Our goal is to achieve dynamic locomotion over challenging unstructured terrain. This requires reasoning about the robot’s dynamics, actuation limits and interaction with the environment. To do so, we exploit optimization techniques in locomotion control to formulate a Whole-Body Control (WBC).
WBC is a motion tracking controller that is capable of achieving multiple locomotion tasks while respecting the robot’s behavior. WBC casts locomotion control as an optimization problem, in which, by incorporating the full dynamics of the legged robot, all of its Degrees of Freedom (DoFs) are exploited in order to spread the desired motion tasks to all the joints. This allows us to reason about multiple tasks and solve them in an optimization fashion while respecting the full system dynamics and the actuation and interaction constraints.
Our WBC was tested on HyQ over a wide range of challenging terrain (slopes, gaps, stairs, etc.), using different gaits (crawl and trot). Our WBC is robust against inaccurate friction coefficient estimation and unstable footholds.
S. Fahmi, C. Mastalli, M. Focchi, and C. Semini, “Passive whole-body control for quadruped robots: Experimental validation over challenging terrain,” IEEE Robot. Automat. Lett. (RA-L), vol. 4, no. 3, pp. 2553–2560, Jul. 2019, DOI:10.1109/LRA.2019.2908502. Full paper