JPH06103166B2 - Actual size measurement method in visual device - Google Patents

Description

The present invention relates to a method for calculating actual dimensions in a visual inspection device that monitors a monitored object on a subject.

[Conventional technology]

Conventionally, as shown in FIG. 6, in a visual inspection device using a TV camera (1), the length of a ruler or the like can be used to obtain the actual size of the monitored object (14) such as rust and scratches on the subject (3). A known object (15) is imaged at the same time as the monitored object (14), and an image of the object of known length (17) and an image of the monitored object (1
6) or by measuring the distance from the TV camera 1 to the monitored object 3 with an ultrasonic range finder, etc. if the focal length of the TV camera lens is known. The field of view on the monitor screen is calculated from the lens viewing angle and the measured distance, so the actual size of the monitor object is converted and calculated according to the ratio of the image of the monitor object on the monitor screen. ing.

[Problems to be Solved by the Invention]

 The above conventional method has the following problems.

(1) Since it is affected by the distortion of the optical system (distortion of the image pickup lens, the image pickup tube, and the cathode ray tube), the conversion error becomes large especially in the peripheral portion of the screen.

(2) If the subject is tilted with respect to the TV camera, the tilt angle will be reduced on the monitor screen.
I do not know the original dimensions.

(3) In the method based on the distance measurement, the dimension conversion accuracy depends on the distance measurement accuracy and the viewing angle accuracy of the lens, but when using a zoom lens for the lens of the TV camera, if the zoom ratio is unknown, Even if the conversion is impossible and the zoom ratio can be measured, the accuracy is not good and the dimensional conversion accuracy is reduced.

(4) With the method based on distance measurement, if the distance between the TV camera and the subject and the zoom ratio of the lens change momentarily (this is often the case with mobile inspection devices), the VT after inspection
When the size is converted from the R image, the size data cannot be converted because there is no data on the distance and data on the zoom ratio on the image.

(5) If an object of known length cannot be imaged (this is often the case with actual inspection equipment), the actual size cannot be converted.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the present invention projects a beam with a projector having an optical axis that is parallel to the optical axis of the visual device and has a predetermined interval, and the projection point and the subject are simultaneously displayed by the visual device. Along with capturing an image, on a plane orthogonal to the optical axis of the visual device, an intersection point with the optical axis is drawn as an origin, and a coordinate diagram previously imaged by the visual device having the same or the same characteristics as the visual device To propose an actual size measuring method in a visual device in which an image is superimposed on the image of the light projecting point and the object and the size of the object is obtained from the mutual relationship between the image of the light projecting point and the image of the object in the image of the coordinate diagram. Is.

[Action]

The projection point image and the image of the monitor target imaged by the above means change as the distance between the television camera and the subject or the zoom ratio of the lens changes, but the projection beam is emitted from the optical axis of the optical system of the camera. The actual distance and size are constant (known). Therefore, by reading these on the scale of the coordinate diagram, the conversion rate is obtained, and by multiplying by the conversion rate of the following formula (1) or (2), the actual dimensions corrected for optical distortion are converted and calculated. .

R / N _R (when the projected beam is not parallel) …… (1) D / N _D (when the projected beam is parallel) …… (2) where R: Distance between the optical axis of the optical system and the projector D: diameter N R parallel beam _projector: distance N D from the coordinate origin of the projected light spot _image: diameter of the projected light spot image also if the monitored object is inclined with respect to the optical axis, projection minor diameter of the light spot image (N _S), the major axis (N _l), the angle of the minor axis (alpha), and the distance from the coordinate origin of the projected light spot image (N
_R ) is measured and the conversion rate of the equation (1) or the equation (3) is obtained in the same manner as described above.

R / N _S (when the projected beams are parallel) (3) On the other hand, the image of the monitored object changes according to the tilt angle θ of the monitored object. Since the rate of change varies depending on the direction on the display screen, the actual dimension is converted and calculated by further multiplying the direction correction coefficient Kψ obtained in advance by the relational expression (4).

Kψ = F _θψ (N ₁ / N _S , α) (4) In this way, not only the distortion correction by the optical system but also the monitor target that changes the zoom ratio or moves relatively,
It becomes possible to monitor effectively.

〔Example〕

An embodiment of the present invention will be described with reference to FIGS.

In FIG. 1, the light projector 2 is always arranged such that its optical axis m is away from the optical axis 1 of the television camera 1 by a distance R to form a visual device. A plane 3 orthogonal to the optical axis 1 is arranged at a position separated by a certain distance. On this plane 3, a grid line of orthogonal coordinates having an origin 5 at the intersection with the optical axis 1 is drawn, a part of which is shown in FIG. 2 (a).

(1) This Cartesian coordinate diagram is the TV camera 1 for this monitor
Alternatively, when the image is picked up by a television camera having the same characteristic as that, a coordinate diagram as shown in an exaggerated part in FIG. 2 (b) is obtained on the display screen 4 (FIG. 1 (b)). Image distortion is distortion of the optical system of the TV camera 1 (imaging lens, image pickup tube,
The distortion of the cathode ray tube is large). As shown in Fig. 3 (a), this coordinate image is displayed on a transparent screen 12
After transferring so as not to disappear on the display screen 4,
Set it so that it matches the same coordinate diagram. This transferred coordinate diagram serves as a reference scale for the subsequent measurement.

(2) In FIG. 1, it is assumed that the plane 3 is a monitor subject, and a part thereof is a monitor target 14. When a beam having a divergence angle β smaller than that of the projector 2 or a divergence angle β = 0 and having a diameter D is projected and imaged by the television camera 1, an image as indicated by reference numeral 6 ′ in FIG. It is placed on the screen 4, which is a transparent screen 12 as shown in Fig. 3 (b).
Seen through. Hereinafter, this image is abbreviated as an image on the display screen 4.

(3) X _S is obtained by reading a scale i.e. the reference scale graduation lateral dimensions of the coordinate diagram of the image 14 'of FIG. 1 and 3 the display screen 4 on the monitored object at 14. Further, N _R will be obtained by reading the horizontal position from the origin 5 projecting point image 6 '. Therefore, the actual dimension X corresponding to the image X _S of the monitored object is
Since the distance R is a known actual dimension, the conversion rate can be calculated by the equation (1). Therefore, the actual size is given by equation (5).

X = X _S · R / N _R (5) Further, when the parallel beam projector 2 having the beam diameter D is used, if the diameter of the projected point image is N _{D in the same} manner as above, It is given by equation (6).

X = X _S · D / N _D (6) (4) Further, for example, as shown in FIG. 4 (a), the subject plane 3 is inclined at an inclination angle θ with respect to the optical axis 1 of the television camera 1. Image, the image obtained on the display screen 4 is
As shown in. That is, the monitored object 14a is 1
The projection point 6a is imaged at 4'a and the projection point image 6'a is projected at 6'a.
Becomes oval. Therefore, the angle α (in the example shown in the figure) formed by the short shape N _S of the projection point image 6 ′ a and the long diameter N _l and the X axis in the short diameter direction.
90 °) can be obtained.

Furthermore, the dimensions of the image 14a 'of the monitoring target object, for example, since the transverse dimension X _S is determined, the actual size is given in the previous (3) similar to the term (1) the following equation (7) from the equation.

X ′ = X _S · R / N _R (7) Further, when the parallel beam projector 2 is used, it is given by the following equation (8) from the equation (2).

X ′ = X _S · D / N _S (8) The actual size obtained above is the size X (in this case, the size X) of the monitored object 14a according to the direction angle ψ (with respect to the X axis) of the measured size.
ψ = 0 °) shorter or expanded. Therefore, the inclination angle θ is changed in advance, the above N ₁ / N _S and α are read,
If the correction coefficient in the direction of the angle ψ from the X axis of the monitor image 14′a, that is, Kψ in the equation (4) is obtained, the corrected actual dimension X in the ψ direction can be easily given by the equation (9).

X = X ′ · Kψ = X ′ · F _θψ (N ₁ / N _S , α) (9) In this way, when the distance between the subject 3 and the television camera 1 changes momentarily, or the lens Even when the zoom ratio changes, the distance R between the optical axis m of the projector 2 and the optical axis 1 of the television camera or the beam parallel type of the projector 2 has a known and constant beam diameter. The actual size of the monitored object can be easily obtained without being affected by the distortion of the optical system.

The above method is premised on that the projected beam can be clearly judged on the display screen 4 (especially important in the method of calculating the conversion by using the outer diameter D of the beam as a standard). FIG. 5 (a) shows, as an example of the structure of the projector (2), a method of clarifying the edge of the light beam by the aperture (9). It consists of a light source (7) such as a laser oscillator, lens systems (8) and (8 '), and an aperture (9) arranged between the lenses. The light is expanded to a predetermined diameter and becomes parallel light. The aperture (9) is provided so that the intensity distribution of the emitted light improves the rising of the intensity at the edge of the pattern as shown by the solid line in FIG.
The broken line in Figure (b) shows the intensity distribution without the aperture (9)). As a result, the measurement of the size of the projected point image on the display screen 4 can be facilitated and made highly accurate.

It should be noted that it is clear that the same can be achieved by using an optical fiber as the light source (7) and guiding laser light.
In this case, the tip of the projector (2) can be made smaller and lighter.

〔The invention's effect〕

Even if there is no object of known size on the subject, the distance between the subject and the TV camera and the zoom ratio of the imaging lens are unknown, and the subject is tilted, the actual size of the monitor target on the subject can be calculated. It can be implemented without being affected by the distortion of the optical system.

Also, since the image of the beam of the projector is captured together with the image of the monitored object on the inspected image, recording the image in the VTR has the advantage that the actual dimensions can be converted and calculated even after the inspection is completed.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is an explanatory view of a method for correcting optical system distortion, FIG. 3 is an explanatory view of a dimension reading method on a display screen, and FIG. 5 is an explanatory view of a case where the subject is tilted), FIG. 5 is a structural example of the projector of FIG. 1, and FIG. 6 is a structural diagram of an embodiment of a conventional method. In the figure, 1 ... TV camera, 2 ... Projector, 3 ... Plane, 4 ... Display screen, 5 ... Origin, 6a ... Projection point, 6 ', 6'a ... Projection point image, 7 ... Light source, 8, 8 '... Lens system, 9 ... Aperture, 12 ... Transparent screen 14, 14a ... Monitor target 14', 14'a ... Monitor target image 15 ... Known Object, 15 '... Image of known object l ... Optical axis of TV camera, m ... Optical axis of projector

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koichi Wada 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries, Ltd. Hiroshima Research Laboratory (72) Inventor Yukio Manabe 4-chome, Kannon Shinmachi, Nishi-ku, Hiroshima Prefecture 6-22 No. 22 Hiroshima Institute of Mitsubishi Heavy Industries, Ltd. (72) Makoto Miyaji 4-6-22 Kannon Shinmachi, Nishi-ku, Hiroshima City, Hiroshima Prefecture Mitsubishi Heavy Industries Ltd. Hiroshima Works

Claims (1)

[Claims] 1. A beam is projected by a projector having an optical axis parallel to the optical axis of the visual device and having a predetermined interval, and the projected point and an object are simultaneously imaged by the visual device and the visual On the plane orthogonal to the optical axis of the device, an image of a coordinate diagram drawn with a point of intersection with the optical axis as an origin and having the same or the same characteristics as the visual device in advance is used as the projection point. And an actual size measuring method in a visual device, wherein the size of the subject is obtained by superimposing on the image of the subject and determining the size of the subject from the mutual relationship between the light projection point and the image of the subject in the image of the coordinate diagram.