Title: An Optimization Based Control Framework for Balancing and Walking: Implementation on the iCub Robot,
Abstract: A whole-body torque control framework adapted for balancing and walking tasks
is presented in this paper. In the proposed approach, centroidal momentum terms
are excluded in favor of a hierarchy of high-priority position and orientation
tasks and a low-priority postural task. More specifically, the controller
stabilizes the position of the center of mass, the orientation of the pelvis
frame, as well as the position and orientation of the feet frames. The
low-priority postural task provides reference positions for each joint of the
robot. Joint torques and contact forces to stabilize tasks are obtained through
quadratic programming optimization. Besides the exclusion of centroidal
momentum terms, part of the novelty of the approach lies in the definition of
control laws in SE(3) which do not require the use of Euler parameterization.
Validation of the framework was achieved in a scenario where the robot kept
balance while walking in place. Experiments have been conducted with the iCub
robot, in simulation and in real-world experiments.