| The mechanically dithered ring laser gyro (MDRLG) is playing a more and more important role in inertial strapdown systems in our country. When the MDRLG working, high frequency dithering is introduced, and the strapdown navigation system with MDRLG has some properties which are different from the systems with other types of gyros. Research on these properties would benefit both the improvement of MDRLG itself and the design of strapdown systems with MDRLG.The kinematic model of inertial measurement unit (IMU) with MDRLG has been analyzed theoretically, the coning drift caused by dithering has been calculated, and some problems including the assembly of inertial sensors have been discussed. Based on the theoretical analysis, the overall optimized design of the system has been presented, including the dithering frequency of RLGs, the resonance frequency and the rotation inertia of IMU, and the resonance frequency and the fix position of isolators, etc.The compensation of high frequency dithering caused by MDRLG has been studied. Different filtering methods have been tested to examine the effects of all kinds of filters. The correction of inertial sensor errors, navigation algorithm, coning motion, and sculling motion have also been investigated. Based on the above works, the initial alignment on stationary base using IMU with MDRLG has been carried out, and an usable navigation software has been completed.Wavelet was introduced to process the MDRLG signal and the noise of MDRLG was analyzed in wavelet domain. As a result, a de-noising algorithm with lift scheme that can work online has been presented. By using wavelet as a pre-filter, the convergence speed of kalman filter can be accelerated.A series of tests have been carried out on the accomplished inertial system. In the position location tests, the CEP of the system is less than 1 nm/h. It showed that the research on inertial strapdown system with MDRLG and the experimental methods in this thesis is correct.
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