The ability of legged systems to traverse highly-constrained environments depends by and large on the performance of their motion and balance controllers. This paper presents a controller that excels in a scenario that most state-of-the-art balance controllers have not yet addressed: line walking, or walking on nearly null support regions. Our approach uses a low-dimensional virtual model (2-DoF) to generate balancing actions through a previously derived four-term balance controller and transforms them to the robot through a derived kinematic mapping. The capabilities of this controller are tested in simulation, where we show the 90kg quadruped robot HyQ crossing a bridge of only 6 cm width (compared to its 4 cm diameter spherical foot), by balancing on two feet at any time while moving along a line. Lastly, we present our preliminary experimental results showing HyQ balancing on two legs while being disturbed.
@article{arxiv.2007.01087,
title = {Line Walking and Balancing for Legged Robots with Point Feet},
author = {Carlos Gonzalez and Victor Barasuol and Marco Frigerio and Roy Featherstone and Darwin G. Caldwell and Claudio Semini},
journal= {arXiv preprint arXiv:2007.01087},
year = {2020}
}