An underwater vehicle navigation method and system based on synchronous imaging and gravity lighthouse

Abstract

The present invention relates to a submersible navigation method and system based on synchronous imaging and gravity lighthouses, and particularly relates to the technical field of underwater submersible gravity navigation. The method includes: determining the error ellipse range according to the sea area position of the submersible in the current sea area and the variances of the eastward and northward directions of the position indicated by the inertial navigation system; determining the level of the gravity lighthouse according to the gravity lighthouses within the error ellipse range and the gravity lighthouse database; the gravity lighthouse database includes the levels of each gravity lighthouse in the current sea area; the levels of each gravity lighthouse in the current sea area are obtained by processing the statistical characteristic parameters of the gravity lighthouses in the current sea area using the principal component analysis method; determining the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse range and the underwater environmental characteristics; correcting the inertial navigation system according to the current position information of the submersible, and navigating the submersible according to the corrected inertial navigation system. The present invention can improve the calculation efficiency and navigation accuracy.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater vehicle gravity navigation, and particularly to a navigation method and system for an underwater vehicle based on synchronous imaging and gravity beacons. Background Art

[0002] At present, submarine navigation uses gravity matching to assist the inertial navigation system, and preloads the gravity beacon database into the submarine navigation terminal. The gravity anomaly value on the track is measured in real time by an on-board gravimeter, and the gravity anomaly measurement results of the track for a period of time are matched with the preloaded gravity beacon database to obtain the submarine position, which is used to correct the inertial navigation system. When matching with the preloaded gravity beacon database, the conventional search method uses a rectangular area or a circular area as the search area, which will increase unnecessary position point calculations and reduce the matching efficiency. Secondly, if the gravity characteristics of the searched beacon are not obvious or there are no characteristics, the inertial navigation system cannot be accurately corrected. Summary of the Invention

[0003] The purpose of the present invention is to provide a navigation method and system for an underwater vehicle based on synchronous imaging and gravity beacons, which can improve the calculation efficiency and navigation accuracy.

[0004] To achieve the above purpose, the present invention provides the following solutions:

[0005] A navigation method for an underwater vehicle based on synchronous imaging and gravity beacons includes:

[0006] Determine the error ellipse range according to the sea area position of the current sea area where the underwater vehicle is located, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system;

[0007] Determine the level of the gravity beacons within the error ellipse range according to the gravity beacons within the error ellipse range and the gravity beacon database; the gravity beacon database includes the levels of each gravity beacon in the current sea area where the underwater vehicle is located; the levels of each gravity beacon in the current sea area where the underwater vehicle is located are obtained by processing the statistical characteristic parameters of the gravity beacons in the current sea area where the underwater vehicle is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient;

[0008] Determine the current position information of the underwater vehicle according to the level of the gravity beacons within the error ellipse range and the underwater environmental characteristics within the error ellipse range; the position information includes longitude and latitude;

[0009] Correct the inertial navigation system according to the current position information of the underwater vehicle, and navigate the underwater vehicle according to the corrected inertial navigation system.

[0010] Optionally, the determination process of the gravity lighthouse database is as follows:

[0011] Obtain the gravity anomaly values at all points within each gravity lighthouse in the sea area where the submersible is currently located;

[0012] For any one gravity lighthouse, calculate the statistical characteristic parameters of the gravity lighthouse according to the gravity anomaly values at all points within the gravity lighthouse;

[0013] Use the principal component analysis method to process the statistical characteristic parameters of the gravity lighthouse to obtain the comprehensive index of the gravity lighthouse;

[0014] Determine the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse.

[0015] Optionally, before determining the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse, it further includes:

[0016] Perform normalization processing on the comprehensive index of the gravity lighthouse.

[0017] Optionally, determining the current position information of the submersible according to the level of the gravity lighthouse within the error ellipse and the underwater environment characteristics within the error ellipse specifically includes:

[0018] If the level of the gravity lighthouse within the error ellipse is a first-level gravity lighthouse, determine the current position information of the submersible according to the gravity lighthouse within the error ellipse;

[0019] If the level of the gravity lighthouse within the error ellipse is a second-level gravity lighthouse and the time for the inertial navigation system to guide the submersible does not exceed the set time, determine the current position information of the submersible according to the gravity lighthouse within the error ellipse;

[0020] If the level of the gravity lighthouse within the error ellipse is a second-level gravity lighthouse and the time for the inertial navigation system to guide the submersible exceeds the set time, determine the current position information of the submersible according to the level of the gravity lighthouse within the error ellipse and the underwater environment characteristics within the error ellipse;

[0021] If the level of the gravity lighthouse within the error ellipse is a third-level gravity lighthouse, determine the current position information of the submersible according to the level of the gravity lighthouse within the error ellipse and the underwater environment characteristics within the error ellipse.

[0022] A submersible navigation system based on synchronous imaging and gravity lighthouses, which is applied to the above-mentioned submersible navigation method based on synchronous imaging and gravity lighthouses. The submersible navigation system includes:

[0023] An inertial navigation system, a gravity lighthouse database, an underwater environment construction device, and a track display workstation, all of which are arranged on the submersible; the track display workstation includes an error ellipse range determination module, a lighthouse level determination module, a submersible position determination module, and a correction navigation module;

[0024] The inertial navigation system is used to obtain the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system;

[0025] The underwater environment construction device is used to construct underwater environment characteristics;

[0026] The gravity lighthouse database includes the levels of each gravity lighthouse in the current sea area where the submersible is located; the levels of each gravity lighthouse in the current sea area where the submersible is located are obtained by processing the statistical characteristic parameters of the gravity lighthouses in the current sea area where the submersible is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient;

[0027] The error ellipse range determination module is used to determine the error ellipse range according to the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system;

[0028] The lighthouse level determination module is used to determine the levels of the gravity lighthouses within the error ellipse range according to the gravity lighthouses within the error ellipse range and the gravity lighthouse database;

[0029] The submersible position determination module is used to determine the current position information of the submersible according to the levels of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range; the position information includes longitude and latitude;

[0030] The correction navigation module is used to correct the inertial navigation system according to the current position information of the submersible, and navigate the submersible according to the corrected inertial navigation system.

[0031] Optionally, the track display workstation further includes a display module for displaying the track of the submersible.

[0032] According to the specific embodiments provided by the present invention, the following technical effects are disclosed by the present invention: The present invention uses the principal component analysis method to process the statistical characteristic parameters of the gravity lighthouses in the current sea area where the submersible is located to obtain the levels of the gravity lighthouses, determines the error ellipse range according to the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system, and corrects the inertial navigation system according to the levels of the gravity lighthouses within the error ellipse range and the underwater environment, which can improve the calculation efficiency and navigation accuracy. Brief Description of the Drawings

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0034] Figure 1 It is a flowchart of a submersible navigation method based on synchronous imaging and gravity lighthouse provided by an embodiment of the present invention;

[0035] Figure 2 It is a schematic diagram of determining a search area of an error ellipse provided by an embodiment of the present invention;

[0036] Figure 3 It is a schematic diagram of the composition of a submersible navigation system based on synchronous imaging and gravity lighthouse provided by an embodiment of the present invention;

[0037] Figure 4 It is a schematic diagram of a gravity lighthouse;

[0038] Figure 5 It is a schematic diagram of the established underwater environment features. Detailed Description of the Embodiments

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0040] To make the above objects, features, and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0041] Traditional gravity lighthouse navigation depends to a large extent on the severity of the change in the ocean gravity field. In areas with no features or a relatively gentle gravity field, it is very difficult to use gravity matching navigation to reduce the error of the inertial navigation system. There are some obvious stationary objects in the underwater environment, such as coral reefs, buildings, sunken ships, etc. The positions of these obvious objects in the global coordinate system can be used as "lighthouses" to construct an underwater environment feature map while the underwater submersible is navigating by using synchronous imaging technology, which is called generalized gravity lighthouse data. Reasonably relying on this generalized gravity lighthouse data can improve the accuracy of gravity lighthouse navigation.

[0042] An embodiment of the present invention provides a submersible navigation method based on synchronous imaging and gravity lighthouses, including:

[0043] Determine the error ellipse range according to the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system.

[0044] Determine the level of the gravity lighthouses within the error ellipse according to the gravity lighthouses within the error ellipse and the gravity lighthouse database. The gravity lighthouse database includes the levels of each gravity lighthouse in the current sea area where the submersible is located; the levels of each gravity lighthouse in the current sea area where the submersible is located are obtained by processing the statistical characteristic parameters of the gravity lighthouses in the current sea area where the submersible is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient.

[0045] Determine the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse and the underwater environmental characteristics within the error ellipse; the position information includes longitude and latitude.

[0046] Correct the inertial navigation system according to the current position information of the submersible, and navigate the submersible according to the corrected inertial navigation system.

[0047] In practical applications, the determination process of the gravity lighthouse database is as follows:

[0048] Obtain the gravity anomaly values at all points within each gravity lighthouse in the current sea area where the submersible is located.

[0049] For any one gravity lighthouse, calculate the statistical characteristic parameters of the gravity lighthouse according to the gravity anomaly values at all points within the gravity lighthouse.

[0050] Process the statistical characteristic parameters of the gravity lighthouse using the principal component analysis method to obtain the comprehensive index of the gravity lighthouse.

[0051] Determine the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse.

[0052] In practical applications, before determining the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse, it further includes:

[0053] Perform normalization processing on the comprehensive index of the gravity lighthouse. Each lighthouse is gridded, and a lighthouse occupies more than one grid. The maximum and minimum values in the normalization processing refer to the maximum and minimum values of the grids within the same gridded lighthouse. Figure 4 is gridded, and a lighthouse occupies more than one grid. The maximum and minimum values in the normalization processing refer to the maximum and minimum values of the grids within the same gridded lighthouse.

[0054] In practical applications, determining the current position information of the submersible according to the level of the gravity beacon within the error ellipse and the underwater environment characteristics within the error ellipse specifically includes:

[0055] If the level of the gravity beacon within the error ellipse is a first-level gravity beacon, determine the current position information of the submersible according to the gravity beacon within the error ellipse.

[0056] If the level of the gravity beacon within the error ellipse is a second-level gravity beacon and the time for which the inertial navigation system guides the submersible does not exceed the set time, determine the current position information of the submersible according to the gravity beacon within the error ellipse.

[0057] If the level of the gravity beacon within the error ellipse is a second-level gravity beacon and the time for which the inertial navigation system guides the submersible exceeds the set time, determine the current position information of the submersible according to the level of the gravity beacon within the error ellipse and the underwater environment characteristics within the error ellipse.

[0058] If the level of the gravity beacon within the error ellipse is a third-level gravity beacon, determine the current position information of the submersible according to the level of the gravity beacon within the error ellipse and the underwater environment characteristics within the error ellipse.

[0059] An embodiment of the present invention further provides a submersible navigation system applied to the above method, including:

[0060] An inertial navigation system, a gravity beacon database, an underwater environment construction device, and a track display workstation, all of which are arranged on the submersible; the track display workstation includes an error ellipse range determination module, a beacon level determination module, a submersible position determination module, and a correction navigation module.

[0061] The inertial navigation system is used to obtain the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system.

[0062] The underwater environment construction device is used to construct underwater environment characteristics.

[0063] The gravity beacon database includes the levels of each gravity beacon in the current sea area where the submersible is located; the levels of each gravity beacon in the current sea area where the submersible is located are obtained by processing the statistical characteristic parameters of the gravity beacons in the current sea area where the submersible is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient.

[0064] The error ellipse range determination module is used to determine the error ellipse range according to the sea area position of the current location of the submersible, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system.

[0065] The lighthouse level determination module is used to determine the level of the gravity lighthouse within the error ellipse according to the gravity lighthouse within the error ellipse and the gravity lighthouse database.

[0066] The submersible position determination module is used to determine the current position information of the submersible according to the level of the gravity lighthouse within the error ellipse and the underwater environmental characteristics within the error ellipse; the position information includes longitude and latitude.

[0067] The correction navigation module is used to correct the inertial navigation system according to the current position information of the submersible, and navigate the submersible according to the corrected inertial navigation system.

[0068] In practical applications, the track display workstation further includes a display module for displaying the track of the submersible.

[0069] As Figure 1 shown, the embodiment of the present invention further provides a specific submersible navigation method, and the specific steps are as follows:

[0070] The first step: For the sea area where the submersible is currently located, use the PCA (Principal Component Analysis) method to calculate the comprehensive index P of the gravity lighthouse, and at the same time perform normalization processing.

[0071] The second step: Perform hierarchical storage on the gravity lighthouse database. If 0.4 ≤ F q * < 0.6, the continuous area in this interval is stored as a third-level gravity lighthouse; if 0.6 ≤ F q * < 0.8, the continuous area in this interval is stored as a second-level gravity lighthouse; if 0.8 ≤ F q * < 1.0, the continuous area in this interval is stored as a first-level gravity lighthouse. First, perform hierarchical storage, and its level can be queried during subsequent navigation.

[0072] The third step: Establish a covariance model according to the eastward and northward variances of the position indicated by the inertial navigation system, calculate the maximum value E, minimum value F of the position difference, and the direction of the maximum value Determine the error ellipse, and the result is as Figure 2 shown, and let it be used as the search area.

[0073] Step 4: Search for gravity lighthouses within the currently determined error ellipse, determine the current gravity lighthouse level, and determine whether it is a first-level lighthouse. Among them, the process of determining the error ellipse according to the current sea area position of the submersible is obtained from the probability error ellipse in the reference paper: Key Technologies Research on Underwater Gravity Field Aided Navigation and Positioning_Zhang Hongwei; the search process is the same as the conventional (rectangular, circular) search process, that is, with the inertial navigation system as the center, search within the error ellipse range.

[0074] A. If it is a first-level lighthouse, the position information of the current submersible can be determined by using gravity lighthouse navigation for surface matching at any navigation time period.

[0075] B. If it is not a first-level lighthouse, determine whether it is a second-level lighthouse.

[0076] i. If it is a second-level lighthouse, determine whether the time for the inertial navigation system to guide the submersible exceeds the effective time of the inertial navigation system.

[0077] a. If it does not exceed the effective time, use this lighthouse for gravity lighthouse surface matching.

[0078] b. If it exceeds the effective time, use the shipborne synchronous imaging technology to establish a real-time underwater environmental feature map within the current search area, and use the underwater environmental features and the second-level lighthouse to determine the position information of the current submersible.

[0079] ii. If it is not a second-level lighthouse, it can only be a third-level lighthouse. Since the gravity characteristics of the third-level lighthouse are not as obvious as those of the first-level and second-level lighthouses, directly use the shipborne synchronous imaging technology to establish a real-time underwater environmental feature map within the current search area, and use the underwater environmental features and the third-level lighthouse to determine the position information of the current submersible.

[0080] Step 5: Calibrate the inertial navigation system according to the position information of the current submersible.

[0081] Step 6: Navigate the submersible according to the calibrated inertial navigation system.

[0082] In practical applications, Step 3 is specifically as follows:

[0083] 1. Establish a covariance model according to the eastward variance and northward variance of the position indicated by the inertial navigation system:

[0084] where σ EN and σ NE are equal, representing the covariance of the eastward and northward directions.

[0085] 2. Determine the maximum value E, minimum value F, and direction of the maximum value of the position difference according to the covariance model as follows:

[0086]

[0087]

[0088]

[0089] 3. Based on the calculated maximum value E, minimum value F of the bit difference and the direction of the maximum value Determine the error ellipse and use it as the search area.

[0090] In practical applications, such as Figure 4 shown, first grid all the lighthouses separately into a 12*12 grid, and then number the grids occupied by the lighthouses from left to right and from top to bottom. q refers to the number of the grid occupied by the lighthouse. The lighthouse grading method is as follows:

[0091] 1. Calculate the standard deviation of the lighthouse grid, Figure 4 as shown, the lighthouse occupies a total of 66 grids, that is, σ q , q = 1, 2,..., 66. The standard deviation σ is a commonly used statistical distribution measurement parameter. σ can measure the degree of dispersion of the data sequence. The larger σ is, the more obvious the gravity fluctuation change in this area. The calculation formula is:

[0092]

[0093]

[0094] 2. Calculate the roughness of the lighthouse grid, a total of 66, that is, r q , q = 1, 2,..., 66. The roughness r is a measure of the smoothness of the surface of the curved surface. The larger r is, the greater the gravity anomaly change in the gravity field. The calculation formula is:

[0095]

[0096]

[0097]

[0098] 3. Calculate the correlation coefficient of the lighthouse grid, a total of 66, that is, R q , q = 1, 2,..., 66. The correlation coefficient R reflects the linear correlation degree of the gravity anomaly sequences of adjacent points; the smaller R is, the smaller the correlation degree of adjacent points and the greater the gravity anomaly change. The calculation formula is:

[0099]

[0100]

[0101]

[0102] 4. Calculate the lighthouse grid slopes, a total of 66, i.e., S q , where q = 1, 2,..., 66. The slope S is the angle between the normal direction and the vertical direction at a certain point on the gravity field surface. The larger S is, the greater the gravity anomaly change. The calculation formula is:

[0103]

[0104]

[0105]

[0106] 5. Calculate the skewness coefficients of the lighthouse grid, a total of 66, i.e., C sq , where q = 1, 2,..., 66. The skewness coefficient C S is a statistical parameter that describes the degree of asymmetry of the data distribution within the statistical region. The larger the absolute value of C S , the greater the skewness of the data sequence and the greater the gravity anomaly change. The calculation formula is:

[0107]

[0108] 6. Calculate the kurtosis coefficients of the lighthouse grid, a total of 66, i.e., C eq , where q = 1, 2,..., 66. The kurtosis coefficient C e is a statistical parameter that describes whether the data shape within the statistical region is steep or flat. The larger the absolute value of C e , the steeper the kurtosis of the data and the greater the gravity anomaly change. The calculation formula is:

[0109]

[0110]

[0111] Among them, m and n are the longitude and latitude spans of the gravity field region, g(i, j) represents the gravity anomaly value at the grid point, represents the mean value of the gravity anomaly.

[0112] 7. Calculate the comprehensive gravity lighthouse index, i.e., P, according to the statistical characteristic parameters by the PCA method; normalize the comprehensive gravity lighthouse index:

[0113] 8. If 0.4 ≤ F q * < 0.6, then the gravity lighthouses in this interval are stored as third-level gravity lighthouses; if 0.6 ≤ F q *< 0.8, the continuous region in this interval is stored as a secondary gravity lighthouse; if 0.8 ≤ Fq * < 1.0, the continuous region in this interval is stored as a primary gravity lighthouse, Fq * is the sum of all of the lighthouse.

[0114] In practical applications, the principal component analysis (PCA) adopts the mathematical idea of dimensionality reduction to transform multi-attributes into uncorrelated comprehensive attributes. Its mathematical model is as follows:

[0115] Y s = a sp SX p T

[0116]

[0117] where a sp (s < p = 1, 2,... 6) is the eigenvector corresponding to the eigenvalue of the covariance matrix of X p T . SX p T is obtained after X p T is standardized, which is to eliminate the influence brought by the non-uniformity of the original index dimensions. Generally speaking; s < 6, which also means that the original index is simplified into a lower-dimensional and more refined index Y s . The specific steps for the PCA method to determine the comprehensive index P are as follows:

[0118] 1. Select any number of the standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient as the original index X according to actual needs p T .

[0119] 2. Standardize the original index and calculate its covariance matrix.

[0120] 3. Calculate the eigenvalues and eigenvectors of the covariance matrix, and select the index with an eigenvalue greater than 1 as the principal component.

[0121] 4. Determine the coefficient of the principal component equation based on the eigenvalue and eigenvector, and divide the index by the square root of the corresponding eigenvalue λ s to obtain the coefficient b , and the principal component equation is expressed as: sp

[0122] 5. Through the ratio of the eigenvalue corresponding to each index to the sum of the eigenvalues​ Multiply by b sp Determine the conversion coefficients, and then add the coefficients of the same index to obtain the final coefficient c p , and the final comprehensive index expression is: where a sp (s < p = 1, 2,... 6) is the eigenvector corresponding to the eigenvalue of the covariance matrix of X p T ; SX p T is obtained after X p T is standardized, and X p T refers to the evaluation matrix composed of the calculated values of the selected original indicators.

[0123] In practical applications, the steps for synchronous imaging are as follows:

[0124] 1. Use an underwater environment imaging device (lidar sensor and underwater feature extractor) to extract underwater stationary objects as two-dimensional point features. Among them, the underwater feature extractor is equivalent to a computer, which is used to extract the environmental features detected by the lidar using the synchronous imaging method.

[0125] 2. Calculate the moment m pq of the feature image block and find the centroid C. The moment m pq of the image block has features of translation, rotation, and scale invariance, which can be used to identify the image and then find the centroid C of the image block. The calculation formula is:

[0126]

[0127]

[0128] where x and y are the horizontal and vertical coordinates, B is the matrix representing the rows and columns of the image block, and I(x, y) is the image; m 10 , m 01 are the first-order moments of the image about the x-axis and y-axis.

[0129] 3. Connect the geometric center and the centroid of the image block to obtain a direction vector, and then sequentially find the direction vectors of other said environmental feature image blocks.

[0130] 4. Establish a marine environmental feature map based on the estimated trajectory, the positions of the two-dimensional point features, and the position information, and the result is as Figure 5 shown.

[0131] An embodiment of the present invention further provides a more specific underwater vehicle navigation system, which mainly consists of six parts: a gravity measurement instrument, a position calculation center, a gravity lighthouse database, an underwater environment construction device, an inertial navigation system, and a track display workstation. All six devices are installed on the underwater vehicle.

[0132] The gravity measurement instrument is mainly used to measure the gravity anomaly data of the underwater vehicle's navigation position in real time. There are absolute gravimeters and relative gravimeters. The former measures the gravitational acceleration, and the latter measures the relative value of the gravitational acceleration, which is the gravity anomaly.

[0133] The gravity lighthouse database is used to store pre-made gravity lighthouse data. The gravity lighthouse data extracts the ranges with obvious gravity characteristics as gravity lighthouses, including lighthouse numbers, longitudes, latitudes, and gravity anomaly values.

[0134] The underwater environment construction device consists of a lidar sensor and an underwater feature extractor, and is used to construct the underwater environmental characteristics near the secondary lighthouses and tertiary lighthouses.

[0135] The inertial navigation system consists of an accelerometer and a gyroscope, and is used to measure the acceleration of the underwater vehicle. The pose information of the underwater vehicle is obtained through integration. The pose includes position and attitude. Its position error has drift accumulation, and the current eastward and northward variances can be obtained according to its current position error.

[0136] The position calculation center is used to receive the gravity anomaly data measured in real time by the gravity measurement instrument and the current position information of the inertial navigation system, and also query the gravity lighthouse data and the re-constructed generalized gravity lighthouse data of the current position in the gravity lighthouse database, and perform comparison and calculation with the measured gravity anomaly data.

[0137] The track display workstation is used to visualize the final matching track. The system composition is as Figure 3 shown.

[0138] The operation process of the underwater vehicle navigation system is as follows:

[0139] First, use the PCA (Principal Component Analysis) method to express the statistical characteristic parameters of the gravity lighthouses (calculated based on the gravity anomaly data) as comprehensive indicators. Secondly, use the comprehensive indicators to classify the gravity lighthouses in the gravity lighthouse database; obtain the current position information of the underwater vehicle and the current eastward and northward variances of the inertial navigation system through the inertial navigation system While obtaining the position information, the gravity measurement instrument also measures the gravity anomaly data at that position in real time; according to the position indicated by the current inertial navigation system and the position error estimation, where the position error estimation can be obtained based on the cumulative drift error of the inertial navigation system during the navigation duration, and the cumulative drift error per hour is provided on the nameplate of the inertial navigation system. By setting the error ellipse search range, the target lighthouse is determined in the gravity lighthouse database; after obtaining the target lighthouse, the target lighthouse level is determined according to the gravity lighthouse grading criteria; if the target lighthouse does not meet the navigation standard, the underwater environment construction device is activated to establish the marine environment feature map within the current search area; the constructed marine environment feature map and the target gravity lighthouse are used together with the gravity anomaly data measured in real time by the gravity measurement instrument to determine the position information of the current submersible; finally, the inertial navigation system is corrected according to the position information of the current submersible; the submersible is continued to be navigated using the corrected inertial navigation system.

[0140] The submersible navigation system provided by the embodiment of the present invention makes up for the defect of low navigation accuracy of gravity lighthouse navigation in areas with small gravity anomaly differences or unobvious gravity characteristics, provides an accurate gravity lighthouse database for the rapid navigation of submarines, reduces the search range of gravity lighthouses, reduces the calculation amount, increases the real-time performance, improves the lighthouse matching efficiency, and thus overall improves the auxiliary navigation ability of gravity lighthouse navigation.

[0141] The present invention has the following advantages compared with the prior art:

[0142] 1. Given that it is difficult to accurately pre-draw the gravity reference map for some sea areas, and even if a high-precision reference map is pre-drawn, due to the dynamic changes of the ocean and its erosion of geophysical characteristics, the gravity reference map may not always meet the application requirements of gravity lighthouses. Therefore, the synchronous imaging technology is proposed to extract the underwater environment characteristics to establish a generalized gravity reference map, achieving the purpose of providing an accurate gravity lighthouse database for the rapid navigation of submarines.

[0143] 2. The principal component analysis method is used to convert a variety of gravity characteristic parameters into a comprehensive index to measure the gravity field adaptability, which is more conducive to screening out gravity lighthouse data with obvious and rich characteristics.

[0144] 3. Although using the conventional method to determine the search area ensures that the track falls within the search area, it increases unnecessary position point calculations, reduces the matching efficiency. However, determining the search area by the error ellipse not only ensures that the track falls within the search area but also reduces the calculation amount, increases the real-time performance, and further improves the gravity lighthouse navigation efficiency.

[0145] The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments. For the same or similar parts among the various embodiments, reference can be made to each other. For the system disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple. For the relevant parts, reference can be made to the description in the method section.

[0146] Specific examples are used in this article to elaborate on the principles and implementation manners of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those of ordinary skill in the art, according to the idea of the present invention, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation on the present invention.

Claims

1. A submersible navigation method based on synchronous imaging and gravity lighthouse, characterized in that, Including: Determine the error ellipse range according to the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system; Determine the level of the gravity lighthouses within the error ellipse range according to the gravity lighthouses within the error ellipse range and the gravity lighthouse database; The gravity lighthouse database includes the levels of each gravity lighthouse in the current sea area where the submersible is located; the levels of each gravity lighthouse in the current sea area where the submersible is located are obtained by processing the statistical characteristic parameters of the gravity lighthouses in the current sea area where the submersible is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient; Determine the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range; the position information includes longitude and latitude; Calibrate the inertial navigation system according to the current position information of the submersible, and navigate the submersible according to the calibrated inertial navigation system.

2. The underwater vehicle navigation method based on synchronous imaging and gravity lighthouse according to claim 1, characterized in that The determination process of the gravity lighthouse database is as follows: Obtain the gravity anomaly values at all points within each gravity lighthouse in the current sea area where the submersible is located; For any one gravity lighthouse, calculate the statistical characteristic parameters of the gravity lighthouse according to the gravity anomaly values at all points within the gravity lighthouse; Process the statistical characteristic parameters of the gravity lighthouse using the principal component analysis method to obtain the comprehensive index of the gravity lighthouse; Determine the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse.

3. The underwater vehicle navigation method based on synchronous imaging and gravity lighthouse according to claim 2, characterized in that, Before determining the level of the gravity lighthouse according to the comprehensive index of the gravity lighthouse, it further includes: Perform normalization processing on the comprehensive index of the gravity lighthouse.

4. A submersible navigation method based on synchronous imaging and a gravity lighthouse according to claim 1, characterized in that, The determining the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range specifically includes: If the level of the gravity lighthouses within the error ellipse range is a first-level gravity lighthouse, determine the current position information of the submersible according to the gravity lighthouses within the error ellipse range; If the level of the gravity lighthouses within the error ellipse range is a second-level gravity lighthouse and the time for the inertial navigation system to guide the submersible does not exceed the set time, determine the current position information of the submersible according to the gravity lighthouses within the error ellipse range; If the level of the gravity lighthouses within the error ellipse range is a second-level gravity lighthouse and the time for the inertial navigation system to guide the submersible exceeds the set time, determine the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range; If the level of the gravity lighthouses within the error ellipse range is a third-level gravity lighthouse, determine the current position information of the submersible according to the level of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range.

5. A submersible navigation system based on synchronous imaging and gravity lighthouse, characterized in that, Applied to the submersible navigation method based on synchronous imaging and gravity lighthouses according to any one of claims 1-4, the submersible navigation system based on synchronous imaging and gravity lighthouses includes: An inertial navigation system, a gravity lighthouse database, an underwater environment construction device, and a track display workstation, all of which are set on the submersible; the track display workstation includes an error ellipse range determination module, a lighthouse level determination module, a submersible position determination module, and a correction navigation module; The inertial navigation system is used to obtain the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system; The underwater environment construction device is used to construct underwater environment characteristics; The gravity lighthouse database includes the levels of each gravity lighthouse in the current sea area where the submersible is located; the levels of each gravity lighthouse in the current sea area where the submersible is located are obtained by processing the statistical characteristic parameters of the gravity lighthouses in the current sea area where the submersible is located using the principal component analysis method; the statistical characteristic parameters include standard deviation, roughness, correlation coefficient, slope, kurtosis coefficient, and skewness coefficient; The error ellipse range determination module is used to determine the error ellipse range according to the sea area position of the submersible in the current sea area, the eastward variance of the position indicated by the inertial navigation system, and the northward variance of the position indicated by the inertial navigation system; The lighthouse level determination module is used to determine the levels of the gravity lighthouses within the error ellipse range according to the gravity lighthouses within the error ellipse range and the gravity lighthouse database; The submersible position determination module is used to determine the current position information of the submersible according to the levels of the gravity lighthouses within the error ellipse range and the underwater environment characteristics within the error ellipse range; the position information includes longitude and latitude; The correction navigation module is used to correct the inertial navigation system according to the current position information of the submersible, and navigate the submersible according to the corrected inertial navigation system.

6. The underwater vehicle navigation system based on synchronous imaging and gravity lighthouse according to claim 5, characterized in that, The track display workstation further includes a display module for displaying the track of the submersible.

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