KR101750883B1 - Method for 3D Shape Measuring OF Vision Inspection System - Google Patents

Abstract

The present invention relates to a vision inspection system for measuring a three-dimensional shape of a measurement object using a pattern image reflected after irradiating pattern light on a measurement object in at least one projector, Wherein a moire degree for a phase of a second wavelength is determined using phase information of a first wavelength when the pattern illumination uses a pattern of a different wavelength, Determining a moire degree for each mounted component; Obtaining a plurality of pattern images for the measurement object using the illumination pattern of the second wavelength after the moire degree for the measurement object is determined; And calculating the actual data of the measurement object using the plurality of pattern images and calculating the height data of the actual measurement object by reflecting the moire degree to the actual data. Therefore, according to the present invention, after determining the moire degree for the measurement object, the height data of the part is measured using only the pattern illumination of a small wavelength in the three-dimensional shape measurement, and then the moiré degree is reflected in the measured height data, Since the height data is calculated, the number of measurement images can be reduced to about half that of the conventional three-dimensional shape measuring method while solving the ambiguity of 2?, And the inspection time can be reduced accordingly.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of measuring a three-dimensional shape of a vision inspection system,

The present invention relates to a three-dimensional shape measurement method of a vision inspection system, and more particularly, to a three-dimensional shape measurement method of a vision inspection system capable of reducing the number of measurement images required for measuring a three- And a measurement method.

The 3D vision inspection technology for the inspection of a typical part adjusts the initial position in the position adjusting device when the measurement object is horizontally conveyed through the conveyor. When the illumination with the grid pattern structure is checked after the adjustment is completed, The shape of the irradiated grating light is photographed to check the height.

 These three-dimensional vision inspection techniques are developed and used by laser triangulation, stereo measurement, and moiré principle. Since this measurement method uses optical, it is possible to obtain a fast and accurate three-dimensional shape.

All three-dimensional vision inspection techniques use a trigonometric function to calculate a three-dimensional height or phase-shifting by measuring a two-dimensional shape.

In the vision inspection technique using the phase shift method, there arises a problem of 2? Ambiguity in which a measurement error occurs when the height difference between two adjacent measurement points is equal to or greater than an integral multiple of the equivalent wavelength of the light source, and the measurement range of the object to be inspected is limited according to the stripe pitch .

In the past, when the phase shift of the point to be measured deviates by more than 2? From the surrounding point, the problem of 2? Ambiguity is solved by correcting 2? To the height value of the measuring point and reflecting it to the resultant value.

However, in the three-dimensional shape measuring method using the phase shift method according to the related art, when two measurement objects are located apart from each other by 2? Or more, whether the measurement result is a result of 2? Ambiguity or a measurement object having a depth of 2? It is difficult to distinguish the recognition, and there still exists a problem that an inaccurate result may occur. That is, 2π ambiguity can be obtained to obtain relative three-dimensional information, but it is impossible to obtain accurate three-dimensional information.

Accordingly, in order to solve the ambiguity of 2?, The apparatus and method for measuring three-dimensional shape using multiple wavelengths take four images in one cycle because the shape of the measurement object is measured while shifting the phase of the grating every 1/4 cycle. In this case, since the pattern illumination of different wavelengths is used, four images are taken in pattern light of a large wavelength and four images are taken in a pattern light of a small wavelength, so that eight images (at least six images) .

Conventionally, in the 3D shape measurement technique using multiple wavelengths, there is a problem that the inspection time becomes longer as the number of times of taking a measurement image for measuring a three-dimensional shape increases.

Korean Patent No. 10-1190122 entitled " Apparatus and method for measuring three-dimensional shape using multi-wavelength "

The present invention is characterized in that when measuring a three-dimensional shape of a measurement object using pattern lights having multiple wavelengths, a moire degree for each component of the measurement object is set in advance, and then, It is possible to reduce the number of measurement images by about half compared with the conventional three-dimensional shape measurement method and to reduce the inspection time accordingly.

Among the embodiments, a method of measuring a three-dimensional shape of a vision inspection system is a vision inspection system for measuring a three-dimensional shape of the measurement object using a pattern image reflected after irradiating a pattern illumination on an object to be measured by at least one projector Wherein a moire degree for a phase of a second wavelength is determined using phase information of a first wavelength when the pattern illumination uses a pattern of a different wavelength, Determining a moire degree for each mounted component; Obtaining a plurality of pattern images for the measurement object using the illumination pattern of the second wavelength after the moire degree for the measurement object is determined; And calculating actual data of the measurement object using the plurality of pattern images and calculating height data of the actual measurement object by reflecting the moire degree to the actual data.

Wherein when the pattern illumination uses a pattern of a different wavelength, a moire degree with respect to a phase of the second wavelength is determined using phase information of the first wavelength, and a moire degree with respect to each component mounted on the measurement object is The determining step may include the step of extracting height data from the CAD data for the measurement object and determining a moire degree for each part before measuring the three-dimensional shape of the measurement object.

Wherein when the pattern illumination uses a pattern of a different wavelength, a moire degree with respect to a phase of the second wavelength is determined using phase information of the first wavelength, and a moire degree with respect to each component mounted on the measurement object is Wherein the step of determining the illumination pattern of the first wavelength and the illumination pattern of the second wavelength is performed by using the pattern of the first wavelength lambda 1 and the pattern of the second wavelength lambda 2, Acquiring a first pattern image and a second pattern image to be reflected after irradiating the measurement object, calculating the first phase information and the second phase information in the acquired first pattern image and the second pattern image, respectively, And the moire degree for the second phase information is determined using the first phase information.

Calculating a shadow size by extracting a shadow region for each component in the plurality of pattern images, estimating a moire degree of the corresponding component using the calculated shadow size, calculating a moire degree of the component based on the estimated moire degree, And judging the measurement error of the part by confirming whether it is matched.

Calculating the actual data of the measurement object using the plurality of pattern images and calculating the height data of the actual measurement object by reflecting the moire degree to the actual data, when the actual data is pi (pi) or more (N = n, 0) to the measured data to calculate height data of the actual measured object, and when the measured data is less than pi, the measured data And the height data of the actual measurement object is calculated by adding the reference data (2 pi x (n + 1)) using the moire degree (N = n + 1) to the data.

A three-dimensional shape measuring method of the vision inspection system of the present invention is characterized in that after determining the moire degree for the measurement object, the height data of the part is measured using only the pattern illumination of a small wavelength in the three- Since the actual height data of the measurement object is calculated by reflecting the moire degree, the number of measurement images can be reduced to about half of the conventional three-dimensional shape measurement method while resolving the 2? Ambiguity, and the inspection time can be reduced .

1 is a block diagram illustrating a configuration of a vision inspection system according to an embodiment of the present invention.
2 is a flowchart illustrating a method of measuring a three-dimensional shape of a vision inspection system according to an exemplary embodiment of the present invention.
FIG. 3 is a diagram illustrating a shadow region measuring process according to an embodiment of the present invention. Referring to FIG.

The description of the present invention is merely an example for structural or functional explanation, and the scope of the present invention should not be construed as being limited by the embodiments described in the text. That is, the embodiments are to be construed as being variously embodied and having various forms, so that the scope of the present invention should be understood to include equivalents capable of realizing technical ideas. Also, the purpose or effect of the present invention should not be construed as limiting the scope of the present invention, since it does not mean that a specific embodiment should include all or only such effect.

Meanwhile, the meaning of the terms described in the present invention should be understood as follows.

The terms "first "," second ", and the like are intended to distinguish one element from another, and the scope of the right should not be limited by these terms. For example, the first component may be referred to as a second component, and similarly, the second component may also be referred to as a first component.

It is to be understood that when an element is referred to as being "connected" to another element, it may be directly connected to the other element, but there may be other elements in between. On the other hand, when an element is referred to as being "directly connected" to another element, it should be understood that there are no other elements in between. On the other hand, other expressions that describe the relationship between components, such as "between" and "between" or "neighboring to" and "directly adjacent to" should be interpreted as well.

It should be understood that the singular " include "or" have "are to be construed as including a stated feature, number, step, operation, component, It is to be understood that the combination is intended to specify that it does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In each step, the identification code (e.g., a, b, c, etc.) is used for convenience of explanation, the identification code does not describe the order of each step, Unless otherwise stated, it may occur differently from the stated order. That is, each step may occur in the same order as described, may be performed substantially concurrently, or may be performed in reverse order.

All terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs, unless otherwise defined. Commonly used predefined terms should be interpreted to be consistent with the meanings in the context of the related art and can not be interpreted as having ideal or overly formal meaning unless explicitly defined in the present invention.

1 is a block diagram illustrating a configuration of a vision inspection system according to an embodiment of the present invention.

1, the vision inspection system 100 includes a stage 110, a plurality of lights (not shown), an illumination driving unit 120, a vertical camera 130, a plurality of projectors 140, a projector driving unit 145, a grabber 150, an image processing unit 160, and an interface unit 170.

The stage 110 supports the object to be measured, and moves the object to be measured to the measurement position while moving under the control of the image processor 160.

The illumination may include various numbers and types of illumination, such as an LED or a spatial light modulator (SLM), for color illumination or white illumination of a measurement object.

The illumination driving unit 120 may control the illumination of the plurality of projectors 140 or the illumination of the plurality of projectors 140 for a predetermined period of time according to the illumination control signal or may change the illumination brightness value of each illumination provided from the image processing unit 160 through the interface unit 170 Adjust the brightness of each lighting accordingly.

The vertical camera 130 is installed on the stage 110 to capture an image of the measurement object and output a video signal. The vertical camera 130 is a camera for acquiring a two-dimensional image in a state in which the color illumination is on, and performs a two-dimensional inspection using the captured color image. Here, a color image is used to shape a three-dimensional image through texturing of three-dimensional data.

The vertical camera 130 acquires a pattern image in a state in which a pattern illumination of a vertical pattern or a horizontal pattern is irradiated by the projector 140, and calculates a three-dimensional shape of the measurement object using the acquired pattern image 3 Perform dimension checking.

The projector 140 can project pattern-specific illumination to the measurement object by loading the illumination pattern data for the pattern illumination in accordance with the purpose of the digital vision inspection. The projector 140 can project the pattern illumination to the measurement object through the image processing unit 160, Can be set. The projector 140 may be a 3D optical system for irradiating a vertical pattern or a horizontal pattern to the surface of the object to be measured. The period of the pattern may be determined according to the pattern data provided by the image processing unit 160.

A plurality of such projectors 140 are disposed around the vertical camera 130 so as to face each other. 3, the first projector 141 and the third projector 133 are provided so as to oppose each other on the right and left sides of the vertical camera 130, and the second projector 142 and the fourth projector 133, And the vertical camera 130 are installed so as to face each other on the upper and lower sides of the vertical camera 130. The first to fourth projectors 141, 142, 143, and 144 may be disposed on the same concentric circle around the vertical camera 130.

The projector driving unit 145 operates the projector 140 in accordance with the illumination control signal when the trigger signal of the image processing unit 160 is transmitted and outputs the image acquisition signal And transmits it to the grabber 150. In addition, the projector driving unit 145 loads and stores pattern data for a pattern that meets the purpose of the vision inspection in a digital manner.

The grabber 150 instructs the photographing of the vertical camera 130 according to the image acquisition signal and converts the image signal of the pattern image transmitted through the connection line of the vertical camera 130 into a digital signal, To the processing unit 160.

The image processor 160 processes the digital image signal transmitted from the grabber 150 and outputs the digital image signal. The image processing unit 160 controls the operation of the stage 110, the illumination, the illumination driving unit 120, the vertical camera 130, the projector 140, and the grabber 150 as a whole.

The image processing unit 160 may output the measurement image or the measurement result data of the measurement object to the display unit (not shown) using the image signals captured by the vertical camera 130, It is possible to check the shape of the object to be measured or judge whether or not the object is defective through the image or the measurement result data.

Here, the image processing unit 160 may be a communication device capable of connecting to the network such as a desktop computer, a laptop computer, a smart phone, a tablet PC, and the like. The image processing unit 160 may include image processing and vision inspection There is no limit to the type of terminal that can be used.

The interface unit 170 receives the trigger signal generated by the image processor 160 and transmits the trigger signal to the projector driver 145.

FIG. 2 is a flowchart illustrating a method of measuring a three-dimensional shape of a vision inspection system according to an exemplary embodiment of the present invention. FIG. 3 is a diagram illustrating a shadow area measurement process according to an exemplary embodiment of the present invention.

Referring to FIGS. 2 and 3, when the illumination pattern uses multiple wavelengths, the 3D shape measurement method of the vision inspection system determines the moire degree with respect to the phase of the second wavelength using the phase information of the first wavelength (S1) At this time, the illumination pattern can use a pattern of a large wavelength lambda 1 and a small wavelength lambda 2, and can obtain a pattern having a small equivalent wavelength lambda 11, lambda 12 ) May be used.

The vision inspection system can determine the degree of moiré for each part by extracting the height data of the part for the measurement object using the CAD data in the initial teaching process.

If there is no CAD data, the vision system uses the illumination pattern of the first wavelength and the illumination pattern of the second wavelength, if the illumination pattern uses the pattern of the first wavelength lambda 1 and the second wavelength lambda 2, A first pattern image and a second pattern image that are reflected after irradiation are obtained, respectively, and first phase information and second phase information are calculated in a first pattern image and a second pattern image, respectively, Determine the moire degree for 2-phase information.

 The vision system uses the first equivalent wavelength lambda 11 and the second equivalent wavelength lambda 12 and lambda 12 > lambda 11 in a case where the illumination pattern uses a plurality of patterns having the slightly equivalent wavelength lambda 11 and lambda 12 The third phase information on the beatted equivalent wavelength lambda 13 is calculated because the beatted equivalent wavelength (lambda 13, lambda 13 > lambda 12) is generated, and the third phase information on the first phase lambda 11 Determines the moire degree of information.

In the case where the object to be measured is a PCB on which a plurality of parts are mounted on a substrate, since the size and height are different according to the types of parts, the number of moiré motors applied to the parts depends on the type of parts.

After the moire degree for the measurement object is determined in this way, the vision inspection system acquires four pattern images for the measurement object using only the pattern illumination of the small wavelength (? 2 or? 11) The vision inspection system calculates the phase information for the measurement object in the four pattern images and calculates the actual measurement data for each part by using the phase-height calculation formula using the calculated phase information (S3 to S4)

The vision inspection system calculates the height data for the actual measurement object by reflecting the Moire degree (N) to the actual measurement data. (S5) At this time, the height data for the actual measurement object is the reference data 2π × N).

When the actual height data of the part mounted on the measurement object corresponds to an integer multiple of the mode value, the vision inspection system determines whether the measured data of the part 1 is equal to or larger than pi (pi) and determines the moire degree to be applied to the part 1 do.

That is, the vision inspection system adds the reference data (2? N) using the moire degree (N = n, n? 0) to the actual data when the actual data of the component 1 is pi Height data is calculated and the height data of the actually measured object is calculated by adding the reference data (2 pi x (n + 1)) using the moire degree (N = n + 1) to the measured data when the measured data is less than pi .

For example, in the case where the height data of the part 1 corresponds to 4π and the moire degree N is n = 1, if the measured data of the measurement object measured using the pattern illumination of the small wavelength λ2 or λ11 is 2π Since the data is larger than π, the height data of the actual measured object becomes 2π + 2π × 1 = 4π.

If the actual data of the measurement object measured using the pattern illumination of the small wavelength lambda 2 or lambda 11 is 0, the measured data is smaller than? So that the moire degree N becomes n + 1, that is, 2, Is 0 + 2 pi x 2 = 4 pi.

On the other hand, the vision inspection system extracts the shadow region of the corresponding component in the pattern image, and calculates the size of the extracted shadow region by using Equation (1). That is, as shown in FIG. 3, the shadow size S can be obtained from Equation (1) using a formula for determining the length of a side of a right triangle.

In Equation (1), h is the height of the measurement object, and? Is the angle of the projector with the vertical line.

The vision inspection system can calculate the actual height value of the measurement object using the shadow size, and estimate the moire degree of the corresponding component using the actual height value. When the estimated moire degree differs from the moire degree applied to the part, the part can be judged to be a part out of the measurement range by the illumination pattern of a large wavelength or a measurement error state.

Conventionally, in order to measure a three-dimensional shape of a measurement object, four times image capturing is performed in a pattern light of a large wavelength, and four times in a pattern light of a small wavelength, so that a total of eight images must be captured. However, in the present invention, since the moire degree is determined and used before the three-dimensional shape measurement, the three-dimensional shape can be measured by imaging four times only in a pattern illumination of a small cycle. Therefore, according to the present invention, as compared with the conventional three-dimensional shape measuring method, the number of times of taking a measurement image is reduced and the number of image taking times is reduced, so that a three-dimensional inspection time can be shortened.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention as defined by the following claims It can be understood that

110: stage 120:
130: vertical camera 140: plural projectors
145: Projector driving part 150: Grabber
160: image processor 170:

Claims (5)

A shape measuring method performed by a vision inspection system for measuring a three-dimensional shape of a measurement object using a pattern image reflected after irradiating a pattern illumination on a measurement object in at least one projector,
Wherein when the pattern illumination uses a pattern of a different wavelength, a moire degree with respect to a phase of the second wavelength is determined using phase information of the first wavelength, and a moire degree with respect to each component mounted on the measurement object is Determining;
Obtaining a plurality of pattern images for the measurement object using the illumination pattern of the second wavelength after the moire degree for the measurement object is determined; And
Calculating actual data of the measurement object using the plurality of pattern images, and calculating height data of the actual measurement object by reflecting the moire degree to the measured data. Shape measuring method.
The method of claim 1, wherein
Wherein when the pattern illumination uses a pattern of a different wavelength, a moire degree with respect to a phase of the second wavelength is determined using phase information of the first wavelength, and a moire degree with respect to each component mounted on the measurement object is The step of determining,
Wherein the height data is extracted from the CAD data of the measurement object before the measurement of the three-dimensional shape with respect to the measurement object to determine a moire degree for each part.
The method according to claim 1,
Wherein when the pattern illumination uses a pattern of a different wavelength, a moire degree with respect to a phase of the second wavelength is determined using phase information of the first wavelength, and a moire degree with respect to each component mounted on the measurement object is The step of determining,
Wherein when the pattern illumination uses a pattern of the first wavelength? 1 and the second wavelength? 2,? 2 <? 1, the illumination pattern of the first wavelength and the illumination pattern of the second wavelength are respectively irradiated to the measurement object And the first phase information and the second phase information are respectively obtained from the acquired first pattern image and the second pattern image, and the first phase information and the second phase information are calculated, Wherein the moire degree for the second phase information is determined using the second phase information.
The method according to claim 1,
Calculating a shadow size by extracting a shadow region for each component in the plurality of pattern images, estimating a moire degree of the corresponding component using the calculated shadow size, comparing the estimated moire degree with a moire degree And determining a measurement error of the component by confirming whether or not the component is misaligned.
The method according to claim 1,
Calculating the actual data of the measurement object using the plurality of pattern images, and calculating the height data of the actual measurement object by reflecting the moire degree to the actual data,
(N = 0, n? 0) is added to the actual data to calculate height data of an actually measured object when the actual data is equal to or larger than pi (pi)
(N + 1)) using the moire degree (N = n + 1) is added to the actual data in the case where the actual data is less than pi, thereby calculating the height data of the actually measured object A method for measuring a three dimensional shape of a vision inspection system.

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