Practical experiment of balancing for a hopping humanoid biped against various disturbances

This paper discusses balancing for a hopping humanoid biped against various disturbances. Contrary to other studies, the present work focuses on the practical experiment with a real humanoid biped, HUBO2. Also, hopping is focused on among various types of locomotion since hopping is simple movement but more dynamic rather than walking. Two control strategies are proposed according to the magnitude of the disturbances. The one is the posture balance control for small disturbance, which uses the ankle torque of the stance leg. The other is to use the posture balancing control and the landing position control together for large disturbance. The landing position controller changes the landing position of the swing foot to maintain stability. The closed form solution of the landing position controller is addressed with the simplified model. As this simplification, both controllers are used together since the landing position controller cannot maintain a perfect balance alone. To this end, practical experiments with HUBO2 are conducted. In the experiments, HUBO2 maintains a balance against not only small disturbance but also large disturbance such as pushing through the proposed control strategies.