Research For FOG Digital Signal Filtering And Dynamic Error Compensation

Fiber optic gyroscope(FOG) is an inertial navigation system equitment which is based on the Signac effect, and it is widely applied in measuring the angular acceleration of the carrier,its prospects got a lot of attentions in recent years. At home and abroad, lots of researches on the high performance FOG are reported, the scale factor and random walk coefficient are the main performance indicates. With the development of inertial navigation system, the output accuracy of the dynamic performance becomes more and more important. In order to optimize these problems, this paper based on the research of interferometry fiber optic gyroscope,analyzed the deviation mechanism and the digital signal filtering in the dynamic condition of FOG, compensated the deviation, and handed the the demodulated signal with wave filter. The following are the main work of this paper.Firstly, this paper elaborated the basic principles of digital closed loop control FOG and established the mathematical model of interferometry fiber optic gyroscope digital closed loop system. In the actual operation situation, rolling is very common, so this paper analysed the deviation factors when the FOG in rolling motion in theory, tested the system time-delay with laboratory methods, and got the signal time-delay by imposing slope-shaped excitation.For the requirement of digital signal processing frequency, it illustrated time delay will cause certain influences to the output.Secondly, designed relevant compensation for system time delay, and analyzed the first-order phase locked loop algorithm's compensation to the deviation. Cause that this algorithm would be restricted by roll variation, this paper presented the phase shift delay compensation algorithm which based on frequency point, it can compensate the system diviation while satisfying the dynamic range of the carrier. According to actual operating environment of the carrier, through simulating different dynamic excitation, this paper compared the system deviation, found that the system deviation was decresed with the compensation, and validated this algorithm could improve the dynamic performance of FOG.Lastly, while handing with the digital signals, the angular speed signals should be filtered,but the wave filter may cause hysteresis, and its order will have some influence on the time delay. So this paper used distributed algorithm which would not be influenced by the order to filter waves, and considering the FPGA inner resources, this paper programed VHDL to realize those functions and verify those functions through Modelsim simulations.