JP2020016458A - Position determining device and position determining system - Google Patents

Abstract

To alleviate arrangement restrictions on a receiver or a transmitter installed in a position determination system.SOLUTION: According to one aspect of the present invention, the position determining device includes receiving units, an estimating unit, and a determining unit. The receiving units are provided at first and second positions, respectively, and receive first and second received power data groups respectively representing received power in a plurality of first and second receivers from the plurality of first and second receivers that respectively receive radio signals transmitted by target transmitters. The estimating unit estimates the received power of the radio signals at the first and second positions based on the first and second received power data groups, and generates first and second estimated values, respectively. The determining unit uses the first and second estimated values and first and second thresholds to determine whether the target transmitter exists on a side closer to the second position than a line defined based on the first position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a position determination technique based on received power of a radio signal.

  In recent years, position detection of a BLE transmitter (also called a beacon) or a BLE receiver has been performed using BLE (Bluetooth Low Energy), which is one of the extended specifications of Bluetooth (registered trademark). For example, it is possible to determine which of the plurality of BLE receivers is closer to the BLE transmitter, based on the received power of the BLE signal (also called a beacon signal) transmitted by the BLE transmitter.

  Patent Literature 1 describes determining RSSI quality based on RSSI (Received Signal Strength Indication) and calculating directional characteristics D of a mobile terminal based on the RSSI quality. Also, in Patent Document 1, when the quality of RSSI is poor, the user of the mobile terminal is turning his / her back to the beacon node, and when the quality of RSSI is good, the user of the mobile terminal is facing the beacon node. There is also a description. Further, in Patent Document 1, RSSI is expressed as a function of environmental factors A and n and a distance between a mobile terminal and a beacon node. The larger the environmental factor [A, n], the worse the quality of RSSI becomes. There is also a description that the smaller [A, n], the better the quality of RSSI. Patent Literature 1 describes that mobile characteristic information including the directional characteristic D is extracted, and the mobile characteristic probability of the mobile terminal with respect to the restricted area is calculated based on the extracted mobile characteristic information.

  Patent Literature 2 describes that even when standing at the same position, the intensity of the received radio wave varies depending on the direction of the human body and the manner of holding the receiver. In addition, in Patent Document 2, the server 4 includes a plurality of ways of holding the receiver 3 by the person 10 of each receiver 3, or a way of holding the receiver 3 by the person 10 of each receiver 3, or It describes that the radio wave information corresponding to the combination of the directions of the receiver and the receiver 3 is appropriately selected and the position of the receiver 3 is specified.

JP-A-2017-37076 ([0052] to [0053], [0062], [0064] to [0065], [0072], [0096] to [0097]) JP-A-2017-201240 ([0007], [0043], [0062])

  When actually performing position determination using BLE, fading due to interference between a direct wave of a beacon signal and a reflected wave (for example, from the ground) becomes a problem. Specifically, when the propagation distance of the beacon signal increases, the difference between the measured RSSI value and the theoretical curve of the distance versus the RSSI increases due to the influence of multipath. Therefore, the distance between the transmitter and the receiver is estimated. Accuracy may be reduced. Furthermore, even if it is a theoretical curve, the change of RSSI with respect to the change of distance becomes small, so that it becomes difficult to estimate an accurate distance from RSSI as distance increases.

  In view of these problems, in order to achieve practical accuracy in the conventional position determination system, it is necessary to closely arrange the receivers or the transmitters close to each other at a distance of about 3 m or less. .

  Although Patent Documents 1 and 2 do not sufficiently explain how to specifically arrange beacon nodes and grids, similar restrictions are imposed in view of the fact that there is no mention of fading countermeasures. Is expected.

  Therefore, due to this placement restriction, for example, when a conventional position determination system is constructed on a road or the like in front of a facility entrance and exit, if a width of the road exceeds approximately 6 m, it is only necessary to install a receiver (or a transmitter) beside the road. When the transmitter (or the receiver) is located near the center of the road, it is difficult to determine the position with practical accuracy. Therefore, there may arise a problem that a receiver (or a transmitter) must be installed near the center of the road due to embedding work or an arch.

  An object of the present invention is to alleviate restrictions on the arrangement of a receiver or a transmitter installed in a position determination system.

  According to one aspect of the present invention, a position determining device includes a receiving unit, an estimating unit, and a determining unit. The receiving unit is: (a) receiving power of the wireless signal from the plurality of first receivers installed at the first position and receiving the wireless signal transmitted by the target transmitter from the plurality of first receivers; Receiving a first group of received power data representing a plurality of second receivers of the wireless signal from a plurality of second receivers located at a second location and receiving the wireless signal. Receiving the second received power data group representing the received power at the time. The estimating unit estimates a received power of the radio signal at the first position based on the first received power data group, generates a first estimated value, and generates a first estimated value based on the second received power data group. And estimating the received power of the radio signal at the second position to generate a second estimated value. The determination unit uses the first estimated value, the second estimated value, a first threshold value, and a second threshold value smaller than the first threshold value to set the target transmitter at the first position. It is determined whether or not the line exists on the side of the second position with respect to the line defined based on the second position.

  According to another aspect of the present invention, a position determining device includes a receiving unit, an estimating unit, and a determining unit. The receiving unit is: (a) receiving power of the wireless signal from the plurality of first receivers installed at the first position and receiving the wireless signal transmitted by the target transmitter from the plurality of first receivers; Receiving a first group of received power data representing a plurality of second receivers of the wireless signal from a plurality of second receivers located at a second location and receiving the wireless signal. Receiving a second received power data group representing the received power of the plurality of third receivers of the wireless signal from a plurality of third receivers installed at a third position and receiving the wireless signal. Receiving a third received power data group representing the received power at the receiver of (d), and (d) receiving the wireless signal from a plurality of fourth receivers installed at a fourth location and receiving the wireless signal. Fourth received power data representing the received power at the fourth receiver To receive the data group. The estimating unit estimates a received power of the radio signal at the first position based on the first received power data group, generates a first estimated value, and generates a first estimated value based on the second received power data group. Estimating the received power of the wireless signal at the second position to generate a second estimated value, and calculating the received power of the wireless signal at the third position based on the third received power data group. Estimating to generate a third estimated value, and estimating the received power of the radio signal at the fourth position based on the fourth received power data group to generate a fourth estimated value. The determining unit determines the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, a first threshold value, and a second threshold value smaller than the first threshold value. And determining whether the target transmitter is closer to the third position or the fourth position than a line defined based on the first position and the second position. I do.

  ADVANTAGE OF THE INVENTION According to this invention, arrangement | positioning restrictions of the receiver or transmitter installed in a position determination system can be eased.

FIG. 1 is a block diagram illustrating a position determination device according to an embodiment. The figure which illustrates the position determination system including the position determination apparatus of FIG. The figure which illustrates the beacon receiving device of FIG. 9 is a graph illustrating a temporal variation of received power in a beacon receiver. 7 is a graph illustrating a relationship between a distance from a beacon transmitter to a beacon receiver and received power. The figure which illustrates the electric wave shielding effect by a human body. FIG. 4 is an explanatory diagram of two thresholds used for beacon position determination. 7 is a graph illustrating a change in received power at each position before and after a user wearing a beacon transmitter passes a passage determination line. 3 is a flowchart illustrating the operation of the position determination device in FIG. 1. 10 is a flowchart illustrating details of step S410 in FIG. 9; 10 is a flowchart illustrating details of part of step S420 in FIG. 9. 10 is a flowchart illustrating details of the remainder of step S420 in FIG. 9. The figure which illustrates the change of the received power in each position before and after the user wearing the beacon transmitter passes the passage determination line, and the position determination result at each time.

  Hereinafter, an embodiment will be described with reference to the drawings. In the following, the same or similar elements as those already described are denoted by the same or similar reference numerals, and redundant description is basically omitted. For example, when there are a plurality of identical or similar elements, a common reference numeral may be used to describe each element without discrimination, and a common reference numeral may be used to distinguish and describe each element. In addition, branch numbers may be used.

(Embodiment)
The position determination device according to the embodiment can be incorporated in, for example, the position determination system shown in FIG. This position determination system includes the position determination device 100 according to the embodiment, and four beacon receiving devices 200-A1, 200-A2, 200-C1, and 200-C2. Each of the four beacon receiving devices 200 includes a plurality of beacon receivers as described later.

  The branch number (suffix) of the code of each beacon receiving device 200 indicates the installation position of the beacon receiving device 200. Further, the position A1 and the position A2 define a pass determination line described later, and the pass determination line may be defined as, for example, a straight line passing through the position A1 and the position A2.

  In the example of FIG. 2, the positions A1, A2, C1, and C2 are determined to correspond to the vertices of a rectangle having a width of 10 m and a depth of 5 m, respectively. That is, according to this position determination system, if the road is an outdoor road having a width of about 10 m, the beacon receiving device 200 does not need to be installed near the center of the road, and the beacon receiving device 200 only needs to be installed beside the road. The possibility of such an arrangement example is supported by the fact that the distance between the beacon transmitter and the beacon receiving device 200 can be estimated with high accuracy up to about 5 m in the present embodiment as described later. Can be

  The beacon transmitter is, for example, a nameplate-type device, and is worn by hanging the user 300 of the beacon transmitter on the neck or on the chest. In the following description, it is basically assumed that the beacon transmitter is worn on the front side of the user 300.

  Note that "beacon", "beacon transmitter", and "beacon receiver" are merely exemplary names. "Beacon" may be read as "wireless signal", "beacon transmitter" may be read as "wireless" transmitter "," beacon receiver (or receiver) "may be read as" (wireless) receiver (or receiver) "and so on. .

  With respect to the positions C1 and C2 on the basis of the passage determination line, taking out the beacon transmitter is prohibited. On the other hand, the side opposite to the positions C1 and C2 with respect to the passage determination line is an area in which the beacon transmitter is permitted to carry (hereinafter, referred to as a permitted area).

  The position determination device 100 is based on received power data from a plurality of beacon receivers included in each beacon reception device 200, at least whether or not the user 300 having the beacon transmitter has passed through the passage determination line. Specifically, it is determined whether or not the beacon transmitter exists on the position C1 or C2 side of the passage determination line.

  As illustrated in FIG. 3, the beacon receiving device 200 includes two beacon receivers 210-1 and 210-2, a pole 220, and a base 230. In the example of FIG. 3, since one beacon receiving device 200 includes two beacon receivers 210, if the beacon receiving devices 200 are installed at four locations, the position determination device 100 can receive eight beacons in total. Power data can be obtained from the communication device 210.

  The beacon receiver 210-1 and the beacon receiver 210-2 are attached to the pole 220 at an interval of at least half a wavelength of the beacon signal. With such a configuration and the later-described received power estimation processing in the position determination device 200, a spatial diversity effect can be obtained. Here, a half wavelength of the beacon signal corresponds to slightly more than 6 cm in the case of a BLE signal, for example.

  In the example of FIG. 3, the beacon receiver 210-1 and the beacon receiver 210-2 are attached to the pole 220 along the vertical direction, that is, along the vertical direction, at an interval of at least half a wavelength of the beacon signal. Have been. Such an arrangement example is suitable for an environment where fading occurs mainly due to interference between a direct wave of a beacon signal and a reflected wave mainly from the ground or the floor, such as outdoors.

  On the other hand, in an environment where reflected waves from a wall also exist, such as indoors, the beacon receiver 210-1 and the beacon receiver 210-2 are spaced apart in the horizontal direction, that is, in the direction perpendicular to the vertical direction, in addition to the vertical direction. It may be placed open. Alternatively, installing the beacon receiving device 200 near a wall is also effective in reducing fading caused by interference between a direct wave and a reflected wave from the wall.

  The number of beacon receivers 210 included in one beacon receiving device 200 may be three or more. For example, four beacon receivers 210 may be mounted on pole 220 such that one side corresponds to the apex of a square that is at least half a wavelength of the beacon signal.

  The beacon receiver 210 may include, for example, a BLE receiver and a Sub-GHz band communication device. Such a combination with the BLE receiver and the Sub-GHz band communication device is also referred to as BLE to Sub-GHz Gateway.

  The BLE receiver receives a BLE signal as a beacon signal and generates received power data, for example, RSSI data. Then, the BLE receiver sends the received power data to the Sub-GHz band communication device via the Host Controller Interface (HCI). Note that the received power data may include an identifier for identifying the BLE receiver and an identifier for identifying the beacon transmitter that is the transmission source of the beacon signal, in addition to the value of the received power, for example, data representing RSSI.

  The Sub-GHz band communication device, as a host, acquires reception power data from the BLE receiver via HCI. The Sub-GHz band communication device converts this into a radio signal for Sub-GHz band communication, and transmits it to the position determination device 100.

  The beacon receiver 210-1 and the beacon receiver 210-2 are attached to and supported by the pole 220. The base 230 supports the pole 220.

  As illustrated in FIG. 1, the position determination device 100 includes a reception unit 101, a reception power log storage unit 102, a reception power estimation unit 103, a position determination unit 104, and an alarm unit 105. The position determination device 100 may be a PC (Personal Computer) or another computer.

  The position determination device 100 may include, as hardware elements, for example, some or all of a processor, a memory, an auxiliary storage device, a communication interface, an input / output interface, an input device, an output device, and the like. Also, the respective hardware elements can be connected to each other via, for example, a bus.

  The processor realizes various processes described later by executing the program. The processor is typically a CPU (Central Processing Unit) and / or a GPU (Graphics Processing Unit), but may be a microcomputer, an FPGA (Field Programmable Gate Array), or a DSP (Digital Signal Processor). .

  The memory may temporarily store programs executed by the processor and data used by the processor. The memory may include a RAM (Random Access Memory) having a work area in which the program / data is expanded. The auxiliary storage device may be, for example, a hard disk drive (HDD), a solid state drive (SSD), or a flash memory.

  The communication interface is a module for communicating with an external device, for example, a plurality of beacon receivers included in the beacon receiving device 200, and includes a signal processing circuit for transmission / reception, an antenna, a LAN (Local Area Network) terminal, and the like. May be included. The communication interface may be, for example, a module for Sub-GHz wireless, a module for wireless LAN, a module for wide area communication such as mobile communication, or the like.

  The input / output interface is a USB (Universal Serial Bus) terminal or a terminal for another data transfer cable. The output device is a display, a speaker, or the like.

  The receiving unit 101 can be realized by the above-described communication interface. The receiving unit 101 receives a received power data group from a plurality of beacon receivers included in the beacon receiving device 200. The received power data group represents the received power of the beacon signal transmitted by the beacon transmitter at the plurality of beacon receivers.

  The reception power log storage unit 102 can be realized by the aforementioned memory and / or auxiliary storage device. The reception power log storage unit 102 stores the reception power data group acquired by the reception unit 101. The received power data group can be read by the received power estimating unit 103 as needed.

  Here, each of the received power data included in the received power data group includes, for example, an identifier for identifying a beacon receiver that is a source of the received power data and an identifier for identifying a beacon transmitter that is a transmission source of a beacon signal (or The identifier may be stored in the received power log storage unit 102 in association with the identifier of the user 300).

  The reception power estimation unit 103 can be realized by the above-described processor and memory. The reception power estimation unit 103 reads a reception power data group corresponding to each beacon receiving device 200 from the reception power log storage unit 102. Then, based on the read received power data group, received power estimating section 103 estimates the received power of the beacon signal at the installation position of beacon receiving device 200 to which beacon receiver 210 corresponding to the received power data group belongs. , And generates an estimate of the received power of the beacon signal at the location. When the beacon receiving devices 200 are installed at four locations as shown in FIG. 2, the received power estimating unit 103 generates four estimated values. Received power estimating section 103 sends an estimated value of the received power of the beacon signal at each position to position determining section 104.

Hereinafter, details of the processing performed by received power estimation section 103 will be described.
More specifically, for each position, the received power estimating unit 103 calculates, for each beacon receiver 210 of the beacon receiving device 200 installed at the position, The maximum value of the received power over the time point is searched, and an offset corresponding to the beacon receiver 210 is further added to calculate one of the candidate values of the received power of the beacon signal at the position. That is, received power estimation section 103 calculates a plurality of candidate values (candidate value group) for each position. Here, the offset is a correction value for absorbing a characteristic difference between the beacon receivers 210, and is determined for each beacon receiver 210.

  Even if the beacon receiver 210 is in a stationary state, the received power in the beacon receiver 210 fluctuates (fluctuates) over time as illustrated in FIG. Therefore, by searching for the maximum value of the received power over a period longer than one cycle of the fluctuation, the influence of the fluctuation of the received power in each beacon receiver 210 can be suppressed.

  Then, reception power estimation section 103 determines the maximum value of the candidate value group at each position as the estimated value of the reception power of the beacon signal at the position. In other words, the received power estimating unit 103 determines the maximum value of the candidate values calculated for the plurality of beacon receivers 210 included in each beacon receiving device 200 by receiving the beacon signal at the position where the beacon receiving device 200 is installed. Determined as the estimated value of the power.

  FIG. 5 shows theoretical curves of distance versus RSSI, actual measurement results of two beacon receivers 1 and 2 arranged similarly to beacon receivers 210-1 and 210-2, and these actual measurement results for each measurement point. The results obtained by connecting the maximum values are shown. The actual measurement results of the beacon receivers 1 and 2 are obtained by plotting the RSSIs of the beacon receivers 1 and 2 when transmitting a beacon signal every 1 m outdoors. In addition, since the actual measurement results of the beacon receivers 1 and 2 take the above-described measures against fluctuation, the influence of the fluctuation can be ignored.

  The theoretical curve of distance versus RSSI in free space can be determined by the Frisian transfer formula. However, in practice, this theoretical curve may not be valid at short distances as well as at long distances where the influence of multipath is great. For example, with respect to the receiver 1, the measured result at a distance of 3 m, which can be said to be a short distance, is about 4 dBm below the theoretical curve, and the estimated distance based only on the RSSI is about 5 m, which results in an error of about 2 m. On the other hand, for the receiver 2, although the measured result closer to the theoretical curve than the receiver 1 was obtained up to a distance of about 11 m, the measured result at the distance 12 m was about 10 dBm below the theoretical curve.

  As can be seen from FIG. 5, the beacon receivers 1 and 2 have different RSSI drop patterns. Therefore, fading can be reduced by employing the maximum value of the two as the estimated value of the received power (spatial diversity effect). As a result, a polygonal line connecting the maximum values of the actual measurement results in the beacon receivers 1 and 2 at each measurement point showed a result close to a theoretical curve until the distance was about 5 m. On the other hand, when the distance is in the range of 5 to 10 m, the influence of fading is partially observed, and when the distance is 10 m or more, it is only understood that the distance is 10 m or more.

  Therefore, the maximum value of the candidate values calculated for the plurality of beacon receivers 210 included in each beacon receiving device 200 is determined as the estimated value of the received power of the beacon signal at the position where the beacon receiving device 200 is installed. , The distance can be estimated with high accuracy up to about 5 m, and even if the distance is larger than 5 m, it is not possible to determine whether the distance is in the range of about 5 m to 10 m or 10 m or more. It is possible.

  The position determination unit 104 can be realized by the above-described processor and memory. The position determining unit 104 determines the position of the beacon transmitter using the estimated value of the received power of the beacon signal at each position, and a first threshold and a second threshold described below. For example, the position determination unit 104 may determine the position of the beacon transmitter from any of a plurality of labels including at least “outside the gate”, which means that the beacon transmitter is on the position C1 or position C2 side of the passage determination line. Is determined. The position determination unit 104 sends the determination result to the alarm unit 105.

  The first threshold may correspond to a reference value for determining whether the beacon transmitter is close to the beacon receiving device 200. As described above, in the present embodiment, since the distance can be estimated with high accuracy up to a distance of about 5 m, the proximity can be determined to be less than or equal to the distance of 5 m or a smaller upper limit. For example, assuming that the upper limit is 4 m in the example of FIG. 5, the first threshold can be determined to be about -58 dBm as illustrated in FIG.

  On the other hand, the second threshold value may correspond to a reference value for determining whether the distance between the beacon transmitter and the beacon receiving device 200 exceeds the detection limit distance. As described above, in the present embodiment, since it is only known that the distance is 10 m or more when the distance is 10 m or more, the detection limit distance can be set to 10 m or a smaller value. For example, assuming that the detection limit distance is 10 m in the example of FIG. 5, the second threshold value can be set to about −66 dBm as illustrated in FIG.

  Also, as described above, the beacon transmitter is worn on the front side of the user 300. Radio waves in the 2.4 GHz frequency band, such as BLE signals, have the property of being highly straight ahead and being easily absorbed by moisture. Since about 70% of the human body is water, the radio wave emitted from the beacon transmitter is absorbed by the body of the user 300 and hardly wraps around. Therefore, the transmission power of the beacon signal is greatly attenuated on the back side of the user 300 as illustrated in FIG. This attenuation exceeds 10 dBm. That is, before and after the user 300 passes the pass determination line, attenuation exceeding 10 dBm occurs at the position A1 and the position A2.

  FIG. 8 shows positions A1, A2, C1 and C1 until the user wearing the beacon transmitter passes through the pass determination line from the permission area and finally passes through the line connecting position C1 and position C2. The change of the received power in C2 is illustrated.

  According to FIG. 8, the received power at the positions A1 and A2 starts to decrease sharply from around the measurement count 33, while the received power at the positions C1 and C2 does not level or increases. This indicates that the user is about to pass the pass determination line. At this time, although the position A1 and the position A2 are actually close to the beacon transmitter, the received power at these positions is lower than the first threshold, and in some cases, the second threshold. .

  Also, from around the measurement count 49, the received power at the positions C1 and C2 also starts to decrease sharply. This implies that the user is finally going past the line connecting the position C1 and the position C2. At this time, although the position C1 and the position C2 are actually close to the beacon transmitter, the reception power at these positions is lower than the first threshold, and in some cases, the second threshold. .

The position determination unit 104 performs the position determination as described below using the drop in the received power due to the radio wave shielding effect of the human body.
(1) When the estimated value at the position A1 or the position A2 is equal to or greater than the first threshold, the beacon transmitter is close to the position A1 or the position A2, and the body of the user 300 is at the position A1 or the position A2. It is expected to be suitable for. If the estimated value at the position A1 is equal to or greater than the estimated value at the position C1, or if the estimated value at the position A2 is equal to or greater than the estimated value at the position C2, the beacon transmitter transmits the position A1 or the position to the position C1 or the position C2. Expected to be close to A2. Therefore, the position determination unit 104 determines the position of the beacon transmitter, for example, “on line”, which means that the beacon transmitter is near the pass determination line, or on the near side of the pass determination line, that is, in the permission area. It can be determined that “inside the gate” means to perform. Note that “on the line” and “in the gate” do not necessarily need to be distinguished from each other. For example, “on the line” may be integrated into “in the gate”. On the other hand, the position determination unit 104 determines that the estimated value at the position A1 is equal to or larger than the first threshold but smaller than the estimated value at the position C1, or the estimated value at the position A2 is equal to or larger than the first threshold but smaller than the estimated value at the position C2. In the case of, the position of the beacon transmitter, for example, means that the beacon transmitter has passed through the passage determination line, that is, that the beacon transmitter is located on the position C1 or position C2 side of the passage determination line. "Outside".

  (2) If both the estimated values at the position A1 and the position A2 are less than the first threshold and the estimated value at the position C1 or the position C2 is greater than or equal to the first threshold, the beacon transmitter determines the position. It is expected that the body of the user 300 is close to the position C1 or the position C2, and faces the position C1 or the position C2, in other words, the back of the user 300 is the position A1 or the position A2. Therefore, the position determination unit 104 can determine the position of the beacon transmitter as “out of gate”.

  (3) When the estimated values at the position A1, the position A2, the position C1, and the position C2 are all smaller than the second threshold, (a) the beacon transmitter is within the permission area, but the position from the beacon transmitter is Both the distance to A1 and the position A2 exceed the distance corresponding to the second threshold value, for example, 10 m. (B) The beacon transmitter is in the permitted area, but the user 300 is located behind the position A1 and the position A2. (C) the beacon transmitter is out of the permitted area, but the distances from the beacon transmitter to the position C1 and the position C2 both exceed the distance corresponding to the second threshold, for example, 10 m; (D) There is a possibility that the beacon transmitter is outside the permission area, but the user 300 is turning his back to the position C1 and the position C2. That is, when the estimated values at the position A1, the position A2, the position C1, and the position C2 are all smaller than the second threshold value, it is determined whether or not the beacon transmitter exists in the permission area from only the estimated values. It is not possible. Therefore, the position determination unit 104 can determine the position of the beacon transmitter as “out of service”, which means that the beacon transmitter is outside the range in which the position can be determined.

  Near the midpoint of the positions A1 and A2 and near the midpoint of the positions C1 and C2, the estimated values at these positions may be less than the first threshold and greater than or equal to the second threshold. Even in such a case, the position determination unit 104 can determine whether or not the beacon transmitter is in the permitted area.

  (4) The estimated value at the position A1 and the position A2 is less than the first threshold and not less than the second threshold, the estimated value at the position A1 is not less than the estimated value at the position C1, and the estimated value at the position A2 is If greater than or equal to the estimate at position C2, this means that the beacon transmitter is near the midpoint of position A1 and position A2, and that the body of user 300 is facing position A1 or position A2. I have. Therefore, the position determination unit 104 can determine the position of the beacon transmitter to be, for example, “in the gate”.

  (5) The estimated value at the position C1 and the position C2 is less than the first threshold and not less than the second threshold, the estimated value at the position C1 is not less than the estimated value at the position A1, and the estimated value at the position C2 is If greater than or equal to the estimate at position A2, the beacon transmitter is near the midpoint of position C1 and position C2, and the body of user 300 is facing position C1 or position C2, in other words, position This means that the player has turned his back to A1 and the position A2. Therefore, the position determination unit 104 can determine the position of the beacon transmitter as “out of gate”.

  The alarm unit 105 can be realized by a combination of the above-described processor and memory, a communication interface, an input / output interface, and / or an output device. The alarm unit 105 issues an alarm when the determination result from the position determination unit 104 is, for example, “out of gate” as described above. For example, the alarm unit 105 may display “taken away!”, “Beacon XX will be taken away!” (XX may be the name or identifier of the beacon transmitter, but may be omitted), “user □ □ will take off the beacon! ”(□□ may be the user's name or identifier, but may be omitted), etc., or may output such message data to the administrator. May be transmitted to the terminal.

Hereinafter, the operation of the position determination device 100 of FIG. 1 will be described with reference to FIG. The operation in FIG. 9 can be executed, for example, for each transmission cycle of a beacon signal.
First, the reception power estimation unit 103 reads the reception power data group from the reception power log storage unit 102, and estimates the reception power of the beacon signal at each position based on the data group (step S410). The details of step S410 will be described later with reference to FIG.

  Next, the position determination unit 104 determines the position of the target beacon based on the estimated value of the received power of the beacon signal at each position generated in step S410 and the first and second thresholds ( Step S420). The details of step S420 will be described later with reference to FIGS.

  If the determination result in step S420 is “out of gate”, the process proceeds to step S442; if the determination result in step S420 is not “out of gate”, the operation in FIG. 9 ends (step S441).

  In step S442, the warning unit 105 outputs a warning. Specifically, the alarm unit 105 may display a message or output a message, or may transmit such message data to a terminal of the administrator. After step S442, the operation in FIG. 9 ends.

Hereinafter, the details of step S410 will be described with reference to FIG. After the start of step S410, the process first proceeds to step S411.
In step S411, received power estimating section 103 selects any one of the unprocessed positions, and the process proceeds to step S412. According to the example of FIG. 2, the reception power estimating unit 103 sequentially selects one from the position A1, the position A2, the position C1, and the position C2 one by one, and calculates the reception power of the beacon signal at the selected position through steps S412 to S417. Will be estimated.

  In step S412, the reception power estimation unit 103 selects any one of the unprocessed beacon receivers 210 related to the selected position. According to the example of FIG. 3, the reception power estimating unit 103 sequentially selects one from the beacon receivers 210-1 and 210-2 included in the beacon receiving device 200 installed at the selected position, one by one. Through S413 to S415, one of the candidate values of the received power of the beacon signal at the selected position is calculated.

  The reception power estimation unit 103 extracts the four most recent RSSIs of the beacon receiver 210 selected in step S412 from the reception power data group (step S413). Then, received power estimation section 103 searches for the maximum value of the four RSSIs extracted in step S413 (step S414). Thereby, it is possible to suppress the influence of the fluctuation of the received power in the beacon receiver 210 selected in step S412.

  Further, received power estimation section 103 adds the offset corresponding to beacon receiver 210 selected in step S412 to the maximum RSSI searched in step S414, and calculates a candidate value corresponding to the beacon receiver 210 (step S415). Thereby, the characteristic difference between the beacon receivers 210 can be absorbed.

  After the end of step S415, the received power estimating unit 103 determines whether or not the unprocessed beacon receiver 210 remains at the selected position (step S416). If unprocessed beacon receivers 210 remain, the process returns to step S412. If all beacon receivers 210 have been processed for the selected position, the process proceeds to step S417. According to the example of FIG. 3, the number of the beacon receivers 210 for each position is two, so the determination result in step S416 is “Yes” and “No” in order.

  In step S417, the reception power estimating unit 103 estimates the maximum value of the candidate values for all the beacon receivers 210 related to the selected position as the reception power of the beacon signal at the selected position.

  After the end of step S417, the received power estimating unit 103 determines whether or not an unprocessed position remains (step S418). If unprocessed positions remain, the process returns to step S411, and if all positions have been processed, step S410 illustrated in FIG. 10 ends. According to the example of FIG. 2, the number of positions is four, and thus the determination result in step S418 is “Yes”, “Yes”, “Yes”, and “No” in order.

Hereinafter, the details of step S420 will be described with reference to FIGS.
First, the position determination unit 104 determines whether all of the estimated values at the position A1, the position A2, the position C1, and the position C2 are less than the second threshold Th2 (Step S421). If it is determined that all of the estimated values at the position A1, the position A2, the position C1, and the position C2 are smaller than the second threshold Th2, the process proceeds to step S422, and the position A1, the position A2, the position C1, and the position C2 If it is determined that at least one of the estimated values is equal to or greater than the second threshold Th2, the process proceeds to step S423.

  In step S422, the position determination unit 104 determines that the position of the beacon transmitter is "out of service", and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S423, the position determination unit 104 determines whether the estimated value at the position A1 or A2 is equal to or greater than the first threshold Th1. If it is determined that the estimated value at the position A1 or the position A2 is equal to or more than the first threshold Th1, the process proceeds to step S426, and it is determined that all the estimated values at the position A1 and the position A2 are less than the first threshold Th1. If so, the process proceeds to step S424.

  In step 424, the position determination unit 104 determines whether the estimated value at the position C1 or C2 is equal to or greater than the first threshold Th1. If it is determined that the estimated value at the position C1 or the position C2 is equal to or more than the first threshold Th1, the process proceeds to step S425, and it is determined that all the estimated values at the position C1 and the position C2 are less than the first threshold Th1. If so, the process proceeds to step S431 in FIG.

  In step S425, the position determination unit 104 determines that the position of the beacon transmitter is "out of gate", and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S426, the position determination unit 104 determines that the estimated value at the position A1 is equal to or greater than the first threshold Th1 and exceeds the estimated value at the position C1, and that the estimated value at the position A2 is equal to or greater than the first threshold Th. It is determined whether at least one of exceeding the estimated value at the position C2 is satisfied. If it is determined that at least one is satisfied, the process proceeds to step S427; otherwise, the process proceeds to step S428.

  In step S427, the position determination unit 104 determines that the position of the beacon transmitter is “in the gate”, and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S428, the estimated value at the position A1 is equal to or greater than the first threshold Th1 and substantially equal to the estimated value at the position C1, and the estimated value at the position A2 is equal to or greater than the first threshold Th1 and is equal to the estimated value at the position C2. It is determined whether at least one of approximately equal is satisfied. If it is determined that at least one is satisfied, the process proceeds to step S429; if it is determined that both are not satisfied, the process proceeds to step S430.

  In step S429, the position determination unit 104 determines that the position of the beacon transmitter is “on the line”, and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S430, the position determining unit 104 determines that the position of the beacon transmitter is “out of gate”, and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S431, the position determination unit 104 determines whether or not both that the estimated value at the position A1 exceeds the estimated value at the position C1 and that the estimated value at the position A2 exceeds the estimated value at the position C2. judge. If it is determined that both are satisfied, the process proceeds to step S432, and if it is determined that at least one is not satisfied, the process proceeds to step S434.

  In step S432, the position determining unit 104 determines whether or not the estimated values at the positions A1 and A2 are equal to or greater than the second threshold Th2. If it is determined that the estimated values at the position A1 and the position A2 are equal to or greater than the second threshold Th2, the process proceeds to step S433, and it is determined that the estimated value at the position A1 or the position A2 is less than the second threshold Th2. If so, the process proceeds to step S437.

  In step S433, the position determination unit 104 determines that the position of the beacon transmitter is “in the gate”, and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S434, the position determination unit 104 determines whether or not both that the estimated value at the position C1 exceeds the estimated value at the position A1 and that the estimated value at the position C2 exceeds the estimated value at the position A2. judge. If it is determined that both are satisfied, the process proceeds to step S435, and if it is determined that at least one is not satisfied, the process proceeds to step S437.

  In step S435, the position determination unit 104 determines whether or not the estimated values at the positions C1 and C2 are equal to or greater than the second threshold Th2. If it is determined that the estimated value at the position C1 and the position C2 is equal to or greater than the second threshold Th2, the process proceeds to step S436, and it is determined that the estimated value at the position C1 or the position C2 is less than the second threshold Th2. If so, the process proceeds to step S437.

  In step S436, the position determination unit 104 determines that the position of the beacon transmitter is "out of gate", and the step S420 illustrated in FIGS. 11 and 12 ends.

  In step S437, the position determination unit 104 determines that the position of the beacon transmitter is not “out of range” but “reserved”, which means that it cannot be concluded as either “in gate” or “out of gate”. Step S420 illustrated in FIGS. 11 and 12 ends.

  FIG. 13 shows positions A1, A2, C1 and C1 until the user wearing the beacon transmitter passes through the pass determination line from the permission area and finally passes through the line connecting position C1 and position C2. The change of the received power at C2 and the determination result of the position determination unit 104 at each time are shown. In the example of FIG. 13, the subject walks over a distance of slightly more than 10 meters for more than 5 minutes in order to collect data at many points and determine a position. In the example of FIG. 13, the first threshold value Th1 and the second threshold value Th2 are set to -58 dBm and -66 dBmm, respectively.

  For example, the estimated values of the received power (RSSI) of the beacon signal at the position A1, the position A2, the position C1, and the position C2 at “14:55:25” in FIG. 13 are “−59 dBm”, “−59 dBm”, "-62 dBm" and "-61 dBm". Therefore, the position determination unit 104 executes the processing in the order of step S421, step S423, step S424, step S431, step S432, and step S433, and obtains a determination result “in gate”.

  Also, the estimated values of the received power (RSSI) of the beacon signal at the position A1, the position A2, the position C1, and the position C2 at “14:57:02” in FIG. 13 are “−75 dBm”, “−70 dBm”, “−60 dBm” and “−55 dBm”. Therefore, the position determination unit 104 executes the processing in the order of step S421, step S423, step S424, and step S425, and obtains a determination result of "out of gate".

  As described above, the position determination device according to the embodiment estimates the received power in which the drop due to fading has been corrected for a plurality of positions with high accuracy by using the spatial diversity effect, and furthermore, these estimated values and two The position of the beacon transmitter is determined by performing a magnitude comparison using a threshold. Specifically, the position determination device, the beacon transmitter of the beacon transmitter by an algorithm utilizing the knowledge that the received power of the beacon receiving device immediately decreases due to the radio wave shielding effect of the human body immediately after the user has passed the beacon receiving device. Determine the position. Therefore, according to the position determination device, the accuracy of the position determination can be maintained even if the distance between the beacon receivers is set to be longer than in the related art. That is, it is possible to ease the restriction on the arrangement of the beacon receivers installed in the position determination system.

(Modification 1)
In the description of the embodiment, it is assumed that the user 300 wears the beacon transmitter, but on the contrary, the user 300 may wear the beacon receiver. In this case, it is necessary to replace the beacon receiver 210 with a beacon transmitter. The beacon receiver worn by the user 300 receives the beacon signals from the plurality of beacon transmitters, and transmits the received power data group to the position determination device 100.

(Modification 2)
In the example of FIG. 2 described above, a total of four beacon receivers 200 are installed to cover the passage determination line having a width of 10 meters. This arrangement example is suitable for an environment where it is difficult to install the beacon receiving device 200 at the center of the passage determination line such as a road. On the other hand, when such a restriction does not exist, a total of two beacon receiving devices 200 may be installed, for example, near the midpoint of the positions A1 and A2 and near the midpoint of the positions C1 and C2. Thereby, it is possible to cover the passage determination line of the same size as the example of FIG. 2 while suppressing the required number of the beacon receiving devices 200.

  In this modification, for example, the algorithm described with reference to FIGS. 11 and 12 needs to be modified. Specifically, “position A1” is read as “near the midpoint of position A1 and position A2”, and “position C1” is read as “near the midpoint of position C1 and position C2”, respectively, and “position A2” and “position The description about "C2" may be ignored.

  The above-described embodiments merely show specific examples to help understand the concept of the present invention, and are not intended to limit the scope of the present invention. In the embodiment, various components can be added, deleted, or changed without departing from the spirit of the present invention.

  In the above embodiments, some functional units have been described, but these are merely examples of implementation of each functional unit. For example, a plurality of functional units described as being mounted on one device may be mounted on a plurality of separate devices, or conversely, a description may be made on a plurality of separate devices. The function unit described above may be mounted on one device.

  The various functional units described in each of the above embodiments may be realized by using a circuit. The circuit may be a dedicated circuit for realizing a specific function or a general-purpose circuit such as a processor.

  At least a part of the processing of each of the above embodiments can also be realized by using, for example, a processor mounted on a general-purpose computer as basic hardware. A program for implementing the above processing may be provided by being stored in a computer-readable recording medium. The program is stored in a recording medium as a file in an installable format or a file in an executable format. The recording medium is a magnetic disk, an optical disk (CD-ROM, CD-R, DVD, etc.), a magneto-optical disk (MO, etc.), a semiconductor memory, or the like. The recording medium may be any as long as it can store a program and can be read by a computer. Further, a program for realizing the above processing may be stored on a computer (server) connected to a network such as the Internet, and downloaded to a computer (client) via the network.

Reference Signs List 100 position determining device 101 receiving unit 102 received power log storage unit 103 received power estimating unit 104 position determining unit 105 alarm unit 200 beacon receiving device 210: beacon receiver 220: pole 230: base 300: user

Claims (10)

(A) a plurality of first receivers installed at a first location and receiving a wireless signal transmitted by a target transmitter, the first power representing the received power of the wireless signal at the plurality of first receivers; (B) receiving power of the radio signal from the plurality of second receivers installed at the second position and receiving the radio signal from the plurality of second receivers; A receiving unit for receiving a second received power data group representing
A first estimated value is generated by estimating the reception power of the radio signal at the first position based on the first reception power data group, and the second estimation is performed based on the second reception power data group. An estimating unit for estimating the reception power of the radio signal at the position of and generating a second estimated value;
The target transmitter is defined based on the first location using the first estimate, the second estimate, a first threshold, and a second threshold that is less than the first threshold. A determination unit for determining whether or not the line exists on the side of the second position with respect to the second line.   When the first estimated value is less than the first threshold value and the second estimated value is equal to or more than the first threshold value, the determination unit determines that the target transmitter is higher than the line. The position determination device according to claim 1, wherein the position determination device determines that the position is present on the side of the second position.   The determination unit may be configured such that both the first estimated value and the second estimated value are less than the first threshold value, the second estimated value is equal to or greater than the first estimated value, and 3. The position determination device according to claim 1, wherein when the value is equal to or larger than a threshold value of 2, the target transmitter is determined to be closer to the second position than the line. 4. The estimating unit includes:
(A) searching for the maximum value of the received power over a plurality of time points for each of the plurality of first receivers from the first received power data group, and determining an offset corresponding to each of the plurality of first receivers; To calculate a first candidate value group, determine the maximum value in the first candidate value group as the first estimated value,
(B) searching the second received power data group for the maximum value of the received power over a plurality of points in time for each of the plurality of second receivers, and determining an offset corresponding to each of the plurality of second receivers; Is added to calculate a second candidate value group, and the maximum value in the second candidate value group is determined as the second estimated value.
The position determination device according to claim 1. A position determination device according to any one of claims 1 to 4,
Said plurality of first receivers;
A first support for supporting the plurality of first receivers;
Said plurality of second receivers;
A second support for supporting the plurality of second receivers,
The plurality of first receivers are installed on the first support at an interval of half a wavelength or more of the wireless signal from each other,
The plurality of second receivers are installed on the second support with an interval of at least half a wavelength of the radio signal from each other,
Position determination system. The plurality of first receivers are installed on the first support at an interval of at least half a wavelength of the wireless signal from each other along a vertical direction,
The plurality of first receivers are installed on the first support at an interval of half a wavelength or more of the wireless signal from each other along a vertical direction,
The position determination system according to claim 5.   The position determination system according to claim 5, wherein the target transmitter is worn on a front side of a user. (A) a plurality of first receivers installed at a first location and receiving a wireless signal transmitted by a target transmitter, the first power representing the received power of the wireless signal at the plurality of first receivers; (B) receiving power of the radio signal from the plurality of second receivers installed at the second position and receiving the radio signal from the plurality of second receivers; Receiving a second group of received power data representing the wireless signal from a plurality of third receivers located at a third location and receiving the wireless signal at the plurality of third receivers of the wireless signal; Receiving a third received power data group representing the received power; and (d) receiving the wireless signal from the fourth receivers located at a fourth location and receiving the wireless signal. A fourth received power data group representing received power at the receiver is received. A receiving unit that,
A first estimated value is generated by estimating the reception power of the radio signal at the first position based on the first reception power data group, and the second estimation is performed based on the second reception power data group. Estimating the received power of the wireless signal at the position of the second to generate a second estimated value, and estimating the received power of the wireless signal at the third position based on the third received power data group. An estimation unit that generates an estimated value of 3 and estimates the received power of the wireless signal at the fourth position based on the fourth received power data group to generate a fourth estimated value;
Using the first estimated value, the second estimated value, the third estimated value, the fourth estimated value, a first threshold value and a second threshold value smaller than the first threshold value, A determining unit that determines whether the target transmitter is located closer to the third position or the fourth position than a line defined based on the first position and the second position; A position determining device comprising: The first position has a largest distance from the fourth position among the second position, the third position, and the fourth position,
The second position has the largest distance from the third position among the first position, the third position, and the fourth position,
The determination unit may be configured such that both the first estimated value and the second estimated value are less than the first threshold, and at least one of the third estimated value and the fourth estimated value is If not less than a first threshold, it is determined that the target transmitter is located closer to the third position or the fourth position than the line.
The position determination device according to claim 8. The first position has a largest distance from the fourth position among the second position, the third position, and the fourth position,
The second position has the largest distance from the third position among the first position, the third position, and the fourth position,
The determination unit may be configured such that all of the first estimated value, the second estimated value, the third estimated value, and the fourth estimated value are below the first threshold value, and the third estimated value The first estimated value or more, the fourth estimated value is equal to or more than the second estimated value, and both the third estimated value and the fourth estimated value are the second estimated value. If not less than a threshold value, it is determined that the target transmitter is located closer to the third position or the fourth position than the line.
The position determination device according to claim 8.