Research On Mechanical Jitter Control Technology Of Laser Gyroscope Based On FPG

As a high precision inertial navigation device,mechanical dither laser gyro is widely used in aerospace and other fields.With the development of inertia technology,it is found in engineering practice that there are still many problems in the research of mechanical dither laser gyro in the distribution of dynamic lock-in region and the process of eliminating dynamic lock-in region by random noise.This paper focuses on the deep error mechanism of dithering offset frequency,dithering frequency and adding noise in eliminating the locking area of mechanical dithering gyro.The specific research contents are as follows:1.The working principle of mechanical dither laser gyro is analyzed theoretically,and the simulation model of mechanical dither laser gyro is built based on Simulink.The dynamic lock in region under different dither offset frequency,dither frequency,dither mode and dither depth was quantitatively analyzed,and the optimal mechanical dither configuration parameters of laser gyro were obtained by adopting the m sequence of dither depth of 1%,dither frequency of 337 Hz,and dither offset frequency of100 KHz.2.In view of the problem that the dynamic locking zone of dithered laser gyro increases significantly when the input angular velocity is close to the maximum dithering angular velocity,based on the actual gyro parameters and the lock in zone equation,the dynamic lock in error distribution characteristics of the input angular velocity when the dithering Angle frequency is integer multiple are studied.The relationship between dynamic locking region and dither offset frequency,dither frequency and noise depth is obtained.The results show that increasing the noise injection depth can reduce the dynamic lock-in region when the input angular velocity is close to the maximum angular velocity of dither laser gyro.3.The mechanical dither control system of laser gyro is designed based on FPGA.The system includes pulse width modulation(PWM),digital phase-locked loop(PLL),random noise injection,frequency offset control,dithering drive,dithering feedback detection and other circuits to realize the generation of dithering drive control signal and control of dithering frequency offset.The jitter driving circuit uses a single power supply instead of the traditional double power supply,and the jitter driving signal is generated by two completely symmetrical and equal circuits.4.The experimental platform of mechanical dither laser gyro was built.According to the National military standard GJB2427-1995,the type 90 mechanical dither laser gyro was tested in high and low temperature environment,and the zero bias stability,dither frequency tracking accuracy and random walk error of the gyro were obtained.The experimental results show that the jitter control system designed in this paper can ensure that the gyro does not lose lock and the tracking error of the jitter frequency is less than 0.02 Hz in the variable temperature environment.At the same time,the precision of the gyro is improved by 5% compared with the original self-excited oscillation control system at different temperatures.