JPH0455710A - Three-dimensional measuring apparatus - Google Patents

Abstract

PURPOSE:To achieve the high speed in three-dimensional measurement of a material to be measured by providing a distance computing part for computing the three-dimensional position of the profile point of the material to be measured based on the coordinates of the profile point stored in a profile-point memory. CONSTITUTION:The shutter array of a multi-slit projector 11 is controlled with a CPU 18 through an interface part 20. A coded multi-slit light pattern is projected on a material to be measured 23. In an image sensing device 12, the image of the multi-slit light 22 which is projected on the material to be measured 23 is picked up. The picked-up image signal is binary-coded in a binary coding circuit 13 of an image processor 10. The signal is supplied into an image memory 14 and an image operating part 15. In the operating part 15, weighting of the binary-coded signal is performed. The coordinate point is stored in a profile-point memory 16. In a distance computing part 17, the three-dimensional position of the profile point of the material to be measured 23 is computed based on the coordinates of the profile point stored in the memory 16.

Description

[Detailed Description of the Invention] [Summary] Regarding a three-dimensional measuring device that performs three-dimensional measurement by projecting multi-slit light, the present invention aims to speed up the three-dimensional measurement of a workpiece by using coded multi-slit light. a multi-slit light projector for projecting a pattern; an imaging device for imaging the coded multi-slit light pattern projected onto the object to be measured; a binarization circuit for binarizing the image signal from the imaging device; Each time the multi-slit light pattern is switched, the weighting of the binary image signal converted by the binarization circuit is changed, and the weighting is changed to the previous weighted binary image signal or the image signal of the previous addition result from the image memory. and the current weighted binary image signal, and store the coordinates of the contour point of the object to be measured corresponding to the multi-slit light decoded by the final calculation result of the image calculation unit. The apparatus is configured to include a contour point memory and a distance calculation section that calculates the three-dimensional position of the contour point of the object based on the coordinates of the contour point stored in the contour point memory.

[Industrial application field]

The present invention relates to a three-dimensional measurement device that performs three-dimensional measurement by projecting multi-slit light.

In automatic devices such as robots and shape input devices that input three-dimensional shapes, multi-slit light is projected onto the object to be measured, the image is captured by an imaging device, and a reference slit light is defined within the multi-slit light. A configuration is known in which the distance from an observation point to a contour point of an object to be measured is calculated.High-speed processing is required in such three-dimensional measurement.

[Prior art] As a multi-slit floodlight in a three-dimensional measurement device,
For example, the configuration shown in FIG. 9 has been previously proposed. That is, a single-wavelength laser beam from a semiconductor laser 51 is converted into parallel light by a collimating lens 52, and is incident on a first diffraction grating 54, producing an output light 58 in which spot lights are arranged in a line in the y-axis direction. The light is incident on the second diffraction grating 55.

Since the second diffraction grating 55 is configured such that its diffraction direction is perpendicular to that of the first diffraction grating 54, the spot light becomes output light 59 arranged in a plurality of rows and enters the cylindrical lens 53.

The first and second diffraction gratings 54,55 are, for example, 20~
It can be constructed from an optical fiber array with a diameter of about 70 μm.

Moreover, since the cylindrical lens 53 is extended in the X-axis direction, the output light 60 becomes multi-slit light with continuous spot lights in the Y-axis direction. If the cylindrical lens 53 is extended in the y-axis direction, the output light 60
becomes continuous multi-slit light in the X-axis direction. This output light 60 is incident on a shutter array 57 and becomes a coded multi-slit light pattern 56 by controlling the opening and closing of selected shutters. The shutter array 57 can be configured by, for example, a liquid crystal shutter using polarized light, a shutter using an electro-optic effect element, or the like.

FIG. 1O is an explanatory diagram of a coded multi-slit light pattern, and shows a case in which different patterns A, B, and C are projected to identify eight slit lights. The pattern is a pattern of every second slit light, and the C pattern is a pattern of every fourth slit light. Each time such three types of coded multi-slit light patterns are projected, the captured image signal is stored in the image memory, and, for example, at the position of the corresponding pick-up light of the stored image signal, , "1" for A pattern, "0" for B pattern, "1" for C pattern, then "C, B, A" = "101", so slit number 5 You will be able to recognize that it is light. That is, by projecting n coded multi-slit light patterns onto one multi-slit light beam,
All slit light numbers can be recognized.

Since it is possible to identify each number of the multi-slit light projected onto the object to be measured in this way, the three-dimensional position of each point on the object to be measured can be calculated based on the image signal obtained by imaging the object. , can recognize three-dimensional shapes.

[Problem to be solved by the invention]

The three-dimensional shape of the object to be measured can be measured by projecting a coded multi-slit light pattern and numbering the slit lights, but as mentioned above, in the conventional example, the coded multi-slit light Image signals corresponding to patterns are stored in respective image memories, and the coded multi-slit light is decoded, that is, the slit lights are numbered by comparing each image memory.
It has the disadvantage of requiring a large number of image memories.

In addition, the image memory matching process for coded multi-slit light beams is performed sequentially for each slit light.
Therefore, when projecting a large number of multi-slit lights, there is a drawback that the processing time becomes long.

An object of the present invention is to speed up three-dimensional measurement of an object to be measured.

[Means to solve the problem]

The three-dimensional measuring device of the present invention aims at high-speed processing by applying image processing, and will be explained with reference to FIG. 1.

A multi-slit projector 1 that projects a coded multi-slit light pattern by controlling a shutter array, etc., and an imaging device 2 that images the coded multi-slit light pattern projected onto the object to be measured from the multi-slit projector I.
A binarization circuit 3 binarizes the image signal from the imaging device 2, and weighting is applied to the binarized image signal converted by the binarization circuit 3 every time the coded multi-slit light pattern is switched. an image calculation section 5 that adds the previous weighted binary image signal or the image signal of the previous addition result read from the image memory 4 and the current weighted binary image signal; a contour point memory 6 for storing the coordinates of contour points of the object to be measured corresponding to the multi-slit light decoded by the final calculation result of the section 5;
The apparatus includes a distance calculation section 7 that calculates the three-dimensional position of the contour point of the object to be measured based on the coordinates of the contour point stored in the contour point memory 6.

Further, the multi-slit projector 1 is placed at a position parallel to the X-axis of the coordinates of the imaging device 2, that is, at a position perpendicular to the slit light of the multi-slit light, and the distance calculation unit 7 is placed in the contour point memory 6. It is constructed of a read-only memory (ROM) from which three-dimensional position data can be read using the coordinates of contour points stored in the memory as an address.

[Effect]

The multi-slit projector l includes a semiconductor laser, a first . By having a second diffraction grating, a cylindrical lens, and a shutter array, and controlling the shutter array,
A coded multi-slit light pattern can be projected. Further, the imaging device 2, like a television camera, images the object to be measured onto which multi-slit light is projected, and the image signal is binarized by the binarization circuit 3. In addition,
After the image signal is once stored in the image memory 4, it can also be binarized by the binarization circuit 3.

Every time the coded multi-slit light pattern is switched, the image calculation unit 5 changes the weighting of the binary image signal, and adds the previous weighted binary image signal and the current weighted binary image signal. Alternatively, the content of the image memory 4 in which the previous addition result was stored is added to the current weighted binary image signal. That is, the first binarized image signal of the coded multi-slit light pattern is stored in the image memory 4 with a weighting of 2'', the second binarized image signal is weighted 21, and the first binarized image signal is stored in the image memory 4. 2nd time and 2
The digitized image signals are added and stored in the image memory 4. Then, the weighting of the third binarized image signal is set to 22, the result is added to the previous addition result stored in the image memory 4, and the result is stored in the image memory 4.

Similarly, the nm-coded multi-slit light pattern is sequentially projected onto the multi-slit light consisting of 0 slit lights, and the weighting of the first binary image signal is set to 2.
'-1 is added to the previous addition result, and when the coded multi-slit light pattern is projected n times and the final addition result is obtained, decoded slit light is obtained.

Note that the weighting of the binarized image signal can also be performed in the binarization circuit 3.

Corresponding to this decoded slit light, the coordinates of the contour points of the object to be measured by multi-slit light projection are stored in the contour point memory 6.
The distance calculation unit 7 calculates the three-dimensional position based on the coordinates of the contour point. That is, the coordinate position of the contour point is calculated by applying the triangulation method.

Furthermore, by arranging the multi-slit light projection n1 at a position parallel to the X-axis of the coordinates of the imaging device 2, it is possible to obtain each coefficient for distance calculation in advance, and therefore,
It becomes possible to use a read-only memory (ROM) that reads out the three-dimensional position of the object to be measured from the coordinates stored in the contour point memory 6.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a block diagram of an embodiment of the present invention, in which 10 is an image processor, 11 is a multi-slit projector, 12 is an imaging device, 13 is a binarization circuit, and 14 are areas M1 to M1 each having a capacity of one screen. An image memory consisting of M4, 15 an image calculation section, 16 a contour point memory, 17 a distance calculation section, 18
is a processor (CPU) that controls each part; 19 is a main memory; 20 is an interface unit; 21 is a common bus;
2 is a multi-slit light beam, and 23 is an object to be measured.

For example, as shown in FIG. 8, the multi-slit projector 11 includes a semiconductor laser and a first . It has a second diffraction grating, a cylindrical lens, and a shutter array, and the shutter array is controlled by the processor 18 via the interface section 20, and a coded multislit light pattern is projected onto the object to be measured 23. The imaging device 12 is an object to be measured 23.
The multi-slit light 22 projected above is imaged, and the captured image signal is binarized by the binarization circuit 13 and added to the image calculation unit 15 or the image memory 14. Alternatively, the captured image signal is once stored in the image memory 14 and then
The data is binarized by the digitization circuit 13.

The image processor 10 includes a binarization circuit 13 and an image memory 1.
4, an image calculation section 15, and a contour point memory 16.
Weighting is performed on the digitized image signal, and control information for projecting a coded multislit light pattern from the multislit projector 11 is also transferred from the processor 18 to the image processor 10, and weighting is controlled based on the control information. will be held.

FIG. 3 is a flowchart of an embodiment of the present invention, consisting of steps 51 to 311, and FIG. 4 is an explanatory diagram of the operation of the embodiment of the present invention. In this embodiment, a case is shown in which multi-slit light consisting of eight slit lights is projected, but it is of course applicable to a case where a larger number of slit lights are projected.

First, the A pattern is projected onto the object to be measured 23 from the multi-slit projector 11, and the image signal captured by the imaging device 12 is stored in the memory area M1 of the image memory 14 (S
l). This A pattern is a pattern consisting of every other slit beam (indicated by a solid line), and the dotted line indicates that the slit beam is blocked by the shutter array. Furthermore, by capturing an image with the imaging device 12 from an angle different from the projection angle of the multi-slit light, the image is captured with the slit light bent or curved in accordance with the shape of the object to be measured 23. For example, When each slit light is imaged as a straight line, it can be seen that it is a plane.

Next, the A-pattern image signal stored in the memory area M1 is binarized by the binarization circuit 13, weighted, and stored in the memory area M2 as an image signal IA (S2);
In this case, the weighting is such that low level "0" is 0 and high level "1" is 2°=1 (H=2°). Therefore, as shown in pattern A in FIG.
The image signal IA is composed of multi-slit light expressed as 01010''.

Next, a B pattern is projected and the damage image signal is stored in the memory area M3 (S3). This B pattern is a pattern consisting of every two slit lights.

The image signal stored in this memory area M3 is binarized by a binarization circuit 13. The binarization circuit 13 or the image calculation unit 15 performs weighting, and for the high level "1" of the binarized image signal, 2I=2 and H=2'
) and is stored in the memory area M4 as an image signal IB (S4). Therefore, as shown in pattern B in Figure 4,
The image signal IB is made up of multi-slit light expressed as "22002200".

The image signal IA stored in the memory area M2 and the image signal IB stored in the memory area M4 are respectively read out and added by the image calculation unit 15, and the result is stored in the memory area M1 and used as the image signal Is. (S5). Therefore, as shown in FIG. 4, this image signal IS is “32
The image signal IS is made up of multi-slit light expressed as 103210''.

Next, the C pattern is projected and the captured image signal is stored in the memory area M3 (S6). This C pattern is a pattern consisting of every four slit lights.

The image signal stored in the memory area M3 is binarized by the binarization circuit 13, and the high level "1" of the binarized image signal is weighted by 22=4 (H=2
”), and store it in the memory area M4, and store it in the image signal I.
C (S7). Therefore, as shown in pattern C in FIG. 4, the image signal IC is made up of multi-slit light expressed as 44440000''.

Next, the image signal IS stored in the memory area Ml,
The image signal IC stored in the memory area M4 is added to the image signal IC by the image calculation unit 15, and the result is stored in the memory area M2 as an image signal Is" (S8). Therefore, as shown in FIG. , the image signal of the addition result is “76543
The coded multi-slit light becomes an image signal IS' consisting of multi-slit light represented by 210'', and the coded multi-slit light is decoded.The coding in this case is based on natural binary numbers, but other codes, For example, it is also possible to use a Gray code.

Since the image signal IS' stored in the memory area M2 indicating the decoding result is a multivalued number, it is binarized and the coordinate points at a level of 2° or higher are stored in the contour point memory 16 (S9). . Then, the contents of this contour point memory 16 are read out (5IO), and the distance calculation unit 17 for each coordinate point.
Distance calculation is performed (Sll). Although this distance calculation is performed by the dedicated distance calculation section 17, it can also be performed by the arithmetic function of the processor 18.

Further, if various parameters etc. are determined, it is also possible to configure the distance calculation section 17 with a read-only memory (ROM).

The outline of distance measurement will be explained with reference to FIG.

Assuming that the camera coordinate system with the origin at the lens center of the imaging device 12 is o-xyz, and the light source coordinate system with the origin at the light source center of the multi-slit projector 11 as o-xyz, the relationship between the two is as follows: m slit lights , and each slit optical surface is πtc
If we focus on the j-th slit light, where j = 1 to m), a projected image P is formed on the object to be measured by its projection, and the captured image I is on the image plane π of the imaging device 12. imaged. At that time, there are points P (Xm, Y
The three-dimensional position of k, Zk) is based on the principle of triangulation,
A point Im (xv,
Line of sight connecting y,) 01. It can be calculated as the intersection point between and the slit optical surface πj.

It is expressed as Here, Lij (x=1~3.j=1~4
) is a coefficient determined by the arrangement relationship between the multi-slit projector 11 and the imaging device 12, and can be determined by calculation.

The multi-slit floodlight 11 spreads around the y-axis with u =
h / g −・・−
(3) g”” (look at X* +t+zym +t+*
f) cosθJ(Ls+Xm+L3z)'h
+t3sf) sinθj・−・(4) h=t3nsinθ)−1,, cosθj −(
5) Here, (xl,,yk) indicates the position of P on the image plane, θ indicates the projection angle of the slit light plane πj,
f is the focal length.

(xh, yb) can be found as the coordinates stored in the contour point memory 16, and θj can be found from the decoded slit light number j. That is, the value of j can be determined as the gray level stored in the contour point memory 16.

FIG. 6 is a block diagram of the main part of the distance calculation section 17, and shows the coordinates X read out from the contour point memory 16.

yk and focal path If are input, and the slit light number (1
) to)) The corresponding calculation units 31-1 to 31-m calculate u(1) to u(m) according to the above-mentioned equation (3).

Then, the selector 32 adds u (j) corresponding to the slit light numbers (1) to (c) to the multipliers 33 to 35 according to the slit light number j, and multiplication is performed according to equation (2) to determine the three-dimensional position. Xk, Ym, and L are found.

In this case, the multi-slit projector 1] is connected to the imaging device 12.
By placing it at a position parallel to the coordinates of on the X axis, U in equation (3) becomes: U = α / (β + T) ... (6)
α=t,,sinθ,-tl,cosθj-'-(7)
β= L z CO3θ7+tIffsinθt
・-(8)T ” L 13 CosθJ-t,,si
It can be expressed as nθj −(9). and,
The coefficients t, ~LI4+131~t34 are, as described above,
This can be determined in advance, and although θj has m types of values according to the slit light numbers (1) to (e), it is possible to determine the coefficients α, β, and γ corresponding to this θj in advance. Therefore, U is a function of χ and θj, and therefore the value of U or
By storing the values of w, Yk, and L, the three-dimensional position of the object to be measured 23 can be quickly determined.

FIG. 7 is an explanatory diagram of the operation of vibration line processing according to an embodiment of the present invention, F1 to F8 indicate frames of image signals,
In frame F1, the A pattern is projected onto the object to be measured 23, and the image signal from the imaging device 12 is stored in the memory area M1. In the next frame F2, the A pattern image signal in the memory area M1 is binarized and stored in the memory area M2 as an image signal IA, and the B pattern is converted to the object to be measured 2.
3, and the image signal from the imaging device 12 is stored in the memory area M3.

In the next frame F3, the B pattern image signal in the memory area M3 is binarized and stored in the memory area M4 as an image signal IB.

In the next frame F4, memory area M2. The contents of M4 are added and stored in the memory area M1 as an image signal Is.

In the next frame F5, the C pattern is projected onto the object to be measured 23, and the image signal from the imaging device 12 is transferred to the memory area M3.
and stores it in memory area M3 in the next frame F6.
The C pattern image signal is divided into two and stored in the memory area M4 as an image signal IC.

In the next frame F7, memory SN areas M 1 , M
4 is added and the image signal I is stored in the memory area M2.
Store as S. This means that the coded multi-slit light has been decoded. Then, in the next frame F8, the image signal IS' in the memory area M2 is binarized and stored in the contour point memory 16.

In the case of 8 slit lights, the decoding process in this embodiment requires 7 frame periods, but in the case of a larger number of slit lights, for example, 16 slit lights, the decoding process requires 9 frame periods. It is possible to decode each frame period, or in the case of 32 slit lights, by 11 frame periods, so as the number of slit lights increases, decoding can be performed with a slight increase in the number of frames. become.

FIG. 8 is an operational explanatory diagram of pipeline processing according to another embodiment of the present invention, in which pattern A is projected in frame F1, an image signal from image pickup device I2 is stored in memory area Ml, and the next frame is A of memory area M1 in F2
The pattern image signal is binarized and stored as the image signal IA in the memory area M2, and at the same time, the B pattern is stored in the object to be measured 2.
3 and stores the image signal by the imaging device 12 in the memory area M34 is the same as that in the embodiment shown in FIG. F4. The processing in F5 is performed simultaneously; the C pattern is projected onto the object to be measured 23, the image signal from the imaging device 12 is stored in the memory area M4, and the B pattern image signal in the memory area M3 is stored in the memory area M3. The image signal IA in the memory area M2 is converted into a value, and the image signal IA is read out and added with a delay corresponding to the binarization process, and is stored in the memory area M1 as an image signal Is.

In the next frame F4, frame F6 of FIG.
The processing in F7 is performed simultaneously, and the C pattern image signal in the memory area M4 is binarized, and the C pattern image signal in the memory area M4 is binarized.
The image signal IS°1 is read out, subjected to addition processing with a delay corresponding to the binarization processing, and the image signal IS° is stored in the memory area M2.
Close and store. This means that the coded multi-slit light has been decoded. next frame F5
Similar to frame F8 in FIG. The step of projecting the A pattern can be initiated.

Also, the above-mentioned frame F3. Memory area M2 in F4.
The image signal read from Ml is stored in each memory area M1 to M4.
Since the address signal of the image signal IA is commonly given, the time required for the binarization process is delayed, but the image signal IA
, Is can be delayed to perform addition processing between the binarized image signals.

In this embodiment, by simultaneously performing the binarization of the image signal, the inter-image addition process, and the projection of the coded multi-slit light, in the case of eight slit lights, four In the case of 16 slit lights, it can be decoded using 5 frames, and in the case of 32 slit lights, it can be decoded using 6 frames. That is, it is possible to perform the decoding process in a shorter time than in the embodiment shown in FIG.

The present invention is not limited to the above-mentioned embodiments (although various additions and changes can be made).

〔Effect of the invention〕

As explained above, the present invention projects coded multislit light from the multislit projector 1 onto an object to be measured,
The image signal captured by the imaging device 2 is binarized by the binarization circuit 3, and each time the coded multi-slit light pattern is switched, the weighting of the binarized image signal is changed, and the previous binarized image signal is Alternatively, the coded multi-slit light can be decoded by adding the image signal of the previous addition result and the image calculation unit 5, and even if the number of slits in the multi-slit light is large,
The capacity of the image memory 4 can be reduced to, for example, about four screens, making it possible to achieve downsizing and economy.

Furthermore, by performing inter-image addition using an image processor or the like, the coded multi-slit light can be decoded at high speed, thereby increasing the speed of three-dimensional measurement processing.

Furthermore, by arranging the multi-slit projector 1 at a position parallel to the coordinate X-axis of the imaging device 2, it becomes possible to obtain coefficients, etc. for distance calculation in advance, making it possible to use read-only memory. Since it is possible to use a configuration in which three-dimensional coordinates are read out, the configuration is simplified and there are advantages in that high-speed processing is possible.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, FIG. 3 is a flowchart of an embodiment of the present invention, and FIG. 4 is an explanatory diagram of the operation of an embodiment of the present invention. Figure 5 is a distance measurement explanatory diagram, Figure 6 is a block diagram of the main parts of the distance calculation section,
FIG. 7 is an explanatory diagram of the operation of pipeline processing according to one embodiment of the present invention, FIG. 8 is an explanatory diagram of the operation of vibe line processing according to another embodiment of the present invention, and FIG. 9 is an explanatory diagram of the operation of pipeline processing according to an embodiment of the present invention. FIG. 10 is an explanatory diagram of a light projector, and FIG. 10 is an explanatory diagram of a coded multi-slit light pattern. 1 is a multi-slit projector, 2 is an imaging device, 3 is a binarization circuit, 4 is an image memory, 5 is an image calculation unit, 6 is a contour point memory, and 7 is a distance calculation unit. Block diagram of an embodiment of the present invention Fig. 2 A pattern Operation explanatory diagram of an embodiment of the present invention Fig. 4 Fig. 5 Fig. 7 Fig. 8

Claims (2)

[Claims] (1) A multi-slit projector (1) that projects a coded multi-slit light pattern, an imaging device (2) that captures an image of the coded multi-slit light pattern projected onto an object to be measured, and the imaging device (2). ); and a binarization circuit (3) that binarizes the image signal from the binarization circuit (3), and weighting the binarized image signal converted by the binarization circuit (3) each time the coded multi-slit light pattern is switched. an image calculation unit (5) that adds the previous weighted binary image signal or the image signal of the previous addition result read from the image memory (4) and the current weighted binary image signal; , a contour point memory (6) for storing coordinates of contour points of the object to be measured corresponding to the multi-slit light decoded by the final calculation result of the image calculation section (5); and the contour point memory (6). A three-dimensional measuring device comprising: a distance calculating section (7) that calculates a three-dimensional position of a contour point of the object to be measured based on the coordinates of the contour point stored in the object. (2) The multi-slit projector (1) is placed at a position parallel to the x-axis of the coordinates of the imaging device 2, and the distance calculation unit (7) is stored in the contour point memory (6). Claim 1 characterized in that the contour point is configured by a read-only memory that reads out the three-dimensional position based on the coordinates of the contour point.
The three-dimensional measuring device described.