Research On The Polar Inertial Navigation Algorithm

As the important values of abundant resources,scientific research and military,it is very significant for countries to realize the exploration of the polar region.Existing navigation methods such as astronomical navigation,satellite navigation,radio navigation and geomagnetic navigation are susceptible to environmental factors.At the same time,since the multipath effect,weak horizontal magnetic lines and uneven magnetic fields distribution in the high latitude areas,which causes the above navigation methods to not always work normally in the harsh environment of the polar region.The inertial navigation system(INS)has the characteristics of not relying on external information or radiating energy to the outside,and can be applied to various complicated and harsh environments.Therefore,as a completely autonomous navigation method,it has been widely used in the polar navigation.However,as the geographical latitude continues to increase,especially near the pole,the extreme convergency of the geographic meridians,so that the traditional north-oriented mechanization with the geographic north direction as the reference heading cannot complete the navigation task in the polar region.In order to solve the problems of the traditional north-oriented mechanization in the polar region,two kinds of inertial navigation algorithms suitable for the polar region are presented in this paper.The first is the transverse inertial navigation algorithm in the polar region.The second is the grid inertial navigation algorithm in the polar region.The main research contents of this paper are as following:First of all,the research and analysis of the traditional INS mechanization.The north-oriented SINS mechanization is deduced.In order to facilitate the analysis,the static error equations of the north-oriented INS mechanization are directly given.Through the analysis of the error equations,it is found that the north-oriented INS mechanization in the polar region would suffer from the difficulty of azimuth gyroscope,the large amount of calculation,the overflow and the increase of the calculation errors.Secondly,the research and analysis of the transverse INS algorithm in the polar region.The original poles are moved to both ends of the original equator to form a transverse south pole and a transverse north pole,and get a new frame,the transverse earth frame.Based on this frame,the transverse INS mechanization is designed.The transforming formulas of attitude matrix,velocity and position in the conventional frame and the transverse earth frameare given,and the free conversion of INS under different mechanization is realized.The transverse INS error equations are established and analyzed,it is found that the transverse INS has three periodic oscillation errors of Foucault,Schuler and Earthquake.This characteristic is the same as the traditional north-oriented mechanization,and the transverse longitude,the transverse latitude and the transverse heading error diverges with time.The simulation experiments verify whether the transverse INS algorithm can achieve the correctness of polar navigation,and the transverse INS performance analysis.Then,the research and analysis of the grid INS algorithm in the polar region.A new frame,namely the grid frame,is established.Based on this frame,the grid INS mechanization is designed.The transforming formulas of attitude matrix,velocity and position in the conventional frame and the grid frame are given,and the free conversion of SINS under different mechanization is realized.The grid INS error equations are established and analyzed,it is found that the grid INS mechanization has three periodic oscillation errors of Foucault,Schuler and Earthquake.This characteristic is the same as the traditional north-oriented mechanization and the transverse INS mechanization.At the same time,it is found that the grid heading angle do not diverge due to the introduction of the grid azimuth.The simulation experiments verify whether the grid INS algorithm can achieve the correctness of polar navigation,and the grid INS performance analysis.Finally,the research and analysis of the polar inertial navigation algorithms in global navigation.Since the transverse earth frame also has the transverse north-south problem similar to the conventional earth north-south problem.Therefore,the transverse inertial navigation algorithm cannot accomplish global navigation alone,and it is necessary to be combined with the north-oriented inertial navigation algorithm.However,the command azimuth angular rate of the grid frame has a latitude-related term(cot L),which causes the grid inertial navigation algorithm to not work properly near the equator.Therefore,the grid inertial navigation algorithm cannot accomplish global navigation alone,and it is necessary to be combined with the north-oriented inertial navigation algorithm.Thus,the application of the polar inertial navigation algorithms in global navigation has been studied;In addition,in order to the application in later engineering and improve the programing efficiency,the global inertial navigation algorithm is implemented in C\C++ language;Finally,the low-static measured data,the low latitude on-board measured data and simulation experiments verify that the polar inertial navigation algorithm can also complete the mid-latitude navigation task and whether the global navigation algorithms can complete the global navigation task.