High-precision position measurement method based on laser projection imaging

Abstract

A high-precision position measurement method based on laser projection imaging comprises the steps that red and green laser emitters are arranged to form a detection area, the frame rate of a line imaging camera is adjusted, after exposure, the line imaging camera is controlled to start a continuous shooting mode, and then measured objects pass through shooting areas on a curtain one by one; the method comprises the following steps: primarily selecting images acquired by a line imaging camera, and respectively extracting red and green colors of each image to obtain monochromatic images; coordinate extraction is carried out on the monochromatic images to obtain corresponding coordinate data; and finally, performing coordinate calculation through a projection algorithm to generate relative coordinates of each object. According to the invention, the projected image is calculated, so that the problem of incapability of collection or insufficient precision caused by the influence of ambient brightness and the like can be overcome. Meanwhile, the high-frame-rate camera is adopted, and the measuring device is relatively simple in structure and low in cost.

Description

Technical Field

[0001] This invention relates to a technology in the field of laser projection and position calculation, specifically a position measurement method for high-speed moving micro-objects based on laser projection imaging with an accuracy of 0.001 mm. Background Technology

[0002] In testing moving objects, accurate position measurement is crucial. Current position calculation methods primarily rely on binocular cameras to capture images of the object and then use algorithms for localization. However, if ambient lighting is insufficient, an image of the object itself cannot be obtained. Furthermore, when using traditional cameras to photograph fast-moving objects, long exposure times or insufficient frame rates can result in motion blur and ghosting. These measurement methods suffer from insufficient accuracy, limited versatility in different working environments, and inability to measure fast-moving or minute objects. High-precision position measurement platforms used in experiments often employ complex designs, primarily designed for scanning the positions of various parts of large objects, and are similarly unsuitable for fast-moving, minute objects. Summary of the Invention

[0003] This invention addresses the problem of motion blur or trailing artifacts produced by existing cameras when capturing images of fast-moving objects. It proposes a high-precision position measurement method based on laser projection imaging. This method uses dual-color RGB light for projection, and by calculating the projected image, it overcomes the problems of insufficient accuracy or inability to acquire data due to factors such as ambient brightness. Furthermore, it employs a high-frame-rate camera, resulting in a relatively simple and low-cost measurement device structure.

[0004] This invention is achieved through the following technical solution:

[0005] This invention relates to a high-precision position measurement method based on laser projection imaging. A detection area is formed by setting up red and green laser emitters. After adjusting the frame rate and exposure of a line imaging camera, the camera is controlled to enter continuous shooting mode, allowing the measured object to pass through the shooting area on a screen one by one. After initial selection of the images acquired by the line imaging camera, red and green colors are extracted from each image to obtain monochrome images. Coordinates are then extracted from each monochrome image to obtain corresponding coordinate data. Finally, a projection algorithm is used to calculate the coordinates and generate the relative coordinates of each object.

[0006] The detection area refers to the area formed by the intersection of two linear laser beams from the red and green lasers, ensuring that objects leave clear shadows when they pass through.

[0007] The line imaging camera described has a high frame rate and high resolution, and is able to capture the motion trajectory of objects.

[0008] The screen is made of a material with appropriate light-diffusing properties to ensure that the shadows generated by the laser are evenly distributed.

[0009] The laser emitter and line imaging camera are preferably controlled and coordinated by a computer.

[0010] The relative coordinates of each object are as follows: Where x1,y1 and x2,y2 are the two-dimensional coordinates of the two laser sources, and m1,m2 are the ray slopes of the objects illuminated by the two laser sources to the projection, which are obtained by the two-dimensional coordinates of the two laser sources and the corresponding projection coordinates.

[0011] Preferably, the relative coordinates of each object, after being programmed in Python and images are acquired by an online imaging camera, can be analyzed frame by frame to determine whether there is a projectile crossing event and to accurately extract the center position of the passing particles. Technical effect

[0012] This invention uses laser projection for measurement. Under the premise that the laser parameters remain unchanged, the measured image is the same under any environment and time, which makes the platform less demanding on the external environment.

[0013] This invention uses two colors of RGB lasers for comparative analysis, thereby increasing the system's detection area and reducing the configuration difficulty of laser line projection. Compared with existing monochromatic laser detection technology, the detection area of ​​this invention is significantly larger than that of monochromatic lasers, and when measuring a group of projectiles with a diameter of 5mm and a speed of 2m / s or more, the calculation accuracy reaches 0.001mm. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the invention;

[0015] Figure 2 This is a schematic diagram of a scenario for an example embodiment;

[0016] Figure 3 This is a physical image of an example;

[0017] Figure 4 This is a comparison chart of the detection areas of monochromatic laser and dual-color laser;

[0018] Figure 5 (a)-(c) are schematic diagrams of image acquisition in the embodiments;

[0019] Figure 6 The example shows the shadow jitter corresponding to random errors. Detailed Implementation

[0020] like Figure 1As shown, this embodiment relates to a method for measuring the position of a high-speed micro-object based on laser projection imaging, including:

[0021] Step 1: Adjust the relative positions of the red and green laser emitters to ensure that both can illuminate the area being measured, while achieving the ideal deflection angle and coordinates, which will facilitate subsequent calculations.

[0022] The two line lasers need to be properly positioned to ensure accurate coverage of the detection area. The parameters of the two lasers currently used are wavelengths of 650nm and 532nm, with an output power of 50mW.

[0023] Step two: After adjusting the frame rate and exposure of the high frame rate camera, control the high frame rate camera to start continuous shooting mode.

[0024] The high frame rate camera is set to a frame rate of 28K frames per second and a resolution of 4096 pixels to capture the shadows left on the screen after a physical object passes through a line laser plane. Considering that the system's sampling interval can reach 10μs, particles with a speed of up to 500m / s can be easily captured if the particle length is around 5mm.

[0025] Step 3, as Figure 3 As shown, the objects to be measured are made to pass through the shooting angle range of the high frame rate camera one by one, which is the area to be measured.

[0026] Step four: After initial selection of images captured by the high frame rate camera, extract red and green colors from each image to obtain monochrome images; then extract coordinates from each monochrome image to obtain corresponding coordinate data; finally, calculate the coordinates using a projection algorithm to generate the relative coordinates of each object, specifically: using the laser coordinates L1(x1,y1) and L2(x2,y2) and the projected coordinates S1(x...) obtained from the test. S1 ,y S1 ) and S2(x S2 ,y S2 ), calculate and Finally passed The position coordinates of the measured object can then be calculated.

[0027] Through specific practical experiments, a set of tungsten projectiles with a diameter of 5mm were allowed to fall freely from a height of 1m with an initial velocity of 2m / s. The coordinates of the projectiles as they passed through the device were measured near the ground using this method. The experimental data obtained are shown in Table 1.

[0028] Table 1

[0029] The experimental data in the table show that the measurement accuracy of this method can reach 0.001 mm. Furthermore, it can effectively measure the position of tiny, high-speed moving objects.

[0030] like Figure 4 The figure shows a comparison of the detection areas of monochromatic laser and dual-color laser. It can be seen that the dual-color laser used in this method can detect a larger range than the monochromatic laser.

[0031] like Figure 5 As shown in (a)-(c), the images are, in order, the original images of the moving object passing through the detection area captured by the high frame rate camera, and the images of red (R channel) and green (G channel) lasers projected onto the screen using this method.

[0032] like Figure 6 The image shows the shadow center of gravity jitter caused by pixel jitter error and acquisition stability error. Since dual-pixel merging was used, the jitter unit value is 2 pixels. Considering the actual pixel size used in the measurement is 8μm, the system jitter is less than 1.6 pixels within 8 minutes. Calculation results show that the fluctuation in X and Y positions is less than two pixels. The deviation in XY coordinates is much less than 0.1mm. Statistical analysis was performed to further quantify the system's accuracy, yielding a standard deviation σ = 0.006mm in 8 minutes of measurement.

[0033] In summary, this invention solves the problem of insufficient data acquisition or inaccurate accuracy caused by factors such as ambient brightness in existing technologies, and obtains high-precision location results in a fast and simple manner.

[0034] The above-described specific implementations can be partially adjusted by those skilled in the art in different ways without departing from the principles and purpose of the present invention. The scope of protection of the present invention is defined by the claims and is not limited to the above-described specific implementations. All implementation schemes within the scope of the claims are bound by the present invention.

Claims

1. A high-precision position measurement method based on laser projection imaging, characterized in that, Red and green laser emitters are set up to form a detection area. After adjusting the frame rate and exposure of the line imaging camera, the line imaging camera is controlled to start continuous shooting mode, so that the objects to be measured pass through the shooting area on the screen one by one. After the images captured by the line imaging camera are initially selected, the red and green colors of each image are extracted separately to obtain a monochrome image. Then, the coordinates of the monochrome images are extracted to obtain the corresponding coordinate data. Finally, the coordinates are calculated by the projection algorithm to generate the relative coordinates of each object.

2. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The detection area refers to the area formed by the intersection of two linear laser beams from the red and green lasers, ensuring that objects leave clear shadows when they pass through.

3. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The line imaging camera described has a high frame rate and high resolution, and is able to capture the motion trajectory of objects.

4. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The screen is made of a material with appropriate light-diffusing properties to ensure that the shadows generated by the laser are evenly distributed.

5. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The laser emitter and line imaging camera are preferably controlled and coordinated by a computer.

6. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The relative coordinates of each object are as follows: Where x1,y1 and x2,y2 are the two-dimensional coordinates of the two laser sources, and m1,m2 are the ray slopes of the objects illuminated by the two laser sources to the projection, which are obtained by the two-dimensional coordinates of the two laser sources and the corresponding projection coordinates.

7. The high-precision position measurement method based on laser projection imaging according to claim 1, characterized in that, The relative coordinates of each object, after being programmed in Python and images acquired by an online imaging camera, can be analyzed frame by frame to determine whether there is a projectile crossing event and accurately extract the center position of the passing particles.

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