Fiber optic gyroscope with variable output period
First Claim
Patent Images
1. A system, comprising:
- a fiber optic gyroscope for sensing angular rate comprisinga light source for generating a light output;
a splitter/modulator for splitting the light output into two beams, modulating one of the beams, and recombining the two beams;
a fiber optic sense coil for directing one of the beams in a clockwise direction through the fiber optic sense coil and the other of the beams in a counterclockwise direction through the fiber optic sense coil; and
a detector for detecting the recombined beams and providing an output proportional to the magnitude of the recombined beams; and
a processor for generating a feedback signal and an output signal, comprisingfirst ramp generator means, responsive to the output of the detector, for generating a feedback signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the feedback signal assumes a steady-state operating point for any given angular rate;
a biasing function generator for shifting the steady-state operating point of the feedback signal;
a dither pattern generator for generating a waveform for continuously oscillating the feedback signal about the instantaneous value of the operating point;
means for providing the feedback signal to the splitter/modulator;
second ramp generator means, responsive to the output of the detector, for generating a signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the signal assumes a steady-state operating point for any given angular rate; and
output processing means, responsive to the signal generated by the second ramp generator means, for generating an output signal.
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Abstract
The linearity of a fiber optic gyroscope can be improved by dithering the gyroscope'"'"'s feedback signal. An output signal can be taken over any time interval by sampling the feedback signal before dithering is applied.
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Citations
17 Claims
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1. A system, comprising:
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a fiber optic gyroscope for sensing angular rate comprising a light source for generating a light output; a splitter/modulator for splitting the light output into two beams, modulating one of the beams, and recombining the two beams; a fiber optic sense coil for directing one of the beams in a clockwise direction through the fiber optic sense coil and the other of the beams in a counterclockwise direction through the fiber optic sense coil; and a detector for detecting the recombined beams and providing an output proportional to the magnitude of the recombined beams; and a processor for generating a feedback signal and an output signal, comprising first ramp generator means, responsive to the output of the detector, for generating a feedback signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the feedback signal assumes a steady-state operating point for any given angular rate; a biasing function generator for shifting the steady-state operating point of the feedback signal; a dither pattern generator for generating a waveform for continuously oscillating the feedback signal about the instantaneous value of the operating point; means for providing the feedback signal to the splitter/modulator; second ramp generator means, responsive to the output of the detector, for generating a signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the signal assumes a steady-state operating point for any given angular rate; and output processing means, responsive to the signal generated by the second ramp generator means, for generating an output signal. - View Dependent Claims (2, 3, 4, 5)
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6. A signal processor for generating a feedback signal and an output signal in response to the output of a rate-sensing fiber optic gyroscope comprising a light source for generating a light output;
- a splitter/modulator for splitting the light output into two beams, modulating the beams in response to the feedback signal, and recombining the two beams;
a fiber optic sense coil for directing one of the beams from the splitter/modulator in a clockwise direction through the fiber optic sense coil and the other of the beams in a counterclockwise direction through the fiber optic sense coil; and
a detector for detecting the recombined beams and providing an output proportional to the magnitude of the recombined beams;
the signal processor comprising;first ramp generator means, responsive to the output, for generating a feedback signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the feedback signal assumes a steady-state operating point for any given angular rate; a biasing function generator for shifting the steady-state operating point; a dither pattern generator for generating a waveform for continuously oscillating the feedback signal about the instantaneous value of the operating point; means for providing the feedback signal to the splitter/modulator; second ramp generator means, responsive to the output of the detector, for generating a signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the signal assumes a steady-state operating point for any given angular rate; and output processing means, responsive to the signal generated by the second ramp generator means, for generating an output signal. - View Dependent Claims (7, 8, 9, 10)
- a splitter/modulator for splitting the light output into two beams, modulating the beams in response to the feedback signal, and recombining the two beams;
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11. A method of sensing angular rate in a fiber optic gyroscope comprising a fiber optic sense coil, comprising the steps of:
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generating a light output; splitting the light output into two beams; directing one of the beams in a clockwise direction through the fiber optic sense coil and the other of the beams in a counterclockwise direction through the fiber optic sense coil; recombining the two beams; detecting the recombined beams and providing an output proportional to the magnitude of the recombined beams; and in response to the output, generating a feedback signal and modulating one of the light beams in response to the feedback signal, the step of generating a feedback signal including the steps of; generating a feedback signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the feedback signal assumes a steady-state operating point for any given angular rate; shifting the steady-state operating point; and continuously oscillating the feedback signal about the instantaneous value of the operating point; in response to the output, generating a second signal proportional to the phase difference between the clockwise and the counterclockwise beams, where the second signal assumes a steady-state operating point for any given angular rate; and in response to the step of generating a second signal, generating an output signal. - View Dependent Claims (12, 13, 14, 15)
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16. An apparatus for reducing non-linearity in a closed-loop fiber optic gyroscope for sensing applied angular rate, comprising:
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means for generating a feedback signal proportional to the applied angular rate; means for continuously oscillating the feedback signal about the instantaneous value of the operating point; and means for extracting the feedback signal prior to the means for continuously oscillating the signal.
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17. A method of reducing non-linearity in a closed-loop fiber optic gyroscope for sensing applied angular rate, comprising the steps of:
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generating a feedback signal proportional to the applied angular rate; continuously oscillating the feedback signal about the instantaneous value of the operating point; and extracting the feedback signal prior to oscillating the signal about the operating point.
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Specification