A method for identifying curves based on longitude and latitude data of inland ships

Abstract

The invention discloses a curve identification method based on the longitude and latitude data of an inland river ship, belongs to the field of ship energy, and is used to solve the problem of fully automatic identification of curves in inland river ship routes. The longitude and latitude data are segmented, and the longitude and latitude data corresponding to the index are projected into plane coordinates; polynomial fitting is performed on the plane coordinates; according to the polynomial fitting result of the plane coordinates, the curvature radius of the plane coordinates of the longitude and latitude data corresponding to the index is calculated; according to the curvature radius of the plane coordinates of the longitude and latitude data corresponding to the index, the inland river ship turning speed drop corresponding to the curvature radius is calculated; according to the inland river ship turning speed drop, the curve of the longitude and latitude data corresponding to the index is marked, and the effect is to automatically and accurately identify the navigation curve through the longitude and latitude data of the inland river ship.

Description

Technical Field

[0001] The invention belongs to the field of ship energy management, and in particular relates to a curve identification method for route segmentation in the early stage of inland river ship speed optimization in an energy management method. Background Art

[0002] As the world's energy is becoming increasingly depleted and global greenhouse gas emissions are increasing, energy conservation and emission reduction are important themes of the current era. As a means of transporting bulk commodities, ships account for more than 80% of the world's total trade and play an important supporting role in international trade and regional economic development. However, ships are also considered to be the largest contributor to fuel consumption in the transportation industry. According to relevant research, reducing the ship's sailing speed by 2 to 3 knots on the basis of the design speed will greatly reduce the ship's fuel consumption and reduce operating costs. Therefore, speed optimization is a simpler and more efficient way to improve ship energy efficiency.

[0003] For inland vessels, the routes are basically fixed and highly repetitive, and the hydrological periodicity of inland rivers varies significantly. Especially for container ships and bulk cargo transportation, the demand is stable and the delivery time is stable. Therefore, it is of great significance to optimize the management of reducing the speed of inland vessels on fixed routes. Under fixed routes, while meeting the requirements of the voyage period, through the optimization management of the speed, the goal of minimizing the total fuel consumption of the voyage and the least carbon dioxide emissions can be achieved, thereby achieving the goal of energy conservation and emission reduction of inland vessels and reducing fuel costs.

[0004] Based on this, the optimization management of reducing the speed of inland ships under fixed routes requires the support of route segmentation in the early stage of inland ship speed optimization. Among them, inland river bend identification is an important technical route for support. For more accurately identified bends, ships are required to slow down when turning, which not only improves the safety of ships when turning, but also can optimize the management of reducing speed according to the bend conditions. In the past, scholars usually used manual segmentation according to the cities passed through in the route segmentation of inland river ship route optimization: for example, the route from Wuhan to Shanghai is divided into Wuhan to Jiujiang section, Jiujiang to Nanjing section and Nanjing to Shanghai section. Or it is manually segmented according to the bends in the route map. In this way, inland river bend identification usually requires manual marking, the marking efficiency is not high, and the accuracy is greatly affected by subjective factors. Summary of the invention

[0005] In order to solve the problem of fully automatic identification of curves in inland river ship routes, a curve identification method based on inland river ship latitude and longitude data according to some embodiments of the present application includes:

[0006] Step 1: Set the indexes of N sequential longitude and latitude data obtained through navigation to be from 0 to N-1;

[0007] Step 2: According to the latitude and longitude data of the starting index i, the latitude and longitude data are segmented, and the segmentation results include the latitude and longitude data corresponding to the index i and the index j and all the indexes between the index i and the index j;

[0008] Step 3: Project the longitude and latitude data corresponding to index i and index j and all indexes between index i and index j into plane coordinates, where the index of the plane coordinates is the same as the index of the longitude and latitude data;

[0009] Step 4: Perform polynomial fitting on the plane coordinates;

[0010] Step 5: Determine index numbers k and l according to the serial numbers i and j of index i and index j; calculate the curvature radius of the plane coordinates of the longitude and latitude data corresponding to index k and index l and all indexes between index k and index l through the polynomial fitting result of the plane coordinates;

[0011] According to the curvature radius of the plane coordinates of the longitude and latitude data corresponding to the index k and the index l and all the indexes between the index k and the index l, the speed drop of the inland river ship turning corresponding to the curvature radius is calculated;

[0012] Mark the curves of the longitude and latitude data corresponding to index k and index l and all indexes between index k and index l according to the drop value of the turning speed of the inland river ship;

[0013] Step 6: Re-determine the starting index i according to the sequence numbers i and j of the index i and the index j, wherein the mark sequence number of the re-determined starting index is greater than the mark sequence number of the starting index;

[0014] Step 7: Repeat steps 2 to 6 until all the curve markings of the latitude and longitude data are completed.

[0015] According to the curve recognition method based on inland river vessel longitude and latitude data in some embodiments of the present application, the segmentation method of step 2 includes:

[0016] Starting from the latitude and longitude data of the starting index i, the serial number of index j increases from i+1. Each time it increases, the difference between the minimum longitude and the maximum longitude of the latitude and longitude data corresponding to all indexes from index i to index j is checked, where the value of the difference between the minimum longitude and the maximum longitude is set to x, the minimum fixed number is y, and the maximum fixed number is z;

[0017] S2.1. If the difference between the minimum longitude and the maximum longitude is greater than x degrees, the serial number of index j stops increasing. At this time, if j-i is less than y, the serial number j=i+y. If j-i is greater than y, no operation is performed, and the serial number of index j is obtained;

[0018] If the difference between the minimum longitude and the maximum longitude is not greater than x degrees, the serial number of index j continues to increase until the difference between the minimum longitude and the maximum longitude is greater than x degrees, then the serial number of index j stops increasing. At this time, if j-i is less than y, the serial number j=i+y. If j-i is greater than y, no operation is performed, and the serial number of index j is obtained.

[0019] If the index number of index j increases to more than i+z but still does not satisfy that the difference between the minimum longitude and the maximum longitude is greater than x degrees, the index number of index j stops increasing and the index number j=i+z, and the index number of index j is obtained;

[0020] S2.2. Calculate the serial number of the obtained index j and the serial number of the starting index i, and use the remainder of (ji)÷3 to increase or decrease the serial number j or keep it unchanged, so that (j-i) can be divided by 3, and get the serial number of the final index j, thereby obtaining the longitude and latitude data corresponding to all the indexes including index i and index j and between index i and index j.

[0021] According to the curve recognition method based on the longitude and latitude data of inland waterway ships in some embodiments of the present application, the method of projecting the longitude and latitude data corresponding to the index i and the index j and all the indexes between the index i and the index j into plane coordinates in step 3 includes:

[0022] S3.1. Extract the minimum longitude and maximum longitude of all longitude and latitude data from index i and index j after segmentation and between index i and index j;

[0023] S3.2. Set the central meridian of the projection zone in the Gauss-Krüger projection equal to one-half times the sum of the minimum and maximum longitudes;

[0024] S3.3. Project the longitude and latitude data of index i and index j and between index i and index j into plane coordinates (x, y) through the central meridian.

[0025] According to the curve identification method based on inland river vessel longitude and latitude data in some embodiments of the present application, the method of performing polynomial fitting on the plane coordinates in step 4 includes:

[0026] S4.1. performing a translation operation on the plane coordinates (x, y) of the projection of the latitude and longitude data of index i and index j and between index i and index j on the central meridian;

[0027] S4.2. Perform polynomial fitting on the plane coordinates (x, y) after the translation operation by four methods: abcd:

[0028] a. directly performing polynomial fitting on the plane coordinates (x, y) after the translation operation;

[0029] b. performing polynomial fitting after exchanging the x and y values ​​of the plane coordinates (x, y) after the translation operation;

[0030] c. Rotate the plane coordinates (x, y) after the translation operation 45 degrees to the right along the origin of the coordinate system and then perform polynomial fitting;

[0031] d. Rotate the plane coordinates (x, y) after the translation operation 45 degrees to the left along the origin of the coordinates and then perform polynomial fitting;

[0032] S4.3. Calculate the R-squared of the fitting results of the four methods abcd, and select the fitting result with the largest R-squared as the final fitting result. If the largest fitting result in the R-squared is qualified, proceed to step 5; if the largest fitting results in the R-squared are all unqualified, proceed to the fifth method for polynomial fitting:

[0033] e. Starting from the plane coordinates (x, y) after the translation operation, the coordinate points are rotated clockwise by 30 degrees with the coordinate origin as the center, generating a total of 12 sets of plane coordinates, and performing polynomial fitting on each set of plane coordinates to obtain 12 sets of fitting results;

[0034] S4.4. Calculate the R-squared of the 12 groups of fitting results in method e, select the fitting result with the largest R-squared as the final fitting result, and if the largest fitting result in the R-squared is qualified, proceed to step 5; if the largest fitting result in the R-squared is unqualified, the fitting fails, and select the largest fitting result in the R-squared in the fitting results to proceed to step 5.

[0035] According to the curve identification method based on the latitude and longitude data of inland vessels in some embodiments of the present application, the step S4.1 specifically includes subtracting the x minimum value and the y minimum value in this segment from the x and y values ​​of the plane coordinates (x, y) projected by the latitude and longitude data between index i and index j, and then adding 10 to each of them, so that the plane coordinates of this segment are translated closer to the coordinate origin;

[0036] The method of rotating the plane coordinates (x, y) after the translation operation to the right by 45 degrees along the coordinate origin in step S4.2 includes:

[0037] First convert the Cartesian coordinates (x, y) to polar coordinates (ρ, θ);

[0038] Then add π / 4 to θ in the polar coordinates;

[0039] Then the polar coordinates are converted to Cartesian coordinate (x, y) values;

[0040] Finally, the x and y values ​​of each coordinate are subtracted from the minimum x and y values ​​of all coordinates to ensure that all values ​​are positive;

[0041] The method of rotating the plane coordinates (x, y) after the translation operation to the left by 45 degrees along the coordinate origin in step S4.2 includes:

[0042] First convert the Cartesian coordinates (x, y) to polar coordinates (ρ, θ);

[0043] Then subtract π / 4 from θ in the polar coordinates;

[0044] Then the polar coordinates are converted to Cartesian coordinate (x, y) values;

[0045] Finally, the x and y values ​​of each coordinate are subtracted from the minimum x and y values ​​of all coordinates to ensure that all values ​​are positive.

[0046] According to the curve identification method based on inland ship longitude and latitude data in some embodiments of the present application, the fitting result evaluation index uses the R-squared determination coefficient, and an R-squared greater than 0.999 indicates that the fitting is qualified;

[0047] The polynomial fitting is specifically as follows: starting from the 5th order polynomial fitting, if the fitting result R square is qualified, the polynomial fitting is terminated; if the fitting result R square is unqualified, the polynomial order is increased by one, and fitting is performed again, and the fitting is terminated if the fitting result R square is qualified; if the polynomial order is increased to 20, and the fitting result R square is still unqualified, the polynomial fitting is forced to end.

[0048] According to the curve identification method based on inland ship longitude and latitude data in some embodiments of the present application, the method of determining index numbers k and l according to index numbers i and j in step 5 includes:

[0049] When the sequence number of the starting index i is equal to 0, it means that this segment is the starting segment. At this time, the sequence number of index k is equal to the sequence number of index i, which is equal to 0, and the sequence number of index l is equal to i+(ji)÷3×2;

[0050] When the sequence number of index j is greater than or equal to N-1, it means that this segment is the end segment. At this time, the sequence number of index k is equal to the sequence number of index l in the previous iteration, and the sequence number of index l in this iteration is equal to N-1;

[0051] When the sequence number of index i and the sequence number of index j do not meet the above two conditions, it means that this segment is an intermediate segment. At this time, the sequence number of index k is equal to the sequence number of index l in the previous iteration, and the sequence number of index l in this iteration is equal to i+(ji)÷3×2.

[0052] According to the curve identification method based on the latitude and longitude data of inland vessels in some embodiments of the present application, the method of calculating the inland vessel turning speed drop corresponding to the curvature radius in step 5 according to the curvature radius of the plane coordinates of the latitude and longitude data corresponding to index k and index l and all indexes between index k and index l, includes:

[0053] According to the maximum fitting result in the qualified R-squared in step step, calculate the curvature radius of each plane coordinate of the latitude and longitude data corresponding to index k to index l;

[0054] The specific value of the speed drop corresponding to the radius of curvature is calculated by the Filtsov speed drop formula, and this value is used as the curve mark of the longitude and latitude data corresponding to the plane coordinate point, where the Filtsov speed drop formula is:

[0055]

[0056] Where: V c is the speed of the ship during the turning process; V0 is the initial speed of the ship's turning, R is the turning curvature radius, and L is the length of the ship.

[0057] According to the curve identification method based on the latitude and longitude data of inland vessels in some embodiments of the present application, the closer the specific value of the speed drop is to 1, the larger the radius of curvature of the curve, the closer it is to a straight line, and the smaller the resistance to turning; the smaller the specific value of the speed drop is, the smaller the radius of curvature of the curve, the greater the resistance to turning, and the more speed must be reduced to turn.

[0058] According to the curve identification method based on the latitude and longitude data of inland vessels in some embodiments of the present application, the method for redetermining the starting index i according to the serial numbers i and j of index i and index j in step 6 includes calculating the serial numbers of index i and index j in the current iteration, and increasing the serial number of the redetermined starting index i by (ji) ÷ 3.

[0059] Beneficial effects:

[0060] The present invention divides the segments by longitude difference to ensure that the deformation of subsequent projections can be controlled within a very small range.

[0061] The segmentation strategy of the present invention, which mainly adopts the fixed longitude difference method and supplemented by the fixed number method, ensures that a few inland river routes in the north-south direction (directions with small longitude changes) can also be successfully segmented. By adjusting the longitude difference and the maximum and minimum number of segments, it can adapt to navigation data with different collection frequencies and routes with too many bends.

[0062] The present invention uses half of the sum of the maximum and minimum values ​​of each longitude segment as the central meridian to form a local Gauss Krüger projection band instead of using a standard projection band, thereby further reducing the deformation of the Gauss Krüger projection.

[0063] The present invention performs polynomial fitting through five methods, abcde, and greatly improves the success rate of polynomial fitting under the premise of ensuring that the route has no deformation.

[0064] The present invention greatly improves the calculation speed while ensuring the success rate through a specific polynomial fitting method.

[0065] The present invention calculates the curvature radius of the middle portion of each section without considering the two ends, thereby eliminating the special situation that the curve appears at the two ends of a section and causes inaccurate fitting and curvature radius calculation.

[0066] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0067] Figure 1 A basic flow chart.

[0068] Figure 2 This is a longitude and latitude data chart for a certain voyage.

[0069] Figure 3 This is the first segmented route map.

[0070] Figure 4 This is the projection result of the first segment of longitude and latitude coordinates.

[0071] Figure 5 This is the fitting result diagram of the four methods of the first segmentation abcd.

[0072] Figure 6 Label the result graph for using the speed drop value.

[0073] Figure 7 This is the route map of the curve recognition result.

[0074] Figure 8 It is the determination of the specific serial number values ​​of index k and index l and the iteration diagram of index i. DETAILED DESCRIPTION

[0075] The following describes the embodiments of the present application in detail with reference to the accompanying drawings. Examples of the embodiments are shown in the accompanying drawings. The present invention proposes a channel bend recognition method based on inland ship navigation data. In the method, longitude and latitude data are obtained during a certain voyage. For the convenience of explanation, N represents the number of longitude and latitude data. The indexes of each longitude and latitude data are from 0 to N-1 in sequence. In the present invention, for index i, it can be understood as an index with a sequence number of i, and i represents the sequence number of index i. According to the longitude and latitude data, the bend recognition method includes the following steps:

[0076] Step 1: Segment all longitude and latitude data in a specific way, and the segmentation result is the longitude and latitude data between index i and index j. In the preferred scheme, in step 1, segmentation is performed mainly by a fixed longitude difference method and supplemented by a fixed number method. Specifically, when the number of segmented data intercepted by the fixed longitude difference method is too large or too small, it is automatically converted to a fixed number method for segmentation. Among them, the route curve characteristics are manifested in the size and density of the curves in the route. The smaller and denser the curves are, the longeritude difference value should be appropriately reduced, and the maximum and minimum number values ​​should be appropriately reduced at the same time to ensure that there are not too many curves in the intercepted section, which will cause the inability to fit the polynomial; the higher the frequency of longitude and latitude data collection, the shorter the actual length of a section of the route intercepted under the same number. At this time, the maximum and minimum number values ​​should be appropriately increased at the same time to ensure that the actual length of the intercepted section of the route does not change much; the smaller the Gauss Kruger projection deformation is required, the smaller the longitude difference value is, and vice versa. In the preferred embodiment, the longitude difference of each segment is set to 0.1 degree, and the fixed number is set to a minimum of 33 and a maximum of 99. It can be understood that the setting parameters can be appropriately adjusted according to the longitude and latitude data of different acquisition frequencies and the Gauss Kruger projection deformation requirements.

[0077] First, each segment of longitude and latitude data is intercepted by a fixed longitude difference. The segmentation starts from the longitude and latitude data of the i-th index, and the index j's serial number increases from i+1. Each time it increases, the difference between the minimum and maximum longitudes of all data between index i and index j is checked. If the longitude difference is greater than 0.1 degrees, the serial number j of index j stops increasing. At this time, if j-i is less than 33, j=i+33 is forced. If j-i is greater than 33, no operation is performed. If the longitude difference is not greater than 0.1 degrees, the serial number j of index j continues to increase until the longitude difference requirement is met. If the serial number j of index j increases to more than i+99 and still does not meet the longitude difference requirement, the serial number j of index j stops increasing and j=i+99 is forced. Finally, through the remainder of (ji)÷3, the serial number j of index j is increased or decreased by one or remains unchanged, ensuring that (j-i) can be divided by 3. The segmentation ends and starts step 2.

[0078] Step 2: Project the longitude and latitude data between index i and j into plane coordinates by Gauss Kruger projection method, and the plane coordinates are the same as the index of the corresponding longitude and latitude data. In the preferred embodiment, the specific content of step 2 includes extracting the minimum longitude and maximum longitude of all longitude and latitude data between index i and index j after segmentation in step 1, and setting the central meridian of the projection zone in the Gauss Kruger projection equal to one-half multiplied by the sum of the minimum and maximum longitudes. Then project the longitude and latitude data between index i and index j into plane coordinates (x, y) through this central meridian.

[0079] Step 3: Perform polynomial fitting on the plane coordinates in a specific manner. In the preferred embodiment, the specific contents of step 3 include:

[0080] First, translate a segment of plane coordinates (x, y) output from step 2: subtract the minimum x and y values ​​in the segment from the x and y values ​​of all coordinates, and then add 10 to each, so that the entire segment of plane coordinates is translated closer to the origin of the coordinates, which is conducive to the polynomial fitting effect. The R-squared determination coefficient is used as the evaluation index for the fitting result. An R-squared greater than 0.999 indicates a qualified fit.

[0081] Then perform polynomial fitting using four methods: abcd:

[0082] Directly perform polynomial fitting according to the original plane coordinates (x, y);

[0083] Swap the values ​​of x and y for the entire segment (i.e., mirror them along the line y=x) and then perform polynomial fitting;

[0084] The entire original plane coordinate (x, y) is rotated 45 degrees to the right along the origin of the coordinate system and then a polynomial fitting is performed;

[0085] The entire original plane coordinate (x, y) is rotated 45 degrees to the left along the coordinate origin and then a polynomial fitting is performed.

[0086] The specific operation of plane coordinate rotation is: first convert the Cartesian coordinate (x, y) value to polar coordinate (ρ, θ), then add or subtract π / 4 from θ in the polar coordinate, and then convert the polar coordinate to Cartesian coordinate (x, y) value, and finally subtract the minimum x value and the minimum y value of all coordinates from the x and y values ​​of each coordinate and then add 10 to ensure that all values ​​are positive.

[0087] The specific method of polynomial fitting is: start from the 5th order polynomial fitting, if the fitting result R square is qualified, then end the polynomial fitting; if the fitting result R square is not qualified, then increase the polynomial order by one, fit again, and end if the fitting result R square is qualified; if the polynomial order is increased to 20, and the fitting result R square is still not qualified, then force the polynomial fitting to end. It can be understood that the specific method of polynomial fitting can be used for any polynomial fitting of a~e.

[0088] Then calculate the R-squared of the fitting results of the four methods abcd, select the fitting result with the largest R-squared as the final fitting result, and if the largest R-squared is qualified, start step 4. If the R-squared of the fitting results of the four methods are not qualified, perform an additional fifth method e polynomial fitting:

[0089] Starting from the original plane coordinates (x, y), the coordinate points are rotated clockwise by 30 degrees to generate a total of 12 sets of plane coordinates, and a polynomial fitting is performed on each set of plane coordinates.

[0090] Finally, calculate the R-square of the 12 groups of fitting results in method e, select the fitting result with the largest R-square as the final fitting result, and if the largest R-square is qualified, start step 4. If the largest R-square is still unqualified, print out the best fitting result graph and prompt "fitting failed". Therefore, in this scheme, you can select the fitting result with the largest R-square in the fitting results to proceed to step 5.

[0091] Step 4: Calculate the radius of curvature of the plane coordinates of a specific part (index k to index l) by fitting the result curve, and use the drop in the inland ship turning speed corresponding to the radius of curvature as a mark. As a preferred solution, in order to prevent the special situation where the curve appears at both ends of a certain section (index i to j) and causes inaccurate fitting and curvature radius calculation, step 4 divides each section (index i to j) into three parts on average, and only calculates the curvature radius of the middle part (index k to l). However, since each segmentation is performed by using the longitude difference segmentation method as the main method and the number segmentation method as the auxiliary method, the length of each segmentation may not be equal, and the calculation of the curvature radius of certain longitudes and latitudes may be skipped. Therefore, the specific serial number values ​​of indexes k and l in step 4 are determined by the following method:

[0092] When the sequence number i of index i is equal to 0, it means that this segment is the starting segment. At this time, the sequence number of index k is equal to i equal to 0, and the sequence number of index l is equal to i+(ji)÷3×2.

[0093] When the sequence number of index j is greater than or equal to N-1, it indicates that this segment is the end segment. At this time, the sequence number of index k is equal to the sequence number of the previous index l, and the sequence number of this index l is equal to N-1.

[0094] When the sequence numbers of index i and index j do not meet the above two conditions, it means that this segment is an intermediate segment. At this time, the sequence number of index k is equal to the sequence number of the previous index l, and the sequence number of index l this time is equal to i+(ji)÷3×2.

[0095] Since the curvature radius is calculated only for the middle part of a segment each time, the sequence number i of index i before each segmentation is iteratively calculated using the following formula:

[0096]

[0097] The determination of the specific serial number values ​​of index k and index l and the iteration of index i are as follows: Figure 8 As shown, according to Figure 8 As shown, the idea of ​​determining the specific sequence number values ​​of index k and index l in the present invention is:

[0098] 1. Only the middle part is calculated to eliminate the problem of inaccurate fitting and curvature radius calculation caused by curves appearing at both ends of a certain section.

[0099] 2. (Assuming the number of each segment is equal) Since only the middle portion is calculated, you can only move forward 1 / 3 of the segment to ensure that the middle portion this time is connected to the middle portion of the previous time in sequence number.

[0100] 3. Since the number of segments is different each time and the middle segment cannot be connected, the k this time is equal to the l last time to force the connection.

[0101] According to the design idea, the present invention adopts a strategy of assigning different index numbers under different segmentation conditions, coordinates the iterative assignment of index numbers, and uses the assignment method of index l being equal to i+(ji)÷3×2. The purpose is to coordinate so that under the segmentation strategy adopted by the present invention, each segment is divided into three parts. Each time the segmentation is iterated, the forward method is to increase the index i by (ji)÷3. In this way, the current iterative segmentation and the previous iterative segmentation can have overlapping parts (such as approximately the last 2 / 3 part of the previous segment and approximately the first 2 / 3 part of the next segment are overlapping), so that after each iteration, for the current segment, only the curvature radius of the middle part of the segment (index k to l) is calculated.

[0102] Under such a technical solution, the problem of inaccurate fitting and curvature radius calculation caused by the curve appearing at both ends of a certain section can be solved as much as possible. After each iteration, the serial number of index k is equal to the serial number of index l in the previous time. Under such a technical solution, the problem that the length of each segment may be different and the calculation of the curvature radius of some longitudes and latitudes may be skipped can be solved as much as possible because the present invention adopts the strategy of segmentation mainly by longitude difference segmentation and supplemented by number segmentation.

[0103] Calculate the curvature radius of each plane coordinate between index k and index l determined by step 4 through the curve fitting result of step 3. Then calculate the specific value of the speed drop corresponding to the curvature radius through the following Felsov speed drop formula. And use this specific value as the curve mark corresponding to the longitude and latitude data of the plane coordinate point. The larger the value and the closer it is to 1, the larger the curvature radius of the curve and the closer it is to a straight line, and the smaller the resistance to turning; the smaller the value, the smaller the curvature radius of the curve, the greater the resistance to turning, and the need to slow down when turning.

[0104] Filtsov speed reduction formula:

[0105]

[0106] Where: V c is the speed of the ship during the turning process; V0 is the initial speed of the ship's turning; R is the turning curvature radius, and L is the length of the ship.

[0107] After the marking is completed, the specific serial number value of index i before the next segmentation is determined by iterating the index i in step 4, and then steps 1 to 5 are repeated until the curve marking of all longitude and latitude data is completed.

[0108] Step 5: After advancing a certain number of longitude and latitude data, the second segmentation is started, and steps 1-4 are repeated, and so on, until the entire navigation data curve identification is completed. As a preferred solution, the specific content of step 5 is: the certain number is equal to (ji) ÷ 3, and the advancing method is to increase the sequence number of index i by (ji) ÷ 3, and then repeat step 1 to segment again. Then repeat the subsequent steps in sequence, and keep looping until the curve identification of all longitude and latitude data is completed.

[0109] Wherein, the specific number is equal to (ji) ÷ 3. As mentioned above, the sequence number i of index i is iteratively calculated by the following formula:

[0110]

[0111] In a specific example, Figure 1 As shown, based on the above-mentioned curve recognition method, the curve recognition method of the present invention is based on a total of 2936 longitude and latitude data obtained during a certain voyage, according to Figure 2 As shown, taking the sequential index from 0 to 2935 as an example, the curve recognition method of the present invention is further described, and the recognition method specifically includes:

[0112] Step 1: Segmentation is performed by using the fixed longitude difference method as the main method and the fixed number method as the auxiliary method. Specifically, when the number of segmented data intercepted by the fixed longitude difference method is too large or too small, it is automatically converted to the fixed number method for segmentation. The longitude difference of each segment is set to 0.1 degrees, and the fixed number is set to a minimum of 33 and a maximum of 99. The setting parameters can be appropriately adjusted according to the longitude and latitude data of different acquisition frequencies and the Gauss Kruger projection deformation requirements.

[0113] First, each segment of longitude and latitude data is intercepted by a fixed longitude difference. The first segmentation starts from the longitude and latitude data corresponding to index i, where the serial number i of index i=0, and the serial number j of index j increases from i+1. Each time it increases, check the difference between the minimum longitude and the maximum longitude of all data between index i and index j. When the serial number j of index j increases to 78, the longitude difference is greater than 0.1 degrees, and the serial number j stops increasing. At this time, j-i=77, which is greater than 33. If the longitude difference is still less than 0.1 when the serial number j of index j increases to more than i+99, the serial number j stops increasing and forces the serial number j=i+99. Finally, through the remainder of (ji)÷3, the serial number j is increased or decreased by one or remains unchanged to ensure that (j-i) is divisible by 3, (ji)÷3=1, j=77+1=78, and the segmentation ends. The result of the first segmentation is i=0, j=78. The route of the first segmentation is as follows: Figure 3 shown.

[0114] Step 2: Extract the minimum and maximum longitudes of all longitude and latitude data between index i=0 and index j=78 after segmentation in step 1, and then use half of the sum of the minimum and maximum longitudes as the central meridian of the Gauss Kruger projection zone, and then project the longitude and latitude data from index i=0 to index j=78 into plane coordinates (x, y). The projection results of the first segment of longitude and latitude coordinates are as follows Figure 4 shown.

[0115] Step 3: Perform polynomial fitting on the plane coordinates in a specific way. First, perform a translation operation on a section of plane coordinates (x, y) projected in step 2: subtract the minimum x value and the minimum y value in the section from the x and y values ​​of all coordinates, and then add 10 to each, so that the entire section of plane coordinates is translated closer to the origin of the coordinates. The R-squared determination coefficient is used as the evaluation index for the fitting result. An R-squared greater than 0.999 indicates a qualified fit.

[0116] Then perform polynomial fitting using four methods: abcd:

[0117] Directly perform polynomial fitting according to the original plane coordinates (x, y);

[0118] Swap the values ​​of x and y for the entire segment (i.e., mirror them along the line y=x) and then perform polynomial fitting;

[0119] The entire original plane coordinate (x, y) is rotated 45 degrees to the right along the origin of the coordinate system and then a polynomial fitting is performed;

[0120] The entire original plane coordinate (x, y) is rotated 45 degrees to the left along the coordinate origin and then a polynomial fitting is performed.

[0121] The fitting results of the four methods of abcd for the first segmentation are as follows Figure 5 shown.

[0122] Then calculate the R-squared of the fitting results of the four methods abcd, which are R-squared_a=0.9861, R-squared_b=0.9564, R-squared_c=0.9957, and R-squared_d=0.9999. Among them, R-squared_d is the largest, so the fitting result of d is selected as the final fitting result. Obviously, R-squared_d>0.999 is a qualified fitting, and step 4 can be started. If the largest R-squared<0.999 is still unqualified, perform an additional fifth method e polynomial fitting:

[0123] Starting from the original plane coordinates (x, y), the coordinate points are rotated clockwise by 30 degrees to generate a total of 12 sets of plane coordinates, and a polynomial fitting is performed on each set of plane coordinates.

[0124] Finally, calculate the R-square of the 12 groups of fitting results in method e, select the fitting result with the largest R-square as the final fitting result, and if the largest R-square is qualified, start step 4. If the largest R-square is still unqualified, print out the best fitting result graph and prompt "fitting failed".

[0125] Step 4: Calculate the curvature radius of the plane coordinates of the specific part (index k to index l) by fitting the result curve, and use the drop value of the inland ship turning speed corresponding to the curvature radius as a mark. First, determine the specific serial number values ​​of the specific part index k and index l according to three situations: when the serial number of index i is equal to 0, it means that this section is the starting section, at this time the serial number of index k is equal to the serial number i is equal to 0, and the serial number of index l is equal to i+(ji)÷3×2. When the serial number of index j is greater than or equal to N-1, it means that this section is the ending section, at this time the serial number of index k is equal to the serial number of the previous index l, and the serial number of this index l is equal to N. When the serial numbers i and j of the indexes do not meet the above two conditions, it means that this section is the middle section, at this time the serial number of index k is equal to the serial number of the previous index l, and the serial number of this index l is equal to i+(ji)÷3×2. At this time, the sequence number i of index i=0 and the sequence number j of index j=78 satisfy the first case, so the sequence number k of index k=0 and the sequence number l of index l=i+(ji) / 3*2=52.

[0126] Then, the curvature radius of each plane coordinate corresponding to the latitude and longitude data corresponding to index k to index l is calculated through the curve fitting result in step 3. Finally, the following Felsoff velocity drop formula is used:

[0127]

[0128] Combined with the ship length L = 189.9m and the radius of curvature corresponding to each coordinate, calculate the specific value of the corresponding speed drop. At the same time, use this value as the curve mark of the longitude and latitude data corresponding to the plane coordinate point. The marking result is as follows Figure 6 As shown. The larger the value is and the closer it is to 1, the larger the curvature radius of the curve is and the closer it is to a straight line, the smaller the resistance to turning; the smaller the value is, the smaller the curvature radius of the curve is and the greater the resistance to turning, and the driver needs to slow down to turn.

[0129] Step 5: Go forward to index i, and go forward (ji) ÷ 3 = 26 longitude and latitude data. Then start the second segmentation from i = 26, and repeat steps 1-4, and so on, until the whole navigation data curve identification is completed. If the longitude and latitude coordinates with a marked speed drop value less than 0.99 are identified as curves, the curve identification result route map is as follows Figure 7 shown.

[0130] According to the scheme, the present invention can ensure that the deformation of the subsequent Gauss Krüger projection can be controlled within a very small range by segmenting through longitude difference. Because the deformation degree of the Gauss Krüger projection is only related to the longitude difference between the point and the central meridian, setting the longitude difference of each segment controls the maximum deformation of each Gauss Krüger projection. The segmentation strategy of the present invention, which mainly uses a fixed longitude difference method and a fixed number method as a supplement, ensures that a small number of inland waterways in the north-south direction (directions with small longitude changes) can also be successfully segmented. By adjusting the longitude difference and the maximum and minimum number of segments, it can adapt to navigation data with different collection frequencies and routes with too many bends.

[0131] According to the scheme, the present invention uses half of the sum of the maximum and minimum values ​​of each longitude segment as the central meridian to form a local Gauss Krüger projection band instead of using a standard projection band, thereby further reducing the deformation of the Gauss Krüger projection.

[0132] According to the scheme, the present invention performs polynomial fitting through five methods abcde, which greatly improves the success rate of polynomial fitting while ensuring that the route is not deformed.

[0133] According to the scheme, the present invention greatly improves the operation speed while ensuring the success rate through a specific polynomial fitting method.

[0134] According to the scheme, the present invention calculates only the curvature radius of the middle portion of each segment without considering the two ends, thereby eliminating the special situation where the curve appears at the two ends of a segment, causing inaccurate fitting and curvature radius calculation.

[0135] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0136] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solutions and inventive concepts of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A curve recognition method based on inland river ship longitude and latitude data, characterized in that: include Step 1: Set the indexes of N sequential longitude and latitude data obtained through navigation to be from 0 to N-1; Step 2: According to the latitude and longitude data of the starting index i, the latitude and longitude data are segmented, and the segmentation results include the latitude and longitude data corresponding to the index i and the index j and all the indexes between the index i and the index j; Step 3: Project the longitude and latitude data corresponding to index i and index j and all indexes between index i and index j into plane coordinates, where the index of the plane coordinates is the same as the index of the longitude and latitude data; Step 4: Perform polynomial fitting on the plane coordinates; Step 5: Determine index numbers k and l according to the serial numbers i and j of index i and index j; calculate the curvature radius of the plane coordinates of the longitude and latitude data corresponding to index k and index l and all indexes between index k and index l through the polynomial fitting result of the plane coordinates; According to the curvature radius of the plane coordinates of the longitude and latitude data corresponding to the index k and the index l and all the indexes between the index k and the index l, the speed drop of the inland river ship turning corresponding to the curvature radius is calculated; Mark the curves of the longitude and latitude data corresponding to index k and index l and all indexes between index k and index l according to the drop value of the turning speed of the inland river ship; Step 6: Re-determine the starting index i according to the sequence numbers i and j of the index i and the index j, wherein the mark sequence number of the re-determined starting index is greater than the mark sequence number of the starting index; Step 7: Repeat steps 2 to 6 until all the curve markings of longitude and latitude data are completed; The segmentation method of step 2 comprises: Starting from the latitude and longitude data of the starting index i, the serial number of index j increases from i+1. Each time it increases, the difference between the minimum longitude and the maximum longitude of the latitude and longitude data corresponding to all indexes from index i to index j is checked, where the value of the difference between the minimum longitude and the maximum longitude is set to x, the minimum fixed number is y, and the maximum fixed number is z; S2.

1. If the difference between the minimum longitude and the maximum longitude is greater than x degrees, the serial number of index j stops increasing. At this time, if j-i is less than y, the serial number j=i+y. If j-i is greater than y, no operation is performed, and the serial number of index j is obtained; If the difference between the minimum longitude and the maximum longitude is not greater than x degrees, the serial number of index j continues to increase until the difference between the minimum longitude and the maximum longitude is greater than x degrees, then the serial number of index j stops increasing. At this time, if j-i is less than y, the serial number j=i+y. If j-i is greater than y, no operation is performed, and the serial number of index j is obtained. If the index number of index j increases to more than i+z but still does not satisfy that the difference between the minimum longitude and the maximum longitude is greater than x degrees, the index number of index j stops increasing and the index number j=i+z, and the index number of index j is obtained; S2.

2. Calculate the serial number of the obtained index j and the serial number of the starting index i, and use the remainder of (ji)÷3 to increase or decrease the serial number j or keep it unchanged, so that (j-i) can be divided by 3, and get the serial number of the final index j, thereby obtaining the longitude and latitude data corresponding to all the indexes including index i and index j and between index i and index j.

2. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 1, characterized in that: The method of projecting the longitude and latitude data corresponding to index i and index j and all indexes between index i and index j into plane coordinates in step 3 includes: S3.

1. Extract the minimum longitude and maximum longitude of all longitude and latitude data from index i and index j after segmentation and between index i and index j; S3.

2. Set the central meridian of the projection zone in the Gauss-Krüger projection equal to one-half times the sum of the minimum and maximum longitudes; S3.

3. Project the longitude and latitude data of index i and index j and between index i and index j into plane coordinates (x, y) through the central meridian.

3. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 1, characterized in that: The method for performing polynomial fitting on the plane coordinates in step 4 includes: S4.

1. perform a translation operation on the plane coordinates (x, y) of the projection of the latitude and longitude data between index i and index j on the central meridian; S4.

2. Perform polynomial fitting on the plane coordinates (x, y) after the translation operation by four methods: abcd: a. directly performing polynomial fitting on the plane coordinates (x, y) after the translation operation; b. performing polynomial fitting after exchanging the x and y values ​​of the plane coordinates (x, y) after the translation operation; c. Rotate the plane coordinates (x, y) after the translation operation 45 degrees to the right along the origin of the coordinate system and then perform polynomial fitting; d. Rotate the plane coordinates (x, y) after the translation operation 45 degrees to the left along the origin of the coordinates and then perform polynomial fitting; S4.

3. Calculate the R-squared of the fitting results of the four methods abcd, and select the fitting result with the largest R-squared as the final fitting result. If the largest fitting result in the R-squared is qualified, proceed to step 5; if the largest fitting results in the R-squared are all unqualified, proceed to the fifth method for polynomial fitting: e. Starting from the plane coordinates (x, y) after the translation operation, the coordinate points are rotated clockwise by 30 degrees with the coordinate origin as the center, generating a total of 12 sets of plane coordinates, and performing polynomial fitting on each set of plane coordinates to obtain 12 sets of fitting results; S4.

4. Calculate the R-squared of the 12 groups of fitting results in method e, select the fitting result with the largest R-squared as the final fitting result, and if the largest fitting result in the R-squared is qualified, proceed to step 5; if the largest fitting result in the R-squared is unqualified, the fitting fails, and select the largest fitting result in the R-squared in the fitting results to proceed to step 5.

4. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 3 is characterized in that: The step S4.1 specifically includes subtracting the x and y values ​​of the plane coordinates (x, y) of the projection of the longitude and latitude data between index i and index j from the minimum x value and the minimum y value in the segment, and then adding 10 to each of them, so that the plane coordinates of the segment are translated closer to the origin of the coordinates; The method of rotating the plane coordinates (x, y) after the translation operation to the right by 45 degrees along the coordinate origin in step S4.2 includes: First convert the Cartesian coordinates (x, y) to polar coordinates (ρ, θ); Then add π / 4 to θ in the polar coordinates; Then the polar coordinates are converted to Cartesian coordinate (x, y) values; Finally, the x and y values ​​of each coordinate are subtracted from the minimum x and y values ​​of all coordinates to ensure that all values ​​are positive; The method of rotating the plane coordinates (x, y) after the translation operation to the left by 45 degrees along the coordinate origin in step S4.2 includes: First convert the Cartesian coordinates (x, y) to polar coordinates (ρ, θ); Then subtract π / 4 from θ in the polar coordinates; Then the polar coordinates are converted to Cartesian coordinate (x, y) values; Finally, the x and y values ​​of each coordinate are subtracted from the minimum x and y values ​​of all coordinates to ensure that all values ​​are positive.

5. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 3 is characterized in that: The R-squared determination coefficient was used as the evaluation index for the fitting results, and an R-squared greater than 0.999 indicated a qualified fit; The polynomial fitting is specifically as follows: starting from the 5th order polynomial fitting, if the fitting result R square is qualified, the polynomial fitting is terminated; if the fitting result R square is unqualified, the polynomial order is increased by one, and fitting is performed again, and the fitting is terminated if the fitting result R square is qualified; if the polynomial order is increased to 20, and the fitting result R square is still unqualified, the polynomial fitting is forced to end.

6. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 1, characterized in that: The method for determining index numbers k and l according to index numbers i and j in step 5 includes: When the sequence number of the starting index i is equal to 0, it means that this segment is the starting segment. At this time, the sequence number of index k is equal to the sequence number of index i, which is equal to 0, and the sequence number of index l is equal to i+(ji)÷3×2; When the sequence number of index j is greater than or equal to N-1, it means that this segment is the end segment. At this time, the sequence number of index k is equal to the sequence number of index l in the previous iteration, and the sequence number of index l in this iteration is equal to N-1; When the sequence number of index i and the sequence number of index j do not meet the above two conditions, it means that this segment is an intermediate segment. At this time, the sequence number of index k is equal to the sequence number of index l in the previous iteration, and the sequence number of index l in this iteration is equal to i+(ji)÷3×2.

7. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 6 is characterized in that: The method of calculating the reduction value of the turning speed of an inland river vessel corresponding to the curvature radius according to the curvature radius of the plane coordinates of the longitude and latitude data corresponding to the index k and the index l and all the indexes between the index k and the index l in step 5 includes: According to the maximum fitting result in the qualified R-squared in step step, calculate the curvature radius of each plane coordinate of the latitude and longitude data corresponding to index k to index l; The specific value of the speed drop corresponding to the radius of curvature is calculated by the Filtsov speed drop formula, and this value is used as the curve mark of the longitude and latitude data corresponding to the plane coordinate point, where the Filtsov speed drop formula is: Where: V c is the speed of the ship during the turning process; V0 is the initial speed of the ship's turning, R is the turning curvature radius, and L is the length of the ship.

8. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 7, characterized in that: The closer the specific value of the speed drop is to 1, the larger the radius of curvature of the curve, the closer it is to a straight line, and the smaller the resistance to turning; the smaller the specific value of the speed drop is, the smaller the radius of curvature of the curve, the greater the resistance to turning, and you need to slow down when turning.

9. The method for identifying a curve based on the latitude and longitude data of an inland river vessel according to claim 6, characterized in that: In step 6, the method for re-determining the starting index i according to the sequence numbers i and j of the indexes i and j includes calculating the sequence numbers of the indexes i and j in the current iteration, and increasing the sequence number of the re-determined starting index i by (ji)÷3.

Images