Research On The Suppressive Method Of The Dead Band Of Fiber Optic Gyroscope

With the development of new technology,Optical gyro has become one of the most important research in the 21 st century and the development of gyro was very rapid.As an important part of optical gyroscope,fiber optic gyro(FOG)was becoming more and more mature,and it has been applied in aerospace,navigation,military and civilian fields.However,due to the existence of various errors inside the fiber optic gyroscope,the non-ideal type technology and the limit of the current technology,fiber optic gyroscope was not sensitive to the angular velocity near zero input,that was called dead band phenomenon.Which greatly affected the function of fiber optic gyroscope,so the appropriate method must be used to suppress the dead band of fiber optic gyroscope.Based on the existing fiber optic gyroscope in the laboratory,the basic principle of fiber optic gyroscope was grasped.Based on this,the mechanism of the dead zone of FOG was analyzed,and the appropriate method was selected according to the dead zone generation mechanism.Accordingly,a dead-zone suppression of the fiber optic gyroscope called random over-modulation was performed in a manner.Its main work was as follows:1 The basic working principle of fiber optic gyroscope was analyzed,and all-digital closed-loop insistence scheme of FOG was introduced,including four-state square wave modulation and second closed-loop control.The part of digital signal processing of the fiber optic gyroscope was mainly realized in the FPGA chip,which mainly realized the modulation and demodulation of the signal,the generation of the step wave,the second closed-loop control and the serial data output.By analyzing the basic working principle of fiber optic gyroscope,the existing situation of FOG was analyzed,which provided a theoretical basis for the follow-up dead-band analysis and improvement of FOG closed-loop control.2 The dead-zone mechanism of fiber optic gyroscope was analyzed.It was shown that the dead-band generation mechanism of fiber-optic gyroscope has two kinds: the dead-band error caused by electronic crosstalk and the nonlinearity of feedback loop device.Then,based on the dead-zone mechanism,several schemes for suppressing the dead-band of FOG were compared and analyzed.Finally,a random over-modulation scheme was selected to suppress the dead-band of FOG.3 The dead-band test of fiber-optic gyroscope,as a measure of the size of the dead zone,the threshold test was the test of the dead zone,which could provide the size of the dead zone,the success of the subsequent improvement provided a theoretical support.It was mainlybased on the national military standard test,the errors of the national standard test were analyzed,and the error was compensated accordingly,and ultimately completed the test task.4 The implementation of random over-modulation of FOG,this part was the most important and the core of the whole design.It mainly completed the design task of pseudo-random module design,modulation and demodulation using VHDL,and finally carried on the function simulation to the whole FPGA chip,timing simulation,and completed the board debugging.The final,new threshold was test,the two threshold test results were compared.