Abstract
Many devices for assisting the elderly to stand up have been developed, but they move automatically without regard for the user's standing-up motion. In order to solve this problem, the user's motion must be measured simply and easily. However, there is no such measuring method, and we wish to estimate the standing-up motion based on information which is simply and easily obtainable. Therefore, we decided to use the plantar information, for the following reasons: 1) the COP (center of pressure) and VRF (vertical reaction force) of the plantar information are said to be influenced by the position of the body during the standing-up process; 2) the plantar information is obtained easily. In this study, we investigated the relationship between the standing-up motion and the COP/VRF to estimate the motion based on the plantar information. In order to reproduce a wide variety of standingup motions from a chair, 36different patterns of standing-up motion were included. We used our analysis device to calculate the COP and VRF, and a motion capture system to measure the standing-up motion, especially the positions of the head and hips. Prior to analyzing the relationship, we divided the standing-up process into two phases. The results for phase1revealed that the forward movement distance of the COP is relevant to the forward movement distance of the head, and that the integrated VRF is relevant to the upward movement distance of the head. The results for phase2revealed that the forward movement distance of the COP is relevant to the forward movement distance of the hips, and that the integrated VRF is relevant to the upward movement distance of the hips. These results suggest that it is possible to estimate to a certain extent the positions of the head and hips based on the plantar information.
