Modeling and analysis of walking chair “Ikkyu-san”

This study aims to verify effectiveness of Ikkyu-san, which is a walking aid developed by Nihon Robotics Co., Ltd., with respect to the function of a walking aid. The issue comes from the fact that the problem of aging society is serious in current Japan, and many senior people suffer from physical depression problems to a varying degree. Hence, many types of walking aids including Ikkyu-san are developed to support and improve physical functions including walking. Traditional evaluation of effectiveness of walking aids is based on quasi-static effect how to provide support for the body. However, in general, a walking aid is used for walking. Hence, we propose a dynamical evaluation method based on ZMP. The effectiveness of Ikkyu-san can be verified from the proposed viewpoint. To apply the dynamical evaluation requires both the center of gravity (CoG) and the base of support (BoS) of the entire system including the aid and its user. Therefore, a mathematical model of Ikkyu-san is derived by Projection Method. CoG of a user can be estimated by Chandler's equation using position of each body part measured by a Motion Capture System (MCS). Through some experiments, it is found that Ikkyu-san provides good stability for supporting body while walking.