Measurement of the inter-foot distance using a Time-of-Flight proximity sensor: preliminary evaluation during leg oscillation exercises

The distance between the feet during walking could be a key factor to better understand gait stability. The aim of this work was to investigate the application of an Infrared Timeof-Flight sensor in the inter-foot distance estimation during leg oscillation exercises. The results, compared to a stereophotogrammetric system used as gold standard, showed a mean absolute error between 3.6 mm and 6.9 mm and a mean absolute percentage error in the range of 1.9% to 3.8%. An improvement of 50% (6 mm) in the inter-foot distance accuracy, compared to a wearable platform based on ultrasound and inertial sensors, was observed.