RHex is a small, power and computationally autonomous hexapod robot with passively compliant legs. Its basic design incorporates only one actuator per leg, capable of achieving fast (~2.5m/s) and robust locomotion over complex outdoor terrain. As a result of the minimal use of exteroceptive sensing, most of its behaviors are task-level open loop, driven by an internal clock. These basic behaviors rely on a human operator for more complicated tasks such as navigation.

In the first few years following RHex's construction, we have characterized and significantly improved the performance and mobility of its open-loop behaviors such as walking, turning, stair climbing and hill climbing. The current research direction for RHex is towards understanding how to combine the robustness of open-loop strategies with the extended performance and capabilities that are afforded by additional sensing such as inertial and visual feedback.