Human body model based inertial measurement of sit-to-stand motion kinematics

In the paper a method for measuring kinematics of sit-to-stand motion using inertial sensors and human body model is presented. The proposed method fuses data from inertial sensors and data from three-segment human body model using Extended Kalman filtering technique and in this way alleviates some of the drawbacks associated with inertial sensors. Dynamic human body model is constructed based on principles of Lagrangian dynamics and incorporates shank, thigh and HAT (Head-Arms-Trunk) segments. The moments required in obtained model equations (ankle, knee and hip moments) are calculated based on the EKF last best estimate and Newton-Euler inverse dynamic approach. Outputs from the EKF are segment angles (orientations), angular rates of change (angular velocities) and angular accelerations. The performance of the method is verified by the measurements acquired with Optotrak optical motion analysis system. Obtained results are presented and discussed.