JP7158540B1 - Conveyed object detection system - Google Patents

Abstract

A transported object detection system capable of detecting a moving direction of a transported object while acquiring tag information of the transported object having an RFID tag is provided. A conveyed object detection system 1 includes a LiDAR sensor 10, an RFID reader 12, and a controller. The LiDAR sensor 10 includes a laser emitting unit that emits a laser beam, a scanning unit that continuously changes the irradiation direction of the laser beam to scan the space including the predetermined detection area with the laser beam, and a laser beam. It has a light receiving portion that receives reflected light, and detects the position of the transported object O within the detection area C based on the reflected light. The controller 14 determines the moving direction of the transported object O based on the change in the position of the transported object O detected by the LiDAR sensor 10, and the information of the RFID tag P of the transported object O read by the RFID reader 12 and the moving direction. Associate. [Selection drawing] Fig. 1

Description

TECHNICAL FIELD The present invention relates to a conveyed object detection system, and more particularly to a conveyed object detection system for detecting a conveyed object having an RFID (Radio Frequency Identifier) tag.

For example, in order to manage the movement of goods in a factory and the receipt and delivery of goods in a warehouse, an RFID tag containing information on the goods is attached to the goods and passed through a predetermined area. By reading the information of the RFID tag with an RFID reader at the time of transportation, it is possible to detect which conveyed article has passed through the area. In cases where the direction of movement of goods in a factory is fixed, or in cases where goods have separate entrances and exits in warehouses, etc., the direction in which the goods pass is known in advance, so the direction of movement of the goods can be specified. There is no need to do so, and the goods to be conveyed can be managed simply by reading the information on the RFID tag with the RFID reader. However, in the case where the moving direction of the goods is not predetermined, such as when the passage for entering and leaving the warehouse is common, simply reading the information of the RFID tag with the RFID reader does not allow the goods to be transported. In some cases, it is not possible to detect the direction in which the goods have passed through the area, making it impossible to adequately manage the goods to be conveyed.

In order to solve such a problem, for example, in Patent Document 1, two RFID antennas are installed separately so as not to interfere with each other, and the two RFID antennas detect the RFID tag in time series, and the transported object is detected. It is determined from which RFID antenna side the robot has moved to which RFID antenna side.

JP-A-2019-8678

However, in order not to interfere with each other, the two RFID antennas must be placed at relatively large distances, and a large area is required to detect the carried object. This limits where it can be installed.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a conveyed object detection system for detecting a conveyed object having an RFID tag, which can solve the above-described problems in the prior art.

That is, the present invention
A conveyed object detection system for detecting a conveyed object having an RFID tag, comprising:
a laser emitting unit for emitting a laser beam, a scanning unit for scanning a space including a predetermined detection area with the laser beam by continuously changing the irradiation direction of the laser beam, and reflected light of the laser beam. and a LiDAR sensor for detecting the position of a transported object within the detection area based on the reflected light;
an RFID reader that reads information on an RFID tag within the detection area;
a computing unit that determines the moving direction of the transported object based on the change in the position of the transported object detected by the LiDAR sensor, and associates information on the RFID tag of the transported object read by the RFID reader with the moving direction; ,
A conveyed object detection system comprising:

In the transported object detection system, the moving direction of the transported object is detected using the LiDAR sensor, and information on the RFID tag attached to the transported object is read by the RFID reader to determine what kind of transported object is which. It becomes possible to detect whether the sheet is conveyed in the direction. In addition, since the conveyed object detection system does not have the problem of mutual interference between the antennas unlike the conventional system using two RFID antennas, it can be applied in a relatively narrow space.

Further, the RFID tag can be read by the RFID reader while the LiDAR sensor is detecting that there is a transported object within the detection area. This makes it possible to limit the period during which reading is performed by the RFID reader.

Furthermore, the detection area includes a direction determination area located on one side in a direction along the assumed flow line of the conveyed product,
The computing unit determines that the conveyed article is in the detection area and that the conveyed article is in the direction determination area within the detection area, and determines that the conveyed article is in the direction determination area within the detection area. Based on this, the moving direction can be identified.

In particular,
the orientation determination region is positioned adjacent to the one side boundary of the sensing region;
The computing unit detects that the conveyed object is in the direction at a first point in time after a first time since the conveyed object enters the detection area and at a second point in time a second time before the conveyed object leaves the detection area. It is determined whether or not the conveyed object is in the determination area, and if the conveyed article is not in the direction determination area at the first time point but is in the direction determination area at the second time point, the moving direction is directed to the one side. If the transported object is in the direction determination area at the first time point and is not in the direction determination area at the second time point, the moving direction is the opposite direction to the first direction. It can be determined that there are two directions.

Alternatively, the computing unit determines a first elapsed time from when the conveyed article enters the detection area until it enters the direction determination area, and the detection area after the conveyed article exits the direction determination area. comparing with a second elapsed time until exiting, and when the first elapsed time is longer than the second elapsed time, determining that the moving direction is the first direction toward the one side; When the first elapsed time is shorter than the second elapsed time, it can be determined that the movement direction is the second direction opposite to the first direction.

Furthermore,
the detection area includes a plurality of direction determination areas,
The computing unit determines whether the conveyed article is in the detection area and in which direction determination area the conveyed article is within the detection area, and determines how the conveyed article is positioned in the plurality of direction determination areas. The direction of movement can be identified by determining whether or not they have passed in the correct order.

In this case
The plurality of direction determination areas include a direction determination area located adjacent to a boundary of the detection area on one side of one or more flow lines assumed for the conveyed article, and the detection area on the other side. and at least an orientation determination region located adjacent to the boundary of
The computing unit determines the direction of the conveyed article at a first time point after a first hour after the conveyed article enters the detection area and at a second time point after a second time period before the conveyed article leaves the detection area. It is determined whether or not the transported object is in the determination area, and it is determined that the moving direction of the transported object is in the direction from the direction determination area where it was located at the first time point toward the direction determination area where it was located at the second time point. can be

By setting a plurality of direction determination regions, it is possible to identify the moving direction of the conveyed article even when it is assumed that the conveyed article moves more complicatedly along a plurality of flow lines.

An embodiment of a transported object detection system according to the present invention will be described below with reference to the accompanying drawings.

It is a figure which shows the conveyed object detection system based on one Embodiment of this invention. 2 is a functional block diagram of the conveyed object detection system of FIG. 1; FIG. 2 is a diagram showing the configuration of a LiDAR sensor of the conveyed object detection system of FIG. 1; FIG. FIG. 10 is a diagram showing a time chart of movement direction detection by the controller when a conveyed product moves in the first direction; FIG. 10 is a diagram showing a time chart of movement direction detection by the controller when the conveyed product moves in the second direction; FIG. 10 is a diagram showing a time chart of movement direction detection when a conveyed product moves in the first direction, according to another method; FIG. 11 is a diagram showing a time chart of moving direction detection when the conveyed product moves in the second direction according to another method; FIG. 4 is a diagram showing a conveyed object detection system in which a plurality of direction determination areas are set within a detection area; FIG. 9 is a diagram showing a time chart of movement direction detection when a conveyed article moves in a first direction in the conveyed article detection system of FIG. 8; FIG. 9 is a diagram showing a time chart of movement direction detection when a conveyed article moves in a second direction in the conveyed article detection system of FIG. 8; It is a figure which shows the state which applied the conveyed object detection system to the T-junction path. 12 is a diagram showing a time chart of moving direction detection by a controller in the conveyed object detection system of FIG. 11; FIG.

As shown in FIGS. 1 and 2, a transported object detection system 1 according to an embodiment of the present invention includes a LiDAR (Light Detection And Ranging) sensor 10 for detecting a transported object O passing through a passage A; An RFID reader 12 for reading information on an RFID tag P attached to an object O, and a controller (calculation unit) 14 connected to the LiDAR sensor 10 and the RFID reader 12 are provided.

As shown in FIG. 3, the LiDAR sensor 10 includes a laser emitting unit 20 that emits a pulsed laser beam L for measurement, and a laser emitting unit 20 that reflects the laser beam L and scans the inside of the external space. and a light receiving unit 24 for receiving the reflected light R of the laser light L striking an object in space. The scanning unit 22 has a rotationally driven turntable 26 , a mirror 28 mounted thereon, and an encoder 30 for detecting the rotational position of the turntable 26 . The mirror 28 is rotationally driven together with the turntable 26 to continuously change the irradiation direction of the reflected laser light L within the horizontal plane. As a result, the laser light L irradiated into the external space is scanned in a fan shape as shown in FIG. When the laser light L hits an object in the external space, the laser light L is reflected, and part of the reflected light R returns into the LiDAR sensor 10 and is focused on the light receiving section 24 via the mirror 28 . The LiDAR sensor 10 measures the distance to the object irradiated with the laser light L based on the time from when the laser emitting unit 20 emits the laser light L to when the light receiving unit 24 receives the reflected light R. , the direction of the object is specified by specifying the direction in which the laser beam L is emitted from the rotational position of the scanning unit 22 at that time. Two-dimensional point cloud data indicating the position of an object on a horizontal plane in the space is obtained by performing the measurement while scanning the space with the laser light L. LiDAR sensor 10 transmits this point cloud data to controller 14 .

Based on the point cloud data received from the LiDAR sensor 10, the controller 14 identifies the position of the article O passing through the passage A and determines its movement direction. Specifically, the controller 14 sets a predetermined detection area C (FIG. 1) within the area B irradiated with the laser beam L, and detects the entry of the article O into the detection area C as point cloud data. Judging from When it is detected that the article O has entered the detection area C, the first flag is turned ON in the control program of the controller 14, as shown in FIGS. The controller 14 further sets a direction determination region D located on one side of the detection region C in the direction along the assumed flow line M of the transported product O, and the transported product O is set in this direction determination region D. Intrusion is determined from point cloud data. In this embodiment, it is assumed that the conveyed goods O move along the passage A extending in the vertical direction in FIG. It is set on the lower side within the detection area C. When it is detected that the transported article O has entered the direction determination area D, the second flag is turned ON as shown in FIGS. When the article to be conveyed O leaves the detection area C and the direction determination area D, the first flag and the second flag are turned OFF. When both the first flag and the second flag are turned off, the controller 14 sets the state of the second flag at the first time point T1 after the first time after the first flag is turned on, and the second flag is turned off. and the state of the second flag at the second time point T2, which is the second time before.

When the article to be conveyed O passes through the detection area C downward as viewed in the figure, the second flag is OFF at the first time T1 and the second flag is OFF at the second time T2, as shown in FIG. is ON. Further, when the article O passes through the passage A upward as viewed in the drawing, the second flag is ON at the first time T1, and the second flag is ON at the second time T2, as shown in FIG. The second flag is OFF. The controller 14 checks the state of the second flag at the first time point T1 and the second time point T2, and if the second flag is OFF at the first time point T1 and is ON at the second time point T2 ( In FIG. 4), it is determined that the moving direction of the goods O is the first downward direction as seen in the figure, the second flag is ON at the first time point T1, and the second flag is OFF at the second time point T2. (FIG. 5), it is determined that the movement direction of the article O is the second upward direction opposite to the first direction. If the state of the second flag is the same at the first time point T1 and the second time point T2, it is assumed that the conveyed article O has returned in the middle, and the detection area is shifted from one side to the other side. It is assumed that it has not passed, so the controller issues an error signal to indicate so. In this manner, the controller 14 identifies the moving direction of the article O based on the timing at which the article O passes through the direction determination area D. FIG.

Further, the controller 14 turns on the tag read signal when the first flag is turned on. The tag read signal is transmitted to the RFID reader 12, and the RFID reader 12 that has received the signal starts reading the RFID tag P. FIG. The controller 14 turns off the tag read signal when the first flag turns off. When the tag read signal is turned off, the RFID reader 12 finishes reading the RFID tag P and transmits the information of the read RFID tag P to the controller 14 . The controller 14 associates and stores the moving direction of the transported article O detected as described above and the information of the RFID tag. Note that the controller 14 may transmit the moving direction of the transported article O and the information of the RFID tag to another external device.

The controller 14 obtains the size and shape of an object that has entered the detection area C from the point cloud data received from the LiDAR sensor 10, and determines whether the object is the object O to be detected. there is When the controller 14 determines that the object detected within the detection area C is not the object to be conveyed O, it does not turn on the first flag. As a result, for example, when a person enters the detection area, it is possible to prevent the object from being erroneously detected as being the object O to be conveyed.

The controller 14 can also specify the moving direction of the transported article O as follows. That is, as shown in FIGS. 6 and 7, a first elapsed time U1 from when the first flag is turned ON to when the second flag is turned ON, and a first elapsed time U1 after the second flag is turned OFF. The first elapsed time U1 and the second elapsed time U2 are calculated, and the first elapsed time U1 is compared with the second elapsed time U2. 6), and if the first elapsed time U1 is shorter, the moving direction of the article O is the second upward direction opposite to the first direction. It is also possible to determine that it was the direction (FIG. 7).

The controller 14 can also set a first direction determination region D1 and a second direction determination region D2 within the detection region C, as shown in FIG. The first direction determination area D1 is located adjacent to the boundary of the detection area C on one side (the upper side in the drawing) of the assumed flow line M of the goods O, and the second direction determination area D2 is located adjacent to the boundary of the sensing area C on the other side of the flow line M (lower side in the figure). In this case, the controller 14 determines in what order the goods O pass through the first direction determination region D1 and the second direction determination region D2 when passing through the detection region C. , the moving direction of the transported object O is specified. In other words, by specifying the direction determination area into which the article O entered first after entering the detection area C and the direction determination area into which the article O entered last before exiting the detection area C, Identify the direction of travel. Specifically, as shown in FIGS. 9 and 10, the controller 14 turns on the second flag when it detects that the article O has entered the first direction determination area D1, and turns on the second flag. When it is detected that the transported article O has entered the direction determination area D2, the third flag is turned ON. The controller 14 determines the states of the second flag and the third flag at a first time point T1 after a first time after the first flag is turned ON and at a second time point T2 a second time before the first flag is turned OFF. to confirm. When the second flag is ON at the first time point T1 and the third flag is ON at the second time point T2, it is determined that the moving direction of the conveyed object is the first downward direction as viewed in the drawing (FIG. 9). ). Further, when the third flag is ON at the first time point T1 and the second flag is ON at the second time point T2, the moving direction of the conveyed object is the second upward direction opposite to the first direction. (Fig. 10).

As shown in FIG. 11, if the path A' is a T-shaped path, the detection area C can be set to have a shape as shown in the drawing. A plurality of flow lines M1, M2, and M3 are assumed in this passage A'. In the detection area C, a first direction determination area D1, a second direction determination area D2, and a third direction determination area are arranged adjacent to the boundaries of the detection areas on both sides of each of the flow lines M1, M2, and M3. Regions D3 are arranged respectively. When the controller 14 detects that the article O has entered the first direction determination area D1, the controller 14 turns on the second flag to detect that the article has entered the second direction determination area D2. If so, the third flag is turned ON, and if it is detected that the conveyed object O has entered the third direction determination area D3, the fourth flag is turned ON. The controller 14 checks the states of the second flag, the third flag, and the fourth flag at the first time point T1 and the second time point T2 in the same manner as described above, and decides which flow line the conveyed article O will follow. Determine which direction you are moving. For example, as shown in FIG. 12, when the second flag is ON at the first time point T1 and the fourth flag is ON at the second time point T2, the controller 14 moves the article O along the flow line M2 along the first flow line M2. It is determined that the movement has occurred in the direction from the direction determination area D1 toward the third direction determination area D3. Further, for example, when the fourth flag is ON at the first time point T1 and the third flag is ON at the second time point T2, the conveyed object O moves along the flow line M3 from the third direction determination region D3 to the second direction determination region D3. is determined to have moved in the direction toward the direction determination area D2. An arbitrary number of direction determination regions can be arranged at arbitrary positions in accordance with the assumed flow line of the conveyed goods. For example, if the passage is a crossroad, four direction determination areas may be set.

In the transported object detection system 1, the LiDAR sensor 10 detects the moving direction of the transported object O, and the RFID reader 12 reads the information of the RFID tag P attached to the transported object O, thereby determining what transport It is designed to detect in which direction the object O is transported. In a conventional system that utilizes the time difference between the detection of an RFID tag by two RFID antennas, it is necessary to place the two RFID antennas far apart so as not to interfere with each other. However, in the conveyed object detection system 1, since the LiDAR sensor 10 detects the moving direction, the moving direction can be detected and the RFID tag P can be read in a relatively narrow area. can be done. In addition, by providing the detection area C with the minimum necessary size in the area B that can be detected by the LiDAR sensor 10, it is not affected by the movement of objects and people outside the detection area C, and the transported object O It is possible to reduce the possibility of erroneous detection.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the detection area can be arbitrarily set according to the passage or place through which the conveyed goods pass, and can be the entire detection range of the LiDAR sensor or a plurality of separated areas. In addition, assuming that the LiDAR sensor acquires three-dimensional point group data by irradiating multiple laser beams aligned in the height direction, the object to be conveyed is detected based on the three-dimensional shape of the object. may By using three-dimensional data, it becomes possible to more accurately determine whether an object that has entered the detection area is a target conveyed product. Further, without providing a direction determination area, it is also possible to determine the movement direction of the transported object by directly obtaining the change in the position of the transported object from the point cloud data of the LiDAR sensor. The reading of the RFID tag by the RFID reader may be performed at another timing instead of when the conveyed article enters the detection area. For example, a read start area may be provided within the detection area of the LiDAR sensor, and the RFID tag may be read when the transported article enters the read start area. Furthermore, the computing unit may be built in a LiDAR sensor or an RFID reader, and the computing unit of the LiDAR sensor has the function of determining the moving direction of the transported object. The functions of the controller described above may be distributed to the LiDAR sensor and the RFID reader, such as the function of linking and storing the information of the RFID reader. Although the RFID readers described above have internal antennas, one or more antennas may be external. By arranging a plurality of antennas, it can be expected that the RFID tag can be read more reliably within the detection area.

1 conveyed object detection system 10 LiDAR sensor 12 RFID reader 14 controller (computing unit)
20 laser emitting unit 22 scanning unit 24 light receiving unit 26 rotating table 28 mirror 30 encoders A, A' path B area C detection area D direction determination area D1 first direction determination area D2 second direction determination area D3 third direction Judgment area L Laser beams M, M1, M2, M3 Flow line O Conveyed object P RFID tag R Reflected light

Claims (7)

A conveyed object detection system for detecting a conveyed object having an RFID tag, comprising:
a laser emitting unit for emitting a laser beam, a scanning unit for scanning a space including a predetermined detection area with the laser beam by continuously changing the irradiation direction of the laser beam, and reflected light of the laser beam. and a LiDAR sensor for detecting the position of a transported object within the detection area based on the reflected light;
an RFID reader that reads information on an RFID tag within the detection area;
a computing unit that determines the moving direction of the transported object based on the change in the position of the transported object detected by the LiDAR sensor, and associates information on the RFID tag of the transported object read by the RFID reader with the moving direction; ,
A conveyed object detection system. 2. The conveyed object detection system according to claim 1, wherein the RFID reader reads the RFID tag while the LiDAR sensor detects the presence of the conveyed object within the detection area. The detection area includes a direction determination area located on one side in a direction along the assumed flow line of the conveyed product,
The computing unit determines that the conveyed article is in the detection area and that the conveyed article is in the direction determination area within the detection area, and determines that the conveyed article is in the direction determination area within the detection area. 3. The conveyed object detection system according to claim 1, wherein the direction of movement is specified based on. the orientation determination region is positioned adjacent to the one side boundary of the sensing region;
The computing unit detects that the conveyed object is in the direction at a first point in time after a first time since the conveyed object enters the detection area and at a second point in time a second time before the conveyed object leaves the detection area. It is determined whether or not the conveyed object is in the determination area, and if the conveyed article is not in the direction determination area at the first time point but is in the direction determination area at the second time point, the moving direction is directed to the one side. If the transported object is in the direction determination area at the first time point and is not in the direction determination area at the second time point, the moving direction is the opposite direction to the first direction. 4. A conveyed object detection system according to claim 3, adapted to determine that there are two directions. The calculation unit calculates a first elapsed time from when the conveyed article enters the detection area until it enters the direction determination area, and from when the conveyed article exits the direction determination area to when it exits the detection area. is compared with a second elapsed time between the 4. The conveyed object detection system according to claim 3, wherein when the first elapsed time is shorter than the second elapsed time, it is determined that the moving direction is the second direction opposite to the first direction. . The detection area includes a plurality of direction determination areas,
The computing unit determines whether the conveyed article is in the detection area and in which direction determination area the conveyed article is within the detection area, and determines how the conveyed article is positioned in the plurality of direction determination areas. 3. The conveyed object detection system according to claim 1, wherein said moving direction is identified by determining whether said conveyed object has passed in the correct order. The plurality of direction determination areas include a direction determination area located adjacent to a boundary of the detection area on one side of one or more flow lines assumed for the conveyed article, and the detection area on the other side. and at least an orientation determination region located adjacent to the boundary of
The computing unit determines the direction of the conveyed article at a first time point after a first hour after the conveyed article enters the detection area and at a second time point after a second time period before the conveyed article leaves the detection area. It is determined whether or not the transported object is in the determination area, and it is determined that the moving direction of the transported object is in the direction from the direction determination area where it was located at the first time point toward the direction determination area where it was located at the second time point. 7. The conveyed object sensing system of claim 6, wherein:

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