Wireless tag search assistance system and method

Abstract

This wireless tag search assistance method includes: a wireless tag; and a portable terminal that receives a radio wave emitted by the wireless tag. When the remaining battery amount of the wireless tag becomes equal to or less than a predetermined warning residual amount, the wireless tag transmits a battery exhaustion notification signal, and the portable terminal receives the signal. On the basis of the battery exhaustion notification signal, the portable terminal calculates the relative orientation of a transmission source of the battery exhaustion notification signal based on an observation point at which the battery exhaustion notification signal is received, and generates tag orientation information including terminal position information and the relative orientation at the observation point. When conducting a search after the wireless tag battery is exhausted, the portable terminal acquires terminal position information at a search point, and displays navigation information to the transmission source on the basis of the terminal position information and the tag orientation information.

Description

Wireless tag search support system and method

[0001] The present invention relates to a system and method for assisting in searching for a wireless tag.

[0002] Conventionally, there are systems for identifying the location of an item using a wireless tag. For example, Patent Document 1 discloses a system in which "a server is configured to communicate with a tag reading device via a network connection. The tag reading device is configured to search for and identify the location of an item within a predetermined range, and to determine location information of the item according to the strength of a signal emitted and detected by the electronic tag of the item. The location information is transmitted to the server via the network connection, and the server operates in a database and adds the location information in the original data format of the database (abstract excerpt)."

[0003] JP 2017-45440 A

[0004] According to Patent Document 1, by attaching a wireless tag to an item, the wireless signal emitted by the wireless tag can be received and the location of the item to which the wireless tag is attached can be identified based on the signal strength and receiving direction of the wireless signal. However, when the battery of the wireless tag runs out, the wireless tag no longer transmits the wireless signal, which leaves a problem in that it becomes impossible to obtain clues for searching for the item.

[0005] The present invention has been made in view of the above circumstances, and has as its object to provide assistance in searching for a wireless tag when the battery in the wireless tag runs out.

[0006] In order to solve the above problems, the present invention has the configuration described in the claims. As an example, the present invention is a radio tag search support system including a radio tag and a portable terminal that receives radio waves emitted by the radio tag, wherein the radio tag includes a battery, a tag transmitter, and a tag processor, and the portable terminal includes a terminal receiver that receives the radio waves emitted by the radio tag, a position detection sensor that detects terminal position information in an absolute coordinate system of the portable terminal, a terminal processor, and a display, and the tag processor controls transmission of a low battery notification signal to notify the tag transmitter that the battery is about to run out when the remaining battery level of the radio tag falls below a predetermined warning level. The terminal-side processor calculates, based on the battery low notification signal, the relative direction of the sender of the battery low notification signal relative to the observation point where the mobile terminal received the battery low notification signal, acquires the terminal position information from the position detection sensor at the observation point, generates tag direction information including the terminal position information and the relative direction at the observation point, and when searching for the wireless tag after its battery has run out, displays navigation information to the sender of the battery low notification signal on the display based on the terminal position information and the tag direction information acquired from the position detection sensor at the search point.

[0007] The present invention also provides a wireless tag search support method comprising a wireless tag and a portable terminal that receives radio waves emitted by the wireless tag, the method comprising the steps of: receiving, when the remaining battery level of the wireless tag falls below a predetermined warning level, a low-battery notification signal to notify the user that the wireless tag's battery is about to run out; calculating, based on the low-battery notification signal, a relative orientation of the source of the low-battery notification signal relative to an observation point where the portable terminal received the low-battery notification signal, acquiring terminal position information at the observation point, and generating tag orientation information including the terminal position information and the relative orientation; and, when searching for the wireless tag after its battery has run out, acquiring terminal position information at the search point, and displaying navigation information to the source of the low-battery notification signal on a display provided on the portable terminal based on the terminal position information and the tag orientation information.

[0008] According to the present invention, it is possible to assist in searching for a wireless tag when the battery in the wireless tag runs out. Objects, configurations, and effects other than those described above will become apparent from the following embodiments.

[0009] 9A is a schematic diagram of a wireless tag search support system. FIG. 9B is a schematic diagram of a wireless tag according to this embodiment. FIG. 9C is a front view of the exterior of a mobile terminal according to this embodiment. FIG. 9D is a schematic diagram of a mobile terminal according to this embodiment. FIG. 9E is a diagram illustrating processing in phase 1 at a first observation point by method A. FIG. 9F is a diagram illustrating processing in phase 1 at a second observation point by method A. FIG. 9G is a diagram illustrating processing in phase 2 by method A. FIG. 9H is a diagram illustrating processing in phase 1 by method B. FIG. 9H is a diagram illustrating processing in phase 2 by method B. FIG. 9I is a diagram illustrating an example of the orientation of the mobile terminal (when the mobile terminal is horizontal). FIG. 9I is a diagram illustrating an example of the orientation of the mobile terminal (when tilted relative to the horizontal plane). FIG. 9I is a diagram illustrating calculation processing of tag orientation information in an absolute coordinate system when the mobile terminal is tilted relative to the horizontal plane. FIG. 9I is a diagram explaining each parameter included in FIG. 9A is a diagram illustrating another example of terminal orientation information, illustrating the acquisition state of orientation information of a mobile terminal during automatic search just before the battery runs out. FIG. 9I is a diagram illustrating an example of an automatically captured image. FIG. 9I is a flowchart illustrating the processing flow in a case of a wireless method (Bluetooth, etc.) that measures distance based on radio wave intensity. FIG. 1 is a detailed explanatory diagram of the processing of phase 1. FIG. 2 is a detailed explanatory diagram of the processing of phase 2. FIG. 3 is a diagram showing the navigation processing from the search start point (point C) to the first observation position (point A) in navigation type 2. FIG. 4 is a diagram showing the navigation processing from the first observation position (point A) to the likely tag search candidate point (point X) in navigation type 2. FIG. 5 is a flowchart showing the processing flow of a wireless method that measures distance using radio wave intensity.

[0010] The present invention relates to a system and method for assisting in the search for a wireless tag whose battery has run out. Therefore, the present invention is expected to contribute to the achievement of Goal 8.2 of the United Nations' Sustainable Development Goals (SDGs), which aims to increase economic productivity through diversification, technological improvement, and innovation, particularly in industries that increase the value of goods and services and in labor-intensive industries, by improving the technology for managing the location of lost items and assisting in the search for such items in labor-intensive industries.

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In all the drawings for explaining the embodiments, the same components are generally designated by the same reference numerals, and repeated description thereof will be omitted.

[0012] First Embodiment FIG. 1 is a schematic diagram of a wireless tag search support system.

[0013] The wireless tag search support system 100 shown in FIG. 1 is configured by connecting a wireless tag 1 and a portable terminal 2 via wireless communication.

[0014] When the remaining battery power of the wireless tag 1 falls below a predetermined warning remaining power, the wireless tag 1 transmits a low battery notification signal to notify the user that the battery is about to run out.

[0015] When the mobile terminal 2 receives a low battery notification signal, it calculates the relative direction of the sender of the low battery notification signal based on the observation point where the mobile terminal 2 received the low battery notification signal, obtains terminal position information indicating the terminal position detected by the position detection sensor at the observation point, and generates and stores tag direction information indicating the terminal position information and the relative direction.

[0016] When searching for the wireless tag 1 after its battery has run out, a navigation screen 270 including navigation information from the search point to the source of the low-battery notification signal is displayed on the display 207 based on the terminal location information and tag direction information. In Figure 1, examples of navigation information displayed include a search target icon 271 indicating the source of the low-battery notification signal, a distance 272 from the search point to the search target icon 271, and a search guide arrow 273 indicating the direction of the source relative to the search point.

[0017] 1 shows a case where the wireless tag 1 has not moved from the position at the time when it transmitted the low-battery notification signal. In this case, the current location of the wireless tag 1 matches the transmitter 3, so the location indicated by the search target icon 271 is the same as the current location of the wireless tag 1.

[0018] On the other hand, if the wireless tag 1 moves further from the sender 3 that transmitted the low-battery notification signal, the location indicated by the search target icon 271 is the location of the sender 3, not the current location of the wireless tag 1. However, because the portable terminal 2 has information on the location where the wireless tag 1 last transmitted the low-battery notification signal, the wireless tag search support system 100 is characterized in that it indicates the location of the sender 3 as the most likely candidate location to search after the wireless tag 1's battery runs out, and provides support for searching for the wireless tag 1 with a dead battery.

[0019] FIG. 2 is a schematic diagram of the wireless tag according to this embodiment.

[0020] As shown in FIG. 2, the wireless tag 1 includes a microprocessor 101, a BT communication device 116 (BT: Bluetooth (registered trademark)), and a battery 120, which are connected to each other via a bus 121.

[0021] The microprocessor 101 monitors the remaining battery power of the battery 120, and controls the transmission of a low-battery notification signal when the battery is nearing exhaustion. Thus, the microprocessor 101 is an example of a tag-side processor.

[0022] The BT communicator 116 is an example of a tag-side transmitter that transmits a wireless signal.

[0023] The battery 120 is, for example, a button battery.

[0024] FIG. 3 is a front view of the appearance of the mobile terminal according to this embodiment, and FIG. 4 is a schematic diagram of the mobile terminal according to this embodiment.

[0025] As shown in Fig. 3, the surface of the mobile terminal 2 is provided with a home button 230, an earpiece 231, a notification lamp 232, an in-camera 206, a distance measurement sensor 213, a display 207, and a touch panel 208. In addition, although not shown in Fig. 3, the side of the mobile terminal 2 is provided with a volume button and a power button, the bottom is provided with a speaker 218 (see Fig. 4), a microphone 217 (see Fig. 4), a power and communication connector, and an earphone jack, and the back is provided with an out-camera 205 (see Fig. 4), a fingerprint sensor, etc. Note that the locations of these components do not have to be as shown in Fig. 3.

[0026] As shown in FIG. 4, the mobile terminal 2 includes a processor 201, a RAM 202, a ROM 203, a memory 204, an outer camera 205, an inner camera 206, a display 207, a touch panel 208, an acceleration sensor 209, a gyro sensor 210, a geomagnetic sensor 211, a position detection sensor 212, a distance measurement sensor 213, a telephone network communication device 214, a LAN communication device 215, a BT communication device 216, a microphone 217, a speaker 218, a key input I / F 219, and a battery 220, which are connected to each other via a bus 221.

[0027] The processor 201 is, for example, a CPU, and corresponds to an example of a terminal-side processor.

[0028] The ROM 203 stores a control program 251 that controls the basic operations of the portable terminal 2 .

[0029] The memory 204 is realized by an EPPROM such as a microSD card, and can store the wireless tag search support application 252 and data generated in the process and as a result of executing the processing program. The control program 251 and the wireless tag search support application 252 are loaded into the RAM 202 by the processor 201 and executed.

[0030] The acceleration sensor 209 is, for example, a three-axis acceleration sensor, and corresponds to a gravity-based sensor since it can detect the component of movement in the direction of gravity.

[0031] The gyro sensor 210 corresponds to an example of an attitude sensor because it can detect the angular velocity due to the rotational movement of the portable terminal 2 and detect the tilt with respect to a horizontal plane. The sensor output of the gyro sensor 210, or the tilt (pitch angle) of the reference axis of the portable terminal 2 with respect to a horizontal plane calculated based on the sensor output of the gyro sensor 210, is an example of attitude information.

[0032] The geomagnetic sensor 211 detects geomagnetism to detect the orientation in an absolute coordinate system, and thus corresponds to an example of an orientation sensor. In the processing described below, the angle (yaw angle) formed by the reference axis of the portable terminal 2 with an axis of the absolute coordinate system (e.g., the north-south axis) can be determined by using the orientation information detected by the geomagnetic sensor 211. When the orientation information is defined in an absolute coordinate system, the orientation as viewed from a reference point of the portable terminal 2 (e.g., the center point of the portable terminal 2 on the reference axis) is constant regardless of the orientation of the portable terminal 2, and therefore the pitch angle can be used as the orientation information. When the orientation information is not defined in an absolute coordinate system but is defined as a yaw angle with respect to the reference axis of the portable terminal 2, the orientation information includes the yaw angle.

[0033] The position detection sensor 212 is a sensor that detects position information in an absolute coordinate system, and may be, for example, a GPS sensor.

[0034] The distance measurement sensor 213 is realized by, for example, a distance sensor using a stereo camera, or a distance measurement sensor (for example, an ultrasonic distance measurement sensor) using a wireless communication method that measures distance using a response time (TOF (Time of Flight)).

[0035] The telephone network communication device 214 is a type of communication device that realizes communication functions for mobile communication such as 4G and 5G.

[0036] The LAN communication device 215 is a type of communication device that realizes a wireless communication function using the Wi-Fi (registered trademark) standard or the like.

[0037] The BT communication device 216 is a type of communication device used for communication connection between the wireless tag 1 and the portable terminal 2, and functions as a detector for detecting the direction of the transmitter 3 used in the process of FIG.

[0038] The processing of the wireless tag search support system 100 according to this embodiment can be broadly divided into phase 1 (a phase in which tag direction information from the observation point to the sender 3 of the low battery notification signal is automatically generated and saved) and phase 2 (a search phase based on the tag direction information).

[0039] The wireless tag search support system 100 stores the observation position information of the wireless tag 1 (corresponding to the position information of the transmitter 3) just before the battery runs out in the mobile terminal 2 (phase 1), and during the search after the battery runs out (phase 2), it uses the current position information of the mobile terminal 2 at the start of the search and the observation position information of the wireless tag 1 to navigate the user to the position where the wireless tag 1 was located before the battery ran out (corresponding to the position of the transmitter 3) using the principle of triangulation (see Figure 5).

[0040] There are two methods for obtaining location information of the wireless tag 1 just before the battery runs out in phase 1 prior to the search, depending on the wireless method: (Method A) a wireless method that measures distance based on radio wave strength (Bluetooth (registered trademark), etc.), and (Method B) a wireless method that measures distance based on response time (UWB, etc.).

[0041] In this embodiment, when the observation location information of the wireless tag 1 is stored in the mobile terminal 2, the battery is already close to running out, so even if direction information can be obtained, the accuracy of the detected distance information is considered to be unreliable due to the unstable radio wave strength caused by the battery being close to running out.

[0042] Therefore, in (Method A), the movement (detection) of the portable terminal 2 is utilized to store the position information of the point where the (horizontal) direction vectors from two points intersect as the observation position information of the wireless tag 1. When actually implementing the system, the observation position information of the wireless tag 1 may be stored as the position information of the two observation points and the vector information from each, and the observation position of the wireless tag 1 may be calculated during an actual search.

[0043] On the other hand, in the case of (Method B), distance measurement is performed during the response time, so if radio waves can be observed, the accuracy of distance information is considered to be high. Therefore, the direction vector and distance are calculated and stored as the position information of the wireless tag 1 at the time of observation. In this case as well, when implementing an actual system, the position information of the observation point, vector information, and distance information may be stored as the position information of the wireless tag 1 at the time of observation, and the position of the wireless tag 1 may be calculated during a search.

[0044] (Method A) Figure 5A is a diagram showing the processing of Phase 1 at a first observation point by Method A, Figure 5B is a diagram showing the processing of Phase 1 at a second observation point by Method A, and Figure 5C is a diagram showing the processing of Phase 2 by Method A.

[0045] In Figure 5A, at a first observation point (point A), the mobile device 2 receives a radio wave signal indicating a low battery at point A. Point A is the first observation point immediately before the battery runs out. Based on the direction of the radio wave reception, the direction of the transmitter 3 of the wireless tag 1 as seen from point A (first direction, corresponding to the "relative orientation") is determined, and a first direction vector is calculated and stored. Note that because the radio wave strength is unreliable, the distance from point A to the observation point of the wireless tag 1 is unknown, and the first direction vector may be a unit length since the distance is unknown. The mobile device 2 also detects its terminal position at the first observation point (point A) using the position detection sensor 212.

[0046] Similarly, in phase 1 shown in FIG. 5B , the mobile device 2 receives the radio wave of the battery low notification signal at a second observation point (point B). Point B is the second observation point immediately before the battery runs out. Based on the direction of the radio wave reception, the direction of the transmitter 3 of the wireless tag 1 as seen from point B (second direction, corresponding to the "relative orientation") is determined, and a second direction vector is calculated and stored. Note that because the radio wave strength is unreliable, the distance from point B to the observation point of the wireless tag 1 is unknown, and the second direction vector may be of unit length since the distance is unknown. The mobile device 2 also detects the terminal position at the second observation point (point B) using the position detection sensor 212.

[0047] The mobile terminal 2 then identifies the intersection of the extension of the first direction vector starting from point A and the extension of the second direction vector starting from point B as the source 3 (point X). Furthermore, the vector from point A to the source 3 (point X) is identified as the tag orientation vector V ＡＸ The tag orientation vector V Ａｘ is a form of tag orientation information. The tag orientation vector V Ａｘ The mobile terminal 2 automatically generates and stores the image data without any user operation. This completes the processing of Phase 1.

[0048] In phase 2 shown in FIG. 5C, the portable device 2 acquires current position information of the search start point (point C) from the position detection sensor 212. Then, based on the position information of the observation point (point A) and the search start point (point C) in the absolute coordinate system, a vector V heading from point C to point A is calculated. ＣＡ Then, the vector V ＣＡ The tag orientation vector V Ａｘ Adding these gives us the vector V ＣＸ The vector V is calculated and the navigation screen 270 is displayed on the mobile terminal 2. ＣＸ indicates the direction and distance from point C to the point where the wireless tag 1 was identified as being located just before the battery ran out.

[0049] (Method B) FIG. 6A is a diagram showing a process in phase 1 according to method B, and FIG. 6B is a diagram showing a process in phase 2 according to method B.

[0050] In phase 1 shown in FIG. 6A, first, when the remaining charge of the battery 120 falls below the warning remaining charge, the wireless tag 1 transmits a low-battery notification signal.

[0051] The mobile terminal 2 uses the observation point (point A) just before the battery ran out where the battery low notification signal was received as a reference point, estimates the estimated location (point X) of the sender 3 of the battery low notification signal from the reception direction of the antenna built into the mobile terminal 2, and estimates the distance from the radio wave intensity. Ａｘ is generated. The tag orientation vector V Ａｘ The direction indicates the receiving direction by the antenna, and the length indicates the distance to the source estimated from the radio wave strength.

[0052] In this state, suppose the battery of the wireless tag 1 runs out. If the user subsequently starts a search for the item to which the wireless tag 1 is attached, the search for the item becomes impossible because no response signal is emitted from the wireless tag 1. Therefore, the user uses the location information (location information of the transmitter 3) immediately before the battery of the wireless tag 1 runs out as a clue to calculate likely search candidate points during the search for the wireless tag 1 (after the battery runs out) and display navigation information to get there, which is the phase 2 described above.

[0053] In phase 2 shown in FIG. 6B, the vector V ＣＡ After calculating the tag orientation vector V Ａｘ Adding these gives us the vector V ＣＸ Ask for.

[0054] FIG. 7A is a diagram showing an example of the orientation of the mobile terminal (when the mobile terminal is horizontal), and FIGS. 7B and 7C are diagrams showing an example of the orientation of the mobile terminal (when the mobile terminal is tilted relative to the horizontal plane).

[0055] 7A , when the portable terminal 2 is horizontal, the search guide arrow 273 and the terminal reference axis vector Vo coincide with each other when the portable terminal 2 is rotated in the horizontal plane so that the terminal reference axis vector Vo points toward the wireless tag 1. The terminal reference axis vector Vo is a vector that passes through the terminal position and is parallel to the long side of the rectangular portable terminal 2.

[0056] However, when the portable terminal 2 is tilted relative to the horizontal plane as shown in Figures 7B and 7C, the search guide arrow 273 and the terminal reference axis vector Vo do not coincide even if the portable terminal 2 is rotated in the horizontal plane. Therefore, in this case, the tag orientation vector V is calculated based on the attitude information of the portable terminal 2. Ａｘ Correct the following.

[0057] FIG. 8 is a diagram showing a process for calculating tag orientation information in an absolute coordinate system when the mobile terminal is tilted relative to the horizontal plane.

[0058] As shown in Fig. 8, the mobile terminal 2 calculates a terminal reference axis vector Vo that passes through the terminal position and is parallel to the terminal reference axis. Then, the terminal reference axis vector Vo and the tag orientation vector V Ａｘ Relative relationship information (for example, terminal reference axis vector Vo and tag orientation vector V ＡｘThis calculation can be done using existing technology.

[0059] Next, the portable device 2 acquires GPS sensor information, geomagnetic sensor information, and gravity sensor information obtained when it receives the low-battery notification signal.The portable device 2 then determines the starting point of the reference axis from the GPS sensor information.Furthermore, the portable device 2 determines, as attitude information, the direction in which the terminal reference axis is facing (north, south, east, west in a horizontal plane) from the geomagnetic sensor information, and the rotation angle of the terminal reference axis relative to the horizontal plane from the weight sensor information.

[0060] The mobile terminal 2 uses the tag orientation vector V Ａｘ Vector V indicating source 3 (point X) from the search point (point C) obtained from ＣＸ1 is corrected using the attitude information, and a search guide arrow 273 is displayed on the navigation screen 270. Note that point a in Fig. 8 corresponds to the point obtained by correcting the origin 3 (point X) identified assuming that the portable terminal 2 is in a horizontal position using the attitude information.

[0061] Fig. 9A is a diagram showing tag orientation information stored in phase 1. Fig. 9B is a diagram explaining each parameter included in Fig. 9A.

[0062] 9A, the mobile terminal 2 calculates the elevation angle, azimuth angle, and rotation angle of the reference axis based on weight-based sensor information from the gravity-based sensor (three-axis acceleration sensor), and converts these into an elevation angle α and azimuth angle β of the direction (tag direction) indicating the transmitter 3. The mobile terminal 2 then saves the "terminal location information," "tag direction," and tag-terminal distance as information immediately before the battery runs out.

[0063] The elevation angle θ in Fig. 9B indicates the tilt of the reference axis with respect to the horizontal plane, and the azimuth angle δ indicates north, south, east, and west. According to the tag orientation information in Fig. 9, even if the orientation of the portable terminal 2 when the tag orientation information is automatically generated is tilted with respect to the horizontal plane, the tag orientation information can be generated by correcting the tilt to be parallel to the horizontal plane. Therefore, even if the orientation during the search is different from that when the tag orientation information is acquired, the search guide arrow 273 can be displayed more accurately.

[0064] FIG. 10A is a diagram showing another example of terminal attitude information, showing the state of acquisition of the mobile terminal attitude information during automatic search just before the battery runs out, and FIG. 10B is a diagram showing an example of an automatically captured image.

[0065] As shown in FIG. 10A, when the mobile terminal 2 receives a low battery notification signal (phase 1), it automatically captures an image using at least one of the in-camera 206 or the out-camera 205, and preferably both, and generates and saves an image of the terminal posture at the time the low battery notification signal is received.

[0066] During the search (phase 2), the user visually checks the terminal orientation image to ascertain the position and orientation of the mobile terminal 2 when it received the low-battery notification signal. For example, the terminal orientation image in Fig. 10B shows the ceiling 300 and the light 301, making it possible to identify the room in which they are located. Furthermore, the orientation of the mobile terminal 2 when it received the low-battery notification signal can be estimated from the direction in which the light 301 is visible in the identified room.

[0067] (Processing Flow) Fig. 11 is a flowchart showing the processing flow in the case of a wireless method (Bluetooth, etc.) that measures distance based on radio wave intensity. Fig. 12 is a detailed explanatory diagram of the processing in Phase 1. Fig. 13 is a detailed explanatory diagram of the processing in Phase 2.

[0068] 11, the portable terminal 2 waits for reception of a low battery notification signal (S11: N). When the portable terminal 2 receives the low battery notification signal (S11: Y), phase 1 starts.

[0069] (Phase 1) In step 1 of phase 1, the portable terminal 2 acquires position information of the first observation position (point A) from the position detection sensor 212. The portable terminal 2 also acquires first direction information (first direction vector) of the source 3 viewed from the first observation position (point A) by essentially using all of the sensor information from the wireless tag communication, the geomagnetic sensor 211, the acceleration sensor 209, and the gyro sensor 210 (see FIG. 12 : Step 1). Note that the portable terminal 2 may use only a portion of the sensor information from the wireless tag communication, the geomagnetic sensor 211, the acceleration sensor 209, and the gyro sensor 210, rather than all of the sensor information.

[0070] The start of step 2 of phase 1 is awaited until the terminal position of the portable terminal 2 has moved for a certain period of time (S12: N). If the terminal position of the portable terminal 2 has moved for a certain period of time (S12: Y), the process of step 2 of phase 1 is started. Here, "certain movement" refers to movement to the extent that the relative directions of the wireless tag 1 and the portable terminal 2 change, and movement that allows three-point positioning. Therefore, movement of the portable terminal 2 along an extension line indicated by the tag orientation information is not included in "certain movement."

[0071] In step 2 of phase 1 ( FIG. 12 : Step 2), the mobile terminal 2 acquires the current position of a second observation position (point B), which is different from the first observation position (point A), from the position detection sensor 212. The mobile terminal 2 also acquires second direction information (second direction vector) of the source 3 viewed from the second observation position (point B) by essentially using all or appropriately selecting information from the sensors of the wireless tag communication, the geomagnetic sensor 211, the acceleration sensor 209, and the gyro sensor 210.

[0072] In step 3 of Phase 1 (FIG. 12: Step 3), the portable device 2 determines the location of the source 3 (location X) as the intersection of the extension line indicated by the first direction information from the first observation location (location A) and the extension line indicated by the second direction information from the second observation location (location B), and calculates the distance from the first observation location (location A) to the source 3 (location X). Then, using the location information of the first observation location (location A), the first direction information from the first observation location (location A), and the distance from the first observation location (location A) to the source 3 (location X), the portable device 2 calculates and saves tag orientation information (tag orientation vector) (see FIG. 12: Step 3). After Phase 1 is completed, the portable device 2 transitions to Phase 2.

[0073] In phase 2, the portable terminal 2 waits for a tag search start instruction (S21: N). When the portable terminal 2 receives the tag search start instruction (S21: Y), it acquires the position information of the search start point (point C) from the position detection sensor 212 (S22).

[0074] The mobile terminal 2 calculates tag search navigation information from the search start point (point C) to the source 3 based on the location information of the first observation position (point A) and the search start point (point C), the tag's orientation information as seen from the first observation position (point A), and the distance from the first observation position (point A) to the source 3 (point X) (S23).

[0075] The portable terminal 2 displays the navigation screen 270 showing tag search navigation from the search start point (point C) to the call source 3, and performs navigation (S24).

[0076] As shown in Figure 13, there are two types of tag search navigation: navigation type 1, which generates and displays a search guide arrow 273 from the search start point (point C) to the intersection point (point X), and navigation type 2, which first navigates from the search start point (point C) to the first observation position (point A), and then displays a search guide arrow 273 from the first observation position (point A) to the intersection point (point X) when the user holds the mobile terminal 2 and moves to the first observation position (point A).

[0077] Figure 14A is a diagram showing the navigation processing from the search start point (point C) to the first observation position (point A) in navigation type 2, and Figure 14B is a diagram showing the navigation processing from the first observation position (point A) to the likely tag search point (point X) in navigation type 2.

[0078] 14A, in navigation type 2, first, the portable terminal 2 displays navigation information (an arrow indicating point A) from the search start point (point C) to the first observation position (point A) on the display 207. Then, when the user reaches the first observation position (point A), the portable terminal 2 displays navigation information (an arrow indicating point X) from the first observation position (point A) on the display 207, as shown in FIG.

[0079] 15 is a flowchart showing the flow of processing in a wireless method for measuring distance based on radio wave intensity. Processing common to that in FIG. 11 is assigned the same step numbers and redundant explanations will be omitted.

[0080] 11 is that steps 1 and 3 of phase 1 are executed, but step 2 is not included. That is, in a wireless method that measures distance using radio wave intensity, in step 1 of phase 1, the portable terminal 2 acquires the current position of the first observation position (point A) from the position detection sensor 212, and also acquires first direction information that indicates the direction of the source 3 (point X) as seen from the first observation position (point A) (see Step 1 in FIG. 12).

[0081] Next, the portable terminal 2 calculates and stores tag direction information indicating the direction and distance from the current position of the first observation position (point A) to the sender 3 (point X) of the battery low notification signal, using the radio wave intensity of the battery low notification signal, the distance to the sender 3 of the battery low notification signal, and the first direction information. The subsequent phase 2 is the same as in Fig. 11, and therefore its description will be omitted.

[0082] According to this embodiment, the wireless tag 1 transmits a low-battery notification signal just before the battery runs out, and the portable terminal 2 that receives this signal calculates and stores tag direction information including the direction and distance from the observation position to the source 3. This process (phase 1) is performed automatically, so it does not require any user intervention.

[0083] If the battery of the wireless tag 1 has already run out when searching for an article with the wireless tag 1 attached, there will be no response from the wireless tag 1. In this case, if the user executes the processing in phase 2, the user can navigate to the transmitter 3 based on the tag direction information as the most likely search location where the wireless tag 1 was located just before the battery ran out. This allows the user to obtain clues for searching for the wireless tag 1 when there is no response from the wireless tag 1 due to a dead battery, making the search for the wireless tag 1 easier.

[0084] The invention made by the inventor has been specifically described above based on the embodiments thereof, but it goes without saying that the present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention.

[0085] For example, Bluetooth (registered trademark) and UWB have been exemplified as indoor positioning systems, but other wireless communication methods suitable for indoor positioning can also be applied to the present invention.

[0086] The above embodiment includes the following aspects.

[0087] (Supplementary Note 1) A wireless tag search support system comprising a wireless tag and a mobile terminal that receives radio waves emitted by the wireless tag, wherein the wireless tag comprises: a battery; a tag-side transmitter; and a tag-side processor; and the mobile terminal comprises: a terminal-side receiver that receives the radio waves emitted by the wireless tag; a position detection sensor that detects terminal position information in an absolute coordinate system of the mobile terminal; a terminal-side processor; and a display; when the remaining battery level of the wireless tag falls below a predetermined warning level, the tag-side processor controls transmission of a low-battery notification signal to notify the tag-side transmitter that the battery is about to run out; and the terminal-side processor calculates, based on the low-battery notification signal, a relative orientation of a sender of the low-battery notification signal with reference to an observation point where the mobile terminal received the low-battery notification signal; acquires the terminal position information from the position detection sensor at the observation point; and generates tag orientation information including the terminal position information and the relative orientation at the observation point. A wireless tag search support system characterized in that, when searching after the wireless tag's battery runs out, navigation information to the source of the battery dead notification signal is displayed on the display based on the terminal position information and tag direction information obtained from the position detection sensor at the search point.

[0088] (Supplementary Note 2) A wireless tag search support method comprising a wireless tag and a portable terminal that receives radio waves emitted by the wireless tag, comprising: a step of receiving, when the remaining battery level of the wireless tag falls below a predetermined warning level, a low-battery notification signal to notify that the battery of the wireless tag is about to run out; a step of calculating, based on the low-battery notification signal, a relative orientation of a source of the low-battery notification signal with respect to an observation point where the portable terminal received the low-battery notification signal, acquiring terminal position information at the observation point, and generating tag orientation information including the terminal position information and the relative orientation; and a step of acquiring terminal position information at a search point when searching for the wireless tag after the battery has run out, and displaying navigation information to the source of the low-battery notification signal on a display provided on the portable terminal based on the terminal position information and the tag orientation information.

[0089] 1: Wireless tag 2: Portable terminal 3: Transmitter 100: Wireless tag search support system 101: Microprocessor 116: Bluetooth communication device 120: Battery 121: Bus 201: Processor 202: RAM 203: ROM 204: Memory 205: Outer camera 206: Inner camera 207: Display 208: Touch panel 209: Acceleration sensor 210: Gyro sensor 211: Geomagnetic sensor 212: Position detection sensor 213: Distance measurement sensor 214: Telephone network communication device 215: LAN communication device 216: Bluetooth communication device 217: Microphone 218: Speaker 219: Key input I / F 220: Battery 221: Bus 230 : Home button 231 : Earpiece 232 : Notification light 251 : Control program 252 : Wireless tag search support application 270 : Navigation screen 271 : Search target icon 272 : Distance 273 : Search guide arrow 300 : Ceiling 301 : Lighting

Claims

1. A radio tag search support system comprising a radio tag and a portable terminal that receives radio waves emitted by the radio tag, wherein the radio tag comprises a battery, a tag side transmitter, and a tag side processor, and the portable terminal comprises a terminal side receiver that receives radio waves emitted by the radio tag, a position detection sensor that detects terminal position information in an absolute coordinate system of the portable terminal, a terminal side processor, and a display, wherein when the remaining battery level of the radio tag falls below a predetermined warning level, the tag side processor controls the transmission of a battery low notification signal to notify the tag side transmitter that the battery is about to run out, and the terminal side processor calculates, based on the battery low notification signal, a relative orientation of a sender of the battery low notification signal based on an observation point at which the portable terminal received the battery low notification signal, acquires the terminal position information from the position detection sensor at the observation point, and generates tag orientation information including the terminal position information and the relative orientation at the observation point, a wireless tag search support system that, when searching for the wireless tag after the battery runs out, displays navigation information to the source of the battery dead notification signal on the display based on the terminal position information and the tag orientation information obtained from the position detection sensor at the search location.

2. A wireless tag search support system as described in claim 1, wherein the terminal side processor calculates the distance and relative direction to the source of the battery low notification signal based on the radio wave strength and receiving direction of the battery low notification signal as the relative direction, and generates the tag direction information including the terminal position information at the observation point and the distance and relative direction to the source of the battery low notification signal based on the observation point.

3. A wireless tag search support system as described in claim 1, wherein the terminal processor, upon receiving the battery low notification signal at a first observation point, controls transmission of a search signal for the wireless tag from the first observation point, calculates a first distance from the first observation point to a source of the battery low notification signal based on a response time from emitting the search signal to receiving a response signal from the wireless tag to the search signal, acquires first terminal position information which is the terminal position information at the first observation point, and generates first tag orientation information including the first distance and the first terminal position information; upon receiving the battery low notification signal again at a second observation point, controls transmission of a search signal for the wireless tag from the second observation point, calculates a second distance from the second observation point to a source of the battery low notification signal based on a response time from emitting the search signal to receiving a response signal from the wireless tag to the search signal, acquires second terminal position information which is the terminal position information at the second observation point, and generates second tag orientation information including the second distance and the second terminal position information; a point that is the first distance from the first observation point and the second distance from the second observation point based on the first tag orientation information and the second tag orientation information, is calculated as the point of origin of the low battery notification signal, and the tag orientation information indicating that point is generated.

4. A wireless tag search support system as described in claim 1, wherein the mobile terminal further comprises a gravity sensor that detects the attitude of the mobile terminal, and the terminal side processor acquires attitude information of the mobile terminal at the observation point, further includes the attitude information in the tag orientation information, and displays the navigation information using the attitude information included in the tag orientation information.

5. A radio tag search support system as described in claim 1, characterized in that the terminal processor displays the navigation information that leads directly from the search point to the source without passing through the observation point.

6. A wireless tag search support system as described in claim 1, characterized in that the terminal side processor displays the navigation information from the search point to the observation point, and when the mobile terminal moves to the observation point, displays the navigation information from the observation point to the source.

7. A wireless tag search support method comprising a wireless tag and a portable terminal for receiving radio waves emitted by the wireless tag, comprising the steps of: receiving a low-battery notification signal for notifying the user that the wireless tag's battery is about to run out when the remaining battery level of the wireless tag falls below a predetermined warning level; calculating a relative orientation of a source of the low-battery notification signal based on the low-battery notification signal and using the low-battery notification signal as a reference from an observation point where the portable terminal received the low-battery notification signal, acquiring terminal position information at the observation point, and generating tag orientation information including the terminal position information and the relative orientation; and acquiring terminal position information at the search point when searching for the wireless tag after the battery runs out, and displaying navigation information to the source of the low-battery notification signal on a display provided on the portable terminal based on the terminal position information and the tag orientation information.

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