Compared with laser gyro, the scale factor performance of high-precision FOG(HPFOG) restricts its application to high-precision and strategic applications. According to the characteristics of HPFOG with well temperature sensitivity and poor nonlinearity, In this paper, the temperature error model of fiber optic loop and the scale factor error output curve of gyro at different angular rates of each temperature point are analyzed. An optical fiber temperature sensor embedded in the optical fiber loop is proposed to accurately measure the temperature of the optical fiber loop. Compared with the existing single point or multi-point external temperature model, the model can accurately measure the internal temperature field of the optical fiber loop, and establish a reliable Shupe error model of the optical fiber loop temperature. A hybrid model is established by introducing the input angular rate information of gyroscope into the model, and the multi coefficient scale error is compensated according to the model. The experimental results show that the scale factor of HPFOG is greatly improved after compensation based on the accurate error model, and the performance index of the scale factor of HPFOG is effectively improved.
We propose an optical gyrocompass using a three-axis Fiber Optic Gyroscope (FOG) that is the technological heart of the optical gyrocompass. The core of the optical gyrocompass is a compact strap-down Inertial Measurement Unit (IMU), which contains a three-axis FOG, three accelerometers, and a real-time computer that is responsible for computing all the necessary data for demanding navigation. Thermal design is performed to manage heat conduction and quickly balance inner temperature of the optical gyrocompass for suppressing the thermally induced error, and then the uniform temperature environment is obtained for three-axis FOG. The long-endurance sea trial experiment result proves that the dynamic accuracy of the optical gyrocompass is lower than ±0.25° secant latitude, and it is capable of navigating in high latitude region. The optical gyrocompass is also certified to meet the requirements of the International Maritime Organization (IMO) for gyrocompasses.