JPH0735547A - Distance measuring device - Google Patents

Abstract

PURPOSE:To provide a distance measuring device capable of quickly finding three-dimensional distance information. CONSTITUTION:A set of video camera at the prescribed distance is installed for photographing the image of a measured object, and a trigger circuit 12 is provided for obtaining a characteristic point where the rate of change of optical information is equal to or above the preset value, regarding information detected with each camera. In addition, a device is so constituted that a counter unit 13 counts a parallax as a scanning time difference, thereby obtaining information regarding a distance up to the measured object.

Description

Detailed Description of the Invention

[0001]

INDUSTRIAL APPLICABILITY The present invention is suitable as, for example, a non-contact distance / dimension / speed measuring device for general use, an object recognizing means at a production site, and a sensor for a three-dimensional learning processing machine. The present invention relates to a distance measuring device for obtaining usable three-dimensional distance information.

[0002]

2. Description of the Related Art Conventionally, as a distance measuring device, for example, a spot light such as a laser beam is projected on a distance measuring object, and the reflected light is provided by a light receiving device installed at a set distance from a light source. There has been a method of calculating the distance to the measurement object by detecting and processing the signal obtained from it based on the principle of triangulation.

[0003]

However, in the conventional structure described above, when strong external light is present, there is a drawback that the detection accuracy is deteriorated by the noise due to the external light, and the measurement is performed. It is necessary to perform arithmetic processing for each measurement of one point on the object, and it is difficult to scan the laser light at high speed with high accuracy when obtaining a plurality of points or distances on a continuous line with respect to the object to be measured,
In addition, the processing time becomes long, and there is an adverse effect that it cannot be used in applications requiring high-speed response. The present invention aims to eliminate the above-mentioned problems.

[0004]

The features of the first invention are as follows:
A pair of optical information detecting means for detecting the optical information from the measurement object is installed at a set interval, and in the detection information of each of the optical information detecting means, the change rate of the optical information is a set value or more. It is characterized in that it is provided with a feature point detecting means for obtaining, and based on the feature points in the respective detection information obtained by the feature point detecting means, there is provided a computing means for computing the distance information to the measurement object.

A characteristic configuration of the second invention is that each of the optical information detecting means detects the optical information from the object to be measured while sequentially scanning in a synchronized state.

According to a third aspect of the invention, the arithmetic means is
The point is that the distance information to the measurement object is calculated from the scanning time difference of each characteristic point in the detection information of each optical information detecting means.

A characteristic configuration of the fourth invention is that it is provided with an adjusting means for changing and adjusting the rate of change of the optical information.

[0008]

According to the characteristic configuration of the first invention, the light information from the measurement object, for example, the light information such as the brightness information or the color information of the reflected light from the measurement object with respect to natural external light or specific irradiation light, Although detected by a pair of optical information detecting means, since each optical information detecting means is installed at a set interval, each detected information has a parallax. And
A feature point where the rate of change of the light information from the measurement object detected by each light information detection means is equal to or greater than a set value, that is, the edge of the measurement object having a large rate of change of the light information such as brightness or color. Find the characteristic points in a portion, a bent portion, or the like. Here, the characteristic point in each detection information indicates the physical same point of the measurement object, but each detection information has the parallax as described above, and is specified in each detection information caused by this parallax. The deviation of each feature point is related to the distance to the measuring object based on the principle of triangulation. Therefore, the distance information to the object to be measured can be obtained by the calculating means from the deviation of each feature point specified in each detection information.

According to the characterizing feature of the second invention, since each optical information detecting means detects the optical information from the object to be measured while sequentially scanning in a synchronous state, the optical information having parallax is sequentially and simultaneously detected. Can be detected.

According to the characteristic construction of the third invention, since the distance information is calculated from the scanning time difference of the optical information detecting means, it is possible to obtain the distance information almost in real time, and high speed processing becomes possible.

According to the characteristic construction of the fourth aspect of the invention, the rate of change of the optical information serving as a reference for obtaining each of the characteristic points is changed and adjusted in accordance with, for example, the brightness or the color tone of the external light, so that the object to be measured can be measured. The detection accuracy of feature points on an object is improved.

[0012]

According to the characteristic constitution of the first invention, the parallax of the left and right optical information detecting means is obtained based on the characteristic points in the continuous optical information of the measuring object. Even when the distance is obtained at a plurality of points or on a continuous line, the distance information can be obtained more quickly than the conventional method in which the light detection and the arithmetic control are repeated at each point.

According to the characteristic configuration of the second aspect of the invention, the deviation of each of the characteristic points can be obtained with a small time delay, and quick control is possible.

According to the characteristic construction of the third aspect of the invention, the calculation of the distance information can be processed at high speed, and more rapid control can be performed.

According to the characteristic construction of the fourth aspect of the present invention, it is possible to always set an appropriate characteristic point detection reference according to the change situation of external light, and it is possible to improve the detection accuracy of optical information.

[0016]

Embodiments will be described below with reference to the drawings. Figure 1
As shown in FIG. 2, two video cameras 1 and 2 [an example of optical information detecting means] for photographing the measurement object are installed with a set interval, and video signals output from these video cameras 1 and 2 are set. The present invention is provided with a signal processing device 3 for processing a signal, an image display device 4 for outputting various output information output by the signal processing device 3 as an image, and a personal computer 5 for recording and processing various output information. Configure a distance measuring device.

The video cameras 1 and 2 are NTSC,
All standards such as PAL and HDTV, CCD,
All types of cameras such as image pickup tubes, infrared night-vision cameras, temperature measurement cameras, etc. can be used, but they are installed at set intervals so that their optical axes are parallel, and both cameras 1,
2 are configured to be scanned in perfect synchronization.

As shown in FIG. 2, the signal processing device 3 has a reference timing 10 for signal processing for each unit.
A clock generation circuit 6 for generating a reference clock pulse of MHz, and a pair for converting the video signal input from each of the video cameras 1 and 2 and the differential value signal of the video signal before and after one clock pulse into an 8-bit digital signal. A / D
A converter 7, a counter module 8 that processes an output signal from the A / D converter 7 as described below and outputs a plurality of types of signals, and a bus driver 9 that selects a designated signal from the plurality of types of signals. And a D / A converter 10 for converting a digital signal into an analog video signal, a key input device 11 for performing various settings for the counter module 8, and the like.

The method of obtaining the parallax from the video signals of the two video cameras 1 and 2 will be explained. Since the optical axes of the video cameras 1 and 2 are set in parallel and the video signals are synchronously scanned, The brightness at each point on the scanning line is compared with the difference value [time differential value] before and after the clock time, and if the values are close, it is regarded as a corresponding point [feature point]. That is, the brightness of two points on the corresponding scanning lines in the left and right images and their difference values are V1, V2, and Δ, respectively.
Let V1 and ΔV2 be D and the allowable range of brightness and difference value, respectively.
Assuming 1, D2

[0020]

[Formula 1] | V1-V2 | ≦ D1

[0021]

[Formula 2] | ΔV1-ΔV2 | Since many uncharacterized parts are included in the image, the points in such parts cannot be correctly matched. Therefore, in the uncharacterized parts, there is a change without searching for the corresponding points as described above. Search only edge points. That is, only when the ΔV1 exceeds the trigger level TL, it is assumed that the point is a characteristic point, V1 and ΔV1 at that time are stored, and the signals V2 and ΔV2 of the video camera 2 satisfy the conditions of the expressions 1 and 2. When satisfied, the corresponding point of the video camera 2 corresponding to the signal of the video camera 1 is found. When the corresponding points are found, the distance between the corresponding points when the two images are superposed corresponds to the parallax. When the two images are superposed, the point on the image of the video camera located on the right side is always located on the left side. As shown in FIG. 4, the coordinates of the corresponding points in the left and right images are respectively P1 (x
R, y) and P2 (xL, y), the parallax ΔX is

[0022]

[Expression 3] ΔX = xL−xR, which specifically corresponds to the time difference on the scanning line of each video camera.

Next, the spatial coordinates between the video cameras 1 and 2 and the distance measuring object will be described. As shown in FIG. 3, the left and right video cameras 1 and 2 are respectively focused on the points OR and OL, and the video cameras 1 and 2 are installed so that their optical axes are on the same plane. In the figure, the broken lines represent the respective imaging fields of view. In the camera coordinates shown in FIG. 4, assuming that the horizontal and vertical widths of the image are a and b, respectively, and the aspect ratio of the image is p,

[0024]

## EQU00004 ## There is a relationship of b = p.a.

In space coordinates, the widths of the visual fields of one video camera in the horizontal direction and the vertical direction at the distance Z are W and H, respectively, and the distance between the points OR and OL is d (constant), the visual field. And the ratio of distance to the zoom factor f of the video camera
(Constant),

[0026]

[Equation 5] W = f · Z

[0027]

[Formula 6] H = p · W = p · f · Z. And in space coordinates and camera coordinates,
Since the field of view corresponds to the width of the screen, and the distance d corresponds to the parallax ΔX,

[0028]

## EQU00007 ## The relationship of a / .DELTA.X = W / d is established. Therefore, the distance Z to the target point from the above equations 5 and 7 is

[0029]

## EQU8 ## Z = d.a / f.ΔX, and the distance Z can be expressed by a simple relationship such that it is inversely proportional to the parallax ΔX. Also, regarding the distance in the X and Y directions,

[0030]

[Equation 9] X = d · x / ΔX

[0031]

(10) There is a relation of Y = d · y / ΔY. x is known by counting the horizontal scanning time from the horizontal synchronizing signal to the feature point, and y is known by detecting the horizontal scanning line number. Therefore, the three-dimensional position (X, Y,
Z) can be detected and output as a three-dimensional distance signal, and by using the original video image signal together, the three-dimensional position of an arbitrary point in the image can be measured and displayed. . One horizontal scanning period of the video camera is about 63.5
Since this image signal is microseconds and this image signal is sampled at every 10 MHz clock, the maximum horizontal coordinate of the camera coordinate is 635 counts. The maximum vertical coordinate is 525 counts.

Next, the detailed structure and operation of the counter module 8 will be described. The counter module 8 has a trigger circuit 12 (corresponding to feature point detecting means) that triggers when a feature point (a point that is higher than the trigger level TL) is detected in the right image, and a right image when the trigger is activated. Data is stored, the points on the left image are compared in order, and if the corresponding points are regarded as corresponding points, a plurality of counter units 13 (corresponding to arithmetic means) that output parallax signals, and failure to take correspondence Each of the reset circuits 14 for resetting the counter unit 13 is provided. More specifically, the trigger circuit 12 is
As shown in FIG. 5, when the comparison circuit 15 has a change larger than the trigger level TL in the right image,
The counter circuit 16 sequentially supplies the trigger signal TRIG to the counter unit 13 via the decoder circuit 17 to activate it. If the next counter unit 13 is counting and is not ready, the preparation signal READ
Based on Y, a predetermined signal OF is transmitted via the multiplexer 18.
Is output.

When receiving the trigger signal TRIG, each counter unit 13 stores the data [brightness and difference value] of the point on the right image at that time in the flip-flops 19 and 20, and the counter circuit 13 At 21, the counting of the reference clock CLK is started. That is, the scanning time difference between each feature point is counted. Then, the data of the points in the left image are sequentially compared to search for corresponding points. At this time,
It is assumed that the above-mentioned formulas 1 and 2 are simultaneously satisfied. This comparison is made in the two comparison circuits 22 and 23. That is, it is assumed that the difference between the stored brightness V1 of the point on the right image and the changing brightness V2 of the point on the left image is taken, and when the value becomes smaller than the set value of D1, the values match. Comparison circuit 22]. Brightness difference ΔV1-ΔV2
Is also compared with the above D2 [second comparison circuit 2
3], the matching signal Matc via the AND circuit 24 is regarded as corresponding when both the brightness and the difference value thereof match.
Output h. When the corresponding points are found, the count value, that is, the distance [parallax] signal 3Ddata between the corresponding points is output.

The reset circuit 14, as shown in FIG.
Encoder 25, counter 26, flip-flop 2
7. The counter unit 13 which is equipped with the decoder 28 and fails to take the correspondence is reset. In addition, all the counter units 13 are reset each time the scanning line ends. The counter unit 13 is sequentially applied from the point on the left side of the image by the trigger circuit 12 to start counting,
You should be able to correspond from the point on the left side of the screen. It is not possible that the points on the right side of the screen correspond to the points on the left side of the screen first, and vice versa. Therefore, when a certain point can be taken into correspondence, it can be seen that the point to the left of that point and which has not taken correspondence has failed to take correspondence. Explaining with the operation time chart of FIG. 8, the horizontal axis in this figure represents time [horizontal coordinates of the video camera], points on the horizontal axis represent characteristic points, and circled numbers represent numbers of the counter unit 13. The upper side corresponds to the scanning line in the right image and the lower side corresponds to the scanning line in the left image. The case where the counter unit 13 in this fails in correspondence is shown.

This device is provided with a multi-feature point detection function by high-speed parallel processing. In other words, by equipping multiple counter modules, there are many feature points in one horizontal scanning period, and even if one counter is triggering and searching for corresponding points, another counter is used to trigger in parallel. It can be processed. Further, since the counter that has already been reset is in the standby state, it is possible to deal with detection of many feature points and distances even with a small number of counter modules.

The bus driver 9 selects and outputs from the left and right image signals, their difference signals, distance signals, and various signals of the feature point image based on the selection signal. Hold the latest value for the distance signal.

The D / A converter 10 converts a digital signal into an analog signal and outputs it to the image display device 4. The image display device 4 can output the distance signal obtained as described above as an image. In addition, the key input device 11 controls the trigger level T based on an artificial operation.
It is possible to change and set L, the reference values D1 and D2 of the brightness and the difference value, and the like. Therefore, the key input device 11 corresponds to a means for adjusting the rate of change of optical information. The personal computer 5 stores the distance signal information in the memory.

9 to 11 show simulation results by the present inventor in this distance measuring device. FIG. 9 shows the image data of the scanning lines in the images of the left and right video cameras 1 and 2, and the one shifted to the left is the image of the right video camera. In the figure, the vertical axis represents brightness and the horizontal axis represents horizontal coordinates. 10 shows a distance signal when the reference clock frequency is set to 10 MHz, and FIG. 11 shows a distance signal when the reference clock frequency is changed to 5 MHz. In this figure, the vertical axis represents the distance, and the upper side in the figure indicates that the distance is shorter. The horizontal axis represents horizontal coordinates.

[Other Embodiments] In the above embodiment, the control is performed by using the brightness of the image, that is, the luminance signal in the video signal, but in addition to this, in the color video signal, R, G, B are used.
If the respective color difference signals are also used together, the accuracy will be further improved. Further, in the above embodiment, the video camera is used as the light information detecting means, but the present invention is not limited to this, and processing using a high-definition camera is also possible, and a pair of linear light detecting sensors can be used to measure an object to be measured. It is also possible to detect and process linear light information at a specific location.

It should be noted that reference numerals are added to the claims for facilitating the comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a block diagram of a distance measuring device.

FIG. 2 is a block diagram of a signal processing device.

FIG. 3 is a diagram showing spatial coordinates

FIG. 4 is a diagram showing camera coordinates.

FIG. 5 is a block diagram of a trigger circuit.

FIG. 6 is a block diagram of a count unit.

FIG. 7 is a block diagram of a reset circuit.

FIG. 8 is an operation timing chart.

FIG. 9 is a diagram showing image data.

FIG. 10 is a diagram showing a distance signal.

FIG. 11 is a diagram showing a distance signal.

[Explanation of symbols]

 1, 2 Optical information detecting means 11 Adjusting means 12 Feature point detecting means 13 Computing means

Claims (4)

[Claims] 1. A pair of optical information detecting means (1), (2) for detecting optical information from an object to be measured are installed at set intervals, and each of the optical information detecting means (1), (2). ), A feature point detecting means (12) for obtaining a feature point having a change rate of optical information equal to or more than a set value is provided, and the feature point in each detection information obtained by the feature point detecting means (12). A distance measuring device provided with a calculating means (13) for calculating distance information to the object to be measured based on the above. 2. The optical information detecting means (1), (2)
2. The distance measuring device according to claim 1, wherein the optical information from the measuring object is detected while sequentially scanning in a synchronized state. 3. The calculation means (13) calculates distance information to a measurement object from the scanning time difference of each characteristic point in the detection information of each of the optical information detection means (1) and (2). The distance measuring device according to claim 2. 4. The distance measuring device according to claim 1, further comprising adjusting means (11) for changing and adjusting the rate of change of the optical information.