Stumbling upon a novel idea, even if it's not exactly new, is always exciting.
Came across this virtual rolling contact joint when researching spherical rolling joints.
Created by IRIM LAB KOREATECH & genius in its simplicity, this joint consists of three pivoting linkages that allows for 2 DOF in roll & pitch.
They then integrated it into a robotic arm, complete with a driveshaft passing through the center.
Has anyone ever used one of these designs in practice?