Systems and methods for environmentally insensitive high-performance fiber-optic gyroscopes
First Claim
1. A fiber optic gyroscope comprising:
- a light source coupled to an optical media;
a fiber optic coil that receives a first light beam and a second light beam from light generated by the light source;
an optical phase modulator coupled between the optical media and the fiber optic coil, wherein the optical phase modulator performs a phase modulation on the first light beam and the second light beam based on an electrical signal, wherein the phase modulation is related to the electrical signal by a transfer function that includes an error component of at least second order;
a photo detector coupled to the optical media, wherein the photo detector detects a combination of the first light beam and the second light beam returning from the fiber optic coil; and
loop closure electronics coupled to the optical phase modulator and the photo detector, wherein the loop closure electronics produces and outputs the electrical signal to the optical phase modulator, the loop closure electronics including an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter compensate for the error component.
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Abstract
Systems and methods for environmentally insensitive high-performance fiber-optic gyroscopes are provided. In one embodiment, a loop closure electronics apparatus for a fiber optic gyroscope having an optical phase modulator characterized by a transfer function that includes an error component of at least second order is provided. The apparatus comprises: a first digital circuit that generates a digital bias modulation signal; a second digital circuit that generates a digital feedback signal; at least one digital-to-analog converter that produces an electrical signal that drives the phase modulator from the digital bias modulation signal and the digital feedback signal; and a compensator that includes an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter pre-filter the electrical signal to compensate for the error component.
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Citations
20 Claims
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1. A fiber optic gyroscope comprising:
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a light source coupled to an optical media; a fiber optic coil that receives a first light beam and a second light beam from light generated by the light source; an optical phase modulator coupled between the optical media and the fiber optic coil, wherein the optical phase modulator performs a phase modulation on the first light beam and the second light beam based on an electrical signal, wherein the phase modulation is related to the electrical signal by a transfer function that includes an error component of at least second order; a photo detector coupled to the optical media, wherein the photo detector detects a combination of the first light beam and the second light beam returning from the fiber optic coil; and loop closure electronics coupled to the optical phase modulator and the photo detector, wherein the loop closure electronics produces and outputs the electrical signal to the optical phase modulator, the loop closure electronics including an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter compensate for the error component. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for a fiber optic gyroscope, the method comprising:
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characterizing a frequency response of an optical phase modulator, wherein the optical phase modulator performs a phase modulation of a light beam based on an electrical signal input; determining a transfer function for the optical phase modulator based on the frequency response, wherein the transfer function includes an error component of at least second order; forming an analog filter of at least second order, wherein at least two poles of the analog filter are placed to compensate for two zeros of the error component and at least two zeros of the analog filter are placed to compensate for two poles of the error component; forming a closed loop fiber optic gyroscope circuit, the circuit including a light source coupled to an optical media, a fiber optic coil that receives a first light beam and a second light beam from light generated by the light source, the optical phase modulator coupled between the optical media and the fiber optic coil, a photo detector coupled to the optical media, wherein the photo detector detects a combination of the first light beam and the second light beam returning from the fiber optic coil, and loop closure electronics coupled to the optical phase modulator and the photo detector, wherein the loop closure electronics drives the electrical signal input to the optical phase modulator, wherein the electrical signal is pre-filtered by the analog filter and a digital filter of at least second order; characterizing a frequency response of the closed loop fiber optic gyroscope circuit; and adjusting coefficients of the digital filter until a flat frequency response is obtained for closed loop fiber optic gyroscope circuit. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A loop closure electronics apparatus for a fiber optic gyroscope having an optical phase modulator characterized by a transfer function that includes an error component of at least second order, the apparatus comprising:
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a first digital circuit that generates a digital bias modulation signal; a second digital circuit that generates a digital feedback signal; at least one digital-to-analog converter that produces an electrical signal that drives the phase modulator from the digital bias modulation signal and the digital feedback signal; a compensator that includes an analog filter of at least second order and a digital filter of at least second order, wherein the analog filter and the digital filter pre-filter the electrical signal to compensate for the error component. - View Dependent Claims (17, 18, 19, 20)
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Specification