| 52751. |
- 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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| 52752. |
- 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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| 52753. |
- 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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| 52754. |
- 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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| 52755. |
- 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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| 52756. |
- 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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| 52757. |
- 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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| 52758. |
- 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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| 52759. |
- Lämkull, Dan, 1966, et al.
(författare)
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Uniformity in manikin posturing: A comparison between posture prediction and manual joint manipulation
- 2008
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Ingår i: International Journal of Human Factors Modelling and Simulation. - 1742-5549. ; 1:2, s. 225-243
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the results of a comparison of manikin posturing within and between simulation engineers. Five simulation engineers were asked to simulate and visualize four manual assembly cases. They repeated each task six times, three times with a posture prediction tool and three times with manual adjustment of the body angles. The results show that the posture prediction tool was not used in an optimal manner. Although the prediction tool was quick at suggesting a likely posture, the simulation engineers were reluctant to consider a simulation task completed until the manikin’s posture was realistic in all aspects, not only in the configurations for the major body joints postures but also for fingers, wrists and feet. This fine tuning of fingers is performed with manual manipulation of joints and cancels out the time gained with the posture prediction tool. The fine tuning does not affect the results in objective evaluation methods. Therefore, a lower acceptance level of correctness among managers, simulation engineers and ergonomic specialists is desired, or a shift from visualization to simulation is necessary. Manikin postures differ between simulation engineers. A posture variation exists and this variation in working behaviour should be accepted and simulated. However, simulation engineers also need more extensive knowledge of how workers actually behave on the assembly line; study visits are thus recommended. A shift is also recommended from simulations and visualizations of normal working behaviours to that of ergonomically correct behaviours. This comparison of manikin posturing within and between simulation engineers is an attempt to understand the use of the tool in a practical sense. The comparison indicates that if a posture prediction tool is to be beneficial for the whole organisation, all disciplines involved in the use of manikins must accept simulation results with postures containing some non-cosmetic elements. It is not until such an acceptance is achieved that the successful use of a posture prediction tool will become a reality.
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| 52760. |
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