Litton Systems, Inc.

Northrop Grumman Systems Corporation

Northrop Grumman Guidance and Electronics Company, Inc.

David Michael Rozelle

Ronald James Michal

Alexander A Trusov

Leo K Lam

Youngmin Albert Choi

Gregory Scott Moore

Robert E Stewart

John P Rahn

David Dexter Lynch

Charles A Lee

James M Pavell

John F Cappi

Fernando Torres

One embodiment of the invention includes a vibrating-mass gyroscope system. The system includes a sensor system comprising a vibrating-mass and a plurality of electrodes coupled to the vibrating-mass that are configured to facilitate in-plane motion of the vibrating-mass. The system also includes a gyroscope controller configured to generate a drive signal that is provided to a first set of the plurality of electrodes to provide an in-plane periodic oscillatory motion of the vibrating-mass along a drive axis, to generate a force-rebalance signal that is provided to a second set of the plurality of electrodes to calculate a rotation of the vibrating-mass gyroscope system about an input axis, and to generate a quadrature signal that is provided to a third set of the plurality of electrodes to substantially mitigate quadrature effects associated with the vibrating-mass.

Vibrating-mass gyroscope systems and method

One example includes a hemispherical resonator gyroscope (HRG). The HRG includes a sensing system comprising a plurality of electrodes arranged in a symmetrical annular arrangement about a sensitive axis and configured to electrostatically force a resonator into a substantially periodic motion based on a plurality of forcer signals applied to the plurality of electrodes. The plurality of electrodes are configured to provide an indication of rotation about a sensitive axis of the HRG. The HRG also includes a controller configured to generate the plurality of forcer signals in a phase-disparate manner to provide the substantially periodic motion in a vibration pattern such that a ratio of the plurality of electrodes and the vibration pattern is a non-integer number, and to measure the rotation about the sensitive axis of the HRG in response to the plurality of forcer signals.

Hemispherical resonator gyroscope

A gyroscope sensor is provided that comprises a resonator including a stem extending along an axis and a shell extending from the stem. The shell includes a hemispherical portion extending from the stem and a cylindrical portion extending from the hemispherical portion. The cylindrical portion includes an outer surface and an inner surface and terminates at an axial end surface that is perpendicular to the outer surface and the inner surface. The resonator further comprises an inner cylindrical substrate that extends along an axis and includes a set of inner electrodes arranged annularly about the axis, and a passage that extends along the axis through a central region of the inner cylindrical substrate. The stem extends through the passage to position the inner cylindrical substrate within the inner surface of the cylindrical portion of the resonator forming gaps between the set of inner electrodes and the inner surface.

Wide rim vibratory resonant sensors

One embodiment of the invention includes a CVG system. A plurality of electrodes electrostatically force a resonator into a periodic motion based on a drive axis forcer signal applied to a first set of the plurality of electrodes and a sense axis force-rebalance signal applied to a second set of the plurality of electrodes, and provides a sense axis pickoff signal and a drive axis pickoff signal. A gyroscope controller generates the drive axis forcer signal based on the drive axis pickoff signal and calculates an angular rate of rotation about an input axis based on the sense axis force-rebalance signal. The gyroscope controller modulates a predetermined disturbance signal component onto the sense axis force-rebalance signal and to control a modulation phase of the sense axis force-rebalance signal based on detection of the predetermined disturbance signal component in the sense axis force-rebalance signal to substantially mitigate bias and scale-factor error.

Bias and scale-factor error mitigation in a Coriolis vibratory gyroscope system

A self-calibrating gyroscope system provides improved estimates of, and compensation or calibration for, scale factor errors and bias errors. The gyroscope system employs a plurality of gyroscope units having sense or input axes in a mutually non-parallel arrangement. A Mode Reversal technique is used to obtain an estimate of bias error for a selected gyroscope. A Random Closed-Loop Scale Factor technique is used to obtain an estimate of scale factor error for a selected gyroscope. Because the Mode Reversal technique temporarily disrupts operation of the affected gyroscope, each of the gyroscopes may be taken offline temporarily, in turn, for calibration, and thereafter returned to normal operation. Because at least one redundant gyroscope is provided, when a selected gyroscope is offline, rate information from the remaining operating gyroscopes can be used to derive a reference rate about the axis of the offline gyroscope.

Self calibrating gyroscope system

The Inner-Forcer milli-Hemispherical Resonator Gyro (mHRG) is a small, low cost, high performance gyroscope. It may have an extremely simplified design, with in one embodiment of the present method and apparatus only five major parts total, with most parts filling multiple functions. The method and apparatus in one embodiment may have: a resonator; and a body operatively coupled to the resonator, the unitary body integrally having electrodes, an electrode support unit, a weld ring and a plurality of electrically conductive pins, the plurality of electrodes operatively coupled to the electrically conductive pins.

Inner-forcer milli-hemispherical resonator gyro

A closed loop scale factor estimator of an apparatus in one example is configured to compare a measured flex angle of a hemispherical resonator gyroscope (HRG) with a demodulation angle signal to estimate a force-to-rebalance (FTR) scale factor for the HRG, wherein the demodulation angle signal corresponds to an integral of a non-uniform rate signal applied to the HRG.

Closed loop scale factor estimation

A source, system and method for generating amplified stimulated emission is provided. The source includes a pump source for generating a pump light which is provided to a doped element, such as a doped fiber. Based on the pump light, the doped fiber, which may be a erbium doped fiber, generates the amplified stimulated emission. A coupler mechanism provides the pump light to the doped fiber and transmits the amplified stimulated emission from the doped fiber. The coupler mechanism isolates the pump light and the amplified stimulated emission using phase conditions. A system is also provided including a source and a sensor, such as a fiber optic gyroscope. A method for generating the amplified stimulated emission is further provided.

Source, system and method for generating amplified stimulated emission using a coupler mechanism

A pump light source provides pump light to an optical fiber arranged to guide the pump light to a first optical isolation device. Light output by the first optical isolation device is input to a wavelength division multiplexer. A gain fiber is connected to the wavelength division multiplexer and arranged to be optically pumped by the pump light such that the gain fiber emits broadband light that propagates to the wavelength division multiplexer. An output optical fiber is connected to the wavelength division multiplexer and arranged to guide a portion of the broadband light emitted by the gain fiber to a second optical isolation device for input to a fiber optic rotation sensor.

Double-pass fully isolated broadband optical signal source for fiber optic interferometric sensors

A wavelength stabilized light source is constructed using a lasing element such as a laser diode which generates light that is substantially polarized. This light is conducted through a polarization maintaining optic fiber to a Bragg grating which reflects a portion of the light back to the laser diode forming a virtual laser cavity and stabilizing the wavelength of the laser diode light output over time and a broad range of temperature and drive circuit conditions. To produce a broad band light source, the laser diode light is used to pump an erbium doped fiber. The wavelength stabilized light source can be used in fiber optic gyroscopes as well as in other applications that require a light source with a very stable wavelength.

Wavelength stabilized laser light source

Apparatus for minimizing the effects of radiation induced attenuation on a sense coil in a fiber optic rotation sensor includes apparatus for injecting photobleach light at a frequency selected to remove radiation-induced color centers. Wavelength division multiplexing optical couplers are used to introduce the photobleach light into the fiber optic rotation sensor system and then remove the photobleach light from the gyroscope optical circuit without effecting the gyro signal.

Apparatus and method for isolated photobleaching fiber optic rotation sensor coils

A system and method for providing scale factor stabilization of a broadband light source used in fiber optic gyroscopes is provided. A primary bandpass filter is positioned in the propagation path of the light emitted by the broadband light source to narrow the spectral width of the optical signal transmitted to the fiber optic gyroscope, which reduces the centroid wavelength shift resulting when the broadband light source is exposed to ionizing radiation and other harsh environmental conditions. The filtered optical signal is then passed through the fiber optic gyroscope, where the filter optical signal is processed to measure the amount of rotation of the fiber optic gyroscope. The scale factor stabilization system further includes the spectral monitor array arranged to perform direct optical wavelength measurements of the filtered optical signal to determine whether a scale factor shift in the optical signal has occurred. When a scale factor shift is detected, the detected scale factor shift is used in a compensation algorithm to correct the scale factor of the optical signal. By monitoring the scale factor shift and adjusting the values measured by the fiber optic gyroscope in accordance with the detected scale factor shift, the accuracy of the fiber optic gyro can be improved to a fraction of a part-per-million.

System and method of stabilizing the scale factor shift in fiber optic

A system for performing scale factor stabilization of a broadband optical signal source used in fiber optic gyroscopes in radiation environments. An optical signal source is provided comprising a pump light source and an optical fiber arranged to receive pump light from the pump light source. Light output from the optical fiber is input into a wavelength division multiplexer. An optical gain fiber having an erbium-doped core is connected to the wavelength division multiplexer and arranged to be optically pumped by the pump light such that the gain fiber emits broadband light that propagates to the wavelength division multiplexer. An output optical fiber is connected to the wavelength division multiplexer and arranged to guide a portion of the broadband light emitted by the gain fiber to a fiber optic gyroscope. A filter device is positioned in-line with the broadband light emitted by the gain fiber to attenuate light outside of the bandwidth of the filter device. The filter device allows a bandwidth of light narrower than the spectral width of the broadband light source to propagate through while attenuating all wavelengths of light outside of its operating bandwidth. Only the portion of the broadband source spectrum contained within the bandpass of the filter is selected out, thus narrowing the spectral width of the broadband fiber source. This narrower spectral width reduces the shift of centroid wavelength of the broadband fiber source which results when the gain fiber and other sensitive optical components are exposed to ionizing radiation.

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Woodland Hills, CA, United States of America

David Michael Rozelle