Pointer type simulation meter verification system and method based on machine vision

Abstract

The invention provides a pointer type simulation meter verification system and verification method based on machine vision, and relates to the technical field of metrological verification. The system comprises an industrial CCD camera, a controller, an image acquisition module, a communication input and output module, a computer, a multifunctional source and a printer, the verification method is automatically realized through the whole process of image acquisition, preprocessing, pointer and scale identification, error calculation and conclusion generation. The core innovation lies in that multi-algorithm fusion of a subtraction method, image refinement and scale correction is adopted, and in combination with the design of an in-situ adaptive fixing bracket, the pain points of limited field observation, large workload and emergency tasks are solved. The verification point identification precision of the system is greater than or equal to 99.8%, the verification time of a single meter is shortened by more than 60%, the system is suitable for multi-meter and multi-verification-point verification requirements of military power supply vehicles, charging cabinets and other scenes, and the field metering guarantee efficiency and accuracy are significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of metrological verification, in particular to a pointer type analog meter verification system and method based on machine vision. BACKGROUND

[0002] The military aircraft power supply vehicle, charging cabinet and other equipment are the core support equipment to ensure the combat effectiveness of military aircraft. A single power supply vehicle is equipped with 7 voltage meters, ammeters and frequency meters, and a single charging cabinet is equipped with 20 voltage meters and ammeters. Each pointer type analog meter contains at least 10 verification points, and the on-site metrological support workload is extremely large.

[0003] The existing pointer type analog meter verification mainly relies on manual operation: reading the indication value by manually observing the pointer position, comparing with the standard signal to calculate the error, manually recording the data and generating the report. This method has the following defects: Limited by the on-site environment: the instruments are installed in scattered positions in the military equipment, and the observation space is small, so visual deviation is easy to occur when reading the indication value manually; Low efficiency: multiple instruments and multiple verification points result in long verification period, which cannot meet the urgent metrological support task requirements; Large human error: the reading and calculation error is difficult to control due to the dependence on the experience of the verification personnel, which affects the verification accuracy; Complicated recording: manual filling of the original record is prone to errors and difficult to trace, which does not meet the requirements of standardized metrological management.

[0004] Although the machine vision technology has been applied to some metrological fields, the adaptability design for the military in-situ pointer type analog meter is insufficient, and there is a lack of deep integration with the military verification regulation GJB124-2005, which cannot solve the core problems of on-site limitation, multiple table parallel and rapid verification.

[0005] Therefore, developing a machine vision verification system and method which is suitable for military scenes, has high automation degree and reliable precision has become the key to improving the metrological support capability of military equipment. SUMMARY

[0006] In view of the defects of the prior art, the present application provides a pointer type analog meter verification system and method based on machine vision, which is suitable for the metrological verification of the pointer type analog meters such as voltage meters, ammeters and frequency meters installed in-situ in military equipment (such as military power supply vehicles and charging cabinets), and can also be applied to the verification of similar instruments in the fields of industry and power, solving the problem that the existing pointer type analog meter verification mainly relies on manual operation, reading the indication value by manually observing the pointer position, comparing with the standard signal to calculate the error, manually recording the data and generating the report, which has the following defects.

[0007] To achieve the above object, the present application is implemented by the following technical scheme: A machine vision-based pointer-type analog meter verification system and verification method, the system comprising an industrial CCD camera, a special fixed support, a controller, an image acquisition module, a communication input / output module, a computer, a multifunctional source, and a printer; The computer integrates image processing software and data processing software; The verification method comprises the following steps: Step one: system deployment The industrial CCD camera is fixed by the special fixed support, so that the camera line of sight is perpendicular to the dial of the pointer-type analog meter to be tested, and the dial fills the image acquisition window; the multifunctional source is connected to the meter to be tested to provide the standard signal required for verification; Step two: parameter configuration The computer software is used to set the basic information of the meter to be tested, the environmental temperature and humidity, the verification point parameters, and the maximum allowable error, and to associate with the GJB124-2005 verification regulation; Step three: image acquisition The controller triggers the industrial CCD camera to acquire the dial image, which is transmitted to the computer through the image acquisition module; Step four: image preprocessing The image processing software sequentially performs image noise reduction, binarization, enhancement, smoothing restoration, and segmentation processing to extract the effective area of the dial; Step five: pointer and scale recognition The subtraction method, image thinning, and scale correction algorithm are used to identify the dial scale and pointer position and obtain the indication value of each verification point; Step six: error calculation and conclusion generation The data processing software calculates the indication error according to the GJB124-2005 regulation, judges whether it meets the maximum allowable error, and outputs the verification conclusion; Step seven: data output The original record is automatically generated, and storage, query, and printer printing are supported.

[0008] Further, the resolution of the industrial CCD camera is ≥50 million pixels, the frame rate is ≥30 fps, the dynamic range is ≥80 dB, and it supports clear acquisition under the condition of low light environment illumination ≥50 lux.

[0009] Further, the special fixed support adopts a telescopic adjustment structure with an adjustment range of 5-30 cm, has horizontal and vertical calibration scales, ensures that the perpendicularity deviation between the camera and the dial is ≤0.5°, and is suitable for in-situ verification scenes in different installation positions.

[0010] Further, in the step four, the image preprocessing further includes image reduction (scaling ratio 0.5-1.0 times adjustable), dial center removal, and abnormal image removal, the abnormal image removal is judged by a gray threshold and a texture feature, and the identification accuracy is greater than or equal to 99%.

[0011] Further, in the step five, the pointer identification adopts an edge detection-straight line fitting-end point positioning process, the scale identification combines gray histogram threshold segmentation and structure pattern matching, and the identification accuracy of the indicating value is less than or equal to ±0.1 graduation value.

[0012] Further, the image processing and data processing software has a visual interactive interface, including software setting, detected table information input, test point configuration, emergency stop, image window, test conclusion display, data management and other function modules.

[0013] Further, in the step six, the indication error calculation is calculated by a comparison method of a standard value and a measured value, the maximum allowable error is automatically matched according to the accuracy level (0.2 level / 0.5 level / 1.0 level) specified in GJB124-2005, the test conclusion is divided into three categories of "qualified", "unqualified" and "pending", and the error exceeding items are marked.

[0014] Further, the communication input and output module supports RS485 and Ethernet double communication protocols, the data transmission delay is less than or equal to 100 ms, one computer can be connected with 1-20 detected tables at the same time, and multiple tables can be tested in parallel.

[0015] The application provides a pointer type analog table test system and a test method based on machine vision. 1. The application provides a pointer type analog table test system and a test method based on machine vision, which solves the problem of limited installation space in the field by using a special adjustable fixing support, ensures that the camera is perpendicular to the dial for collection, the perpendicularity deviation is less than or equal to 0.5°, adapts to the test of instruments in different positions, and integrates the subtraction method, image refinement and scale correction algorithm to solve the problems of pointer and scale adhesion and light interference, and the identification accuracy of the indicating value is less than or equal to ±0.1 graduation value.

[0016] 2. The application provides a pointer type analog table test system and a test method based on machine vision, which has GJB124-2005 full procedure parameters built-in, automatically matches the instrument accuracy level and the maximum allowable error, and completes error calculation and conclusion determination without manual intervention, realizes end-to-end automation from image acquisition, processing and identification to error calculation, record generation and printing, and the test time of a single table is shortened by more than 60%.

[0017] 3. This invention provides a machine vision-based pointer analog meter calibration system and method, which supports the simultaneous connection of 1-20 meters and is suitable for centralized installation scenarios of multiple meters such as charging cabinets, further improving calibration efficiency. The visual interface lowers the operation threshold, and calibration can be completed without professional metrology personnel. The visual interface integrates emergency stop, quick parameter configuration, and data traceability functions, which meet the operational needs of on-site emergency support. Attached Figure Description

[0018] Fig. 1 This is a schematic diagram of the pointer-type analog table calibration system based on machine vision according to the present invention; Fig. 2 This is a flowchart of the verification method of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0022] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0023] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0024] like Figs. 1-2 As shown, this embodiment of the invention provides a machine vision-based pointer-type analog table calibration system and calibration method, the system comprising: Industrial CCD camera: The core image acquisition component, with a resolution of over 5 million pixels, strong adaptability to low light, ensuring clear acquisition of dial images; Dedicated mounting bracket: adjustable from 5-30cm, with horizontal / vertical calibration scale, quickly fixes the camera and ensures accurate acquisition angle, adaptable to in-situ verification space limitations; Controller: Coordinates the working sequence of the camera, multi-function source, and computer, triggers image acquisition and standard signal output, with a response delay of ≤100ms; Image acquisition module: Converts analog / digital images captured by the camera into computer-processable formats and supports real-time transmission; Communication input / output module: adopts RS485 + Ethernet dual protocol to realize data interaction between various components and support parallel communication of multiple devices; Computer: Integrates image processing software and data processing software, serves as the core of human-computer interaction, and is responsible for image processing, data computation, procedure matching, and conclusion generation; Multifunctional source: Provides stable standard voltage, current, and frequency signals to provide the input signals required for the calibration of the instrument under test, with an accuracy class ≥0.05; Printer: Prints original verification records and conclusion reports in real time, and supports paper archiving.

[0025] The verification method includes the following steps: Step 1: System Deployment and Connection Install the special fixed bracket near the table being inspected, and adjust the height and angle of the bracket so that the line of sight of the industrial CCD camera is perpendicular to the surface of the dial, and the dial completely fills the acquisition window. The controller, image acquisition module, and computer are connected via a communication line, and the multi-functional source is connected to the power and signal input terminals of the meter under test.

[0026] Step 2: Parameter Configuration Open the computer software, enter the basic information such as the model, accuracy class, range, and installation location of the meter under test, and input the ambient temperature and humidity. Select the calibration point parameters (≥10 per meter, custom additions are supported), and the software will automatically match the maximum permissible error specified in GJB124-2005 according to the accuracy level.

[0027] Step 3: Standard Signal Output and Image Acquisition When the calibration procedure is started, the controller triggers the multi-function source to output the standard signal of the first calibration point. After the signal stabilizes (stabilization time is adjustable from 0.5 to 2 seconds), the industrial CCD camera is triggered to acquire the dial image, and the image is transmitted to the computer in real time through the acquisition module.

[0028] Step 4: Image Preprocessing Image processing software processes images according to the following process: Image noise reduction: Median filtering algorithm is used to remove environmental noise while preserving pointer and scale details; Binarization: Through adaptive thresholding, grayscale images are converted into black-and-white binary images to highlight the pointer and scale. Image enhancement: Gray-level histogram equalization technology is used to adjust contrast and improve image quality in low light conditions; Smoothing Restoration: Gaussian filtering removes image distortion and restores the original information of the dial; Image segmentation: Based on grayscale threshold and texture features, the effective area of ​​the dial is segmented, and background interference is removed; Auxiliary processing: Image reduction (reducing computational load), dial center removal (avoiding interference from the center marker), and abnormal image removal (identifying blurry / occluded images and re-acquiring them) as needed.

[0029] Step 5: Pointer and Scale Recognition Scale recognition: A structural pattern matching algorithm is used to identify the position of the dial scale lines and their corresponding values, and a scale correction algorithm is used to correct the dial eccentricity error. Pointer recognition: The subtraction method is used to eliminate interference from the dial background. The pointer outline is extracted through edge detection and line fitting. The coordinates of the pointer endpoint are located, and the current calibration point value is calculated by combining the scale position.

[0030] Step Six: Error Calculation and Conclusion Generation The data processing software calls the parameters of GJB124-2005 to calculate the indication error of "standard signal value - measured value" and determine whether the error is within the maximum permissible error range; After verifying all the verification points one by one, the verification conclusions of "qualified", "unqualified" or "pending" are obtained, and the error deviation of the unqualified verification points is marked.

[0031] Step 7: Data Output and Storage The software automatically generates a complete original record containing information about the test form, environmental parameters, values ​​at each test point, errors, and test conclusions, and supports local storage and historical data retrieval. Finally, a paper report is printed using a printer to complete the verification process.

[0032] Implementation Case 1: Calibration of Pointer-Type Voltmeter in Military Power Supply Vehicle ①System Configuration Industrial CCD camera: 5 megapixel resolution, 30fps frame rate, 85dB dynamic range, and 30-1000 lux illuminance range; Dedicated fixing bracket: telescopic range 10-25cm, verticality calibration accuracy ±0.3°; Multifunctional source: accuracy class 0.05, voltage output range 0-600V, current output range 0-10A; The objects under inspection are three voltmeters from a military power supply vehicle, with an accuracy class of 0.5 and a range of 0-380V. Each voltmeter has 10 calibration points: 0V, 38V, 76V, 114V, 152V, 190V, 228V, 266V, 304V, 342V, and 380V.

[0033] ②Verification steps Step 1: Install the mounting bracket near the instrument panel on the power supply vehicle, and adjust the bracket so that the camera is perpendicular to the dial of each voltmeter, and the dial fills the acquisition window. Connect the communication and power lines of each component, and connect the multi-function source to the signal input terminal of the voltmeter.

[0034] Step 2: Open the computer software, enter the model of the meter under test, accuracy class 0.5, range 0-380V, and ambient temperature and humidity. The software will automatically match the maximum permissible error specified in GJB124-2005.

[0035] Step 3: Start the calibration program. The multi-function source outputs the standard voltage of each calibration point in sequence, and the camera simultaneously acquires the dial image. Each meter acquires 11 images, including the 0V calibration point.

[0036] Step 4: The image processing software performs noise reduction, binarization, enhancement, and segmentation on the image, removes one abnormal image caused by reflection, and re-acquires the image.

[0037] Step 5: Extract the readings of each calibration point using the scale calibration and pointer recognition algorithm. The measured reading of the 380V calibration point is 378.5V.

[0038] Step 6: The software calculates the indication error: 380V - 378.5V = 1.5V, which is less than the maximum permissible error of 1.9V; All calibration point errors were within the allowable range, and the calibration conclusion was "qualified".

[0039] Step 7: Generate the original record containing all the verification point data from the three tables, print the paper report, and store the electronic data.

[0040] ③ Implementation Results Verification efficiency: The total verification time for the three meters was 25 minutes, which is 72% shorter than the 90 minutes required for manual verification. Verification accuracy: The indication recognition error is ≤ ±0.3V, which meets the verification requirements of 0.5 grade instruments; On-site adaptability: The bracket is flexibly adjustable to fit the narrow installation space of the power supply vehicle, and the image acquisition is clear in low light conditions; Data standardization: The original records fully comply with the requirements of GJB124-2005 and can be directly used for measurement archiving.

[0041] Implementation Case 2: Verification of Multi-Pointer Ammeter in Charging Cabinet ①System Configuration Similar to Example 1, the computer expands the multi-meter parallel communication module to support the simultaneous verification of 20 ammeters.

[0042] ②The inspected object The charging cabinet contains 20 ammeters, with an accuracy class of 1.0 and a range of 0-50A. Each ammeter has 10 calibration points: 0A, 5A, 10A, 15A, 20A, 25A, 30A, 35A, 40A, 45A, and 50A.

[0043] ③ Implementation Results The total calibration time for 20 watches was 40 minutes, a 93% reduction compared to the 600 minutes required for manual calibration. The accuracy rate of error identification at all verification points is 99.9%, generating unified original records and enabling centralized management of multiple tables.

[0044] The following points should be noted in this article: 1. The accompanying drawings of the embodiments disclosed herein only relate to the structures involved in the embodiments disclosed herein; other structures can be referred to in a general design.

[0045] 2. Where there is no conflict, the embodiments of this disclosure and the features in the embodiments can be combined with each other to obtain new embodiments.

[0046] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents. 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.

Claims

1. A machine vision-based pointer-type analog dial indicator calibration system and calibration method, characterized in that, The system includes an industrial CCD camera, a dedicated mounting bracket, a controller, an image acquisition module, a communication input / output module, a computer, a multi-function source, and a printer; The computer integrates image processing software and data processing software; The verification method includes the following steps: Step 1: System Deployment The industrial CCD camera is fixed with a dedicated bracket, so that the camera's line of sight is perpendicular to the dial of the analog pointer meter under test, and the dial fills the image acquisition window; a multi-functional source is connected to the meter under test to provide the standard signals required for verification. Step 2: Parameter Configuration The basic information of the test form, ambient temperature and humidity, test point parameters, and maximum permissible error are set by computer software, and linked to the GJB124-2005 test procedure. Step 3: Image Acquisition The controller triggers the industrial CCD camera to acquire images of the dial, which are then transmitted to the computer via the image acquisition module. Step 4: Image Preprocessing The image processing software sequentially performs image noise reduction, binarization, enhancement, smoothing restoration, and segmentation to extract the effective area of ​​the dial; Step 5: Pointer and Scale Recognition Using subtraction, image thinning, and scale correction algorithms, the dial scale lines and pointer positions are identified, and the readings at each calibration point are obtained. Step Six: Error Calculation and Conclusion Generation The data processing software calculates the indication error according to the GJB124-2005 standard, determines whether it meets the maximum permissible error, and outputs the verification conclusion. Step 7: Data Output It automatically generates original records and supports storage, retrieval, and printing.

2. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, The industrial CCD camera has a resolution of ≥5 million pixels, a frame rate of ≥30fps, a dynamic range of ≥80dB, and supports clear acquisition in low-light environments with an illumination of ≥50 lux.

3. The machine vision-based pointer-type analog table calibration system and method according to claim 1, characterized in that, The dedicated fixed bracket adopts a telescopic and adjustable structure with an adjustment range of 5-30cm. It has horizontal and vertical calibration scales to ensure that the verticality deviation between the camera and the dial is ≤0.5°, and is suitable for in-situ verification scenarios with different installation positions.

4. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, In step four, image preprocessing also includes image reduction, dial center removal, and abnormal image removal. The abnormal image removal is judged by grayscale threshold and texture features, with an accuracy rate of ≥99%.

5. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, In step five, the pointer recognition adopts the process of "edge detection - straight line fitting - endpoint positioning", and the scale recognition combines gray-level histogram threshold segmentation and structural pattern matching. The accuracy of the verification point indication recognition is ≤ ±0.1 division value.

6. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, The image processing and data processing software has a visual interactive interface, including functional modules such as software settings, input of test form information, configuration of test points, emergency stop, image window, display of test results, and data management.

7. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, In step six, the indication error is calculated using the "standard value - measured value" comparison method. The maximum permissible error is automatically matched according to the accuracy level specified in GJB124-2005. The verification conclusion is divided into three categories: "qualified", "unqualified" and "pending" and the error exceeding the tolerance is marked.

8. The machine vision-based pointer-type analog table calibration system and calibration method according to claim 1, characterized in that, The communication input / output module supports both RS485 and Ethernet communication protocols, with a data transmission delay of ≤100ms. It can enable a single computer to connect to 1-20 test tables simultaneously, supporting parallel testing of multiple tables.

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