Agile and Dynamic Standing-Up Control for Humanoids Using 3D Divergent Component of Motion in Multi-Contact Scenario.

Standing-up is a task that humanoids need to be able to perform in order to be employed in real-world scenarios. This letter proposes a new robust strategy for a humanoid to stand up in challenging scenarios where no completely preplanned motion can accomplish the same task. This strategy exploits the concept of three-dimensional divergent component of motion and passivity-based whole-body control. The latter firstly maximizes the push forces applied to the robot's center of mass to make agile whole-body recovery motion. Then, during the rising phase, it reduces these forces to zero and stabilizes the robot in an upward position. Optimization of centroidal angular momentum is fully integrated into the proposed whole-body standing-up control to create the trajectories of the hip and the upper body joints online. The effectiveness of the proposed method is validated in simulations and experiments on the humanoid TORO.