The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this p...The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this problem,a line-surface integrated terrain matching algorithm is presented.First,the similarity evaluation method of the traditional Terrain Contour Matching(TERCOM)algorithm is improved,and the strategy used to select the matching regions is developed.Then,a surface matching algorithm based on the geometric similarity is established to determine the optimum match between the reference maps and the actual measured terrains.Finally,a means of“line matching algorithm”and“surface matching algorithm”integration is proposed based on a fixed threshold.The experimental results show that the proposed algorithm can obtain a more accurate location and has greater robustness than that of the surface underwater matching algorithm based on Hu moment.展开更多
To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwat...To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation（LSE） is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.展开更多
This article presents a passive navigation method of terrain contour matching by reconstructing the 3-D terrain from the image sequence(acquired by the onboard camera).To achieve automation and simultaneity of the ima...This article presents a passive navigation method of terrain contour matching by reconstructing the 3-D terrain from the image sequence(acquired by the onboard camera).To achieve automation and simultaneity of the image sequence processing for navigation,a correspondence registration method based on control points tracking is proposed which tracks the sparse control points through the whole image sequence and uses them as correspondence in the relation geometry solution.Besides,a key frame selection method based on the images overlapping ratio and intersecting angles is explored,thereafter the requirement for the camera system configuration is provided.The proposed method also includes an optimal local homography estimating algorithm according to the control points,which helps correctly predict points to be matched and their speed corresponding.Consequently,the real-time 3-D terrain of the trajectory thus reconstructed is matched with the referenced terrain map,and the result of which provides navigating information.The digital simulation experiment and the real image based experiment have verified the proposed method.展开更多
The maximum ocean depth so far reported is about 11000 m,and is located in the Mariana Trench in the Western Pacific Ocean.The hybrid unmanned underwater vehicle,Haidou,is developed to perform scientific survey at the...The maximum ocean depth so far reported is about 11000 m,and is located in the Mariana Trench in the Western Pacific Ocean.The hybrid unmanned underwater vehicle,Haidou,is developed to perform scientific survey at the deepest parts of the Earth oceans.For vehicles working at the full-ocean depth,acoustic positioning is the most effective and popular method.The 11000 m class acoustic positioning system is relatively massive and complex,and it requires specialized research vessels equipped with compatible acoustic instruments.As a compact testbed platform,it is impractical for Haidou to carry an LBL/USBL beacon with its large volume and weight.During the descent to about 11000 m,horizontal drift could not be eliminated because of the hydrodynamics and uncertain ocean currents in the sea trials.The maximum depth recorded by Haidou is 10905 m,and determining the precise location of the deepest point is challenging.With the bathymetric map produced by a multibeam sonar,the terrain contour matching(TERCOM)method is adopted for terrain matching localization.TERCOM is stable in providing an accurate position because of its insensitivity to the initial position errors.The final matching results show the best estimate of location in the reference terrain map.展开更多
基金The National Nature Science Foundation of China(Nos.414713804160149841774014)。
文摘The current underwater terrain surface matching algorithm,which uses Hu moment as the similarity index,cannot gain accurate location due to the algorithm’s disadvantage in detecting slight differences.To solve this problem,a line-surface integrated terrain matching algorithm is presented.First,the similarity evaluation method of the traditional Terrain Contour Matching(TERCOM)algorithm is improved,and the strategy used to select the matching regions is developed.Then,a surface matching algorithm based on the geometric similarity is established to determine the optimum match between the reference maps and the actual measured terrains.Finally,a means of“line matching algorithm”and“surface matching algorithm”integration is proposed based on a fixed threshold.The experimental results show that the proposed algorithm can obtain a more accurate location and has greater robustness than that of the surface underwater matching algorithm based on Hu moment.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.51179035 and 51279221)the Natural Science Foundation of Heilongjiang Province(Grant No.E201121)
文摘To achieve accurate positioning of autonomous underwater vehicles, an appropriate underwater terrain database storage format for underwater terrain-matching positioning is established using multi-beam data as underwater terrainmatching data. An underwater terrain interpolation error compensation method based on fractional Brownian motion is proposed for defects of normal terrain interpolation, and an underwater terrain-matching positioning method based on least squares estimation（LSE） is proposed for correlation analysis of topographic features. The Fisher method is introduced as a secondary criterion for pseudo localization appearing in a topographic features flat area, effectively reducing the impact of pseudo positioning points on matching accuracy and improving the positioning accuracy of terrain flat areas. Simulation experiments based on electronic chart and multi-beam sea trial data show that drift errors of an inertial navigation system can be corrected effectively using the proposed method. The positioning accuracy and practicality are high, satisfying the requirement of underwater accurate positioning.
基金supported by the "Eleventh Five" Obligatory Budget of PLA (Grant No.513150801)
文摘This article presents a passive navigation method of terrain contour matching by reconstructing the 3-D terrain from the image sequence(acquired by the onboard camera).To achieve automation and simultaneity of the image sequence processing for navigation,a correspondence registration method based on control points tracking is proposed which tracks the sparse control points through the whole image sequence and uses them as correspondence in the relation geometry solution.Besides,a key frame selection method based on the images overlapping ratio and intersecting angles is explored,thereafter the requirement for the camera system configuration is provided.The proposed method also includes an optimal local homography estimating algorithm according to the control points,which helps correctly predict points to be matched and their speed corresponding.Consequently,the real-time 3-D terrain of the trajectory thus reconstructed is matched with the referenced terrain map,and the result of which provides navigating information.The digital simulation experiment and the real image based experiment have verified the proposed method.
基金Project supported by the National Key R&D Program of China(Nos.2018YFC0308804 and 2016YFC0300800)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDB06050200)。
文摘The maximum ocean depth so far reported is about 11000 m,and is located in the Mariana Trench in the Western Pacific Ocean.The hybrid unmanned underwater vehicle,Haidou,is developed to perform scientific survey at the deepest parts of the Earth oceans.For vehicles working at the full-ocean depth,acoustic positioning is the most effective and popular method.The 11000 m class acoustic positioning system is relatively massive and complex,and it requires specialized research vessels equipped with compatible acoustic instruments.As a compact testbed platform,it is impractical for Haidou to carry an LBL/USBL beacon with its large volume and weight.During the descent to about 11000 m,horizontal drift could not be eliminated because of the hydrodynamics and uncertain ocean currents in the sea trials.The maximum depth recorded by Haidou is 10905 m,and determining the precise location of the deepest point is challenging.With the bathymetric map produced by a multibeam sonar,the terrain contour matching(TERCOM)method is adopted for terrain matching localization.TERCOM is stable in providing an accurate position because of its insensitivity to the initial position errors.The final matching results show the best estimate of location in the reference terrain map.
