Passive dynamics of animal locomotion
by
Te-yuan Chyou
University of Otago
Coauthors: Mike Paulin and Gerrard Liddell

For decades biologists believed that animals walk because the brain calculates the motion trajectories for the limbs. More recently a new hypothesis about animal locomotion suggests the contrary. Animal are built to walk “naturally” in the first place, such that they can walk without relying on controls. Instead, the walking gait is generated simply by the interaction of gravity and inertia, in a stable, naturally emerged limit-cycle, known as passive dynamic walking. We had demonstrated that passive dynamic walking is also feasible in the presence of a torso and upper-limbs. With an upper-body, passive dynamic walking also takes place on the level ground but for energetic reasons it is unstable. In this talk we look at how to stabilize the unstable passive walking trajectory in a physically feasible and biologically relevant way, as well as our recent passive dynamic walking models. These results suggest that the role of controls is to provide stability, rather than driving the limb along a pre-calculated trajectory.

Date received: January 13, 2010