CN114611248A - Three-dimensional reconstruction method, device, medium and equipment for machining blank of airplane radome - Google Patents
Three-dimensional reconstruction method, device, medium and equipment for machining blank of airplane radome Download PDFInfo
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Abstract
The invention relates to a three-dimensional reconstruction method, a device, a medium and equipment for a blank machined by an airplane radome, which comprises the steps of measuring scene arrangement, planning a measuring path, automatic measurement, point cloud pretreatment and curved surface reconstruction. During point cloud data processing, under the condition that the surface characteristic information of the blank is reserved through a non-uniform simplified algorithm, the point cloud data volume is simplified, and the subsequent point cloud data processing speed and the model reconstruction efficiency are improved.
Description
Technical Field
The invention relates to the technical field of mechanical reverse engineering, in particular to a three-dimensional reconstruction method, a device, a medium and equipment for a blank part processed by an airplane radome.
Background
With the development of industrial technology and military equipment in China, a plurality of precise thin-wall parts are arranged in the aerospace field, and have the advantages of complex structure, large curvature of a molded surface and high requirement on forming precision. The radome is a structural/pneumatic/wave-transmitting/stealth functional integrated composite material part and has the structural characteristics of a typical large-scale complex aviation composite material. Need carry out the operation of polishing many times in the radome manufacturing process, and the process of polishing need the strict control polish surface and get rid of volume precision and power of polishing, should satisfy the regional profile precision of polishing of combined material solid core, avoid the damage of polishing of the ultra-thin covering of honeycomb sandwich structure again, on the other hand, the metal function structure on radome surface need initiatively be dodged to the in-process of polishing. However, the traditional polishing mode of the large radome is mainly that traditional manual polishing is adopted, polishing efficiency is low, dust harm is large, a digital polishing scheme needs to be formulated for the equipment, a three-dimensional model of the surface of a blank workpiece is reconstructed as a first link of the polishing scheme, the quality of three-dimensional reconstruction directly influences the final forming precision of the blank workpiece, and the technical problem of three-dimensional reconstruction of the blank workpiece made of the large composite material needs to be solved urgently.
At present, the research on the three-dimensional reconstruction technology of large components such as airplane radomes is less, and for the acquisition of measured data of blank workpieces, a manual scanning acquisition mode is basically adopted, so that the mode has low automation level and poor data quality stability, and the digital and intelligent conversion requirements from a large manufacturing country to a strong manufacturing country in China cannot be met. In addition, when the traditional point cloud data processing method aims at the reconstruction processing of large-size blank workpieces, the application of the method facing the machining field has extremely high requirements on the accuracy of a reconstructed model, so that the huge data volume caused by the method consumes a great deal of time during the subsequent reconstruction processing, and the production efficiency is influenced. Therefore, it is necessary to provide a three-dimensional reconstruction method for a blank workpiece model, which satisfies the requirements of large measurement scale, small data quality fluctuation, high point cloud processing speed and high reconstruction accuracy.
Disclosure of Invention
The invention aims to provide a three-dimensional reconstruction method, a device, a medium and equipment for a blank part machined by an airplane radome, and aims to solve the problems of low automation level, large fluctuation of acquired data and low data processing speed in reconstruction of a large-scale composite material blank workpiece model in the prior art.
In order to achieve the purpose, the invention adopts the following technical scheme:
a three-dimensional reconstruction method for a blank part processed by an aircraft radome comprises the following steps:
s1, arranging a measurement scene, including arrangement of a blank workpiece, a rotary tool, a measurement robot, a three-dimensional scanner and a global positioning camera, wherein mark points are arranged on the rotary tool, and high-reflection points are marked on the three-dimensional scanner;
s2, partitioning according to the model curved surface of the blank workpiece design, and sequentially planning the measurement path of the partitioned surface according to the circumferential sequence to realize the full coverage of the measurement path of the surface of the blank workpiece;
s3, operating a rotary tool, and automatically scanning and measuring the area to be processed of the blank workpiece by a three-dimensional scanner to obtain three-dimensional point cloud data of the blank workpiece; starting a mark point on a global positioning camera monitoring rotary tool and a high-reflection point on a three-dimensional scanner, acquiring a spatial position relation between the three-dimensional scanner and a blank workpiece in real time, splicing acquired three-dimensional point cloud data according to the spatial position of the mark point, and generating an edge feature point;
s4, filtering and simplifying the point cloud data of the blank workpiece;
and S5, performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data, and reconstructing a three-dimensional model of the blank workpiece.
Further, in step S1:
the blank workpiece is a large composite panel formed by coating a glass fiber reinforced material on the surface of a complex curved mold and curing;
the rotary tool is composed of a rotary worktable and a positioning and clamping fixture, the rotary worktable is used for providing rotary motion and is matched with a measuring robot to finish the measurement work of all areas to be processed, a mark point is arranged on the lower edge of the rotary worktable and is used as a corresponding point for registration splicing of multi-frame scanning data during scanning;
the positioning and clamping fixture is used for fixing blank workpieces, fixing different blank workpieces at specified positions according to mounting standards, and clamping the blank workpieces on the rotary fixture in a hoisting mode;
the measuring robot is a six-axis robot, is arranged beside the rotary worktable and is used for clamping the three-dimensional scanner to scan and collect the blank workpiece according to the partition planning path, and takes a rotating shaft of the rotary worktable as a seventh axis of the measuring robot so as to be matched with the measuring robot for linkage;
the three-dimensional scanner is a scanning instrument with high light reflection points, is clamped at the execution tail end of the measuring robot and is used for acquiring space coordinate information of a blank workpiece by utilizing a laser triangulation distance measuring principle, and N high light reflection mark points are marked on the three-dimensional scanner, wherein N is more than or equal to 32;
the overall positioning camera is hung on one side of the rotary tool, the acquisition direction of the overall positioning camera faces the blank workpiece, and the overall positioning camera is used for capturing the space coordinate information of the mark points, monitoring the mark points on the rotary worktable and the high reflection points on the three-dimensional scanner, acquiring the space position relation between the three-dimensional scanner and the blank workpiece in real time, and completing the splicing of multi-frame point clouds in the scanning process.
Further, in step S1, the method for spatially positioning a blank workpiece includes: the method comprises the steps of placing a combination of a blank workpiece and a complex curved die on the table top of a rotary table by using a crown block, adjusting the position of the die by using a positioning block, fixing the die on the rotary table by using a positioning clamping clamp, wherein different die clamping positions are different, reserving radial T-shaped grooves on the table top of the rotary table and the mounting surface of the blank workpiece, clamping the blank workpiece in the T-shaped grooves, positioning the blank workpiece by using reference blocks in X, Y two directions, enabling the blank workpiece to coincide with the rotation center of the rotary table, and fixing the blank workpiece on the table top of the rotary table by using T-shaped screws and pressing plates to complete the positioning of the blank workpiece.
Further, in step S2, the method for measuring the path plan includes: the curved surface measurement area needs to be divided when the measurement track planning is carried out, the sectorial measurement is adopted according to the characteristics of a specific blank workpiece, the blank workpiece is rotated after the current sector measurement is finished once, and the next sector measurement is carried out until the whole blank workpiece is finished once.
Further, in step S3, the method of scan measurement includes:
setting a bottom plane before scanning, so that only data points above the bottom plane are reserved when measurement data are dynamically displayed in real time, respectively obtaining laser linear arrays projected onto a scanning sample piece through two groups of cameras arranged on a three-dimensional scanner, wherein the linear arrays deform along with the shape of a measured object, and acquiring linear three-dimensional point cloud data projected by the laser linear arrays through calculation;
meanwhile, the global positioning camera tracks high-reflection points on the three-dimensional scanner in real time, relative information of the spatial position of the scanner is acquired in real time, the relative position of a blank workpiece can deviate after the rotary worktable rotates, and the automatic alignment and splicing functions of the two scanning parts can be realized through the mark points.
Further, the implementation process of step S4 includes:
a. denoising the point cloud, namely removing noise points generated in the scanning process by adopting a statistical filtering method to ensure the reconstruction quality of a subsequent model;
b. extracting characteristic points, and expressing the average distance d from the point cloud in the local neighborhood range to the tangent plane as
In the formula, p is a characteristic point cloud; k is the number of point clouds in the local neighborhood range of the p point; p is a radical ofjPoint cloud in local neighborhood range of p points(ii) a j is any value from 1 to k; n ispIs the average normal vector at p points;
if d is larger than the threshold value, the point is considered as a characteristic point;
c. determining the optimal region, determining the lower limit r of the search radius of the regionminAnd upper limit rmaxAnd varying the step length r△Setting the search radius R as R, and sequentially setting R as Rmin+r△Respectively calculating corresponding dimension characteristics and entropy function values of the point clouds in the local neighborhood according to the search radius until R is more than RmaxFinally, selecting the minimum entropy function value through comparison, and taking the neighborhood range obtained by the result as the optimal neighborhood;
d. determining weight, and calculating the weight w of the local optimal neighborhood of the non-feature point according to the local neighborhood densityiThe calculation formula is
In the formula, piCharacteristic point cloud is obtained; k is piThe number of point clouds within a local neighborhood of a point; p is a radical ofjPoint cloud in the local neighborhood range of the p points; j is any value from 1 to k;
e. and determining an optimal point, after the optimal neighborhood radius R is determined, setting x as the optimal point in the optimal neighborhood R, setting c as the central point of the selected non-characteristic local neighborhood range point cloud, calculating whether the optimal point is located in the optimal neighborhood range, namely whether the optimal point meets the condition | x-c | < R, and if the x is located in the optimal neighborhood range, replacing the point cloud in the whole neighborhood range by the optimal point x to obtain simplified point cloud data.
Further, in step S5, the step of three-dimensional reconstruction of the model includes:
a. selecting a non-uniform rational B-spline curve based on the edge feature points and the three-dimensional coordinate data;
b. selecting a non-uniform rational B spline curve function, and performing curve surface fitting;
c. and generating a three-dimensional model of the blank by fitting the curve surface.
Based on the three-dimensional reconstruction method for the airplane radome machining blank, the invention also provides a model establishing device of the method, which comprises the following steps:
the first processing unit is used for partitioning according to a blank workpiece design model curved surface, and sequentially planning measurement paths on the partitioned surfaces according to a circumferential sequence to complete full coverage of the measurement paths on the surface of the blank workpiece;
the second processing unit is used for controlling the operation of the rotary tool, controlling the three-dimensional scanner to automatically scan and measure the area to be processed of the blank workpiece, starting the global positioning camera, acquiring the spatial position relation between the three-dimensional scanner and the blank workpiece in real time, splicing the acquired multi-frame point cloud data according to the spatial position of the mark points, and generating edge feature points;
the third processing unit is used for filtering and simplifying the point cloud data of the blank workpiece;
and the fourth processing unit is used for performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data and reconstructing a three-dimensional model of the blank workpiece.
Based on the three-dimensional reconstruction method for the aircraft radome processing blank, the invention also provides a computer readable storage medium of the method, wherein a computer program is stored on the computer readable storage medium, and the computer program is executed by a processor to realize the steps of the three-dimensional reconstruction method for the aircraft radome processing blank.
Based on the three-dimensional reconstruction method for the airplane radome machining blank, the invention also provides computer equipment of the method, which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor realizes the steps of the three-dimensional reconstruction method for the airplane radome machining blank when executing the computer program.
Due to the adoption of the technical scheme, the invention has the following advantages:
1. by adopting a mode of linkage of a rotary tool and a measuring robot, automatic full-coverage measurement of the surface of a large-sized composite material blank piece can be realized, and the problem of unstable quality of data on the surface of a large-sized blank workpiece obtained by traditional manual measurement is solved;
2. in the measuring process, a global positioning camera is adopted to capture the space coordinate information of the mark points, and the scanner splices the acquired multi-frame point cloud data according to the space positions of the mark points during scanning, so that the mark points are prevented from being arranged on the surface of the blank workpiece, and the forming precision of the surface of the blank workpiece is ensured;
3. during point cloud data processing, under the condition that the surface characteristic information of the blank is reserved through a non-uniform simplified algorithm, the point cloud data volume is simplified, and the subsequent point cloud data processing speed and the model reconstruction efficiency are improved.
Drawings
Various additional advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments. The drawings are only for purposes of illustrating the preferred embodiments and are not to be construed as limiting the invention. Like reference numerals refer to like parts throughout the drawings.
In the drawings:
FIG. 1 is a flow chart of a method for three-dimensional reconstruction of a blank for machining an aircraft radome according to an embodiment of the present invention;
fig. 2 is a schematic diagram of a measurement scene layout of a three-dimensional reconstruction method for an aircraft radome machining blank according to the embodiment of the invention;
fig. 3 is a schematic view of a profile partition measurement path planning of the three-dimensional reconstruction method for the aircraft radome processing blank according to the embodiment of the invention;
fig. 4 is a flow chart of point cloud data preprocessing of the three-dimensional reconstruction method for the aircraft radome machining blank according to the embodiment of the invention.
The reference symbols in the drawings denote the following:
1-a blank workpiece; 2-rotating the tool; 3-a measuring robot; 4-a three-dimensional scanner; 5-global positioning camera.
Detailed Description
Exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. While exemplary embodiments of the invention are shown in the drawings, it should be understood that the invention can be embodied in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.
In the prior art, the reconstruction automation level of the large-scale composite material blank workpiece model is low, the fluctuation of acquired data is large, and the data processing speed is low. The invention can realize the automatic full-coverage measurement of the surface of the large-scale composite material blank by the steps of measurement scene arrangement, measurement path planning, automatic measurement, point cloud pretreatment and curved surface reconstruction in a mode of linkage of a rotary tool and a measurement robot, solves the problem of unstable quality of the surface data of the large-scale blank workpiece obtained by traditional manual measurement, adopts a global positioning camera to capture the space coordinate information of a mark point in the measurement process, and splices a plurality of frames of point cloud data obtained by a scanner according to the space position of the mark point during scanning, thereby avoiding the mark point arrangement on the surface of the blank workpiece, ensuring the forming precision of the surface of the blank workpiece, and simultaneously simplifying the amount of the point cloud data under the condition of retaining the surface characteristic information of the blank by a non-uniform simplified algorithm during processing the point cloud data, the speed of subsequent point cloud data processing and the model reconstruction efficiency are improved.
The embodiment of the present invention will be described in detail by examples.
Examples
As shown in fig. 1, a three-dimensional reconstruction method for an aircraft radome machining blank according to an embodiment of the present invention includes the following steps:
s1, measurement scene arrangement:
the measurement scene is arranged, the measurement scene comprises arrangement of a blank workpiece 1, a rotary tool 2, a measurement robot 3, a three-dimensional scanner 4 and a global positioning camera 5, and a mark point 21 (refer to fig. 2) is arranged on the rotary tool 2.
In this step, the blank workpiece 1 is a large composite panel formed by coating a glass fiber reinforced material on the surface of a complex curved mold and curing. Wherein, the height of the blank workpiece is more than or equal to 2m, and the blank workpiece belongs to a large-scale composite material blank workpiece. The blank workpiece material includes but is not limited to glass fiber composite material, ceramic, polycarbonate, polyolefin fiber weaving and other materials used in radar cover preparation schemes.
The rotary tool 2 consists of a rotary worktable and a positioning and clamping fixture, the rotary worktable is used for providing rotary motion, and the rotary worktable is matched with the measuring robot 3 to complete the measurement work of all areas to be processed. And a marking point 21 is arranged at the lower edge of the rotary table, and the marking point 21 is used as a corresponding point for registration splicing of multi-frame scanning data during scanning. By not arranging the mark points 21 on the surface of the blank workpiece 1 during measurement and arranging the mark points 21 on the die below the blank workpiece, the reconstruction accuracy of the blank workpiece is prevented from being influenced by arranging the mark points 21 on the surface of the blank workpiece.
The positioning and clamping fixture is used for fixing blank workpieces, and fixing different blank workpieces at specified positions according to mounting standards, so that the blank workpieces 1 are clamped in the rotary tool 2 in a hoisting mode. The space positioning method of the blank workpiece 1 comprises the following steps: the combined body of the blank workpiece 1 and the complex curved die is placed at the table top of the rotary workbench by using the crown block, the die position is adjusted by using the positioning block, the die is fixed on the rotary workbench by using the positioning clamping fixture, the different die clamping positions are different, and radial T-shaped grooves are reserved on the installation surfaces of the table top of the rotary workbench and the blank workpiece 1, so that the blank workpiece 1 is conveniently installed, and the table top can be adapted to the clamping of the blank workpieces 1 with different shapes and sizes. And (3) clamping the blank workpiece 1 in the T-shaped groove, positioning the blank workpiece through X, Y reference blocks in two directions to enable the rotation center of the blank workpiece 1 to coincide with that of the rotary worktable, and fixing the blank workpiece 1 on the table top of the rotary worktable by using T-shaped screws and a pressure plate to complete the positioning of the blank workpiece.
The measuring robot 3 is a six-axis robot, is arranged beside the rotary worktable and is used for clamping the three-dimensional scanner 4 to scan and collect blank workpieces according to a partition planning path, and a rotating shaft of the rotary worktable is used as a seventh axis of the measuring robot 3 to be matched with the measuring robot 3 for linkage. The rotary table is arranged in the mode, when scanning is conducted, the rotary table rotating shaft is used as a seventh shaft of the industrial robot to be linked with the robot, and automatic scanning of the surface of a large blank workpiece can be achieved.
The three-dimensional scanner 4 is a scanning instrument with a high light reflection point, is clamped at the execution tail end of the measuring robot 3 and is used for acquiring the space coordinate information of a blank workpiece by utilizing the laser triangulation distance measuring principle. The three-dimensional scanner 4 is marked with N high-reflection mark points, and N is more than or equal to 32, so that the global positioning camera 5 can acquire the relative spatial position of the scanner no matter what pose the scanner is in during scanning measurement.
The global positioning camera 5 is hung on one side of the rotary tool, the acquisition direction of the global positioning camera 5 faces the blank workpiece, and the global positioning camera is used for capturing the space coordinate information of the mark point 21, monitoring the mark point 21 on the rotary worktable and the high reflection point on the three-dimensional scanner 4, acquiring the space position relation between the three-dimensional scanner 4 and the blank workpiece in real time, and completing the splicing of multi-frame point clouds in the scanning process.
S2, planning a measurement path:
partitioning is carried out according to the blank workpiece design model curved surface, and measurement path planning is carried out on the partitioned surfaces in sequence according to the circumferential sequence, so that the full coverage of the measurement path of the blank workpiece surface is realized (refer to fig. 3).
In this step, the measurement method of the path plan includes: the curved surface measurement area needs to be divided when the measurement track planning is carried out, the sectorial measurement is adopted according to the characteristics of a specific blank workpiece, the blank workpiece is rotated after the current sector measurement is finished once, and the next sector measurement is carried out until the whole blank workpiece is finished once.
Due to the fact that the special-shaped composite material is large in size and complex in surface shape, a curved surface measuring area needs to be divided when measuring track planning is conducted, and the whole blank workpiece rotates for a certain angle after being measured for one time and is machined for the next time. The method can avoid point cloud data accumulation caused by the same splicing position of the cutter every time, and reduce the point cloud processing calculation amount.
S3, automatic measurement:
operating the rotary tool 2, and automatically scanning and measuring the area to be processed of the blank workpiece 1 by the three-dimensional scanner 4 to obtain three-dimensional point cloud data of the blank workpiece 1; starting a global positioning camera 5 to monitor a mark point 21 on a rotary tool 2 and a high reflection point on a three-dimensional scanner 4, acquiring a spatial position relation between the three-dimensional scanner 4 and a blank workpiece 1 in real time, and splicing acquired three-dimensional point cloud data according to the spatial position of the mark point 21 to generate an edge feature point;
in the step, in order to reduce the splicing calculation pressure of the measurement software, a bottom plane is arranged before scanning, so that only data points above the bottom plane are reserved when the measurement data are dynamically displayed in real time, then the global positioning camera 5 and the scanner system are started, and the control program of the rotary worktable and the measurement robot 3 is operated. The measuring robot 3 drives a three-dimensional scanner at the execution tail end to perform scanning measurement on the area to be processed by matching with the rotary table.
In the measuring process, two groups of cameras arranged on the three-dimensional scanner 4 are used for respectively obtaining laser linear arrays projected onto a scanning sample piece, the linear arrays deform along with the shape of a measured object, and linear three-dimensional point cloud data collection projected by the laser linear arrays can be obtained through calculation;
meanwhile, the global positioning camera 5 tracks the high reflection point on the three-dimensional scanner 4 in real time to acquire relative information of the spatial position of the scanner in real time, the relative position of a blank workpiece can deviate after the rotary worktable rotates, and the automatic alignment and splicing functions of two groups of scanning components can be realized through the mark points 21.
S4, point cloud pretreatment:
the error point cloud measured in step S3 is removed by a statistical filtering method, and the point cloud data is reduced based on a non-uniform simplified algorithm (refer to fig. 4).
In this step, the method for point cloud reduction includes:
a. denoising the point cloud, namely removing noise points generated in the scanning process by adopting a statistical filtering method to ensure the reconstruction quality of a subsequent model;
b. extracting characteristic points, and expressing the average distance d from the point cloud in the local neighborhood range to the tangent plane as
In the formula, p is a characteristic point cloud; k is the number of point clouds in the local neighborhood range of the p point; p is a radical ofjPoint cloud in the local neighborhood range of the p points; j is any value from 1 to k; n ispIs the average normal vector at p points;
if d is larger than the threshold value, the point is considered as a characteristic point;
c. determining the optimal region, determining the lower limit r of the search radius of the regionminAnd upper limit rmaxAnd varying the step length r△Setting the search radius R as R, and sequentially setting R as Rmin+r△Respectively calculating corresponding dimension characteristics and entropy function values of the point clouds in the local neighborhood according to the search radius until R is more than RmaxFinally, selecting the minimum entropy function value through comparison, and taking the neighborhood range obtained by the result as the optimal neighborhood;
d. determining weight, and calculating the weight w of the local optimal neighborhood of the non-feature point according to the local neighborhood densityiThe calculation formula is
In the formula, piCharacteristic point cloud is obtained; k is piThe number of point clouds within a local neighborhood of a point; p is a radical of formulajPoint cloud in the local neighborhood range of the p points; j is any value from 1 to k;
e. and determining an optimal point, after the optimal neighborhood radius R is determined, setting x as the optimal point in the optimal neighborhood R, setting c as the central point of the selected non-characteristic local neighborhood range point cloud, calculating whether the optimal point is located in the optimal neighborhood range, namely whether the optimal point meets the condition | x-c | < R, and if the x is located in the optimal neighborhood range, replacing the point cloud in the whole neighborhood range by the optimal point x to obtain simplified point cloud data.
S5, curved surface reconstruction:
and performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data, and reconstructing a three-dimensional model of the blank workpiece.
In this step, the step of three-dimensional reconstruction of the model includes:
a. selecting a non-uniform rational B-spline curve based on the edge feature points and the three-dimensional coordinate data;
b. selecting a non-uniform rational B spline curve function, and performing curve surface fitting;
c. and generating a three-dimensional model of the blank by fitting the curve surface.
Therefore, according to the technical scheme, the automatic full-coverage measurement of the surface of the large-sized composite material blank can be realized by adopting the linkage mode of the rotary tool 2 and the measuring robot 3, the problem that the quality of the surface data of the large-sized blank workpiece obtained by the traditional manual measurement is unstable is solved, the global positioning camera 5 is adopted to capture the space coordinate information of the mark points in the measurement process, the scanner splices the acquired multi-frame point cloud data according to the space positions of the mark points 21 during scanning, the mark points 21 are prevented from being arranged on the surface of the blank workpiece, and the forming precision of the surface of the blank workpiece is ensured. During point cloud data processing, under the condition that the surface characteristic information of the blank is reserved through a non-uniform simplified algorithm, the point cloud data volume is simplified, and the subsequent point cloud data processing speed and the model reconstruction efficiency are improved.
Based on the three-dimensional reconstruction method for the airplane radome machining blank, the invention also provides a model establishing device of the method, which comprises the following steps:
the first processing unit is used for partitioning according to the design model curved surface of the blank workpiece, and sequentially planning the measurement path of the partitioned surface according to the circumferential sequence to realize the full coverage of the measurement path of the surface of the blank workpiece;
the second processing unit is used for controlling the operation of the rotary tool 2, controlling the three-dimensional scanner 4 to perform automatic scanning measurement on the area to be processed of the blank workpiece 1, starting the global positioning camera 5, acquiring the spatial position relation between the three-dimensional scanner 4 and the blank workpiece 1 in real time, splicing the acquired multi-frame point cloud data according to the spatial position of the mark points 21, and generating edge feature points;
the third processing unit is used for filtering and simplifying the point cloud data of the blank workpiece 1;
and the fourth processing unit is used for performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data and reconstructing a three-dimensional model of the blank workpiece.
Based on the three-dimensional reconstruction method for the airplane radome machining blank, the invention further provides a computer readable storage medium for the method, wherein a computer program is stored on the computer readable storage medium, and when the computer program is executed by a processor, the steps of the three-dimensional reconstruction method for the airplane radome machining blank are realized.
Based on the three-dimensional reconstruction method for the airplane radome machining blank, the invention also provides computer equipment of the method, which comprises a memory, a processor and a computer program which is stored on the memory and can run on the processor, wherein the processor realizes the steps of the three-dimensional reconstruction method for the airplane radome machining blank when executing the computer program.
The present invention is described in terms of flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments. It will be understood that each flow and/or block of the flow diagrams and/or block diagrams, and combinations of flows and/or blocks in the flow diagrams and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.
These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.
Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. A three-dimensional reconstruction method for a blank part processed by an aircraft radome comprises the following steps:
s1, arranging a measurement scene, including arrangement of a blank workpiece, a rotary tool, a measurement robot, a three-dimensional scanner and a global positioning camera, wherein mark points are arranged on the rotary tool, and high-reflection points are marked on the three-dimensional scanner;
s2, partitioning according to the model curved surface of the blank workpiece design, and sequentially planning the measurement path of the partitioned surface according to the circumferential sequence to realize the full coverage of the measurement path of the surface of the blank workpiece;
s3, operating a rotary tool, and automatically scanning and measuring the area to be processed of the blank workpiece by a three-dimensional scanner to obtain three-dimensional point cloud data of the blank workpiece; starting a mark point on a global positioning camera monitoring rotary tool and a high-reflection point on a three-dimensional scanner, acquiring a spatial position relation between the three-dimensional scanner and a blank workpiece in real time, splicing acquired three-dimensional point cloud data according to the spatial position of the mark point, and generating an edge feature point;
s4, filtering and simplifying the point cloud data of the blank workpiece;
and S5, performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data, and reconstructing a three-dimensional model of the blank workpiece.
2. The three-dimensional reconstruction method for the aircraft radome processing blank member of claim 1, wherein in step S1:
the blank workpiece is a large composite panel formed by coating a glass fiber reinforced material on the surface of a complex curved mold and curing;
the rotary tool is composed of a rotary worktable and a positioning and clamping fixture, the rotary worktable is used for providing rotary motion and is matched with a measuring robot to finish the measurement work of all areas to be processed, a mark point is arranged on the lower edge of the rotary worktable and is used as a corresponding point for registration splicing of multi-frame scanning data during scanning;
the positioning and clamping fixture is used for fixing blank workpieces, fixing different blank workpieces at specified positions according to mounting standards, and clamping the blank workpieces on the rotary fixture in a hoisting mode;
the measuring robot is a six-axis robot, is arranged beside the rotary worktable and is used for clamping the three-dimensional scanner to scan and collect the blank workpiece according to the partition planning path, and takes a rotating shaft of the rotary worktable as a seventh axis of the measuring robot so as to be matched with the measuring robot for linkage;
the three-dimensional scanner is a scanning instrument with high light reflection points, is clamped at the execution tail end of the measuring robot and is used for acquiring space coordinate information of a blank workpiece by utilizing a laser triangulation distance measuring principle, and N high light reflection mark points are marked on the three-dimensional scanner, wherein N is more than or equal to 32;
the global positioning camera is hung on one side of the rotary tool, the acquisition direction of the global positioning camera faces to the blank workpiece, and the global positioning camera is used for capturing the space coordinate information of the mark points, monitoring the mark points on the rotary worktable and the high reflection points on the three-dimensional scanner, acquiring the space position relation between the three-dimensional scanner and the blank workpiece in real time, and completing the splicing of multi-frame point clouds in the scanning process.
3. The three-dimensional reconstruction method for the aircraft radome machining blank according to the claim 2, wherein in the step S1, the spatial positioning method for the blank workpiece comprises the following steps: the method comprises the steps of placing a combination of a blank workpiece and a complex curved die on the table top of a rotary table by using a crown block, adjusting the position of the die by using a positioning block, fixing the die on the rotary table by using a positioning clamping clamp, enabling different die clamping positions to be different, reserving radial T-shaped grooves on the table top of the rotary table and the mounting surface of the blank workpiece, clamping the blank workpiece in the T-shaped grooves, positioning the blank workpiece by using X, Y reference blocks in two directions, enabling the rotation center of the blank workpiece to coincide with that of the rotary table, and fixing the blank workpiece on the table top of the rotary table by using T-shaped screws and pressing plates to complete the positioning of the blank workpiece.
4. The three-dimensional reconstruction method for the aircraft radome processing blank according to the claim 1, wherein in the step S2, the measurement method for the path planning comprises: the curved surface measurement area needs to be divided when the measurement track planning is carried out, the sectorial measurement is adopted according to the characteristics of a specific blank workpiece, the blank workpiece is rotated after the current sector measurement is finished once, and the next sector measurement is carried out until the whole blank workpiece is finished once.
5. The three-dimensional reconstruction method for the aircraft radome processing blank member of claim 1, wherein in the step S3, the scanning measurement method comprises the following steps:
setting a bottom plane before scanning, so that only data points above the bottom plane are reserved when measurement data are dynamically displayed in real time, respectively obtaining laser linear arrays projected onto a scanning sample piece through two groups of cameras arranged on a three-dimensional scanner, wherein the linear arrays deform along with the shape of a measured object, and acquiring linear three-dimensional point cloud data projected by the laser linear arrays through calculation;
meanwhile, the global positioning camera tracks high-reflection points on the three-dimensional scanner in real time, relative information of the spatial position of the scanner is acquired in real time, the relative position of a blank workpiece can deviate after the rotary worktable rotates, and the automatic alignment and splicing functions of the two scanning parts can be realized through the mark points.
6. The three-dimensional reconstruction method for the aircraft radome processing blank piece according to the claim 1, wherein the step S4 is realized by the following steps:
a. denoising the point cloud, namely removing noise points generated in the scanning process by adopting a statistical filtering method to ensure the reconstruction quality of a subsequent model;
b. extracting characteristic points, and expressing the average distance d from the point cloud in the local neighborhood range to the tangent plane as
In the formula, p is a characteristic point cloud; k is the number of point clouds in the local neighborhood range of the p points; p is a radical ofjPoint cloud in the local neighborhood range of the p points; j is any value from 1 to k; n ispIs the average normal vector at p points;
if d is larger than the threshold value, the point is considered as a characteristic point;
c. determining the optimal region, determining the lower limit r of the search radius of the regionminAnd upper limit rmaxAnd varying the step length r△Setting the search radius R as R, and sequentially setting R as Rmin+r△Respectively calculating corresponding dimension characteristics and entropy function values of the point clouds in the local neighborhood according to the search radius until R is more than RmaxFinally, selecting the minimum entropy function value through comparison, and taking the neighborhood range obtained by the result as the optimal neighborhood;
d. determining weight, and calculating the weight w of the local optimal neighborhood of the non-feature point according to the local neighborhood densityiThe calculation formula is
In the formula, piCharacteristic point cloud is obtained; k is piThe number of point clouds within a local neighborhood of a point; p is a radical ofjPoint cloud in the local neighborhood range of the p points; j is any value from 1 to k;
e. and determining an optimal point, after the optimal neighborhood radius R is determined, setting x as the optimal point in the optimal neighborhood R, setting c as the central point of the selected non-characteristic local neighborhood range point cloud, calculating whether the optimal point is located in the optimal neighborhood range, namely whether the optimal point meets the condition | x-c | < R, and if the x is located in the optimal neighborhood range, replacing the point cloud in the whole neighborhood range by the optimal point x to obtain simplified point cloud data.
7. The aircraft radome processing blank three-dimensional reconstruction method of claim 1, wherein in the step S5, the step of three-dimensional reconstruction of the model comprises the following steps:
a. selecting a non-uniform rational B-spline curve based on the edge feature points and the three-dimensional coordinate data;
b. selecting a non-uniform rational B spline curve function, and performing curve surface fitting;
c. and generating a three-dimensional model of the blank by fitting the curve surface.
8. A model building device of a three-dimensional reconstruction method of a blank for machining an aircraft radome comprises the following steps:
the first processing unit is used for partitioning according to a blank workpiece design model curved surface, and sequentially planning measurement paths on the partitioned surfaces according to a circumferential sequence to complete full coverage of the measurement paths on the surface of the blank workpiece;
the second processing unit is used for controlling the operation of the rotary tool, controlling the three-dimensional scanner to automatically scan and measure the area to be processed of the blank workpiece, starting the global positioning camera, acquiring the spatial position relation between the three-dimensional scanner and the blank workpiece in real time, splicing the acquired multi-frame point cloud data according to the spatial position of the mark points, and generating edge feature points;
the third processing unit is used for filtering and simplifying the point cloud data of the blank workpiece;
and the fourth processing unit is used for performing curve surface fitting based on the edge feature points and the three-dimensional point cloud data and reconstructing a three-dimensional model of the blank workpiece.
9. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out the steps of the method for three-dimensional reconstruction of an aircraft radome processing blank according to any one of claims 1-7.
10. A computer arrangement comprising a memory, a processor and a computer program stored on the memory and executable on the processor, wherein the processor when executing the computer program performs the steps of the method for three-dimensional reconstruction of an aircraft radome processing blank according to any one of claims 1-7.
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