Task-level objectives and low-order models of bipedal locomotion

Animals must seamlessly integrate mechanics and sensorimotor control to achieve agile and stable locomotion in complex environments. Striding bipedal animals (humans and ground birds) use walking and running gaits that look qualitatively similar in whole-body dynamics, gait duty factor, and ground reaction forces. This observation suggests that many aspects of locomotor dynamics arise from the fundamental physics of locomotion on legs.Our work uses math models based on these fundamental physics coupled with trajectory optimization techniques to pinpoint the cause of these gait observations as observed in nature. This work suggests that the inertia of a swing leg is a parsimonious explanation for the utility of low duty factors in bipedal locomotion at high speed.