Realization of dynamic biped walking varying joint stiffness using antagonistic driven joints

Abstract

In this paper, the authors introduce a life-size biped walking robot having antagonistic driven joints using a nonlinear spring mechanism and a 4namic biped walking control method using these joints.In the current research concerning a biped walking robot, there is no developed example of a life-size biped walking robot with antagonistically driven joints by which the human musculo-skeletal system is imitated in lower limbs. Humans are considered to walk eflciently using the inertial energy and the potential energy of the lower limbs effectively, walk smoothly with less impact force when a foot lands and cope flexibly with the outside environment. The Human joint is driven by two or more muscle groups. Humans can vary the joint stiffness, using nonlinear spring characteristics possessed by the muscles themselves. These functions are indispensable for a humanoid. However, the biped walking robots developed previously have been unable to walk in this way. Therefore, the authors developed a biped walking robot having antagonistic driven joints, and proposed a walking control method for dynamic biped walking that uses antagonistic driven joints to vary joint stiffness. The authors performed walking experiments using the biped walking robot and the control method. As a result, dynamic biped walking varying the joint stirness using antagonistic driven joints was realized.

BLUE: A bipedal robot with variable stiffness and damping

“…Some have antagonistic non-linear springs [9] or pneumatic muscles [10]; however, these have tended to be slow and not capable of exhibiting dynamic effects. A more agile, antagonistic pneumatic robot is described in [11], but compliance control of its joints is still fairly primitive.…”

Biomimetic Design of Low Stiffness Actuator Systems for Prosthetic Limbs

“…In this application, size, weight and energy supplies are severely limited. Compliant actuators provide increased energy efficiency [19,25,30,32] as well as reduced weight and cost [34]. Commercial prosthetic designs generally have not incorporated compliance, due to control challenges as well as space limitations.…”

Kick it with elasticity: Safety and performance in human–robot soccer

“…In WL-14 [66,67], a sophisticated nonlinear spring mechanism was used for stiffness adjustment. More recently in Lucy [63], a biped that is able to walk in the sagittal plane, approaches were made to utilize adjustable passive compliance for high energy efficiency during walking.…”

“…The former has received larger attention especially for biped walking [66,67,63]. Our focus lies on the latter as it allows to considerably increase the link speed [56,54,51,24,65] above motor level.…”