Line Walking and Balancing for Legged Robots with Point Feet
This addresses a specific challenge in robotics for applications requiring traversal of highly-constrained environments, but it is incremental as it builds on existing balance control methods.
The paper tackles the problem of legged robots walking on extremely narrow surfaces, such as a 6 cm wide bridge, by developing a controller that enables a 90kg quadruped robot to balance on two point feet while moving along a line in simulation.
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.