Gao Yanbin

Research on Intensity Noise Suppression for Closed Loop FOG

The main factor of random walk in a high precision fiber optic gyroscope is the intensity noise using erbium-doped fiber source, so decrease the intensity noise can reduce random walk. An intensity noise suppression method is proposed to reduce the random walk. An approach to reduce the random walk using subtraction combined with depolarizer was advanced after analyzing the relation of light intensity, phase and degree of polarization between two light beams. Analyze the gyroscope output data with Allan variance and we could determine from the result that the random walk coefficient was reduced by 32% than before.

Low Cost Method for FOG Eigenfrequency Measurement

A low-cost approach was advanced to solve the problem of measuring fiber optic gyroscope (FOG) eigen frequency. Based on the principles of square wave modulation and demodulation in digital closed-loop FOG, the modulation of phase modulator had been done using fourfold eigen frequency square wave. Analysis of the demodulated signal obtained the relation between photoelectric detector output wave pattern and the frequency of modulation square wave, so the problem of eigen frequency measuring was transformed into the problem of pulse measuring and the complex programming software and expensive measuring devices was avoided. Experimental results show that the accuracy could be up to 0.075KHz when FOG eigen frequency was measured manually using this method.

Transfer Alignment Algorithm Based on Attitude Information

Two kinds of transfer alignment algorithms based on attitude information were proposed, which were attitude angle matching algorithm and attitude matrix matching algorithm. Simulations were done for comparing estimation performance of the two algorithms when velocity maneuvers and wing-rock maneuvers. The simulations results show the later algorithm is superior to the former in accuracy whichever maneuvers. However, the later algorithm would invalid in case of some certain maneuvers, so this paper firstly proposes selection method of measure variables of the later algorithm, and presents three sets of effective choices.