Inverse Kinematics of Hybrid Multi-link System and its Application to Motion Capture for Athlete Wearing Sports Prosthesis

This paper presents the kinematics of soft-rigid hybrid multi-link system and its application to motion analysis by the motion capture measurement. Analysis of a gait or sprint motion including a sports prosthetic leg is challenging because we need to consider the interaction between the human body and the flexible deformation of the prosthesis. To precisely calculate the flexible deformation with a low computational cost, we employ the piece-wise constant strain (PCS) model, and integrate it with a rigid-body link system that represents a human skeleton motion. This hybrid link system can appropriately represent the motion of an athlete wearing a prosthesis. In this paper, we focus on the inverse kinematics (IK) that is one of the fundamental calculations to analyze a human motion from the motion capture measurement. We report an experiment of a subject wearing a sports prosthesis and validate that the proposed hybrid link IK can reconstruct the measured motion.