New Optimized Dynamic Calibration Proposition for Discretized Sensorized Insoles With Resistive Force Sensor: A Descriptive and Comparative Study

Abstract

Sensorized insoles (SIs) have been used as a wearable instrument to study human gait and have the potential to identify and predict pathologies and injuries. However, most of these sensorized insoles are only statically calibrated, relying on a scale and known weights to establish a relationship between electrical signals and the load applied on laboratory benches while ignoring the dynamic interaction between person and instrument. This study proposes and verifies a calibration method complementary to static calibration to compensate for different dynamic interactions between the insole and the individual during gait. In order to perform this comparison, a laboratory test was proposed with 32 volunteers (18 men and 14 women). Each volunteer walked on a double-belt instrumented treadmill (Bertec at 1000 Hz, Bertec Corp, Columbus, OH) while wearing an experimental resistive sensorized insole (SI). The SI data were compared with the instrumented treadmill and adjusted using an optimization algorithm to create a dynamic coefficient to complement and optimize the results. This study also verifies the impact of the method considering three different types of gait: pronated, neutral, and supinated. After using this technique and considering static calibration, the Pearson correlation coefficient between the SI and the instrumented treadmill improved by 12%.