A proposal of elasticity distribution measurement for the foot sole

Abstract

This paper aimed to develop an implementation for measuring the elasticity distribution on the foot sole. In advance to the human experiment, some material foams which were imitate human subcutaneous fat and muscle layers of the foot sole were examined using our implemented device and validated its elasticity. The validation result showed that the relationship between compression depth and reaction force could be expressed as two different piecewise linear approximation and its hysteresis of two-layered structure of the artificial materials. The results of human sole measurements also showed hysteresis characteristics among whole segmented small compartment areas. On the other hand, in some of compartment areas, such as edges of the foot sole or lateral longitudinal arch, reaction force could not be measured due to the slippage in the compression process. The distribution pattern of the reaction forces depended on the subject with the constant depth condition. The quantitative foot sole elasticity obtained using the proposed device may have the potential to design criteria for insoles by prosthetists and orthotist in the future.