A projection fringe based visual detection device and method for impact specimen

Abstract

The application provides a kind of impact sample visual detection device and method based on projection stripe, this scheme utilizes projection lamp to project stripe to the surface of structure to be measured, for measuring the size parameter perpendicular to projection plane;Image acquisition is carried out to the structure to be measured by two-dimensional camera with set acquisition parameter, and the image information obtained by acquisition is transmitted to image processing unit by data line;Image processing unit processes and analyzes image information to obtain three-dimensional size and gap angle parameter of structure to be measured.The application combines the measurement method of projection stripe, realizes the measurement of three-dimensional size parameter of impact sample through a two-dimensional image, effectively improves the detection efficiency of impact sample, improves the measurement precision, realizes the efficient and high-precision measurement of size, gap angle parameter of impact sample.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of machine vision three-dimensional detection, and particularly relates to a projection-stripe-based impact specimen visual detection device and method. BACKGROUND

[0002] Charpy impact test has strict requirements on the geometric shape and size of a specimen, such as the depth, angle and root radius of a V-shaped notch or a U-shaped notch, and a slight change in these parameters can affect the measurement result of subsequent impact test, so the impact specimen size and notch angle parameter detection has extraordinary significance.

[0003] At present, the detection of an impact specimen mainly depends on the measurement of a worker using a vernier caliper, and such a measurement method is relatively cumbersome, and the operation error caused by manual measurement is large. In addition to the manual measurement method, there is also a method of using an impact test notch projector to detect a notch, which uses the optical magnification principle to image the specimen notch on a projection screen and compares it with a measurement template to determine whether the notch is qualified. However, such a method only measures the related parameters of the specimen notch, and does not measure the three-dimensional size parameters, and the measurement device is expensive, the operation is cumbersome, and the measurement efficiency is low.

[0004] Meanwhile, with the development of visual technology, the measurement method based on machine vision is applied more and more widely, but in the common visual measurement method, the camera needs to be calibrated and the calibration process is relatively cumbersome and complex, and there is a problem of slow data processing speed. SUMMARY

[0005] Therefore, the present application aims to provide a projection-stripe-based impact specimen visual detection device and method, which greatly reduces the hardware cost, obtains the size parameters perpendicular to the projection plane through the projection of a stripe image, solves the problem that one two-dimensional image can only obtain two-dimensional size parameters, and improves the data processing efficiency, and realizes efficient and high-precision measurement of three-dimensional size and notch angle parameters.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solution: a projection-stripe-based impact specimen visual detection device, comprising a projection lamp, a two-dimensional camera, a placing platform, a beam splitter, a data line and an image processing unit; the projection lamp projects a sinusoidal stripe on the surface of the impact specimen and the placing platform to measure the size parameters of the impact specimen perpendicular to the projection plane; the two-dimensional camera collects images of the projection surface of the impact specimen and the placing platform, and transmits the collected image information to the image processing unit through the data line; and 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 comprises an LED light source and a striped sheet, and the LED light source projects a striped image to the surface of the structure to be measured by irradiating the striped sheet.

[0008] In a preferred embodiment, the two-dimensional camera comprises a plane 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 of the projected stripes to improve the sampling frame rate of the camera. When the two-dimensional camera collects the projected stripes, the imaging optical axis is perpendicular to the plane of the projected stripes, and the projected stripes are imaged at the center position of the two-dimensional camera image.

[0009] In a preferred embodiment, the projection direction of the projection lamp is 45° to the reflecting surface of the beam splitter, and the projection light is reflected by the beam splitter to the surface of the impact sample and the surface of the placement platform. The projected image is a single-density projected stripe, and the density of the stripe is constant. When the distance between the projection surface and the projection lamp changes, the density of the projected stripe on the projection surface also changes. The distance between the projection surface and the reference surface can be accurately measured by using the characteristics of the stripe signal, and the height size of the structure to be measured can be obtained by solving the density of the projected stripe on the structure to be measured.

[0010] The application also provides an impact sample visual detection method based on projected stripes, which adopts the impact sample visual detection device based on projected stripes, and comprises the following steps:

[0011] Step S1: projecting a striped image to the impact sample and the placement platform by using the projection lamp, setting the collection parameters of the two-dimensional camera, setting the installation position of the two-dimensional camera and fixing it, and imaging the projected stripe at the center position of the two-dimensional sensor;

[0012] Step S2: recording the image information by using the two-dimensional camera;

[0013] Step S3: transmitting the image signal in the two-dimensional camera to the image processing unit, analyzing by the image processing module, and extracting the three-dimensional size and the notch angle parameter of the impact sample from the collected image.

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

[0015] Step S31: intercepting the stripe signal projected on the surface of the placement platform, operating the stripe signal, obtaining the stripe density as the reference stripe density, and denoted as d r ;

[0016] Step S32: after the impact sample is placed at the specified position, intercepting the stripe signal projected on the impact sample and operating it by using the program, obtaining the stripe density, denoted as d i , and calculating the height size information of the impact sample by using the formula.

[0017] Step S33: image processing is performed on the collected image, profile information of the impact sample is extracted, height dimension information measured is combined, length and width of the impact sample are obtained through machine vision algorithm operation in combination with angle parameter information of the notch.

[0018] In a preferred embodiment, the height dimension calculation formula of the impact sample is:

[0019]

[0020] Wherein H is the height dimension of the structure, D is the imaging object distance of the imaging system, 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 dimension calculation formula of the impact sample is:

[0022]

[0023] Wherein L is the length dimension of the structure, F is the camera lens focal length, N L is the pixel point number of the structure profile in the image along the length direction.

[0024] In a preferred embodiment, the width dimension calculation formula of the impact sample is:

[0025]

[0026] Wherein W is the width dimension of the structure, F is the camera lens focal length, N W is the pixel point number of the structure profile in the image along the width direction.

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

[0028] The present application adopts the structure of machine vision projection fringe combined with image processing system, which improves the detection efficiency.

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

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

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

[0032] Figure 3 is the image signal collected by the camera in the simulation experiment of the embodiment of the present application, and it can be seen from the figure that the density of the projection stripe on the placing platform is different from the density of the projection stripe on the structure to be measured.

[0033] Figure 4 is the stripe density change curve obtained after the stripe signal is operated by the embodiment of the present application.

[0034] Figure 5 is the fitting curve and residual plot obtained by fitting the stripe density and height dimension data obtained after the simulation of the samples with different heights by the embodiment of the present application.

[0035] Figure 6 is the result image of the image processing of the image signal by the embodiment of the present application, the image processing program realizes the recognition and frame selection of the structure to be measured, and the pixel size of the structure to be measured in the length direction and the width direction on the image is obtained through image operation. DETAILED DESCRIPTION

[0036] The present application will be further described below in combination with the drawings and embodiments.

[0037] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0038] It should be noted that the terms used herein are only for the purpose of describing the specific embodiments and are not intended to limit the exemplary embodiments according to the present application; as used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise, and furthermore, it should be understood that when the terms "comprise" and / or "include" are used in the specification, there is a feature, step, operation, device, component and / or combination thereof.

[0039] Please refer to Figures 1-6 The present application provides a projection stripe-based impact sample visual detection device, such as Figure 1, including two-dimensional camera (1), spectroscope (2), structure to be measured (3), placing platform (4), data line (5), computer (6), stripe projection lamp (7). The stripe projection lamp projects sinusoidal stripes on the surface of the structure to be measured (3) and the placing platform (4) to measure the size parameter of the structure perpendicular to the projection plane. The two-dimensional camera (1) is used to continuously take images of the structure to be measured (3) and the placing platform (4) after projection, and the image signals are transmitted 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 image processing software module is built in the computer (6), which can preprocess the image signals transmitted to the computer (6) and perform related calculations to obtain the three-dimensional size and gap angle parameters of the structure to be measured (3).

[0040] In the embodiment, reference is made to Figures 2-5 As shown in Figure 2 , when the structure to be measured reaches the projection area, the stripe density at the center line of the stripe image in the width direction of the surface of the structure to be measured is different from the stripe density at the center line of the stripe image in the width direction of the surface of the placing platform. The stripe signals are processed and analyzed by the computer program to obtain the stripe density analysis diagram as shown in Figure 3 , and the principle is as shown in Figure 4 , in which D is the imaging object distance between the imaging system and the placing 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 size of the structure to be measured. The height of the structure to be measured is calculated according to the density difference of the projection surface stripe, and the mathematical calculation formula of the height size is:

[0041]

[0042] In which H is the height size of the structure, D is the imaging object distance between the imaging system and the placing platform, d r and d i are the reference stripe density and the projection stripe density on the structure respectively.

[0043] The projection simulation is carried out on the structures to be measured with different heights, the surface of the structure to be measured is imaged by using the simulation camera, the obtained images are processed, the stripe density information in the images is obtained, a plurality of groups of data are analyzed and fitted, and the fitting curve and the residual diagram as shown in Figure 5 are obtained. As can be seen from the diagram, the stripe density on the surface of the structure to be measured is linearly related to the height size of the structure.

[0044] In the embodiment, reference is made to Figure 6After obtaining the height dimension information of the structure, the distance between the surface of the structure to be measured and the two-dimensional camera can be obtained. After image processing of the image information using a machine vision algorithm, the recognition and framing of the structure to be measured are realized, and the pixel size information of the structure to be measured on the image is output, as shown in FIG. 8. Figure 6 In combination with the height dimension information of the structure to be measured, the length information and the width information of the structure to be measured are obtained through the following formula:

[0045]

[0046] Wherein L is the length dimension of the structure, F is the focal length of the camera lens, N L is the number of pixel points occupied by the structure profile in the image along the length direction, W is the width dimension of the structure, and N W is the number of pixel points occupied by the structure profile in the image along the width direction.

Claims

1. A visual inspection device for impact specimens based on projected fringes, characterized in that, The system includes a projection lamp, a two-dimensional camera, a placement platform, a beam splitter, a data cable, and an image processing unit. The projection lamp projects sinusoidal fringes onto the surfaces of the impact specimen and the placement platform to measure the dimensional parameters of the impact specimen perpendicular to the projection plane. The two-dimensional camera acquires images of the projection surfaces of the impact specimen and the placement platform and transmits the acquired image information to the image processing unit via the data cable. The image processing unit processes and analyzes the acquired images to obtain the three-dimensional dimensions and notch angle parameters of the impact specimen. The visual inspection method for impact specimens based on projected fringes includes the following steps: Step S1: Project the stripe image onto the impact sample and the placement platform using a projector lamp, 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 stripes are imaged at the center position of the two-dimensional sensor. Step S2: Record image information using a 2D camera; Step S3: The image signal from the two-dimensional camera is transmitted to the image processing unit, where it is analyzed by the image processing module to extract the three-dimensional dimensions and notch angle parameters of the impact specimen from the acquired image. Step S3 specifically involves: Step S31: Extract the fringe signal projected onto the placement platform, perform calculations on the fringe signal, and use the obtained fringe density as the reference fringe density, denoted as... ; Step S32: After the impact specimen is placed in the designated position, the fringe signal projected onto the impact specimen is captured and calculated by the program to obtain the fringe density, which is denoted as... The height and dimensions of the impact specimen are calculated using a formula. Step S33: Perform image processing on the acquired image to extract the contour information of the impact specimen. Combined with the measured height dimension information, calculate the length and width of the impact specimen through machine vision algorithm, and obtain the angle parameter information of the notch at the same time.

2. The visual inspection device for impact specimens based on projected fringes according to claim 1, characterized in that, The projection lamp includes an LED light source and a striped sheet. The LED light source projects a striped image onto the surface of the structure under test by illuminating the striped sheet.

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

4. The visual inspection device for impact specimens based on projected fringes according to claim 1, characterized in that, The projection direction of the projection lamp is at a 45° angle to the reflective surface of the beam splitter. The projected light is reflected by the beam splitter and projected onto the surface of the impact sample and the surface of the placement platform.

5. The visual inspection device for impact specimens based on projected fringes according to claim 1, characterized in that, The formula for calculating the height of the impact specimen is as follows: Where H is the height dimension of the structure, and D is the imaging object distance of the imaging system. and These are the reference fringe density and the projected fringe density on the structure, respectively.

6. The visual inspection device for impact specimens based on projected fringes according to claim 1, characterized in that, The formula for calculating the length of the impact specimen is as follows: Where L is the length of the structure, and F is the focal length of the camera lens. This represents the number of pixels the structural outline occupies along the length of the image.

7. The visual inspection device for impact specimens based on projected fringes according to claim 1, characterized in that, The formula for calculating the width of the impact specimen is as follows: Where W is the width of the structure and F is the focal length of the camera lens. This represents the number of pixels the structural outline occupies along the width direction in the image.

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