Based on the Sagnac effect, the small changes in thermally induced stresses and microcosmic size of optical fiber coil can cause the drift of the Shupe error and scale factor of fiber optic gyroscope (FOG). As polymer functional resin represents a high proportion in optical fiber coil, its physical and chemical properties determine largely the thermally induced stresses and dimensional stability of the coil, thus influencing the performance of FOG. Given the demands for the long-term stability and temperature characteristics of FOG, this paper studies the influence of molecular chain structure and thermal conductivity of polymer functional resin for optical fiber sensing on FOG. The experimental results suggest: high thermal conductivity can reduce the thermal induced stresses of polymer functional resin of reticular molecular structure, greatly improving the zero bias stability of FOG at all temperature; hyperbranched molecular structure reports outstanding creep-resistant characteristics thanks to the significantly reduced internal free volume of optical fiber coil after encapsulation and insignificant dimensional changes at all temperatures, thus ensuring long-term stability of the scale factor of FOG.
On the base of an analyzing system, we demonstrate a testing method to reveal whether the FOG scale factor is stability after a long term ageing. The temperature of the chamber is set to 85°C in order to accelerate ageing of the adhesive. The FOG scale factor data is sampled each month. Results show that the MTTF (Mean Time to Failure) of the FOG coils is not satisfied with the application need. The analyzing system has good application prospects in testing the instabilities of the FOG’s Scale Factor.
Fiber optic gyroscope (FOG) is a multi-technology product which integrates optics, mechanics and electricity. It has the advantages of high reliability, long life, light weight, small size and "all solid state". It has been widely used in military and civil fields such as sea, land, air, sky and submarine, and has become the mainstream gyroscope in the field of inertial technology. With the widespread application of FOG, the degradation of its key performance indicators gradually emerges as time goes on. Therefore, it is urgent to obtain the reliability index of FOG. In order to obtain reliable reliability index of FOG with time and cost saving as much as possible, it is necessary to choose reasonable acceleration test method, acceleration model and life distribution model to study the acceleration life model of high precision FOG. To this end, this paper carries out the following aspects of work: (1) The basic composition and main reliability index of high precision fiber optic gyroscope are introduced. (2) The sensitive stress of high-precision FOG is temperature and humidity. A high-precision FOG acceleration model based on temperature-humidity double-stress Peck model is established for the first time. (3) The life distribution model based on drift Brownian motion is analyzed, and the applicability of the life distribution model is determined by Monte Carlo simulation combined with the acceleration model of Peck model. (4) According to the performance degradation data of accelerated life test of FOG, the reliability of life distribution model of high precision FOG is evaluated.
The improvement in the performance of fiber optic gyroscope raises increasingly high standard on the performance of potting adhesive for optical fiber coil. It cannot only enable the stability of coil potting, but also maintain long-term stability under complex environmental stress. In order to meet the indicators of temperature performance of optical fiber coil, we have prepared the acrylic matrix potting adhesive via UV photo-curing by grafting the hard-segment chain containing benzene ring with polyurethane acrylate(PUA) as the matrix, studied the influence of resin matrix, photoinitiator and active diluent on the UV curing of potting adhesive for optical fiber coil, and went into in details the indicators including the curing rate, modulus and glass transition temperature performance of potting adhesive so as to provide experimental support for obtaining the best matched UV potting adhesive curing system. In this study, we have characterized the molecular structure of potting adhesive via infrared spectroscopy, studied the thermomechanical properties of potting adhesive by thermal analysis, and finally verified the process stability of potting adhesive and the temperature characteristics of coil through coil winding and potting and curing.
The fiber optic gyroscope has become to one of the most important sensors in developing due to light in quality, high accuracy, compact in dimension and long life[1-4]． These features have developed new applications of the gyroscope not only in conventional aerospace application area but also in industrial application area, such as control and navigations of unmanned vehicles, antenna/camera stabilizers, and so on. More and more FOGs have been applied in all kinds of satellites for attitude control. With the great technology progress on fiber optic gyroscopes in recent years, the reliability of fiber optic gyroscopes has been focused on. The fiber coil, as one of the most critical components in fiber optic gyroscope，its reliability directly determines the reliability of the fiber optic gyro. This paper uses the Bayesian estimation method to study the reliability of the fiber coil. Aiming fiber optic gyroscope fiber coil Failure Data Reliability analysis of the problem, on the basis of analyzing the failure mode, select Weibull distribution as its life mode, the estimated time of each detection without failure data using Bayesian theory failure rate, and thus the estimated model parameters fiber coil reliability. The Bayesian estimation method combined with experience information greatly reduces the number of test samples, and to overcome the shortcomings of the traditional reliability evaluation method relies on failure data, has a high value in engineering applications. This estimation method shows its significance in saving test costs and time.
The fiber optic gyroscope (FOG) has become to one of the most important sensors in developing due to light in quality, high accuracy, compact in dimension and long life. These features have developed new applications of the gyroscope not only in conventional aerospace application area but also in industrial aerospace, such as control and navigations of unmanned vehicles, antenna/camera stabilizers, and so on. Fiber coil is the core of fiber optic gyroscope. The accuracy of fiber optic gyroscope depends on the temperature performance of fiber coil.
In this paper, the temperature transient error model was built based on discrete mathematics model of SHUPE error in the Fiber optic gyroscope and the element physical model of the fiber coil. Based on the temperature distribution model mentioned above, the effects of the coil with different winding method and different geometric dimensions on the temperature performance of FOG were simulated under the same temperature condition. Theoretical analysis and experimental results showed by optimizing the design of the fiber coil, the temperature error of fiber coil can be reduced obviously.