Using Cosserat Point Theory for Estimating Kinematics and Soft-Tissue Deformation During Gait Analysis

Abstract

Analyzing the biomechanics of human or animal motion requires a kinematical characterization of the motion of body segments as a function of time. Common noninvasive techniques for motion tracking involve placing markers on the skin of the body part and using a motion capturing system to track the marker positions. Determining the underlying joint motion requires processing the acquired marker coordinates. This is typically done using the assumption of rigid body motion of the segment even though soft tissues deform and marker acquisition is imperfect. In this paper, a new method is presented based on a continuum mechanics approach to estimate motion of body segments while assuming a non-rigid body transformation. The new method, based on the theory of a Cosserat Point, explicitly accounts for the fact that the marker kinematics include not only translation and rotation but also the associated and possibly large deformation of the body part. The method was validated with an experimental setup and the results were compared to ground truth results also obtained during the experiment.