JP2002310625A - Three-dimensional measuring method and instrument thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a three-dimensional measuring method and its measuring instrument, capable of accurately measuring the surface shape of a measuring object by reducing adjustment errors in the installation angle of a light source for irradiating the measuring object with the measuring light. SOLUTION: A lighting system 12 is rotated, so that the length direction of a slit light 15 becomes parallel with respect to a plane including a perpendicular erected on an imaging visual field surface and the emitting optical axis of the slit light 15, and the slit light 15 is applied to an imaging visual field surface 14 from the lighting system 12 to measure a width WA of the slit light 15 applied to the imaging visual field surface. Then, the lighting system 12 is rotated by 90 deg., so that the length direction of the slit light 15 becomes vertical with respect to the plane, including the perpendicular erected on the imaging visual field surface and the emission optical axis of the slit light 15, and the slit light 15 is applied to the imaging visual field surface from the lighting system 12 for measuring a width WB of the slit light 15 irradiated to the imaging visual field surface. An illuminating angle α of the slit light 15 is determined from cosα=WA/WB, from the measured widths WA and WB of the slit light 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a three-dimensional measuring method using a light section method and an apparatus therefor. For more information,
The present invention relates to a three-dimensional measurement method and a three-dimensional measurement method capable of detecting a three-dimensional shape at a light irradiation position by irradiating slit light to a measurement target from a direction different from that of an imaging device.

[0002]

2. Description of the Related Art When performing three-dimensional measurement, a slit beam is applied to an object to be measured from obliquely above, and the bending distance of the irradiated light is measured in an image to measure the three-dimensional height of the object. A method called a method has been conventionally used.

FIG. 1A is a diagram showing a configuration of a three-dimensional measuring apparatus 1 using a light section method. The lighting device 2 is installed at an angle of α with respect to a perpendicular C standing on the surface of the measurement object 5, and the camera 3 is installed at an angle of β. The slit light 4 emitted from the illumination device 2 is
The slit light 4, which extends in a direction perpendicular to a plane including the emission direction of the slit light 4 and the perpendicular C, is emitted from the illumination device 2 toward the measurement target 5 from obliquely above. FIG. 1B shows an image of the measurement object 5 having the concave portion 6 photographed by the camera 3. In the case of FIG. 1B, if the camera 3 measures a shift t between the center of the irradiation slit light 4 in the flat portion 7 of the measurement object 5 and the center of the irradiation slit light 4 in the concave portion 6, the illumination device The height information (in this case, the depth) of the concave portion 6 at the slit light irradiation position can be obtained using the installation angles α and β of the camera 2 and the camera 3.

In the measuring device 1 using such a light cutting method, the illuminating device 2 is inclined sideways so that the emission angle α of the slit light 4 is
Is larger, the lateral shift of the irradiation slit light 4 in the step portion becomes larger. Therefore, if the step has the same height, the deviation of the irradiation slit light 4 measured by the camera 3 becomes larger, and the projection magnification of the slit light 4 Becomes larger. Here, the projection magnification e is defined as h, where the height of the step portion at the light irradiation position is h, and the deviation between the irradiation slit light 4 below the step and the irradiation slit light 4 above the step measured by the camera 3 is t.
Where, projection magnification e = t / h = sin (α + β) / cosα (1) Therefore, the projection magnification e is determined only by the installation angle β of the camera and the installation angle α of the illumination device, and the height h of the stepped portion at the slit light irradiation location is calculated by using the projection magnification e as h = t / e = t · cosα / sin (α + β) (2)

FIG. 2 shows that the camera 3 is installed vertically (β =
0), the projection magnification e when the angle α of the illumination device 2 is changed
Is represented. In this case, as can be seen from the above equation (1), the projection magnification e is e = tanα. In the region where the irradiation angle α of the slit light 4 is close to 90 °, as can be seen from the curve of the projection magnification e of FIG. The irradiation angle α may be made large, but on the other hand, in order to keep the error Δe of the projection magnification e to a constant value, the adjustment error Δα of the irradiation angle α gradually increases as the irradiation angle α of the slit light 4 increases. Strictness is required. For example, if an attempt is made to set the projection magnification e to be twice as shown in FIG.
Is set vertically, and the irradiation angle α of the slit light 4 is 63.
What is necessary is just to set to 43 degrees. At this time, the projection magnification error Δ
If e is to be set to 0.1 or less, the emission angle adjustment error Δα of the slit light 4 must be suppressed to 1.19 ° or less. On the other hand, in order to set the projection magnification e to 10 times, the camera may be set vertically and the irradiation angle α of the slit light 4 may be set to 84.29 °. At this time,
In order to reduce the projection magnification error Δe to 0.1 or less, the emission angle adjustment error Δα of the slit light 4 needs to be suppressed to within 0.05 °.

FIG. 3 is a view three-dimensionally showing the relationship among the irradiation angle α of the slit light 4, the installation angle β of the camera 3, and the projection magnification e. As can be seen from this figure, even when the installation angle β of the camera 3 is not vertical (β ≠ 0), in order to obtain a large projection magnification e, the irradiation angle α of the slit light 4 may be increased. Under such installation conditions, the adjustment error Δα of the irradiation angle α of the slit light 4 becomes severe. On the other hand, it is also understood that the projection magnification e is not so sensitive to the installation angle β of the camera 3.

Therefore, in such a measuring apparatus 1, it is necessary to increase the projection magnification e in order to increase the measurement resolution.
When the irradiation angle α is increased, the projection magnification e becomes sensitive to the irradiation angle error Δα of the slit light, and adjustment becomes difficult.
For example, in order to make the projection magnification e 10 times, the camera is installed vertically and the irradiation angle α of the slit light is set to 84.29 °.
In this case, if the irradiation angle of the slit light has an adjustment error of only Δα = 0.1, the projection magnification error Δe becomes 0.2. Therefore, in the conventional measuring device 1, it is necessary to perform the adjustment with high accuracy and maintain the accuracy, and there is a problem that the adjustment time naturally takes a long time.

Another conventional example is disclosed in Japanese Unexamined Patent Application Publication No.
There is one disclosed in Japanese Patent No. 161935. This realizes high-precision measurement without adjustment by moving the slit light to be irradiated in parallel and causing the camera to recognize the locus of the slit light. However, in this method, since the slit light is moved to obtain the irradiation angle of the slit light, positioning reproducibility is required, and the field of view of the camera must be expanded when a minute measurement object is brought. Could not.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to reduce an adjustment error of an installation angle of a light source for irradiating a measuring object with light for measurement and to accurately measure the surface shape of the measuring object. An object of the present invention is to provide a three-dimensional measuring method and a measuring device thereof.

[0010] A three-dimensional measurement method according to the present invention comprises: an imaging device for imaging a measurement object arranged on an imaging field of view; and a light source for irradiating light to the imaging field of view on which the measurement object is arranged. In a three-dimensional measurement method comprising: determining a surface shape of a measurement target based on a change in a pattern of light applied to the measurement target disposed on an imaging field of view. The light source is rotated by a predetermined angle (for example, 90 °) around the light emission optical axis, and the installation angle of the light source is calculated based on a change in the dimension of a predetermined portion of the light pattern applied to the imaging visual field before and after the light is rotated. Then, the surface shape of the measurement object is obtained using the calculated light source installation angle.

Here, the imaging field of view is a surface within the field of view of the imaging device on which the object to be measured is placed. Light emitted from the light source is generally long in one direction (slit light), and is often emitted obliquely from above. The pattern shape in the cross section perpendicular to the optical axis may be different between the light used for measuring the measurement object and the light used for obtaining the installation angle of the light source.

The pattern of light emitted from the light source to the imaging field surface has a different projection magnification depending on the direction.
The projection magnification also differs depending on the installation angle of the light source (inclination from a vertical line on the imaging visual field plane). Therefore, the light emitted from the light source is rotated by a predetermined angle around the light emission optical axis, and the light source is rotated based on the change in the size of the predetermined portion of the light pattern applied to the imaging visual field before and after the light is rotated. The installation angle can be calculated. After installing the light source at the desired installation angle and then optically measuring the installation angle of the light source in this way, determine the installation angle of the light source first and adjust the angle of the light source to be equal to the installation angle. The error between the actual installation angle of the light source and the installation angle acquired as a value is extremely small as compared with the case of adjustment. As a result, when determining the surface shape of the measurement target based on the change in the pattern of the light irradiated on the measurement target, the error due to the error in the installation angle of the light source is reduced, and the measurement accuracy of the surface shape of the measurement target is reduced. Is improved.

The dimensions of the predetermined portion of the light pattern irradiated on the imaging visual field surface may be various embodiments. For example, the width of the predetermined light irradiation area of the light pattern irradiated on the imaging visual field surface may be used. And the width or length of a predetermined light non-irradiation area (shadow area). Also, at least 2
When the book light is emitted, the distance is, for example, the distance between predetermined light irradiation regions or the predetermined light non-irradiation region (shadow region) of the light pattern irradiated on the imaging visual field surface. .

[0014] A three-dimensional measuring apparatus according to the present invention comprises: an image pickup device for picking up an image of a measurement object arranged on an image pickup field; a light source for irradiating light to the image pickup field on which the object is set; Means for rotating the light emitted from the light source by a predetermined angle around the light emission optical axis, and before and after rotating the light by the rotating means, the dimensions of the predetermined portion of the pattern of the light applied to the imaging visual field surface Means for calculating the installation angle of the light source based on the change, a change in the pattern of light applied to the measurement object arranged on the imaging field of view, and the calculated installation angle of the light source based on the calculated installation angle of the light source Means for measuring the surface shape.

According to this three-dimensional measuring device, the above-described three-dimensional measuring method can be performed, the installation angle of the light source can be obtained with high accuracy, and the surface shape of the measurement object can be obtained with high accuracy. Further, the rotation of the light around the optical axis and the calculation of the installation angle of the light source based on the change in the dimension of the light pattern when the light is rotated can be automated, and the measurement time can be shortened.

The components of the present invention described above can be combined as much as possible.

[0017]

FIG. 4 is a perspective view showing the structure of a three-dimensional measuring apparatus 11 according to one embodiment of the present invention. The illuminating device 12 is installed at an angle of α to a perpendicular C standing on the imaging visual field surface 14, and light emitted from the illuminating device 12 becomes slit light 15 extending in one direction. I have. The extending direction of the slit light 15 emitted from the illumination device 12 is as shown in FIG.
The light is rotated around the output optical axis by an optical rotation mechanism 16. In order to rotate the direction in which the slit light 15 extends, the illumination device 12 itself may be rotated by the light rotating mechanism 16 or the slit 17 for emitting the slit light 15 may be rotated. Also,
The installation angle α of the illumination device 12 (or the light emission angle of the illumination device 12) can be adjusted by an angle adjustment mechanism (not shown). The structures of the light rotating mechanism 16 and the angle adjusting mechanism are not particularly limited to specific ones, and therefore details are omitted. For example, the illumination device 12 is rotated around the optical axis by a servomotor or the like. It is possible to use an optical rotation mechanism 16, an angle adjustment mechanism that rotates the optical rotation mechanism 16 with a servomotor, a cam mechanism, or the like about a slit light irradiation point on the imaging visual field surface 14. The illumination controller 18 controls the illumination system, and performs on / off control of the illumination device 12, control of the emission angle α of the slit light 15, control of the rotation angle of the slit light 15 around the optical axis, and the like. Can be. Note that the width of the slit light 15 emitted from the illumination device 12 is large enough to be measured accurately, and it is desirable that the slit light 15 is a collimated light.

An imaging device 13 such as a CCD camera is installed on the opposite side of the illumination device 12 at an angle of β with respect to a perpendicular C standing on an imaging visual field surface 14. The installation angle β of the imaging device 13 can be adjusted by an angle adjustment mechanism (not shown). The structure of the angle adjusting mechanism is not particularly limited to a specific one, but may be, for example, a structure in which the position of the imaging device 13 is rotated by a servomotor, a cam mechanism, or the like. The image captured by the image capturing device 13 is input to an image processing device 20 configured by a personal computer and predetermined software.

FIG. 6 is a flowchart showing a procedure for measuring the three-dimensional shape of the measurement object using the three-dimensional measuring device 11. Hereinafter, a method of using the three-dimensional measuring apparatus 11 (measuring method) will be described with reference to this flowchart. First, the illumination device 12 and the imaging device 13 are installed at an appropriate angle.
Here, the installation angle α of the illuminating device 12 is set to an angle substantially equal to an angle at which a desired projection magnification is obtained. In particular, when a large projection magnification is desired, the angle is set close to 90 °. In a state in which the measurement object is not placed on the imaging visual field surface 14 (or a plate having a uniform surface and roughness and a uniform thickness may be placed), as shown in FIG. The illuminating device 12 is rotated such that the vertical direction is parallel to a plane including the perpendicular C drawn on the imaging visual field surface 14 and the emission optical axis of the slit light 15, and the slit light 15 is transmitted from the illuminating device 12 to the imaging visual field surface 14. Irradiation (vertical line irradiation) is performed (step S1). Then, the width WA of the slit light 15 applied to the imaging visual field surface 14 is measured (step S2).

Next, as shown in FIG.
The illumination device 12 is rotated 90 ° by the optical rotation mechanism 16 so that the length direction of the illumination device 12 is perpendicular to a plane including the perpendicular C formed on the imaging visual field surface 14 and the emission optical axis of the slit light 15. The slit light 15 is irradiated (horizontal line irradiation) to the imaging visual field surface 14 (step S3). Then, the width WB of the slit light 15 applied to the imaging visual field surface 14 is measured (step S4).

From the measured widths WA and WB of the slit light 15, an installation angle α of the illumination device 12 (irradiation angle of the slit light 15) α is obtained by calculation (step S 5). FIG.
This shows a state in which the slit light 15 is irradiated on the horizontal line in the step S3. The irradiation slit light 1 measured by irradiating the slit light 15 with the vertical line in the step S1
5 is equal to the width of the irradiation slit light 15 emitted from the illumination device 12, the relationship between the installation angle α of the illumination device 12 and the widths WA and WB of the irradiation slit light 15 is shown in FIG.
It is represented as Therefore, the installation angle α of the lighting device 12
Is expressed as cos α = WA / WB α = arccos (WA / WB).

By calculating the installation angle α in this way, the installation angle of the illumination device 12 (the irradiation slit light 15
Can be obtained with high accuracy. That is, when the position of the illumination device 12 is adjusted so that the illumination device 12 has a predetermined installation angle α, an adjustment error cannot be avoided.
Is set at a substantially desired angle, and the installation angle α is obtained optically as described above, whereby the error can be extremely reduced. Further, by obtaining α with high accuracy, the projection magnification e can be calculated with high accuracy.

The accuracy of the installation angle α of the illuminating device 12 depends on the accuracy of the measurement of the ratio WA / WB of the width of the irradiation slit light 15. The width ratio WA / WB may be measured with high accuracy based on an image captured by the imaging device 13, or the widths WA and WB may be directly measured using a gauge or the like.

After the installation angle α of the illuminating device 12 is determined in this way, the measurement object 21 is set on the imaging visual field surface 14 (step S6). FIG. 10 shows an example of the measurement target 21, and shows a surface mount component 23 mounted on a circuit board 22. The measurement object 21 is irradiated with the slit light 15 in a horizontal line, and an image thereof is captured from the imaging device 13 (step S7).
The information on the cross-sectional shape or the three-dimensional height direction at the irradiation location can be obtained (step S8). For example,
FIG. 11 shows an image when the measurement object 21 as shown in FIG. 10 is irradiated with the slit light 15. In this image, the slit light 15 irradiated on the circuit board 22 is shown.
The interval between the slit light 15 illuminated on the surface mount component 23 and the upper end in the drawing is t1, and the slit light 15 illuminated on the circuit board 22 and the surface mount component 23 are illuminated. Assuming that the interval between the slit light 15 and the upper and lower ends in the drawing is t2, the surface mount component 2
3 is calculated as follows: h1 = t1 / e = t1 · cos α / sin (α + β), and the height of the upper and lower ends of the surface mount component 23 in the figure is h2 = t2 / e = t2 · cos α / sin (α + β) Therefore, whether or not the surface mount component 23 is mounted in parallel with the circuit board 22 can be inspected based on whether or not the values of the heights h1 and h2 are equal. Alternatively, whether or not the surface mount component 23 has risen from the circuit board 22 can be inspected based on whether or not the heights h1 and h2 are equal to a predetermined height.

Also, depending on the object to be measured, the three-dimensional shape of the object to be measured 21 is measured by measuring the height of the object to be measured 21 while moving the three-dimensional measuring device 11 and the object to be measured 21. Can also.

According to the measuring method of the present invention, the irradiation angle α of the slit light 15 which greatly affects the projection magnification of an image can be obtained with high accuracy. Can be measured. On the other hand, the installation angle β of the imaging device 13 is the installation angle α of the lighting device 12.
Since it does not greatly affect the projection magnification, a value measured using a method similar to the conventional method or using a gauge for angle measurement or the like is used.

As a modification of this embodiment, in the step of obtaining the irradiation angle α in steps S1 to S4,
Step S7 to Step S7
In the three-dimensional measurement process of 8, the width of the slit light 15 may be narrowed.

Also, for example, the image pickup device 13 is connected to the image pickup field plane 1.
4 is set perpendicularly to 4, and measured while irradiating the slit light 15 from the right with the illumination device 12, then measuring while irradiating the slit light 15 from the left with the illumination device 12,
If the three-dimensional height and the like of the measurement object 21 are measured based on data from both sides, the measurement accuracy can be further improved.

(Second Embodiment) FIGS. 12A and 12B
FIG. 13 is a perspective view showing a configuration of a three-dimensional measuring apparatus according to another embodiment of the present invention. In the illumination device 12 in this embodiment, two parallel slit lights 15 are emitted. After the illuminating device 12 and the imaging device 13 are set at appropriate angles, the length direction of the slit light 15 is changed to the imaging visual field surface 14 as shown in FIGS.
The illuminating device 12 is rotated so as to be parallel to a plane including a perpendicular line formed on the surface and the emission optical axis of the slit light 15, and the two parallel slit lights 15 are transmitted from the illuminating device 12 to the imaging visual field surface 14.
Is irradiated. Then, 2
The distance DA between the slit lights 15 is measured.

Next, as shown in FIG.
The illumination device 12 is rotated by 90 ° by the optical rotation mechanism 16 so that the length direction of 5 is perpendicular to a plane including the perpendicular to the imaging visual field surface 14 and the emission optical axis of the slit light 15. Two slit lights 15 on imaging field of view 14
Is irradiated. Then, a distance DB between the two slit lights 15 irradiated on the imaging visual field surface 14 is measured.

Thus, the distance DA between the slit lights 15
If the DB is measured, the installation angle α of the illumination device 12 (the irradiation angle of the slit light 15) α can be calculated by α = arccos (DA / DB) in the same manner as in the first embodiment. The value of the installation angle α can be determined with high accuracy. Therefore, by obtaining the three-dimensional height and the like of the measurement target using this value as the irradiation angle α of the slit light 15, it is possible to accurately measure the three-dimensional height and the like of the measurement target with a small error. .

[0032]

According to the present invention, the light emitted from the light source is rotated around the optical axis before irradiating the object to be measured with light to perform three-dimensional measurement. Since the light irradiation angle is measured by calculating the change in the dimensions of the predetermined part of the pattern, it is necessary to obtain the light irradiation angle with high accuracy after the light source installation even if the adjustment of the light source installation angle is slightly shifted. And light source adjustment errors can be reduced. Therefore,
The three-dimensional measurement accuracy of the measurement object can be improved. In particular, it is effective when the light irradiation angle is set close to parallel to the imaging field of view in order to increase the measurement resolution.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a light cutting method using slit light.

FIG. 2 is a diagram illustrating a change in a projection magnification e when a camera is installed vertically and an angle α of a lighting device is changed.

FIG. 3 shows the irradiation angle α of the slit light and the installation angle β of the camera.
FIG. 6 is a diagram showing a relationship between the projection magnification e.

FIG. 4 is a perspective view showing a structure of a three-dimensional measuring apparatus according to one embodiment of the present invention.

FIG. 5 is a perspective view showing an illumination device and a light rotating mechanism in the three-dimensional measuring device according to the first embodiment.

FIG. 6 is a flowchart showing a procedure for measuring a three-dimensional shape of a measurement object using the three-dimensional measuring device of FIG.

FIG. 7 is a perspective view illustrating a state in which slit light is emitted from an illumination device to a vertical line.

FIG. 8 is a perspective view showing a state in which a slit light is emitted from a lighting device to a horizontal line.

FIG. 9 is a diagram illustrating a relationship between the width of each slit light and the light irradiation angle when the slit light is irradiated on a vertical line and when the slit light is irradiated on a horizontal line.

FIG. 10 is a plan view illustrating an example of a measurement target.

11 is a diagram illustrating an image when a measurement target illustrated in FIG. 10 is irradiated with slit light.

FIG. 12A is a perspective view showing a three-dimensional measuring apparatus according to another embodiment of the present invention, and FIG. 12B is a partially enlarged view of FIG. The state of irradiation is shown.

FIG. 13 is a perspective view showing a state in which a horizontal line is irradiated with slit light from an illumination device in the embodiment.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 12 Illumination device 13 Imaging device 14 Image field of view 15 Slit light 16 Optical rotation mechanism 17 Slit 21 Measurement object

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA04 AA53 DD03 FF01 FF02 FF09 HH05 HH12 HH18 JJ03 JJ08 JJ26

Claims (4)

[Claims] An imaging device configured to capture an image of an object to be measured disposed on an imaging field of view; and a light source configured to irradiate light toward the imaging field of view on which the object to be measured is disposed. A three-dimensional measurement method for determining a surface shape of a measurement target based on a change in a pattern of light applied to the measurement target, wherein light emitted from the light source is determined around a light emission optical axis thereof. Rotate the angle and calculate the installation angle of the light source based on the change in the dimensions of the predetermined part of the pattern of the light applied to the imaging field of view before and after rotating the light, and use the calculated installation angle of the light source to measure A three-dimensional measurement method characterized by determining a surface shape of an object. 2. An installation angle of the light source is calculated by measuring a change in a width of a pattern of light applied to an imaging field of view before and after rotating the light source around a light emission optical axis by a predetermined angle. The three-dimensional measurement method according to claim 1, wherein 3. The method according to claim 1, wherein at least two lights are emitted from the light source, and a distance between patterns of the respective lights applied to the imaging visual field surface is measured before and after the light source is rotated by a predetermined angle around the light emission optical axis. The three-dimensional measurement method according to claim 1, wherein an installation angle of the light source is calculated by the following. 4. An image pickup apparatus for picking up an image of an object to be measured arranged on an imaging field of view, a light source for irradiating light toward an image pickup field of view on which the object to be measured is arranged, and a light emitted from the light source. Means for rotating the light source by a predetermined angle around the light emitting optical axis; and an installation angle of the light source based on a change in the size of a predetermined portion of the pattern of the light applied to the imaging visual field before and after rotating the light by the rotating means. And means for measuring the surface shape of the measurement target based on the change in the pattern of light applied to the measurement target disposed on the imaging visual field plane and the calculated installation angle of the light source. Equipped three-dimensional measuring device.