Spine Balancing Strategy Using Muscle ZMP on Musculoskeletal Humanoid Kenshiro

In this paper, we propose a new balancing strategy for musculoskeletal humanoids by using their redundant musculoskeletal structures. This strategy is based on the idea of muscle Zero Moment Point(ZMP) and involves the use of a balance stabilizer utilizing the spine. The muscle ZMP is a stabilization indicator instead of a normal ZMP that is computed from 6DOF force sensors installed on robots’ foot. In order to compute the muscle ZMP, we use the joint torques obtained from muscle tensions. The spine stabilizer compensates for the COG displacement of the whole-body by utilizing the spine movements. Further, we confirm the effectiveness of the proposed strategy by demonstrating several balancing motions of Kenshiro, a musculoskeletal humanoid.