Patent ID: 8342054

Claim:
A spatial linkage comprising: an inboard gimbal plate that provides a ground for the spatial linkage; an outboard gimbal plate; at least three links, each link having a longitudinal axis and two pivotal couplings disposed at opposite ends of the longitudinal axis, each link pivotally coupled to the outboard gimbal plate at a first end of the longitudinal axis and pivotally coupled to the inboard gimbal plate at a second end of the longitudinal axis opposite the first end, the pivotal couplings allowing the outboard gimbal plate to move relative to the inboard gimbal plate with two degrees of freedom and keeping the outboard gimbal plate parallel to the inboard gimbal plate; a load coupled to the outboard gimbal plate; and a counterweight coupled to at least one of the links on the opposite side of the inboard gimbal plate from the outboard gimbal plate to counterbalance the load regardless of a position of the load with respect to the outboard gimbal plate.