Hip actuations can be used to control bifurcations and chaos in a passive dynamic walking model.

We explored how hip joint actuation can be used to control locomotive bifurcations and chaos in a passive dynamic walking model that negotiated a slightly sloped surface (gamma<0.019 rad). With no hip actuation, our passive dynamic walking model was capable of producing a chaotic locomotive pattern when the ramp angle was 0.01839 rad<gamma<0.0190 rad. Systematic alterations in hip actuation resulted in rapid transition to any locomotive pattern available in the chaotic attractor and induced stability at ramp angles that were previously considered unstable. Our results detail how chaos can be used as a control scheme for locomotion.