Research On Digital Closed Loop Technology Of Interferometric Fiber Optic Gyroscope

The fiber optic gyroscope is a new generation of inertial instrument,it can be sensitive to the rotational angular velocity of the carrier relative to the inertial space,and it is an important part of the inertial navigation system.In theory,it is a kind of all solid state inertial device with simple structure and high precision.But due to unreasonable design of the schematic diagram of the current gyro board,the PCB layout and wiring is not standard and the signal demodulation modulation timing is not strict,which causes the shortcomings of the low precision and the instability of the control performance of the existing gyro board.Therefore,it is necessary to redesign the existing gyroscope.This paper redesigns the schematic diagram and PCB of the circuit part of the fiber optic gyroscope,and using the Verilog language to designed and simulated the gyroscope,proposed and implemented the gyro angle increment output,completed the actual test of the overall performance of the designed gyro board.With the deep research on the interference of digital close loop fiber optic gyroscope technology.Firstly,according to the working principle of the interferometric fiber optic gyroscope,determined the design of the general control scheme.According to the flow and characteristics of the signal,the function of the circuit is put forward and the selection of the device model is preliminarily established.Complete the circuit design scheme of gyroscope.In view of the complexity and importance of the front end signal,the paper detailed analysis research on gyro front-end detection circuit,designed a high performance filter amplifier with low noise.By reading the manual data to complete the A/D and its driving circuit.Complete the selection and configuration of FPGA circuit.The back end circuit of the gyro board has designed the D/A conversion circuit,increase the gyro board serial communication function,and the simulation principle diagram modeling is completed,to prove the correctness of the principle diagram.The rules of designing PCB and the problems of EMI and EMC are analyzed,the PCB is layered and distributed,and the PCB design of the four layer gyro board is completed.Secondly,the FPGA realization of the digital closed loop system of fiber optic gyroscope is completed.Given the overall thought of realizing the closed-loop system of FPGA.The design is divided into several separate functional modules,using Verilog language to complete the realization of the two digital closed loop.Complete signal modulation / demodulation,demodulating the number of open-loop digits and gain error numbers,generate modulation wave digits.Integral of open loop digital signal to generate phase step wave,again,generation of digital integral step wave,complete the step wave and modulating wave digital superposition.Through the serial port output digital quantity and phase step angle increment.Modelsim is used to simulate the digital implementation of each functional module and the whole closed loop system,verifying the accuracy of FPGA implementation.Finally,the actual function of the designed gyroscope is verified.Verification the designed PCB function on board level,using Verilog to write the implementation code of the hardware on board D/A,serial port and so on,using an oscilloscope to observe the output of the waveform to illustrate the accuracy of the hardware and code.Based on the method of equivalent input,the performance of the modulation scheme of the designed gyro board and FPGA is tested.The output data of the gyro board are analyzed after the equivalent excitation signal is added,and the control and tracking ability of the gyro board is obtained.Based on the actual test of the single axis turntable,labview admissions the dynamic data of the turntable and the gyroscope,then compare the actual output data of the two,completed the actual dynamic performance test of the gyro board,give the bandwidth and other performance parameters of the design of the gyroscope.