CN114018935A

CN114018935A - Multipoint rapid calibration method

Info

Publication number: CN114018935A
Application number: CN202111303895.2A
Authority: CN
Inventors: 庄一
Original assignee: Suzhou Zhongruitu Intelligent Technology Co ltd
Current assignee: Suzhou Zhongruitu Intelligent Technology Co ltd
Priority date: 2021-11-05
Filing date: 2021-11-05
Publication date: 2022-02-08

Abstract

The invention discloses a multipoint quick calibration method, which comprises the following steps: drawing Mark points at random positions on an object to be calibrated to obtain a template drawing; polishing and rotating the object to obtain a plurality of object and Mark point test charts with different angles; manually finding the center of the corresponding Mark point on the test chart, and carrying out rough alignment to obtain a matrix M; carrying out threshold segmentation on the template graph, and extracting Mark points on the template graph; performing threshold segmentation on the test chart, and obtaining the position of a Mark point on the test chart through a rotation matrix M to obtain a rotation test chart; and performing distance test on the centers of the Mark points corresponding to the rotating test chart and the plurality of test charts to obtain a rotating point, and superposing the template chart and the test charts together through rotation to finish calibration. The invention has the beneficial effects that: the idea of the algorithm is utilized to calibrate and attach the object, the calibration speed is high, the calibration cost is low, the calibration precision is high, and the operation is simple and convenient.

Description

Multipoint rapid calibration method

Technical Field

The invention relates to the technical field of industrial detection, in particular to a multipoint quick calibration method.

Background

In the industries of chip semiconductors, display panels, mobile phone panels, PCB manufacturing and the like, the manufacturing process has extremely high requirements on precision, has low tolerance on defects generated in the manufacturing process, and generally needs a high-precision defect detection method. When the visual image is used for detection, in order to ensure the detection precision, the product is usually aligned first and then compared with the standard template to locate the defect, and the alignment precision directly influences the detection effect.

In the conventional visual image defect detection method, a product is usually positioned by various external instruments such as various calibration plates and the like, and the calibration process is complex, the manufacturing cost of the calibration plates is high, the logic of a calibration algorithm is complex, the alignment error is large, the alignment precision is low, and the large calibration error and the low calibration precision are caused.

Disclosure of Invention

The invention aims to provide a multipoint quick calibration method to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme: a multipoint quick calibration method comprises the following steps:

firstly, drawing Mark points at an upper random position by taking an object to be calibrated as a template to obtain a template drawing;

polishing the object, rotating the object, and obtaining a plurality of objects with different angles and test patterns of Mark points by rotating the object at different angles;

step three, manually finding the center of the corresponding Mark point on each test chart, and carrying out rough alignment to obtain a matrix M;

fourthly, performing threshold segmentation on the template graph, and extracting Mark points on the template graph;

step five, performing threshold segmentation on the test chart, and obtaining the position of a Mark point on the test chart through a rotation matrix M to obtain a rotation test chart;

and step six, testing the distance between the rotary test chart and the centers of the corresponding Mark points on the plurality of test charts to obtain the closest point as a rotary point, and superposing the template chart and the test charts together through rotation to finish calibration.

Further preferably, the precision of the coarse alignment is no greater than 10 pixels.

Further preferably, the object is placed on a horizontal rotating table, and a motor is connected to the lower portion of the middle of the rotating table.

Further preferably, the polishing direction of each test chart is different.

Further preferably, the brightness of each test chart is different.

Further preferably, the template chart, the test chart and the rotary test chart are all acquired by an industrial camera.

Further preferably, the Mark points have an arbitrary shape.

Has the advantages that: the method is based on the frequency domain diagram, utilizes the idea of algorithm, namely the steps from one to six, to calibrate and attach the object without external instruments such as a calibration card and the like, has high calibration speed and low calibration cost, can improve the calibration precision, and is simple and convenient to operate.

Drawings

FIG. 1 is a template view of an object;

FIG. 2 is a test chart of the rotated object;

FIG. 3 is another test chart of the rotated object;

FIG. 4 is a labeled view of FIG. 1;

FIG. 5 is a labeled view of FIG. 2;

FIG. 6 is a labeled view of FIG. 3;

FIG. 7 is a schematic illustration of the rough alignment of FIG. 2;

FIG. 8 is an enlarged accuracy chart of FIG. 7;

FIG. 9 is a schematic illustration of the rough alignment of FIG. 3;

FIG. 10 is an enlarged accuracy chart of FIG. 9;

FIG. 11 is a picture after thresholding of FIG. 1;

FIG. 12 is a rotation test chart obtained by performing threshold segmentation and rotation on FIG. 2;

FIG. 13 is a rotation test chart obtained by performing threshold segmentation and rotation on FIG. 3;

FIG. 14 is a high-precision calibration chart obtained by calibrating the components shown in FIGS. 1 and 2;

FIG. 15 is an enlarged precision view of FIG. 14;

FIG. 16 is a high-precision calibration chart obtained by calibrating the components shown in FIGS. 1 and 3;

fig. 17 is an enlarged accuracy diagram of fig. 16.

Detailed Description

The following are specific embodiments of the present invention and are further described with reference to the drawings, but the present invention is not limited to these embodiments.

A multipoint quick calibration method comprises the following steps:

step one, an object to be calibrated is used as a template, Mark points are drawn at an upper random position to obtain a template drawing, as shown in figure 1, figure 1 is used as the template drawing, and the Mark points on the template drawing only need to be clearly visible;

step two, polishing the object and rotating the object, and obtaining two object and Mark point test charts with different angles and brightness by rotating the object at different angles and adjusting the polishing direction and brightness, as shown in fig. 2 and fig. 3;

step three, manually finding the center of the corresponding Mark point on each test chart, roughly aligning to obtain a matrix M, marking the matrix M in the figures 1, 2 and 3, and facilitating finding of the Mark point as shown in figures 4, 5 and 6; fig. 4 shows four

Mark points

1, 2, 3, and 4 marked in the template map of fig. 1, fig. 5 shows four Mark points S1, S2, S3, and S4 corresponding to the test map of fig. 2, and fig. 6 shows four Mark points N1, N2, N3, and N4 corresponding to the test map of fig. 3; the rough alignment is completed by marking Mark points, the results of the rough alignment of the test chart are shown in fig. 7, fig. 8, fig. 9 and fig. 10, fig. 7 and fig. 8 correspond to the test chart of fig. 2, and fig. 8 is an enlarged precision chart of fig. 7; FIG. 9 and FIG. 10 correspond to the test chart of FIG. 3, and FIG. 10 is an enlarged precision chart of FIG. 7 and FIG. 9;

step four, performing threshold segmentation on the template graph, and extracting Mark points on the template graph as shown in fig. 11;

step five, performing threshold segmentation on the test chart, and obtaining Mark point positions on the test chart through a rotation matrix M to obtain a rotation test chart, as shown in FIGS. 12 and 13;

step six, distance testing is carried out on centers of corresponding Mark points on the rotation test chart 12 and 13 and the two test charts 2 and 3 to obtain a nearest point serving as a rotation point, the template chart 1 and the test charts 2 and 3 are superposed through rotation to complete calibration, and high-precision calibration charts 14, 15, 16 and 17 are obtained, wherein the graph 15 is an enlarged precision chart of the graph 14, and the graph 17 is an enlarged precision chart of the graph 16.

According to the method, calibration is not needed through various calibration plates, rapid calibration is achieved, and calibration cost is reduced; meanwhile, the calibration precision is high, and the operation is simple. As can be seen by comparing fig. 14, 15, 16 and 17 with fig. 7, 8, 9 and 10, the calibration accuracy is improved by half.

In the application, the precision of the rough alignment is not more than 10 pixels, so that the error of manual rough alignment can be reduced.

In this application, the object is placed on horizontal rotation platform, the centre below of revolving stage is connected with the motor, rotates through the motor drive revolving stage, drives the object rotation on it, realizes carrying out different angle pictures to the object and gathers, and guarantees that the object is located the vision acquisition within range of industry camera all the time.

In this application, template picture, test chart and rotatory test chart all adopt the industry camera to gather, and it has higher image stability, high transmission ability and high interference killing feature. The CCD camera is preferably selected, so that the CCD camera has the advantages of no burn, no lag, low-voltage work, low power consumption and the like, and the definition of the acquired template graph, the acquired test graph and the acquired rotation test graph is ensured.

In the application, the Mark points are in any shapes, such as circles and polygons, and the Mark points are required to be clear, so that human eyes can recognize and search the Mark points conveniently.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the content of the present invention within the scope of the protection of the present invention.

Claims

1. A multipoint quick calibration method is characterized in that: the method comprises the following steps:

2. The multipoint rapid calibration method according to claim 1, characterized in that: the coarse alignment is not more accurate than 10 pixels.

3. The multipoint rapid calibration method according to claim 1, characterized in that: the object is placed on the horizontal rotating platform, and a motor is connected to the lower portion of the middle of the rotating platform.

4. The multipoint rapid calibration method according to claim 1, characterized in that: the polishing directions of the test patterns are different.

5. The multipoint rapid calibration method according to claim 1, characterized in that: the lighting brightness of each test chart is different.

6. The multipoint rapid calibration method according to claim 1, characterized in that: the template graph, the test graph and the rotary test graph are all collected by an industrial camera.

7. The multipoint rapid calibration method according to claim 1, characterized in that: the Mark points are in any shape.