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.

WholeBody Control of Humanoid Robot in 3D MultiContact under Contact Wrench Constraints Including Joint Load Reduction with SelfCollision and Internal Wrench Distribution In this paper, we propose an approach for online wholebody control of positioncontrolled humanoid robot with 3D multicontact to cope with contact wrench constraints and joint overload. In our method, robots are controlled under contact wrench constraints with three features: 1) internal wrench control to reduce joint load and prolong the time in which the highload postures can be maintained 2) feasible utilization of selfcollision to reduce joint load by turning off joint servo gains 3) handling degenerated degree of freedom by solving a quadratic optimization problem integrating wrench distribution and inverse kinematics in which internal wrench is controlled only in controllable directions.With our methods, HRP2JSKNTS could pick up an object under a desk with squatting with the back of the upper leg on the back of the lower leg without sliding at the right arm. We also evaluated the effectiveness of our control to reduce joint load with another experiment.