KR100269119B1 - Method and apparatus for calibration of light vision sensor - Google Patents

Abstract

PURPOSE: A calibration method and a device of an optical vision sensor is provided to improve relative calibration precision by effectively increasing numbers of object points. CONSTITUTION: After installing a reference optical vision sensor at a reference point, a light beam(36) is illuminated perpendicular to several strings(37). The first position coordinates of the light reception points are determined by the reference optical vision sensor. After installing an optical vision sensor(33) for calibration at the reference point, a light beam(36) is illuminated perpendicular to the several strings(37). The second position coordinates corresponding to the light reception points of the several strings(37) are determined. The measurement algorithm is changed to calibrate the difference of the first and second position coordinates.

Description

Method and apparatus for calibrating an optical vision sensor {Method and apparatus for calibration of light vision sensor}

The present invention relates to a method and apparatus for calibrating an optical vision sensor.

A general optical vision sensor is used in a system for measuring the shape of a target object in order to perform position control for a robot or the like. As a representative example thereof, there may be mentioned a laser vision sensor provided with a laser beam generator and a charge coupled device (CCD) camera. The laser beam generating unit irradiates the laser beam to the object. The CCD camera converts the laser light signal from the object into an electrical signal. Accordingly, the system can measure the three-dimensional shape of the object by processing the electrical signal from the CCD camera. Calibration for the optical vision sensor used in this way is necessary to accurately measure the object. In calibration of an optical vision sensor, a multi-stage calibration apparatus is conventionally irradiated with an optical beam from an optical vision sensor and its switching points are applied as calibration points.

1 and 2, in the conventional calibration method of the optical vision sensor, the multi-stage calibration device 12 irradiates the light beam 13 from the optical vision sensor 11, the switching points 241, 242, 243, 244, 245 are adapted to the target points. That is, as the light is irradiated to the multi-stage calibration apparatus 12, the multi-stage shapes 14 and 24 appear, and the switching points 241, 242, 243, 244 and 245 are applied to the target points. The position coordinates for these target points are compared with the reference position coordinates, and the deviation of the measurement algorithm of the system is changed.

In the conventional calibration method as described above, since the target points are obtained from the multistage calibration device 12, the number of target points is relatively limited. As a result, the accuracy of calibration is relatively low.

It is an object of the present invention to provide a method and apparatus for calibrating an optical vision sensor that can efficiently increase the number of target points thereof.

1 is a schematic view showing a calibration apparatus of a conventional optical vision sensor.

FIG. 2 is a diagram of an image obtained from the optical vision sensor of FIG. 1.

3 is a schematic view showing a calibration device according to the present invention.

4 is a diagram of an image acquired from the laser vision sensor of FIG. 3.

FIG. 5 is a view of an image that appears as the strings of FIG. 3 move.

<Description of the code | symbol about the principal part of drawing>

11, 33 ... optical vision sensor, 13, 36 ... optical beam,

12 ... stage device, 14, 24 ... stage shape,

241, ..., 245, 41, ..., 50, 51, ..., 60 ...

331 ... CCD camera, 332 ... laser beam generator,

37 strings, 31 ...

32 ... frame.

The calibration method of the optical vision sensor of this invention for achieving the said objective is used for the system which measures the shape of a target object. The method includes providing a plurality of strings arranged next to each other at predetermined intervals. Next, a reference light vision sensor is mounted at a reference position to irradiate light beams orthogonal to the plurality of strings. Next, through the reference light vision sensor, first position coordinates for light receiving points of the plurality of strings are obtained. An optical vision sensor to be calibrated next is seated at the reference position to irradiate a light beam orthogonal to the plurality of strings. Next, a second position coordinate for light receiving points of the plurality of strings is obtained through an optical vision sensor on which the calibration is to be performed. The measurement algorithm of the system is changed to correct the difference between the first and second position coordinates.

Accordingly, by applying the light receiving points for the plurality of strings, it is possible to efficiently increase the number of calibration target points.

Moreover, the calibration apparatus of the optical vision sensor of this invention for achieving the said objective is used for the system which measures the shape of a target object. The apparatus comprises a frame, a plurality of strings, a fixing means and a moving means. The frame is provided with a mounting portion of the optical vision sensor. The plurality of strings are arranged side by side in a direction orthogonal to the light beam irradiated by the light vision sensor seated on the frame. The fixing means is installed in the frame to fix the plurality of strings. The moving means moves the fixing means stepwise such that the distance between the plurality of strings and the optical vision sensor is adjusted step by step.

Preferably, the optical vision sensor includes a laser beam generator and a CCD camera. The laser beam generating unit irradiates a laser beam onto the target object. The CCD camera converts a laser light signal from the target object into an electrical signal.

Hereinafter, preferred embodiments of the present invention will be described in detail.

Referring to FIG. 3, the calibration apparatus of the laser vision sensor 33 according to the present invention includes a frame 32, a plurality of strings 37, and a fixing frame 31. The frame 32 is provided with mounting portions of the laser vision sensor 33. The plurality of strings 37 are arranged in parallel with each other in a direction orthogonal to the laser beam 36 irradiated by the laser vision sensor 33 seated on the frame 32, and the seating portion of the laser vision sensor 33 is arranged. It is installed so as to be movable so that the distance between the body and the body increases and decreases by 10 mm (mm). That is, the fixing frame 31 for fixing the plurality of strings 37 can be moved in stages by the moving means, so that the distance between the plurality of strings 37 and the laser vision sensor 33 can be adjusted in stages. Can be.

The laser vision sensor 33 includes a laser beam generator 332 and a CCD camera 331. The laser beam generator 332 generates the laser beam 36 irradiated to the measurement target object. The CCD camera 331 converts the laser light signal from the measurement object into an electrical signal.

3, 4 and 5, the calibration process of the laser vision sensor 33 according to the present invention will be described sequentially.

First, the reference laser vision sensor is mounted on the seating portion of the frame 32 to irradiate a laser beam 36 that is orthogonal to the plurality of strings 37. 4 illustrates an image obtained from the laser vision sensor of FIG. 3. When ten strings 37 are suspended on the fixing frame 31, ten calibration points 41, ..., 50 are created. When the fixing frame 31 is moved step by step while the laser beam 36 is irradiated to the ten strings 37, the matrix object points 51, ..., 60 as shown in FIG. Is generated. For example, if the fixing frame 31 suspended from ten strings 37 moves up to 15 steps on the frame 32, 150 object points 51, ..., 60, ... are generated. . The system (not shown) obtains three-dimensional position coordinates of these target points 51, ..., 60 and stores them as first position coordinates, that is, reference position coordinates.

Next, the laser vision sensor 33 to be calibrated is mounted on the seating portion of the frame 32 to irradiate a laser beam orthogonal to the plurality of strings 37. When the fixing frame 31 is moved step by step while the laser beam 36 is irradiated to the ten strings 37, the matrix object points 51, ..., 60 as shown in FIG. Is generated. The system obtains the three-dimensional position coordinates of the target points 51,... 60, that is, the second position coordinates. And modify the measurement algorithm of the system so that the difference between the first and second position coordinates is corrected.

As described above, according to the calibration method and apparatus of the optical vision sensor according to the present invention, since the number of the target points thereof can be efficiently increased, the accuracy of calibration is relatively high.

The present invention is not limited to the above embodiments, and modifications and improvements are possible at the level of those skilled in the art.

Claims (4)

In the calibration method of the optical vision sensor used in the system for measuring the shape of the target object, Providing a plurality of strings arranged side by side at a predetermined interval; Mounting a reference light vision sensor at a reference position to irradiate an orthogonal light beam with respect to the plurality of strings; Obtaining, via the reference light vision sensor, first position coordinates for light receiving points of the plurality of chords; Mounting an optical vision sensor to be calibrated at the reference position to irradiate a light beam orthogonal to the plurality of strings; Obtaining second position coordinates for the light receiving points of the plurality of strings, through the optical vision sensor on which the calibration is to be performed; And And modifying a measurement algorithm of the system such that the difference between the first and second position coordinates is corrected. The optical vision sensor of claim 1, A laser beam generator for irradiating a laser beam onto the target object; And And a CCD camera for converting a laser light signal from the target object into an electrical signal. In the calibration device of the optical vision sensor used in the system for measuring the shape of the target object, A frame provided with a seating portion of the optical vision sensor; And A plurality of strings arranged in parallel with each other in a direction orthogonal to an optical beam irradiated by the optical vision sensor mounted on the frame; Fixing means mounted to the frame to fix the strings; And And a moving means for moving the fixing means stepwise such that the distance between the plurality of strings and the optical vision sensor is adjusted stepwise. The optical vision sensor of claim 3, A laser beam generator for irradiating a laser beam onto the target object; And And a CCD camera for converting a laser light signal from the target object into an electrical signal.

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