Error Analysis And Correction Method For Digital Closed-Loop Interferometric Fiber Optic Gyros

Interferometric fiber optic gyroscope is an optical measurement system based on the Sagnac effect.The Sagnac interferometer optical sensor body realizes the linear mapping between the measured angular velocity and the interference phase,while the digital signal processing part realizes the tracking,control and measurement of the angular velocity.This paper briefly explains the all-digital closed-loop processing technology proposed by Dr.H.C.Lefevre,and completes system modeling and stability analysis in the Z domain.This article further analyzes the impact of loop gain on system response,and proposes a loop gain control scheme.The experimental results achieve the expected goal.In this paper,the cause of low-speed measurement offset distortion of the interferometric fiber optic gyroscope is further discussed and analyzed,and the same frequency crosstalk of the modulation signal is proved to be the root cause of the low-speed measurement offset distortion by software simulation.At the same time,the theoretical calculation shows that the width of the low-speed measurement distortion region has a quadratic relationship with the signal crosstalk intensity.According to the signal crosstalk model,this paper uses a pseudo-random modulation and demodulation method to improve the speed measurement system.On the basis of pseudo-random modulation and demodulation,the control target of loop gain is also achieved.At the same time,a corresponding tracking cancellation module is designed for the random walk error caused by signal crosstalk.The newly designed control scheme is verified and tested on a 300 m polarization-maintaining fiber ring.The non-linearity of the gyroscope scale factor is 30.223 ppm,and the temperature sensitivity of the scale factor is 6.01 ppm.The standard deviation(zero drift)of the gyroscope output at room temperature is 0.3544°/h,random walk coefficient is 0 005 °/?,zero bias instability is 0.0188°/h;output standard deviation(zero drift)at variable temperature is 0.5809°/h;no bias distortion and dead zone at small rotation rates.