JP2019078721A - Wireless communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wireless communication system capable of realizing physical distribution management and position management of products etc. in a wide area by using a general-purpose passive type RF tag. SOLUTION: A passive RF tag 1 for storing unique information is attached to each object placed in a yard. The wireless communication system includes a set of a plurality of transmitters 2 and a transmitting antenna 3 and a set of a plurality of receivers 4 and a receiving antenna 5. The transmitter 2 transmits radio waves to the RF tag 1 via the transmitting antenna 3. The receiver 4 receives radio waves from the RF tag 1 that operates by receiving the radio waves transmitted from the transmission antenna 3 via the reception antenna 5. The transmission antenna 3 is an omnidirectional antenna or a directional antenna. The receiving antenna 5 is a directional antenna, is supported by an antenna rotator 6 that is a supporting device, and the orientation of the receiving antenna 5 is variable. [Selection diagram] Figure 1

Description

  The present invention relates to a wireless communication system using an RF tag.

  RF tags are sometimes used to identify and manage products and the like. By attaching an RF tag storing unique information to a product or the like and the communication device reading the unique information from the RF tag by wireless communication, physical distribution management and position management of the product or the like can be realized.

  As an RF tag, there are an active type that operates with a built-in battery and a passive type that operates without using a battery and using radio waves received from the outside as an energy source. The active RF tag can make the communication distance long distance, but the unit price is high, and it is necessary to grasp the remaining capacity of the built-in battery, and it is almost used when handling a large number of products etc. It has not been. On the other hand, passive RF tags are often employed when handling a large number of products and the like because the unit price is low and there is no need to manage the remaining battery capacity.

JP 2001-525970 gazette

  A passive RF tag generally has a short communication distance of about 5 to 6 [m], and is required to extend the communication distance in order to apply to distribution management and position management of products in a wide area. The wide area is assumed to be an area of several tens of meters to several hundreds of meters in each of the vertical and horizontal directions.

  In order to extend the communication distance with the RF tag, for example, it may be considered to improve the area, length, shape, etc. of the antenna inside the RF tag, but the maker of the RF tag will respond and the unit price will be high. It will

Moreover, in order to extend the communication distance with the RF tag, it is conceivable to use a directional antenna as a transmitting and receiving antenna of the communication device while using a general-purpose passive RF tag.
However, when applied to, for example, physical distribution management or location management of products outdoors, the radio wave law may limit the total dB of the output of the communication device and the gain of the transmitting / receiving antenna. In this case, it may be necessary to reduce the transmission output of radio waves as an energy source for operating the RF tag.

For example, in Patent Document 1, an RFID tag electrostatically receives an excitation signal from an electrostatic exciter at a close position to be in an excited state, generates a read signal based on stored tag information, and reads a read signal. An arrangement for electrostatically transmitting to a reader in close proximity is disclosed.
However, Patent Document 1 is not assumed to be applied to distribution management and location management of products and the like in a wide area.

  The present invention has been made in view of the above-described points, and an object of the present invention is to realize physical distribution management and position management of products and the like in a wide area by using a general-purpose passive RF tag. I assume.

The gist of the present invention for solving the above problems is as follows.
[1] Passive RF tag,
A transmitting antenna for transmitting radio waves to the RF tag;
A wireless communication system, comprising: a receiving antenna separate from the transmitting antenna for receiving a radio wave from the RF tag that operates by receiving a radio wave transmitted from the transmitting antenna.
[2] The wireless communication system according to [1], wherein the receiving antenna is a directional antenna.
[3] The wireless communication system according to [1] or [2], wherein a plurality of the transmitting antennas are installed.
[4] The wireless communication system according to any one of [1] to [3], wherein a plurality of the receiving antennas are installed.
[5] The wireless communication system according to [2], wherein the receiving antenna is supported by a support device, and the direction of the receiving antenna is variable.
[6] A control means is provided to control to transmit radio waves from the transmitting antenna, and to control to change the direction of the receiving antenna in accordance with the position of the transmitting antenna [5]. The wireless communication system according to.
[7] The wireless communication system according to [2], further comprising: position specifying means for specifying a position of the RF tag based on radio waves received from the RF tag via the receiving antenna.
[8] The wireless communication system according to [7], wherein the position specifying unit obtains the position of the RF tag in an intersection area in which the reception ranges of the two reception antennas are crossed.

  According to the present invention, it is possible to realize physical distribution management and position management of products and the like in a wide area by using a general-purpose passive RF tag.

It is a figure showing the schematic structure of the radio communications system concerning an embodiment. It is a figure showing the schematic structure of the radio communications system concerning an embodiment. It is a figure which shows the relationship between the transmission range of a transmission antenna, the communicable area | region of RF tag in operation | movement, and the reception range of a receiving antenna. It is a figure for demonstrating the algorithm which cross | intersects the receiving range of two receiving antennas, and calculates | requires the position of the RF tag which has entered the crossing area | region. It is a figure for demonstrating the RF tag detection vector on three-dimensional space.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
1 and 2 show a schematic configuration of a wireless communication system according to an embodiment. In the present embodiment, as shown in FIG. 2, a wireless communication system used to specify the position of an object 9 in an outdoor yard (place) where the object 9 such as a product is placed will be described. The target yard is assumed to be an area of several tens of meters to several hundreds of meters in length and width, respectively.

  As shown in FIG. 2, an RF tag 1 storing unique information is attached to each object 9 placed in the yard. The RF tag 1 may use a general-purpose passive RF tag, for example, a 920 MHz band passive RF tag. Note that attaching the RF tag 1 to the object 9 means, for example, simply placing the RF tag 1 on a predetermined portion of the object 9 in addition to attaching the RF tag 1 to the object 9, etc. It also includes the form.

As shown in FIG. 1, the wireless communication system includes a set of a plurality of transmitters 2 and transmit antennas 3 and a set of a plurality of receivers 4 and receive antennas 5.
The transmitter 2 transmits a radio wave to the RF tag 1 via the transmission antenna 3. The receiver 4 receives radio waves from the RF tag 1 that operates by receiving radio waves transmitted from the transmission antenna 3 via the reception antenna 5.

The transmitting antenna 3 for transmitting radio waves to the RF tag 1 may be selected according to the application, and for example, a directional antenna such as a nondirectional antenna such as a monopole antenna or a planar antenna is used. In the present embodiment, a nondirectional antenna is used, and the transmission range t of the transmission antenna 3 is schematically shown.
As shown in FIG. 2, although only a part of the transmitting antenna 3 is shown, the transmitting antenna 3 is in a suitable place in the yard so as to cover the entire area of the yard where the object 9 is placed (hereinafter referred to as the target area). An appropriate number will be allocated.

The receiving antenna 5 for receiving radio waves from the RF tag 1 is a directional antenna, and for example, a Yagi Uda antenna or a circularly polarized antenna is used. The reception range r of the reception antenna 5 is schematically shown.
The receiving antenna 5 is supported by an antenna rotator 6, which is a supporting device (see FIG. 1), and the orientation of the receiving antenna 5 is variable.
As shown in FIG. 2, an appropriate number of receiving antennas 5 are arranged on the outer periphery, corners, etc. of the yard so that the entire area of the target area can be covered by changing the direction.

  As described above, by separating the transmitting antenna 3 and the receiving antenna 5 as separate bodies, long-distance reception can be realized by high sensitivity antenna formation without being restricted by the radio wave method, with the receiving antenna 5 dedicated to reception. . In this embodiment, weak radio wave detection is performed by appropriately setting various structural design parameters of the receiving antenna 5 and amplifying the signal in the receiver 4 to increase the gain of the receiving antenna 5, and the predetermined radio wave detection exceeds 100 meters. It is possible to receive radio waves from the RF tag 1 separated by a distance of. In addition, since dB within the restrictions of the Radio Law can be distributed to the transmission side, the transmission output of radio waves to be transmitted from the transmission antenna 3 and serving as an energy source for operating the RF tag 1 is secured. The transmission range t can be made wide.

The wireless communication system also includes an information processing device 8. The information processing device 8 is connected to the transmitter 2, the receiver 4 and the antenna rotator 6 via the line concentrator 7. The information processing device 8 holds the position information of the transmitting antenna 3 and the position information of the receiving antenna 5, and controls the transmitter 2, the receiver 4, and the antenna rotator 6 in an integrated manner.
The information processing device 8 controls so as to transmit radio waves from the transmission antenna 3 and functions as control means for controlling the direction of the reception antenna 5 in accordance with the position of the transmission antenna 3. Further, the information processing device 8 functions as a position specifying means for specifying the position of the RF tag 1, that is, the position of the object 9 in the yard, based on the radio wave received from the RF tag 1 via the receiving antenna 5. The information processing device 8 is constituted by a computer device provided with, for example, a CPU, a ROM, a RAM and the like, and the CPU executes a predetermined program to realize the function of the control means and the function of the position specifying means.

The process of specifying the position of the object 9 will be described below with reference to FIGS. 3 to 5. In FIG. 3, only the RF tag 1 is illustrated, and the illustration of the object 9 is omitted. In addition, although in FIG. 3 and FIG. 4, the size of the reception range r of the reception antenna 5 is illustrated to be different, the viewability of the drawing is considered, and the reception range r depends on the direction of the reception antenna 5 It does not mean that the size of
Under the control of the information processing device 8, the transmitter 2 transmits a radio wave via the transmission antenna 3. Thus, the RF tag 1 present in the transmission range t of the transmission antenna 3 receives the radio wave transmitted from the transmission antenna 3 and operates as an energy source. The communicable area a of the RF tag 1 in operation is schematically shown. The information processing device 8 controls to transmit radio waves from a part of the transmission antennas 3 among the plurality of transmission antennas 3, for example.

Further, under the control of the information processing device 8, the receiver 4 receives a radio wave from the RF tag 1 in operation via the receiving antenna 5, and reads the unique information.
In this case, as shown in FIGS. 3B and 3C, in order to overlap the reception range r of the reception antenna 5 on the communicable area a of the RF tag 1 in operation, the direction of the reception antenna 5 (reception antenna The pointing direction 5) needs to be directed to the communicable area 1a of the RF tag 1 in operation. Since the information processing device 8 recognizes the transmitting antenna 3 during radio wave transmission, the information processing device 8 controls the antenna rotator 6 to direct the receiving antenna 5 to the transmission range t of the transmitting antenna 3 during radio wave transmission. Since the RF tag 1 in operation is within the transmission range t of the transmitting antenna 3 during radio wave transmission, if the direction of the receiving antenna 5 is finely adjusted, the reception range r of the receiving antenna 5 is an RF tag in operation It can be superimposed on one communicable area a.

  Under the control of the information processing apparatus 8, the transmitting antenna 3 for transmitting radio waves is switched, and the direction of the receiving antenna 5 is changed accordingly, thereby scanning the entire area of the target area, all of which are placed in the target area. Specific information can be read from the RF tag 1 of the object 9 of FIG.

Here, FIG. 3A shows a target area in which the target 9 is disposed on a straight line.
In this case, if the unique information is read from the RF tag 1 in operation, the position of the RF tag 1 can be specified based on the orientation of the receiving antenna 5 at that time. As long as the target area is such that the object 9 is disposed on a straight line, only one receiving antenna 5 is sufficient.

FIGS. 3 (b) and 3 (c) show target areas where the target 9 can be arranged other than on a straight line, such as the target 9 is arranged vertically and horizontally.
In this case, if the unique information is read from the operating RF tag 1, it can be identified that the RF tag 1 is present in the direction of the direction of the receiving antenna 5 at that time, but until the position of the RF tag 1 is identified It does not reach. Although it is conceivable to estimate the distance to the RF tag 1 in the direction of the direction of the receiving antenna 5 according to the strength of the radio wave received by the receiving antenna 5, it can not be said that the specific accuracy is high.
Therefore, the reception range r of the two reception antennas 5 is made to intersect, and the position of the RF tag 1 in the intersection area is determined.

Taking FIG. 3C as an example, the RF tag 1a is an RF tag in operation, and is in the intersection area of the reception ranges r of the two receiving antennas 5, and the position can be specified. .
On the other hand, the RF tags 1b to 1d can not be identified. Specifically, the RF tag 1 b is an operating RF tag, but falls within the reception range r of one receiving antenna 5. Also, although the RF tag 1 c is an operating RF tag, it does not fall within the reception range r of any of the receiving antennas 5. Also, the RF tag 1 d is in non-operation.

Here, in FIG. 3B, the receiving antenna 5 is installed at a height close to a plane to be a target area (a height at which the RF tag 1 is attached to the target 9), and an azimuth rotator is used as the antenna rotator 6. An example is shown.
However, in the case of FIG. 3B, for example, if the object 9 is metal, the radio wave is blocked, and the unique information can not be read from the operating RF tag 1.

On the other hand, FIG. 3C shows an example in which the receiving antenna 5 is disposed at the upper side (the receiving antenna 5 is disposed at a position higher than the plane serving as the target area), and the azimuth and elevation rotator is used as the antenna rotator 6. It is.
In the case of FIG. 3C, the radio wave is not blocked by the object 9, and the unique information can be read from any position of the RF tag 1 in operation. As described above, in the case where the object 9 blocks radio waves, it is preferable to install the receiving antenna 5 at the upper side and use the azimuth and elevation rotator as the antenna rotator 6. Further, even when the object 9 is placed one on top of the other, it is preferable to set the receiving antenna 5 above and use an azimuth and elevation rotator as the antenna rotator 6.

An algorithm will be described with reference to FIGS. 4 and 5 in which the reception ranges r of the two reception antennas 5 are crossed to obtain the position of the RF tag 1 in the intersection area.
In general, a space line parallel to the reference vector d shown in equation (1) passing the point (X0, Y0, Z0) is expressed by equation (2).

  If the angles (θx1, θy1, θz1) with the X axis, Y axis, and Z axis in a three-dimensional space are known, the RF tag detection vector becomes (cos θx1, cos θy1, cos θz1) as shown in FIG. . Therefore, if the angles (θx1, θy1, θz1) and the angles (θx2, θy2, θz2) are known, the equations (3) and (4) hold.

  From these relational expressions, the position (X, Y, Z) of the RF tag 1 to be specified is the position (X1, Y1, Z1), (X2, Y2) of the two receiving antennas 5 which are fixed known positions. , Z2), angles (θx1, θy1, θz1) and (θx2, θy2, θz2) representing the orientations of the two receiving antennas 5 obtained by the antenna rotator 6, and analytically by solving the simultaneous equations It is possible to ask.

  As described above, by separating the transmitting antenna 3 and the receiving antenna 5 as separate bodies, long distance reception by high sensitivity antenna becomes possible in the receiving antenna 5, and the transmitting range t becomes wide in the transmitting antenna 3. can do. Therefore, it is possible to realize physical distribution management and position management of products and the like in a wide area by using the general-purpose passive RF tag 1.

As mentioned above, although the present invention was explained with an embodiment, the above-mentioned embodiment shows only an example of the embodiment in the case of carrying out the present invention, and the technical scope of the present invention is interpreted restrictively by these. It is a must-have. That is, the present invention can be implemented in various forms without departing from the technical concept or the main features thereof.
For example, although FIG. 1 shows an example in which a plurality of transmitters 2 and transmission antennas 3 are installed in a set, and a plurality of transmission antennas 3 are provided, one transmitter 2 may be provided for a plurality of transmission antennas 3. . The same applies to the receiver 4 and the receiving antenna 5.
In addition, although the passive type RF tag 1 of 920 MHz band is taken as an example, the size, shape, and frequency band of the passive type RF tag are not limited.

1: RF tag 2: transmitter 3: transmitting antenna 4: receiver 5: receiving antenna 6: antenna rotator 7: concentrator 8: information processor 9: object

Claims (8)

Passive RF tags,
A transmitting antenna for transmitting radio waves to the RF tag;
A wireless communication system, comprising: a receiving antenna separate from the transmitting antenna for receiving a radio wave from the RF tag that operates by receiving a radio wave transmitted from the transmitting antenna.   The wireless communication system according to claim 1, wherein the receiving antenna is a directional antenna.   The wireless communication system according to claim 1 or 2, wherein a plurality of the transmitting antennas are installed.   The wireless communication system according to any one of claims 1 to 3, wherein a plurality of the receiving antennas are installed.   The wireless communication system according to claim 2, wherein the receiving antenna is supported by a support device, and the direction of the receiving antenna is variable.   6. The control apparatus according to claim 5, further comprising: control means for controlling so as to transmit radio waves from the transmitting antenna, and controlling so as to change the direction of the receiving antenna in accordance with the position of the transmitting antenna. Wireless communication system.   The wireless communication system according to claim 2, further comprising: position specifying means for specifying a position of the RF tag based on radio waves received from the RF tag via the receiving antenna.   8. The wireless communication system according to claim 7, wherein the position specifying means obtains the position of the RF tag in an intersection area in which the reception ranges of the two reception antennas are crossed.

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