RHex: A Simple and Highly Mobile

In this paper, the authors describe the design and control of RHex, a power autonomous, untethered, compliant-legged hexapod robot. RHex has only six actuators—one motor located at each hip— achieving mechanical simplicity that promotes reliable and robust operation in real-world tasks. Empirically stable and highly maneu-verable locomotion arises from a very simple clock-driven, open-loop tripod gait. The legs rotate full circle, thereby preventing the common problem of toe stubbing in the protraction (swing) phase. An extensive suite of experimental results documents the robot’s sig-nificant “intrinsic mobility”—the traversal of rugged, broken, and obstacle-ridden ground without any terrain sensing or actively con-trolled adaptation. RHex achieves fast and robust forward loco-motion traveling at speeds up to one body length per second and traversing height variations well exceeding its body clearance. KEY WORDS—legged locomotion, hexapod robot, clock driven, mobility, autonomy, biomimesis 1