US Patent 7441442 System for determining the displacement of a movable member

A means for simultaneous determination of the radial and angular vectors of rotary motion of a body relative to a single reference axis, by measurement of the common aid differential states of three position detectors and, together with an axial position detector, thus to allow the measurable modulation of magnetic devices such as to provide measurable vector forces to support that body against the vector effects of any external forces that tend to change its position relative to the reference axis, in the absence of any contact between the rotor and the combined system of sensors and magnetic devices.