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US 5,926,275 AGranted
Vibration error reduction servo for a fiber optic gyroscope
AssigneeHoneywell Inc.
InventorsGlen A. Sanders, Rudolf C. Dankwort, Andrew W. Kaliszek, Clarence E. Laskoskie, Lee K. Strandjord, Daniel L. Sugarbaker, Jerry L. Page
Life of this patent
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Abstract
A rectification error reducer for a fiber optic gyroscope, which is an intensity servo or compensator for reducing vibration effects in the optical signals caused by modulation at vibration frequencies induced by the gyroscope operating environment. The vibration effects may be detected in signals from the photodiode output in amplitude form which is used in a control system to null out optical intensity variations at the frequencies of vibration.
Claims32
A vibration rectification error reducer for a fiber optic gyroscope, comprising:
- a light source;
- a photodetector;
- a first splitter/combiner having a first waveguide connected to said light source, a second waveguide connected to said photodetector, and a third waveguide;
- an intensity modulator connected to said first splitter/combiner;
- a second splitter/combiner having a first waveguide connected to said intensity modulator or said first splitter/combiner, and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- and
- an intensity modulator driver connected to said photodetector and to said intensity modulator.
5 more elements
A vibration rectification error reducer for a multiple fiber optic gyroscope unit, comprising:
- a light source;
- a three-way splitter having a first waveguide connected to said light source, a second waveguide, a third waveguide and a fourth waveguide;
- a first splitter/combiner having a first waveguide connected to the second waveguide of said three way splitter, and having second and third waveguides;
- a first photo detector connected to the second waveguide of said first splitter/combiner;
- a first intensity modulator connected to said first splitter/combiner;
- a second splitter/combiner having a first waveguide connected to said first intensity modulator and having second and third waveguides;
- a first sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a first filter connected to said first photo detector;
- a first intensity modulator driver connected to said first filter and to said first intensity modulator;
- a third splitter/combiner having a first waveguide connected to the third waveguide of said three way splitter, and having second and third waveguides;
- a second photo detector connected to the second waveguide of said third splitter/combiner;
- a second intensity modulator connected to said third splitter/combiner;
- a fourth splitter/combiner having a first waveguide connected to said second intensity modulator or said third splitter/combiner, and having second and third waveguides;
- a second sensing coil having first and second ends connected to the second and third waveguides, respectively, of said fourth splitter/combiner;
- a second filter connected to said second photo detector;
- a second intensity modulator driver connected to said second filter and to said second intensity modulator;
- a fifth splitter/combiner having a first waveguide connected to the fourth waveguide of said three way splitter, and having second and third waveguides;
- a third photo detector connected to the second waveguide of said fifth splitter/combiner;
- a third intensity modulator connected to said fifth splitter/combiner;
- a sixth splitter/combiner having a first waveguide connected to said third intensity modulator or said fifth splitter/combiner, and having second and third waveguides;
- a third sensing coil having first and second ends connected to the second and third waveguides, respectively, of said sixth splitter/combiner;
- a third filter connected to said third photo detector;
- and
- a third intensity modulator driver connected to said third filter and to said third intensity modulator.
21 more elements
A vibration rectification error reducer for a multiple fiber optic gyroscope unit, comprising:
- a light source;
- a multiple-way splitter having an input waveguide connected to said light source, and having a plurality of output waveguides;
- a plurality of fiber optic gyroscopes wherein each gyroscope is connected to an output waveguide, respectively, of the plurality of waveguides;
- and
- wherein each fiber optic gyroscope comprises:
- a photo detector;
- a first splitter/combiner having a first waveguide connected to an output waveguide of the plurality of waveguides, a second waveguide connected to said photo detector, and a third waveguide;
- an intensity modulator connected to said first splitter/combiner;
- a second splitter/combiner having a first waveguide connected to said intensity modulator and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a filter connected to said first photo detector;
- and
- an intensity modulator driver connected to said filter and to said intensity modulator.
10 more elements
A vibration rectification error reducer for a fiber optic gyroscope, comprising:
- a light source;
- a photo detector;
- a first splitter/combiner having a first waveguide connected to said light source, a second waveguide connected to said photo detector, and a third waveguide;
- a second splitter/combiner having a first waveguide connected to said first splitter/combiner, and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a phase sensitive demodulator connected to said photo detector;
- a modulator situated in an optical path of said sensing coil and said second splitter/combiner;
- a modulator driver connected to said modulator and to said phase sensitive demodulator;
- and
- a rate loop servo connected to said phase sensitive demodulator and to said modulator;
- and
- wherein:
- said rate loop servo nulls phase differences between counter-propagating light waves in said sensing coil due to rotation of said sensing coil;
- and
- said rate loop servo has a bandwidth expanded to frequencies of vibration so as to significantly reduce phase differences between the counter-propagating light waves in said sensing coil caused by vibration.
12 more elements
A vibration rectification error reducer for a fiber optic gyroscope, comprising:
- a light source;
- a first photo detector;
- a second photo detector;
- a first splitter/combiner having a first waveguide connected to said light source, a second waveguide connected to said first photo detector, a third waveguide connected to said second photo detector, and fourth waveguide;
- a second splitter/combiner having a first waveguide connected to said first splitter/combiner, and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a source current controller connected to said second photo detector and said light source;
- a phase sensitive demodulator connected to said first photo detector;
- a modulator situated in an optical path of said sensing coil and said second splitter/combiner;
- a modulator driver connected to said modulator and to said phase sensitive demodulator;
- and
- a rate loop servo connected to said phase sensitive demodulator and to said modulator;
- and
- wherein said rate loop servo has a bandwidth having a range of frequencies of vibration so as to significantly reduce phase differences between the counter-propagating light waves in said sensing coil caused by vibration.
11 more elements
A vibration rectification error reducer for a fiber optic gyroscope, comprising:
- a light source;
- a photo detector;
- a first splitter/combiner having a first waveguide connected to said light source, a second waveguide connected to said photo detector, and a third waveguide;
- a second splitter/combiner having a first waveguide connected to third waveguide of said first splitter/combiner, and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a preamplifier connected to said photo detector;
- a signal generator;
- an amplifier connected to said signal generator;
- an amplifier gain controller connected to said preamplifier and to said amplifier;
- and
- a modulator situated in an optical path of said sensing coil and said second splitter/combiner, and connected to said amplifier;
- and
- wherein:
- said amplifier outputs a modulation signal having an amplitude that is varied in response to an output of said amplifier gain controller;
- the output of said amplifier gain controller is responsive to intensity changes of light at said photo detector cause by vibration;
- and
- the amplitude of the modulation signal is changed so as to reduce effects of vibration on the intensity of the light at the photo detector.
14 more elements
A vibration rectification error reducer for a multiple fiber optic gyroscope unit, comprising:
- a light source;
- a multiple-way splitter having an input waveguide connected to said light source, and having a plurality of output waveguides;
- a plurality of fiber optic gyroscopes wherein each gyroscope is connected to an output waveguide, respectively, of said plurality of waveguides;
- and
- wherein each fiber optic gyroscope comprises:
- a photo detector;
- a first splitter/combiner having a first waveguide connected to an output waveguide of said plurality of waveguides, a second waveguide connected to said photo detector, and a third waveguide;
- a second splitter/combiner having a first waveguide connected to the third waveguide of said first splitter/combiner, and having second and third waveguides;
- a sensing coil having first and second ends connected to the second and third waveguides, respectively, of said second splitter/combiner;
- a signal generator;
- an amplifier connected to said signal generator;
- an amplifier gain controller connected to said photo detector and to said amplifier;
- and
- a modulator situated in an optical path of said sensing coil and said second splitter/combiner, and connected to said amplifier;
- and
- wherein:
- said amplifier outputs a modulation signal having an amplitude that is varied in response to an output of said amplifier gain controller;
- the output of said amplifier gain controller is responsive to intensity changes of light at said photo detector cause by vibration;
- and
- the amplitude of the modulation signal is changed so as to reduce effects of vibration on the intensity of the light at the photo detector.
17 more elements
Dependencies are inferred from the claim text.