Research On Online Self-calibration Technology Of Three-axis Rotation Modulation RLG INS

Inertial navigation is an important navigation method in aerospace,aviation,marine navigation and other fields,with a high degree of independence and concealment.In order to further improve the accuracy of long-endurance navigation and positioning,it is necessary to carry out in-depth research on several key technologies of the inertial navigation system(INS).The calibration technology is to identify and estimate the error factors of the INS,and to construct a mathematical model to compensate the error of output of the inertial device.Error compensation is the basis for obtaining accurate navigation information.Therefore,the calibration accuracy of the INS will directly affect the navigation accuracy.The thesis researches on the online self-calibration technology of three-axis rotation modulation RLG INS.The purpose is to propose an online self-calibration scheme suitable for the three-axis rotation modulation RLG INS,and to improve the navigation and positioning accuracy of the system in a variable temperature environment and a dynamic environment.The research contains the following aspects:1.The error model and the design of online self-calibration scheme of three-axis rotation modulation RLG INS.Introduce the system composition of the three-axis rotation modulation RLG INS.The error model of the system’s main inertial devices(laser gyroscope and accelerometer)is constructed.Based on the error propagation equation of the strapdown inertial navigation system,the state equation and measurement equation of the 30-dimensional Kalman filter are derived.According to the shaft configuration requirements of the three-axis rotation mechanism,the arrangement of the calibration path is determined.The feasibility of the self-calibration scheme is verified by the simulation experiment.Simulate the three-axis rotation mechanism with a three-axis turntable,the online self-calibration experiment of the three-axis rotation modulation RLG INS is carried out,and the repeatability of the experiment and the long-term stability of the calibration parameters are analyzed.The results of the navigation experiment prove that the navigation accuracy in static environment is better than 0.2 n mile/2h,and the seven-day positioning error of three-axis rotation modulation is better than 0.73 n mile.The navigation accuracy in dynamic environment is better than 0.23 n mile/h.2.Research on online self-calibration temperature compensation technology.The two algorithms for constructing the temperature model of online self-calibration parameters are separately studied.Firstly,the traditional experiment of calibration at multi-temperature point is carried out to fit temperature coefficients,and the fitting result of the temperature coefficients is given.In view of the long calibration cycle and complex calibration process of this method,a new system-level temperature compensation method is proposed,and a 42-dimensional Kalman filter including temperature coefficients is designed.Under the excitation of a variable temperature environment,the temperature coefficients can be calibrated through one experiment.The calibration process is greatly simplified,and the calibration time is shortened.The natural temperature rise effect of the INS during the cold start process can be effectively utilized,so the calibration can be completed without occupying the initial alignment and navigation time.The feasibility of this method is verified by simulation experiment.The results of repeatability experiments and long-term parameters stability analysis show that the proposed temperature coefficients calibration method has high repeatability,and the calibration results have good long-term stability,which can be applied to engineering practice.Finally,the static and moving vehicle experiment under a random variable temperature environment were designed and implemented.The experimental results show that the system-level temperature compensation method can improve the navigation accuracy by more than 10% in both static and dynamic environments.3.Research on the calibration method of size effect error.The principle of the size effect error is analysed.The error modeling and calibration compensation method of the inner lever arm effect are emphasized.A 39-dimensional Kalman filter containing the parameters of the inner lever arm is designed.The simulation experiment was carried out on the calibration path of variable angular velocity motion.The results of the simulation experiment show that all 9 inner lever arm parameters can be accurately calibrated.Based on the laboratory three-axis turntable,an online self-calibration experiment of the inner lever arm parameters was carried out to verify the repeatability of the calibration method.Analyzing the calibration results of the inner lever arm parameters of two different IMU installation methods,it is proved that the inner lever arm parameters have no relationship with the position of the IMU relative to the center of the carrier.A swing motion navigation experiment under the static base was carried out.The experimental results show that in a large angular motion environment,the navigation error of speed and positioning after the compensation of the inner lever arm parameters are significantly reduced,and the positioning accuracy is improved by more than 30%.