The essential multi-degree-of-freedom joints for parallel mechanisms have conventionally been obtained 2 to 3 degrees of freedom with combinations of spherical joints. However, such spherical joints combinations often lead to structural complexity and bulkiness. There are multi-degree-of-freedom sliding spherical ball bearings available, but they come with large frictional resistance and internal clearance issues. Hephaist has developed SRJ – Spherical Rolling Joints as the solutions to all these issues.
