KR100893883B1 - Apparatus and Method for Three Dimensional Measurement Using Moire and Dynamic Stereo Vision - Google Patents

Abstract

The present invention relates to a three-dimensional measuring apparatus and method using a moiré and dynamic stereo vision to improve the 2π ambiguity that may occur when measuring the three-dimensional shape of the measurement object using the moiré measurement method.

In the measuring method of the present invention, when the measurement object is transferred to the first measurement position, the moiré pattern light is projected from the measurement head to the measurement object, and then the reflected moire pattern image is taken and received by the control device using a 4-bucket algorithm. Calculating a first phase map and storing a first brightness image; controlling a measuring head feeder to transfer the measuring head to a second measuring position; and projecting a moire pattern light from the measuring head to a measuring object and then reflecting Photographing the moiré pattern image and receiving it from the control device to calculate a second phase map using a 4-bucket algorithm and to store the second brightness image, and the control device 2π in the first and second phase maps, respectively. After calculating the area where ambiguity has occurred, calculate the distance difference between the specific values of the first and second brightness images of the area where the 2π ambiguity has occurred and using the first and second Compensating the phase map and then integrated to measure the three-dimensional shape of the measurement object.

Moiré, Stereo, Vision, Dynamic, 3D

Description

Apparatus and Method for Three Dimensional Measurement Using Moire and Dynamic Stereo Vision}

1 is a block diagram of a three-dimensional measuring apparatus using a conventional moiré and stereo vision,

2 is a block diagram of a three-dimensional measuring apparatus using a moiré and dynamic stereo vision of the present invention,

3 is a flow chart showing a three-dimensional measurement method using the moiré and dynamic stereo vision of the present invention,

 4A to 4F are views illustrating a three-dimensional measurement process using moiré and dynamic stereo vision;

5 is a block diagram showing another embodiment of a three-dimensional measuring apparatus using the moiré and dynamic stereo vision of the present invention shown in FIG.

Explanation of symbols on the main parts of the drawings

10: measuring head 11: projection

12: imaging part 13: measuring head

20: measuring head feed section 30: transfer table

31: motor 40: controller

The present invention relates to a three-dimensional measuring apparatus and method using a moiré and dynamic stereo vision, and more particularly to improve the 2π ambiguity that may occur when measuring the three-dimensional shape of the measurement object using the moiré measurement method The present invention relates to a three-dimensional measuring apparatus and method using moiré and dynamic stereo vision.

The prior art for solving the 2π ambiguity that may occur when three-dimensional measurement using the moire is disclosed in the Patent Publication No. 2005-31328 (2005.04.06) and described schematically using the accompanying FIG. same.

As shown in FIG. 1, a three-dimensional measuring apparatus using a conventional moiré and stereo vision includes a projection part 2, a first imaging part 3, a second imaging part 4, and a transfer table 5. , The measurement object 1 is located on the transfer table 5 driven by the drive motor 5a. The projection part 2 which projects the moire pattern illumination onto the measurement object 1 is composed of a light source 2a, a condenser lens 2b, a projection grid 2c, a driver 2d and a projection lens 2e. The first imaging unit 3 includes a CCD camera 3a and an imaging lens 3b in order to obtain a modified moire pattern image from the measurement object 1. The second imaging unit 4 includes a CCD camera 4a and an imaging lens 4b to acquire an image of the measurement object 1.

Referring to the method of measuring a three-dimensional shape of the measurement object 1 by using a three-dimensional measuring apparatus using a conventional moiré and stereo vision having the above configuration as follows. The moiré pattern image of the measurement object 1 is obtained by using any one of the first imaging unit 3 and the second imaging unit 4 and the projection unit 2, and then the phase is extracted. When the phase is extracted, the height of the measurement object 1 is calculated using the first imaging unit 3 and the second imaging unit 4. When the height of the measurement object 1 is calculated, the measurement object 1 is conventionally measuring the height of a lead (not shown) of the semiconductor package, thereby calculating the height of each lead. When the height of each lead is calculated, the height difference between neighboring leads is calculated. Once the height difference is calculated, the actual order of the measured value is calculated. Once the actual order is calculated, it is used to compensate for the final measurement.

Since the three-dimensional measurement method of the measurement object using the moiré and stereo vision as in the prior art only provides a method for measuring the individual height of each lead of the semiconductor package, there is a problem that its application range is very limited. In addition, there is a problem in that the configuration of the three-dimensional measuring apparatus is complicated by providing two imaging units in one projection unit as shown in FIG. 1 to measure individual heights of the leads.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and using moiré and dynamic stereo vision, which can more compactly configure a measuring device for improving the 2π ambiguity that may occur during moiré three-dimensional measurement. To provide a dimensional measuring device.

Another object of the present invention is to improve the reliability of the three-dimensional shape measurement work by calculating the phase of the object to be measured at two positions and combining the phase extraction values calculated at each point to obtain an integrated phase from which phase noise is removed. To provide a 3D measurement method using moiré and dynamic stereo vision.

The three-dimensional measuring apparatus using the moiré and the dynamic stereo vision of the present invention comprises a projection part and an image forming part, and a measurement head for photographing the moiré pattern image reflected after projecting the moire pattern light to the measurement object, and the measurement head is transported. A measuring head conveying unit which is installed to be capable of being installed, a conveying table installed to be positioned below the measuring head to convey the measuring object to the first measuring position, and controlling the conveying table to convey the measuring object to the first measuring position; The measuring head feeder is controlled to move the measuring head to the second measuring position for dynamic stereo vision imaging. When the measuring head is positioned at the first and second measuring positions, the measuring head is controlled at each position to capture the first and second images. And a control device for receiving the phase information and the first and second brightness images, respectively, and measuring the three-dimensional shape of the measurement object.

In the three-dimensional measurement method using the moiré and dynamic stereo vision of the present invention, when the measurement object is transported to the first measurement position by the transfer table, the moiré pattern image is reflected after projecting the moire pattern light from the measuring head to the measurement object. Receiving this from the control unit using the 4-bucket algorithm to calculate the first phase map and to store the first brightness image, and for dynamic stereo vision imaging, the control unit controls the measuring head transfer unit to measure the second measuring head Step to transfer to the measuring position, and when the measuring head is transferred to the second measuring position project the moire pattern light from the measuring head to the measuring object and then take the reflected moiré image and receive it from the control device 4-bucket algorithm calculating a second phase map and storing a second brightness image using a bucket algorithm, and storing the second brightness map at each of the first and second measurement positions. When the first and second phase maps are calculated and the first and second brightness images are stored, the controller calculates regions where 2π ambiguity is generated in the first and second phase maps, respectively, Computing the distance difference between the specific value of the first and second brightness image, and correcting the first and second phase map by using it, characterized in that it comprises the step of measuring the three-dimensional shape of the measurement object.

(Example)

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

2 is a block diagram of a three-dimensional measuring apparatus using the moiré and dynamic stereo vision of the present invention. As shown, the three-dimensional measuring apparatus using the moiré and the dynamic stereo vision of the present invention is largely composed of a measuring head 10, measuring head transfer unit 20, transfer table 30 and the control device 40, The configuration will be described sequentially as follows.

The measuring head 10 is composed of a projection unit 11 and an image forming unit 12 to project the moire pattern light to the measurement object (1), and then take the reflected moire pattern image and transmit it to the control device 40, the measurement A head frame 11 is further provided. The measuring head frame 11 is installed to be movable in the measuring head conveying part 20. On one side, that is, on one side of the inside of the measurement head frame 11, the light source 12a, the grating element 12b, the projection lens 12c, and the grating transfer mechanism 12d are composed of the moire pattern illumination to the measurement object 1. The projection part 12 which projects this is inclinedly installed. The other side of the measurement head frame 11, that is, the other side inside the measurement head frame 11, includes a CCD camera 13a, an imaging lens 13b, an optical filter 13c, and a circular lamp 13d. An image forming unit 13 for photographing a moiré pattern image reflected from is installed.

The measuring head conveying unit 20 is installed so that the measuring head 10 can be transferred. In the case of installing the measuring head 10 in the measuring head conveying unit 20 so as to be transported, the measuring head frame 11 may be installed so as to be transported in the measuring head conveying unit 20. The measuring head conveying unit 20 may include a ball screw, a linear motor, or an air cylinder conveying mechanism to convey the measuring head 10 to the second measuring position B2. By applying any one of the measurement head 10 is to be transferred to the dynamic stereo vision imaging of the measurement object (1).

The transfer table 30 is driven by the motor 31 to transfer the measurement object 1 to the first measurement position B1 so that the measurement head 10 can photograph the measurement object 1 when the measurement object 1 is seated. In order to transfer the measurement object 1, the transfer table 30 applies the transfer table 30 which is movable in the X-Y axis direction to transfer the measurement object 10 to the first measurement position B1. Here, when the measurement object 10 is not only transferred to the first measurement position B1 using the transfer table 30 but also the measurement object 10 is transferred to an arbitrary measurement position by the transfer table 30. The measuring head conveying unit 20 may be configured to transfer the measuring head 10 to the first measuring position (B1) of the measurement object (1).

The control device 40 includes a drive controller 41, an image acquisition unit 42, and a central controller 43 to control the transfer table 30 to transfer the measurement object 1 to the first measurement position B1. And to control the measurement head transfer unit 20 for dynamic stereo vision imaging to transfer the measurement head 10 to the second measurement position (B2). When the measuring head 10 is moved in the direction of arrow 'A' at the first measuring position B1 and positioned at the second measuring positions B1 and B2, the control device 40 moves the measuring head at each position B1 and B2. The control unit 10 receives the captured first and second phase information and the first and second brightness images, respectively, and measures the three-dimensional shape of the measurement object 1. The drive controller 41 of the control device 40 includes a table controller 41a, an illumination controller 41b, a grid controller 41c, and a measurement head feed controller 41d. ), The circular lamp 13d, the measuring head feed section 20 and the motor 31 of the feed table 30 are respectively driven. In addition, the image acquisition unit 42 receives the phase information photographed by the CCD camera 13a, processes the image, and transmits the image to the central control unit 43. The central control unit 43 uses the transmitted phase information to measure the object 1. We will measure the three-dimensional shape of

The three-dimensional measuring device using the moiré and dynamic stereo vision of the present invention can be configured as shown in FIG. 5 so that the measurement object 1 can be configured more compactly by measuring the moiré and the dynamic stereo vision. have. In the three-dimensional measuring apparatus of the present invention shown in FIG. 5, the measuring object 1 is controlled by controlling the transfer table 230 without using the measuring head conveying unit 10 for dynamic stereo vision imaging of the measuring object 10. It can be configured to be transferred in the direction of the arrow 'A' so that the measurement object 1 can be transferred from the first measurement position B1 to the second measurement position B2. As a result, the configuration of the additional measurement head transfer unit 10 and the measurement head transfer controller 41d can be omitted, and thus the three-dimensional measurement device can be configured more compactly.

The measuring head 10 or the transfer table 230 is transported to collect the measurement object 1 at the first and second measurement positions B1 and B2, respectively, and to perform dynamic stereo vision imaging of the measurement object 1. A method of measuring a three-dimensional shape will be described with reference to FIGS. 2 and 3.

2 is a block diagram of a three-dimensional measuring apparatus using a moiré and dynamic stereo vision of the present invention, Figure 3 is a flow chart showing a three-dimensional measuring method using a moiré and dynamic stereo vision of the present invention. As shown in the measurement method of the present invention, first, when the measurement object 1 is transferred to the first measurement position B1 by the transfer table 230, the moire pattern illumination is transferred from the measurement head 10 to the measurement object 1. After taking the projected image of the reflected moiré pattern and receiving it from the control device 40, using the 4-bucket algorithm to calculate the first phase map 120 shown in Fig. 4b and the first brightness shown in Fig. 4e The image 130 is stored (S10). In order to calculate the first phase map 120 using a 4-bucket algorithm, the control device 40 controls the grid feed mechanism 12d to control the grid element 12b to 0, π / 2, π, 3π / 2. As long as the transfer is carried out by the image pickup unit 13 for each transfer to take a four-frame image 110 as shown in Figure 4a.

When the first phase map 120 of the measurement object 1 is calculated at the first measurement position B1 and the first brightness image 130 is stored, the control device 40 transfers the measurement head for dynamic stereo vision imaging. Control 20 to transfer the measurement head 10 to the second measurement position (B2) (S20). Instead of using the measuring head 10 to measure the measuring object 1 at the second measuring position B2, the control unit 40 controls the transfer table 230 to move the measuring object 1 to the second measuring position. Can be transferred.

When the measuring head 10 is transferred to the second measuring position B2 for dynamic stereo vision shooting, the moiré pattern image is reflected and projected from the measuring head 10 to the measurement object 1 and then reflected and photographed. The device 40 receives the received image, calculates the second phase map 220 shown in FIG. 4D using the 4-bucket algorithm, and stores the second brightness image 230 shown in FIG. 4E (S30). In order to calculate the second phase map 220 by using the 4-bucket algorithm, the grid transfer mechanism 12d is controlled by the control device 40 as in the first measurement position B1 to zero the grid element 12b. , π / 2, π, 3π / 2 is transferred and photographed by the imaging unit 13 every transfer to take a four-frame image 210 as shown in FIG. 4C.

When the first and second phase maps 120 and 220 are calculated and the first and second brightness images 130 and 230 are stored in the first and second measurement positions B1 and B2, respectively, the control device 40 determines the first and second phases. After calculating the region where the 2π ambiguity is generated in the two-phase maps 120 and 220, respectively, the distance difference between the specific values of the first and second brightness images 130 and 230 of the region where the 2π ambiguity is generated is calculated and used. And after correcting the second phase maps 120 and 220, the three-dimensional shape of the measurement object 1 is measured (S40).

The distance difference between the specific values of the first and second brightness images 130 and 230 of the region in which the 2π ambiguity is generated is calculated, and the first and second phase maps 120 and 220 are corrected and integrated, and then the measured object (1 Referring to the step (S40) of measuring the three-dimensional shape of in more detail as follows.

When the first and second phase maps 120 and 220 are calculated, the control device 40 includes phase noises C included in the first and second phase maps 120 and 220, respectively, as shown in FIGS. 4B and 4D, respectively. Phase unwrapping is performed to remove the signal (S41). When the phase noise C included in the first and second phase maps 120 and 220 is removed through phase unwrapping, the controller 40 may generate a region of 2π ambiguity in the first and second phase maps 120 and 220, respectively. The first and second phase ambiguities D1 and F1 are calculated using the information of the measurement object 1 stored in advance (S42). The information of the measurement object 1 inputs information, such as the thickness of the measurement object 1, to the control device 40 in advance, and the control device 40 uses the input information as shown in FIGS. 4B and 4D, respectively. As described above, the first and second phase maps 120 and 220 are respectively divided into regions D2 and F2 where no 2π ambiguity is generated and first and second phase ambiguity regions D1 and F1.

When the first and second phase ambiguities D1 and F1 are calculated, the control device 40 may determine the first and second phase ambiguity areas (1 and 2) in the first and second brightness images 130 and 230, respectively, as shown in FIG. The brightness specific values E of the D1 and F1 are calculated as the specific values E of the first and second brightness images 130 and 230 (S43).

When the specific values E of the first and second brightness images 130 and 230 are calculated, the controller 40 may determine the distance (or disparity) between the specific values E of the first and second brightness images E. FIG. L is calculated (S44). The distance L between the specific values E of the first and second brightness images 130 and 230 is calculated as follows using a model for calculating the binocular stereo equation shown in FIG. 4F. can do.

First, the relationship between the measurement object 1 and the CCD camera 13a shown in FIG. 4F may be expressed by Equation 1 and Equation 2 below using the binocular stereo equation model.

Here, x 'and x "represent the lengths of the images formed on the CCD camera 13a before and after the movement away from the optical axis, that is, the center of the photographing area, and d is the length between the CCD cameras 13a before and after the movement. X represents half of the base line, and x represents the length of the image captured by the CCD camera 13a before and after moving away from the center of the photographing area (meaning the number of pixels during image processing). , f represents the focal length, and z represents the distance to the moiré phase plane.

Equations 1 and 2 represented by the variables x ', x ", d, and x are represented by the following equations 3 and 4, respectively, as x' and x".

Each can be represented by Since x "-x '= L, Equations 3 and 4 may be represented by Equation 5 as follows.

In Equation 5, the distance L between the specific value E of the first and second brightness images E is calculated by using Equation 6 below.

Where z is the distance to the moiré phase plane, f is the focal length, and 2d is the baseline length.

When the distance L between the specific values E of the first and second brightness images 130 and 230 is calculated, the controller 40 determines the distance between the specific values E of the first and second brightness images 130 and 230. The actual phase order n is calculated using (L) (S45). Calculation of the actual phase order n of the phase ambiguity regions D1 and F1 using the distance L between the specific values E of the first and second brightness images 130 and 230 uses Equation 7 below. .

Here, z is the distance to the moire phase plane, z ₀ is the distance to the moire reference phase plane, and λ is the wavelength of the moire pattern.

When the actual phase order n is calculated, the controller 40 corrects the first and second phase maps 120 and 220 using the actual phase order n (S46). Equation 8 below is used to correct the first and second phase maps 120 and 220 using the actual phase order n.

Here, φ 'is the actual phase, n is the actual order of the phase ambiguity region, and φ is the measurement phase before phase correction.

When the first and second phase maps 120 and 220 are corrected, the control device 40 calculates an integrated phase map using the corrected first and second phase maps 120 and 220 to calculate a three-dimensional shape of the measurement object 1. It measures (S47).

The integrated phase map is calculated using the first and second phase maps 120 and 220 corrected as described above, the height of the measurement object 1 is measured using the calculated integrated phase map, and the height information is used. By measuring the three-dimensional shape of the measurement object 1, more reliable three-dimensional shape information can be extracted.

As described above, the three-dimensional measuring apparatus and method using the moiré and the dynamic stereo vision of the present invention have the advantage that the measuring apparatus for improving the 2π ambiguity using one projection unit and one imaging unit can be more compactly constructed. In addition, by obtaining an integrated phase from which phase noise is removed and measuring a three-dimensional shape, it is possible to provide an advantage of improving reliability of a three-dimensional measurement operation.

Claims (10)

A measuring head including an illumination source and a projection unit for projecting the grid-patterned light onto the measurement object including the grid element, and an imaging unit for photographing the grid-pattern image reflected from the measurement object; When the measuring head is positioned at the first and second measuring positions, the first phase information and the first brightness image at the first measuring position and the first brightness image photographed by controlling the measuring head at each position are measured. Receiving the second phase information and the second brightness image, calculating a distance difference between a specific value of the first brightness image and the second brightness image, and correcting the first or second phase information by using the distance difference. And a control device for calculating a three-dimensional shape of the measurement object. According to claim 1, wherein the measuring head further comprises a measuring head frame which is installed to be movable to the measuring head transfer unit for moving the measuring head, The projection unit is installed to be inclined on one side of the measuring head frame to project the grid pattern light to the measurement object, The image forming unit is installed on the other side of the measuring head frame is a three-dimensional measuring device, characterized in that for taking the grid pattern image reflected from the measurement object. Measuring the grid pattern image after the measurement head projects the grid pattern light from the first measurement position to the measurement object, receiving the result from the control device, calculating first phase information, and storing the first brightness image; Positioning the measuring head in a second measuring position; When the measuring head is positioned at the second measuring position, the grid is projected from the measuring head to the measurement object, and then the reflected grid pattern image is photographed and received by the controller to calculate second phase information. 2 storing the brightness image; The controller calculates an area where 2π ambiguity is generated from the first and second phase information, respectively, and then calculates a distance difference between the specific values of the first and second brightness images of the area where the 2π ambiguity is generated. Calculating a three-dimensional shape of a measurement object by correcting the first and second phase information using the first and second phase information. The method of claim 3, wherein the positioning of the measuring head to the second measuring position comprises controlling the transfer table in the control device to transfer the measuring object to the second measuring position. The method of claim 3, wherein the measuring of the three-dimensional shape of the measurement object comprises: Performing phase unwrapping to remove phase noise included in the first and second phase information, respectively, when the first and second phase information are calculated; When the phase noise included in the first and second phase information is removed through the phase unwrapping, the control apparatus stores information on a measurement object previously stored in a region where 2π ambiguity is generated in the first and second phase information, respectively. Calculating the first and second phase ambiguities using When the first and second phase ambiguities are calculated, the control apparatus may determine brightness values of the first and second phase ambiguities in the first and second brightness images, respectively, as specific values of the first and second brightness images. Calculating step, Calculating a distance between the specified values of the first and second brightness images when the specific values of the first and second brightness images are calculated; Calculating the actual phase order using the distance between the specified values of the first and second brightness images when the distance between the specified values of the first and second brightness images is calculated; Correcting each of the first and second phase information by using the actual phase order when the actual phase order is calculated; And if the first and second phase information are corrected, calculating the integrated phase map using the corrected first and second phase information to measure a three-dimensional shape of the measurement object. 3D measurement method. The method of claim 5, wherein the calculating of the distance between the specific values of the first and second brightness images comprises: 3D measuring method characterized in that the distance between the specific value of the first and second brightness image is calculated by the following equation.

here,

z: Distance to moiré phase plane 2d: baseline length f: focal length x ', x ": The length off the center of the image before and after the movement of the CCD camera L: distance The method of claim 5, wherein the calculating of the actual phase order using the distance between the specific values of the first and second brightness images, And calculating the actual phase order using the distance between the specific values of the first and second brightness images by the following equation.

n: actual order of phase ambiguity z: Distance to moiré phase plane z ₀ : Distance to moiré reference phase plane λ: wavelength of moire pattern The method of claim 5, wherein the correcting of each of the first and second phase information using the actual phase order includes: 3D measuring method, characterized in that for correcting the respective first and second phase information by using the actual phase order according to the following equation.

φ ': actual phase n: actual order of phase ambiguity φ: measured phase before phase correction The method of claim 3, wherein the calculating of the first phase information and storing the first brightness image and the calculating of the second phase information and storing the second brightness image include: And the control device uses an N-bucket algorithm. Where N is a natural number of 2 or more The method of claim 1, And the control device calculates the first and second phase information by using an N-bucket algorithm and stores the first and second brightness images. Where N is a natural number of 2 or more

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