Walking control on uneven terrain with short cycle pattern generation

This paper addresses sensor feedback control methods that are used with short cycle walking pattern generation and realize walking on uneven terrains which are not modelled in advance. We have proposed an online walking control system that generates a dynamically stable motion pattern in short cycles, such as 20 [ms]. The system is capable of reflecting the actual motion status which is modified from the previously generated pattern by sensor feedback to the pattern generation of the next period so that the long-term stability of the walking is maintained using the dynamic model. Two new functions are introduced into the system in this paper. One is posture control and absolute motion estimation by using attitude measurement sensor mounted on the waist link. The other is center of pressure control for each foot which realizes the stable contact of the foot to the terrain. The proposed system is implemented on HRP-2 and verified. Finally an experiment of walking on the terrain on which plates with up to 14[mm] thickness are scattered is shown. The robot was able to walk through the terrain even when it stepped on the edge of a plate.