The paper reports on two results issued from a multidisciplinary research action tending to explore the motor synergies of anthropomorphic walking. By combining biomechanics, neurophysiology and robotics perspectives, it is intended to better understand the human locomotion with the ambition to better design bipedal robot architectures. The motivation of the research starts from the simple observation that humans may stumble when following a simple reflex-based locomotion on uneven terrains. The rationale combines two well established results in robotics and neuroscience respectively: • Passive robot walkers, which are very efficient in terms of energy consumption, can be modelled by a simple rotating rimless wheel; • Humans and animals stabilize their head when moving. The seminal hypothesis is then to consider a wheel equipped with a top-down control as a plausible model of bipedal walking. The two results presented in the paper comfort the hypothesis: • From a motion capture data basis of twelve human walkers we first identify the center of mass (CoM) as a geometric center from which the motions of the feet are organized. • After introducing a ground texture model that allows to quantify the stability performance of walker control schemes, we show how compass-like passive walkers are better controlled when equipped with a stabilized 2-degree-of-freedom moving mass on top of them. CoM and head then play complementary roles that define what we call the Yoyo-Man. Beyond the two results presented in the paper, the Yoyo-Man model opens new perspectives to explore the computational foundations of anthropomorphic walking.
International Journal of Robotics Research