Recovery of proper body orientation is one of the most basic robotic self-manipulation tasks. It becomes most critical in autonomous scenarios as well as teleoperation, where the robot may be unreachable. In such cases, the inability to autonomously recover from even a simple fall may render the robot completely useless, decreasing the overall robustness of the platform for real-world missions.

Traditionally, robots adopt specialized kinematic structures and actuators specifically designed for relf-righting. RHex is not equipped with such mechanisms and cannot achieve self-righting through purely kinematic maneuvers. RHex can only achieve self-righting by use of its body dynamics to manipulate its orientation. We have recently designed a feedback controller based on a planar model of RHex that can dynamically perform back-flips over a variety of indoor and outdoor surfaces such as carpet, asphalt and grass. This controller serves both as a useful behavioral tool and as an important step towards more sensor based dynamic behaviors on RHex.