Fiber Optic Gyro With The Temperature Of Zero Drift And Its Compensation Technology

Fiber-optic gyroscope is a new-style solid inertial device without mechanicalrotator, which gives it wide-spread application in the future. Nowadays the mainbottleneck in domestic research is the strong sensitivity of gyroscope module toenvironmental temperature, and the zero-point drift when temperature changes. In thispaper, the contributions of each part of gyroscope to the zero-point drift is deeplyanalyzed, then a real-time compensation based on an improved optical structure ofY-branch waveguide, and a feedback compensation based on neuron network are takenout and verified. And the zero-point drift of fiber-optic gyroscope under temperaturechange has been compensated well. The main work has been achieved as follows:(1) The basic principle of interferential fiber-optic gyroscope is represented, andthe key role of the Y-branch waveguide in the gyroscope phase modulation is studied;using the nonlinear optics theory under classic condition, the formula about howrefraction index of LiNbO3acts under changing temperature has been figured out, thenthe law on the extra phase drift under changing temperature is obtained; the contributionof other parts of gyroscope in its zero-point drift is also discussed, which shows that theY-branch waveguide is the main reason for fiber-optic gyroscope zero-point drift.(2) An improved optical structure is designed to compensate the extra phase drift ofY-branch waveguide. A new positive temperature coefficient thermistor fixed into thestructure of Y-branch waveguide will experience the same temperature change as theoriginal LiNbO3crystal, which ensures that the extra optical path difference caused bythe refraction index change under temperature is effectively counterbalanced, thus thezero-point of the fiber optic gyroscope holds steady while the environmentaltemperature changes rapidly.(3) The improved BP Neuron Network based on Chebyshev chaos sequence isdesigned. Improve BP Neuron Network on its easily dropping in partly minimum by Chebyshev chaos sequence. By using this improved BP Neuron Network, gyroscope’szero-point drift is modeled and compensated.(4) The serial port communication software fitting to fiber-optic gyroscope isdeveloped using C++builder. This software is used for output test of fiber-opticgyroscope under the changing temperature; the BP Neuron Network software isdeveloped using Visual C#and the two kinds of compensations is verified; theexperimental results show that, both the improved optical structure of Y-branchwaveguide and the improved BP Neuron Network can compensate the zero-point driftof fiber-optic gyroscope when temperature changes. The scale factory stability offiber-optic gyroscope increases by one order of magnitude. Thus, the thermalperformance, reliability and the applicability to tough environment of fiber-opticgyroscope system have been improved.