Observation of human multi-joint arm movement from the viewpoint of a Riemannian distance

This paper aims at analyzing dynamic characteristics of human arm movements from the viewpoint of Riemannian distance. In order to evaluate the amount of inertia-induced movement of a multi-joint arm, a measure called inertia-induced measure is developed. By applying the measure to actual human reaching, it is shown that the smooth reaching tends to be closer to the inertia-induced movement than the clumsy reaching. From this observation, it is suggested that humans use their own inertia properties efficiently in smooth reaching.