A device for measuring three-dimensional shape of micro-particles based on machine vision

Abstract

A kind of measuring device of the three-dimensional shape of micro-particle based on machine vision, comprising: micro-particle driving unit, micro-particle position adjustment unit, side view image shooting unit, overhead view image shooting unit, light source and processing unit;Wherein, processing unit includes computer and controller;Computer is analyzed to the micro-particle image obtained by side view image shooting unit and overhead view image shooting unit, and further by controller micro-particle driving unit and management micro-particle position adjustment unit are started to execute action to control the motion trajectory of micro-particle in time.The micro-particle guiding device and micro-particle driving unit in the application can accurately position and drive micro-particle;The measurement accuracy of microscopic camera can reach 1 μm, and the shape of micro-particle in the range of 10 μm-500 μm can be accurately measured;Device structure is simple, convenient to operate, modeling method is simple and effective, and measurement cost is lower.

Description

Technical Field

[0001] This invention relates to the field of microscale measurement technology, and in particular to a measurement device for the three-dimensional shape of tiny particles based on machine vision. Background Technology

[0002] Air contains varying amounts of sand, dust, and other particulate matter, which poses a significant threat to helicopters. Helicopters, with their high maneuverability, often lack fixed landing sites and dedicated airfields during wartime. In most cases, they use makeshift landing sites, or even temporary outdoor areas of soil, sand, or grass. Furthermore, when helicopters fly or hover at low altitudes near the ground, the downwash generated by their rotors stirs up large amounts of sand and dust, greatly increasing the concentration of fine particulate matter in the air and posing a considerable hazard to helicopters.

[0003] Fine particles such as sand and dust entering the engine intake manifold can cause severe wear on various components in the engine's air and combustion passages, especially the rotor blades. The consequences are: ① Severe wear on the engine's internal compressor: For axial compressors, the most severe wear is typically at the intake edges of the blades, the necks of the working blades, and the roots of the rectifier blades; the sealing coating on the inner wall of the compressor casing also wears down. For centrifugal compressors, due to their larger impeller frontal area, wear is most severe. This damage deteriorates engine performance, causing a decrease in power and an increase in fuel consumption; ② The heat-resistant magnetic coating on the combustion chamber will be worn away, affecting the combustion chamber's high-temperature resistance; ③ Sand and dust entering some poorly sealed rotating parts of the engine can disrupt rotor balance; ④ Fine sand and dust entering the turbine working blade cooling channels can block the channels, causing the working blades to overheat and even burn out; ⑤ When larger sand and dust enter the engine at high speeds, they may damage the compressor blades.

[0004] Currently, preventative measures against the hazards of dust and other fine particulate matter to helicopters include: proper helicopter parking, installation of air intake protection devices, thorough helicopter cleaning, and strict control over the disassembly and assembly of components. Furthermore, to better numerically simulate the movement of dust particles in airflow and develop accurate force models, it is necessary to precisely measure the three-dimensional shape of dust particles at different scales and conduct motion and force analysis experiments on dust particles or dust models in a specialized wind tunnel. Therefore, how to conveniently, quickly, and accurately measure the three-dimensional shape of dust particles and other fine particulate matter at different scales is a pressing technical challenge that needs to be addressed.

[0005] Currently, methods for measuring the shape of particles at the tens of micrometer scale include micro-computed tomography (Micro-CT). The principle of Micro-CT imaging involves using a microfocus X-ray tube to scan and project X-rays onto different parts of an object. A detector receives the X-rays transmitted through that layer, converts them into visible light, a photoelectric converter converts them into electrical signals, and then an analog-to-digital converter converts them into digital signals, which are then input into a computer for imaging. However, Micro-CT equipment is expensive, and measurement costs are high. Currently, there is a lack of technology that can accurately locate and manipulate particles at the tens of micrometer scale, and that provides convenient, economical, and rapid three-dimensional shape measurement. Summary of the Invention

[0006] The purpose of this invention is to solve the problems mentioned in the background art and to propose a machine vision-based device for measuring the three-dimensional shape of tiny particles.

[0007] Based on the background technology, this invention proposes a machine vision-based device for measuring the three-dimensional shape of tiny particles. This device is not only low-cost, but also enables precise positioning and manipulation of particles on the order of tens of micrometers, and quickly and accurately obtains their three-dimensional shape.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A machine vision-based device for measuring the three-dimensional shape of microparticles includes five units: a side view image capturing unit, a top view image capturing unit, a microparticle driving unit, a microparticle position adjustment unit, and a control and management unit.

[0010] The microparticle drive unit includes a pressure reducing valve (11), a high-pressure gas tank (12), a gas conduit (13), a three-way valve (14), a valve one (15), a valve two (16), a nozzle one (17), and a nozzle two (18), used to generate an airflow of moderate intensity to drive the microparticles to move to the center position of the turntable surface. The function of the pressure reducing valve (13) is to reduce the pressure of the airflow flowing out of the high-pressure gas tank. The functions of the valve one (15) and the valve two (16) are to further fine-tune the airflow velocity ejected from the nozzle one (17) and the nozzle two (18), and the size of the nozzle one (17) and the nozzle two (18) can be adjusted according to the size of the microparticles.

[0011] The particulate matter position adjustment unit includes a particulate matter guide device (19), a guide device remover (21), a turntable (22), a horizontal displacement adjustment device (23), a vertical displacement adjustment device (24), an acrylic protective cover (25), and a tabletop magnifying glass (26). It is used to adjust the position of the particulate matter so that it can be clearly captured by the side view imaging unit and the top view imaging unit. The bottom area of ​​the particulate matter guide device (19) is the same as the surface area of ​​the turntable. Its sidewalls are spiral-shaped. At the same time, the center of the bottom surface of the particulate matter guide device is consistent with the center of the turntable surface. There is a small hole in the center of the bottom surface of the particulate matter guide device, through which the particulate matter can be guided to the center position of the turntable surface, and then the particulate matter guide device is removed. The guide device remover (21) specifically includes a vertical support three (21-1), a horizontal adjustment mechanism (21-2), a height adjustment mechanism three (21-3), a longitudinal adjustment mechanism (21-4), and a positioning slot (21-5). The function of the guide device remover (21) is to first vertically raise the microparticle guide device after the microparticle is in a designated position, and then move it back a certain distance to remove the microparticle guide device (19). The turntable (22) changes the shooting angle of the side view of the microparticle by rotating. The horizontal displacement adjustment device (23) can adjust the horizontal position of the microparticle. The vertical displacement adjustment device (24) can adjust the vertical position of the microparticle. The plexiglass protective cover (25) can prevent the airflow from disturbing the position of the microparticle. The tabletop magnifying glass (26) can magnify the microparticle, thereby facilitating the manipulation and positioning of the microparticle using nozzle one (17) and nozzle two (18).

[0012] The control and management unit includes a controller (2) and a computer (1) to analyze the particulate matter images obtained by the side-view and top-view image capturing units and further drive the particulate matter position adjustment unit. The controller (2) can control the height adjustment mechanism one (5), the height adjustment mechanism two (9), the horizontal displacement adjustment device (23), and the vertical displacement adjustment device (24). The computer (1) is used to save and analyze the particulate matter images;

[0013] The side-view image acquisition unit includes a vertical support (4), a height adjustment mechanism (5), a horizontally placed microscope camera (6), and a light source (7) for acquiring side-view images of minute particles. The height adjustment mechanism (5) can adjust the position of the horizontally placed microscope camera (6) in the vertical direction. The light source (7) is used to provide suitable illumination to obtain clear images of minute particles. The central axis of the horizontally placed microscope camera (6) is parallel to the turntable plane;

[0014] The top-view image capturing unit includes a vertically placed microscope camera (8), a height adjustment mechanism two (9), and a vertical support two (10) for obtaining top-view images of tiny particles. The height adjustment mechanism two (9) can adjust the position of the horizontally placed microscope camera (8) in the vertical direction. The central axis of the vertically placed microscope camera is perpendicular to the turntable plane;

[0015] A microscope camera consists of a CCD camera, a teleconverter, a lens barrel, a light source, and a lens. The CCD camera is used for image capture, the teleconverter is used to magnify the captured image, the lens barrel is used to produce a suitable focal length, and the light source is used to improve the image capture quality. A clip is installed on the lens barrel so that the microscope camera can be fixed on the threaded hole of the height adjustment mechanism.

[0016] The steps for constructing the three-dimensional shape of tiny particles are as follows:

[0017] ① Extraction of the outer contour curve of fine particles: Based on the captured images of fine particles, basic parameters and an empty matrix are first defined. Image filtering and enhancement processing are performed on the captured images of gravel to highlight the features of contours and edges in the image. Then, the Sobel operator is used to extract the edges of the gravel in the top and side views to obtain the coordinate data of the contour points, while removing some noise. Finally, the target contour is determined based on the boundary point data of fine particles in the top and side views; ② Contour point data processing: First, the center point of each contour is calculated, the coordinates of the contour points are reset, and the polarization angle of each contour point is calculated. Then, the contour points of each view are uniformly processed, and finally, the data of each view is output. Figure 2 ③ Constructing the 3D model: First, based on the angle of the microparticles when they were photographed, transform each 2D contour line to the same 3D coordinate system. Then, output the coordinate information of all contour point clouds and use the Delaunay triangulation algorithm to construct the microparticle entity. Finally, output the 3D microparticle model in the corresponding format as required.

[0018] When taking side view photos of small particles, the rotation angle of the turntable can be selected from 10-60°, and the angle accuracy of the turntable is not less than 0.5°.

[0019] Compared with the prior art, the present invention provides a measurement system for the three-dimensional shape of tiny particles, which has the following advantages:

[0020] ①The microparticle guiding device and microparticle driving unit in this invention can accurately position and drive microparticles;

[0021] ②The measurement accuracy of the microscope camera in this invention can reach 1µm, which can accurately measure the shape of tiny particles in the range of 10µm-500µm.

[0022] ③The device of the present invention has a simple structure, is easy to operate, has a concise and effective modeling method, and has a low measurement cost.

[0023] The parts of the device not covered herein are the same as or can be implemented using existing technologies. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the imaging system of the present invention;

[0025] Figure 2 This is a top view of the microparticle guiding device of the present invention;

[0026] Figure 3 This is a perspective view of the microparticle guiding device of the present invention;

[0027] Figure 4 This is a schematic diagram of the remover and part of the control device of the microparticle guiding device of the present invention.

[0028] Figure 5 This is a schematic diagram of the microscope camera of the present invention;

[0029] Figure 6 This is a schematic diagram of the vertical support and height adjustment mechanism of the present invention;

[0030] Figure 7 This is a schematic diagram of the controller in this invention;

[0031] Figure 8 This is a schematic diagram of the process for constructing the three-dimensional shape of tiny particles in this invention.

[0032] Figure label:

[0033] 1-Computer; 2-Controller; 3-Optical vibration isolation platform; 4-Vertical support one; 5-Height adjustment mechanism one; 6-Horizontally placed microscope camera; 7-Light source; 8-Vertically placed microscope camera; 9-Height adjustment mechanism two; 10-Vertical support two; 11-Pressure reducing valve; 12-High-pressure gas tank; 13-Gas conduit; 14-T-connector; 15-Valve one; 16-Valve two; 17-Nozzle one; 18-Nozzle two; 19-Microparticle guiding device; 20-Microparticles; 21-Remover of guiding device; 22-Turntable; 23-Horizontal displacement adjustment device; 24-Vertical displacement adjustment device; 25-Acrylic protective cover; 26-Tabletop magnifying glass; 27-CCD camera; 28-Magnifying lens; 29-Lens barrel; 30-Light source; 31-Lens; 32-Stepper motor; 33-V groove. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0035] In the description of this invention, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0036] Example 1

[0037] like Figure 1 As shown, the particulate guide 19 is placed on the positioning slot 31 of the guide device remover 21. By adjusting the position of the positioning slot, the particulate guide 19 is positioned on the upper surface of the turntable 22. Then, the top cover of the plexiglass protective cover 25 is opened, and the operator can use the smooth inner surface of the V-groove 33 to place the particulate 20 at the inlet of the particulate guide 19. The size of the particulate is in the range of 40 to 3000 micrometers, and the inlet width of the particulate guide is 4000 micrometers. Then, the pressure reducing valve 11, valve one 15, and valve two 16 of the high-pressure gas tank are opened in sequence. By adjusting the position of nozzle one 17 and nozzle two 18 and the resulting airflow velocity, the operator manually drives the particulate along the spiral curve of the particulate guide to the center of the turntable 22. The bottom area of ​​the microparticle guiding device 19 is the same as the surface area of ​​the turntable, and its sidewalls are spiral-shaped. At the same time, the center of the bottom surface of the microparticle guiding device is consistent with the center of the turntable surface. There is a small hole in the center of the bottom surface of the microparticle guiding device, through which microparticles can be guided to the center position of the turntable surface. Then, the microparticle guiding device 19 is first vertically lifted using the guide device remover 21, and then moved back a distance to remove the microparticle guiding device.

[0038] Turn on computer 1, controller 2, horizontally placed microscope camera 6, and vertically placed microscope camera 8;

[0039] like Figure 7As shown, the image clarity of the microscopic particles is determined by the images captured by the horizontally placed microscope camera 6 and the vertically placed microscope camera 8. If the clarity of the microscopic particle outline does not match the set value, the controller 2 drives the height adjustment mechanism 5, the height adjustment mechanism 9, the horizontal displacement adjustment device 23, and the vertical displacement adjustment device 24 until the clarity of the microscopic particle outline meets the requirements. Finally, the images captured by the horizontally placed microscope camera 6 and the vertically placed microscope camera 7 at the same rotation angle of the microscopic particle are stored in the computer 1.

[0040] The turntable was rotated so that the tiny particles rotated 30º, and then two microscopic cameras were used to take pictures and record the existing images and their position information. This process was repeated 12 times.

[0041] Based on the images captured by the two cameras and their corresponding location information, the three-dimensional shape of the microparticles is reconstructed to obtain a three-dimensional shape model of the microparticles.

[0042] like Figure 8 As shown, the steps for constructing the three-dimensional shape of tiny particles are as follows:

[0043] ① Extraction of the outer contour curve of small particles: Based on the captured images of small particles, first define basic information (including file path, file name, image grayscale threshold, angle step size, etc.) and empty matrix and cells for storing target point cloud data. Then extract the boundary point data of small particles in the top view and side view. Finally, use the bwboundaries() function to determine the target contour.

[0044] ② Contour point data processing: First, the center point of each contour is calculated by averaging the maximum and minimum values ​​of the horizontal and vertical coordinates. The contour point coordinates are then reset, and the polarization angle of each contour point is calculated. The polarization angle data is sorted using the sort() function in ascending order. Then, based on the selected angle step size, the contour points of each view are uniformly processed to ensure that the number of contour points in each contour is equal. Finally, each view is output. Figure 2 3D outline diagram and point numbering;

[0045] ③ Constructing the 3D model: First, the transfer() function is used to transfer the 2D contour lines to the same 3D space, and the mixpoints() function is used to interpolate between the existing contour lines; then, all point cloud data is output, and the unique() function is used to remove duplicate data, the boundary() function is used to obtain the 3D boundary of the point cloud, the triangulation() function is used to create triangulation, and the triplot() function is used to output the triangulation and write it to an STL file; finally, the alphaShape() function is used to draw the 3D polyhedron.

[0046] In image processing software, the operators and functions in this invention are known algorithms and functions.

[0047] This measuring device can quickly obtain contour images of tiny particles at different rotation angles within minutes, and accurately reconstruct the three-dimensional shape of the tiny particles based on these images.

[0048] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A machine vision-based device for measuring the three-dimensional shape of tiny particles, characterized in that, The measuring device comprises five units: a micro-particle driving unit, a micro-particle position adjusting unit, a side-view image shooting unit, an overhead-view image shooting unit, a light source (7) and a processing unit; Wherein, The processing unit comprises a computer (1) and a controller (2); The computer (1) analyzes the micro-particle images obtained by the side-view image shooting unit and the overhead-view image shooting unit, and further initiates the micro-particle driving unit and the micro-particle position adjusting unit to execute actions to timely control the motion trajectory of the micro-particle through the controller (2); The micro-particle driving unit comprises a pressure reducing valve (11), a high-pressure gas tank (12), a gas conduit (13), a tee joint (14), a valve one (15), a valve two (16), a nozzle one (17) and a nozzle two (18), which are used to generate a moderate-intensity air flow to drive the micro-particle to move on the turntable to the central position of the turntable surface under the management of the controller (2); The micro-particle position adjusting unit comprises a micro-particle guiding device (19), a remover (21) of the guiding device, a turntable (22), a horizontal displacement adjusting device (23), a vertical displacement adjusting device (24), an organic glass protective cover (25) and a table magnifier (26), which are used to adjust the position of the micro-particle to be clearly shot by the side-view image shooting unit and the overhead-view image shooting unit under the management of the controller (2); The side-view image shooting unit comprises a vertical support one (4), a height adjusting mechanism one (5) and a horizontally placed micro camera (6), which are used to obtain the side-view image of the micro-particle and provide it to the computer (1) under the management of the controller (2); The overhead-view image shooting unit comprises a vertically placed micro camera (8), a height adjusting mechanism two (9) and a vertical support two (10), which are used to obtain the overhead-view image of the micro-particle and provide it to the computer (1) under the management of the controller (2); The bottom surface area of the micro-particle guiding device (19) is the same as the area of the turntable surface, the sidewall of the micro-particle guiding device is in a spiral shape, the center of the bottom surface of the micro-particle guiding device is consistent with the center of the turntable surface, and a small hole exists in the center of the bottom surface of the micro-particle guiding device; Under the management of the controller (2), the micro-particle is guided to the central position of the turntable through the small hole by the micro-particle guiding device (19) and the micro-particle driving unit, the remover (21) of the guiding device vertically lifts the micro-particle guiding device first, then retreats a distance to remove the micro-particle guiding device after the micro-particle is in the specified position, and the organic glass protective cover (25) prevents the disturbance of air flow to the position of the micro-particle; The central axis of the vertically placed micro camera is perpendicular to the turntable plane, and the central axis of the horizontally placed micro camera is parallel to the turntable plane.

2. The machine vision-based three-dimensional profile measuring apparatus of fine particulate matter according to claim 1, wherein The three-dimensional shape construction method of the micro-particle runs on the computer (1), and the algorithm steps are as follows: ① The outline curve extraction of the fine particle: According to the picture of the fine particle, the basic parameters and the empty matrix are defined firstly, then the boundary point data of the fine particle in the top view and side view are extracted, and finally the target outline is determined; ② The data processing of the outline point: Firstly, the center point of each outline is calculated, the coordinate of the outline point is reset, and the polarization angle of each outline point is calculated, then the uniform processing of each view outline point is carried out, and finally the two-dimensional outline graph and the point serial number of each view are outputted; ③ The construction of the three-dimensional model: Firstly, the two-dimensional outline line is converted to the same three-dimensional space, then the point cloud data is outputted, and the triangular partition is further created, and finally the three-dimensional model is drawn and outputted.

3. The machine vision-based three-dimensional profile measuring apparatus of minute particles according to claim 1, wherein The rotation angle of the turntable is selected from 10-60° when the side view of the fine particle is shot each time, and the angle accuracy of the turntable is not less than 0.5°.

4. The machine vision-based three-dimensional profile measuring apparatus of minute particles according to claim 1, wherein The micro camera includes a CCD camera, a magnifying lens, a lens barrel, a light source and a lens, and the measurement accuracy reaches 1µm.

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