To Calculate Reference Movement of Impaired Knee in Real-time Based on Biomechanical Information of the Contra-lateral Healthy Limb

摘要

Reference movement provided for an exoskeleton prosthesis that assists patients in walking is usually given based on statistical gait data of healthy individuals. However, it is easy to cause misidentification of gait?s phase, discontinuity of reference movement and serious asymmetry of two limbs. This study proposes a method to give a reference movement for impaired knee based on biomechanical information of the contra-lateral healthy limb. This can enhance movement symmetry of two limbs. Different phases are identified according to the statuses (peak, valley and zero values, increasing or decreasing) of knee angle, angular velocity, forefoot reaction force and heel reaction force of the healthy limb. The specific statuses rather than numerical values are favourable to enhance accuracy of phase identification and continuity of reference movement. Sine or cosine function is used to express motion trajectory of knee approximately and the period and peak value of the output function can be regulated according to the measured knee angles of the healthy limb. Thus, the reference movement can match that of the healthy knee in real-time even though walking pace and stride length are changed. Verification experiment was performed on four subjects and the results confirmed the feasibility of the proposed method.