Estimation of Continous Heel and Toe Clearances Using Foot-Worn Inertial Sensors

Falls happen frequently to older people in their daily life. Heel and toe clearances are regarded as significant indicators for the risk of falling. In this study, we developed a foot-worn inertial system to capture kinematic gait data. An estimation method of continuous heel and toe clearances during walking was proposed. Based on heel strike and toe off events detection, a foot movement model was presented to calculate the continuous heel and toe clearances. To compensate the sensor drift, an algorithm combined Zero Velocity Update, Zero Angular Rate Update, Zero Vertical Displacement Update plus a liner drift correction model was implemented. To verify the effectiveness of the drift compensation algorithm, the calculated IMU clearances before and after the implementation of the algorithm were compared and the walking tests results supported its feasibility. Furthermore, the continuous heel and toe clearances were estimated successfully using the foot movement model.