Geometry-based Computational Methodology to Reduce Markers Deviation

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Abstract

Nowadays, determination of the ankle angular displacement and angular velocity are very common in sports biomechanics. The determined human biomechanics can be used to evaluate the surgical outcome of patients after surgery and the effects of ankle supportive braces (Figures 1). Human biomechanics are usually determined by the marker-based motion capture system. In order to compute the biomechnaics of ankle joint, markers are usually attached to the the fifth metatarsal head, heel, lateral malleolus and medial malleolus (Figure 2). Nevertheless, it is known that computation of human biomechanics is significantly affected by the deviation of markers positions [2, 3]. Particularly, the markers at the lateral malleolus and medial malleolus will have large deviation with the original position when the subjects are wearing ankle supportive braces (Figure 1b). In order to reduce the computational errors due to the deviation of markers positions, a simple and fast geometry-based computational methodology is proposed.
The methodology makes use of the simple human anatomical geometry and the thickness of the brace compartments to estimate the original position of the markers (Figure 3). Then, the estimated position of the markers are used to determine the biomechanics of the ankle. In order to validate our methodology, experimental results of a subject with and without applying the proposed methodology were compared with the biomechancis of a subject without wearing ankle supportive brace. Experimental results showed that the proposed methodology can reduce the error of ankle biomechanics due to the deviations of the markers effectively.
Original languageEnglish
Title of host publicationProceedings of the 2nd International Symposium on Computational Mechanics
Place of PublicationHong Kong
Publication statusPublished - Nov 2009

Keywords

  • ankle
  • braces
  • biomechanics
  • markers
  • motion capture system

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