Measurement of Contact Stresses on the Sole of the Foot During Walking Using a Wearable Measurement System

Hiiro Kimura, Kazuhiko Sasagawa, Kazuhiro Fujisaki
Vol. 12 (2023) p. 147-153

Motion analysis can be performed during walking by measuring the contact pressure and shear stress acting on the body surface. Although floor reaction force gauges and stress sensors embedded in shoe soles are often used to measure triaxial stress acting on the sole of the foot, the stress acting on the contact interface is difficult to measure directly. In recent years, we have developed thin and flexible triaxial stress sensors that may be placed directly at the contact interface of the body, thus enabling the measurement and evaluation of contact stress in a more natural state. In this study, we developed a compact wearable measurement system that does not restrict the conditions of measurement such as range of motion and motion environment. The compact wearable measurement system consisting of a microcomputer and a sensor measurement circuit was developed for use with triaxial stress film sensors. The signals from the sensor circuit were processed by a program in the microcomputer and recorded on a microSD card to realize a measurement system that does not require cable connection to an external power supply or computer. Sensors were placed on the thenar and heel of the foot, and the usefulness of the system was evaluated by comparing the contact stresses acting on the foot while walking on a flat indoor track. We confirmed the validity of the wearable measurement system by measuring the values of contact pressure and shear stress acting on each measurement part during walking on the flat indoor track. Furthermore, the developed system was applied to gait measurement during walking on snow covered roads. With further improvements in this system, its application in rehabilitation and sports medicine is expected.