Research On Deadband Analysis And Deadband Supression Method Of High-precision Fiber Optic Gyroscope

The gyroscope acts as a vital component of inertial navigation system plays a crucial roleon it development. The fiber optic gyroscope（FOG）with a series of advantages becomes oneof the main instruments of inertial instruments, such as a small size, a light weight, a low costand so on. Someday the fiber optic gyroscope will replace the traditional mechanicalgyroscope and laser gyroscope. In the project, the gyroscope produces the dead effect thatlead to the output of gyroscope appears serious non-liner, and that indirectly affect the inertialnavigation systems. Therefore it must be to research on the dead band effect, and find outeffective way to improve gyroscope performance. At this paper have based on the laboratoryproject of fiber optical gyroscope AHRS, and from the optical circuit and electrical circuit ofclosed-loop of FOG to analyze the influence of the factors of dead band. It has study thePrinciple of the factors act on dead band, at last use the random over-modulation method toovercome the fiber optical gyroscope dead band. This paper main including some tasks asfollows:1. In-depth analysis of the basic principles of fiber optic gyroscope and key performanceindicators. A brief introduction of the structure of FOG and type of devices. Analysis themethod of detect the interference signal phase of FOG, and analysis of the square-wavemodulation and four-state modulation, and then based on four-state modulation, in depthstudy the theory of the second closed-loop control inhibiting half-wave voltage drift of Ywaveguide.2. In-depth analysis of the main influencing factors that result in dead band effect. Analysisof cross-coupled from the approach, type and size of it. Study the effect of modulationcharacteristic of Y waveguide and analysis of the source of non-liner error. Study the spectralwidth of source impact to light intensity and derive the relationship between the light intensityerror and spectral width under the four-state modulation. Study the parasitical effect that existin optical system of gyroscope and analysis of them impact on the gyroscope output.3. Detailed analysis of the test method and the reason of dead band. In-depth study theinfluence of installation error and zero error on dead band test. And then design optimizationof the threshold test methods to improve the dead band test. Based on the dead band ofinfluencing factors, and use the error signal to establish error model, then summarize thenecessary conditions that cased the dead band. In order provide a theoretical basis to exploreinhibition method of the dead band. 4. At this paper introduce the technique of random over-modulation to overcome the deadband. In-depth analysis of the idea and the theory of random modulation act on the dead band.Then design a pseudo-random modulation module and program of signal processing. Finally,download the program to gyroscope signal processing board and verify the feasibility of thedesign.