Identifying Z-axis gyro drift and scale factor error using azimuth measurement in fiber optic gyroscope single-axis rotation inertial navigation system

In the fiber optic gyroscope (FOG) single-axis rotation inertial navigation system (SRINS), the Z-axis gyro drift (epsilon(z)) dramatically limits its navigation precision and the Z-axis gyro scale factor error (delta K-Gz) can cause greater navigation error because of the rotation process compared with the strap-down inertial navigation system. Hence, identification and compensation for the epsilon(z) and delta K-Gz are important in SRINS. An approach based on the azimuth error model of open-loop algorithm is proposed. This approach considers azimuth angle as a measurement and uses a least recursive square algorithm for identifying the epsilon(z) and delta K-Gz. Compared with the traditional method, which takes velocity and position errors as measurements, the time required for identifying epsilon(z) with the proposed method is only approximately 10 min, while the traditional method requires 6 h to 12 h. Experimental results from an SRINS with FOGs demonstrate that the accuracy of identifying the epsilon(z) reaches 0.002 degrees/h and that of the delta K-Gz reaches 8 ppm in 10 min. The positioning accuracy of the SRINS improves greatly after the identification and compensation. (C) 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)