Performance evaluation of lower limb ambulatory measurement using reduced Inertial Measurement Units and 3R gait model

The Inertial Measurement Units (IMUs) have been widely used equipment to measure different parameters during human locomotion. However, the research gap lies in implementing the IMUs to monitor lower limb joint kinematics. This paper presents a novel approach to estimate the lower limb joint angles using only 4 IMUs attached to the heel and pelvis. We model the gait as a planar 3R (R denotes revolute) serial chain and solve its inverse kinematics by using the information obtained from the IMUs. The results are validated by the reference measurements which are simultaneously obtained by an optical motion capture system. The results show that the lower limb joint angles are estimated accurately by our measurement method. This study can benefit the future clinical application on conducting complete outdoor lower limbs kinematics analysis to monitor rehabilitation with unobtrusive and minimal numbers of wearable sensors.