Unified Balance Control for Biped Robots Including Modification of Footsteps with Angular Momentum and Falling Detection Based on Capturability In this paper, we propose walking balance control based on Caputurability. The proposed method consists of five strategies: (i) moving Zero Moment Point (ZMP) in the support polygon (ii) landing position modification (iii) landing timing modification (iv) angular momentum control (v) falling detection and fall control. Walking pattern generation calculates the ZMP so that the Capture Point (CP) reaches the position of the supporting foot at the end of the double support phase. Owing to the asymmetry of the reachable landing region, landing timing modification is different in the sagittal and lateral planes, and the step time is extended in the lateral plane depending on the direction of disturbances. The torque around the center of gravity to avoid falling is realized through wholebody inverse kinematics with constraints on the angular momentum. In addition, we propose falling detection considering the reachable landing region. We verified the effectiveness of the proposed method through experiments in which the biped robot was disturbed by pushing during tetherfree walking. The robot could prevent breakdown by detecting possible falling and performed knee bending motions to suppress damage.

MultiContact Stabilization of a Humanoid Robot for Realizing Dynamic Contact Transitions on Noncoplanar Surfaces This paper focuses on a stabilization control for multicontact motion which enables a humanoid robot to locomote by realizing dynamic contact transitions on nonflat environment. In the stabilization process of the multicontact motion, the desired ZeroMoment Point (ZMP) is modified by the position of the Divergent Component of Motion (DCM) error with respect to the 3D Center of Mass (CoM) motion generated from the force distribution ratio. The contact wrench of each endeffector is determined by quadratic optimization considering the centroidal dynamics and contact friction constraints so as to satisfy the modified ZMP. Each endeffector is controlled by optimized force reference through a projection of null space by force distribution ratio. We propose a multicontact stabilization framework which can be designed not only to generate 3D CoM motion but also the CoM position estimation and the optimal force distribution around the reference ZMP in a unified manner from a balance controller, by using the force distribution ratio. The effectiveness of proposed method is validated by a quadruped locomotion leaning against a vertical wall using the joint position controlled humanoid HRP5P in a dynamic simulator.