Abstract: An adjustable resistance hinge system for a joint connecting at least a first articulating member and a second articulating member, the hinge system comprising a central element defining a hinge axis. The central element comprises a first and a second elongate arm, each elongate arm extending away from the hinge axis, and a first and a second keeping element hinging on the hinge axis are attached to the first and the second articulating members, respectively. A first and a second biasing device are also engageable with the first and the second elongate arms, respectively. The first and the second elongate arms extend into the first and the second articulating members, respectively, and the first and the second biasing devices engage the central element to resist relative motion of the first and the second articulating members about the hinge axis. The adjustable resistance hinge system allows two joined members to be adjusted to replicate desired physiology, limits, and resistance.

Abstract: A method and apparatus for testing roll together of a mattress using two weights, preferably weighted cylinders, and moving one of the weights towards the other while measuring change in distance between the weights and changes in angle of the stationary weight.

Abstract: A method and apparatus for testing rolling resistance of a mattress by rolling a cylindrical weight across at least a portion of the mattress and measuring torque of the cylindrical weight moving across the mattress. The apparatus is preferably automated and preferably continuously measures torque as the cylinder is continuously moved across the mattress at a constant speed.

Abstract: A method and apparatus for testing roll together of a mattress using two weights, preferably weighted cylinders, and moving one of the weights towards the other while measuring change in distance between the weights and changes in angle of the stationary weight.

Abstract: A method and apparatus for testing rolling resistance of a mattress by rolling a cylindrical weight across at least a portion of the mattress and measuring torque of the cylindrical weight moving across the mattress. The apparatus is preferably automated and preferably continuously measures torque as the cylinder is continuously moved across the mattress at a constant speed.