Momentum compensation for fast dynamic walking of humanoids based on pelvic rotation of contact sport athletes

This paper presents a method of momentum compensation around the perpendicular axis during fast dynamic waking of humanoid robots. In order to perform a task using the arms during a walk, it is desirable that the upper body part, i.e., the arms and the trunk, should not be used for the momentum compensation and should be dedicated to the task. In this paper, a particular walk called trunk-twistless walk is investigated which is experientially acquired by contact sport athletes. An antiphase rotation of the pelvis against the swing leg is observed compared to a normal walk. This Characteristic of the pelvic rotation is implemented to a humanoid. A method of determining the rotation of the humanoid's waist is proposed coupling with the pitch angle of the swing leg. The proposed walk achieves the whole walking motion including the momentum compensation only by the lower body. It is confirmed that the stance foot torque around the perpendicular axis is reduced compared to a standard humanoid walk without twisting the trunk OF swinging the arms. The improvements on the straightness of the walking trajectory and the stability of the upper body during a fast dynamic walk are also confirmed.