Reliability analysis of high precision FOG input axis misalignment angle based on FTA

Abstract

Different from the traditional mechanical gyroscope, fiber optic gyroscope (FOG) has the characteristics of fast start-up speed, high precision, small volume, and low cost, which has been widely used in the fields of sea, land, air and so on. With the wide application of FOG, the problem of its reliability has gradually emerged. Among all kinds of reliability problems, the problem of degradation of the input axis misalignment angle of high-precision FOG with the time is particularly prominent. If it cannot be solved as soon as possible, this problem will seriously affect the actual use of highprecision FOG In this paper, a fault tree is established, which takes the degradation of the input axis misalignment angle of high-precision FOG with time as the top event. The physical and chemical factors and manufactucoil process parameters that cause the degradation of the misalignment angle are analyzed. Through the study of the degradation mechanism, it is concluded that the change of the size stability of the fiber coil is one of the main factors that cause the degradation of the misalignment angle with time. Then we design and build a special testing system for the misalignment angle of highprecision FOG. The degradation mechanism of the misalignment angle of high-precision FOG is verified by experiments. The theoretical analysis and experimental results show that the stability of the size of fiber-optic coil changes with time, which will have a very bad impact on the reliability of the misalignment angle of FOG. Finally, through the design and process optimization, the reliability of the misalignment angle of gyro can be improved.