JP2007304874A - System and device for specifying location of radio ic tag - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To accurately specify the location of a radio IC tag even when the intensity of a radio signal, that a reader/writer receives from the radio IC tag, does not reach an intensity to be essentially obtained due to some factor by fluctuating or the like. <P>SOLUTION: This locationspecification system includes: a plurality of reading means (for example, reader/writers) for reading identification information from an identification information holding device (for example, a radio IC tag) wherein identification (for example, a peculiar ID) is stored; and a location specifying means (for example, a location specifying device) for using the number of times of success, which is the number of times of successfully reading identification information when the identification information was read by the reading means a plurality of times, to calculate a position of the identification information holding device having the identification information stored therein. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a position determination device that determines the position of a wireless IC tag.

  In recent years, due to advances in semiconductor technology and IT technology, high-performance chips suitable for wireless IC tags have been supplied, such as ensuring communication distance without batteries, and the expansion of application fields associated with this As a result of mass production by, the introduction of wireless IC tags (also referred to as RFID, RF tags, and electronic tags) is rapidly expanding as a result of price reductions.

Wireless IC tags have begun to be used for the purpose of managing items by attaching identification codes to items such as products (automatic recognition). However, not only such automatic recognition but also a method of using that to determine the position has been proposed. The For example, a system in which a wireless signal transmitted from a wireless IC tag, such as load modulation, is read by a reader / writer, information received by the reader / writer is transmitted to a server, and the position of the wireless IC tag is specified by the server Has been proposed (for example, Patent Document 1).
Japanese Unexamined Patent Publication No. 2005-303402

  In the conventional system for specifying the position as described above, the reader / writer measures the intensity of a radio signal such as load modulation received from the wireless IC tag, and based on the intensity, the reader / writer uses the wireless IC tag. It is conceivable to determine the position based on the distance and the distance.

  However, the intensity of wireless signals such as load modulation received by the reader / writer from the wireless IC tag easily changes depending on factors such as the directivity of the antenna of the wireless IC tag, the radio wave reception environment, and the presence of obstacles. There is a problem that it is difficult to specify the exact position.

  The object of the present invention is to accurately position the wireless IC tag even if the intensity of the wireless signal such as load modulation received by the reader / writer from the wireless IC tag fluctuates or does not reach the intensity that should be originally obtained due to some factor. It is to provide a technology that can be specified.

  As means for solving the above problems, the present invention has the following features.

  The first aspect of the present invention is proposed as a location system.

  The position specifying system includes a plurality of reading means (for example, reader / writer) that reads identification information from an identification information holding device (for example, a wireless IC tag) that stores identification information (for example, a unique ID), and a reading means. As a result of reading the identification information a plurality of times, a position specifying unit (for example, calculating the position of the identification information holding device storing the identification information using the number of successes that is the number of times the identification information has been successfully read) A position specifying device).

  According to this invention, the position of the identification information holding device can be specified without being affected by fluctuations in radio wave intensity from the identification information holding device due to passage of an obstacle or the like.

  The position specifying means further records the signal intensity such as load modulation received from the identification information holding device when the identification information is successfully read, and uses the signal intensity such as load modulation together with the number of successes to identify the identification information. May be calculated. Furthermore, with the aim of eliminating null points, etc., more readings can be performed while changing the frequency (channel) of the radio waves for reading from multiple reading means and changing the phase and polarization direction. It is also possible to comprehensively calculate the position from the information of the wireless IC tag that succeeded.

  According to this invention, it becomes possible to specify a position with higher accuracy.

  The second aspect of the present invention is proposed as a position specifying device.

The position specifying device reads a plurality of times by a plurality of reading means (for example, reader / writer) that reads the identification information from an identification information holding device (for example, a wireless IC tag) that stores the identification information (for example, a unique ID). A reading instruction unit for executing processing, and a reading unit that receives the number of successful readings for each identification information, which is information obtained as a result of the reading unit reading the identification information a plurality of times, and reads the number of successes for each identification information It is characterized by having a reading result storage unit that records each time and a position calculation unit that calculates the position of the identification information holding device by using the number of successes for each identification information recorded for each reading unit.

  According to this invention, the position of the identification information holding device can be specified without being affected by fluctuations in radio wave intensity from the identification information holding device due to passage of an obstacle or the like.

  According to the present invention, position detection by reading an IC tag can be performed with higher accuracy without being affected by fluctuations in radio wave propagation conditions.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[1. Example of position detection system configuration]
FIG. 1 is a block diagram illustrating a configuration example of a position specifying system according to the present embodiment.

  The position specifying system 1 controls the reading operation of the reader / writer 10 for reading the wireless IC tag and the reader / writer 10 and the number of successful readings regarding the unique ID of the wireless IC tag 20 read by the reader / writer 10. Alternatively, the position identification device 30 identifies the position of the wireless IC tag based on the success rate.

[1.1. Reader / Writer]
FIG. 2 is a functional block diagram showing a configuration example of the reader / writer 10.
The reader / writer 10 includes a control unit 101 including a CPU, a circuit connected to the control unit 101, a transmission / reception unit 102 that is a circuit that performs wireless transmission / reception such as modulation, demodulation, and amplification, and a transmission / reception unit And an antenna 103 connected to 102. The control unit 101 receives a command from the position specifying device 30, drives the transmitting / receiving unit 102 in accordance with the command, and specifies the data output from the transmitting / receiving unit 102 (such as a unique ID read from the wireless IC tag 20). It has a function of passing to the device 30.

  The transmission / reception unit 102 has a function of performing wireless communication with the wireless IC tag 20 via the antenna 103. The transmission / reception unit 102 includes a modulation unit 104 and a demodulation unit 105. The modulation unit 104 modulates a signal corresponding to information such as a predetermined command, request, and command received from the control unit 101 with a predetermined modulation method to generate a carrier wave. The demodulator 105 demodulates the carrier wave modulated by a predetermined modulation method based on the signal corresponding to the data stored in the wireless IC tag 20, takes out the signal corresponding to the data, and passes it to the controller 101. .

The antenna 103 radiates a carrier wave received from the transmission / reception unit 102, more specifically the modulation unit 104, in the air, radiates a radio wave toward the wireless IC tag 20, and performs load modulation or the like radiated from the wireless IC tag 20. The carrier wave is received, and this carrier wave is supplied to the transmission / reception unit 102, more specifically to the demodulation unit 105.
Note that the antenna 103 is not necessarily stored in the housing of the reader / writer 10, and may be an antenna unit separate from the reader / writer 10 main body. The antenna unit includes a transmitting antenna / receiving antenna and a case for protecting the antenna. The antenna unit is a separate device or unit from the reader / writer main body in which the control unit 101 and the transmission / reception unit 102 are stored, and is connected to the reader / writer main body by a cable or the like. Therefore, the antenna unit can be installed even in a place away from the reader / writer main body. A plurality of antenna units, which are installed at different locations, may be connected to one reader / writer main body, and the reader / writer main body may be used while switching between the plurality of antenna units.

  Further, as another configuration example, the present embodiment can also be configured as a configuration in which one antenna unit of a plurality of antenna units connected to the reader / writer 10 is incorporated in the reader / writer 10.

[1.2. Wireless IC tag]
FIG. 3 is a functional block diagram showing a configuration example of the wireless IC tag 20.

  The wireless IC tag 20 includes a memory 201, a control unit 202, a transmission / reception unit 203, and an antenna 204. The memory 201 is a storage device that stores information to be read such as identification information (unique ID) such as product information and shipper information. (For the flexibility of the system configuration, the wireless tag may have only a unique unique ID, and identification information such as product information and shipper information may be held in a DB connected to the upper side.) 202 interprets a command, request, command, etc. from the reader / writer 10 and executes an operation in response thereto. Similar to the reader / writer 10, the transmission / reception unit 203 includes a modulation unit (not shown) and a demodulation unit (not shown), and modulates / demodulates signals in order to communicate with the reader / writer 10. The antenna 204 receives the carrier wave from the reader / writer 10 and supplies and feeds the carrier wave to the transmission / reception unit 203, receives the modulated carrier wave from the transmission / reception unit 203, and causes the reader / writer 10 to receive it. Radiates into the air.

[1.3. Positioning device]
The position specifying device 30 controls the reading operation of the reader / writer 10 and determines the position of the wireless IC tag based on the number of successful readings or the success rate related to the unique ID of the wireless IC tag 20 read by the reader / writer 10. Has a function to identify. The position specifying device 30 includes an arithmetic processing unit (CPU), a main memory (RAM), a read only memory (ROM), an input / output device (I / O), and, if necessary, an external storage device such as a hard disk device. An information processing apparatus such as a computer or a workstation. A program for causing the information processing device to function as the position specifying device 30 or a program for causing the computer to execute the position specifying method is stored in the ROM or the hard disk device, and this program is placed on the main memory. When the CPU executes this, the position specifying device 30 is realized or the position specifying method is executed.

FIG. 4 is a functional block diagram showing an example of the position specifying device 30.
The position specifying device 30 includes a reading instruction unit 301, a reading result storage unit 302, and a position calculation unit 303.
The reading instructing unit 301 has a function of issuing an instruction to the reader / writer 10 to execute a predetermined number of reading processes when performing position specification. Each reader / writer 10 executes a predetermined number of reading processes in accordance with this command. In this embodiment, the predetermined number of times is assumed to be 100. However, the predetermined number of times may not be a fixed number, and the predetermined number may be appropriately changed according to the communication environment in the environment where the position specifying system 1 is installed. The predetermined number of times may be set differently for each reader / writer 10.

  In each reading process, each reader / writer 10 communicates with all the wireless IC tags 20 existing in the communication area of the reader / writer 10, and all the unique IDs that have been successfully read as a result of the communication are located in the position specifying device 30, More specifically, the reading result storage unit 302 is notified.

  The reading result storage unit 302 has a function of storing the reading result notified by each reader / writer 10. FIG. 5 shows an example of read result data stored in the read result storage unit 302. The read result data shown in FIG. 5 shows an example in which the read result from a certain reader / writer is stored as a table. Such a table 50 is stored in the reading result storage unit 302 for each reader / writer 10 one by one.

  The table 50 has one record 501 for each unique ID read by the reader / writer 10. Each record 501 includes a unique ID field 502 for storing a unique ID, a result of the first reading process, a first field 503 for storing whether or not the corresponding unique ID has been successfully read, and a result of the second reading process. , A second field 504 for storing whether or not the corresponding unique ID has been successfully read, and a third field 505 for storing whether or not the corresponding unique ID has been successfully read as a result of the third reading process. (The fourth to 99th fields are not shown). As a result of the 100th reading process, which is the predetermined number of times, the 100th field 506 stores whether or not the corresponding unique ID has been successfully read. Of the read processing results up to, a success count field 507 for storing the number of successful reads, and the success count Has an estimated distance field 508 determined based on.

  The unique ID field 502 stores a unique ID notified from the reader / writer 10. Since one unique ID is stored in one record, for example, when 50 unique IDs are read in one reading operation, 50 records 501 are created in the table 50. It becomes.

  The first-time field 503 to the 100th-time field 506 store information indicating whether or not the corresponding unique ID has been notified from the reader / writer 10 as a result of the reading process at that time. In this example, “1” indicates that the corresponding unique ID is notified from the reader / writer 10 in the reading process result of that time, that is, “0” indicates that the corresponding unique ID is in the reading process result of that time. This indicates that notification from the reader / writer 10 has not been made, that is, reading of the wireless IC tag 20 having the unique ID has failed.

  The number-of-success field 507 includes the number of fields in which information indicating that the corresponding unique ID is notified from the reader / writer 10 among the first-time field 503 to the 100th-time field 506, that is, in the record 501. The number of successful readings of the wireless IC tag having the corresponding unique ID is stored.

  In the estimated distance field 508, a distance estimated based on the number of successes stored in the success number field 507, that is, an estimated distance between the wireless IC tag having a unique ID corresponding to the record and the reader / writer 10 is calculated. Stored. The estimated distance is information calculated by a position calculation unit 303 described later, and is a part of the table 50 in this example, but is not necessarily a part of the table 50.

  As described above, one table 50 is created for each reader / writer 10.

  The position calculation unit 303 calculates an estimated distance between each reader / writer 10 and the wireless IC tag 20 having each unique ID based on the number of successes stored in the success number field 507, and based on each estimated distance, The wireless IC tag 20 having each unique ID is calculated.

  FIG. 6 shows an example of data used by the position calculation unit 303 to calculate the estimated distance from the number of successes. The data shown in the figure is a graph for uniquely determining the estimated distance according to the value of the number of successes (vertical axis). For example, when the number of successes is 100, the estimated distance is 0, when the number of successful times is 50, the estimated distance is L, and when the number of successful times is 25, the estimated distance is 2L. Such data can be created by taking statistics of the number of successes while changing the distance between the wireless IC tag 20 and the reader / writer 10, but even if such data is created by other methods. I do not care.

  FIG. 7 shows an example of a table that stores the result of the position calculation unit 303 calculating the estimated position of the wireless IC tag 20 based on the estimated distance calculated from the number of successes. In this example, it is assumed that the position is specified by using two different reader / writers 10 (hereinafter referred to as reader / writer A and reader / writer B). This table 70 has one record 701 for each unique ID. Each record 701 includes a unique ID field 702 for storing a unique ID, a first estimated distance field 703 for storing an estimated distance from the reader / writer A, and a second estimated distance field 704 for storing an estimated distance from the reader / writer B. , And an estimated position field 705 for storing the estimated position of the wireless IC tag 20 corresponding to the unique ID.

  The estimated position stored in the estimated position field 705 is calculated by the position calculation unit 303 based on the estimated distances stored in the first estimated distance field 703 and the second estimated distance field 704. FIG. 8 is a conceptual diagram of a method for calculating an estimated position based on the estimated distances stored in the first estimated distance field 703 and the second estimated distance field 704. In this example, two reader / writers A and B are provided in a certain space (for example, a warehouse). The position of the reader / writer A is point P, and the position of the reader / writer A is point Q.

  Assume that the estimated distance between a certain wireless IC tag 20 and the reader / writer A is L1, and the estimated distance between the wireless IC tag 20 and the reader / writer B is L2. Then, it is considered that this wireless IC tag exists on a circle 801 having a radius L1 centered on the point P and satisfying a circle 802 having a radius L2 centered on the point P. That is, the estimated position of the wireless IC tag 20 can be obtained by obtaining the intersection of the circle 801 and the circle 802.

  Note that the estimated position is not necessarily coordinate information, and information specifying an area having a certain spread (for example, individual sections obtained by dividing a space into 16 sections) may be used as the estimated position. In the example shown in FIG. 8, since there are two intersections, the coordinates cannot be uniquely determined. In such a case, an area including these two intersections may be set as the estimated position.

  The estimated position calculated as described above is stored in the estimated position field 705 of each record 701. By referring to this table 70, the position specifying device 30 can output the estimated position for each unique ID and provide the user with the estimated position of each wireless IC tag.

[2. Modifications, etc.]
(1) In the above embodiment, it has been described that the estimated distance is determined based on the number of successes. However, even if the estimated distance is determined based on the success probability (the number of successes / the total number of reading processes), the present invention. Holds.

  (2) In addition to the number of successful readings described above, the radio wave intensity at the time of successful transmission of each response from the wireless IC tag 20 is recorded, and the estimated distance is calculated based on the number of successful times and the radio wave intensity. Then, the estimated distance of the position may be calculated from the estimated distance of both.

Block diagram showing a configuration example of the location system Functional block diagram showing a configuration example of a reader / writer Functional block diagram showing a configuration example of a wireless IC tag Functional block diagram showing an example of a position specifying device The figure which shows an example of the reading result data which a reading result memory | storage part memorize | stores The figure which shows an example of the data which a position calculation part uses in order to calculate an estimated distance from the frequency | count of success The figure which shows the example of the table which stores the result which the position calculation part calculated the estimated position of the wireless IC tag 20 based on the estimated distance calculated from the frequency | count of success. Conceptual diagram of a method for calculating an estimated position based on estimated distances stored in the first estimated distance field and the second estimated distance field

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Position specification system 10 ... Reader / writer 20 ... Wireless IC tag 30 ... Position specification apparatus 301 ... Reading instruction | indication part 302 ... Reading result memory | storage part 303 ... Position calculation part

Claims (3)

A plurality of reading means for reading the identification information from the identification information holding device storing the identification information;
As a result of causing the reading means to read the identification information a plurality of times, a position specification that calculates the position of the identification information holding device that stores the identification information using the number of successes that is the number of times the identification information has been successfully read. Means,
A location system characterized by comprising:   The position specifying means further records the signal strength received from the identification information holding device when each identification information is successfully read, and stores the identification information using the signal strength together with the number of successes. The position specifying system according to claim 1, wherein the position is calculated. A reading instruction unit that causes a plurality of reading units that read identification information from the identification information holding device that stores the identification information to execute a plurality of reading processes;
A reading result storage unit which receives the number of successful readings for each identification information, which is information obtained as a result of the reading means reading the identification information a plurality of times, and records the number of successes for each identification information for each reading means When,
A position specifying device, comprising: a position calculation unit that calculates the position of the identification information holding device by using the number of successes for each piece of identification information recorded for each reading unit.

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