A method of monitoring the speed of a belt conveyor

Abstract

This invention relates to the field of speed monitoring technology, and more particularly to a method for monitoring the speed of a belt conveyor. The method includes setting marker points on the side of the conveyor's rollers and installing a monitoring camera; during conveyor operation, the monitoring camera continuously acquires several images of the roller side and numbers them; defining a study area centered on the marker points on the captured images and constructing a matrix A corresponding to the study area; performing image binarization processing on matrix A based on the pixel values ​​of the study area in each captured image to obtain a binarized matrix for each captured image; calculating the centroid coordinates of the study area in each captured image based on the binarized matrix, and recording the image number of the first image whose centroid coordinates coincide with the first captured image; and calculating the operating speed of the belt conveyor based on the camera's acquisition frequency and the image number. This invention avoids mechanical wear during the measurement process and is simple and convenient to install.

Description

Technical Field

[0001] This invention relates to the field of speed monitoring technology, and in particular to a method for monitoring the speed of a belt conveyor. Background Technology

[0002] Belt conveyors are essential equipment widely used in industrial production and logistics transportation, and their operating status directly affects production efficiency and safety. Speed ​​control is one of the core parameters during belt conveyor operation, as it determines the material transfer efficiency and affects the coordination and stability of the entire production line. Traditional speed measurement methods typically rely on mechanical sensors (such as speed measuring wheels and photoelectric encoders), but these methods have certain limitations, such as susceptibility to wear, complex installation, and difficulty in adapting to complex environments.

[0003] Traditional belt conveyor speed measurement methods typically involve setting up a flywheel device to contact the belt. When the belt conveyor is running, the flywheel rotates, and a speed encoder is installed on the flywheel device. The speed encoder measures the linear velocity of the outer edge of the flywheel to determine the belt conveyor speed. However, in this method, the speed measuring structure is prone to wear and requires regular maintenance, and the installation is complex.

[0004] Therefore, it is necessary to provide a new method for monitoring the speed of belt conveyors to solve the above-mentioned technical problems. Summary of the Invention

[0005] The main objective of this invention is to provide a method for monitoring the speed of belt conveyors, aiming to solve the problems of existing belt conveyor speed monitoring methods, such as equipment being prone to wear and complex installation.

[0006] To achieve the above objectives, the present invention proposes a belt conveyor speed monitoring method, comprising the following steps: S1: Marking points are set on the side of the rollers of the belt conveyor, and monitoring cameras are set on the belt conveyor corresponding to the side of the rollers; S2: During the operation of the belt conveyor, a monitoring camera continuously captures several images of the side of the drum, and the images are numbered according to the acquisition order. S3: Define a point centered on the marked point on the captured image. The study area is defined, and the corresponding matrix A is constructed; where: The number of pixel rows in the study area. The number of pixel columns in the study area; S4: Perform image binarization processing on matrix A based on the pixel values ​​of the study area in each captured image to obtain the corresponding binarization matrix for each captured image; S5: Calculate the centroid coordinates of the study area in each captured image based on the binarization matrix, and record the image number of the first captured image whose centroid coordinates coincide with the first captured image. S6: The operating speed of the belt conveyor is calculated based on the acquisition frequency of the monitoring camera and the image number recorded in S5.

[0007] Optionally, the specific formula for image binarization processing in step S4 is as follows: ; in: The elements in the binary matrix, For row number, Take 1 to natural numbers, For column numbers, Take 1 to 0 natural numbers; For the study area Line 1 The pixel value of the column pixel; To set a pixel threshold.

[0008] Optionally, in step S5, the specific formula for calculating the centroid coordinates is as follows: ; ; in: The x-coordinate of the centroid The ordinate is the centroid.

[0009] Optionally, if the number of marker points set in S1 is one, then the operating speed of the belt conveyor is... The specific calculation formula is as follows: ; in: The diameter of the roller; To monitor the camera's acquisition frequency; The image number is the first image whose centroid coordinates coincide with the first captured image. Number the first image taken.

[0010] Optionally, the number of marker points set in S1 is indivual, If the marked points are evenly distributed circumferentially around the center of the roller, the specific formula for calculating the running speed of the belt conveyor is as follows: .

[0011] Optionally, the roller can be any one of the drive roller, redirecting roller, and idler roller of a belt conveyor.

[0012] Optionally, in step S4, the pixel threshold is set to the pixel value at the marked point.

[0013] Optionally, the monitoring camera is a grayscale camera, and the set pixel threshold is determined using the OTU threshold segmentation method, specifically: Let the image In position The grayscale value at that location is set to , ,in: Image grayscale levels; Calculate the first The proportion of pixels corresponding to each gray level is given by the following formula: ; in: For the first The number of pixels corresponding to each gray level; , ; In terms of intervals Different gray levels are used as the thresholds for separating background and marker points, and the inter-class variances of the corresponding background and marker points are calculated. The gray level corresponding to the largest inter-class variance is selected as the set pixel threshold. The specific formula is as follows: ; in: The number of pixels corresponding to the marker point. ; The threshold for segmentation; This represents the number of pixels corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the marked point. ; This represents the overall average grayscale value. .

[0014] Optionally, the monitoring camera is an RGB camera, and the OSTU threshold segmentation method is used to obtain the set pixel threshold for each channel of each pixel corresponding to the marked point.

[0015] Optionally, a monitoring camera is installed for each of the drive roller, redirecting roller, and idler roller of the belt conveyor; in step S6, the running speeds of the belt conveyor corresponding to the drive roller, redirecting roller, and idler roller are calculated respectively, and the average value is taken to obtain the final running speed of the belt conveyor.

[0016] Optionally, an alarm signal is triggered when the difference between any two of the running speeds of the drive roller, the redirecting roller, and the idler roller exceeds a set threshold.

[0017] This invention captures images of the side of the rollers on a belt conveyor using a monitoring camera, and determines the roller's rotation period by calculating its centroid coordinates through binarization processing. Combined with the roller's diameter, the operating speed of the belt conveyor is then calculated. Compared to traditional mechanical speed measurement methods, this approach offers greater flexibility, requires no mechanical modifications or sensor installation, avoids mechanical wear during measurement, and is simple and convenient to install. It can also be used to process data from existing belt conveyor image monitoring systems to determine the belt conveyor's operating speed. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the monitoring camera and belt conveyor in an embodiment of the present invention; Figure 2 for Figure 1 Enlarged view of part A; Figure 3 This is a schematic diagram of the captured images in an embodiment of the present invention; Figure 4 a to e are schematic diagrams of the continuously acquired images numbered 1 to 5 in the embodiments of the present invention; Figure 5 This is a schematic diagram illustrating the division of the study area in an embodiment of the present invention; Figure 6 This is a schematic diagram of an image captured with four marker points set up in an embodiment of the present invention; Figure 7 This is a schematic diagram of an image taken with 8 marker points set up in an embodiment of the present invention.

[0020] Explanation of icon numbers: 1. Belt conveyor, 2. Roller, 3. Monitoring camera, 4. Marker point, 5. Study area.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0024] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0025] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0026] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0027] This invention proposes a method for monitoring the speed of belt conveyors, aiming to solve the problems of existing belt conveyor speed monitoring methods, such as equipment being prone to wear and complex installation.

[0028] Example 1 See Figures 1 to 5This embodiment proposes a method for monitoring the speed of a belt conveyor, including the following steps: S1: Marking points are set on the side of the roller of the belt conveyor, and monitoring cameras are set on the belt conveyor corresponding to the side of the roller; in this embodiment, the roller is any one of the drive roller, redirecting roller and idler roller of the belt conveyor.

[0029] S2: During the operation of the belt conveyor, a monitoring camera continuously captures several images of the side of the drum, and the images are numbered according to the acquisition order. S3: Define a point centered on the marked point on the captured image. The study area is determined, and the matrix A corresponding to the study area is constructed. The number of pixel rows in the study area. The number of pixel columns in the study area; S4: Perform image binarization processing on matrix A based on the pixel values ​​of the study area in each captured image to obtain the corresponding binarization matrix for each captured image; the specific formula for image binarization processing in S4 is as follows: ; in: The elements in the binary matrix, For row number, Take 1 to natural numbers, For column numbers, Take 1 to 0 natural numbers; For the study area Line 1 The pixel value of the column pixel; To set a pixel threshold.

[0030] In this embodiment, the pixel threshold is set to the pixel value at the marked point.

[0031] S5: Calculate the centroid coordinates of the study area in each captured image based on the binarization matrix, and record the image number of the first captured image whose centroid coordinates coincide with the first captured image. In S5, the specific formula for calculating the centroid coordinates is as follows: ; ; in: The x-coordinate of the centroid The ordinate is the centroid.

[0032] S6: The operating speed of the belt conveyor is calculated based on the acquisition frequency of the monitoring camera and the image number recorded in S5.

[0033] Specifically, the centroid of the study area in each image is calculated sequentially. When the marked point rotates one full turn and coincides with the initial position, the image sequence number is recorded. The industrial camera's acquisition frequency is The rotation period T of the drum is: ( ) / ， According to the roller diameter The belt speed can then be obtained.

[0034] In this embodiment, the number of marker points set in S1 is one, so the operating speed of the belt conveyor is... The specific calculation formula is as follows: ; in: The diameter of the roller; To monitor the camera's acquisition frequency; The image number is the first image whose centroid coordinates coincide with the first captured image. Number the first image taken.

[0035] In this embodiment, an alarm signal is triggered when the difference between any two of the running speeds of the drive roller, the redirecting roller, and the idler roller exceeds a set threshold.

[0036] Example 2 The difference between this embodiment and the previous embodiment is that the number of marker points set in S1 is... indivual, If the marked points are evenly distributed circumferentially around the center of the roller, the specific formula for calculating the running speed of the belt conveyor is as follows: .

[0037] In this embodiment, the image taken when the number of marker points can be 4 or 8 is as follows: Figure 6 and Figure 7 As shown, setting multiple marker points helps improve measurement sensitivity.

[0038] Example 3 In machine vision processing, it is often necessary to segment the target object from the background to analyze the unique information of the target object. When there is a significant difference in color gamut between the background and the target object, the acquired image is often processed as a grayscale image to improve the efficiency of the image processing algorithm. This embodiment uses an adaptive threshold segmentation method (OSTU) to binarize the grayscale image. When the color gamut difference between the background and the target object is large, this method can achieve very ideal results. However, in actual operation, it was found that to ensure an absolute difference in the color gamut between the background and the target object, relatively high hardware support is required. Furthermore, due to the differences between the measured objects, it is difficult to apply to large-scale machine vision measurement work.

[0039] The difference between this embodiment and Embodiment 1 is that the monitoring camera is a grayscale camera, and the OTU threshold segmentation method is used to determine the set pixel threshold. Specifically: Let the image In position The grayscale value at that location is set to , ,in: Image grayscale levels; Calculate the first The proportion of pixels corresponding to each gray level is given by the following formula: ; in: For the first The number of pixels corresponding to each gray level; , ; In terms of intervals Different gray levels are used as the thresholds for separating background and marker points, and the inter-class variances of the corresponding background and marker points are calculated. The gray level corresponding to the largest inter-class variance is selected as the set pixel threshold. The specific formula is as follows: ; in: The number of pixels corresponding to the marker point. ; The threshold for segmentation; This represents the number of pixels corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the marked point. ; This represents the overall average grayscale value. .

[0040] Example 4 The difference between this embodiment and Embodiment 1 is that the monitoring camera is an RGB camera, and the OSTU threshold segmentation method is used to obtain the set pixel threshold for each channel of each pixel corresponding to the marker point.

[0041] Example 5 The difference between this embodiment and embodiment 1 is that a monitoring camera is set for each of the drive roller, redirecting roller and idler roller of the belt conveyor; in S6, the running speed of the belt conveyor corresponding to the drive roller, redirecting roller and idler roller is calculated respectively, and the average value is taken to obtain the final running speed of the belt conveyor.

[0042] The above description is only a preferred embodiment of the present invention and does not limit the scope of the present invention. All equivalent structural transformations made under the inventive concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included within the protection scope of the present invention.

Claims

1. A method for monitoring the speed of a belt conveyor, characterized in that, Includes the following steps: S1: Marking points are set on the side of the rollers of the belt conveyor, and monitoring cameras are set on the belt conveyor corresponding to the side of the rollers; S2: During the operation of the belt conveyor, a monitoring camera continuously captures several images of the side of the drum, and the images are numbered according to the acquisition order. S3: Define a point centered on the marked point on the captured image. The study area is defined, and the corresponding matrix A is constructed; where: The number of pixel rows in the study area. The number of pixel columns in the study area; S4: Perform image binarization processing on matrix A based on the pixel values ​​of the study area in each captured image to obtain the corresponding binarization matrix for each captured image; S5: Calculate the centroid coordinates of the study area in each captured image based on the binarization matrix, and record the image number of the first captured image whose centroid coordinates coincide with the first captured image. S6: The operating speed of the belt conveyor is calculated based on the acquisition frequency of the monitoring camera and the image number recorded in S5.

2. The belt conveyor speed monitoring method according to claim 1, characterized in that, In step S4, the specific formula for image binarization is as follows: ； in: The elements in the binary matrix, For row number, Take 1 to natural numbers, For column numbers, Take 1 to 0 natural numbers; For the study area Line 1 The pixel value of the column pixel; To set a pixel threshold.

3. The belt conveyor speed monitoring method according to claim 2, characterized in that, In S5, the specific formula for calculating the centroid coordinates is as follows: ； ； in: The x-coordinate of the centroid The ordinate is the centroid.

4. The belt conveyor speed monitoring method according to claim 3, characterized in that, If the number of marker points set in S1 is one, then the operating speed of the belt conveyor is... The specific calculation formula is as follows: ； in: The diameter of the roller; To monitor the camera's acquisition frequency; The image number is the first image whose centroid coordinates coincide with the first captured image. Number the first image taken.

5. The belt conveyor speed monitoring method according to claim 3, characterized in that, The number of marker points set in S1 is: indivual, If the marked points are evenly distributed circumferentially around the center of the roller, the specific formula for calculating the running speed of the belt conveyor is as follows: 。 6. The belt conveyor speed monitoring method according to any one of claims 1-5, characterized in that, The roller can be any one of the drive roller, redirecting roller, and idler roller of a belt conveyor.

7. The belt conveyor speed monitoring method according to any one of claims 1-5, characterized in that, In step S4, the pixel threshold is set to the pixel value at the marked point.

8. The method for monitoring the speed of a belt conveyor according to any one of claims 1-5, characterized in that, The monitoring camera is a grayscale camera, and the set pixel threshold is determined using the OTU threshold segmentation method, specifically: Let the image In position The grayscale value at that location is set to , ,in: Image grayscale levels; Calculate the first The proportion of pixels corresponding to each gray level is given by the following formula: ； in: For the first The number of pixels corresponding to each gray level; , ; In terms of intervals Different gray levels are used as the thresholds for separating background and marker points, and the inter-class variances of the corresponding background and marker points are calculated. The gray level corresponding to the largest inter-class variance is selected as the set pixel threshold. The specific formula is as follows: ； in: The number of pixels corresponding to the marker point. ; The threshold for segmentation; This represents the number of pixels corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the background. ; This represents the average grayscale value of each pixel corresponding to the marked point. ; This represents the overall average grayscale value. .

9. The method for monitoring the speed of a belt conveyor according to any one of claims 1-5, characterized in that, The monitoring camera is an RGB camera. The OTU threshold segmentation method is used to obtain the set pixel threshold for each channel of each pixel corresponding to the marked point.

10. The method for monitoring the speed of a belt conveyor according to any one of claims 1-5, characterized in that, Each of the drive roller, idler roller, and idler roller of the belt conveyor is equipped with a monitoring camera; in step S6, the running speed of the belt conveyor corresponding to the drive roller, idler roller, and idler roller is calculated respectively, and the average value is taken to obtain the final running speed of the belt conveyor.

11. The belt conveyor speed monitoring method according to claim 10, characterized in that, An alarm signal is triggered when the difference between any two of the running speeds of the drive roller, redirecting roller, and idler roller exceeds a set threshold.

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