Rollbot.zip -
This paper details the design of a minimalist spherical robot that uses only one actuator to achieve controlled rolling motion.
To create the simplest possible spherical robot for use as a testbed in underactuated robotics. Key Content:
You can find the full paper on arXiv and the accompanying open-source implementation on GitHub . Other "Rollbot" Projects
Derivation of how internal masses drive spherical rolling.