A machine vision-based charging auxiliary system and a charging method

Abstract

The present application relates to the field of nuclear fuel operation, in particular to a loading auxiliary system and method based on machine vision. The method comprises the following steps: calibrating a bilateral image acquisition module, and constructing a fitting linear equation of left-right gap pixel difference and offset distance; setting the fuel assembly at a specified height of a standard position; shooting the lower nozzle edge image of the to-be-loaded fuel assembly and the upper nozzle edge image of the loaded fuel assembly from the opposite two sides; calculating the pixel distance of the two edges and the left-right gap pixel difference through an image processing algorithm; calculating the offset distance of the current fuel assembly relative to the central position; controlling the fuel assembly to move back to the central position, and then loading the fuel assembly. The system comprises an image acquisition module and a loading gap measurement control system. The present application is suitable for measuring / judging the relative position of the fuel assembly, guiding the to-be-loaded fuel assembly to move to the central position of the loaded fuel assembly by the loading and unloading machine, so as to ensure the smooth insertion of the to-be-loaded fuel assembly.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear fuel operation, in particular to a loading auxiliary system and a loading method based on machine vision. BACKGROUND

[0002] In the loading process of a nuclear power plant, there are two cases for lowering fuel assemblies in the core: one is offset loading, that is, using the position offset movement of the crane and trolley of the refueling machine to lower the fuel assemblies. When two adjacent sides of the four sides of the fuel assembly to be loaded are not loaded fuel assemblies, offset loading can be used. When offset loading is used, the fuel assembly can be successfully seated with the assistance of the small shoe, and the position accuracy requirement of the fuel assembly to be loaded is relatively low. The other is straight insertion loading, that is, the refueling machine is lowered at the standard coordinate position. When three or four sides of the four sides of the fuel assembly to be loaded are loaded fuel assemblies, the fuel assembly can only be loaded by straight insertion. Since the theoretical size of the fuel assembly lower tube seat is 214mm, and the theoretical distance between the two opposite sides of the fuel assembly to be loaded is 215.04mm, the position accuracy requirement of the fuel assembly to be loaded is relatively high when straight insertion loading is used. If the fuel assembly to be loaded is not at the center position of the two loaded fuel assemblies below, interference will occur and the fuel assembly cannot be successfully inserted.

[0003] At present, when the fuel assembly is straightly inserted and loaded, the positioning of the fuel assembly to be loaded and the safety of the loading process mainly rely on the confirmation of the refueling master through a telescope and personal experience. There is no perfect device for measuring the relative position of the straightly inserted fuel assembly in China. SUMMARY

[0004] The technical problem to be solved by the present application is to provide a loading auxiliary system and a loading method based on machine vision, which measure / judge the relative position of the fuel assembly to be loaded and the loaded fuel assembly under straight insertion loading, guide the refueling machine to move the fuel assembly to be loaded to the center position of the loaded fuel assembly, and ensure that the fuel assembly to be loaded is successfully inserted.

[0005] The present application provides a loading method based on machine vision, comprising the following steps:

[0006] Step S1: calibrate the double-sided image acquisition module, and construct a fitting linear equation of the left-right gap pixel difference and the offset distance;

[0007] Step S2: set the fuel assembly at a specified height of the standard position;

[0008] Step S3: respectively shoot the lower tube seat edge image of the fuel assembly to be loaded and the upper tube seat edge image of the loaded fuel assembly from the opposite two sides;

[0009] Step S4: calculate the pixel distance of the two edges and the left-right gap pixel difference by an image processing algorithm.

[0010] Step S5: According to the obtained left-right gap pixel difference and the calibration result, the offset distance of the current fuel assembly relative to the centered position is calculated;

[0011] Step S6: The fuel assembly is controlled to move back to the centered position, and the next loading is performed.

[0012] In a specific embodiment of the present application, the step S1 is specifically:

[0013] Step S100: The loading and unloading machine reaches the standard coordinate position;

[0014] Step S101: The fuel assembly is lowered to a specified height;

[0015] Step S102: The left and right gaps are photographed respectively, and the left-right gap pixel difference in the image is calculated and taken as the initial value b0 of the left-right gap pixel difference when the fuel assembly is centered;

[0016] Step S103: The fuel assembly is kept at the same height and is horizontally moved by a unit distance to one side gap direction;

[0017] Step S104: The measuring unit photographs the left and right gaps, calculates and records the left-right edge pixel difference in the image and the corresponding offset distance;

[0018] Step S105: If the number of offsets is less than N, return to step S103; the N is not less than 5;

[0019] If the number of offsets is greater than or equal to N, the next step is performed;

[0020] Step S106: According to the calculated left-right gap pixel difference and the corresponding offset distance, a linear equation Y=kX+b0 is fitted;

[0021] The abscissa is the offset distance, and the ordinate is the corresponding gap difference;

[0022] Step S107: The fuel assembly is translated to the standard coordinate position;

[0023] Step S108: The fuel assembly is manually observed to be inserted;

[0024] Step S109: Whether the fuel assembly can be smoothly inserted at the standard position is observed, and if so, the calibration is completed;

[0025] If the fuel assembly cannot be smoothly inserted due to stacking, the position of the fuel assembly is adjusted until it can be inserted, and the offset amount x1 of the smoothly inserted fuel assembly relative to the standard position is recorded;

[0026] Step S110: The calibration result b0 is corrected to b0'=kx1+b0.

[0027] In a specific embodiment of the present application, in the step S103, the unit distance is 2-3mm.

[0028] In a specific embodiment of the present application, in the step S103, the direction of the horizontal movement can be positive or negative.

[0029] The positive direction is 0° and 90°.

[0030] In a specific embodiment of the present application, in the step S3, the image acquisition module height during shooting is the same as the fuel assembly height.

[0031] In a specific embodiment of the present application, in the step S3, the vertical distance of the image acquisition module from the shooting position is much greater than the horizontal distance.

[0032] The present application also provides a machine vision-based loading auxiliary system, comprising: an image acquisition module, a loading gap measurement control system;

[0033] The image acquisition module is arranged on the 0° and 180° two sides of the loading and unloading trolley rail, or the trolley bottom, or the fixed sleeve, etc.

[0034] The loading gap measurement control system is used for controlling the image acquisition module and the installation gap measurement software, and is connected with the image acquisition module through a cable to receive the shooting picture in real time and calculate the measurement result.

[0035] In a specific embodiment of the present application, the image acquisition module comprises four sets of image acquisition units, each set of image acquisition unit is composed of one high-definition camera and one camera holder, and the image acquisition unit adopts the water shooting mode or the underwater shooting mode.

[0036] In a specific embodiment of the present application, the loading gap measurement control system comprises a holder control module, a camera control module, a calibration module and an offset distance measurement module.

[0037] Compared with the prior art, the machine vision-based loading auxiliary system and the loading method of the present application can determine the two-side gap of the to-be-loaded straight-insertion fuel assembly by acquiring the shooting image, judge whether the fuel assembly is centered according to the gap difference in the shooting image, and quantitatively calculate the offset amount of the to-be-loaded fuel assembly relative to the centered position, which fills the blank in the field of quantitative measurement of the loading gap of the straight-insertion fuel assembly in China.

[0038] The charging auxiliary system can replace the current charging method of observing the fuel assembly gap on both sides by the charging supervisor through the telescope and judging whether the fuel assembly is centered according to the personal experience of the supervisor, thereby reducing the dependence on the personal experience of the charging supervisor, reducing the workload of the charging supervisor, facilitating the reduction of the key path of the overhaul charging, and providing technical reserves for the realization of the charging automation. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A flowchart of a machine vision-based charging method is shown;

[0040] Figure 2 A flowchart of an image acquisition module calibration is shown;

[0041] Figure 3 A structure diagram of a machine vision-based charging auxiliary system is shown;

[0042] Figure 4 A measurement diagram of a machine vision-based charging auxiliary system is shown;

[0043] In the drawings,

[0044] 1 - image acquisition module, 2 - cable, 3 - gap measurement control system, 4 - first image acquisition unit, 5 - second image acquisition unit, 6 - to-be-charged assembly, 7 - first charged assembly, 8 - second charged assembly. DETAILED DESCRIPTION

[0045] In order to further understand the present application, the embodiments of the present application are described below in combination with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, but not for limiting the present application.

[0046] In the present application, the pixel distance of the two edges refers to the distance between the lower nozzle seat edge of the to-be-charged fuel assembly and the upper nozzle seat edge of the charged fuel assembly, for example, the distance between the left lower nozzle seat edge of the to-be-charged fuel assembly and the upper nozzle seat edge of the charged fuel assembly on the left side, and the distance between the right lower nozzle seat edge of the to-be-charged fuel assembly and the upper nozzle seat edge of the charged fuel assembly on the right side.

[0047] The left-right gap pixel difference refers to the difference between the pixel distance of the two edges on the left side and the pixel distance of the two edges on the right side.

[0048] The embodiments of the present application disclose a machine vision-based charging method, as shown in Figure 1 The method comprises the following steps:

[0049] Step S1: calibrate the double-sided image acquisition module, and construct a fitting linear equation of the left-right gap pixel difference and the offset distance;

[0050] AsFigure 2 As shown, in particular:

[0051] Step S100: The loading and unloading machine reaches the standard coordinate position;

[0052] Step S101: The fuel assembly is lowered to a specified height;

[0053] Since the image gap in the image changes with the change of the height of the fuel assembly, in order to maintain consistency, the image acquisition module calibration and the fuel assembly measurement are performed at the same height, including but not limited to the lowering of the telescopic sleeve from the fast zone to the slow zone position.

[0054] Step S102: The left and right gaps are photographed respectively, and the pixel difference of the left and right gaps in the image is calculated and taken as the initial value b0 of the pixel difference of the left and right gaps when the fuel assembly is centered;

[0055] Step S103: The fuel assembly height remains unchanged, and the horizontal movement unit distance is moved to one side gap direction;

[0056] The unit distance is 2-3 mm;

[0057] The direction of the horizontal movement can be positive or negative, including but not limited to 0° and 90° as two directions of the positive direction.

[0058] Step S104: The measurement unit photographs the left and right gaps, calculates and records the pixel difference of the left and right edges in the image and the corresponding offset distance;

[0059] Step S105: If the offset number is less than N, return to step S103; the N is not less than 5;

[0060] If the offset number is greater than or equal to N, the next step is executed;

[0061] Step S106: According to the calculated left and right gap pixel difference and the corresponding offset distance, a linear equation Y=kX+b0 is fitted;

[0062] The abscissa is the offset distance, and the ordinate is the corresponding gap difference;

[0063] Wherein k represents the change amount of the image gap difference corresponding to the offset of 1 mm of the fuel assembly; b0 represents the image gap difference of the fuel assembly when it is centered;

[0064] Step S107: The fuel assembly is translated to the standard coordinate position;

[0065] Step S108: Artificial observation of the fuel assembly insertion;

[0066] Step S109: Observation of whether the fuel assembly can be smoothly inserted at the standard position, if yes, the calibration is completed;

[0067] If the fuel assembly cannot be inserted smoothly, the position of the fuel assembly is adjusted until it can be inserted, and the offset x1 of the fuel assembly from the standard position is recorded when it is inserted smoothly;

[0068] Step S110: The calibration result b0 is corrected to b0'=kx1+b0.

[0069] If the fuel assembly is inserted smoothly after translation, it indicates that the fuel assembly is not in the center position at the standard position, and the calibrated b0 is not the gap difference at the center position. Therefore, b0 is corrected to b0'=kx1+b0 according to the calibrated k in step S106 and the offset x1 of the fuel assembly from the standard position when it is inserted, and the calibration of the image acquisition module is completed.

[0070] Step S2: The fuel assembly is set at a specified height of the standard position;

[0071] Step S3: The lower nozzle edge image of the fuel assembly to be installed and the upper nozzle edge image of the fuel assembly already installed are respectively photographed from the opposite two sides;

[0072] Step S4: The pixel distance of the two edges and the left-right gap pixel difference b1 are calculated through an image processing algorithm;

[0073] Step S5: The offset distance of the current fuel assembly from the center position is calculated according to the obtained left-right gap pixel difference b1 and the calibration result.

[0074] The calibration result includes k, b0 or b0';

[0075] The calculation method is to use the above fitting linear equation, X=(b1-b0) / k or X=(b1-b0') / k.

[0076] According to the calibration result of the fuel assembly and the gap difference of the current fuel assembly, the offset direction and size of the fuel assembly from the center position can be calculated, and the corresponding offset of the fuel handling machine is guided, so that the fuel assembly returns to the center position to be inserted smoothly.

[0077] Step S6: The fuel assembly is controlled to move back to the center position and be inserted.

[0078] Embodiments of the present application also disclose a loading auxiliary system based on machine vision, as shown in Figure 3 The loading auxiliary system based on machine vision comprises an image acquisition module 1 and a loading gap measurement control system 3.

[0079] The image acquisition module 1 is arranged on the 0° and 180° side rail of the fuel handling trolley, or the bottom of the trolley, or a fixed sleeve.

[0080] The charging gap measurement control system 3 is used for controlling the image acquisition module 1 and installing the gap measurement software, and is connected with the image acquisition module 1 through the cable 2 to receive the shooting screen in real time and calculate the measurement result.

[0081] The image acquisition module 1 includes four sets of image acquisition units for acquiring images of fuel assemblies to be measured, including but not limited to a combination of a gimbal and an industrial camera, a digital camera and a spherical camera.

[0082] Optionally, each set of image acquisition unit is composed of one high-definition camera and one camera gimbal. The image acquisition unit can adopt an overwater shooting mode or an underwater shooting mode.

[0083] The four sets of image acquisition units are respectively installed on the 0° and 180° side railings of the fuel handling machine trolley, or the bottom of the trolley, or the fixed sleeve, to realize shooting of all straight-inserted fuel assemblies.

[0084] The charging gap measurement control system 3 is placed on the fuel handling machine trolley and connected with the four sets of image acquisition units through the cable 2.

[0085] The charging gap measurement control system includes a gimbal control module, a camera control module, a calibration module and an offset distance measurement module.

[0086] The gimbal control module is used for adjusting the angle of the camera before measurement to achieve a good shooting angle. The camera control module is used for adjusting the camera parameters and controlling the camera to trigger the acquisition of the fuel assembly gap image. The calibration module is used for calibrating the pixel difference of the gap in the images shot by the two sets of image acquisition units when the fuel assembly is centered and the proportional relationship between the pixel difference of the gap and the offset distance of the fuel assembly. The offset distance measurement module is used for calculating the offset distance of the current fuel assembly according to the image gap pixel difference of the fuel assembly to be measured and the calibrated parameters.

[0087] Reference Figure 4 Two groups of image acquisition units are arranged on both sides of the fuel assembly to be loaded, and the images of the lower tube seat of the fuel assembly to be loaded and the upper tube seat of the fuel assembly already loaded are shot when the fuel assembly to be loaded is lowered to a specified height. Then the pixel distance of the two edges is calculated through the image processing algorithm, and the pixel difference of the distance of the two edges is calculated. Two sets of image acquisition units are needed to measure a single fuel assembly, and when measuring on site, two groups of image acquisition units can be combined in four groups according to the shielding of the pressure vessel to different fuel assemblies.

[0088] The working principle of the system is that two image acquisition units respectively shoot the upper tube seat edge of the installed fuel assembly on both sides of the to-be-installed fuel assembly and the lower tube seat edge of the to-be-installed fuel assembly, and calculate the gap value of the two edges. When the vertical distance of the image acquisition unit from the shot position is much larger than the horizontal distance, if the fuel assembly moves horizontally at the same height, the gap between the fuel assemblies shot by the two image acquisition units will change at the same time. When the moving distance is small, the change amount of the gap difference between the two image acquisition units is in linear proportion to the moving distance of the to-be-installed fuel assembly. Therefore, the image acquisition unit can be fixedly installed on the charging and discharging machine trolley, and shot when the to-be-installed fuel assembly is lowered to the same height. At this time, the position of the to-be-installed fuel assembly remains unchanged when the image acquisition unit is shot, so the gap difference between the two sides of the fuel assembly should also remain unchanged. The initial gap difference between the two sides of the fuel assembly when the fuel assembly is centered and the relationship between the gap difference change amount and the fuel assembly displacement are calibrated by the first group of straight insertion fuel assemblies. When the subsequent straight insertion fuel assembly is inserted, the difference between the gap difference and the initial gap difference is calculated, and the displacement distance of the fuel assembly is determined according to the relationship between the gap difference change amount and the displacement of the fuel assembly, so as to guide the charging and discharging machine to move the to-be-installed fuel assembly to the middle position of the installed fuel assembly.

[0089] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be noted that, for those skilled in the art, without departing from the principles of the present application, some improvements and modifications can be made to the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

[0090] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A loading method based on machine vision, characterized in that, Includes the following steps: Step S1: Calibrate the dual-sided image acquisition modules and construct a fitted linear equation for the pixel difference between the left and right gaps and the offset distance; Specifically: Step S100: The loading and unloading machine reaches the standard coordinate position; Step S101: The fuel assembly descends to the designated height; Step S102: Take pictures of the gaps on the left and right sides respectively, and calculate the pixel difference between the left and right gaps in the image, and use it as the initial value of the pixel difference b0 between the left and right gaps when the fuel assembly is centered; Step S103: Keeping the fuel assembly height unchanged, move it horizontally a unit distance in the gap direction to one side; Step S104: The measurement unit takes pictures of the gaps on the left and right sides, calculates and records the pixel difference between the left and right edges in the image and the corresponding offset distance; Step S105: If the number of offsets is less than N, then return to step S103; where N is not less than 5; If the offset count is greater than or equal to N, proceed to the next step; Step S106: Based on the calculated left and right gap pixel difference and the corresponding offset distance, fit the linear equation Y=kX+b0; The horizontal axis represents the offset distance, and the vertical axis represents the corresponding gap difference. Step S107: The fuel assembly is translated to the standard coordinate position; Step S108: Manually observe the insertion of the fuel assembly; Step S109: Observe whether the fuel assembly can be successfully inserted in the standard position. If it is successfully inserted, the calibration is complete. If the fuel assembly is stacked and cannot be inserted smoothly, adjust the position of the fuel assembly until it can be inserted, and record the offset x1 of the fuel assembly being successfully inserted relative to the standard position. Step S110: Correct the calibration result b0 to b0' = kx1 + b0; Step S2: Position the fuel assembly at the specified height in the standard position; Step S3: Take images of the edge of the lower pipe socket of the fuel assembly to be installed and the edge of the upper pipe socket of the installed fuel assembly from two opposite sides; Step S4: Calculate the pixel distance between the two edges and the pixel difference between the left and right gaps using an image processing algorithm; Step S5: Based on the obtained left and right gap pixel difference and calibration results, calculate the offset distance of the current fuel assembly relative to the center position; Step S6: Control the movement of the fuel assembly to return to the center position and perform the lower insertion and loading.

2. The machine vision-based loading method according to claim 1, characterized in that, In step S103, the unit distance is 2-3 mm.

3. The machine vision-based loading method according to claim 1, characterized in that, In step S103, the direction of the horizontal movement is either positive or negative. 0° and 90° are considered the positive directions.

4. The machine vision-based loading method according to claim 1, characterized in that, In step S3, the height of the image acquisition module during shooting is the same as the height of the fuel assembly.

5. The machine vision-based loading method according to claim 4, characterized in that, In step S3, the vertical distance between the image acquisition module and the shooting location is greater than the horizontal distance.

6. A machine vision-based loading assistance system for performing the method according to any one of claims 1 to 5, characterized in that, include: Image acquisition module, loading gap measurement and control system; The image acquisition module is installed on the railings at 0° and 180° on both sides of the loading and unloading trolley, or at the bottom of the trolley, or on the fixed sleeve; The loading gap measurement and control system is used to control the image acquisition module and the installation gap measurement software, and is connected to the image acquisition module via a cable to receive the captured images in real time and calculate the measurement results.

7. The machine vision-based loading assistance system according to claim 6, characterized in that, The image acquisition module contains four sets of image acquisition units. Each set of image acquisition units consists of one high-definition camera and one camera gimbal. The image acquisition units adopt either a surface shooting mode or an underwater shooting mode.

8. The machine vision-based loading assistance system according to claim 7, characterized in that, The loading gap measurement and control system includes a gimbal control module, a camera control module, a calibration module, and an offset distance measurement module.

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