A method and apparatus for identifying pressure gauges during inspection and testing.

Abstract

The present application relates to pressure gauge metrological verification technical field, especially provide a kind of for pressure gauge identification method and device of test.The method includes the image of double pressure gauge of digital pressure gauge and pointer pressure gauge is collected using single camera, and image segmentation is carried out;The image of pointer pressure gauge is preprocessed;By constructing the character recognition model based on PaddleOCR library, the range of pointer pressure gauge and digital pressure indication are identified;The image of pointer pressure gauge is subjected to Hough circle transformation detection and straight line Hough transformation detection, and the scale line ring and pointer are obtained by setting threshold;According to scale line ring, after the mask of annular scale line non-scale area is constructed, polar coordinate is developed;The indication of pointer pressure gauge is calculated, the method overcomes the uncertainty and artificial error of manual reading, realizes the synchronous identification of double pressure indication, and improves the accuracy and efficiency of identification.

Description

Technical Field

[0001] This invention relates to the field of pressure gauge metrology and verification technology, and in particular to an identification method and apparatus for pressure gauge inspection and testing. Background Technology

[0002] Pointer pressure gauges are widely used in many pressure monitoring fields due to their simple structure, convenient installation, low cost, and reliable operation. Their measurement accuracy directly affects process safety, product quality, personnel safety, and the reliability of experimental results; therefore, they are listed as working measuring instruments subject to mandatory verification. However, a significant contradiction exists between the large number of gauges in use and the legally mandated periodic verification requirements: the traditional fully manual verification mode is inefficient, with the verification of a single gauge often taking several minutes or even tens of minutes. This not only leads to lengthy verification cycles and severe backlogs of tasks but also subjects frontline metrology personnel to high-intensity repetitive labor. More importantly, the accuracy of manual readings is easily affected by factors such as eyesight, experience, fatigue, viewing angle, and operational standardization. The quality of verification results is highly dependent on individual condition, with uncertainties and the risk of human error, making it difficult to guarantee the consistency of results under large-scale testing. Existing image processing methods typically only target pointer pressure gauges, but actual verification requires simultaneous reading of both the digital pressure gauge used as a standard and the pointer pressure gauge used as the test gauge. Furthermore, the glare on the pointer gauge dial also severely interferes with the accuracy of visual recognition. Summary of the Invention

[0003] In view of this, the present invention provides an identification method and apparatus for pressure gauge inspection and testing, which overcomes the uncertainty and human error risk of manual reading, realizes the synchronous identification of dual pressure gauge readings, and improves the accuracy and efficiency of identification.

[0004] In a first aspect, the present invention provides an identification method for pressure gauge inspection and testing, the method comprising:

[0005] Step 1: Use a single camera to acquire images of both a digital pressure gauge and a pointer pressure gauge, and then perform image segmentation.

[0006] Step 2: Image preprocessing. Preprocess the image of the pointer pressure gauge.

[0007] Step 3: OCR recognition. By constructing a character recognition model based on the PaddleOCR library, the range of the pointer-type pressure gauge and the pressure reading of the digital pressure gauge are recognized.

[0008] Step 4: Identify the scale rings and pointer. Perform Hough circle transform and linear Hough transform detection on the image of the pointer pressure gauge. Obtain the scale rings and pointer by setting a threshold.

[0009] Step 5: Polar coordinate expansion of the scale line. Based on the scale line ring, after constructing a mask for the non-scale area of ​​the ring scale line, perform polar coordinate expansion.

[0010] Step 6: Calculate the reading of the pointer pressure gauge.

[0011] Optionally, step 2 includes:

[0012] First, Gaussian blur is applied to the image of the pointer pressure gauge to remove noise; second, the image is converted to grayscale to reduce computation; finally, the grayscale image is binarized using adaptive thresholding.

[0013] Optionally, step 4 includes:

[0014] Step 4.1: Based on the image of the pointer pressure gauge, use Hough circle transform to detect all candidate circles with the same center and obtain their corresponding center coordinates and radius values; sort all detected candidate circles in descending order according to their radius values; based on the radius distribution characteristics of the candidate circles, select the circles with the second and third radius values ​​as the scale line rings representing the main scale range.

[0015] Step 4.2: Use the Hough transform to extract straight lines within the dial area, and form an initial set in descending order of line segment length. Secondly, traverse the set. L Calculate the included angle of all straight line combinations. The threshold range of the pointer tip angle is limited to 1. Select a pair of lines that meet the conditions. For the pairs of lines that meet the constraints, calculate the intersection point using Formula 1, and use the line connecting the intersection point and the center of the dial as the pointer line:

[0016] (1).

[0017] Optionally, step 5 includes:

[0018] Step 5.1: Based on the tick mark ring obtained after constructing the mask, expand its polar coordinates according to Formula 2:

[0019] (2);

[0020] in, Let the radius be the inner circle radius. Let the radius be the outer circle. W The width of the rectangle. H The height of the rectangle. The ordinate of the unfolded rectangular plane is given by [reference]. u Let x be the x-coordinate of the unfolded rectangular plane. Polar coordinates;

[0021] Step 5.2: After polar coordinate transformation, the diagonal tick marks in the original image are converted into vertical straight lines in polar coordinate expansion. A custom convolutional kernel filter is used in the edge detection stage to detect the tick marks. The form of the custom convolutional kernel filter is as follows: .

[0022] Optionally, step 6 includes:

[0023] Calculate the reading of the pointer pressure gauge using Formula 3:

[0024] (3);

[0025] in, This represents the total number of tick marks the pointer has passed. , These are the upper and lower limits of the pressure gauge's measurement range. N This represents the total number of scale marks on the dial. , L The length of the tick mark interval currently held by the pointer. L 0 represents the distance of the current pointer from the starting tick mark of the current tick interval.

[0026] Secondly, the present invention provides an identification device for pressure gauge inspection and testing. The device is used to implement the identification method for pressure gauge inspection and testing as described in the first aspect or any possible implementation of the first aspect. The device includes: a digital pressure gauge, a pointer pressure gauge, a ring light source, a mounting platform, a camera, and an air hose connector. The pointer pressure gauge is fixed to the mounting platform by a quick-connect nut. The camera is used to acquire images of both the digital and pointer pressure gauges. The ring light source is used to process the light to eliminate interference from dial reflections. The air hose connector is used to connect to a standard air source.

[0027] Thirdly, embodiments of the present invention provide a computer-readable storage medium comprising a stored program, wherein, when the program is executed, it controls the device on which the computer-readable storage medium is located to perform the identification method for pressure gauge inspection and testing as described in the first aspect or any possible implementation thereof.

[0028] Fourthly, embodiments of the present invention provide an electronic device, comprising: one or more processors; a memory; and one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs include instructions that, when executed by the device, cause the device to perform the identification method for pressure gauge inspection and testing in the first aspect or any possible implementation thereof.

[0029] The technical solution provided by this invention includes a method that involves acquiring images of both a digital pressure gauge and a pointer pressure gauge using a single camera, and performing image segmentation; preprocessing the image of the pointer pressure gauge; identifying the range and digital pressure reading of the pointer pressure gauge by constructing a character recognition model based on the PaddleOCR library; identifying the scale ring and pointer by performing Hough circle transform and linear Hough transform detection on the image of the pointer pressure gauge, and obtaining the scale ring and pointer by setting a threshold; expanding the scale ring in polar coordinates, and after constructing a mask for the non-scale area of ​​the annular scale ring based on the scale ring, performing polar coordinate expansion; and calculating the reading of the pointer pressure gauge. This method overcomes the uncertainty and human error inherent in manual reading, achieves synchronous recognition of the dual pressure gauge readings, and improves the accuracy and efficiency of recognition. Attached Figure Description

[0030] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the embodiments 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 these drawings without creative effort.

[0031] Figure 1 A flowchart illustrating the identification method for pressure gauge inspection and testing provided in this embodiment of the invention;

[0032] Figure 2 This is a schematic diagram of dual pressure gauge image segmentation provided in an embodiment of the present invention, wherein (a) is a pointer-type pressure gauge; and (b) is a digital pressure gauge.

[0033] Figure 3 A schematic diagram of the polar coordinate expansion of the scale line annulus provided in an embodiment of the present invention;

[0034] Figure 4 This is a schematic diagram of the calculation display provided in an embodiment of the present invention;

[0035] Figure 5 A schematic diagram of the detection results provided in an embodiment of the present invention;

[0036] Figure 6 A schematic diagram of an identification device for pressure gauge inspection and testing provided in an embodiment of the present invention;

[0037] Figure 7 This is a schematic diagram of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0039] It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0040] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” used in the embodiments of this invention are also intended to include the plural forms unless the context clearly indicates otherwise.

[0041] It should be understood that the term "and / or" used in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this article generally indicates that the preceding and following related objects have an "or" relationship.

[0042] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0043] Figure 1 A flowchart of the identification method for pressure gauge inspection and testing provided in the embodiments of the present invention is shown below. Figure 1 As shown, the method includes:

[0044] Step 1: Use a single camera to acquire images of both a digital pressure gauge and a pointer pressure gauge, and then perform image segmentation.

[0045] In this embodiment of the invention, images of two pressure gauges are captured by a camera; image segmentation: as follows Figure 2 As shown in (a) and (b) in the image, during the testing process, a digital pressure gauge (standard gauge) and a pointer pressure gauge (test gauge) are located on both sides, and the two pressure gauges are separated from the middle of the image.

[0046] Step 2: Image preprocessing. Preprocess the image of the pointer pressure gauge.

[0047] In this embodiment of the invention, step 2 includes:

[0048] First, Gaussian blur is applied to the image of the pointer pressure gauge to remove noise; second, the image is converted to grayscale to reduce computation; finally, the grayscale image is binarized using adaptive thresholding.

[0049] Step 3: OCR recognition. By constructing a character recognition model based on the PaddleOCR library, the range of the pointer-type pressure gauge and the digital pressure reading are recognized.

[0050] Step 4: Identify the scale rings and pointer. Perform Hough Circle Transform and Linear Hough Transform detection on the image of the pointer pressure gauge. Obtain the scale rings and pointer by setting a threshold.

[0051] In this embodiment of the invention, step 4 includes:

[0052] Step 4.1: Based on the image of the pointer pressure gauge, use Hough circle transform to detect all candidate circles with the same center and obtain their corresponding center coordinates and radius values; sort all detected candidate circles in descending order according to their radius values; based on the radius distribution characteristics of the candidate circles, select the circles with the second and third radius values ​​as the scale line rings representing the main scale range.

[0053] Step 4.2: Use the Hough transform to extract straight lines within the dial area, and form an initial set in descending order of line segment length. Secondly, traverse the set. L Calculate the included angle of all straight line combinations. The threshold range of the pointer tip angle is limited to 1. Select a pair of lines that meet the conditions. For the pairs of lines that meet the constraints, calculate the intersection point using Formula 1, and use the line connecting the intersection point and the center of the dial as the pointer line:

[0054] (1).

[0055] Step 5: Polar coordinate expansion of the scale ring. Based on the scale ring, after constructing a mask for the non-scale area of ​​the annular scale line, polar coordinate expansion is performed.

[0056] In embodiments of the present invention, such as Figure 3 As shown, step 5 includes:

[0057] Step 5.1: Based on the tick mark ring obtained after constructing the mask, expand its polar coordinates according to Formula 2:

[0058] (2);

[0059] in, Let the radius be the inner circle radius. Let the radius be the outer circle. W The width of the rectangle. H The height of the rectangle. The ordinate of the unfolded rectangular plane is given by [reference]. u Let x be the x-coordinate of the unfolded rectangular plane. Polar coordinates;

[0060] Step 5.2: After polar coordinate transformation, the diagonal tick marks in the original image are converted into vertical straight lines in polar coordinate expansion. A custom convolutional kernel filter is used in the edge detection stage to detect the tick marks. The form of the custom convolutional kernel filter is as follows: .

[0061] Step 6: Calculate the reading of the pointer pressure gauge.

[0062] In embodiments of the present invention, such as Figure 4 As shown, step 6 includes:

[0063] Calculate the reading of the pointer pressure gauge using Formula 3:

[0064] (3);

[0065] in, This represents the total number of tick marks the pointer has passed. , These are the upper and lower limits of the pressure gauge's measurement range. N This represents the total number of scale marks on the dial. , L The length of the tick mark interval currently held by the pointer. L 0 represents the distance of the current pointer from the starting tick mark of the current tick interval.

[0066] In embodiments of the present invention, such as Figure 5 As shown, the image to be tested was segmented to obtain images of a digital pressure gauge and an analog pressure gauge, and the test results were 0.2035 MPa and 0.2027 MPa, respectively.

[0067] Figure 6 This is a schematic diagram of an identification device for pressure gauge inspection and testing provided in an embodiment of the present invention. This device is used to implement the aforementioned identification method for pressure gauge inspection and testing, such as... Figure 6As shown, the device includes: a digital pressure gauge, a pointer pressure gauge, a ring light source, a mounting platform, a camera, and an air hose connector; the pointer pressure gauge is fixed to the mounting platform by a quick-connect nut; the camera is used to acquire images of both the digital and pointer pressure gauges; the ring light source is used to process the light to eliminate interference from dial reflections, thus solving the problem of visual recognition interference; the air hose connector is used to connect to a standard air source.

[0068] This invention utilizes a single-camera machine vision system to identify the readings of two pressure gauges. During pressure gauge calibration, the readings of a digital pressure gauge (standard gauge) and a pointer pressure gauge (test gauge) are typically read simultaneously at specific times. The standard gauge is usually a high-precision digital pressure gauge. This invention adds a machine vision system to a common calibration device. By acquiring images of both gauges with a single camera, it identifies the readings of the digital pressure gauge (standard gauge) and the pointer pressure gauge (test gauge) and calculates the reading deviation. This achieves rapid, synchronous, and automated identification and reading of the two gauge readings, significantly improving the efficiency and accuracy of pressure gauge calibration, effectively meeting metrological verification requirements, and providing technical support for the intelligent upgrading of pressure instrument calibration.

[0069] Compared with manual calibration and existing intelligent pressure gauge detection, this invention solves the problems of pressure gauge dial reflection, inability to simultaneously identify dual pressure gauges, low efficiency and fatigue associated with manual calibration, and provides a practical solution for the metrology bureau to carry out pressure gauge calibration.

[0070] The technical solution provided by this invention includes a method that involves acquiring images of both a digital pressure gauge and a pointer pressure gauge using a single camera, and performing image segmentation; preprocessing the image of the pointer pressure gauge; identifying the range and digital pressure reading of the pointer pressure gauge by constructing a character recognition model based on the PaddleOCR library; identifying the scale ring and pointer by performing Hough circle transform and linear Hough transform detection on the image of the pointer pressure gauge, and obtaining the scale ring and pointer by setting a threshold; expanding the scale ring in polar coordinates, and after constructing a mask for the non-scale area of ​​the annular scale ring based on the scale ring, performing polar coordinate expansion; and calculating the reading of the pointer pressure gauge. This method overcomes the uncertainty and human error inherent in manual reading, achieves synchronous recognition of the dual pressure gauge readings, and improves the accuracy and efficiency of recognition.

[0071] The various steps in the embodiments of the present invention can be performed by an electronic device. This electronic device includes, but is not limited to, tablet computers, portable PCs, and desktop computers.

[0072] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the electronic device containing the computer-readable storage medium to perform the above-described identification method for pressure gauge inspection and testing.

[0073] Figure 7 A schematic diagram of an electronic device provided in an embodiment of the present invention, such as... Figure 7 As shown, the electronic device 21 includes a processor 211, a memory 212, and a computer program 213 stored in the memory 212 and executable on the processor 211. When the computer program 213 is executed by the processor 211, it implements the identification method for pressure gauge inspection and testing in the embodiment. To avoid repetition, it will not be described in detail here.

[0074] Electronic device 21 includes, but is not limited to, processor 211 and memory 212. Those skilled in the art will understand that... Figure 7 This is merely an example of electronic device 21 and does not constitute a limitation on electronic device 21. It may include more or fewer components than shown, or combine certain components, or different components. For example, electronic device may also include input / output devices, network access devices, buses, etc.

[0075] The processor 211 may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor.

[0076] The memory 212 can be an internal storage unit of the electronic device 21, such as a hard disk or RAM of the electronic device 21. The memory 212 can also be an external storage device of the electronic device 21, such as a plug-in hard disk, Smart Media Card (SMC), Secure Digital (SD) card, or FlashCard equipped on the electronic device 21. Furthermore, the memory 212 can include both internal and external storage units of the electronic device 21. The memory 212 is used to store computer programs and other programs and data required by network devices. The memory 212 can also be used to temporarily store data that has been output or will be output.

[0077] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for identification of pressure gauge inspection and testing, characterized by, The method comprises: Step 1, acquiring the image of the dual pressure gauge of the digital pressure gauge and the pointer pressure gauge by using a single camera, and performing image segmentation; in the detection process, the digital pressure gauge and the pointer pressure gauge are located on both sides, and two pressure gauges are segmented from the middle of the image, wherein the digital pressure gauge is a standard gauge, and the pointer pressure gauge is a to-be-detected gauge; Step 2, image preprocessing, preprocessing the image of the pointer pressure gauge; Step 3, OCR recognition, constructing a character recognition model based on the PaddleOCR library to recognize the range of the pointer pressure gauge and the digital pressure gauge; Step 4, recognizing the scale circle and the pointer, performing Hough circle transformation detection and straight line Hough transformation detection on the image of the pointer pressure gauge, and obtaining the scale circle and the pointer by setting a threshold value; Step 5, scale line polar coordinate expansion, according to the scale circle, constructing a mask for the non-scale area of the ring scale line, and then performing polar coordinate expansion; Step 6, calculating the reading of the pointer pressure gauge; The step 4 comprises: Step 4.1, based on the image of the pointer pressure gauge, detecting all candidate circles with the same center by using Hough circle transformation to obtain the corresponding center coordinates and radius values; sorting all detected candidate circles in descending order according to their radius values; based on the radius distribution characteristics of the candidate circles, selecting the circles with the 2nd and 3rd radius values as the scale circle of the main scale range; Step 4.2, extract lines in the dial region using the straight line Hough transform and form an initial set in descending order of line segment length Secondly, traverse all line combinations in the set L to calculate their included angles , limit the angle threshold range of the pointer tip to , and select a set of lines that meet the conditions. For the line pair that meets the constraints, calculate the intersection point by formula 1, and take the line connecting the intersection point and the center of the dial as the pointer line: （1）； The step 5 comprises: Step 5.1, based on the scale circle obtained after constructing the mask, expanding the scale circle according to formula 2: （2）； wherein, is the inner circle radius, is the outer circle radius, W is the rectangular width, H is the rectangular height, is the longitudinal coordinate of the rectangular plane after unfolding, u is the transversal coordinate of the rectangular plane after unfolding, is the polar coordinate system coordinate; Step 5.2, after polar coordinate transformation, the slanting scale line in the original image is converted into a vertical straight line in the polar coordinate expansion, and a self-defined convolution kernel filter is used in the edge detection link to detect the scale line, and the form of the self-defined convolution kernel filter is ; The step 6 comprises: The reading of the pointer pressure gauge is calculated by formula 3: （3）； wherein, is the total number of scale divisions passed by the pointer, , are the upper and lower limits of the pressure gauge measurement range, N is the total number of scale divisions of the dial, , L is the length of the scale interval in which the current pointer is located, L 0 is the distance of the current pointer from the start scale division of the scale interval in which it is located.

2. The method of claim 1, wherein, The step 2 comprises: Firstly, removing noise from the image of the pointer pressure gauge by Gaussian blur; secondly, performing grayscale processing on the image to reduce the calculation amount; finally, binarizing the grayscale image by adaptive threshold segmentation.

3. An identification device for pressure gauge inspection and testing, characterized in that, The device is used to implement the identification method for pressure gauge inspection and test according to any one of claims 1 to 2, and the device comprises a digital pressure gauge, a pointer pressure gauge, a ring light source, a mounting platform, a camera and a gas pipe joint; wherein the pointer pressure gauge is fixed on the mounting platform by a quick-connection nut; the camera is used to acquire the image of the dual pressure gauge of the digital pressure gauge and the pointer pressure gauge; the ring light source is used to process light to eliminate dial plate reflection interference; and the gas pipe joint is used to connect a standard gas source.

4. A computer-readable storage medium, characterized in that, The computer-readable storage medium comprises a stored program, wherein the program controls the device where the computer-readable storage medium is located to execute the identification method for pressure gauge inspection and test according to any one of claims 1 to 2 when the program is running.

5. An electronic device, comprising: Comprise: One or more processors; Memory; And one or more computer programs, wherein the one or more computer programs are stored in the memory, and the one or more computer programs comprise instructions which, when executed by the device, cause the device to execute the identification method for pressure gauge inspection and test according to any one of claims 1 to 2.

Images