Analysis of motions of a small biped entertainment robot

SDR-4X II is the latest prototype model which is a small biped entertainment robot. Formerly we reported the outline of SDR-4X II, and mechanical system, control system and sensor system. In this paper we report about analysis of various important motions of this small biped entertainment robot which is used in home environment. Humanoid type robot basically has very small foot area and the standing stability is essentially very low. Therefore we do not try that the robot never falls down, but we have to think that the robot sometimes surely falls down by some reasons. And when it falls down, the robot should not be damaged and stand up by himself. In this paper, we describe the method of falling-over and standing up motions and analyze the measured joint angle data and confirm the successfulness of our measures. The major point of the shock absorbing method is the motion of effective joints and the real-time servo loop gain modification control. Lastly as one of the important motions, the wide-angle turn motion analysis is explained.