Plantar Haptic Display to Estimate the Position of the Projected Center of Gravity of a Humanoid

Abstract

Humans can perform stable motion with a sense of stability that involves identifying their center of gravity point with plantar sensory system. By contrast, the stability of a humanoid robot is inferior to that of a human. If the sense of stability of a humanoid robot is presented to a human who operates the robot in real time, the operator can control the robot more stably. However, studies wherein humans recognize the projected center of gravity point with a plantar haptic display are lacking. In this study, we investigated the possibility of estimating the projected center of gravity point of a small humanoid robot from only the foot force information. We propose a plantar haptic display to reproduce the foot reaction force on four points of a single sole as large as the force during human running. We conducted an experiment to verify the estimated center of gravity point using the foot reaction forces of a small robot with and without scaling by a weight ratio between an operator and the robot. The results indicated that it is difficult to estimate the projected center of gravity point without scaling; however, it is possible to estimate the movement of the projected center of gravity point with a maximum error of [Formula: see text][Formula: see text]mm with scaling.