A control method based on Smith estimator applied in closed-loop I-FOG

With the rapid development of I-FOG, high precision I-FOG is becoming an urgent demand in strategic submarine, navigation and armed vehicles. This paper focuses on the closed-loop control method design. A direct way to improve the precision of I-FOG is to increase the length of fiber. However, the enhanced Sagnac effect brings a longer transition period. If the demodulation frequency of I-FOG is at base frequency, it will cause longer sampling period, narrow bandwidth and small dynamic range. Especially in high dynamic environment, closed-loop feedback can not compensate high frequency noise effectively and increases the dynamic error. An enhanced control method with Smith estimator is presented to solve these critical defects. With the help of Smith estimator, the delay caused by odd times frequency modulation is figured out. Further, the dynamic performance and noise-restrain capability are highly improved.

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