Effects of joint acceleration on rod's length perception by dynamic touch

Abstract

Studies on dynamic touch have indicated that humans can estimate the length of a rod held in one hand simply by wielding it, without any visual information. Traditionally, these types of studies have held that proprioception is important for perceiving the moment of inertia of the rod, but this has not been demonstrated experimentally. In the present paper, we focused on joint acceleration and torque as physical values that approximate proprioception by introducing dynamics-based mechanics. In the experiments, the acceleration of the swinging of the rod was controlled. Since the acceleration and the torque both varied with time, their peak values were adopted as representative values. No correlation was observed between the angular acceleration and the perceived rod length. However, a strong correlation was found between joint torque and the perceived length. This indicates that humans perceive rod length through joint torque, which approximates proprioception. © 2011 Springer-Verlag.