CN114092560A - Back-drilled hole two-dimensional/three-dimensional characteristic measurement system, method and device - Google Patents

Back-drilled hole two-dimensional/three-dimensional characteristic measurement system, method and device Download PDF

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CN114092560A
CN114092560A CN202111457821.4A CN202111457821A CN114092560A CN 114092560 A CN114092560 A CN 114092560A CN 202111457821 A CN202111457821 A CN 202111457821A CN 114092560 A CN114092560 A CN 114092560A
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dimensional
hole
drilling hole
back drilling
circuit
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雷志辉
陈状
周翔
郑如寿
李秀懂
傅丹
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Shenzhen Eagle Eye Online Electronics Technology Co ltd
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Shenzhen Eagle Eye Online Electronics Technology Co ltd
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    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
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    • G06T7/00—Image analysis
    • G06T7/70—Determining position or orientation of objects or cameras
    • G06T7/73—Determining position or orientation of objects or cameras using feature-based methods
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B11/00—Measuring arrangements characterised by the use of optical techniques
    • G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06F—ELECTRIC DIGITAL DATA PROCESSING
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    • G06T7/00—Image analysis
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    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T7/00—Image analysis
    • G06T7/10—Segmentation; Edge detection
    • G06T7/136—Segmentation; Edge detection involving thresholding
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
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    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/10—Image acquisition modality
    • G06T2207/10004—Still image; Photographic image
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    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
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    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/20—Special algorithmic details
    • G06T2207/20004—Adaptive image processing
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T2207/00—Indexing scheme for image analysis or image enhancement
    • G06T2207/20—Special algorithmic details
    • G06T2207/20092—Interactive image processing based on input by user
    • G06T2207/20104—Interactive definition of region of interest [ROI]
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
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Abstract

The invention relates to a two-dimensional/three-dimensional characteristic measuring system of a back drilling hole, which comprises: the image acquisition device acquires two-dimensional real-time images and three-dimensional actual height images of the circuit board with the back drilling holes through the movement of the motion platform at equal intervals; the position acquisition device performs fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling holes to obtain position information of each back drilling hole on the two-dimensional real-time image; the back drilling hole center extraction device acquires an interested area image of the position of each back drilling hole according to the position of each back drilling hole in the two-dimensional real-time image; the back drill hole inner and outer boundary processing device performs double threshold segmentation according to the center of a back drill hole to obtain the inner and outer boundaries of the back drill hole and obtain the position relation between the circle center of the inner and outer boundaries; and the characteristic parameter generating device calculates the characteristic parameters of the back drilling hole on the three-dimensional actual height image. The invention also discloses a back drilling hole two-dimensional/three-dimensional characteristic measuring method and a back drilling hole two-dimensional/three-dimensional characteristic measuring device.

Description

Back-drilled hole two-dimensional/three-dimensional characteristic measurement system, method and device
Technical Field
The invention relates to the technical field of optical measurement, in particular to a back drilling hole two-dimensional/three-dimensional characteristic measurement system, a back drilling hole two-dimensional/three-dimensional characteristic measurement method and a back drilling hole two-dimensional/three-dimensional characteristic measurement device.
Background
The circuit board is used as a substrate for carrying electronic elements and has wide application in the electronic field, and the main structure of the circuit board can be divided into two blocks due to the wiring requirements of different electronic products, wherein the circuit board can be divided into a single panel, a double-sided board, a multilayer board and a flexible board according to the number of layers; and secondly, the production process is divided into copper plates, tin spraying plates, halogen-free plain plates, gold immersion plates, nickel plating plates, aluminum substrates and the like. Among them, a wiring board, which is a circuit board having inter-point connections and printed elements formed on a common substrate in a predetermined design and mainly functions to connect various electronic components to a predetermined circuit, has attracted attention as a carrier for electrical connection of electronic components. The circuit board is used as an important electronic component and is widely applied to different fields, wherein the fields comprise consumer electronics, automotive electronics, semiconductor packaging, network communication, aerospace and the like, especially the demand of automotive electronics is greatly increased along with the rapid development of new energy vehicles, and in addition, the demand of consumer electronics and semiconductor packaging on the circuit board is also large.
However, the existing production process of the circuit board is not mature, and especially, process detection of relevant parameters of backdrilling (Backdrill) in the circuit board has many problems, which also restricts the working efficiency of the circuit board production line.
Disclosure of Invention
In view of the defects of the prior art, the present application aims to provide a two-dimensional/three-dimensional feature measurement system for a back-drilled hole, and aims to solve the problems of low detection efficiency and poor accuracy of the roundness, the back-drilled height and the like of a back-drilled hole of a circuit board in the existing detection system.
A backdrilled hole two/three dimensional feature measurement system comprising: the image acquisition device is used for acquiring a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole through the movement of the motion platform at equal intervals; the position acquisition device is electrically connected with the image acquisition device and is used for performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling holes to obtain the position information of each back drilling hole on the two-dimensional real-time image, and constructing the position information of each back drilling hole on the two-dimensional real-time image and preset standard data of a circuit board back drilling hole manufacturing plate into a corresponding position conversion model to obtain the position of each back drilling hole in the two-dimensional real-time image; the back drilling hole center extracting device is electrically connected with the position acquiring device and is used for acquiring an interested area image of the position of each back drilling hole according to the position of each back drilling hole in the two-dimensional real-time image and acquiring the center of each back drilling hole; the back-drilling inner and outer boundary processing device is electrically connected with the back-drilling center extracting device and used for carrying out dual threshold segmentation according to the center of the back drilling hole to obtain the inner and outer boundaries of the back drilling hole, calculating two-dimensional technological parameters of the inner and outer circle centers of the back drilling hole and converting the two-dimensional technological parameters of the back drilling hole into actual numerical parameters under a first coordinate system to obtain the position relation between the inner and outer boundary circle centers and the inner and outer boundaries; and the characteristic parameter generating device is electrically connected with the back drilling hole inner and outer boundary processing device and is used for calculating the characteristic parameters of the back drilling hole on the three-dimensional actual height image transmitted by the image acquisition device according to the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
Optionally, the image acquisition device includes a camera and a line laser, wherein the line laser emits a laser line, and an included angle between the line laser and the camera is a preset angle.
Optionally, the position obtaining device includes a contour point calculating circuit, a feature hole obtaining circuit, a matching result obtaining circuit, a secondary center position calculating circuit, and a conversion model calculating circuit, where the contour point calculating circuit is configured to perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled hole and extract a contour, calculate a centroid set of each contour point in the circuit board with the back drilled hole, and transmit the centroid set of each contour point to the feature hole obtaining circuit; the characteristic hole acquisition circuit is electrically connected with the contour point calculation circuit and is used for screening the centroid sets of the contour points to obtain a global characteristic hole set with a preset number; the matching result acquisition circuit is electrically connected with the characteristic hole acquisition circuit and is used for acquiring a corresponding matching result according to the preset number of global characteristic hole sets; the secondary central position calculating circuit is electrically connected with the matching result acquiring circuit and is used for calculating and obtaining the corresponding secondary central position of the back drilling hole in the circuit board according to the matching result; the conversion model calculation circuit is electrically connected with the secondary central position calculation circuit, and the conversion model calculation circuit is used for calculating a position conversion model according to the central position of the two-dimensional real-time image of the circuit board with the back drilling hole and the central position of the corresponding standard hole of the circuit board back drilling hole manufacturing plate so as to obtain the position of each back drilling hole in the two-dimensional real-time image.
Optionally, the back-drilling hole center extraction device includes an interested region image acquisition circuit, a threshold segmentation processing circuit, and a cubic center position calculation circuit, where the interested region image acquisition circuit is configured to acquire an interested region image of a center position on the two-dimensional real-time image according to the position conversion model; the threshold segmentation processing circuit is electrically connected with the interesting region image acquisition circuit and is used for carrying out self-adaptive threshold segmentation processing according to the interesting region image of each backdrilled hole on the two-dimensional real-time image; the cubic central position calculating circuit is electrically connected with the threshold segmentation processing circuit and is used for calculating the cubic central position of the back drilling hole in the corresponding circuit board according to the segmentation threshold.
Optionally, the back-drilled hole inner and outer boundary processing device includes a segmentation threshold calculation circuit, a first fitting circuit, an eccentricity calculation circuit, a process parameter acquisition circuit, and a first parameter conversion circuit, where the segmentation threshold calculation circuit is configured to calculate according to the center of the back-drilled hole to obtain a first segmentation threshold and a second segmentation threshold; the first fitting circuit is electrically connected with the segmentation threshold calculation circuit and is used for segmenting the target back drilling hole region through the first segmentation threshold and the second segmentation threshold and fitting to obtain the circle center and the radius of the inner boundary and the outer boundary; the eccentricity calculation circuit is electrically connected with the first fitting circuit and is used for calculating the eccentricity according to the circle center and the radius of the inner boundary and the outer boundary; the process parameter acquisition circuit is electrically connected with the eccentricity calculation circuit and is used for acquiring two-dimensional process parameters of an inner boundary and an outer boundary according to the eccentricity; the first parameter conversion circuit is electrically connected with the process parameter acquisition circuit and is used for converting the two-dimensional process parameters into actual numerical parameters in a first coordinate system so as to acquire the position relation between the circle center of the inner boundary and the outer boundary.
Optionally, the characteristic parameter generating device includes a boundary data obtaining circuit, a second fitting circuit and a second parameter converting circuit, where the boundary data obtaining circuit is configured to obtain, according to the inner and outer boundary circle center positions and the inner and outer boundary positions, central height data of the back drilling hole in the three-dimensional actual height image and positions of the inner and outer boundaries; the second fitting circuit is electrically connected with the boundary data acquisition circuit and is used for calculating and fitting according to the positions of the inner and outer boundaries of the back drilling hole on the three-dimensional actual height image to obtain a first height plane and a second height plane; the second parameter conversion circuit is electrically connected with the second fitting circuit, and is used for calculating a first distance between the first height planes and a second distance between the first height planes and the second height planes, and converting the obtained first distance and second distance into characteristic parameters of the back drilling hole under a first coordinate system.
In summary, in the application, the two-dimensional/three-dimensional characteristic measurement system of the back drilling hole acquires the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilling hole through the image acquisition device, the back drilling hole center extraction device, the back drilling hole inner and outer boundary processing device and the characteristic parameter generation device, and calculates the characteristic parameters of the back drilling hole, so that the problems of low detection efficiency and poor precision of the roundness of the back drilling hole of the circuit board, the back drilling height and the like are solved, and the production efficiency of the circuit board is effectively improved.
Based on the same inventive concept, the application also provides a back drilling hole two-dimensional/three-dimensional characteristic measurement method, which is executed by the back drilling hole two-dimensional/three-dimensional characteristic measurement system, and the back drilling hole two-dimensional/three-dimensional characteristic measurement method comprises the following steps: the method comprises the steps that a two-dimensional real-time image and a three-dimensional actual height image of a circuit board with a back drilling hole are obtained through equal-interval movement of a motion platform; performing fixed threshold segmentation on the acquired two-dimensional real-time image of the circuit board with the back drilling holes to obtain position information of each back drilling hole on the two-dimensional real-time image, and constructing the position information of each back drilling hole and preset standard data of a circuit board back drilling hole manufacturing plate into a corresponding position conversion model to acquire the position of each back drilling hole in the two-dimensional real-time image; acquiring an interested area image of the position of each back drilling hole according to the position of each back drilling hole in the acquired two-dimensional real-time image, and acquiring the center of each back drilling hole through calculation; performing dual threshold segmentation according to the acquired center of the back drilling hole to acquire the inner and outer boundaries of the back drilling hole, calculating two-dimensional process parameters of the inner and outer circle centers of the back drilling hole, and converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters under a first coordinate system to acquire the position relation of the inner and outer boundary circle centers and the inner and outer boundaries; and calculating to obtain the characteristic parameters of the back drilling hole on the three-dimensional actual height image according to the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
Optionally, the obtaining of the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilling hole by moving the motion platform at equal intervals includes: moving the motion platform along a first direction at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole of the current row; moving the moving platform along a second direction at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole in the next column, wherein the second direction is perpendicular to the first direction; and sequentially scanning the circuit board with the back drilling hole along the second direction through the motion platform so as to obtain a two-dimensional real-time image and a three-dimensional actual height image of the whole circuit board with the back drilling hole.
Optionally, the performing fixed threshold segmentation on the acquired two-dimensional real-time image of the circuit board with the back-drilled holes to obtain position information of each back-drilled hole on the two-dimensional real-time image, and constructing a corresponding position conversion model by using the position information of each back-drilled hole and preset standard data of a circuit board back-drilled hole manufacturing board to acquire a position of each back-drilled hole in the two-dimensional real-time image includes: performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling hole, extracting a contour, and calculating a mass center set of each contour point in the circuit board with the back drilling hole; screening the centroid set of each contour point to obtain a preset number of global feature hole sets; obtaining a corresponding matching result according to the global feature hole set with the preset number; calculating to obtain the secondary center position of the back drilling hole in the corresponding circuit board according to the obtained matching result; and calculating to obtain a position conversion model according to the obtained central position of the two-dimensional real-time image of the circuit board with the back drilling hole and the central position of the corresponding standard hole of the circuit board back drilling hole manufacturing plate so as to obtain the position of each back drilling hole in the two-dimensional real-time image.
Optionally, the obtaining an image of an area of interest of a position of each back drilling hole according to the position of each back drilling hole in the obtained two-dimensional real-time image, and obtaining the center of each back drilling hole by calculation includes: acquiring an interested area image of the central position on the two-dimensional real-time image according to the position conversion model; performing self-adaptive threshold segmentation processing according to the interesting region image of each back drilling hole on the two-dimensional real-time image; and calculating the three central positions of the back drilling holes in the corresponding circuit board according to the obtained segmentation threshold.
Optionally, the performing dual threshold segmentation according to the acquired center of the back drill hole to acquire inner and outer boundaries of the back drill hole, calculating two-dimensional process parameters of inner and outer circle centers of the back drill hole, and converting the two-dimensional process parameters of the back drill hole into actual numerical parameters in a first coordinate system to acquire a position relationship between the inner and outer boundary circle centers and the inner and outer boundaries includes: calculating according to the center of the back drilling hole to obtain a first segmentation threshold value and a second segmentation threshold value; dividing the target back drilling hole area through the obtained first division threshold and the second division threshold, and fitting to obtain the circle center and the radius of the inner circle boundary; calculating to obtain an eccentricity according to the acquired circle centers and radii of the inner boundary and the outer boundary; acquiring two-dimensional process parameters of the inner and outer boundaries according to the acquired eccentricity; and converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters in a first coordinate system to obtain the position relation between the circle center of the inner boundary and the circle center of the outer boundary.
Optionally, the calculating on the three-dimensional actual height image according to the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries to obtain the characteristic parameters of the back drilling hole includes: obtaining central height data of the back drilling hole and positions of the inner and outer boundaries on the three-dimensional actual height image according to the obtained inner and outer boundary circle center positions and the obtained inner and outer boundary positions of the back drilling hole; calculating and fitting according to the positions of the inner and outer boundaries of the back drilling hole on the obtained three-dimensional actual height image to obtain a first height plane and a second height plane; and calculating a first distance between the center height of the back drilled hole and the first height plane and a second distance between the first height plane and the second height plane, and converting the obtained first distance and second distance into the characteristic parameters of the back drilled hole under a first coordinate system.
In summary, in the two-dimensional/three-dimensional characteristic measurement method for the back drilling hole in the application, the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilling hole are obtained, and the characteristic parameters of the back drilling hole are calculated, so that the problems of low detection efficiency and poor precision of the roundness, the back drilling height and the like of the back drilling hole of the circuit board are solved, and the production efficiency of the circuit board is effectively improved.
Based on the same inventive concept, the present application also provides a back-drilled hole two-dimensional/three-dimensional feature measurement device, which comprises: at least one processor and a memory, at least one of the processors executing computer-executable instructions stored by the memory, at least one of the processors performing the above-described backborehole two-dimensional/three-dimensional feature measurement method.
In summary, the back drilling hole two-dimensional/three-dimensional characteristic measuring device provided by the application can realize the detection of the circuit board, thereby effectively improving the working efficiency of a circuit board production line and improving the market competition rate of products.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.
Fig. 1 is a schematic structural diagram of a back-drilled hole two-dimensional/three-dimensional feature measurement system disclosed in an embodiment of the present application;
FIG. 2 is a light path diagram of the transparent material screen thickness measuring system shown in FIG. 1;
FIG. 3 is a schematic structural diagram of a position acquisition device of the back-drilled hole two-dimensional/three-dimensional feature measurement system shown in FIG. 1;
FIG. 4 is a schematic structural diagram of a back-drilled hole center extraction device of the back-drilled hole two-dimensional/three-dimensional feature measurement system shown in FIG. 1;
FIG. 5 is a schematic structural diagram of an inner and outer boundary processing device of a back-drilled hole of the back-drilled hole two-dimensional/three-dimensional feature measurement system shown in FIG. 1;
FIG. 6 is a schematic structural diagram of a characteristic parameter generating device of the back-drilled hole two-dimensional/three-dimensional characteristic measuring system shown in FIG. 1;
fig. 7 is a schematic flow chart of a back-drilled hole two-dimensional/three-dimensional feature measurement method disclosed in the embodiment of the present application;
FIG. 8 is a schematic flow chart of step S10 of the backdrilling two-dimensional/three-dimensional feature measurement method of FIG. 7;
FIG. 9 is a schematic flow chart of step S20 of the backdrilling two-dimensional/three-dimensional feature measurement method of FIG. 7;
FIG. 10 is a schematic flow chart of step S30 of the backdrilling two-dimensional/three-dimensional feature measurement method of FIG. 7;
FIG. 11 is a schematic flow chart of step S40 of the backdrilling two-dimensional/three-dimensional feature measurement method of FIG. 7;
FIG. 12 is a schematic flow chart of step S50 of the backdrilling two-dimensional/three-dimensional feature measurement method of FIG. 7;
fig. 13 is a schematic hardware structure diagram of a back-drilled hole two-dimensional/three-dimensional feature measurement apparatus disclosed in an embodiment of the present application.
Detailed Description
To facilitate an understanding of the present application, the present application will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present application are given in the accompanying drawings. This application may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
The following description of the various embodiments refers to the accompanying drawings, which are included to illustrate specific embodiments that can be implemented by the application. The numbering of the components as such, e.g., "first", "second", etc., is used herein only to distinguish the objects as described, and does not have any sequential or technical meaning. The term "connected" and "coupled" when used in this application, unless otherwise indicated, includes both direct and indirect connections (couplings). Directional phrases used in this application, such as "upper," "lower," "front," "rear," "left," "right," "inner," "outer," "side," and the like, refer only to the direction of the appended figures and, therefore, are used in order to better and more clearly illustrate and understand the present application and are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in the particular orientation, and, therefore, should not be taken to be limiting of the present application.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as being fixedly connected, detachably connected, or integrally connected; may be a mechanical connection; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art. It should be noted that the terms "first", "second", and the like in the description and claims of the present application and in the drawings are used for distinguishing between different objects and not for describing a particular order. Furthermore, the terms "comprises," "comprising," "includes," "including," or "including," when used in this application, specify the presence of stated features, operations, elements, and/or the like, but do not limit one or more other features, operations, elements, and/or the like. Furthermore, the terms "comprises" or "comprising" indicate the presence of the respective features, numbers, steps, operations, elements, components or combinations thereof disclosed in the specification, but do not preclude the presence or addition of one or more other features, numbers, steps, operations, elements, components or combinations thereof, and are intended to cover non-exclusive inclusions.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
The circuit board is used as a substrate for carrying electronic elements and has wide application in the electronic field, and the main structure of the circuit board can be divided into two blocks due to the wiring requirements of different electronic products, wherein the circuit board can be divided into a single panel, a double-sided board, a multilayer board and a flexible board according to the number of layers; and secondly, the production process is divided into copper plates, tin spraying plates, halogen-free plain plates, gold immersion plates, nickel plating plates, aluminum substrates and the like. Among them, a wiring board, which is a circuit board having inter-point connections and printed elements formed on a common substrate in a predetermined design and mainly functions to connect various electronic components to a predetermined circuit, has attracted attention as a carrier for electrical connection of electronic components. The circuit board is used as an important electronic component and is widely applied to different fields, wherein the fields comprise consumer electronics, automotive electronics, semiconductor packaging, network communication, aerospace and the like, especially the demand of automotive electronics is greatly increased along with the rapid development of new energy vehicles, and in addition, the demand of consumer electronics and semiconductor packaging on the circuit board is also large. However, the existing production process of the circuit board is not mature, and especially, process detection of relevant parameters of backdrilling (Backdrill) in the circuit board has many problems, which also restricts the working efficiency of the circuit board production line.
Based on this, the present application hopes to provide a solution to the above technical problem, which can solve the problems of low detection efficiency and poor precision, such as the roundness of the back drilling hole and the height of the back drilling hole of the circuit board, thereby effectively improving the production efficiency of the circuit board, and the details of which will be explained in the following embodiments.
The two-dimensional/three-dimensional characteristic measuring system, method and device for the back drilling hole are designed based on structured light, and can acquire two-dimensional/three-dimensional data of the back drilling hole in the circuit board under the structured light. Specifically, the structured light is a system structure composed of a projector and a camera, and specifically, the projector is used for projecting specific light information to the surface of an object and the background, the specific light information is collected by the camera, information such as the position and the depth of the object is calculated according to the change of a light signal caused by the object, and then the whole three-dimensional space is restored.
Please refer to fig. 1, which is a schematic structural diagram of a two-dimensional/three-dimensional feature measurement system of a backdrilled hole according to an embodiment of the present application. As shown in fig. 1, in the embodiment of the present application, the present application provides an two-dimensional/three-dimensional feature measurement system 100 for an back borehole, which may include at least an image acquisition device 110, a position acquisition device 120, a back borehole center extraction device 130, an back borehole inner and outer boundary processing device 140, and a feature parameter generation device 150. The image acquiring device 110 is electrically connected to the position acquiring device 120, the position acquiring device 120 is electrically connected to the back-drilled hole center extracting device 130, the back-drilled hole center extracting device 130 is electrically connected to the back-drilled hole inner and outer boundary processing device 140, and the back-drilled hole inner and outer boundary processing device 140 is electrically connected to the characteristic parameter generating device 150, that is, the position acquiring device 120, the back-drilled hole center extracting device 130, the back-drilled hole inner and outer boundary processing device 140, and the characteristic parameter generating device 150 are electrically connected in sequence.
The image acquiring device 110 is configured to acquire a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilled hole at equal intervals through the moving platform, and transmit the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilled hole to the position acquiring device 120. In an exemplary embodiment, as shown in fig. 2, the image obtaining apparatus 110 may include a camera and a line laser, wherein the line laser emits a laser line, an included angle between the line laser and the camera is a preset angle, and the preset angle may be 50 degrees. Optionally, the camera may be angled at 20 degrees from vertical, and correspondingly, the line laser may be angled at 30 degrees from vertical. The motion platform is a two-dimensional motion platform.
The position acquiring device 120 is configured to perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled holes acquired by the image acquiring device 110 to obtain position information of each back drilled hole on the two-dimensional real-time image, construct a corresponding position conversion model with the position information of each back drilled hole on the two-dimensional real-time image and preset standard data of a circuit board back drilled hole manufacturing board to acquire a position of each back drilled hole in the two-dimensional real-time image, and transmit the position of each back drilled hole in the two-dimensional real-time image to the back drilled hole center extracting device 130.
In this embodiment of the application, specifically, the position obtaining device 120 may perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled hole, which is obtained by the image obtaining device 110, by using a two-dimensional imaging feature of the back drilled hole, to obtain the position information of each back drilled hole on the two-dimensional real-time image of the circuit board with the back drilled hole, construct a one-to-one corresponding position conversion model according to the position information of each back drilled hole on the two-dimensional real-time image of the circuit board with the back drilled hole and preset standard data obtained by manufacturing the circuit board with the back drilled hole, so as to obtain the position of each back drilled hole in the two-dimensional real-time image, and transmit the position of each back drilled hole in the two-dimensional real-time image to the back drilled hole center extracting device 130.
The back-drilled hole center extracting device 130 is configured to obtain a Region of Interest (ROI) image of a position of each back-drilled hole according to the position of each back-drilled hole in the two-dimensional real-time image obtained by the position obtaining device 120, obtain the center of each back-drilled hole through calculation, and transmit the center of each back-drilled hole to the back-drilled hole inner and outer boundary processing device 140.
In this embodiment of the application, specifically, the back drill hole center extracting device 130 may obtain an ROI image of each back drill hole according to a position of each back drill hole in the two-dimensional real-time image obtained by the position obtaining device 120, segment the current back drill hole and a background region of the ROI image according to a maximum inter-class variance principle, and extract the center of the back drill hole through a gravity center formula, so as to accurately position the back drill hole. In machine vision and image processing, a region to be processed is defined as a frame, a circle, an ellipse, an irregular polygon, or the like from a processed image, and is referred to as a region of interest (ROI).
The back-drilled hole inner and outer boundary processing device 140 is configured to perform dual threshold segmentation according to the center of the back-drilled hole obtained by the back-drilled hole center extracting device 130 to obtain inner and outer boundaries of the back-drilled hole, calculate two-dimensional process parameters of the inner and outer circle centers of the back-drilled hole, convert the two-dimensional process parameters of the back-drilled hole into actual numerical parameters in a first coordinate system to obtain the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries, and transmit the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries of the back-drilled hole to the characteristic parameter generating device 150.
In this embodiment, specifically, the back-drilled hole inner and outer boundary processing device 140 may perform dual threshold segmentation with its inner and outer radii as a range according to the center of the back-drilled hole obtained by the back-drilled hole center extracting device 130, obtain the inner and outer boundaries of the back-drilled hole, fit the sub-pixel circle center positions of the inner and outer holes corresponding to the inner and outer boundaries, calculate a two-dimensional process parameter of the back-drilled hole by using a hole roundness calculation method, convert the two-dimensional process parameter of the back-drilled hole into an actual numerical parameter in the first coordinate system according to a camera field resolution to obtain a position relationship between the inner and outer boundary circle centers and the inner and outer boundaries, and transmit the position relationship between the inner and outer boundary circle centers of the back-drilled hole and the inner and outer boundary boundaries to the characteristic parameter generating device 150. In an exemplary embodiment of the present application, the two-dimensional process parameters of the back drilling hole include two-dimensional process parameters such as a center distance between an inner center and an outer center, an inner roundness and an outer roundness. The first coordinate system is a physical coordinate system.
The characteristic parameter generating device 150 is configured to calculate the characteristic parameter of the back drill hole on the three-dimensional actual height image transmitted by the image acquiring device 110 according to the inner and outer boundary circle centers and the inner and outer boundary position relationship transmitted by the back drill hole inner and outer boundary processing device 140. In the exemplary embodiments of the present application, the characteristic parameters of the backdrilled hole include, but are not limited to: the height value of the outer boundary of the circuit board surface and the back drilling hole, the height value of the outer boundary of the back drilling hole and the bottom of the circle center and the like.
In summary, in the application, the two-dimensional/three-dimensional characteristic measurement system of the back drilling hole acquires the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilling hole through the image acquisition device 110, the position acquisition device 120, the back drilling hole center extraction device 130, the back drilling hole inner and outer boundary processing device 140 and the characteristic parameter generation device 150, and calculates the characteristic parameters of the back drilling hole, so that the problems of low detection efficiency and poor precision of the roundness, the back drilling height and the like of the circuit board back drilling hole are solved, and the production efficiency of the circuit board is effectively improved.
Referring to fig. 1 and fig. 2, in the present embodiment, the image capturing device 110 is specifically configured to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with back drilled holes in a current row by moving the moving platform along a first direction at equal intervals. The first direction can be the Y-axis direction of the motion platform, and the three-dimensional actual height image can be height data obtained through a laser triangulation principle. Referring to fig. 2, when a measured point O of a measured object (i.e., a circuit board having a back-drilled hole) moves or the surface height changes, the coordinates of a reference point P, from which an imaging point can be observed on the imaging surface of a camera, change by x. The principle of the laser triangulation method is as follows:
according to the similar triangular property, there are:
Figure BDA0003387128240000131
h is the surface height or displacement variation of the measured object, and l is the distance from the intersection point of the laser optical axis and the camera optical axis to the center of the lens, namely the object distance; d is the distance from the center of the lens to the image plane of the camera, namely the image distance; alpha is an included angle between the laser optical axis and the camera optical axis, namely an included angle between the laser plane and the camera optical axis; x is the distance from point P to point P1 on the camera image plane.
In order to ensure that the measured point O forms a clear real image on the camera image plane, the following formula is satisfied:
Figure BDA0003387128240000141
wherein f is the focal length of the lens.
In the formula, combining formula (1) and formula (2) can obtain:
Figure BDA0003387128240000142
the image acquiring device 110 is further specifically configured to acquire a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilled hole in the next column by moving the moving platform at equal intervals along the second direction. Wherein the second direction is perpendicular to the first direction. In this embodiment, the second direction may be an X-axis direction.
The image obtaining device 110 is further specifically configured to sequentially scan the circuit board with the back drilled hole along the second direction through the moving platform, so as to obtain a two-dimensional real-time image and a three-dimensional actual height image of the entire circuit board with the back drilled hole.
Please refer to fig. 3, which is a schematic structural diagram of the position acquiring device 120 of the back-drilled hole two-dimensional/three-dimensional feature measuring system shown in fig. 1. As shown in fig. 3, the position acquisition device 120 includes a contour point calculation circuit 121, a feature hole acquisition circuit 122, a matching result acquisition circuit 123, a secondary center position calculation circuit 124, and a conversion model calculation circuit 125. The contour point calculating circuit 121 is electrically connected to the characteristic hole obtaining circuit 122, the characteristic hole obtaining circuit 122 is electrically connected to the matching result obtaining circuit 123, the matching result obtaining circuit 123 is electrically connected to the secondary central position calculating circuit 124, and the secondary central position calculating circuit 124 is electrically connected to the conversion model calculating circuit 125.
In this embodiment, the contour point calculating circuit 121 is configured to perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back-drilled hole transmitted by the image acquiring device 110 and extract a contour, calculate a centroid set of each contour point in the circuit board with the back-drilled hole, and transmit the centroid set of each contour point to the feature hole acquiring circuit 122. Specifically, the contour point calculation circuit 121 may perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled hole transmitted by the image acquisition device 110 through an opencv library threshold function, extract the contour of the circuit board with the back drilled hole by using cvFindContours, and calculate a centroid set { C1, C2, …, Cn } of each contour point in the circuit board with the back drilled hole.
The feature hole obtaining circuit 122 is configured to screen the centroid sets of the contour points transmitted by the contour point calculating circuit 121, so as to obtain a preset number of global feature hole sets. Specifically, the aspect ratio of the circumscribed rectangle that is needed to satisfy the contour for screening the set of centroids of each contour point is smaller than a set threshold 1, and the set of global feature holes is { C1 ', C2 ', …, Cn ' }.
The matching result obtaining circuit 123 is configured to obtain a corresponding matching result according to the global feature hole set with the preset number obtained by the feature hole obtaining circuit 122. In this embodiment of the application, the matching result obtaining circuit 123 reads standard hole data of a back-drilled hole board of a circuit board, and calculates a multiplication correlation coefficient between the global feature hole set { C1 ', C2 ', …, Cn ' } and the standard hole data by using a set step length by using a translation search, so as to obtain a corresponding matching result. Wherein, the multiplied correlation coefficient calculation formula is as follows:
g ═ STD _ Template ═ REAL _ Template equation (4)
The REAL _ Template is the ROI area of the REAL-time image corresponding to each moving step position.
The secondary center position calculating circuit 124 is configured to calculate a secondary center position of the back-drilled hole in the corresponding circuit board according to the matching result obtained by the matching result obtaining circuit 123. In this embodiment of the application, the secondary center position calculating circuit 124 may correspond the standard hole data of the board manufactured by the back drilling of the circuit board to the two-dimensional real-time image of the circuit board with the back drilling hole according to the matching result obtained by the matching result obtaining circuit 123, obtain the approximate center position and the radius of the back drilling hole corresponding to the two-dimensional real-time image of the circuit board with the back drilling hole, and calculate the secondary center position of the back drilling hole in the corresponding circuit board by using a gray scale center-of-gravity calculation formula in a circular region with a preset radius as a center. Wherein, the preset radius can be 1.5 cm, and the gray scale gravity center formula is as follows:
Figure BDA0003387128240000151
the conversion model calculation circuit 125 is configured to calculate a position conversion model according to the central position of the two-dimensional real-time image of the circuit board with the back drilling hole obtained by the secondary central position calculation circuit 124 and the central position of the standard hole of the corresponding circuit board back drilling hole board to obtain a position of each back drilling hole in the two-dimensional real-time image. Specifically, the conversion model calculation circuit 125 calculates an affine transformation matrix of the central position of the two-dimensional real-time image of the circuit board with the back-drilled hole and the central position of the corresponding standard hole of the circuit board back-drilled hole manufacturing plate according to the central position of the two-dimensional real-time image of the circuit board with the back-drilled hole obtained by the secondary central position calculation circuit 124 and the central position of the corresponding standard hole of the circuit board back-drilled hole manufacturing plate, so as to obtain the position conversion model to obtain the position of each back-drilled hole in the two-dimensional real-time image. The parameters of the affine transformation matrix can be estimated by a least square method, and the calculation process is as follows:
if the original image is F (X, Y), the transformed image is F (X ', Y'), and F (X ', Y') is to be restored to F (X, Y), a conversion relationship between the coordinates of (X ', Y') and the coordinates of (X, Y) is found, which is called coordinate transformation and is expressed as (X, Y) ═ T (X ', Y').
The expression for affine transformation is: r (x) ═ Px + Q, x ═ (x, y) is the planar position of the pixel, P is the rotation matrix of 2 × 2, Q is the translation vector of 2 × 1, P, Q are affine transformation parameters, namely:
x ═ AX '+ BY' + C formula (6)
y ═ DX '+ EY' + F equation (7)
Therefore, it can be generalized to the solution of the coordinate transformation coefficients a, B, C, D, E, F. To prevent the occurrence of empty pixels, inverse mapping is generally used, which is obtained by the least squares method:
vec1 ═ inv ([ X Y I ] '[ X Y I ]) [ X Y I ]' U formula (8)
vec2 ═ inv ([ xy I ] '[ xy I ]) [ xy I ]' V; formula (9)
Wherein vec1 ═ a B C'; vec2 ═ D E F ]'; and X, Y, U, V and I are vectors formed by X, Y, X ', Y' and 1 respectively.
Please refer to fig. 4, which is a schematic structural diagram of the back-drilled hole center extracting device 130 of the back-drilled hole two-dimensional/three-dimensional feature measuring system shown in fig. 1. As shown in fig. 4, the back-drilled hole center extracting device 130 includes an ROI image acquiring circuit 131, a threshold segmentation processing circuit 132, and a cubic center position calculating circuit 133. The ROI image acquiring circuit 131 is electrically connected to the threshold segmentation processing circuit 132, and the threshold segmentation processing circuit 132 is electrically connected to the cubic central position calculating circuit 133.
In the embodiment of the present application, the ROI image obtaining circuit 131 is configured to obtain the ROI image of the center position on the two-dimensional real-time image according to the position conversion model transmitted by the position obtaining device 120. Specifically, the ROI image obtaining circuit 131 may correspond all the holes of the standard map to the two-dimensional real-time map according to the position conversion model transmitted by the position obtaining device 120, obtain approximate center positions and radii of all the back-drilled holes in the two-dimensional real-time map, and obtain an ROI image corresponding to the ROI region of the back-drilled hole on the two-dimensional real-time image. Wherein the ROI area may be 2 radii of the center position of the backdrilled hole.
The threshold segmentation processing circuit 132 is configured to perform adaptive threshold segmentation processing according to the ROI image of each backdrilled hole on the two-dimensional real-time image acquired by the ROI image acquisition circuit 131. Specifically, the threshold segmentation processing circuit 132 may perform adaptive threshold segmentation based on the maximum variance principle on the ROI image of each back borehole acquired by the ROI image acquisition circuit 131 within the inner and outer radius ranges of the back borehole. Wherein the maximum variance principle is as follows:
calculating an accumulation average value M of the gray level K and an image global average value MG:
Figure BDA0003387128240000171
wherein, PiFor the probability value of the current gray level, the final inter-class variance formula in this embodiment is:
Figure BDA0003387128240000172
wherein, the gray level K maximized by the formula is the calculated segmentation threshold.
The cubic center position calculating circuit 133 is configured to calculate a cubic center position of the back-drilled hole in the corresponding circuit board according to the division threshold obtained by the threshold division processing circuit 132. Specifically, the cubic center position calculating circuit 133 may divide the target back-drilled hole and the background plane according to the division threshold obtained by the threshold division processing circuit 132, and then calculate the cubic center position of the back-drilled hole in the circuit board by using a gray scale center-of-gravity formula.
Please refer to fig. 5, which is a schematic structural diagram of the back-drilled hole inner and outer boundary processing device 140 of the back-drilled hole two-dimensional/three-dimensional feature measurement system shown in fig. 1. As shown in fig. 5, the back-drilled inner and outer boundary processing device 140 includes a division threshold calculation circuit 141, a first fitting circuit 142, an eccentricity calculation circuit 143, a process parameter acquisition circuit 144, and a first parameter conversion circuit 145. The segmentation threshold calculation circuit 141 is electrically connected to the first fitting circuit 142, the first fitting circuit 142 is electrically connected to the eccentricity calculation circuit 143, the eccentricity calculation circuit 143 is electrically connected to the process parameter acquisition circuit 144, and the process parameter acquisition circuit 144 is electrically connected to the first parameter conversion circuit 145.
The division threshold calculation circuit 141 is configured to calculate a first division threshold and a second division threshold according to the center of the back drill hole transmitted by the back drill hole center extraction device 130. Specifically, the segmentation threshold calculation circuit 141 may perform circular ROI region interception in the inner and outer radius regions of the back borehole according to the center of the back borehole transmitted by the back borehole center extraction device 130, and perform adaptive segmentation by using the maximum variance principle to obtain a first segmentation threshold and a second segmentation threshold.
The first fitting circuit 142 is configured to segment the target back-drilled hole region by using the first segmentation threshold and the second segmentation threshold obtained by the segmentation threshold calculation circuit 141, and fit to obtain the circle center and the radius of the inner and outer boundaries. Specifically, the first fitting circuit 142 may divide the target back-drilled hole region by using the first division threshold and the second division threshold obtained by the division threshold calculation circuit 141, extract the inner and outer boundary contour information of the target back-drilled hole, obtain the boundary position, and fit the circle center and the radius of the inner circle boundary by using a least square method. The circle fitting is carried out by a least square method, and the optimization objective function of the square error is as follows:
Figure BDA0003387128240000181
in the formula: (x)i,yi) 1,2, wherein n is the coordinate of a characteristic point on the arc; n is the number of feature points participating in the fitting. On the premise of keeping the optimized objective function characteristics, to avoid root calculation, the error function is optimized, and the expression of equation (11) means that the minimum difference between the distances from all moving points to fixed points is changed into the minimum difference between the square of the distances from all moving points to fixed points and the square of the radius, which is defined as follows:
Figure BDA0003387128240000191
then equation (12) expands to:
Figure BDA0003387128240000192
at the same time, let B be-2 y0，A＝-2x0，
Figure BDA0003387128240000193
That is, equation (13) can be expressed as:
Figure BDA0003387128240000194
by the principle of least squares, the parameters A, B, C should be such that E is minimal. According to the minimum value, A, B and C should satisfy the following formula:
Figure BDA0003387128240000195
solving the system of equations and writing them in matrix form, to obtain equation (16):
Figure BDA0003387128240000196
each parameter in equation (16) is calculated as follows:
Figure BDA0003387128240000197
Figure BDA0003387128240000198
Figure BDA0003387128240000199
Figure BDA00033871282400001910
so as to obtain the best fitting circle center coordinate (x)0,y0) Fitted value of radius r:
Figure BDA0003387128240000201
in the embodiment, when least square circle fitting is performed, fitting points are determined, that is, the number of n is a known quantity, so that x can be directly calculated by using the formula as a prior formula0,y0And r is three parameters.
The eccentricity calculating circuit 143 is configured to calculate an eccentricity according to the circle center and the radius of the inner and outer boundaries obtained by the first fitting circuit 142. Specifically, the center of the inner circle is (X)0，Y0，R0) The center of the excircle is (X)1，Y1，R1) And calculating the corresponding eccentricity according to the formula of the eccentricity. Wherein the formula of the eccentricity is as follows:
Figure BDA0003387128240000202
the process parameter acquiring circuit 144 is configured to acquire two-dimensional process parameters of the inner and outer boundaries according to the eccentricity obtained by the eccentricity calculating circuit 143. For example, taking calculation of the roundness process parameter in the two-dimensional process parameters as an example, the following steps are performed, namely, the distances from all contour points on the circuit board with the back drilling hole to the fitting circle center are calculated, then, the difference (i.e., the absolute value) between the distance from each contour point on the circuit board with the back drilling hole to the fitting circle center and the radius R is calculated to obtain a roundness residual En, the mean value of the roundness residual En is calculated, and finally, (Rn-ave (En))/Rn is used as the roundness process parameter.
The first parameter conversion circuit 145 is configured to convert the two-dimensional process parameter of the back drill hole into an actual numerical parameter in a first coordinate system to obtain a position relationship between the circle center of the inner and outer boundaries and the inner and outer boundaries. Specifically, in the embodiment of the present application, all the parameters calculated above are the results in the image coordinate system, that is, the pixel units and the resolutions in the horizontal direction and the vertical direction of the image are both 16um/pixel, and the actual numerical parameter in the first coordinate system is obtained by multiplying the value of each process parameter obtained by the calculation by the corresponding resolution.
Please refer to fig. 6, which is a schematic structural diagram of a feature parameter generating apparatus 150 of the back-drilled hole two-dimensional/three-dimensional feature measurement system shown in fig. 1. As shown in fig. 6, the characteristic parameter generating means 150 includes a boundary data acquiring circuit 151, a second fitting circuit 152, and a second parameter converting circuit 153. The boundary data obtaining circuit 151 is electrically connected to the second fitting circuit 152, and the second fitting circuit 152 is electrically connected to the second parameter converting circuit 153.
In this embodiment, the boundary data obtaining circuit 151 is configured to obtain central height data of the back drill hole and positions of the inner and outer boundaries on the three-dimensional actual height image according to the inner and outer boundary circle center positions and the inner and outer boundary positions of the back drill hole, which are obtained by the back drill hole inner and outer boundary processing device 140. Specifically, the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilled hole are obtained simultaneously in the scanning process, and the two-dimensional real-time image and the three-dimensional actual height image have a one-to-one correspondence relationship, so the boundary data obtaining circuit 151 can obtain the center height data of the back drilled hole and the positions of the inner and outer boundaries on the three-dimensional actual height image according to the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries of the back drilled hole, which is obtained by the back drilled hole inner and outer boundary processing device 140.
The second fitting circuit 152 is configured to calculate and fit the positions of the inner and outer boundaries of the back drilling hole on the three-dimensional actual height image acquired by the boundary data acquiring circuit 151 to obtain a first height plane and a second height plane. Specifically, the second fitting circuit 152 obtains a height value of an annular region of the back-drilled hole according to positions of inner and outer boundaries of the back-drilled hole on the three-dimensional actual height image obtained by the boundary data obtaining circuit 151, obtains the first height plane, which is recorded as Z1, by fitting inside the region 1.5 times the radius of the back-drilled hole and outside the outer boundary of the back-drilled hole, and obtains the second height plane, which is recorded as Z2.
The second parameter conversion circuit 153 is configured to calculate a first distance between a center height of the back borehole and the first height plane and a second distance between the first height plane and the second height plane, and convert the obtained first distance and second distance into a characteristic parameter of the back borehole in a first coordinate system. Specifically, a first distance between the center height of the back drilling hole and the first height plane is the height between the outer boundary of the back drilling hole and the bottom of the circle center, and a second distance between the first height plane and the second height plane is the height between the circuit board back drilling hole manufacturing plate and the outer boundary of the back drilling hole. In the embodiment of the application, the height resolution is about 12um/pixel, and the characteristic parameters of the back drilling hole under the physical coordinate system are obtained by multiplying each calculated height value by the corresponding resolution. In the exemplary embodiments of the present application, the characteristic parameters of the backdrilled hole include, but are not limited to: the height value of the outer boundary of the circuit board surface and the back drilling hole, the height value of the outer boundary of the back drilling hole and the bottom of the circle center and the like.
Referring to fig. 7, which is a schematic flow chart of a back-drilled hole two-dimensional/three-dimensional feature measurement method disclosed in an embodiment of the present application, the back-drilled hole two-dimensional/three-dimensional feature measurement system in the embodiments shown in fig. 1 to 6 measures two-dimensional/three-dimensional features of a back-drilled hole in a circuit board by using the following back-drilled hole two-dimensional/three-dimensional feature measurement method, so as to effectively improve the working efficiency of a circuit board production line. As shown in fig. 7, the backdrilling two-dimensional/three-dimensional feature measurement method includes at least the following steps.
And S10, moving the motion platform at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole.
In this embodiment, the image capturing device 110 captures a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back hole simultaneously by moving the motion platform at equal intervals, and transmits the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back hole to the position capturing device 120.
In the embodiment of the present application, please refer to fig. 8, wherein the step S10 at least includes the following steps.
And S11, moving the moving platform along the first direction at equal intervals to obtain the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilling hole of the current column.
Specifically, the first direction may be a Y-axis direction of the motion platform, and the three-dimensional actual height image may be height data obtained by a laser triangulation principle. Referring to fig. 2, when a measured point O of a measured object (i.e., a circuit board having a back-drilled hole) moves or the surface height changes, the coordinates of a reference point P, from which an imaging point can be observed on the imaging surface of a camera, change by x. The principle of the laser triangulation method is as follows:
according to the similar triangular property, there are:
Figure BDA0003387128240000221
h is the surface height or displacement variation of the measured object, and l is the distance from the intersection point of the laser optical axis and the camera optical axis to the center of the lens, namely the object distance; d is the distance from the center of the lens to the image plane of the camera, namely the image distance; alpha is an included angle between the laser optical axis and the camera optical axis, namely an included angle between the laser plane and the camera optical axis; x is the distance from point P to point P1 on the camera image plane.
In order to ensure that the measured point O forms a clear real image on the camera image plane, the following formula is satisfied:
Figure BDA0003387128240000231
wherein f is the focal length of the lens.
In the formula, combining formula (1) and formula (2) can obtain:
Figure BDA0003387128240000232
and S12, moving the moving platform along the second direction at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole in the next column.
Wherein the second direction is perpendicular to the first direction. In this embodiment, the second direction may be an X-axis direction.
And S13, sequentially scanning the circuit board with the back drilling hole along the second direction through the motion platform to obtain a two-dimensional real-time image and a three-dimensional actual height image of the whole circuit board with the back drilling hole.
S20, performing fixed threshold segmentation on the acquired two-dimensional real-time image of the circuit board with the back drilling holes to obtain the position information of each back drilling hole on the two-dimensional real-time image, and constructing the position information of each back drilling hole and preset standard data of a circuit board back drilling hole manufacturing board into a corresponding position conversion model to acquire the position of each back drilling hole in the two-dimensional real-time image.
In this embodiment, the position obtaining device 120 performs fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled holes, which is obtained by the image obtaining device 110, to obtain the position information of each back drilled hole on the two-dimensional real-time image, constructs the position information of each back drilled hole on the two-dimensional real-time image and the preset standard data of the circuit board back drilled hole manufacturing board into a corresponding position conversion model to obtain the position of each back drilled hole in the two-dimensional real-time image, and transmits the position of each back drilled hole in the two-dimensional real-time image to the back drilled hole center extracting device 130.
In the embodiment of the present application, please refer to fig. 9, wherein the step S20 at least includes the following steps.
S21, performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling hole, extracting a contour, and calculating a centroid set of each contour point in the circuit board with the back drilling hole.
Specifically, the contour point calculation circuit 121 performs fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back-drilled hole transmitted by the image acquisition device 110, extracts a contour, calculates a centroid set of each contour point in the circuit board with the back-drilled hole, and transmits the centroid set of each contour point to the characteristic hole acquisition circuit 122. Specifically, the contour point calculation circuit 121 may perform fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilled hole transmitted by the image acquisition device 110 through an opencv library threshold function, extract the contour of the circuit board with the back drilled hole by using cvFindContours, and calculate a centroid set { C1, C2, …, Cn } of each contour point in the circuit board with the back drilled hole.
And S22, screening the centroid set of each contour point to obtain a preset number of global feature hole sets.
Specifically, the feature hole obtaining circuit 122 screens the centroid sets of the contour points transmitted by the contour point calculating circuit 121 to obtain a preset number of global feature hole sets. Specifically, the aspect ratio of the circumscribed rectangle that is needed to satisfy the contour for screening the set of centroids of each contour point is smaller than a set threshold 1, and the set of global feature holes is { C1 ', C2 ', …, Cn ' }.
And S23, obtaining a corresponding matching result according to the preset number of global feature hole sets.
In this embodiment, the matching result obtaining circuit 123 obtains a corresponding matching result according to the global feature hole set with the preset number obtained by the feature hole obtaining circuit 122. In this embodiment of the application, the matching result obtaining circuit 123 reads standard hole data of a back-drilled hole board of a circuit board, and calculates a multiplication correlation coefficient between the global feature hole set { C1 ', C2 ', …, Cn ' } and the standard hole data by using a set step length by using a translation search, so as to obtain a corresponding matching result.
Wherein, the multiplied correlation coefficient calculation formula is as follows:
g ═ STD _ Template ═ REAL _ Template equation (4)
The REAL _ Template is the ROI area of the REAL-time image corresponding to each moving step position.
And S24, calculating the secondary center position of the back drilling hole in the corresponding circuit board according to the obtained matching result.
In this embodiment, the secondary center position calculating circuit 124 calculates the secondary center position of the back-drilled hole in the corresponding circuit board according to the matching result obtained by the matching result obtaining circuit 123. In this embodiment of the application, the secondary center position calculating circuit 124 may correspond the standard hole data of the board manufactured by the back drilling of the circuit board to the two-dimensional real-time image of the circuit board with the back drilling hole according to the matching result obtained by the matching result obtaining circuit 123, obtain the approximate center position and the radius of the back drilling hole corresponding to the two-dimensional real-time image of the circuit board with the back drilling hole, and calculate the secondary center position of the back drilling hole in the corresponding circuit board by using a gray scale center-of-gravity calculation formula in a circular region with a preset radius as a center. Wherein, the preset radius can be 1.5 cm, and the gray scale gravity center formula is as follows:
Figure BDA0003387128240000251
s25, calculating according to the obtained center position of the two-dimensional real-time image of the circuit board with the back drilling hole and the center position of the corresponding standard hole of the circuit board back drilling hole manufacturing board to obtain a position conversion model so as to obtain the position of each back drilling hole in the two-dimensional real-time image.
In this embodiment, the conversion model calculation circuit 125 calculates a position conversion model according to the center position of the two-dimensional real-time image of the circuit board with the back drilling hole obtained by the secondary center position calculation circuit 124 and the center position of the standard hole of the corresponding circuit board back drilling hole manufacturing board, so as to obtain the position of each back drilling hole in the two-dimensional real-time image. Specifically, the conversion model calculation circuit 125 calculates an affine transformation matrix of the central position of the two-dimensional real-time image of the circuit board with the back-drilled hole and the central position of the corresponding standard hole of the circuit board back-drilled hole manufacturing plate according to the central position of the two-dimensional real-time image of the circuit board with the back-drilled hole obtained by the secondary central position calculation circuit 124 and the central position of the corresponding standard hole of the circuit board back-drilled hole manufacturing plate, so as to obtain the position conversion model to obtain the position of each back-drilled hole in the two-dimensional real-time image. The parameters of the affine transformation matrix can be estimated by a least square method, and the calculation process is as follows:
if the original image is F (X, Y), the transformed image is F (X ', Y'), and F (X ', Y') is to be restored to F (X, Y), a conversion relationship between the coordinates of (X ', Y') and the coordinates of (X, Y) is found, which is called coordinate transformation and is expressed as (X, Y) ═ T (X ', Y').
The expression for affine transformation is: r (x) ═ Px + Q, x ═ (x, y) is the planar position of the pixel, P is the rotation matrix of 2 × 2, Q is the translation vector of 2 × 1, P, Q are affine transformation parameters, namely:
x ═ AX '+ BY' + C formula (6)
y ═ DX '+ EY' + F equation (7)
Therefore, it can be generalized to the solution of the coordinate transformation coefficients a, B, C, D, E, F. To prevent the occurrence of empty pixels, inverse mapping is generally used, which is obtained by the least squares method:
vec1 ═ inv ([ X Y I ] '[ X Y I ]) [ X Y I ]' U formula (8)
vec2 ═ inv ([ xy I ] '[ xy I ]) [ xy I ]' V; formula (9)
Wherein vec1 ═ a B C'; vec2 ═ D E F ]'; and X, Y, U, V and I are vectors formed by X, Y, X ', Y' and 1 respectively.
S30, obtaining the ROI image of the position of each back drilling hole according to the position of each back drilling hole in the obtained two-dimensional real-time image, and obtaining the center of each back drilling hole through calculation.
In this embodiment, the back-drilled hole center extracting device 130 is configured to obtain an ROI image of the position of each back-drilled hole according to the position of each back-drilled hole in the two-dimensional real-time image obtained by the position obtaining device 120, obtain the center of each back-drilled hole through calculation, and transmit the center of the back-drilled hole to the back-drilled hole inner and outer boundary processing device 140.
In the embodiment of the present application, please refer to fig. 10, wherein the step S30 at least includes the following steps.
And S31, acquiring an ROI image of the central position on the two-dimensional real-time image according to the position conversion model.
Specifically, the ROI image obtaining circuit 131 obtains the ROI image of the center position on the two-dimensional real-time image according to the position conversion model transmitted by the position obtaining device 120. Specifically, the ROI image obtaining circuit 131 may correspond all the holes of the standard map to the two-dimensional real-time map according to the position conversion model transmitted by the position obtaining device 120, obtain approximate center positions and radii of all the back-drilled holes in the two-dimensional real-time map, and obtain an ROI image corresponding to the ROI region of the back-drilled hole on the two-dimensional real-time image. Wherein the ROI area may be 2 radii of the center position of the backdrilled hole.
And S32, performing self-adaptive threshold segmentation processing according to the ROI image of each back drilling hole on the two-dimensional real-time image.
Specifically, the threshold segmentation processing circuit 132 performs adaptive threshold segmentation processing according to the ROI image of each backdrilled hole on the two-dimensional real-time image acquired by the ROI image acquisition circuit 131. Specifically, the threshold segmentation processing circuit 132 performs adaptive threshold segmentation according to the maximum variance principle on the ROI image of each back borehole acquired by the region acquisition 131 within the inner and outer radius ranges of the back borehole. Wherein the maximum variance principle is as follows:
calculating an accumulation average value M of the gray level K and an image global average value MG:
Figure BDA0003387128240000271
wherein, PiFor the probability value of the current gray level, the final inter-class variance formula in this embodiment is:
Figure BDA0003387128240000272
wherein, the gray level K maximized by the formula is the calculated segmentation threshold.
And S33, calculating the three-time central position of the back drilling hole in the corresponding circuit board according to the obtained segmentation threshold.
Specifically, the third-order center position calculating circuit 133 calculates the third-order center position of the back-drilled hole in the corresponding circuit board according to the division threshold obtained by the threshold division processing circuit 132. Specifically, the cubic center position calculating circuit 133 may divide the target back-drilled hole and the background plane according to the division threshold obtained by the threshold division processing circuit 132, and then calculate the cubic center position of the back-drilled hole in the circuit board by using a gray scale center-of-gravity formula.
S40, performing dual threshold segmentation according to the acquired center of the back drilling hole to acquire the inner and outer boundaries of the back drilling hole, calculating two-dimensional process parameters of the inner and outer circle centers of the back drilling hole, and converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters under a first coordinate system to acquire the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
In this embodiment, the back-drilled hole inner and outer boundary processing device 140 performs dual threshold segmentation according to the center of the back-drilled hole obtained by the back-drilled hole center extracting device 130 to obtain inner and outer boundaries of the back-drilled hole, calculates two-dimensional process parameters of the inner and outer circle centers of the back-drilled hole, converts the two-dimensional process parameters of the back-drilled hole into actual numerical parameters in a first coordinate system to obtain the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries, and transmits the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries of the back-drilled hole to the characteristic parameter generating device 150.
In the embodiment of the present application, please refer to fig. 11, wherein the step S40 at least includes the following steps.
And S41, calculating according to the center of the back drilling hole to obtain a first segmentation threshold value and a second segmentation threshold value.
Specifically, the segmentation threshold calculation circuit 141 calculates the first segmentation threshold and the second segmentation threshold according to the center of the back drill hole transmitted by the back drill hole center extraction device 130. Specifically, the segmentation threshold calculation circuit 141 may perform circular ROI region interception in the inner and outer radius regions of the back borehole according to the center of the back borehole transmitted by the back borehole center extraction device 130, and perform adaptive segmentation by using the maximum variance principle to obtain a first segmentation threshold and a second segmentation threshold.
And S42, segmenting the target back drilling hole area through the acquired first segmentation threshold and the acquired second segmentation threshold, and fitting to obtain the circle center and the radius of the inner circle boundary.
Specifically, the first fitting circuit 142 divides the target back-drilled hole region by the first division threshold and the second division threshold obtained by the division threshold calculation circuit 141, and fits to obtain the center and the radius of the inner circle boundary. Specifically, the first fitting circuit 142 may divide the target back-drilled hole region by using the first division threshold and the second division threshold obtained by the division threshold calculation circuit 141, extract the inner and outer boundary contour information of the target back-drilled hole, obtain the boundary position, and fit the circle center and the radius of the inner circle boundary by using a least square method. The circle fitting is carried out by a least square method, and the optimization objective function of the square error is as follows:
Figure BDA0003387128240000291
in the formula: (x)i,yi) 1,2, wherein n is the coordinate of a characteristic point on the arc; n is the number of feature points participating in the fitting. On the premise of keeping the optimized objective function characteristics, to avoid root calculation, the error function is optimized, and the expression of equation (11) means that the minimum difference between the distances from all moving points to fixed points is changed into the minimum difference between the square of the distances from all moving points to fixed points and the square of the radius, which is defined as follows:
Figure BDA0003387128240000292
then equation (12) expands to:
Figure BDA0003387128240000293
at the same timeLet B be-2 y0，A＝-2x0，
Figure BDA0003387128240000294
That is, equation (13) can be expressed as:
Figure BDA0003387128240000295
by the principle of least squares, the parameters A, B, C should be such that E is minimal. According to the minimum value, A, B and C should satisfy the following formula:
Figure BDA0003387128240000296
solving the system of equations and writing them in matrix form, to obtain equation (16):
Figure BDA0003387128240000297
each parameter in equation (16) is calculated as follows:
Figure BDA0003387128240000301
Figure BDA0003387128240000302
Figure BDA0003387128240000303
Figure BDA0003387128240000304
so as to obtain the best fitting circle center coordinate (x)0,y0) Fitted value of radius r:
Figure BDA0003387128240000305
in the embodiment, when least square circle fitting is performed, fitting points are determined, that is, the number of n is a known quantity, so that x can be directly calculated by using the formula as a prior formula0,y0And r is three parameters.
And S43, calculating to obtain the eccentricity according to the acquired circle centers and radiuses of the inner and outer boundaries.
Specifically, the eccentricity calculating circuit 143 calculates the eccentricity according to the circle center and the radius of the inner and outer boundaries obtained by the first fitting circuit 142. Specifically, the center of the inner circle is (X)0，Y0，R0) The center of the excircle is (X)1，Y1，R1) And calculating the corresponding eccentricity according to the formula of the eccentricity. Wherein the formula of the eccentricity is as follows:
Figure BDA0003387128240000306
and S44, acquiring two-dimensional process parameters of the inner boundary and the outer boundary according to the acquired eccentricity.
Specifically, the process parameter obtaining circuit 144 obtains the two-dimensional process parameters of the inner and outer boundaries according to the eccentricity obtained by the eccentricity calculating circuit 143. For example, taking calculation of the roundness process parameter in the two-dimensional process parameters as an example, the following steps are performed, namely, the distances from all contour points on the circuit board with the back drilling hole to the fitting circle center are calculated, then, the difference (i.e., the absolute value) between the distance from each contour point on the circuit board with the back drilling hole to the fitting circle center and the radius R is calculated to obtain a roundness residual En, the mean value of the roundness residual En is calculated, and finally, (Rn-ave (En))/Rn is used as the roundness process parameter.
S45, converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters in a first coordinate system to obtain the position relation between the circle center of the inner boundary and the circle center of the outer boundary and the position relation between the inner boundary and the outer boundary.
Specifically, the two-dimensional process parameters of the back-drilled hole are converted into actual numerical parameters in a first coordinate system by the first parameter conversion circuit 145 to obtain the position relationship between the circle center of the inner boundary and the circle center of the outer boundary. Specifically, in the embodiment of the present application, all the parameters calculated above are the results in the image coordinate system, that is, the pixel units and the resolutions in the horizontal direction and the vertical direction of the image are both 16um/pixel, and the actual numerical parameter in the first coordinate system is obtained by multiplying the value of each process parameter obtained by the calculation by the corresponding resolution.
And S50, calculating characteristic parameters of the back drilling hole on the three-dimensional actual height image according to the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
In the embodiment of the present application, please refer to fig. 12, wherein the step S50 at least includes the following steps.
And S51, obtaining the central height data of the back drilling hole on the three-dimensional actual height image and the positions of the inner and outer boundaries according to the obtained inner and outer boundary circle center positions and the obtained inner and outer boundary positions of the back drilling hole.
Specifically, the boundary data obtaining circuit 151 obtains the central height data of the back drill hole and the positions of the inner and outer boundaries on the three-dimensional actual height image according to the inner and outer boundary circle center positions and the inner and outer boundary positions of the back drill hole obtained by the back drill hole inner and outer boundary processing device 140. Specifically, the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the back drilled hole are obtained simultaneously in the scanning process, and the two-dimensional real-time image and the three-dimensional actual height image have a one-to-one correspondence relationship, so the boundary data obtaining circuit 151 can obtain the center height data of the back drilled hole and the positions of the inner and outer boundaries on the three-dimensional actual height image according to the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries of the back drilled hole, which is obtained by the back drilled hole inner and outer boundary processing device 140.
And S52, calculating and fitting according to the positions of the inner and outer boundaries of the back drilling hole on the acquired three-dimensional actual height image to obtain a first height plane and a second height plane.
Specifically, the second fitting circuit 152 calculates and fits the positions of the inner and outer boundaries of the back-drilled hole on the three-dimensional actual height image acquired by the boundary data acquiring circuit 151 to obtain a first height plane and a second height plane. Specifically, the second fitting circuit 152 obtains a height value of an annular region of the back-drilled hole according to positions of inner and outer boundaries of the back-drilled hole on the three-dimensional actual height image obtained by the boundary data obtaining circuit 151, obtains the first height plane, which is recorded as Z1, by fitting inside the region 1.5 times the radius of the back-drilled hole and outside the outer boundary of the back-drilled hole, and obtains the second height plane, which is recorded as Z2.
S53, calculating a first distance between the center height of the back drilled hole and the first height plane and a second distance between the first height plane and the second height plane, and converting the obtained first distance and second distance into the characteristic parameters of the back drilled hole under a first coordinate system.
Specifically, a first distance between the center height of the back drill hole and the first height plane and a second distance between the first height plane and the second height plane are calculated by the second parameter conversion circuit 153, and the obtained first distance and second distance are converted into the characteristic parameters of the back drill hole in the first coordinate system. Specifically, a first distance between the center height of the back drilling hole and the first height plane is the height between the outer boundary of the back drilling hole and the bottom of the circle center, and a second distance between the first height plane and the second height plane is the height between the circuit board back drilling hole manufacturing plate and the outer boundary of the back drilling hole. In the embodiment of the application, the height resolution is about 12um/pixel, and the characteristic parameters of the back drilling hole under the physical coordinate system are obtained by multiplying each calculated height value by the corresponding resolution. In the exemplary embodiments of the present application, the characteristic parameters of the backdrilled hole include, but are not limited to: the height value of the outer boundary of the circuit board surface and the back drilling hole, the height value of the outer boundary of the back drilling hole and the bottom of the circle center and the like.
In summary, the two-dimensional/three-dimensional characteristic measurement method for the back drilling hole can realize the detection of the circuit board, thereby effectively improving the working efficiency of the circuit board production line and improving the market competition rate of products.
Please refer to fig. 13, which is a schematic diagram of a hardware structure of a back-drilled hole two-dimensional/three-dimensional feature measurement apparatus according to an embodiment of the present application. As shown in fig. 13, the back-drilled hole two-dimensional/three-dimensional feature measurement apparatus 200 provided by the embodiment of the present application includes at least one processor 201 and a memory 202. The backborehole two-dimensional/three-dimensional feature measurement apparatus 200 also includes at least one bus 203. Wherein the processor 201 and the memory 202 are electrically connected by a bus 203. The backdrilled hole two-dimensional/three-dimensional feature measurement apparatus 200 may be a computer or a server, and the present application is not particularly limited thereto.
The backborehole two-dimensional/three-dimensional feature measurement apparatus 200 may also include a backborehole two-dimensional/three-dimensional feature measurement system as in the embodiments of figures 1-6 described above. In a specific implementation, the at least one processor 201 executes computer-executable instructions stored in the memory 202 to cause the at least one processor 201 to perform the back-drilled hole two-dimensional/three-dimensional feature measurement method according to the embodiment shown in fig. 7-12 via the back-drilled hole two-dimensional/three-dimensional feature measurement system.
For a specific implementation process of the processor 201 provided in the embodiment of the present application, reference may be made to the embodiments of the two-dimensional/three-dimensional feature measurement method for back drilling hole in the embodiments described in fig. 7 to 12, which have similar implementation principles and technical effects, and details are not repeated here.
It is understood that the Processor 201 may be a Central Processing Unit (CPU), other general purpose Processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), etc. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like. The steps of a method provided in connection with the present application may be embodied directly in a hardware processor, or in a combination of the hardware and software modules included in the processor.
The Memory 202 may be a Random Access Memory (RAM) or a Non-Volatile Memory (NVM).
The bus 203 may be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, an Extended ISA (enhanced Industry Standard Architecture) bus, or the like. For ease of illustration, the bus 203 in the figures of the present application is not limited to only one bus or one type of bus.
It is to be understood that the invention is not limited to the examples described above, but that modifications and variations may be effected thereto by those of ordinary skill in the art in light of the foregoing description, and that all such modifications and variations are intended to be within the scope of the invention as defined by the appended claims.

Claims (13)

1. A backdrilled two/three dimensional feature measurement system comprising:
the image acquisition device is used for acquiring a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole through the movement of the motion platform at equal intervals;
the position acquisition device is electrically connected with the image acquisition device and is used for performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling holes to obtain the position information of each back drilling hole on the two-dimensional real-time image, and constructing the position information of each back drilling hole on the two-dimensional real-time image and preset standard data of a circuit board back drilling hole manufacturing plate into a corresponding position conversion model to obtain the position of each back drilling hole in the two-dimensional real-time image;
the back drilling hole center extracting device is electrically connected with the position acquiring device and is used for acquiring an interested area image of the position of each back drilling hole according to the position of each back drilling hole in the two-dimensional real-time image and acquiring the center of each back drilling hole;
the back-drilling inner and outer boundary processing device is electrically connected with the back-drilling center extracting device and used for carrying out dual threshold segmentation according to the center of the back drilling hole to obtain the inner and outer boundaries of the back drilling hole, calculating two-dimensional technological parameters of the inner and outer circle centers of the back drilling hole and converting the two-dimensional technological parameters of the back drilling hole into actual numerical parameters under a first coordinate system to obtain the position relation between the inner and outer boundary circle centers and the inner and outer boundaries;
and the characteristic parameter generating device is electrically connected with the back drilling hole inner and outer boundary processing device and is used for calculating the characteristic parameters of the back drilling hole on the three-dimensional actual height image transmitted by the image acquisition device according to the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
2. The backdrilled two-dimensional/three-dimensional feature measurement system of claim 1 wherein the image acquisition device comprises a camera and a line laser, wherein the line laser emits a laser line and the angle between the line laser and the camera is a preset angle.
3. The backdrilled two-dimensional/three-dimensional feature measurement system of claim 1, wherein the position acquisition device comprises a contour point calculation circuit, a feature hole acquisition circuit, a matching result acquisition circuit, a secondary center position calculation circuit, and a transformation model calculation circuit, wherein,
the contour point calculation circuit is used for performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling hole, extracting a contour, calculating a centroid set of each contour point in the circuit board with the back drilling hole, and transmitting the centroid set of each contour point to the characteristic hole acquisition circuit;
the characteristic hole acquisition circuit is electrically connected with the contour point calculation circuit and is used for screening the centroid sets of the contour points to obtain a global characteristic hole set with a preset number;
the matching result acquisition circuit is electrically connected with the characteristic hole acquisition circuit and is used for acquiring a corresponding matching result according to the preset number of global characteristic hole sets;
the secondary central position calculating circuit is electrically connected with the matching result acquiring circuit and is used for calculating and obtaining the corresponding secondary central position of the back drilling hole in the circuit board according to the matching result;
the conversion model calculation circuit is electrically connected with the secondary central position calculation circuit, and the conversion model calculation circuit is used for calculating a position conversion model according to the central position of the two-dimensional real-time image of the circuit board with the back drilling hole and the central position of the corresponding standard hole of the circuit board back drilling hole manufacturing plate so as to obtain the position of each back drilling hole in the two-dimensional real-time image.
4. The back-drilled two-dimensional/three-dimensional feature measurement system of claim 1, wherein the back-drilled hole center extraction means comprises a region-of-interest image acquisition circuit, a threshold segmentation processing circuit, and a cubic center position calculation circuit, wherein,
the interesting region image acquisition circuit is used for acquiring an interesting region image of the central position on the two-dimensional real-time image according to the position conversion model;
the threshold segmentation processing circuit is electrically connected with the interesting region image acquisition circuit and is used for carrying out self-adaptive threshold segmentation processing according to the interesting region image of each backdrilled hole on the two-dimensional real-time image;
the cubic central position calculating circuit is electrically connected with the threshold segmentation processing circuit and is used for calculating the cubic central position of the back drilling hole in the corresponding circuit board according to the segmentation threshold.
5. The back-drilled two-dimensional/three-dimensional feature measurement system of claim 1, wherein the back-drilled inner and outer boundary processing means comprises a segmentation threshold calculation circuit, a first fitting circuit, an eccentricity calculation circuit, a process parameter acquisition circuit, and a first parameter conversion circuit, wherein,
the segmentation threshold calculation circuit is used for calculating according to the center of the back drilling hole to obtain a first segmentation threshold and a second segmentation threshold;
the first fitting circuit is electrically connected with the segmentation threshold calculation circuit and is used for segmenting the target back drilling hole region through the first segmentation threshold and the second segmentation threshold and fitting to obtain the circle center and the radius of the inner boundary and the outer boundary;
the eccentricity calculation circuit is electrically connected with the first fitting circuit and is used for calculating the eccentricity according to the circle center and the radius of the inner boundary and the outer boundary;
the process parameter acquisition circuit is electrically connected with the eccentricity calculation circuit and is used for acquiring two-dimensional process parameters of an inner boundary and an outer boundary according to the eccentricity;
the first parameter conversion circuit is electrically connected with the process parameter acquisition circuit and is used for converting the two-dimensional process parameters into actual numerical parameters in a first coordinate system so as to acquire the position relation between the circle center of the inner boundary and the outer boundary.
6. The backborehole two-dimensional/three-dimensional feature measurement system of claim 1, wherein the feature parameter generation means comprises a boundary data acquisition circuit, a second fitting circuit, and a second parameter conversion circuit, wherein,
the boundary data acquisition circuit is used for acquiring the central height data of the back drilling hole on the three-dimensional actual height image and the positions of the inner boundary and the outer boundary according to the positions of the circle centers of the inner boundary and the outer boundary and the positions of the inner boundary and the outer boundary;
the second fitting circuit is electrically connected with the boundary data acquisition circuit and is used for calculating and fitting according to the positions of the inner and outer boundaries of the back drilling hole on the three-dimensional actual height image to obtain a first height plane and a second height plane;
the second parameter conversion circuit is electrically connected with the second fitting circuit, and is used for calculating a first distance between the first height planes and a second distance between the first height planes and the second height planes, and converting the obtained first distance and second distance into characteristic parameters of the back drilling hole under a first coordinate system.
7. An backborehole two-dimensional/three-dimensional feature measurement method performed by the backborehole two-dimensional/three-dimensional feature measurement system of any of claims 1-6 above, the backborehole two-dimensional/three-dimensional feature measurement method comprising:
the method comprises the steps that a two-dimensional real-time image and a three-dimensional actual height image of a circuit board with a back drilling hole are obtained through equal-interval movement of a motion platform;
performing fixed threshold segmentation on the acquired two-dimensional real-time image of the circuit board with the back drilling holes to obtain position information of each back drilling hole on the two-dimensional real-time image, and constructing the position information of each back drilling hole and preset standard data of a circuit board back drilling hole manufacturing plate into a corresponding position conversion model to acquire the position of each back drilling hole in the two-dimensional real-time image;
acquiring an interested area image of the position of each back drilling hole according to the position of each back drilling hole in the acquired two-dimensional real-time image, and acquiring the center of each back drilling hole through calculation;
performing dual threshold segmentation according to the acquired center of the back drilling hole to acquire the inner and outer boundaries of the back drilling hole, calculating two-dimensional process parameters of the inner and outer circle centers of the back drilling hole, and converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters under a first coordinate system to acquire the position relation of the inner and outer boundary circle centers and the inner and outer boundaries;
and calculating to obtain the characteristic parameters of the back drilling hole on the three-dimensional actual height image according to the position relation between the inner and outer boundary circle centers and the inner and outer boundaries.
8. The backdrilled hole two-dimensional/three-dimensional feature measurement method of claim 7, wherein the obtaining of the two-dimensional real-time image and the three-dimensional actual height image of the circuit board with the backdrilled hole by moving the motion platform at equal intervals comprises:
moving the motion platform along a first direction at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole of the current row;
moving the moving platform along a second direction at equal intervals to obtain a two-dimensional real-time image and a three-dimensional actual height image of the circuit board with the back drilling hole in the next column, wherein the second direction is perpendicular to the first direction;
and sequentially scanning the circuit board with the back drilling hole along the second direction through the motion platform so as to obtain a two-dimensional real-time image and a three-dimensional actual height image of the whole circuit board with the back drilling hole.
9. The method for measuring two-dimensional/three-dimensional characteristics of back-drilled holes according to claim 8, wherein the step of performing fixed threshold segmentation on the acquired two-dimensional real-time image of the circuit board with the back-drilled holes to obtain the position information of each back-drilled hole on the two-dimensional real-time image, and constructing a corresponding position conversion model by using the position information of each back-drilled hole and preset standard data of a circuit board back-drilled hole manufacturing plate to acquire the position of each back-drilled hole in the two-dimensional real-time image comprises the following steps:
performing fixed threshold segmentation on the two-dimensional real-time image of the circuit board with the back drilling hole, extracting a contour, and calculating a mass center set of each contour point in the circuit board with the back drilling hole;
screening the centroid set of each contour point to obtain a preset number of global feature hole sets;
obtaining a corresponding matching result according to the global feature hole set with the preset number;
calculating to obtain the secondary center position of the back drilling hole in the corresponding circuit board according to the obtained matching result;
and calculating to obtain a position conversion model according to the obtained central position of the two-dimensional real-time image of the circuit board with the back drilling hole and the central position of the corresponding standard hole of the circuit board back drilling hole manufacturing plate so as to obtain the position of each back drilling hole in the two-dimensional real-time image.
10. The method for measuring two-dimensional/three-dimensional characteristics of back drilled holes according to claim 9, wherein the step of obtaining the image of the region of interest of the position of each back drilled hole according to the position of each back drilled hole in the obtained two-dimensional real-time image and obtaining the center of each back drilled hole by calculation comprises the following steps:
acquiring an interested area image of the central position on the two-dimensional real-time image according to the position conversion model;
performing self-adaptive threshold segmentation processing according to the interesting region image of each back drilling hole on the two-dimensional real-time image;
and calculating the three central positions of the back drilling holes in the corresponding circuit board according to the obtained segmentation threshold.
11. The method for measuring two-dimensional/three-dimensional characteristics of the back-drilled hole according to claim 10, wherein the steps of obtaining the inner and outer boundaries of the back-drilled hole by performing dual threshold segmentation according to the obtained center of the back-drilled hole, calculating two-dimensional process parameters of the inner and outer circle centers of the back-drilled hole, and converting the two-dimensional process parameters of the back-drilled hole into actual numerical parameters in a first coordinate system to obtain the position relationship between the inner and outer boundary circle centers and the inner and outer boundaries comprise:
calculating according to the center of the back drilling hole to obtain a first segmentation threshold value and a second segmentation threshold value;
dividing the target back drilling hole area through the obtained first division threshold and the second division threshold, and fitting to obtain the circle center and the radius of the inner circle boundary;
calculating to obtain an eccentricity according to the acquired circle centers and radii of the inner boundary and the outer boundary;
acquiring two-dimensional process parameters of the inner and outer boundaries according to the acquired eccentricity;
and converting the two-dimensional process parameters of the back drilling hole into actual numerical parameters in a first coordinate system to obtain the position relation between the circle center of the inner boundary and the circle center of the outer boundary.
12. The method for measuring two-dimensional/three-dimensional characteristics of the back drilled hole according to claim 11, wherein the step of calculating characteristic parameters of the back drilled hole on the three-dimensional actual height image according to the position relationship between the circle centers of the inner boundary and the outer boundary comprises the following steps:
obtaining central height data of the back drilling hole and positions of the inner and outer boundaries on the three-dimensional actual height image according to the obtained inner and outer boundary circle center positions and the obtained inner and outer boundary positions of the back drilling hole;
calculating and fitting according to the positions of the inner and outer boundaries of the back drilling hole on the obtained three-dimensional actual height image to obtain a first height plane and a second height plane;
and calculating a first distance between the center height of the back drilled hole and the first height plane and a second distance between the first height plane and the second height plane, and converting the obtained first distance and second distance into the characteristic parameters of the back drilled hole under a first coordinate system.
13. A backdrilled hole two/three dimensional feature measurement device comprising: at least one processor and memory, at least one of the processor executing computer-executable instructions stored by the memory, at least one of the processor performing the backborehole two-dimensional/three-dimensional feature measurement method of any of claims 7 to 12.
CN202111457821.4A 2021-12-01 2021-12-01 Back-drilled hole two-dimensional/three-dimensional characteristic measurement system, method and device Pending CN114092560A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
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CN114877821A (en) * 2022-05-31 2022-08-09 苏州浪潮智能科技有限公司 Back drilling depth detection system and method for PCB

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114877821A (en) * 2022-05-31 2022-08-09 苏州浪潮智能科技有限公司 Back drilling depth detection system and method for PCB
CN114877821B (en) * 2022-05-31 2023-09-22 苏州浪潮智能科技有限公司 Back drilling depth detection system and method for PCB

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