Online 3D CoM Trajectory Generation for Multi-Contact Locomotion Synchronizing Contact

This paper proposes a fast computation method for 3D multi-contact locomotion. The contributions of this paper are (a) the derivation of the prospect centroidal dynamics by introducing a force distribution ratio, where the centroidal dynamics in multi-contact can be represented with a formulation similar to the inverted pendulum's one, and (b) the development of a fast computation method for generating a 3D center of mass (CoM) trajectory. The proposed method allows to generate a trajectory sequentially and to change the locomotion parameters at any time even under variable CoM height. Then, the contact timing of each end-effector can be adjusted to synchronize with the actual contact with the environment by shortening or extending the desired duration of the support phase. This can be used to improve the robustness of the locomotion. In this paper, we deal with a multi-contact locomotion which can be fully received a vertical reaction force from the environment and the validity of the proposed method is confirmed by several numerical results: the CoM motion while changing the contact timing and a multi-contact locomotion considering a transition between biped and quadruped walking in a dynamics simulator.