Measuring system and measuring method of three-dimensional coordinate measuring machine based on image processing

Abstract

The present invention belongs to the field of three-coordinate measurement technology, and specifically discloses a measurement system of a three-coordinate measuring machine based on image processing, including a three-coordinate measuring machine and an image processing module connected to the three-coordinate measuring machine; the three-coordinate measuring machine includes a substrate, a Z-axis sliding plate is arranged on one side of the upper surface of the substrate, a rotating platform is arranged at the center position of the upper surface of the substrate, the rotating platform is arranged with 3 mobile fixture assemblies, and the substrate is evenly arranged with 3 image collectors; the image processing module includes a controller and a three-dimensional reconstruction unit, an image processing unit, a three-coordinate establishment unit, and an image display unit connected to the controller. The present invention can use the feature point and contour line coordinates as the standard in batch workpiece measurement to quickly determine the three-dimensional parameters of the workpiece, and can determine whether the workpiece is qualified by the coordinates of other feature points.

Description

Technical Field

[0001] The method belongs to the technical field of three-coordinate measurement, and particularly relates to a measurement system of a three-coordinate measuring machine based on image processing and a measurement method thereof. Background Art

[0002] The three-dimensional coordinate measuring machine obtains the spatial coordinate information of the contact point through contact measurement, reflecting the actual manufacturing size of the part and the surface flatness and other information, and is widely used in laboratory scientific research and industrial production. When performing three-dimensional coordinate measurement, it mainly relies on manual point finding, but for complex workpiece measurement, it is necessary to repeatedly find the contact point, which is cumbersome to operate. In addition, when the same workpiece is placed at different positions on the measurement platform, the coordinates in the three-dimensional coordinate software system will also be different, resulting in the lack of standard coordinates of feature points in the batch measurement process, and low measurement efficiency.

[0003] Therefore, providing a new measurement system and measurement method of a three-dimensional coordinate measuring machine based on image processing is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0004] The purpose of the method is to overcome the defects of complicated measuring process and low efficiency in the prior art, and to provide a measuring system of a three-coordinate measuring machine based on image processing and a measuring method thereof.

[0005] A first aspect of the present invention provides a measurement system for a three-coordinate measuring machine based on image processing, comprising a three-coordinate measuring machine and an image processing module connected to the three-coordinate measuring machine;

[0006] The three-dimensional coordinate measuring machine includes a base plate, a Z-axis sliding plate is arranged on one side of the upper surface of the base plate, a rotating platform is arranged at the center position of the upper surface of the base plate, a Y-axis sliding plate is arranged on the Z-axis sliding plate, an X-axis sliding rod is arranged on the lower surface of the Y-axis sliding plate, and a measuring ball is arranged at the end of the Z-axis sliding rod;

[0007] Three movable fixture assemblies are installed on the rotating platform, and the three movable fixture assemblies are symmetrically arranged relative to the center of the rotating platform; three image collectors are arranged on the substrate, and the three image collectors are located on the peripheral side of the rotating platform and are symmetrically arranged relative to the center of the rotating platform;

[0008] The substrate is slidably connected to the Z-axis sliding plate via a first driving unit, the Z-axis sliding plate is slidably connected to the Y-axis sliding plate via a second driving unit, and the Y-axis sliding plate is slidably connected to the X-axis sliding rod via a third driving unit;

[0009] The image processing module includes a controller and a three-dimensional reconstruction unit, an image processing unit, a three-coordinate establishment unit, and an image display unit connected to the controller;

[0010] The measuring ball is connected to the three-dimensional reconstruction unit and is used to establish the complete elements of the workpiece to be measured and obtain a three-dimensional model. The image collector is connected to the image processing unit and is used to perform edge image conversion and sharpening processing on the original image acquired by the image collector. The image display unit is connected to the three-coordinate establishment unit and is used to display the established three-coordinate system on the image display unit and display the processed image. The controller is used to control the movement of at least the first drive unit, the second drive unit, the third drive unit and the mobile fixture assembly, and selects the contour line and the feature point so that a certain feature point of the workpiece to be measured coincides with the origin of the three-dimensional coordinate.

[0011] A further solution is that the mobile fixture assembly includes a slider, a telescopic rod, a fixture and a driving cylinder;

[0012] Three slide grooves are installed on the rotating platform, and the three slide grooves are symmetrically arranged relative to the center of the rotating platform; the slide grooves are slidably connected to the slider;

[0013] One end of the slider is connected to the driving cylinder, and the other end is connected to the telescopic rod, and a clamp is provided at one end of the telescopic rod away from the slider;

[0014] The driving cylinder and the telescopic rod are both connected to the controller signal;

[0015] The driving cylinder controls the clamp to move within the range of Q1, and the telescopic rod controls the clamp to move within the range of Q2, wherein Q1 is the moving range of the output end of the driving cylinder, and Q2 is the extension range of the telescopic rod, and Q1>Q2.

[0016] A further solution is that a measuring platform is provided at a central position of an upper surface of the rotating platform, and the measuring platform is mechanically fixedly connected to the rotating platform.

[0017] A further solution is that the image processing module also includes a feature point determination unit, which is used to determine the feature points of the three-dimensional model and obtain the coordinate information of the feature points based on the projection relationship between the three-dimensional model and the two-dimensional image and the key point information of the workpiece to be measured.

[0018] A further solution is that the image processing unit performs grayscale processing on the original image to obtain a grayscale image;

[0019] The controller calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel;

[0020] The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

[0021] A second aspect of the present invention provides a measurement method of a three-dimensional coordinate measuring machine based on image processing, the method utilizing the above system and comprising the following steps:

[0022] The workpiece to be measured is placed on the rotating platform, and the original image of the workpiece is acquired by the image collector and sent to the image processing unit;

[0023] After the image processing unit processes the original image, it displays it in a three-coordinate system;

[0024] Adjust the position of the mobile fixture assembly so that a certain feature point of the processed image coincides with the coordinate origin of the three-coordinate system;

[0025] The workpiece to be measured is measured using a measuring ball.

[0026] A further solution is that the processing of the original image by the image processing unit includes edge image conversion and sharpening processing;

[0027] The edge image conversion comprises: an image processing unit performs grayscale processing on the original image to obtain a grayscale image;

[0028] The controller calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel;

[0029] The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

[0030] A further solution is that the adjusting and moving fixture assembly makes a certain feature point of the processed image coincide with the coordinate origin of the three-coordinate system through coarse adjustment and fine adjustment;

[0031] The coarse adjustment is as follows: the vector value of the distance between the feature point and the origin of the three coordinates is calculated according to the coordinates of the selected feature point, and the controller controls a driving cylinder to push a fixture to control the workpiece to be measured to move within the range of Q1; the controller calculates the moving distance of the other two fixtures through trigonometric functions and controls the other two driving cylinders to drive the fixtures to move. In this process, the length of the telescopic rod is the initial length;

[0032] The fine adjustment is as follows: the extension / contraction amount of the telescopic rod is determined again according to the workpiece to be measured after the movement, and the controller controls one telescopic rod to push one fixture to control the workpiece to be measured to move within the range of Q2; the controller calculates the moving distance of the other two fixtures through trigonometric functions and controls the other two telescopic rods to drive the fixtures to move;

[0033] Said Q1>Q2.

[0034] Compared with the prior art, the beneficial effect of the method is that the present invention controls the rotating platform, the mobile fixture assembly and the image collector through a controller to obtain the original image of the workpiece to be measured, and displays the processed original image in a three-dimensional coordinate system. By selecting contour lines and feature points, a certain feature point is made to coincide with the origin of the three-dimensional coordinates. The feature point and contour line coordinates can be used as a standard in batch workpiece measurement to quickly determine the three-dimensional parameters of the workpiece, and the coordinates of other feature points can be used to determine whether the workpiece is qualified. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The following figures are only used to illustrate and explain the method, and are not used to limit the scope of the method, wherein:

[0036] Figure 1 : Schematic diagram of the structural connection of the present invention;

[0037] Figure 2 : Schematic diagram of the rotating platform structure;

[0038] Figure 3 : Principle block diagram of image processing module;

[0039] In the figure: 1. Base plate; 2. Z-axis sliding plate; 3. Y-axis sliding plate; 4. Rotating platform; 4.1. Sliding block; 4.2. Telescopic rod; 4.3. Fixture; 4.4. Slide groove; 4.5. Driving cylinder; 4.6. Workpiece to be measured; 5. X-axis sliding rod; 6. Image acquisition device; 7. Image processing module; 7.1. Controller; 7.2. Three-dimensional reconstruction unit; 7.3. Image processing unit; 7.4. Three-coordinate establishing unit; 7.5. Image display unit; 7.6. Feature point determination unit. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution, design method and advantages of the method clearer, the method is further described in detail by specific embodiments in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to explain the method and are not used to limit the method.

[0041] Embodiment 1:

[0042] like Figure 1 and Figure 3As shown, the first aspect of the present invention provides a measurement system of a three-coordinate measuring machine based on image processing, comprising a three-coordinate measuring machine and an image processing module 7 connected to the three-coordinate measuring machine;

[0043] The three-dimensional coordinate measuring machine comprises a base plate 1, a Z-axis sliding plate 2 is arranged on one side of the upper surface of the base plate 1, a rotating platform 4 is arranged at the center of the upper surface of the base plate 1, a Y-axis sliding plate 3 is arranged on the Z-axis sliding plate 2, an X-axis sliding rod 5 is arranged on the lower surface of the Y-axis sliding plate 3, and a measuring ball is arranged at the end of the X-axis sliding rod 5;

[0044] The rotating platform 4 is provided with three movable fixture assemblies, which are symmetrically arranged relative to the center of the rotating platform; the substrate 1 is provided with three image collectors 6, which are located on the periphery of the rotating platform 4 and are symmetrically arranged relative to the center of the rotating platform 4. That is, the included angle of the three movable fixture assemblies is 120°, and the three image collectors 6, which are 120° apart from each other, are not on the extension line of the same equilateral triangle.

[0045] The substrate 1 is slidably connected to the Z-axis sliding plate 2 through a first driving part, ensuring that the Z-axis sliding plate 2 can slide relative to the substrate 1 along the Z-axis direction under the action of the first driving part; the Z-axis sliding plate 2 is slidably connected to the Y-axis sliding plate 3 through a second driving part, ensuring that the Y-axis sliding plate 3 can slide relative to the Z-axis sliding plate 2 along the Y-axis direction under the action of the second driving part; the Y-axis sliding plate 3 is slidably connected to the X-axis sliding rod 5 through a third driving part, ensuring that the X-axis sliding rod 5 can slide relative to the X-axis sliding plate along the Z-axis direction under the action of the third driving part;

[0046] The image processing module 7 comprises a controller 7.1 and a three-dimensional reconstruction unit 7.2, an image processing unit 7.3, a three-coordinate establishment unit 7.4, and an image display unit 7.5 connected to the controller 7.1;

[0047] The measuring ball is connected to the three-dimensional reconstruction unit 7.2, and is used to obtain the complete elements of the workpiece 4.6 to be measured to obtain a three-dimensional model. The image collector 6 is connected to the image processing unit 7.3, and is used to perform edge image conversion and sharpening processing on the original image obtained by the image collector 6. The image display unit 7.5 is connected to the three-coordinate establishment unit 7.4, and the image display unit 7.5 is used to display the established three-coordinate system and display the processed image. The controller 7.1 is at least used to control the movement of the first drive unit, the second drive unit, the third drive unit and the movable fixture assembly.

[0048] like Figure 2 As shown, the mobile fixture assembly includes a slider 4.1, a telescopic rod 4.2, a fixture 4.3 and a driving cylinder 4.5;

[0049] The rotating platform 4 is provided with three slide grooves 4.4, and the three slide grooves 4.4 are symmetrically arranged relative to the center of the rotating platform 4; the slider 4.1 is slidably connected with the slide grooves 4.4;

[0050] One end of the slider 4.1 is connected to the driving cylinder 4.5, and the other end is connected to the telescopic rod 4.2. The end of the telescopic rod 4.2 away from the slider 4.1 is provided with a clamp 4.3;

[0051] The driving cylinder 4.5 and the telescopic rod 4.2 are both connected to the controller 7.1 by signals;

[0052] The driving cylinder 4.5 controls the clamp 4.3 to move within the range of Q1, and the telescopic rod 4.2 controls the clamp 4.3 to move within the range of Q2. Q1 is the moving range of the output end of the driving cylinder 4.5, and Q2 is the extension range of the telescopic rod 4.2. Q1>Q2, Q1 range is preliminary movement, and Q2 range is precise movement.

[0053] For example, one of the driving cylinders 4.5 pushes a fixture 4.3 and controls the workpiece 4.6 to move a unit length; the controller 7.1 calculates the moving distances of the other two fixtures 4.3 through trigonometric functions and controls the other two driving cylinders 4.5 to drive the fixtures 4.3 to move. During this process, the length of the telescopic rod 4.2 is the initial length; then the elongation / shortening amount of the telescopic rod 4.2 is determined again according to the workpiece 4.6 to be measured after the movement, and the controller 7.1 controls a telescopic rod 4.2 to push a fixture 4.3 and controls the workpiece 4.6 to be measured to move within a smaller range; the controller 7.1 calculates the moving distances of the other two fixtures 4.3 through trigonometric functions and controls the other two telescopic rods 4.2 to drive the fixtures 4.3 to move.

[0054] In one embodiment of the present invention, a measuring platform is disposed at the center of the upper surface of the rotating platform 4 , and the measuring platform is mechanically fixedly connected to the rotating platform 4 .

[0055] Please continue to refer to Figure 3 In one embodiment of the present invention, the image processing module 7 further includes a feature point determination unit 7.6, which is used to determine the feature points of the three-dimensional model and obtain the coordinate information of the feature points according to the projection relationship between the three-dimensional model and the two-dimensional image and the key point information of the workpiece 4.6 to be measured. For example, if there is a convex or concave structure on a workpiece, the highest point or the lowest point of the convex or concave structure can be used as a key point, and this is used as a feature point to make it coincide with the origin of the three-dimensional coordinates.

[0056] The purpose of the present invention is to obtain the contour lines and feature point coordinates of the original image of the workpiece 4.6 to be measured, therefore, the original image needs to be processed, that is, the image processing unit 7.3 performs grayscale processing on the original image to obtain a grayscale image;

[0057] The controller 7.1 calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel;

[0058] The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

[0059] Embodiment 2:

[0060] This embodiment provides a measurement method of a three-dimensional coordinate measuring machine based on image processing, and the method uses the system of embodiment 1 and includes the following steps:

[0061] The workpiece 4.6 to be measured is placed on the rotating platform 4, and the original image of the workpiece is acquired by the image collector 6 and sent to the image processing unit 7.3;

[0062] The image processing unit 7.3 processes the original image and displays it in a three-coordinate system;

[0063] Adjust the position of the mobile fixture assembly so that a certain feature point of the processed image coincides with the coordinate origin of the three-coordinate system;

[0064] The workpiece 4.6 is measured using a measuring ball.

[0065] The processing of the original image by the image processing unit 7.3 includes edge image conversion and sharpening processing; specifically, the edge image conversion includes: the image processing unit 7.3 performs grayscale processing on the original image to obtain a grayscale image;

[0066] The controller 7.1 calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel;

[0067] The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

[0068] In the above, the movable fixture assembly is adjusted by coarse adjustment and fine adjustment so that a certain feature point of the processed image coincides with the coordinate origin of the three-coordinate system;

[0069] The coarse adjustment is as follows: according to the selected feature point coordinates, the vector value of the feature point from the three-coordinate origin is calculated, and the controller 7.1 controls a driving cylinder 4.5 to push a fixture 4.3 and thus controls the workpiece 4.6 to be measured to move within the range of Q1; the controller 7.1 calculates the moving distances of the other two fixtures 4.3 through trigonometric functions and controls the other two driving cylinders 4.5 to drive the fixtures 4.3 to move, and the length of the telescopic rod 4.2 in this process is the initial length;

[0070] The fine adjustment is as follows: the extension / contraction amount of the telescopic rod 4.2 is determined again according to the workpiece 4.6 to be measured after the movement, and the controller 7.1 controls one telescopic rod 4.2 to push one clamp 4.3 and thus controls the workpiece 4.6 to be measured to move within the range of Q2; the controller 7.1 calculates the moving distances of the other two clamps 4.3 through trigonometric functions and controls the other two telescopic rods 4.2 to drive the clamps to move; Q1>Q2.

[0071] The present invention can use the characteristic points and contour line coordinates as standards in batch workpiece measurement to quickly determine the three-dimensional parameters of the workpiece, and can determine whether the workpiece is qualified by the coordinates of other characteristic points.

[0072] The embodiments of the present method have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

Claims

1. A measuring system of a coordinate measuring machine based on image processing, characterized in that: It includes a three-coordinate measuring machine and an image processing module connected to the three-coordinate measuring machine; The three-coordinate measuring machine comprises a base plate, a Z-axis sliding plate is arranged on one side of the upper surface of the base plate, a rotating platform is arranged at the center of the upper surface of the base plate, the rotating platform is rotatably connected to the base plate, a Y-axis sliding plate is arranged on the Z-axis sliding plate, an X-axis sliding rod is arranged on the lower surface of the Y-axis sliding plate, and a measuring ball is arranged at the end of the Z-axis sliding rod; Three movable fixture assemblies are installed on the rotating platform, and the three movable fixture assemblies are symmetrically arranged relative to the center of the rotating platform; three image collectors are arranged on the substrate, and the three image collectors are located on the peripheral side of the rotating platform and are symmetrically arranged relative to the center of the rotating platform; The substrate is slidably connected to the Z-axis sliding plate via a first driving unit, the Z-axis sliding plate is slidably connected to the Y-axis sliding plate via a second driving unit, and the Y-axis sliding plate is slidably connected to the X-axis sliding rod via a third driving unit; The image processing module includes a controller and a three-dimensional reconstruction unit, an image processing unit, a three-coordinate establishment unit, and an image display unit connected to the controller; The three-dimensional reconstruction unit is connected to the measuring ball and is used to establish the complete elements of the workpiece to be measured and obtain a three-dimensional model. The image processing unit is connected to the image collector and is used to perform edge image conversion and sharpening processing on the original image acquired by the image collector. The image display unit is used to display the processed image in the established three-coordinate system. The controller is used to control the movement of the first driving unit, the second driving unit, the third driving unit and the mobile fixture assembly, and select the contour line and the feature point so that a certain feature point of the workpiece to be measured coincides with the origin of the three-dimensional coordinates. The mobile fixture assembly includes a slider, a telescopic rod, a fixture and a driving cylinder; Three slide grooves are installed on the rotating platform, and the three slide grooves are symmetrically arranged relative to the center of the rotating platform; the slide grooves are slidably connected to the slider; One end of the slider is connected to the driving cylinder, and the other end is connected to the telescopic rod, and a clamp is provided at one end of the telescopic rod away from the slider; The driving cylinder and the telescopic rod are both connected to the controller signal; The driving cylinder controls the clamp to move within the range of Q1, and the telescopic rod controls the clamp to move within the range of Q2, wherein Q1 is the moving range of the output end of the driving cylinder, and Q2 is the extension range of the telescopic rod, and Q1>Q2.

2. The measuring system of a three-dimensional coordinate measuring machine based on image processing according to claim 1, characterized in that: A measuring platform is provided at the center position of the upper surface of the rotating platform, and the measuring platform is fixedly connected to the rotating platform.

3. The measuring system of a three-dimensional coordinate measuring machine based on image processing according to claim 2, characterized in that: The image processing module also includes a feature point determination unit, which is used to determine the feature points of the three-dimensional model and obtain the coordinate information of the feature points according to the projection relationship between the three-dimensional model and the two-dimensional image and the key point information of the workpiece to be measured.

4. The measuring system of the three-dimensional coordinate measuring machine based on image processing according to claim 3 is characterized in that: The image processing unit performs grayscale processing on the original image to obtain a grayscale image; The controller calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel; The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

5. A measurement method of a three-dimensional coordinate measuring machine based on image processing, characterized in that: The method utilizes the system described in any one of claims 1 to 4; and comprises the following steps: The workpiece to be measured is placed on the rotating platform, and the original image of the workpiece is acquired by the image collector and sent to the image processing unit; After the image processing unit processes the original image, it displays it in a three-coordinate system; Adjust the position of the mobile fixture assembly so that a certain feature point of the processed image coincides with the coordinate origin of the three-coordinate system; Use the measuring ball to measure the workpiece to be measured; Adjust the mobile fixture assembly through coarse adjustment and fine adjustment so that a certain feature point of the processed image coincides with the coordinate origin of the three-coordinate system; The coarse adjustment is as follows: the vector value of the distance between the feature point and the origin of the three coordinates is calculated according to the coordinates of the selected feature point, and the controller controls a driving cylinder to push a fixture to control the workpiece to be measured to move within the range of Q1; the controller calculates the moving distance of the other two fixtures through trigonometric functions and controls the other two driving cylinders to drive the fixtures to move. In this process, the length of the telescopic rod is the initial length; The fine adjustment is as follows: the extension / contraction amount of the telescopic rod is determined again according to the workpiece to be measured after the movement, and the controller controls one telescopic rod to push one fixture to control the workpiece to be measured to move within the range of Q2; the controller calculates the moving distance of the other two fixtures through trigonometric functions and controls the other two telescopic rods to drive the fixtures to move; Said Q1>Q2.

6. The measuring method of a three-dimensional coordinate measuring machine based on image processing according to claim 5, characterized in that: The image processing unit processes the original image including edge image conversion and sharpening; The edge image conversion comprises: an image processing unit performs grayscale processing on the original image to obtain a grayscale image; The controller calculates the grayscale gradient of each pixel in the grayscale image, and determines whether it is greater than a preset grayscale gradient, and regards the pixel whose grayscale gradient is greater than the preset grayscale gradient as an edge pixel; The positional relationship of each edge pixel point and the gray gradient change relationship of each edge pixel point are obtained, a plurality of pixel point sets are determined, and the pixel points in each of the pixel point sets are connected to form an edge contour line; an edge image is obtained according to the plurality of edge contour lines.

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