JP2021063780A - Object detection system and program for objection detection system - Google Patents

Abstract

To provide an object detection system capable of accurately measuring a floating amount of an object conveyed by a conveyance mechanism.SOLUTION: Disclosed is an object detection system for detecting an object which is carried on a transport mechanism and moves in a predetermined traveling direction. This system includes: an imaging device for imaging an area through which the object passes; a light source for irradiating the tip of the object with light in an imaging area of the imaging device; a shadow length calculation part of calculating a shadow length which is a length along the traveling direction of the shadow generated from the tip of the object based on an image captured by the imaging device; and a floating amount calculation part of calculating the floating amount of the tip of the object based on the calculate shadow length.SELECTED DRAWING: Figure 1

Description

The present invention relates to an object detection system that detects an object moving in a predetermined direction and a program for the object detection system.

As an object detection system, for example, a system that detects an object such as paper or film conveyed by a transfer mechanism such as a belt conveyor with a photoelectric sensor or the like and calculates its position and moving speed is known.

By the way, in this object detection system, the tip of the object to be conveyed may be lifted from the conveyor belt, and the position of the tip may not be calculated accurately. Therefore, in such an object detection system, there is a desire to measure the amount of floating of an object during transportation.

In response to such a request, for example, it is conceivable to apply a technique using a reflective optical sensor as disclosed in Patent Document 1. According to this technology, the light emitting unit irradiates an object with light, the reflected light is detected by the light receiving unit, and the fluctuation of the intensity of the reflected light is measured to know the fluctuation of the distance between the object and the sensor. be able to. It is considered that the floating amount of the transported object can be measured by this.

However, when a reflective optical sensor is used, the light intensity detected by the light receiving part varies depending on the material of the surface of the object and the angle of the raised surface, and the floating amount must be measured accurately. There is a problem that it is difficult.

JP-A-2018-150109

The present invention has been made in view of such a problem, and an object of the present invention is to provide an object detection system capable of accurately measuring the floating amount of an object transported by a transport mechanism.

That is, the object detection system according to the present invention detects an object that is mounted on a transport mechanism and moves in a predetermined traveling direction, and an image pickup device that captures an image of a region through which the object passes and an image pickup device of the image pickup device. A light source that irradiates a region with light from a predetermined direction, and a shadow length that is the length of a shadow generated from an edge of the object that is reflected in an image captured by the imaging device along the light irradiation direction. It is characterized by including a shadow length calculation unit for calculating the above, and a floating amount calculation unit for calculating the floating amount of the object based on the calculated shadow length.

With such a configuration, the amount of floating of the object is calculated based on the length of the shadow reflected in the captured image of the object, so that it is not affected by the material of the surface of the object or the angle of the floating surface. , The amount of floating can be measured. Therefore, the floating amount of the object can be measured more accurately than when the reflection type optical sensor is used.

The object detection system processes the captured image, detects each edge of the end of the object and the end of the shadow reflected in the captured image, and indicates the position of each of the detected edges. An edge detection unit that outputs object edge position data and shadow edge position data is further provided, and the shadow length calculation unit is based on the difference in edge position indicated by each of the output object edge position data and shadow edge position data. It is preferable to calculate the shadow length.
In such a case, the shadow length is calculated based on the detailed edge positions of the edge of the object and the edge of the shadow detected in the captured image, so that the shadow length is calculated more accurately. be able to. Further, since the position of the edge of the object is detected and the shadow length is calculated, the shadow length can be calculated more accurately even if the moving body is a transparent object such as a film. Then, by using the shadow length calculated more accurately in this way, the floating amount of the object can be measured more accurately.

As a specific embodiment of the object detection system, the floating amount calculation unit is based on the thickness of the object, the irradiation angle of light from the light source, and the shadow length calculated by the shadow length calculation unit. Examples thereof include those for calculating the floating amount of the end portion of the object.

In the object detection system, it is preferable that the light source irradiates the imaging region with parallel light.
In this way, regardless of the position of the object in the imaging region, if the floating amount of the end portion is the same, shadows of the same length can be generated. Therefore, the amount of floating of the object can be measured accurately regardless of the timing of imaging.

In the object detection system, the light source irradiates light in the traveling direction, and it is preferable that the floating amount calculation unit calculates the floating amount at the tip portion of the object along the traveling direction. ..
In such an object detection system, the tip of the transported object is detected and its position and moving speed are calculated. In this way, the amount of float at the tip of the object (that is, the front end in the traveling direction) is calculated. Is more useful because it can be calculated.

In the object detection system, the image pickup device has an area sensor in which a plurality of image pickup elements are laid in a vertical and horizontal matrix, and the float amount calculation unit has a plurality of points along a direction perpendicular to the traveling direction. It is preferable to calculate the floating amount of the object in.
With such a thing, it is possible to grasp the amount of deflection of the object along the direction orthogonal to the traveling direction.

Comparing the floating state and the non-floating state of the edge of the object, even if the actual position of the edge along the moving direction is the same, the edge position of the edge detected from the captured image is It will be different in the image coordinate system. Therefore, if the moving speed of the object is calculated by using the edge position of the end detected in the state where the end is raised as it is, the moving speed will include an error.
Therefore, it is preferable that the object detection system further includes an edge position correction unit that corrects the edge position of the end portion of the object indicated by the object edge position data according to the float amount calculated by the float amount calculation unit.
In this way, the edge position of the edge of the object can be corrected according to the amount of floating. Therefore, the detected edge position can be corrected to the position where the edge of the object is not floating, for example, to correct the position of the object. And the movement speed can be calculated more accurately.

As an embodiment in which the effect of the object detection system is remarkably exhibited, an object having a film shape, a sheet shape, or a plate shape can be mentioned.

Further, the object detection system program according to the present invention detects an object that is mounted on a transport mechanism and moves in a predetermined traveling direction, and includes an image pickup device that captures an image of a region through which the object passes and the image pickup device. A program for an object detection system including a light source that irradiates an imaging region with light from a predetermined direction, and the shadow of the shadow generated from the edge of the object reflected in the image captured by the imaging device. A function as a shadow length calculation unit that calculates the shadow length, which is the length along the irradiation direction, and a function as a floating amount calculation unit that calculates the floating amount of the object based on the calculated shadow length. It is characterized by letting the computer exert the above.

A program for such an object detection system can have the same effect as the above-mentioned object detection system.

According to the present invention as described above, it is possible to provide an object detection system capable of accurately measuring the floating amount of an object transported by the transport mechanism.

The perspective view which shows typically the structure of the object detection system in one Embodiment of this invention. The functional block diagram of the object detection system of the same embodiment. The figure which shows an example of the captured image processed by the object detection system of the same embodiment. The figure explaining the calculation of the float amount by the object detection system of the same embodiment. The graph which shows an example of the calculation result by the float amount calculation part of the same embodiment. The figure explaining the correction of the object edge position by the object detection system of the same embodiment. The figure explaining the calibration of the irradiation angle and the like by the object detection system of the same embodiment. The flowchart explaining the operation of the object detection system of the same embodiment.

Hereinafter, the object detection system 100 according to the embodiment of the present invention will be described with reference to the drawings.

The object detection system 100 according to the present embodiment detects the passage of an object O such as paper that is mounted on a transport mechanism M such as a belt conveyor and moves in a predetermined traveling direction. Specifically, as shown in FIG. 1, the object detection system 100 includes an imaging device 1 that captures a predetermined region (hereinafter, also referred to as an imaging region) R through which the object O passes, and an imaging region R of the imaging device 1. It includes a light source 2 that irradiates light, and an image processing device 3 that processes the image pickup device 1 by the image pickup device 1 to detect an object O. Each part will be described below. In the following description, the traveling direction of the object O (i.e., the feeding direction M) is parallel to the x-axis direction to a direction parallel to the transport mechanism M of the mounting surface M _{s (specifically} belt) The direction perpendicular to the x-axis direction is defined as the y-axis direction, and the direction orthogonal to the x-axis direction and the y-axis direction is defined as the z-axis direction.

The imaging device 1 images the imaging region R on the transport mechanism M at regular time intervals, and sequentially outputs the captured image data. Specifically, the image pickup device 1 includes an area sensor (for example, a 128 × 128 pixel CMOS image sensor) in which a plurality of image pickup elements are laid out in a vertical and horizontal matrix pattern, and an optical system arranged in front of the area sensor. It is equipped with 11. The imaging region R has a rectangular shape of about 2 to 20 mm square, and the two sets of opposite sides are set to be parallel to the x-axis direction and the y-axis direction, respectively. That is, the vertical and horizontal directions in which the plurality of image pickup devices are lined up are parallel to the x-axis direction and the y-axis direction. The optical system 11 preferably includes a lens having a deep depth of field. With such a thing, it is possible to reduce the out-of-focus due to the thickness of the object O and the height of the surface.

The light source 2 irradiates the object O passing through the imaging region R of the imaging device 1 with parallel light. Specifically, the light source 2 includes an LED device such as a white LED and a condensing mechanism such as a lens that condenses the light emitted from the LED device. More specifically the light source 2, for at least the distal end portion (or forward end portion in the traveling direction) O _t of the object O, and light is irradiated obliquely downward toward the traveling direction, placed in the transport mechanism M (specifically forward of the distal end portion O _t of the object O) on the surface M _s it is configured to project a shadow S of the object O of the tip O _t in. When viewed from the z-axis direction, the light emitted from the light source 2 is made parallel to the x-axis direction.

The image processing device 3 receives the captured image data output from the imaging device 1 and processes the captured image data to detect the object O passing through the imaging region R.

Then, in the object detection system 100 of the present embodiment, the image processing device 3 processes the acquired image data to calculate the length of the shadow S generated from _{the tip O t of the object O, and the calculated shadow.} It is configured to calculate the floating amount h of _{the tip O t} of the object O based on the length of S.

Physically speaking, the image processing device 3 is a general-purpose or dedicated computer provided with a CPU, a memory, an input / output interface, and the like, and the CPU and peripheral devices are made to cooperate according to a predetermined program stored in a predetermined area of the memory. As a result, as shown in FIG. 2, at least the functions as the edge detection unit 31, the shadow length calculation unit 32, the storage unit 33, and the floating amount calculation unit 34 are exhibited. Each functional part will be described below.

The edge detection unit 31 processes the captured image data received from the imaging device 1, and the tip O _t of the object O reflected in one captured image captured at the same timing and the shadow S generated from the object O. detecting the respective edges of the front end portion S _t. Then, the detected is a position of an edge of the object O of the tip O _t object edge position _{E о (x о, y о} ) and the object edge position data indicating a is the position of the edge of the tip portion S _t of the shadow S shadow edge position _{E s (x s, y s} ) to produce a shadow edge position data indicating the outputs these to Kagecho calculating section 32. In the present embodiment, as shown in FIG. 3, the object edge position E _о (x _о , y _о ) and the shadow edge position E _s (x _s , y _s ) are the upper left corners (in the traveling direction) of the image pickup apparatus 1. This is the rearmost position represented by the image coordinate system with the pixel center (leftmost in the traveling direction) as the origin (0,0).

Edge detecting unit 31 based on the gradient calculation of the brightness of the captured image P indicated by the captured image data, detects the respective tip O _t, edges of S _t of the object O and the shadow S. At this time, a smoothing process (moving average, Gaussian), a filter process such as a median, a Pruwitt filter, a Sobel filter, or a subpixel process may be performed.

Edge detecting unit 31 of the present embodiment, in a plurality of positions along the y-axis direction, each of the distal end portion O _t of the object O and shadow _S, it is configured to detect an edge of S _t. Specifically, as shown in FIG. 3, a plurality of edge detection lines L _{1 to} L _{7 that} are parallel to the x-axis direction and have different y-coordinates are set in the target region. Edge detection unit 31, each edge detection lines _L 1 ~L _7, detects the edge position of each of the tip _O t, _{S t} of the object O and shadow S.

The shadow length calculation unit 32 receives the object edge position data and the shadow edge position data, and calculates the shadow length, which is the length of the shadow S along the x-axis direction, based on these. Kagecho calculator 32, Kagecho of the difference between the x-coordinate x _o x coordinate x _s and the object edge position E _o of the shadow edge positions E _s visible on captured single captured image captured at the same timing 1 is calculated. Specifically, the shadow length l is calculated by performing the calculation shown in the following equation (1) or an operation equivalent thereto.

l = (x _s −x _о ) × r (1)
Here, l is Kagecho of (mm), x _o is the x-coordinate position of the object O of the tip _{O t} (pix), _{x s} is the x-coordinate position of the tip portion _{S t} of the shadow S (pix), r is It is the pixel resolution (mm / pix) with respect to the imaging field of view.

Here, the shadow length calculation unit 32 is configured to calculate the shadow length at a plurality of positions along the y-axis direction. Specifically, on the basis of the detected object edge position and the shadow edge positions for each edge detection lines L ₁ ~L _7, calculates the Kagecho of each edge detection lines L ₁ ~L _7.

The storage unit 33 is set in a predetermined area of the memory, and has _{thickness data indicating the thickness t} of the tip O t of the object O and irradiation angle data indicating the irradiation angle θ of the light from the light source 2 with respect to the object O. And the distance data indicating the distance z from the main point of the optical system 11 to the transport surface of the transport mechanism M are stored.

_{The thickness data indicating the thickness t} of the tip O t of the object O, the distance data indicating the distance z from the principal point of the optical system 11 to the transport surface of the transport mechanism M, and the irradiation angle data indicating the irradiation angle θ are provided by the user. It is preset and stored.

Floating amount calculating unit 34 calculates the floating amount h of the object O of the tip O _t based on Kagecho of l to Kagecho calculator 32 has calculated. The floating amount calculation unit 34 refers to the thickness t stored in the storage unit 33 and the irradiation angle θ, multiplies the shadow length l by the tangent of the irradiation angle θ, and subtracts the thickness t from this, as shown in FIG. Calculate with. Specifically, the floating amount h of _{the tip O t} of the object O is calculated by performing the calculation shown in the following equation (2) or an operation equivalent thereto.

h = l × tan θ−t (2)
Here, h is floating amount (mm), θ is the irradiation angle of the light source 2 (°), t is the thickness of the object O of the tip _{O t} (mm).

The float amount calculation unit 34 calculates the float amount h at a plurality of positions along the y-axis direction. Specifically, based on of Kagecho calculated for each edge detection lines L ₁ ~L _7, floating amount of the plurality of per edge detection lines L ₁ ~L _7, of the object O tip O _t h Is calculated. Then, as shown in FIG. 5, information on the float amount h at a plurality of positions along the calculated y-axis direction is output to the display, and serial communication, pulse output, or the like is performed to another device.

The image processing device 3 of the present embodiment is configured to further exhibit the function as the edge position correction unit 35. The edge position correction unit 35 corrects the object edge position E _о (x _о , y _о ) calculated by the edge detection unit 31 according to the float amount h calculated by the float calculation unit 34, and the corrected object. _{The corrected object edge position E о} '(x _о ', y _о '), which is the edge position, is calculated. The corrected object edge position _{E о '(x о',} y о ') is in assuming a floating amount h of the object O of the tip O _t zero, the edge position of the object O of the tip O _t means. _{Specifically, the edge position correction unit 35 calculates the corrected object edge position E о'by} performing the operations shown in the following equations (3) and (4), or an operation equivalent thereto.

x _о '= (x _о −x _c ) × {z'/ (z−t)) + x _c (3)
z'= z- (t + h) (4)
Here, as shown in FIG. 6, z is the distance (mm) from the principal point of the optical system 11 to the transport surface of the transport mechanism M, and z'is the vertical distance (mm) from the principal point of the optical system 11 to the object O. ), t is the thickness of the object O of the tip _{O t} (mm), _{x c} is the x coordinate position of the center of the image pickup apparatus 1 (pix), floating amount of h is tip _{O t} (mm).

The edge position correction unit 35 of the present embodiment calculates the _{corrected object edge position E о'at a plurality of positions along the y-axis direction. Specifically, the corrected object edge position E о'at} a plurality of positions along the y-axis direction is calculated based on the object edge position E _о and the floating amount h calculated for each of the edge detection lines L _{1 to} L _7. To do. Then, for example, serial communication or pulse output is performed so that the calculated information on the corrected object edge position E _о'can be output to the display or taken into another device for control.

The image processing device 3 of the present embodiment further includes a calibration unit 36 that calibrates the irradiation angle θ and the distance z stored in the storage unit 33 based on the corrected object edge position calculated by the edge position correction unit 35. ing.

Specifically calibration unit 36, as shown in FIG. 7, is obtained from the calibration image captured placed within the imaging region R by standard object P thickness t _r is known as brooding its tip Based on the information, the irradiation angle θ _c after calibration is calculated. More specifically, the calibration unit 36 is obtained by performing the above processing on the calibration image by the edge detection unit 31, the shadow length calculation unit 32, the floating amount calculation unit 34, and the edge position correction unit 35. , The shadow edge position x _rs of the tip of the standard object and the corrected edge position x _rо'of the tip of the standard object are used to perform the calculation shown in the following equation (5) or an equivalent calculation. By doing so, the irradiation angle θ _c after calibration is calculated. Then, the calculated irradiation angle θ _c is stored in the storage unit 33.

_{θ c = arctan [t r /} {(x rs -x rо ') × r}] (5)
Here, t _r is the standard object of the tip portion of the thickness (mm), x _rs is the x-coordinate position of the distal end portion of the shadow resulting from the standard object _(pix), x rо 'is x after the correction of the front end portion of a standard object The coordinate position (pix) and r are pixel resolutions (mm / pix) with respect to the imaging field of view.

Further, as shown in FIG. 7, the calibration unit 36 places a standard object having a known length W along the x-axis direction in the imaging region R so that the front end portion and the rear end portion do not float. based on the information obtained from the calibration image taken as both the tip and the rear end portion objects appear, to calculate the distance z _c after calibration. More specifically, the calibration unit 36 is obtained by performing the above-mentioned processing by the edge detection unit 31, the shadow length calculation unit 32, the floating amount calculation unit 34, and the edge position correction unit 35 on the calibration image. , corrected the tip of a standard object 'and the edge position after the correction of the rear end portion of a standard object x _rp' edge position x _Ro by using the arithmetic shown in the following equation (6), or as this by an even operation, to calculate the distance z _c after calibration. Then, the calculated distance z _c is stored in the storage unit 33.

_{z c = (W × 128)} / {(x rp '-x rо') × 2 × tan (θ 2/2)} (6)
Here, W is the x-axis direction to the length along the standard object _(mm), x rо 'is the x-coordinate position after the correction of the tip edge of the standard object (pix), x _rp' is the standard object rear The x-coordinate position (pix) and θ ₂ after the correction of the part edge are the viewing angles (°) of the image pickup apparatus 1.

The floating amount calculating section 34 and the edge position correcting unit 35 and, using the irradiation angle theta _c and the distance z _c after calibration calculated by the calibration unit 36, the correction of the floating amount h and the tip O _t of the object O It may be configured to calculate the later edge position E _о'.

Next, the operation of the object detection system 100 having such a configuration will be described with reference to the flowchart of FIG.

First, the transport mechanism M moves the object O in the traveling direction. _{Then, the tip O t} of the object O that has entered the imaging region R of the imaging device 1 is imaged (step S1). Processing the imaging apparatus 1, the plurality of points along the y-axis direction, the edge position of the object O of the tip O _t, detects the edge position of the front end portion S _t of the shadow S (step S2). From the difference in each edge position, the length of the shadow S at a plurality of points along the y-axis direction is calculated (step S3). _{Then, using the calculated length of the shadow S, the floating amount h of the tip O t} of the object O at a plurality of points along the y-axis direction is calculated and output (step S4). _{Next, based on the calculated float amount h, the edge position of the tip O t} of the object O at a plurality of points along the y-axis direction is corrected (step S5). Then, the corrected object edge position, which is the edge position of the corrected object O, is output.

According to the object detection system 100 of the present embodiment configured in this way, the floating amount h of the object O is calculated based on the length of the shadow S reflected on the image pickup device 1 in which the object O is imaged. The floating amount h can be measured without being affected by the surface material of the surface and the angle of the floating surface. Therefore, the floating amount h of the object O can be measured more accurately than when a reflection type optical sensor is used.

Further, the object detection system 100 of the present embodiment calculates the shadow length based on the detailed edge positions of the end of the object O and the end of the shadow S detected in the image pickup apparatus 1 by the edge detection unit 31. Therefore, the shadow length can be calculated more accurately. Then, by using the shadow length calculated accurately in this way, the floating amount h of the object O can be measured with extremely high accuracy.

Further, since the object detection system 100 of the present embodiment includes an edge position correction unit 35 that corrects the calculated edge position of the end portion of the object O according to the floating amount h, the object O can be used by using the corrected edge position. The position and moving speed of the can be calculated more accurately.

Further, the object detection system 100 of the present embodiment includes a calibration unit 36 that calibrates the irradiation angle θ of the light of the light source 2 and the distance z from the main point of the optical system 11 to the transport surface of the transport mechanism M. By using the irradiation angle θ _c after calibration and the distance z _c after calibration, the floating amount h of the object O and the corrected edge position E _{о'of the tip O t} can be calculated accurately.

The present invention is not limited to the above embodiment.

In the above embodiment, the image pickup apparatus 1 provided with an area sensor is used, but the present invention is not limited to this. In another embodiment, the image pickup apparatus 1 may be a line camera including a line sensor. By providing such a line camera so that the image sensor is along the x-axis direction, it is possible to calculate the floating amount h of _{the tip O t of the object O.}

But was to calculate the floating amount h of the object O of the tip O _t in the embodiment, may be configured to calculate the floating amount h of the side end portion of the object O is not limited thereto. In this case, the light from the light source 2 is irradiated along the y-axis direction, and the length of the shadow S along the y-axis direction is calculated from the side end portion of the object O to obtain the floating amount h of the side end portion. It may be calculated.

Each of the above-mentioned functional parts may be realized by a reconfigurable hardware circuit such as FPGA (Field Programmable Gate Array).

In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

100 ・ ・ ・ Object detection system 1 ・ ・ ・ Light source 2 ・ ・ ・ Imaging device 31 ・ ・ ・ Edge detection unit 32 ・ ・ ・ Shadow length calculation unit 34 ・ ・ ・ Float amount calculation unit 35 ・ ・ ・ Edge position correction unit

Claims (9)

It detects an object that is mounted on a transport mechanism and moves in a predetermined direction of travel.
An imaging device that images the area through which the object passes, and
A light source that irradiates the imaging region of the imaging apparatus with light from a predetermined direction,
A shadow length calculation unit that calculates a shadow length that is the length of a shadow generated from an edge of the object along the irradiation direction of the light, which is reflected in an image captured by the image pickup device.
An object detection system including a floating amount calculation unit that calculates a floating amount of the object based on the calculated shadow length. The captured image is processed to detect the edges of the edge of the object and the edge of the shadow reflected in the captured image, and the object edge position data and the shadow indicating the positions of the detected edges. It also has an edge detection unit that outputs edge position data.
The object detection system according to claim 1, wherein the shadow length calculation unit calculates the shadow length from the difference between the output edge positions of the object edge position data and the shadow edge position data. The floating amount calculation unit calculates the floating amount of the end portion of the object based on the thickness of the object, the irradiation angle of the light from the light source, and the shadow length calculated by the shadow length calculating unit. The object detection system according to claim 1 or 2. The object detection system according to any one of claims 1 to 3, wherein the light source irradiates the imaging region with parallel light. The light source irradiates light in the traveling direction.
The object detection system according to any one of claims 1 to 4, wherein the floating amount calculating unit calculates a floating amount at a tip portion of the object along the traveling direction. The image pickup device has an area sensor in which a plurality of image pickup elements are laid in a vertical and horizontal matrix.
The object detection system according to any one of claims 1 to 5, wherein the floating amount calculation unit calculates the floating amount of the object at a plurality of points along a direction perpendicular to the traveling direction. Claim 2 or claim 2 which further includes an edge position correction unit that corrects the edge position of the end portion of the object indicated by the object edge position data according to the floating amount calculated by the floating amount calculation unit. Item 3. The object detection system according to any one of Items 3 to 6. The object detection system according to any one of claims 1 to 7, wherein the object is in the form of a film, a sheet, or a plate. It detects an object that is mounted on a transport mechanism and moves in a predetermined traveling direction, and irradiates an imaging device that images an area through which the object passes and an imaging area of the imaging device with light from a predetermined direction. A program of an object detection system equipped with a light source
A function as a shadow length calculation unit that calculates a shadow length that is the length of a shadow generated from an edge of the object along the irradiation direction of the light, which is reflected in an image captured by the image pickup device.
A program of an object detection system characterized in that a computer exerts a function as a float amount calculation unit that calculates a float amount of the object based on the calculated shadow length.

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