A method for rapid slitting of aircraft nose skin

Abstract

This invention belongs to the field of aircraft design technology and discloses a method for rapid segmentation of the aircraft nose skin. The method divides the aircraft nose skin into a front half and a rear half based on the coordinates of the skin points according to predetermined boundaries. Then, the coordinates of the front and rear half of the nose skin are grouped and numbered according to a given axis. The rear half of the nose skin is then modeled in blocks, followed by the front half. This invention enables high-quality and efficient segmentation of the nose skin, thereby reducing design time and labor costs.

Description

Technical Field

[0001] This invention belongs to the field of aircraft design technology and relates to a method for rapid segmentation of the nose skin of an aircraft. Background Technology

[0002] Aircraft skin refers to the conical components that surround the aircraft's skeletal structure, forming the aircraft's aerodynamic shape. Fixed to the frame, it can be considered the aircraft's "skin." After being subjected to aerodynamic forces, it transmits these forces to the connected fuselage frame, making it a crucial part of the aircraft's aerodynamic structure. Since the skin is in direct contact with the external environment, it requires materials with high strength and high plasticity, as well as a smooth surface and high corrosion resistance. Initially, aircraft skin was typically made of fabrics such as cotton and linen. However, with the continuous evolution of technology and the increasing demands on aircraft speed, altitude, and weight, fabric materials have gradually been replaced by metal skins. Currently, the main material for aircraft skin is aluminum-magnesium alloy, with some high-performance aircraft using titanium alloys or composite materials. Based on the aircraft's shape, skins are classified into single-curvature skins, double-curvature skins, and complex-shaped skins. The relatively simple single-curvature skin has curvature in only one direction and is mostly used for the fuselage and wings. Double-curvature skin has curvature in two directions and is used for most aircraft air intakes and components. Complex-shaped skins are used for the nose and wingtips, among other areas.

[0003] Due to the complex shape of large aircraft nose sections, the nose skins are often complex shapes that cannot be fully covered by a single skin. Therefore, it is necessary to consider how to divide the nose skin size to meet the overall shape requirements and performance specifications, while also taking into account factors such as the size of the raw materials, manufacturing costs, and the skin's location. Currently, due to the relatively complex structure and high technical requirements of large aircraft nose sections, the initial division of the nose skin is mainly determined through offline discussions with experts. Then, by calculating processing costs and stress levels, the initial plan is adjusted and modified to determine the final division position. This process relies entirely on experts, resulting in a long division cycle and high labor costs. Therefore, there is an urgent need to conduct research on forward modular design technology for large aircraft components and to strengthen research on methods for dividing the nose skin into sections. The main purpose is to improve the efficiency of nose skin division, reduce the design cycle, and lower labor costs. Summary of the Invention

[0004] The purpose of this invention is to address the problems existing in the prior art by providing a method for rapid segmentation of aircraft nose skin, thereby improving the efficiency of aircraft nose skin segmentation, reducing design cycle, and lowering labor costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solutions.

[0006] The rapid cutting method for aircraft nose skin provided by this invention includes the following steps:

[0007] S1 divides the coordinates of the aircraft nose skin points into the front half of the nose skin and the rear half of the nose skin according to the set boundaries. The front half of the nose skin includes the position coordinates of the windshield. The coordinates of the front half of the nose skin and the rear half of the nose skin are grouped and numbered according to the given axis.

[0008] S2 performs block modeling of the rear half of the nose skin, defining the search boundary of the skin block as a spatial quadrilateral. The four vertices of the spatial quadrilateral are the coordinates of the starting point, the second point, the diagonal point, and the ending point, respectively. The set of coordinates from the starting point to the second point is defined as the line1 set, the set of coordinates from the second point to the diagonal point is defined as the line2 set, the set of coordinates from the diagonal point to the ending point is defined as the line3 set, and the set of coordinates from the ending point to the starting point is defined as the line4 set. This step includes the following sub-steps:

[0009] S21 determines the first layer segment of the rear half of the nose skin along the given axis;

[0010] Based on the determined first-layer segmentation, S22 segments the unsegmented area of ​​the rear half of the machine head according to the following steps:

[0011] S221 determines the lowest horizontal line between the undivided area and the boundary of the divided area in the rear half of the machine head, and determines whether the coordinate group of the lowest horizontal line is less than the maximum number of the coordinate group of the rear half of the machine head. If yes, proceed to step S222; otherwise, it means that the segmentation has been completed.

[0012] S222 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S223; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the blocks are divided, return to step S221.

[0013] S223 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S224; otherwise, proceed to step S225.

[0014] S224 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S221.

[0015] S225 divides the undivided area into blocks based on the point coordinates in the line3 set of each block where the lowest horizontal line is located, and returns to step S221 after the block division is completed;

[0016] S3 performs block modeling of the front half of the nose skin; based on the position coordinates of the windshield, it constructs the first and second skins. The first skin is the area from the front of the windshield to the front end face of the nose, and the second skin is the area of ​​the front half of the nose excluding the windshield and the first skin; the search boundary of the second skin block is defined as a spatial quadrilateral, with the four vertices of the spatial quadrilateral being the coordinates of the starting point, the second point, the diagonal point, and the ending point, respectively; the set of coordinates from the starting point to the second point is defined as the line1 set, the set of coordinates from the second point to the diagonal point is defined as the line2 set, the set of coordinates from the diagonal point to the ending point is defined as the line3 set, and the set of coordinates from the ending point to the starting point is defined as the line4 set; this step includes the following sub-steps:

[0017] S31 determines the first layer segment of the second skin along the given axis;

[0018] Based on the determined first layer of blocks, S32 divides the unblocked area of ​​the second skin in the front half of the engine head into blocks according to the following steps:

[0019] S321 determines the lowest horizontal line between the unsegmented area and the segmented area boundary of the second skin of the front half of the nose, and determines whether the coordinate group of the lowest horizontal line is less than the maximum number of the coordinate group of the front half of the nose. If yes, proceed to step S322; otherwise, it means that the segmentation has been completed.

[0020] S322 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S323; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the block division is completed, return to step S321.

[0021] S323 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S324; otherwise, proceed to step S325.

[0022] S324 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S321.

[0023] S325 divides the undivided area into blocks based on the point coordinates in the line3 set of each block containing the lowest horizontal line, and returns to step S321 after the block division is completed.

[0024] The segmentation operations in step S21 (first layer of the rear half of the nose skin), S222, S224, and S225 are all the same, and the steps are as follows:

[0025] (1) Based on the coordinate order in the coordinate group to be divided in the rear half of the nose skin, the second point coordinate of the previous block is used as the starting point coordinate of the current block. The distance from the starting point coordinate is not less than the first limit distance to obtain the second point coordinate of the current block. The starting point coordinate, the second point coordinate, and the point coordinate passing through the two points are stored in the line1 set of the current block.

[0026] (2) Along the given axis, find the nearest coordinates in the adjacent groups in turn until the distance to the second point coordinates is not less than the second limit distance, and obtain the diagonal coordinates of the current block; and store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block;

[0027] (3) Based on the starting point coordinates, along the given axis, find the nearest coordinates in the adjacent groups until they belong to the same group as the diagonal point coordinates, and obtain the ending coordinates of the current block; and store the starting point coordinates, ending coordinates, and coordinates of the points passing through the two points into the line4 set of the current block;

[0028] (4) Store the coordinates of the diagonal point, the endpoint coordinates, and the coordinates of the point passing through the two points into the line3 set of the current block;

[0029] (5) Connect the coordinates of the end of the line1 set, line2 set, line3 set and line4 set of the current block to obtain the current block;

[0030] (6) Determine whether the coordinates of the second point of the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step (1).

[0031] For the first layer of the nose cone skin in step S21 above, the current coordinate group to be divided is the first coordinate group of the nose cone skin. When the current block is the first block of the first layer, the first coordinate point is taken as the starting point coordinate of the current block according to the coordinate order in the first coordinate group of the nose cone skin. When the block division operation of the current coordinate group to be divided ends, the second point coordinate of the last block is the last coordinate in the first coordinate group, that is, the coordinate cycle in the first coordinate group is completed.

[0032] For the block division operations in steps S222, S224, and S225, the current coordinate group to be divided is composed of the point coordinates determined in steps S222, S224, and S225. When the current block is the first block in the current coordinate group to be divided, the first coordinate point is used as the starting point coordinate of the current block according to the coordinate order in the current coordinate group to be divided. When the block division operation of the current coordinate group to be divided ends, the second point coordinate of the last block is the last coordinate in the current coordinate group to be divided.

[0033] The segmentation operations in step S31 (first layer segmentation of the second skin), S322, S324, and S325 are all the same, and the steps are as follows:

[0034] ① Based on the coordinate order in the coordinate group to be divided in the second skin of the front half of the nose, determine the starting point coordinates. Then, find the second point coordinates in sequence according to the distance from the starting point coordinates not being less than the first limit distance. When it exceeds the boundary of the windshield, take the first boundary coordinate point that intersects the boundary as the second point coordinates. When it does not exceed the boundary of the windshield, take the coordinates that meet the first limit distance requirement as the second point coordinates of the current block. Store the second point coordinates, the diagonal point coordinates, and the coordinates of the points passing through the two points in the line2 set of the current block.

[0035] ②When the coordinates of the second point are located on the edge of the windshield and the given axis is within the edge of the windshield, abandon the search for the coordinates of the diagonal point;

[0036] Otherwise, along the given axis, find the nearest coordinates in adjacent groups according to the distance from the second point coordinates not less than the second limit distance. When it exceeds the windshield boundary, use the boundary coordinates that intersect the boundary as the diagonal coordinates; when it does not exceed the windshield boundary, use the coordinates that meet the second limit distance requirement as the diagonal coordinates of the current block; and store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block.

[0037] ③ When the starting point coordinates are located on the windshield boundary and the given axis is located within the windshield boundary, abandon the search for the endpoint coordinates;

[0038] Otherwise, when diagonal coordinates exist, based on the starting point coordinates, along the given axis, the nearest coordinates in adjacent groups belonging to the same group as the diagonal coordinates are searched sequentially. When the boundary of the windshield is exceeded, the boundary coordinates intersecting with the boundary are used as the endpoint coordinates; when the boundary of the windshield is not exceeded, the coordinates belonging to the same group as the diagonal coordinates are used as the endpoint coordinates of the current block. The starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points are stored in the line4 set of the current block.

[0039] When no diagonal point coordinates exist, the nearest coordinates in adjacent groups are searched sequentially according to the distance from the starting point coordinates not being less than the second limit distance. When the diagonal point coordinates are found beyond the windshield boundary, the boundary coordinates intersecting with the boundary are used as the diagonal point coordinates. When the diagonal point coordinates are not found beyond the windshield boundary, the coordinates that meet the second limit distance requirement are used as the endpoint coordinates of the current block. The starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points are stored in the line4 set of the current block.

[0040] ④ When both diagonal point and endpoint coordinates exist, store the diagonal point coordinates, endpoint coordinates, and coordinates of points passing through the two points into the line3 set of the current block; connect the endpoint coordinates of the line1, line2, line3, and line4 sets of the current block to obtain the current block; when there is a windshield boundary between the diagonal point coordinates and the endpoint coordinates, the corresponding boundary coordinates also need to be stored into the line3 set of the current block.

[0041] When there are diagonal points but no endpoint coordinates, the current block is obtained by connecting the line1 set, line2 set, and the windshield boundary coordinates of the current block.

[0042] When there are endpoint coordinates but no diagonal coordinates, search sequentially along the coordinate group containing the endpoint coordinates until the boundary coordinates intersect with the windshield boundary. Store the endpoint coordinates, boundary coordinates, and coordinates of the points passing through the two points into the line3 set of the current block. Connect the line1 set, line3 set, line4 set of the current block with the windshield boundary coordinates to obtain the current block.

[0043] ⑤ Determine whether the coordinates of the second point in the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step ①.

[0044] In step ① above, if the coordinates of the second point of the previous block are located at the boundary of the windshield, the second boundary coordinate point where the coordinate group of the second point of the previous block intersects with the boundary of the windshield is taken as the starting point coordinates of the current block.

[0045] If the coordinates of the second point of the previous block are not located on the edge of the windshield, the coordinates of the second point of the previous block shall be used as the starting point coordinates of the current block.

[0046] For the first layer of the second skin in step S31 above, the coordinate group to be divided is the first coordinate group of the front half of the second skin of the nose. When the current block is the first block of the first layer, the first coordinate point is taken as the starting point coordinate of the current block according to the coordinate order in the first coordinate group of the front half of the second skin of the nose. When the block division operation of the current coordinate group to be divided ends, the second point coordinate of the last block is the last coordinate in the first coordinate group, that is, the coordinate cycle in the first coordinate group is completed.

[0047] For the block division operations in steps S322, S324, and S325, the current coordinate group to be divided is composed of the point coordinates determined in steps S322, S324, or S325. When the current block is the first block in the current coordinate group to be divided, the first coordinate point is used as the starting point coordinate of the current block according to the coordinate order in the current coordinate group to be divided. When the block division operation of the current coordinate group to be divided ends, the second point coordinate of the last block is the last coordinate in the current coordinate group to be divided.

[0048] Compared with the prior art, the rapid segmentation method for aircraft nose skin provided by the present invention has the following advantages:

[0049] This invention first divides the aircraft nose into a front half and a rear half. Then, according to a given direction, the front half and the rear half are grouped by coordinates. Based on the coordinate grouping and combined with the target coordinate point determination method for skin segmentation, the front half and the rear half of the nose skin are divided. This enables high-quality and high-efficiency division of the nose skin, thereby reducing the design cycle and lowering labor costs. Attached Figure Description

[0050] Figure 1 This is a schematic diagram of the rapid segmentation method for aircraft nose skin provided in an embodiment of the present invention;

[0051] Figure 2 Visualization of the coordinates of points on the nose cone skin;

[0052] Figure 3 The visualization results after dividing the nose section; where (a) corresponds to the front half of the nose section and (b) corresponds to the rear half of the nose section.

[0053] Figure 4 Grouping results for the coordinates of points in the front half of the aircraft nose;

[0054] Figure 5 Grouping results for the coordinates of points in the rear half of the nose section;

[0055] Figure 6 A visualization of the front half of the aircraft nose obtained from two perspectives;

[0056] Figure 7 This is a schematic diagram showing the coordinates of the skin blocks.

[0057] Figure 8 A schematic diagram illustrating the process of segmenting and modeling the rear half of the nose section skin;

[0058] Figure 9 The process of segmenting the skin of the rear half of the machine head;

[0059] Figure 10 A schematic diagram illustrating the process of segmenting and modeling the front half of the nose section skin;

[0060] Figure 11 The process of segmenting the skin of the front half of the machine head;

[0061] Figure 12 The simplified operation procedure for the first layer of the second skin in the front half of the engine head;

[0062] Figure 13 To simplify the non-first-layer segmentation operation process of the second skin in the front half of the machine head;

[0063] Figure 14 The results of the skin division for the front half of the nose section;

[0064] Figure 15 The visualization results of the nose skin are shown; where (a) represents the segmentation result of the front half of the nose skin, and (b) represents the segmentation result of the rear half of the nose skin. Detailed Implementation

[0065] The technical solutions of various embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] Example

[0067] like Figure 1 As shown, the rapid segmentation method for aircraft nose skin provided in this embodiment includes the following steps:

[0068] S1 divides the coordinates of the aircraft nose skin points into the front half of the nose skin and the rear half of the nose skin according to the set boundaries. The front half of the nose skin includes the position coordinates of the windshield. S1 then groups and numbers the coordinates of the front half of the nose skin and the rear half of the nose skin according to the given axis.

[0069] The coordinates of all nose cone skin points are currently known. These coordinates will be imported into CATIA software for visualization. Figure 2 As shown. The length of the aircraft is taken as the x-axis.

[0070] Importing the data into CATIA reveals that the front half of the nose has a larger curvature and more openings, while the rear half has a gentler curvature and fewer openings. Therefore, the nose skin segmentation for large aircraft is divided into two parts, based on defined boundaries (e.g., the boundary between the cockpit and service bay), dividing the nose into a front half and a rear half. The point coordinates are then preprocessed, initially divided into two groups, and visualized in CATIA software, such as... Figure 3 As shown.

[0071] First, the coordinates of the points in the front half of the nose section are organized and preprocessed. Using the tail section of the divided front half of the nose section as the starting position, coordinate groups are encoded. The original coordinates are classified (mainly by the x-axis coordinates), ultimately resulting in 14 groups of coordinate data. The specific grouping files are as follows... Figure 4 As shown. Simultaneously, the point coordinates in the 14 sets of coordinate data are encoded and stored.

[0072] Next, the coordinates of the points in the rear half of the nose section are organized and preprocessed. Starting with the nose and tail of the large aircraft, coordinate groups are encoded. When importing these coordinates into CATIA, the import is primarily done sequentially using the x-axis coordinates. During the import process, the data is divided into 20 groups based on the x-axis coordinates of each point, and then imported into the modeling software in sequence. The specific grouped files are as follows: Figure 5 As shown, the 20 sets of data are divided into 11 coordinate groups through summarization and organization, as shown in Table 1. The specific points need to be encoded and stored in the future to facilitate their input into the program.

[0073] Table 1 Final grouping results of the rear half of the aircraft nose

[0074]

[0075] Meanwhile, the gaps were categorized in the same way: the front half of the nose mainly contains 5 gaps, and the rear half mainly contains 4 gaps. Due to the complex shape of the front half of the nose, three boundary conditions were set. These boundary conditions mainly consist of the three edges 1, 2, and 3 of the boundary at the front windshield position, specifically as follows: Figure 6As shown in (a), gaps in other locations are filled using coordinate points. The rear half of the nose mainly contains four gaps. For smaller gaps (such as those at the hatch locations), they do not affect the skin division and are not addressed here. For larger gaps (such as those at the landing gear locations), auxiliary coordinates can be added to fill the gaps until the requirements are met. Therefore, no boundary conditions are set for the rear half of the nose. These processes were completed before the point coordinate data was imported and are therefore not within the scope of protection claimed in this invention.

[0076] S2 performs block modeling of the rear half of the nose skin.

[0077] To achieve the segmentation of the skin in the rear half of the nose of a large aircraft, a mathematical model is first needed to randomly segment the skin, thereby generating an initial scheme to be optimized. Then, constraints are added to remove schemes that do not meet the constraints. This is mainly achieved through two steps: the first step is to obtain the skin segmentation result, and the second step is to visualize the segmentation result.

[0078] Before introducing the specific process, the meanings of the specific letter names are briefly described, as shown in Table 2:

[0079] Table 2 shows the letter names and their specific meanings in the embodiments.

[0080]

[0081] The search boundary for skinning blocks is defined as a spatial quadrilateral, with its four vertices representing the coordinates of the starting point, the second point, the diagonal points, and the ending point, respectively. The positions are as follows: Figure 7 As shown. The set of coordinates from the starting point to the second point is defined as line1, the set of coordinates from the second point to the diagonal point is defined as line2, the set of coordinates from the diagonal point to the ending point is defined as line3, and the set of coordinates from the ending point to the starting point is defined as line4.

[0082] The process of constructing the block modeling of the rear half of the nose skin is as follows: Figure 8 As shown, this is implemented through a program. First, the first layer of blocks is determined; after the first layer of blocks is completed, the position to be divided is located by finding the lowest horizontal line, and then the undivided area is divided into blocks. This process is repeated until the blocks of the rear half of the machine head skin are completed.

[0083] Based on the definition of the skin block search boundary given earlier, the block division mainly involves determining four coordinate points. Since the coordinates of the large aircraft nose skin points are known, and the grouping was completed during the skin point cloud coordinate preprocessing, the storage method in the specific implementation is ordered. Therefore, it is only necessary to move them in sequence to specify the direction of movement. First, the starting point coordinates are determined. Then, the coordinates of the second point that satisfies the movement limit distance within the coordinate group are found. Next, the coordinates of the diagonal point that satisfies the movement limit distance across coordinate groups are found along the given axis. Finally, the coordinates of the endpoint in the same coordinate group as the diagonal point are found from the starting point coordinates along the given axis, thus obtaining the blocks.

[0084] The distance traveled during the coordinate search process described above is primarily calculated using the distance formula for three-dimensional point coordinates. For two points A(x1, y1, z1) and B(x2, y2, z2) within the same coordinate set, the distance from point A to point B is:

[0085]

[0086] For two points C(x3,y3,z3) and D(x4,y4,z4) that span a coordinate system, the distance from point C to point D is:

[0087]

[0088] Because there are certain limitations on the size of the raw materials used for processing the skin, with the largest size being 7m*2.2m, it is necessary to compare the distances to avoid exceeding the maximum size and making processing impossible. R1 and R2 are randomly determined. If the length of R1 is greater than 2.2m and less than or equal to 7m, then the length of R2 must be less than or equal to 2.2m and greater than 0, and vice versa.

[0089] Based on the above analysis, step S2 specifically includes the following sub-steps:

[0090] S21 determines the first layer segment of the rear half of the nose skin along the given axial direction.

[0091] As previously mentioned, coordinate grouping starts from the nose and tail of the aircraft. Therefore, in this embodiment, the rear half of the nose skin is divided into blocks from the smallest to the largest coordinate group code. Specifically, the first layer of the rear half of the nose skin is determined starting from the position with the smallest coordinate group code.

[0092] Based on the determined first-layer segmentation, S22 segments the unsegmented area of ​​the rear half of the machine head according to the following steps:

[0093] S221 determines the lowest horizontal line between the undivided area and the boundary of the divided area in the rear half of the machine head (the lowest horizontal line is represented by the coordinate group number i), and determines whether the coordinate group i where the lowest horizontal line is located is less than the maximum number of the coordinate group of the rear half of the machine head (in this embodiment, the maximum number is 11). If yes, proceed to step S222; if no, it means that the segmentation has been completed.

[0094] S222 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S223; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the blocks are divided, return to step S221.

[0095] S223 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S224; otherwise, proceed to step S225.

[0096] S224 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S221.

[0097] S225 divides the undivided area into blocks based on the point coordinates in the line3 set of each block containing the lowest horizontal line, and returns to step S221 after the block division is completed.

[0098] The segmentation operations in step S21 (first layer of the rear half of the nose skin), S222, S224, and S225 are all the same, as shown above. Figure 9 As shown, the steps are as follows:

[0099] (1) Based on the current coordinate group k to be divided for the rear half of the nose skin. i In the coordinate order, the coordinates of the second point of the previous block are used as the coordinates of the starting point of the current block. The distance d1 from the starting point coordinates is not less than the first limit distance R1 (i.e., d1≥R1) to obtain the coordinates of the second point of the current block. The coordinates of the starting point, the coordinates of the second point, and the coordinates of the points passing through the two points are stored in the line1 set of the current block.

[0100] (2) Along the given axis, find the nearest coordinates in the adjacent groups until the distance d2 to the second point coordinates is not less than the second limit distance (i.e., d2≥R2), and obtain the diagonal coordinates of the current block; and store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block;

[0101] (3) Based on the starting point coordinates, along the given axis, find the nearest coordinates in the adjacent groups until they belong to the same group as the diagonal point coordinates, and obtain the ending coordinates of the current block; and store the starting point coordinates, ending coordinates, and coordinates of the points passing through the two points into the line4 set of the current block;

[0102] (4) Store the coordinates of the diagonal point, the endpoint coordinates, and the coordinates of the point passing through the two points into the line3 set of the current block;

[0103] (5) Connect the coordinates of the end of the line1 set, line2 set, line3 set and line4 set of the current block to obtain the current block; the line1, line2, line3 and line4 sets can be stored in the block set C;

[0104] (6) Determine whether the coordinates of the second point of the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step (1).

[0105] For the first layer of the nose cone skin in step S21 above, the current coordinate group to be divided is the first coordinate group of the nose cone skin. When the current block is the first block of the first layer, according to the coordinate order in the first coordinate group k1 of the nose cone skin, the first coordinate point k is used. 11 This serves as the starting point coordinate of the current block. When the block division operation of the current coordinate group is completed, the second point coordinate of the last block becomes the last coordinate in the first coordinate group, meaning that the coordinate cycle in the first coordinate group is complete.

[0106] For the block division operation in steps S222, S224, and S225, the current coordinate group to be divided is k. i The points are defined by the coordinates determined in steps S222, S224, and S225; the current block is the current coordinate group k to be divided. i When dividing the first block, the coordinates are ordered according to the coordinate order in the current coordinate group to be divided, starting with the first coordinate point k. i1 This serves as the starting point coordinate of the current block. When the block division operation for the current coordinate group ends, the second point coordinate of the last block becomes the last coordinate in the current coordinate group.

[0107] S3 performs block modeling of the front half of the nose skin.

[0108] The front half of the nose cone's skin is divided into the same blocks as the rear half. However, because the front half has a more irregular shape, more factors need to be considered before dividing it into blocks. After the previous preprocessing of the point cloud coordinates, the preprocessed point cloud coordinates of the front half of the nose cone are as follows: Figure 6As shown in (a) and 6(b).

[0109] Compared to the original, unprocessed state, the main difference lies in the area of ​​the windshield, specifically the region from the front of the windshield to the front edge of the engine (the front of the windshield is defined as 1-3 points offset to the left and right of the center position). Because the coordinates of this location are significantly different from other locations, it is removed separately. Based on the actual situation, this part is directly classified as a single skin layer, i.e., the first skin layer. Figure 6 As shown in (b), in this embodiment, the front end of the windshield is defined by offsetting one point to the left and right of the center position of the windshield, and the area from the front end of the windshield to the front end face of the nose cone is defined as the first skin. Therefore, this part is no longer included in the division of the front half of the nose cone.

[0110] The front half of the nose skin is divided in a similar manner to the rear half, but there are some differences. The most significant difference lies in the front windshield area. Since this part is no longer included in the overall division after preprocessing, boundary conditions need to be set to prevent it from being divided, which could lead to inaccurate results. Figure 6 As shown, the windshield boundary includes boundary 1, boundary 2 and boundary 3.

[0111] Based on the preceding analysis, the first skin has been defined. Here, the area of ​​the front half of the nose, excluding the windshield and the first skin, is defined as the second skin. The search boundary for the second skin is defined as a spatial quadrilateral, with its four vertices representing the coordinates of the starting point, the second point, the diagonal point, and the ending point, respectively. The set of coordinates from the starting point to the second point is defined as set line1, the set of coordinates from the second point to the diagonal point is defined as set line2, the set of coordinates from the diagonal point to the ending point is defined as set line3, and the set of coordinates from the ending point to the starting point is defined as set line4.

[0112] The process of constructing the segmented modeling of the front half of the nose skin is as follows: Figure 10 As shown, this is implemented through a program. First, the first layer of blocks is determined; after the first layer of blocks is completed, the position to be divided is located by finding the lowest horizontal line, and then the undivided area is divided into blocks. This process is repeated until the blocks of the front half of the machine head skin are completed.

[0113] Step S3 specifically includes the following sub-steps:

[0114] S31 determines the first layer segment of the second skin along the given axis.

[0115] As previously mentioned, coordinate grouping starts from the rear of the front half of the nose section and encodes the coordinate groups. Therefore, in this embodiment, the rear half of the nose skin is divided into blocks from the smallest to the largest coordinate group code. Here, the first layer of the rear half of the nose skin is determined starting from the position with the smallest coordinate group code.

[0116] Based on the determined first layer of blocks, S32 divides the unblocked area of ​​the second skin in the front half of the engine head into blocks according to the following steps:

[0117] S321 determines the lowest horizontal line (represented by coordinate group number i) between the unsegmented area and the segmented area of ​​the second skin in the front half of the nose cone, and determines whether the coordinate group i containing the lowest horizontal line is less than the maximum number of the coordinate group in the front half of the nose cone. If yes, proceed to step S322; otherwise, it means that the segmentation has been completed.

[0118] S322 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S323; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the block division is completed, return to step S321.

[0119] S323 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S324; otherwise, proceed to step S325.

[0120] S324 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S321.

[0121] S325 divides the undivided area into blocks based on the point coordinates in the line3 set of each block containing the lowest horizontal line, and returns to step S321 after the block division is completed.

[0122] The segmentation operations in step S31 (first layer segmentation of the second skin), S322, S324, and S325 are all the same, as follows: Figure 11 As shown, the steps are as follows:

[0123] ①Based on the coordinate group k′ to be divided in the second skin of the front half of the nose cone iThe coordinates are determined by first determining the starting point coordinates, and then the second point coordinates are found sequentially according to the distance from the starting point coordinates not less than the first limit distance. When the point exceeds the front windshield boundary (boundary 2), the first boundary coordinate point intersecting with the boundary (boundary 2) is used as the second point coordinates. When the point does not exceed the front windshield boundary, the second point coordinates of the current block are obtained according to the distance d1 from the starting point coordinates not less than the first limit distance R1 (i.e., d1≥R1). The second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points are stored in the line2 set of the current block.

[0124] If the coordinates of the second point of the previous block are located at the boundary of the windshield (boundary 1 or boundary 2), the coordinates of the second boundary point (that is, the coordinates of the point that intersects with the boundary of boundary 1 or boundary 3) of the coordinate group of the second point of the previous block are used as the starting point coordinates of the current block.

[0125] If the coordinates of the second point of the previous block are not located on the edge of the windshield, the coordinates of the second point of the previous block shall be used as the starting point coordinates of the current block.

[0126] ② When the coordinates of the second point are located on the windshield boundary (boundary 1 or boundary 2) and the given axis is located within the windshield boundary, abandon the search for the coordinates of the diagonal point;

[0127] Otherwise, along the given axis, find the nearest coordinates in the adjacent groups according to the distance from the second point coordinates not less than the second limit distance. When it exceeds the windshield boundary, use the boundary coordinates that intersect the boundary as the diagonal coordinates. When it does not exceed the windshield boundary, obtain the diagonal coordinates of the current block according to the distance d2 from the second point coordinates not less than the second limit distance R2 (i.e., d2≥R2). Then store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block.

[0128] ③ When the starting point coordinates are located on the windshield boundary (boundary 1) and the given axis is located within the windshield boundary, abandon the search for the endpoint coordinates;

[0129] Otherwise, when diagonal coordinates exist, based on the starting point coordinates, along the given axis, the nearest coordinates in adjacent groups belonging to the same group as the diagonal coordinates are searched sequentially. When the diagonal coordinates exceed the windshield boundary (boundary 1, boundary 2, or boundary 3), the boundary coordinates intersecting with the boundary are used as the endpoint coordinates; when the diagonal coordinates do not exceed the windshield boundary (boundary 1, boundary 2, or boundary 3), the coordinates belonging to the same group as the diagonal coordinates are used as the endpoint coordinates of the current block; and the starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points are stored in the line4 set of the current block.

[0130] When no diagonal point coordinates exist, the nearest coordinates in adjacent groups are searched sequentially according to the distance d2 from the starting point coordinates being no less than the second limit distance R2. When the diagonal point coordinates are found beyond the windshield boundary (boundary 1, boundary 2, or boundary 3), the boundary coordinates intersecting with the boundary are used as the diagonal point coordinates. When the diagonal point coordinates are not found beyond the windshield boundary (boundary 1, boundary 2, or boundary 3), the diagonal point coordinates of the current block are obtained according to the distance d2 from the second point coordinates being no less than the second limit distance R2 (i.e., d2≥R2). The starting point coordinates, the ending point coordinates, and the coordinates of the points passing through the two points are stored in the line4 set of the current block.

[0131] ④ When both diagonal and endpoint coordinates exist, store the diagonal coordinates, endpoint coordinates, and coordinates of points passing through the two points into the line3 set of the current block; when there is a windshield boundary between the diagonal coordinates and the endpoint coordinates, the corresponding boundary coordinates also need to be stored into the line3 set of the current block; the coordinates of the endpoints of the line1, line2, line3, and line4 sets of the current block are connected to obtain the current block; the line1, line2, line3, and line4 sets can be stored into the block set C.

[0132] When there are diagonal points but no endpoint coordinates, the current block is obtained by connecting the line1 set, line2 set, and windshield boundary coordinates; the line1, line2, line3, and line4 sets can be stored in the block set C.

[0133] When the endpoint coordinates exist but the diagonal coordinates do not, search sequentially along the coordinate group containing the endpoint coordinates until the boundary coordinates intersect with the windshield boundary. Store the endpoint coordinates, boundary coordinates, and coordinates of the points passing through the two points into the line3 set of the current block. Connect the line1, line3, and line4 sets of the current block with the windshield boundary coordinates to obtain the current block. The line1, line2, line3, and line4 sets can be stored in the block set C.

[0134] ⑤ Determine whether the coordinates of the second point in the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step ①.

[0135] For the first layer of the second skin in step S31 above, the coordinates to be divided in the current coordinate group, i.e., the first coordinate group of the front half of the second skin of the nose, are k′1. When the current block is the first block of the first layer, according to the coordinate order in the first coordinate group of the front half of the second skin of the nose, the first coordinate point k′ is used. 11This serves as the starting point coordinate of the current block. When the block division operation of the current coordinate group is completed, the second point coordinate of the last block becomes the last coordinate in the first coordinate group, meaning that the coordinate cycle in the first coordinate group is complete.

[0136] For the block division operations in steps S322, S324, and S325, the current coordinate group to be divided consists of the point coordinates determined in steps S322, S324, and S325; the current block is the current coordinate group to be divided, k′. i When dividing the first block, the coordinates are ordered according to the coordinate order in the current coordinate group to be divided, starting with the first coordinate point k′. i1 This serves as the starting point coordinate of the current block. When the block division operation for the current coordinate group ends, the second point coordinate of the last block becomes the last coordinate in the current coordinate group.

[0137] To further simplify the construction process of the front half of the nose section, the minimum distance between the windshield boundary 1 and the rear of the front half of the nose section can be set to be less than the minimum distance between boundary 2 and boundary 3 and the rear of the front half of the nose section, and the maximum distance between boundary 1 and the rear of the front half of the nose section is less than R2, and coordinate group 1 does not intersect with the windshield boundary. In this case, when the second skin of the front half of the nose section is divided into the first layer, boundary 2 and boundary 3 will not be involved, and when other areas of the second skin are divided, boundary 1 will not be involved.

[0138] At this point, the segmentation operation of the first layer of the second skin in step S31 above is as follows: Figure 12 As shown, the steps are as follows:

[0139] (i) Determine the starting point coordinates according to the coordinate order in the second skin coordinate group 1 (k′1) of the front half of the machine head. Then, based on the starting point coordinates, find the second point coordinates in sequence. According to the distance d1 from the starting point coordinates not being less than the first limit distance R1 (i.e., d1≥R1), obtain the second point coordinates of the current block. Store the second point coordinates, the diagonal point coordinates, and the point coordinates passing through the two points in the line2 set of the current block.

[0140] (ii) Along the given axis, based on the coordinates of the second point, find the nearest coordinates in the adjacent groups in turn. When it exceeds the front windshield boundary 1, take the boundary coordinates that intersect with boundary 1 as the diagonal coordinates. When it does not exceed the front windshield boundary, obtain the diagonal coordinates of the current block according to the distance d2 from the second point coordinates not being less than the second limit distance R2 (i.e., d2≥R2). Store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block.

[0141] (iii) Based on the starting point coordinates, find the nearest coordinates in the adjacent groups along the given axis, according to the coordinates belonging to the same group as the diagonal point coordinates. When it exceeds the front windshield boundary 1, take the boundary coordinate point that intersects with boundary 1 as the endpoint coordinates; when it does not exceed the front windshield boundary, take the coordinates belonging to the same group as the diagonal point coordinates as the endpoint coordinates of the current block; and store the starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points into the line4 set of the current block.

[0142] (iv) Store the coordinates of the diagonal point, the endpoint, and the coordinates of the point passing through the two points into the line3 set of the current block; when there is a windshield boundary between the diagonal point coordinates and the endpoint coordinates, the corresponding boundary coordinates also need to be stored into the line3 set of the current block; connect the coordinates of the endpoints of the line1, line2, line3, and line4 sets of the current block to obtain the current block; the line1, line2, line3, and line4 sets can be stored into the block set C;

[0143] (v) Determine whether the coordinates of the second point in the current block are the coordinates of the last point in coordinate group 1. If yes, complete the first-level block operation; otherwise, return to step (i).

[0144] The block operations in steps S322, S324, and S325 above, such as Figure 13 As shown, the steps are as follows:

[0145] (i′) Based on the current coordinate group k′ to be divided in the second skin of the front half of the nose cone. i The coordinates are determined by first determining the starting point coordinates, and then the second point coordinates are found sequentially according to the distance from the starting point coordinates not less than the first limit distance. When the point exceeds the front windshield boundary (boundary 2), the first boundary coordinate point intersecting with the boundary (boundary 2) is used as the second point coordinates. When the point does not exceed the front windshield boundary, the second point coordinates of the current block are obtained according to the distance d1 from the starting point coordinates not less than the first limit distance R1 (i.e., d1≥R1). The second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points are stored in the line2 set of the current block.

[0146] If the coordinates of the second point of the previous block are located at the windshield boundary (boundary 2), the coordinates of the second boundary point where the coordinates of the second point of the previous block intersect with the windshield boundary (boundary 3) shall be used as the starting point coordinates of the current block.

[0147] If the coordinates of the second point of the previous block are not located on the edge of the windshield, the coordinates of the second point of the previous block shall be used as the starting point coordinates of the current block.

[0148] (ii′) Since the coordinates of the second point are either located on the windshield boundary (boundary 2) or not on the windshield boundary (here, boundary 2), its given axis is not within the windshield boundary. Therefore, it is necessary to find the coordinates of the diagonal point. Along the given axis, the diagonal coordinates of the current block are obtained according to the distance d2 from the coordinates of the second point being no less than the second constraint distance R2 (i.e., d2≥R2). The coordinates of the second point, the diagonal coordinates, and the coordinates of the point passing through the two points are stored in the line2 set of the current block.

[0149] (iii′) Since the starting point coordinates are either located at the windshield boundary (here, boundary 3) or not located at the windshield boundary (here, boundary 3), their given axis is not within the windshield boundary. In both cases, it is necessary to find the endpoint coordinates. Based on the starting point coordinates, along the given axis, find the nearest coordinates in the adjacent groups. Use the coordinates that belong to the same group as the diagonal point coordinates as the endpoint coordinates of the current block. Store the starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points in the line4 set of the current block.

[0150] (iv′) Store the coordinates of the diagonal point, the endpoint coordinates, and the coordinates of the point passing through the two points into the line3 set of the current block; connect the coordinates of the endpoints of the line1 set, line2 set, line3 set, and line4 set of the current block to obtain the current block.

[0151] (v′) Determine whether the coordinates of the second point in the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step (i′).

[0152] Based on the modeling steps for the front and rear sections of the nose skin, the nose skin is segmented. For example, the front section of the nose skin can be divided programmatically. Different values ​​of R1 and R2 can be set according to actual needs, allowing for multiple divisions. The resulting segmentation is as follows. Figure 14 As shown, the partitioning results are different each time. The better partitioning scheme can be selected based on the partitioning results and other constraints. Figure 14 In the diagram, the fourth group represents the result of the fourth division. Groups 1 to 7 represent the division into 7 blocks. In group 1, Line 1, Line 2, Line 3, and Line 4 represent four sets of points. Line 1 (10) indicates that there are 10 points in this set, Line 2 (14) indicates that there are 14 points in this set, Line 3 (9) indicates that there are 10 points in this set, and Line 4 (14) indicates that there are 14 points in this set.

[0153] At this point, multiple skin segmentation schemes can be obtained. The current segmentation scheme considers the raw material length and the cross-joint constraint. To further optimize the segmentation scheme by taking stress concentration constraints into account, the points with high stress are first identified, and these points are restricted from being used as segmentation boundaries. The segmentation results are then filtered to obtain the final skin segmentation scheme.

[0154] Since displaying the results as point coordinates is not very intuitive, visualizing the results can yield the following results: Figure 15 (a) (front half of the nose) and Figure 15 (b) (rear half of the machine head) shows that each piece is a different color.

[0155] Those skilled in the art will recognize that the embodiments described herein are intended to help the reader understand the principles of the invention, and should be understood that the scope of protection of the invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific modifications and combinations based on the technical teachings disclosed in this invention without departing from the spirit of the invention, and these modifications and combinations are still within the scope of protection of this invention.

Claims

1. A method for rapid cutting of aircraft nose skin, characterized in that, Includes the following steps: S1 divides the coordinates of the aircraft nose skin points into the front half of the nose skin and the rear half of the nose skin according to the set boundaries. The front half of the nose skin includes the position coordinates of the windshield. The coordinates of the front half of the nose skin and the rear half of the nose skin are grouped and numbered according to the given axis. S2 performs block modeling of the rear half of the nose skin, defining the search boundary of the skin block as a spatial quadrilateral. The four vertices of the spatial quadrilateral are the coordinates of the starting point, the second point, the diagonal point, and the ending point, respectively. The set of coordinates from the starting point to the second point is defined as the line1 set, the set of coordinates from the second point to the diagonal point is defined as the line2 set, the set of coordinates from the diagonal point to the ending point is defined as the line3 set, and the set of coordinates from the ending point to the starting point is defined as the line4 set. This step includes the following sub-steps: S21 determines the first layer segment of the rear half of the nose skin along the given axis; Based on the determined first-layer segmentation, S22 segments the unsegmented area of ​​the rear half of the machine head according to the following steps: S221 determines the lowest horizontal line between the undivided area and the boundary of the divided area in the rear half of the machine head, and determines whether the coordinate group of the lowest horizontal line is less than the maximum number of the coordinate group of the rear half of the machine head. If yes, proceed to step S222; otherwise, it means that the segmentation has been completed. S222 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S223; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the blocks are divided, return to step S221. S223 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S224; otherwise, proceed to step S225. S224 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S221. S225 divides the undivided area into blocks based on the point coordinates in the line3 set of each block where the lowest horizontal line is located, and returns to step S221 after the block division is completed; S3 performs block modeling of the front half of the nose skin; based on the position coordinates of the windshield, it constructs the first and second skins. The first skin is the area from the front of the windshield to the front end face of the nose, and the second skin is the area of ​​the front half of the nose excluding the windshield and the first skin; the search boundary of the second skin block is defined as a spatial quadrilateral, with the four vertices of the spatial quadrilateral being the coordinates of the starting point, the second point, the diagonal point, and the ending point, respectively; the set of coordinates from the starting point to the second point is defined as the line1 set, the set of coordinates from the second point to the diagonal point is defined as the line2 set, the set of coordinates from the diagonal point to the ending point is defined as the line3 set, and the set of coordinates from the ending point to the starting point is defined as the line4 set; this step includes the following sub-steps: S31 determines the first layer segment of the second skin along the given axis; Based on the determined first layer of blocks, S32 divides the unblocked area of ​​the second skin in the front half of the engine head into blocks according to the following steps: S321 determines the lowest horizontal line between the unsegmented area and the segmented area boundary of the second skin of the front half of the nose, and determines whether the coordinate group of the lowest horizontal line is less than the maximum number of the coordinate group of the front half of the nose. If yes, proceed to step S322; otherwise, it means that the segmentation has been completed. S322 Determine whether the number m of the lowest horizontal line is greater than 1. If yes, proceed to step S323; otherwise, divide the undivided area into blocks based on the point coordinates in the block set line3. After the block division is completed, return to step S321. S323 Determine whether all blocks containing the lowest horizontal lines are adjacent. If yes, proceed to step S324; otherwise, proceed to step S325. S324 merges the point coordinates in the line3 set of adjacent blocks, and then divides the undivided area into blocks based on the merged point coordinates. After the block division is completed, return to step S321. S325 divides the undivided area into blocks based on the point coordinates in the line3 set of each block containing the lowest horizontal line, and returns to step S321 after the block division is completed.

2. The method for rapid cutting of aircraft nose skin according to claim 1, characterized in that, The segmentation operations in step S21 (first layer of the rear half of the nose skin), S222, S224, and S225 are all the same, and the steps are as follows: (1) Based on the coordinate order in the coordinate group to be divided in the rear half of the nose skin, the second point coordinate of the previous block is used as the starting point coordinate of the current block. The distance from the starting point coordinate is not less than the first limit distance to obtain the second point coordinate of the current block. The starting point coordinate, the second point coordinate, and the point coordinate passing through the two points are stored in the line1 set of the current block. (2) Along the given axis, find the nearest coordinates in the adjacent groups in turn until the distance to the second point coordinates is not less than the second limit distance, and obtain the diagonal coordinates of the current block; and store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block; (3) Based on the starting point coordinates, along the given axis, find the nearest coordinates in the adjacent groups until they belong to the same group as the diagonal point coordinates, and obtain the ending coordinates of the current block; and store the starting point coordinates, ending coordinates, and coordinates of the points passing through the two points into the line4 set of the current block; (4) Store the coordinates of the diagonal point, the endpoint coordinates, and the coordinates of the point passing through the two points into the line3 set of the current block; (5) Connect the coordinates of the end of the line1 set, line2 set, line3 set and line4 set of the current block to obtain the current block; (6) Determine whether the coordinates of the second point of the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step (1).

3. The method for rapid segmentation of aircraft nose skin according to claim 2, characterized in that, For the first layer of the rear half of the nose skin in step S21, the current coordinate group to be divided is the coordinate of the first coordinate group of the rear half of the nose skin. When the current segment is the first segment of the first layer, the first coordinate point is taken as the starting point coordinate of the current segment according to the coordinate order in the first coordinate group of the rear half of the nose skin; When the current block division operation of the coordinate group is completed, the second point coordinate of the last block is the last coordinate in the first coordinate group, which means that the coordinate cycle in the first coordinate group is complete.

4. The method for rapid cutting of aircraft nose skin according to claim 2, characterized in that, For the block division operation in steps S222, S224, and S225, the current coordinate group to be divided is composed of the point coordinates determined in steps S222, S224, or S225; when the current block is the first block in the current coordinate group to be divided, the first coordinate point is taken as the starting point coordinate of the current block according to the coordinate order in the current coordinate group to be divided. When the current coordinate group to be divided into blocks is finished, the second point coordinate of the last block is the last coordinate in the current coordinate group to be divided.

5. The method for rapid cutting of aircraft nose skin according to claim 1, characterized in that, The segmentation operations in step S31 (first layer segmentation of the second skin), S322, S324, and S325 are all the same, and the steps are as follows: ① Based on the coordinate order in the coordinate group to be divided in the second skin of the front half of the nose, determine the starting point coordinates. Then, find the second point coordinates in sequence according to the distance from the starting point coordinates not being less than the first limit distance. When it exceeds the boundary of the windshield, take the first boundary coordinate point that intersects the boundary as the second point coordinates. When it does not exceed the boundary of the windshield, take the coordinates that meet the first limit distance requirement as the second point coordinates of the current block. Store the second point coordinates, the diagonal point coordinates, and the coordinates of the points passing through the two points in the line2 set of the current block. ②When the coordinates of the second point are located on the edge of the windshield and the given axis is within the edge of the windshield, abandon the search for the coordinates of the diagonal point; Otherwise, along the given axis, find the nearest coordinates in adjacent groups according to the distance from the second point coordinates not less than the second limit distance. When it exceeds the windshield boundary, use the boundary coordinates that intersect the boundary as the diagonal coordinates; when it does not exceed the windshield boundary, use the coordinates that meet the second limit distance requirement as the diagonal coordinates of the current block; and store the second point coordinates, the diagonal coordinates, and the coordinates of the points passing through the two points into the line2 set of the current block. ③ When the starting point coordinates are located on the windshield boundary and the given axis is located within the windshield boundary, abandon the search for the endpoint coordinates; Otherwise, when diagonal coordinates exist, based on the starting point coordinates, along the given axis, the nearest coordinates in adjacent groups belonging to the same group as the diagonal coordinates are searched sequentially. When the boundary of the windshield is exceeded, the boundary coordinates intersecting with the boundary are used as the endpoint coordinates; when the boundary of the windshield is not exceeded, the coordinates belonging to the same group as the diagonal coordinates are used as the endpoint coordinates of the current block. The starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points are stored in the line4 set of the current block. When no diagonal point coordinates exist, the nearest coordinates in adjacent groups are searched sequentially according to the distance from the starting point coordinates not being less than the second limit distance. When the diagonal point coordinates are found beyond the windshield boundary, the boundary coordinates intersecting with the boundary are used as the diagonal point coordinates. When the diagonal point coordinates are not found beyond the windshield boundary, the coordinates that meet the second limit distance requirement are used as the endpoint coordinates of the current block. The starting point coordinates, endpoint coordinates, and coordinates of the points passing through the two points are stored in the line4 set of the current block. ④ When both diagonal point and endpoint coordinates exist, store the diagonal point coordinates, endpoint coordinates, and coordinates of points passing through the two points into the line3 set of the current block; connect the endpoint coordinates of the line1, line2, line3, and line4 sets of the current block to obtain the current block; when there is a windshield boundary between the diagonal point coordinates and the endpoint coordinates, the corresponding boundary coordinates also need to be stored into the line3 set of the current block. When there are diagonal points but no endpoint coordinates, the current block is obtained by connecting the line1 set, line2 set, and the windshield boundary coordinates of the current block. When there are endpoint coordinates but no diagonal coordinates, search sequentially along the coordinate group containing the endpoint coordinates until the boundary coordinates intersect with the windshield boundary. Store the endpoint coordinates, boundary coordinates, and coordinates of the points passing through the two points into the line3 set of the current block. Connect the line1 set, line3 set, line4 set of the current block with the windshield boundary coordinates to obtain the current block. ⑤ Determine whether the coordinates of the second point in the current block are the coordinates of the last point in the current coordinate group to be divided. If yes, complete the block division operation of the current coordinate group to be divided; otherwise, return to step ①.

6. The method for rapid cutting of aircraft nose skin according to claim 5, characterized in that, In step ①, if the coordinates of the second point of the previous block are located on the edge of the windshield, the coordinates of the second point of the previous block intersect with the edge of the windshield at the second boundary coordinate point, which is the starting point coordinate of the current block. If the coordinates of the second point of the previous block are not located on the edge of the windshield, the coordinates of the second point of the previous block shall be used as the starting point coordinates of the current block.

7. The method for rapid segmentation of aircraft nose skin according to claim 5, characterized in that, For the first layer of the second skin in step S31, the coordinate group to be divided is the first coordinate group of the second skin in the front half of the nose. When the current segment is the first segment of the first layer, the first coordinate point is taken as the starting point coordinate of the current segment according to the coordinate order in the first coordinate group of the second skin of the front half of the nose. When the current block division operation of the coordinate group is completed, the second point coordinate of the last block is the last coordinate in the first coordinate group, which means that the coordinate cycle in the first coordinate group is complete.

8. The method for rapid segmentation of aircraft nose skin according to claim 5, characterized in that, For the block division operation in steps S322, S324, and S325, the current coordinate group to be divided is composed of the point coordinates determined in steps S322, S324, and S325; when the current block is the first block in the current coordinate group to be divided, the first coordinate point is taken as the starting point coordinate of the current block according to the coordinate order in the current coordinate group to be divided. When the current coordinate group to be divided into blocks is finished, the second point coordinate of the last block is the last coordinate in the current coordinate group to be divided.

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