Effect of Temperature Sensitivity of Coating adhesive on Thermal Induced Non-reciprocal Bias in Fiber Optic Gyroscopes

Abstract

As a new all-solid-state instrument, fiber optic gyroscope (FOG) is increasingly used as a core component of inertial measurement unit because of its high stability, low cost, impact resistance and good dynamic performance. As the sensitive component in FOG, fiber optic coil is very susceptible to transient temperature gradient, which becomes a key factor that restricts the development and precision of FOG. The non-reciprocity error of the fiber coil caused directly by the temperature gradient has been studied by many researchers. While the non-reciprocity error caused by thermal stress is rarely concerned. Studies have shown that proper winding pattern and good winding quality can greatly reduce the Shupe error of the fiber coil. However, the phenomenon that the Shupe error peaks at different temperature points are different in size is confused, even under the same temperature gradient. In the process of derivation of the thermal stress Shupe error model, the thermal stress induced Shupe error is the main cause of the difference in the peak of the FOG at different temperature points.By studying the influence of material parameters of coating adhesive in the fiber coil on FOG, the purpose of improving the performance of the fiber optic gyroscope can be achieved. Based on the mathematical model of Shupe error, the non-reciprocity error of the FOG caused by thermal stress is analyzed. The distribution of thermal stress of fiber coil with different coating adhesive parameters (Young’s modulus and thermal expansion coefficient) was obtained by ANSYS finite element analysis software. The influence of temperature sensitivity of coating adhesive parameters on thermal stress of FOG and Shupe error was studied. The simulation results show that both the Young’s modulus and the thermal expansion coefficient of the coating adhesive affect the magnitude and uniformity of the thermal stress induced Shupe error, but the degree and mode of influence are different. The absolute value of the thermal expansion coefficient and the gradient over temperature will directly affect the non-uniformity of the thermal stress induced Shupe error. In general, the gradient of the thermal expansion coefficient with temperature lead to a negative correlation trend with the peak value of the Shupe error. While, the temperature sensitivity of the Young’s modulus also indirectly affect the non-uniformity of Shupe error. When the coefficient of thermal expansion changes rapidly with temperature, the changing Young’s modulus will intensify the non-uniformity of Shupe error. By studying material parameters of coating adhesive, the variation law of Shupe error can be obtained and it is possible to optimize coating adhesive selection principle of coating adhesive and reduce the non-uniformity of thermal induced non-reciprocal bias, which is of great significance in the application of FOG. Finally, the coating adhesive of fiber coil with suitable material parameters was selected by the selection principle of coating adhesive obtained in this paper.