Locomotion pattern generation and mechanisms of a new biped walking machine

This paper describes the mechanism of a 16 d.f. biped walking machine, Waseda biped humanoid robot-2 lower limb (WABIAN-2LL), which has two 7 d.f. legs and a 2 d.f. waist actuated by DC servo motors with reduction gears. WABIAN-2LL is designed with large movable angle ranges like those of a human. Its height and weight are 1200 mm and 40 kg, respectively. It is able to walk with its knees stretched using the redundancy of the legs and to move around an object using a hip-bending motion without touching the object. A knee-stretched locomotion pattern generation is also proposed in this paper, which separately creates joint angles in a supporting and a swinging phase. During knee-stretched walking, the joint rate of the knee will approach infinitely when the knee is stretched. This singularity problem is solved by using the motion of the waist, not the posture of the trunk. The effectiveness of the mechanisms and pattern generations of WABIAN-2LL is verified through dynamic walking experiments.