Dynamical effect of elastically supported wobbling mass on biped running

Our research team has been developing biped robots based on the nature of passive dynamics. We aim to both investigate the effect of wobbling mass and apply the findings to biped robots to achieve high-performance running. We used an elastically supported wobbling mass in the trunk of biped robots because humans utilize their elastic organs in the upper body and arms to improve running performance. To investigate the characteristics and mechanisms of passive dynamics of the wobbling mass focusing on the vertical ground reaction force, we used a simple model equipped with an elastically supported wobbling mass and analytically derived periodic solutions. The normal mode analysis of the obtained solutions explained the mechanism under which periodic solutions are achieved, and analytic solutions showed similar vertical locomotion to human running and suggested the mechanism under which high-performance locomotion is achieved from the viewpoint of the ground reaction force and energy efficiency. Based on these solutions, we conducted experiments using a prototype and a biped robot equipped with wobbling mass. Experimental results showed similar characteristics in the vertical movement to the simple model and human running. These findings will help improve our understanding of biped running and contribute to producing human-like running of biped robots.