Patent ID: 8251938

Claim:
A device comprising a first plate and a second plate; and a linkage system comprising at least three rods, each having a first end and a second end; wherein: the first ends of the rods are attached to the first plate, each by a universal joint; the second ends of the rods are attached to the second plate, each by a universal joint; the rods are arranged such that they are: parallel to one another; and do not all lie in one plane; the universal joints attaching the first plate to the first ends of the rods lie in a first plane; and the universal joints attaching the second plate to the second ends of the rods lie in a second plane parallel to the first plane; such that: the first plate and the second plate are capable of translating relative to each other; and the first plate and the second plate are incapable of rotating relative to each other.