Research On Polar Region Navigation Method Of Long Endurance Inertial Navigation System

The polar regions are rich in natural resources,important transportation value and unique military value,which makes it gradually become a battlefield for national competition.To explore in the polar regions,the first thing to solve is the navigation problem.The ability to have long-endurance navigation across polar regions is one of the country’s requirements for a new generation of aircraft and ships.As a passive and fully autonomous navigation method,inertial navigation is the first choice for polar navigation.However,inertial navigation has the problem that errors accumulate over time.Therefore,it is often used with other sensors such as satellites,astronomy,etc.as observation methods and information fusion is carried out through Kalman filtering to achieve the purpose of high-precision integrated navigation.The traditional single navigation frame has its own shortcomings.In order to achieve transpolar global integrated navigation,the existing navigation system often adopts two or more navigation coordinate systems,for example,the local geographic frame and the grid frame.When the carrier enters the polar region,the integrated navigation frame is switched from the north-pointing coordinate system to the grid system,which ensures the smooth progress of navigation.However,in different integrated navigation frames,the error status will change,resulting in filter overshoot and error discontinuity,which reduces the navigation accuracy.In response to this problem,this paper analyzes the coordinate system switching and studies a method to realize the smooth switching of the navigation coordinate system without changing the existing navigation arrangement method.This paper proposes INS/GNSS and INS/DVL global integrated navigation methods based on covariance transformation to solve the problems of stable navigation across regions in low and middle latitudes/high latitudes,and provide technical support for global navigation of large aircraft and ships.The thesis is divided into three parts,arranged as follows:In the first part,the paper analyzes four common navigation coordinate systems:the ECEF,the local geographic frame,the traverse frame and the grid frame.Their definitions,mechanical arrangement and error equations are given respectively.Finally,through simulation experiments,the accuracy of their navigation in the polar regions is studied,which lays the foundation for the selection of the global integrated navigation scheme and the covariance transformation algorithm in the following text.In the second part,this paper uses the local geographic coordinate system and grid system as the global integrated navigation scheme,and satellites as the observation.A method of INS/GNSS integrated navigation based on covariance transformation is proposed.The paper establishes the conversion relationship between the system error state and its covariance in the local geographic frame and the grid frame,and designs an integrated navigation filter with full latitude applicability.The effectiveness of the algorithm is verified through vehicle experiments and semi-physical simulation experiments.Subsequently,this paper designs open-loop and closed-loop filtering schemes,and compares the effectiveness of covariance transformation algorithms in open-loop and closed-loop filtering through aviation flight experiments.In the third part,the paper uses the local geographic frame and the traverse frame as the global integrated navigation scheme,and the DVL as the observation.A combined INS/DVL navigation method based on covariance transformation is proposed.The paper establishes the conversion relationship between the system error state and its covariance in the northern coordinate system and the abscissa coordinate system,and designs an integrated navigation filter with applicability in all latitudes.The effectiveness of the algorithm is verified through experiments.