JP2017142255A - Wireless tag search method and device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a direction estimation taking into consideration an error generated between a direction at which a wireless tag is actually located and the direction at which a signal reception intensity from the wireless tag is maximum in a system for estimating a location direction of the wireless tag to be a search object from a wireless search device.SOLUTION: A wireless search device includes: a position estimation part for estimating a direction at which wireless equipment is located; a sensor for detecting a change of the direction of the wireless search device; and a wireless communication part for measuring an intensity of a wireless signal. The position estimation part includes: means for recording a change of an intensity measured by the wireless communication part in association with the change of the detection detected by the sensor as a measurement result of the change of the intensity measured by the wireless communication part; means for calculating an azimuth angle shift amount of a standard curve in which a signal intensity change curve shown by the recorded measurement result is maximum; and means for estimating the direction at which wireless equipment is located based on the calculated azimuth angle shift amount.SELECTED DRAWING: Figure 4

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 Documents 1 to 4, the wireless monitoring station detects the azimuth corresponding to the signal arrival angle (received beam direction) from the wireless transmission source based on the directivity control of the antenna, so that the wireless transmission source is positioned. A technique for detecting a direction to perform 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.

JP 2011-149808 A JP 2007-074323 A JP 2006-105723 A JP 2006-071380 A JP 2010-127755 A

  When estimating the direction in which the search target radio tag is located based on the intensity level of the received signal from the radio tag measured while the user holding the radio search device makes one rotation over 360 degrees. In some cases, accurate direction estimation may be difficult due to an estimation error. Specifically, the direction in which the wireless tag is actually located and the reception strength of the wireless signal are maximized due to surrounding electromagnetic influences (including those caused by the human body holding the wireless search device), scattering, or obstacles. There may be an error between As a result, there arises a problem that a user who searches for the position of the wireless tag using the wireless search device cannot accurately estimate the direction in which the wireless tag exists. Moreover, as will be described later, the error that occurs between the direction in which the wireless tag is actually located and the direction in which the reception strength of the wireless signal is maximized varies greatly depending on the antenna directivity of each individual wireless search device. This appears as a unique error for each wireless search device.

  On the other hand, a small number of techniques for correcting such a direction estimation error when a direction in which a wireless tag exists is estimated by a wireless search device is known. For example, the invention described in Patent Document 5 discloses a technique for correcting a positioning error of a wireless tag position in the following procedure. First, (1) for each observation point where a wireless tag is installed and positioned, a characteristic pattern (expected positioning distribution pattern) of the predicted positioning distribution obtained by predicting the theoretical positioning distribution is calculated, and then , (2) Obtaining the positioning result obtained by positioning the position of the wireless tag with the wireless search device as observation data, (3) Obtaining the positioning result statistically analyzed for each observation point based on these observation data The characteristic pattern (measurement positioning distribution pattern) of the calculated measurement positioning distribution is calculated. Finally, (4) the position of the wireless tag position is calculated using the calculated expected positioning distribution pattern and the calculated measurement positioning distribution pattern. Correct the error.

  However, in the method described in Patent Document 5, a theoretical model or a mathematical model that is a premise for calculating a characteristic pattern of the predicted positioning distribution must be set as a hypothesis, and the accuracy of the predicted positioning distribution pattern is The problem arises that it depends heavily on the correctness of hypotheses based on simple models.

  Further, the method described in Patent Document 5 has another problem as described below. Specifically, in the disclosure of Patent Document 5, a technique for correcting a positioning error related to a wireless tag position by using a measured positioning distribution pattern is a form of software determination that estimates an estimated value of a positioning error. It can be considered. More specifically, in order to estimate the positioning error, the above technique performs the positioning error by executing the maximum likelihood estimation method using the measured positioning distribution pattern obtained by statistically analyzing the positioning result. It can be regarded as a form of a soft decision technique for estimating a soft decision value for the. As a result, in the method described in Patent Document 5, in order to increase the estimation accuracy of the positioning error of the RFID tag position, the number of sample values (positioning sampling data) used when statistically processing the positioning results, It is necessary to increase the amount of statistical processing calculation according to this. Therefore, in the method described in Patent Document 5, the estimation accuracy of the positioning error of the wireless tag position greatly depends on the information amount input for error estimation and the statistical processing calculation amount corresponding to the information amount. Cause problems.

  In view of the above problems, the present invention provides a system for estimating the direction of the wireless tag viewed from the wireless search device based on the intensity level of the received signal from the wireless tag to be searched. It is an object of the present invention to realize direction estimation in consideration of the influence of an error that occurs between a direction located in a direction and a direction in which the signal reception intensity from the wireless tag is maximized. Further, the present invention realizes a mechanism for correctly estimating the direction of the wireless tag in consideration of the influence of the above error even if the above error differs depending on the antenna directivity for each wireless search device. The purpose is to do. Furthermore, the present invention relates to direction estimation in consideration of an error generated between the direction in which the wireless tag is actually located and the direction in which the signal reception intensity is maximum, and the correctness of the hypothesis model, a large amount of information, and the corresponding amount The purpose is to realize a highly accurate direction estimation mechanism without implementing an error estimation calculation that requires a large amount of calculation.

  Therefore, in order to solve the above problem, the wireless search device searches for the wireless device based on the strength of the wireless signal received from one or more wireless devices, and estimates a direction in which the wireless device is located When the user holding the wireless search device changes the direction, the sensor that detects a change in the direction of the wireless search device and the wireless signal is received from the wireless device, and the strength of the wireless signal is measured. A wireless communication unit, wherein the position estimating unit associates with the change in orientation detected by the sensor when the user changes the orientation, and the wireless communication unit measures the intensity measured by the wireless communication unit. Means for recording a change as a measurement result; means for calculating an azimuth shift amount of the reference curve that maximizes the correlation strength between the signal intensity change curve represented by the recorded measurement result and the reference curve; Calculation It was based on the azimuth angle shift amount, and means for estimating the direction in which the radio is located. The reference curve is obtained as an intensity change curve of the reference wireless signal corresponding to the azimuth angle by actually measuring the intensity of the reference wireless signal received for each azimuth angle from a radio device installed in a known direction.

  As described above, the present invention is a system that estimates the direction of the wireless tag viewed from the wireless search device based on the intensity level of the received signal from the wireless tag to be searched. The direction in which the wireless tag is actually located And direction estimation can be performed in consideration of the influence of an error that occurs between the direction in which the signal reception intensity from the wireless tag is maximum. Further, the present invention realizes a mechanism for correctly estimating the direction of the wireless tag in consideration of the influence of the above error even if the above error differs depending on the antenna directivity for each wireless search device. can do. Furthermore, the present invention relates to direction estimation in consideration of an error generated between the direction in which the wireless tag is actually located and the direction in which the signal reception intensity is maximum, and the correctness of the hypothesis model, a large amount of information, and the corresponding amount In addition, a highly accurate direction estimation mechanism can be realized without implementing error estimation calculation that requires a large amount of calculation.

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 of this invention, and a tag search device 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 which shows the antenna directivity pattern of tag search device and the change of the reception electric wave intensity corresponding to it The figure explaining the direction estimation method which concerns on 1st Example and 2nd Example The figure explaining the direction estimation method which concerns on 3rd Example Flowchart of direction estimation method according to the third embodiment The figure explaining the direction estimation method which concerns on 4th Example The figure which shows the actual measurement method of the reference data used in 3rd Example and 4th Example Flow chart showing how to calculate reference data Numerical table showing examples of calculation of reference data

<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 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. Specifically, in the present embodiment, the direction in which the active wireless tag is actually located due to surrounding electromagnetic influences (including the influence of a human body holding the wireless search device in hand), scattering, or obstacles Disclosed is a technique for overcoming the problem that an error occurs between the direction in which the reception intensity of a radio signal is maximized.

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

  One embodiment of the wireless communication system includes a tag searching device 100 used by a user as a portable 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 have. 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.

(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. Instructs the transmission unit 203.

  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 terminal with which a user can communicate, and includes, but is not limited to, a user terminal such as a mobile phone, an information terminal, a personal digital assistant, a portable personal computer, and a smartphone. Not.

  The tag searching device 100 includes a control unit 101, a notification information receiving unit 202, a wireless communication unit 103, a display unit 104, a storage unit 105, a user input / output unit 106, a sensor 107, a transmission / reception antenna 108, And a control signal transmission unit 110.

  The control unit 101 can be implemented by a general-purpose microprocessor, a digital signal processor, or the like, and exchanges signals with the notification information receiving unit 102, the display unit 104, the storage unit 105, the user input / output unit 106, and the sensor 107. However, control of the entire tag search device 100 is executed. 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 broadcast information receiving unit 102 is connected to the control unit 101 and the wireless communication unit 103 so as to be interposed therebetween. The broadcast information receiving unit 102 receives a wireless signal from the wireless tag 200n. When the received wireless signal is an Advertising signal, the broadcast information receiving unit 102 decodes the information content of the received signal, thereby identifying the wireless tag identification information of the wireless tag 200n. (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.

  The wireless communication unit 103 performs wireless communication according to a short-range wireless communication standard such as Bluetooth, zigbee, Wi-Fi, or ANT +. The wireless communication unit 103 is not limited to Bluetooth, zigbee, Wi-Fi, and ANT +, and may perform wireless communication in accordance with a short-range wireless communication standard other than these. In one embodiment of the tag search device 100, a case where the wireless communication unit 103 performs short-range wireless communication according to Bluetooth Low Energy Wireless Technology will be described. The wireless communication unit 103 measures 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 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.

  The control signal transmission unit 110 is connected to the control unit 101 and the wireless communication unit 103 so as to be interposed therebetween. The control signal transmission unit 110 receives a control command from the control unit 101 for the tag search device 100 as a base unit to control the operation of the wireless tag 200n, encodes it as a control signal, and then transmits the control command to the wireless communication unit 103. To the wireless tag 200n.

(2-4) Function provided by tag search device 100 to user and usage mode of tag search device 100 Hereinafter, the tag search device 100 executing the RFID tag search application is provided to the user using FIG. 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.
(2-5) Functional Block Configuration Inside Tag Search Device 100 FIG. 4 is a functional block diagram showing an embodiment 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. Changes in the radio field intensity received from the radio tag 200n are recorded, and the orientation of the tag search device 100 when the radio field intensity becomes maximum is detected.

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. 7 and FIG. 8 (C). 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. Further, in this case, the position of the wireless tag 200n is not changed while waiting for the user holding the tag search device 100 to rotate once around 360 degrees from the above-described movement start timing. It is also possible for the position estimation unit 304 to update the estimation result as needed. For example, it is assumed that the tag search device 100 can obtain a certain amount or more of measurement data representing the electric field strength received from the wireless tag 200n and measurement data measured by the sensors 107A to 107C while the user is rotating. At that time, every time new measurement data of a certain amount or more is obtained, the position estimation unit 304 executes the position estimation calculation of the wireless tag 200n based on the data obtained so far, and the position of the wireless tag 200n It is possible to update the estimation result.

  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> Direction estimation method considering error included in estimation result of direction in which radio tag is located (4-1) Direction estimation error First, the direction in which the radio tag is located will be described with reference to FIGS. The estimation error when estimated by the method as described above will be described with reference to FIG.

  When a radio wave from the wireless tag 200n is reflected or absorbed by a human body having the tag search device 100 in hand or a shield or the like existing around the tag search device 100, the tag search device 100 receives the radio wave. The antenna directivity pattern is ideally as shown in the upper diagram of FIG. 9A shows a state in which the directivity of the receiving antenna is distributed in an elliptical shape with no bias over all 360 degrees around the position of the receiving antenna of the tag search device 100. FIG. . In that case, the change in the reception intensity of the radio wave received from the wireless tag 200n while the user holding the tag search device 100 makes one turn on the spot is as shown by the curve graph in the lower diagram of FIG. In the curve graph shown in the lower diagram of FIG. 9A, the horizontal axis corresponds to the azimuth angle facing the tag search device 100 held by the user, and the vertical axis represents the radio wave reception intensity corresponding to the azimuth angle. Represent. For the sake of convenience of explanation, the curve graph shown in the lower part of FIG. 9A shows the range of azimuth values that the horizontal axis can take as the origin position on the horizontal axis where the radio wave reception intensity is maximum. The origin position is between −180 ° and + 180 ° with reference direction. That is, the horizontal axis shown in the lower diagram of FIG. 9A corresponds to the azimuth angle (−180 ° to + 180 °) over 360 degrees around the tag searching device 100. From the above, as described above with reference to FIGS. 6 to 8, the direction in which the reception intensity of the radio wave from the wireless tag is the strongest can be estimated as the direction in which the wireless tag exists.

  However, the actual directivity pattern of the receiving antenna of the tag search device 100 is not an ideal pattern as shown in FIG. 9A, but only in a specific direction as shown in the upper diagram of FIG. 9B, for example. Is biased. For this reason, the directivity of the receiving antenna is not distributed evenly in all directions, and the directivity corresponding to a part of the direction may be strong or weak. In that case, the change in the radio wave reception intensity when the user holding the tag search device 100 makes a full turn is as shown by the curve graph shown in the lower diagram of FIG. 9B, so that the radio wave received from the radio tag is received. The wireless tag 200n does not always exist in the direction of the strongest intensity. As a result, it is difficult for the tag searching device 100 to execute accurate direction estimation with respect to the direction in which the wireless tag 200n is located. In addition, since the method of distorting the directivity pattern related to the receiving antenna of the tag search device 100 is different for each tag search device, the above direction estimation caused by the distortion of the antenna directivity pattern shown in FIG. The error is also different for each tag search device.

  Hereinafter, when the tag search device 100 estimates the direction corresponding to the current position of the wireless tag 200n using FIGS. 10 to 13, the direction estimation considering the error of FIG. 9B included in the estimation. Specific examples of the method will be described as the first to fourth embodiments. In the direction estimation methods according to the first to fourth embodiments described below, the control unit 101 in the tag search device 100 is in the storage unit 105 while communicating with the notification information receiving unit 102 and the control signal transmitting unit 110. Implemented by executing a stored software program.

(4-2) First Example Regarding Method of Estimating Direction of Wireless Tag First, the first example will be described with reference to FIG. In the direction estimation method according to the first embodiment, the tag search device 100 measures the azimuth angle at which the intensity of the radio wave received from the wireless tag 200n is the minimum as the minimum intensity azimuth, and 180 ° when viewed from the minimum intensity azimuth. The opposite direction is estimated as the direction corresponding to the current position of the wireless tag 200n. Specifically, it is as follows. The tag search device 100 according to the first embodiment, when a user holding the tag search device 100 makes one turn on the spot, changes in the azimuth angle of the tag search device 100 and the radio wave intensity received from the wireless tag 200n. Is measured in the form of a curve graph shown in FIG. In the curve graph shown in FIG. 10A, as in the curve graph shown in the lower diagrams of FIGS. 9A and 9B, the horizontal axis is directed to the tag search device 100 held by the user. Corresponding to the azimuth angle, the vertical axis represents the radio wave reception intensity according to the azimuth angle. That is, the horizontal axis shown in FIG. 10A corresponds to the azimuth angle (−180 ° to + 180 °) over 360 degrees around the tag searching device 100. In the direction estimation method according to the first embodiment, an azimuth angle obtained by adding or subtracting 180 ° from the azimuth angle (corresponding to the point 1001 on the horizontal axis of FIG. 10 (A) corresponding to the point 1002 on the horizontal axis) is output as the direction estimation result.

  The reason why the direction estimation method according to the first embodiment is configured as described above can be explained as follows. As described above with reference to FIG. 9, the maximum intensity azimuth angle corresponding to the direction in which the radio wave reception intensity from the wireless tag 200n is maximum may deviate from the actual direction of the wireless tag. On the other hand, the minimum intensity azimuth corresponding to the direction in which the radio wave reception intensity from the wireless tag 200n is minimum compared to the azimuth angle where the radio wave reception intensity is maximum is the above-described (1) to (3). It is considered that there is little fluctuation due to distortion in the receiving antenna directivity, which is not significantly affected by the factors.

  As described above, the direction estimation method according to the first embodiment measures the azimuth angle at which the radio wave reception intensity from the wireless tag 200n is minimized, as a direction not significantly affected by the distortion of the receiving antenna directivity of the tag search device 100. Then, the direction opposite to the azimuth angle is estimated as the direction in which the wireless tag 200n is located. As a result, the direction estimation method according to the first embodiment is not significantly affected by the distortion of the receiving antenna directivity of the tag search device 100 due to the factors (1) to (3) described above, and the wireless tag 200n. The direction in which is located can be estimated.

(4-3) Second Example Regarding Method for Estimating Direction of Wireless Tag Next, a second example will be described with reference to FIG. In the direction estimation method according to the second embodiment, first, the tag searching device 100 measures the azimuth angle at which the intensity of the radio wave received from the wireless tag 200n is minimum as the minimum intensity azimuth angle, and from this minimum intensity azimuth angle, The azimuth angle that is 180 ° opposite to the viewing angle is taken as the first azimuth angle. Subsequently, in the direction estimation method according to the second embodiment, the first azimuth angle is averaged with the second azimuth angle that is the azimuth angle at which the intensity of the radio wave received from the wireless tag 200n is maximized, and the averaged azimuth angle. Is estimated as the direction corresponding to the current position of the wireless tag. Specifically, it is as follows. The tag search device 100 according to the second embodiment is configured to change the azimuth angle of the tag search device 100 and the radio wave intensity received from the wireless tag 200n when a user holding the tag search device 100 makes a full turn on the spot. Is measured in the form of a curve graph shown in FIG. In the curve graph shown in FIG. 10B, as in the curve graph shown in the lower diagrams of FIGS. 9A and 9B, the horizontal axis indicates the tag search device 100 held by the user in the hand. Corresponding to the azimuth angle, the vertical axis represents the radio wave reception intensity according to the azimuth angle. In the direction estimation method according to the second embodiment, first, an azimuth angle (corresponding to the point 1003 on the horizontal axis in FIG. 10B) at which the radio wave reception intensity is minimum is measured as the minimum intensity azimuth angle. Then, an azimuth angle (corresponding to the point 1004 on the horizontal axis of FIG. 10B) obtained by adding or subtracting 180 ° from this minimum intensity azimuth angle is determined, and this is set as the first azimuth angle. Subsequently, in the direction estimation method according to the second embodiment, the azimuth angle (corresponding to the point 1005 on the horizontal axis in FIG. 10B) at which the radio wave reception intensity is maximum is determined as the maximum local azimuth angle, This is the second azimuth angle. Finally, in the direction estimation method according to the second embodiment, the azimuth angle corresponding to the average value of the first azimuth angle and the second azimuth angle (corresponding to the point 1006 on the horizontal axis of FIG. 10B). Is estimated as the direction in which the wireless tag 200n is located.

  From the above, the direction estimation method according to the second embodiment combines the information on the minimum intensity azimuth and the information on the maximum intensity azimuth that are not significantly affected by the distortion of the receiving antenna directivity, A direction estimation result with higher accuracy than the method according to the first embodiment can be obtained.

(4-4) Third Example Regarding Direction Estimation Method of Wireless Tag Next, a third example will be described with reference to FIG. In the direction estimation method according to the third embodiment, first, the angle difference between the direction in which the wireless tag 200n is actually located when viewed from the tag search device 100 and the direction of the wireless tag 200n estimated by the tag search device 100 is used. Is estimated as a calibration offset angle (calibration offset angle). Subsequently, in the direction estimation method according to the third embodiment, the azimuth angle of the wireless tag 200n is estimated using the direction estimation method according to the first embodiment or the second embodiment, and this is set as an azimuth angle before calibration. The calibration offset angle described above is added to or subtracted from the pre-calibration azimuth, and the result is output as a final estimation result regarding the direction of the wireless tag 200n.

  The calibration offset angle D described above is measured empirically as follows. First, the wireless tag 200n is installed in a known direction when viewed from the tag searching device 100, and the azimuth angle of the wireless tag 200n estimated by the direction estimation method according to the first embodiment or the second embodiment and the wireless tag 200n are actually The angle difference from the installed known direction is measured as one sample value. As another embodiment, the maximum intensity azimuth angle described above with reference to FIG. 9 (that is, the azimuth angle at which the radio wave reception intensity from the radio tag 200n is maximum) and the known direction in which the radio tag 200n is actually installed are It is also possible to actually measure the difference in angle as one sample value. A specific example for actually measuring such sample values will be described as follows. In FIG. 11A, the wireless tag 200n is installed in a known direction where the azimuth angle = 0 ° (origin position on the horizontal axis) when viewed from the tag search device 100, and the wireless tag 200n corresponding to the change in azimuth angle. It is a curve graph which recorded the change of the radio wave reception intensity from. The curve graph shown in FIG. 11A is referred to as reference data measured in order to obtain the calibration offset angle D empirically. This reference data is distinguished from the curve graph of the radio wave reception intensity change measured when the tag searching device 100 estimates the direction in which the wireless tag 200n is located when searching for the wireless tag 200n using the tag searching device 100. Is done. Note that since the directivity distortion of the receiving antenna described above in FIG. 9 is different for each tag search device, the reference data described with reference to FIG. 11A is also different for each tag search device. That is, for each tag search device, reference data unique to the tag search device is obtained.

  An angular difference between a point 1101 corresponding to the maximum intensity azimuth angle on the horizontal axis of the curve graph shown in FIG. 11A and 0 ° (origin position) on the horizontal axis is a sample value. Thereafter, the above-described measurement of the sample values is repeated under the same situation, and a statistical value is calculated from a large number of sample values obtained by these actual measurements, and the statistical value is set as the calibration offset angle D. Such a statistical value can be obtained, for example, by calculating an average value or a median value for a set of a large number of sample values obtained by a large number of actual measurements.

  FIG. 11B illustrates an example in which the calibration offset angle described above is added to or subtracted from the pre-calibration azimuth angle and output as a final estimation result regarding the direction of the wireless tag 200n. FIG. 11B is a curve graph of a change in radio wave reception intensity measured when the tag search device 100 estimates the direction in which the wireless tag 200n is located based on the method according to the third embodiment. In FIG. 11B, the pre-calibration azimuth is the maximum intensity azimuth described above with reference to FIG. 9, and the pre-calibration azimuth corresponds to the point 1102 on the horizontal axis of FIG. In FIG. 11B, the calibration offset angle D empirically measured by the above-described method is subtracted from the pre-calibration azimuth corresponding to the point 1102 on the horizontal axis to thereby relate to the direction of the wireless tag 200n. The final estimation result is output.

  Furthermore, as a modified embodiment of the direction estimation method according to the third embodiment, the following direction estimation method can be configured. In the example shown in FIG. 11A, a single calibration offset based on the angular difference between the maximum intensity azimuth described above with respect to FIG. 9 and the known direction in which the wireless tag 200n is actually installed. Although the angle D has been obtained, this modified embodiment also uses a calibration offset angle obtained by another method. Specifically, in the present modified embodiment, the minimum intensity azimuth angle determined using the method according to the first embodiment at the same time as obtaining the calibration offset angle D1 according to the example shown in FIG. The calibration offset angle D2 is also obtained based on the angle difference between the opposite direction of the above and the known direction where the wireless tag 200n is actually installed. In addition, in this modified embodiment, the direction of the wireless tag 200n is estimated using the two calibration offset angles D1 and D2.

  Hereinafter, the operation procedure of the method in which the modified embodiment estimates the direction in which the wireless tag 200n is located based on both of the two calibration offset angles D1 and D2 will be described with reference to the flowchart of FIG. In the operation procedure shown in the flowchart of FIG. 12, the control unit 101 in the tag search device 100 executes a software program stored in the storage unit 105 while communicating with the notification information receiving unit 102 and the control signal transmitting unit 110. Is implemented. First, in this modified example, in step SA1 of FIG. 12, a curve graph of a change in radio wave reception intensity from the wireless tag 200n measured when the user holding the tag search device 100 makes one turn on the spot, The maximum intensity azimuth described above with respect to FIG. 9 is determined. Subsequently, in this modified example, in step SA2 of FIG. 12, the calibration offset angle D1 is added to or subtracted from the determined maximum intensity azimuth to obtain the first estimated direction. In the flowchart of FIG. 12, the following processing steps of Step SB1 and Step SB2 are executed in parallel with the execution of the processing steps of Step SA1 and Step SA2. In step SB1, the opposite direction of the minimum intensity azimuth angle is determined according to the same method as the direction estimation method according to the first embodiment. In step SB2, the calibration offset angle D2 is added or subtracted in the direction opposite to the minimum intensity azimuth determined as described above to obtain the second estimated direction. Finally, in the modified example, in step S3 of FIG. 12, the azimuth angle corresponding to the first estimated direction and the azimuth angle corresponding to the second estimated direction are averaged, thereby obtaining a final direction regarding the direction of the wireless tag 200n. Output the estimation result.

  As described above, the direction estimation method according to the third example obtains the estimated direction estimated according to the first example or the second example with respect to the direction in which the wireless tag 200n is located based on the actual measurement result of the reference data. By correcting with the calibration offset angle D thus obtained, it is possible to output a more accurate direction estimation result than in the first and second embodiments.

  Furthermore, in the direction estimation method according to the third embodiment, reference data unique to the tag search device 100 is actually measured, and the wireless tag 200n is determined by the calibration offset angle D obtained according to the unique reference data measurement result. The estimation result of the direction of the position is corrected. Thereby, the direction estimation method according to the third embodiment is based on the reference data measurement result according to the directionality distortion method even if the directionality distortion method of the receiving antenna is different for each tag search device. The direction estimation result can be corrected appropriately. This is because the directivity distortion of the receiving antenna described above in FIG. 9 is different for each tag search device, and the reference data is also different for each tag search device.

(4-5) Fourth Example Regarding Direction Estimation Method of Wireless Tag Next, a fourth example will be described with reference to FIGS. The direction estimation method according to the fourth embodiment performs the following procedure. First, prior to searching for the wireless tag 200n by the tag search device 100, reference data is actually measured. Specifically, in a situation where the wireless tag 200n is installed in a known direction in advance by the tag search device 100, the known direction is set to an azimuth angle of 0 °, and the wireless tag 200n corresponding to the change in the azimuth angle is used. Changes in received radio wave intensity are measured as reference data. Subsequently, when searching for the wireless tag 200n using the tag search device 100, the user who holds the tag search device 100 makes one turn on the spot and responds to a change in azimuth angle over 360 degrees around the user. The change in the received radio wave intensity from the wireless tag 200n is measured as a measurement result during search. A curve 1301 indicated by a solid line in FIG. 13 is a curve graph representing a change in received radio wave intensity corresponding to the measurement result at the time of search measured as described above when searching for the wireless tag 200n using the tag search device 100. Similar to the curve graphs shown in FIGS. 9 to 11, the horizontal axis of FIG. 13 is the azimuth (−180 ° to + 180 °) over 360 degrees around the tag searching device 100, while the curve 1302 shown in FIG. It is a curve graph showing the received radio wave intensity change corresponding to the reference data measured as described above. Subsequently, the method according to the fourth embodiment is based on the correlation strength between the received radio wave intensity change curve 1302 shown as reference data in FIG. 13 and the received radio wave intensity change curve 1301 shown as a solid line in FIG. Calculate Thereafter, in the method according to the fourth embodiment, the received radio wave intensity change curve 1301 indicated by the solid line is gradually shifted to the right along the horizontal axis of FIG. 13 while the received radio wave intensity change curve 1302 shown as the reference data is gradually shifted. The correlation strength between and is repeatedly calculated. As a result, in FIG. 13, when the received radio wave intensity change curve representing the reference data is shifted to the position represented by the curve 1303, the received radio wave intensity change curve representing the reference data and the received radio wave intensity indicated by the solid line. It is assumed that the correlation strength with the change curve 1301 is maximized. In the method according to the fourth embodiment, the shift amount at this time point of the curve representing the reference data is recorded as the maximum correlation shift amount, and the azimuth is shifted by the maximum correlation shift amount from the initial state represented by the curve 1302. Based on the reference data, a final estimation result regarding the direction in which the wireless tag 200n is located is obtained. Note that since the directivity distortion of the receiving antenna described above in FIG. 9 differs for each tag search device, the reference data described above with reference to FIG. 13 also differs for each tag search device. That is, for each tag search device, reference data unique to the tag search device is obtained.

  Next, a method for calculating the correlation strength between the curve representing the reference data and the curve representing the measurement result at the time of searching in FIG. 13 will be described as follows. First, in FIG. 13, for each azimuth corresponding to each point on the horizontal axis, the difference in received radio wave strength between the curve representing the reference data and the curve representing the measurement result at the time of search (vertical length in FIG. 13). Calculate the difference in axis values) and square the difference. Subsequently, the correlation strength is calculated by summing the square differences calculated for each azimuth corresponding to each point on the horizontal axis in this way over all directions (over the entire horizontal axis). . At this time, when the curve representing the reference data and the curve representing the measurement result at the time of the search are spaced apart in the vertical direction in FIG. 13, the offset value corresponding to the separation width is placed on the lower curve. It is also possible to calculate the square difference described above for each azimuth angle. By obtaining the correlation strength in this way, the correlation strength between the two curves described above can be appropriately evaluated even when the two curves described above are spaced apart from each other in the plane of FIG. I can do it. Further, in the plane of FIG. 13, when there is a marked difference between the maximum amplitudes of the curve representing the reference data and the curve representing the measurement result at the time of search, the received radio wave intensity change represented by the curve having the smaller maximum amplitude On the other hand, it is also possible to multiply the maximum amplitude ratio between the two curves and then calculate the above-mentioned square difference for each azimuth. By obtaining the correlation strength in this way, even when the maximum amplitudes of the two curves described above are greatly different in the plane of FIG. 13, the correlation strength of the two curves described above is appropriately evaluated. I can do it.

  Hereinafter, a specific example of a method for calculating the reference data used in the fourth embodiment will be described with reference to FIGS. FIG. 14 is a diagram showing an actually measured direction of reference data used in the fourth embodiment, and FIG. 15 is a flowchart showing a reference data calculation method.

  The reference data is actually measured by the tag search device 100 according to the following procedure. First, the wireless tag 200n is installed in a known direction when viewed from the tag searching device 100, and this known direction is set to a direction of azimuth = 0 ° when viewed from the tag searching device 100 (step S1 in FIG. 15). This is because it is necessary to actually measure the received radio wave intensity for each azimuth with reference to the correct direction in which the wireless tag 200n is actually located. Next, while the user holding the tag search device 100 makes one rotation on the spot, the tag search device 100 changes the intensity of the radio wave received from the wireless tag 200n over 360 degrees around. Measure and record the received radio wave intensity for each azimuth (step S2 in FIG. 15). Subsequently, the tag search device 100 divides all directions over 360 degrees around the tag search device 100 into sampling points separated by a sampling step angle Δ, as shown in FIG. Subsequently, as shown in FIG. 14, the tag search device 100 has received radio wave intensity measured for each azimuth angle within an angular range that extends to the left and right over an angular range represented by the calculation range angle δ around each sampling point. Is averaged (step S3 in FIG. 15). At this time, the sampling step angle Δ is set to Δ = 10 °, for example, and the average value is calculated within a calculation range angle δ (for example, δ = 30 °) around the sampling point. Note that when the number of measured values of the received radio wave intensity measured within the calculation range is less than a certain value (for example, two), the sampling point may be treated as having no received intensity data. As described above, by measuring the received radio wave intensity at each azimuth corresponding to each sampling point in FIG. 14 with reference to the correct direction in which the wireless tag 200n is actually located, the antenna orientation of the tag search device 100 is measured. Gender specific reference data is obtained.

  A specific calculation example of the reference data is shown in the numerical table of FIG.

  As described above, the direction estimation method according to the fourth embodiment is not based on the maximum intensity azimuth angle or the minimum intensity azimuth angle, but a curve representing the reference data and a curve representing the change in the received radio wave intensity during the RFID tag search. The direction of the wireless tag 200n is estimated on the basis of the maximum correlation shift amount that optimally matches. That is, the method according to the fourth embodiment does not focus only on a specific azimuth angle at which the radio wave reception intensity is maximized or minimized, but comprehensively considers the variation pattern of the received radio wave intensity over all directions. Then, the direction in which the wireless tag 200n is located is estimated. Therefore, in the method according to the fourth embodiment, both the maximum intensity azimuth angle and the minimum intensity azimuth angle are directions of the wireless tag 200n due to the antenna directivity distortion of the tag searching device 100 as shown in FIG. 9B. Even in the case of a large deviation from, the direction in which the wireless tag 200n is located can be estimated with high accuracy.

  Furthermore, the direction estimation method according to the fourth embodiment actually measures reference data unique to the tag search device 100, and uses the maximum correlation shift amount obtained according to the unique reference data measurement result as a reference. The direction in which 200n is located is estimated. As a result, the direction estimation method according to the fourth embodiment is based on the reference data measurement result corresponding to the directionality distortion method, even if the reception antenna directionality distortion method differs for each tag search device. The direction of the wireless tag 200n can be estimated appropriately. This is because the directivity distortion of the receiving antenna described above in FIG. 9 is different for each tag search device, and the reference data is also different for each tag search device.

<5> Effects of this Embodiment As described above, the direction estimation methods described as the first to fourth examples with respect to this embodiment are based on the strength level of the received signal from the wireless tag to be searched. The direction estimation can be performed in consideration of an error generated between the direction in which the wireless tag is actually located and the direction in which the signal reception intensity from the wireless tag is maximized. Furthermore, the direction estimation methods described as the first to fourth examples with respect to the present embodiment are not limited to the above error even if the error differs depending on the antenna directivity for each wireless search device. In consideration of the influence of the wireless tag, it is possible to realize a mechanism for correctly estimating the direction of the wireless tag. Furthermore, the direction estimation method described as the first to fourth examples in relation to the present embodiment takes into account the above-described error by a simple calculation procedure with a small amount of calculation without depending on a hypothetical model or complicated statistical processing. Direction estimation can be realized. As a result, the direction estimation method according to the present embodiment relates to a direction estimation in consideration of an error generated between the direction in which the wireless tag is actually located and the direction in which the signal reception intensity is maximum. Unlike the disclosed invention, to realize a highly accurate direction estimation mechanism without implementing error estimation calculation that requires correctness of a hypothetical model and a large amount of information and a large amount of calculation accordingly. Can do.

[Appendix 1]
A wireless search device for searching for a radio based on the strength of a radio signal received from one or more radios:
A position estimation unit that estimates a direction in which the radio is located;
A sensor that detects a change in the direction of the wireless search device when the user holding the wireless search device changes direction;
A wireless communication unit that receives a wireless signal from the wireless device and measures the strength of the wireless signal; and
The position estimation unit
Means for recording, as a measurement result, the change in intensity measured by the wireless communication unit in association with a change in orientation detected by the sensor when the user changes the orientation;
Means for determining the orientation of the wireless search device that minimizes the intensity from the recorded measurement results;
Means for estimating the direction in which the radio is located based on the direction in which the intensity is minimal;
A wireless search device comprising:
[Appendix 2]
The position estimation unit further determines the direction of the wireless search device that maximizes the strength from the recorded measurement results, and based on the direction that maximizes the strength in addition to the direction that minimizes the strength. The wireless search device according to appendix 1, wherein a direction in which the wireless device is located is estimated.
[Appendix 3]
The position estimation unit estimates a direction in which the radio is located by further correcting the estimated direction by a calibration offset angle based on a direction in which the intensity is minimum and a direction in which the intensity is maximum. It is characterized by
The calibration offset angle is calculated by calculating an angular difference between the direction of the radio and the known direction estimated using a reference radio signal received from a radio installed in a known direction. The wireless search device according to supplementary note 2, which is an offset angle determined by the position estimation unit by calculating a statistical value as a sample value.
[Appendix 4]
A wireless search device for searching for a radio based on the strength of a radio signal received from one or more radios:
A position estimation unit that estimates a direction in which the radio is located;
A sensor that detects a change in the direction of the wireless search device when the user holding the wireless search device changes direction;
A wireless communication unit that receives a wireless signal from the wireless device and measures the strength of the wireless signal; and
The position estimation unit
Means for recording, as a measurement result, the change in intensity measured by the wireless communication unit in association with a change in orientation detected by the sensor when the user changes the orientation;
Means for calculating an azimuth shift amount of the reference curve that maximizes the correlation strength between the signal intensity change curve represented by the recorded measurement result and the reference curve;
Means for estimating a direction in which the radio is located based on the calculated azimuth shift amount;
With
The reference curve is obtained as an intensity change curve of the reference radio signal according to the azimuth angle by actually measuring the intensity of the reference radio signal received at every azimuth angle from a radio device installed in a known direction. A wireless search device.
[Appendix 5]
A method of searching for a radio by a radio search device based on the strength of radio signals received from one or more radios:
When a user holding the wireless search device changes its direction, it detects a change in the direction of the wireless search device using a dynamic sensor in the wireless search device and simultaneously receives a radio signal from the wireless device. Measuring the strength of the radio signal;
Recording the measured change in intensity as a measurement result in association with a change in orientation detected by the dynamic sensor;
Determining the orientation of the wireless search device that minimizes the intensity from the recorded measurement results;
Estimating the direction in which the radio is located based on the direction in which the intensity is minimal.
[Appendix 6]
Determining the orientation of the wireless search device that maximizes the intensity from the recorded measurement results,
The wireless search device according to appendix 5, wherein the estimating step further includes an operation of estimating a direction in which the radio is located based on a direction in which the strength is maximized in addition to a direction in which the strength is minimum. .
[Appendix 7]
The estimating step further estimates the direction in which the radio is located by further correcting the estimated direction by a calibration offset angle based on a direction in which the intensity is minimum and a direction in which the intensity is maximum. Further includes an action to
The calibration offset angle is calculated by calculating an angular difference between the direction of the radio and the known direction estimated using a reference radio signal received from a radio installed in a known direction. The method according to appendix 6, which is an offset angle determined by the position estimation unit by calculating a statistical value as a sample value.
[Appendix 8]
A method of searching for a radio by a radio search device based on the strength of radio signals received from one or more radios:
When a user holding the wireless search device changes its direction, it detects a change in the direction of the wireless search device using a dynamic sensor in the wireless search device and simultaneously receives a radio signal from the wireless device. Measuring the strength of the radio signal;
Recording the measured change in intensity as a measurement result in association with a change in orientation detected by the dynamic sensor;
Calculating an azimuth shift amount of the reference curve that maximizes the correlation strength between the signal intensity change curve represented by the recorded measurement result and the reference curve;
Estimating the direction in which the radio is located based on the calculated azimuth shift amount,
The reference curve is obtained as an intensity change curve of the reference radio signal according to the azimuth angle by actually measuring the intensity of the reference radio signal received at every azimuth angle from a radio device installed in a known direction. how to.

  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 Notification information receiving part 103 Wireless communication part 104 Display part 105 Storage part 106 User input / output part 107 Sensor 108 Transmission / reception antenna 110 Control signal transmission part 200 Wireless tag 201 Control part 202 Notification information transmission part 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 for displaying a radio tag position

Claims (2)

A wireless search device for searching for a radio based on the strength of a radio signal received from one or more radios,
A position estimation unit that estimates a direction in which the radio is located;
A sensor that detects a change in the direction of the wireless search device when the user holding the wireless search device changes direction;
A wireless communication unit that receives a wireless signal from the wireless device and measures the strength of the wireless signal; and
The position estimation unit
Means for recording, as a measurement result, the change in intensity measured by the wireless communication unit in association with a change in orientation detected by the sensor when the user changes the orientation;
Means for calculating an azimuth shift amount of the reference curve that maximizes the correlation strength between the signal intensity change curve represented by the recorded measurement result and the reference curve;
Means for estimating a direction in which the wireless device is located based on the calculated azimuth shift amount;
The reference curve is obtained as an intensity change curve of the reference radio signal according to the azimuth angle by actually measuring the intensity of the reference radio signal received at every azimuth angle from a radio device installed in a known direction. Wireless search device to do. A method of searching for a radio by a radio search device based on the strength of a radio signal received from one or more radios,
When a user holding the wireless search device changes its direction, it detects a change in the direction of the wireless search device using a dynamic sensor in the wireless search device and simultaneously receives a radio signal from the wireless device. Measuring the strength of the radio signal;
Recording the measured change in intensity as a measurement result in association with a change in orientation detected by the dynamic sensor;
Calculating an azimuth shift amount of the reference curve that maximizes the correlation strength between the signal intensity change curve represented by the recorded measurement result and the reference curve;
Estimating the direction in which the radio is located based on the calculated azimuth shift amount,
The reference curve is obtained as an intensity change curve of the reference radio signal according to the azimuth angle by actually measuring the intensity of the reference radio signal received at every azimuth angle from a radio device installed in a known direction. how to.

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