Location measurement system, information terminal, location measurement program, and location measurement method

Abstract

This technology uses radio waves other than GNSS to measure the location of information terminals, enabling the estimation of the location of information terminals receiving radio waves from multiple radio transmitters, even if the location information of those transmitters cannot be obtained in advance. [Solution] The location measurement system includes a communication circuit that receives location information relating to the location of an information terminal by performing data communication with the information terminal, and also receives radio wave information including radio wave strength information relating to the strength of radio waves received by the information terminal from multiple radio wave transmitters; a reference data creation unit that creates reference data relating to the relationship between multiple locations and the radio wave strength from each radio wave transmitter based on the location information and radio wave information obtained at multiple locations; and a location estimation unit that estimates the location of the information terminal based on the reference data created by the reference data creation unit and the radio wave information from multiple radio wave transmitters received from the information terminal by the communication circuit.

Description

[Technical Field]

[0001] The present invention relates to an information terminal that can receive radio waves transmitted from a radio wave transmitting device and is also transportable or movable, and a location measurement system for measuring the location of such an information terminal. Furthermore, the present invention relates to a location measurement program and a location measurement method used in such a location measurement system or information terminal. [Background technology]

[0002] For example, in order to secure a building, it may be necessary to know the location of information terminals such as smartphones carried by security guards patrolling the building's interior. GNSS (Global Navigation Satellite System) is used as the location measurement technology for smartphones and is an essential element of autonomous driving for mobile vehicles such as automobiles. However, in fields where radio waves transmitted from positioning satellites are blocked by buildings, etc., location measurement becomes difficult. Therefore, technologies that measure location using radio waves other than GNSS are also being developed.

[0003] As a related technology, Patent Document 1 discloses a positioning device aimed at improving the positioning accuracy of a radio wave receiving device, in light of the fact that when the base station used for calculating three-point positioning switches due to the movement of the receiving terminal, a phenomenon occurs in which the positioning position of the receiving terminal suddenly changes drastically, making it easy for the positioning accuracy to deteriorate.

[0004] The positioning device of Patent Document 1 includes means for calculating the position of a radio wave receiving device for each combination of three different radio wave transmitting devices using the radio wave strengths of three of the four or more radio wave transmitting devices; means for calculating the distance from the four or more radio wave transmitting devices to the radio wave receiving device using the radio wave strengths, finding the reciprocal of the sum of the distances from the radio wave transmitting devices for each combination, and calculating a weighting coefficient for the position of the radio wave receiving device for each combination by dividing the reciprocal for each combination by the sum of the reciprocals for all combinations; and means for multiplying the position of the radio wave receiving device by the weighting coefficient for each combination, and taking the sum of the multiplied values ​​as the positioning position of the radio wave receiving device.

[0005] Furthermore, Patent Document 2 discloses a location estimation device that aims to estimate the location information of users who have not authorized the provision of their location information, in light of the fact that in recent years, from the perspective of protecting personal information, there has been a trend towards stricter restrictions on the transmission of location information of personal terminal devices such as smartphones to external parties due to the specifications of such devices.

[0006] The location estimation device described in Patent Document 2 includes an acquisition unit that acquires location information and radio wave information corresponding to said location information from a user terminal of a licensed user who has authorized the provision of location information; a learning unit that learns the characteristics of the radio wave information for each region corresponding to said location information based on the location information and radio wave information acquired by the acquisition unit; and an estimation unit that estimates the region of said user terminal using the radio wave information acquired from the user terminal based on the learning results by the learning unit.

[0007] Furthermore, Patent Document 3 discloses a system for positioning using non-GPS information when a GPS-only solution is not available, which uses the signal strength of a signal received from an identifiable source to determine the location of a wireless device.

[0008] The system described in Patent Document 3 comprises a database configured to maintain predicted signal strengths of signals within a geographic area, a mapper that identifies regions of the geographic area, and one or more servers that locate the wireless device within one of the identified regions based on the signal strength measured by the wireless device. Each region is characterized by a range of predicted signal strengths for each of the one or more signals detectable within the respective region. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Japanese Patent Publication No. 2017-181166 (paragraphs 0006-0009, 0030-0040, Figure 9-10) [Patent Document 2] Japanese Patent Publication No. 2023-076239 (paragraphs 0004-0006, 0017) [Patent Document 3] Special Publication No. 2010-500604 (Paragraphs 0001-0004, 0015, Claim 22) [Disclosure of the Invention] [Problems that the invention aims to solve]

[0010] However, in Patent Document 1, the administrator or other relevant party must associate the identification IDs and location information of the four radio wave transmitters and store them in advance as base station information in the base station information storage DB (database) of the base station information storage device. Furthermore, since the distance from each radio wave transmitter to the radio wave receiver is directly calculated using the radio wave strength of the four radio wave transmitters, there is a risk that the positioning accuracy will deteriorate if the radio wave strength is weak.

[0011] In Patent Document 2, the precise position information of a user terminal is not estimated, and position information is estimated on an area basis. Similarly, in Patent Document 3 as well, the precise position of a wireless device is not identified, and for example, the wireless device is estimated to be located in a geographical area where the signal strength is measured between -100dBm and -80dBm.

[0012] In view of the above points, a first object of the present invention is to enable estimation of the position of an information terminal that receives radio waves transmitted from a plurality of radio wave transmitters, even when the position information of the plurality of radio wave transmitters cannot be obtained in advance, when the position of the information terminal is measured using radio waves other than GNSS. A second object of the present invention is to estimate the position of the information terminal by narrowing it down to a point, instead of estimating the position on an area basis. Furthermore, a third object of the present invention is to improve positioning accuracy even when the radio wave intensity from the radio wave transmitter is weak. [Means for Solving the Problems]

[0013] To solve at least part of the above problems, a position measurement system according to a first aspect of the present invention is a position measurement system for measuring the position of an information terminal capable of receiving radio waves transmitted from radio wave transmitters, the position measurement system being , love a communication circuit that performs data communication with the information terminal to receive position information related to the position of the information terminal, and receives radio wave information including radio wave intensity information related to the intensity of radio waves that the information terminal has received from the plurality of radio wave transmitters, and In advance at a plurality of positions Collect a reference data creation unit that creates reference data related to the relationship between the plurality of positions and the radio wave intensity from each of the radio wave transmitters, based on the received position information and the radio wave information, and The communication circuit extracts a predetermined number of reference data where the difference in radio wave intensity between the radio wave information received from the information terminal and the radio wave intensity from each radio wave transmitter is small. Using the extracted reference data, the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between the position and the radio wave intensity from each radio wave transmitter are determined. By comparing the radio wave intensity from each radio wave transmitter in the radio wave information with the radio wave intensity calculated for multiple positions using the predetermined number of parameters, it is possible to obtain the necessary information without using the position information of the radio wave transmitters. a position estimation unit that estimates the position of the information terminal.

[0014] Furthermore, the position measurement program according to the first aspect of the present invention is a position measurement program used for measuring the position of the information terminal in a position measurement system that performs data communication with an information terminal capable of receiving radio waves transmitted from a radio wave transmission device, the position measurement program being configured to , love a step (a) of receiving position information related to the position of the information terminal, and receiving radio wave information including radio wave intensity information related to the intensity of radio waves received by the information terminal from a plurality of radio wave transmission devices, and at a plurality of positions Collect a step (b) of creating reference data related to the relationship between a plurality of positions and the radio wave intensity from each radio wave transmission device, based on the acquired position information and the radio wave information, and A predetermined number of reference data points are extracted from the radio wave information received from the information terminal, where the difference in radio wave intensity between the radio wave intensity from each radio wave transmitting device is small. Using the extracted reference data, the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between the location and the radio wave intensity from each radio wave transmitting device are determined. By comparing the radio wave intensity from each radio wave transmitting device in the radio wave information with the radio wave intensity calculated for multiple locations using the predetermined number of parameters, it is possible to obtain the necessary information without using the location information of the radio wave transmitting device. causing a CPU to execute a step (c) of estimating the position of the information terminal.

[0015] Furthermore, the position measurement method according to the first aspect of the present invention is a position measurement method for measuring the position of the information terminal in a position measurement system that performs data communication with an information terminal capable of receiving radio waves transmitted from a radio wave transmission device, the position measurement method comprising , love a step (a) of receiving position information related to the position of the information terminal, and receiving radio wave information including radio wave intensity information related to the intensity of radio waves received by the information terminal from a plurality of radio wave transmission devices, and at a plurality of positions Collect a step (b) of creating reference data related to the relationship between a plurality of positions and the radio wave intensity from each radio wave transmission device, based on the acquired position information and the radio wave information, and A predetermined number of reference data points are extracted from the radio wave information received from the information terminal, where the difference in radio wave intensity between the radio wave intensity from each radio wave transmitting device is small. Using the extracted reference data, the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between the location and the radio wave intensity from each radio wave transmitting device are determined. By comparing the radio wave intensity from each radio wave transmitting device in the radio wave information with the radio wave intensity calculated for multiple locations using the predetermined number of parameters, it is possible to obtain the necessary information without using the location information of the radio wave transmitting device. a step (c) of estimating the position of the information terminal.

[0016] An information terminal according to the second aspect of the present invention is Radio wave transmitting device a communication circuit that receives radio waves transmitted from, and (1) in a data collection mode, causes a display unit to display an image of a designated map, generates position information related to a position designated on the map image, and collects radio wave information including radio wave intensity information related to the intensity of radio waves received by the communication circuit from a plurality of radio wave transmission devices at that position hand , creating reference data related to the relationship between a plurality of positions and the radio wave intensity from each radio wave transmission device death, (2) In the position estimation mode, The communication circuit extracts a predetermined number of reference data where the difference in radio wave intensity between the radio wave intensity received from each radio wave transmitter is small, uses the extracted reference data to determine the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between the position and the radio wave intensity from each radio wave transmitter, and compares the radio wave intensity of the radio waves received from each radio wave transmitter with the radio wave intensity calculated for multiple positions using the predetermined number of parameters, thereby eliminating the need to use the position information of the radio wave transmitters. The system includes a control circuit for estimating the location of the information terminal. [Effects of the Invention]

[0018] According to a first aspect of the present invention, reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitting device is created. Then, a predetermined number of reference data points with small differences in signal strength between the signal strength of the radio waves received from each radio wave transmitter are extracted, and using the extracted reference data, the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between position and the signal strength from each radio wave transmitter are determined. As a result, It can be approximately expressed using those parameters. The location of the information terminal is determined based on the gradient of the radio wave intensity. Estimate It is possible Therefore When measuring the location of an information terminal using radio waves other than GNSS, even if the location information of multiple radio wave transmitters cannot be obtained in advance, it becomes possible to estimate the location of the information terminal receiving radio waves emitted from those transmitters by narrowing it down to a single point rather than an area.

[0019] Also, According to a second aspect of the present invention, an information terminal displays a specified map image on its display unit and generates location information relating to a specified location on the map image. Then, collect radio wave information at that location and create reference data. Therefore, even in fields where radio waves transmitted from GNSS positioning satellites are blocked by buildings, etc. This allows for the estimation of the location of information terminals by focusing on a specific point, rather than estimating it on a region-by-region basis. [Brief explanation of the drawing]

[0020] [Figure 1] This is a block diagram showing an example of the configuration of an overall system including a position measurement system according to the first embodiment of the present invention. [Figure 2] Figure 1 is a block diagram showing an example configuration of an information terminal. [Figure 3] Figure 1 is a block diagram showing an example configuration of a location measurement server. [Figure 4] This is a schematic plan view showing the positional relationship between an information terminal and multiple wireless LAN access points. [Figure 5] This flowchart shows an example of operation in the data acquisition mode of the position measurement method according to the first embodiment of the present invention. [Figure 6] This is a schematic diagram showing an example of the structure of map data and collected data. [Figure 7] This flowchart shows an example of the operation for creating reference data in the position measurement method according to the first embodiment of the present invention. [Figure 8] This is a schematic diagram showing an example of the structure of reference data and estimation data. [Figure 9] This flowchart shows an example of operation in the position estimation mode of the position measurement method according to the first embodiment of the present invention. [Figure 10] This is a schematic diagram showing an example of a map image indicating the estimated location of an information terminal. [Modes for carrying out the invention]

[0021] Embodiments of the present invention will be described in detail below with reference to the drawings. The same reference numerals are used for identical components, and redundant descriptions are omitted.

[0022] <First Embodiment> Figure 1 is a block diagram showing an example configuration of an overall system including a position measurement system according to a first embodiment of the present invention. This overall system includes a plurality of radio wave transmitting devices 101, 102, ... that emit radio waves, at least one information terminal (in Figure 1, a plurality of information terminals 201, 202, ... are shown as an example) that receives the radio waves emitted by the radio wave transmitting devices 101, 102, ..., and a position measurement system 300.

[0023] In this example, the location measurement system 300 consists of a location measurement server 310, a database server 320, and a terminal location monitoring device 330. Alternatively, the location measurement system 300 may consist only of a location measurement server 310 that integrates the functions of multiple devices, or it may consist of a location measurement server 310 and a database server 320, or it may consist of a location measurement server 310 and a terminal location monitoring device 330.

[0024] The information terminals 201, 202, ... and the location measurement server 310 are connected via a wired connection such as a USB cable, or they have the function of communicating data with each other via a mobile communication network or the Internet. In addition, the location measurement server 310, the database server 320, and the terminal location monitoring device 330 have the function of communicating data with each other via a LAN (Local Area Network) or the Internet.

[0025] The position measurement system 300 measures the position of an information terminal 201, etc., that can receive radio waves transmitted from radio wave transmitters 101, 102, ... At least two radio wave transmitters 101 and 102 are required for 2D position measurement, and at least three radio wave transmitters 101 to 103 are required for 3D position measurement.

[0026] In this embodiment, the radio waves or radio wave transmitting device used for position measurement must satisfy the following conditions. (1) The RSSI of radio waves changes depending on the location. (2) The RSSI of the radio waves does not change significantly over time. (3) The position of the radio wave transmitting device shall not change for a certain period of time. (4) Each radio wave transmitting device must be identifiable by radio waves (depending on the circumstances).

[0027] Here, RSSI stands for "Received Signal Strength Indicator," which measures the power or quality of a radio frequency signal at the moment the radio wave reaches a receiver such as an antenna or network equipment, and is generally used as radio wave strength.

[0028] Radio waves that meet the above conditions include radio waves from stationary routers in wireless LAN communication such as Wi-Fi (Wireless Fidelity), radio waves from stationary beacons, and 4G and 5G radio waves from cellular base stations. For example, BLE (Bluetooth Low Energy) beacons are used as beacons.

[0029] Furthermore, multiple types of radio waves may be combined and used for position measurement. For example, when performing 3D position measurement, radio waves from Wi-Fi communication, beacon signals, and cell phone base station signals may be used. In such cases, since multiple radio wave transmitters can be identified by the type of radio wave, it is not necessarily required that the identification signal of the radio wave transmitter be included in the radio wave.

[0030] For example, a portable device such as a smartphone, tablet, or notebook PC (personal computer) can be used as the information terminal 201. Alternatively, the information terminal 201 may be mounted on a mobile device such as an automated guided vehicle, an automated delivery vehicle, a self-driving vehicle, or a robot used in the manufacturing or transportation of goods at a manufacturing company.

[0031] The location measurement server 310 and database server 320, which constitute the location measurement system 300, are installed, for example, in a data center to provide location measurement services. The terminal location monitoring device 330 may consist of a general PC and a display, and is used, for example, in a control center of a security company or a manufacturing company to monitor location measurement results.

[0032] For example, a security guard belonging to a security company carries an information terminal 201 while patrolling a building or other location, and a location measurement server 310 estimates the current location of the information terminal 201. The estimated current location is displayed on the screen of a terminal location monitoring device 330 installed in the security company's control center or other location.

[0033] As another example, the position measurement system 300 may estimate the current location of an information terminal 201 mounted on a mobile vehicle such as an automated guided vehicle or an automated delivery vehicle. In this case, the estimated current location is displayed on the screen of a terminal location monitoring device 330 installed in a control center of a manufacturing company or transportation company.

[0034] <Information Terminal> Figure 2 is a block diagram showing an example configuration of the information terminal shown in Figure 1. As shown in Figure 2, the information terminal 201 includes a wireless LAN communication circuit 21, a beacon communication circuit 22, a mobile communication circuit 23, a GNSS receiving circuit 24, a display unit 25, an operation unit 26, and a control circuit 27.

[0035] Here, the information terminal 201 only needs to include at least one of the wireless LAN communication circuits 21 to mobile communication circuits 23 in order to receive radio waves from multiple radio wave transmitters 101, 102, ..., and in this application, this is also referred to as a "communication circuit". Furthermore, the information terminals 202, 203, ... may be configured in the same way as the information terminal 201.

[0036] The wireless LAN communication circuit 21 includes a transmitting and receiving circuit and modem for transmitting and receiving wireless LAN radio waves, and enables wireless LAN communication with the radio wave transmitter 101, etc., when the radio wave transmitter 101, etc. is a wireless LAN access point. In addition, the wireless LAN communication circuit 21 can communicate data with the location measurement server 310 via the network. For example, Wi-Fi is used as the wireless LAN communication method. A Wi-Fi access point has the function of wirelessly connecting with Wi-Fi-enabled devices as a base station for Wi-Fi radio waves.

[0037] A wireless LAN can be divided into multiple subnetworks that require different authentication methods. In wireless LAN infrastructure mode, a network consisting of one access point and wireless LAN client terminals within its radio wave range is called a BSS (Basic Service Set).

[0038] Wireless LAN signals include a Wireless LAN Access Point ID (BSSID) as identification information to identify individual access points. While BSSIDs can be arbitrarily set and are therefore not completely unique identifiers, they can, individually or in combination, serve to distinguish a wireless LAN or subnetwork from surrounding networks.

[0039] The beacon communication circuit 22 includes a transmitting and receiving circuit and modem for sending and receiving beacon radio waves, and enables beacon communication with the radio wave transmitter 101, etc., when the radio wave transmitter 101, etc. is a beacon device. For example, a BLE beacon device transmits radio waves wirelessly once every few seconds within a radius of several meters to tens of meters, and if there is an information terminal 201 that can receive the beacon signal within that range, it detects it and transmits location information, etc., to the information terminal 201. The beacon signal includes a beacon device ID as identification information that identifies each beacon device.

[0040] The mobile communication circuit 23 includes a transmitting and receiving circuit and modem for transmitting and receiving mobile communication radio waves, and enables mobile communication with the radio wave transmitter 101, etc., when the radio wave transmitter 101, etc. is a mobile phone base station. In addition, the mobile communication circuit 23 can communicate data with the location measurement server 310 via a network.

[0041] The GNSS receiving circuit 24 receives radio waves transmitted from three or more (typically four) positioning satellites of the global positioning system. Since the radio waves transmitted from the positioning satellites contain information about the time of transmission, the radio wave propagation time can be determined, and the distance from the positioning satellite can be calculated. Therefore, the current position of the information terminal 201 can be calculated based on the radio waves received by the GNSS receiving circuit 24.

[0042] While GNSS-based positioning is effective when the information terminal 201 is located outdoors, it is known to have a measurement error of approximately 1 to 5 meters. Furthermore, positioning becomes difficult in fields where radio waves transmitted from positioning satellites are blocked by buildings or other obstacles. Therefore, in positioning performed in cooperation with the positioning system 300, radio waves other than those from GNSS are used.

[0043] The display unit 25 and the operation unit 26 are composed of, for example, a touch panel. The display unit 25 displays an operation screen, a map image, etc. The operation unit 26 is used to operate the information terminal 201 and perform various operations.

[0044] The control circuit 27 includes, for example, a CPU (Central Processing Unit), storage consisting of flash memory or the like, and cache memory consisting of RAM (Random Access Memory) or the like. The CPU performs various calculations and data processing according to various software (including a position measurement client program used for position measurement) stored in the storage.

[0045] When the information terminal 201 performs location measurement operations in cooperation with the location measurement system 300, the control circuit 27 controls the wireless LAN communication circuit 21 to the display unit 25 by coordinating with the location measurement server 310 using an API (Application Programming Interface).

[0046] Here, an API (Application Programming Interface) is a set of rules or specifications that define the procedures and data formats for calling and using the functions and managed data of a particular computer program (software) from other external programs. The information terminal 201 can use APIs to integrate or cooperate with the applications and web services of the location measurement server 310.

[0047] For example, a security guard (also referred to as an "operator" in this application) belonging to a security company carries an information terminal 201 in preparation for guarding a building, measures the radio wave intensity at multiple locations within a desired measurement area of ​​the building, and collects data including location information and radio wave information (data collection mode). Multiple information terminals 201, 202, ... may be used to collect such data, but below, as an example, the case in which one information terminal 201 is used will be described.

[0048] In data acquisition mode, when the operator operates the control unit 26 to specify a map of the desired measurement area, the control circuit 27 displays the image of the specified map on the display unit 25. When the operator taps or clicks their current position on the map image, the control circuit 27 generates position information (for example, 2D position coordinates on the specified map) related to the specified position on the map image.

[0049] Furthermore, the control circuit 27 controls the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 to receive radio waves from multiple radio wave transmitters 101, 102, ... at the above-mentioned location.

[0050] The wireless LAN communication circuit 21, under the control of the control circuit 27, receives wireless LAN radio waves transmitted from wireless LAN access points installed in or around the building being guarded, demodulates the wireless LAN signal to obtain a wireless LAN access point ID (BSSID), and outputs information regarding the strength of the radio waves transmitted from the wireless LAN access point (RSSI) to the control circuit 27.

[0051] The beacon communication circuit 22, under the control of the control circuit 27, receives radio waves from beacon devices installed in or around the building being guarded, demodulates the beacon signal to obtain a beacon device ID, and outputs information regarding the strength of the radio waves transmitted from the beacon device (RSSI) to the control circuit 27.

[0052] The mobile communication circuit 23, under the control of the control circuit 27, receives mobile communication radio waves transmitted from a mobile phone base station installed in or around the building being guarded, demodulates the mobile communication signal to obtain the mobile phone base station ID, and outputs information regarding the strength of the radio waves transmitted from the mobile phone base station (RSSI) to the control circuit 27.

[0053] Furthermore, when using multiple types of radio waves for position measurement, instead of using IDs that identify each individual radio wave transmitting device 101, 102, ..., identification information representing the type of radio wave may be used as identification information to identify the radio wave source.

[0054] The control circuit 27 collects radio wave information, which includes identification information to identify the radio wave source and radio wave strength information regarding the strength of radio waves received by the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 from multiple radio wave transmitters 101, 102, ... The control circuit 27 also supplies location information and radio wave information to the location measurement system 300. For this purpose, a wired connection may be used, or the control circuit 27 may control the wireless LAN communication circuit 21 or the mobile communication circuit 23.

[0055] In this way, as the operator moves within the building being guarded and repeats the above operations at multiple different locations, the control circuit 27 causes the position measurement system 300 to create reference data regarding the relationship between multiple locations and the radio wave intensity from each radio wave transmitter 101, etc.

[0056] Next, when an operator is guarding a building, they carry the information terminal 201 and patrol the desired measurement area of ​​the building. The information terminal 201 receives radio waves from multiple radio wave transmitters 101, 102, ... and supplies the radio wave information to the position measurement system 300, causing the position measurement system 300 to estimate the position of the information terminal 201 (position estimation mode).

[0057] In position estimation mode, the control circuit 27 controls the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 to receive radio waves from multiple radio transmitters 101, 102, ... This receiving operation may be performed periodically based on timing operations, or it may be performed in accordance with commands from an operator or position measurement server 310.

[0058] The control circuit 27 generates radio wave information that includes identification information to identify the radio wave source and radio wave intensity information regarding the strength of the radio waves received by the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 from multiple radio wave transmitters 101, 102, ... The control circuit 27 also supplies this radio wave information to the position measurement system 300. As a result, the control circuit 27 causes the position measurement system 300 to estimate the position of the information terminal 201 based on reference data and the radio wave information from the multiple radio wave transmitters 101, 102, ...

[0059] When a smartphone is used as the information terminal 201, a smartphone attachment device for self-positioning may be attached to the smartphone in order to enable the smartphone to operate normally without the operator having to use their hands. This smartphone attachment device includes a belt portion that is worn around the waist of the human body and a storage portion fixed to the belt portion.

[0060] <Location measurement server> Figure 3 is a block diagram showing an example configuration of the location measurement server shown in Figure 1. In this example, the location measurement server 310 has the necessary database and also functions as the database server 320.

[0061] As shown in Figure 3, the position measurement server 310 includes an operation unit 31, a display unit 32, an audio input / output unit 33, a communication circuit 34, a timer unit 35, an interface 36, a CPU 37, a storage unit 38, and a cache memory 39. The interface 36 to the cache memory 39 are connected to each other via a bus line. Note that some of the components shown in Figures 1 to 3 may be omitted or modified, or other components may be added to the components shown in Figures 1 to 3.

[0062] The operation unit 31 consists of, for example, a keyboard and mouse, and is used to input various commands and data to the position measurement server 310. The display unit 32 includes, for example, an LCD (liquid crystal display), and displays the operation screen, map images, etc. The audio input / output unit 33 includes, for example, a microphone, amplifier, and speaker, and converts audio signals into electrical signals and electrical signals into audio signals.

[0063] The communication circuit 34 has the function of performing data communication with information terminals 201, 202, ..., database server 320, and terminal location monitoring device 330 using a wired connection, or via a network such as a wired LAN, wireless LAN, mobile communication network, or the Internet.

[0064] The timer unit 35 performs timing operations or acquires timing data from an external source, causing the CPU 37 to execute predetermined processes at predetermined dates and times or at predetermined time intervals. The interface 36 is connected to the operation unit 31 and the timer unit 35, and transmits various commands and data between them and the CPU 37.

[0065] The CPU 37 performs various calculations and data processing according to the various software (including the location measurement server program used for location measurement) stored in the storage unit 38. When the location measurement server 310 performs location measurement operations in cooperation with the information terminal 201, the CPU 37 controls various parts of the location measurement server 310 by coordinating with the information terminal 201 using an API.

[0066] The storage unit 38 can use a hard disk, flexible disk, magneto-optical disk, CD-ROM, DVD-ROM, SSD (solid-state drive), or ROM (read-only memory) as its recording medium (storage medium). The cache memory 39 is composed of RAM or the like. In addition to the above software, the storage unit 38 stores various data used for position measurement, and this data is read out and written to the cache memory 39 as needed.

[0067] Here, the CPU 37 and the position measurement server program stored in the storage unit 38 constitute a functional block comprising the communication control unit 370, the map selection unit 371, the reference data creation unit 372, and the position estimation unit 373.

[0068] The communication control unit 370 controls the communication operation of the communication circuit 34. The map selection unit 371 selects the map data for the specified measurement target area from the map database DB1 of the storage unit 38, which stores map data for multiple measurement target areas.

[0069] The map data used in the information terminal 201 may be stored in the information terminal 201 in advance prior to the location measurement operation, or it may be transmitted to the information terminal 201 by the communication circuit 34 of the location measurement server 310 in response to a request from the information terminal 201 during the location measurement operation. Alternatively, it is possible to select the map data for the desired measurement target area by operating the operation unit 31 of the location measurement server 310.

[0070] Under the control of the communication control unit 370, the communication circuit 34 performs data communication with the information terminal 201 to receive location information regarding the location of the information terminal 201, and to receive radio wave information including radio wave intensity information (RSSI) regarding the strength of radio waves received by the information terminal 201 from multiple radio wave transmitters 101, 102, ...

[0071] In data acquisition mode, the reference data creation unit 372 stores the acquired data, including location information and radio wave information obtained at multiple locations, in the comparison database DB2 of the storage unit 38. Furthermore, based on the acquired data, the reference data creation unit 372 creates reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitter 101, etc., and stores it in the comparison database DB2 of the storage unit 38. Alternatively, instead of saving the acquired data, the reference data creation unit 372 may immediately create the reference data and store it in the comparison database DB2 as soon as location information and radio wave information are received by the communication circuit 34.

[0072] For example, the reference data creation unit 372 may create reference data with a larger number of effective samples than the collected data by interpolating or extrapolating the sample points included in the collected data, or it may create reference data that includes parameters for identifying an approximation formula created based on the collected data.

[0073] Furthermore, the reference data creation unit 372 may create reference data by obtaining three-dimensional location information from the two-dimensional location information contained in the collected data. On the other hand, if there is no need to improve positioning accuracy, or if the two-dimensional location of the information terminal 201 is to be determined, at least a portion of the collected data may be used as reference data.

[0074] In position estimation mode, the position estimation unit 373 estimates the position of the information terminal 201 based on reference data created by the reference data creation unit 372 and stored in the comparison database DB2, and radio wave information from multiple radio wave transmitters 101, 102, ... received from the information terminal 201 by the communication circuit 34. Estimation data, including radio wave information for position estimation, is stored in the estimation database DB3.

[0075] Furthermore, the position estimation unit 373 displays two-dimensional or three-dimensional position coordinates representing the estimated position of the information terminal 201 on the display unit 32, or displays the position of the information terminal 201 on a two-dimensional or three-dimensional map image on the display unit 32. Alternatively, this information may be transmitted from the communication circuit 34 to the terminal position monitoring device 330 or the information terminal 201 and displayed on the display of the terminal position monitoring device 330 or the display unit 25 of the information terminal 201.

[0076] <Example of information processing system operation> Next, an example of the operation of the information processing system according to the first embodiment of the present invention will be described with reference to Figures 1 to 10. In the following, as an example, a case will be described in which three wireless LAN access points are used as multiple radio wave transmitting devices 101, 102, ... to measure the three-dimensional position of an information terminal 201 on the fourth floor of building A.

[0077] Figure 4 is a schematic plan view showing the positional relationship between the information terminal and multiple wireless LAN access points. In Figure 4, the spread of wireless LAN radio waves emitted from wireless LAN access points 101-103 installed in or around Building A is shown by dashed lines on the 4th floor of Building A where the information terminal 201 is located.

[0078] <Data acquisition mode> In data acquisition mode, the operator, carrying an information terminal 201, measures radio wave strength at multiple locations on each floor of Building A in preparation for guarding Building A, and collects data including location information and radio wave information.

[0079] Figure 5 is a flowchart showing an example of operation in the data acquisition mode of the position measurement method according to the first embodiment of the present invention. In step S11 of Figure 5, when the operator operates the control unit 26 of the information terminal 201 to specify a map of one floor of building A (for example, the 4th floor), the map image of the 4th floor of building A is displayed on the display unit 25.

[0080] In step S12, when the operator specifies their current location on the map image, the information terminal 201 generates location information related to the specified location on the map image. For example, the operator taps their current location on the map image displayed on the display unit 25, or aligns the pointer to their current location on the map image and clicks the mouse.

[0081] In step S13, at that location, the wireless LAN communication circuit 21 of the information terminal 201 receives wireless LAN radio waves transmitted from wireless LAN access points 101 to 103 installed in or around building A, and the control circuit 27 acquires radio wave information including the wireless LAN access point ID (BSSID) obtained by demodulating the wireless LAN signal and information regarding the strength of the radio waves transmitted from the wireless LAN access point (RSSI).

[0082] In step S14, the information terminal 201 transmits location information and radio wave information to the location measurement server 310, and the reference data creation unit 372 in the location measurement server 310 stores the location information and radio wave information in the comparison database DB2 of the storage unit 38. The information terminal 201 may also transmit a map ID to the location measurement server 310 that identifies the map used for location measurement.

[0083] In step S15, the operator or the reference data creation unit 372 determines whether the amount of data (number of samples) on the 4th floor is sufficient. To determine the 3D position of the information terminal 201, it is desirable to collect data at at least four locations.

[0084] If it is determined that the amount of data is insufficient, the process moves to step S16, the operator moves to a location on the 4th floor with less data, and steps S12 to S15 are repeated. On the other hand, if it is determined that the amount of data is sufficient, the process moves to step S17.

[0085] In step S17, the operator or the reference data creation unit 372 determines whether data collection in building A has been completed. If it is determined that data collection in building A has not been completed, the process moves to step S18, the operator moves to another floor of building A, and steps S11 to S17 are repeated.

[0086] On the other hand, if it is determined that data collection in building A is complete, the data collection mode processing ends. In this way, the operator carries the information terminal 201 and moves around building A, repeatedly collecting data at multiple different locations. The reference data creation unit 372 of the position measurement server 310 collects the location information and radio wave information obtained at multiple locations and stores it as collected data in the comparison database DB2 of the storage unit 38.

[0087] Figure 6 is a schematic diagram showing an example of the structure of map data and collected data. For example, the map data includes a map ID that identifies the plan view of each measurement target area (also referred to as a "local map" in this application), the position of the origin of the local map on a map that includes the entire building containing multiple measurement target areas or an even wider area (also referred to as a "global map" in this application), the width and length of the local map, and the direction of the local map.

[0088] In the example shown in Figure 6, the map ID "ABC0001" represents an identifier used to identify a floor plan of a building. The map origin "(X1, Y1, Z1)" represents the coordinates of the origin of the local map on a 3D global map. The map width and length "(W1, L1)" represent the width and length of the local map. The map direction "D1" represents the angle of deviation, etc., when the top direction on the local map is different from the north direction on the global map. These can be used to convert between the coordinates of the local map and the coordinates of the global map.

[0089] On the other hand, the collected data includes the map ID of the local map used to collect the data, the location coordinates of the information terminal 201 on that local map as location information, and the wireless LAN access point ID and radio wave strength information obtained at that location as radio wave information.

[0090] In the example shown in Figure 6, the location information "(x1, y1)" represents the two-dimensional coordinates of the information terminal 201 on the local map. The access point ID "BSSID1" indicates that the radio waves are from wireless LAN access point 101. The radio wave strength information "RSSI1" represents the strength of the radio waves as a logarithmic representation of the power of the radio frequency signal [mdB (decibels / milliwatts)].

[0091] <Example of operation for creating reference data> In creating reference data, the reference data creation unit 372 of the position measurement server 310 creates reference data used to estimate the position of the information terminal 201 based on the collected data. Figure 7 is a flowchart showing an example of the operation for creating reference data in the position measurement method according to the first embodiment of the present invention.

[0092] In step S21 of Figure 7, the reference data creation unit 372 retrieves all collected data related to building A from the comparison database DB2 and writes it to the cache memory 39. Next, in step S22, the reference data creation unit 372 reads the collected data for each wireless LAN access point ID (BSSID) in order to perform data processing for each wireless LAN access point.

[0093] In step S23, the reference data creation unit 372 determines whether or not there are many missing values ​​for signal strength (RSSI) in the collected data. Missing RSSI values ​​may occur if there are obstacles between the wireless LAN access points 101-103 and the information terminal 201, or if the timing of receiving radio waves from the wireless LAN access points 101-103 is poor.

[0094] For example, if the number of valid samples in the collected data is less than a predetermined number, it is determined that there are many missing values ​​in the RSSI, and the process proceeds to S24. On the other hand, if the number of valid samples in the collected data is greater than or equal to the predetermined number, it is determined that there are few missing values ​​in the RSSI, and the process proceeds to S26.

[0095] In steps S24 to S25, the reference data creation unit 372 creates reference data relating to the relationship between multiple locations and the RSSI from each wireless LAN access point 101, etc., based on collected data including location information and radio wave information obtained at multiple locations.

[0096] For example, in step S24, the reference data creation unit 372 creates an approximate formula representing the relationship between multiple locations and the RSSI from each wireless LAN access point 101, etc., based on the collected data which includes location information and radio wave information obtained at multiple locations. Next, in step S25, the reference data creation unit 372 applies the location information of the collected data to the approximate formula and fills in any missing values ​​of the RSSI in the collected data with calculated RSSI values.

[0097] In step S26, the reference data creation unit 372 creates reference data relating to the relationship between multiple locations and the RSSI from each wireless LAN access point 101, etc., based on the supplemented RSSI values, and stores it in the comparison database DB2 of the storage unit 38.

[0098] In step S27, the reference data creation unit 372 determines whether data processing for all BSSIDs has been completed. If data processing for all BSSIDs has not been completed, the process moves to step S22, and the reference data creation unit 372 reads the collected data for the next BSSID. On the other hand, if data processing for all BSSIDs has been completed, the process ends.

[0099] <Example of creating an approximation formula> The reference data creation unit 372 creates an approximate formula for each of the wireless LAN access points 101 to 103 that represents the relationship between multiple locations and RSSI. First, the reference data creation unit 372 extracts multiple data points (sample points) from the collected data. In order to determine the three-dimensional position of the information terminal 201, it is desirable to extract at least three data points from each wireless LAN access point, starting with the ones with the largest RSSI values.

[0100] Next, the reference data creation unit 372 takes a weighted average of the positions represented by the position information of multiple data points, using exp(r), which is proportional to the power [mW] of the radio frequency signal, as a weight when the RSSI value is r [mdB], and assumes that the position represented by this weighted average is the position Pa (vector) of the wireless LAN access point. Alternatively, if the position of the wireless LAN access point is known in advance, that can be used as the position Pa.

[0101] Furthermore, the reference data creation unit 372 calculates parameters a and b that minimize the mean squared error between the following terms (1) and (2), assuming that the positions of multiple data points are represented by Pi (vector) (i=1, 2, ...) and the RSSI values ​​at those positions are Ri[mdB]. a + b × Ri ... (1) log(|Pi-Pa|) ···(2) Here, the absolute value symbol represents the length (distance) of the vector. Since the power density of radio waves attenuates in proportion to the square of the distance |Pi-Pa|, the relationship between the two can be expressed as a linear function by taking the logarithm of both.

[0102] After determining parameters a and b, the reference data creation unit 372 sets the following equation (3) as an approximate formula for the RSSI value R [mdB] at position P (vector) for the radio waves emitted from each wireless LAN access point. R={-a+log(|P-Pa|)} / bc ···(3) Here, parameter c is an adjustment term to bring the approximation formula (3) closer to the measured value, and may be set so that the approximation value is close to the measured value, for example, c = 10.

[0103] By substituting the location information of the missing RSSI data into approximation formula (3) to calculate the RSSI value R, the missing RSSI values ​​are filled with the calculated RSSI values. Furthermore, the RSSI value R at a new sample point may also be calculated. In addition, if the calculated RSSI value R is less than -100, it may be replaced with -100, or the calculated RSSI value R may be set to the maximum RSSI value R of the wireless LAN access point. MAX If it exceeds R MAX You can also modify the calculated RSSI value R by replacing it with something else.

[0104] Since there are many data points where the RSSI value R is -100 or less, data points with an RSSI value R of -100 or less may be excluded from the reference data stored in the comparison database DB2 as they are not valid samples. Alternatively, reference data including parameters to identify the approximation formula (3) may be stored in the comparison database DB2 instead of, or in addition to, the RSSI. For example, for each wireless LAN access point, the wireless LAN access point ID (BSSID), parameters a and b, the provisional location Pa of the wireless LAN access point, and the maximum RSSI value R may be stored. MAX It will be saved.

[0105] <Position estimation mode> In location estimation mode, when an operator is guarding building A, they carry an information terminal 201 and patrol multiple floors of building A. The information terminal 201 receives wireless LAN radio waves transmitted from wireless LAN access points 101 to 103 and transmits radio wave information, including radio wave strength information, to the location measurement server 310.

[0106] The location measurement server 310 stores estimation data, including the terminal ID and radio wave information of the acquired information terminal 201, in the estimation database DB3 of the storage unit 38, and estimates the location of the information terminal 201 based on the reference data and estimation data in order to manage security operations.

[0107] Figure 8 is a schematic diagram showing an example of the structure of reference data and estimation data. For example, the reference data includes location information such as location coordinates (X,Y,Z) on a 3D global map, and radio wave information such as the wireless LAN access point ID (BSSID) and radio wave strength information (RSSI) obtained at that location. The coordinate value (height) in the Z-axis direction in the 3D coordinate system may be a predetermined value based on the floor height identified by the map ID. Alternatively, location information such as location coordinates (x,y) on a 2D local map may be used.

[0108] on the other hand, recommendation The standard data includes a terminal ID such as "device01" to identify the information terminal, and radio wave information such as the wireless LAN access point ID (BSSID) and signal strength information (RSSI) obtained at that information terminal. Figure 9 is a flowchart showing an example of operation in the position estimation mode of the position measurement method according to the first embodiment of the present invention.

[0109] In step S31 of Figure 9, the information terminal 201 receives wireless LAN radio waves transmitted from wireless LAN access points 101 to 103, demodulates the wireless LAN signal to obtain the wireless LAN access point ID (BSSID), and acquires radio wave information including information on the strength of the radio waves transmitted from the wireless LAN access points (RSSI).

[0110] In step S32, the information terminal 201 transmits estimation data including the terminal ID and radio wave information to the location measurement server 310, and the location estimation unit 373 of the location measurement server 310 stores the estimation data in the estimation database DB3 of the storage unit 38.

[0111] In step S33, the position estimation unit 373 reads multiple data points with similar RSSI distributions from the comparison database DB2, where reference data is stored, for each of the wireless LAN access points 101 to 103.

[0112] In steps S34 to S35, the position estimation unit 373 estimates the position of the information terminal 201 based on the reference data created by the reference data creation unit 372 and the radio wave information of multiple wireless LAN access points 101 to 103 acquired from the information terminal 201.

[0113] For example, in step S34, the position estimation unit 373 creates an approximate formula that represents the relationship between multiple locations and the RSSI from each wireless LAN access point 101, etc., based on multiple data read from the comparison database DB2 where reference data is stored.

[0114] In step S35, the position estimation unit 373 calculates the position for each of the multiple wireless LAN access points 101 to 103 where the mean squared error between the RSSI included in the radio wave information acquired from the information terminal 201 and the RSSI calculated from the approximation formula is minimized. This determines the estimated position of the information terminal 201. Next, in step S36, the position estimation unit 373 stores the estimation result in the estimation result database DB4 of the storage unit 38.

[0115] <Example of creating an approximation formula> First, the position estimation unit 373 calculates the difference between the RSSI of the reference data and the acquired RSSI for each wireless LAN access point 101 to 103, calculates their mean absolute errors, and extracts multiple data points from those with the smallest mean absolute error values. To determine the 3D position of the information terminal 201, it is desirable to extract at least four data points from those with the smallest mean absolute error values.

[0116] Here, the mean absolute error means a value obtained by averaging the absolute values of the difference between an actual measured value and a predicted value based on a model. Note that when the number of pieces of reference data is insufficient, for example, when the number of pieces of data is less than 3 for obtaining a three-dimensional position, or when the number of pieces of data is less than 2 for obtaining a two-dimensional position, an error display may be performed.

[0117] The three-dimensional position coordinate of position p in the reference data is defined as (X p , Y p , Z p ), for the q-th wireless LAN access point (q=1, 2, ···), the RSSI value of the reference data at position p is denoted as level p、q [mdB], and the position estimation unit 373 calculates the parameter a that minimizes the mean square error between the following expressions (4) and (5) q , b q , c q , d q . a q ×X p +b q ×Y p +c q ×Z p +d q ···(4) level p、q ···(5) This approximate expression may be a first-order approximation, or an approximation of second order or higher. Since it can be expected that the positions of the reference data fall within a narrow range by using data with close RSSI distributions, the first-order approximation can be effectively used.

[0118] Next, after obtaining the parameters a q , b q , c q , d q , the position estimation unit 373 sets the RSSI value acquired for the q-th wireless LAN access point as level q [mdB] (q=1, 2, ···), and calculates a position (X, Y, Z) that minimizes the mean square error between the following expressions (6) and (7) for the plurality of wireless LAN access points 101 to 103, and sets this position as the estimated position. aq ×X+b q ×Y+c q ×Z ···(6) level q -d q ...(7) Since term (4) above is a linear approximation, the least squares method can be performed algebraically, and data processing is executed at high speed.

[0119] The position estimation unit 373 displays the coordinates of the estimated position of the information terminal 201 on the display unit 32 as a result of the position estimation, or transmits the information to the terminal position monitoring device 330 or the information terminal 201 via the communication circuit 34 for display. Furthermore, the position measurement server 310, the terminal position monitoring device 330, or the information terminal 201 may generate image data that displays the estimated position of the information terminal 201 on a two-dimensional or three-dimensional map, and display the map image on the display unit.

[0120] Figure 10 is a schematic diagram showing an example of a map image indicating the estimated location of an information terminal. In Figure 10, the estimated location of information terminal 201 is indicated by a predetermined mark in both a perspective view of the entire building A (global map) and a floor plan of the 4th floor of building A (local map). The coordinates (X,Y,Z) of the estimated location of information terminal 201 on the global map and the coordinates (x,y) on the local map are also shown.

[0121] <Effects of the First Embodiment> According to the first embodiment, by creating reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitter 101, the location of the information terminal 201 can be determined based on the gradient of the radio wave intensity. Therefore, when measuring the location of the information terminal 201 using radio waves other than GNSS, even if the location information of multiple radio wave transmitters 101, 102, ... cannot be obtained in advance, it becomes possible to estimate the location of the information terminal 201 that receives radio waves emitted from those radio wave transmitters 101, 102, ... by narrowing it down to a single point rather than on a regional basis.

[0122] Furthermore, the information terminal 201 displays a specified map image on the display unit 25 and generates location information for a specified location on the map image, so it can be used even in fields where radio waves transmitted from GNSS positioning satellites are blocked by buildings, etc.

[0123] Furthermore, the reference data creation unit 372 of the position measurement server 310 creates an approximate formula representing the relationship between multiple locations and the radio wave intensity from each radio wave transmitter 101, etc., based on the collected data including location information and radio wave information obtained at multiple locations. This creates reference data with a larger number of effective samples than the collected data, or creates reference data that includes parameters for specifying the approximate formula. As a result, positioning accuracy can be improved even when the radio wave intensity from the radio wave transmitter 101, etc. is weak.

[0124] <Second Embodiment> In the second embodiment, the control circuit 27 of the information terminal 201 shown in Figure 2 has the functions of the reference data creation unit 372 and the position estimation unit 373 of the position measurement server 310 shown in Figure 3.

[0125] Specifically, in data acquisition mode, the control circuit 27 displays a specified map image on the display unit 25, generates location information for a specified location on the map image, and collects radio wave information including radio wave intensity information for radio waves received at that location by the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 from multiple radio wave transmitters 101, 102, ...

[0126] Furthermore, the control circuit 27 creates and stores reference data regarding the relationship between multiple locations and the signal strength from each radio wave transmitter. For example, it stores calculation formulas necessary to estimate the location of the information terminal 201 based on the signal strength information (RSSI) of radio waves received from multiple radio wave transmitters 101, 102, ...

[0127] Furthermore, in position estimation mode, the control circuit 27 estimates the position of the information terminal 201 based on reference data and radio wave information from radio waves received by the wireless LAN communication circuit 21, beacon communication circuit 22, or mobile communication circuit 23 from multiple radio wave transmitters 101, 102, ...

[0128] According to the second embodiment, the information terminal 201 can estimate its own location independently without data communication between the information terminal 201 and the location measurement server 310. In other respects, the second embodiment may be the same as the first embodiment.

[0129] The present invention is not limited to the embodiments described above, and many modifications can be made within the technical concept of the invention by those who have ordinary skill in the art. For example, it is possible to carry out the invention by omitting some of the operations from the embodiments described above. [Industrial applicability]

[0130] The present invention can be used in a location measurement system, etc., which receives radio waves transmitted from a radio wave transmitting device and measures the location of a transportable or movable information terminal. [Explanation of Symbols]

[0131] 101, 102, 103... Radio wave transmitters, 201, 202, 203... Information terminals, 21... Wireless LAN communication circuit, 22... Beacon communication circuit, 23... Mobile communication circuit, 24... GNSS receiving circuit, 25... Display unit, 26... Operation unit, 27... Control circuit, 300... Position measurement system, 310... Position measurement server, 31... Operation unit, 32... Display unit, 33... Audio input / output unit, 34... Communication circuit, 35... Timer unit, 36... Interface, 37... CPU, 370... Communication control unit, 371... Map selection unit, 372... Reference data creation unit, 373... Position estimation unit, 38... Storage unit, 39... Cache memory, 320... Database server, 330... Terminal position monitoring device

Claims

1. A location measurement system for measuring the location of an information terminal capable of receiving radio waves transmitted from a radio wave transmitting device, A communication circuit that, by performing data communication with an information terminal, receives location information relating to the location of the information terminal, and also receives radio wave information including radio wave strength information relating to the strength of radio waves received by the information terminal from multiple radio wave transmitting devices, A reference data creation unit creates reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitting device, based on the location information and radio wave information collected in advance at multiple locations. A position estimation unit that estimates the position of the information terminal without using the position information of the radio wave transmitters by extracting a predetermined number of reference data in which the difference in radio wave intensity between the radio wave information received from the information terminal by the communication circuit and the radio wave intensity from each radio wave transmitter is small, using the extracted reference data to determine the values ​​of a predetermined number of parameters included in an approximation formula that represents the relationship between the position and the radio wave intensity from each radio wave transmitter, and comparing the radio wave intensity from each radio wave transmitter in the radio wave information with the radio wave intensity calculated for multiple positions using the predetermined number of parameters, A position measurement system equipped with the following features.

2. The position measurement system according to claim 1, wherein the reference data creation unit creates a reference data supplementation formula that represents the relationship between the position and the radio wave intensity from each radio wave transmitting device for a plurality of sample points extracted from the collected data, based on the collected data which includes the position information and radio wave information collected at a plurality of locations, thereby creating reference data with a larger number of effective samples than the collected data, or creating reference data which includes parameters for specifying the collected data supplementation formula.

3. The position measurement system according to claim 2, wherein the reference data creation unit creates an approximate formula for supplementing collected data that represents the relationship between the distance between the information terminal and each radio wave transmitter and the radio wave intensity from each radio wave transmitter, based on the collected data including the position information and radio wave information collected at a plurality of locations, assuming the position of each radio wave transmitter.

4. The aforementioned reference data creation unit creates reference data based on location information relating to the two-dimensional position of the information terminal, radio wave information received by the information terminal from multiple radio wave transmitting devices, and an identifier that identifies the floor plan of the building where the location information and the radio wave information were collected. The position measurement system according to any one of claims 1 to 3, wherein the position estimation unit estimates the three-dimensional position of the information terminal, including position information in the height direction predetermined based on the floor height specified by the identifier, or the two-dimensional position of the information terminal on a plan view specified by the identifier, based on the reference data created by the reference data creation unit and radio wave information from a plurality of radio wave transmitters received from the information terminal by the communication circuit.

5. The position measurement system according to any one of claims 1 to 3, wherein the reference data creation unit or the position estimation unit identifies the plurality of radio wave transmitters using a wireless LAN access point ID, beacon device ID, or mobile phone base station ID included in the radio wave information of the plurality of radio wave transmitters received by the communication circuit.

6. It is an information terminal, A communication circuit that receives radio waves transmitted from a radio wave transmitting device, (1) In data acquisition mode, the control circuit displays a specified map image on the display unit, generates location information for a specified location on the map image, collects radio wave information including radio wave strength information for the strength of radio waves received by the communication circuit from multiple radio wave transmitters at that location, and creates reference data for the relationship between multiple locations and the radio wave strength from each radio wave transmitter; (2) In location estimation mode, the control circuit extracts a predetermined number of reference data for which the difference in radio wave strength between the radio wave strength of the radio waves received by the communication circuit from each radio wave transmitter is small, uses the extracted reference data to determine the values ​​of a predetermined number of parameters included in an approximation formula representing the relationship between a location and the radio wave strength from each radio wave transmitter, and estimates the location of the information terminal without using the location information of the radio wave transmitters by comparing the radio wave strength of the radio waves received from each radio wave transmitter with the radio wave strength calculated for multiple locations using the predetermined number of parameters; An information terminal equipped with the following features.

7. A location measurement system that performs data communication with an information terminal capable of receiving radio waves transmitted from a radio wave transmitter, wherein a location measurement program is used to measure the location of the information terminal, A procedure (a) for receiving location information relating to the location of an information terminal, and for receiving radio wave information including radio wave strength information relating to the strength of radio waves received by the information terminal from multiple radio wave transmitting devices, A procedure (b) for creating reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitting device, based on the location information and radio wave information collected at multiple locations, (c) A procedure for estimating the location of the information terminal without using the location information of the radio wave transmitters by extracting a predetermined number of reference data in which the difference in radio wave intensity between the radio wave information received from the information terminal and the radio wave intensity from each radio wave transmitter is small, using the extracted reference data to determine the values ​​of a predetermined number of parameters included in an approximation formula that represents the relationship between the location and the radio wave intensity from each radio wave transmitter, and comparing the radio wave intensity from each radio wave transmitter in the radio wave information with the radio wave intensity calculated for multiple locations using the predetermined number of parameters, A position measurement program that the CPU executes.

8. A location measurement system that performs data communication with an information terminal capable of receiving radio waves transmitted from a radio wave transmitting device, wherein the location of the information terminal is measured, (a) A step of receiving location information relating to the location of an information terminal and receiving radio wave information including radio wave strength information relating to the strength of radio waves received by the information terminal from multiple radio wave transmitting devices, (b) A step of creating reference data relating to the relationship between multiple locations and the radio wave intensity from each radio wave transmitting device based on the location information and radio wave information collected at multiple locations, Step (c) extracts a predetermined number of reference data in which the difference in radio wave intensity between the radio wave intensity from each radio wave transmitting device in the radio wave information received from the information terminal is small, uses the extracted reference data to determine the values ​​of a predetermined number of parameters included in an approximation formula that represents the relationship between the position and the radio wave intensity from each radio wave transmitting device, and compares the radio wave intensity from each radio wave transmitting device in the radio wave information with the radio wave intensity calculated for multiple positions using the predetermined number of parameters, thereby estimating the position of the information terminal without using the position information of the radio wave transmitting device. A position measurement method comprising the following features.

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