The Influence of Fiber-Optic Circuit's Laying Defects on the Gyro’s Thermal Drift
DOI:
https://doi.org/10.22213/2413-1172-2018-2-185-190Keywords:
fiber optical gyro, thermal drift, Sagnac effect, direct numerical modeling, laying of optical fiber, defectsAbstract
The approach that uses direct numerical simulation to estimate the value of the thermal drift of a fiber-optic gyroscope under the action of external forces fails to provide computational data consistent with experiment. One of the reasons is the presence of random defects associated with a violation of the regularity of optical fiber turns wrapped on the fiber optic gyro coil. The purpose of this study is to assess the influence of optical fiber winding defects on the gyroscope readings under external non-stationary thermal loads. The paper introduces the mathematical and computer models for calculating the thermal drift of a fiber-optic gyroscope and considers the details of the computational technique. The main feature of the proposed model is solving a thermal elasticity problem for a regular micro-inhomogeneous medium of optical fiber winding within the structure of a gyroscope. The data of processing the field information on the thermal and stress-strain states of the optical fiber turns are used to solve the piezo-optical problem with the aim to calculate the thermally induced “apparent” angular velocity. The thermal drift of the gyroscope calculated for the ambient temperature ranging from + 20 to + 60 °C for an ideal fiber coil with a defect-free winding is compared with the results of numerical drift simulation taking into account typical defects encountered in practice. The paper presents a description of each defect including information on its location in the fiber array, as well as an explanation of the reasons for a drift change. The obtained results of calculation provide convincing evidence for a multiple increase in the thermal drift of the gyroscope even in the case of considering the single defects in the optical fiber winding. Therefore it is obvious that in order to increase the accuracy and reliability of the navigation device it is necessary to meet the requirement of strict control of the technology of fiber winding on the gyro sensor coil.References
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