Nihon Kikai Gakkai ronbunshu (Aug 2018)
Investigation of analysis method of prosthetic running using motion sensors (Derivation of ground reaction force estimation value through all running process)
Abstract
This study proposes a method to measure ground force outside the laboratory using motion sensors. The authors estimated ground reaction force (GRF) from the measurements obtained by a motion sensor at an athletics track with no force plates installed. First, experimental data were measured in the laboratory using motion sensors and a 3D motion analysis system and by motion sensors and force plates. Data were compared using three types of prosthetic foot parts with different shapes and rigidities and were evaluated using a root mean square error method. As a result, the estimation accuracy of the displacement of the prosthetic foot and GRFs were high, and the laboratory experiment demonstrates the accuracy of the proposed method. In the second measurement, the authors measured a 60 m run at a stadium comparing two subjects with different competition levels. The GRF of subject A showed values of 2.8 to 3.5 times the body weight whereas subject B showed a value of 1.8 to 2.5 times the body weight. As a result of comparing trunk momentum and prosthesis side, in the stance phase of subject B, the trunk went up, and only the movement on the prosthesis side was used to obtain propulsive force. This may be due to the timing of the trunk and lower limb being unsynchronized. Furthermore, the trunk momentum of both subjects was compared using wavelet analysis. In Subject B, a larger value also appeared at high frequencies other than the main component. This is considered to be due to a difference in the movement of the lower limb during the swing phase. Based on these findings, this analysis method could be useful, and the GRF measured with this analysis method may be an important index in the evaluation of running motion, parts selection, setting of prostheses, and coaching.
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