2 research outputs found
Humanoid Control Under Interchangeable Fixed and Sliding Unilateral Contacts
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
Balance of Humanoid robot in Multi-contact and Sliding Scenarios
This study deals with the balance of humanoid or multi-legged robots in a
multi-contact setting where a chosen subset of contacts is undergoing desired
sliding-task motions. One method to keep balance is to hold the center-of-mass
(CoM) within an admissible convex area. This area should be calculated based on
the contact positions and forces. We introduce a methodology to compute this
CoM support area (CSA) for multiple fixed and sliding contacts. To select the
most appropriate CoM position inside CSA, we account for (i) constraints of
multiple fixed and sliding contacts, (ii) desired wrench distribution for
contacts, and (iii) desired position of CoM (eventually dictated by other
tasks). These are formulated as a quadratic programming optimization problem.
We illustrate our approach with pushing against a wall and wiping and conducted
experiments using the HRP-4 humanoid robot