ALL-FIBER INTERFEROMETRIC FIBER OPTIC GYROSCOPE FOR INHIBITING ZERO DRIFT

• US 20120092676A1
• Filed: 03/07/2011
• Published: 04/19/2012
• Est. Priority Date: 10/15/2010
• Status: Active Grant

• Current Assignee: Peking University
• Original Assignee: Peking University
• Inventors: Wang, Xinyue, Wang, Ziyu, He, Changhong
• Granted Patent: US 8,422,021 B2
• Time in Patent Office: Days
• US Class Current: 356/461
• CPC Class Codes: G01C 19/72 with counter-rotating light beams in a passive ring, e.g. fibre laser gyrometers

Abstract

A method for inhibiting zero drift of an all-fiber interferometric fiber optic gyroscope and a corresponding all-fiber interferometric fiber optic gyroscope are disclosed. The method comprises: reversing the polarity of an AC voltage applied to a PZT piezoelectric ceramic phase modulator according to a predetermined half-cycle time period, and making half of the difference between output rotation rates of the gyroscope in two adjacent half-cycle time periods as the output rotation rate of the gyroscope in a cycle. A phase reversal switch and a DSP chip are added to the all-fiber interferometric fiber optic gyroscope. The phase reversal switch is used for controlling the polarity of the AC voltage, and the DSP chip is used for outputting a square wave signal to control the phase reversal switch and for calculating the output rotation rate of the gyroscope according to the output signal of a demodulation/amplifier circuit.

Claims

1. A method comprising:

inhibiting zero drift of an interferometric fiber optic gyroscope by;

reversing the polarity of an AC signal applied to a phase modulator of the gyroscope, according to a predetermined half-cycle time period;

determining output rotation rates of the gyroscope in two adjacent half-cycles; and

calculating a final output rotation rate of the gyroscope in a cycle based on a difference between the determined output rotation rates of the gyroscope in the two adjacent half-cycles.

2. The method according to claim 1, wherein the output rotation rates of the gyroscope in the two adjacent half-cycles are determined by a demodulator/amplifier.

3. The method according to claim 1, wherein the phase modulator is a PZT piezoelectric ceramic phase modulator.

4. The method according to claim 1, wherein reversing the polarity of the AC signal is controlled by a square wave signal.

5. The method according to claim 4, wherein the ratio of the cycle of polarity switching of the AC signal to the cycle of the AC signal is greater than 1000.

6. A method for inhibiting zero drift of an all-fiber interferometric fiber optic gyroscope, comprising:

reversing the polarity of an AC voltage applied to a PZT piezoelectric ceramic phase modulator according to a predetermined half-cycle time period, and

making the output rotation rate of the gyroscope in a cycle equal to half of the difference between output rotation rates of the gyroscope in two adjacent half-cycles.

7. The method according to claim 6, wherein the switch of the polarity of the AC voltage is realized by:

a phase reversal switch is provided between an oscillator for generating the AC voltage and the PZT piezoelectric ceramic phase modulator;

wherein the phase reversal switch periodically switches the polarity of the AC voltage applied to the PZT piezoelectric ceramic phase modulator.

8. The method according to claim 7, wherein the phase reversal switch is controlled by a square wave signal.

9. The method according to claim 6, wherein the ratio of the cycle with polarity switch of the AC voltage to the cycle of the AC voltage is greater than 1000.

10. An all-fiber interferometric fiber optic gyroscope, comprising

a first portion including a light source, a fiber optic loop and a photodetector, optically coupled to each other;

and

a circuit portion coupled to the first portion, the circuit portion including

a piezoelectric phase modulator;

a demodulator;

an oscillator to apply an AC signal to the piezoelectric phase modulator;

a phase reversal switch coupled between the oscillator and the piezoelectric phase modulator to control the polarity of the AC signal; and

circuitry coupled to the phase reversal switch and the demodulator and configured to;

output a square wave signal to control the phase reversal switch to reverse the polarity of the AC signal applied to the piezoelectric phase modulator according to a predetermined half-cycle time period; and

calculate an output rotation rate of the gyroscope in a cycle, based on an output of the demodulator, as a function of a difference between output rotation rates of the gyroscope in two adjacent half-cycles.

11. The gyroscope according to claim 10, wherein the ratio of the cycle of polarity reversal of the AC signal to the cycle of the AC signal is greater than 1000.

12. The gyroscope according to claim 10, wherein the optical portion further comprises:

a light source coupler optically coupled to the light source;

a polarizer optically coupled to the light source; and

a fiber optic loop coupler optically coupled to the light source.

13. The gyroscope according to claim 10, wherein said circuitry is embodied in a digital signal processor chip.

14. An all-fiber interferometric fiber optic gyroscope, comprising

a superluminescent diode;

a light source coupler;

a polarizer;

a fiber optic loop coupler;

a fiber optic loop;

an oscillator;

a PZT piezoelectric ceramic phase modulator;

a photodetector diode;

a demodulation/amplifier circuit;

wherein the light source coupler, the superluminescent diode, the polarizer, the photodetector diode are coupled via signal;

the fiber optic loop coupler, the polarizer and the fiber optic loop are coupled via signal;

the demodulation/amplifier circuit and the photodetector diode are coupled via signal;

the oscillator applies an AC voltage to the PZT piezoelectric phase modulator, and part of an end of the fiber optic loop is wound around an outer circle of the PZT piezoelectric ceramic phase modulator;

a phase reversal switch provided between the oscillator and the PZT piezoelectric ceramic phase modulator for controlling the polarity of the AC voltage; and

a DSP chip, coupled to the phase reversal switch and the demodulation/amplifier circuit via signal, which is used to;

output a square wave signal and control the phase reversal switch to reverse the polarity of the AC voltage applied to the PZT piezoelectric ceramic phase modulator according to a predetermined half-cycle time period; and

calculate a half of the difference between output rotation rates of the gyroscope in two adjacent half-cycles as an output rotation rate of the gyroscope in a cycle according to the output signal of the demodulation/amplifier circuit and a phase of the square wave signal.

15. The gyroscope according to claim 14, wherein the ratio of the cycle with polarity switch of the AC voltage to the cycle of the AC voltage is greater than 1000.