Dynamic Gait Generation of Telescopic-legged Rimless Wheel Based on Asymmetric Impact Posture

Dynamic Gait Generation of Telescopic-legged Rimless Wheel Based on Asymmetric Impact Posture There are still many differences between human walking and robotic limit cycle walking. Limit cycle walkers must start walking with sufficient initial velocity to overcome the potential barrier at mid-stance, whereas we human can smoothly start walking from the standing posture and can continue walking being not aware of the potential barrier. This comes from the fact that limit cycle walkers have anterior-posterior symmetric impact posture. On the other hand, in human foot, the toe-side is longer than the heel-side. This implies that the human foot has an appropriate shape to put a brake on the forward motion. In contrast, limit cycle walkers must actuate the ankle joint to drive the stance leg forward, and the zero moment point (ZMP) consequently shifts to rearward of the ankle joint. The heel-side is thus more important, but this contradicts humans. Based on the observations, in this paper we propose a novel method for gait generation based on asymmetry of the impact posture, and discuss the role of asymmetric shape of human foot from the ZMP point of view. A simple model of a planar rimless wheel with telescopic legs is introduced, and the validity of the stance-leg extension control is investigated. The gait properties are also numerically analyzed.