Visual detection device and method for impact sample based on projection fringes

Abstract

The invention provides an impact sample visual detection device and method based on projection fringes, and the method employs a projection lamp to project fringes to the surface of a to-be-detected structure, and is used for measuring the size parameters perpendicular to a projection plane. Performing image acquisition on the to-be-measured structure by using the two-dimensional camera with the set acquisition parameters, and transmitting the acquired image information to an image processing unit through a data line; and the image processing unit is used for processing and analyzing the image information so as to obtain the three-dimensional size and notch angle parameters of the to-be-measured structure. The method is combined with a measurement method of projection fringes, the three-dimensional size parameters of the impact sample are measured through one two-dimensional image, the detection efficiency of the impact sample is effectively improved, the measurement precision is improved, and high-efficiency and high-precision measurement of the size and notch angle parameters of the impact sample is achieved.

Description

Technical Field

[0001] The invention relates to the technical field of machine vision three-dimensional detection, in particular to a device and method for visual detection of impact samples based on projection fringes. Background Art

[0002] The Charpy impact test has strict requirements on the geometric shape and size of the specimen, such as the depth, angle and root radius of the V-shaped or U-shaped notch. Slight changes in these parameters may affect the measurement results of subsequent impact tests. Therefore, the detection of impact specimen size and notch angle parameters is of extraordinary significance.

[0003] At present, the detection of impact specimens mainly relies on staff to measure with vernier calipers. This measurement method is cumbersome, and the manual measurement brings large operational errors. In addition to the manual measurement method, there is also a method of using an impact test notch projector for notch detection. This method uses the principle of optical magnification to image the specimen notch on the projection screen and compare it with the measurement sample to determine whether the notch is qualified. However, this method only measures the relevant parameters of the specimen notch, and does not measure the three-dimensional size parameters. In addition, the measurement equipment is expensive, the operation is cumbersome, and the measurement efficiency is low.

[0004] At the same time, with the development of visual technology, measurement methods based on machine vision are becoming more and more widely used. However, in common visual measurement methods, the camera needs to be calibrated and the calibration process is relatively cumbersome and complicated, and there is a problem of slow data processing speed. Summary of the invention

[0005] In view of this, the purpose of the present invention is to provide an impact specimen visual inspection device and method based on projection fringes, which greatly reduces the hardware cost, obtains the dimensional parameters perpendicular to the projection surface by projecting the fringe image, solves the problem that a two-dimensional image can only obtain dimensional parameters of two dimensions, and improves the data processing efficiency, thereby realizing efficient and high-precision measurement of three-dimensional size and notch angle parameters.

[0006] To achieve the above-mentioned purpose, the present invention adopts the following technical scheme: a visual inspection device for impact specimens based on projection stripes, comprising a projection lamp, a two-dimensional camera, a placement platform, a spectroscope, a data line and an image processing unit; the projection lamp projects sinusoidal stripes onto the surface of the impact specimen and the placement platform to measure the size parameters of the impact specimen perpendicular to the projection surface; the two-dimensional camera collects images of the projection surface of the impact specimen and the placement platform, and transmits the collected image information to the image processing unit via the data line; the image processing unit processes and analyzes the collected images to obtain the three-dimensional size and notch angle parameters of the impact specimen.

[0007] In a preferred embodiment, the projection lamp includes an LED light source and a stripe sheet, and the LED light source projects a stripe image onto the surface of the structure to be measured by irradiating the stripe sheet.

[0008] In a preferred embodiment, the two-dimensional camera includes an array sensor, an integrated circuit board, an imaging lens, a device interface and a power supply. The imaging range can be reduced according to the pixel area where the projection stripes are located to improve the sampling frame rate of the camera. When the two-dimensional camera collects the projection stripes, its imaging optical axis is perpendicular to the projection stripe plane, and the projection stripes are placed at the center of the two-dimensional camera image for imaging.

[0009] In a preferred embodiment, the projection direction of the projection lamp is 45° to the reflection surface of the beam splitter, and the projection light is reflected by the beam splitter and projected onto the surface of the impact sample and the surface of the placement platform. The projection image is a single-density projection fringe, and the density of the fringe is constant; when the distance between the projection surface and the projection lamp is different, the density of the projection fringe on the projection surface will also change accordingly. The characteristics of the fringe signal can accurately measure the distance between the projection surface and the reference surface, and the height size of the structure to be measured can be obtained by solving the projection fringe density on the structure to be measured.

[0010] The present invention also provides a method for visually inspecting impact specimens based on projection fringes, using the device for visually inspecting impact specimens based on projection fringes, comprising the following steps:

[0011] Step S1: Use a projector to project a fringe image onto the impact sample and the placement platform, set the acquisition parameters of the two-dimensional camera, set the installation position of the two-dimensional camera and fix it so that the projected fringe image is at the center of the two-dimensional sensor;

[0012] Step S2: Recording image information through a two-dimensional camera;

[0013] Step S3: The image signal in the two-dimensional camera is transmitted to the image processing unit, and the image processing module analyzes the image signal to extract the three-dimensional size and notch angle parameters of the impact specimen from the collected image.

[0014] In a preferred embodiment, the step S3 is specifically as follows:

[0015] Step S31: intercept the fringe signal projected onto the placement platform, perform calculations on the fringe signal, and obtain the fringe density as the reference fringe density, denoted as d r ;

[0016] Step S32: After the impact sample is placed at the designated position, the fringe signal projected onto the impact sample is intercepted and calculated through a program to obtain the fringe density, which is recorded as d i And the height dimension information of the impact specimen is obtained by calculating the formula;

[0017] Step S33: Perform image processing on the collected image to extract the contour information of the impact specimen, combine the measured height dimension information, and calculate the length and width of the impact specimen through machine vision algorithm, and at the same time obtain the angle parameter information of the notch.

[0018] In a preferred embodiment, the height of the impact specimen is calculated using the formula:

[0019]

[0020] Where H is the height of the structure, D is the imaging object distance of the imaging system, and d r and d i are the reference fringe density and the projected fringe density on the structure, respectively.

[0021] In a preferred embodiment, the length of the impact specimen is calculated using the formula:

[0022]

[0023] Where L is the length of the structure, F is the focal length of the camera lens, and N L It is the number of pixels occupied by the structure contour along the length direction in the image.

[0024] In a preferred embodiment, the width of the impact specimen is calculated by the following formula:

[0025]

[0026] Where W is the width of the structure, F is the focal length of the camera lens, and N W It is the number of pixels occupied by the structural contour in the image along the width direction.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention adopts a structure that combines machine vision projection stripes with an image processing system to improve detection efficiency.

[0029] The present invention realizes the measurement of the three-dimensional size and notch angle parameters of the structure to be measured, effectively reduces the hardware cost, and improves the efficiency and accuracy of the measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 1 is a schematic diagram of the device structure of an embodiment of the present invention; in the figure, 1 is a two-dimensional camera, 2 is a spectroscope, 3 is a structure to be measured, 4 is a placement platform, 5 is a data line, 6 is a computer, and 7 is a stripe projection lamp.

[0031] Figure 2is the height measurement principle of the embodiment of the present invention; wherein F is the focal length of the two-dimensional camera, D is the imaging distance of the placement platform, and D i is the imaging distance of the structure to be measured, and H is the height of the structure to be measured.

[0032] Figure 3 It is an image signal collected by the camera in the simulation experiment of the embodiment of the present invention. It can be seen from the figure that the density of the projection stripes on the placement platform is different from the density of the projection stripes on the structure to be tested.

[0033] Figure 4 It is a fringe density variation curve obtained after the fringe signal is calculated in the embodiment of the present invention.

[0034] Figure 5 After simulating samples of different heights in an embodiment of the present invention, the obtained stripe density and height dimension data are subjected to curve fitting, and the obtained fitting curve and residual graph are obtained.

[0035] Figure 6 This is a result diagram of image processing of an image signal by an embodiment of the present invention. The image processing program realizes the recognition and selection of the structure to be measured, and at the same time obtains the pixel size of the structure to be measured along the length and width directions on the image through image calculation. DETAILED DESCRIPTION

[0036] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0037] It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present application belongs.

[0038] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or their combinations.

[0039] Please refer to Figure 1-6 The present invention provides a visual inspection device for impact specimens based on projection fringes, such as Figure 1, comprising a two-dimensional camera (1), a beam splitter (2), a structure to be measured (3), a placement platform (4), a data line (5), a computer (6), and a stripe projection lamp (7). The stripe projection lamp projects sinusoidal stripes on the surface of the structure to be measured (3) and the placement platform (4) to measure the size parameters of the structure to be measured perpendicular to the projection surface. The two-dimensional camera (1) is used to continuously capture images of the structure to be measured (3) and the placement platform (4) after the projection is completed, and transmit the image signal to the computer (6) through the data line (5) for storage and processing. The computer (6) is used to control the signal acquisition of the two-dimensional camera, and the computer (6) is built with an image processing software module, which can pre-process the image signal transmitted to the computer (6) and perform relevant calculations to obtain the three-dimensional size and notch angle parameters of the structure to be measured (3).

[0040] In this embodiment, reference Figure 2-Figure 5 ,like Figure 2 As shown in FIG. 1 , when the structure to be measured reaches the projection area, the fringe density at the center line of the fringe image in the width direction projected onto the surface of the structure to be measured is different from the fringe density at the center line of the fringe image in the width direction of the surface of the placement plane. The fringe signal is processed and analyzed by a computer program, and the following is obtained: Figure 3 The fringe density analysis diagram shown in the figure is based on the principle Figure 4 As shown in the figure, D is the imaging object distance between the imaging system and the placement platform, D i is the imaging object distance between the imaging system and the structure to be measured, F is the focal length of the imaging system, and H is the height of the structure to be measured. The height of the structure to be measured is calculated based on the density difference of the projection surface fringes. The mathematical calculation formula for the height dimension is:

[0041]

[0042] Where H is the height of the structure, D is the imaging object distance between the imaging system and the placement platform, and d r With d i are the reference fringe density and the projected fringe density on the structure, respectively.

[0043] By projecting the structure to be tested at different heights, using a simulated camera to collect images of the surface of the structure to be tested, processing the obtained images to obtain the fringe density information in the images, analyzing the obtained multiple sets of data and fitting the curves, the following results are obtained: Figure 5 The fitting curve and residual diagram shown in the figure show that the stripe density on the surface of the structure to be measured is linearly related to the height size of the structure.

[0044] In this embodiment, reference Figure 6After obtaining the height information of the structure, the distance between the surface of the structure to be tested and the two-dimensional camera can be obtained. After processing the image information using the machine vision algorithm, the structure to be tested can be identified and selected, and the pixel size information of the structure to be tested in the image can be output, such as Figure 6 Combined with the height dimension information of the structure to be tested, the length information and width information of the structure to be tested are obtained through the following formula:

[0045]

[0046] Where L is the length of the structure, F is the focal length of the camera lens, and N L is the number of pixels occupied by the structure contour in the image along the length direction, W is the width of the structure, N W It is the number of pixels occupied by the structural contour in the image along the width direction.

Claims

1. A visual inspection device for impact specimens based on projection fringes, characterized in that: It includes a projection lamp, a two-dimensional camera, a placement platform, a spectroscope, a data line and an image processing unit; the projection lamp projects sinusoidal stripes onto the surface of the impact specimen and the placement platform to measure the size parameters of the impact specimen perpendicular to the projection surface; the two-dimensional camera collects images of the impact specimen and the projection surface of the placement platform, and transmits the collected image information to the image processing unit via the data line; the image processing unit processes and analyzes the collected images to obtain the three-dimensional size and notch angle parameters of the impact specimen.

2. The device for visually inspecting impact specimens based on projection fringes according to claim 1, characterized in that: The projection lamp comprises an LED light source and a stripe sheet. The LED light source projects a stripe image onto the surface of the structure to be measured by irradiating the stripe sheet.

3. The device for visually inspecting impact specimens based on projection fringes according to claim 1, characterized in that: The two-dimensional camera includes an array sensor, an integrated circuit board, an imaging lens, a device interface and a power supply.

4. The device for visually inspecting impact specimens based on projection fringes according to claim 1, characterized in that: The projection direction of the projection lamp is 45 degrees to the reflection surface of the beam splitter. The projection light is reflected by the beam splitter and projected onto the surface of the impact sample and the surface of the placement platform.

5. A method for visual inspection of impact specimens based on projection fringes, characterized in that The device for visually inspecting impact specimens based on projection fringes according to any one of claims 1 to 4 comprises the following steps: Step S1: Use a projector to project a fringe image onto the impact sample and the placement platform, set the acquisition parameters of the two-dimensional camera, set the installation position of the two-dimensional camera and fix it so that the projected fringe image is at the center of the two-dimensional sensor; Step S2: Recording image information through a two-dimensional camera; Step S3: The image signal in the two-dimensional camera is transmitted to the image processing unit, and the image processing module analyzes the image signal to extract the three-dimensional size and notch angle parameters of the impact specimen from the collected image.

6. The method for visual inspection of impact specimens based on projection fringes according to claim 5, characterized in that: The step S3 is specifically as follows: Step S31: intercept the fringe signal projected onto the placement platform, perform calculations on the fringe signal, and obtain the fringe density as the reference fringe density, denoted as d r ; Step S32: After the impact sample is placed at the designated position, the fringe signal projected onto the impact sample is intercepted and calculated through a program to obtain the fringe density, which is recorded as d i And the height dimension information of the impact specimen is obtained by calculating the formula; Step S33: Perform image processing on the collected image to extract the contour information of the impact specimen, combine the measured height dimension information, and calculate the length and width of the impact specimen through machine vision algorithm, and at the same time obtain the angle parameter information of the notch.

7. The method for visual inspection of impact specimens based on projection fringes according to claim 6, characterized in that: The dimension calculation formula of the height of the impact specimen is: Where H is the height of the structure, D is the imaging object distance of the imaging system, and d r and d i are the reference fringe density and the projected fringe density on the structure, respectively.

8. The method for visual inspection of impact specimens based on projection fringes according to claim 6, characterized in that: The dimension calculation formula of the length of the impact specimen is: Where L is the length of the structure, F is the focal length of the camera lens, and N L It is the number of pixels occupied by the structure contour along the length direction in the image.

9. The method for visual inspection of impact specimens based on projection fringes according to claim 6, characterized in that: The dimension calculation formula of the width of the impact specimen is: Where W is the width of the structure, F is the focal length of the camera lens, and N W It is the number of pixels occupied by the structural contour in the image along the width direction.

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