Structure Optimization Design Of Single-axis Fiber Optic Gyroscope Based On Temperature Characteristics

As a new type of inertial device developed in China in twentieth Century,fiber optic gyroscope(FOG)has many advantages,such as no moving rotor,wide dynamic range,long life,strong anti-interference ability and so on,so it is widely used in many fields,such as navigation,aviation,space and so on.At present,the precision of fiber optic gyroscope in China is generally 1%.Which can't meet the needs of its present application of high precision.Temperature is the main factor affecting the accuracy of FOG.Therefore,improving the FOG's temperature performance has become the focus of the research.In this paper,the optimal structure of single-axis fiber optic gyroscope under normal temperature is studied based on the starting time and thermal non-reciprocity error of FOG.It makes the starting time as short as possible and the thermal induced non-reciprocity error as small as possible.First,the theoretical factors that affect the starting time and thermal non-reciprocity error are analyzed.From the principle of conservation of energy and the theory of heat transfer,it is known that the starting time is essentially the problem of heat dissipation in the inner of the gyroscope.Therefore,the purpose of shortening the starting time can be achieved by improving the internal heat source of the gyro to accelerate the heat dissipation of themselves.The mathematical model of the thermotropic non-reciprocal error of the fiber optic gyroscope is established.It is concluded that the temperature gradient and temperature variation within the fiber ring are the factors affecting the temperature of the fiber ring.Therefore,the fundamental way to reduce the thermal non-reciprocal error is to reduce the temperature gradient and the temperature change of each turn of the fiber ring.Secondly,the original physical model of the uniaxial fiber optic gyroscope is established,and the thermal simulation at normal temperature is carried out.According to the simulation results,some specific parts of the gyro structure are analyzed,and the most serious part of the temperature performance of the fiber optic gyroscope is obtained.The physical model includes the structure model and the physical parameters,so the accurate establishment of the physical model requires accurate structure size and accurate physical parameters,including the material of the components of the gyroscope,the heat transfer mode,the heat source power of the heat source,the convection heat transfer coefficient and so on.After that,the physical model type intake is verified by simulation.Time and fiber ringsurface temperature are compared with actual start-up time and measured temperature,and the accurate conclusion of the single axis fiber optic gyroscope's physical model is obtained.According to the thermal simulation results of the physical model,it is concluded that the light source is the most influential heat source on the gyroscope performance.On the basis of the original physical model,different heat transfer conditions are applied to it.It is concluded that the most influential structure of the fiber optic gyroscope is the outer shell and the inner cavity of the gyroscope.The two ones affect the start time and the thermal non reciprocity of the fiber optic gyroscope in the form of heat conduction and heat convection respectively.Furthermore,the influence of the specific characteristics of the fiber optic gyro on the startup time and thermal error is studied.The shape,material,heat transfer coefficient and thickness of the heat source,the inner cavity of the gyroscope,the cushion,the ring groove of the optical fiber and the shell of the gyroscope are studied respectively.The influence of the different structure characteristics on the starting time and the thermal error is obtained.According to this,the fiber ring groove is redesigned.Finally,the structure of the single axis fiber optic gyroscope is redesigned and its performance is verified.According to the analysis of the previous part,the structure of the uniaxial fiber optic gyroscope is designed and simulated.The simulation results demonstrate the superiority of the new structure of the fiber optic gyroscope in shortening the start time and reducing the non reciprocity error.Considering the installation of the components in the actual gyroscope,the new structure is improved and simulated again.The result of the simulation is more obvious in reducing the start time and the thermal error.The results show that the start time and the non reciprocity error of the gyro are greatly improved,the startup time is reduced from 1500 s to 700 s,and the thermal non reciprocal error is reduced from 0.005 /h。to 0.001 /h。.