Reactive whole-body control for humanoid balancing on non-rigid unilateral contacts

Humanoid robots are expected to act in human environments, where some of the contacts can be non-rigid. A fairly large amount of work has been devoted to the whole-body control of humanoids under rigid contacts, but few of them take into account non-rigid contacts. Indeed, the handling of unknown compliant contacts to achieve goal directed actions and whole-body balance remains a challenge. This paper addresses this problem by proposing a control mechanism that solves whole-body tasks under non-rigid contacts. It is a reactive control approach that automatically regulates contact forces and whole-body motions based on the motion of contact points without the awareness of the rigidity properties of the contact material. Verification of this approach is conducted through experiments on the iCub humanoid robot in simulation.