Stability and controllability in a rising motion: a global dynamics approach

A novel concept for controlling a humanoid robot, global dynamics, is investigated by motion capture experiments. This concept generalises human/humanoid body motion as successive transitions of "envelopes", where body dynamics is exploited and high level control input is adopted only at the "nodes", where the body is unstable and control input is necessary. Dynamical rising is chosen for our experiment and full body motion is measured. By evaluating the coordination between joint angles, we have seen variation of motion and corresponding envelope volume (stable region within the phase space). Also, by analysis in the phase space (including variables both of positions and their time derivatives), we have seen variations not only according to boundary conditions for the motion (i.e., adopting physical restriction) but also according to experience. Our results suggest that the body dynamics have rich complexity in phase space. Within an envelope, small nodes may exist to give variation and controllability without damaging stability.