Steering of a 3D bipedal robot with an underactuated ankle

This paper focuses on steering a 3D robot while walking on a flat surface. A hybrid feedback controller designed in for stable walking along a straight line is modified so that it is capable of adjusting the net yaw rotation of the robot over a step in order to steer the robot along paths with mild curvature. The controller is designed on the basis of a single pre-defined trajectory for periodic walking along a straight line. In order to illustrate the role of internal/external (i.e., medial/lateral) rotation at the hip in achieving curved walking motions, the performance of two robots, one with internal/external rotation and one without, is compared.