Research On The Key Technology Of Grid SINS/Acoustic Integrated Navigation For Polar Regions

The grid strapdown inertial navigation system(SINS)has been proposed to solve the problem of meridian convergence and employed as the basic navigation system in polar regions.Navigation with a single grid SINS is hard to be sufficient.The acoustic sensors,such as the Doppler velocity log(DVL)and ultra-short base line(USBL),have high accuracy and will not lose ability in polar regions,which can be employed to correct the grid SINS errors.Therefore,the grid SINS/acoustic integrated navigation algorithms,which contain the error propagation,grid SINS mechanization,integration algorithms and anti-interference technology,will be researched to improve the accuracy and reliability of the polar navigation.To improve the accuracy and reliability of the long-endurance navigation systems in polar regions,the navigation theory and method of grid SINS/acoustic integration are researched to solve the problems caused by artificial definition,interval measurements and measurement outliers.The research contents are included as follows:(1)the error propagation and problem analysis of navigation systems in polar regionsThe error propagation of grid SINS is studied and compared with the traditional north-oriented SINS to explore the influence of polar environment on the grid SINS.Then the availability of the DVL and USBL in polar regions is analysed and the grid SINS/acoustic integrated navigation algorithm is designed with the single axis rotation modulation to improve the navigation accuracy.Finally,the problems of polar grid SINS/acoustic integration are sorted out to guide the research direction.(2)research about the grid SINS/DVL integrated navigation algorithmTo solve the accuracy problem caused by artificial definition,the grid SINS/DVL integratd navigation algorithm is modified by changing the position coordinate and unifying the earth models.The spherical and orthogonal position coordinates of the earth are employed by the traditional mechanization.To avoid the longitude error amplification caused by the meridian convergence in polar regions,the mechanization without longitude is proposed,which is the basis of the modified grid SINS/DVL integration algorithm.The traditional grid SINS/DVL integrated algorithm employs different earth models between the SINS mechanization and the integrated filter model,which will lead to the principle errors and decrease the navigation accuracy.Based on the mechanization without longitude and unified rotating ellipsoid earth model,the gird SINS error equations are derived,and a dynamic filter model is designed to improve the estimation accuracy.Then,the grid SINS/DVL integrated navigation algorithm is proposed with the unified earth model to improve the navigation accuracy.Finally,some simulation and experiments are conducted to verify the performance of the proposed algorithms.(3)research about the grid SINS/USBL/DVL integrated navigation algorithmTo restrain the position error divergence,the position from the USBL is introduced as measurements.The acoustic navigation signal in polar regions is easy to be interrupted,which will lead to the accuracy decrease,so some navigation algorithms with different integrated patterns are proposed to exploit potentiality of the USBL.To improve the position accuracy and adaptation of intermittent measurements,the relative position between the transponder and hydrophone array from the USBL is chosen as the measurement to conduct the relative position loose-coupled integrated navigation algorithm.To improve the accuracy and stability of USBL output,the original phase difference and time delay from the USBL are employed as measurements to design the tightly-coupled integrated navigation algorithm,in which the USBL and grid SINS can be assisted by each other to maintain navigation stable and accurracy.Finally,some simulation and experiments are conducted to verify the performance of the proposed algorithms.(4)research about the anti-interference technology of the grid SINS/acoustic integrationThe accuracy and reliability of integrated navigation will be reduced by the outliers of acoustic measurements,so some anti-interference technologies are researched.First,the traditional fault detection method cannot locate the fault measurements of the centralized filter.Therefore,the vector fault detection technology is proposed,which takes the measurement as the detection object and will not rely on the filter structure.Second,the small slowness outliers is hard to be detected.Therefore,the fault-tolerant Kalman filter is proposed with a quality evaluation function to restrain multiple outliers by adjusting the measurement weight.Third,the adaptive dual-channel correction structure is proposed.According to the time and measurement noise intensity,the integrated navigation system chooses the correction channel adaptively,which can help improving the long endurance accuracy and reduce the influence from filter estimation errors on navigation system.Finally,some simulation and experiments are conducted to verify the performance of the proposed anti-interference technologies.