Multi-beam survey line optimization method based on underwater topographic survey

Abstract

The invention relates to a multi-beam survey line optimization method based on underwater topographic survey, and belongs to the technical field of measurement. In order to solve the problem that in the prior art, mastering cannot be carried out from a global perspective, the method comprises the following steps that 1, a measuring line interval and coverage width basic model in an ideal state is constructed, and a calculation method of basic data under the model is determined; 2, constructing a measuring line interval and coverage width basic model in an actual state, and determining a calculation method of basic data under the model; and step 3, establishing a survey line deployment optimization model and performing corresponding solution. The model established through the method is convenient to solve, the solving speed is high, the range where all the reference measuring lines meeting the optimal measuring line are located can be obtained in the whole domain instead of a single optimal solution, and the error-tolerant rate is high.

Description

Technical Field

[0001] The invention relates to a multi-beam survey line optimization method based on underwater topography measurement, and belongs to the technical field of measurement. Background Art

[0002] Sea area topography detection has important research value in the field of earth science. Through sea area topography detection, the seabed topography can be studied, the evolution process of the earth's natural environment can be understood, and the laws of natural disasters such as earthquakes and volcanic eruptions can be studied. For crashed planes and shipwrecks, the location of sediments and their volume and shape can be determined by the changes in sea area topography before and after the crash. Multi-beam bathymetry is one of the important means of current sea area topography detection. How to achieve high-precision full coverage detection of the area to be measured with a reasonable overlap rate, the survey line optimization method is the key. At present, the more ideal approach is to optimize the survey line interval based on modern optimization algorithms, and use the multi-beam sideways data edge wave velocity to correct the roll motion residual model and other model methods to find the most ideal survey line optimization solution, but it is impossible to give control from the perspective of the entire domain. Summary of the invention

[0003] The purpose of the present invention is to solve the problem that the prior art cannot grasp from a global perspective, and to provide a multi-beam survey line optimization method based on underwater topography measurement with strong fault tolerance and the ability to obtain the range of all reference survey lines that meet the optimal survey line in the global domain.

[0004] In order to solve the above problems, the present application is implemented through the following technical solutions: A multi-beam survey line optimization method based on underwater topography measurement is special in that it includes the following steps: Step 1: Construct a basic model of survey line interval and coverage width under ideal conditions, and determine the calculation method of basic data under this model; Step 2: Construct a basic model of line spacing and coverage width under actual conditions, and determine the calculation method of basic data under this model; Step 3: Establish a survey line deployment optimization model and perform corresponding solutions.

[0005] Furthermore, the step 1 specifically includes the following steps: Step 1.1, establish the mathematical model of the basic model; Step 1.2, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of water depth height; Step 1.3, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of the coverage width of the bathymetric strip of the survey vessel; Step 1.4: In the plane rectangular coordinate system established in step 1.1, determine the calculation method of the overlap rate between adjacent strips.

[0006] Further, the step 1.1 is specifically as follows: select a section perpendicular to the direction of the measurement line, set the center point of the sea area as the left origin, the vertical downward direction as the positive direction of the x-axis, and the straight line between the horizontal plane and the vertical section as the y-axis, and construct a plane rectangular coordinate system according to the right-hand rule; The water depth in step 1.2 is related to the y-axis coordinate of the detection line where the survey ship is located. When the coordinate of the survey ship is y, the water depth height is: ; Where: The y coordinate of the location of the survey ship is 0, It means when the survey ship is at point y, that is, the distance from the survey ship to the center of the sea is y, the depth from the survey ship to the seabed. ; Indicates the angle between the detection line and the sea level; In step 1.3, the coverage width of the bathymetric strip of the survey ship is related to its depth to the seabed. For the survey ship at point y, the coverage width of its bathymetric strip is: ; Where: is the width measured along the slope towards the deep water side, is the width measured along the slope towards the shallow water side, , , Where: is the opening angle of the multi-beam transducer; The distance between the measurement lines of two adjacent measurement ships in step 1.4 is The detection overlap rate between the survey ship at point y and the survey ship on the shallow water side, i.e. the direction where the y coordinate increases, is: .

[0007] Furthermore, the step 2 specifically includes the following steps: Step 2.1, establish a mathematical model of the general model; Step 2.2: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method of the distance from the survey ship to the seabed; Step 2.3: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method for the coverage width of the survey vessel's bathymetric strip.

[0008] Further, the step 2.1 is specifically as follows: a three-dimensional rectangular coordinate system is constructed with the intersection of a straight line passing through the center of the sea area and perpendicular to the horizontal plane and the slope as the origin of the coordinates, the projection of the normal vector of the slope on the horizontal plane as the positive direction of the x-axis, and the vertically upward direction as the positive direction of the z-axis; vector is the unit projection vector of the survey line direction on the horizontal xoy plane, then The angle with the positive x-axis is , , the unit vector in the opposite direction to the normal vector of the seafloor slope is: , The vector is projected onto the seabed slope, and the projection vector is the vector , the angle between the two vectors is the vector Angle with horizontal plane ,Right now The angle between the vector and the slope, Vector and The angle is ,but: ,have to: ,and The unit vectors in the same direction are: , The beam is intercepted at a section perpendicular to the survey line. The intersection of the section and the ground is perpendicular to the survey line, so the vector ,vector is a vector On the slope, a single normal vector Counterclockwise rotation obtained; Known vector , direction vector ,like ,but Around (Right-hand rule) Rotate counterclockwise by an angle The resulting vector is: , If the rotation is clockwise, the angle takes a negative value, and the vector for: , Written in row vector form: , vector The angle with the xoy plane is , the coordinates of point A where the survey ship is located in the central sea area are ,vector With vector The angle is ,vector With vector Angle: ,because For vector Rotate to get, is a unit vector, so is also a unit vector, ,but .

[0009] Furthermore, the step 2.2 is specifically as follows: when the survey ship sails along the survey line and keeps the survey line direction angle unchanged, the distance from the location of the survey ship to the seabed will change, and its height will change with the distance from the survey ship to the center of the sea area. The change relationship is: ; Further, the step 2.3 is specifically as follows: the coverage width of the deep water side of the bathymetric strip is: ; The coverage width on the shallow water side is: , Coverage Width: , Where: y represents the distance from the measuring ship to the center of the sea area.

[0010] Furthermore, the survey line optimization deployment model in step 3 includes the following steps: Step 3.1, under the condition that the overlap rate is 10%-20%, determine the angle between the survey lines with the largest interval between the survey lines; Step 3.2, under the condition of 10% overlap, determine the shortest measurement line length; Step 3.3: Determine the optimal reference line.

[0011] Furthermore, the step 3.1 specifically includes the following steps: Step 3.1.1, according to the mathematical model of step 1, respectively calculate the seawater depth, coverage width and overlap rate of the baseline survey line and the adjacent survey line on the deep-water side of the baseline survey line; Step 3.1.2: Based on the overlap ratio calculated in step 3.1.1, As the decision variable, the following optimization model is constructed: ; Step 3.1.3: Use the variable step-size search algorithm to solve the optimization model of step 3.1.2 to obtain the angle between the survey lines with the largest interval between the survey lines.

[0012] Furthermore, the specific calculation process of step 3.1.1 is as follows: draw a north-south straight line through the center of the sea area, perpendicularly intersecting the east-west boundary at point O, with point O as the origin and the due west direction of the east-west boundary as the positive direction of the x-axis, and construct a plane rectangular coordinate system that satisfies the right-hand rule; the reference line intersects the east-west boundary at point , the water depth at the origin O is the same as the water depth at the center of the sea area, both are D, and the angle between the slope and the horizontal plane is , the direction vector of the reference line is: , the coordinates of the center of the sea area in this coordinate system are (0,1852), and the linear equation of the benchmark line is: ,but The coordinates of the point are: , the water depth at this point is: , Point on a straight line Distance to point O: ,point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , the coverage width on the shallow water side is: , Where: for Function of The adjacent survey line on the deep water side intersects the east-west boundary at point This survey line is equivalent to the benchmark survey line being shifted to the deep water side. , the equation of the line is: ,but The coordinates are: , the water depth at this point is: , the survey line is parallel to the reference survey line and is the reference survey line shifted to the left The point on the line is obtained. The distance is: ,point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , the coverage width on the shallow water side is: , Where: for Function of The distance between the reference survey line and its adjacent survey line on the deep water side is , then The overlap rate of the two lines is: .

[0013] Furthermore, the step 3.2 specifically includes the following steps: Step 3.2.1: Determine the recursive formula for the distance between the deepwater survey line and the benchmark survey line: The distance between the kth survey line on the deepwater side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the k-1th line is 10%, , the specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the deep water side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , the width of detection on the shallow water side: , The coincidence rate between the baseline survey line and the first survey line on the deep water side is: , make ,but: ,make ,but: , The depth of the benchmark line is the interval between the second survey line and the benchmark line. , the depth of the survey line is: , Then the width of the second survey line measured on the deep water side is: , the width of detection on the shallow water side: , The overlap rate between the first survey line and the second survey line on the deep water side is: , make ,but: ,make ,but: ; Step 3.2.2: Determine the recursive formula for the distance between the shallow water side survey line and the benchmark survey line: The distance between the sth survey line on the shallow water side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the s-1th line is 10%, The specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the shallow side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , the width of detection on the shallow water side: , The coincidence rate between the reference survey line and the first survey line on the shallow water side is: , make ,but: , make ,but: , The interval between the second survey line and the benchmark survey line on the shallow water side of the benchmark survey line is , the depth of the survey line is: , The width of the second survey line measured on the deep water side is: , the width of detection on the shallow water side: , The overlap rate between the first and second survey lines on the shallow water side is: , make ,but: ,make ,but: .

[0014] Furthermore, the step 3.3 is as follows: u survey lines are required on the deep water side, and v survey lines are required on the shallow water side, and the total coverage width should exceed the east-west length of the rectangular area, that is, , Right now , after simplification: , The optimal deployment position of the benchmark survey line is the position where the number of u+v+1 is the smallest under the above conditions, so the following optimization model is constructed: , Traverse and solve the above model, from all the constraints that meet the and Select The minimum value of the sum, that is Minimum, The total number of measurement lines required is strip.

[0015] This application designs a recursive formula for the spacing between deep and shallow survey lines when the overlap rate is 10% based on a certain survey line, and constructs an optimal survey line deployment optimization model based on this formula. The model is easy to solve and has a fast solution rate. It can also obtain the range of all benchmark survey lines that meet the optimal survey line in the entire domain, rather than a single optimal solution, and has a strong fault tolerance rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a flow chart of the present invention; Figure 2 Construct a schematic diagram for a plane rectangular coordinate system; Figure 3 This is a schematic diagram of water depth changes; Figure 4 This is a schematic diagram for calculating the coverage width of the bathymetric strip; Figure 5 Construct a schematic diagram for a three-dimensional rectangular coordinate system; Figure 6 It is a schematic diagram of the survey line; Figure 7 This is a schematic diagram of a reference survey line with a survey line angle of 90 degrees; Figure 8 The horizontal axis coordinate of the reference survey line for searching the optimal solution for the next part; Fig. 9 It is the horizontal axis coordinate of the benchmark survey line of some optimal solutions. DETAILED DESCRIPTION

[0017] The following is a specific implementation of the present invention with reference to the accompanying drawings to further illustrate the composition of the present invention.

[0018] Embodiment 1. A multi-beam survey line optimization method based on underwater topography measurement, the process is as follows Figure 1 As shown, the following steps are included: Step 1: Construct a basic model of survey line interval and coverage width under ideal conditions, and determine the calculation method of basic data under this model; Step 2: Construct a basic model of line spacing and coverage width under actual conditions, and determine the calculation method of basic data under this model; Step 3: Establish a survey line deployment optimization model and perform corresponding solutions.

[0019] Furthermore, the step 1 specifically includes the following steps: Step 1.1, establish the mathematical model of the basic model; Step 1.2, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of water depth height; Step 1.3, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of the coverage width of the bathymetric strip of the survey vessel; Step 1.4: In the plane rectangular coordinate system established in step 1.1, determine the calculation method of the overlap rate between adjacent strips.

[0020] Furthermore, the step 1.1 is as follows: select a section perpendicular to the direction of the measurement line, set the center point of the sea area as the left origin, the vertical downward direction as the positive direction of the x-axis, and the straight line between the horizontal plane and the vertical section as the y-axis. According to the right-hand rule, construct a plane rectangular coordinate system, such as Figure 2 As shown; The water depth in step 1.2 is related to the y-axis coordinate of the detection line where the survey ship is located. When the coordinate of the survey ship is y, the water depth height is: ; Where: The y coordinate of the location of the survey ship is 0, It means when the survey ship is at point y, that is, the distance from the survey ship to the center of the sea is y, the depth from the survey ship to the seabed. ; Indicates the angle between the detection line and the sea level; The specific derivation process is as follows: Assume that the distance between the measurement lines of two adjacent survey ships is d, and the schematic diagram of the depth change from the survey ship to the seabed is as follows: Figure 3 As shown, When the distance between two adjacent measuring lines is d, the change in water depth height is: If it is the deep water side, the coordinate of the survey ship is -d, and the height of the water depth is: , If it is the shallow water side, the coordinate of the survey ship is d, and the height of the water depth is: ; In step 1.3, the coverage width of the bathymetric strip of the survey ship is related to its depth to the seabed. For the survey ship at point y, the coverage width of its bathymetric strip is: ; Where: is the width measured along the slope towards the deep water side, is the width measured along the slope towards the shallow water side, , , Where: is the opening angle of the multi-beam transducer; The specific derivation process is as follows: Take the survey ship at the center point as an example for derivation. At this time, the coordinate origin of the survey ship, the y-axis coordinate is 0, such as Figure 4 As shown, According to the known conditions and the law of sine, , calculate the length of AB, that is, the width of the detection along the slope to the deep water side: , Where: The length of OB is the depth of the measuring ship from the seabed , when the survey ship is at the center, the depth is , the width of the detection along the slope to the deep water side is: , Similarly, , calculate the length of BC, that is, the width of the detection along the slope to the shallow water side: ; The distance between the measurement lines of two adjacent measurement ships in step 1.4 is The detection overlap rate between the survey ship at point y and the survey ship on the shallow water side, i.e. the direction where the y coordinate increases, is: .

[0021] Furthermore, the step 2 specifically includes the following steps: Step 2.1, establish a mathematical model of the general model; Step 2.2: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method of the distance from the survey ship to the seabed; Step 2.3: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method for the coverage width of the survey vessel's bathymetric strip.

[0022] Further, the step 2.1 is specifically as follows: a three-dimensional rectangular coordinate system is constructed with the intersection of the straight line passing through the center of the sea area and perpendicular to the horizontal plane and the slope as the origin of the coordinates, the projection of the normal vector of the slope on the horizontal plane as the positive direction of the x-axis, and the vertically upward direction as the positive direction of the z-axis, as shown in Figure 5; vector is the unit projection vector of the survey line direction on the horizontal xoy plane, then The angle with the positive x-axis is , , the unit vector in the opposite direction to the normal vector of the seafloor slope is: , The vector is projected onto the seabed slope, and the projection vector is the vector , the angle between the two vectors is the vector Angle with horizontal plane ,Right now The angle between the vector and the slope, Vector and The angle is ,but: ,have to: ,and The unit vectors in the same direction are: , The beam is intercepted at a section perpendicular to the survey line. The intersection of the section and the ground is perpendicular to the survey line, so the vector ,vector is a vector On the slope, a single normal vector Counterclockwise rotation obtained; Known vector , direction vector ,like ,but Around (Right-hand rule) Rotate counterclockwise by an angle The resulting vector is: , If the rotation is clockwise, the angle takes a negative value, and the vector for: , Written in row vector form: , vector The angle with the xoy plane is , the coordinates of point A where the survey ship is located in the central sea area are ,vector With vector The angle is ,vector With vector Angle: , because For vector Rotate to get, is a unit vector, so is also a unit vector, ,but .

[0023] Furthermore, the step 2.2 is specifically as follows: when the survey ship sails along the survey line and keeps the survey line direction angle unchanged, the distance from the location of the survey ship to the seabed will change, and its height will change with the distance from the survey ship to the center of the sea area. The change relationship is: ; Further, the step 2.3 is specifically as follows: the coverage width of the deep water side of the bathymetric strip is: ; The coverage width on the shallow water side is: , Coverage Width: , Where: y represents the distance from the measuring ship to the center of the sea area.

[0024] Furthermore, the survey line optimization deployment model in step 3 includes the following steps: Step 3.1, under the condition that the overlap rate is 10%-20%, determine the angle between the survey lines with the largest interval between the survey lines; Step 3.2, under the condition of 10% overlap, determine the shortest measurement line length; According to step 3.1, the angle between the survey lines with the largest interval between them is determined to be 90°. The depth from each point on the survey line to the seabed is equal, and the overlap rate at any position of two adjacent survey lines is equal. In the plane rectangular coordinate system constructed above, the horizontal coordinate of the reference survey line is set as x, and the overlap rate is 10% as a constraint condition. The coordinates of the survey lines are calculated in turn on both sides of the deep and shallow sides until the entire rectangular sea area can be covered. The goal is to minimize the length of the survey lines in all rectangular areas. The horizontal coordinate x of the reference survey line is the decision variable, as shown in Figure 7 shown.

[0025] The horizontal coordinate of the reference survey line is x. Since the horizontal axis points to the deep water direction as the positive direction, the depth of the survey line at point x is: , the width measured on the deep water side of the benchmark survey line is: , the width of detection on the shallow water side: ,make , , then the width measured on the deep water side is: , the width measured on the shallow water side is: .

[0026] Step 3.3: Determine the optimal reference line.

[0027] Furthermore, the step 3.1 specifically includes the following steps: Step 3.1.1, according to the mathematical model of step 1, respectively calculate the seawater depth, coverage width and overlap rate of the baseline survey line and the adjacent survey line on the deep-water side of the baseline survey line; Since the seabed is a slope, it is in a very ideal state. The angle of the slope is determined, and the change of the interval d between the survey lines has a similar law. Assuming that the survey line passing through the center of the sea area is taken as the benchmark, the angle between the survey lines is , according to the mathematical model of step 2, in Under certain conditions, the coverage width is related to the distance from the survey ship to the center of the sea area along the survey line direction: the survey line angles are different, and the intervals between the survey lines are different under the condition that the overlap rate is 10%-20%; Step 3.1.2: Based on the overlap ratio calculated in step 3.1.1, As the decision variable, the following optimization model is constructed: ; Step 3.1.3: Use the variable step-size search algorithm to solve the optimization model of step 3.1.2 to obtain the angle between the survey lines with the largest interval between the survey lines.

[0028] In this embodiment, 5 degrees is first used as the measuring line angle The step length is 0.1 nautical mile as the line interval The step size and coarseness search show that there is a situation where the overlap rate is between 10% and 20% between 85° and 95°. Within the range of 85° and 95°, the step size of the line angle is 1 degree and the step size of the line interval is 0.001 nautical miles. The best result appears at the line angle when the reference line passes through the center of the sea area. , and the maximum distance between the deep water side survey line is m.

[0029] Furthermore, the specific calculation process of step 3.1.1 is as follows: draw a north-south straight line through the center of the sea area, perpendicularly intersecting the east-west boundary at point O, such as Figure 6 As shown in the figure, with point O as the origin and the west direction of the east-west boundary as the positive direction of the x-axis, a plane rectangular coordinate system is constructed by satisfying the right-hand rule; the reference line intersects the east-west boundary at point , the water depth at the origin O is the same as the water depth at the center of the sea area, both are D, and the angle between the slope and the horizontal plane is , the direction vector of the reference line is: , the coordinates of the center of the sea area in this coordinate system are (0,1852), and the linear equation of the benchmark line is: ,but The coordinates of the point are: , the water depth at this point is: , Point on a straight line Distance to point O: ,point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , the coverage width on the shallow water side is: , Where: for Function of The adjacent survey line on the deep water side intersects the east-west boundary at point This survey line is equivalent to the benchmark survey line being shifted to the deep water side. , the equation of the line is: ,but The coordinates are: , The water depth at this point is: , the survey line is parallel to the reference survey line and is the reference survey line shifted to the left The point on the line is obtained. The distance is: ,point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , the coverage width on the shallow water side is: , Where: for Function of The distance between the reference survey line and its adjacent survey line on the deep water side is , then The overlap rate of the two lines is: .

[0030] Furthermore, the step 3.2 specifically includes the following steps: Step 3.2.1: Determine the recursive formula for the distance between the deepwater survey line and the benchmark survey line: The distance between the kth survey line on the deepwater side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the k-1th line is 10%, The specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the deep water side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , the width of detection on the shallow water side: , The coincidence rate between the baseline survey line and the first survey line on the deep water side is: , make ,but: ,make ,but: , The depth of the benchmark line is the interval between the second survey line and the benchmark line. , the depth of the survey line is: , Then the width of the second survey line measured on the deep water side is: , the width of detection on the shallow water side: , The overlap rate between the first survey line and the second survey line on the deep water side is: , make ,but: ,make ,but: ; Step 3.2.2: Determine the recursive formula for the distance between the shallow water side survey line and the benchmark survey line: The distance between the sth survey line on the shallow water side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the s-1th line is 10%, The specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the shallow side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , the width of detection on the shallow water side: , The coincidence rate between the reference survey line and the first survey line on the shallow water side is: , make ,but: , make ,but: , The interval between the second survey line and the benchmark survey line on the shallow water side of the benchmark survey line is , the depth of the survey line is: , The width of the second survey line measured on the deep water side is: , the width of detection on the shallow water side: , The overlap rate between the first and second survey lines on the shallow water side is: , make ,but: ,make ,but: .

[0031] Furthermore, the step 3.3 is as follows: u survey lines are required on the deep water side, and v survey lines are required on the shallow water side, and the total coverage width should exceed the east-west length of the rectangular area, that is, , Right now , after simplification: , The optimal deployment position of the benchmark survey line is the position where the number of u+v+1 is the smallest under the above conditions, so the following optimization model is constructed: , Traverse and solve the above model, from all the constraints that meet the and Select The minimum value of the sum, that is Minimum, The total number of measurement lines required is strip.

[0032] Example 2. A. Simulation experiment of the universal model of survey line spacing and coverage width Given the distance between the survey ship and the center of the sea area and the angle data of the survey line direction, a general model of survey line interval and coverage width was constructed, and the results were calculated as shown in Table 2. Table 1 Calculation results of Problem 2 , B. Simulation experiment of the optimal survey line deployment optimization model The given area is a rectangular area, 2 nautical miles long from north to south and 4 nautical miles wide from east to west. It can be understood that the center point of the sea area is the center point of the rectangle. Different, the coverage width is different, and it is related to the depth of the survey ship to the seabed. The shallower the depth to the seabed, the smaller the coverage width. The survey ship usually uses a Z-shaped route to search in the search area. In order to achieve full coverage of the area and simple operation, Z-shaped survey lines are usually selected for parallel distribution. When the survey ship is at a deeper depth from the seabed, the spacing d between the parallel survey lines is larger. When the survey ship is at a shallower depth from the seabed, the spacing between the survey lines is smaller. The spacing between the survey lines is variable, and its variation pattern is related to the angle between the survey lines. According to the requirements of the problem, the minimum overlap rate between the two survey lines must exceed 10%, and the maximum overlap rate must not exceed 20%.

[0033] The benchmark survey line is usually located in the center of the area, that is, the number of survey lines on the deep water side and the diving area side is not much different. Starting from 2, Starting from 2, the difference between the two is no more than 2, traverse and solve, first verify and Whether the value of satisfies the constraint condition, if it satisfies the constraint condition, select The minimum value of the sum, that is Minimum, at this time The total number of measurement lines required is After solving, it is found that at least 34 survey lines are needed to achieve full coverage of the entire rectangular area, and the overlap rate between adjacent survey lines is 10%. The total length of the 34 survey lines is: .

[0034] There are many such solutions. The horizontal axis coordinates of the benchmark survey line are searched and solved, with a step length of 50 meters. The search range is from deep water to the center of the sea area. The results are as follows: Figure 8 shown.

[0035] A set of solutions was randomly selected and searched around 3450 with a step size of 10. The search results are as follows Fig. 9 shown.

[0036] Select the solution with the horizontal axis coordinate of the benchmark line as 3490, and use the mathematical model and algorithm in step 1 to verify the results. The calculation results are shown in .from It can be seen that the overlap rate between any two survey lines is 10%, and the coverage width of the deep water side of the deepest water survey line is 365.39 meters, and the coverage width of the shallow water side of the shallow water survey line is 22.51 meters, both covering the north-south boundaries on both sides of the rectangular area. This scheme can achieve coverage of the entire sea area with the least number of survey lines.

[0037] Table 2 Verification of the search scheme for 34 survey lines , Under this scheme, the total navigation route of the survey ship is: (nautical miles).

[0038] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the defined scope.

Claims

1. A multi-beam survey line optimization method based on underwater topography measurement, characterized in that: The following steps are involved: Step 1: Construct a basic model of survey line interval and coverage width under ideal conditions, and determine the calculation method of basic data under this model; Step 2: Construct a basic model of line spacing and coverage width under actual conditions, and determine the calculation method of basic data under this model; Step 3: Establish a survey line deployment optimization model and perform corresponding solutions.

2. The multi-beam survey line optimization method based on underwater topography measurement according to claim 1, characterized in that: The step 1 specifically comprises the following steps: Step 1.1, establish the mathematical model of the basic model; Step 1.2, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of water depth height; Step 1.3, in the plane rectangular coordinate system established in step 1.1, determine the calculation method of the coverage width of the bathymetric strip of the survey vessel; Step 1.4: In the plane rectangular coordinate system established in step 1.1, determine the calculation method of the overlap rate between adjacent strips.

3. The multi-beam survey line optimization method based on underwater topography measurement according to claim 2 is characterized in that: The step 1.1 is as follows: select a section perpendicular to the direction of the measurement line, set the center point of the sea area as the left origin, the vertical downward direction as the positive direction of the x-axis, and the straight line between the horizontal plane and the vertical section as the y-axis, and construct a plane rectangular coordinate system according to the right-hand rule; The water depth in step 1.2 is related to the y-axis coordinate of the detection line where the survey ship is located. When the coordinate of the survey ship is y, the water depth height is: ; Where: The y coordinate of the location of the survey ship is 0, It means when the survey ship is at point y, that is, the distance from the survey ship to the center of the sea is y, the depth from the survey ship to the seabed. ; Indicates the angle between the detection line and the sea level; In step 1.3, the coverage width of the bathymetric strip of the survey ship is related to its depth to the seabed. For the survey ship at point y, the coverage width of its bathymetric strip is: ; Where: is the width measured along the slope towards the deep water side, is the width measured along the slope towards the shallow water side, , , Where: is the opening angle of the multi-beam transducer; The distance between the measurement lines of two adjacent measurement ships in step 1.4 is The detection overlap rate between the survey ship at point y and the survey ship on the shallow water side, i.e. the direction where the y coordinate increases, is: .

4. A multi-beam survey line optimization method based on underwater topography measurement according to claim 1, 2 or 3, characterized in that: The step 2 specifically includes the following steps: Step 2.1, establish a mathematical model of the general model; Step 2.2: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method of the distance from the survey ship to the seabed; Step 2.3: In the three-dimensional rectangular coordinate system established in step 2.1, determine the calculation method for the coverage width of the survey vessel's bathymetric strip.

5. The multi-beam survey line optimization method based on underwater topography measurement according to claim 4 is characterized in that: The step 2.1 is specifically as follows: a three-dimensional rectangular coordinate system is constructed with the intersection of a straight line passing through the center of the sea area and perpendicular to the horizontal plane and the slope as the origin of the coordinates, the projection of the normal vector of the slope on the horizontal plane as the positive direction of the x-axis, and the vertically upward direction as the positive direction of the z-axis; vector is the unit projection vector of the survey line direction on the horizontal xoy plane, then The angle with the positive x-axis is , , The unit vector in the opposite direction to the normal vector of the seafloor slope is: , The vector is projected onto the seabed slope, and the projection vector is the vector , the angle between the two vectors is the vector Angle with horizontal plane ,Right now The angle between the vector and the slope, Vector and The angle is ,but: ,have to: , and The unit vectors in the same direction are: , The beam is intercepted at a section perpendicular to the survey line. The intersection of the section and the ground is perpendicular to the survey line, so the vector ,vector is a vector On the slope, a single normal vector Counterclockwise rotation obtained; Known vector , direction vector ,like ,but Around Counterclockwise rotation angle The resulting vector is: , If the rotation is clockwise, the angle takes a negative value, and the vector for: ， Written in row vector form: , vector The angle with the xoy plane is , the coordinates of point A where the survey ship is located in the central sea area are ,vector With vector The angle is ,vector With vector Angle: ， because For vector Rotate to get, is a unit vector, so is also a unit vector, ,but .

6. The multi-beam survey line optimization method based on underwater topography measurement according to claim 4, characterized in that: The specific details of step 2.2 are as follows: when the survey ship sails along the survey line and keeps the survey line direction angle unchanged, the distance from the survey ship to the seabed will change, and its height will change with the distance from the survey ship to the center of the sea area. The change relationship is: ; The step 2.3 is as follows: The coverage width of the deep water side of the bathymetric strip is: ; The coverage width on the shallow water side is: , Coverage Width: , Where: y represents the distance from the measuring ship to the center of the sea area.

7. The multi-beam survey line optimization method based on underwater topography measurement according to claim 4 is characterized in that: The survey line optimization deployment model in step 3 includes the following steps: Step 3.1, under the condition that the overlap rate is 10%-20%, determine the angle between the survey lines with the largest interval between the survey lines; Step 3.2, under the condition of 10% overlap, determine the shortest measurement line length; Step 3.3: Determine the optimal reference line.

8. The multi-beam survey line optimization method based on underwater topography measurement according to claim 7 is characterized in that: The step 3.1 specifically includes the following steps: Step 3.1.1: Calculate the seawater depth, coverage width and overlap rate of the baseline survey line and the adjacent survey line on the deepwater side of the baseline survey line according to the mathematical model in step 1. The specific calculation process is as follows: Draw a north-south straight line through the center of the sea area, perpendicular to the east-west boundary at point O, with point O as the origin and the west direction of the east-west boundary as the positive direction of the x-axis. Construct a plane rectangular coordinate system that satisfies the right-hand rule; the benchmark line intersects the east-west boundary at point , the water depth at the origin O is the same as the water depth at the center of the sea area, both are D, and the angle between the slope and the horizontal plane is , the direction vector of the reference line is: , The coordinates of the center of the sea area in this coordinate system are (0,1852), and the linear equation of the benchmark line is: , but The coordinates of the point are: , the water depth at this point is: , Point on a straight line Distance to point O: , point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , The coverage width on the shallow water side is: , Where: for Function of The adjacent survey line on the deep water side intersects the east-west boundary at point This survey line is equivalent to the benchmark survey line being shifted to the deep water side. , the equation of the line is: , but The coordinates are: , the water depth at this point is: , This survey line is parallel to the benchmark survey line and is shifted to the left by the benchmark survey line. The point on the line is obtained. The distance is: , point The sea depth is: , The coverage width of the deep water side of the benchmark survey line is: , The coverage width on the shallow water side is: , Where: for Function of The distance between the reference survey line and its adjacent survey line on the deep water side is , then , The overlap ratio of the two lines is: ; Step 3.1.2: Based on the overlap ratio calculated in step 3.1.1, As the decision variable, the following optimization model is constructed: ; Step 3.1.3: Use the variable step-size search algorithm to solve the optimization model of step 3.1.2 to obtain the angle between the survey lines with the largest interval between the survey lines.

9. The multi-beam survey line optimization method based on underwater topography measurement according to claim 7, characterized in that: The step 3.2 specifically includes the following steps: Step 3.2.1: Determine the recursive formula for the distance between the deepwater survey line and the benchmark survey line: The distance between the kth survey line on the deepwater side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the k-1th line is 10%, , the specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the deep water side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , Detection width on the shallow water side: , The coincidence rate between the baseline survey line and the first survey line on the deep water side is: , make ,but: , make ,but: , The depth of the benchmark line is the interval between the second survey line and the benchmark line. , the depth of the survey line is: , Then the width of the second survey line measured on the deep water side is: , Detection width on the shallow water side: , The overlap rate between the first survey line and the second survey line on the deep water side is: , make ,but: , make ,but: ; Step 3.2.2: Determine the recursive formula for the distance between the shallow water side survey line and the benchmark survey line: The distance between the sth survey line on the shallow water side of the benchmark survey line and the benchmark survey line is , under the condition that the overlap rate of the s-1th line is 10%, The specific derivation process is as follows: The first survey line on the deep water side of the benchmark survey line, that is, the distance between the adjacent survey line on the shallow side and the benchmark survey line is , so the horizontal coordinate of the survey line is , the depth of the survey line is: , Then the width of the first survey line measured on the deep water side is: , Detection width on the shallow water side: , The coincidence rate between the reference survey line and the first survey line on the shallow water side is: , make ,but: , make ,but: , The interval between the second survey line and the benchmark survey line on the shallow water side of the benchmark survey line is , the depth of the survey line is: , The width of the second survey line measured on the deep water side is: , Detection width on the shallow water side: , The overlap rate between the first and second survey lines on the shallow water side is: , make ,but: , make ,but: .

10. The multi-beam survey line optimization method based on underwater topography measurement according to claim 7, characterized in that: The specific steps of step 3.3 are as follows: u survey lines are required on the deep water side, and v survey lines are required on the shallow water side. The total width of the survey lines should exceed the length of the rectangular area in the east-west direction, that is, ,Right now , After simplification, we get: , The optimal deployment position of the benchmark survey line is the position where the number of u+v+1 is the smallest under the above conditions, so the following optimization model is constructed: , Traverse and solve the above model, from all the constraints that meet the and Select The minimum value of the sum, that is Minimum, The total number of measurement lines required is strip.

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