Human Center of Mass Trajectory Estimation Based on the IMU System

The dynamics of body center of mass (CoM) 3D trajectory during locomotion is crucial to the mechanical understanding of the different gaits. Forward Dynamics (FD) obtains CoM motion from ground reaction forces while Inverse Dynamics (ID) estimates CoM position and speed from motion capture of body segments. These two techniques are widely used by the literature on the estimation of CoM. In this paper, a self-contained procedure to estimate the CoM trajectory of a single sacrum-worn inertial measurement unit (IMU) is presented, which can be related to the human body center of mass (CoM) displacement during walking through an adaptation of the sacral marker method. The proposed method uses only IMU to gather the movement information of the subject, without the requirement for additional external positioning facilities. This enables the CoM trajectory can be obtained in both indoor and outdoor scenarios. The effectiveness of the IMU-based human CoM trajectory measure method will be verified by comparison experiments with using motion capture system.