Research On The Vibration Reduction Of Dithered Laser Gyro Strapdown Attitude & Heading Measurement System

Strapdown Inertial Systems are widely used in the fields of navigation, guiding and attitude&heading measurement for their merits of simple structure, small volume and low cost. Vibration reduction should be considered in Strapdown Inertial Systems composed of dithered laser gyros to reduce the bad influence of vibration caused by gyros and the carrier. Theoretical study and simulation analysis have been carried out in this dissertation for the vibration reduction of strapdown systems. A practical vibration reduction system is designed for a shipborne strapdown attitude&heading measurement system. The main work of this dissertation is as follows:1. The influence on Strapdown Inertial System caused by gyros'vibration is studied based on the research of strapdown system's structure and laser gyro's dither biasing principle. The task of vibration reduction is analyzed.2. The mass-spring model and its motion differential equations are developed for both single-freedom and multi-freedom vibration systems based on the study of basic vibration theory. Both the frequency ratio's and damping ratio's influence on the reduction effect are analyzed and the damping's energy-consuming formula during the process of vibration reduction is deduced. The choosing principles of isolators and their layouts are also analyzed.3. Vibration reduction is designed for a shipborne strapdown attitude&heading measurement system. Through the analysis of the vibration influence caused by mechanical resonance, this dissertation points out that the power of damping's energy-consuming will be too large for the gyro to work normally while resonance happens. Rubber vibration isolators and the horizontal push-pull layout for them are chosen while designing the vibration reduction system. Both the linear vibration theoretical model and finite element simulation model are developed for rubber isolators, then the two models are validated by experiments. The performance of the vibration reduction system designed in this dissertation is analyzed through the methods of theoretical study and finite element simulation, and the results illustrate that it has a good performance while isolating the vibration caused by gyros or the environment.Finally, theoretical analysis and simulation study are carried out for the optimization of the vibration reduction system and suggestions for optimizing the vibration reduction design in Strapdown Inertial System are also given.