Analysis of foot shape deformation during walking and its application to designing insole

本研究的目的是测量和定量地阐明步行过程中足型的变化，以便从个体足型中获得设计定制鞋垫的依据。鞋垫可以通过调节脚和楦的形状差异来提高舒适度。为此，我们制作了一个猫步道（BxLxH=100x800x100 [cm]），中间设置了一块玻璃板（35.5x40 [cm]）。在玻璃板下设置4个测力元件，测量地面反力（120 Hz）。用高频摄像机（200赫兹）从玻璃板下方捕捉鞋底的视频图像。在玻璃板周围设置由12台摄像机组成的内部4D形状测量系统，测量足部四个横截面的形状（14 Hz）。对45名受试者在行走和站立时的右脚进行测量，体重均匀分布在双脚上。根据脚底视频图像测量6个测量值，根据脚背横截面数据测量足底弓和背弓高度。将站立时的测量值与地面反力第一个峰或两个峰底部的测量值进行比较。结果发现，与站立时相比，(1)步行时内侧足弓长度增加，外侧足弓长度没有增加；(2)中站阶段球与脚背接触地宽度增大；(3)站立中期足底足弓高度不降低。结果表明，站姿测量的足型可作为设计定制鞋垫的依据。

The purpose of this study is to measure and quantitatively clarify the foot shape changes during walking in order to obtain grounds for designing the custom insole from individual foot shape. Insole can be used to improve the comfort by adjusting the differences between the shapes of the foot and last. For this purpose, a cat walk (BxLxH=100x800x100 [cm]) with a glass plate (35.5x40 [cm]) set in the middle was constructed. Four load cells were set under the glass plate, and the ground reaction force was measured (120 Hz). Video images of the sole were captured with a high frequency video camera (200 Hz) from below the glass plate. An in-house 4D shape measurement system consisting of 12 video cameras was set around the glass plate, and the shapes of four cross sections on the foot were measured (14 Hz). The right foot was measured for 45 subjects during walking and standing with weight distributed equally on both feet. Six measurements were measured from the sole video images, and the heights of the plantar arch and dorsal arch were measured from the instep cross-section data. Measurements at standing were compared with those at the first peak or the bottom of 2 peaks of the ground reaction force. It was found that compared to the measurement at standing, (1) the medial arch length increased but the lateral arch length does not during walking; (2) ground contact breadth at the ball and instep increased at the mid stance phase; (3) height of plantar arch does not decrease during the mid stance phase. The results suggest that the foot shape measured in the standing posture may be used as the basis for designing custom insole.