Research On Signal Processing Of Interferometric Fiber Optic Gyro And Resonator Fiber Optic Gyro

Fiber-optic gyroscope(FOG)is an inertial sensor to measure the rotation rate,which is based on Sagnac effect.FOG can be classified into two types:resonator fiber-optic gyros(RFOGs)and interferometric fiber-optic gyros(IFOGs).IFOGs have been widely used in many applications,but RFOGs are still in an experimental phase.In this paper,the research on the signal processing of FOGs is presented.It is primarily divided into two parts.In the previous part of the paper,we mainly treat some improvements in signal processing of digital closed-loop IFOGs.They consist of that:(1)a PIN photodectector and a FET OP Amp are exploited to replace the traditional integrated PIN-FET device.In the latter part,a new signal processing scheme on digital closed-loop RFOGs is proposed.In the novel proposal,we adopt the low frequency sin wave modulation and analog device hardware demodulation techniques,which have the advantage of high response speed.This paper firstly introduce some usual optical devices and two signal detection schemes in FOGs.The related design principle of photodetectors' circuits and test results are shown afterwards.Then,each module in the signal processing circuit of IFOGs is further analyzed and the novel prototype is tested.At last,each module in the signal processing circuit of RFOGs is also analyzed and the performance of the prototype is also proved.The experimental results are shown as fellow:(1)Compared with the traditional integrated PIN-FET device,the performance of the photodetector comprised of high-gain trans resistance amplifier is better.What's more,the corresponding cost has fallen by about 90 percent.(2)At room temperature,test results of the IFOG applying the photodetector demonstrate that the zero bias is-7.880/h(including the projection-7.560/h of the earth's rotation in Hangzhou),the bias drift is 0.027°/h and the angular random walk is about 0.00230°/(?).Compared with the original scheme,the power cost can drop 200mW and the circuit area of the pre-amplifier module can fall by about 40 percent.(3)The photodetector designed by analog integrator has been implemented initially,but the prototype has not been tested.(4)A sin wave modulation signal whose signal-to-noise(SNR)ratio is about 72.5dB can be received in the signal processing circuit of RFOGs.And the processing circuit can realize the detection and demodulation of the signal.By adjusting PI control parameter to stabilize the system,we conduct the simulated rotational rate experiment.The result indicates that the measured values are linearly correlated with the frequency shift of resonance points within certain range.