Fiber optic gyroscope with deadband error reduction
First Claim
Patent Images
1. A fiber optic gyroscope having a photodetector coupled to a phase modulator by a feedback circuit, the feedback circuit comprising:
- a demodulator in communication with said photodetector;
a rate accumulator in communication with said demodulator;
a ramp generator in communication with said rate accumulator producing a feedback modulation signal; and
an offset modulation signal generator introducing a source signal into said feedback circuit to produce an offset modulation signal configured to average said feedback modulation signal, said offset modulation signal having a cyclical component with an amplitude substantially equal to an integer multiple of 2π
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Abstract
A deadband error reducer for a fiber optic gyroscope, which is an offset modulation signal that averages the deadband producing error over the range of the feedback modulation signal provided to the phase modulator. Although the offset modulation signal may be introduced at any of several points in the feedback loop, the offset modulation must approximate a critical amplitude at the phase modulator. If the offset modulation is a signal having segments that are linear with time, the critical amplitude of this signal will be 2π.
43 Citations
21 Claims
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1. A fiber optic gyroscope having a photodetector coupled to a phase modulator by a feedback circuit, the feedback circuit comprising:
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a demodulator in communication with said photodetector; a rate accumulator in communication with said demodulator; a ramp generator in communication with said rate accumulator producing a feedback modulation signal; and an offset modulation signal generator introducing a source signal into said feedback circuit to produce an offset modulation signal configured to average said feedback modulation signal, said offset modulation signal having a cyclical component with an amplitude substantially equal to an integer multiple of 2π
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16. A method of operating a Sagnac interferometer comprising the steps of:
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providing an electrical representation of rotation data based upon phase differences between first and second beams of light; demodulating said electrical representation to extract a rotation rate; providing a modulation signal having a modulation component and a nulling component, the nulling component based at least in part upon said rotation rate to a phase modulator for modulating said first and second beams of light; and dithering said modulation signal such that said modulation signal is averaged, thus reducing errors in said rotation rate imposed by said modulation signal. - View Dependent Claims (17, 18, 19)
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20. A feedback electronics circuit for a fiber optic gyroscope, the feedback electronics circuit comprising:
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a demodulator configured to receive a first signal based upon a rate of gyroscope rotation, the demodulator being further configured to demodulate said first signal to produce a rotation signal; an accumulator configured to receive and to integrate said rotation signal to produce a gyroscope output; a signal generator configured to receive said gyroscope output and to produce a feedback modulation signal based upon said gyroscope output; and an offset modulation signal generator configured to produce an offset modulation signal, the offset modulation signal being associated with an averaging of said feedback modulation signal such that deadband errors are reduced. - View Dependent Claims (21)
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Specification