Vibration error suppression technique for a fiber optic gyroscope based on partial demodulation and feedback in advance

The performance of a fiber optic gyroscope (FOG) changes under vibration, it is called a vibration error, thus it is necessary to suppress the error for the usage of FOG. Here, the effects of the feedback delay existing in the fully digitalized closed-loop of a FOG on its closed-loop tracking performance were ananlyzed. The formation mechanism of vibration error was revealed, it was shown that the disturbances brought by vibration environment cannot be suppressed efficiently, so the additional phase errors are introduced. In order to suppress the errors, a method named partial demodulation and feedback in advance was proposed considering the stability of the closed-loop. The additional phase errors were analyzed with different proportions of feedback in advance theoretically and numerically, and the additional phases with different proportions of feedback in advance and the outputs of FOG were measured on a vibration testing table. The results showed that the vibration errors and the additional phase errors decrease simultaneously with increase in the proportion of feedback in advance; the method of partial demodulation and feedback in advance is suitable for different demodulations and it can improve the adaptability of FOG to vibration environment without modifying its hardware designs including structural design and light path design.