Our Omnisphere robot is a user-friendly controlled platform with three spheres for wheels. A friction-based drive system rotates each sphere with 360 degrees of full planar freedom. This system eliminates the restrictive motions associated with common cylindrical-wheel systems and utilizes previously unattainable motions.
Ballentine, Chris; Dudamel, Gerardo; Frisbie, James; and Taylor, Macdonald, "Omnisphere" (2016). Electrical Engineering and Computer Science Student Publications. 46.