JPH06180279A - Discriminating method and device for particulate matter - Google Patents

Abstract

PURPOSE:To raise discrimination precision and to enable non-contact and objective discrimination by Fourier-transforming the picture data obtained by sensing an image of particulate matter for obtaining frequency distribution, so that average frequency is calculated from this frequency. CONSTITUTION:A concrete aggregate 1 is subjected to image sensing while transported on a transportation equipment 2 such as a belt-conveyor by an image sensing means 3 such as a CCD camera. During image sensing, it is caught in a specified view field, orthogonal to advancement direction, from above the transportation equipment 2, and the output signal is converted into picture data by a picture processing means 4, then inputted in a computer 5. In the computer 5, by Fourier-transforming the irregular signal sequence of special picture data obtained by the image sensing means 3, frequency distribution of the aggregate 1 is obtained. The computer 5 also calculates an average frequency from the frequency distribution, and, by outputting the value on a display device 6, the aggregate is objectively discriminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for discriminating granular materials, particularly for concrete aggregates.

[0002]

2. Description of the Related Art Aggregates for concrete are classified into fine aggregate and coarse aggregate according to the particle size at a ready-mixed concrete plant, a concrete product manufacturing plant, etc. The required amount of fine aggregate and coarse aggregate that have been taken out are mixed with cement and the like, and the mixture is provided for the next step. Here, the aggregate during transfer needs to be constantly monitored whether it is a fine aggregate or a coarse aggregate. That is, the aggregate must be correctly identified in terms of equipment, process and quality.

Conventionally, as a means for discriminating aggregate for concrete, a tongue-shaped pickup is arranged on a belt conveyor to which the aggregate is transferred, and the aggregate is discriminated by vibration when the aggregate collides with the pickup. There is. This is a stone,
If the particle size is large like gravel, the tongue-shaped pickup vibrates greatly, and if the particle size is small like sand,
Since the pickup does not vibrate so much, the magnitude of the vibration is converted into an electric signal to determine the particle size.

[0004]

DISCLOSURE OF THE INVENTION In the discrimination of aggregates by the vibration of such a contact type pickup, how aggregates are piled up, for example, sand (fine aggregates) is wavy,
When the top surface of a stone (coarse aggregate) is piled up flat, the magnitude of vibration does not necessarily correspond to the particle size of the aggregate, and it may be difficult to identify the aggregate. Further, there is a similar problem depending on the dry state of the aggregate, that is, whether the aggregate is dry or wet, and as a result, the determination accuracy tends to be low, and the labor of the supervisor cannot be reduced. .

An object of the present invention is to provide a non-contact type granular material discriminating method and apparatus which have a very good discriminating accuracy and can be objectively discriminated.

[0006]

In order to achieve the above-mentioned object, a method of discriminating granular objects according to the present invention is such that the image data of the granular objects is Fourier transformed to obtain a frequency distribution, and an average is calculated from the frequency distribution. It is characterized by calculating the frequency.

Further, the granular object discriminating apparatus of the present invention is such that the granular object imaging means, the image processing means connected to the imaging means, and the operation including the Fourier transform of the image data connected to the image processing means. It is characterized in that a computer having a processing means is provided.

[0008]

According to the present invention, the particulate matter is picked up by the image pickup means.
It is captured in a non-contact manner, and this is converted into image data, and the frequency distribution is obtained by Fourier transforming this image data. Although it is not possible to objectively judge the granular material only by the irregular signal sequence of the spatial image data captured by the image pickup means, the frequency distribution obtained by the Fourier transform is irrespective of how the granular material is stacked or the dry state. No, it corresponds to the particle size of the granular material. In other words, coarse aggregate with a large grain size has many low frequency components, and fine aggregate with a small grain size has many high frequency components. Can be done extremely accurately.

[0009]

Embodiments of the present invention will be described below with reference to the accompanying drawings. The aggregate 1 for concrete is picked up by an image pickup means 3 such as a CCD camera while being transported on a transporting machine 2 such as a belt conveyor. The image is picked up from above the transportation machine 2 in a predetermined visual field in the lateral direction of travel, and the output signal is converted into image data by the image processing means 4 as shown in FIG. In FIG. 2, the horizontal axis represents the imaging field of view, and the vertical axis represents the brightness of image gradation. This image data is input to the computer 5 and subjected to the arithmetic processing described later. That is, the frequency distribution of the aggregate 1 shown in FIG. 3 is obtained by Fourier-transforming the irregular signal sequence of the spatial image data captured by the image pickup means 3 by the computer 5. Further, the computer 5 calculates the average frequency from this frequency distribution and outputs this value to the display device 6, whereby the aggregate can be objectively discriminated.

It is also possible to store a preset reference value in the computer 5, compare this reference value with the average frequency, and display the comparison result on the display device 6.

As the average frequency of the frequency distribution, the median value or the average value of the plurality of average frequencies obtained by imaging the aggregate a plurality of times is displayed on the display device 6 to improve the accuracy of the aggregate determination. desirable.

Next, sand (fine aggregate) having a particle size of about 2 mm,
An example of determining a stone (coarse aggregate) having a particle size of about 20 mm will be described.
225m horizontally on the aggregate with CCD camera
The image was taken in the visual field of m. Using a general-purpose image processing device, the image data was captured as 512 × 480 dots and 256-gradation image data (see FIG. 2). I802 image data
The frequency distribution (see FIG. 3) was obtained by performing Fourier transform on a computer of 86 + numerical operation processor and 8 MHz. The average value obtained from Equation 1 from the frequency and amplitude in the frequency distribution was taken as the average frequency. 2 and 3 show an example of a stone (coarse aggregate) having a particle diameter of about 20 mm.

[0013]

[Equation 1]

In the above formula, f is frequency and m is amplitude. In order to find the average frequency, in order to exclude low-frequency components for changes in the cycle longer than the size of stone (coarse aggregate) and high-frequency components for the period shorter than the size of sand (fine aggregate), Frequency 1 from 5 (45 mm)
The average value calculation range was up to 55 (1.5 mm).

The above operation was repeated 50 times, and the median value of 50 average frequencies was used as the discriminant value of the aggregate. When the aggregate is dry, the discriminant value is 71 for stone (coarse aggregate) and 9 for sand (fine aggregate).
1 and the aggregate is wet, the stone (coarse aggregate) is 7
9, and the sand (fine aggregate) was 88. Therefore, by setting 85 as the reference value in advance and storing it in the computer and displaying it on the display device in comparison with the determination value, it was possible to objectively and extremely accurately determine the aggregate.

Further, the discriminant value of the aggregate differs depending on whether the aggregate is stacked flatly or piled, and whether the lighting method is upper room light or oblique light from the side. Was not particularly recognized.

Although the above has mainly described the determination of the aggregate for concrete, it goes without saying that the present invention can be applied not only to the aggregate but also to the determination of various granular materials.

[0018]

As described above, according to the present invention, it is possible to objectively discriminate a granular material with high precision and with high accuracy.
The labor of the observer at the time of discrimination can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of image processing data.

FIG. 3 is a diagram showing an example of Fourier transform of image processing data.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete aggregate 2 Transport machine 3 Imaging means 4 Image processing means 5 Computer 6 Display device

Claims (4)

[Claims] 1. A method of discriminating a granular object, characterized in that image data of an image of a granular object is Fourier transformed to obtain a frequency distribution, and an average frequency is calculated from the frequency distribution. 2. The method for determining a granular material according to claim 1, wherein the granular material is an aggregate for concrete transferred on a transportation machine. 3. A computer having an image pickup means for the granular material, an image processing means connected to the image pickup means, and an arithmetic processing means connected to the image processing means and including a Fourier transform of image data. A device for discriminating granular objects. 4. The granular material discriminating apparatus according to claim 3, wherein the granular material is aggregate for concrete transferred on a transport machine.