The Research On Inertial/gravity Integrated Navigation Algorithm Using In Polar Region

As the global temperature rising,the arctic navigation become possible,at the same time,the polar region is rich in natural resources.Therefore,the competition for polar space and resource is increasingly fierce,and reliable polar navigation system is the premise of human activity in polar region.So,under the background of polar navigation issues,the thesis carry on the demand analysis,give a polar integrated navigation system which combines the inertial navigation units and gravity gradiometer,design the INS/GGI and INS/GGI/GPS integrated navigation filter,the main contents are shown as follows:Firstly,the thesis gives the definition of coordinate system and transformation relations,and the measurement model of gyroscope and accelerometer measurement model is established.In view of the meridian convergence problems which happened to traditional inertial navigation calculating method in polar region,the thesis derives the mechanical layout equation of INS,gives the measuring principle of rotating accelerometer gravity gradiometer,analyses the characteristics of error and the foundation is established for modeling INS/GGI integrated navigation system.Secondly,the method for calculating gravity gradient map is studied.The gravity gradient consists of two parts: low frequency and high frequency.The low frequency part is mainly produced by geological density changes,the high frequency part is produced by the terrain changes.In view of this characteristic,the low frequency part is simulated by partial differentiate gravity ball harmonic function,the high frequency is simulated by DEM(Digital Elevation Model),and the method is proved by mathematical simulation.Thirdly,INS/GGI integrated navigation method is studied.The state equation is established based on inertial navigation calculating equations of grid coordinate system.According to the measuring principle of GGI,the measurement model of 12 accelerometer gravity gradiometer is given.The thesis also designs the INS/GGI integrated navigation filter and analyses the influence caused by terrain,flight height,fly velocity and sensor accuracy.Finally,an INS/GGI/GPS information fusion integrated navigation method is proposed to improve the accuracy and reliability of navigation system.The method applies the distributed fusion structure and designs the integrated navigation filter based on cubature information filter.In contrast to INS/GGI navigation system,the accuracy and reliability are both improved in the INS/GGI/GPS navigation system.