| 52781. |
- Lämkull, Dan, 1966, et al.
(författare)
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A comparative study of digital human modelling simulation results and their outcomes in reality : A case study within manual assembly of automobiles
- 2009
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier. - 0169-8141 .- 1872-8219. ; 39:2, s. 428-441
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to examine to what extent ergonomics simulations of manual assembly tasks correctly predict the real outcomes in the plants and if recommended measures originating from ergonomics simulations are taken into consideration. 155 ergonomics simulation cases were used in the study and all cases were performed by nine simulation engineers at Volvo Car Corporation in Gothenburg. The evaluations of the ergonomics conditions of the simulated tasks were done by six professional ergonomists working at Volvo Car Corporation in Gothenburg. The results show that digital human modelling tools (DHM-tools) are useful for the purpose of providing designs for standing and unconstrained working postures. Furthermore, the design of various auxiliary devices and their needed space for movements is a prevalent use of DHM-tools. However, the study also identifies areas that require additional development in order to further improve the digital human modelling tools' possibility to correctly predict a work task's real outcome, i.e. hand access, push pressure and pull forces, leaning and balance behaviour and field of vision. Moreover, a better feedback of product and process changes and a more careful order description of simulation cases to the simulation engineers would lead to improved simulation results in current and future projects.Relevance to industry: DHM-tools are increasingly the major means used to perform ergonomics analyses of manual assembly tasks in the automotive industry, but there is still a need for improvements of the tools. It is of great importance to disseminate end users' experiences of the use of different DHM-tools so these can be developed and applied in a more efficient way.
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| 52782. |
- Lämkull, Dan, 1966
(författare)
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Computer Manikins in Evaluation of Manual Assembly Tasks
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Time to market is a critical success factor in todays business environment. The challange is to reduce the development cycle without sacrificing the performance and quality of products and production systems. With the short-lived products of todays competetive global markets most of the engineering has to be done before the start of the production and simultaneous with product development simultaneous engineering.Any use of computer software to solve engineering problems is called computer-aided engineering, and has become one of the most important tools for simultaneous engineering. Fast, high quality computer graphics now allow us to render lifelike images of people performing a multitude of tasks within various computer aided engineering programs. Thus it now is possible to position and move manikins to predict the performance capabilities of designated groups of people within a computer rendered environment. Digital human modelling tools have been introduced in industry to facilitate a faster and more cost efficient design process. Most of the tool users are in the fields of automotive and aerospace engineering. The tools are applied in the design, modification, visualization and analysis of human workplace layouts and/or product interactions.Focus of research within ergonomics simulation has primarily been related to improve the simulation tools with more enhanced functionalities resulting in better and more accurate posture and motion algorithms and biomechanical models. Considerably less research has been conducted to investigate the needs of organizations and end users and their experiences of using the digital human modelling tools.The aim of the research in this thesis is to enlighten the importance of some of the features which can make the manufacturing simulation results more realistic and increase their credibility. Two studies are presented. The aim of the first study was to investigate whether different appearances of manikins in detail levels and genders influence the observers ergonomics posture evaluations, as well as to see if the evaluations differ between the three working disciplines: manufacturing managers, simulation engineers and ergonomists. The primary aspect addressed by the second study was whether repeated simulation results achieved by using a posture prediction tool were more uniform than results achieved by manual manipulating of all body angles. The uniformity was compared both among users and within users. Another aspect addressed was time needed to carry out a simulation case when using a posture prediction tool or not.Results from the first study show that manufacturing managers and simulation engineers were influenced by the appearance whereas ergonomists showed no significance in being influenced by the appearance of the manikins. Moreover, only the ergonomists could distinguish between the different workpostures used in the study. These were different in workload and classified according to the OWAS-system. Results from the second study show that the use of a posture prediction tool, in such complex tasks as the study included, neither reduced time needed to fulfill a simulation, nor differences within or among simulation engineers, at least not significantly. Differences in simulation results often originate from the different assumptions the simulation engineers have of the task when positioning the manikins. The differences could be minimized by a more careful order description and by such activities as simulation engineering days at assembly plants and by bringing the people working with human simulation tools together in the organization.
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| 52783. |
- Lämkull, Dan, 1966
(författare)
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Computer Manikins in Evaluation of Manual Assembly Tasks
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Digital human modelling (DHM) tools have been introduced in industry to facilitate a faster and more cost efficient design process. The research in this thesis is directed towards the DHM-tool-users’ needs and the objective is to identify difficulties and shortcomings, and identify requirements for improving the output of DHM-simulations.The research is directed towards both the tool functions and the processes related to the use of the tools. Five studies are presented in the thesis.In the first study three examples of the development of DHM-based company-specific ergonomics evaluation methods and work processes are portrayed. These illustrate the use of DHM-tools for performing static work and occupant packaging analyses, as well as customizing activities made for the implementation of the tools in companies’ work processes. This is followed by a discussion of future needs of DHM-tools including the call for ergonomics methods for evaluating full work cycles.The second study shows that DHM-tools correctly predict ergonomics issues for standing and unconstrained working postures. However, for more complex and constrained working postures the tools must be used with caution to prevent an unlikely working posture from being the result/outcome of an ergonomics simulation. The third study confirms that posture differences are found in simulation results between users who carry out identical simulation cases. However, humans are different and tasks are carried out differently. Thus, simulation engineers should preferably simulate and visualize a number of different strategies when analysing work tasks. The fourth study illustrates how the appearance of a manikin used when showing and visually evaluating ergonomics conditions makes a difference. Knowledge in ergonomics and/or experience of making visual ergonomics posture evaluations decreases the appearance modes’ influences on the observers. The fifth study exemplifies a method where time sensitive wrist exposure data are extracted from a manikin’s wrist movements. The results show that the exemplified method makes it easy to compare simulations with data from avaliable field studies. However, to be able to use the data to predict prevalence for work-related musculoskeletal disorders additional research is needed to understand the different exposure-dimensions’ (position, velocity, rest) importance as epidemiological risk factors.
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| 52784. |
- Lämkull, Dan, 1966, et al.
(författare)
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Consistency in figure posturing results within and between simulation engineers
- 2006
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Konferensbidrag (refereegranskat)abstract
- This paper presents the results of an effort to compare figure posturing results within and between simulation engineers. The simulation engineers simulated four manual tasks. Alternately they used a posture prediction tool, and alternately they were only allowed to apply manual adjustments of the body angles. The simulation engineers repeated each task six times and always with at least six days between each occasion, to minimize the subject's rememberance of how she/he carried out the cases. Results show that the use of a posture prediction tool, in such complex tasks as the study includes, neither reduces needed time to fulfill a simulation, nor differences within or between simulation engineers. Differences in simulation results often originate from the different assumptions the simulation engineers have of the task when positioning the manikins. The differences could be minimized by a more careful orderer description and by such activities as simulation engineering days at assembly plants and by bringing the people working with human simulation tools together in the organization. Copyright © 2006 SAE International.
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| 52785. |
- Lämkull, Dan, 1966, et al.
(författare)
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DHM - Evaluation Tools.
- 2008
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Ingår i: Handbook of Digital Human Modeling: Research for Applied Ergonomics and Human Factors Engineering (Human Factors & Ergonomics). Vincent. G. Duffy (Ed.). Taylor & Francis, CRC Press.. - 0805856463
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter will only briefly describe the most commonly used evaluation tools for physical work loads, body postures, reach abilities and fields of vision integrated in different Digital Human Modelling Software (DHMS). We try to do so in a way that is neither too specific to any particular DHMS nor so generic that all evaluation tools, more or less integrated in DHMS, are covered. The continuation of this chapter is structured according to the different tool sets that are available in the most commercial DHMS. We have chosen to divide the tool sets into three groups: 1) Quantitative evaluation tools, 2) Semi-quantitative tools and 3) Tools for discomfort, anthropometry, human performance and cognition. The main focus of this chapter is addressed to group one (quantitative evaluation tools), whereas group two and three are less extensive.
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| 52786. |
- Lämkull, Dan, 1966, et al.
(författare)
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DHM in Automotive Manufacturing Applications
- 2008
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Ingår i: Handbook of Digital Human Modeling: Research for Applied Ergonomics and Human Factors Engineering. Duffy, V.G. (Ed.). Taylor & Francis, CRC Press.. - 0805856463
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter covers the main reasons for the use of Digital Human Modelling tools in the automotive manufacturing industry. The focus is entirely on physical digital human modelling, not on cognitive digital human modelling. Important aspects regarding work process and organization are covered as well as how companies deal with some identified shortcomings. The chapter also describes how fewer physical prototype vehicles has made it necessary to find new methods for training of operators adapted to the new conditions. Finally, also an example of a simulation case from the order of the case to the result presentation is given.
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| 52787. |
- Lämkull, Dan, 1966, et al.
(författare)
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Digital Human Models' Appearance Impact on Observers' Ergonomic Assessment
- 2005
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Ingår i: SAE Technical Papers. - 400 Commonwealth Drive, Warrendale, PA, United States : SAE International. - 0148-7191 .- 2688-3627.
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this paper is to investigate whether different appearance modes of the digital human models (DHM or manikins) affect the observers when judging a working posture. A case where the manikin is manually assembling a battery in the boot with help of a lifting device is used in the experiment. 16 different pictures were created and presented for the subjects. All pictures have the same background, but include a unique posture and manikin appearance combination. Four postures and four manikin appearances were used. The subjects were asked to rank the pictures after ergonomic assessment based on posture of the manikin. Subjects taking part in the study were either manufacturing engineering managers, simulation engineers or ergonomists. Results show that the different appearance modes affect the ergonomic judgment. A more realistic looking manikin is rated higher than the very same posture visualized with a less natural appearance. Therefore, it is important to educate human simulation tool users to always combine visualizations (pictures) with an objective ergonomic evaluation method.
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| 52788. |
- Lämkull, Dan, 1966, et al.
(författare)
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Proactive ergonomics and virtual ergonomics within Manufacturing Department at Volvo Car Corporation.
- 2007
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Ingår i: Proceedings of the 39th annual Nordic Ergonomic Society Conference, Lysekil, Sweden, October 1-3, CD-ROM.. ; , s. 6-
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Konferensbidrag (refereegranskat)abstract
- This paper covers the main reasons for proactive ergonomics and the use of Digital Human Model tools (DHM tools or manikin tools) in the automotive manufacturing industry. The tools are applied in the design, modification, visualization and analysis of human workplace layouts and/or product interactions. The paper explains why the manikin is used during the manufacturing development process, from the earliest phase to start of production. Setting early ergonomic requirements aims at several goals simultaneously: preventing work related musculoskeletal disorders, creating good assembly premises, attaining good quality work and keeping costs as low as possible. The paper also mentions important prerequisites for a successfull use of DHM tools. Furthermore, the paper stresses the needs for methods able to assess motions and cost/benefit calculations connected to results from ergonomics analysis.
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| 52789. |
- Lämkull, Dan, 1966
(författare)
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The daily use of manikins within the manufacturing department at Volvo Car Corporation – working methodology, developments and wanted improvements.
- 2005
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Ingår i: In: Proceedings of 37th Annual Conference of Nordic Ergonomics Society, October 10-12, Oslo, Norway. - 8299574714 ; , s. 86-90
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Konferensbidrag (refereegranskat)abstract
- This paper describes the daily use of manikins (computerized human models) within the manufacturing department at Volvo Car Corporation. The paper explains how the manikin is used during the manufacturing development process, from the earliest phase to start of production, and gives examples of which questions that can be answered by using computerized human models. The paper also enlightens limitations in the software/technique and also raises the importance of participatory ergonomics and multidisciplinary work groups when simulating ergonomics.
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| 52790. |
- Lämkull, Dan, 1966, et al.
(författare)
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The influence of virtual human model appearance on visual ergonomics posture evaluation.
- 2007
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Ingår i: Applied Ergonomics. - : Elsevier BV. - 1872-9126 .- 0003-6870. ; 38:6, s. 713-722
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to investigate whether the appearance of virtual human models influences observers when judging a working posture. A task in which a manikin is manually assembling a car battery was used in the experiment. In total, 16 different pictures were presented to the subjects. All pictures had the same background, but included a unique posture and manikin appearancecombination. 24 subjects consisting of manufacturing managers, simulation engineers and ergonomists were asked to rate and rank the pictures. The results showed that the virtual human model appearance influenced subjects when they rated pictures one by one: a more realistic manikin was rated higher than the identical posture visualized with a less natural appearance. This appearance effect was notseen when subjects ranked the pictures while looking at all of them at the same time. The study demonstrates that the human modelling tool used when showing and visually evaluating results makes a difference. To minimize subjective effects, a combination of visualizations and objective ergonomic assessment methods is recommended.
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