JP7050289B2 - Approach detection system - Google Patents

Description

The present invention relates to an approach detection system that detects that a mobile device such as a forklift or a bulldozer comes and goes in a work site where the mobile device and a worker or the mobile device and another device are close to each other.
In the present invention, the term "equipment" is a general term for not only mobile devices but also non-moving devices.

As such an approach detection system, a system using an induced magnetic field (electromagnetic induction wave) and a radio wave is known, and the applicant of the present application applies to the distance detection control device attached to the mobile device side and the operator side in Patent Document 1. We disclosed an approach detection system that makes it possible to change the alarm level according to the distance from the attached RFID tag with magnetic field detection function, and also allows the distance to output the alarm to be set on the mobile device side.

In the approach detection system of Patent Document 1, the alarm level is changed according to the distance between the mobile device (distance detection control device) and the worker (RFID tag with magnetic field detection function), so that the worker can use the mobile device. There is a particular merit in being able to grasp whether or not the device is approaching to a certain distance, and there are several achievements in practical application.

Japanese Unexamined Patent Publication No. 2013-142675 (Patent No. 583577) Japanese Unexamined Patent Publication No. 2016-57934

The inventors of the present application have obtained a need from a user of the approach detection system of Patent Document 1 that has been put into practical use to grasp in which direction a worker approaching a mobile device is with respect to the mobile device.
However, this need cannot be met by the proximity detection system of Patent Document 1. This is because the approach detection system of Patent Document 1 has only one inductive magnetic field transmitter.
On the other hand, FIG. 12 of Patent Document 2 discloses an example in which a plurality of induced magnetic field transmitting units (transmitting antennas) are provided, but the purpose is to expand the reach area of the induced magnetic field (trigger signal) (Patent). Reference 2 [0105]), which does not meet the above-mentioned needs.

Therefore, the problem to be solved by the present invention is to have an approach detection control device attached to a mobile device and a magnetic field detection function attached to a device other than the mobile device or a worker (hereinafter referred to as "worker or the like"). In an approach detection system that detects an approach to an RFID tag, the purpose is to be able to grasp in which direction the RFID tag with a magnetic field detection function that is close to the mobile device is located with respect to the mobile device.

According to one aspect of the present invention, the following approach detection system is provided.
An approach detection system that detects the approach between an approach detection control device attached to a mobile device and an RFID tag with a magnetic field detection function attached to a device other than the mobile device or an operator.
The approach detection control device includes n inductive magnetic field transmitters of Nos. 1 to n (n is a natural number of 2 or more; the same applies hereinafter) that transmits an inductive magnetic field, a radio wave receiver, and a device that controls these. The induced magnetic fields provided with the control unit and transmitted from the n induced magnetic field transmitting units are transmitted so as to include regions having different reach.
An RFID tag with a magnetic field detection function includes a magnetic field sensor unit that detects an induced magnetic field, a radio wave transmission unit that transmits a magnetic field detection radio wave, and a tag control unit that controls these.
The device control unit transmits an induced magnetic field from the n induced magnetic field transmitting units at a predetermined specific timing in the order of No. 1 to n, and in the order of No. 1 to n, respectively. The transmission cycle of transmitting the induced magnetic field at the specific timing is repeated at predetermined time intervals, and the transmission cycle is repeated.
The tag control unit acquires in advance the order information of the order from No. 1 to n and the timing information about the specific timing, and the magnetic field sensor unit obtains any of the induced magnetic fields of No. 1 to n. When it is detected, it waits until the timing when the nth induced magnetic field in the transmission cycle is transmitted, and the information about the induced magnetic field detected by this timing (hereinafter referred to as "induced magnetic field information") is used as the magnetic field detection radio wave to transmit the radio wave. An approach detection system that sends from the unit.

As described above, in the approach detection system of the present invention, the approach detection control device includes a plurality of (n) inductive magnetic field transmitters, and each of the inductive magnetic fields transmitted from the plurality of (n) inductive magnetic field transmitters. Is received by the magnetic field sensor unit of the RFID tag with magnetic field detection function (hereinafter, simply referred to as "RFID tag"), and the radio wave transmission unit detects the approach to the induced magnetic field information (magnetic field detection radio wave) which is information about the induced magnetic field. Send to the control device. Then, the radio wave receiving unit of the approach detection control device receives this induced magnetic field information (magnetic field detection radio wave), and the approach detection control device is attached to the mobile device based on the received induced magnetic field information. It is possible to grasp in which direction the RFID tag (worker, etc.) approaching the mobile device is located with respect to this mobile device.
Moreover, the n induced magnetic field transmitters always transmit the induced magnetic fields in the order of No. 1 to n at predetermined specific timings, and the tag control unit always transmits the induced magnetic fields in the order of No. 1 to n. Since the information and the timing information about this specific timing are acquired in advance, when the magnetic field sensor unit detects any of the induced magnetic fields of Nos. 1 to n, the tag control unit is at the end of the transmission cycle ( Since the timing at which the nth induced magnetic field is transmitted is known, the RFID tag is the first RFID tag only by waiting until the nth induced magnetic field is transmitted in the transmission cycle without waiting until the start of the next transmission cycle. It is possible to grasp whether or not each of the induced magnetic fields of No. n is received from.
For example, when the magnetic field sensor unit detects the second induced magnetic field when there are two induced magnetic field transmission units as described later, if the above-mentioned order information and timing information are known, the first induced magnetic field is already transmitted. Since it can be seen that the RFID tag has been received but could not be received, it is possible to immediately grasp that the RFID tag is in a position where it can receive only the second induced magnetic field without waiting for the start of the next transmission cycle.
As described above, according to the approach detection system of the present invention, it is possible to quickly grasp in which direction the RFID tag (worker or the like) is located with respect to the mobile device.

In the proximity detection system of the present invention, it is preferable that the device control unit randomly changes the time interval between transmission cycles. As a result, even if there are a plurality of approach detection control devices, it is possible to avoid overlapping the transmission cycles of the approach detection control devices.

Further, in the proximity detection system of the present invention, the radio wave transmitting unit can transmit the magnetic field detection radio wave in any one of a plurality of time slots, and randomly changes the time slot for transmitting the magnetic field detection radio wave. Is preferable. As a result, even if there are a plurality of RFID tags, it is possible to prevent the magnetic field detection radio waves transmitted from the RFID tags from overlapping each other.

Further, in the approach detection system of the present invention, the approach detection control device can be provided with an alarm output unit (device-side alarm output unit). Then, the device control unit controls the device side alarm output unit based on the induced magnetic field information received by the radio wave receiving unit, and outputs or does not output the alarm from the device side alarm output unit, or outputs the alarm from the device side alarm output unit. It is possible to change the type of alarm to be given.

Similarly, in the approach detection system of the present invention, the RFID tag can be provided with an alarm output unit (tag-side alarm output unit). Then, the tag control unit controls the tag side alarm output unit based on the induced magnetic field information, and outputs or does not output the alarm from the tag side alarm output unit, or outputs the type of alarm from the tag side alarm output unit. You can change it.

According to the approach detection system of the present invention, it is possible to quickly grasp in which direction an operator or the like having an RFID tag is located with respect to a mobile device having an approach detection control device.

The conceptual diagram which shows the whole structure of the approach detection system which is one Embodiment of this invention. The block diagram which shows the structure of the approach detection control device and the RFID tag in the approach detection system of FIG. The time chart which shows the operation of the approach detection system of FIG. An example in which the radio wave transmission unit of the RFID tag in the proximity detection system of FIG. 1 can transmit a magnetic field detection radio wave (induced magnetic field information) in three time slots.

FIG. 1 conceptually shows the overall configuration of an approach detection system according to an embodiment of the present invention, and FIG. 2 shows the configuration of an approach detection control device and an RFID tag in this approach detection system as a block diagram.

This approach detection system includes an approach detection control device 10 and an RFID tag 20.
The approach detection control device 10 is attached to the vehicle 30 which is a mobile device, and the RFID tag 20 is attached to an operator or the like (not shown). The vehicle 30 travels to the left in FIG. That is, in FIG. 1, the left direction is the front of the vehicle 30, and the right direction is the rear of the vehicle 30.

As shown in the upper part of FIG. 2, the approach detection control device 10 controls the first inductive magnetic field transmission unit 11, the second inductive magnetic field transmission unit 12, the radio wave receiving unit 13, the device-side alarm output unit 14, and these. As shown in the lower part of FIG. 2, the RFID tag 20 includes a device control unit 15, a magnetic field sensor unit 21, a radio wave transmission unit 22, a tag-side alarm output unit 23, and a tag control unit that controls them. Further, the proximity detection control device 10 includes a voltage conversion unit 16 that converts an external power source into a DC voltage (12V) suitable for the operation of the approach detection control device 10, and the RFID tag 20 includes a battery as a DC power source.

As shown in FIG. 1, in this embodiment, the first induced magnetic field transmitting unit 11 is attached to the front of the vehicle 30, and is referred to as an induced magnetic field (hereinafter referred to as “magnetic field A”” with an ID of magnetic field A. ) Is sent. On the other hand, the second induced magnetic field transmitting unit 12 is attached to the rear of the vehicle 30 and transmits an induced magnetic field (hereinafter referred to as "magnetic field B") having an ID of magnetic field B. As conceptually shown in FIG. 1, the reach of these magnetic fields A and B is an elliptical shape having a long axis along the traveling direction of the vehicle 30, and the magnetic field A covers the front of the vehicle 30 and is a magnetic field. B covers the rear of the vehicle 30. The reach of the magnetic field A and the magnetic field B overlap on both sides of the vehicle 30.

In this embodiment, the number of induced magnetic field transmission units is two, but three or more may be provided. For example, in addition to the two in this embodiment, a total of four induced magnetic field transmission units may be provided, one on the right side and one on the left side of the vehicle 30. When the induced magnetic field transmission units are provided on both sides of the vehicle 30 in this way, the reach of the induced magnetic field from the induced magnetic field transmission units is a direction orthogonal to the traveling direction of the vehicle 30 in order to cover both sides of the vehicle 30. It is preferable to have an elliptical shape having a long axis along the line.
Further, although only one vehicle 30 to which the approach detection control device 10 is attached is shown in FIG. 1, there may be a plurality of vehicles 30 to which the approach detection control device 10 is attached.
Further, in FIG. 1, only one RFID tag 20 is shown. That is, the number of workers and the like to which the RFID tag 20 is attached is 1, but there may be a plurality of workers and the like to which the RFID tag 20 is attached.

FIG. 3 shows the operation of this approach detection system in a time chart. Hereinafter, the operation of this approach detection system will be described with reference to FIGS. 1 to 3.

The device control unit 15 is specified in advance from the two induced magnetic field transmitting units 11 and 12, in the order of the first induced magnetic field transmitting unit 11 (No. 1) and the second induced magnetic field transmitting unit 12 (No. 2). The induced magnetic field (magnetic fields A and B) is transmitted at the timing of. Then, the transmission cycle of transmitting the induced magnetic field at the specific timing of the first induced magnetic field transmitting unit 11 (No. 1) and the second induced magnetic field transmitting unit 12 (No. 2) is repeated at a predetermined time interval t0 ( See Figure 3). In this way, the order in which the induced magnetic field is transmitted in each transmission cycle is the same each time, and the timing is also the same each time. Here, the timing is a concept that collectively refers to the transmission time t1 of the magnetic field A, the time interval t2 between the transmission of the magnetic field A and the transmission of the magnetic field B, and the transmission time t3 of the magnetic field B, and is a predetermined specific cycle. , These t1 to t3 are cycles having a predetermined specific value, and the fact that the timing is the same every time means that t1 to t3 are the same every time in each transmission cycle. That is, the time length of each transmission cycle is the same each time.

Even when there are three or more induced magnetic field transmitting units, the order and timing of transmitting the induced magnetic field shall be the same each time. For example, when there are three induced magnetic field transmitters, the timing is t1 to t3 described above, as well as the time interval t4 between the transmission of the second magnetic field B and the transmission of the third magnetic field C and the transmission time t5 of the magnetic field C. However, t1 to t5 are the same each time in each transmission cycle. On the other hand, the time interval t2 between the transmission of the magnetic field A and the transmission of the magnetic field B and the time interval t4 between the transmission of the magnetic field B and the transmission of the magnetic field C may be different. That is, the fact that the timing is the same each time means that t1 to t5 are the same each time in each transmission cycle, and it is not necessary that the above-mentioned time interval t2 and the time interval t4 have the same value.

The time interval t0 between the transmission cycles may be the same or different each time, but from the viewpoint of avoiding overlapping of the transmission cycles of the approach detection control devices when there are a plurality of approach detection control devices 10. It is preferable that the time interval t0 between transmission cycles is randomly changed each time. The time interval t0 between the transmission cycles is changed by the control of the device control unit 15.

On the other hand, the tag control unit 24 acquires and stores in advance the order information of the magnetic field A and the magnetic field B described above and the timing information regarding the specific timing (t1 to t3) described above. As a result, the tag control unit 24 knows that the magnetic field B is always transmitted at a specific timing next to the magnetic field A.

Then, when the magnetic field sensor unit 21 detects the induced magnetic field of either the magnetic field A (No. 1) or the magnetic field B (No. 2), the tag control unit 24 induces the last (No. 2 in this embodiment) in the transmission cycle. It waits until the timing at which the magnetic field (magnetic field B) is transmitted, and causes the radio wave transmission unit 22 to transmit the induced magnetic field information, which is information about the induced magnetic field detected by this timing, as the magnetic field detection radio wave. The tag control unit 24 can know "the timing at which the last (second in this embodiment) induced magnetic field (magnetic field B) in the transmission cycle is transmitted" based on the above-mentioned order information and timing information. You can, so you can wait until this timing.

For example, in the first transmission cycle on the leftmost side of FIG. 3, since the magnetic field sensor unit 21 receives (detects) the magnetic field A, the tag control unit 24 waits until the timing when the magnetic field B is transmitted in this transmission cycle. In this transmission cycle, the magnetic field B is received (detected) at the timing when the magnetic field B is transmitted, so that the magnetic field A + the magnetic field B is received (detected) as the induced magnetic field information about the induced magnetic field received (detected) by this timing. Information to that effect is transmitted from the radio wave transmission unit 22 as a magnetic field detection radio wave.
This magnetic field detection radio wave (induced magnetic field information) is received by the radio wave receiving unit 13 of the approach detection control device 10, and the device control unit 15 has the RFID tag 20 on the vehicle based on the induced magnetic field information received by the radio wave receiving unit 13. It is possible to grasp in which direction the position is located with respect to 30. In this transmission cycle, since the magnetic field A + the magnetic field B is received (detected), the RFID tag 20 can receive (detect) both the magnetic field A and the magnetic field B (the position where the reach of the magnetic field A and the magnetic field B overlap). That is, it can be grasped that it is located on the right side or the left side of the vehicle 30.

Next, since the magnetic field sensor unit 21 receives (detects) the magnetic field A also in the second transmission cycle of FIG. 3, the tag control unit 24 waits until the timing at which the magnetic field B is transmitted in this transmission cycle. In this transmission cycle, the magnetic field B is not received (detected) at the timing when the magnetic field B is transmitted, so that only the magnetic field A is received (detected) as the induced magnetic field information about the induced magnetic field received (detected) by this timing. Information is transmitted from the radio wave transmission unit 22 as a magnetic field detection radio wave.
This magnetic field detection radio wave (induced magnetic field information) is received by the radio wave receiving unit 13 of the approach detection control device 10, and the device control unit 15 has the RFID tag 20 on the vehicle based on the induced magnetic field information received by the radio wave receiving unit 13. It is possible to grasp in which direction the position is located with respect to 30. In this transmission cycle, since only the magnetic field A is received (detected), the RFID tag 20 is in a position where only the magnetic field A can be received (detected) (a position within the range where only the magnetic field A can reach), that is, in front of the vehicle 30. You can know where it is located.

Next, in the third transmission cycle of FIG. 3, since the magnetic field sensor unit 21 receives (detects) the magnetic field B, the tag control unit 24 has already transmitted the magnetic field A in this transmission cycle. Since it can be seen that the magnetic field B could not be received (detected), it can be seen that the timing of receiving the magnetic field B waited until the timing of transmitting the magnetic field B in this transmission cycle. Then, the radio wave transmission unit 22 transmits information to the effect that only the magnetic field B is received (detected) as the induced magnetic field information about the induced magnetic field received (detected) by this timing as the magnetic field detection radio wave.
This magnetic field detection radio wave (induced magnetic field information) is received by the radio wave receiving unit 13 of the approach detection control device 10, and the device control unit 15 has the RFID tag 20 on the vehicle based on the induced magnetic field information received by the radio wave receiving unit 13. It is possible to grasp in which direction the position is located with respect to 30. In this transmission cycle, since only the magnetic field B is received (detected), the RFID tag 20 is at a position where only the magnetic field B can be received (detected) (a position within the range where only the magnetic field B can reach), that is, behind the vehicle 30. You can know where it is located.

As described above, in this approach detection system, the device control unit 15 has the RFID tag 20 forward and backward with respect to the vehicle 30 based on the induced magnetic field information indicating whether or not the magnetic field A and the magnetic field B have been received (detected). , You can grasp which direction it is located on the side. Similarly, the tag control unit 24 can grasp whether the RFID tag 20 is located in the front, rear, or side direction with respect to the vehicle 30 based on the above-mentioned induced magnetic field information.

Moreover, in this approach detection system, since the tag control unit 24 has acquired the above-mentioned order information and timing information in advance, the magnetic field sensor unit induces either magnetic field A (No. 1) or magnetic field B (No. 2). When a magnetic field is detected, the timing at which the last (second) induced magnetic field (magnetic field B) in the transmission cycle is transmitted is known, so that the second induction in the transmission cycle is not required until the start of the next transmission cycle. Only by waiting until the timing at which the magnetic field (magnetic field B) is transmitted, it is possible to grasp whether or not the RFID tag 20 has received the magnetic field A and the magnetic field B.
For example, in the third transmission cycle of FIG. 3, when the magnetic field sensor unit first receives the second magnetic field B, it can be seen that the first magnetic field A has already been transmitted but could not be received. Without waiting for the start of the next transmission cycle, it is possible to immediately know that the RFID tag is in a position where it can receive only the second magnetic field B.
On the other hand, in the configuration in which the magnetic field A and the magnetic field B are simply received and the magnetic field detection radio waves are individually transmitted, for example, when the magnetic field B is received first, it is determined whether or not to receive the magnetic field A after waiting for a predetermined time. This requires waiting for a predetermined time, and it takes time to grasp in which direction the RFID tag (worker, etc.) is located with respect to the mobile device.
As described above, according to the approach detection system of this embodiment, it is possible to quickly grasp in which direction the RFID tag (worker or the like) is located with respect to the mobile device.

In this embodiment, it is preferable that the radio wave transmission unit 22 can transmit a magnetic field detection radio wave (induced magnetic field information) in a plurality of time slots (transmission slots). For example, FIG. 4 shows an example in which a magnetic field detection radio wave (induced magnetic field information) can be transmitted in three time slots.

When a plurality of RFID tags 20 are within the reach of the magnetic field A or the magnetic field B, the radio wave transmission unit 22 of each RFID tag 20 receives only the magnetic field A, receives only the magnetic field B, and receives the magnetic field A + the magnetic field B. Any one of the induced magnetic field information is transmitted as a magnetic field detection radio wave, but if each RFID tag 20 has a single time slot, the magnetic field detection radio waves transmitted from each RFID tag may overlap. On the other hand, in the example of FIG. 4, by properly using the three time slots, it is possible to avoid overlapping of the magnetic field detection radio waves transmitted from the RFID tags. Specifically, by randomly changing the time slot for transmitting the magnetic field detection radio wave in each RFID tag, it is possible to avoid overlapping of the magnetic field detection radio waves transmitted from each RFID.

In this embodiment, the approach detection control device 10 includes a device-side alarm output unit 14. Therefore, the device control unit 15 controls the device-side alarm output unit 14 based on the above-mentioned induced magnetic field information received by the radio wave receiving unit 13, and outputs or does not output an alarm from the device-side alarm output unit 14. The type of alarm output from the device-side alarm output unit 14 can be changed.
Specifically, the induced magnetic field information includes any one of (1) receiving only the magnetic field A, (2) receiving only the magnetic field B, and (3) receiving the magnetic field A + the magnetic field B. The alarm can be output only in the case of 1), and the type of alarm (alarm sound, alarm display, etc.) to be output in the above (1), (2), and (3) can be changed. Can be done.

In this embodiment, the RFID tag 20 includes a tag-side alarm output unit 23. Therefore, the tag control unit 24 controls the tag side alarm output unit 23 based on the above-mentioned induced magnetic field information, and outputs or does not output an alarm from the tag side alarm output unit 23, or from the tag side alarm output unit 23. It is possible to change the type of alarm to be output. The specific example is the same as the above-mentioned device-side alarm output unit 14.

Here, the time interval t0 between the transmission cycles shown in FIG. 2, the time interval t2 between the transmission of the magnetic field A and the transmission of the magnetic field B, and the transmission of the magnetic field B and the transmission of the magnetic field detection radio wave (induced magnetic field information). The time interval tt is preferably short from the viewpoint of quickness of approach detection.
For example, t0 is preferably 1 second or less, more preferably 0.5 seconds or less, and even more preferably 0.1 seconds or less.
t2 is preferably 0.1 seconds or less, more preferably 0.01 seconds or less, and even more preferably 0.001 seconds or less.
The tt is preferably 0.1 seconds or less, more preferably 0.01 seconds or less, and even more preferably 0.001 seconds or less.

The transmission time t1 of the magnetic field A and the transmission time t3 of the magnetic field B are preferably 0.001 to 0.1 seconds, more preferably 0.001 to 0.05 seconds, and 0.001. It is more preferably ~ 0.01 seconds.

10 Approach detection control device 11 1st inductive magnetic field transmitter 12 2nd inductive magnetic field transmitter 13 Radio wave receiver 14 Device side alarm output unit 15 Device control unit 16 Voltage conversion unit 20 RFID tag 21 Magnetic field sensor unit 22 Radio wave transmission unit 23 Tag side alarm output unit 24 Tag control unit 25 Battery

Claims (5)

An approach detection system that detects the approach between an approach detection control device attached to a mobile device and an RFID tag with a magnetic field detection function attached to a device other than the mobile device or an operator.
The approach detection control device includes n inductive magnetic field transmitters of Nos. 1 to n (n is a natural number of 2 or more; the same applies hereinafter) that transmits an inductive magnetic field, a radio wave receiver, and a device that controls these. The induced magnetic fields provided with the control unit and transmitted from the n induced magnetic field transmitting units are transmitted so as to include regions having different reach.
An RFID tag with a magnetic field detection function includes a magnetic field sensor unit that detects an induced magnetic field, a radio wave transmission unit that transmits a magnetic field detection radio wave, and a tag control unit that controls these.
The device control unit transmits an induced magnetic field from the n induced magnetic field transmitting units at a predetermined specific timing in the order of No. 1 to n, and in the order of No. 1 to n, respectively. The transmission cycle of transmitting the induced magnetic field at the specific timing is repeated at predetermined time intervals, and the transmission cycle is repeated.
The tag control unit acquires in advance the order information of the order from No. 1 to n and the timing information about the specific timing, and the magnetic field sensor unit obtains any of the induced magnetic fields of No. 1 to n. When it is detected, it waits until the timing when the nth induced magnetic field in the transmission cycle is transmitted, and the information about the induced magnetic field detected by this timing (hereinafter referred to as "induced magnetic field information") is used as the magnetic field detection radio wave to transmit the radio wave. An approach detection system that sends from the unit. The approach detection system according to claim 1, wherein the device control unit randomly changes the time interval between the transmission cycles. The radio wave transmitting unit can transmit the magnetic field detection radio wave in any one of a plurality of time slots, and randomly changes the time slot for transmitting the magnetic field detection radio wave, claim 1 or 2. The approach detection system described in. The approach detection control device further includes an alarm output unit (hereinafter referred to as “device-side alarm output unit”), and the device control unit further includes the device-side alarm output unit based on the induced magnetic field information received by the radio wave receiving unit. The approach according to any one of claims 1 to 3, wherein the alarm is output or not output from the device-side alarm output unit, or the type of the alarm output from the device-side alarm output unit is changed. Detection system. The RFID tag with a magnetic field detection function further includes an alarm output unit (hereinafter referred to as "tag side alarm output unit"), and the tag control unit controls the tag side alarm output unit based on the induced magnetic field information. The approach detection system according to any one of claims 1 to 4, wherein an alarm is output or not output from the tag side alarm output unit, or the type of alarm output from the tag side alarm output unit is changed.

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