Cooperative-Dual-Task-Space-based whole-body motion balancing for humanoid robots

This paper studies the use of Cooperative Dual-Task Space (CDTS) as an efficient approach for the whole-body motion balancing problem for humanoid robots. The CDTS variables have been used efficiently to describe and control coordinated motions of dual-arms. Similarly, the concept of CDTS variables can be extended to describe the constraints and the control of humanoid legs. When the leg motion is described and controlled by CDTS variables, the variables regarding the feet constraints and the control variables in the leg motion regarding the waist movement can be nicely decoupled. One of the CDTS variables can be used to describe the constraints on the feet, and the constraints can be expressed independently of the support-foot changes. The proposed CDTS-based method provides an efficient way to stabilize the merged whole-body motion by modifying the horizontal waist position by a coordinated motion of both legs while satisfying the changing constraints on both feet in the lower-body motion. Thus, the proposed CDTS-based method provides the possibility of generating a large library of whole-body motions for a humanoid robot by combining an upper-body motion captured from humans and lower-body motions generated by an existing biped walking pattern planner. The performance of the proposed CDTS-based approach was validated through extensive simulations including cases that showed a HOAP-2 robot walking on a flat terrain and climbing up the stairs with a rapid upper-body movement.