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Ng, A. H. C., Bernedixen, J., Andersson, M., Bandaru, S. & Lezama, T. (2020). Aircraft Assembly Ramp-Up Planning Using a Hybrid Simulation-Optimization Approach. In: K.-H. Bae; B. Feng; S. Kim; S. Lazarova-Molnar; Z. Zheng; T. Roeder; R. Thiesing (Ed.), Proceedings - Winter Simulation Conference: . Paper presented at 2020 Winter Simulation Conference, WSC 2020, Orlando, United States, 14 December 2020 through 18 December 2020; Category number CFP20WSC-ART; Code 168205 (pp. 3045-3056). IEEE
Open this publication in new window or tab >>Aircraft Assembly Ramp-Up Planning Using a Hybrid Simulation-Optimization Approach
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2020 (English)In: Proceedings - Winter Simulation Conference / [ed] K.-H. Bae; B. Feng; S. Kim; S. Lazarova-Molnar; Z. Zheng; T. Roeder; R. Thiesing, IEEE, 2020, p. 3045-3056Conference paper, Published paper (Refereed)
Abstract [en]

Assembly processes have the most influencing and long-term impact on the production volume and cost in the aerospace industry. One of the most crucial factors in aircraft assembly lines design during the conceptual design phase is ramp-up planning that synchronizes the production rates at the globally dispersed facilities. Inspired by a pilot study performed with an aerospace company, this paper introduces a hybrid simulation-optimization approach for addressing an assembly production chain ramp-up problem that takes into account: (1) the interdependencies of the ramp-up profiles between final assembly lines and its upstream lines; (2) workforce planning with various learning curves; (3) inter-plant buffer and lead-time optimization, in the problem formulation. The approach supports the optimization of the ramp-up profile that minimizes the times the aircraft assemblies stay in the buffers and simultaneously attains zero backlog. It also generates the required simulation-optimization data for supporting the decision-making activities in the industrialization projects. 

Place, publisher, year, edition, pages
IEEE, 2020
Series
Proceedings - Winter Simulation Conference, ISSN 1558-4305, E-ISSN 0891-7736
Keywords
Aerospace industry, Aircraft, Assembly machines, Conceptual design, Curve fitting, Decision making, Aerospace company, Aircraft assemblies, Conceptual design phase, Hybrid simulation optimizations, Problem formulation, Production volumes, Simulation optimization, Workforce planning, Assembly
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
VF-KDO; Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-19651 (URN)10.1109/WSC48552.2020.9383887 (DOI)000679196303007 ()2-s2.0-85103898531 (Scopus ID)978-1-7281-9499-8 (ISBN)978-1-7281-9500-1 (ISBN)
Conference
2020 Winter Simulation Conference, WSC 2020, Orlando, United States, 14 December 2020 through 18 December 2020; Category number CFP20WSC-ART; Code 168205
Note

© 2020 IEEE

Available from: 2021-04-22 Created: 2021-04-22 Last updated: 2023-08-17Bibliographically approved
Bernedixen, J. (2018). Automated Bottleneck Analysis of Production Systems: Increasing the applicability of simulation-based multi-objective optimization for bottleneck analysis within industry. (Doctoral dissertation). Skövde: University of Skövde
Open this publication in new window or tab >>Automated Bottleneck Analysis of Production Systems: Increasing the applicability of simulation-based multi-objective optimization for bottleneck analysis within industry
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
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.

Abstract [sv]

Tillverkningsföretag behöver ständigt utforska nya ledningsstrategier och nya metoder för att påskynda effektiviteten i sina produktionssystem och behålla sin konkurrenskraft. Av yttersta vikt är att utveckla nya flaskhalsanalysmetoder som kan identifierade faktorer som hindrar produktiviteten i produktionssystemen så att optimala förbättringsåtgärderna kan utföras. Många av de flaskhalsrelaterade forskningsmetoder som utvecklats under de senaste två decennierna syftar främst till att upptäcka flaskhalsen. På grund av avsaknaden av förebyggande förmåga är de mindre användbara för att utvärdera effekten av flaskhalsförbättringar.

En effektiv och korrekt metod för identifiering av korrekta förbättringsåtgärder, ordningen de ska utföras i samt dess effekt på produktionssystemets produktivitet är nödvändig. SCORE (simulation-based constraint removal) är en ny metod som möjliggör flaskhalsanalys genom användning av simuleringsbaserad flermålsoptimering. Genom att innovativt formulera flaskhalsanalys till ett flermålsoptimeringsproblem ochanvända simulering för att utvärdera effekterna av olika kombinationer av förbättringar, kan alla uppnåeliga maximala produktivitetsnivåer av produktionssystemet sökas i en enda optimering. Dessutom kan en frekvensanalys på Pareto-optimala lösningar från en sådan optimering generera en rangordning av de systemparameterar som behöver förbättras för att uppnå den önskade produktivitetsnivån. Dessa fördelar med SCORE kan dock endast uppnås med en mycket hög beräkningskostnad, speciellt när simuleringsmodellen är komplex och/eller består av ett stort antal beslutsvariabler. Dessutom innebär formuleringen av det simuleringsbaserade flermålsoptimeringsproblemet mycket manuellt och felbenäget arbete som kan begränsa användbarheten inom industrin, detta trots den enorma potential som metoden erbjuder. Dessutom har noggrannheten i SCORE, när det gäller konvergens i optimeringsteori och korrekthet att identifiera optimala förbättringsåtgärder, inte utvärderats vetenskapligt.

Syftet med denna avhandling är därför att med avstamp i tidigare forskning kring SCORE utveckla en effektiv, automatiserad och korrekt metod för flaskhalsidentifiering och förbättringsanalys som kan tillämpas inom industrin.

Bidrag från detta avhandlingsarbete inkluderar:

(1) implementering av en mångsidig optimeringsvariabel (multiple-choice set variabel) och därtill en reparationsstrategi i evolutionära flermålsoptimeringsalgoritmer(EA);

(2) introducera en ny teknik som baserat på information från en sekventiell screening initialiserar första populationen i en EA samt möjliggör skapandet av variabelvisa genetiska operatorer, båda med syftet att stödja en effektivare sökprocess;

(3) en automatiserad formulering av flermålsoptimeringsproblemet i SCORE för att bespara användarna den stora mängd manuellt och felbenäget arbete med optimeringsvariabler och mål som krävs;

(4) presentera hur upprepad användning av rankningsavstånd (mätetal som visar hur lika/olika två rankningar är varandra) kan användas för att kvantifiera och visualisera konvergens och korrekthet av flaskhalsrankningen genererad av SCORE.

Alla dessa bidrag har demonstrerats och utvärderats genom omfattande experiment på skalbara, benchmark-simuleringsmodeller samt på flera stora simuleringsmodeller som använts i förbättringsprojekt inom fordonsindustrin.

De framgångsrika resultaten har visat att förbättringarna av SCORE-metoden presenterade i detta arbete gör det möjligt för tillverkningsföretag att förvärva verkliga fördelar genom att optimera sina produktionssystem optimalt.

Place, publisher, year, edition, pages
Skövde: University of Skövde, 2018. p. 218
Series
Dissertation Series ; 23 (2018)
Keywords
bottleneck analysis, bottleneck identification, bottleneck improvement, multi-objective optimization, simulation
National Category
Production Engineering, Human Work Science and Ergonomics Information Systems
Research subject
Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-15214 (URN)978-91-984187-6-7 (ISBN)
Public defence
2018-06-08, Portalen, Insikten, Skövde, 13:15 (English)
Opponent
Supervisors
Funder
Knowledge Foundation
Available from: 2018-06-04 Created: 2018-05-31 Last updated: 2019-07-03Bibliographically approved
Karlsson, I., Bernedixen, J., Ng, A. H. C. & Pehrsson, L. (2017). Combining augmented reality and simulation-based optimization for decision support in manufacturing. In: W. K. V. Chan, A. D’Ambrogio, G. Zacharewicz, N. Mustafee, G. Wainer, E. Page (Ed.), Proceedings of the 2017 Winter Simulation Conference: . Paper presented at 2017 Winter Simulation Conference, WSC 2017, Las Vegas, USA, 3-6 December 2017 (pp. 3988-3999). Institute of Electrical and Electronics Engineers (IEEE)
Open this publication in new window or tab >>Combining augmented reality and simulation-based optimization for decision support in manufacturing
2017 (English)In: Proceedings of the 2017 Winter Simulation Conference / [ed] W. K. V. Chan, A. D’Ambrogio, G. Zacharewicz, N. Mustafee, G. Wainer, E. Page, Institute of Electrical and Electronics Engineers (IEEE), 2017, p. 3988-3999Conference paper, Published paper (Refereed)
Abstract [en]

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

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2017
Series
Winter Simulation Conference. Proceedings, ISSN 0891-7736, E-ISSN 1558-4305
Keywords
Artificial intelligence, Augmented reality, Automobile drivers, Decision support systems, Hardware, Optimization, Bottleneck detection, Decision supports, Manufacturing IS, Manufacturing organizations, MicroSoft, Simulation model, Simulation-based optimizations, Quality control
National Category
Computer Sciences Computer Systems Production Engineering, Human Work Science and Ergonomics
Research subject
Production and Automation Engineering; INF201 Virtual Production Development
Identifiers
urn:nbn:se:his:diva-15109 (URN)10.1109/WSC.2017.8248108 (DOI)000427768604018 ()2-s2.0-85044511682 (Scopus ID)978-1-5386-3428-8 (ISBN)978-1-5386-3429-5 (ISBN)978-1-5386-3430-1 (ISBN)
Conference
2017 Winter Simulation Conference, WSC 2017, Las Vegas, USA, 3-6 December 2017
Available from: 2018-04-30 Created: 2018-04-30 Last updated: 2020-09-23Bibliographically approved
Ng, A. H. C., Shaaban, S. & Bernedixen, J. (2017). Studying unbalanced workload and buffer allocation of production systems using multi-objective optimisation. International Journal of Production Research, 55(24), 7435-7451
Open this publication in new window or tab >>Studying unbalanced workload and buffer allocation of production systems using multi-objective optimisation
2017 (English)In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 55, no 24, p. 7435-7451Article in journal (Refereed) Published
Abstract [en]

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

Place, publisher, year, edition, pages
Taylor & Francis, 2017
National Category
Computer Sciences Computer Systems Production Engineering, Human Work Science and Ergonomics Other Mechanical Engineering
Research subject
Production and Automation Engineering; INF201 Virtual Production Development; VF-KDO
Identifiers
urn:nbn:se:his:diva-14730 (URN)10.1080/00207543.2017.1362121 (DOI)000423135100011 ()2-s2.0-85027107431 (Scopus ID)
Note

Received 22 Jun 2016, Accepted 24 Jul 2017, Published online: 09 Aug 2017

Available from: 2018-02-08 Created: 2018-02-08 Last updated: 2023-02-22Bibliographically approved
Pehrsson, L., Ng, A. H. C. & Bernedixen, J. (2016). Automatic identification of constraints and improvement actions in production systems using multi-objective optimization and post-optimality analysis. Journal of manufacturing systems, 39, 24-37
Open this publication in new window or tab >>Automatic identification of constraints and improvement actions in production systems using multi-objective optimization and post-optimality analysis
2016 (English)In: Journal of manufacturing systems, ISSN 0278-6125, E-ISSN 1878-6642, Vol. 39, p. 24-37Article in journal (Refereed) Published
Abstract [en]

Manufacturing companies are operating in a severely competitive global market, which renders an urgent need for them to explore new methods to enhance the performance of their production systems in order to retain their competitiveness. Regarding the performance of a production system, it is not sufficient simply to detect which operations to improve, but it is imperative to pinpoint the right actions in the right order to avoid sub-optimizations and wastes in time and expense. Therefore, a more accurate and efficient method for supporting system improvement decisions is greatly needed in manufacturing systems management. Based on research in combining simulation-based multi-objective optimization and post-optimality analysis methods for production systems design and analysis, a novel method for the automatic identification of bottlenecks and improvement actions, so-called Simulation-based Constraint Identification (SCI), is proposed in this paper. The essence of the SCI method is the application of simulation-based multi-objective optimization with the conflicting objectives to maximize the throughput and minimize the number of required improvement actions simultaneously. By using post-optimality analysis to process the generated optimization dataset, the exact improvement actions needed to attain a certain level of performance of the production line are automatically put into a rank order. In other words, when compared to other existing approaches in bottleneck detection, the key novelty of combining multi-objective optimization and post-optimality analysis is to make SCI capable of accurately identifying a rank order for the required levels of improvement for a large number of system parameters which impede the performance of the entire system, in a single optimization run. At the same time, since SCI is basically built a top a simulation-based optimization approach, it is capable of handling large-scale, real-world system models with complicated process characteristics. Apart from introducing such a method, this paper provides some detailed validation results from applying SCI both in hypothetical examples that can easily be replicated as well as a complex, real-world industrial improvement project. The promising results compared to other existing bottleneck detection methods have demonstrated that SCI can provide valuable higher-level information to support confident decision-making in production systems improvement.

Place, publisher, year, edition, pages
Elsevier, 2016
Keywords
Multi-objective optimization, Simulation, Production system, SCI
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Technology; Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-12020 (URN)10.1016/j.jmsy.2016.02.001 (DOI)000376694200003 ()2-s2.0-84959481904 (Scopus ID)
Available from: 2016-03-08 Created: 2016-03-08 Last updated: 2019-02-25Bibliographically approved
Bernedixen, J., Ng, A. H. C., Pehrsson, L. & Antonsson, T. (2015). Simulation-based multi-objective bottleneck improvement: Towards an automated toolset for industry. In: L. Yilmaz, W. K. V. Chan, I. Moon, T. M. K. Roeder, C. Macal, and M. D. Rossetti (Ed.), Proceedings of the 2015 Winter Simulation Conference: . Paper presented at WSC '15 Winter Simulation Conference, Huntington Beach, CA, USA — December 06 - 09, 2015 (pp. 2183-2194). Press Piscataway, NJ: IEEE Press
Open this publication in new window or tab >>Simulation-based multi-objective bottleneck improvement: Towards an automated toolset for industry
2015 (English)In: 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, p. 2183-2194Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Press Piscataway, NJ: IEEE Press, 2015
Series
Winter Simulation Conference. Proceedings, ISSN 0891-7736
Keywords
Simulation, Optimization, Manufacturing
National Category
Other Mechanical Engineering
Research subject
Technology; Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-11919 (URN)10.1109/WSC.2015.7408331 (DOI)000399133902006 ()2-s2.0-84962811728 (Scopus ID)978-1-4673-9743-8 (ISBN)
Conference
WSC '15 Winter Simulation Conference, Huntington Beach, CA, USA — December 06 - 09, 2015
Available from: 2016-02-12 Created: 2016-02-12 Last updated: 2018-05-31
Bernedixen, J. & Ng, A. H. C. (2014). Practical Production Systems Optimization Using Multiple-Choice Sets and Manhattan Distance based Constraints Handling. In: Amos Ng; Anna Syberfeldt (Ed.), 12th International Industrial Simulation Conference 2014: ISC'2014. Paper presented at ISC'2014, 12th Annual Industrial Simulation Conference, June 11-13, 2014, University of Skövde, Skövde, Sweden (pp. 97-103). Eurosis
Open this publication in new window or tab >>Practical Production Systems Optimization Using Multiple-Choice Sets and Manhattan Distance based Constraints Handling
2014 (English)In: 12th International Industrial Simulation Conference 2014: ISC'2014 / [ed] Amos Ng; Anna Syberfeldt, Eurosis , 2014, p. 97-103Conference paper, Published paper (Refereed)
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.

Place, publisher, year, edition, pages
Eurosis, 2014
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Technology; Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-9387 (URN)2-s2.0-84922203716 (Scopus ID)978-90-77381-83-0 (ISBN)
Conference
ISC'2014, 12th Annual Industrial Simulation Conference, June 11-13, 2014, University of Skövde, Skövde, Sweden
Available from: 2014-06-09 Created: 2014-06-09 Last updated: 2023-03-23Bibliographically approved
Ng, A. H. C., Bernedixen, J. & Pehrsson, L. (2014). What Does Multi-Objective Optimization Have to Do with Bottleneck Improvement of Production Systems?. In: Johan Stahre, Björn Johansson & Mats Björkman (Ed.), Proceedings of The 6th International Swedish Production Symposium 2014: . Paper presented at The 6th International Swedish Production Symposium 2014, Gothenburg, September 16 – September 18.
Open this publication in new window or tab >>What Does Multi-Objective Optimization Have to Do with Bottleneck Improvement of Production Systems?
2014 (English)In: Proceedings of The 6th International Swedish Production Symposium 2014 / [ed] Johan Stahre, Björn Johansson & Mats Björkman, 2014Conference paper, Published paper (Refereed)
Abstract [en]

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

Keywords
Bottleneck Improvement, Production System Simulation, Multi-objective Optimization, Data Mining
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Technology; Production and Automation Engineering
Identifiers
urn:nbn:se:his:diva-10359 (URN)978-91-980974-1-2 (ISBN)
Conference
The 6th International Swedish Production Symposium 2014, Gothenburg, September 16 – September 18
Funder
Knowledge Foundation
Available from: 2014-12-08 Created: 2014-12-08 Last updated: 2018-05-31Bibliographically approved
Pehrsson, L., Ng, A. H. C., Bernedixen, J. & Stockton, D. (2013). Sectioned Walking Worker Lines with Loop Balancing. In: : . Paper presented at ISC 2013, Industrial Simulation Conference, May 22-24, 2013, Ghent University, Ghent, Belgium (pp. 187-191).
Open this publication in new window or tab >>Sectioned Walking Worker Lines with Loop Balancing
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

The competition in the automotive industry moves forward and alternative production concepts emerge. Within assembly systems development the walking worker concept has been noticed as an interesting approach to level capacity to customer demand. One of the main disadvantages has been that each worker has to learn a large work content covering all stations in the line. This paper investigates an approach with a sectioned line divided into worker loops (streets) in order to overcome some of this disadvantage while maintaining the effectiveness and ability to align capacity to customer demand.

Keywords
Assembly, Optimisation, Simulation, Walking worker
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-8437 (URN)2-s2.0-84898449239 (Scopus ID)978-90-77381-76-2 (ISBN)
Conference
ISC 2013, Industrial Simulation Conference, May 22-24, 2013, Ghent University, Ghent, Belgium
Available from: 2013-08-20 Created: 2013-08-20 Last updated: 2021-08-04Bibliographically approved
Ng, A. H. C., Bernedixen, J. & Syberfeldt, A. (2012). A comparative study of production control mechanisms using simulation-based multi-objective optimisation. International Journal of Production Research, 50(2), 359-377
Open this publication in new window or tab >>A comparative study of production control mechanisms using simulation-based multi-objective optimisation
2012 (English)In: International Journal of Production Research, ISSN 0020-7543, E-ISSN 1366-588X, Vol. 50, no 2, p. 359-377Article in journal (Refereed) Published
Abstract [en]

There exist many studies conducted to compare the performance of different production control mechanisms (PCMs) in order to determine which one performs the best under different conditions. Nonetheless, most of these studies suffer from the problems that the PCMs are not compared with their optimal parameter settings in a truly multi-objective context. This paper describes how different PCMs can be compared under their optimal settings through generating the Pareto-optimal frontiers, in the form of optimal trade-off curves in the performance space, by applying evolutionary multi-objective optimisation to simulation models. This concept is illustrated with a bi-objective comparative study of the four most popular PCMs in the literature, namely Push, Kanban, CONWIP and DBR, on an unbalanced serial flow line in which both control parameters and buffer capacities are to be optimised. Additionally, it introduces the use of normalised hyper-volume as the quantitative metric and confidence-based significant dominance as the statistical analysis method to verify the differences of the PCMs in the performance space. While the results from this unbalanced flow line cannot be generalised, it indicates clearly that a PCM may be preferable in certain regions of the performance space, but not others, which supports the argument that PCM comparative studies have to be performed within a Pareto-based multi-objective context.

Place, publisher, year, edition, pages
Taylor & Francis, 2012
Keywords
production control mechanisms, stochastic simulation, multi-objective optimisation, optimal buffer allocation
National Category
Production Engineering, Human Work Science and Ergonomics Computer and Information Sciences
Research subject
Technology
Identifiers
urn:nbn:se:his:diva-6219 (URN)10.1080/00207543.2010.538741 (DOI)000303582300005 ()2-s2.0-84860008051 (Scopus ID)
Available from: 2012-08-08 Created: 2012-08-08 Last updated: 2023-07-06Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-9643-6233

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