CN114295048A - Spacecraft structure digital detection method based on laser scanner - Google Patents
Spacecraft structure digital detection method based on laser scanner Download PDFInfo
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Abstract
The invention relates to the technical field of spacecraft structure detection, and discloses a laser scanner-based spacecraft structure digital detection method, which comprises the following specific steps: the method comprises the following steps of structure digital-analog preprocessing, structure preprocessing, fast mark plate calibration, mark point scanning, laser surface patch scanning, data gridding, feature construction, alignment and analysis, wherein the data gridding is to encapsulate point cloud data to enable the point cloud data to exist in a surface form, the gridded data can be stored in a stl or ply format file format, the file can be used for 3D printing, reverse engineering and other operations, and selectable items in the gridding process have the functions of mark point filling, edge optimization, high-precision mode, small hole filling, maximum edge number, thinning strength, smooth grade, optimized grade and the like. The spacecraft structure digital detection method based on the laser scanner solves the problem that the special-shaped curved surface of the spacecraft structure is not easy to detect, improves the reliability and accuracy of spacecraft structure detection, and also improves the efficiency of spacecraft structure detection.
Description
Technical Field
The invention relates to the technical field of spacecraft structure detection, in particular to a spacecraft structure digital detection method based on a laser scanner.
Background
The spacecraft structure part is mainly an aluminum alloy thin plate structure or a special-shaped curved surface structure, the structural shape is irregular, threaded holes and lightening holes are more, the requirements on form and position tolerance are high, and the spacecraft structure is a main body bearing component of a spacecraft and influences the mounting precision of a platform and load equipment, so that the spacecraft structure is very important for quality control and detection of the spacecraft structure.
At present, the detection of the spacecraft structure adopts tools such as a caliper rule, an angle rule, a central rule, a depth gauge, a feeler gauge and the like to measure, the feeler gauge is attached to the structure in the gap measurement, and the size of the gap of the structure is judged; detecting a threaded hole or a through hole of the structure by adopting a depth gauge, measuring the structural flatness by adopting a horizontal table workbench, and judging whether the flatness meets the requirement; the traditional detection method is only suitable for structures with regular shapes and measurement spaces, and special detection tools and tools are needed, so that the detection of the structure of the special-shaped curved surface is difficult to realize; meanwhile, the manual detection method is dependent on more influence of human factors, the result consistency is poor, and the measurement result is unstable. With the increasing complexity of the structure shape of the spacecraft and the increasing appearance of various special-shaped curved surfaces, hyperboloids or multi-curved surfaces, the traditional detection method can not meet the requirement of spacecraft structure detection.
Disclosure of Invention
The invention aims to provide a spacecraft structure digital detection method based on a laser scanner, so as to solve the defects in the background technology.
The technical problem solved by the invention is realized by adopting the following technical scheme:
the spacecraft structure digital detection method based on the laser scanner comprises the following specific steps:
d1, the structural digital-analog preprocessing is to process the spacecraft structural model by using Proe 5.0 software to generate detection characteristics, and set characteristic measurement points for representing measurement parameters on the extracted detection characteristics;
d2, the structure pretreatment comprises spraying a contrast enhancer on the surface of the structure so that the structure can diffuse and reflect laser irradiated on the surface of the structure;
d3, calibrating the fast target, and when the detection is started or temperature change occurs or the scanning data quality is poor, calibrating the camera by using the fast target;
d4, scanning the mark points, after calibration is completed, collecting and scanning the mark points on the surface of the structure, establishing the coordinates and the location of the structure, establishing the position relation of each surface of the structure, and collecting the located mark points, so that the subsequent scanning of laser patches (points) is easier to perform, and the transition from surface to surface is more convenient;
d5, before scanning the laser patch, setting scanning parameters (or default values of using parameters) such as scanning resolution, exposure parameter setting, scanning control, advanced parameter setting, professional parameter setting and the like, wherein the process comprises four parts of data protection, automatic exposure, fine scanning and background marking points;
d6, meshing the data, packaging the point cloud data to enable the point cloud data to exist in a surface form, storing the meshed data into a stl or ply format file format, enabling the file to be used for operations such as 3D printing and reverse engineering, and selecting items in the meshing process to have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling holes, increasing the number of the edges, thinning strength, smoothing grade, optimizing grade and the like;
d7, the feature structure comprises attributes of features such as circles, rectangular grooves, points and straight lines, application modes such as feature structure, feature storage and feature extraction, and application modes such as an intersection mode, a fitting mode, a point selection mode, a CAD mode, an object mode and a projection mode; the characteristic optimization comprises attributes, characteristic structures, characteristic storage, characteristic extraction and the like of characteristics such as a solution circle, a rectangular groove, a point, a straight line and the like;
d8, aligning the two groups of different data through rigid transformation to unify the two groups of different data in the same coordinate system, wherein the aligning comprises the processes of best fit aligning, aligning to the global state, feature aligning, N point aligning, PLP aligning and RPS aligning;
d9, the analysis mainly includes measurement, angle, section, 3D comparison, GD & T, etc.
Preferably, in the step D2, the structure pretreatment includes structure material or surface color treatment, and the transparent material is penetrated by laser, so that the camera cannot accurately capture the position of the glass, and therefore cannot scan the glass; the laser line penetrates into the object when projected to the surface of the object, so that the position of the laser line captured by the camera is not the surface profile of the object, and the accuracy of scanning data is influenced; the highly reflective material can generate mirror reflection on light, so that the camera cannot capture the reflected light at certain angles and cannot obtain scanning data under the irradiation conditions; other materials or colors which can affect the diffuse reflection effect of the laser; before scanning, a contrast enhancer needs to be sprayed on the surface of the structure, so that the structure can perform diffuse reflection on laser irradiated on the surface of the structure.
Preferably, in the step D3, the fast calibration board calibration includes fast calibration of the device by using the fast calibration board after the scanner is connected; placing the calibration plate on a stable plane, and enabling the scanner to be opposite to the calibration plate at a distance of about 400 mm; controlling the angle of the scanner, and adjusting the distance between the scanner and the calibration plate to enable the shadow circles on the left side to coincide; under the condition of ensuring that the shadow circles on the left side are basically overlapped, the scanner is horizontally moved without changing the angle, so that the trapezoidal shadows on the right side are overlapped, and then the distance is adjusted to enable the sizes of the trapezoidal shadows to be consistent; gradually lifting the equipment, calibrating the vertical direction, then calibrating the right side by 45 degrees, tilting the scanner by about 45 degrees to the right, and keeping the laser beam between the marking points of the fourth line and the fifth line to ensure that the shadows are overlapped; after the calibration of the right side is finished, the calibration of 45 degrees of the left side is carried out, the scanner is inclined by about 45 degrees to the left, and the laser beam is kept between the marking points of the fourth line and the fifth line, so that the shadows are overlapped; after the left side calibration is finished, performing upper side 45-degree calibration, tilting the scanner upwards by about 45 degrees, and keeping the laser beam between the fourth row marking point and the fifth row marking point to enable the shadow to coincide; after the upper side calibration is finished, the lower side 45-degree calibration is carried out, the scanner is inclined downwards by about 45 degrees, and the laser beam is kept between the fourth line marking point and the fifth line marking point, so that the shadows are overlapped; and finishing calibration.
Preferably, in the step D4, pre-scanning the mark points includes collecting and scanning the mark points on the surface of the structure, and establishing coordinates and positioning of the structure; and performing identification reading on the mark points again by using a plurality of angles, or selecting the intelligent mark points for scanning.
Preferably, in step D5, the laser patch is scanned, including before scanning the laser patch (point), scan parameters (or default values of the parameters used) need to be set, such as scan resolution, exposure parameter setting, scan control, advanced parameter setting, professional parameter setting, and the like; the angle of the scanner and the distance between the scanner and the structure stably move the scanner, and the blank position data is completely acquired by using laser; after the scanning is completed, clicking to stop, starting to process the scanned data by software, waiting for the completion of the data processing, and finishing the scanning of the laser surface patch (point); the scanning software comprises data protection, automatic exposure, fine scanning, background mark points and the like.
Preferably, in the step D6, the gridding includes encapsulating the point cloud data to make it exist in a planar form, the gridded data may be stored in a stl or ply format file format, and the file may be used for operations such as 3D printing and reverse engineering; the optional items in the gridding process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling small holes, realizing the maximum edge number, thinning strength, smoothing level, optimizing level and the like.
Preferably, in step D7, the features include attributes of features such as circles, rectangular grooves, points, and straight lines, feature structures, feature storage, feature extraction, and other applications, and the feature structures include intersection methods, fitting methods, point selection methods, CAD methods, object methods, projection methods, and other methods; feature extraction refers to the automatic fitting of features on reference data to near positions on test data under the same coordinate system to create the same type of feature operation.
Preferably, in the step D9, the analysis includes application modes such as measurement, angle, section, 3D comparison, GD & T, and the like, and when the measurement includes measuring the distance between the features, the second feature is used as a main feature, the circle degenerates as a circle center, the circular groove, the elliptical groove, and the rectangular groove degenerates as a center point, the sphere degenerates as a sphere center, the cylinder and the cone degenerates as an axis, and the distance is finally converted into one of three modes, i.e., a point-to-point distance, a point-to-line distance, and a point-to-plane distance; when the angle comprises the angle between the measurement characteristics (plane and plane), the cylinder and the cone are degenerated into the axis, and the corresponding plane is taken as the circle, the circular groove, the elliptical groove and the rectangular groove; when the cross section comprises the cross sections of point cloud, grid and CAD data, the digital-to-analog data and the grid data are intercepted on the plane to obtain a cross section line, and the scanning data are intercepted on the plane to obtain the point cloud; 3D comparing and representing the deviation graph between the Test data and the Reference data by generating different colors, wherein the deviation graph is defined as a chromatogram (color difference graph), the deviation exists in positive and negative, the color value in the chromatogram evolves from blue to green to red, the blue represents that the measured curved surface is lower than the Reference curved surface, if the measured data is displayed in red, the data is positioned on the Reference surface, and the deviation is calculated by adopting the principle of the closest point; creating annotations partial bias annotations may be viewed; after creating the annotation, clicking the 'creation report' to store in a pdf format file; GD & T, form and position tolerances, including shape and position tolerances;
the shape tolerance comprises the variation amount allowed by the shape of a single actual element, such as roundness, straightness, flatness, cylindricity, sphericity and the like;
the position tolerance comprises the deviation of the associated actual measured element to an ideal measured element with a determined direction, and a position tolerance band is an allowable change area of the associated actual measured element and has parallelism, perpendicularity, coaxiality and the like;
the GD & T detection is established on the basis of the fitting features, the shape tolerance is only related to the fitting features and the fitted point cloud data, the position tolerance needs to be provided with the reference features, and the reference features can be constructed in any construction mode.
Has the advantages that: the digital detection method of the laser scanner can improve the reliability and detection efficiency of measurement, and the digital measurement data can be used for acceptance and process analysis of products and provide data support for spacecraft platforms and load equipment; meanwhile, geometric tolerances such as theoretical external surface, outline, threaded hole position, instrument and equipment mounting interface size and the like of the structure can be visually expressed under a system coordinate system, and the mounting precision of the spacecraft structural system is ensured.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and other drawings can be obtained by those skilled in the art without creative efforts.
FIG. 1 is a schematic diagram of a laser scanner based spacecraft structure digital detection method provided by the invention;
FIG. 2 is a schematic view of a structural scanning system of the laser scanner-based spacecraft structure digital detection method provided by the invention;
fig. 3 is a characteristic structure schematic diagram of the spacecraft structure digital detection method based on the laser scanner provided by the invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the embodiments of the present invention, it should be noted that, unless explicitly stated or limited otherwise, the terms "mounted," "connected," and "connected" are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally connected; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meanings of the above terms in the present invention can be understood in specific cases to those skilled in the art.
In order to make the technical means, the creation characteristics, the achievement purposes and the effects of the invention easy to understand, the invention is further explained below by combining the specific drawings.
Example 1:
referring to fig. 1 and fig. 3, the present invention provides a technical solution: the spacecraft structure digital detection method based on the laser scanner comprises the following specific steps:
d1, preprocessing a structure digital-analog, namely processing a spacecraft structure model by using Proe 5.0 software to generate detection characteristics, and setting characteristic measurement points for representing measurement parameters on the extracted detection characteristics;
d2, pretreating the structure, which comprises spraying a contrast enhancer on the surface of the structure to make the structure diffuse-reflect the laser irradiated on the surface;
d3, calibrating the fast target, and when the temperature change or the scanning data quality is not good before the detection is started, the fast target is needed to be used for camera calibration;
d4, data meshing, namely packaging the point cloud data to enable the point cloud data to exist in a surface form, wherein the meshed data can be stored in a stl or ply format file format, the file can be used for 3D printing, reverse engineering and other operations, and selectable items in the meshing process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling holes, increasing the number of the edges, thinning strength, smoothing grade, optimizing grade and the like;
d5, the feature structure comprises attributes of features such as circles, rectangular grooves, points and straight lines, application modes such as feature structure, feature storage and feature extraction, and application modes such as an intersection mode, a fitting mode, a point selection mode, a CAD mode, an object mode and a projection mode; the characteristic optimization comprises attributes, characteristic structures, characteristic storage, characteristic extraction and the like of characteristics such as a solution circle, a rectangular groove, a point, a straight line and the like;
d6, aligning, namely unifying two groups of different data into the same coordinate system through rigid transformation, wherein the process comprises best fit aligning, aligning to the global state, feature aligning, N point aligning, PLP aligning and RPS aligning;
d7, analysis mainly including measurement, angle, section, 3D comparison, GD & T, etc.
In step D2, the structure pretreatment includes structure material or surface color treatment, and the transparent material is penetrated by laser, so that the camera cannot accurately capture the position of the glass, and therefore cannot scan the glass; the laser line penetrates into the object when projected to the surface of the object, so that the position of the laser line captured by the camera is not the surface profile of the object, and the accuracy of scanning data is influenced; the highly reflective material can generate mirror reflection on light, so that the camera cannot capture the reflected light at certain angles and cannot obtain scanning data under the irradiation conditions; other materials or colors which can affect the diffuse reflection effect of the laser; before scanning, a contrast enhancer needs to be sprayed on the surface of the structure, so that the structure can perform diffuse reflection on laser irradiated on the surface of the structure.
In step D3, the fast calibration board calibration includes that after the scanner is connected, the fast calibration board is needed to be used for fast calibrating the equipment; placing the calibration plate on a stable plane, and enabling the scanner to be opposite to the calibration plate at a distance of about 400 mm; controlling the angle of the scanner, and adjusting the distance between the scanner and the calibration plate to enable the shadow circles on the left side to coincide; under the condition of ensuring that the shadow circles on the left side are basically overlapped, the scanner is horizontally moved without changing the angle, so that the trapezoidal shadows on the right side are overlapped, and then the distance is adjusted to enable the sizes of the trapezoidal shadows to be consistent; gradually lifting the equipment, calibrating the vertical direction, then calibrating the right side by 45 degrees, tilting the scanner by about 45 degrees to the right, and keeping the laser beam between the marking points of the fourth line and the fifth line to ensure that the shadows are overlapped; after the right side calibration is finished, performing left side 45-degree calibration, inclining the scanner to the left by about 45 degrees, and keeping the laser beam between the marking points of the fourth line and the fifth line to enable the shadow to coincide; after the left side calibration is finished, performing upper side 45-degree calibration, tilting the scanner upwards by about 45 degrees, and keeping the laser beam between the fourth row marking point and the fifth row marking point to enable the shadow to coincide; after the upper side calibration is finished, the lower side 45-degree calibration is carried out, the scanner is inclined downwards by about 45 degrees, and the laser beam is kept between the fourth line marking point and the fifth line marking point, so that the shadows are overlapped; and finishing calibration.
Step D4, gridding, which includes packaging the point cloud data to make it exist in a surface form, the gridded data can be stored in stl or ply format file format, and the file can be used for 3D printing, reverse engineering and other operations; the optional items in the gridding process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling small holes, realizing the maximum edge number, thinning strength, smoothing level, optimizing level and the like.
In step D5, the features include attributes of the features such as circles, rectangular grooves, points, and straight lines, feature structures, feature storage, feature extraction, and other applications, and the feature structures include intersection, fitting, point selection, CAD, object, and projection; feature extraction refers to the automatic fitting of features on reference data to near positions on test data under the same coordinate system to create the same type of feature operation.
In the step D6, analyzing the application modes including measurement, angle, section, 3D comparison, GD & T and the like, wherein when the measurement comprises the distance between the measurement features, the second feature is taken as a main feature, the circle is degenerated as the circle center, the circular groove, the elliptical groove and the rectangular groove are degenerated as the central point, the sphere is degenerated as the sphere center, the cylinder and the cone are degenerated as the axis, and the distance is finally converted into one of three modes of point-to-point distance, point-to-line distance and point-to-surface distance; when the angle comprises the angle between the measurement characteristics (plane and plane), the cylinder and the cone are degenerated into the axis, and the corresponding plane is taken as the circle, the circular groove, the elliptical groove and the rectangular groove; when the cross section comprises the cross sections of point cloud, grid and CAD data, the digital-to-analog data and the grid data are intercepted on the plane to obtain a cross section line, and the scanning data are intercepted on the plane to obtain the point cloud; 3D comparing and representing the deviation graph between the Test data and the Reference data by generating different colors, wherein the deviation graph is defined as a chromatogram (color difference graph), the deviation exists in positive and negative, the color value in the chromatogram evolves from blue to green to red, the blue represents that the measured curved surface is lower than the Reference curved surface, if the measured data is displayed in red, the data is positioned on the Reference surface, and the deviation is calculated by adopting the principle of the closest point; creating annotations partial bias annotations may be viewed; after creating the annotation, clicking the 'creation report' to store in a pdf format file; GD & T, form and position tolerances, including shape and position tolerances;
the shape tolerance comprises the variation allowed by the shape of a single actual element, such as roundness, straightness, flatness, cylindricity, sphericity and the like;
the position tolerance comprises the deviation of the related actual measured element to an ideal measured element with a determined direction, and a position tolerance band is an allowable change area of the related actual measured element and has parallelism, perpendicularity, coaxiality and the like;
the GD & T detection is based on the fitting characteristic, the shape tolerance is only related to the fitting characteristic and the fitting point cloud data, the position tolerance needs to be provided with a reference characteristic, the reference characteristic can be constructed in any construction mode,
in the embodiment, the point cloud data is packaged through data gridding, so that the point cloud data is in a surface form, the gridded data can be stored in a stl or ply format file format, the file can be used for operations such as 3D printing and reverse engineering, and the like, and the functions of mark point filling, edge optimization, a high-precision mode, small hole filling, maximum edge number, thinning strength, a smooth grade, an optimized grade and the like can be selected in the gridding process.
Example 2:
referring to fig. 1-3, the present invention provides a technical solution: the spacecraft structure digital detection method based on the laser scanner comprises the following specific steps:
d1, preprocessing a structure digital-analog, namely processing a spacecraft structure model by using Proe 5.0 software to generate detection characteristics, and setting characteristic measurement points for representing measurement parameters on the extracted detection characteristics;
d2, pretreating the structure, which comprises spraying a contrast enhancer on the surface of the structure to make the structure diffuse-reflect the laser irradiated on the surface;
d3, calibrating the fast target, and when the temperature change or the scanning data quality is not good before the detection is started, the fast target is needed to be used for camera calibration;
d4, marking point scanning, after calibration is completed, collecting and scanning the marking points on the surface of the structure, establishing the coordinates and the location of the structure, establishing the position relation of each surface of the structure, and collecting the located marking points, so that the subsequent scanning of laser patches (points) is easier to perform, and the transition from surface to surface is more convenient;
d5, scanning the laser patch, setting scanning parameters (or default values of using parameters) before scanning the laser patch (point), such as scanning resolution, exposure parameter setting, scanning control, advanced parameter setting, professional parameter setting and the like, wherein the process comprises four parts of data protection, automatic exposure, fine scanning and background marking points;
d6, data meshing, namely packaging the point cloud data to enable the point cloud data to exist in a surface form, wherein the meshed data can be stored in a stl or ply format file format, the file can be used for 3D printing, reverse engineering and other operations, and selectable items in the meshing process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling holes, increasing the number of the edges, thinning strength, smoothing grade, optimizing grade and the like;
d7, the feature structure comprises attributes of features such as circles, rectangular grooves, points and straight lines, application modes such as feature structure, feature storage and feature extraction, and application modes such as an intersection mode, a fitting mode, a point selection mode, a CAD mode, an object mode and a projection mode; the characteristic optimization comprises attributes, characteristic structures, characteristic storage, characteristic extraction and the like of characteristics such as a solution circle, a rectangular groove, a point, a straight line and the like;
d8, aligning, namely unifying two groups of different data into the same coordinate system through rigid transformation, wherein the process comprises best fit aligning, aligning to the global state, feature aligning, N point aligning, PLP aligning and RPS aligning;
d9, analyzing, mainly including measurement, angle, section, 3D comparison, GD & T, etc.,
in step D2, the structure pretreatment includes structure material or surface color treatment, and the transparent material is penetrated by laser, so that the camera cannot accurately capture the position of the glass, and therefore cannot scan the glass; the laser line penetrates into the object when projected to the surface of the object, so that the position of the laser line captured by the camera is not the surface profile of the object, and the accuracy of scanning data is influenced; the highly reflective material can generate mirror reflection on light, so that the camera cannot capture the reflected light at certain angles and cannot obtain scanning data under the irradiation conditions; other materials or colors which can affect the diffuse reflection effect of the laser; before scanning, a contrast enhancer needs to be sprayed on the surface of the structure, so that the structure can perform diffuse reflection on laser irradiated on the surface of the structure.
In step D3, the fast calibration board calibration includes that after the scanner is connected, the fast calibration board is needed to be used for fast calibrating the equipment; placing the calibration plate on a stable plane, and enabling the scanner to be opposite to the calibration plate at a distance of about 400 mm; controlling the angle of the scanner, and adjusting the distance between the scanner and the calibration plate to enable the shadow circles on the left side to coincide; under the condition of ensuring that the shadow circles on the left side are basically overlapped, the scanner is horizontally moved without changing the angle, so that the trapezoidal shadows on the right side are overlapped, and then the distance is adjusted to enable the sizes of the trapezoidal shadows to be consistent; gradually lifting the equipment, calibrating the vertical direction, then calibrating the right side by 45 degrees, tilting the scanner by about 45 degrees to the right, and keeping the laser beam between the marking points of the fourth line and the fifth line to ensure that the shadows are overlapped; after the right side calibration is finished, performing left side 45-degree calibration, inclining the scanner to the left by about 45 degrees, and keeping the laser beam between the marking points of the fourth line and the fifth line to enable the shadow to coincide; after the left side calibration is finished, performing upper side 45-degree calibration, tilting the scanner upwards by about 45 degrees, and keeping the laser beam between the fourth row marking point and the fifth row marking point to enable the shadow to coincide; after the upper side calibration is finished, the lower side 45-degree calibration is carried out, the scanner is inclined downwards by about 45 degrees, and the laser beam is kept between the fourth line marking point and the fifth line marking point, so that the shadows are overlapped; and finishing calibration.
In step D4, pre-scanning the mark points comprises collecting and scanning the mark points on the surface of the structure, establishing the coordinates and positioning of the structure; and performing identification reading on the mark points again by using a plurality of angles, or selecting the intelligent mark points for scanning.
In step D5, scanning the laser patch, including setting scanning parameters (or default values of the parameters to be used) before scanning the laser patch (point), such as scanning resolution, exposure parameter setting, scanning control, advanced parameter setting, professional parameter setting, and the like; the angle of the scanner and the distance between the scanner and the structure stably move the scanner, and the blank position data is completely acquired by using laser; after the scanning is completed, clicking to stop, starting to process the scanned data by software, waiting for the completion of the data processing, and finishing the scanning of the laser surface patch (point); the scanning software comprises data protection, automatic exposure, fine scanning, background mark points and the like.
Step D6, gridding, which includes packaging the point cloud data to make it exist in a surface form, the gridded data can be stored in stl or ply format file format, and the file can be used for 3D printing, reverse engineering and other operations; the optional items in the gridding process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling small holes, realizing the maximum edge number, thinning strength, smoothing level, optimizing level and the like.
In step D7, the features include attributes of the features such as circles, rectangular grooves, points, and straight lines, feature structures, feature storage, feature extraction, and other applications, and the feature structures include intersection, fitting, point selection, CAD, object, and projection; feature extraction refers to the automatic fitting of features on reference data to near positions on test data under the same coordinate system to create the same type of feature operation.
In the step D9, analyzing the application modes including measurement, angle, section, 3D comparison, GD & T and the like, wherein when the measurement comprises the distance between the measurement features, the second feature is taken as a main feature, the circle is degenerated as the circle center, the circular groove, the elliptical groove and the rectangular groove are degenerated as the central point, the sphere is degenerated as the sphere center, the cylinder and the cone are degenerated as the axis, and the distance is finally converted into one of three modes of point-to-point distance, point-to-line distance and point-to-surface distance; when the angle comprises the angle between the measurement characteristics (plane and plane), the cylinder and the cone are degenerated into the axis, and the corresponding plane is taken as the circle, the circular groove, the elliptical groove and the rectangular groove; when the cross section comprises the cross sections of point cloud, grid and CAD data, the digital-to-analog data and the grid data are intercepted on the plane to obtain a cross section line, and the scanning data are intercepted on the plane to obtain the point cloud; 3D comparing and representing the deviation graph between the Test data and the Reference data by generating different colors, wherein the deviation graph is defined as a chromatogram (color difference graph), the deviation exists in positive and negative, the color value in the chromatogram evolves from blue to green to red, the blue represents that the measured curved surface is lower than the Reference curved surface, if the measured data is displayed in red, the data is positioned on the Reference surface, and the deviation is calculated by adopting the principle of the closest point; creating annotations partial bias annotations may be viewed; after creating the annotation, clicking the 'creation report' to store in a pdf format file; GD & T, form and position tolerances, including shape and position tolerances;
the shape tolerance comprises the variation allowed by the shape of a single actual element, such as roundness, straightness, flatness, cylindricity, sphericity and the like;
the position tolerance comprises the deviation of the related actual measured element to an ideal measured element with a determined direction, and a position tolerance band is an allowable change area of the related actual measured element and has parallelism, perpendicularity, coaxiality and the like;
the GD & T detection is established on the basis of the fitting features, the shape tolerance is only related to the fitting features and the fitting point cloud data, the position tolerance needs to be provided with the reference features, and the reference features can be constructed in any construction mode.
The digital detection method of the laser scanner adopted in the embodiment can improve the reliability and detection efficiency of measurement, and the digital measurement data can also be used for acceptance and process analysis of products and provide data support for spacecraft platforms and load equipment; meanwhile, geometric tolerances such as theoretical external surface, outline, threaded hole position, instrument and equipment mounting interface size and the like of the structure can be visually expressed under a system coordinate system, the mounting precision of a spacecraft structure system is ensured, the problem that the special-shaped curved surface of the spacecraft structure is difficult to detect is solved, the reliability and accuracy of spacecraft structure detection are improved, and the efficiency of spacecraft structure detection is also improved.
The above examples only express the specific embodiments of the present invention, and the description thereof is more specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention.
Claims (8)
1. The spacecraft structure digital detection method based on the laser scanner is characterized by comprising the following specific steps:
d1, the structural digital-analog preprocessing is to process the spacecraft structural model by using Proe 5.0 software to generate detection characteristics, and set characteristic measurement points for representing measurement parameters on the extracted detection characteristics;
d2, the structure pretreatment comprises spraying a contrast enhancer on the surface of the structure so that the structure can diffuse and reflect laser irradiated on the surface of the structure;
d3, calibrating the fast target, and when the detection is started or temperature change occurs or the scanning data quality is poor, calibrating the camera by using the fast target;
d4, scanning the mark points, after calibration is completed, collecting and scanning the mark points on the surface of the structure, establishing the coordinates and the location of the structure, establishing the position relation of each surface of the structure, and collecting the located mark points, so that the subsequent scanning of laser patches (points) is easier to perform, and the transition from surface to surface is more convenient;
d5, before scanning the laser patch, setting scanning parameters (or default values of using parameters) such as scanning resolution, exposure parameter setting, scanning control, advanced parameter setting, professional parameter setting and the like, wherein the process comprises four parts of data protection, automatic exposure, fine scanning and background marking points;
d6, meshing the data, packaging the point cloud data to enable the point cloud data to exist in a surface form, storing the meshed data into a stl or ply format file format, enabling the file to be used for operations such as 3D printing and reverse engineering, and selecting items in the meshing process to have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling holes, increasing the number of the edges, thinning strength, smoothing grade, optimizing grade and the like;
d7, the feature structure comprises attributes of features such as circles, rectangular grooves, points and straight lines, application modes such as feature structure, feature storage and feature extraction, and application modes such as an intersection mode, a fitting mode, a point selection mode, a CAD mode, an object mode and a projection mode; the characteristic optimization comprises attributes, characteristic structures, characteristic storage, characteristic extraction and the like of characteristics such as a solution circle, a rectangular groove, a point, a straight line and the like;
d8, aligning the two groups of different data through rigid transformation to unify the two groups of different data in the same coordinate system, wherein the aligning comprises the processes of best fit aligning, aligning to the global state, feature aligning, N point aligning, PLP aligning and RPS aligning;
d9, the analysis mainly includes measurement, angle, section, 3D comparison, GD & T, etc.
2. The method for digitally detecting the structure of a spacecraft based on a laser scanner as claimed in claim 1, wherein in the step D2, the structure pretreatment includes a structure material or surface color treatment, the structure material is transparent, the laser penetrates through the structure material or surface color treatment, so that the camera cannot accurately capture the position of the glass, and therefore the glass cannot be scanned; the laser line penetrates into the object when projected to the surface of the object, so that the position of the laser line captured by the camera is not the surface profile of the object, and the accuracy of scanning data is influenced; the highly reflective material can generate mirror reflection on light, so that the camera cannot capture the reflected light at certain angles and cannot obtain scanning data under the irradiation conditions; other materials or colors which can affect the diffuse reflection effect of the laser; before scanning, a contrast enhancer needs to be sprayed on the surface of the structure, so that the structure can perform diffuse reflection on laser irradiated on the surface of the structure.
3. The method for digitally detecting the structure of a spacecraft based on the laser scanner as claimed in claim 2, wherein in the step D3, the fast calibration board calibration includes fast calibration of the device by using the fast calibration board after the scanner is connected; placing the calibration plate on a stable plane, and enabling the scanner to be opposite to the calibration plate at a distance of about 400 mm; controlling the angle of the scanner, and adjusting the distance between the scanner and the calibration plate to enable the shadow circles on the left side to coincide; under the condition of ensuring that the shadow circles on the left side are basically overlapped, the scanner is horizontally moved without changing the angle, so that the trapezoidal shadows on the right side are overlapped, and then the distance is adjusted to enable the sizes of the trapezoidal shadows to be consistent; gradually lifting the equipment, calibrating the vertical direction, then calibrating the right side by 45 degrees, tilting the scanner by about 45 degrees to the right, and keeping the laser beam between the marking points of the fourth line and the fifth line to ensure that the shadows are overlapped; after the right side calibration is finished, performing left side 45-degree calibration, inclining the scanner to the left by about 45 degrees, and keeping the laser beam between the marking points of the fourth line and the fifth line to enable the shadow to coincide; after the left side calibration is finished, performing upper side 45-degree calibration, tilting the scanner upwards by about 45 degrees, and keeping the laser beam between the fourth row marking point and the fifth row marking point to enable the shadow to coincide; after the upper side calibration is finished, the lower side 45-degree calibration is carried out, the scanner is inclined downwards by about 45 degrees, and the laser beam is kept between the fourth line marking point and the fifth line marking point, so that the shadows are overlapped; and finishing calibration.
4. The laser scanner-based spacecraft structure digital detection method according to claim 3, wherein in the step D4, pre-scanning the mark points comprises collecting and scanning the mark points on the structure surface to establish the coordinates and the location of the structure; and performing identification reading on the mark points again by using a plurality of angles, or selecting the intelligent mark points for scanning.
5. The laser scanner-based spacecraft structure digital detection method according to claim 4, wherein in the step D5, the laser patch is scanned, including before scanning the laser patch (point), scan parameters (or default values of the parameters used) need to be set, such as scan resolution, exposure parameter setting, scan control, advanced parameter setting, professional parameter setting, and the like; the angle of the scanner and the distance between the scanner and the structure stably move the scanner, and the blank position data is completely acquired by using laser; after the scanning is completed, clicking to stop, starting to process the scanned data by software, waiting for the completion of the data processing, and finishing the scanning of the laser surface patch (point); the scanning software comprises data protection, automatic exposure, fine scanning, background mark points and the like.
6. The method for digitally detecting the spacecraft structure based on the laser scanner as claimed in claim 5, wherein in the step D6, gridding is performed, which includes packaging the point cloud data to make it exist in a planar form, the gridded data can be saved in a stl or ply format file format, and the file can be used for operations such as 3D printing and reverse engineering; the optional items in the gridding process have the functions of filling mark points, optimizing edges, realizing a high-precision mode, filling small holes, realizing the maximum edge number, thinning strength, smoothing level, optimizing level and the like.
7. The laser scanner-based spacecraft structure digital detection method according to claim 6, wherein in the step D7, the features include attributes of the features such as circles, rectangular grooves, points and straight lines, feature structures including intersection modes, fitting modes, point selection modes, CAD modes, object modes, projection modes, feature storage, feature extraction and other applications; feature extraction refers to the automatic fitting of features on reference data to near positions on test data under the same coordinate system to create the same type of feature operation.
8. The laser scanner-based spacecraft structure digital detection method according to claim 7, wherein in the step D9, analysis including measurement, angle, section, 3D comparison, GD & T and other application modes, when the measurement includes measuring the distance between the features, the second feature is taken as a main feature, the circle degenerates as a circle center, the circular groove, the elliptical groove and the rectangular groove degenerate as a central point, the sphere degenerates as a sphere center, the cylinder and the cone degenerate as an axis, and the distance is finally converted into one of a point-to-point distance, a point-to-line distance and a point-to-surface distance; when the angle comprises the angle between the measurement characteristics (plane and plane), the cylinder and the cone are degenerated into the axis, and the corresponding plane is taken as the circle, the circular groove, the elliptical groove and the rectangular groove; when the cross section comprises the cross sections of point cloud, grid and CAD data, the digital-to-analog data and the grid data are intercepted on the plane to obtain a cross section line, and the scanning data are intercepted on the plane to obtain the point cloud; 3D comparing and representing the deviation graph between the Test data and the Reference data by generating different colors, wherein the deviation graph is defined as a chromatogram (color difference graph), the deviation exists in positive and negative, the color value in the chromatogram evolves from blue to green to red, the blue represents that the measured curved surface is lower than the Reference curved surface, if the measured data is displayed in red, the data is positioned on the Reference surface, and the deviation is calculated by adopting the principle of the closest point; creating annotations partial bias annotations may be viewed; after creating the annotation, clicking the 'creation report' to store in a pdf format file; GD & T, form and position tolerances, including shape and position tolerances;
the shape tolerance comprises the variation amount allowed by the shape of a single actual element, such as roundness, straightness, flatness, cylindricity, sphericity and the like;
the position tolerance comprises the deviation of the associated actual measured element to an ideal measured element with a determined direction, and a position tolerance band is an allowable change area of the associated actual measured element and has parallelism, perpendicularity, coaxiality and the like;
the GD & T detection is established on the basis of the fitting features, the shape tolerance is only related to the fitting features and the fitted point cloud data, the position tolerance needs to be provided with the reference features, and the reference features can be constructed in any construction mode.
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