Visual inspection system for internal defects of flat shell

Abstract

The invention discloses a visual inspection device for internal defects of a flat shell. The visual inspection device comprises a base shell, in the application, the line scanning camera shoots the structured light image reflected by the internal surface of the shell from the outside through the folded light path of the semi-reflecting and semi-transmitting mirror and the prism, the structured light pattern deforms due to the existence of the bulge, the deformation is directly related to the surface height, each image is subjected to Fourier transform or is directly substituted into a phase formula, and the surface height of the structured light pattern is calculated. A phase value of each pixel point is extracted, the phase values are converted into height values by utilizing a triangulation principle and combining installation angles and distances of a light source and a camera, a three-dimensional height map of the inner surface of the shell is generated, and a folded light path formed by a semi-reflecting and semi-transmitting mirror and a prism is matched with an upper line scanning camera to form a three-dimensional height map of the inner surface of the shell. The problem that traditional equipment cannot enter a narrow shell is solved, meanwhile, an optical scheme is adopted, the equipment cost is effectively reduced, and compared with a linear scanning laser or structured light scheme, a customized sensor is not needed, and compatibility is high.

Description

Technical Field

[0001] This invention relates to the field of visual inspection equipment technology, and in particular to a visual inspection system for internal defects of a flat shell. Background Technology

[0002] A visual inspection device for internal defects of a housing refers to a device that uses machine vision technology to automatically detect defects on the internal surfaces or cavities of housing-type parts.

[0003] The casing, as a protective barrier for core components, plays a crucial role in protecting the products inside. However, various defects are unavoidable during casing welding. When a defect is a hard protrusion located inside the casing with a height exceeding a certain threshold, it poses a risk of damaging the core components. Therefore, the determination of this defect must include its height. When the casing is large enough, traditional line-scanning lasers, structured light, or light field cameras can be placed inside for height detection. However, when the casing is flat, these devices cannot enter to collect data. Although X-ray computed tomography scanners can detect defect height by performing three-dimensional reconstruction of the casing through X-ray penetration, this equipment is extremely expensive and slow, failing to meet the needs of production inspection. Therefore, there is an urgent need to develop a corresponding visual inspection device for defects inside flat casings to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to provide a visual inspection system for internal defects of flat shells in order to solve the above-mentioned problems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] In a first aspect, a visual inspection system for internal defects of a flat shell is provided, comprising a base shell, a line scan camera and a support assembly for adjusting the position of the line scan camera are integrated on the top of the base shell, the line scan camera includes a lens and a camera component, a light source is mounted on the horizontal outer side of the base shell, a prism is provided at the bottom of the base shell, and an inclined semi-reflective lens is fixedly connected to the inner surface wall of the base shell.

[0007] Preferably, a connecting frame is fixedly connected to the bottom of the base shell, and the bottom of the connecting frame is connected to the prism.

[0008] Preferably, the support assembly includes a vertical rod fixedly connected to the top of the base shell, a sleeve detachably connected to the outer wall of the vertical rod via a locking rod, a horizontal rod detachably connected to the inner wall of the sleeve via a locking rod, and the open end of the horizontal rod being fixedly engaged with a line scan camera.

[0009] Secondly, a visual inspection system for internal defects of a flat shell is provided, comprising:

[0010] The lighting equipment consists of a lighting unit and a control unit. The lighting unit consists of multiple sets of LED light sources, and the brightness of each LED light source is individually controlled by the control unit.

[0011] The image acquisition module consists of a lens, a camera component, a semi-reflective lens, a prism, and structural components. The image acquisition module acquires an image each time the lighting device changes its pattern, until the last pattern is acquired.

[0012] The movable slide is used to move the workpiece under test, enabling the line scan camera to scan the inner cavity of the workpiece and to move the prism into the required detection position of the housing.

[0013] The image fusion module combines multiple images acquired by the image acquisition module into a structural map that can display height information, thereby enabling the height of the protrusion to be detected.

[0014] The defect detection module is used to detect and judge defects based on the height information provided by the structural diagram;

[0015] The industrial control computer is used to implement the software functions of the image fusion and defect detection modules.

[0016] Thirdly, a visual inspection method for internal defects of a flat shell is provided, comprising the following steps:

[0017] S1. Structured light projection and image acquisition:

[0018] S11, Phase-shift structured light projection: LED light source sequentially projects sine wave patterns of different brightness onto the inner surface of the housing according to a preset phase;

[0019] S12, Image Acquisition: The line scan camera captures structured light images reflected from the internal surface of the housing from the outside through the folded light path of the semi-reflective lens and prism. Due to the presence of protrusions, the structured light pattern will be deformed, and these deformations are directly related to the surface height.

[0020] S2. Image Processing and 3D Reconstruction:

[0021] S21. Phase calculation: Substitute the phase formula into each image to extract the phase value of each pixel.

[0022] S22. Phase unwrapping: Since the phase value is limited to a certain range, the algorithm extends the phase value to a globally continuous value.

[0023] S23. Using the principle of triangulation, combined with the installation angle and distance between the light source and the camera, the phase value is converted into a height value to generate a three-dimensional height map of the inner surface of the shell.

[0024] S3. Defect detection and judgment.

[0025] Preferably, the defect detection and determination includes the following steps:

[0026] S31. Height threshold determination: Compare the height map with a preset threshold. If the height exceeds the threshold, it is determined to be a defect.

[0027] S32. Defect Marking and Handling: The system automatically marks the location of defects and outputs the detection results through the industrial control computer.

[0028] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0029] In this application, an LED light source projects sinusoidal wave patterns of different brightness onto the inner surface of the housing in sequence according to a preset phase. A line scan camera captures structured light images reflected from the inner surface of the housing from the outside through a folded optical path composed of a semi-reflective lens and a prism. Due to the presence of protrusions, the structured light pattern will be deformed. These deformations are directly related to the surface height. Fourier transform is performed on each image or the phase formula is directly substituted to extract the phase value of each pixel. Using the principle of triangulation, combined with the installation angle and distance between the light source and the camera, the phase value is converted into a height value to generate a three-dimensional height map of the inner surface of the housing. The height map is compared with a preset threshold (such as the maximum allowable height). If the height of a certain area is greater than the threshold, it is judged as a defect. The system automatically marks the defect location and outputs the detection results through the industrial control computer. It can be linked with mechanical equipment to sort unqualified products. The folded optical path composed of a semi-reflective lens and a prism, combined with the line scan camera, solves the problem that traditional equipment cannot enter the narrow interior of the housing. At the same time, the optical solution effectively reduces the equipment cost. Compared with line scan laser or structured light solutions, it does not require customized sensors and has strong compatibility. Attached Figure Description

[0030] Figure 1 A schematic diagram of the overall structure provided according to an embodiment of the present invention is shown;

[0031] Figure 2 A schematic diagram of a semi-reflective mirror structure provided according to an embodiment of the present invention is shown;

[0032] Figure 3 A schematic diagram of the crossbar and vertical bar structure provided according to an embodiment of the present invention is shown;

[0033] Figure 4 A schematic diagram of an optical path provided according to an embodiment of the present invention is shown.

[0034] Legend:

[0035] 1. Base shell; 2. Vertical rod; 3. Lens; 4. Camera component; 5. Light source component; 6. Connecting frame; 7. Prism; 8. Semi-reflective semi-transparent mirror; 9. Horizontal rod; 10. Support sleeve; 11. Locking rod one; 12. Locking rod two. Detailed Implementation

[0036] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0037] Please see Figure 1-4 The present invention provides a technical solution:

[0038] A visual inspection system for internal defects of a flat shell includes a base shell 1. A line scan camera and a support assembly for adjusting the position of the line scan camera are integrated on the top of the base shell 1. The line scan camera includes a lens 3 and a camera assembly 4. A light source 5 is mounted on the horizontal outer side of the base shell 1. A prism 7 is disposed at the bottom of the base shell 1, and a tilted semi-reflective lens 8 is fixedly connected to the inner surface of the base shell 1. A connecting frame 6 is fixedly connected to the bottom of the base shell 1, and the bottom of the connecting frame 6 is connected to the prism 7 to ensure convenient assembly and disassembly of the prism 7. The LED light source projects sine wave patterns of different brightness onto the internal surface of the shell in sequence according to a preset phase. The line scan camera, through the folded light path of the semi-reflective lens and the prism, captures the defects reflected from the internal surface of the shell from the outside. In the structured light image, due to the presence of protrusions, the structured light pattern will be deformed. These deformations are directly related to the surface height. Fourier transform is performed on each image or the phase formula is directly substituted to extract the phase value of each pixel. Using the principle of triangulation, combined with the installation angle and distance of the light source and the camera, the phase value is converted into a height value to generate a three-dimensional height map of the inner surface of the shell. The support component includes a vertical rod 2 fixedly connected to the top of the base shell 1. The outer wall of the vertical rod 2 is detachably connected to a sleeve 10 through a locking rod 11. The inner wall of the sleeve 10 is detachably connected to a horizontal rod 9 through a locking rod 12. The open end of the horizontal rod 9 is fixedly engaged with the line scan camera to realize the adjustment of the horizontal and vertical positions of the line scan camera.

[0039] A visual inspection system for internal defects of a flat shell, comprising:

[0040] The lighting equipment consists of a lighting unit and a control unit. The lighting unit comprises multiple sets of LED light sources, and the brightness of each LED in each set is individually controlled by the control unit, following the principle of phase-shift structured light.

[0041] y = sin(xπ + aπ / n)

[0042] y—brightness

[0043] x — pixel or LED position

[0044] a—The a-th image

[0045] n—total number of images;

[0046] The image acquisition module consists of a lens 3, a camera component 4, a semi-reflective lens 8, a prism 7, and structural components. The image acquisition module acquires an image each time the lighting device changes its pattern, until the last pattern is acquired.

[0047] The movable slide is used to move the workpiece under test, enabling the line scan camera to scan the inner cavity of the workpiece by moving it, and to move the prism 7 into the required detection position of the housing.

[0048] The image fusion module combines multiple images acquired by the image acquisition module into a structural map that can display height information, thereby enabling the height of the protrusion to be detected.

[0049] The defect detection module is used to detect and judge defects based on the height information provided by the structural diagram;

[0050] An industrial control computer is used to implement the software functions of the image fusion and defect detection module. A visual inspection method for internal defects of a flat shell includes the following steps:

[0051] S1. Structured light projection and image acquisition:

[0052] S11, Phase-shift structured light projection: LED light source sequentially projects sine wave patterns of different brightness onto the inner surface of the housing according to a preset phase;

[0053] S12, Image Acquisition: The line scan camera captures structured light images reflected from the internal surface of the housing from the outside through the folded optical path of the semi-reflective mirror 8 and prism 7. Due to the presence of protrusions, the structured light pattern will be deformed, and these deformations are directly related to the surface height.

[0054] S2. Image Processing and 3D Reconstruction:

[0055] S21. Phase calculation: Substitute the phase formula into each image to extract the phase value of each pixel.

[0056] S22. Phase unwrapping: Since the phase value is limited to a certain range, the algorithm extends the phase value to a globally continuous value.

[0057] S23. Using the principle of triangulation, combined with the installation angle and distance between the light source 5 and the camera, the phase value is converted into a height value to generate a three-dimensional height map of the inner surface of the shell.

[0058] S3. Defect detection and judgment.

[0059] Defect detection and judgment include the following steps:

[0060] S31. Height threshold determination: Compare the height map with a preset threshold. If the height exceeds the threshold, it is determined to be a defect.

[0061] S32. Defect Marking and Handling: The system automatically marks the location of defects and outputs the detection results through the industrial control computer.

[0062] Working Principle: The LED light source projects sinusoidal wave patterns of different brightness onto the inner surface of the housing in sequence according to a preset phase. The line scan camera captures the structured light image reflected from the inner surface of the housing from the outside through the folded optical path of the semi-reflective lens and prism. Due to the presence of protrusions, the structured light pattern will be deformed. These deformations are directly related to the surface height. Fourier transform is performed on each image or the phase formula is directly substituted to extract the phase value of each pixel. Using the principle of triangulation, combined with the installation angle and distance between the light source and the camera, the phase value is converted into a height value to generate a three-dimensional height map of the inner surface of the housing. The height map is compared with a preset threshold. If the height of a certain area is greater than the threshold, it is judged as a defect. The system automatically marks the defect location and outputs the detection result through the industrial control computer. It can be linked with mechanical equipment to sort unqualified products. The folded optical path composed of the semi-reflective lens 8 and prism 7, combined with the line scan camera, solves the problem that traditional equipment cannot enter the narrow interior of the housing. At the same time, the optical solution effectively reduces the equipment cost. Compared with line scan laser or structured light solutions, it does not require customized sensors and has strong compatibility.

[0063] The above description of the embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A visual inspection device for internal defects of a flat shell, comprising a base shell (1), characterized in that, The top of the base shell (1) is integrated with a line scan camera and a support assembly for adjusting the position of the line scan camera. The line scan camera includes a lens (3) and a camera component (4). A light source component (5) is installed on the horizontal outer side of the base shell (1). A prism (7) is provided at the bottom of the base shell (1), and a tilted semi-reflective lens (8) is fixedly connected to the inner surface wall of the base shell (1).

2. The visual inspection device for internal defects of a flat shell according to claim 1, characterized in that, The bottom of the base shell (1) is fixedly connected to a connecting frame (6), and the bottom of the connecting frame (6) is connected to the prism (7).

3. The visual inspection device for internal defects of a flat shell according to claim 2, characterized in that, The support assembly includes a vertical rod (2) fixedly connected to the top of the base shell (1), a sleeve (10) detachably connected to the outer wall of the vertical rod (2) via a locking rod (11), a horizontal rod (9) detachably connected to the inner wall of the sleeve (10) via a locking rod (12), and the open end of the horizontal rod (9) being fixedly engaged with the line scan camera.

4. A visual inspection system for internal defects of a flat shell, characterized in that, include: The lighting equipment consists of a lighting unit and a control unit. The lighting unit consists of multiple sets of LED light sources, and the brightness of each LED light source is individually controlled by the control unit. The image acquisition module consists of a lens (3), a camera component (4), a semi-reflective lens (8), a prism (7), and structural components. The image acquisition module acquires an image once for each change of the pattern of the lighting device, until the last pattern is acquired. The movable slide is used to move the workpiece to be measured, so that the line scan camera can scan the inner cavity of the workpiece by moving it, and the prism (7) can enter the required detection position of the housing. The image fusion module combines multiple images acquired by the image acquisition module into a structural map that can display height information, thereby enabling the height of the protrusion to be detected. The defect detection module is used to detect and judge defects based on the height information provided by the structural diagram; The industrial control computer is used to implement the software functions of the image fusion and defect detection modules.

5. A visual inspection method for internal defects of a flat shell, characterized in that, Includes the following steps: S1. Structured light projection and image acquisition: S11, Phase-shift structured light projection: LED light source sequentially projects sine wave patterns of different brightness onto the inner surface of the housing according to a preset phase; S12, Image Acquisition: The line scan camera captures the structured light image reflected from the inner surface of the shell from the outside through the folded light path of the semi-reflective half-lens (8) and prism (7). Due to the presence of protrusions, the structured light pattern will be deformed, and these deformations are directly related to the surface height. S2. Image Processing and 3D Reconstruction: S21. Phase calculation: Substitute the phase formula into each image to extract the phase value of each pixel. S22. Phase unwrapping: Since the phase value is limited to a certain range, the algorithm extends the phase value to a globally continuous value. S23. Using the principle of triangulation, the phase value is converted into a height value by combining the installation angle and distance between the light source (5) and the camera, and a three-dimensional height map of the inner surface of the shell is generated. S3. Defect detection and judgment.

6. The visual inspection device for internal defects of a flat shell according to claim 5, characterized in that, The defect detection and determination includes the following steps: S31. Height threshold determination: Compare the height map with a preset threshold. If the height exceeds the threshold, it is determined to be a defect. S32. Defect Marking and Handling: The system automatically marks the location of defects and outputs the detection results through the industrial control computer.

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