JP2001074418A - Method and apparatus for measuring moving object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate setting of operational conditions and to ensure high accuracy measurement while releasing restriction on the installing place even when the moving speed of an object is low or the object is stationary by providing a process for extracting a relative position having a maximum correlation value as a moving distance. SOLUTION: An image pickup means 105 picks up the image of a moving body to produce a time series image and a correlation value operating means 108 operates a correlation value by varying the relative position of two images preceding and following in time series. Subsequently, a moving distance extracting process extracts a relative position having a maximum correlation value as a moving distance. In other words, the correlation value operating means 108 operates a correlation value based on picked up images in order to measure a moving object. Data operated by a central processing means 103, i.e., moving distance, moving speed and accumulated moving distance, are delivered to an IO controller 102. The IO controller 102 transfers the data to an external unit, e.g. a data collector or the control section of a transfer unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention belongs to the technical field of measuring position, speed, cumulative moving distance, acceleration, and the like. In particular, the present invention relates to a method and an apparatus for measuring a moving body in a non-contact manner by capturing an optical image of the moving body.

[0002]

2. Description of the Related Art As a method for optically measuring the motion of an object in a non-contact manner, a laser Doppler method is known. The laser Doppler method is a method in which a laser beam irradiated on an object and a laser beam reflected from the object interfere with each other. It is.

[0003]

However, in a measuring apparatus to which the laser Doppler method is applied, it is difficult to set operating conditions and the installation place is largely restricted. When the moving speed of the object is low, the measurement error is large or measurement is impossible. They are also generally expensive.

The present invention has been made to solve such a problem, and has as its object the case where the operating conditions can be easily set, the installation location is less restricted, and the moving speed of the object is low. Or even when stationary,
It is an object of the present invention to provide a moving object measuring method and device capable of performing highly accurate measurement.

[0005]

The above object is achieved by the present invention described below. In other words, the moving object measurement method according to claim 1 of the present invention includes an imaging process of imaging a moving object and outputting a time-series captured image, and changing a relative position between two time-sequential captured images. The method includes a correlation value calculating step of calculating a correlation value, and a moving distance extracting step of extracting a relative position at which the correlation value has a maximum as a moving distance. According to the present invention, a moving object is imaged in an imaging process, a time-series captured image is output, and a correlation value is calculated by changing a relative position of two time-sequential captured images in a correlation value calculation process, In the moving distance extraction process, the relative position where the correlation value becomes maximum is extracted as the moving distance. In this way, the mobile object is measured by calculating the correlation value based on the captured image. Therefore, it is easy to set the operating conditions, the installation location is less restricted, and the movement that can perform high-accuracy measurement regardless of whether the moving speed of the object is low or stationary. A body measurement method is provided.

According to a second aspect of the present invention, in the moving object measuring method according to the first aspect, the moving distance is divided by a time interval between two captured images preceding and following the time series. Thus, a moving speed calculating process for calculating the moving speed is provided. According to the present invention, the moving speed is calculated.

According to a third aspect of the present invention, there is provided the moving object measuring method according to the first or second aspect, wherein all of the moving distances of the predetermined time period in the time series are integrated to accumulate the moving distance. The present invention has a cumulative moving distance calculating step of calculating a distance. According to the present invention,
An accumulated moving distance is calculated.

According to a fourth aspect of the present invention, in the moving object measuring method according to any one of the first to third aspects, the captured image is one-dimensional with respect to a moving direction of the moving object. This is a line profile image obtained by performing the above-described imaging. According to the present invention, one-dimensional movement (linear movement) is measured at high speed.

In the moving object measuring method according to a fifth aspect of the present invention, in the moving object measuring method according to the fourth aspect, the correlation value calculating step includes two line profiles which move the correlation value back and forth in time series. This is a process in which each pixel value of an image is obtained as an inner product of a vector having components. According to the present invention, a correlation value as an inner product of vectors can be obtained at high speed.

According to a sixth aspect of the present invention, there is provided a moving object measuring apparatus, comprising: an image pickup means for picking up an image of a moving object and outputting a time-series picked-up image; A correlation value calculating means for calculating a correlation value by changing;
Moving distance extracting means for extracting, as a moving distance, a relative position at which the correlation value becomes maximum. According to the present invention, the moving body is imaged by the imaging means, a time-series captured image is output, and the correlation value is calculated by changing the relative position of the two captured images preceding and succeeding in time series by the correlation value calculation means, The relative position at which the correlation value becomes maximum is extracted as the moving distance by the moving distance extracting means.
In this way, the mobile object is measured by calculating the correlation value based on the captured image. Therefore, it is easy to set the operating conditions, the installation location is less restricted, and the movement that can perform high-accuracy measurement regardless of whether the moving speed of the object is low or stationary. A body measurement device is provided.

According to a seventh aspect of the present invention, in the moving object measuring method according to the sixth aspect, the moving distance is divided by a time interval between two captured images preceding and following the time series. Thus, a moving speed calculating means for calculating the moving speed is provided. According to the present invention, the moving speed is calculated.

[0012] In the moving object measuring apparatus according to claim 8 of the present invention, in the moving object measuring method according to claim 6 or 7, the moving object is accumulated by integrating all the moving distances in a predetermined period in the time series. It has a cumulative moving distance calculating means for calculating the distance. According to the present invention,
An accumulated moving distance is calculated.

According to a ninth aspect of the present invention, in the moving body measuring method according to any one of the sixth to eighth aspects, the imaging means is one-dimensional with respect to a moving direction of the moving body. This is a line sensor camera that outputs a line profile image for capturing an image. According to the present invention, one-dimensional movement (linear movement) is measured at high speed.

According to a tenth aspect of the present invention, in the moving object measuring apparatus according to the ninth aspect, the correlation value calculating means is configured to change the correlation value forward or backward in time series.
This is a means for obtaining as a dot product of a vector having each pixel value of one line profile image as a component. According to the present invention, a correlation value as an inner product of vectors can be obtained at high speed.

[0015]

Next, an embodiment of the present invention will be described. FIG. 1 shows an example of the configuration of the moving object measuring device of the present invention. In FIG. 1, 101 is a push button switch, 102 is an I / O controller, 103 is a central processing unit, 104 is a timing generation unit, 105 is an imaging unit, 106 is an A / D conversion unit, 107 is a buffer memory, and 108 is a correlation. Value calculation means, 109 is an LED controller, 110 is an LED panel.

The push button switch 101 is provided so that the operator can input a trigger for starting the measurement of the moving object to the moving object measuring device. An open / close signal of the push button switch 101 is output to the I / O controller 102. Of course, if necessary, the push button switch 101
Instead of this, it is also possible to configure so that a relay contact is output from a control panel of a device for transferring articles, and automatic measurement is performed at a predetermined timing.

The I / O controller 102 controls input / output of an opening / closing signal, other signals, measurement data, control data, and the like between the central processing unit 103 and an external device. The central processing means 103 performs data input / output control and data processing. The central processing unit 103 can be realized by hardware and software of a data processing device such as a microcomputer, a programmable sequencer, and a personal computer.

The timing generation means 104 generates a timing signal for imaging in the imaging means 105 based on a trigger input inputted from the central processing means 103. Further, a timing signal is generated when the central processing unit 103 inputs a correlation value (described later) output from the correlation value calculation unit 108.

The imaging means 105 is, for example, a CCD (char
and an area sensor camera that captures a two-dimensional area, and a line sensor camera that captures a one-dimensional area. Imaging means 10
Reference numeral 5 inputs a timing signal output from the timing signal generating means 104, performs imaging, and outputs an imaging signal. The difference between the case where the imaging unit 105 is an area sensor camera and the case where the imaging unit 105 is a line sensor camera is based on the difference between whether the imaging signal is a two-dimensional imaging signal or a one-dimensional imaging signal. Except for the difference, the handling of the two imaging signals has no essential difference in the present invention, and it is easy for a person skilled in the art to infer the other from the explanation of one. Therefore, in the following description, the case of a line sensor camera will be mainly described.

The image pickup means 105 (line sensor camera) picks up an image of a moving object and outputs an image pickup signal. A / D conversion means 106 is a line sensor camera 202 (imaging means 105)
Converts the output imaging signal into digital data. The buffer memory 107 stores the digital data as a line profile image.

FIG. 2 shows an example of the arrangement of a moving object and a line sensor camera for imaging the moving object. In FIG.
201 is a moving body, and 202 is a line sensor camera.
The arrow → indicates the transfer direction. In an example shown in FIG. 2, the moving body 201 includes a printing paper, a printed film,
It is a web (long sheet) such as a woven fabric. As shown in FIG. 2, the web 201 is transported in the direction indicated by the arrow.
The moving direction of the web 201 and the scanning direction of the line sensor camera are parallel to each other.

If the transport direction and the scanning direction are not parallel (the angle is 0), for example, in speed measurement, the measured speed is the direction cosine of the actual speed in the scanning direction. Therefore, when the line sensor camera is installed, accuracy according to the required accuracy is required. Alternatively, the measurement value is corrected by dividing by the direction cosine.

As described above, the line sensor camera 202 captures an image of a moving object and outputs a line profile image (imaging signal). The line profile image is converted into digital data and stored in the buffer memory 108.
The buffer memory 108 has a plurality of (at least two)
A line profile image (digital data) can be stored. Fig. 3 shows an example of a line profile image
Shown in In the line profile image shown in FIG. 3, the horizontal axis indicates pixels arranged on a straight line, and the vertical axis indicates the pixel value of each pixel. In FIG. 3, Line1 and Line2 are two line profile images (captured images) that are chronologically preceding and succeeding. Line 1 is a line profile image that is earlier in time series than Line 2. It can be seen from the shape of the line profile image that the position A1 in Line1 has moved to the position A2 in Line2.

The correspondence between the positions is determined by the correlation value calculating means 10.
8 can be calculated based on the correlation value calculated.
The correlation value calculation means 108 changes the relative position of the two line profile images (changes the corresponding pixels relatively) for predetermined two of the line profile images stored in the buffer memory 107, and calculates the correlation value. Is calculated.

For example, a line profile image Lin
It is assumed that e1 and Line2 are constituted by 512 pixels. 256 pixels near the center of the line profile image Line1 are used as a reference line. In addition, 256 256 pixels obtained by moving the 256 pixels near the center of the line profile image Line2 forward and backward by 128 pixels are used as corresponding lines. The correlation value calculation means 108 calculates a correlation value for each of the reference line and the 256 corresponding lines. In this case, 256 correlation values are obtained.

The correlation value calculating means 108 calculates a correlation value by, for example, the following equation (1). The correlation value calculated by the equation 1 matches the correlation coefficient and has a value from 0 to 1.

(Equation 1) Where: i; position (address) f (i); data line g (i) of reference line; data line Rj of corresponding line; correlation coefficient j; position n of data line of corresponding line; number of pixels of data line

Further, for example, the correlation value calculating means 108 calculates a correlation value by the following equation (2). The correlation value calculated by Expression 2 matches the inner product. Although it does not match the exact correlation coefficient, the calculation can be performed at high speed, and there is no problem in the normal use of the mobile measuring device.

(Equation 2) Where: i; position (address) f (i); data line of reference line g (i); data line of corresponding line Ij; inner product j; position of data line of corresponding line n; number of pixels of data line

The central processing means 103 inputs the 256 correlation values. Then, the relative position between the corresponding line giving the maximum correlation value and the reference line is calculated as the moving distance. For example, suppose that the maximum correlation value is obtained when j = 50 in Equation 1 or Equation 2 described above. Line2 is Li
That is, it has moved by a distance of 50 pixels with respect to ne1. For example, if the distance between pixels is 1
If it is 00 μm, the moving distance is 5000 μm (=
5 mm).

The imaging times T1 and L at which Line 1 was obtained
(T2−T1) is calculated from the imaging time T2 at which ine2 was obtained as the time interval between the two captured images Line1 and Line2 which are successive in time series. Then, the moving speed V of the moving body 201 is calculated by dividing the moving distance by the time interval. For example, if the time interval is 200μ
Suppose it is sec. The moving distance 5000 μm is divided by the time interval 200 μsec, and the moving speed V is 25 m
/ Sec. At this time, by setting a large time interval (T2−T1) between the captured images Line1 and Line2, the low-speed range can be set as the measurement range, and conversely, by setting it small, the high-speed range can be set. The area can be a measurement range.

The moving speed V described above is, of course, the moving speed V1 between the imaging times T1 and T2, the moving speed V2 between the imaging times T2 and T3, and the imaging times T3 and T3.
4, the moving speed V3 can be obtained in time series. The acceleration A (n) can be calculated from the moving speed V (n) obtained in this time series, where n is an integer value. That is, the central processing unit 103 calculates the acceleration A (n) by the following equation (3).

A (n) = (V (n + 1) -V (n)) /
(T (n + 1) -T (n))

The central processing means 103 calculates the cumulative moving distance by integrating all the moving distances in a predetermined time period in the time series. For example, the predetermined period is set to the photographing time T (i)
It is assumed that the period is between the shooting time T (i + n) and the shooting time T (i + n). Further, the photographing time T (i + j-1) and the photographing time T (i
+ J) is defined as L (j). At this time, the cumulative moving distance S can be calculated by the following equation (4).

(Equation 4) Where i, j, n: integer, j ≦ n S; cumulative moving distance L; moving distance

Another method for calculating the cumulative moving distance will be described. Since the line profile images are obtained in time series, the moving speed is also obtained in time series. That is, there is a moving speed V (j) corresponding to the photographing time T (j), where n is an integer. At this time, the moving distance L (j) is defined by the following equation (4). The central processing unit 103 calculates
By performing the calculation of Equation (3), the cumulative moving distance can be calculated.

L (j) = (T (j + 1) -T (j)) ×
((V (j) + V (j + 1)) / 2)

The data such as the moving distance, the moving speed, the cumulative moving distance, and the acceleration calculated by the central processing means 103 are output to the LED controller 109. The LED controller 109 converts any or all of the data into data in a format to be displayed on the LED panel 110 and outputs the data to the LED panel 110. The LED panel inputs the data and performs display in a visually recognizable form. Further, data such as the moving distance, the moving speed, and the cumulative moving distance calculated by the central processing unit 103 are output to the IO controller 102. The IO controller 102 transfers the data to an external device such as a data collection device, a control unit of a transfer device, or the like.

As described above, the imaging means 1 according to the present invention
The description has been made with reference to the configuration in which 05 is the line sensor camera 202. As is clear from the above description, the line sensor camera 202 captures an image using a one-dimensional image sensor to obtain a line profile image (the image sensor 10).
Because of 5), essentially only the one-dimensional movement amount of the moving object is measured. However, in general, the use of measuring the one-dimensional movement amount is extremely wide, and the application range is not narrow.

In order to measure the two-dimensional movement amount, it is sufficient to use two line sensor cameras so as to obtain line profile images in different directions. Further, as described first, the imaging unit 105 may be configured to be an area sensor camera that obtains a two-dimensional (in a normal sense) image. In the case of an area sensor camera, the calculation target of the correlation value is two-dimensional image data, but there is no essential difference. It is easy for a person skilled in the art to apply the two-dimensional case based on the one-dimensional description described above.

[0036]

According to the moving object measuring method according to the first aspect of the present invention, it is easy to set the operating condition, the restriction on the installation place is small, and the moving speed of the object is small.
Even when stationary, high-precision measurement can be performed. Further, according to the moving object measuring method according to the second aspect of the present invention, the moving speed can be calculated. Also,
According to the moving object measuring method according to the third aspect of the present invention, the accumulated moving distance can be calculated. Further, according to the moving object measuring method according to claim 4 of the present invention, one-dimensional movement (linear movement) can be measured at high speed. Further, according to the moving object measuring method according to claim 5 of the present invention, a correlation value as an inner product of vectors can be obtained at high speed.

According to the moving object measuring apparatus of the sixth aspect of the present invention, it is easy to set the operating conditions, the installation location is small, and even if the moving speed of the object is low, A moving object measurement device capable of performing high-accuracy measurement even when the measurement is performed is provided. Further, according to the moving object measuring device according to claim 7 of the present invention, the moving speed can be calculated. Further, according to the moving object measuring device according to claim 8 of the present invention, the accumulated moving distance can be calculated. Further, according to the moving object measuring device of the ninth aspect of the present invention, one-dimensional movement (linear movement) can be measured at high speed. Further, according to the moving object measuring device of the tenth aspect of the present invention, a correlation value as an inner product of vectors can be obtained at high speed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a configuration of a moving object measuring device according to the present invention.

FIG. 2 is a diagram illustrating an example of an arrangement of a moving object and a line sensor camera when imaging the moving object.

[Explanation of symbols]

 Reference Signs List 101 push button switch 102 I / O controller 103 central processing means 104 timing generation means 105 imaging means 106 A / D conversion means 107 buffer memory 108 correlation value calculation means 109 LED controller 110 LED panel

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[Procedure amendment]

[Submission date] October 18, 1999 (1999.10.
18)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Brief description of drawings

[Correction method] Change

[Correction contents]

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a configuration of a moving object measuring device according to the present invention.

FIG. 2 is a diagram illustrating an example of an arrangement of a moving object and a line sensor camera when imaging the moving object.

FIG. 3 is a diagram illustrating an example of a line profile image.

DESCRIPTION OF SYMBOLS 101 push button switch 102 I / O controller 103 central processing means 104 timing generation means 105 imaging means 106 A / D conversion means 107 buffer memory 108 correlation value calculation means 109 LED controller 110 LED panel

Claims (10)

[Claims] An imaging step of imaging a moving body and outputting a time-series captured image; a correlation value calculating step of calculating a correlation value by changing a relative position of two captured images preceding and succeeding in the time series; A moving distance extracting step of extracting, as a moving distance, a relative position at which the correlation value becomes a maximum. 2. The moving object measuring method according to claim 1, wherein
A moving object measuring method comprising a moving speed calculating step of calculating a moving speed by dividing the moving distance by a time interval between two captured images preceding and succeeding in the time series. 3. The moving object measuring method according to claim 1, further comprising a cumulative moving distance calculating step of calculating a cumulative moving distance by integrating all of the moving distances in a predetermined period in the time series. Mobile object measurement method. 4. The moving object measuring method according to claim 1, wherein the captured image is a line profile image obtained by performing one-dimensional imaging in a moving direction of the moving object. Mobile object measurement method. 5. The moving object measuring method according to claim 4,
The moving object measuring method according to claim 1, wherein the correlation value calculating step is a step of obtaining the correlation value as an inner product of a vector having each pixel value of two preceding and succeeding line profile images as components. 6. An image capturing means for capturing an image of a moving object and outputting a time-series captured image, a correlation value calculating means for calculating a correlation value by changing a relative position of two time-series captured images, and A moving-distance extracting unit that extracts, as a moving distance, a relative position at which the correlation value becomes a maximum. 7. The moving object measuring method according to claim 6, wherein
A moving object measuring device, comprising moving speed calculating means for calculating a moving speed by dividing the moving distance by a time interval between two captured images that are successive in the time series. 8. The moving object measuring method according to claim 6, further comprising a cumulative moving distance calculating means for calculating a cumulative moving distance by integrating all the moving distances of the predetermined period in the time series. Mobile object measuring device. 9. A moving object measuring apparatus according to claim 6, wherein said image pickup means is a line sensor camera which performs one-dimensional image pickup in a moving direction of said moving object and outputs a line profile image. A moving object measuring device, comprising: 10. The moving object measuring method according to claim 9, wherein the correlation value calculating means obtains the correlation value as an inner product of a vector having each pixel value of two line profile images preceding and succeeding the correlation value in time series. A moving object measuring device characterized by being means.