Universal joint flexure assembly

Claim 1

A gyroscope which includes a rotor, a shaft for driving said rotor about a spin axis, and a dual two-axis universal joint multi-flexure unit for interconnecting said rotor to said shaft and comprising inner and outer multi-gimbal hinge assemblies attached to one another so that a middle gimbal of the inner hinge assembly moves wiTh the rotor as the rotor is flexed around a first flexure axis, and so that middle gimbal of the outer hinge assembly moves with the rotor when the rotor is flexed around a second flexure axis displaced ninety degrees from the first flexure axis, the combination of an elongated rod coaxially positioned relative to the spin axis of the middle gimbal of said inner hinge assembly and adjustable along said spin axis to define a moment of inertia of said last-named middle gimbal to compensate dynamically the spring rate torques of flexure which flex when said middle gimbal of said inner hinge assembly moves with said rotor, and said rod being effective to adjust for unbalance around said first flexure axis in a plane perpendicular to said spin axis; and compensation weights mounted on said middle gimbal of said outer hinge assembly to define the moment of inertia of said last-named middle gimbal to compensate dynamically for the spring rate torques of flexure which flex when said middle gimbal of said outer hinge assembly moves with said rotor, said compensation weights being effective to adjust for unbalance around said second flexure axis in a plane perpendicular to said spin axis, the combined compensation of said rod and of said weights dynamically compensating for spring rate torques and eliminating gyroscopic rectified drift errors due to angular vibrations and linear vibrations occurring at twice the rotor speed frequency.