Research On The Key Navigation Technology Of The Unmanned Underwater Vehicle In The Polar Region

Unmanned Underwater Vehicle(UUV)is important marine equipment.Its development follows two important directions.On the one hand,in terms of its navigational environment,UUV will surely sail towards farther and deeper seas.This will involve the issues related to UUV navigation in the polar region.On the other hand,UUV will become more intelligent and efficient way to cope with the increasingly complex mission.This will involve the cooperative problem of multi-UUV.This paper will follow the above two development directions of UUV.Based on solving the failure of conventional UUV navigation algorithms in the polar region,aiming at improving the navigation accuracy of UUV in the polar region,focusing on navigation hotspots and key issues of polar UUV naviagtion,the key navigation technology of UUV in the polar region is discussed in this paper.The Arctic region is rich in the natural and mineral resources.The exploration and development of the Arctic region has certain practical value.In addition,from the geographical location of the Arctic,it is the most convenient sea passage connecting the Pacific Ocean and the Atlantic Ocean.It is the closest area to some of the world's most influential countries.The security of the northern hemisphere countries is closely related to the Arctic region.Therefore,the exploration and development of the Arctic region also has certain military value.Due to the chilly climate,most areas of the Arctic Ocean are covered by sea ice all the year round.The scientific research ship need to carry out ice-breaking operations when sailing,which brings certain difficulties.And because of the human beings on the scientific research ship,the reliability requirements are high.The UUV is safer than the scientific research ship because it does not need to carry the humans,but it needs high autonomy and intelligence.In addition,UUV can sail underwater without the need for ice breaking operations.At the same time,accurate and meticulous detection of the marine conditions and resources in the Arctic Ocean can be carried out.The Stradown Inertial Navigation Syatem(SINS)is widely used in the UUV navigation because of high autonomy.However,most of the algorithms currently used in UUV navigation are only applicable to mid-low latitudes.The natural environment and navigation environment of the polar region are unique,such as the rapid convergence of the meridian near the pole,and the latitude approaching 90°.These have caused problems such as computational overflow and error amplification in conventional UUV inertial navigation algorithms.As a result,the conventional UUV inertial navigation algorithms are failure in the polar region.In order to solve the failure of the conventional UUV inertial navigation algorithm in the polar region,a UUV grid inertial navigation algorithm suitable for UUV navigation in the polar region is proposed.The system model and the mechanical arrangement mode of the UUV grid inertial navigation algorithm are constructed.Aiming at the problem that the Strapdown Inertial Navigation System has accumulated error over time and the failure of the traditional auxiliary navigation algorithm caused by the polar environment,the auxiliary navigation algorithm suitable for UUV navigation in the polar region is explored.In order to solve the problem that the bottom tracking mode in the Doppler Velocity Log(DVL)assisted UUV navigation algorithm fails in the polar region and the water tracking mode is not accurate,a DVL-assisted UUV navigation algorithm based on the top tracking mode is proposed.The DVL system with top tracking mode is selected as the auxiliary navigation mode for UUV navigation in the polar region.The USBL system is selected to realize the posization measurement of UUV in the polar region.The principle of the auxiliary navigation system is explored and the model of the auxiliary navigation system is built.There are acceleration errors in polar UUV grid inertial navigation.Based on the DVL/USBL integrated assistive technology,the UUV polar navigation algorithm is proposed to effectively solve the problem of error accumulation in the UUV grid inertial navigation algorithm.There are two sources of error in the UUV polar inertial navigation,including the error in the navigation process and the error in the initial conditions.Therefore,the initial condition also affects the navigation accuracy of the UUV polar navigation.Aiming at the problem that the conventional UUV initial alignment algorithms are failure in the polar region,based on UUV grid inertial navigation,the initial coarse alignment algorithm of UUV polar navigation is designed.Based on the initial alignment result of the polar UUV coarse alignment,the UUV polar fine alignment is designed.The coarse alignment uses the projection of the gravity acceleration vector in the inertial frame to obtain the value of the initial attitude matrix of the UUV.When UUV reaches near the pole,the gravity vector is collinear with the ground axis,which affects its accuracy.Further,the initial coarse alignment result is the large azimuth misalignment angle.Therefore,the polar UUV fine alignment algorithm will be constructed with a large azimuth misalignment angle.The conventional UUV initial alignment algorithm is modified to meet the initial alignment accuracy requirements of the UUV in the polar region.Finally,based on the UUV polar initial alignment algorithm and the UUV polar navigation algorithm,the multi-UUV polar cooperative navigation algorithm is designed to meet the needs of future UUV task complexity and high efficiency.The centralized formation configuration is adopted in this paper.The navigation information of the follower UUV is corrected by the navigation information of the leader UUV.On the one hand,the cost of the navigation device is saved,and on the other hand,the navigation accuracy of the follower UUV is guaranteed.The UUV polar initial alignment algorithm and the UUV polar navigation algorithm are designed on both the leader UUV and the follower UUV to solve the failure of the conventional navigation algorithm in the polar region.The underwater communication delay is analyzed and quantified,and the traditional adaptive Kalman filtering algorithm is improved with the quantitative model to meet the needs of multi-UUV polar cooperative navigation.Due to the limitation of the geographical environment,the verification experiments in this paper are carried out by means of simulation experiments and semi-physical simulation experiments based on the measured data.Considering the characteristics of the Strapdown Inertial Navigation System,some of the data does not change in different geographical position,so it can be measured at the middle or low latitudes to obtain the measured data.The other part of the data is directly related to the specific navigation state of the UUV.The value of this part of the data can be directly determined by the determination of the navigation state.Therefore,this part of the data can be obtained through the simulation.Therefore,the UUV voyage experiment in the polar region can be simulated by the mode of the semi-physical simulation experiment.Simulation and semi-physical simulation experiments based on measured data verify the effectiveness of the the key navigation technology of UUV in the polar region.