Research On Temperature Control And Compensation Of Digital Closed-Loop Fiber Optic Gyroscope

Fiber optic gyroscope (FOG) is a novel type of solid-state inertial instrumentbased on optical Sagnac effect. Compare to traditional gyroscopes, it has someparticular advantages such as higher precision, stronger impact resistance, smallersize, lower power consumption et al. In recent years, with the development ofintegrated optical devices and fiber optic technologies, FOG has broad prospectors inmany application fields. But due to a large number of optical devices in FOG, it issensitive to temperature disturbance, and this is one of reasons limiting engineeringapplication of high precision FOG. According to temperature control andcompensation, this paper is focused on inhibiting temperature performance of opticalsource and Y waveguide phase modulator in interferometric closed-loop fiber-opticgyroscope (IFOG). The research contents mainly include:1. To illustrate the influence of temperature on IFOG, the instructor andworking principle of IFOG is presented; then the temperature characteristic of everyoptical component is further studied; finally, some feasible schemes of inhibitingFOG’s temperature sensitivity are discussed.2. According to the temperature characteristic of FOG’s SLD optical source,choose temperature control system to stable the working temperature of SLD in acertain range. The design of SLD temperature control system is discussed in detail,the mathematic model of the system is established and simulated, and the influenceof every PID parameter on the system output is obtained. Finally, the temperaturecontrol system is tested in all temperature range, and the tested data is analyzed.3. Through analyzing the influence of Y waveguide phase modulator onclosed-loop IFOG in a varying temperature environment, use temperaturecompensation technology to modify the modulating volta ge applied on the Ywaveguide phase modulator. The efficiency of compensating the modulating voltageis low with the square wave modulation. In order to solve this defect, the four-state modulation IFOG is proposed. The demodulation of rove information andmodulating phase error is presented in detail. Meanwhile, the second closed-loop isintroduced to modify the gain factor of the first closed-loop. Via establishing themathematic of four-state modulation IFOG, the simulations of square wavemodulation and four-state modulation are analyzed and compared. The four-statemodulation IFOG is realized in laboratory, and some primitive verified results areobtained.