Signal Processing Of White Light Interferometric Fiber-optic Gyroscope

Fiber optic gyro is a kind of angular velocity measuring instrument based on the principle of Sagnac,which has the advantages of anti-electromagnetic interference,no relative moving parts,high sensitivity,flexible measurement mode and long service life.Since its invention,it has been valued by many countries,and after more than thirty years of development,fiber optic gyroscope has been applied to military and civil fields in large quantities,and there is still a huge development space in the future.In this study,a rhombic optical range difference bias structure fiber optic gyroscope is proposed,which uses rhombic optical range difference bias structure to generate optical range difference bias instead of phase modulator of traditional interferometric fiber optic gyroscope,and uses high-speed tunable laser for multi-wavelength phase shift algorithm,which provides an alternative angular velocity measurement solution for the traditional fiber optic gyro field.Due to the high response frequency of this experimental setup,it can also be applied to high frequency angular vibration measurements of spacecraft.The main work of the paper is as follows.Firstly,this paper introduces the development history of gyroscope and the current research and application status at home and abroad,and lays down the idea of building fiber optic gyroscope system in the next chapter by focusing on each component of fiber optic gyro and its working principle,and then improves the stability and accuracy of fiber optic gyro by analyzing the noise existing in fiber optic gyro and designing various approaches to suppress the noise in a targeted way.Secondly,after analyzing the system composition and modulation mode of closed-loop fiber optic gyro,a new diamond-shaped optical range difference bias optical path structure is proposed,which can replace the phase modulator in the traditional interferometric fiber optic gyroscope,by introducing a non-reciprocal optical range difference bias,the fiber optic gyro can produce white light interference spectrum at rest;meanwhile,a common dual wavelength switching modulation and demodulation technique is proposed based on the traditional square wave modulation,which makes the fiber optic gyroscope more stable and accurate.Based on the traditional square wave modulation,a common dual wavelength switching modulation and demodulation technique is proposed,which can greatly improve the sensitivity and demodulation rate of fiber optic gyroscope and reduce the response time.The common dualwavelength switching algorithm is improved to realize the common three-wavelength switching algorithm,which can directly obtain the rotational speed information of the fiber optic gyro,though sacrificing part of the demodulation rate.Finally,this paper introduces the components of the rhombic optical range difference bias structure fiber optic gyro system and the design ideas,including the optical path part and the circuit part,the circuit part includes the hardware part and the software part,the hardware includes: the laser and its driver,analog-to-digital conversion,photoelectric detection,etc.,the software part includes the Verilog program on the FPGA,and the program on the Lab VIEW upper computer,and The experimental verification of angular velocity sensing is carried out for the co-circuit dual-wavelength and tri-wavelength algorithms.