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Evaluation of the manikin building function in eM-RAMSIS when using Motion Capture
2007 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

This thesis project was formulated by Volvo Cars to find an answer to the question if an investment in a manikin building software was necessary or if the existing manikin eM-RAMSIS could produce valid results when using Motion Capture data to guide it. Motion Capture is a system for recording an objects motion and transforming it to a digital form which can be utilized to guide the motions or postures of various digital objects, in this case computer manikins. A computer manikin is a digital human model and has all the characteristics of a human: joints that are restricted to movements in only some directions, hands that can grasp things etc. These manikins are used by Volvo Cars to simulate working postures for the assembly workers who will work on the assembly lines of future car models. The manikins have been positioned after the best knowledge of the simulation engineer using mouse and keyboard. However with this new technique it is possible to record the actual position of an assembly worker in the Motion Capture lab. Research conducted on the subject of Motion Capture and manikins show that it is crucial that the manikin closely resembles the person recorded. The manikin available for simulation engineers on Volvo Cars is eM-RAMSIS who only has three possible adjustments: length, sitting height and circumference. Thus the question arose whether eM-RAMSIS could produce valid results or not. Three tests were originally carried out to find an answer to the question. The first test was aimed at examining the markerset used and verifying it, the result being to stick to the original markerset of 42 markers. The second test was designed to try to find some postures where the manikin encountered trouble and the postures identified were further analyzed and used as input in the design of the main test. This third test was performed by a test group of eleven, six female and five male participants of different anthropometry. The test consisted of different stretching and twisting tasks. The one which caused the manikin the most problems was reaching forward to the maximum while leaning forwards supported by a table frame. This task was extensively analyzed, taking the manikin to a virtual table and measuring how far it could reach and comparing this with the values from the test session. In general the manikin reached shorter than the test objects, in some cases up to 20 cm. Since there were many possible sources of error in the main test it was decided to do a supplementary test where the variables were cut down to a minimum. The position of the feet was exactly marked out on the floor and carefully measured against the table frame. For measuring of the reaching distance a cord with a stripe running on it was fastened on the table frame. This making the fingertip of the test object identified in three dimensions at the extreme of the motion. The test object was accurately positioned on the markings for the feet before the recording started. The analysis of the supplementary test showed the same behavior as the previous test: that the manikin could not reach as far as the actual person. A measurement showed that the manikin had longer arms than the test objects. It would appear that the manikin has some built in limitations as to how it can move and be positioned. When reaching far a human lets the shoulder follow the arm forwards and also twists the back to reach even further, this behavior can not be mimicked by the manikin when using Motion Capture data. To be able to answer the question whether the manikin created with Human Builder would produce better results comparing studies will have to be performed and has not been performed since the software was not available during the course of this thesis project. There has been no behavior observed where it could be determined that it would not have occurred with a more anthropometrically correct manikin. The recommendations which will conclude this project are to do a comparison study using manikins created in Human Builder, to utilize all settings available for the eM-RAMSIS manikin, to unmark markers to instantly create a better manikin posture, to move the Motion Capture cameras when using many props to ensure a better data collection and using additional camera views to collect more photographic material that can be used as reference for judging the manikin posture.

Place, publisher, year, edition, pages
Keyword [en]
Technology, digital human model, simulation, manikins
Keyword [sv]
URN: urn:nbn:se:ltu:diva-45567ISRN: LTU-EX--07/122--SELocal ID: 3405c8bd-21d6-42a4-9b2a-7b0e9bae6b5bOAI: diva2:1018861
Subject / course
Student thesis, at least 30 credits
Educational program
Ergonomic Design & Production Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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