From stable walking to steering of a 3D bipedal robot with passive point feet

Ching-Long Shih (1) , Jessy Grizzle (2) , Christine Chevallereau (3)

1 EE-506 - Servo Control Lab
2 EECS - Department of Electrical Engineering and Computer Science
3 IRCCyN - Institut de Recherche en Communications et en Cybernétique de Nantes

This paper exploits a natural symmetry present in a 3D robot in order to achieve asymptotically stable steering. The robot under study is composed of 5-links and unactuated point feet; it has 9 DoF (degree-of-freedom) in the single support phase and six actuators. The control design begins with a hybrid feedback controller that stabilizes a straight-line walking gait for the 3D bipedal robot. The closed-loop system (i.e., robot plus controller) is shown to be equivariant under yaw rotations, and this property is used to construct a modification of the controller that has a local, but uniform, input-to-state stability (ISS) property, where the input is the desired turning direction. The resulting controller 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. An interesting feature of this work is that one is able to control the robot's motion along a curved path using only a single predefined periodic motion.

Mots clés: 3D underactuated bipedal robot; hybrid zero dynamics; orbital stability; Poincaré map; steering; stride-to-stride control

Domaines: Robotique [cs.RO]

Ching-Long Shih, Jessy Grizzle, Christine Chevallereau. From stable walking to steering of a 3D bipedal robot with passive point feet. Robotica, 2012, 30 (7), pp.1119-1130. ⟨10.1017/S026357471100138X⟩. ⟨hal-00794633⟩