This report is the result of a joint reflection carried out by researchers from automatic control and neuroscience fields, both trying to answer a same question: what are the functional basis of bipedal locomotion and how to control them? The originality of this work is to put in parallel two synthesis of how the problem of biped displacements is solved in robotics in one hand and in nature in the other hand. We believe that the key e lements explaining the performances in adaptability and reactivity of human could help roboticians to find some issues for the design of automatic control schemes. Similarly, the theoretical framework of biped robotics could help neuroscientists to formulate concepts and models.