Dynamics morphing between standing and repetitive hopping of biped robots

This paper presents a repetitive hopping control of biped robots, which has the following properties: 1) It can initiate or cease hopping at any time, 2) The peak altitude can be freely altered during hopping, and 3) The impact at touchdown is suppressed. Hopping motions accompany frequent changes of contact conditions with the environment and lead the discontinuity of dynamics they are governed, therefore, it is difficult to achieve the motion in a way without relying any passive mechanisms such as springs and dampers. Three controllers, that is, (I) a regulator to stabilize, (II) a controller to converge a desired velocity when lifting off the ground and (III) a controller to absorb the landing impact are unified by the global scheme to transit each other depending on a commanded value and the state of the robot.