel
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Birtic, Martin
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Optimizing Cycle Time and Energy Efficiency of a Robotic Cell Using an Emulation Model2018Inngår i: 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, Vol. 8, s. 411-416Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Industrial automated systems are mostly designed and pre-adjusted to always work at their maximum production rate. This leaves room for important energy consumption reductions considering the production rate variations of factories in reality. This article presents a multi-objective optimization application targeting cycle time and energy consumption of a robotic cell. A novel approach is presented where an existing emulation model of a fictitious robotic cell was extended with low-level electrical components modeled and encapsulated as FMUs. The model, commanded by PLC and Robot Control software, was subjected to a multi-objective optimization algorithm in order to find the Pareto front between energy consumption and production rate. The result of the optimization process allows selecting the most efficient energy consumption for the robotic cell in order to achieve the required cycle.

  • 59.
    Backlund, Per
    et al.
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gustavsson, Martin
    Högskolan i Skövde.
    Johannesson, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lebram, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Sjörs, Emmy
    Högskolan i Skövde.
    SIDH: A Game-Based Architecture for a Training Simulator2009Inngår i: International Journal of Computer Games Technology, ISSN 1687-7047, E-ISSN 1687-7055, artikkel-id 472672Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Game-based simulators, sometimes referred to as "lightweight" simulators, have benefits such as flexible technology and economic feasibility. In this article, we extend the notion of a game-based simulator by introducing multiple screen view and physical interaction. These features are expected to enhance immersion and fidelity. By utilizing these concepts we have constructed a training simulator for breathing apparatus entry. Game hardware and software have been used to produce the application. More important, the application itself is deliberately designed to be a game. Indeed, one important design goal is to create an entertaining and motivating experience combined with learning goals in order to create a serious game. The system has been evaluated in cooperation with the Swedish Rescue Services Agency to see which architectural features contribute to perceived fidelity. The modes of visualization and interaction as well as level design contribute to the usefulness of the system.

  • 60.
    Backlund, Per
    et al.
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Engström, Henrik
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Johannesson, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lebram, Mikael
    Högskolan i Skövde, Institutionen för kommunikation och information. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Games for traffic education: An experimental study of a game-based driving simulator2010Inngår i: Journal Simulation & Gaming, ISSN 1046-8781, E-ISSN 1552-826X, Vol. 41, nr 2, s. 145-169Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, the authors report on the construction and evaluation of a game-based driving simulator using a real car as a joystick. The simulator is constructed from off-the-shelf hardware and the simulation runs on open-source software. The feasibility of the simulator as a learning tool has been experimentally evaluated. Results are reported from an experimental study of games and traffic safety performed in an advanced gaming environment. During car simulator sessions, the authors collected data about different traffic safety variables, such as speed, headway distance, and lane change behavior, from 70 participants. The data were analyzed to investigate possible individual learning effects and differences between groupings of participants. The experiment shows clear, positive, individual learning effects for all traffic safety variables analyzed. The authors also made a qualitative analysis of the participants’ perception of the simulator as a learning tool. From the results, it is concluded that a game-based simulation can be used to enhance learning in driving education.

  • 61.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Andersson, Martin
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Metamodel-based prediction of performance metrics for bilevel parameter tuning in MOEAs2016Inngår i: 2016 IEEE Congress on Evolutionary Computation (CEC), New York: IEEE, 2016, s. 1909-1916Konferansepaper (Fagfellevurdert)
    Abstract [en]

    We consider a bilevel parameter tuning problem where the goal is to maximize the performance of a given multi-objective evolutionary optimizer on a given problem. The search for optimal algorithmic parameters requires the assessment of several sets of parameters, through multiple optimization runs, in order to mitigate the effect of noise that is inherent to evolutionary algorithms. This task is computationally expensive and therefore, in this paper, we propose to use sampling and metamodeling to approximate the performance of the optimizer as a function of its parameters. While such an approach is not unheard of, the choice of the metamodel to be used still remains unclear. The aim of this paper is to empirically compare 11 different metamodeling techniques with respect to their accuracy and training times in predicting two popular multi-objective performance metrics, namely, the hypervolume and the inverted generational distance. For the experiments in this pilot study, NSGA-II is used as the multi-objective optimizer for solving ZDT problems, 1 through 4.

  • 62.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Aslam, Tehseen
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Deb, Kalyanmoy
    Department of Electrical and Computer Engineering, Michigan State University, East Lansing, USA.
    Generalized higher-level automated innovization with application to inventory management2015Inngår i: European Journal of Operational Research, ISSN 0377-2217, E-ISSN 1872-6860, Vol. 243, nr 2, s. 480-496Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper generalizes the automated innovization framework using genetic programming in the context of higher-level innovization. Automated innovization is an unsupervised machine learning technique that can automatically extract significant mathematical relationships from Pareto-optimal solution sets. These resulting relationships describe the conditions for Pareto-optimality for the multi-objective problem under consideration and can be used by scientists and practitioners as thumb rules to understand the problem better and to innovate new problem solving techniques; hence the name innovization (innovation through optimization). Higher-level innovization involves performing automated innovization on multiple Pareto-optimal solution sets obtained by varying one or more problem parameters. The automated innovization framework was recently updated using genetic programming. We extend this generalization to perform higher-level automated innovization and demonstrate the methodology on a standard two-bar bi-objective truss design problem. The procedure is then applied to a classic case of inventory management with multi-objective optimization performed at both system and process levels. The applicability of automated innovization to this area should motivate its use in other avenues of operational research.

  • 63.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Deb, Kalyanmoy
    BEACON Center for the Study of Evolution in Action, Department of Electrical and Computer Engineering, Michigan State University, USA.
    Metaheuristic Techniques2017Inngår i: Decision Sciences: Theory and Practice / [ed] Raghu Nandan Sengupta, Aparna Gupta, Joydeep Dutta, Boca Raton: CRC Press, 2017, s. 693-750Kapittel i bok, del av antologi (Fagfellevurdert)
  • 64.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Deb, Kalyanmoy
    Michigan State University, USA.
    Temporal Innovization: Evolution of Design Principles Using Multi-objective Optimization2015Inngår i: Proceedings of the 8th International Conference on Evolutionary Multi-Criterion Optimization (EMO 2015), Springer, 2015, Vol. 9018, s. 79-93Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Multi-objective optimization yields multiple solutions each of which is no better or worse than the others when the objectives are conflicting. These solutions lie on the Pareto-optimal front which is a lower-dimensional slice of the objective space. Together, the solutions may possess special properties that make them optimal over other feasible solutions. Innovization is the process of extracting such special properties (or design principles) from a trade-off dataset in the form of mathematical relationships between the variables and objective functions. In this paper, we deal with a closely related concept called temporal innovization. While innovization concerns the design principles obtained from the trade-off front, temporal innovization refers to the evolution of these design principles during the optimization process. Our study indicates that not only do different design principles evolve at different rates, but that they start evolving at different times. We illustrate temporal innovization using several examples.

  • 65.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gaur, Abhinav
    Department of Electrical and Computer Engineering, Michigan State University, USA.
    Deb, Kalyanmoy
    Department of Electrical and Computer Engineering, Michigan State University, USA.
    Khare, Vineet
    Amazon Development Centre (India) Pvt. Ltd., Bengaluru, India.
    Chougule, Rahul
    Department of Mechanical Engineering, Walchand College of Engineering, Sangli, India.
    Bandyopadhyay, Pulak
    General Motors R&D Center, Warren, USA.
    Development, analysis and applications of a quantitative methodology for assessing customer satisfaction using evolutionary optimization2015Inngår i: Applied Soft Computing, ISSN 1568-4946, E-ISSN 1872-9681, Vol. 30, s. 265-278Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Consumer-oriented companies are getting increasingly more sensitive about customer's perception of their products, not only to get a feedback on their popularity, but also to improve the quality and service through a better understanding of design issues for further development. However, a consumer's perception is often qualitative and is achieved through third party surveys or the company's recording of after-sale feedback through explicit surveys or warranty based commitments. In this paper, we consider an automobile company's warranty records for different vehicle models and suggest a data mining procedure to assign a customer satisfaction index (CSI) to each vehicle model based on the perceived notion of the level of satisfaction of customers. Based on the developed CSI function, customers are then divided into satisfied and dissatisfied customer groups. The warranty data are then clustered separately for each group and analyzed to find possible causes (field failures) and their relative effects on customer's satisfaction (or dissatisfaction) for a vehicle model. Finally, speculative introspection has been made to identify the amount of improvement in CSI that can be achieved by the reduction of some critical field failures through better design practices. Thus, this paper shows how warranty data from customers can be utilized to have a better perception of ranking of a product compared to its competitors in the market and also to identify possible causes for making some customers dissatisfied and eventually to help percolate these issues at the design level. This closes the design cycle loop in which after a design is converted into a product, its perceived level of satisfaction by customers can also provide valuable information to help make the design better in an iterative manner. The proposed methodology is generic and novel, and can be applied to other consumer products as well.

  • 66.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Ng, Amos
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Deb, Kalyanmoy
    Department of Electrical and Computer Engineering, Michigan State University, East Lansing, USA.
    On the Performance of Classification Algorithms for Learning Pareto-Dominance Relations2014Inngår i: Proceedings of the 2014 IEEE Congress on Evolutionary Computation (CEC), IEEE Press, 2014, s. 1139-1146Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Multi-objective evolutionary algorithms (MOEAs)are often criticized for their high-computational costs. Thisbecomes especially relevant in simulation-based optimizationwhere the objectives lack a closed form and are expensive toevaluate. Over the years, meta-modeling or surrogate modelingtechniques have been used to build inexpensive approximationsof the objective functions which reduce the overall number offunction evaluations (simulations). Some recent studies however,have pointed out that accurate models of the objective functionsmay not be required at all since evolutionary algorithms onlyrely on the relative ranking of candidate solutions. Extendingthis notion to MOEAs, algorithms which can ‘learn’ Paretodominancerelations can be used to compare candidate solutionsunder multiple objectives. With this goal in mind, in thispaper, we study the performance of ten different off-the-shelfclassification algorithms for learning Pareto-dominance relationsin the ZDT test suite of benchmark problems. We considerprediction accuracy and training time as performance measureswith respect to dimensionality and skewness of the training data.Being a preliminary study, this paper does not include results ofintegrating the classifiers into the search process of MOEAs.

  • 67.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    An empirical comparison of metamodeling strategies in noisy environments2018Inngår i: Proceedings of the Genetic and Evolutionary Computation Conference (GECCO-2018) / [ed] Hernan Aguirre, New York, NY, USA: ACM Digital Library, 2018, s. 817-824, artikkel-id 3205509Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Metamodeling plays an important role in simulation-based optimization by providing computationally inexpensive approximations for the objective and constraint functions. Additionally metamodeling can also serve to filter noise, which is inherent in many simulation problems causing optimization algorithms to be mislead. In this paper, we conduct a thorough statistical comparison of four popular metamodeling methods with respect to their approximation accuracy at various levels of noise. We use six scalable benchmark problems from the optimization literature as our test suite. The problems have been chosen to represent different types of fitness landscapes, namely, bowl-shaped, valley-shaped, steep ridges and multi-modal, all of which can significantly influence the impact of noise. Each metamodeling technique is used in combination with four different noise handling techniques that are commonly employed by practitioners in the field of simulation-based optimization. The goal is to identify the metamodeling strategy, i.e. a combination of metamodeling and noise handling, that performs significantly better than others on the fitness landscapes under consideration. We also demonstrate how these results carry over to a simulation-based optimization problem concerning a scalable discrete event model of a simple but realistic production line.

  • 68.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    On the scalability of meta-models in simulation-based optimization of production systems2015Inngår i: 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, Piscataway, NJ: IEEE Press, 2015, s. 3644-3655Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Optimization of production systems often involves numerous simulations of computationally expensive discrete-event models. When derivative-free optimization is sought, one usually resorts to evolutionary and other population-based meta-heuristics. These algorithms typically demand a large number of objective function evaluations, which in turn, drastically increases the computational cost of simulations. To counteract this, meta-models are used to replace expensive simulations with inexpensive approximations. Despite their widespread use, a thorough evaluation of meta-modeling methods has not been carried out yet to the authors' knowledge. In this paper, we analyze 10 different meta-models with respect to their accuracy and training time as a function of the number of training samples and the problem dimension. For our experiments, we choose a standard discrete-event model of an unpaced flow line with scalable number of machines and buffers. The best performing meta-model is then used with an evolutionary algorithm to perform multi-objective optimization of the production model.

  • 69.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Trend Mining: A Visualization Technique to Discover Variable Trends in the Objective Space2019Inngår i: Evolutionary Multi-Criterion Optimization: 10th International Conference, EMO 2019, East Lansing, MI, USA, March 10-13, 2019, Proceedings / [ed] Kalyanmoy Deb, Erik Goodman, Carlos A. Coello Coello, Kathrin Klamroth, Kaisa Miettinen, Sanaz Mostaghim, Patrick Reed, Cham, Switzerland: Springer, 2019, Vol. 11411, s. 605-617Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Practical multi-objective optimization problems often involve several decision variables that influence the objective space in different ways. All variables may not be equally important in determining the trade-offs of the problem. Decision makers, who are usually only concerned with the objective space, have a hard time identifying such important variables and understanding how the variables impact their decisions and vice versa. Several graphical methods exist in the MCDM literature that can aid decision makers in visualizing and navigating high-dimensional objective spaces. However, visualization methods that can specifically reveal the relationship between decision and objective space have not been developed so far. We address this issue through a novel visualization technique called trend mining that enables a decision maker to quickly comprehend the effect of variables on the structure of the objective space and easily discover interesting variable trends. The method uses moving averages with different windows to calculate an interestingness score for each variable along predefined reference directions. These scores are presented to the user in the form of an interactive heatmap. We demonstrate the working of the method and its usefulness through a benchmark and two engineering problems.

    Fulltekst tilgjengelig fra 2020-02-03 00:00
  • 70.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Deb, Kalyanmoy
    Department of Electrical and Computer Engineering, Michigan State University, USA.
    Data mining methods for knowledge discovery in multi-objective optimization: Part A - Survey2017Inngår i: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 70, s. 139-159Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Real-world optimization problems typically involve multiple objectives to be optimized simultaneously under multiple constraints and with respect to several variables. While multi-objective optimization itself can be a challenging task, equally difficult is the ability to make sense of the obtained solutions. In this two-part paper, we deal with data mining methods that can be applied to extract knowledge about multi-objective optimization problems from the solutions generated during optimization. This knowledge is expected to provide deeper insights about the problem to the decision maker, in addition to assisting the optimization process in future design iterations through an expert system. The current paper surveys several existing data mining methods and classifies them by methodology and type of knowledge discovered. Most of these methods come from the domain of exploratory data analysis and can be applied to any multivariate data. We specifically look at methods that can generate explicit knowledge in a machine-usable form. A framework for knowledge-driven optimization is proposed, which involves both online and offline elements of knowledge discovery. One of the conclusions of this survey is that while there are a number of data mining methods that can deal with data involving continuous variables, only a few ad hoc methods exist that can provide explicit knowledge when the variables involved are of a discrete nature. Part B of this paper proposes new techniques that can be used with such datasets and applies them to discrete variable multi-objective problems related to production systems. 

  • 71.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Deb, Kalyanmoy
    Department of Electrical and Computer Engineering, Michigan State University, USA.
    Data mining methods for knowledge discovery in multi-objective optimization: Part B - New developments and applications2017Inngår i: Expert systems with applications, ISSN 0957-4174, E-ISSN 1873-6793, Vol. 70, s. 119-138Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The first part of this paper served as a comprehensive survey of data mining methods that have been used to extract knowledge from solutions generated during multi-objective optimization. The current paper addresses three major shortcomings of existing methods, namely, lack of interactiveness in the objective space, inability to handle discrete variables and inability to generate explicit knowledge. Four data mining methods are developed that can discover knowledge in the decision space and visualize it in the objective space. These methods are (i) sequential pattern mining, (ii) clustering-based classification trees, (iii) hybrid learning, and (iv) flexible pattern mining. Each method uses a unique learning strategy to generate explicit knowledge in the form of patterns, decision rules and unsupervised rules. The methods are also capable of taking the decision maker's preferences into account to generate knowledge unique to preferred regions of the objective space. Three realistic production systems involving different types of discrete variables are chosen as application studies. A multi-objective optimization problem is formulated for each system and solved using NSGA-II to generate the optimization datasets. Next, all four methods are applied to each dataset. In each application, the methods discover similar knowledge for specified regions of the objective space. Overall, the unsupervised rules generated by flexible pattern mining are found to be the most consistent, whereas the supervised rules from classification trees are the most sensitive to user-preferences. 

  • 72.
    Bandaru, Sunith
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Smedberg, Henrik
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A parameterless performance metric for reference-point based multi-objective evolutionary algorithms2019Inngår i: GECCO '19: Proceedings of the Genetic and Evolutionary Computation Conference / [ed] Manuel López-Ibáñez, New York, NY, USA: ACM Digital Library, 2019, s. 499-506Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Most preference-based multi-objective evolutionary algorithms use reference points to articulate the decision maker's preferences. Since these algorithms typically converge to a sub-region of the Pareto-optimal front, the use of conventional performance measures (such as hypervolume and inverted generational distance) may lead to misleading results. Therefore, experimental studies in preference-based optimization often resort to using graphical methods to compare various algorithms. Though a few ad-hoc measures have been proposed in the literature, they either fail to generalize or involve parameters that are non-intuitive for a decision maker. In this paper, we propose a performance metric that is simple to implement, inexpensive to compute, and most importantly, does not involve any parameters. The so called expanding hypercube metric has been designed to extend the concepts of convergence and diversity to preference optimization. We demonstrate its effectiveness through constructed preference solution sets in two and three objectives. The proposed metric is then used to compare two popular reference-point based evolutionary algorithms on benchmark optimization problems up to 20 objectives.

    Fulltekst tilgjengelig fra 2020-08-01 00:00
  • 73.
    Barrera Diaz, Carlos Alberto
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Oscarsson, Jan
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lidberg, Simon
    Volvo Car Corporation, Skövde, Sweden.
    Sellgren, Tommy
    Volvo Car Corporation, Skövde, Sweden.
    A Study of Discrete Event Simulation Project Data and Provenance Information Management in an Automotive Manufacturing Plant2017Inngår i: Proceedings of the 2017 Winter Simulation Conference / [ed] W. K. V. Chan, A. D’Ambrogio, G. Zacharewicz, N. Mustafee, G. Wainer, E. Page, IEEE, 2017, , s. 12s. 4012-4023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Discrete Event Simulation (DES) project data management is a complex and important engineering activity which impacts on an organization’s efficiency. This efficiency could be decreased by the lack of provenance information or the unreliability of existing information regarding previous simulation projects, all of which complicates the reusability of the existing data. This study presents an analysis of the management of simulation projects and their provenance data, according to the different types of scenarios usually found at a manufacturing plant. A survey based on simulation projects at an automotive manufacturing plant was conducted, in order to categorize the information regarding the studied projects, map the available provenance data and standardize its management. This study also introduces an approach that demonstrates how a structured framework based on the specific data involved in the different types of scenarios could allow an improvement of the management of DES projects.

  • 74.
    Barrera Diaz, Carlos Alberto
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Oscarsson, Jan
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Lidberg, Simon
    Manufacturing Engineering, Research and Simulation, Volvo Car Corporation, Skövde, Sweden.
    Sellgren, Tommy
    Manufacturing Engineering, Research and Simulation, Volvo Car Corporation, Skövde, Sweden.
    Discrete Event Simulation Output Data-Handling System in an Automotive Manufacturing Plant2018Inngår i: Procedia Manufacturing, E-ISSN 2351-9789, Vol. 25, s. 8s. 23-30Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Discrete Event Simulation is a comprehensive tool for the analysis and design of manufacturing systems. Over the years, considerable efforts to improve simulation processes have been made. One step in these efforts is the standardisation of the output data through the development of an appropriate system which presents the results in a standardised way. This paper presents the results of a survey based on simulation projects undertaken in the automotive industry. In addition, it presents the implementation of an automated output data-handling system which aims to simplify the project’s documentation task for the simulation engineers and make the results more accessible for other stakeholders.

  • 75.
    Beheshtinia, Mohammad Ali
    et al.
    Department of Industrial Engineering, University of Semnan, Iran.
    Ahmadi, Bahar
    Department of Industrial Engineering, University of Semnan, Iran.
    Fathi, Masood
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A Genetic Algorithm with Multiple Populations to Reduce Fuel Consumption in Supply Chain2019Inngår i: International Journal of Transportation Engineering, ISSN 2322-259XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Reducing fuel consumption by transportation fleet in a supply chain, reduces transportation costs and consequently, the product final cost. Moreover, it reduces environmental pollution, and in some cases, it helps governments constitute less subsidies for fuels. In this paper, a supply chain scheduling is studied, with the two objective functions of minimizing the total fuel consumption, and the total order delivery time. After presenting the mathematical model of the problem, a genetic algorithm, named Social Genetic Algorithm (SGA) is proposed to solve it. The proposed algorithm helps decision makers determine the allocation of orders to the suppliers and vehicles and production and transportation scheduling to minimize total order delivery time and fuel consumption. In order for SGA performance evaluation, its results are compared with another genetic algorithm in the literature and optimal solution. Finally, a sensitivity analysis is performed on SGA. The results of comparisons also show the high performance of SGA. Moreover, by increasing the number of suppliers and vehicles and decreasing the number of orders, the value of the objective function is reduced.

  • 76.
    Bergman, Christian
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bäckstrand, Gunnar
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system. Swerea IVF AB, Stockholm.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Moestam, Lena
    Volvo Trucks GTT, Gothenburg.
    A tool to assist and evalute workstation design2013Inngår i: Proceedings of NES 2013, 45th Nordic Ergonomics & Human Factors Society conference, Iceland, August 2013, 2013Konferansepaper (Fagfellevurdert)
    Abstract [en]

    It can be argued that it is common that industrial workstations are “built” rather than purposefully designed with user and task requirements in mind. Afterwards, built-in problems typically need to be corrected, causing undesired costs and efforts. With the objective to assist workstation designers in avoiding most problems already in the design phase, a design support tool is being developed. The paper argues the need for such a tool and presents the fundamental tool functionality. Expected advantages are more efficient and ergonomic workstations and a more efficient design process with built-in learning and documentation.

  • 77.
    Bergman, Christian
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bäckstrand, Gunnar
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Swerea IVF AB, Gothernburg, Sweden.
    Moestam, Lena
    Volvo Group Trucks Operations, Gothenburg, Sweden.
    A Library Based Tool to Assist the Generative Activity in Workstation Design2014Inngår i: Advances in Ergonomics in Design, Usability & Special Populations: Part II / [ed] Francisco Rebelo and Marcelo Soares, AHFE Conference , 2014, s. 206-214Konferansepaper (Fagfellevurdert)
  • 78.
    Bergman, Christian
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ruiz Castro, Pamela
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, Lars
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Scania AB, Södertälje, Sweden.
    Implementation of Suitable Comfort Model for Posture and Motion Prediction in DHM Supported Vehicle Design2015Inngår i: Procedia Manufacturing, ISSN 2351-9789, Vol. 3, s. 3753-3758Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Driver-vehicle interaction analyses are done to ensure a successful vehicle design from an ergonomics perspective. Digital Human Modelling (DHM) tools are often used to support such verifications, particularly at early stages of the product development process. When verifying that a vehicle design accommodates the diversity of users and tasks, a DHM tool needs to be able to represent postures and motions that are likely under certain conditions. This functionality is essential so that the tool user will obtain objective and repeatable simulation results. The DHM tool IMMA (Intelligently Moving Manikins) predicts postures and motions by using computational methods. This offers the possibility to generate postures and motions that are unique for the present design conditions. IMMA was originally developed for simulating manual assembly work, whereas the work presented here is a step towards utilizing the IMMA tool for occupant packaging and related tasks. The objective is a tool for virtual verification of driver-vehicle interaction that supports and automates the simulation work to a high degree. The prediction functionality in IMMA is based on the use of optimization algorithms where one important component is the consideration of comfort level. This paper reports results from an basic investigation of driving postures and available comfort models suitable in a driving context, and shows initial results of seated posture and motion prediction functionality in the IMMA tool.

  • 79.
    Bergman, Christian
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ruiz Castro, Pamela
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, Lars
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Industrial Development, Scania CV, Sweden.
    Implementation of Suitable Comfort Model for Posture and Motion Prediction in DHM Supported Vehicle Design2015Inngår i: Proceedings of the 6th International Conference on Applied Human Factors and Ergonomics (AHFE 2015), AHFE , 2015Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Driver-vehicle interaction analyses are done to ensure a successful vehicle design from an ergonomics perspective. Digital Human Modelling (DHM) tools are often used to support such verifications, particularly at early stages of the product development process. When verifying that a vehicle design accommodates the diversity of users and tasks, a DHM tool needs to be able to represent postures and motions that are likely under certain conditions. This functionality is essential so that the tool user will obtain objective and repeatable simulation results. The DHM tool IMMA (Intelligently Moving Manikins) predicts postures and motions by using computational methods. This offers the possibility to generate postures and motions that are unique for the present design conditions. IMMA was originally developed for simulating manual assembly work, whereas the work presented here is a step towards utilizing the IMMA tool for occupant packaging and related tasks. The objective is a tool for virtual verification of driver-vehicle interaction that supports and automates the simulation work to a high degree. The prediction functionality in IMMA is based on the use of optimization algorithms where one important component is the consideration of comfort level. This paper reports results from an basic investigation of driving postures and available comfort models suitable in a driving context, and shows initial results of seated posture and motion prediction functionality in the IMMA tool.

  • 80.
    Bernedixen, Jacob
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Automated Bottleneck Analysis of Production Systems: Increasing the applicability of simulation-based multi-objective optimization for bottleneck analysis within industry2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Manufacturing companies constantly need to explore new management strategies and new methods to increase the efficiency of their production systems and retain their competitiveness. It is of paramount importance to develop new bottleneck analysis methods that can identify the factors that impede the overall performance of their productionsystems so that the optimal improvement actions can be performed. Many of the bottleneck-related research methods developed in the last two decades are aimed mainly at detecting bottlenecks. Due to their sole reliance on historical data and lackof any predictive capability, they are less useful for evaluating the effect of bottleneck improvements.

    There is an urgent need for an efficient and accurate method of pinpointing bottlenecks, identifying the correct improvement actions and the order in which these should be carried out, and evaluating their effects on the overall system performance. SCORE (simulation-based constraint removal) is a novel method that uses simulation based multi-objective optimization to analyze bottlenecks. By innovatively formulating bottleneck analysis as a multi-objective optimization problem and using simulation to evaluate the effects of various combinations of improvements, all attainable, maximum throughput levels of the production system can be sought through a single optimization run. Additionally, post-optimality frequency analysis of the Pareto-optimal solutions can generate a rank order of the attributes of the resources required to achieve the target throughput levels. However, in its original compilation, SCORE has a very high computational cost, especially when the simulation model is complex with a large number of decision variables. Some tedious manual setup of the simulation based optimization is also needed, which restricts its applicability within industry, despite its huge potential. Furthermore, the accuracy of SCORE in terms of convergence in optimization theory and correctness of identifying the optimal improvement actions has not been evaluated scientifically.

    Building on previous SCORE research, the aim of this work is to develop an effective method of automated, accurate bottleneck identification and improvement analysis that can be applied in industry.

    The contributions of this thesis work include:

    (1) implementation of a versatile representation in terms of multiple-choice set variables and a corresponding constraint repair strategy into evolutionary multi-objective optimization algorithms;

    (2) introduction of a novel technique that combines variable screening enabled initializationof population and variable-wise genetic operators to support a more efficient search process;

    (3) development of an automated setup for SCORE to avoid the tedious manual creation of optimization variables and objectives;

    (4) the use of ranking distance metrics to quantify and visualize the convergence and accuracy of the bottleneck ranking generated by SCORE.

    All these contributions have been demonstrated and evaluated through extensive experiments on scalable benchmark simulation models as well as several large-scale simulation models for real-world improvement projects in the automotive industry.

    The promising results have proved that, when augmented with the techniques proposed in this thesis, the SCORE method can offer real benefits to manufacturing companies by optimizing their production systems.

  • 81.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Multiple Choice Sets and Manhattan Distance Based Equality Constraint Handling for Production Systems OptimizationInngår i: Computers & Operations Research, ISSN 0305-0548, E-ISSN 1873-765XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many simulation-based optimization packages provide powerful algorithms to solve industrialproblems. But most of them fail to oer their users the techniques they needto eectively handle multiple-choice problems involving a large set of decision variableswith mixed types (continuous, discrete and combinatorial) and problems that are highlyconstrained (e.g., with many equality constraints). Yet such issues are found in manyreal-world production system design and improvement problems. Thus, this paper introducesa method to eectively embed multiple choice sets and Manhattan-distancebasedconstraint handling into multi-objective optimization algorithms like NSGA-II andNSGA-III. This paper illustrates and evaluates how these two techniques have been appliedtogether to solve optimal workload, buer and workforce allocation problems. Anexample follows, showing their application to a complex production system improvementproblem at an automotive manufacturer.

  • 82.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Practical Production Systems Optimization Using Multiple-Choice Sets and Manhattan Distance based Constraints Handling2014Inngår i: Industrial Simulation Conference, Skövde, June 11-13, 2014, 2014, s. 97-103Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Many simulation-based optimization packages provide powerful algorithms to solve large-scale system problems. But most of them fall short to offer their users the techniques to effectively handle decision variables that are of multiple-choice type, as well as equality constraints, which can be found in many real-world industrial system design and improvement problems. Hence, this paper introduces how multiple choice sets and Manhattan-distance-based constraint handling can be effectively embedded into a meta-heuristic algorithm for simulation-based optimization. How these two techniques have been applied together to make the improvement of a complex production system, provided by an automotive manufacturer, possible will also be presented.

  • 83.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    On the convergence of stochastic simulation-based multi-objective optimization for bottleneck identificationInngår i: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588XArtikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    By innovatively formulating a bottleneck identication problem into a bi-objective optimization,simulation-based multi-objective optimization (SMO) can be eectively used as a new method for gen-eral production systems improvement. In a single optimization run, all attainable, maximum throughputlevels of the system can be sought through various optimal combinations of improvement changes ofthe resources. Additionally, the post-optimality frequency analysis on the Pareto-optimal solutions cangenerate a rank order of the attributes of the resources required to achieve the target throughput levels.Observing that existing research mainly put emphasis on measuring the convergence of the optimizationin the objective space, leaving no information on when the solutions in the decision space have convergedand stabilized, this paper represents the rst eort in increasing the knowledge about the convergence ofSMO for the rank ordering in the context of bottleneck analysis. By customizing the Spearman's footruledistance and Kendall's tau, this paper presents how these metrics can be used eectively to provide thedesired visual aid in determining the convergence of bottleneck ranking, hence can assist the user todetermine correctly the terminating condition of the optimization process. It illustrates and evaluatesthe convergence of the SMO for bottleneck analysis on a set of scalable benchmark models as well as twoindustrial simulation models. The results have shed promising direction of applying these new metrics tocomplex, real-world applications.

  • 84.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Bandaru, Sunith
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Variables Screening Enabled Multi-Objective Optimization for Bottleneck Analysis of Production SystemsManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Bottleneck analysis can be defined as the process that includes both bottleneck identification and improvement. In the literature most of the proposed bottleneck-related methods address mainly bottleneck detection. By innovatively formulating a bottleneck analysis into a bi-objective optimization method, recent research has shown that all attainable, maximized TH of a production system, through various combinations of improvement changes of the resources, can be sought in a single optimization run. Nevertheless, when applied to simulation-based evaluation, such a bi-objective optimization is computationally expensive especially when the simulation model is complex and/or with a large amount of decision variables representing the improvement actions. The aim of this paper is therefore to introduce a novel variables screening enabled bi-objective optimization that is customized for bottleneck analysis of production systems. By using the Sequential Bifurcation screening technique which is particularly suitable for large-scale simulation models, fewer simulation runs are required to find the most influenacing factors in a simulation model. With the knowledge of these input variables, the bi-objective optimization used in the bottleneck analysis can customize the genetic operators on these variables individually according to their rank of main effects with the target to speed up the entire optimization process. The screening-enabled algorithm is then applied to a set of experiments designed to evaluate how well it performs when the number of variables increases is a scalable, benchmark model, as well as two real-world industrial-scale simulation models found in the automotive industry. The results have illustrated the promising direction of incorporating the knowledge of influencing variables and variable-wise genetic operators into a multi-objective optimization algorithm for bottleneck analysis.

  • 85.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H. C.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för ingenjörsvetenskap.
    Pehrsson, Leif
    Högskolan i Skövde, Institutionen för ingenjörsvetenskap. Högskolan i Skövde, Forskningscentrum för Virtuella system. Volvo Car Corporation, Gothenburg, Sweden.
    Antonsson, Tobias
    Volvo Car Corporation, Gothenburg, Sweden.
    Simulation-based multi-objective bottleneck improvement: Towards an automated toolset for industry2015Inngår i: 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, Press Piscataway, NJ: IEEE Press, 2015, s. 2183-2194Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Manufacturing companies of today are under pressure to run their production most efficiently in order to sustain their competitiveness. Manufacturing systems usually have bottlenecks that impede their performance, and finding the causes of these constraints, or even identifying their locations, is not a straightforward task. SCORE (Simulation-based COnstraint REmoval) is a promising method for detecting and ranking bottlenecks of production systems, that utilizes simulation-based multi-objective optimization (SMO). However, formulating a real-world, large-scale industrial bottleneck analysis problem into a SMO problem using the SCORE-method manually include tedious and error-prone tasks that may prohibit manufacturing companies to benefit from it. This paper presents how the greater part of the manual tasks can be automated by introducing a new, generic way of defining improvements of production systems and illustrates how the simplified application of SCORE can assist manufacturing companies in identifying their production constraints.

  • 86.
    Bernedixen, Jacob
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Ng, Amos H.C.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Optimal Buffer Allocation for Semi-synchronized Automotive Assembly Lines using Simulation-based Multi-objective Optimization2011Inngår i: Proceedings of the 9th Industrial Simulation Conference, Eurosis , 2011, s. 129-135Konferansepaper (Fagfellevurdert)
    Abstract [en]

    A practical question in industry in designing or re-designing a production system is: how small can intermediated buffers be to ensure the desired production rate? This topic is usually called optimal buffer allocation as the goal is to allocate the minimum buffer capacities to optimize the performance of the line. This paper presents a case study of using simulation-based evolutionary multi-objective optimization to determine the optimal buffer capacities and positions in the reconfiguration of a real-world truck axle assembly line in an automobile manufacturer. The case study has not only revealed the applicability of the methodology in seeking optimal configurations in a truly multi-objective context, it also illustrates how additional important knowledge was gained by analyzing the optimization results in the objective space.

  • 87.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Gustafsson, E.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, L.
    Chalmers University of Technology.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Swedish engineering anthropometric web resource2011Inngår i: Proceedings of the 43rd Annual Nordic Ergonomics Society Conference / [ed] Juha Lindfors Merja Savolainen, Seppo Väyrynen, University of Oulu , 2011, s. 442-446Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Anthropometry, the study of human measurements, is central in the design of products and workplaces. This paper describes how Swedish anthropometric data is made available through a web page (www.antropometri.se) intended to be used by designers and engineers when developing new products and workplaces. With the anthropometric web resource it is possible to get mean and standard deviation values, and to calculate percentile values, for a number of anthropometric measurements. Further functionality on the web page enables simultaneous consideration of several anthropometric measurements. The web page also contains guidelines for how to use anthropometric data depending on the design task at hand.

  • 88.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, L.
    Chalmers University of Technology.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Rhén, Ida-Märta
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Creation of the IMMA manikin with consideration of anthropometric diversity2011Inngår i: Proceedings of the 21st International Conference on Production Research (ICPR), Fraunhofer Verlag , 2011Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Digital human modelling (DHM) systems are used to simulate production processes and analyse the human-machine interaction, particularly at early development stages. Consideration of anthropometric variation is central in DHM simulations due to the necessity of ensuring intended accommodation levels. This paper describes the process of how digital human models are created and defined within the IMMA software. The process begins with the definition of a number of key measurements, which acts as the basis for the definition of several boundary manikins using a confidence ellipsoid methodology. These manikins represents the appropriate confidence region and hence the anthropometric diversity. Key measurements are then entered into regression equations to define the complete set of measurements for each manikin. These measurements are based on the appropriate ISO-standard. Finally, measurements are used to define the size and alignment of each segment in the biomechanical model of the manikin. The manikins are then used to automatically simulate and analyse human-machine interaction.

  • 89.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Göteborg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Digital Human Model Module and Work Process for Considering Anthropometric Diversity2010Inngår i: Proceedings of the 3rd Applied Human Factors and Ergonomics (AHFE) International Conference / [ed] Gavriel Salvendy, Waldemar Karwowski, Louisville: AHFE International , 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In digital human modelling (DHM), ergonomics evaluations are typically done with few human models. However, humans vary a lot in sizes and shapes. Therefore, few manikins can rarely ensure accommodation of an entire target population. Different approaches exist on how to consider anthropometric diversity. This paper reviews current  DHM  tools  and  clarify  problems  and  opportunities  when  working  with anthropometric diversity. The aim is to suggest  functionality  for a state of the art DHM  module  and  work  process  for  considering  anthropometric  diversity.  The study is done by an analysis of some of the current DHM systems and by interviews of  personnel  at  car  companies  about  their  way  of  working  with  anthropometric diversity. The study confirmed that critical production simulations are often done in early development stages with only one or a few human models. The reason for this is claimed to be time consuming processes, both at the creation of the human model but  mainly  when  correctly  positioning  the  model  in  the  CAD  environment.  The development  of  a  new  method  and  work  process  for  considering  anthropometric diversity is suggested. Necessary features for such a module are that it shall be easy to use and not require expert knowledge about the consideration of anthropometric diversity. It shall also be configurable and transparent, in a sense that it should be possible  to  work  with  own  anthropometric  data  and  ergonomics  evaluation standards. The module has to be flexible and have different entrances depending on the type of anthropometric problem being analyzed. An improved work method is expected to lead to faster and more correct analyses.

  • 90.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, Lars
    Chalmers University of Technology.
    Using experimental design to define boundary manikins2012Inngår i: Work: A Journal of Prevention, Assessment and Rehabilitation, ISSN 1051-9815, Vol. 41, s. 4598-4605Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    When evaluating human-machine interaction it is central to consider anthropometric diversity to ensure intended accommodation levels. A well-known method is the use of boundary cases where manikins with extreme but likely measurement combinations are derived by mathematical treatment of anthropometric data. The supposition by that method is that the use of these manikins will facilitate accommodation of the expected part of the total, less extreme, population. In literature sources there are differences in how many and in what way these manikins should be defined. A similar field to the boundary case method is the use of experimental design in where relationships between affecting factors of a process is studied by a systematic approach. This paper examines the possibilities to adopt methodology used in experimental design to define a group of manikins. Different experimental designs were adopted to be used together with a confidence region and its axes. The result from the study shows that it is possible to adapt the methodology of experimental design when creating groups of manikins. The size of these groups of manikins depends heavily on the number of key measurements but also on the type of chosen experimental design.

  • 91.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Högberg, Dan
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Hanson, Lars
    Chalmers University of Technology.
    Wondmagegne, Yosief
    Högskolan i Skövde.
    Multidimensional consideration of anthropometric diversity2011Inngår i: Proceedings of DHM, First International Symposium on Digital Human Modeling, Université Claude Bernard Lyon , 2011, s. 1-6Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Boundary manikins, the concept of creating statistically extreme cases to accommodate a big part of the less extreme population has been known for decades. Despite this, many ergonomics simulations are done with few human models. This fact can be explained by the time consuming processes when working with many manikins in current digital human modelling (DHM) tools, but may also be a result of difficulty to understand how these manikins are calculated and defined. This paper focuses on the method of defining boundary manikins and how that functionality can be integrated into a DHM tool. Examples of boundary case methods in the literature often use Principal Component Analysis (PCA) which makes it possible to reduce the dimensions of the problem without much loss of the variance of the analysed data. Using PCA often demands some extent of manual analysis at the critical stage of reducing dimensions. This paper will explain a similar methodology for ceating boundary manikins from any number of variables, i.e. anthropometric variables chosen as key measurements. This method of creating a group of manikins is intended to be used in an automatic simulation feature in the IMMA software being developed in the associated research project. By using the method, a confidence region in the standardized space is created from eigenvectors and scaled eigenvalues of a correlation matrix. Boundary manikins are chosen at the ends of the axes of the enclosing confidence region, and one manikin of mean values is also added to the group of manikins. In the method presented here, the number of manikins created depends directly on the number of variables, which lead to the fact that the decision making of which key measurements to consider has to be done carefully to not create an overwhelming number of manikins. In comparison with one method using PCA, the method presented in this paper creates more manikins with a bigger difference in the max and min values of the chosen key measurements. If a limited number of cases are of crucial interest, then using PCA to reduce the dimensions of the problem is a good method to use. But if it is possible to create automated simulations the limitation of the number of manikins might not be so important. This will, though, depend heavily on the speed of the automated simulations.

  • 92.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle. Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden.
    Keyvani, Ali
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Innovatum AB, Trollhättan, Sweden.
    Högberg, Dan
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Gothenburg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Assessment of manikin motions in IMMA2012Inngår i: Advances in Applied Human Modeling and Simulation / [ed] Vincent G. Duffy, Boca Raton: CRC Press, 2012, s. 235-244Kapittel i bok, del av antologi (Fagfellevurdert)
    Abstract [en]

    When evaluating human-machine interaction in a virtual environment using Digital human modelling (DHM) it is important to ensure that the predicted motions lie within the range of behavioural diversity for different people within a population. This paper presents a study in which a comparison is made between motions predicted by the DHM tool IMMA (Intelligently Moving Manikin) and motions from real humans stored in a motion database. Results show similar motions but the predicted motions were in total statistically significantly different compared to the motions performed by real persons. The differences are most likely due to the balance function and joint constraints that the IMMA tool uses for predicting motions. Differences can also be due to other factors, aside of body size, such as age, gender or strength that affects the movement behaviour.

  • 93.
    Bertilsson, Erik
    et al.
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Svensson, Erik
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Högberg, Dan
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Hanson, Lars
    Department of Product and Production Development, Chalmers University of Technology, Göteborg, Sweden / Industrial Development, Scania CV, Södertälje, Sweden.
    Use of digital human modelling and consideration of anthropometric diversity in Swedish industry2010Inngår i: Proceedings of the 42nd annual Nordic Ergonomic Society Conference, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This  paper  study  and  clarify  problems,  needs  and  opportunities  when  working  with anthropometric  diversity  in  digital  human  modelling  (DHM)  systems.  A  comparison between  product  development  and  production  development  in  Swedish  automotive industry is made. Interviews with DHM users and ergonomics specialists about their way of working with anthropometric diversity confirmed that simulations are often done with only one or  a  few  human models.  The reason for  this  is  claimed  to  be  time  consuming processes, both at the creation of the human model but mainly when correctly positioning the model in the CAD environment.

  • 94.
    Bi, Z. M.
    et al.
    Department of Engineering, Indiana University Purdue University Fort Wayne, Fort Wayne, IN, United States.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    A Study on Optimal Machine Setups Using an Energy Modeling Approach2012Inngår i: Proceedings of NAMRI/SME, Society of Manufacturing Engineers, North American Manufacturing Research Institution of SME , 2012, s. 571-579Konferansepaper (Fagfellevurdert)
    Abstract [en]

    In this paper, energy models are developed based on the kinematic and dynamic behaviors of chosen machine tools. One significant benefit of the developed energy models is their inherited relationship to the design variables involved in the manufacturing processes. Therefore, they can be readily applied to optimize process parameters to reduce energy consumption. A new parallel kinematic machine Exechon is used as a case study to demonstrate the procedures of energy model development with direct relation to appropriate process parameters. The derived energy model is then used for simulation of drilling operations on aircraft components to demonstrate its feasibility. Simulation results indicate that the developed energy model has led to an optimized machine setup which only consumes less than one-third of the energy of an average machine setup over the workspace. This approach can be extended and applied to other machines to establish their energy models for green manufacturing.

  • 95.
    Bi, Z. M.
    et al.
    Department of Engineering, Indiana University Purdue University Fort Wayne, 2101 E. Coliseum Blvd., Fort Wayne, IN 46805, United States.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Advances in 3D data acquisition and processing for industrial applications2010Inngår i: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 26, nr 5, s. 403-413Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    A critical task of vision-based manufacturing applications is to generate a virtual representation of a physical object from a dataset of point clouds. Its success relies on reliable algorithms and tools. Many effective technologies have been developed to solve various problems involved in data acquisition and processing. Some articles are available on evaluating and reviewing these technologies and underlying methodologies. However, for most practitioners who lack a strong background on mathematics and computer science, it is hard to understand theoretical fundamentals of the methodologies. In this paper, we intend to survey and evaluate recent advances in data acquisition and progressing,and provide an overview from a manufacturing perspective. Some potential manufacturing applications have been introduced, the technical gaps between the practical requirements and existing technologies discussed, and research opportunities identified.

  • 96.
    Bi, Z. M.
    et al.
    Indiana University Purdue University Fort Wayne.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Energy Modeling of Machine Tools for Optimization of Machine Setups2012Inngår i: IEEE Transactions on Automation Science and Engineering, ISSN 1545-5955, E-ISSN 1558-3783, Vol. 9, nr 3, s. 607-613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this paper, a new energy model is developed based on the kinematic and dynamic behaviors of a chosen machine tool. One significant benefit of the developed energy model is their inherited relationship to the design variables involved in the manufacturing processes. Without radical changes of the machine tool’s structure, the proposed model can be readily applied to optimize process parameters to reduce energy consumption. A new parallel kinematic machine Exechon is used as a case study to demonstrate the modeling procedure. The derived energy model is then used for simulation of drilling operations on aircraft components to verify its feasibility. Simulation results indicate that the developed energy model has led to an optimized machine setup which only consumes less than one-third of the energy of an average machine setup over the workspace. This approach can be extended and applied to other machines to establish their energy models for green and sustainable manufacturing.

  • 97.
    Bi, Z. M.
    et al.
    Indiana University Purdue University Fort Wayne.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Feasibility Study on a Collaborative Robot with Omni-wheels2010Inngår i: Proceedings of the 12th Mechatronics Forum Biennial International Conference / [ed] Thomas Kennel, Zürich: IWF Institute of Machine Tools and Manufacturing , 2010, s. 114-120Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Robotics has brought radical changes to maximise the productivity of modern manufacturing. However, a full  automation  is  not  always  advantageous;  sometimes  robots  and  human  being  must  work  together  in  a shared  environment  to  meet  specific  requirements.  A  robot  used  in  a  collaborative  environment  is  a collaborative robot. In this paper, a collaborative robot to assist human being’s locomotion is considered: omni-wheels  are  used  to  increase  the  flexibility  and  mobility  of  the  robot  and  they  are  controlled dynamically  to  confine  the  robot  in  a  prescribed  trajectory.  The  new  control  algorithms  are  developed  to meet the following challenges (a) unpredictable driving force from a human operator; (b) the rotation of an omni-wheel along two axes but with one independent motion; and (c) the strongly-coupled kinematics and dynamics of the mobile robot.

  • 98.
    Bi, Z. M.
    et al.
    Indiana University-Purdue University Fort Wayne, USA.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Optimal design of reconfigurable parallel machining systems2009Inngår i: Robotics and Computer-Integrated Manufacturing, ISSN 0736-5845, E-ISSN 1879-2537, Vol. 25, nr 6, s. 951-961Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A reconfigurable machining system is usually a modularized system, and its configuration design concerns the selections of modules and the determination of geometric dimensions in some specific modules. All of its design perspectives from kinematics, dynamics, and control have to be taken into considerations simultaneously, and a multidisciplinary design optimization (MDO) tool is required to support the configuration design process. This paper presents a new MDO tool for reconfigurable machining systems, and it includes the following works: (i) the literatures on the computer-aided design of reconfigurable parallel machining systems have been reviewed with a conclusion that the multidisciplinary design optimization is essential, but no comprehensive design tool is available to reconfigurable parallel machining systems; (ii) a class of reconfigurable systems called reconfigurable tripod-based machining system has been introduced, its reconfiguration problem is identified, and the corresponding design criteria have been discussed; (iii) design analysis in all of the disciplines including kinematics, dynamics, and control have been taken into considerations, and design models have been developed to evaluate various design candidates; in particular, the innovative solutions to direct kinematics, stiffness analysis for the design configurations of tripod-based machines with a passive leg, and concise dynamic modelling have been provided; and (iv) A design optimization approach is proposed to determine the best solution from all possible configurations. Based on the works presented in this paper, a computer-aided design and control tool have been implemented to support the system reconfiguration design and control processes. Some issues relevant to the practical implementation have also been discussed.

  • 99.
    Bi, Z. M.
    et al.
    Department of Engineering, Indiana University Purdue University Fort Wayne, Fort Wayne, IN, USA.
    Wang, Lihui
    Högskolan i Skövde, Institutionen för teknik och samhälle. Högskolan i Skövde, Forskningscentrum för Virtuella system.
    Optimization of machining processes from the perspective of energy consumption: A case study2012Inngår i: Journal of manufacturing systems, ISSN 0278-6125, E-ISSN 1878-6642, Vol. 31, nr 4, s. 420-428Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    One of the primary objectives of sustainable manufacturing is to minimize energy consumption in its manufacturing processes. A strategy of energy saving is to adapt new materials or new processes; but its implementation requires radical changes of the manufacturing system and usually a heavy initial investment. The other strategy is to optimize existing manufacturing processes from the perspective of energy saving. However, an explicit relational model between machining parameters and energy cost is required; while most of the works in this field treat the manufacturing processes as black or gray boxes. In this paper, analytical energy modeling for the explicit relations of machining parameters and energy consumption is investigated, and the modeling method is based on the kinematic and dynamic behaviors of chosen machine tools. The developed model is applied to optimize the  machine setup for energy saving. A new parallel kinematic machine Exechon is used to demonstrate the procedure of energy modeling. The simulation results indicate that the optimization can result in 67% energy saving for the specific drilling operation of the given machine tool. This approach can be extended and applied to other machines to establish their energy models for sustainable manufacturing.

  • 100.
    Bi, Z.M.
    et al.
    Queen's University Belfast.
    Wang, Lihui
    Högskolan i Skövde, Forskningscentrum för Virtuella system. Högskolan i Skövde, Institutionen för teknik och samhälle.
    Design of a Cobot with Three Omni-Wheels2009Inngår i: Proceedings of the 19th International Conference on Flexible Automation and Intelligent Manufacturing, FAIM 2009 , 2009, s. 186-193Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Collaborative robots (Cobots) have been proposed to guide and assist human operators to move heavy objects in a given trajectory. Most of the existing cobots us steering wheels; typical drawbacks of using steering wheels include (i) the difficulty to follow a trajectory with a curvature larger than that of the base platform, (ii) the difficulty to mount encoders on steering wheels due to self-spinning of the wheels, and (iii) the difficulty to quarantine dynamic control performance since it is purely kinematic control. In this paper, a new cobot with the omni-wheels has been proposed, and its design model has been developed, and a simulation has been conducted to validate this control performance.

1234567 51 - 100 of 657
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf