MPC-based Locomotion Control of Bipedal Robots with Line-Feet Contact using Centroidal Dynamics

Recently we have seen a lot of progress done in dynamic locomotion with quadrupedal robots using the Single-Rigid Body Model, which contains simplified dynamics that considers the robot a single "potato". This approach performs poorly when the robot contains heavy links, because those links take a considerable momentum to move and because they also change the overall inertia of the robot. In this paper, we generalize the SRBM using the Centroidal Dynamics model plus an orientation variable, whose dynamics contain the linearized effects of other links' momentum and variable inertia. We are designing this Enhanced Centroidal Dynamics using the Full-Body Dynamics, so the trajectories we obtain are instantaneously dynamically feasible. We show our approach in a full-body dynamic simulation of the MIT Humanoid, a biped with line-feet contact, and we show a simplification in the modeling of the wrenches that can be applied with line-feet.