Captive screw and method for supporting automatic assembly of captive screw

Abstract

The present invention provides a captive screw and a method for supporting the automatic assembly of the captive screw. The captive screw is provided with a positioning module of a positioning circle formed by several annular boundary contours arranged on the surface of the captive screw in the captive screw shell; and / or an identification module of a coding belt composed of several coding points in the annular area at the top of the captive screw shell, so that the captive screw can be visually automatically positioned based on the coordinate information of the positioning circle. By setting the coding points, the coding sequence of the corresponding coding points is determined according to the average grayscale, and then the coding value is obtained to realize the automatic identification of the captive screw, thereby ensuring the visual and automatic identification and / or positioning and assembly of the captive screw, and improving the accuracy and efficiency of mechanical operation.

Description

Technical Field

[0001] The present application relates to the field of automation technology, and in particular to a captive screw and a method for supporting automated assembly of the captive screw. Background Art

[0002] Captive screws are widely used in the machining industry. For captive screws in non-fixed scenarios, most of the captive screws require tools to tighten or disassemble. The assembly of the captive screws relies on manual assembly. Accurate positioning and identification of the captive screw shell cannot be achieved, and automated assembly is difficult to achieve through mechanical equipment. Currently, manual assembly has high costs, low efficiency, unstable quality, and even certain specific dangerous scenarios are not suitable for manual operation. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide such a possibility. A captive screw housing with coding points and / or positioning circles that can be used for visual measurement is designed to realize the identification and / or positioning of the captive screws, so that the captive screws can be automatically identified, positioned and assembled, thereby improving the accuracy and efficiency of mechanical operations.

[0004] The first purpose of the present invention is to provide a captive screw, which includes: a positioning module, the positioning module includes a positioning circle formed by several annular boundary contours arranged on the surface of the captive screw; and / or, an identification module, the identification module includes a coding belt composed of several coding points arranged in an annular area on the top of the shell of the captive screw.

[0005] In one embodiment of the present invention, the coding points are evenly spaced in the top annular area, and the spacing between the coding points is set according to the number of coding points. Preferably, the coding points can be evenly distributed along the circumference of the detection circle formed by the annular area.

[0006] In one embodiment of the present invention, a plurality of coding points of the captive screw correspond to coding values ​​for identifying the captive screw.

[0007] The second invention of the present invention provides a method for supporting the automated assembly of captive screws, wherein the aforementioned positioning module and / or identification module is installed on the captive screws, comprising the following steps:

[0008] Acquire an original image of the captive screw housing, the original image including a positioning circle image and / or a coding point image;

[0009] The positioning circle image and / or the coding point image are subjected to a first preprocessing and / or a second preprocessing to realize automatic positioning and / or automatic identification, so as to support the automatic assembly of the captive screws.

[0010] In one embodiment of the present invention, performing a first preprocessing on the positioning circle image includes:

[0011] Get the pixel coordinates of the center of the positioning circle in the positioning circle image,

[0012] Calculate the three-dimensional coordinates in the preset coordinate system based on the pixel coordinates; and realize the automatic positioning of the captive screws.

[0013] In one embodiment of the present invention, performing the second preprocessing on the code point image includes:

[0014] Preprocessing the original image to enhance the contrast of the original image and obtain a preprocessed image;

[0015] Extract contour information of preprocessed images;

[0016] Perform ellipse fitting on the contour information, obtain the pixel coordinates of the ellipse center and the pixel sizes of the major and minor axes for clustering, and obtain the coded point clusters and / or positioning circle clusters.

[0017] In one embodiment of the present invention, obtaining the code point clusters and / or positioning circle clusters includes:

[0018] Perform perspective transformation on the contour points and center points of the code point cluster to obtain the code point orthographic projection cluster, and obtain the central pixel coordinates of the center point of the code band according to the code point orthographic projection cluster;

[0019] Perform perspective transformation on the preprocessed image to obtain an orthographic projection image, and set several coding points according to the center coordinates and center pixel coordinates of the orthographic projection image;

[0020] Select the starting code point. Preferably, it is only necessary to use any point as the starting point for searching to obtain a set of binary code values, and then cyclically shift it left by one position to obtain 8 sets of binary code sequences, among which the one with the smallest corresponding decimal value is the code value. There is no need to use the remaining 7 detection points as the starting position in turn to generate 8-bit binary code;

[0021] Taking the starting coding point as the starting point, sequentially compare the first grayscale values ​​of several coding points with the global average grayscale value to obtain a comparison result;

[0022] According to the comparison result, the binary code corresponding to the code point sequence is generated;

[0023] The binary code is shifted according to the preset rules to obtain the minimum decimal code value, which is the code value corresponding to the code target, thereby realizing automatic identification of loose and captive screws.

[0024] In one embodiment of the present invention, starting from the starting coding point, the first grayscale values ​​of a plurality of coding points are sequentially compared with the global average grayscale value, and obtaining the comparison result includes:

[0025] Get the global average grayscale of all pixels in the orthographic projection image;

[0026] Starting from the starting code point, the code points are detected in sequence and a first grayscale value is obtained; and whether the first grayscale value is less than the average grayscale is determined;

[0027] If so, the code bit of the mark code point is 0;

[0028] Otherwise, the code bit of the marking code point is 1.

[0029] In one embodiment of the present invention, the binary code is shifted according to a preset rule to obtain a minimum decimal code value, which is the code value corresponding to the code target, including: shifting each code sequence generated by the comparison result according to a preset shift rule of cyclic left shifting by one position, obtaining the code value after the shift processing, and saving the minimum value of the decimal values ​​corresponding to the code values ​​corresponding to each code point, which is the code value corresponding to the code target.

[0030] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0031] The present invention achieves high-precision positioning by setting a positioning module including a positioning circle and / or an identification module of coding points on the housing of the captive screw, and obtaining the positioning circle image coordinate points based on the positioning module; based on the coding belt set with several coding points, a mapping relationship between the coding value and the captive screw is realized, and the captive screw is accurately identified; through the technical solution of the present application, the captive screw can be automatically identified, positioned and assembled, thereby improving the accuracy and efficiency of mechanical operations, and helping to realize automation in the fields of high-precision mechanical assembly, disassembly, and maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1a and Figure 1b Figures of captive screw housings with coding and positioning circles are shown respectively;

[0033] Figure 2 A schematic diagram of the positioning circle on the top of the captive screw housing is shown;

[0034] Figure 3 A schematic diagram showing the coding points on the top of the captive screw housing is shown;

[0035] Figure 4a and Figure 4b The pre-processed target images of the captive screw housing with coding and positioning circle are shown respectively;

[0036] Figure 5a and Figure 5bThe elliptical outline of the pre-processed image of the captive screw housing with coding and positioning circle is shown respectively;

[0037] Figure 6 A schematic diagram of ellipse contour fitting is shown;

[0038] Figure 7 The target image of the positive projection of the pre-processed image of the captive screw housing is shown;

[0039] Figure 8 Shown is a schematic diagram of determining the target encoding center;

[0040] Figure 9 A schematic diagram of the detection circle and detection points is shown.

[0041] 1—Code point ellipse outline; 2—Positioning circle ellipse outline DETAILED DESCRIPTION

[0042] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0043] It should be noted that the term “and / or” is used as a function word to indicate that two words or expressions are used together or separately, for example, A and / or B includes A alone, B alone, and A and B together.

[0044] All directional indications in the embodiments of the present application (such as up, down, left, right, front, back, etc.) are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0045] In order to further understand the content, features and effects of the present invention, the following embodiments are described in detail with reference to the accompanying drawings:

[0046] Reference Figure 1a and Figure 1b 、 Figure 2 and Figure 3 A captive screw housing includes a positioning module, wherein the positioning module includes a positioning circle formed by several annular boundary contours arranged on the surface of the captive screw; and / or an identification module, wherein the identification module includes a coding belt composed of several coding points arranged in an annular area on the top of the captive screw housing.

[0047] In one embodiment, a positioning module and / or an identification module is set up using the external features of the captive screw housing, and a captive screw housing with a coding belt formed by several coding points and / or a captive screw housing with a positioning mark and a positioning circle is set up.

[0048] In one embodiment, the positioning module is formed on the captive screw housing by surface processing in the form of a black and white annular band, and the black and white boundary outline thereof serves as the positioning circle.

[0049] In one embodiment, the identification module is formed on the captive screw housing by using the top annular area thereof as a coding belt and processing the area to be black, and dot-type distributed coding points are provided on the coding belt.

[0050] In one embodiment, the coding points are evenly distributed in the top annular area. Specifically, the circumference of the detection circle formed by the coding band can be evenly divided into a number of coding points according to a certain interval or angle.

[0051] In one embodiment, the coding tape can be evenly divided into 8 coding points at 45 degrees. The coding points are used to provide coding value information, representing a ten-bit binary code. Each coding point can be black or white. The coding bit of the black coding point is set to the binary code "0". Since the coding tape is black, the black coding point does not show an outline in the coding tape. The coding bit of the white coding point is set to the binary code "1" for identification of loose and fixed screws.

[0052] In one embodiment, the positioning circle is realized by processing a black and white annular band on the top of the captive screw housing, and its boundary contour is used as the positioning circle. The positioning circle is used to provide position information for positioning the captive screw.

[0053] In one embodiment, several coding points of a captive screw correspond to coding values ​​for identifying the captive screw, and coding positions corresponding to the several coding points generate a coding sequence. A suitable coding value is screened according to the coding sequence, and the coding value is used to identify the captive screw.

[0054] Reference Figure 4a and Figure 4b As shown, an original image of a captive screw housing is obtained, the original image including a positioning circle image and / or a coding point image. First, an image of a captive screw housing including a coding tape and / or a positioning circle containing several coding points is obtained by a camera.

[0055] In one embodiment, a first pre-processing is performed on the positioning circle image to achieve automatic positioning of the captive screws to support automated assembly.

[0056] In one embodiment, performing the first preprocessing includes obtaining pixel coordinates of the center of the positioning circle in the positioning circle image, and calculating three-dimensional coordinates in a preset coordinate system based on the pixel coordinates; thereby achieving automatic positioning of the captive screw.

[0057] The pixel coordinates of the center of the positioning circle in the positioning circle image may be obtained based on an image processing method.

[0058] In one embodiment, the three-dimensional coordinates in the preset coordinate system can be calculated using the pixel coordinates of the center of the positioning circle through photogrammetry, binocular stereo measurement, etc. to calculate the three-dimensional coordinates in the measurement coordinate system or the world coordinate system to achieve the positioning of the captive screw.

[0059] Reference Figure 4a and Figure 4b As shown, an original image of a captive screw housing is obtained, the original image including a positioning circle image and / or a coding point image. First, an image of a captive screw housing including a coding tape and / or a positioning circle containing several coding points is obtained by a camera.

[0060] 5 to 9 , the second pre-processing of the code point image is performed to realize the automatic identification of the loose and captive screws to support the automated assembly.

[0061] In one embodiment, the second preprocessing of the coding point image includes performing preprocessing such as noise reduction filtering on the original image including the positioning circle image and / or the coding point image, enhancing the contrast of the original image to enhance the contrast of the positioning circle and / or the edge contour of the coding point, and obtaining a preprocessed image label image1; performing edge detection on the preprocessed image image1 to extract the contour information of the preprocessed image image1; performing ellipse fitting on the contour information to obtain the pixel coordinates of the ellipse center and the major and minor axis pixel sizes, clustering the ellipses in the image according to the major and minor axis sizes and the center spacing to obtain the coding point cluster cluster_code1 and / or the positioning circle cluster cluster_location1.

[0062] The contour information during ellipse fitting may be the edge contour corresponding to the positioning circle and / or the coding point.

[0063] Specifically, the calculation formula of the ellipse is as follows:

[0064]

[0065] Where (x0, y0) is the coordinate of the center of the ellipse in the pixel coordinate system of the image, a is the major semi-axis of the ellipse, b is the minor semi-axis of the ellipse, and θ is the angle between the major axis of the ellipse and the positive semi-axis of the X axis. The following formula is:

[0066]

[0067]

[0068]

[0069]

[0070]

[0071] The ellipse formula can be transformed into:

[0072] Ax 2 +Bxy+Cy 2 +Dx+Ey+F=0

[0073] Then the coordinates of the ellipse center can be expressed as:

[0074]

[0075] In one embodiment, after obtaining the coding point cluster and / or positioning circle cluster, it includes: performing perspective transformation on the contour points and center points of the coding point cluster to obtain the coding point orthographic projection cluster, and obtaining the center pixel coordinates of the center point of the coding band according to the coding point orthographic projection cluster; performing perspective transformation on the preprocessed image to obtain the orthographic projection image, and setting a number of coding points according to the center coordinates and center pixel coordinates of the orthographic projection image; selecting a starting coding point; taking the starting coding point as the starting point, sequentially comparing the first grayscale values ​​of a number of coding points with the global average grayscale value to obtain a comparison result; based on the comparison result, generating a number of coding points as a number of coding sequences corresponding to the starting coding point; selecting the coding value corresponding to the coding sequence that meets the preset conditions to realize automatic identification of loose and captive screws.

[0076] Specifically, after obtaining the post-coding point clustering and / or positioning circle clustering when ellipse fitting, it further includes calculating the pixel coordinates of the four vertices of the circumscribed rectangle of the ellipse in the positioning circle cluster, and calculating according to the preset formula based on the pixel coordinate values ​​of the four vertices to transform the projected ellipse into the perspective transformation matrix M of the orthographic projection circle; performing perspective transformation on the image image1 to obtain the orthographic projection target image of the preprocessed image, marking it as the orthographic projection image image2, and performing perspective transformation on the contour points and the center point of the coding point cluster cluster_code1 to obtain the coding point orthographic projection cluster cluster_code2;

[0077] Multiply image1 by the perspective transformation matrix M to obtain the orthographic projection image image2:

[0078] image2=image1·M

[0079] Multiply the code point cluster cluster_code1 by the perspective transformation matrix M to obtain the code point orthographic projection cluster. cluster_code2: cluster_code2 = cluster_code1·M

[0080] In one embodiment, the center pixel coordinates of the center point of the coding band are obtained according to the coding point forward projection clustering; and a plurality of coding points are set according to the center coordinates and the center pixel coordinates of the forward projection image.

[0081] Specifically, the perpendicular bisectors of the lines connecting any two coding points in the coding point orthographic projection cluster are calculated, and the intersection points of the perpendicular bisectors are calculated. The pixel coordinates of the center point of the coding band are calculated as the mean of the pixel coordinates of all the intersection points; the mean of the pixel Euclidean distances between the center points of the orthographic projection circles of all coding points and the center of the coding band is calculated, and this is used as the radius r, and the center point of the coding band is used as the center o. A detection circle is determined in the orthographic projection image image2, and the center point of any coding point is selected as coding point 1. Starting from coding point 1, traverse 360° around the center o, and take a coding point on the detection circle every 45°, which are recorded as coding point 2, coding point 3, coding point 4, coding point 5, coding point 6, coding point 7, and coding point 8, respectively. A total of 8 coding points are obtained, and the 8 coding points are evenly distributed along the circumference of the detection circle.

[0082] In one embodiment, the first grayscale value of the coding point is compared with the global average grayscale value in sequence to obtain a comparison result; based on the comparison result, a coding value of the coding point is generated; and based on the coding value, automatic identification of loose and non-loose screws is achieved.

[0083] In one embodiment, a global average grayscale of all pixels in the orthographic projection image is obtained; starting from the starting code point, the code points are detected one by one and a first grayscale value is obtained; it is determined whether the first grayscale value is less than the average grayscale; if so, the code bit of the code point is marked as 0;

[0084] If not, the coding bit of the mark coding point is 1, and according to the result of the grayscale comparison value of each detection coding point, the coding bit value of the corresponding detection coding point is obtained as "0" or "1", and the values ​​of each coding bit are saved, and finally a binary coding sequence of several bits is generated.

[0085] Specifically, calculate the global average grayscale of all pixels in image2, randomly select a coding point as the starting bit, and read clockwise to generate an 8-bit binary code. Then detect the 8 detection points in turn. If the first grayscale value of the detection point is less than the average grayscale, the coding bit is recorded as 0. If the first grayscale value is greater than or equal to the average grayscale, the coding bit is recorded as 1. It is only necessary to use any point as the starting point for search. After comparing the first grayscale values ​​of coding point 2, coding point 3, coding point 4, coding point 5, coding point 6, coding point 7, and coding point 8, 8 groups of corresponding binary coding sequences are generated to obtain a group of binary coding values. Then, they are cyclically shifted left by one position to obtain 8 groups of binary coding sequences, among which the one with the smallest corresponding decimal value is the coding value. There is no need to take the remaining 7 detection points in turn as the starting bit to generate 8-bit binary coding.

[0086] A starting coding point is selected, and the first grayscale values ​​of several coding points are compared with the global average grayscale value in sequence starting from the starting coding point to obtain a comparison result; based on the comparison result, a binary code corresponding to the coding point sequence is generated; the binary code is shifted according to a preset rule to obtain the minimum decimal code value, which is the code value corresponding to the coding target to realize automatic identification of loose and captive screws.

[0087] In one embodiment, there is no limitation on the direction in which the starting code point is compared with the code points on the circumference of the detection circle, and the comparison marks can be performed in a counterclockwise or clockwise direction.

[0088] In one embodiment, generating the coding value of the coding point includes: shifting each coding sequence generated corresponding to the comparison result according to a preset shift rule, obtaining the coding value after the shift processing, and saving the minimum value of the decimal value corresponding to the coding value corresponding to each coding point as the coding value.

[0089] Specifically, the preset shift rule can be to shift the eight-bit binary code to the left 1 bit in sequence, and calculate its corresponding decimal code value, compare all the decimal code values ​​formed after the shift of all code sequences in sequence, and find the minimum value of all decimal code values, which is the code value of the screw, thereby realizing the identification of loose and non-loose screws.

[0090] In one embodiment, the annular area on the top of the captive screw housing is used as a coding belt and processed into black. The coding belt is evenly divided into 8 coding points at 45° to represent an eight-bit binary code. Each coding point can be black or white. The black coding point is set to the binary code "0". The coding belt is set to black so that the black coding point does not show an outline in the coding belt. The white coding point is set to the binary code "1". A coding point is randomly selected as the starting position. Reading clockwise can generate an 8-bit binary number code, and then cyclically shifting it left by one position to obtain 8 groups of binary code sequences. The code value corresponding to the coding point is the minimum value of these 8 binary numbers. According to the minimum value of the code value, automatic identification of the captive screw is achieved.

[0091] Specifically, the determination of the 8-bit binary value only requires searching with any point as the starting point. After comparing the first grayscale values ​​of code point 2, code point 3, code point 4, code point 5, code point 6, code point 7, and code point 8, 8 groups of corresponding binary code sequences are generated to obtain a group of binary code values. Then, they are cyclically shifted left by one position to obtain 8 groups of binary code sequences, among which the one with the smallest corresponding decimal value is the code value. There is no need to take turns using the remaining 7 detection points as the starting position to generate 8-bit binary code. The minimum decimal code value can be determined to be the code value corresponding to the coding target, thereby realizing automatic identification of loose and captive screws.

[0092] Based on a more complex installation application scenario, the automated installation of captive screws requires the simultaneous setting of a positioning module and an identification module. After the coded point image undergoes a second preprocessing to achieve automated identification of the captive screws, if further positioning is required, the positioning circle image undergoes a first preprocessing to achieve automated positioning of the captive screws to support automated assembly. The implementation steps are the same as those described above and will not be repeated here.

[0093] Based on the disclosure and teachings of the above description, the above description is only a preferred embodiment of the present invention, and those skilled in the art may also make appropriate changes and modifications to the above embodiment. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this description, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A captive screw, characterized in that: The captive screws include: A positioning module, the positioning module comprising a positioning circle formed by a plurality of annular boundary contours arranged on the surface of the captive screw; an identification module comprising a coding strip formed by a plurality of coding points disposed in an annular area at the top of the housing of the captive screw; The first preprocessing includes obtaining pixel coordinates of the center of the positioning circle in the positioning circle image, and calculating the three-dimensional coordinates in a preset coordinate system based on the pixel coordinates; thus realizing automatic positioning of the captive screw; Performing a second preprocessing on the coded point image to extract contour information of the preprocessed image; performing ellipse fitting on the contour information to obtain the pixel coordinates of the ellipse center and the pixel sizes of the major and minor axes; clustering the ellipses in the image based on the major and minor axis sizes and the center spacing to obtain coded point clusters; After clustering, the projected ellipse is further transformed into an orthographic projection circle; During assembly, an original image of the captive screw housing is obtained, wherein the original image includes a positioning circle image and a coding point image; Performing a first preprocessing and a second preprocessing on the positioning circle image and the coding point image to achieve the automatic positioning and automatic recognition, so as to support the automatic assembly of the captive screws; Performing a first preprocessing on the positioning circle image includes: Obtaining the pixel coordinates of the center of the positioning circle in the positioning circle image; Calculating the three-dimensional coordinates in a preset coordinate system according to the pixel coordinates to achieve automatic positioning of the captive screw; The second preprocessing of the code point image includes: Preprocessing the original image to enhance the contrast of the original image and obtain a preprocessed image; extracting contour information of the preprocessed image; Ellipse fitting is performed on the contour information to obtain the pixel coordinates of the ellipse center and the pixel sizes of the major and minor axes for clustering, thereby obtaining the coding point clusters and the positioning circle clusters.

2. A captive screw according to claim 1, characterized in that: The coding points are distributed at equal intervals in the top annular area.

3. The captive screw according to claim 1, characterized in that: The plurality of coding points of the captive screw correspond to coding values ​​for identifying the captive screw.

4. A method for supporting the automated assembly of captive screws, characterized in that: The captive screw is mounted with the positioning module and the identification module according to any one of claims 1 to 3, comprising the following steps: After obtaining the coded point clusters and positioning circle clusters, it includes: Performing perspective transformation on the outline points and the center point of the code point cluster to obtain a code point orthographic projection cluster, and obtaining the center pixel coordinates of the center point of the code band according to the code point orthographic projection cluster; Performing perspective transformation on the preprocessed image to obtain an orthographic projection image, and setting a plurality of encoding points according to the center coordinates of the orthographic projection image and the center pixel coordinates; Select the starting code point; Taking the starting coding point as a starting point, sequentially comparing the first grayscale values ​​of a plurality of coding points with the global average grayscale value to obtain a comparison result; Generating a binary code corresponding to the code point sequence according to the comparison result; The binary code is shifted according to a preset rule to obtain a minimum decimal code value, which is the code value corresponding to the coding target, thereby realizing automatic identification of the captive screw.

5. A method for supporting automatic assembly of captive screws according to claim 4, characterized in that: Taking the starting coding point as a starting point, sequentially comparing the first grayscale values ​​of a plurality of coding points with the global average grayscale value, and obtaining the comparison result includes: Obtaining the global average grayscale of all pixels in the orthographic projection image; Taking the starting code point as the starting point, detecting code points in sequence and obtaining the first grayscale value; determining whether the first grayscale value is less than the average grayscale; If so, mark the code point as 0; Otherwise, mark the code point's code bit as 1.

6. A method for supporting automatic assembly of captive screws according to claim 5, characterized in that: The binary code is shifted according to the preset rules to obtain the minimum decimal code value, which is the code value corresponding to the code target. Shifting each of the code point sequences generated by the comparison result according to a preset shift rule of cyclic left shifting by one position to obtain the code value after the shifting process; The minimum value of the decimal values ​​corresponding to the code values ​​corresponding to the code points is the code value corresponding to the code target.

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