Development of a biped walking robot having antagonistic driven joints using nonlinear spring mechanism

The authors are engaged in studies of biped walking robots from the following two viewpoints. One is a viewpoint as a human science. The other is a viewpoint towards the development of humanoid robots. In the current research concerning a biped walking robot, there is no developed example of a life-size biped walking robot with the antagonistically driven joints by which the human musculo-skeletal system is imitated in lower limbs. Humans are considered to exhibit walking behavior, both efficient and capable of flexibly coping with contact with the outside environment. However, developed biped walking robots can not realize the human walking. The human joint is driven by two or more antagonistic muscle groups. Humans can vary the joint stiffness, using nonlinear spring characteristics possessed by the muscle themselves. The function is an indispensable function for a humanoid. Therefore, the authors designed and built an anthropomorphic biped walking robot having antagonistic driven joints. In this paper, the authors introduce the design method of the robot. The authors performed walking experiments with the robot. As a result, quasi-dynamic biped walking using antagonist driven joint was realized. The walking speed was 7.68 s/step with a 0.1 m step length.