CN117110642A - Glass plane speed measuring method based on binocular telecentric lens - Google Patents

Abstract

The application discloses a glass plane speed measurement method based on a binocular telecentric lens, which comprises the following steps: s1, placing the device in the moving direction of the surface of the glass so that the lens is perpendicular to the side surface of the glass; s2, adjusting the distance between the lens and the side face of the glass; s3, initializing two cameras and setting corresponding acquisition parameters. S4, starting the device, so that the lower edge of the glass sequentially appears from the upper lens and the lower lens. The upper lens detects whether the glass enters the visual field in real time, and if so, the upper camera and the lower camera respectively take two pictures according to a fixed time interval. S5, processing and calculating the 2 pictures obtained by shooting to obtain the position of the lower edge of the glass in the picture, and calculating the accurate time interval of the two pictures. And S6, calculating the moving distance and time of the glass to obtain the moving speed of the glass. The application has higher measurement precision, lower environmental requirement and can maintain high-precision measurement for a long time.

Description

A glass plane speed measurement method based on binocular telecentric lens

Technical field

The invention relates to the field of machine vision technology, and specifically refers to a glass plane speed measurement method based on a binocular telecentric lens.

Background technique

In actual industrial scenarios, it is necessary to measure the moving speed of transparent objects such as glass. Common speed measurement methods use binocular vision, laser ranging, etc. to measure distance, count the time required for formation, and then calculate the speed. Binocular ranging mainly uses two fixed-distance monocular ordinary lenses to calculate the difference in field of view of the same object in two pictures and then estimate the distance. The edges of transparent objects such as glass are often not obvious enough, and the field of view difference between the two pictures in binocular vision is very weak and difficult to calculate. In order to enhance the edge characteristics of the glass, an auxiliary light source can be used to illuminate the glass to increase the brightness, but the imaging results are related to the ambient lighting. After the glass position changes, the imaging effect under optimal lighting cannot be maintained, so the movement range available for measurement is small and difficult. Laser ranging mainly measures distance by measuring the time it takes for laser, ultrasonic, etc. to return to the source point after contacting the surface of the object. Its accuracy is very high. However, in industrial scenarios, the glass on the production line generally has a high temperature of about 300 degrees Celsius, and the ambient humidity is high. The above-mentioned environmental factors will affect the reflection of laser and ultrasonic waves, making ranging solutions based on light reflected from the object surface unable to be applied in industrial scenarios. The above two solutions cannot guarantee the continuous stability of measurement results for transparent objects such as glass in industrial scenarios with harsh environmental conditions, and have high environmental requirements and are not versatile. A telecentric lens is a camera lens with a special optical design. Its main feature is that the magnification of the image obtained does not change within a certain object distance range. The technical characteristics of the telecentric lens with no perspective error and nearly zero distortion enable visual measurement and inspection to achieve high accuracy.

Use a telecentric lens to take multiple shots of the moving glass plane. After measuring the position of the lower surface of the glass, the movement of the glass between two adjacent shots can be obtained by calculating the resolution of the image and the field of view of the telecentric lens. distance. The ultra-low distortion (maximum image square distortion does not exceed 0.1%) and high telecentricity of the telecentric lens ensure that the measurement results obtained through the image still maintain high accuracy. However, the field of view of the telecentric lens is smaller than that of an ordinary lens. For example, the field of view of the telecentric lens used in the present invention is about 5cm*3cm. For scenes with fast movement speed and high error requirements, a single telecentric lens cannot meet the target requirements.

The present invention proposes the solution of using a binocular telecentric lens to measure the velocity of a glass plane. The distance between the two binocular lenses can be set to a fixed value, which depends on the moving speed of the target object and the actual deployment equipment needs. By lengthening the interval between two shots, the measured speed error is also smaller.

Contents of the invention

In view of the above technical problems existing in the prior art, the present invention provides a glass plane speed measurement method based on a binocular telecentric lens. Compared with general ranging solutions, the present invention has higher measurement accuracy, has lower environmental requirements, and can maintain high-precision measurements for a long time.

In order to solve the above technical problems, the technical solution of the present invention is:

A glass plane speed measurement method based on binocular telecentric lenses, including the following steps:

S1. Build an image capturing device. The image capturing device includes two cameras. The telecentric lenses of the two cameras are marked as α and β respectively. The two cameras are located on one side of the glass plane to be measured, and the telecentric lenses of the two cameras are located on one side of the glass plane to be measured. The center lens is perpendicular to the side of the glass plane to be tested;

S2. Set the shooting time interval T of the two cameras according to the moving speed of the glass plane to be measured and the distance between the two cameras. The distance d between the two telecentric lenses is a fixed known value;

S3. Initialize the two cameras and set the acquisition parameters;

S4. Let α take a picture M _α and record the timestamp time _α corresponding to the photo. After an interval of time T, let β take a picture M _β and record the timestamp time _β corresponding to the photo;

When shooting, start the device so that the lower edge of the glass appears from the upper lens and the lower lens in sequence. The upper lens detects in real time whether the glass enters the field of view. If it enters the field of view, the upper and lower cameras take two photos respectively at fixed time intervals.

The distance d between the two telecentric lenses should be set in combination with the moving speed range of the object. If two shots are shot with an interval of 1s, it should be ensured that the object appears in the upper lens field of view at the moment before the start of 1s, and the object appears in the lower lens field of view at the end of 1s. At the same time, it should also be avoided that the object is captured in the upper lens but not in the lower lens.

Preferably, the value of the object working distance is related to the optical parameters of the telecentric lens and should be adjusted based on the specific lens used. The distance between the object and the lens should be kept as close as possible, and the error should not exceed 3mm.

Preferably, before starting the measurement, it should be ensured that the lower edge of the glass is above the upper lens, that is, the lower edge of the glass plane has not yet entered the field of view of the upper lens.

S5. Position the lower edge of the glass on the two pictures.

S5-1. First, use the Sobel operator to process the image horizontally;

S5-2. Use binarization processing on the horizontally processed images;

S6. Detect the boundary position of the picture after positioning the lower edge of the glass.

S6-1. For the binarized image dst _w*h , sum all the points in each column to obtain a one-dimensional vector P _w . Each value in the vector is calculated as follows:

Traverse the values in the vector from front to back. If the value of a certain point is greater than 255*Thickness, the coordinates of the point can be considered to be the abscissa values x _α and x _β of the lower edge of the glass.

Among them, 255 is the pixel value represented by white, and Thickness is the pixel length of the glass thickness.

S6-2. In the picture dst _w*h , draw the lower edge straight line for detection;

S7. Calculate the average moving speed of the glass based on the time interval I of the movement of the glass plane corresponding to the two photos and the distance of the glass movement.

Preferably, the specific method of step S2 is:

Estimate the change range of the moving speed of the target glass plane [v ₀ , v ₁ ], adjust the distance d (mm) between the two telecentric lenses, and calculate the adjacent shooting time interval T:

Preferably, step S2 also includes adjusting the distance between the telecentric lens and the side of the glass.

Preferably, the telecentric lenses α and β shoot at a shooting frame rate of 50 Hz.

Preferably, the step S4 also includes image preprocessing:

Convert the color RGB image into grayscale image and continue detection:

Gray＝Red*0.3+Green*0.59+Blue*0.11

The obtained grayscale two-dimensional picture matrix M _w*h . Each value in the matrix represents the grayscale value at that point. The value range is [0, 255]. The field of view of the telecentric lens is when the camera is placed. Rotated 90 degrees counterclockwise to obtain a larger field of view, all points on each column of the matrix M are summed to obtain a one-dimensional vector N _w , where each value in the vector is calculated as follows:

Traverse the values in the vector from back to front. If the value at one point exceeds the predetermined width Thickness=40pixel, it indicates that the glass appears in the field of view. Here 40 pixels refers to the thickness of the glass on the picture.

If the glass appears, go to the next step. If it does not, repeat step 3.

Preferably, the specific method of step S5-1 is:

Use the matrix in the X direction of the Sobel operator to perform a convolution operation on M _{α, β} to obtain the preliminary edge position:

Preferably, the specific method of step S5-2 is:

Use binarization processing to enhance the effect of the boundary, and obtain the binarized processing result map dst. The value of each pixel on dst is calculated from the value of the corresponding point on SobelX, so the size of the dst matrix is also w*h. Each point in dst is calculated as follows:

Preferably, the specific method of step S6 is:

Next, the position of the glass boundary is detected. Similarly, for the binarized image dst, sum all the points in each column to obtain a one-dimensional vector P, which has a total of h values. Each value in the vector is calculated as follows:

Among them, i represents the i-th column in the picture M, and also represents the i-th value in the vector P, and the value range is [1, w]. j represents the row number, and the value range is [1, h].

Traverse the values in the vector from front to back. If the value of a certain point is greater than 255*Thickness, the coordinates of the point can be considered to be the abscissa values x _α and x _β of the lower edge of the glass, where 255 is the pixel value represented by white. , Thickness is the pixel length of the glass thickness.

Preferably, in step S7, the time interval I (ms) for the movement of the glass plane corresponding to the two photos is:

I=(time _β -time _α )/10 ⁹ ,

The distance the glass moves is calculated as:

The moving distance of the glass is divided into three parts: the distance between the glass edge in M _α and the lower boundary of α; the distance between the glass edge in M _β and the upper boundary of β; the distance from the lower boundary of α to the upper boundary of β, that is, α, β The distance d between the two lenses,

Then the distance the glass moves is:

Distance＝(x _α +wx _β )*K+d

Among them, K is the proportional coefficient that converts the pixel length into the actual length.

Preferably, the proportional coefficient K is calculated as follows:

Where len _w is the lateral field of view of the telecentric lens, in mm. image _w is the horizontal resolution of the image, in pixels.

The invention has the following characteristics and beneficial effects:

Adopting the above technical solution, the present invention proposes the solution of using a binocular telecentric lens to measure the speed of a glass plane, which is simple and convenient to deploy and use. No preset parameters are required and can be used directly for measurement. By adjusting the distance between cameras and the time interval between detections, a wide range of speeds can be measured. The present invention uses a combination scheme of a telecentric lens and a global exposure camera, which will not produce blurry imaging effects when shooting high-speed moving objects. A telecentric lens is used to capture objects, and its ultra-low distortion imaging characteristics enable high accuracy in distance measurement. At the same time, the telecentric lens has low requirements for the light in the environment. There is no need to additionally light the glass. You only need to avoid direct light from the telecentric lens. The entire device has low environmental requirements and can meet the requirements for high-precision speed measurement of transparent objects in a variety of situations.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without exerting any creative effort.

Figure 1 is a flow chart of an embodiment of the present invention.

Figure 2 is a schematic diagram of the positions of the glass and the camera according to the present invention.

Figure 3 shows the grayscale image captured by the camera.

Figure 4 shows the result after processing using the Sobel operator.

Figure 5 shows the result after binarization processing.

Figure 6 shows the results of the detected lower edge position of the glass.

Detailed ways

It should be noted that, as long as there is no conflict, the embodiments and features in the embodiments of the present invention can be combined with each other.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", " The orientations or positional relationships indicated by "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and The simplified description is not intended to indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms “first”, “second”, etc. are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Thus, features defined by "first," "second," etc. may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, "plurality" means two or more.

In the description of the present invention, it should be noted that, unless otherwise clearly stated and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense. For example, it can be a fixed connection or a detachable connection. Connection, or integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be an internal connection between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood through specific situations.

In the following steps, the telecentric lens model used is: Daheng Image-ZXCM118-64H-AL, and the camera model used: Daheng Image-MER2-302-56U3M. The present invention has no fixed requirements on the model and brand of the telecentric lens and camera. It should be noted that the calculation and implementation should be based on the specific optical parameters of the equipment when implementing the solution.

The present invention provides a solution for measuring the speed of a glass plane based on a binocular telecentric lens. For a specific flow chart, refer to Figure 1. The present invention's solution for measuring the speed of a glass plane based on a binocular telecentric lens includes the following steps:

Step 1. Make the lens perpendicular to the side of the glass plane. The line between the two lenses is the direction of plane movement. Estimate the change range of the moving speed of the target glass plane [v ₀ , v ₁ ], and adjust the distance d (mm) between the two telecentric lenses. Calculate the time interval T between adjacent shots.

The target moving speed is between 85mm/s and 90mm/s. Try to make the calculated time interval T greater than 1 second to make the calculated speed error lower. Therefore, under the premise that the target moving speed interval is fixed, let d>v ₁ *1s. Here, take d=100mm and calculate T≈1.14s. The interval time here does not need to be very accurate, so it is set to 1.1s. .

Step 2. Adjust the distance between the telecentric lens and the glass plane, that is, the object working distance is within the range of 158mm±3mm. It should be noted that the object working distance is related to the optical parameters of the telecentric lens, and the distance length should be determined according to the specific model used. The relative position information of the device and the object can be referred to Figure 2.

Step 3. Initialize the two cameras to ensure that the two cameras start normally and can obtain images. Set the corresponding collection parameters. The specific parameters for the implementation of the present invention are shown in the following table:

parameter value Exposure time 5000μs Gain 12dB trigger mode turn on trigger source Soft trigger Acquisition mode single frame mode

It should be combined with the actual application scene settings to ensure that the lens is completely black when there are no objects. It should be noted that the exposure time has a great influence on the brightness of the photos taken. The longer the exposure time, the stronger the brightness. But it should not be too strong, so as not to affect the accuracy of the time interval. The telecentric lens has a strong ability to capture objects within the field of view, and the transparent glass surface can still be seen in the field of view without additional supplementary light enhancement. Shooting the glass from the side at the same time can further enhance the imaging effect of transparent glass.

Step 4. Before the glass enters the field of view, start the detection process. Let the upper telecentric lens be α and the lower telecentric lens β. Let α perform shooting detection at a shooting frame rate of 50Hz. Each time a frame of picture is obtained, the captured content is detected.

If you use a color camera to shoot, you should convert the color RGB image into a grayscale image before continuing the detection:

Gray＝Red*0.3+Green*0.59+Blue*0.11 (2)

The obtained grayscale two-dimensional picture matrix M _w*h is shown in Figure 3. Each value in the matrix represents the gray value at that point, and the value range is [0, 255]. The field of view of the telecentric lens is that the camera is rotated 90 degrees counterclockwise when placed to obtain a larger field of view. So from the picture, the glass is moving from the right to the left. Summing all the points on each column of the matrix M results in a one-dimensional vector N _w , where each value in the vector is calculated as follows:

Traverse the values in the vector from back to front. If the value at one point exceeds the predetermined width Thickness=40pixel, it indicates that the glass appears in the field of view. Here 40 pixels refers to the thickness of the glass on the picture.

If the glass appears, go to the next step. If it does not, repeat step 3.

Step 5. Let α take a photo M _α and record the timestamp time _α corresponding to the photo. After an interval of time T, let β take a photo M _β and record the timestamp time _β corresponding to the photo. The timestamp is provided by the camera's internal clock, and the unit is nanoseconds.

Position the lower edge of the glass in the above two pictures. First, use the Sobel operator to process the image in the horizontal direction, that is, use the matrix in the X direction of the Sobel operator to perform a convolution operation on M _{α and β} to obtain the preliminary edge position:

The results obtained from the processing are shown in Figure 4.

Use binarization to enhance the effect of boundaries. The value of each point on the picture is calculated as follows:

The threshold value should be set according to the brightness obtained by Sobel operator processing. This method is set to 175. The image obtained after binarization is shown in Figure 5.

Next, the position of the glass boundary is detected. Similarly, for the binarized image dst _w*h , all points on each column are summed to obtain a one-dimensional vector P _w , where each value in the vector is calculated as follows:

Traverse the values in the vector from front to back. If the value of a certain point is greater than 255*Thickness, the coordinates of the point can be considered to be the abscissa values x _α and x _β of the lower edge of the glass. Among them, 255 is the pixel value represented by white, and Thickness is the pixel length of the glass thickness.

In M, draw the lower edge straight line of the test, as shown in Figure 6. By doing the same process for M _α and M _β , the positions x _α and x _β of the glass boundary in the two photos can be obtained.

The calculation of the proportion coefficient K for converting pixel length into actual length is as follows:

For the telecentric lens and camera used in this patent, K=0.02568359375mm/pixel can be calculated. Step 6. From the values obtained in the above steps, the time interval I (ms) of the movement of the glass plane corresponding to the two photos can be obtained as:

I＝(time _β -time _α )/10 ⁹ (9)

The moving distance of the glass is divided into three parts: the distance between the glass edge in M _α and the lower boundary of α; the distance between the glass edge in M _β and the upper boundary of β; the distance from the lower boundary of α to the upper boundary of β, that is, α, β The distance d between the two lenses.

Then the distance the glass moves is:

Distance＝(x _α +wx _β )*K+d (10)

The average moving speed of the glass is:

Based on the above steps, perform multiple experiments and collect statistical data. A robotic arm is used to ensure that the glass moves at a specified speed. The measured speed and speed error are kept to 4 decimal places, as shown in the following table:

It can be seen from the data in the table that the speed measurement method provided by this patent has high accuracy and can still ensure sufficient high-precision speed measurement results under relatively fast speed conditions.

The above method provided by this application has the following advantages compared with the existing technology:

This algorithm is based on the glass plane speed measurement method with binocular telecentric lenses. It has strong applicability and can calculate objects in a variety of scenarios, including transparent and high-temperature objects. There is no need to calculate preset parameters, and it is easy to deploy and use. The accuracy value of this algorithm depends on the calculated K value, which is related to the field of view of the telecentric lens and the imaging element of the camera. In the above experiment, a high accuracy level of about 0.02mm/pixel can be achieved. If a larger field of view is selected, Telecentric lenses and higher-resolution cameras further improve accuracy. For the time interval I of the glass movement, the accuracy can reach nanosecond level due to the use of the built-in clock of the camera. And when calculating the time interval, the time corresponding to the photo returned by the camera is used. The time calculation includes the time overhead of the optical imaging process such as exposure time, and the calculation of the time interval is accurate enough. In detecting the lower edge of the glass, unlike common edge detection algorithms, this method is based on the imaging characteristics of the telecentric lens. It does not use image processing methods such as Gaussian filtering that may blur the imaging content, and retains the texture of the glass in the image as much as possible. part to make the measurement results as accurate as possible. Judging from the experimental data, the method proposed in this patent has the characteristics of wide applicability, high recognition rate and high measurement accuracy.

The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and apply the present invention. It is obvious that those skilled in the art can easily make various modifications to the above-described embodiments and apply the general principles described here to other embodiments without going through any creative efforts. Therefore, the present invention is not limited to the above embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention should be within the protection scope of the present invention.

Claims (10)

1. A glass plane speed measurement method based on a binocular telecentric lens, which is characterized by including the following steps: S1. Build an image capturing device. The image capturing device includes two cameras. The telecentric lenses of the two cameras are marked as α and β respectively. The two cameras are located on one side of the glass plane to be measured, and the telecentric lenses of the two cameras are located on one side of the glass plane to be measured. The center lens is perpendicular to the side of the glass plane to be tested; S2. Set the shooting time interval T of the two cameras according to the moving speed of the glass plane to be measured and the distance between the two cameras; S3. Initialize the two cameras and set the acquisition parameters; S4. Let α take a picture M _α and record the timestamp time _α corresponding to the photo. After an interval of time T, let β take a picture M _β and record the timestamp time _β corresponding to the photo; S5. Position the lower edge of the glass on the two pictures. S5-1. First, use the Sobel operator to process the image horizontally; S5-2. Use binarization processing on the horizontally processed image to obtain the image dst; S6. Detect the boundary position of the picture after positioning the lower edge of the glass. S6-1. For the binarized image dst, sum all the points in each column to obtain a one-dimensional vector P. Each value in the vector is calculated as follows: Among them, i represents the i-th column in the picture M, and also represents the i-th value in the vector P, and the value range is [1, w]. j represents the row number, and the value range is [1, h]; Traverse the values in the vector from front to back. If the value of a certain point is greater than 255*Thickness, the coordinates of the point can be considered to be the abscissa values x _α and x _β of the lower edge of the glass. Among them, 255 is the pixel value represented by white, and Thickness is the pixel length of the glass thickness; S6-2. In the picture dst, draw the lower edge straight line for detection; S7. Calculate the average moving speed of the glass based on the time interval I of the movement of the glass plane corresponding to the two photos and the distance of the glass movement. 2. A glass plane speed measurement method based on a binocular telecentric lens according to claim 1, characterized in that the specific method of step S2 is: Estimate the change range of the moving speed of the target glass plane [v ₀ , v ₁ ], adjust the distance d (mm) between the two telecentric lenses, and calculate the adjacent shooting time interval T: where d is the distance between the two telecentric lenses. 3. A glass plane speed measurement method based on a binocular telecentric lens according to claim 1, characterized in that step S2 further includes adjusting the distance between the telecentric lens and the side of the glass. 4. A glass plane speed measurement method based on a binocular telecentric lens according to claim 1, characterized in that the telecentric lenses α and β shoot at a shooting frame rate of 50 Hz. 5. A glass plane speed measurement method based on a binocular telecentric lens according to claim 2, characterized in that the step S4 also includes image preprocessing: Convert the color RGB image into grayscale image and continue detection: Gray＝Red*0.3+Green*0.59+Blue*0.11 The obtained grayscale two-dimensional picture matrix M _w*h . Each value in the matrix represents the grayscale value at that point. The value range is [0, 255]. The field of view of the telecentric lens is when the camera is placed. Rotated 90 degrees counterclockwise to obtain a larger field of view, all points on each column of the matrix M are summed to obtain a one-dimensional vector N _w , where each value in the vector is calculated as follows: Traverse the values in the vector from back to front. If the value at one point exceeds the predetermined width Thickness=40pixel, it indicates that the glass appears in the field of view. Here 40 pixels refers to the thickness of the glass on the picture. If the glass appears, go to the next step. If it does not, repeat step 3. 6. A glass plane speed measurement method based on a binocular telecentric lens according to claim 1, characterized in that the specific method of step S5-1 is: Use the matrix in the X direction of the Sobel operator to perform a convolution operation on M _{α, β} to obtain the preliminary edge position: 7. A glass plane speed measurement method based on a binocular telecentric lens according to claim 6, characterized in that in step S5-2: The value of each point on the image dst is calculated by the conversion between the corresponding point values on the SobelX image as follows: Among them (x, y) represents the horizontal and vertical coordinates of a certain point, x∈[1, w], y∈[1, h]. 8. A glass plane speed measurement method based on a binocular telecentric lens according to claim 7, characterized in that the specific method of step S6 is: For the binarized image dst, the resolution is w*h, and the unit is pixels. Sum all the points on each column to obtain a one-dimensional vector P, in which the number of values in the vector is w. Each value is calculated as follows: Among them, i represents the i-th column in the picture M, and also represents the i-th value in the vector P. The value range is [1, w], j represents the row, and the value range is [1, h]; Traverse the values in the vector from front to back. If the value of a certain point is greater than 255*Thickness, the coordinates of the point can be considered to be the abscissa values x _α and x _β of the lower edge of the glass, where 255 is the pixel value represented by white. , Thickness is the pixel length of the glass thickness. 9. A glass plane speed measurement method based on a binocular telecentric lens according to claim 8, characterized in that in step S7, the time interval I (ms) for the movement of the glass plane corresponding to the two photos is: I=(time _β -time _α )/10 ⁹ , The distance the glass moves is calculated as: The moving distance of the glass is divided into three parts: the distance between the glass edge in M _α and the lower boundary of α; the distance between the glass edge in M _β and the upper boundary of β; the distance from the lower boundary of α to the upper boundary of β, that is, α, β The distance d between the two lenses, Then the distance the glass moves is: Distance＝(x _a +wx _β )*K+d Among them, K is the proportional coefficient that converts the pixel length into the actual length. 10. A glass plane speed measurement method based on a binocular telecentric lens according to claim 9, characterized in that the calculation of the proportional coefficient K is as follows: Among them, len _w is the lateral field of view of the telecentric lens, in mm, and image _w is the lateral resolution of the image, in pixels.