Study On The Key Technology Of North Seeking System Based On Fiber Optic Gyroscope

The gyro north seeker can provide the orientation information quickly and independently in any weather conditions, so it has very important application value in both military and civil fields. Fiber optic gyroscope (FOG) is a kind of all solid state inertial instruments, which has a lot of advantages compared with the traditional mechanical gyroscope, and it has been more and more widely used in inertial field. This paper aims to the high accuracy FOG north seeking system. Based on the theoretical analysis and experimental research of the FOG's output characteristic and north seeking principle, the key technology of FOG north seeking system is discussed in detail. From the practical demand of improving the system accuracy, the north seeking scheme, error analysis, system design and data processing are studied extensively and intensively in this paper. The main work and contributions of the dissertation are as follows:1. The random error model and the output drift model of FOG are proposed. Based on the study of random noise sources, the Allan variance analysis method is introduced to establish the random error model. The method of time series modeling is proposed. The Kalman filter is applied to decrease the effect of random output drift.2. The theoretical models of static and continuous rotation north seeking scheme are established. An improvement method for two-position and four-position scheme, and the algorithms based on correlation theory and phase difference for continuous rotation scheme are proposed. The north seeking models for inclination compensation are established.3. The error model of north seeking system is established. The effects of each error sources, such as FOG drift error, mounting error, rotation error, angle measurement error and latitude error, on the north seeking accuracy are derived. The method for estimating the north seeking system error is proposed.4. The architectural structure of north seeking system based on FOG is proposed; the hardware and software of system are designed and implemented. During the system implementation, a high accuracy rotation control system based on fuzzy-PID algorithm is proposed to improve the rotation error effectively. The north seeking system is tested, the performance of each north seeking scheme in different conditions are obtained.5. The application of particle filtering in the north seeking system is proposed. It can effectively reduce the influence of drift and random noise on the north seeking accuracy. Two kinds of particle filter are designed and experiments are carried out in four-position scheme. The results show that, compared with the particle filter based on system resampling, the filter based on MCMC algorithm can achieve better performance.6. The effects of base disturbance on the north seeking system performance and solution are studied. The application of wavelet filter in the north seeking with base disturbance is proposed. According to the experimental analysis, the high frequency disturbance can be effectively filtered by wavelet filtering; for the pulse disturbance, the method of performing the weighting process to the result of wavelet filtering is proposed.