R-FOG Signal Detection Method Based On Double Resonator Structure

Resonator fiber optic gyroscope is a new type of inertial sensor device.The angular velocity information of a moving carrier is obtained by the resonance frequency difference between two oppositely transmitted light waves in a sensitive resonant cavity.In theory,only a dozen meters of fiber resonator can be used to achieve inertial navigation accuracy,and it has a huge market application prospect in the future with high-precision and integrated development trends.However,there are many optical noises in the resonator,such as backscattering noise and polarization fluctuation noise,etc.,which greatly limits the accuracy of gyroscope detection.This article is mainly aimed at the asymmetry of the resonance curve caused by optical noise,and proposes corresponding signal detection methods,in order to achieve the purpose of eliminating gyro drift and improving the dynamic detection performance of gyro.The main research contents of the paper are as follows:Firstly,the theoretical basis of the resonator fiber optic gyroscope is introduced.The light wave field superposition theory is used to analyze the transmission characteristics of light waves in the resonator.The influence of various structural parameters on the resonance characteristics is also studied.Secondly,the generation mechanism and suppression methods of backscattering noise and polarization fluctuation noise existing in the resonator are analyzed respectively,and the advantages and disadvantages of the existing suppression methods are pointed out.The influence of these two kinds of noise on the asymmetry rate of the resonance curve is studied to lay the foundation for the subsequent signal detection methods.Next,the system composition of the resonator fiber optic gyro is introduced,and the specific influence of the asymmetry of the resonance curve on the output drift of the gyro in the triangle wave modulation and demodulation scheme is analyzed.In order to suppress the output error caused by the asymmetry of the resonance curve,from the perspective of signal detection,Design a fiber-optic gyro system with a dual-resonator structure,and add a MZI thermo-optical switch to the optical path structure to periodically change the transmission direction of light waves in the cavity.Based on this structure,a new signal detection method is proposed,and the specific process of signal detection in a complete modulation period is discussed in detail.Finally,the newly proposed signal detection method is analyzed theoretically and verified by simulation.The dual-cavity and single-cavity resonator fiber optic gyroscopes are compared in terms of the zero offset of the demodulation curve and the dynamic detection performance.The influence of backscattering noise is completely avoided from the structural characteristics,and the signal detection method proposed in this paper can completely eliminate the gyro drift error caused by non-reciprocity factors in the triangular wave modulation process.The analog gyro rotates at a fixed angular rate at different temperatures,and uses the side of the resonance curve that is less affected by polarization fluctuations to detect the signal.It can be deduced from the numerical simulation comparison results that the new detection method can maximize the thermally induced polarization.The new detection method can reduce the angular rate detection deviation caused by thermally induced polarization fluctuations by an order of magnitude.