An instrumented shoe to measure vertical foot displacement profile and other gait parameters

Human foot plays an important role in various activities of daily living and therefore many technologies have been developed to measure and study the dynamic behavior of the foot. This study proposes the use of inertial measurement unit and laser ranging sensors to quantify the vertical foot displacement profile during walking. This profile delineates the position of different parts of the foot e.g. forefoot and rearfoot in every gait cycle. Various relevant gait parameters can then be estimated, including stride length, stride time, duration of swing phase, and the maximum and minimum foot clearances. An optical motion capture system was used here to validate the proposed method, with reflective markers placed directly on the instrumented shoe to obtain similar information. A total of 96 steps were evaluated. The maximum and minimum foot clearances were comparable to results obtained using the optical system. An average error of less than 16 mm was found. The results demonstrated the viability of this approach in quantifying the foot motion during walking. They also indicated the potential of the instrumented shoe in capturing motion in an unconstrained environment.