Turning motion by control constraint mechanism of passive dynamic walking

This paper proposes a foot shape design to enhance stability of passive dynamic walk, by constraining fall down phenomenon in both sagittal and lateral planes. From geometrical analysis, we found that stability under a wide range of slope inclinations will be achieved by limiting swing legs spatially in a certain angle. We also found that the limiting leg´s angles, we call constraint mechanisms, are achieved by a certain type of a 3D sole shape, which provides stability in a compact size. We show the turning motion for a passive dynamic biped walker with constraint mechanisms.