JP6059607B2 - Wireless tag search method and apparatus - Google Patents

Description

  The present invention relates to a search method and a search device using a wireless device, and more specifically to a method and device for searching for the position of a wireless tag using a wireless device.

  The wireless tag is attached to an identification target such as a product or a person, and is used for logistics management or entrance / exit management of a station or a company. For example, a wireless tag stores therein attribute information related to an identification target such as a product to which the tag is attached, and the attribute information and current position of the product to which the tag is attached are accessed from a user wireless terminal. Used for user identification.

  As means for searching for the current position of an active wireless tag, for example, the following wireless search device is known. First, the wireless search device requests the wireless tag to transmit an ID number. Subsequently, the wireless search device that has received the electromagnetic wave transmitted by the wireless tag estimates the distance and direction from the wireless device to the wireless tag based on the reception intensity of the electromagnetic wave and the arrival direction of the electromagnetic wave. Finally, the wireless search device displays the estimated position in association with the ID number of the wireless tag.

  In addition, the wireless search device that intermittently receives the radio wave from the radio tag detects the direction corresponding to the maximum radio wave intensity among the received radio wave intensity measured over 360 degrees around the center, and A technique for estimating the direction in which a detected wireless tag exists is known. At this time, in order to scan the direction in which the wireless tag is located in all directions of 360 degrees around, the beam directivity is applied to the antenna directivity over all directions of 360 degrees around the signal reception. The technology to change is also known.

  In Patent Document 1, a radio monitoring station detects an orientation corresponding to a signal arrival angle (received beam direction) from a radio transmission source based on antenna directivity control, thereby detecting the direction in which the radio transmission source is located. The technology to do is disclosed. For example, in the invention disclosed in Patent Document 1, the wireless tag is equipped with a plurality of directional antennas, and periodically transmits the distance measurement signal and the direction measurement signal while switching the plurality of directional antennas. The mobile terminal that has received the signal measures the phase of the distance measurement signal to calculate the distance from the wireless tag, measures the phase difference of the direction measurement signals respectively corresponding to the plurality of directional antennas, and wirelessly The direction in which the tag is located is calculated.

  However, the wireless monitoring station described in Patent Literature 1 transmits a signal to one or more wireless tags scattered around by controlling the directivity of the transmission beam, and the directivity of the reception beam is 360 degrees around the omnidirectional. It is necessary to rotate it over. In order to perform positioning of a radio transmission source with high accuracy using such a radio monitoring station, it is complicated and expensive to precisely control the beam directivity of a transmission / reception antenna and timing synchronization of positioning signals with high accuracy. It is necessary for the radio monitoring station to have a simple antenna control mechanism.

  Therefore, in order to perform a wireless tag search by a wireless search device that does not have such a complicated and expensive antenna control mechanism, for example, a user holding the wireless search device rotates his body on the spot, It is necessary to scan the arrival direction of the electromagnetic wave from the wireless tag over all directions of 360 degrees. However, in that case, the estimation accuracy of the arrival direction and propagation distance of the electromagnetic wave from the wireless tag may be lowered depending on the surrounding environment.

  On the other hand, the inventions described in the following Patent Documents 2 to 5 are a technique for improving the estimation accuracy of the current position related to a wireless transmission source such as a wireless tag. A technique for combining or synthesizing auxiliary information is disclosed. As a result, the inventions described in Patent Documents 2 to 5 are more specific than the case where the position of the wireless tag is measured using a single positioning signal received from a single positioning signal supply source, as will be specifically described below. The position of the wireless tag can be measured with high accuracy.

  For example, in Patent Document 2, a ranging signal is communicated between a wireless tag attached to an automated transport vehicle that carries parts and the like and three base stations that are geographically distributed and transmitted to a positioning terminal. A technique for triangulating the position of a wireless tag on an automatic transport vehicle based on three ranging signals acquired from three base stations by a positioning terminal is disclosed.

  Patent Document 3 discloses a positioning method in which a GPS positioning terminal acquires positioning information including ephemeris information based on a GPS signal received from a GPS satellite and includes orbit information of the GPS satellite based on a radio signal received from a base station. Disclosed is a technique for acquiring auxiliary information and performing positioning based on a common part of ephemeris information and positioning auxiliary information.

  In addition to Patent Document 3, Patent Document 4 also discloses a positioning technique that uses both a GPS satellite and a base station. However, positioning auxiliary information received from a base station includes ephemeris information (satellite orbit information) and time synchronization with the satellite. Contains information about.

  Patent Document 5 discloses the positioning of a satellite used for positioning by performing positioning of a mobile terminal using not only a GPS signal transmitted from a GPS satellite but also a positioning signal transmitted from a cellular network base station. Disclosed is a technique for replenishing the shortage of positioning signals by using positioning signals from cellular network base stations in combination even when the number is small.

JP 2006-071380 A JP-A-2005-241301 JP 2004-093378 A JP 2004-085209 A JP 2010-169688 A

  As described above, a wireless search device having an inexpensive and simple configuration that does not have a complicated and expensive mechanism for directivity control of transmission / reception beams and timing synchronization control of positioning signals is used, and positioning accuracy is not deteriorated. There is a need for a positioning system for performing searches for wireless tags. However, in the invention described in Patent Document 2, the positioning signal that the base station communicates with the wireless tag measures only the distance, and the direction in which the wireless tag is located from the arrival direction of the radio wave carrying the positioning signal. Is not an estimate. Therefore, even when the current position of the wireless tag is expressed as a two-dimensional coordinate instead of a three-dimensional coordinate, three or more base stations are required to communicate the positioning signal with the wireless tag.

  In the inventions described in Patent Documents 3 to 5, the current position of the mobile radio device that is to be positioned using the GPS positioning system and the base station is, for example, a three-dimensional coordinate such as a combination of latitude, longitude, and altitude. The geographically absolute coordinate position represented. Moreover, in many cases, clock times are not synchronized between a plurality of GPS satellites and between a GPS satellite and a base station. Therefore, in order to accurately evaluate the propagation delay time of the positioning signal, which is the basis of the position estimation calculation for positioning, with respect to all GPS satellites and base stations, the clock time between all GPS satellites and base stations. It is necessary to correct the deviation. Therefore, unlike the case of triangulation by three base stations described in Patent Document 2, in the invention described in Patent Document 5, a positioning target represented by three-dimensional coordinates is considered in consideration of the necessity of clock time correction. In order to estimate the current position, four or more GPS satellites or base stations are required. The inventions described in Patent Document 3 and Patent Document 4 use ephemeris information, positioning assistance information, and the like together so that necessary positioning accuracy can be obtained even when there are three or less GPS satellites or base stations. However, providing a mechanism for generating such auxiliary information in a positioning system other than the GPS system makes the positioning system very complicated and expensive.

  On the other hand, when positioning the current position with respect to the wireless tag, the current position of the wireless tag to be positioned does not have to be a geographically absolute position in view of the use and field of use of the wireless tag described later. A relative position based on the position of the user who is the positioning subject is sufficient. Further, when positioning the current position with respect to the wireless tag, it is sufficient if the current position of the wireless tag to be measured is obtained as a combination of the direction in which the wireless tag is located and the distance to the wireless tag when viewed from the user.

  In view of the above problems, the present invention provides a wireless tag search device that is inexpensive without providing a complicated and expensive antenna control mechanism for controlling the antenna beam directivity and timing synchronization of positioning signals with high accuracy. The purpose is to realize a simple but highly accurate RFID tag positioning system. In addition, the present invention estimates the relative direction and distance only where the wireless tag is located, thereby minimizing system configuration without requiring positioning signal communication with a large number of satellites and base stations. The purpose is to realize a highly accurate RFID tag positioning system.

  As described above, the present invention is a wireless search device that searches for the wireless device based on wireless signals received from one or more wireless devices and supporting wireless stations, and a position estimation unit that estimates the position of the wireless device And a radio transmission / reception unit for transmitting / receiving the radio signal, wherein the position estimation unit is: first based on the radio signal received from the radio and the support radio station, with respect to positions of the radio and the support radio station And a means for generating a second estimation result relating to the position of the radio using a support signal received from the support radio station together with the first estimation result. The support signal includes distance information on the distance to the radio measured by the support radio station, and the second estimation result is a position of the radio more than the first estimation result. Identifying with high precision, and wherein the.

  Further, in the present invention, the means for generating the second estimation result includes: means for calculating a region separated from the region represented by the first estimation result by the distance represented by the distance information with respect to the estimated position of the supporting radio station. Means for calculating an intersection area between the calculated area and an area represented by the first estimation result with respect to an estimated position of the radio; and outputting information representing the intersection area as the second estimation result; Means.

  Further, in the present invention, the positions of the wireless device and the supporting wireless station are represented by a direction and a distance in which the wireless device and the supporting wireless station are located when viewed from the wireless search device, and the first estimation result is , Including the estimation result regarding the direction and distance in which the radio device and the supporting radio station are respectively located, and the second estimation result is more accurate than the first estimation result regarding the direction and distance in which the radio device is positioned Including the estimation result.

  Further, in the present invention, the support radio station estimates a distance to the radio based on a received electric field strength of the radio signal received from the radio, and outputs the support signal based on the estimated distance. It produces | generates and transmits to the said radio | wireless search apparatus, It is characterized by the above-mentioned.

  Further, in the present invention, the wireless search device further includes a sensor that detects a change in the direction of the wireless search device when a user holding the wireless search device changes direction, the position estimation unit includes: Means for recording, as a measurement result, a change in reception intensity of the radio signal in association with a change in the direction detected by the sensor when the user changes the orientation; the radio is located from the recorded measurement result; Means for estimating a direction to travel.

  The present invention provides an inexpensive and simple but highly accurate antenna search device without providing a complicated and expensive antenna control mechanism for controlling the beam directivity of antennas and timing synchronization of positioning signals with high accuracy. A wireless tag positioning system can be realized. In addition, the present invention estimates the relative direction and distance only where the wireless tag is located, thereby minimizing system configuration without requiring positioning signal communication with a large number of satellites and base stations. A highly accurate RFID tag positioning system can be realized.

Overall configuration diagram of radio communication system according to the present embodiment The figure which shows the hardware constitutions of the radio | wireless tag which concerns on embodiment to this invention, a tag search device, and a radio | wireless transmitter / receiver The figure explaining the function which a wireless tag search application provides to a user The figure which shows the functional block structure of the tag search apparatus which concerns on embodiment of this invention The figure which shows the relationship between the electric field strength of the signal received from the wireless tag, and the distance to a wireless tag The figure explaining an example of a motion of the tag search device in a state where the user has the tag search device in his hand The figure which shows the change of the measured electric field strength and the output value from each sensor according to the change of the direction of the tag search device The figure which shows the state change from the time of the operation | movement which a user moves a tag search device to the end time The figure explaining the position estimation result which spreads in the area of a certain range because the accuracy which presumes a wireless tag position is low The figure which shows the signal communication performed between the three of the tag search device, the wireless tag, and the wireless transceiver for the positioning of the wireless tag The figure which shows the positioning result by the tag search device and the wireless transceiver, and the composition operation of these positioning results on the radar chart screen of the tag search device Event flow diagram for explaining the operation flow executed between the tag search device, the wireless tag and the wireless transceiver for positioning of the wireless tag

<1> Outline The wireless tag is attached to an identification target such as a product or a person, and is used for logistics management or entrance / exit management of a station or company. Wireless tags are roughly classified into passive types and active types.

  The passive wireless tag does not have a built-in battery, generates electric power required inside by radio waves from an external reader / writer, and communicates with the reader / writer in response to a call from the reader / writer. Although the communication range cannot be made large and is about 1 m at the maximum, it can be downsized and the operation can be made permanent.

  On the other hand, an active type wireless tag has a battery inside and transmits radio waves to an external receiver. Since the battery is built in, the communication range is as wide as 10 to 20 m, but there is a difficulty in that the battery cannot be downsized because of the built-in battery and the battery has a lifetime. However, since information can be sent spontaneously, various applications can be considered by making good use of its functions. For example, when searching for an identification target existing in an unspecified location, an active wireless tag is more suitable than a passive wireless tag.

  As such an active wireless tag, a small wireless tag using a short-range wireless communication standard such as Bluetooth (registered trademark) is known. For example, small tags using Bluetooth Low Energy Wireless Technology are provided. As another example, there is a method in which a GPS module is mounted on a wireless tag in addition to the wireless module, and the tag location is estimated from the position of the GPS module.

  The system according to the present embodiment is a system that estimates the distance and direction in which an active wireless tag is located. Specifically, in this system, the radio search device measures the intensity level of the received signal from the active type radio tag while the user holding the radio search device makes one rotation in all directions of 360 degrees around. Then, by recording the measurement result together with the change in the direction of the wireless search device, the direction in which the wireless tag is located is estimated. At this time, the wireless search device detects a change in the direction of the wireless search device using a dynamic sensor such as a gyro sensor or a geomagnetic sensor built in the wireless search device. In this embodiment, in the above-described system, the direction in which the active wireless tag is located is estimated based on the intensity level of the received signal from the active wireless tag measured during one rotation over 360 degrees. A technique for overcoming the problem that accurate direction estimation is difficult due to estimation errors is disclosed.

<2> Configuration of Radio Communication System According to this Embodiment (2-1) Overall Configuration of Radio Communication System An example of the overall configuration of the radio communication system will be described below using FIG.

  One embodiment of a wireless communication system includes a tag searching device 100 used by a user as a portable wireless user terminal device for searching for a wireless tag, and a wireless tag 200n that is an active wireless tag (n is an integer of n> 0) ) And a wireless transceiver 700. FIG. 1 shows a case where n = 4 as an example. The value of n may be 1 to 3, or 5 or more.

  The wireless tag 200n may be called a slave unit. The wireless tag 200n has a short-range wireless communication module. For example, the wireless tag 200n may be a small wireless tag that performs short-range wireless communication according to Bluetooth Low Energy Wireless Technology. The wireless tag 200n is affixed to various things. For example, the wireless tag 200n may be affixed to what is not desired to be lost. In one embodiment of the wireless communication system, the wireless tag 200n is attached to a key, a remote controller, an umbrella, a wallet, or the like.

  Since the wireless tag 200n is an active wireless tag, the wireless tag 200n is driven by a built-in battery and can spontaneously transmit a wireless signal to another wireless device. The wireless tag 200n can intermittently transmit an Advertising signal at a constant cycle in order to inform its current position, and the transmission cycle of the Advertising signal is set by a setting command from a parent device described later. It is possible. The wireless tag 200n can also notify the parent device of the current transmission cycle and transmission output of the Advertising signal.

  Tag search device 100 may be referred to as a parent device. The short-range wireless communication module of the tag searching device 100 performs wireless communication with the short-range wireless communication module of the wireless tag 200n. The tag search device 100 measures the electric field strength of the radio wave from the wireless tag 200n. A sensor built in the tag search device 100 detects the dynamics of the tag search device 100. The tag search device 100 estimates the position of the wireless tag 200n based on the electric field strength of the radio wave from the wireless tag 200n and the dynamics detected by the sensor. The tag searching device 100 has a display screen having a user interface that can be intuitively operated by a user such as a GUI (Graphical User Interface), and the display screen displays the position of the wireless tag 200n. The tag searching device 100 can simultaneously identify the plurality of wireless tags by simultaneously estimating the positions of the plurality of wireless tags 200n, and display a list of all the identified wireless tags on the display screen. It is.

  An example of the wireless transceiver 700 is a wireless access point that communicates data signals and control signals with an uplink channel and a downlink channel with a tag search device 100 that also functions as a cellular phone or a wireless user terminal. It is. The wireless transceiver 700 can transmit and receive wireless signals not only between the wireless tag and the tag searching device, but also between the wireless tag and the tag searching device. It is also possible to relay radio signals to be performed. In this case, the wireless signal is a wireless signal used for position estimation of the wireless tag. The wireless transceiver 700 may be a wireless access point including a cellular network base station, a wireless LAN access point, a macro cell base station, a pico cell base station, a femto cell base station, and the like. Alternatively, the wireless transceiver 700 may be any wireless transceiver other than a wireless access point, and may include a wireless relay station (repeater), a wireless ground station, a wireless transceiver having a wireless signal relay function, and the like.

(2-2) 200n wireless tag
FIG. 2A shows an embodiment of the wireless tag 200n.

In one embodiment of a wireless communication system, the wireless tag 200 ₁ is attached to the key, the wireless tag 200 ₂ is attached to the remote control, the wireless tag 200 ₃ is attached to the umbrella, the wireless tag 200 ₄ is affixed to the wallet.

  The wireless tag 200n includes a control unit 201, a notification information transmission unit 202, a wireless communication unit 203, a timing unit 204, a storage unit 205, a battery 206, a transmission / reception antenna 207, and a control signal reception unit 210. It has.

  The control unit 201 can be implemented by a general-purpose microprocessor, a digital signal processor, or the like, and controls the overall operation of the wireless tag 200n.

  The broadcast information transmitting unit 202 is connected to the control unit 201 and the wireless communication unit 203 so as to be interposed between them, and transmits the advertising signal at the transmission cycle set by the tag search device 100 as the base unit. The wireless communication unit 203 is controlled. Specifically, the broadcast information transmission unit 202 counts down the internal counter value by the number of clock pulses set by the control unit 201, and performs wireless transmission of the Advertising signal when the counter value becomes zero. The communication unit 203 is instructed.

  The wireless communication unit 203 is connected to the broadcast information transmission unit 202 and the transmission / reception antenna 207, and performs wireless communication according to a short-range wireless communication standard such as Bluetooth, zigbee, Wi-Fi, or ANT +. It is not limited to Bluetooth, zigbee, Wi-Fi, and ANT +, and the short-range wireless communication module may perform wireless communication according to a short-range wireless communication standard other than these. In one embodiment of the wireless tag 200n, a case will be described in which the wireless communication unit 203 performs short-range wireless communication according to Bluetooth Low Energy Wireless Technology.

  Whenever the advertising signal transmission cycle is newly set by the master unit, the timer unit 204 measures a time length equal to the newly set transmission cycle, and the number of clock pulses corresponding to the measured time length. Is set in the broadcast information transmitting unit 202. At this time, the number of clocks and pulses set by the time measuring unit 204 is output from the time measuring unit 204 to the notification information transmitting unit 202 via the control unit 201.

  The storage unit 205 stores various setting parameters related to the wireless tag 200n. In such a setting parameter, the setting value of the Advertising signal transmission cycle in the standby state in which the wireless tag 200n is not a search target or the current Advertising signal transmission cycle is automatically returned to the setting value of the transmission cycle in the standby state. The waiting time is included.

  The battery 206 supplies power to the notification information transmission unit 202, the wireless transmission / reception unit 203, the time measurement unit 204, the storage unit 205, and the transmission / reception antenna 207 via the control unit 201.

  The control signal receiving unit 210 is connected to the control unit 201 and the wireless communication unit 203 so as to be interposed therebetween. The control signal receiving unit 210 transmits the control signal transmitted from the tag searching device 100 serving as the parent device to control the operation of the wireless tag 200n. A signal is received via the wireless communication unit 203, and a control command included in the control signal is decoded and output to the control unit 201.

(2-3) Tag search device 100
FIG. 2B shows an embodiment of the tag search device 100.

  The tag search device 100 may be any appropriate wireless user terminal that can be used for wireless communication by a user, and includes, for example, a user terminal such as a mobile phone, an information terminal, a personal digital assistant, a portable personal computer, and a smartphone. However, it is not limited to these.

  The tag search device 100 includes a control unit 101, wireless information transmission / reception units 102A / 102B, wireless communication units 103A / 103B, a display unit 104, a storage unit 105, a user input / output unit 106, a sensor unit 107, And a transmission / reception antenna 108A / 108B.

  The control unit 101 can be implemented by a general-purpose microprocessor, a digital signal processor, or the like. The wireless information reception unit 102A / 102B, the display unit 104, the storage unit 105, the user input / output unit 106, the sensor unit 107, and the signal The tag search device 100 is controlled as a whole. The control unit 101 functions according to a program stored in the storage unit 105 and performs predetermined processing. Specifically, the control unit 101 wirelessly uses the electric field intensity of the radio wave from the wireless tag 200n and information indicating the dynamics of the tag search device 100 (the direction and orientation of the tag search device 100 and their changes). The position of the tag 200n is estimated. The position of the wireless tag 200n estimated by the control unit 101 may be a relative position with respect to the tag search device 100. The control unit 101 outputs information representing the position of the wireless tag 200n to the display unit 104.

  The wireless information transmitting / receiving unit 102A is connected to the control unit 101 and the wireless communication unit 103A so as to be interposed therebetween. The wireless information transmitting / receiving unit 102A receives a wireless signal from the wireless tag 200n, and when the received wireless signal is an Advertising signal, the wireless information identification information of the wireless tag 200n is decoded by decoding the information content of the received signal. (Tag ID information) and attribute information of the tag-attached article are extracted and notified to the control unit 101. Thereby, the tag search device 100 can uniquely identify the wireless tag that is the transmission source of the received signal, and can identify the attribute information of the article on which the wireless tag is attached. Further, the wireless information transmitting / receiving unit 102A receives a control command for controlling the operation of the wireless tag 200n from the tag searching device 100 as a base unit from the control unit 101, encodes it as a control signal, and then performs wireless communication. The data is transmitted to the wireless tag 200n via the unit 103A.

  The wireless information transmitting / receiving unit 102B is connected to the control unit 101 and the wireless communication unit 103B so as to be interposed therebetween. The wireless information transmitter / receiver 102B receives the wireless signal from the wireless transmitter / receiver 700, decodes the information content of the received signal, extracts the positioning information related to the estimation of the current position of the wireless tag 200n, and sends it to the controller 101. Notice. Thereby, the tag search device 100 can communicate with the wireless transceiver 700 auxiliary positioning information used in an auxiliary manner to estimate the current position of the wireless tag 200n with high accuracy. Further, the wireless information transmitting / receiving unit 102A receives a control command for the tag searching device 100 to request the wireless transmitter / receiver 700 to transmit necessary information from the control unit 101 and encodes it as a control signal. Then, the data is transmitted to the wireless transceiver 700 via the wireless communication unit 103B.

  The wireless communication units 103A / 103B perform wireless communication in accordance with short-range wireless communication standards such as Bluetooth, zigbee, Wi-Fi, and ANT +. The wireless communication unit 103A performs wireless communication with the search target wireless tag 200n via the antenna 108A, and the wireless communication unit 103B performs wireless communication with the wireless transceiver 700 via the antenna 108B. . Not limited to Bluetooth, zigbee, Wi-Fi, and ANT +, the wireless communication units 103A / 103B may perform wireless communication in accordance with other short-range wireless communication standards. In one embodiment of the tag search device 100, a case where the wireless communication units 103A / 103B perform short-range wireless communication according to Bluetooth Low Energy Wireless Technology will be described. Further, the wireless communication units 103A / 103B measure the electric field strength based on the radio wave from the wireless tag 200n. For example, the wireless communication unit 103 may measure the received signal strength (RSSI: Received Signal Strength Indication, Received Signal Strength Indicator) based on the radio wave from the wireless tag 200n.

  The display unit 104 is configured by a display, for example, and displays a processing state and a processing result by the tag search device 100. The processing state and the processing result include those according to the OS and applications. The display includes a liquid crystal display (LCD), a CRT (Cathode Ray Tube) display, a plasma display (PDP), an organic EL (Electro-Luminescence) display, and the like. When the tag search device 100 is executing the above-described RFID tag search application, the display unit 104 collectively displays the positions of all the wireless tags existing around the tag search device 100, or by the user A search screen is displayed while searching for a specific wireless tag to be searched.

  The storage unit 105 stores various setting parameters related to the wireless tag 200n. In such a setting parameter, the set value of the Advertising signal transmission period in the standby state where the wireless tag 200n is not a search target and the positions of all the wireless tags existing around the tag search device 100 are collectively displayed. The setting value of the Advertising signal transmission period when performing the search, the setting value of the Advertising signal transmission period during the search for the specific wireless tag to be searched by the user, and the like are included.

  Further, the storage unit 105 stores data obtained by the wireless communication unit 103 measuring the measurement value measured by the sensor 107 and the intensity of the received radio wave from the wireless tag 200n. When the control unit 101 stores the measurement value measured by the sensor 107 and the data measured by the wireless communication unit 103 such as the intensity of the radio wave received from the wireless tag 200 n in the storage unit 105, the control unit 101 receives the sensor from the sensor 107. The measurement value and the received radio wave intensity change are associated with each other and stored in the storage unit 105 as received radio wave intensity change data.

  Further, the storage unit 105 stores an application and an operating system (OS: Operating System). The application is software that includes a program that is activated by an instruction command input by the user from the user input unit 106 and that is executed by the control unit 101, and that has a function of performing operations performed by the user on the tag search device 100. . The OS includes a system control program that is automatically started when the tag search device 100 is turned on and executed by the control unit 101. In the tag search device 100, an interface that abstracts hardware is provided to application software. Software. A specific example of such an OS includes Android OS (registered trademark). Note that the application in this embodiment includes a wireless tag search application in which the user searches for the current position of the wireless tag 200n and displays the current position of the wireless tag 200n on the display unit 104 using a GUI.

  The user input / output unit 106 includes, for example, a keyboard and a mouse, and is a device for a user to give an instruction to the tag search device 100 and input data. The user input unit 106 may be configured with a touch panel. In addition, the user input / output unit 106 is configured by a microphone, for example, and inputs a voice uttered by the user. The voice may include a message to the called party and an instruction to the tag search device 100. The instruction includes an instruction for the OS and an application. Further, the user input / output unit 106 may be configured by a speaker, for example, and may output a sound to the user in accordance with a processing state and a processing result by the tag search device 100.

  The sensor unit 107 includes a dynamic sensor, and the dynamic sensor detects a movement of the apparatus including a change in the orientation and posture of the tag search apparatus 100 held by the user. As an example of the dynamic sensor, a dynamic sensor including a geomagnetic sensor 107A, a gyro sensor 107B, an acceleration sensor 107C (see FIG. 4), and the like can be considered. The sensor is not limited to the geomagnetic sensor 107A, the gyro sensor 107B, and the acceleration sensor 107C, and other sensors may be included. The acceleration sensor 107 </ b> C is a sensor that measures angular acceleration (rotational acceleration) and acceleration (linear acceleration) when the direction and orientation of the tag search device 100 change. The gyro sensor 107 </ b> B is a sensor that detects the current orientation of the tag search device 100. The geomagnetic sensor 107A is a sensor that detects an absolute direction such as east, west, south, and north as seen from the tag search device 100 based on geomagnetism.

(2-4) Radio transceiver 700
FIG. 2C shows a device configuration of the wireless transceiver 700. A wireless transceiver 700 shown in FIG. 2C transmits / receives a wireless signal used for position estimation of the wireless tag 200n to be searched between the tag searching device 100 and the wireless tag 200n, and further detects the tag searching device. 100 and a wireless station that relays these wireless signals to be transmitted and received between the wireless tag 200n. The wireless transceiver 700 is an arbitrary wireless device such as a wireless relay station (repeater), a wireless ground station, and a wireless transceiver having a wireless signal relay function in addition to a wireless access point including a base station of a cellular network and a wireless LAN access point. A transceiver may be included. The wireless transceiver 700 includes a control unit 701, a wireless information transmission unit 702A, a wireless information reception unit 702B, a wireless communication unit 703, and an antenna 704.

  The control unit 701 can be implemented by a general-purpose microprocessor, a digital signal processor, or the like, and executes overall control of the wireless transceiver 700 while exchanging signals with the wireless information transmitting unit 702A and the wireless information receiving unit 702B. . The control unit 701 may have a built-in memory that stores information transmitted and received by the wireless transceiver 700 and a control program for controlling the operation of the wireless transceiver 700.

  The wireless information transmitting unit 702A and the wireless information receiving unit 702B are connected in parallel with each other between the wireless communication unit 703 and the control unit 701 so as to be interposed between the wireless communication unit 703 and the control unit 701. The wireless information transmission unit 702A receives from the control unit 101 a control command for the wireless transceiver 700 to request transmission of necessary information to the tag searching device 100 and the m backward tag 200n, and encodes this as a control signal. Then, the data is transmitted to the tag searching device 100 and the wireless tag 200n via the wireless communication unit 703. The wireless information receiving unit 702B receives wireless signals from the tag search device 100 and the wireless tag 200n via the wireless communication unit 703, and decodes the information content of the received signal, thereby determining the current position of the wireless tag 200n. Information necessary for estimation is extracted and notified to the control unit 101.

  The wireless communication unit 703 is connected to the wireless information transmission unit 702A and the wireless information reception unit 702B. The wireless communication unit 703 up-converts the signal received from the wireless information transmission unit 702A into an RF signal and transmits the RF signal from the RF signal antenna 704. Further, the wireless communication unit 703 receives the RF signal received by the antenna 704, down-converts it to a baseband signal, and passes the baseband signal to the wireless information reception unit 702B.

(2-5) Function provided by tag search device 100 to user and usage mode of tag search device 100 Hereinafter, using FIG. 3, the tag search device 100 that is executing the RFID tag search application provides to the user. The function to perform will be described. The RFID tag search application executed on the tag search device 100 can also be implemented as an Android application executed by calling an API of Android OS (registered trademark). In this case, the RFID tag search application is activated when the user taps the corresponding icon on the touch panel screen displaying the Android OS (registered trademark) desktop with a finger.

  The tag searching device 100 searches for the positions of all the wireless tags located in the searchable area, and displays the current positions of all the wireless tags located in the search screen as a two-dimensional map. It is possible to display a list. The searchable area described above is the maximum range in which a signal transmitted from a wireless tag at a location where the tag search device 100 is remote can be received with a reception quality higher than a predetermined quality, and the tag search device 100 Corresponds to a coverage area where wireless communication is possible. The predetermined quality in this case may be a reception quality that allows the tag ID information to be extracted by correctly decoding the reception signal from the wireless tag with a certain probability.

  First, the user swings the tag search device 100 held in his / her hand to the left and right in an arbitrary direction, or makes one rotation on the spot. At this time, the RFID tag searching application executed by the tag searching device 100 stores in the storage unit 105 the strength of the Advertising signal received from each RFID tag and the direction at the time of receiving the signal. Subsequently, the RFID tag search application displays the direction and distance in which all searched RFID tags are located on the radar chart displayed on the display screen of the tag search device 100, centering on the current position of the user. A list is displayed (FIG. 3). When the direction and distance of each wireless tag are displayed on the radar chart, icon images corresponding to the tag ID information of each wireless tag are displayed in a list at positions in the radar chart corresponding to the direction and distance (FIG. 3). ).

FIG. 3 shows a state in which the tag searching device 100 displays a list of the positions of all the wireless tags located in the searchable area as a radar chart on the display screen. In FIG. 3, an icon image 500 located at the center of the radar chart represents the current position of the user who has the tag search device 100 in hand. Each of the plurality of concentric circles displayed in the radar chart represents a circular distance range that increases stepwise around the user position represented by the icon image 500, and the numbers appended to the concentric circles correspond to each other. Represents the radius of the distance range. In FIG. 3, icon images 400 ₁ , 400 ₂ , 400 _3, and 400 ₄ in the radar chart represent the current positions of the four wireless tags located in the searchable area. Icon image 400 ₁ displays the current position of the wireless tag 200 ₁ affixed to the key, the icon image 400 ₂ displays a patch current position of the wireless tag 200 ₂ to the remote control, icon image 400 _3, displays the current position of the wireless tag 200 ₃ affixed to an umbrella, icon image 400 ₄ displays the current position of the wireless tag 200 ₄ affixed to purse.

(2-6) Functional Block Configuration Inside Tag Search Device 100 FIG. 4 is a functional block diagram showing an example of the function of the tag search device 100. The functions represented by this functional block diagram are mainly executed by the control unit 101. That is, the function represented by the functional block diagram of FIG. 4 is executed by the control unit 101 according to the application stored in the storage unit 105. The CPU that executes the function represented by the functional block diagram of FIG. 4 according to the application stored in the storage unit 105 may be referred to as an A-CPU (application-CPU) 300.

  The control unit 101 functions as a behavior determination unit 302. Information representing acceleration is input to the dynamic determination unit 302 from the acceleration sensor 107C. The dynamic determination unit 302 determines whether or not the tag search device 100 has moved based on information representing the acceleration from the acceleration sensor 107C. The dynamic determination unit 302 inputs information indicating whether or not the tag search device 100 has moved to the position estimation unit 304.

  The control unit 101 functions as the position estimation unit 304. Information indicating whether or not the tag search device 100 has moved from the dynamic determination unit 302 is input to the position estimation unit 304. The position estimation unit 304 detects the timing at which the tag search device 100 starts to move and the timing at which the movement ends based on information from the dynamic determination unit 302. The position estimation unit 304 is detected by the wireless communication unit 103 between the timing of starting the movement and the timing of ending the movement after detecting the timing of starting the movement of the tag search device 100 and the timing of ending the movement. The position of the wireless tag 200n is estimated based on the measured electric field strength, the information indicating the geomagnetic direction detected by the geomagnetic sensor 107A, and the information indicating the angular acceleration detected by the gyro sensor 107B.

  The position estimation unit 304 estimates the distance between the tag search device 100 and the wireless tag 200n based on information representing the electric field strength from the wireless communication unit 103. Specifically, the position estimation unit 304 may have a database including a relationship between the electric field strength and the distance.

  FIG. 5 shows an example of the relationship between electric field strength and distance. According to FIG. 5, it is shown that the distance between the tag search device 100 and the wireless tag 200n is shorter (closer) as the electric field strength becomes higher, and the tag search device 100 and the wireless tag 200n are changed as the electric field strength becomes lower. It is shown that the distance between is long (far). Based on FIG. 5, a table in which the electric field intensity and the distance are associated may be prepared.

  The position estimation unit 304 estimates the distance between the tag search device 100 and the wireless tag 200n based on the relationship between the electric field strength and the distance included in the database.

  The position estimation unit 304 calculates the orientation of the tag search device 100 based on information indicating the direction of geomagnetism from the geomagnetic sensor 107A. The position estimation unit 304 calculates the angle and rotation speed of the tag search device 100 based on information representing the angular velocity from the gyro sensor 107B.

  The position estimation unit 304 estimates the position of the wireless tag 200n based on the estimated distance value, the information indicating the azimuth, and the information indicating the angle and the rotation speed. The position estimation unit 304 inputs information indicating the estimated position of the wireless tag 200 n to the user input / output unit 106.

  The user input / output unit 106 displays the position of the wireless tag 200n based on the information representing the position of the wireless tag 200n from the position estimation unit 304.

<3> Method for Estimating Position of Wireless Tag Hereinafter, a method for the tag searching device 100 to estimate the distance and direction where the unspecified wireless tag 200n is located will be described with reference to FIGS. For the sake of simplicity, a description will first be given from the case where an error included in the estimated direction is not taken into consideration. The direction estimation mechanism that takes into account the error included in the result of estimating the direction in which the wireless tag 200n is located by this method will be described later in the description of the embodiments relating to FIG. Generally speaking, the method described below is to detect a change in the direction of the tag search device 100 using a dynamic sensor built in the tag search device 100, and at the same time, relate the tag search device 100 to the change in the direction. A change in radio field intensity received from the wireless tag 200n is recorded, and the orientation of the tag search device 100 is detected based on the record.

The tag searching device 100 activates a wireless tag searching application that estimates the position of the wireless tag 200n. When a wireless tag search application that estimates the position of the wireless tag 200n is activated, a message that prompts the user to move the tag search device 100 is output. A message that prompts the user to swing the tag search device 100 may be output, or a message that prompts the user to tilt the tag search apparatus 100 may be output.
For example, a message such as “Please move the wireless communication device over about 5 seconds to draw a circle around the body” is output. The user may be notified by voice, or the user may be notified by displaying.

  The user moves the tag search device 100 according to the message.

  FIG. 6 shows an example in which the user moves the tag search device 100 according to the message. The user places the tag search device 100 on the palm and makes one rotation around the user himself / herself.

  The process of estimating the position of the tag search device 100 may be started after the tag search device 100 is rotated once around the user, or may be executed in real time when the tag search device 100 is rotated. In one embodiment of the tag search device 100, a case will be described in which the tag search device 100 is started after the tag search device 100 is rotated around the user.

  The position estimation unit 304 detects the timing at which the tag search device 100 starts to move and the timing at which the motion ends based on information indicating whether the tag search device 100 has moved from the dynamic determination unit 302. If the position estimation unit 304 can detect the timing of the start of movement and the timing of the end of movement, the electric field intensity detected by the wireless communication unit 103 between the timing of the start of movement and the timing of the end of movement. Information indicating the direction of geomagnetism detected by the geomagnetic sensor 107A and information indicating angular acceleration detected by the gyro sensor 107B are acquired.

  The position estimation unit 304 estimates the orientation of the tag search device 100 based on information representing the direction of geomagnetism. The position estimation unit 304 obtains an angle and a rotation speed from information representing the angular acceleration, and estimates a movement state of the tag search device 100 based on the angle and the rotation speed. The position estimation unit 304 estimates the distance between the tag search device 100 and the wireless tag 200n based on information representing the electric field strength. Instead of estimating the azimuth of the tag search device 100 based on the information indicating the direction of geomagnetism, the position estimation unit 304 obtains an angle and a rotation speed from the information indicating the angular acceleration, and the tag search device based on the angle and the rotation speed. The state of 100 movements is estimated. In this way, the relative position from the start of movement can be estimated.

  FIG. 7 shows an example of a change in the value detected by each sensor when the tag search device 100 itself is moved. FIG. 7 shows, from the bottom, the acceleration detected by the acceleration sensor 107C, the orientation detected by the gyro sensor 107B and the geomagnetic sensor 107A, and the electric field strength detected by the wireless communication unit 103.

  FIG. 8A to FIG. 8C show a movement in which the user rotates the tag search device 100 itself around the user. 8A to 8C illustrate a case where the wireless tag 200n is located in a direction opposite to the direction in which the user is facing when starting to move.

  When the user starts to move the tag search device 100 itself, the horizontal acceleration detected by the acceleration sensor 107C changes greatly. This corresponds to “beginning of movement” in FIGS. 7 and 8A. The position estimation unit 304 is input with information indicating that it has moved from the dynamic determination unit 302.

  When the user continues to move the tag search device 100 itself, the change in acceleration detected by the acceleration sensor 107C is reduced. This is after the “start of movement” in FIG. 7 and FIG. 8 (A), through “when rotated 180 degrees” in FIG. 7 and FIG. 8 (B), and “at the end of rotation” in FIG. To continue.

  When the user continues to move the tag search device 100 itself and makes one revolution, the change in acceleration detected by the acceleration sensor 107C increases. This corresponds to “at the end of rotation” in FIG. The position estimation unit 304 is input with information indicating that no movement has occurred from the dynamic determination unit 302.

  The position estimation unit 304 detects the timing at which the tag search device 100 starts to move and the timing at which the motion ends based on information indicating whether the tag search device 100 has moved from the dynamic determination unit 302.

  When the timing for starting the movement and the timing for ending the movement are detected, the position estimating unit 304 starts position estimation of the wireless tag 200n.

  At the time of “beginning of movement”, based on the direction detected by the geomagnetic sensor 107A, the position estimation unit 304 estimates, for example, that the user is facing west. In addition, the electric field strength detected by the wireless communication unit 103 at the time of “beginning of movement” is a low value because there is a user between the wireless tag 200 n and the wireless communication terminal 100. The position estimation unit 304 estimates the distance between the wireless tag 200n and the tag search device 100 based on the electric field strength from the wireless communication unit 103.

  Further, the position estimation unit 304 estimates the angle and the rotation speed of the tag search device 100 based on information representing the angular velocity from the gyro sensor 107B after the “start of movement” until the end of the rotation. By estimating the angle and rotation speed of the tag search device 100 based on the information representing the angular velocity from the gyro sensor 107B, it is possible to estimate the relative movement from the “beginning of movement”.

  Further, the position estimation unit 304 may estimate the azimuth facing the radio communication terminal 100 based on the azimuth detected by the geomagnetic sensor 107A. In the example illustrated in FIG. 7, for example, the tag search device 100 is estimated that the user faces from west to north and from north to east.

  In addition, the electric field strength detected by the wireless communication unit 103 gradually increases because the distance between the wireless tag 200n and the wireless communication terminal 100 is reduced. The electric field strength detected by the wireless communication unit 103 is high when there is no obstacle between the wireless tag 200n and the wireless communication terminal 100. The position estimation unit 304 estimates the distance between the wireless tag 200n and the tag search device 100 based on the electric field strength from the wireless communication unit 103. Further, the position estimation unit 304 detects the direction in which the tag search device 100 is facing based on the electric field intensity from the wireless communication unit 103 and information indicating the angular velocity from the gyro sensor 107B. Further, the position estimation unit 304 is directed to the tag search device 100 based on the electric field strength from the wireless communication unit 103, information indicating the angular velocity from the gyro sensor 107B, and information indicating the azimuth from the geomagnetic sensor 107A. You may make it detect the direction which exists. Specifically, since the electric field strength detected by the wireless communication unit 103 at “180 degree rotation” has no obstacle between the wireless tag 200n and the wireless communication terminal 100, and the distance is closest, Maximum. The position estimation unit 304 estimates the distance between the wireless tag 200n and the tag search device 100 based on the electric field strength from the wireless communication unit 103. Furthermore, when the electric field intensity detected by the wireless communication unit 103 is the maximum, the position estimation unit 304 calculates the direction obtained from the angular velocity detected by the gyro sensor 107B and the azimuth detected by the geomagnetic sensor 107A. The direction in which the tag search device 100 is facing is assumed.

  As described above, tag search device 100 according to the present embodiment incorporates a battery inside and receives a signal transmitted from an active wireless tag that transmits radio waves to an external receiver. In addition, the tag search device 100 according to the present embodiment uses a built-in dynamic sensor (such as a gyro sensor or a geomagnetic sensor) when a user holding the device itself makes one turn on the spot. Then, changes in the orientation and posture of the device are detected and correlated with changes in the intensity of the received signal from the wireless tag. Therefore, unlike the inventions described in Patent Literature 1 to Patent Literature 4, the tag search device 100 according to the present embodiment controls the directivity of the transmission beam and sends a signal to one or more wireless tags scattered around. Since there is no need to transmit or rotate the directivity of the received beam in all directions of 360 degrees, it is necessary to provide a complicated and expensive antenna mechanism for controlling the beam directivity of the transmission / reception antenna. No.

<4> Problem of Position Estimation Accuracy in Wireless Tag Position Estimation Method According to the method described above with reference to FIGS. 4 to 8, the direction in which the wireless tag 200 n is located based on the Advertising signal received by the tag search device 100 from the wireless tag 200 n When estimating the distance, the estimation accuracy of the tag position is lower than the method described in Patent Document 1. This is because the RFID tag search device described in Patent Document 1 includes a complicated and expensive antenna control mechanism for precisely performing directivity control of transmission / reception beams and timing synchronization control of positioning signals. Therefore, referring first to FIG. 9, the tag search device 100 that does not have the complicated and expensive antenna control mechanism described in Patent Document 1 is assumed to estimate the tag position according to the method described above with reference to FIGS. A specific example of the estimated decrease in estimation accuracy will be described.

  FIG. 9A shows a state in which the user holding the tag search device 100 rotates his / her body on the spot and scans the reception intensity of the advertising signal from the wireless tag 200n over 360 degrees around the user. Represent. At this time, as shown in FIG. 7, the direction (azimuth angle) in which the receiving electric field strength of the Advertising signal from the wireless tag 200n reaches a peak (azimuth angle) does not converge to a specific azimuth angle but shows a spread over a certain range. . This is because the received signal strength curve shown in FIG. 7 has a regular unimodal curve due to an error in the measured value of the received signal strength of the Advertising signal or due to the surrounding fading environment or radio wave interference. Because it will not be. For the same reason as described above, the estimation result of the distance to the wireless tag 200n estimated based on the received electric field strength of the Advertising signal received by the tag searching device 100 from the wireless tag 200n does not converge to a specific value. Shows spread over a certain range.

  A state in which the direction in which the received electric field intensity of the Advertising signal from the wireless tag 200n reaches a peak is spread within a certain range is shown as a sector area A1 in the radar chart shown in FIG. 9B. In addition, the radar shown in FIG. 9B shows that the estimated distance from the wireless tag 200n to the wireless tag 200n estimated based on the received electric field strength of the Advertising signal received by the tag searching device 100 is spread over a certain range. This is shown as a donut-shaped region D1 in the chart. When the tag position is determined from the combination of the direction and distance in which the wireless tag 200n is estimated to be located according to the method described above with reference to FIGS. 4 to 8, the tag specified in the radar chart shown in FIG. 9B. The position is an intersection region R1 between the sector region A1 and the donut region D1. Since this intersection region R1 shows a certain range of spread in both the direction and distance where the wireless tag 200n is estimated to be located, the position estimation accuracy of the wireless tag 200n estimated according to the method described above with reference to FIGS. Often not enough.

<5> Method for Improving Position Estimation Accuracy of Wireless Tag According to the Present Embodiment Hereinafter, a method for improving the position estimation accuracy of the wireless tag according to the present embodiment will be specifically described with reference to FIGS. 10 and 11. To do. According to the method for improving the position estimation accuracy, according to the method described above with reference to FIGS. 4 to 8, the wireless tag 200n is selected from the intersection region R1 including the current position of the wireless tag 200n on the radar chart of FIG. 9B. This is a method for narrowing down a region that is highly likely to be located. Accordingly, it is possible to improve the estimation accuracy related to the current position of the wireless tag 200n estimated on the radar chart of FIG. 9B in accordance with the method described above with reference to FIGS. As a result of the improvement of the estimation accuracy, in the present embodiment, the tag search device 100 estimates the current position of the wireless tag 200n even if the tag search device 100 does not include the complicated and expensive antenna control mechanism described in Patent Document 1. With respect to the above, a practically sufficient estimation accuracy can be achieved. In the following, when the method described with reference to FIGS. 10 and 11 is executed, the processing operation executed on the tag search device 100 is executed by the position estimation unit 304 shown in FIG. It is possible. The position estimation unit 304 shown in FIG. 4 is realized by executing a predetermined control program stored in the storage unit 105 by the control unit 101 shown in FIG.

  First, a method for improving the position estimation accuracy will be described with reference to FIG. In FIG. 10, the tag search device 100 considers not only the direction and distance estimated by the received signal from the wireless tag 200n but also the positioning information estimated by other wireless transceivers such as the wireless transceiver 700 shown in FIG. By doing so, the position of the wireless tag 100n is estimated. Thereby, the tag search device 100 can obtain a position estimation result with higher accuracy than estimating the position of the wireless tag 200n alone from the received signal from the wireless tag 200n. However, at that time, the tag search device 100 needs to grasp the relative positional relationship between the wireless transceiver 700 and itself. Therefore, the tag search device 100 uses a method similar to the method described above with reference to FIGS. 4 to 8 in order to estimate the relative position of the wireless transceiver 700.

  Therefore, in the tag position estimation method shown in FIG. 10, as with the case of FIG. 9 (A), the user holding the tag search device 100 makes one turn on the spot to receive from the wireless tag 200n. The signal strength is scanned over 360 degrees around the user. During the scanning operation of the received signal strength, the tag search device 100 receives the Advertising signal transmitted from the wireless tag 200n and generates positioning information regarding the wireless tag 200n. At the same time, the wireless transceiver 700 also receives the Advertising signal transmitted from the wireless tag 200n and generates positioning information related to the wireless tag 200n. The flow of Advertising signal at this time is shown as m1 and m3 in FIG. Furthermore, since the tag search device 100 needs to grasp the relative positional relationship between the radio transceiver 700 and itself, the tag search device 100 also receives a positioning signal from the radio transceiver 700. The positioning signal transmitted by the wireless transceiver 700 in response to a request from the tag search device 100 is the same signal as the Advertising signal transmitted from the wireless tag 200n. Further, the tag search device 100 receives distance information representing the distance to the wireless tag 200n estimated by the wireless transceiver 700 from the wireless transceiver 700. The flow of the positioning signal at this time is shown as m2 in FIG.

  As described above, the tag search device 100 can determine the position of the wireless tag 200n by considering not only the direction and distance estimated by the received signal from the wireless tag 200n but also the positioning information estimated by the wireless transceiver 700. It is possible to obtain a position estimation result with higher accuracy than that estimated by. Accordingly, another wireless transceiver such as the wireless transceiver 700 shown in FIG. 1 has a role of supporting the operation of positioning the tag 200n by the tag searching device 100, and positioning is performed when viewed from the tag searching device 100. Act as a supporting radio station.

  Next, using FIG. 11, a region for which the wireless tag 200n is likely to be located is further narrowed down from the intersecting region R1 (FIG. 9B) including the current position of the wireless tag 200n. The principle will be described as follows. In FIG. 11A, the tag search device 100 uses the positioning signal (m2 in FIG. 10) received from the wireless transceiver 700 to estimate the direction and distance in which the wireless transceiver 700 is located on the radar chart. Results are shown. This estimate of the direction and distance in which the radio transceiver 700 is located follows the same method as described above with respect to FIGS. 4-8, in which the tag search device 100 is positioned relative to the radio transceiver 700 and itself. It is executed to grasp the relationship. As described above with reference to FIG. 9, on the radar chart of FIG. 11A, the estimation result regarding the direction and distance in which the wireless transceiver 700 is located does not converge on a specific direction and distance, and is within a certain range. Show the spread of. As a result, on the radar chart of FIG. 11A, the direction in which the radio transceiver 700 is located is indicated as a sector area A2, and the distance to the radio transceiver 700 is indicated as a donut area D2. Therefore, in the radar chart of FIG. 11A, the intersecting region R2 between the fan-shaped region A2 and the donut-shaped region D2 is the estimation result of the position of the wireless transceiver 700 viewed from the tag search device 100.

  Next, the tag search device 100 receives the above-mentioned positioning signal for estimating the relative position of the wireless transceiver 700 from the wireless transceiver 700 at m2 in FIG. Receive from the transceiver 700. This distance information d is information representing the distance to the wireless tag 200n estimated by the wireless transceiver 700, and is transmitted and received in the same manner as a positioning signal for notifying the tag searching device 100 of the position of the wireless transceiver 700. Is transmitted from the machine 700 to the tag search device 100. For the same reason as described above with reference to FIG. 9, the estimation result of the distance to the wireless tag 200n represented by the distance information d also spreads over a certain range without converging on a specific value. In other words, the distance from the wireless transceiver 700 to the wireless tag 200n represented by the distance information d is not a specific value but a numerical range over a certain width. In the donut-shaped area A3 shown in FIG. 11B, the distance information d indicates the outer edge of the area R2 around the area R2 corresponding to the relative position of the radio transceiver 700 viewed from the tag search device 100 on the radar chart. This is an area obtained by expanding the distance represented. Accordingly, the donut-shaped area A3 corresponds to a range in which the wireless tag 200n may be located around the estimated position of the wireless transceiver 700 when the tag search device 100 is the origin of the radar chart. It is.

  Next, a region R1 shown in FIG. 11C corresponds to the intersection region R1 shown in FIG. 9B, and the position of the wireless tag 200n estimated by the tag search device 100 independently according to the method of FIGS. It corresponds to the estimation result. Therefore, the tag search device 100 obtains the intersection region R3 between the intersection region R1 in FIG. 9B and the donut-shaped region A3 shown in FIG. The region where the tag 200n is likely to be located can be narrowed down further. That is, in the radar chart of FIG. 11C, the above-described intersection region R3 utilizes the distance information d received from the wireless transceiver 700 for the region R1 of FIG. 9B, which is the position estimation result of the wireless tag 200n. Thus, it is an area obtained by further narrowing down. By making the above-described intersection region R3 the position estimation result of the wireless tag 200n viewed from the tag search device 100, the tag search device 100 is more than the region R1 corresponding to the result of estimation independently according to the method of FIGS. The estimation accuracy can be improved.

  In the embodiment described above with reference to FIGS. 10 and 11, the wireless transceiver 700 generates the distance information d described above based on the received electric field strength of the Advertising signal received from the wireless tag 200n. It was set as the structure transmitted to the tag search device 100. However, as will be described later with reference to FIG. 12, in an alternative embodiment, the wireless transceiver 700 simply uses the received field strength of the Advertising signal received from the wireless tag 200n instead of performing the operation of generating the distance information d. It is also possible to measure and transmit the measured electric field strength value to the tag search device 100 as it is. In this case, the tag search device 100 that has received the electric field strength value from the wireless transceiver 700 estimates the distance between the wireless transmitter / receiver 700 and the wireless tag 200n from the electric field strength value, and the distance inside the tag search device 100 Information d can be generated.

<6> Operation Flow of Radio Tag Position Estimation Method According to the Present Embodiment Hereinafter, according to the method described above with reference to FIGS. 10 and 11, the tag search device 100, the radio tag 200 n and the radio transmission / reception device 700 are respectively executed. The flow of operations to be performed and the flow of information communicated between these three parties will be described with reference to the event flow diagram of FIG. In a series of processing operations described below along the event flow diagram of FIG. 12, processing operations executed on the tag search device 100 may be executed by the position estimation unit 304 shown in FIG. Is possible. The position estimation unit 304 shown in FIG. 4 is realized by executing a predetermined control program stored in the storage unit 105 by the control unit 101 shown in FIG.

  First, in step S1101, the tag search device 100 transmits a control signal including a command for instructing transmission start of the Advertising signal to the wireless tag 200n. At the same time, the tag search device 100 transmits a control signal instructing the wireless transceiver 700 to start transmission of a positioning signal. The positioning signal transmitted by the wireless transceiver 700 in response to an instruction from the tag search device 100 is the same signal as the Advertising signal transmitted from the wireless tag 200n.

  Subsequently, in step S1102, in response to the control signal received from the tag search device 100, the wireless tag 200n starts a periodic repeated transmission operation of the Advertising signal. The Advertising signal transmitted by the wireless tag 200n at this time is received by both the tag search device 100 and the wireless transceiver 700. In parallel with this, the wireless transceiver 700 starts a cyclic repetitive transmission operation of the positioning signal according to the control signal received from the tag search device 100, and this positioning signal is received by the tag search device 100. The

  Subsequently, in step S1103A, the tag search device 100 performs positioning of the wireless tag 200n and the wireless transceiver 700 using the Advertising signal and the positioning signal received from the wireless tag 200n and the wireless transceiver 700, respectively. Specifically, based on the received Advertising signal and positioning signal, the tag search device 100 estimates the direction and distance in which the wireless tag 200n and the wireless transmitter / receiver 700 are located, centering on its own position. At this time, the tag search device 100 can perform estimation of the direction and distance in which the wireless tag 200n and the wireless transceiver 700 are located according to the method described above with reference to FIGS.

  In step S1103B executed in parallel with step S1103A, the wireless transceiver 700 measures the received electric field strength of the Advertising signal received from the wireless tag 200n.

  Subsequently, in step S1104, the wireless transceiver 700 transmits information representing the received electric field strength measured with respect to the Advertising signal received from the wireless tag 200n to the tag search device 100.

  In step S1105, the tag search device 100 estimates the distance from the wireless transceiver 700 to the wireless tag 200n based on the received electric field strength of the Advertising signal transmitted from the wireless transceiver 700. The result of the wireless transceiver 700 estimating the distance to the wireless tag 200n is generated as the distance information d described above with reference to FIG. Note that the distance from the wireless transceiver 700 to the wireless tag 200n represented by the distance information d is not a specific value but a numerical range over a certain width.

  Finally, in step S1106, in the tag searching device 100, the wireless tag 200n is located based on the direction and distance in which the wireless tag 200n and the wireless transceiver 700 are located, and the distance information d transmitted from the wireless transceiver 700. Estimate the exact direction and distance. At this time, the tag search device 100 estimates an accurate direction and distance in which the wireless tag 200n is located according to the method described above with reference to FIGS. 11 (A) to 11 (C). The direction and the distance in which each of the wireless tag 200n and the wireless transceiver 700 is located are the direction and the position estimated by the tag search device 100 regarding the wireless tag 200n and the wireless transceiver 700 in step S1103A. Note that the direction and distance estimated in step S1106 with respect to the position of the wireless tag 200n are the positions of the wireless tag 200n estimated by the tag searching device 100 alone without being notified of the distance information d from the wireless transceiver 700 in step S1103A. The estimation accuracy is better than the direction and distance.

<7> Effects of this Embodiment In the tag position estimation method shown in FIGS. 10 and 11, the wireless transceiver 700 does not need to estimate the direction in which the wireless tag 200 n is located. It should be noted that only the estimation result regarding the distance needs to be reported to the tag search device 100 as the distance information d. Accordingly, the tag search device 100 detects sensors (the geomagnetic sensor 107A, the gyro sensor 107B, and the sensor shown in FIG. 4) in order to detect the arrival direction of the received signal from the wireless tag 200n according to the method described above with reference to FIGS. The acceleration sensor 107C) needs to be provided, whereas the wireless transceiver 700 does not require such sensors. Similarly, the wireless monitoring station described in Patent Document 1 requires a highly accurate antenna control mechanism for transmission / reception beam directivity control and positioning signal synchronization in order to estimate the direction in which the wireless tag 200n is located. The wireless transceiver 700 does not require such a mechanism. As a result, in this embodiment, the wireless transceiver 700 may be any wireless transceiver as long as it has a function of measuring the electric field strength of the received signal from the wireless tag 200n. It can be any cellular base station, any radio relay station or any radio transceiver.

  Further, in the tag position estimation method shown in FIG. 10 and FIG. 11, only two units of the tag search device 100 and the wireless transceiver 700 are required as positioning execution devices. Thus, three or more positioning execution devices are not required. In addition, the methods shown in FIGS. 10 and 11 improve the estimation accuracy of the wireless tag position to a practically sufficient level by using only the tag search device 100 and the wireless transceiver 700 as positioning execution devices. I can do it. This is because, in this embodiment, the position of the wireless tag is a two-dimensional polar coordinate consisting of only the direction and distance in which the wireless tag 200n is located, based only on the arrival direction of the received signal from the wireless tag 200n and the received electric field strength. This is because it is sufficient to estimate the position.

  As a result, according to the present embodiment, the RFID tag searching apparatus 100 is inexpensive and simple without providing a complicated and expensive antenna control mechanism for controlling the beam directivity of the antenna and timing synchronization of the positioning signal with high accuracy. However, it is possible to realize a wireless tag positioning system having practically sufficient accuracy. In addition, the present embodiment estimates only the relative direction and distance in which the wireless tag 200n is located, and does not require positioning signal communication with many satellites and base stations. A wireless tag positioning system can be realized with this system configuration.

  INDUSTRIAL APPLICABILITY The present invention can be used as a position search device and a position search system for searching for the position of an article or person to which a small wireless transmitter is attached based on radio waves from the wireless transmitter.

DESCRIPTION OF SYMBOLS 100 Tag search apparatus 101 Control part 102 Wireless information transmission / reception part 103 Wireless communication part 104 Display part 105 Storage part 106 User input / output part 107 Sensor part 107A Geomagnetic sensor 107B Gyro sensor 107C Acceleration sensor 108 Transmission / reception antenna 200 Wireless tag 201 Control part 202 Notification information transmission unit 203 Wireless communication unit 204 Timekeeping unit 205 Storage unit 206 Battery 207 Transmission / reception antenna 210 Control signal reception unit 300 Functional block structure of tag search device 302 Dynamic determination unit 304 Position estimation unit 400 Icon image 700 that displays a wireless tag position Wireless transceiver 701 Control unit 702A Wireless information transmission unit 702B Wireless information reception unit 703 Wireless communication unit 704 Antenna

Claims (9)

A wireless search device that searches for a wireless device based on wireless signals received from one or more wireless devices and supporting wireless stations, and transmits and receives the wireless signal and a position estimation unit that estimates the position of the wireless device A wireless transceiver, wherein the position estimator is:
Means for generating a first estimation result relating to positions of the radio and the supporting radio station based on the radio signals received from the radio and the supporting radio station; and
Means for generating a second estimation result relating to the position of the radio using the assistance signal received from the assistance radio station together with the first estimation result;
With
The wireless search device according to claim 1, wherein the support signal includes distance information related to a distance to the wireless device measured by the support wireless station. The means for generating the second estimation result is:
Means for calculating a region separated by a distance represented by the distance information from a region represented by the first estimation result with respect to an estimated position of the supporting radio station;
Means for calculating an intersection area between the calculated area and an area represented by the first estimation result with respect to an estimated position of the radio; and
Means for outputting information representing the intersection area as the second estimation result;
The wireless search device according to claim 1, comprising: The positions of the wireless device and the supporting wireless station are represented by the direction and distance where the wireless device and the supporting wireless station are located when viewed from the wireless search device,
The first estimation result includes an estimation result regarding a direction and a distance in which the wireless device and the supporting wireless station are respectively located,
The second estimation result includes an estimation result with higher accuracy than the first estimation result with respect to the direction and distance in which the radio is located.
The wireless search device according to claim 1. The support radio station estimates a distance to the radio based on a received electric field strength of the radio signal received from the radio, generates the support signal based on the estimated distance, and performs the radio search Send to device,
The wireless search device according to claim 1, wherein: When the user holding the wireless search device changes direction, the sensor further detects a change in the direction of the wireless search device,
The position estimation unit
Means for recording a change in the reception intensity of the radio signal as a measurement result in association with a change in the direction detected by the sensor when the user changes the direction;
Means for determining the orientation of the wireless search device from the recorded measurement results;
Means for estimating a direction in which the radio is located based on the strength;
The wireless search device according to claim 1, further comprising: A wireless search device searches for the wireless device based on wireless signals received from one or more wireless devices and supporting wireless stations, the wireless search device estimating a position of the wireless device And a wireless transceiver for transmitting and receiving the wireless signal:
The position estimation unit generating a first estimation result regarding the positions of the radio and the support radio station based on the radio signals received from the radio and the support radio station; and
Means for generating a second estimation result relating to the position of the radio by the position estimation unit using the support signal received from the support radio station together with the first estimation result;
With
The support signal includes distance information regarding the distance to the radio station measured by the support radio station, and the second estimation result specifies the position of the radio device with higher accuracy than the first estimation result. A method characterized by that. The step of generating the second estimation result includes:
Calculating a region separated from the region represented by the first estimation result by the distance represented by the distance information with respect to the estimated position of the supporting wireless station;
Calculating an intersection area between the calculated area and an area represented by the first estimation result with respect to the estimated position of the radio; and
Outputting information representing the intersection area as the second estimation result;
The method of claim 6 comprising: The positions of the wireless device and the supporting wireless station are represented by the direction and distance where the wireless device and the supporting wireless station are located when viewed from the wireless search device,
The first estimation result includes an estimation result regarding a direction and a distance in which the wireless device and the supporting wireless station are respectively located,
The second estimation result includes an estimation result with higher accuracy than the first estimation result with respect to the direction and distance in which the radio is located.
The method according to claim 6. The support radio station estimates a distance to the radio station based on a received electric field strength of the radio signal received from the radio, generates the support signal based on the estimated distance, and performs the radio search Send to device,
The method according to claim 6, wherein:

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