Ringbot: Monocycle Robot with Legs

This article presents the development and evaluation of Ringbot, a novel leg-wheel transformer robot incorporating a monocycle mechanism with legs. Ringbot aims to provide versatile mobility by replacing the driver and driving components of a conventional monocycle vehicle with legs mounted on compact driving modules inside the wheel. The article covers the hardware and software implementation of a prototype robot. The Ringbot prototype features a wheel and two driving modules located inside, each equipped with a 3-DoF leg for balancing, steering, and legged motions to assist monocycle driving. The driving control is achieved through decoupled speed controller and steering controller. In addition, active-legged motions are implemented and managed through a finite-state machine. The controllers for wheeled driving and legged motions were tested in a simulation environment, as well as on the hardware prototype, to verify the concept of a monocycle with legs and evaluate the prototype's capabilities.

Ringbot was tested on a 3 km track and completed the run in 37 minutes using a single battery charge.

K. G. Gim and J. Kim, "Ringbot: Monocycle Robot With Legs," in IEEE Transactions on Robotics, vol. 40, pp. 1890-1905, 2024, doi: 10.1109/TRO.2024.3362326.