| 1. |
- 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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| 2. |
- Johansson, Björn, 1975, et al.
(författare)
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Power Level Sampling of Metal Cutting Machines for Data Representation in Discrete Event Simulation
- 2015
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Ingår i: International Journal of Production Research. - : Informa UK Limited. - 0020-7543 .- 1366-588X. ; 53:23, s. 7060-7070
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Tidskriftsartikel (refereegranskat)abstract
- An extension to the application area for discrete event simulation (DES) has been ongoing since the last decade and focused only on economic aspects to include ecologic sustainability. With this new focus, additional input parameters, such as electrical power consumption of machines, are needed. This paper aim at investigating how NC machine power consumption should be represented in simulation models of factories. The study includes data-sets from three different factories. One factory producing truck engine blocks, one producing brake disc parts for cars and one producing forklift components. The total number of data points analysed are more than 2,45,000, where of over 1,11,000 on busy state for 11 NC machines. The low variability between busy cycles indicates that statistical representations are not adding significant variability. Furthermore, results show that non-value-added activities cause a substantial amount of the total energy consumption, which can be reduced by optimising the production flow using dynamic simulations such as DES.
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| 3. |
- Berlin, Cecilia, 1981, et al.
(författare)
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Corporate-internal vs. national standard - A comparison study of two ergonomics evaluation procedures used in automotive manufacturing
- 2009
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Ingår i: International Journal of Industrial Ergonomics. - : Elsevier BV. - 0169-8141 .- 1872-8219. ; 39:6, s. 940-946
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Tidskriftsartikel (refereegranskat)abstract
- Manufacturing corporations sometimes use corporate-internal procedures to evaluate and monitor the ergonomic status of the workplace. This article describes an industrial case study in the Swedish automotive sector, where an internally developed evaluation procedure was compared with a procedure based on a Swedish national standard provision. It was found that the national standard procedure tended to give more severe ratings and statistical support shows that the two evaluation procedures are not equivalent. The ability of the methods to identify body segments at risk was also compared. The quantitative comparison was followed up with interviews, where the influence of professional tasks and objectives became evident, as well as the fact that evaluation criteria are quantified differently by the two procedures. The main finding is that unforeseen differences in analysis procedure, criteria of acceptability and levels of detail can cause use-related difficulties for different professional groups when methods are used interchangeably. Relevance to industry: Industrial corporations wishing to monitor ergonomics consistently are advised by the authors to ensure that ratings from internal evaluations are interpreted the same way by all involved personnel, and that they at least have criteria levels equivalent to those of a national standard. (C) 2009 Elsevier B.V. All rights reserved.
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| 4. |
- Blomé, Mikael, et al.
(författare)
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Structured time observation of human modelling tool users' activites.
- 2006
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Ingår i: In: Proceedings of 16th Triennial World Congress on Ergonomics, International Ergonomics Association, 2006, July 10-14, Maastricht, The Netherlands..
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Konferensbidrag (refereegranskat)abstract
- Most statements regarding human modeling tools efficiency are based on perceived time. No structured timeobservation of task activities performed by a simulation engineers working with the tools are previous performed.The aim of the study is to identify digital human modelling tool users’ activates and measure the time distributionof the activities. Furthermore, measured time distribution is compared with users perceived time distribution.Five simulation engineers at Volvo were observed for five days each. The simulation engineers’ activities can becategorised in twelve groups. The direct value added work and the indirect value added work important for a newintroduced tool were of similar size as direct value added work for a vehicle disassembly worker. Waiting time, theresimulation is out of control e.g. waiting for information from colleague and computer processor, was perceived muchlonger compared to measured time.The human modelling tool seems to have matured and most of the activities identified seems to be necessary to perform human modelling simulations of high quality; however the time distribution could to some extend be questioned. There are a lot of activities associated with communication, i.e. different kinds of contacts and meetings. Therefore it appears to be a potential to increase efficiency with respect to communication.
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| 5. |
- Flores-García, Erik, et al.
(författare)
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Characterizing Digital Dashboards for Smart Production Logistics
- 2022
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Ingår i: Advances in Production Management Systems. Smart Manufacturing and Logistics Systems: Turning Ideas into Action. - Cham : Springer Nature Switzerland AG. - 9783031164101 - 9783031164118 ; , s. 521-528, s. 521-528
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Konferensbidrag (refereegranskat)abstract
- Developing digital dashboards (DD) that support staff in monitoring, identifying anomalies, and facilitating corrective actions are decisive for achieving the benefits of Smart Production Logistics (SPL). However, existing literature about SPL has not sufficiently investigated the characteristics of DD allowing staff to enhance operational performance. This conceptual study identifies the characteristics of DD in SPL for enhancing operational performance of material handling. The study presents preliminary findings from an ongoing laboratory development, and identifies six characteristics of DD. These include monitoring, analysis, prediction, identification, recommendation, and control. The study discusses the implications of these characteristics when applied to energy consumption, makespan, on-time delivery, and status for material handling. The study proposes the prototype of a DD in a laboratory environment involving Autonomous Mobile Robots.
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| 6. |
- Högberg, Dan, et al.
(författare)
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Industrial customisation of digital human modelling tools
- 2008
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Ingår i: International Journal of Services Operations and Informatics. - 1741-5403 .- 1741-539X. ; 3:1, s. 53-70
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Tidskriftsartikel (refereegranskat)abstract
- Computer aided visualization and simulation enables early evaluation of important design parameters of future products and production systems. Typically, humans affect the system performance, and in order to achieve the expected system efficiency ergonomics needs to beconsidered in the design process in addition to the more technical or logistical matters. Hence, there is a call for ergonomics to be a natural part of the product and production development process,also at virtual stages. Three examples of the development of DHM (digital human modelling) based company-specific ergonomics evaluation methods and work processes are portrayed, argued anddiscussed. These illustrate the use of DHM tools for performing static work and occupantpackaging 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.
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| 7. |
- Örtengren, Roland, 1942, et al.
(författare)
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Digital Human Modeling Simulation Results and Their Outcomes in Reality : A Comparative Study within Manual Assembly of Automobiles
- 2009
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Ingår i: SAE International Journal of Passenger Cars - Mechanical Systems. - : SAE International. - 1946-3995 .- 1946-4002. ; 2009
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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 automotive assembly plants, and if recommended measures originating from ergonomics simulations are considered. 155 ergonomics simulation cases done by nine simulation engineers at Volvo Car Corporation in Gothenburg were used in the study. The evaluations of the ergonomics conditions in reality of the cases were done by six professional ergonomists working in the company. The results show that digital human modelling tools are useful for providing designs for standing and unconstrained working postures as well as for the design of various auxiliary devices and their needed space for movements. The study also identifies areas that require additional development in order to improve the digital human modelling tools’ ability to correctly predict a work task's real outcome. Moreover, a better feedback of product and process changes, and a more careful order description to the simulation engineers, would improve simulation results in current and future projects.
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| 8. |
- Bertilsson, Erik, et al.
(författare)
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Using experimental design to define boundary manikins
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 41, s. 4598-4605
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 9. |
- Delfs, Niclas, et al.
(författare)
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Introducing Stability of Forces to the Automatic Creation of Digital Human Postures
- 2013
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Ingår i: 2nd International Digital Human Modeling.
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Konferensbidrag (refereegranskat)abstract
- Although the degree of automation is increasing in manufacturing industries, many assembly operations are performed manually. To avoid injuries and to reach sustainable production of high quality, comfortable environments for the operators are vital. Poor station layouts, poor product designs or badly chosen assembly sequences are common sources leading to unfavorable poses and motions. To keep costs low, preventive actions should be taken early in a project, raising the need for feasibility and ergonomics studies in virtual environments long before physical prototypes are available. Today, in the automotive industries, such studies are conducted to some extent. The full potential, however, is far from reached due to limited software support in terms of capability for realistic pose prediction, motion generation and collision avoidance. As a consequence, ergonomics studies are time consuming and are mostly done for static poses, not for full assembly motions. Furthermore, these ergonomic studies, even though performed by a small group of highly specialized simulation engineers, show low reproducibility within the group.Effective simulation of manual assembly operations considering ergonomic load and clearance demands requires detailed modeling of human body kinematics and motions as well as a fast and robust inverse kinematics solver. In this paper we introduce a stability measure rewarding poses insensitive to variations in contact points and contact forces. Normally this has been neglected and only the balance of moment and forces has been taken into account. The manikin used in this work has 162 degrees of freedom and uses an exterior root. To describe operations and facilitate motion generation, the manikin is equipped with coordinate frames attached to end-effectors like hands and feet. The inverse kinematic problem is to find joint values such that the position and orientation of hands and feet matches certain target frames during an assembly motion. This inverse problem leads to an underdetermined system of equations since the number of joints exceeds the end-effectors’ constraints. Due to this redundancy there exist a set of solutions, allowing us to pick a solution that maximizes a scalar valued comfort function. Many objectives are included in the comfort function, for example in terms of joint angles, joint moments and solid objects’ distance to the manikin. The proposed stability measure complements the earlier balance criterion and is combined into the comfort function. By increasing the importance of this function the digital human model will reposition to a more stable pose. The digital human model will be tested on a set of challenging assembly operations taken from the automotive industry to show the effect of the stability measure.
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| 10. |
- Hanson, Lars, et al.
(författare)
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Digital test assembly of truck parts with the IMMA-tool - an illustrative case
- 2012
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Ingår i: Work. - : IOS Press. - 1051-9815 .- 1875-9270. ; 41:Suppl 1, s. 2248-2252
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Tidskriftsartikel (refereegranskat)abstract
- Several digital human modelling (DHM) tools have been developed for simulation and visualisation of human postures and motions. In 2010 the DHM tool IMMA (Intelligently Moving Manikins) was introduced as a DHM tool that uses advanced path planning techniques to generate collision free and biomechanically acceptable motions for digital human models (as well as parts) in complex assembly situations. The aim of the paper is to illustrate how the IPS/IMMA tool is used at Scania CV AB in a digital test assembly process, and to compare the tool with other DHM tools on the market. The illustrated case of using the IMMA tool, here combined with the path planner tool IPS, indicates that the tool is promising. The major strengths of the tool are its user friendly interface, the motion generation algorithms, the batch simulation of manikins and the ergonomics assessment methods that consider time.
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