Realization of dynamic biped walking stabilized by trunk motion on a sagittally uneven surface

The authors introduce a control method for dynamic biped walking stabilized by trunk motion on a sagitally uneven surface, that is for a biped walking robot which has a trunk to stabilize its walking, and its effectiveness as supported by walking experiments using a biped walking robot. This control method is based on the introduction of a new concept called a virtual surface, to consider the ZMP (zero moment point) on an uneven surface, and the main algorithm for computing the trunk motion which compensates for lower-limbs motion and time trajectory of the arbitrarily planned ZMP on the virtual surfaces. Using this control method in a number of experiments, the biped walking robot WL-12RIII (Waseda Leg-12 Refined III) which has a trunk, realized dynamic biped walking on stairs with a step height of 0.1 m and a trapezoidal terrain with an inclination of ±10 deg. The walking period was 2.6 sec/step on the stairs, and 1.6 sec/step on the trapezoidal terrain. So that, the effectiveness of this control method was experimentally supported