Research On Strapdown Inertial Navigation System With Mechanically Dithered Ring Laser Gyroscope And Its Real-time Temperature Compensating Approach

The mechanically dithered ring laser gyro (MDRLG) is playing a more and more important role in strapdown inertial navigation system (SINS) in our country. Due to change of environment temperature and thermo effect of system self-generating, the temperature of inertial instrument is changed, and their scale and bias are altered in practical engineering application. The precision of initial alignment and navigation is affected ultimately. The kinematics error of SINS must be compensated also. The temperature compensating approach and compensating model of MDRLG and accelerometer are studied mainly, and temperature compensating approach, coning error compensation and calibration approach of SINS are investigated.At the beginning, the principle and structure of SINS with MDRLG are presented firstly. The error factors of inertial measurement unit (IMU) have been analyzed; the error compensating approach and its think have been analyzed emphatically. In third chapter the application of digital signal processor (DSP) in SINS has been mainly studied according to require of engineering and temperature compensation, and has presented the software's and hardware's implementation of the main board (DSP board),and the theory above has been used in navigation system's practical operation and control. The high precision testing temperature circuit has been designed, and the navigation software has been introduced. In the course,we can get a conclusion that the DSP'S sustentation of advanced language and modularized programming idea make the whole navigation program' s development easy, the period of development shorten greatly, readability boost enormously, and extensibility and maintainability improved highly.In fourth chapter MDRLG's error has been analyzed theoretically. The temperature characteristic of MDRLG's bias has been analyzed theoretically and experimentally. The real-time temperature compensating model of MDRLG's bias has been found by polynomial fitting, sparse multivariable regression model and stepwise regression model. The model has been validated experimentally, and the result has shown that the model is effective and universal. In addition, the adaptive modeling for the bias of MDRLG has been researched, and application of Radial Basis Function (RBF) neural network has been researched in identifying temperature bias model of MDRLG. In the end, the calibration for MDRLG in SINS has been carried out.In fifth chapter accelerometer's error has been analyzed theoretically. The temperature characteristic of accelerometer's bias and scale has been analyzed theoretically and experimentally. The real-time temperature compensating model of accelerometer and I/F conversion circuitry have been found by polynomial fitting. The model has been validated experimentally. The multi-temperature and multi-position calibration for accelerometer in SINS has been carried out.In sixth chapter the kinematics error of SINS has been analyzed theoretically. The corrections of coning motion and sculling motion have been investigated. Based on linear vibration experiment, the compensating effect has been validated, and it has been shown that the compensating method is effective.A series of tests have been carried out on the accomplished inertial system. Based on compensating testing experiment, the means of temperature compensation and kinematics error compensation in SINS are effective. Considering initial alignment in disturbing, turning around after alignment, altering environment temperature, unilateral, loopy and close position location tests, in any position location tests, the CEP of the system is less than 0.3nm/h. It showed that the research on inertial strapdown system with MDRLG and the experimental methods in this thesis is correct.