Dual-Hierarchical Control Mechanism of Interpersonal Embodied Interactions in Cooperative Walking

Interpersonal embodied interactions play a significant role as emergent functions in human development and rehabilitation. However, a framework for applying embodied interactions to “human interface systems” to support such emergent functions has not yet been suggested because the details of the motorcontrol mechanism have not yet been clarified. In this study, the interpersonal cooperative walking motions of two humans, as an example of such a mechanism, have been replicated and their motor-control mechanisms analyzed. The results indicate that the hierarchical dynamics were derived from an interpersonal footstep entrainment process and an intrapersonal interaction of arm and footstep motions. We suggest that embodied interactions in cooperative walking are achieved by a dual-hierarchical control structure related to emergence of the phase-control function of interpersonal cooperative walking, based on an automatic control mechanism for interpersonal entrainment of footstep motions and an intrapersonal voluntary-motion-control mechanism.