著者

井上 喜雄 劉 涛 芝田 京子 園部 元康

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集 (ISSN:21879761)

巻号頁・発行日

vol.83, no.851, pp.17-00029, 2017 (Released:2017-07-25)

参考文献数

11

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We aim to clarify dynamics of the wrist turn of the golf swing and the effect of the parameters on dynamic behavior at the wrist turn using the double pendulum model and the modal analysis method. Eigenvalue analysis was carried out and natural frequency and mode were calculated by using linearized equation of motion assuming the exterior angle of the cock angle is small. We found out that the first mode is a rigid mode and the second one is a vibration mode of the double pendulum, and the mode shapes are constant during the wrist turn even though natural frequency changes. By applying the modal analysis method we obtained equations of motion for the rigid mode and the vibration mode separately. Furthermore, using the theory of linear superposition, the equation of motion for the vibration mode was separated again into 3 equations which can help to understand the mechanism of the wrist turn. After accuracy of the proposed method for small exterior angle of the cock angle was confirmed by comparing with the exact solution using numerical integration, the proposed method was applied to the general case with large exterior angle of the cock angle which has nonlinearity, and the mechanism of the wrist turn and the effect of the parameters of the arm and wrist torque on the dynamic behavior at the wrist turn were clarified qualitatively. Finally parameter survey using the numerical integration for the original nonlinear equation of motion was carried out to show the validity of the proposed method.

著者

芝田 京子 井上 喜雄 岩田 祥孝 片川 準也 藤井 涼

出版者

一般社団法人 日本機械学会

雑誌

日本機械学会論文集C編 (ISSN:18848354)

巻号頁・発行日

vol.78, no.791, pp.2483-2495, 2012 (Released:2012-07-25)

参考文献数

33

被引用文献数

4 8

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Lumbago occurs when load causes malformation of the flexible intervertebral disks of the lumbar vertebrae. The conventional method of measuring load on the intervertebral disk is an invasive method in which the internal pressure of the intervertebral disk is measured by directly inserting an electrode. In this study, intervertebral disk load is derived indirectly by the noninvasive estimation method that uses three-dimensional motion analysis system and signal processing to estimate the shape of the lumbar vertebrae. Specific estimation method is shown as follows. First, vertebra is assumed to a rigid body. Next, lumbar vertebrae are approximated with an arc using 3-D positional coordinates. Finally, average of the intervertebral gap is estimated. Accordingly, because the proposed method only entails applying markers to the surface of the back and taking pictures with cameras, it is safe and does not require surgical procedures. Furthermore, this method allows estimation of intervertebral disk load in a moving subject. In this paper, the proposed method is described in detail. And an experiment in which intervertebral disk load is estimated from stationary postures is executed. Moreover the proposed method is compared with the conventional method. As a results, the experiment shows that the proposed method is effective in that the magnitude correlation tendencies of intervertebral disk load estimated with the proposed method are qualitatively consistent with the tendencies calculated from actual measurements of internal pressure.

著者

柿森 亮昌 錦戸 亮太 勝 隆志 井上 喜雄 芝田 京子 王 碩玉

出版者

一般社団法人日本機械学会

雑誌

機械力学・計測制御講演論文集 (ISSN:13480235)

巻号頁・発行日

vol.2014, pp."130-1"-"130-7", 2014-08-25

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The aim of this study is to improve of stick picture using wearable motion sensor, in order to estimate human joint center and stride. Human joint center was estimated by least square method of sphere and marker points on the human arm were observed by motion analysis system (MAC3D System). First, as a basic experiment, instead of measuring human joint, we made use of a stick which has 490 mm length and two markers were affixed at the end of the stick. Next, it is hard to measure the movement of lower body, we performed an experiment on the movement of arm. As a result, estimated value by sphere method has a higher accuracy than estimated by circle. Finally, gait acceleration value was observed by acceleration sensor. Then, gait acceleration value had coordinate transform toward direction of movement and filtered by low pass filter. After, Gait velocity and acceleration were calibrated to 0 and integrated. In a result, stride was calculated with high accuracy. In this paper, it is shown that estimated stride and value of human joint center were calculated with high accuracy. To summary, these experiments, it is feasible that the accuracy of stick picture using wearable motion sensor is to be improved.