Study On Temperature Compensation Of Laser Gyroscope With Total Reflection Prisms

Laser gyroscope is the key component of inertial navigation system,which has the advantages as quick start,low loss,and high precision.It has played an important role in the fields of aviation,aerospace and missile guidance.The ring optical path is formed by four total reflection prisms in the prisms laser gyroscope,which has the advantages such as small backscatter and non-coating.However,the optical path of this gyroscope has a long transmission distance in the prisms,and the optical stability is easily affected by temperature changes.In addition,in order to avoid the prisms stress birefringence effect brought by using the traditional piezoelectric ceramic push-pull mirrors to stabilize frequency,the heater is used to achieve frequency stabilization control of the gyroscope by controlling the refractive-index of a section of gas in the resonator.However,in a temperature-varying environment,the bias stability of the prisms laser gyroscope is affected by the thermal relaxation in the process of external heat introduced into the cavity,the self-heating of the gyro,and changes in physical and geometric characteristics over temperature.In this thesis,according to the temperature characteristics of the prisms laser gyroscope,the tempeature compensation is studied form the internal frequency stabilization control parameters temperature compensation is studied from the internal frequency stabilization control parameters of the laser gyroscope and the overall bias of the laser gyroscope over temperature,respectively.The main contents of the thesis include as follows:First,the working principle and error theory of the laser gyroscope are introduced.The structural characteristics of the prisms laser gyroscope are mainly introduced,and the temperature characteristics of this gyroscope are analyzed.Second,based on the characteristics of thermal relaxation in the process of the prisms laser gyroscope stabilized frequency,a finite element analysis method is used to construct an analysis model.The distribution of the gas temperature field in the frequency-stabilizing channel of the gyroscope under the condition of changing ambient temperature is simulated,and the infl uence of thermal relaxation on the frequency-stabilizing operation is summarized.Third,according to the principle of frequency stabilization control,a temperature compensation correction term is added to the frequency stabilization control,and the thermal relaxation model is combined with the optical principle for analysis.Eventually,the thermal relaxation is attributed to the mode-jumping voltage.The temperature(-40??70?)is divided into 11 segments,and each segment is separated by 10?.Then,the gyroscope is subjected to frequency stabilization control in different temperature ranges and parameters.The experiments show that the bias stability of the prisms laser gyroscope has been improved to some extent.Fourth,when performing bias temperature compensation on the entire gyroscope,in order to solve the non-linearity of the gyroscope output pulse curve in the fitting process and to ensure the adaptability of the model to the environment,a piecewise least square method with overlap is proposed after comparing least squares,stepwise regression,spline interpolation and neural network modeling method.In addition,the temperature derivative term and temperature derivative cross term are introduced on the basis of static temperature compensation to meet the requirements of complex variable temperature environment.Fifth,after the temperature change test of the gyroscope,the accuracy of the two methods of piecewise least squares with or without overlap is analyzed.The gyroscope accuracy of using overlap is significantly increased.On this basis,the gyroscope accuracy of the uncompensated,static temperature compensation and composite temperature compensation is studied.Eventually,it is concluded that the composite temperature compensation model and the piecewise least squares method with overlap used in the parameters identification process are better to adapt the changing temperature environment,and the accuracy of the gyroscope is significantly improved.