Research On Large Dynamic Measurement Technology Of Interferometric Closed Loop Fiber Optic Gyroscope

Fiber optic gyroscope,an angular velocity measurement device,is an important part of inertial navigation system.Compared with other angular velocity measurement devices,fiber optic gyroscope has obvious advantages: no rotating parts,short response time,long service life.It plays an important role in many military and civil fields as well as social development and national life.With the deepening of the research,the accuracy of the domestic mainstream FOG has reached the application precision.More and more fields require that FOG has both high precision and large dynamic measurement range.However,high-precision and dynamic are contradictory indicators.The existing solutions mainly use an auxiliary equipment which has large dynamic range to expand the measurement range,but it costs too much.This paper presents an improved single-stage interference fringe expansion method,which can realize the large dynamic measurement of fiber optic gyroscope without any auxiliary measurement equipment,while maintaining high precision.The main work of this thesis is as follows:Firstly,this article explains the reasons for the research of large dynamic measurement technology of fiber optic gyroscope and the significance of doing this work to the related research of the laboratory.According to the development of technology and time frame combing the research progress and research methods in the field of fiber optic gyroscope large dynamic measurement.Combined with a laboratory digital closed-loop optical fiber gyroscope system implementation method,establishing FOG system for dynamic mathematical model in accordance with the order of digital closed-loop feedback system.After getting the transfer function of the whole digital closed-loop FOG system,analyzing the influence of different input signals on the tracking characteristics of closed-loop FOG system.Secondly,analyzing the dynamic measurement range of a type of closed-loop FOG.The reason of the multi-value of the FOG system is analyzed by simulation.The response characteristics of the system are analyzed in the state of large dynamic input,and the reasons that affect system sensitivity are analyzed.Based on the above analysis,an improved single-stage interference fringe expansion scheme is proposed to realize the large dynamic measurement of FOG without affecting the system resolution.Thirdly,the FPGA implementation scheme to improve single-stage interference fringe expansion method is designed.The modules of single fringe expansion scheme are written by Verilog hardware description language,and the data communication module is designed.The top testbench test file is designed and simulated in modelsim software.Finally,the experimental scheme is tested by using the equivalent input principle.The test module is added into the FPGA implementation scheme of the improved single-stage interference fringe expansion method,and the program is downloaded to the hardware circuit through ise software after it synthesized,placement and routed,and pin assignment.After the system is running the data is received by a software.The data processed by MATLAB M file and the Allan variance analysis.The results show that this method can effectively measure the large dynamic range of fiber optic gyroscope and maintain the high precision of the system.