Position estimation device, position estimation system, position estimation method, and program

Abstract

An intensity information acquisition unit (312) acquires intensity information indicating the reception intensity of a wireless signal in a wireless terminal (20), the wireless signal being periodically transmitted from a transmitter. An intensity identification unit (313) identifies a threshold intensity that is a reception intensity at which the cumulative relative frequency of the reception intensity indicated by the intensity information acquired by the intensity information acquisition unit (312) becomes a predetermined threshold. A position estimation unit (314) estimates the position of the wireless terminal (20) on the basis of the threshold intensity identified by the intensity identification unit (313) and the position of the transmitter.

Description

Technical Field

[0001] The present disclosure relates to a position estimation device, a position estimation system, a position estimation method, and a program.

Background Art

[0002] Techniques for estimating the position of a wireless terminal are known. For example, triangulation is a main method for estimating the position of a wireless terminal. Further, Patent Document 1 discloses a system for estimating the current position of an operation terminal using the radio wave intensity of two or more beacon signals transmitted from two or more air conditioners and the previous position, which was the last estimated position where the operation terminal existed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique for estimating the position of a wireless terminal as described above, for example, interference of a wireless signal may occur due to multipath by reflected waves, wireless signals from other devices, or the like. When such interference occurs, there is a problem that the reception intensity of the wireless signal in the wireless terminal is not stable and the accuracy of position estimation decreases.

[0005] The present disclosure has been made to solve the above problems, and an object thereof is to provide a position estimation device or the like capable of estimating the position of a wireless terminal with high accuracy.

Means for Solving the Problems

[0006] To achieve the above object, the position estimation device according to the present disclosure is A location estimation device for estimating the location of a wireless terminal, The reception strength of the wireless signal periodically transmitted from the transmitter at the wireless terminal. degree An intensity identification means for identifying a threshold intensity, which is a received intensity where the cumulative relative frequency reaches a predetermined threshold, The system includes a position estimation means for estimating the position of the wireless terminal based on the threshold intensity determined by the intensity determination means and the position of the transmitter. [Effects of the Invention]

[0007] The position estimation device according to this disclosure identifies a threshold intensity, which is the cumulative relative frequency of the received intensity of a radio signal periodically transmitted from a transmitter at a radio terminal, to a predetermined threshold. Based on the identified threshold intensity and the position of the transmitter, the device estimates the position of the radio terminal. Therefore, according to this disclosure, the position of the radio terminal can be estimated with high accuracy. [Brief explanation of the drawing]

[0008] [Figure 1] Diagram showing the overall configuration of the position estimation system according to Embodiment 1. [Figure 2] A diagram showing an example of a building in which a transmitter according to Embodiment 1 is installed. [Figure 3] Block diagram showing the hardware configuration of the wireless terminal according to Embodiment 1 [Figure 4] Block diagram showing the hardware configuration of the management device according to Embodiment 1 [Figure 5] Block diagram showing the functional configuration of the position estimation system according to Embodiment 1 [Figure 6] A diagram showing an example of transmitter information according to Embodiment 1. [Figure 7] A diagram showing an example of intensity information according to Embodiment 1. [Figure 8] This figure shows an example of sorting the received intensity included in the intensity information according to Embodiment 1 in ascending order for each transmitter. [Figure 9] Figure showing two examples of the frequency distribution of received signal strength and cumulative relative frequency according to Embodiment 1. [Figure 10] Figure showing the relationship between reception intensity and distance according to Embodiment 1 [Figure 11] Figure showing an example of the display of the position estimated by the position estimation system according to Embodiment 1 [Figure 12] Flowchart showing the flow of the intensity information transmission process executed by the wireless terminal according to Embodiment 1 [Figure 13] Flowchart showing the flow of the position estimation process executed by the management device according to Embodiment 1 [Figure 14] Block diagram showing the functional configuration of the position estimation system according to Embodiment 2 [Figure 15] Figure showing an example in which the room to be estimated in Embodiment 2 is divided into a plurality of areas [Figure 16] Figure showing an example of a neural network in Embodiment 2

Embodiments for Carrying Out the Invention

[0009] Hereinafter, embodiments will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

[0010] (Embodiment 1) FIG. 1 shows the overall configuration of a position estimation system 1 according to Embodiment 1. The position estimation system 1 is a system that estimates the position of the wireless terminal 20 and the position of the user who possesses or operates the wireless terminal 20. The position estimation system 1 includes a plurality of transmitters 10, a wireless terminal 20, and a management device 30. The plurality of transmitters 10 and the wireless terminal 20 are installed in a building 5 which is an example of a position estimation area.

[0011] Each of the plurality of transmitters 10 is a device that transmits a wireless signal. The wireless signal is a signal for transmitting information between remote devices. As an example, the wireless signal is a radio wave signal of Bluetooth (registered trademark), and is a beacon signal conforming to the BLE (Bluetooth Low Energy (registered trademark)) standard.

[0012] As shown in FIG. 2, each transmitter 10 is installed in a building 5. The building 5 is a building such as a detached house, an apartment building, an office building, a commercial facility, a factory, etc. The building 5 has a plurality of floors including a first-floor part and a second-floor part. Also, the building 5 has a plurality of rooms on each floor. Each transmitter 10 is installed at an appropriate location such as a wall, a ceiling, a floor, etc. in any one of the plurality of rooms in the building 5.

[0013] In FIG. 2, for ease of understanding, an example is shown where one or two transmitters 10 are installed in each of the plurality of rooms in the building 5. However, there may be rooms in the building 5 where no transmitter 10 is installed, or three or more transmitters 10 may be installed in one room. Also, the building 5 may have floors above the third floor. Hereinafter, a case where there are a plurality of rooms on each floor in the building 5 and three or more transmitters 10 are installed in each room will be taken as an example for explanation.

[0014] Each transmitter 10 may be any device as long as it is a device that transmits a wireless signal. For example, each transmitter 10 may be a device that only has a function of transmitting a radio wave signal of Bluetooth (registered trademark). Alternatively, devices such as air conditioners, lighting, and environmental sensors installed in the building 5 have a function of transmitting a wireless signal, and these devices may function as the transmitter 10.

[0015] Note that each transmitter 10 may be installed as long as it is not completely fixed. However, since the position of each transmitter 10 is used to estimate the position of the wireless terminal 20, it is desirable that it is not moved as much as possible.

[0016] Each transmitter 10 periodically transmits a radio signal of a predetermined intensity. Here, "periodic" means repeatedly executing a predetermined process, and the interval between executions is not limited to a constant interval. The interval may be arbitrarily determined by the administrator of the management device 30, or it may be determined at the time of shipment of the transmitters 10. The interval may be set according to a predetermined rule, or it may be set to an irregular value. For example, each transmitter 10 repeatedly transmits a radio signal at a frequency of once per second. The intensity of the radio signal transmitted from each transmitter 10 is predetermined to be equal among the multiple transmitters 10 installed in the building 5.

[0017] Each radio signal transmitted from the transmitter 10 includes a transmitter ID, which is identification information of the source of the signal. The transmitter ID is, for example, a beacon ID, and is uniquely set for each transmitter 10 that is the source of the radio signal.

[0018] Returning to Figure 1, the wireless terminal 20 is a terminal device such as a smartphone, PC (Personal Computer), or tablet. As shown in Figure 2, the wireless terminal 20 is held and operated by a user located within building 5. Since the wireless terminal 20 is a portable terminal, when a user moves around building 5 with the wireless terminal 20, it moves to various locations within building 5 as the user moves. As shown in Figure 3, the wireless terminal 20 comprises a control unit 21, a storage unit 22, an operation unit 23, a display unit 24, and a communication unit 25.

[0019] The control unit 21 includes a CPU (Central Processing Unit), ROM (Read Only Memory), and RAM (Random Access Memory). The CPU, also called a central processing unit, central computing unit, processor, microprocessor, or microcomputer, functions as a central computing unit that performs processing and calculations related to the control of the wireless terminal 20. In the control unit 21, the CPU reads programs and data stored in the ROM and uses the RAM as a work area to comprehensively control the wireless terminal 20.

[0020] The storage unit 22 is equipped with non-volatile semiconductor memory such as flash memory, EPROM (Erasable Programmable ROM), and EEPROM (Electrically Erasable Programmable ROM), and plays the role of a so-called secondary storage device or auxiliary storage device. The storage unit 22 stores programs and data used by the control unit 21 for various processing. It also stores data generated or acquired by the control unit 21 through various processing.

[0021] The operation unit 23 is equipped with input devices such as a keyboard, mouse, buttons, touchpad, and touch panel, and accepts operations from the user. The user can input various instructions to the wireless terminal 20 by operating the operation unit 23. When the operation unit 23 receives an operation instruction from the user, it transmits the received operation instruction to the control unit 21.

[0022] The display unit 24 includes a display device such as a liquid crystal display or an organic EL (Electro-Luminescence) display. The display unit 24 is driven by a display drive circuit (not shown) and displays various images under the control of the control unit 21.

[0023] The communication unit 25 is equipped with a communication interface for the wireless terminal 20 to communicate with external devices. The communication unit 25 communicates with external devices, including the management device 30, via a communication network, which is a wide-area communication network. The protocol used for communication is not particularly limited, but a certain general-purpose protocol such as the ECHONET Lite® standard can be adopted. The communication unit 25 also receives wireless signals transmitted from each of the multiple transmitters 10 using a communication standard such as BLE®.

[0024] Returning to Figure 1, the management device 30 is a device that manages the position estimation system 1 and is an example of a position estimation device that estimates the position of the wireless terminal 20. The management device 30 is an information processing device such as a PC or server and is installed under the management of the administrator of the position estimation system 1. The management device 30 may also be a cloud server such as AWS (Amazon Web Services). As shown in Figure 4, the management device 30 comprises a control unit 31, a storage unit 32, and a communication unit 35.

[0025] The control unit 31 includes a CPU, ROM, and RAM. The CPU, also called a central processing unit, central computing unit, processor, microprocessor, or microcomputer, functions as a central computing unit that performs processing and calculations related to the control of the management device 30. In the control unit 31, the CPU reads programs and data stored in the ROM and uses the RAM as a work area to comprehensively control the management device 30.

[0026] The storage unit 32 is equipped with non-volatile semiconductor memory such as flash memory, EPROM, or EEPROM, and serves as a so-called secondary storage device or auxiliary storage device. The storage unit 32 stores programs and data used by the control unit 31 for various processing tasks. It also stores data generated or acquired by the control unit 31 through various processing tasks.

[0027] The communication unit 35 is equipped with a communication interface for the management device 30 to communicate with external devices. The communication unit 35 communicates with external devices, including the wireless terminal 20, via a communication network, which is a wide-area communication network.

[0028] Next, with reference to Figure 5, the functional configuration of the position estimation system 1 will be described. The wireless terminal 20 functionally comprises, in the control unit 21, a transmitter information acquisition unit 211 which is an example of a transmitter information acquisition means, a signal receiving unit 212 which is an example of a signal receiving means, an intensity information transmission unit 213 which is an example of an intensity information transmission means, and a notification unit 214 which is an example of a notification means. The management device 30 functionally comprises, in the control unit 31, a transmitter information transmission unit 311 which is an example of a transmitter information transmission means, an intensity information acquisition unit 312 which is an example of an intensity information acquisition means, an intensity identification unit 313 which is an example of an intensity identification means, a position estimation unit 314 which is an example of a position estimation means, and an output unit 315 which is an example of an output means.

[0029] Each of these functions is implemented in the control units 21 and 31 by software, firmware, or a combination of software and firmware. The software and firmware are written as programs and stored in ROM or storage units 22 and 32. Then, in the control units 21 and 31, the CPU implements the functions shown in Figure 5 by executing the programs stored in ROM or storage units 22 and 32.

[0030] Furthermore, the wireless terminal 20 stores strength information 221 in its storage unit 22. The management device 30 stores transmitter information 321 and property information 322 in its storage unit 32.

[0031] In the management device 30, the storage unit 32 stores transmitter information 321. Transmitter information 321 is information about multiple transmitters 10 installed in building 5. Specifically, as shown in Figure 6, the transmitter information 321 includes the transmitter ID, which is the identification information of each of the multiple transmitters 10, and the location information of each of the multiple transmitters 10 within building 5.

[0032] In the transmitter information 321, the transmitter ID is the same as the identification information included in the radio signal transmitted from each transmitter 10, and is information for uniquely identifying each transmitter 10. The location information is information for identifying the location where each transmitter 10 is installed within the building 5.

[0033] In the example shown in Figure 6, the location information in the transmitter information 321 indicates the location where each transmitter 10 is installed, using three-dimensional coordinates that uniquely represent its position within the building 5. Alternatively, the location information is not limited to this; it may also indicate the location of each transmitter 10 by providing information that shows the room in which each transmitter 10 is installed and its detailed position within that room. Such transmitter information 321 is prepared in advance when multiple transmitters 10 are installed in the building 5, which is the location estimation area, and is stored in the storage unit 32 of the management device 30.

[0034] Returning to Figure 5, in the wireless terminal 20, the transmitter information acquisition unit 211 acquires transmitter information 321 from the management device 30. Specifically, the transmitter information acquisition unit 211 communicates with the management device 30 via the communication unit 25 and sends a request for transmitter information 321 to the management device 30. In the management device 30, when the transmitter information transmission unit 311 receives a request for transmitter information 321 from the wireless terminal 20, it reads the transmitter information 321 stored in the storage unit 32 and transmits it to the wireless terminal 20 that made the request. The transmitter information acquisition unit 211 acquires the transmitter information 321 transmitted from the management device 30 in this way and stores it in the storage unit 22.

[0035] Here, the timing at which the transmitter information acquisition unit 211 acquires the transmitter information 321 from the management device 30 is arbitrary. For example, the transmitter information acquisition unit 211 acquires the transmitter information 321 from the management device 30 immediately after the user operates the operation unit 23 of the wireless terminal 20 and starts the application software that acquires the location information of the wireless terminal 20. Alternatively, the transmitter information acquisition unit 211 may acquire the transmitter information 321 from the management device 30 at any timing in response to the user's operation.

[0036] In the wireless terminal 20, the signal receiving unit 212 receives wireless signals transmitted from each of the multiple transmitters 10. As described above, each transmitter 10 periodically transmits a wireless signal of a predetermined intensity. The signal receiving unit 212 receives a wireless signal when it is transmitted from a transmitter 10 that is within the range in which the wireless terminal 20 can receive wireless signals.

[0037] When the signal receiving unit 212 receives a radio signal transmitted from any of the transmitters 10, it measures the strength of the received radio signal. The strength of the radio signal transmitted from each transmitter 10 is constant at the time of transmission, but it attenuates according to the propagation distance of the radio signal. Therefore, the longer the distance from the source transmitter 10 to the radio terminal 20, the weaker the strength of the radio signal received by the radio terminal 20 becomes. When the signal receiving unit 212 receives a radio signal, it measures the received strength, which is the strength of the received radio signal, and stores the measured value of the received strength in the storage unit 22.

[0038] More specifically, when the signal receiving unit 212 receives a wireless signal, it updates the intensity information 221 stored in the storage unit 22. As shown in Figure 7, the intensity information 221 is information that associates the transmitter ID, which is the identification information of the transmitter 10, with the received intensity of the wireless signal at the wireless terminal 20, in chronological order of the date and time the wireless terminal 20 received the wireless signal. When the signal receiving unit 212 receives a wireless signal, it measures the received intensity of the received wireless signal. The signal receiving unit 212 then stores the measured received intensity value in the intensity information 221, along with the identification information and the current date and time contained in the received wireless signal.

[0039] The signal receiving unit 212 updates this strength information 221 each time it receives a wireless signal transmitted from one of the multiple transmitters 10. As a result, the signal receiving unit 212 accumulates data on the received strength at the wireless terminal 20 for wireless signals repeatedly transmitted from each of the multiple transmitters 10.

[0040] As described above, each transmitter 10 periodically transmits a wireless signal, and therefore transmits the wireless signal multiple times. For this reason, the signal receiving unit 212 receives the wireless signal multiple times for each of the multiple transmitters 10 that are within range of the wireless terminal 20. The strength information 221 indicates the received strength at the wireless terminal 20 of the wireless signals periodically transmitted from each of the multiple transmitters 10.

[0041] Returning to Figure 5, in the wireless terminal 20, the intensity information transmission unit 213 transmits intensity information 221 to the management device 30. Specifically, the intensity information transmission unit 213 communicates with the management device 30 via the communication unit 25 every time the first time interval elapses and transmits the latest intensity information 221 stored in the storage unit 22 to the management device 30.

[0042] Here, the first time is a predetermined duration, corresponding to the time interval used when the management device 30 repeatedly estimates the position of the wireless terminal 20. To ensure the accuracy of position estimation, the first time is set to a duration that allows for the accumulation of, for example, 100 or more received signal strength data points per transmitter 10. For example, if each transmitter 10 repeatedly transmits a wireless signal at a frequency of once per second, the first time is set to a duration such as 5 minutes or 10 minutes.

[0043] Furthermore, when the intensity information transmission unit 213 transmits the intensity information 221 to the management device 30, it transmits the identification information of the wireless terminal 20 along with the intensity information 221 to the management device 30 so that the management device 30 can identify the wireless terminal 20 that is the source of the transmission.

[0044] More specifically, when the intensity information transmission unit 213 has last transmitted intensity information 221, it transmits the information stored in the storage unit 22 that was not transmitted in previous transmissions to the management device 30. In other words, each time an hour has elapsed, the intensity information transmission unit 213 transmits the information updated during the most recent hour to the management device 30.

[0045] In the management device 30, the intensity information acquisition unit 312 acquires intensity information 221 transmitted from the wireless terminal 20. Specifically, the intensity information acquisition unit 312 communicates with the wireless terminal 20 via the communication unit 35 and receives the intensity information 221 transmitted from the wireless terminal 20 every 1 hour, along with the identification information of the wireless terminal 20, which is the source of the transmission.

[0046] As described above, the strength information 221 is information indicating the received strength at the wireless terminal 20 of the wireless signals periodically transmitted from each of the multiple transmitters 10. When the strength information acquisition unit 312 acquires the strength information 221, it stores the acquired strength information 221 in the storage unit 32.

[0047] The intensity determination unit 313 performs data preprocessing for the management device 30 to estimate the location of the wireless terminal 20 based on the intensity information 221 acquired by the intensity information acquisition unit 312. Specifically, the intensity determination unit 313 identifies a threshold intensity, which is the received intensity at which the cumulative relative frequency of the received intensity shown in the intensity information 221 acquired by the intensity information acquisition unit 312 becomes a predetermined threshold T1. Here, the cumulative relative frequency of the received intensity means the cumulative sum of the relative frequencies when the received intensity is sorted in ascending or descending order. When the intensity information acquisition unit 312 acquires the intensity information 221, the intensity determination unit 313 calculates the cumulative relative frequency of the received intensity shown in the acquired intensity information 221 for each transmitter 10.

[0048] To explain in more detail, the intensity information 221 acquired by the intensity information acquisition unit 312 includes accumulated data of the received intensity of radio signals periodically transmitted from each of the multiple transmitters 10 during the most recent first hour. The intensity identification unit 313 classifies the multiple received intensities included in the intensity information 221 acquired by the intensity information acquisition unit 312 for each transmitter 10 based on the identification information of the transmitter 10 associated with each received intensity. Then, the intensity identification unit 313 sorts the multiple received intensities for each transmitter 10 in ascending order, that is, from the lowest received intensity to the highest.

[0049] Figure 8 shows an example in which multiple received intensities included in the intensity information 221 acquired by the intensity information acquisition unit 312 are sorted in ascending order for each transmitter 10. The intensity identification unit 313 sorts, for example, the received intensities of radio signals transmitted from transmitter 10 with transmitter ID "0001" in the most recent 1st hour, from the minimum value "-71.2 dBm" to the maximum value "-46.4 dBm". The intensity identification unit 313 similarly sorts the received intensities of radio signals transmitted from other transmitters 10 in ascending order.

[0050] When the received signals are sorted, the intensity identification unit 313 calculates the cumulative relative frequency of the multiple received signals sorted in ascending order for each transmitter 10. That is, for each transmitter 10, the intensity identification unit 313 calculates the cumulative sum of the relative frequencies of the multiple received signals, starting from the lowest received signal. Then, the intensity identification unit 313 identifies the received signal whose cumulative relative frequency reaches a predetermined threshold T1. The threshold T1 is a first threshold, which is pre-set to a value of, for example, about 75%.

[0051] In the example shown in Figure 8, for the received signal strength of transmitter ID "0001", the received signal strength at which the cumulative relative frequency reaches the threshold of 75% corresponds to "-61.4 dBm". The signal strength identification unit 313 identifies the received signal strength at which such a cumulative relative frequency reaches the threshold T1 for each of the multiple transmitters 10 identified by the transmitter ID as the threshold signal strength.

[0052] The reason for calculating the cumulative relative frequency of the received signal strength and identifying the received signal strength at which the calculated cumulative relative frequency becomes the threshold T1 is to suppress the variation in the received signal strength of the radio signals transmitted from each transmitter 10. This will be explained in detail with reference to Figure 9.

[0053] Figure 9 shows an example of the frequency distribution and cumulative relative frequency of the received signal strength at the wireless terminal 20 for a single transmitter 10 transmitted on different days or at different times, namely Schedule A and Schedule B. In Figure 9, the horizontal axis represents the received signal strength as RSSI (Received Signal Strength Indicator), and the vertical axis represents the frequency and cumulative relative frequency. In Figure 9, the frequency distribution is represented by a solid line, and the cumulative relative frequency is represented by a dashed line. Note that the positions of the transmitter 10 and the wireless terminal 20 are fixed in both Schedule A and Schedule B, and all other conditions are assumed to be the same.

[0054] In the upper panel of Figure 9, under Schedule A, the frequency distribution of received signal strength forms a single peak around -60 dBm. In contrast, in the lower panel of Figure 9, under Schedule B, the frequency distribution of received signal strength forms two peaks, i.e., two maximum values, around -70 dBm and -60 dBm.

[0055] The reason for the difference in frequency distribution between Schedule A and Schedule B is that the strength of the radio signal received by the wireless terminal 20 fluctuates due to the environment surrounding the wireless terminal 20. Specifically, radio waves include direct waves and reflected waves, and multiple radio waves are present in environments such as homes and offices. Radio interference occurs due to various factors such as the influence of reflected waves from walls, floors, and ceilings, and the influence of radio waves emitted from other devices. Therefore, even if the wireless terminal 20 is in the same location, the degree of radio interference differs depending on the environment surrounding the wireless terminal 20, such as the number of people and the degree of their movement, and the received strength of the radio signal may fluctuate. For example, the received strength of the radio signal can fluctuate by about 10 dBm instantaneously. Due to such fluctuations, when the influence of radio interference is small, as in Schedule A, the frequency distribution forms a single peak, but when the influence of radio interference is large, as in Schedule B, the frequency distribution forms two peaks.

[0056] Thus, even if the wireless terminal 20 receives a wireless signal in the same location, the received signal strength may fluctuate. Therefore, even if the maximum value, average value, median value, mode value, etc. are used as representative values ​​of the received signal strength for estimating the location of the wireless terminal 20, the accuracy of the location estimation may not be stable. Taking these circumstances into consideration, the intensity determination unit 313 determines a value based on the cumulative relative frequency of the received signal strength as a representative value of the received signal strength of wireless signals repeatedly transmitted from a single transmitter 10.

[0057] More specifically, the intensity determination unit 313 identifies the received intensity at which the cumulative relative frequency of the received intensity becomes a predetermined threshold T1, as a representative value of the received intensity used for position estimation of the wireless terminal 20, i.e., an index. Here, the threshold T1 is predetermined to an appropriate value so that a value that is easily stable regardless of the environment can be used as a representative value of the received intensity.

[0058] For example, although the number of peaks in the frequency distribution differs between Schedule A and Schedule B shown in Figure 9, the cumulative relative frequency is approximately the same for both Schedule A and Schedule B if the received intensity is around -60 dBm, as indicated by the dashed line in Figure 9. The received intensity within this dashed line range corresponds to the intensity near a single peak in the frequency distribution for Schedule A, and to the intensity near the stronger of the two peaks in the frequency distribution for Schedule B.

[0059] As described above, when two peaks are formed in the frequency distribution, it has been found through experimentation that the received intensity corresponding to the upper peak tends to be more stable and less affected by the environment. The reason for this is that when multiple peaks are formed in the frequency distribution, the peaks at lower intensities often correspond to intensities that have been attenuated due to interference, and are therefore less stable than the peaks at higher intensities. Taking this phenomenon into consideration, the threshold T1 is set to a value near the upper peak when two peaks exist in the frequency distribution, that is, a value where the cumulative relative frequency when the received intensities are arranged in ascending order is 50% or higher.

[0060] More specifically, the threshold T1 is unsuitable if it is close to 100%, so it is set to a value that is 50% or more and less than 100%. For example, it is preferable to set it in the range of 70% to 80%. Below, we will explain using the case where 75% is used as the threshold T1 as an example. In other words, the received strengths corresponding to 75% of the received strengths of the wireless signals transmitted multiple times from a single transmitter 10 are used as the threshold strength, which is their representative value. Note that the threshold strength specified for each transmitter 10 serves as an indicator of the distance from each transmitter 10 to the wireless terminal 20, so the threshold T1 is set to the same value among the multiple transmitters 10 installed in the building 5.

[0061] In this way, the intensity determination unit 313 calculates the cumulative relative frequency of received signal strength from the accumulated data of received signal strength of the wireless terminal 20 received by the wireless terminal 20 in the most recent first hour for each of the multiple transmitters 10, and identifies the received signal strength at which the calculated cumulative relative frequency becomes the threshold T1 as the threshold strength. As a result, the intensity determination unit 313 derives an index of received signal strength for each of the multiple transmitters 10 that is different from general representative values ​​such as the maximum value, mean value, median value, and mode value, and is less susceptible to variation due to the surrounding environment.

[0062] Returning to Figure 5, the position estimation unit 314 estimates the position of the wireless terminal 20 based on the threshold intensity identified by the intensity identification unit 313 and the positions of each of the multiple transmitters 10. In order to estimate the position of the wireless terminal 20, the position estimation unit 314 first determines whether the threshold intensity identified for each of the multiple transmitters 10 by the intensity identification unit 313 is smaller than a predetermined threshold T2. Threshold T2 is a second threshold set to improve the accuracy of position estimation.

[0063] Figure 10 shows how the received signal strength of the wireless terminal 20 attenuates according to the distance between the transmitter 10 and the wireless terminal 20. In Figure 10, the solid line represents the actually measured received signal strength, and the dashed line represents the ideal attenuation curve of the wireless signal.

[0064] As shown by the dashed line in Figure 10, ideally, the received signal strength of a wireless signal attenuates smoothly as the distance between the transmitter 10 and the wireless terminal 20 increases. However, as shown by the solid line in Figure 10, the actually measured received signal strength exhibits variability compared to the ideal attenuation curve due to the effects of multipath. Such variability makes it difficult to calculate the distance from the received signal strength value, leading to a large error in position estimation.

[0065] Therefore, the position estimation unit 314 discards the calculation results of threshold intensities smaller than threshold T2 among the threshold intensities identified for each of the multiple transmitters 10 by the intensity identification unit 313, and excludes them from the received intensities used for position estimation. In other words, if a wireless terminal 20 receives a wireless signal but its threshold intensity is smaller than threshold T2, it is highly likely that the wireless terminal 20 is not near the transmitter 10. Transmitters 10 that are far from the wireless terminal 20 and whose received intensities tend to vary are excluded from the targets used for position estimation. In this way, the position estimation unit 314 avoids using received intensities whose distance is difficult to uniquely determine in position estimation, thereby improving the accuracy of position estimation. In the example in Figure 10, threshold T2 is set to a value corresponding to -70 dBm.

[0066] More specifically, the position estimation unit 314 estimates that the wireless terminal 20 is not located in building 5 if all of the threshold intensities identified for each of the multiple transmitters 10 by the intensity identification unit 313 are smaller than the threshold T2. To explain in more detail, if the threshold intensities from all transmitters 10 are smaller than the threshold T2, the wireless terminal 20 is located far from all of the transmitters 10, and therefore is highly likely not to be located inside building 5 at all. In this case, the position estimation unit 314 estimates that the wireless terminal 20 is located outside building 5.

[0067] In response to this, if, among the threshold intensities identified for multiple transmitters 10, some threshold intensities are smaller than threshold T2 and some threshold intensities are larger than threshold T2, the position estimation unit 314 excludes the threshold intensities smaller than threshold T2 from the threshold intensities used for position estimation. In this case, the position estimation unit 314 decides that the remaining threshold intensities larger than threshold T2 will be the target of position estimation as described below. This improves the accuracy of position estimation by excluding transmitters 10 that are far from the wireless terminal 20 and whose received signal strength is prone to variation from the target of position estimation. Furthermore, if all of the threshold intensities identified for multiple transmitters 10 are larger than threshold T2, the position estimation unit 314 decides that all of the threshold intensities will be the target of position estimation as described below.

[0068] Once threshold strengths greater than threshold T2 are determined to be the target for location estimation, the location estimation unit 314 estimates the floor and room where the wireless terminal 20 is located. The location estimation unit 314 identifies the transmitter 10 with the highest threshold strength among multiple transmitters 10 whose threshold strengths are greater than threshold T2. Then, the location estimation unit 314 refers to the transmitter information 321 to obtain the location information of the transmitter 10 with the highest threshold strength and identifies the floor and room within the building 5 corresponding to the obtained location information.

[0069] The location estimation unit 314 refers to the property information 322 stored in the memory unit 32 when identifying the floor and room within the building 5. The property information 322 is information about the building 5, which is the location estimation area, and includes information about the floors and rooms that the building 5 has. Specifically, the property information 322 includes information such as the number of floors that the building 5 has and a floor map showing the arrangement of rooms on each floor. From the property information 322 and the location information of each transmitter 10 in the transmitter information 321, the floor and room where each transmitter 10 is located within the building 5 can be identified.

[0070] The position estimation unit 314 acquires property information 322 from a property information management device, which is an external device to the management device 30, via the communication unit 35. The property information management device, although not shown in the figures, is a device that manages information about properties, including building 5. The property information management device is equipped with a communication interface and transmits the latest property information 322 of building 5 to the management device 30 in response to a request from the management device 30. The timing at which the position estimation unit 314 acquires property information 322 from the property information management device is an arbitrary design matter. For example, the position estimation unit 314 may acquire property information 322 from the property information management device immediately after the management program in the management device 30 is started, or it may acquire property information 322 from the property information management device in response to operator operations.

[0071] The location estimation unit 314 refers to the property information 322 and identifies the floor on which the transmitter 10 with the highest threshold strength is located among the multiple floors of the building 5. The location estimation unit 314 then estimates that the wireless terminal 20 is located on the identified floor and determines that the identified floor is the floor to be estimated.

[0072] This makes it possible to narrow down the floor on which the wireless terminal 20 is located when multiple transmitters 10 are installed on different floors. In particular, even if a wireless signal is received from a transmitter 10 on a different floor from the floor on which the user is located, the accuracy of subsequent location estimation can be improved by narrowing down the floor to which the target floor is the transmitter 10 with the highest threshold strength.

[0073] Once the floor where the wireless terminal 20 is located is identified, the location estimation unit 314 further refers to the property information 322 to identify the room where the transmitter 10 with the highest threshold strength is located from among several rooms on the identified floor. The location estimation unit 314 then estimates that the wireless terminal 20 is located in the identified room and determines that the identified room is the room to be estimated.

[0074] This allows the system to pinpoint the location to a single room when multiple transmitters 10 are installed in different rooms. In particular, wireless signals from transmitters 10 installed in enclosed spaces such as conference rooms or apartment rooms are more susceptible to signal attenuation due to walls, ceilings, etc., compared to wireless signals from transmitters 10 installed in open spaces. By avoiding the use of transmitters 10 in enclosed spaces that are prone to signal attenuation when the user is not in an enclosed space, the accuracy of subsequent location estimation can be improved.

[0075] Once the floor and room to be estimated are determined, the location estimation unit 314 estimates the location of the wireless terminal 20 in more detail within the estimated floor and room. Specifically, the location estimation unit 314 estimates the location of the wireless terminal 20 based on the threshold strength of at least one transmitter 10 installed in the target room on the target floor, among the multiple transmitters 10 installed in the building 5, and the location of at least one transmitter 10.

[0076] More specifically, the position estimation unit 314 estimates the position of the wireless terminal 20 using one of the estimation methods (1) to (3) below, or a combination of multiple estimation methods. Which of the estimation methods (1) to (3) below to be adopted may be predetermined by, for example, the operator of the management device 30, or it may be made possible for the user of the wireless terminal 20 to select it.

[0077] (1) As a first estimation method, the position estimation unit 314 estimates that the wireless terminal 20 is located at the position of the transmitter 10 with the highest threshold strength among the multiple transmitters 10 installed in the floor and room to be estimated. For example, if the transmitter 10 with the highest threshold strength is installed on the wall of the room, the position estimation unit 314 estimates that the wireless terminal 20 is located at that wall. If there is only one transmitter 10 installed in the floor and room to be estimated, the position estimation unit 314 estimates that the wireless terminal 20 is located at the position of that transmitter 10. The accuracy of position estimation in the first estimation method is limited by the installation interval of the transmitters 10. Therefore, the first estimation method has the lowest accuracy of position estimation among the three estimation methods, but it is the simplest to process.

[0078] (2) As a second estimation method, the position estimation unit 314 estimates the position of the wireless terminal 20 using the principle of so-called triangulation or three-point surveying. Specifically, the position estimation unit 314 uses the position of one transmitter 10 as a reference and sets a range based on the threshold intensity specified for one transmitter 10 for each of the multiple transmitters 10 installed on the floor and in the room to be estimated. The position estimation unit 314 then estimates that the wireless terminal 20 is located at the position where the ranges set for each of the multiple transmitters 10 overlap. Here, the range based on the threshold intensity is represented by a circle that gets larger as the threshold intensity value decreases, based on the attenuation curve according to the distance of the wireless signal. The position estimation unit 314 sets such a circle for each transmitter 10 and estimates that the wireless terminal 20 is located at the position where multiple circles overlap.

[0079] (3) As a third estimation method, the position estimation unit 314 sets multiple candidate positions and estimates the location where the wireless terminal 20 is located from among the multiple candidate positions. Specifically, the position estimation unit 314 sets multiple candidate positions on the floor and room to be estimated. For example, the position estimation unit 314 sets multiple candidate positions within a predetermined range based on the previous position, which is the last position of the wireless terminal 20 estimated by the position estimation unit 314.

[0080] When multiple candidate locations are set, the location estimation unit 314 compares a distance order, which is obtained by arranging the distances between one of the multiple candidate locations and each of the multiple transmitters 10 installed in the floor and room to be estimated, in ascending order, with an intensity order, which is obtained by arranging the threshold intensity identified for each of the multiple transmitters 10 in descending order.

[0081] The position estimation unit 314 performs a comparison process comparing distance order and intensity order for each of the multiple candidate positions. Since the received intensity increases as the distance decreases, if the wireless terminal 20 is present at a candidate position, the distance order and intensity order at that position will ideally match perfectly. Therefore, the position estimation unit 314 estimates that the wireless terminal 20 is present at the candidate position among the multiple candidate positions where the distance order and intensity order best match.

[0082] Regardless of which of the estimation methods (1) to (3) is used, the position estimation unit 314 can estimate the position of the wireless terminal 20 using a stable index because it uses a threshold intensity determined based on the cumulative relative frequency of the received intensity. Therefore, the position of the wireless terminal 20 can be estimated with high accuracy.

[0083] Returning to Figure 5, the output unit 315 outputs output information based on the position of the wireless terminal 20 estimated by the position estimation unit 314. Specifically, when the position of the wireless terminal 20 is estimated by the position estimation unit 314, the output unit 315 communicates with the wireless terminal 20 via the communication unit 35 and transmits output information indicating the estimated position to the wireless terminal 20. As a result, the output unit 315 displays the position of the wireless terminal 20 estimated by the position estimation unit 314 on the display unit 24 of the wireless terminal 20.

[0084] In the wireless terminal 20, the notification unit 214 notifies the user of the location of the wireless terminal 20 estimated by the location estimation unit 314. When output information is transmitted from the management device 30, the notification unit 214 receives the transmitted output information and displays the received output information on the display unit 24 of the wireless terminal 20.

[0085] The notification unit 214 displays, for example, the notification screen shown in Figure 11 on the display unit 24. Specifically, the notification unit 214 displays a floor map centered on the room of the estimated target on the floor of the building 5. The notification unit 214 then displays a mark indicating the current location of the wireless terminal 20 at the location indicated in the output information received from the management device 30 on the floor map. This allows the user of the wireless terminal 20 to easily confirm their current location within the building 5.

[0086] Next, with reference to Figures 12 and 13, the processing flow performed in the position estimation system 1 will be described. The processing shown in Figures 12 and 13 is an example of a position estimation method.

[0087] Firstly, Figure 12 shows the flow of the intensity information transmission process performed by the wireless terminal 20. The intensity information transmission process shown in Figure 12 is initiated when the application software for acquiring the device's location information is launched in the wireless terminal 20.

[0088] When the signal strength information transmission process is started, the control unit 21 in the wireless terminal 20 acquires transmitter information 321, which includes identification information and location information of multiple transmitters 10 located within the building 5, from the management device 30 and stores it in the storage unit 22 (step S1). In step S1, the control unit 21 functions as a transmitter information acquisition unit 211.

[0089] Upon acquiring transmitter information 321, the control unit 21 determines whether or not it has received a radio signal from any of the transmitters 10 (step S2). If a radio signal is received (step S2; YES), the control unit 21 measures the received strength of the radio signal (step S3).

[0090] When the received signal strength is measured, the control unit 21 updates the signal strength information 221 (step S4). Specifically, the control unit 21 associates the measured received signal strength value with the identification information of the source transmitter 10 included in the received wireless signal and the current date and time, and stores it in the signal strength information 221 stored in the memory unit 22.

[0091] In contrast, if no wireless signal is received (step S2; NO), the control unit 21 skips the processing in steps S3 to S4. In steps S2 to S4, the control unit 21 functions as a signal receiving unit 212.

[0092] Next, the control unit 21 determines whether or not 1 hour has elapsed since the transmission of the most recent intensity information 221 (step S5). If 1 hour has elapsed (step S5; YES), the control unit 21 transmits the intensity information 221 to the management device 30 (step S6).

[0093] In contrast, if 1 hour has not elapsed since the transmission of the most recent intensity information 221 (step S5; NO), the control unit 21 skips step S6. In steps S5 and S6, the control unit 21 functions as an intensity information transmission unit 213.

[0094] Subsequently, the control unit 21 returns to step S2 and executes the processes in steps S2 to S6 again. As a result, the control unit 21 repeatedly updates the intensity information 221 each time it receives a radio signal from any of the transmitters 10, and transmits the intensity information 221 to the management device 30 each time the first time interval has elapsed.

[0095] Secondly, Figure 13 shows the flow of the position estimation process performed by the management device 30. The position estimation process shown in Figure 13 is performed when the management device 30 is operating normally and intensity information 221 is transmitted from the wireless terminal 20.

[0096] When the position estimation process starts, the control unit 31 in the management device 30 determines whether or not it has acquired the intensity information 221 transmitted from the wireless terminal 20 (step S11). If the intensity information 221 has not been acquired (step S11; NO), the control unit 31 terminates the position estimation process shown in Figure 13 without executing the processes from step S12 onward. In step S11, the control unit 31 functions as an intensity information acquisition unit 312.

[0097] If intensity information 221 is acquired (step S11; YES), the control unit 31 sorts the received intensities included in the acquired intensity information 221 in ascending order for each transmitter 10 and calculates the cumulative relative frequency of the received intensities (step S12). Then, for each transmitter 10, the control unit 31 identifies a threshold intensity, which is the received intensity at which the cumulative relative frequency becomes the threshold T1 (step S13). In steps S12 to S13, the control unit 31 functions as an intensity identification unit 313.

[0098] Once the threshold intensity is determined, the control unit 31 determines whether the threshold intensity of all transmitters 10 is less than the threshold T2 (step S14). If the threshold intensity of at least one transmitter 10 is greater than or equal to the threshold T2 (step S14; NO), the control unit 31 identifies the floor to be estimated (step S15). Specifically, the control unit 31 identifies the floor to be estimated as the floor where the transmitter 10 with the highest threshold intensity, as determined for each transmitter 10 in step S13, is located among the multiple floors of the building 5.

[0099] Once the hierarchy to be estimated is identified, the control unit 31 identifies the room to be estimated (step S16). Specifically, among the multiple hierarchies included in the hierarchy to be estimated identified in step S15, the control unit 31 identifies the room where the transmitter 10 with the maximum threshold strength, identified for each transmitter 10 in step S13, is installed as the room to be estimated.

[0100] Once the floor and room to be estimated are identified, the control unit 31 estimates the location of the wireless terminal 20 (step S17). Specifically, the control unit 31 estimates the location of the wireless terminal 20 in the floor and room to be estimated based on the threshold intensity of at least one transmitter 10 installed in the floor and room to be estimated identified in steps S15 and S16, and the location of at least one transmitter 10, using one or a combination of the estimation methods (1) to (3) described above. In steps S14 to S17 and S19, the control unit 31 functions as a location estimation unit 314.

[0101] When the position of the wireless terminal 20 is estimated, the control unit 31 outputs the estimation result (step S18). For example, the control unit 31 transmits output information indicating the position of the wireless terminal 20 estimated in step S17 to the wireless terminal 20, and displays it on the display unit 24 of the wireless terminal 20. In step S18, the control unit 31 functions as an output unit 315.

[0102] In contrast, if the threshold intensity of all transmitters 10 is less than the threshold T2 (step S14; YES), the control unit 31 estimates that the wireless terminal 20 is not in building 5 (step S19). Then, the control unit 31 moves to step S18 and transmits output information to the wireless terminal 20 indicating that the wireless terminal 20 is not in building 5, which is then displayed on the display unit 24 of the wireless terminal 20. With this, the position estimation process shown in Figure 13 is completed.

[0103] As described above, the position estimation system 1 according to Embodiment 1 identifies a threshold intensity, which is the reception intensity at which the cumulative relative frequency of the received intensity of the radio signal periodically transmitted from the transmitter 10 reaches a predetermined threshold T1. Based on the identified threshold intensity and the position of the transmitter 10, the position of the radio terminal 20 is estimated. By using the cumulative relative frequency of the received intensity in this way, variations in the received intensity due to interference of the radio signal can be suppressed, and a stable index can be used as an index for estimating the position of the radio terminal 20. As a result, the position of the radio terminal 20 can be estimated with high accuracy.

[0104] In particular, when the wireless terminal 20 is located inside a building 5 where interference is likely to occur due to various factors such as reflected waves and signals from other devices, variations in reception strength are likely to occur. Even in such situations, the position estimation system 1 according to Embodiment 1 can estimate the position of the wireless terminal 20 with high accuracy.

[0105] (Embodiment 2) Next, Embodiment 2 will be described. Descriptions of the same configuration and functions as in Embodiment 1 will be omitted as appropriate.

[0106] Figure 14 shows the functional configuration of the position estimation system 1 according to Embodiment 2. The management device 30 according to Embodiment 2 functionally includes, in the control unit 31, a transmitter information transmission unit 311, an intensity information acquisition unit 312, an intensity identification unit 313, a position estimation unit 314, an output unit 315, and a learning unit 316. Each of these functions is realized in the control unit 31 by software, firmware, or a combination of software and firmware.

[0107] Furthermore, the management device 30 stores transmitter information 321, property information 322, and learned models 323 in its storage unit 32. Note that the configuration of the management device 30 other than the learning unit 316 and learned models 323, and the configuration of the wireless terminal 20 are the same as in Embodiment 1, so their description is omitted.

[0108] The position estimation unit 314 estimates the floor and room to be estimated in the same manner as in Embodiment 1. Once the floor and room to be estimated are estimated, the position estimation unit 314 estimates the position of the wireless terminal 20 using an estimation method that utilizes the trained model 323, instead of the estimation methods (1) to (3) described in Embodiment 1.

[0109] First, the location estimation unit 314 divides the room to be estimated into multiple areas. As an example, as shown in Figure 15, the location estimation unit 314 divides the room to be estimated into 16 areas numbered 1 to 16. This allows the location estimation unit 314 to set up multiple areas within the room to be estimated that are candidates for the presence of the wireless terminal 20. Using the trained model 323, the location estimation unit 314 estimates which of the 16 areas the wireless terminal 20 is located in.

[0110] The trained model 323 is a model for estimating the location of the wireless terminal 20 from the threshold intensity identified for each of the multiple transmitters 10 by the intensity identification unit 313. The trained model 323 receives the threshold intensity values ​​identified for each of the multiple transmitters 10 installed in the room to be estimated as input, and outputs a value indicating the probability of existence, which is the likelihood that the wireless terminal 20 is present in each of the multiple areas.

[0111] In Figure 15, as an example, four transmitters a to d are installed at the boundary of each area in the room to be estimated. The trained model 323 receives the threshold intensity values ​​identified for each of the four transmitters a to d as input and outputs a value indicating the probability of the presence of the wireless terminal 20 in each of the 16 areas 1 to 16.

[0112] Specifically, as shown in Figure 16, the trained model 323 is composed of a neural network. The neural network has an input layer into which input data is input, an output layer into which output data is output, and at least one hidden layer. The number of nodes in the input layer corresponds to the number of input data, and the number of nodes in the output layer corresponds to the number of output data. The number of hidden layers can be arbitrary. The straight lines between nodes represent the parameter connections between the input layer and the output layer. Each node in the input layer accepts input values ​​of threshold intensity values ​​identified for each of the four transmitters a to d. In response to such inputs, each node in the output layer outputs the probability of presence of the wireless terminal 20 in each of the 16 areas 1 to 16.

[0113] Returning to Figure 14, the learning unit 316 generates such a trained model 323 using machine learning. The learning unit 316 is an example of a learning method.

[0114] As an example, the learning unit 316 calculates the distance D1 between each transmitter 10 and the wireless terminal 20 by converting the threshold strength identified for each transmitter a to d into distance, according to the equation for the attenuation curve of the wireless signal. For example, in the ideal attenuation curve shown in Figure 10, if the threshold strength of transmitter a is -55 dBm, the distance between transmitter a and the wireless terminal 20 is converted to approximately 3 m. Next, the learning unit 316 calculates the distance D2 to each transmitter 10 for each area, using the position coordinates of transmitters a to d and the coordinates of areas 1 to 16. The learning unit 316 calculates these distances D1 and D2 for each of the four transmitters a to d. Then, for each area, the learning unit 316 calculates the sum of the differences between distance D1 and distance D2 for the four transmitters a to d. The learning unit 316 adjusts the weights of the connections in each layer of the neural network so that the probability of the presence of the wireless terminal 20 is higher in areas where the calculated sum is smaller. The learning unit 316 generates a trained model 323 by repeatedly performing this type of learning.

[0115] Alternatively, the actual location information of the wireless terminal 20 may be used as training data. The actual location information of the wireless terminal 20 can be obtained, for example, by having the user input their current location coordinates into the wireless terminal 20 using a questionnaire. By using the location information of the wireless terminal 20, the distance D1 can be calculated from the location coordinates of the wireless terminal 20 and the location coordinates of transmitters a to d. Therefore, by combining the calculated distance D1 with the threshold intensity of transmitters a to d, it is possible to derive a correlation between distance D1 and threshold intensity. As a result, the threshold intensity can be converted to distance D1 without using the attenuation curve equation.

[0116] Alternatively, the learning unit 316 may generate a trained model 323 by performing supervised learning using multiple datasets, each consisting of a combination of threshold intensity values ​​of transmitters a to d and the position coordinates of the wireless terminal 20, as training data.

[0117] The position estimation unit 314 estimates the position of the wireless terminal 20 based on the trained model 323 generated by the learning unit 316. Specifically, the position estimation unit 314 inputs the threshold intensity identified for each of the multiple transmitters 10 by the intensity identification unit 313 as input data to the trained model 323. The position estimation unit 314 then compares the probability of the wireless terminal 20's presence in each area, output from the trained model 323 for these inputs, and estimates that the wireless terminal 20 is located in the area with the highest probability of presence.

[0118] As described above, the position estimation system 1 according to Embodiment 2 estimates the position of the wireless terminal 20 using a trained model 323 generated by machine learning. Since the trained model 323 uses a threshold intensity determined based on the cumulative relative frequency of received intensity as input, the position of the wireless terminal 20 can be estimated using a stable index. Therefore, the position of the wireless terminal 20 can be estimated with high accuracy.

[0119] (Embodiment 3) Next, Embodiment 3 will be described. Descriptions of configurations and functions similar to those in Embodiments 1 and 2 will be omitted as appropriate.

[0120] If any of the multiple transmitters 10 installed within the building 5 are located in the ceiling space, behind a pillar, inside equipment, etc., the received signal strength of the wireless signal transmitted from that transmitter 10 at the wireless terminal 20 will always be attenuated by a certain amount compared to the received signal strength from the other transmitters 10. To compensate for this attenuation of received signal strength, in Embodiment 3, the position estimation unit 314 corrects the identified threshold strength for at least one transmitter 10 installed behind an obstruction before estimating the position.

[0121] Specifically, the position estimation unit 314 corrects the threshold intensity identified by the intensity determination unit 313 for at least one of the multiple transmitters 10 that are within range of the wireless terminal 20's ability to receive wireless signals, according to the location where that at least one transmitter 10 is installed. Then, the position estimation unit 314 estimates the position of the wireless terminal 20 based on the corrected threshold intensity.

[0122] More specifically, the position estimation unit 314 does not correct the threshold intensity for the remaining transmitters 10 of the plurality of transmitters 10, except for at least one transmitter 10, as in Embodiment 1, and uses the threshold intensity determined by the intensity determination unit 313 as is. Therefore, the position estimation unit 314 estimates the position of the wireless terminal 20 based on the corrected threshold intensity for at least one transmitter 10 of the plurality of transmitters 10, the uncorrected threshold intensity for the remaining transmitters 10 of the plurality of transmitters 10, and the positions of the plurality of transmitters 10. The details of the position estimation process are the same as in Embodiment 1.

[0123] When correcting the threshold strength, the position estimation unit 314 adds a larger offset value to the threshold strength for transmitters 10 installed in locations where the degree of attenuation of the received signal strength is greater. Here, the degree of attenuation of the received signal strength varies depending on the location where each transmitter 10 is installed. The offset value used to correct the threshold strength may be set manually or derived from past measurement data using machine learning.

[0124] By correcting the threshold strength in this way, the threshold strength of transmitter 10 installed in a location where wireless signals are easily attenuated is converted to a value that can be compared with the threshold strength of other transmitters 10. As a result, the threshold strength of each transmitter 10 can be appropriately used as an indicator of distance, thereby improving the accuracy of estimating the position of the wireless terminal 20.

[0125] (modified version) Although the embodiments have been described above, it is possible to combine the embodiments or modify or omit them as appropriate.

[0126] For example, in the above embodiment, the intensity determination unit 313 sorted the multiple received intensities included in the intensity information 221 in ascending order and calculated the cumulative relative frequency. However, the intensity determination unit 313 may also sort the multiple received intensities included in the intensity information 221 in descending order and calculate the cumulative relative frequency. The threshold T1 = 75% when the received intensities are sorted in ascending order is the same as the threshold T1 = 25% when the received intensities are sorted in descending order.

[0127] Furthermore, the threshold T1 is not limited to 75%. The threshold T1 may be set to, for example, 65%, 70%, 80%, 85%, etc. Also, the threshold T1 may be any value that allows the reception intensity at the peak with the larger reception intensity among the two peaks, i.e., the frequency distribution of the reception intensity, to be identified as the threshold intensity, when there are two peaks, i.e., local maximums, in the case of two peaks in the frequency distribution of the reception intensity.

[0128] Threshold T1, threshold T2, and the first time interval for determining the threshold intensity may be set manually or derived from past measured data using machine learning. For example, from the measured data of received signal intensity over multiple past instances of wireless signals transmitted from each transmitter 10, if there are two peaks in the frequency distribution of received signal intensity, the value corresponding to the higher of the two peaks may be derived as threshold T1.

[0129] In the above embodiment 2, the management device 30 was equipped with the functions of a learning unit 316. However, the management device 30 does not necessarily have to be equipped with the functions of a learning unit 316. In this case, an external device to the management device 30 generates a trained model 323 by performing machine learning, and the management device 30 acquires the generated trained model 323 via the communication unit 35. The position estimation unit 314 estimates the position of the wireless terminal 20 using the trained model 323 acquired from the external device. Furthermore, the learning unit 316 may use other machine learning methods, not just the neural network method described above.

[0130] In the above embodiment, the position estimation system 1 was equipped with multiple transmitters 10. However, the position estimation system 1 may have only one transmitter 10. When there is only one transmitter 10, the position estimation unit 314 estimates that the wireless terminal 20 is located within a range based on the position of the single transmitter 10, where a smaller threshold intensity corresponds to a larger range. Thus, while the accuracy of position estimation can be improved by using multiple transmitters 10, the position of the wireless terminal 20 can be estimated with a minimum level of accuracy even with only one transmitter 10.

[0131] More specifically, in the above embodiment, the position estimation unit 314 estimated that the wireless terminal 20 was not present in the building 5 if all of the threshold intensities identified for each of the multiple transmitters 10 by the intensity identification unit 313 were smaller than the threshold T2. In contrast, when there is only one transmitter 10, the position estimation unit 314 estimated that the wireless terminal 20 was not present in the building 5 if the threshold intensity identified for that single transmitter 10 by the intensity identification unit 313 was smaller than the threshold T2. Furthermore, in the above embodiment 2, the trained model 323 was a model that estimated the position of the wireless terminal 20 from the threshold intensities identified for each of the multiple transmitters 10 by the intensity identification unit 313. In contrast, when there is only one transmitter 10, the trained model 323 is a model that estimates the position of the wireless terminal 20 from the threshold intensity identified for that single transmitter 10 by the intensity identification unit 313. The learning unit 316 generates such a trained model 323 using machine learning.

[0132] In the above embodiment, there was only one wireless terminal 20 whose position was to be estimated in the position estimation system 1. However, there may be multiple wireless terminals 20 within the building 5. The management device 30 may then perform the processing described in the above embodiment for each of the multiple wireless terminals 20 to estimate the position of each of the multiple wireless terminals 20.

[0133] In the above embodiment, the output unit 315 transmits output information indicating the location of the wireless terminal 20 estimated by the location estimation unit 314 to the wireless terminal 20, and displays it on the display unit 24 of the wireless terminal 20. However, the output unit 315 is not limited to displaying output information on the display unit 24 and may be used for other purposes. For example, the output unit 315 may control equipment such as air conditioners and lighting installed in the building 5 based on the location of the wireless terminal 20 estimated by the location estimation unit 314.

[0134] To explain in more detail, the output unit 315 may transmit a control command to the air conditioner or lighting as output information, which in turn turns on the air conditioner or lighting at the location of the wireless terminal 20 estimated by the location estimation unit 314. Alternatively, the location estimation unit 314 estimates the locations of multiple wireless terminals 20 and, based on the estimated locations of the multiple wireless terminals 20, estimates the areas within the building 5 where people are present and areas where people are not. The output unit 315 may then transmit a control command to the air conditioner or lighting as output information, which in turn turns on the air conditioner or lighting in the areas within the building 5 where people are present and turns off the air conditioner or lighting in the areas within the building 5 where people are not present.

[0135] In the above embodiment, the wireless terminal 20 was equipped with an operation unit 23 and a display unit 24, and was an operation terminal operated by the user. However, the wireless terminal 20 does not need to have an operation unit 23 or a display unit 24, as long as it has the function of receiving wireless signals transmitted from the transmitter 10 and transmitting information related to the reception to the management device 30. For example, the wireless terminal 20 may be a device such as an IC (Integrated Circuit) tag that only has the function of transmitting and receiving radio waves. If the wireless terminal 20 does not have a display unit 24, the wireless terminal 20 may transmit the information transmitted from the management device 30 to an external device such as a PC or digital signage and display it.

[0136] In the above embodiment, the wireless terminal 20 and the management device 30 had the functional configuration shown in Figure 5. However, the configuration shown in Figure 5 is just one example, and in the position estimation system 1, the functions of each part may be provided in any device. For example, the function of the intensity determination unit 313 may be provided in the wireless terminal 20. In this case, the wireless terminal 20 identifies a threshold intensity, which is the received intensity at which the cumulative relative frequency of the received intensity of the wireless signal reaches a predetermined threshold, and transmits the information of the identified threshold intensity to the management device 30 via the communication unit 25. Then, in the management device 30, the position estimation unit 314 estimates the position of the wireless terminal 20 based on the threshold intensity identified in the wireless terminal 20 and the position of the transmitter 10. Alternatively, the function of the position estimation unit 314 may also be provided in the wireless terminal 20 in addition to the intensity determination unit 313.

[0137] In the above embodiment, the control units 21 and 31 functioned as the respective parts shown in Figure 5 by the CPU executing programs stored in ROM or storage units 22 and 32. However, the control units 21 and 31 may be dedicated hardware. Dedicated hardware includes, for example, single circuits, complex circuits, programmed processors, ASICs (Application Specific Integrated Circuits), FPGAs (Field-Programmable Gate Arrays), or combinations thereof. If the control units 21 and 31 are dedicated hardware, each function of each part may be implemented with separate hardware, or the functions of each part may be implemented together with a single piece of hardware.

[0138] Furthermore, some of the functions of each part may be implemented by dedicated hardware, while other parts may be implemented by software or firmware. In this way, the control units 21 and 31 can implement the above-mentioned functions by hardware, software, firmware, or a combination thereof.

[0139] By applying a program that defines the operation of the control units 21 and 31 to an existing computer such as a personal computer or information terminal device, it is also possible to make the computer function as an air conditioning control device.

[0140] Furthermore, the method of distribution of such programs is arbitrary. For example, they may be distributed on computer-readable storage media such as CD-ROMs (Compact Disk ROMs), DVDs (Digital Versatile Disks), MOs (Magneto Optical Disks), or memory cards, or they may be distributed via communication networks such as the Internet.

[0141] This disclosure allows for various embodiments and modifications without departing from its broad spirit and scope. Furthermore, the embodiments described above are for illustrative purposes only and do not limit the scope of this disclosure. That is, the scope of this disclosure is indicated by the claims, not by the embodiments. Various modifications made within the scope of the claims and the equivalent significance of the disclosure are considered to be within the scope of this disclosure. [Industrial applicability]

[0142] This disclosure is applicable to systems for estimating location. [Explanation of Symbols]

[0143] 1 Position estimation system, 5 Building, 10 Transmitter, 20 Wireless terminal, 21 Control unit, 22 Memory unit, 23 Operation unit, 24 Display unit, 25 Communication unit, 30 Management device, 31 Control unit, 32 Memory unit, 35 Communication unit, 211 Transmitter information acquisition unit, 212 Signal receiving unit, 213 Intensity information transmission unit, 214 Notification unit, 221 Intensity information, 311 Transmitter information transmission unit, 312 Intensity information acquisition unit, 313 Intensity identification unit, 314 Position estimation unit, 315 Output unit, 316 Learning unit, 321 Transmitter information, 322 Property information, 323 Trained model

Claims

1. A location estimation device for estimating the location of a wireless terminal, A strength determination means for determining a threshold strength, which is a received strength where the cumulative relative frequency of the received strength of a wireless signal periodically transmitted from a transmitter reaches a predetermined threshold at the wireless terminal, The system includes a position estimation means for estimating the position of the wireless terminal based on the threshold intensity determined by the intensity determination means and the position of the transmitter. Location estimation device.

2. The system further comprises strength information acquisition means for acquiring strength information indicating the received strength of wireless signals periodically transmitted from each of a plurality of transmitters at the wireless terminal, The intensity determination means determines the threshold intensity for each of the plurality of transmitters based on the intensity information obtained by the intensity information acquisition means. The position estimation means estimates the position of the wireless terminal based on the threshold intensity identified for each of the plurality of transmitters by the intensity identification means and the positions of the plurality of transmitters. The position estimation device according to claim 1.

3. The aforementioned multiple transmitters are installed in the building. The position estimation means estimates that the wireless terminal is not present in the building if all of the threshold intensities identified for each of the plurality of transmitters by the intensity identification means are smaller than the second threshold. The position estimation device according to claim 2.

4. The aforementioned multiple transmitters are installed in a building having multiple floors. The position estimation means estimates that the wireless terminal is located in the layer among the multiple layers in which the transmitter with the highest threshold strength among the multiple transmitters is located. The position estimation device according to claim 2 or 3.

5. The aforementioned multiple transmitters are installed in a building having multiple rooms. The position estimation means estimates that the wireless terminal is located in the room among the plurality of rooms where the transmitter with the highest threshold intensity among the plurality of transmitters is located. The position estimation device according to claim 2 or 3.

6. The position estimation means estimates that the wireless terminal is located at the position where the transmitter with the highest threshold intensity among the plurality of transmitters is located. The position estimation device according to claim 2 or 3.

7. The position estimation means is Based on the position of one of the plurality of transmitters, a range based on the threshold intensity identified for the one transmitter is set for each of the plurality of transmitters. It is presumed that the wireless terminal is located at a position where the ranges set for each of the aforementioned multiple transmitters overlap. The position estimation device according to claim 2 or 3.

8. The position estimation means is For each of the multiple candidate locations, a process is performed to compare the distance order, which is obtained by arranging the distances between one of the multiple candidate locations and each of the multiple transmitters in ascending order, with the intensity order, which is obtained by arranging the threshold intensity identified for each of the multiple transmitters in descending order. It is estimated that the wireless terminal is located at the candidate location among the multiple candidate locations where the distance order and the intensity order best match. The position estimation device according to claim 2 or 3.

9. The plurality of candidate positions are set based on the position of the wireless terminal last estimated by the position estimation means. The position estimation device according to claim 8.

10. The position estimation means estimates the position of the wireless terminal using a trained model for estimating the position of the wireless terminal from the threshold intensity identified for each of the plurality of transmitters by the intensity identification means. The position estimation device according to claim 2 or 3.

11. The system further comprises a learning unit that generates the trained model using machine learning, The position estimation device according to claim 10.

12. The position estimation means corrects the threshold intensity identified for at least one of the plurality of transmitters by the intensity identification means according to the location where the at least one transmitter is installed, and estimates the position of the wireless terminal based on the corrected threshold intensity. The position estimation device according to claim 2 or 3.

13. The aforementioned transmitter is installed in the building. The position estimation means estimates that the wireless terminal is not present in the building if the threshold intensity identified by the intensity identification means is smaller than the second threshold. The position estimation device according to claim 1.

14. The position estimation means estimates the position of the wireless terminal using a trained model for estimating the position of the wireless terminal from the threshold intensity identified by the intensity identification means. A position estimation device according to claim 1 or 13.

15. The system further comprises a learning unit that generates the trained model using machine learning, The position estimation device according to claim 14.

16. A location estimation system for estimating the location of a wireless terminal, A transmitter that periodically emits wireless signals, A strength determination means for determining a threshold strength, which is a received strength where the cumulative relative frequency of the received strength of the wireless signal periodically transmitted from the transmitter reaches a predetermined threshold at the wireless terminal, The system includes a position estimation means for estimating the position of the wireless terminal based on the threshold intensity determined by the intensity determination means and the position of the transmitter. Location estimation system.

17. A location estimation method for estimating the location of a wireless terminal, The cumulative relative frequency of the received intensity at the wireless terminal of the wireless signal periodically transmitted from the transmitter is calculated. A threshold intensity is identified, which is the received intensity at which the cumulative relative frequency reaches a predetermined threshold. Based on the identified threshold intensity and the position of the transmitter, the position of the wireless terminal is estimated. Location estimation method.

18. Computers, A means for identifying a threshold intensity, which is the received intensity at which the cumulative relative frequency of the received intensity of a radio signal periodically transmitted from a transmitter reaches a predetermined threshold at a radio terminal. Based on the threshold intensity identified by the intensity identification means and the position of the transmitter, the position estimation means is configured to estimate the position of the wireless terminal. program.

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