3D-SLIP steering for high-speed humanoid turns

This paper presents new methods to control humanoid turns while running, through the use of a 3D-SLIP template model with steering control. The work builds on a previous controller for straight-ahead running and describes the new methods that enable online humanoid steering for different speeds and turn rates. As opposed to previous research which has studied 3D-SLIP steering with a monopod model, motion optimization for the SLIP here enforces leg separation. This leg separation gives rise to body sway in forward running and allows the template to capture the unique roles that the inside and outside legs each play during a high-speed turn. The trajectory optimization approach for this template is given, and the resultant CoM trajectories are characterized. Modifications to a previous controller for straight-ahead running are shown to enable running turns in a simulated humanoid model. The methods allow the humanoid to change its turn rate and direction from step to step and enable execution of a high-speed turn with a radius that is one fourth that of a standard 400m track. A video attachment to this paper shows the humanoid turning while running at up to 4.0 m/s, and highlights its ability to maintain balance in spite of push disturbances.