Researches On Error Mechanism And Modeling Methods Of Laser Gyro Strapdown Inertial System In Thermal Circumstances

Laser gyro is an optical sensor which was invented and developed by military requirements. It works on the effect of Sagnac and is the ideal device of Strapdown Inertial Navigation System (SINS). So it is widely used in the areas of aviation, position finding, guided missile and land guidance. Because of the various errors in laser gyro, the precision of developing is restricted. Thereinto, temperature is one of the most important elements that affect the output precision of bias. The main features are randomness and instability.To improve the accuracy and stabilization of SINS, we must modeling analysis thermal induced bias error.With the method enhance the precision of SINS.First, backgrounds and developments of related areas at home and abroad are briefly presented. The measurement principle of laser gyro is derived and the three main error factors that affect the output accuracy of laser gyro are narrated. Several ideas of thermal induced bias and their compesation methods are analysed emphatically.Second, according to characteristics of laser SINS's output error mechanism, proposed system-level temperature error modeling theory. Conducted an experimental design and proposed weighted multi-sensor fusion of data processing method.The experiment was carried out under static state, and the error model of SINS was derived to calibrate the four mode multi-oscillation gyro's bias and scaling factors using generalized inverse algorithm. Based on the past temperature error models and using Final Output Error criteria of Asymptotical Identification theory, the rank of nonlinear part of temperature error models is calculated, and the best structure of temperature error compensation model is determined. The paper applies Self-adapt Ridge Regression estimator to calculate the coefficients of the temperature error models to avoid overflowing of least square algorithm, and establishes a system-level temperature error compensation. The experiment results show that the method is applicable, and the acquisition precision of the system has been improved obviously.Last, based on the hypothermia lauching experiment of dithered gyro, using recursive least square algorithm to calculate the coefficients of the temperature error models to avoid overflowing of LS algorithm. The experiment and simulation demonstrate that the recursive algorithm is correct and effective, with the advantage of less computation time, valid parameter estimation and small modeling errors. The algorithm is suitable for on-line modeling applications in the cases of large-scale measurement data and the requirements of high efficiency as well.