Humanoid Control Under Interchangeable Fixed and Sliding Unilateral Contacts
This work addresses the challenge of dynamic contact management for humanoid robots, which is incremental but important for improving mobility in complex environments.
The authors tackled the problem of controlling humanoid robots in multi-contact settings by enabling real-time switching between fixed and sliding contacts under active balance, achieving desired forces, center-of-mass position, and planned trajectories in experiments.
In this letter, we propose a whole-body control strategy for humanoid robots in multi-contact settings that enables switching between fixed and sliding contacts under active balance. We compute, in real-time, a safe center-of-mass position and wrench distribution of the contact points based on the Chebyshev center. Our solution is formulated as a quadratic programming problem without a priori computation of balance regions. We assess our approach with experiments highlighting switches between fixed and sliding contact modes in multi-contact configurations. A humanoid robot demonstrates such contact interchanges from fully-fixed to multi-sliding and also shuffling of the foot. The scenarios illustrate the performance of our control scheme in achieving the desired forces, CoM position attractor, and planned trajectories while actively maintaining balance.