JPH01213507A - Three-dimensional object measuring instrument - Google Patents

Abstract

PURPOSE:To measure the shape of an object from the distance information of the object by one time of scanning by projecting slit light on the same picture element of a reference plane from right and left sides and scanning the projected location synchronously to TV signals, and then, detecting the position of a base line on the object on a TV camera side from the reference plane. CONSTITUTION:Projectors 3a and 3b are provided on both sides of a TV camera 1 and slit light 7a and 7b is projected on the same position on a reference plane S at a fixed distance from the camera 1. Then the projected position is scanned at every picture element as X1, X2... synchronously to TV signals. A measuring plane is set on the TV camera 1 side of the reference plane S by a prescribed interval and light is projected from the projectors 3a and 3b on an object placed on the measuring plane and positions of bright lines on the object to be measured are detected. The distance to the object is calculated from the positions of the bright lines, projecting angles, and positional relations between the TV camera 1 and projectors 3a and 3b. Thus the distance information of the object can be obtained by one time of scanning.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is a three-dimensional object in which a three-dimensional object is irradiated with a slit light, and the bright line generated on the object surface is imaged with a television camera to measure the distance to the object surface. The present invention relates to an object measuring device, and particularly to a three-dimensional object measuring device that uses two projectors and can perform measurement in one scan.

[Conventional technology]

Generally, three-dimensional recognition ability is required for visual functions used in factory inspection processes and assembly robots, but the reality is that the conventional method of object recognition based on brightness image information is not sufficient. It is. Therefore,
Many attempts have been made to facilitate object recognition and extraction by obtaining not only luminance image information but also distance information to the object.

FIG. 12(A) is a diagram showing the configuration of such a conventional three-dimensional object measuring device, and FIG. 12(B) is a diagram showing bright lines. On the measurement surface, 7 is a slit light.

In the figure, it is assumed that the television camera 1 and the projector 3 are arranged at predetermined positions with an interval l, and the projector 3 projects a slit light 7 across the viewing range PL-P2 by changing the angle of the measurement plane by a unit angle. . The television camera l is capable of capturing an image of a viewing range, and captures an image of a bright line formed by a slit light and displays the image on a monitor (not shown).

In such a configuration, a normal brightness image is first obtained by scanning the object plane with a television camera.

Next, when the projector 3 is scanned by a predetermined number of steps,
A bright line image as shown in FIG. 12(b) is obtained. Suppose now that a bright line at a position Px on the measurement surface 5 is observed. Since the angle of the projector 3 in a unit step is known, the angle α of the projector 3 can be found from this and the number of steps, and the incident angle β of the bright line to the television camera can also be determined from the position of the observed bright line, so Using the distance β between the television cameras, the distance from the television camera to the measurement position can be calculated using trigonometry.

In this way, it becomes possible to obtain distance information as well as brightness image information.

[Problem that the invention seeks to solve]

However, with the conventional three-dimensional object measuring device shown in Fig. 12, even though a brightness image can be obtained instantly, in the case of an object with a shape as shown in Fig. 13 (a), a shadow part appears. Therefore, first, a slit light is projected onto the TV camera from one side for scanning, then a slit light is projected onto the TV camera from the opposite side and scanned in the same manner, and each bright line is imaged. A complete measurement cannot be made without scanning twice.
It takes 1/1 screen scanning time to image one bright line.
It takes 30 seconds, so if you scan, for example, 512 pixels in the horizontal direction using slit light, it will take about 17 seconds (=512 x 1/30) for just one scan, and 34 seconds for two scans. There was a problem. In addition, in FIGS. 13(b), (c), and (d), the black parts indicate the bright lines of the areas hit by the laser beam, and FIG. 13(b) is an example of a projected image, and FIG. C) is an enlarged view of part A of the projected image and shows an example of a change in bright line width. Also the first
Figure 3 (d) is an enlarged view of part B of the projected image, with 3 bright lines.
An example is shown where it is divided into books.

The present invention is intended to solve the above-mentioned problems, and aims to provide a three-dimensional object measuring device that can measure the shape of an object in a short time by eliminating shape parts by scanning at -degrees.

(Means for Solving the Problems) For this purpose, the three-dimensional object measuring device of the present invention includes a television camera, which is placed on both sides of the television camera, and scans the television camera simultaneously from the left and right toward the same position on a reference plane. two projectors that project slit light perpendicular to the line; and a projection angle control means that changes the projection angle of the projectors so as to scan the projection position pixel by pixel on a reference plane in synchronization with a television signal. , distance calculation means for calculating the distance to the measurement object from the bright line imaging position, projection angle, and positions of the television camera and the projector using the slit light from the measurement object installed on the side of the television camera from the reference plane. It is characterized by

[Effect]

The three-dimensional object measuring device of the present invention uses two projectors placed on both sides of a television camera to simultaneously project slit light perpendicular to the scanning line of the television camera toward the same position on a reference plane to generate a television signal. Synchronized scanning is performed pixel by pixel, and the position of the bright line drawn by the slit light on the measurement object placed closer to the TV camera than the reference plane is detected for each scanning line, and the detected bright line position, projection angle, TV camera, By calculating the distance from the position of the projector to the measurement object, the shape of the measurement object can be determined with one scanning.

〔Example〕

Examples will be described below based on the drawings.

FIG. 1 is a diagram showing an embodiment of the three-dimensional object measuring device according to the present invention, FIG. 2 is a diagram showing a scanning method, and FIG. 3 is a diagram showing an example of measuring a hemispherical measurement object, and l is a television Camera, 3a, 3b are left and right floodlights, S is reference plane, 5 is measurement plane, ? a, 7b are slit lights, 1113 is a step motor, 15 is a preprocessing section, 17 is a position detection section, 19 is a distance calculation section, 21 is a distance data recording section, 23 is a distance image memory,
25 is a table correction unit, 27.29 is a control table, 3
Reference numeral 1 denotes a left side projection angle control section, and numeral 33 denotes a right side projection angle control section.

In the figure, on both sides of the TV camera l are floodlights 3a and 3.
b is arranged, and the slit lights 7a and 7b are connected to the television camera l.
Light is projected toward the same position on the reference plane S at a certain distance d from the center, and scanning is performed pixel by pixel as shown in FIG. The projection angles of the projectors 3a and 3b are controlled by controlling the step motors 11 and 13 by the left projection angle control section 31 and the right projection angle control section 33. In this case, the rotation of the step motor is slowed down and transmitted to the floodlight using gears, etc., so mechanical errors such as gear pinch error, bearing diameter error, or bank lash may be applied to the step motor. Since the relationship between the number of pulses and the rotation angle of the projector is not completely linear, the relationship between the number of pulses and the rotation angle is actually measured and determined in advance, and the number of pulses corresponding to each pixel on the reference plane is determined from the control table 27.2.
9, and by reading out the values in the control table and controlling the projection angle, scanning is performed for each pixel. The control table is created in advance in this way, but in order to further improve the accuracy, the reference plane is scanned pixel by pixel prior to measurement, and the result of detecting the position of the bright line is used to determine the actual light emitted. The number of pulses is converted from the deviation between the current position and the original position, and the table correction section 25 corrects the contents of the control tables 27 and 29.

The measurement surface 5 is placed in front of the reference surface S by a predetermined distance, as shown in FIG. By doing this, the bright line position on the measurement surface is always separated to the left and right with respect to the target pixel on the reference surface.
The bright line on the left side is from the floodlight 3a, and the bright line on the right side is from the floodlight 3a.
b. Therefore, by measuring each bright line, it is possible to perform measurement without the bulge by one scanning using the above-mentioned triangulation method.

For example, if a hemispherical object is placed on the measurement surface as shown in Figure 3 (a), it will be projected by a projector.

A television image without light, that is, a brightness image, is obtained as shown in FIG. 3 (b). A and B on the reference plane S.

Assuming that the bright line at position C is as shown in Fig. 3 (c), when the slit light is projected onto the reference plane A position,
The left slit light is projected on a flat surface, so the bright line is straight, and the right slit light is projected on a spherical surface, so the bright line is arc shaped (Figure 3 (d)). When the light is emitted from the position B on the surface, the emission line becomes an arc because both the left slit light and the right slit light illuminate the spherical surface (Fig. 3 (e)), and the position C on the reference surface is When the light is projected, the bright line similarly becomes an arc, but since the right slit light projects the edge of the spherical surface, it becomes a collapsed arc (see Figure 3).The broken line is the reference plane. shows the emission line position at .

The brightness image and bright line signal obtained in this way are transmitted to the TV camera 1.
The data is taken into the preprocessing section 15 from there. The preprocessing unit 15 includes a frame memory for brightness images, a circuit for binarizing and extracting bright lines, and i! of bright lines in a bright environment. To make it easier to understand
It has a circuit that takes the difference between the brightness image and the bright line image, cancels out the background brightness, and extracts the bright lines.

Based on the data from the preprocessing section, the position detection section 17 detects the positions of the left and right bright lines using the left and right slit lights, and based on this, the distance calculation section 19 detects the bright line position of the light emission, the positions of the television camera and the light projector, and the position of the light emission line. Distance calculation is performed using the trigonometric method using the corners, and the calculated distance data is recorded in the distance data recording section 21, and is stored in the distance image memory section 23 as an address on the image whose position has been detected. will be written to.

By the way, if the beam of the slit light has a width, the beams will not be separated in the area where the beams of the left and right projectors overlap, and as a result, the imaged bright lines will not be separated into the left and right sides, resulting in a decrease in measurement accuracy.

Figure 4 shows this situation, and shows the case where the beam width is 5 pixels, and since the left and right beams overlap in the area R from the reference plane, the measurement plane should be in front of R. There is a need to. The size of the overlap area is the beam width,
Since it changes depending on the angle of incidence on the reference plane, it is necessary to set the measurement plane by taking these into consideration. Note that when the pixel at address X is illuminated with the left beam and right beam as shown in the figure, the distance conversion value rl (
(for left side light emission), distance conversion value r2 (for right side light emission)
is the distance resolution, and it can be seen that these depend on the angle of incidence of the beam.

Figure 5 is a diagram for explaining distance resolution, and the figure (a)
1 is an overall configuration diagram, (b) is an enlarged view of the center P of the visual field, and (c) is a diagram showing the relationship between the distance resolution and the distance between the television camera and the projector.

As shown in Figure 5 (a), the incident angle of the laser beam is set to θ, θ.
', the distance between TV camera 1 and floodlight 3! , when the measurement distance is d, the field of view of the television camera is V, and the field of view of one pixel at the center of the field of view is ΔV, as shown in Figure 5 (b),
Distance resolution is defined as resolution Δd relative to ΔV. Since Δd depends on the incident angle θ', and θ′ changes depending on l, the relationship between Δd and l is shown in FIG. 5(c). As can be seen from FIG. 5(c), the distance resolution can be increased by increasing the distance between the television camera and the projector.

FIG. 6 is a diagram showing an example of the specific configuration of the three-dimensional measuring device of the present invention, in which 41 is a He-Ne laser, 43 is a half mirror 145, 47 is a movable mirror, and D and E are slit lights. This is the bright line.

In this embodiment, the laser beam from the )ie-Ne laser 41 is divided into two by a half mirror 43, and each is divided into two by a movable mirror 4.
5.47 generates left and right slit lights. The movable mirror consists of a mirror that vibrates in the Y direction and is driven in the X direction by a step motor as described above.By vibrating in the Y direction, a slit light is generated, and by driving in the X direction, scanning is performed. 0 figure glue,
E shows the bright line of the slit light irradiated onto the object by the left and right projectors.

Note that the number of laser light sources is not one as in this embodiment, but may be provided in each of the left and right projectors.

Figure 7 is a diagram showing an example of measuring a three-dimensional object according to the present invention.
When the coins are arranged as shown in Fig. 2, it is observed as shown in the figure (b) using only the brightness image, and it is actually impossible to determine the relative positional relationship of each coin, but according to the present invention, these distances can be The signal is obtained as shown in the same figure (c), and the bright line due to the edge of each coin is obtained as shown in the same figure (d), and even if the coins have the same reflectance, their relative positions can be clearly distinguished. It becomes possible to do so.

By the way, since the slit light has a predetermined beam width, depending on the shape of the object to be measured, for example, the beam width shown in FIG.
The beam is split into two as shown in
If the image is captured as two bright lines as shown in Figure 8 (B), the brightness distribution will be as shown in Figure 8 (C), and by setting a predetermined binarization level to this, The center Pc of the beam, which will result in a binarized image as shown in Figure 8(d), can be found as (A+8)/2, where the widths of each binarized image are A and B. become.

If the object has a more complicated shape, it will be further divided, and the center position of the bright line will not be known, resulting in a large distance measurement error.The method for determining the beam center position in this case will be explained below.

FIG. 9 is a diagram showing the configuration for determining the beam center position;
FIG. 10 is a diagram showing a timing chart, and FIG. 11 is an explanatory diagram for determining the center position.

In the figure, 101 is a binarization circuit, 103 is an AND circuit, 10
5 is a width counter, 107 is a 1/2 circuit, 109 is a delay circuit, 111 is a selector, 113 is a RAM, 115 is a delay circuit, 117 is an X address counter, 119 is a comparison circuit, 121 is a binary counter, 123 is an X It is a counter.

In the figure, the image clock of the TV camera is approximately 39ns.
It has a period (approximately 12.5 MHz), is counted by the X address counter 117, and is reset every horizontal scan (HD). Therefore, the contents of the X address counter 117 represent the X address in each scan line. Since the measurement range must cover the entire TV screen, the effective measurement area will be shorter than one horizontal scan (Fig. 10 (c)).
The signal is inputted to , the frequency is divided by 1/2, and counted by an X counter 123 . Therefore, since the X counter 123 is counted and amplified every odd field or even field, that is, every time one double-sided update is performed, the number of scanning steps of the slit light, that is, the current projection position on the reference plane shown by the broken line in FIG. represents. Therefore, depending on the size of the X address counter and the X counter, it can be determined whether the scanning position is to the left or right of the light emitting pixel position on the reference plane, so compare the contents of the X address counter and the X counter when the bright line is detected, and It can be determined that the address counter is X counter → left bright line.

19 line, rOJ, can be detected as a bright line by the right side projector. Although the output of the X address counter is shown as having a 9-bit configuration, this may be changed as appropriate depending on the image clock frequency.

On the other hand, the video signal is applied to a binarization circuit 101 and compared with a threshold level to detect a slit projected image, that is, a bright line signal. Since this bright line signal and the image clock are added to the AND circuit 103, the width counter 10
5 counts clocks only during the period when a bright line image is obtained.

Therefore, for example, when the beam is divided into two and a binarized emission line symbol as shown in FIG. 10 (E) is obtained, the width counter is set as shown in FIG. 10 (E). The sum of the widths of the divided beams is counted, and when this counting is completed, the center of the beam can be determined by halving this value using a 1/2 circuit 1G7. 1/2
The circuit may be configured with a shift register, for example, and a 1/2 operation may be performed by shifting 1 bit.

Therefore, the value of the width counter is used as an address, and the value of the X address counter (Fig. 10 (d)) is used as data.
13, read the data using the output of the 172 circuit as an address, and the output of the comparison circuit 119 at this time is "1".
In that case, as shown in FIG. 10(G), for example, 55 indicates the center position of the beam from the projector from the left side.

When this situation is shown in FIG. 11, the clock count number 55 from the scanning start position indicates the center position of the left bright line. Then, when the contents of the X address counter and the X counter match, the output of the comparison circuit 119 is used as the congestion counter
Clear 5. That is, the counter is cleared when the scanning position reaches the light projection position on the reference plane indicated by the broken line in FIG. Then, the center position of the right bright line is detected in the same way, and when horizontal deflection (HD) blanking starts and the contents of the X address are read using the width center value as an address, the HD blanking start position is detected from the bright line position. The position of the beam by the right projector can be detected as the number of counts (value shown as m in FIG. 11).

After that, the width counter 105.1/2 circuit 107 is reset by the HD, and similar detection is performed for each horizontal scan.
i'IIA, the position of the right bright line is detected.

Note that the selector 111 is necessary when the RAMI 13 has one port, but is not necessary if the RAMI 13 has dual ports and can be accessed on a random basis.

Further, delay circuits 109 and 115 are used for timing adjustment of each circuit device.

Even when the beam is split in this way, the center position can be easily determined, making it possible to detect the bright line position with high accuracy and to measure distance with high accuracy.

〔Effect of the invention〕

As described above, according to the present invention, slit light is projected from the left and right toward the same pixel on the reference plane, the position of the slit light is scanned in synchronization with the TV signal, and the slit light is installed closer to the TV camera than the reference plane. By detecting the position of the bright line on the measured object, it is possible to obtain distance information of the object in a single scan without creating shadows, and by converting this distance information into an image together with the brightness image, accurate information can be obtained. It becomes possible to recognize the shape of a three-dimensional object.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an embodiment of a three-dimensional object measuring device according to the present invention, FIG. 2 is a diagram showing a scanning method, FIG. 3 is a diagram showing an example of measuring a hemispherical measurement object, and FIG. 4 is a diagram showing a beam 5 is a diagram showing the relationship between the distance resolution and the distance between the TV camera and the projector. FIG. 6 is a diagram showing a specific example of the three-dimensional measuring device of the present invention. Figure 8 shows the measurement results according to the present invention, Figure 8 shows the case where the bright line is divided by the measurement object, Figure 9 is a block diagram of the configuration for determining the center position of the beam, and Figure 10 shows the timing chart. 11 is an explanatory diagram for determining the center position, FIG. 12 is a diagram showing the configuration of a conventional three-dimensional measuring device, and FIG. 13 is an example of shadow areas, changes in bright line width, and bright line division. It is a diagram. 1... Television camera, 3a, 3b... Left and right floodlights, S... Reference plane, 5... Measurement plane, 7a, 7b,...
Slit□Light, 11.13...Step motor, 15
. . . Preprocessing section, 17. . . Position detection section, 19. . . Distance calculation section, 21. . . Distance data recording section, 23. 29
...Control table, 31...Left projection angle control section, 3
3...Right side projection angle control section. Applicant Hamamatsu Photonics Co., Ltd. Representative
Person Patent Attorney Masanobu Hirukawa Figure 1 Figure 2 Figure 4 Figure 3 (a)! *t5t TV j Mefuhi W Yo Expansion Figure 7 (a)' (b) (d) (c) Figure 11 1 e Figure 8 C a) Figure 9 remainder a? (10) Data left and right Figure 12 Figure 13

Claims (7)

[Claims] (1) A TV camera and two projectors placed on both sides of the TV camera that simultaneously project slit light perpendicular to the TV camera's scanning line from the left and right to the same position on the reference plane, synchronized with the TV signal. a projection angle control means for changing the projection angle of the projector so as to scan the projection position pixel by pixel on the reference plane; and a bright line produced by a slit light from a measurement object installed closer to the television camera than the reference plane. A three-dimensional object measuring device comprising a distance calculation means for calculating a distance to a measurement object from an imaging position, a projection angle, and the positions of a television camera and a projector. (2) A patent claim in which the bright line imaging position is recognized by comparing the light projection position address on the reference plane and the image clock count value for each horizontal scan, and separating them into left bright lines and right bright lines depending on their size. The three-dimensional object measuring device according to item 1. (3) The three-dimensional object measuring device according to claim 1, wherein the projection angle control means controls the projector drive motor using a control table created regarding the number of drive pulses and the projection angle. (4) The three-dimensional object measuring device according to claim 1, wherein the slit light from the left and right projectors is generated by a movable mirror that divides the light from the same laser into two. (5) The center position of the bright line is obtained by counting the clocks during the period during which bright line imaging data by slit light is obtained, and calculating the sum of the bright line widths, and finding it as the address corresponding to 1/2 of the counted value. The three-dimensional object measuring device described in Section 3. (6) The three-dimensional object measuring device according to claim 1, wherein the measurement object is separated from the reference plane by a distance that depends on the projection angle or the slit light beam width. (7) The three-dimensional object measuring device according to claim 1, wherein the distance data is converted into an image together with the brightness image.