JPH0827839B2 - Slit image labeling device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a three-dimensional object recognition technique using a light-section method applied to, for example, the vision of a robot. The present invention relates to a slit image labeling device for labeling each slit image by associating each slit light with its slit image in the case of applying the light cutting method by irradiating slit light all at once.

<Prior Art> In general, the “light cutting method” irradiates a plate-shaped slit light toward a three-dimensional object to generate an intersecting line of the slit light on the object surface, and the intersecting line is imaged by a television camera. The ray image (hereinafter referred to as “slit image”) is obtained by calculating the three-dimensional coordinates of the points on the intersection line from the coordinates of each point on the slit image and the equation of the plane of the slit light. is there.

However, in the case of this kind of method, only the information about the portion irradiated with the slit light can be obtained, which makes it difficult to recognize the entire object.

Therefore, in order to obtain information on the entire object, a large number of slit lights are generated by scanning the slit light using a reflecting mirror,
A method has been proposed in which a large number of intersecting lines are formed by being distributed over the entire object by applying each slit light to the surface of the object.

However, in the case of this method, since the intersecting line is imaged at each scanning position of the slit light, there is a problem that the number of times the intersecting line is imaged increases and the time required for the recognition process increases.

In order to solve this problem, in recent years, a method has been proposed in which a large number of slit lights are generated at the same time and these are irradiated onto the object surface all at once.

When adopting this type of irradiation method, it is necessary to perform a process (which is referred to as "slit image labeling") for determining which slit light each of the plurality of slit images obtained by the television camera corresponds to. As one of the methods, a method has been proposed in which slit light is spatially coded with a gray code to illuminate an object (The 59th General Meeting of the Institute of Electrical Communication of Japan, "Distance Image Generation by Gray Code Space Projection").

<Problems to be Solved by the Invention> However, this method has a drawback that it is susceptible to external factors such as variations in the reflectance of the object surface.
Moreover, at least N (e.g., 8) imagings are required to obtain 2 ^N -1 (e.g., 256) slit images, and there is a limit in reducing the number of imagings.

The present invention is for solving the above-mentioned problems, and it is possible to obtain the information necessary for object recognition by imaging only twice and to label each slit image regardless of the number of slit images. An object of the present invention is to propose a labeling device for a simple slit image.

<Means for Solving Problems> In order to achieve the above object, in the present invention, a projecting means for irradiating an object with a plurality of slit light beams twice before and after, and radiant energy of each slit light beam are individually supplied. Control means for setting and controlling independently, imaging means for imaging the intersecting line of each slit light generated on the object surface to obtain the slit image of each slit light, and light irradiation twice before and after The brightness information processing means for simultaneously acquiring the brightness information of the corresponding pixels in the two obtained images at the same time to obtain the relationship between the two brightness information, and the relationship between the two brightness information for each slit light The label setting means for allocating the label of each slit light to each slit image by collating with the relationship between the radiant energy and the set value before and after twice.

<Operation> When a plurality of slit light beams are simultaneously emitted to the object by the light projecting means, intersection lines of the slit light beams are simultaneously generated on the surface of the object. These intersecting lines are imaged by the image pickup means to obtain the slit image of each slit light. The same operation is performed twice before and after, whereby two images are obtained.

The brightness information of the pixels corresponding to these two images is sequentially taken into the brightness information processing means at the same time, and the relationship (for example, the rate of change) between the two brightness information is obtained here.
The relationship between the two pieces of brightness information is collated with the relationship between the set values of the radiant energy for each slit light before and after twice in the label setting means. If the two match as a result of the matching, the slit image is determined to correspond to the slit light, and the slit light is labeled with the slit light for matching.

Therefore, in the case of this apparatus, it is possible to label each slit image by imaging only twice regardless of the number of slit images, and the processing time for object recognition is shortened accordingly.

<Example> FIG. 1 shows a three-dimensional object recognition system incorporating a slit image labeling device of the present invention.
It includes a multi-slit light source 1, a slit light modulator 2, a television camera 3, and an image processing device 4.

The multi-slit light source 1 of the illustrated example irradiates the three-dimensional object 5 to be recognized with a plurality of plate-shaped slit lights 6 in parallel from an obliquely upper position, and generates an intersecting line 7 where the slit lights intersect on the object surface. To do. In this case, each slit light 6 is simultaneously irradiated toward the object 5, and this light irradiation is performed twice before and after one object recognition process.

The slit light modulator 2 is for controlling the energy radiated within one frame period for each of the plurality of slit lights 6 to a set value, and as a control method thereof, controls the length of the lighting time within one frame period. One of the following methods is adopted: a PWM method, a method of controlling the number of pulses to be lit in one frame period (PNM method), and a method of controlling the pulse lighting frequency in one frame period (PFM method). The setting of the radiant energy value for each slit light 6 is performed independently for each slit light, and each time the light irradiation is performed twice before and after.

The television camera 3 images a plurality of intersecting lines 7 simultaneously formed on the surface of the object by irradiating the light twice from the position directly above the object 5 each time to generate a slit image of each slit light 6.

FIGS. 2 (1) and 2 (2) show an example of two images 9A and 9a obtained by imaging twice.

The first image 9A shows slit images A _{1 to} A ₃ of each slit light 6 by the first light irradiation, and the second image 9a shows the slit image a of each slit light 6 by the second light irradiation. _{1 to} a ₃ ,
Each slit image includes one or more segments (for example, the slit image A ₁ has three segments A ₁₁ , A ₁₂ , and A).
Consisting of ₁₃ ).

Returning to FIG. 1, the image processing apparatus 4 takes in each of the images 9A and 9a from the television camera 3 each time, and outputs each slit image A.
Labeling of each slit image is performed by using the brightness information for each segment of _{1 to} A ₃ , a _{1 to} a ₃ , and then the coordinates of the points on each slit image and the equation of the plane of each slit light 6 are calculated. From this, the coordinates of the point on the intersection line 7 are calculated to recognize the object.

In Fig. 2 (1), I ₁₁ , I ₁₂ , ... are the first image 9A.
The brightness of each segment, in addition in Figure 2, i _11,
i ₁₂ , ... Show the brightness of each segment in the second image 9a.

When the radiant energy of the existing slit light is P and the brightness of the slit image of this slit light is I, the relationship of the following equation is established between the two.

In the above formula, Is the position and orientation of the TV camera, Is the position / orientation of the object, α is the reflectance of the object, and f
Are these It is a function of α.

Next, when it is assumed that the brightness of the slit image changes from I to i when the radiant energy of the slit light is changed from P to p, the following equation is satisfied.

According to this equation, the change rate of the radiant energy of the slit light and the corresponding change rate of the brightness of the slit image are the position and orientation of the TV camera. Position / posture of light source Object position / posture It can be seen that they agree with each other without depending on the reflectance α of the object.

The following equation is a more generalized expression of the above equation. In this equation, when m = 1, a = 1, b = 0, d = 1, e = 1, the relation of the above equation is derived. Get burned.

Thus, in the device according to the present invention, when a plurality of slit light beams 6 are radiated to the object 5 simultaneously twice before and after, the relationship between the radiant energies of the first time and the second time for each slit light (the relationship on the right side of the equation). And for each slit image, the relationship between the first brightness and the second brightness (relationship on the left side of the formula) is obtained, and these two are collated. Is configured to assign the label of. In the case of this embodiment, the rate of change in brightness (left side of the equation) for each slit image is obtained and collated with the rate of change in radiant energy (right side of the equation) for each slit light, and the equations match. Items are labeled by determining that they correspond to each other.

FIG. 3 shows a concrete example of the configuration of the image processing apparatus 4, and FIG. 4 shows signal waveforms of respective parts of the circuit.

In FIG. 3, a video signal I ′ (t) (shown in FIG. 4 (1)) is applied to the input terminal 11 from the television camera 3. The video signal I '(t) is a time-series signal (I' (t) in which a video signal A '(t) for the first image and a video signal B' (t) for the second image are sequentially provided. t) = A '(t) + B' (t)). The video signal I ′ (t) contains a noise component 19 as shown in FIG. 4 (1). The noise component 19 is removed by the low-pass filter 12 and the noise removal signal I (t) (=
A (t) + B (t)).

The noise-removed signal I (t) is the first image signal A (t) (shown in FIG. 4 (4)) and the second image signal B (t) (FIG. 4 ( 5)) and). The switching device 13 has a first image signal A
The first time control signal G ₁ (t) (shown in FIG. 4 (2)) and the second image signal B which are turned on for the time width corresponding to (t)
A second time control signal G ₂ (t) which is turned on for a time width corresponding to (t) (shown in FIG. 4 (3)) is given, and these control signals G ₁ (t), G ₂ (t ) The switch 13 is switched at the timing of time.

The first image signal A (t) is given to the A / D converter 14 and converted into a digital signal at the time timing of the first time control signal G ₁ (t), and then temporarily written in the image memory 15.

On the other hand, the second image signal B (t) is given to the other A / D converter 16 and similarly analog-digital converted at the time timing of the second time control signal G ₂ (t), and then the digital signal thereof. B _D (t) is output to the table memory 16. In this case, the digital signal A _D (t) of the first image signal A (t) is read from the image memory 15 in synchronism with the timing of analog-digital conversion.
_D (t) is output to the table memory 16. This digital signal A _D (t) is delayed from the first image signal A (t) by the time interval t _f between the first image and the second image (A _D (t) = A (t -T _f )), and as a result, the brightness information on the same pixel in each of the first and second images is synchronously applied to the table memory 16 one after another.

The brightness information of each pixel has a data structure of, for example, 8 bits, and two brightness information (8 bits + 8 bits = 16 bits) are given to the table memory 17 as an address input. The table memory 17 stores the label of slit light, which is assigned based on the above principle, for all combinations of two pieces of brightness information.

The following equation expresses the table contents of the table memory 17, that is, the output θ (t) of the table memory 17 with respect to the inputs of the two digital signals A _D (t) and B _D (t) ((6) in FIG. 4).
In the same equation, the function L is a function for converting the rate of change in brightness into a label.

The output θ (t) of the table memory 17 is the image memory 18
Therefore, a label image in which a label is assigned to the constituent pixels of each slit image is generated in the image memory 18.

It should be noted that the output θ (t) shown in FIG. 4 (6) includes three labels, and the pixel group shown by i _{1 to} i ₆
The label 1 is assigned to i ₃ and i ₆ , and the label 2 is assigned to pixel i ₂ and i _4.
Label 3 is assigned to i ₁ and i ₅ , respectively.

FIG. 5 shows another example of the configuration of the image processing apparatus 4, and FIG. 6 shows the signal waveform of each part of the circuit.

The embodiment shown in FIG. 5 has a hardware configuration for processing two pieces of brightness information in a digital amount in the embodiment shown in FIG. 3, whereas it processes two pieces of brightness information in an analog amount. The difference is that it is a hardware configuration.

In FIG. 5, reference numeral 21 denotes an input terminal, which is a video signal I ′ (t) from the television camera 3 (shown in FIG. 6 (1)).
Is given. This video signal I '(t) is a time-series signal (I' (t) = A '(t) including video signals A' (t) and B '(t) of the first and second images. + B '(t)), and the noise component is removed by the low-pass filter 22 to become the noise removal signal I (t) (= A (t) + B (t)).

Of this signal I (t), the first image signal A (t) (sixth image signal
(Shown in FIG. 4) is given to the A / D converter 23 and converted into a digital signal at the time timing of the first time control signal G ₁ (t) (shown in FIG. 6 (2)). It is once written in the image memory 24.

Then, the digital signal of the first image signal A (t) is read out from the image memory 24 at the time timing of the second time control signal G ₂ (t) (shown in FIG. 6 (3)). The D / A converter 25 converts the analog amount into the first image signal X (t) (shown in FIG. 6 (6)).

The first image signal X (t) and the second image signal B
(T) (shown in FIG. 6 (5)) is applied to the differential amplifier 26 and the difference signal Y (t) (= X (t) -B (t)) between the two is given.
(Shown in FIG. 6 (7)) is required. In this case the first
The image signal X (t) is delayed from the first image signal A (t) by the time interval t _f between the first image and the second image (X (t) = A (t−t). _f )), and as a result, the brightness information on the same pixel in each of the first and second images is synchronously applied to the differential amplifier 26 one after another.

The first image signal X (t) is given to the inverting circuit 27 to become the inverted output 1 / X (t), and this output and the difference signal Y (t) are given to the arithmetic circuit 28, and the following equation is obtained. Is executed to output an analog amount label image O (t)
(Shown in FIG. 6 (8)) is obtained.

Next, the operation of the entire apparatus will be described with reference to FIG.

First, the value of the radiant energy of each slit light 6 is set independently, and then all slit light 6
Are simultaneously radiated from the multi-slit light source 1 toward the object 5. The radiant energy of each slit light 6 is controlled to each set value by the slit light modulator 2, and the surface of the object 5 has an intersection line of brightness according to the magnitude of the radiant energy of each slit light 6. Is generated. Each intersection line is imaged by the television camera 3, an image including all slit images is generated on the imaging surface of the television camera 3, and the video signal thereof is sent to the image processing device 4.

Next, the values of the radiant energy of each of the plurality of slit light beams 6 are individually set again, and the slit light beams 6 are simultaneously irradiated from the multi-slit light source 1 to the object 5. In this case, the value of the radiant energy is determined based on the rate of change set to a different value for each slit light.

By irradiating the slit light 6 all at once, intersecting lines of each slit light are generated on the surface of the object 5, the second slit image is captured by the television camera 3, and an image including all slit images is displayed on the television camera 3. Is sent to the image processing device 4.

Thus, in the image processing apparatus 4 having the configuration shown in FIG. 3, two pieces of brightness information corresponding to two images are simultaneously taken out and processed in digital amounts, and in the image processing apparatus having the configuration shown in FIG. Labeling of each slit image is performed by simultaneously extracting two corresponding pieces of brightness information and processing them with an analog amount.

<Effects of the Invention> As described above, the present invention irradiates a large number of slit lights at the same time to perform image processing thereof, and moreover, the information necessary for object recognition can be obtained by imaging only twice regardless of the number of slit images. Since each slit image is obtained and labeled, the number of times of imaging can be significantly reduced as compared with the conventional method, and the recognition processing time can be shortened. In addition, when labeling, it is not adversely affected by external factors such as variations in the reflectance of the object surface,
There is a remarkable effect that the object of the invention is achieved such that there is no risk of erroneous determination.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration example of an object recognition system in which the labeling device of the present invention is incorporated, FIG. 2 is an explanatory diagram showing images obtained by two times of imaging, and FIG. 3 is an image processing device. FIG. 4 is a circuit block diagram showing one embodiment, FIG. 4 is a time chart of the circuit configuration example of FIG. 3, FIG. 5 is a circuit block diagram showing another embodiment of the image processing apparatus, and FIG. 6 is FIG. It is a time chart of a circuit configuration example. 1 ... Multi-slit light source 2 ... Slit light modulator 3 ... TV camera 4 ... Image processing device 6 ... Slit light

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 63-195773 (JP, A) JP 63-196981 (JP, A) JP 63-201877 (JP, A) JAACE '87 -5 Proc. Of the 31st System and Control Research Presentation, 31 (1987) P. 49-50

Claims (4)

[Claims] 1. A light projecting means for irradiating an object with a plurality of slit lights simultaneously twice before and after, a control means for individually setting and controlling the radiant energy of each slit light, and an object surface. The image pickup means for obtaining the slit image of each slit light by imaging the intersecting line of each slit light generated, and the brightness information of the corresponding pixel for the two images obtained by the light irradiation twice before and after at the same time. A brightness information processing means for sequentially capturing and obtaining a relationship between two pieces of brightness information, and a relationship between the two pieces of brightness information is collated with a relationship between two set values before and after the radiant energy for each slit light. A slit image labeling apparatus comprising label setting means for allocating a label of each slit light to each slit image. 2. The slit image labeling apparatus according to claim 1, wherein the brightness information processing means has a hardware configuration for processing two pieces of brightness information in a digital amount. 3. The slit image labeling device according to claim 1, wherein said brightness information processing means has a hardware configuration for processing two pieces of brightness information in an analog amount. 4. The brightness information processing means includes an image memory for storing a first image, and data reading from the image memory and data input of a second image are executed in synchronization with each other. The slit image labeling device according to any one of claims 1 to 3, wherein the brightness information of the corresponding pixels is simultaneously captured by the above.