LAUSR

Pelvic rotation, which is observed in human gait, is used to increase a robot’s step length in the humanoid robot walking. Existing methods empirically or experimentally generate the pelvic-rotation angle offline using predetermined pelvis and foot trajectories. However, these methods are difficult to combine with the method used to generate the center of mass (CoM) trajectory in real time using techniques such as preview control or model predictive model control. Our previous study proposed a method to optimize the pelvic rotation trajectory at every control time using redundancy in the lower body of the robot. However, because the proposed method did not reflect the future state of the robot, the waist yaw joint rotated abruptly. In this study, we propose a method that generates a pelvic-rotation trajectory that can be used with a real-time CoM generation method while reflecting the future state of the robot. A lower body composed of the waist yaw joint and leg joint was used in quadratic programming-based inverse kinematics to obtain the leg-joint input value for walking using pelvic rotation. In addition, an arm swing motion was generated to compensate for the yaw angular momentum during walking. The proposed method was analyzed through simulations and experimentally verified.