The study of kinematic transients in locomotion using the integrated kinematic sensor

A system based on the integrated kinematic sensor (IKS) was used to study the three-dimensional (3-D) kinematics of human lower limb during walking and running. The linear displacement, angular velocity, and linear acceleration of the foot, shank, and thigh segments were directly measured using three IKS's. The results clearly showed the heel strike impact in both walking and running, illustrating the high frequency components that exist in those activities. This paper illustrates the limitations of standard position measurements to capture transients associated with phase transitions, not only in acceleration estimates, but also in the determination of segmental angular velocities. An error analysis was conducted to determine the relative contribution of the accelerometer and the angular rate sensor to the determination of the segmental center of mass (COM) acceleration. The results suggest that in practical kinesiological applications, adding either an accelerometer or an angular rate sensor can remarkably increase the accuracy of segmental COM acceleration estimates.