Development of a wearable shear and normal ground reaction force measuring system for running and jumping

Abstract

The force between the ground and a human foot is specifically called ground reaction force (GRF), which is important for evaluating the performance of athletes and identifying injuries in sports biomechanics. Especially, investigating vertical GRF (vGRF) and anterior-posterior GRF (A-P GRF) is important during walking, running, and jumping which are the fundamental movements of sports. In this study, a wearable two axes GRF measuring system was developed to measure vGRF and A-P GRF during walking, running and jumping. First of all, a high capacity two axes (normal force and shear force) force sensor was developed and the characteristic of the sensor, such as linearity, hysteresis, repeatability, interference rate, and impact response, were examined. Next, a wearable GRF measuring system was developed by installing eight of the developed force sensors in specific locations. A forefoot bending stiffness test was conducted to confirm the comfortability of the system. GRF measurement tests during walking, running, and jumping tests on a commercial force plate were also carried out on three subjects wearing the system. Finally, a center of pressure (COP) estimation test was conducted to validate the developed system. It was found that the developed system guaranteed comfortability for the users and it was able to measure partial vGRF and A-P GRF for certain regions where the force sensors were installed. The results suggest that the developed system could be used in the investigation of performance of athletes and injury identification.