In order to minimize cost and complexity of legged robots, we investigate the design and control of simple mechanical designs for quadruped robots which feature only one actuated degree of freedom per leg. Two protoypes of such robots, SCOUT I and SCOUT II have been built and have demonstrated experimentally to be capable of walking, turning, and climbing over a step, despite their mechanical simplicity. The underlying principle is dynamic operation, based on controlled momentum transfer. When the legs are made compliant, running (bounding) is achievable as well.
ARL Scout I
ARL Scout II