Research On Signal Processing And Closed-loop Detection Technology Of Fiber Optic Gyroscope

Gyroscope is used to measure the angular velocity of a moving vehicle in the inertial space.It has a wide range of applications in the field of inertial sensing,According to the precision of the gyroscope,the military level of a country can be directly reflected.Therefore,it is of great value to research the fiber optic gyroscope.The interferometric fiber optic gyroscope obtains the inputting angular velocity of a moving vehicle by measuring the Sagnac effect.Compared to electromechanical gyroscope or other types of photoelectric gyroscope,the interferometric fiber optic gyroscope has the advantages of longer service life,higher precision,lower cost and smaller size.This paper mainly studies the stable control technology of light source and digital closed-loop detection technology of the interferometric fiber optic gyroscope.In order to improve the stability of the output signal of the light source in interferometric fiber-optic gyroscope.A circuit to drive the light source is designed in this paper,witch based on the scheme of "constant current source and temperature control".This scheme can effectively control the driving current and temperature of the light source tube core.Thus,the stability of optical power and wavelength of light source are indirectly guaranteed.This paper discussed two detection principles of interference signal in detail.Compared with open-loop detection of the interferometric fiber optic gyroscope,closed-loop detection has broader measuring range and higher detection precision,at the same time,the structure of the system is more simple,It meets the needs of the high precision and miniaturization of fiber optic gyroscope at present.This paper also designed a closed-loop detection circuit,including signal gyroscope at present.This paper also designed a closed-loop detection circuit,including signal detection analog circuit,digital closed-loop detection circuit and feedback drive circuit,the core processing unit in this circuit is FPGA.The signal detection analog circuit realizes the photoelectric conversion and analog-to-digital conversion of light signal.The digital closed-loop detection circuit mainly completes the demodulation of modulating the digital signal,generating the step feedback signal,and outputting the signal information.The feedback drive circuit transforms the step wave signal and bias modulated signal into voltage analog signal to act on the phase modulator.The system realizes the communication between FPGA and host computer through UART.Finally,We have performed a performance test on the light source drive circuit and digital closed-loop detection circuit.Test results are as follows:The light source driving circuit effectively improves the current drift and temperature drift of light source.The maximum deviation of current is within 0.5mA.In the temperature range of-40??60?,the wavelength of the light source is stable at 1310 ?0.3nm,and the stability of light power is less than 7?W.The closed-loop detection circuit can effectively extracts the optical signal of 100KHz,and completes the modulation/demodulation of the signal.At room temperature,the zero drift of the system is 22.154 °/h,the scaling factor is 341.72 bit/°/s,and the nonlinerity of scaling factor is 1109.41ppm.The light source drive circuit and signal detection circuit meet the requirements and achieves the desired effect.