Humanoid Control Under Interchangeable Fixed and Sliding Unilateral\n Contacts

Abstract

In this letter, we propose a whole-body control strategy for humanoid robots\nin multi-contact settings that enables switching between fixed and sliding\ncontacts under active balance. We compute, in real-time, a safe center-of-mass\nposition and wrench distribution of the contact points based on the Chebyshev\ncenter. Our solution is formulated as a quadratic programming problem without a\npriori computation of balance regions. We assess our approach with experiments\nhighlighting switches between fixed and sliding contact modes in multi-contact\nconfigurations. A humanoid robot demonstrates such contact interchanges from\nfully-fixed to multi-sliding and also shuffling of the foot. The scenarios\nillustrate the performance of our control scheme in achieving the desired\nforces, CoM position attractor, and planned trajectories while actively\nmaintaining balance.\n