US 4,017,187 AGranted

Double rotation inertial measurement apparatus

AssigneeSperry Rand Corporation

InventorBernard Schwartz

Life of this patent

Estimating the term…

Loading patent…

Abstract

Apparatus for sensing movement with respect to mutually orthogonal axes includes a plurality of ring laser motion sensors, mounted so as to lie as if in planes which would define contiguous mutually perpendicular surfaces such as are found at a corner of a cube, wherein the cube is rotated constantly about a diagonal axis thereof. The rotation imparts equal components of rotation to each of the ring laser motion sensors, thereby eliminating the effects of mode locking and assuring that the beat frequencies obtained by heterodyning signals related to the contra-rotating light waves of each motion sensor are linearly related, over the operating range of the inertial device, to the components of rotational rate measured parallel to the input axes of the respective ring laser motion sensors. The rotating sensor system is supported along its spin axis in an inner gimbal member for rotation, in turn, about an outer or vertical axis perpendicular thereto. The effects of fixed or slowly changing bias errors are substantially cancelled in the system, any remaining drift about inertial or earth's coordinate axes being substantially minimized by periodic reversal of the sense of rotation about the outer axis.

Claims12

Dependent claims

Inertial measurement apparatus comprising:

a plurality of equi-spaced ring laser means similarly disposed upon an inner spin member about a spin axis, thereof,
all of said ring laser means being disposed in individual planes at equal predetermined angles with respect to said spin axis,
spin motor means for rotating said inner spin member about said inner spin axis in a predetermined direction for eliminating mode-lock operation of each of said ring laser means within a predetermined operating range and whereby first components of bias and scale factor errors of the ring laser means outputs are cancelled,
drive frame means including first trunnion means for supporting said inner spin member therein,
reversible motor means for reversibly rotating said drive frame means about a second axis substantially perpendicular to said inner spin axis whereby second components of bias and scale factor errors of said ring laser means output are cancelled, and
fixed frame means including second trunnion means for supporting said drive frame means for reversible rotation about said second axis,
said reversible motor means serving to drive said drive frame means with respect to said fixed frame means through successive integral numbers of revolutions after respective successive reversals thereof.

4 more elements

Dependencies are inferred from the claim text.