A three-dimensional passive-dynamic walking robot with two legs and knees

The authors have built the first three-dimensional, kneed, two-legged, pass ive-dynamic walking machine. Since the work of Tad McGeer in the late 1980s , the concept of passive dynamics has added insight into animal locomotion and the design of anthropomorphic robots. Various analyses and machines tha t demonstrate efficient humanlike walking have been developed using this st rategy. Human-like passive machines, however have only operated in two dime nsions (i.e., within the fore-aft or sagittal plane). Three-dimensional pas sive walking devices, mostly toys, have not had human-like motions but inst ead a stiff legged waddle. In the present three-dimensional device, the aut hors preserve features of McGeers two-dimensional models, including mechani cal simplicity, human-like knee flexure, and passive gravitational power fr om descending a shallow slope, They then add specially curved feet, a compl iant heel, and mechanically constrained arms to achieve a harmonious and st able gait. The device stands 85 cut tall. It weighs 4.8 kg, walks at about 0.51 mls down a 3.1-degree slope, and consumes 1.3 W. This robot further im plicates passive dynamics in human walking and may help point the way towar d simple and efficient robots with human-like motions.