Uncontrolled manifold analysis of standing-up motion for development of an assistance system

Standing-up motion is essential to performance of the activities of daily life (ADL). In this research, we analyse human standing-up motion in terms of how joint angles coordinate to contribute to the motion. Uncontrolled manifold (UCM) analysis is applied, and degrees of joint coordination are calculated for the entire course of the motion. Those values are investigated for the four phases of the motion to understand which positions of the body are under explicit control. Results indicate that individuals control their hip and shoulder positions in the horizontal direction until extending their upper body and also after they finish lifting up their body. On the other hand, it is shown that vertical direction of the hip and shoulder are controlled until the time they bend their back and lift up their hip. Based on time series of calculated joint coordination over the entire standing-up motion, we suggest a new control method for our previously developed force assisting system. The controller allows deviated range of movement during the time points in which healthy participants show less explicit control of their body positions, and requires more consistent trajectories during times when participants show more explicit control.