Research On Temperature Characteristic Of Fiber Optic Gyroscope Scale Factor

The fiber optic gyroscope(FOG)is widely used in fields of aviation,aerospace,navigation and weapons for their advantages of high dynamic,all-solid,small size,light weight and long lifetime.With the improvement of FOG engineering technology,temperature has become one of the main problems affecting the accuracy of FOG.FOG's main components are sensitive to temperature,so the scale factor error caused by the different temperature directly affects accuracy of the FOG.The existing fiber optic gyro scale factor error model is only considered as a whole,and there is no analyzes in the temperature characteristics of the internal components of the fiber optic gyroscope.The paper takes the interferometric fiber optic gyroscope as research object,and expounds its working principle and main performance index based on Sagnac effect.Through temperature characteristic and mechanism of FOG,get the main factors causing the FOG's scale factor error.The paper focuses on the average wavelength of light source,the thickness of fiber and the frequency of crystal oscillator at different temperature points.The following research works are carried out in this paper:Firstly,based on ANSYS finite element simulation and the principle of heat transfer,the heat transfer model of the fiber ring wound by different thickness of fiber is established,and the fiber ring of different sizes and the local heat of the fiber ring are combined to explore scale factor error model of the fiber ring about temperature change at full temperature range.Studies have shown that the thinner and thinner coating fibers have less influence on scale factor.And scale factor variation is linear with the temperature of each side of the fiber ring.In addition,for the problem that the influence model of the crystal frequency on the scale factor error is uncertain in the full temperature range,by analyzing the basic principle of the digital closed-loop fiber optic gyroscope,combined with the influence of temperature on the crystal frequency and the method of measuring the scale factor of the angular increment.The function model of crystal frequency,temperature and scale factor is established,and its correctness is verified by experiments.In order to improve the stability of the scale factor,another temperature-compensated crystal oscillator was experimented,which was compared with the ordinary crystal oscillator in the full temperature range.It was found that the temperature-compensated crystal oscillator has better temperature stability and can reduce the influence of crystal frequency to scale factor and increases the stability of the scale factor.After that,according to the evaluation of light source and the theoretical analysis of the influence of the light source on the scale factor,combined with model of the average wavelength of the light source on the scale factor.It is found that the scale factor error of theclosed-loop fiber optic gyroscope is proportional to the relative change of the average wavelength of the light source.The average wavelength variation of the SLD source and the erbium-doped fiber source in the full temperature range was compared and the influence of the average wavelength of the two sources on the scale factor in the full temperature range was calculated.It is concluded that the SLD light source is suitable for use in medium and low precision fiber optic gyroscopes,and the erbium-doped fiber source is suitable for use in high precision fiber optic gyroscopes.Finally,scale factor variation of FOG in the full temperature range was tested,and the correctness of scale factor error caused by fiber ring,crystal oscillator and light source was verified.The compensation model of scale factor temperature error is established.And through re-writing the established compensation model into the same FOG,the correctness of the proposed model is testified.