The ARL monopod II running robot: control and energetics

This paper presents the experimental implementation of an energy efficient "controlled passive dynamic running" strategy on a planar one-legged running robot with hip and leg compliance. We (1997) introduced the approach previously via simulations, and tested via preliminary experiments. The improved version described here permits running speed of up to 4.5 km/h with a total mechanical power expenditure of only 48 W, which translates into a specific resistance of only 0.22. This is the highest efficiency among all actively controlled legged robots.