JP2012032152A - Position detection system and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high detection precision by suppressing multipath effects without increasing hardware.SOLUTION: An arithmetic unit 30 includes a storage section 34 for sequentially storing received electric field strengths obtained in a reception terminal 20, and a position calculation section 35 for calculating a terminal position of a transmission terminal 10 on the basis of the received electric field strengths stored in the storage section 34. In the position calculation section 35, maximum received electric field strength in received electric field strengths obtained within a target period subjected to terminal position calculation is selected from among the received electric field strengths stored in the storage section 34 for each reception terminal 20, and the terminal position is calculated from the maximum received electric field strengths.

Description

  The present invention relates to a position detection technique, and more particularly to a technique for detecting the position of a transmission terminal based on reception statuses at a plurality of reception terminals regarding radio waves transmitted from the transmission terminal.

  As a method for detecting the position of a person or an object, there is a method in which a transmission terminal such as a wireless tag that emits radio waves is attached to the person or an object and the emission position of the radio waves is measured. Although there are a plurality of position detection methods using radio waves, a method using a received signal strength indication (RSSI) of a radio wave transmitted from a transmission terminal is generally used. The RSSI method calculates the position of a transmitting terminal based on the reception intensity of a direct wave that directly reaches the receiving terminal from the transmitting terminal among the radio waves transmitted from the transmitting terminal in a plurality of receiving terminals.

  In such a position detection method, the main cause of the position detection error is considered to be the influence of the multipath of the radio wave transmitted from the transmission terminal to the reception terminal. In particular, when radio waves are transmitted in a room, the radio waves are reflected in a complex manner by objects such as pillars and partitions arranged in the room, as well as walls and ceilings constituting the room, and a large number of multipaths are generated.

As a method for suppressing the influence of such multipath, a space diversity method is generally used (see, for example, Patent Document 1). In this method, a receiving terminal is provided with a plurality of antennas and switched to the antenna with the better radio wave propagation state. There is a method of selecting received data obtained by a receiving terminal having a better radio wave propagation state among terminals.
In addition, the same effect as described above can be obtained for a transmission diversity method in which a plurality of transmission terminals are used and a plurality of radio waves are transmitted instead of using multiple reception terminals.

JP 2008-224489 A

  However, in such a conventional technique, although the influence of multipath can be suppressed to some extent, hardware such as an antenna, a receiving terminal, or a transmitting terminal increases, so that the power consumption and cost of the entire position detection system increase. There was a point.

  This invention is for solving such a problem, and it aims at providing the position detection technique which can suppress the influence of multipath and can obtain high detection accuracy, without increasing hardware. Yes.

  In order to achieve such an object, a position detection system according to the present invention includes a transmission terminal that transmits radio waves at a constant transmission interval, and a plurality of reception electric field strengths received by receiving radio waves from the transmission terminals. A receiving terminal; a storage unit that sequentially stores received electric field strengths obtained by the receiving terminals; and a position calculating unit that calculates a terminal position of the transmitting terminal based on the received electric field strengths stored in the storing unit A receiving unit that calculates the maximum received electric field strength of the received electric field strength obtained during the target period for the terminal position calculation among the received electric field strengths stored in the storage unit by the position calculation unit. The terminal position is calculated from these maximum received electric field strengths.

  At this time, the computing device is further provided with a movement presence / absence determination unit that determines whether or not the transmission terminal moves during the target period, and the position calculation unit receives the maximum reception when the movement presence / absence determination unit determines that the transmission terminal does not move. If the terminal position is calculated based on the electric field strength and it is determined that there is a movement of the transmitting terminal, the terminal position is calculated based on the latest received electric field strength among the received electric field strengths stored in the storage unit. Also good.

  Moreover, you may further provide the target period change part which calculates the moving speed of the transmission terminal in a target period, and changes the length of a target period according to the obtained moving speed in an arithmetic unit.

  In addition, the transmitting terminal sequentially transmits the acceleration data measured by the acceleration sensor by radio waves, the receiving terminal receives the acceleration data by radio waves, the storage unit sequentially stores the acceleration data obtained by the receiving terminal, and moves The presence / absence determination unit calculates the moving distance of the transmission terminal in the target period from the acceleration data obtained in the target period among the acceleration data stored in the storage unit, and based on the obtained moving distance, the target You may make it determine the presence or absence of the movement of the transmission terminal in a period.

  In addition, the transmitting terminal sequentially transmits the acceleration data measured by the acceleration sensor by radio waves, the receiving terminal receives the acceleration data by radio waves, the storage unit sequentially stores the acceleration data obtained by the receiving terminal, and moves The presence / absence determining unit may determine whether or not the transmitting terminal has moved during the target period from the acceleration data obtained during the target period among the acceleration data stored in the storage unit.

  In addition, the transmitting terminal sequentially transmits the acceleration data measured by the acceleration sensor by radio waves, the receiving terminal receives the acceleration data by radio waves, and the storage unit sequentially stores the acceleration data obtained by the receiving terminal. The period changing unit may calculate the moving speed from the acceleration data obtained in the target period among the acceleration data stored in the storage unit.

  In addition, the transmission terminal sequentially stores acceleration data measured by the acceleration sensor, determines whether or not it is moving during the target period based on the acceleration data, and sequentially transmits determination data indicating the determination result by radio waves and receives it. The terminal receives the determination data by radio waves, the storage unit sequentially stores the determination data obtained by the receiving terminal, and the movement presence / absence determination unit stores the latest determination data among the determination data stored in the storage unit. Based on this, the presence / absence of movement of the transmission terminal may be determined.

  The position detection method according to the present invention includes a step in which a transmitting terminal transmits radio waves at a constant transmission interval, and a step in which a plurality of receiving terminals receive radio waves from the transmitting terminals and measure received electric field strength. The storage unit of the arithmetic device sequentially stores the received electric field strength obtained at the receiving terminal, and the position calculator of the arithmetic device calculates the terminal position of the transmitting terminal based on the received electric field strength stored in the storage unit. A position calculation step for calculating the received electric field strength of the received electric field strength obtained during the target period for the terminal position calculation among the received electric field strengths stored in the storage unit in the position calculation step. Is selected for each receiving terminal, and the terminal position is calculated from these maximum received electric field strengths.

  At this time, the movement presence / absence determination unit of the arithmetic device further includes a movement presence / absence determination step for determining whether or not the transmission terminal has moved in the target period. In this case, the terminal position is calculated based on the maximum received electric field strength, and when it is determined that there is a movement of the transmitting terminal, the terminal position is calculated based on the latest received electric field strength stored in the storage unit. You may make it calculate.

  The target period changing unit of the arithmetic device may further include a target period changing step of calculating the moving speed of the transmitting terminal in the target period and changing the length of the target period according to the obtained moving speed.

  According to the present invention, space diversity can be realized by using the received electric field strength measured in the past. Therefore, the influence of multipath can be reduced without adding hardware such as an antenna, a receiving terminal, or a transmitting terminal. It can suppress and can obtain high detection accuracy.

It is a block diagram which shows the structure of the position detection system concerning 1st Embodiment. It is an example of a structure of reception result data. It is a flowchart which shows the position calculation process in the arithmetic unit concerning 1st Embodiment. It is explanatory drawing which shows the operation example of the position calculation operation | movement concerning 1st Embodiment. It is explanatory drawing which shows the terminal arrangement | positioning at the time of 1st simulation. It is explanatory drawing which shows the displacement position of a transmission terminal. It is a reception electric field strength calculation result obtained by the 1st simulation. It is a graph which shows the simulation result of transmission terminal TX1. It is a position calculation result which shows the simulation result of transmission terminal TX1. It is a graph which shows the simulation result of transmission terminal TX2. It is a position calculation result which shows the simulation result of transmission terminal TX2. It is a graph which shows the simulation result of transmission terminal TX3. It is a position calculation result which shows the simulation result of transmission terminal TX3. It is explanatory drawing which shows the other terminal arrangement | positioning at the time of a 2nd simulation. This is the position coordinate of the human body. It is a reception electric field strength calculation result obtained by the 2nd simulation. It is explanatory drawing which shows the example of a position calculation operation | movement in 2nd simulation. It is a graph which shows the simulation result of transmission terminal TX4. It is a position calculation result which shows the simulation result of transmission terminal TX4. It is a block diagram which shows the structure of the position detection system concerning 2nd Embodiment. It is a flowchart which shows the position calculation process in the arithmetic unit concerning 2nd Embodiment. It is explanatory drawing which shows the operation example of the position calculation operation | movement concerning 2nd Embodiment. It is a block diagram which shows the structure of the position detection system concerning 3rd Embodiment. It is a flowchart which shows the target period change process in the arithmetic unit concerning 3rd Embodiment. It is a graph which shows an object period calculation model. It is explanatory drawing which shows the operation example of the position calculation operation | movement concerning 3rd Embodiment.

Next, embodiments of the present invention will be described with reference to the drawings.
[First Embodiment]
First, a position detection system 1 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a position detection system according to the first embodiment.

  The position detection system 1 receives a radio wave transmitted from a transmission terminal 10 that transmits a radio wave, and obtains a reception result such as a received signal strength indication (RSSI) related to the radio wave, and these A reception result obtained by the reception terminal 20 is received via the communication line 40, and the calculation device 30 is configured to detect the position of the transmission terminal 10 based on the reception result.

  In the present embodiment, a storage unit 34 that sequentially stores the received electric field strength obtained at the receiving terminal 20 in the arithmetic device 30, and a terminal of the transmitting terminal 10 based on the received electric field strength stored in the storage unit 34. A position calculation unit 35 for calculating the position. Of the received electric field strengths stored in the storage unit 34 by the position calculation unit 35, the received electric field strengths obtained during the target period for the terminal position calculation are calculated. The maximum received electric field strength is selected for each receiving terminal 20, and the terminal position is calculated from these maximum received electric field strengths.

[Configuration of sending terminal]
Next, the configuration of the transmission terminal 10 used in the position detection system according to the present embodiment will be described in detail with reference to FIG.
The transmission terminal 10 is composed of a general small wireless transmitter such as a wireless tag that emits radio waves as a whole, and is attached to a person or an object whose position is to be detected. The transmission terminal 10 is provided with a transmission control unit 11, a transmission unit 12, and an antenna 13 as main components.

  The transmission control unit 11 is composed of a dedicated control circuit, generates transmission data including its own transmission ID for identifying the transmission terminal 10 in accordance with the function of measuring a certain transmission interval and the arrival of transmission timing, A function of notifying the transmission unit 12.

The transmission unit 12 has a function of generating a transmission signal by modulating the transmission data at a carrier frequency such as 2.45 GHz in response to the transmission data notification from the transmission control unit 11 and outputting the transmission signal to the antenna 13. ing.
The antenna 13 has a function of transmitting a transmission signal from the transmission unit 12 as a radio wave.

[Receiver configuration]
Next, the configuration of the receiving terminal 20 used in the position detection system according to the present embodiment will be described in detail with reference to FIG.
The receiving terminal 20 includes a receiving device that receives radio waves as a whole, and is provided with an antenna 21, a receiving unit 22, and a communication processing unit 23 as main components.

The antenna 21 is an antenna that receives radio waves from the transmission terminal 10.
The receiving unit 22 demodulates the radio wave received by the antenna 21 and extracts the transmission ID of the transmission terminal 10, the function of measuring the received electric field strength of the received radio wave, and the radio wave from a clock circuit (not shown). And the function of acquiring the measurement time of the received electric field strength.
The communication processing unit 23 includes a communication circuit that performs data communication with the arithmetic device 30 via the communication line 40. The communication processing unit 23 uses the transmission ID, the received electric field strength, and the measurement time obtained by the receiving unit 22 to identify the receiving terminal. The reception result data to which the own reception ID is added is transmitted to the arithmetic unit 30.

[Configuration of arithmetic unit]
Next, with reference to FIG. 1, the structure of the arithmetic unit 30 used in the position detection system according to the present embodiment will be described in detail.
The arithmetic device 30 is composed of an information processing device such as a server or a personal computer as a whole, and includes a terminal control unit 31, an operation input unit 32, a screen display unit 33, a storage unit 34, and a position calculation unit 35 as main functional units. Is provided.

The terminal control unit 31 includes a communication circuit that performs data communication with each receiving terminal 20 via the communication line 40, and has a function of receiving reception result data transmitted from each receiving terminal 20. The operation input unit 32 includes an operation input device such as a keyboard and a mouse, and has a function of detecting an operation of the operator and outputting it to each functional unit.
The screen display unit 33 includes a screen display device such as an LCD, and has a function of displaying various information such as a reception result obtained by each receiving terminal 20 and a position of the transmitting terminal 10 on the screen.

The storage unit 34 includes a storage device such as a hard disk or a semiconductor memory. The storage unit 34 includes environmental data such as the arrangement position of each reception terminal 20 and reception result data such as reception field strength and transmission ID received from the reception terminal 20. 10 has a function of storing various processing information and programs used for position detection.
FIG. 2 is a configuration example of reception result data. Here, the reception ID, the measurement time, and the received electric field strength are registered as a set.

  The position calculation unit 35 is the maximum received electric field strength of the received electric field strength measured within the target period to be subjected to terminal position calculation based on the measurement time among the received electric field strengths of the same transmission ID stored in the storage unit 34. A function of selecting the intensity for each receiving terminal 20 and a function of calculating the position where the transmitting terminal 10 exists based on the selected maximum received electric field intensity, for example, based on a weighted average method.

  Among these functions of the arithmetic unit 30, the position calculation unit 35 has a microprocessor such as a CPU and its peripheral circuits, and executes various programs by executing programs read from the storage unit 34. Can be realized.

[Operation of First Embodiment]
Next, the operation of the position detection system according to the present embodiment will be described with reference to FIG. FIG. 3 is a flowchart illustrating position calculation processing in the arithmetic device according to the first embodiment.

The transmission terminal 10 transmits a radio wave including a transmission ID unique to itself at a certain transmission interval or when an arbitrary event occurs.
The receiving unit 22 of the receiving terminal 20 receives the radio wave from the transmitting terminal 10 via the antenna 21, demodulates the radio wave, extracts the transmission ID, measures the received electric field strength of the radio wave, and further measures the measurement. Get the time.

The communication processing unit 23 of the reception terminal 20 transmits reception result data in which the reception ID is added to the set of the transmission ID, the reception electric field strength, and the measurement time from the communication line 40 to the arithmetic device 30.
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34.

  The computing device 30 periodically executes the position calculation process of FIG. 3. First, the position calculation unit 35 selects a transmission ID in which reception result data from each receiving terminal 20 is prepared, and relates to the transmission ID. From the reception result data of each receiving terminal 20, the received electric field strength RSi (i is an integer of 1 or more: the number of the receiving terminal 20) measured during the target period Tc is acquired (step 100). This target period Tc has a certain length of time, and is set to a period that goes back to the past from the latest reception result data every time the reception result data in the storage unit 34 is updated.

Next, the position calculator 35 selects the maximum value, that is, the maximum received electric field strength RSimax for each receiving terminal RXi from the received electric field strength RSi within the acquired target period Tc (step 101).
Thereafter, the position of the transmitting terminal 10 having the transmission ID is calculated from the maximum received electric field strength RSimax for each selected receiving terminal RXi based on, for example, the weighted average method (step 102), and a series of position calculating processes is completed. To do.

As a specific example of the weighted average method, first, the corrected received electric field strength is obtained by subtracting and correcting the received gain Gi set in advance in the storage unit 34 for each receiving terminal 20 from the received electric field strength RSi. RSi ′ (= RSi−Gi) is calculated.
Subsequently, the obtained corrected received electric field strength RSi ′ is converted from the decibel value (dB) to the corrected received electric field strength Pi (= 10RSI ′ / 10) indicated by the true value (W).

Next, the reception intensity ratio Ri (= Pi / ΣPi) for the obtained corrected reception electric field intensity Pi is calculated.
Then, based on the received intensity ratio Ri and the coordinate positions Xi and Yi of the receiving terminal 20 preset in the storage unit 34, the coordinate positions X (= ΣXiRi) and Y (= ΣYiRi) of the transmitting terminal 10 are calculated. do it.

[Operation Example of First Embodiment]
Next, with reference to FIG. 4, an operation example of the position detection system according to the present embodiment will be described. FIG. 4 is an explanatory diagram illustrating an operation example of the position calculation operation according to the first embodiment.
Here, four receiving terminals RX1, RX2, RX3, RX4 are installed, and the received electric field strength RS is measured every time T1 to T5.

  Specifically, the receiving terminal RX1 measures RS11 to RS15 at times T1 to T5, the receiving terminal RX2 measures RS21 to RS25 at times T1 to T5, and the receiving terminal RX3 at times T1 to T5. RS31 to RS35 are measured, and at the receiving terminal RX4, RS41 to RS45 are measured at times T1 to T5. In particular, in FIG. 4, the magnitude of the received electric field strength is indicated by the size of a circle.

When the current time is T5 or later, the target period Tc is set to a period of a certain time length that goes back to the past from the latest received electric field intensity measured at time T5. In FIG. 4, the period of time T1 to T5 Is set to
Therefore, the position calculator 35 selects the maximum received electric field strength RSimax for each receiving terminal RXi among the received electric field strengths RS measured during the target period Tc at times T1 to T5.

Specifically, for the receiving terminal RX1, RS13 is selected as RS1max, for the receiving terminal RX2, RS21 is selected as RS2max, for the receiving terminal RX3, RS32 is selected as RS3max, and for the receiving terminal RX4, RS45 is selected as RS4max.
The position calculation unit 35 calculates the terminal position from the RS13, RS21, RS32, and RS45 selected in this way.

[First simulation result]
Next, a first simulation result of the position calculation method according to the present embodiment will be described with reference to FIGS. 5 and 6. FIG. 5 is an explanatory diagram showing a terminal arrangement during the first simulation. FIG. 6 is an explanatory diagram showing the displacement position of the transmission terminal.

When it is assumed that a person uses the transmission terminal 10 by carrying it, in the office or the like, even if the person is sitting on a chair, the person is not at all stationary and usually moves a little. For this reason, the position of the transmission terminal 10 is also displaced with time. For this reason, the occurrence state of multipath also changes, and there is a possibility that the received electric field strength may change greatly at the receiving terminal 20, which is considered to appear as a position detection error.
In the first simulation, it was simulated how the terminal position of the transmission terminal 10 obtained by calculation changes when the transmission terminal 10 is displaced.

  As shown in FIG. 5, in this simulation, a rectangular room 50 made of concrete and having a size of 14.8 m × 7.8 m × 3 m (X × Y × H) is used, and four receiving terminals RX1 are provided on the ceiling thereof. ˜RX4 is fixed, and the positions of the transmission terminals TX1 to TX3 are detected based on the received electric field intensity measured by these receiving terminals. The antennas 13 and 21 of the transmission terminal 10 and the reception terminal 20 are omnidirectional, the gain is 0 dBi, and the transmission power is 0 dBm. The coordinate positions of the transmission terminals TX1 to TX3 and the reception terminals RX1 to RX4 described in FIG.

  As shown in FIG. 6, the positions of the transmission terminals TX1 and TX2 were displaced to positions P1 to P9 that were shifted by 6 cm vertically and horizontally from the position P5. The heights of these positions P1 to P9 were set to 0.75 m corresponding to the height per person's waist. These displacements can be regarded as the displacement of the person sitting on the chair. The displacement distance 6 cm corresponds to λ / 2 of the carrier frequency of the radio wave from the transmission terminal 10, and the magnitude of the multipath phase shift generated in the room 50 is about this level. These displacements of the transmission terminal TX can also be regarded as movements of the transmission terminal TX with normal time passage. Further, the displacement distance of the transmission terminal TX3 was set to 2 cm instead of 6 cm.

Under such conditions, the transmission terminals TX1 to TX3 were respectively displaced, and the received electric field strengths at the reception terminals RX1 to RX4 were calculated by simulation. FIG. 7 is a calculation result of the received electric field intensity obtained in the first simulation.
Below, it verified about each of the transmission terminals TX1-TX3 about the difference in the position calculation method, and each error.

  First, referring to FIG. 8 and FIG. 9, the transmission terminal TX1 is verified. FIG. 8 is a graph showing a simulation result of the transmission terminal TX1. FIG. 9 is a position calculation result showing a simulation result of the transmission terminal TX1. 8 and 9, TX11 to TX19 indicate calculation positions when the transmission terminal TX1 is displaced to the positions P1 to P9 in FIG.

  Although the displacement of the transmission terminal TX1 is ± 6 cm in the X and Y directions, the calculation positions of the transmission terminals TX11 to TX19 are ± 1.5 m in the X and Y directions as shown in FIG. However, the displacement of the transmission terminal TX1 is expanded to about 25 times, but the direction of displacement and the direction of variation of the calculation position do not match. The distance from the true value may be very close to the true value as in TX13, but may be as much as 1.9m away as in TX17. As a whole, the average error with respect to the true value is 0. .56 m.

  On the other hand, according to the present method of calculating the terminal position by selecting the maximum received electric field strength from the received electric field strengths obtained in TX11 to TX19, for TX1 to RX4, TX12, TX17, The position calculation was performed by selecting the maximum received electric field strength of TX12 and TX13. As a result, the error from the true value is reduced to 0.35 m, and it can be seen that the error is reduced by 37.5% from the average error.

  Next, referring to FIG. 10 and FIG. 11, the transmission terminal TX2 is verified. FIG. 10 is a graph showing a simulation result of the transmission terminal TX2. FIG. 11 is a position calculation result showing a simulation result of the transmission terminal TX2. 10 and 11, TX21 to TX29 indicate calculation positions when the transmission terminal TX2 is displaced to the positions P1 to P9 in FIG.

  Although the displacement of the transmission terminal TX2 is ± 6 cm in the X and Y directions, the calculation positions of the transmission terminals TX21 to TX29 vary greatly as shown in FIG. Among them, the error when TX22 is closest to the true value is 0.61 m, and the error is as far as 2.11 m like TX21. As a whole, the average error with the true value is 0.80 m.

  On the other hand, according to the present method of calculating the terminal position by selecting the maximum received electric field strength from the received electric field strengths obtained in TX21 to TX29, TX29, TX26, The position calculation was performed by selecting the maximum received electric field strengths of TX28 and TX27. As a result, the error from the true value is reduced to 0.40 m, and it can be seen that the error is reduced by 50% from the error average.

  Finally, referring to FIG. 12 and FIG. 13, the transmission terminal TX3 is verified. FIG. 12 is a graph showing a simulation result of the transmission terminal TX3. FIG. 13 is a position calculation result showing a simulation result of the transmission terminal TX3. 12 and 13, TX31 to TX39 indicate calculation positions when the transmission terminal TX3 is displaced to the positions P1 to P9 in FIG.

  Although the displacement of the transmission terminal TX3 is ± 2 cm in the X and Y directions, the calculation positions of the transmission terminals TX31 to TX39 vary greatly as shown in FIG. Among these, some are very close to the true value as in TX36, but some are as far as 1.41m away as in TX38, and overall, the average error from the true value is 0.51m.

  On the other hand, according to the present method of calculating the terminal position by selecting the maximum received electric field strength from the received electric field strengths obtained in TX31 to TX39, for RX1 to RX4, TX39, TX31, The position calculation was performed by selecting the maximum received electric field strengths of TX39 and TX37. As a result, the error from the true value is reduced to 0.47 m, and it can be seen that the error is reduced by about 7.8% from the average error.

As described above, when the position of the transmission terminal 10 moves, the occurrence state of multipath changes, and the received electric field strength measured by the reception terminal 20 changes greatly. For example, in the case of the 2.45 GHz band, it is not uncommon for the received electric field strength to vary by 10 dB only when the position of the transmitting terminal 10 is different by 1 cm. It will be different.
According to this method, even if the transmission terminal 10 is displaced and the generation state of multipulses is changed from the simulation result described above, the position detection error is further reduced from the average error of the nine displacement positions. It can be seen that the influence of multipath in position detection is suppressed.

[Second simulation result]
Next, a second simulation result of the position calculation method according to the present embodiment will be described with reference to FIGS. 14 and 15. FIG. 14 is an explanatory diagram showing the terminal arrangement during the second simulation. FIG. 15 shows the position coordinates of the human body.
In the first simulation, the influence on the position calculation when the transmission terminal 10 is slightly displaced has been described. In the second simulation, the influence on the position calculation when the human body moves around the transmission terminal 10 will be described.

Even if the person to whom the transmission terminal 10 is attached does not move at all, in the office or the like, other people often appear around the person or other people pass around the person. In such a case, the state of the radio wave propagation space from the transmitting terminal 10 to the receiving terminal 20 may be changed by another person, and the received electric field strength measured by the receiving terminal 20 may change.
In the second simulation, simulation was performed on how the terminal position of the transmission terminal 10 obtained by calculation changes when the position of another person who does not have the transmission terminal 10 in the room changes.

As shown in FIG. 14, in this simulation, the same room 50 as in the first simulation is used, and the four receiving terminals RX1 to RX4 are fixed at the same positions as in the first simulation, and the transmitting terminal TX4 is connected to the first simulation. Fixed at the same position as the transmitting terminal TX3.
In addition, rectangular parallelepiped human bodies A1 to A9 having a size of 0.5 m × 0.3 m × 1.7 m (X × Y × H) were arranged at randomly selected positions in the room 50. As the material of these human bodies, “water” having close electrical characteristics was used.

  Under such conditions, any one of these human bodies A1 to A9 was selected, and the received electric field strengths at the receiving terminals RX1 to RX4 were calculated by simulation for each of the cases where the human body exists. FIG. 16 shows reception field strength calculation results obtained in the second simulation.

  FIG. 17 is an explanatory diagram illustrating an example of a position calculation operation in the second simulation. In the second simulation, it can be considered that the position of the transmission terminal TX4 is fixed and the human body position is moved every time T1 to T9. In the example of FIG. 17, four receiving terminals RX1, RX2, RX3, and RX4 are installed, and the received electric field strength RS is measured in a state where the human body position moves from A1 to A9 at each time T1 to T9. It will be.

  At each time T1 to T9, the result of calculating the position of the transmitting terminal TX using the received electric field strength RS measured by the receiving terminals RX1 to RX4 corresponds to TX41 to TX49 in FIGS. The values obtained are the average values in FIGS.

When the current time is T9 or later, the target period Tc is set to a period of a certain time length that goes back from the latest received electric field strength measured at time T9. In FIG. 17, the period of time T1 to T9 is set. Is set to
Therefore, the position calculation unit 35 selects the maximum received electric field strength RSimax for each receiving terminal RXi from the received electric field strengths RS measured during the target period Tc at times T1 to T9.

Specifically, for the receiving terminal RX1, RS14 is selected as RS1max, for the receiving terminal RX2, RS23 is selected as RS2max, for the receiving terminal RX3, RS39 is selected as RS3max, and for the receiving terminal RX4, RS49 is selected as RS4max.
The position calculation unit 35 calculates the terminal position from the RS14, RS23, RS39, and RS49 selected in this way.

  Next, with reference to FIG. 18 and FIG. 19, the difference in the position calculation method and each error were verified for each of the human bodies A1 to A9. FIG. 18 is a graph showing a simulation result of the transmission terminal TX4. FIG. 19 shows a position calculation result indicating a simulation result of the transmission terminal TX4.

  Even though the position of the transmission terminal TX4 is not displaced, there is a variation of about ± 30 to 40 cm in the position calculation result due to the influence of the movement of surrounding people. The distance from the true value may be close to the true value as in TX44, but may be as far as 1.2m as in TX41. As a whole, the average error from the true value is 0.98m. is there.

  On the other hand, according to the present method of calculating the terminal position by selecting the maximum received electric field strength from the received electric field strengths obtained in TX41 to TX49, TX44, TX43, The position calculation is performed by selecting the maximum received electric field strength of TX49 and TX49. As a result, the error from the true value is reduced to 0.73 m, and it can be seen that the error is reduced by 25.5% from the error average.

[Effect of the first embodiment]
As described above, according to the present embodiment, the storage unit 34 that sequentially stores the received electric field strength obtained by the receiving terminal 20 in the arithmetic device 30 and the transmission electric field strength that is stored in the storage unit 34 are transmitted. A position calculation unit 35 for calculating the terminal position of the terminal 10, and the position calculation unit 35 obtained within the target period for the terminal position calculation among the received electric field strengths stored in the storage unit 34. The maximum received electric field strength of the received electric field strength is selected for each receiving terminal 20, and the terminal position is calculated from these maximum received electric field strengths.

  As a result, space diversity can be realized using the received field strength measured in the past, so that the effects of multipath can be suppressed without adding hardware such as antennas, receiving terminals, or transmitting terminals. High detection accuracy can be obtained. In particular, as can be seen from the simulation results, even when the position of the transmission terminal 10 is slightly changed, or when a person moves around the transmission terminal 10, the position of the transmission terminal 10 is hardly changed. In an environment where the path generation situation changes greatly, the position calculation error can be greatly reduced.

[Second Embodiment]
Next, a position detection system 1 according to the second embodiment of the present invention will be described with reference to FIG. FIG. 20 is a block diagram showing a configuration of a position detection system according to the second embodiment, and the same or equivalent parts as those in FIG. 1 described above are denoted by the same reference numerals.

In the position calculation method of the first embodiment, when the position of the transmission terminal 10 does not change, or when the position of the transmission terminal 10 is displaced within a narrow range, that is, when a person is almost stationary such as sitting or standing However, when a person is moving by walking or the like, the position changes every moment, so that the deviation of the received electric field strength between the past and the present becomes large, and the above-described effect cannot be obtained.
In the present embodiment, a case will be described in which the presence or absence of movement of the transmission terminal 10 is determined, the present method is applied when there is no movement, and the terminal position is calculated from the latest received electric field strength when there is movement.

Compared with the first embodiment, in this embodiment, as shown in FIG. 20, a movement presence / absence determination unit 36 is added to the arithmetic unit 30 and an acceleration sensor 14 is added to the transmission terminal 10. ing.
The movement presence / absence determination unit 36 of the arithmetic device 30 has a function of determining whether or not the transmission terminal 10 has moved during the target period.
The position calculation unit 35 calculates the terminal position based on the maximum received electric field strength when the movement presence / absence determination unit 36 determines that the transmission terminal 10 has not moved, and when it is determined that the transmission terminal 10 has moved. The terminal unit is calculated based on the latest received electric field strength among the received electric field strengths stored in the storage unit 34.

The acceleration sensor 14 of the transmission terminal 10 includes a general acceleration sensor that measures acceleration, and has a function of measuring the acceleration applied to the transmission terminal 10 and outputting it to the transmission control unit 11.
Other configurations in the position detection system 1 according to the present embodiment are the same as those in the first embodiment, and a detailed description thereof is omitted here.

[Operation of Second Embodiment]
Next, the operation of the position detection system 1 according to the present embodiment will be described with reference to FIG. FIG. 21 is a flowchart showing the position calculation processing in the arithmetic device according to the second embodiment, and the same or equivalent parts as those in FIG. 3 are given the same reference numerals.

The transmission terminal 10 acquires acceleration data measured by the acceleration sensor 14 at a certain transmission interval or when an arbitrary event occurs, and transmits radio waves including the acceleration data and a transmission ID unique to itself.
The receiving unit 22 of the receiving terminal 20 receives the radio wave from the transmitting terminal 10 via the antenna 21, demodulates the radio wave, extracts the transmission ID and acceleration data, and measures the received electric field strength of the radio wave. Further, the measurement time is acquired.

The communication processing unit 23 of the reception terminal 20 transmits the reception result data in which the reception ID is added to the set of the transmission ID, acceleration data, received electric field strength, and measurement time from the communication line 40 to the arithmetic device 30. .
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34.

  The arithmetic unit 30 periodically executes the position calculation process of FIG. 21. First, the movement presence / absence determination unit 36 selects a transmission ID in which reception result data from each receiving terminal 20 is prepared, and the transmission ID The acceleration data AC received during the target period Tc is acquired from the reception result data of each receiving terminal 20 regarding (step 200), and the moving distance L or the moving speed of the transmitting terminal 10 during the target period Tc is obtained from these acceleration data AC. Determination element data consisting of V is calculated (step 201).

  In general, the moving distance L of the transmission terminal 10 can be obtained by second-order integration of the acceleration data AC. Further, the moving speed V of the transmission terminal 10 can be obtained by first-order integrating the acceleration data AC. At this time, the moving speed V obtained during the calculation of the second order integration when calculating the moving distance L in the second embodiment may be used. Since each receiving terminal 20 receives the same acceleration data from the transmitting terminal 10, the acceleration data received by any receiving terminal 20 may be used for calculating the moving distance L and the moving speed V.

Next, the movement presence / absence determination unit 36 compares the obtained movement distance L with a determination distance Lth preset in the storage unit 34 (step 202).
If the movement distance L is equal to or less than the determination distance Lth (step 202: YES), it is determined that the transmission terminal 10 has not moved in the target period Tc, and the position of the transmission terminal 10 is calculated based on the above-described method. . Regarding the value of the determination distance Lth, a calculation error of the terminal position when the position detection system 1 is used in each environment may be used. According to the simulation result to be described later, it was 1 to 2 m at a carrier frequency of 2.45 GHz.

  Hereinafter, a case where the movement distance L is used as the determination element data will be described as an example. However, when the movement speed V is used as the determination element data, the determination speed Vth may be used instead of the determination distance Lth. In this case, for example, if the moving speed V in a specific direction such as horizontal or vertical is higher than the determination speed Vth, it may be determined that there is movement. At this time, the moving speed V after statistical processing such as an average value of a plurality of moving speeds V may be compared with the determination speed Vth in consideration of errors and variations. As the value of the determination speed Vth, a value obtained by dividing the determination distance Lth by the acceleration data acquisition interval may be used.

Thus, when it is determined that there is no movement of the transmission terminal 10 in the target period Tc, the position calculation unit 35 measures the reception result data of each reception terminal 20 related to the transmission ID within the target period Tc. Received field strength RSi (i is an integer of 1 or more: number of receiving terminal 20) is acquired (step 100).
Next, the position calculator 35 selects the maximum value, that is, the maximum received electric field strength RSimax for each receiving terminal RXi from the received electric field strength RSi within the acquired target period Tc (step 101).
Thereafter, the position of the transmitting terminal 10 having the transmission ID is calculated from the maximum received electric field strength RSimax for each selected receiving terminal RXi based on, for example, the weighted average method (step 102), and a series of position calculating processes is completed. To do.

On the other hand, when the moving distance L is larger than the determination distance Lth in step 202 (step 202: YES), it is determined that the transmitting terminal 10 has moved in the target period Tc.
In this case, the position calculation unit 35 acquires the latest received electric field strength RSinew measured latest from the reception result data of each receiving terminal 20 related to the transmission ID (step 203), and from the latest received electric field strength RSinew, For example, based on the weighted average method, the position of the transmission terminal 10 having the transmission ID is calculated (step 204), and a series of position calculation processing is terminated.

[Operation Example of Second Embodiment]
Next, an operation example of the position detection system according to the present embodiment will be described with reference to FIG. FIG. 22 is an explanatory diagram of an example of the position calculation operation according to the second embodiment.
Here, four receiving terminals RX1, RX2, RX3, RX4 are installed, and the received electric field strength RS is measured every time T1 to T5.

  Specifically, the receiving terminal RX1 measures RS11 to RS15 at times T1 to T5, the receiving terminal RX2 measures RS21 to RS25 at times T1 to T5, and the receiving terminal RX3 at times T1 to T5. RS31 to RS35 are measured, and at the receiving terminal RX4, RS41 to RS45 are measured at times T1 to T5. In particular, in FIG. 22, the magnitude of the received electric field strength is indicated by the size of a circle.

In addition, acceleration data is measured at the transmission terminal TX1 and transmitted to the reception terminals RX1 to RX4, and acceleration data AC1 to AC5 are received at times T1 to T5.
When the current time is T5 or later, the target period Tc is set to a period of a certain time length that goes back to the past from the latest received electric field strength measured at time T5. In FIG. 22, the period is set to times T1 to T5. Has been.

Therefore, the movement presence / absence determination unit 36 calculates the movement distance L of the transmission terminal TX1 in the target period Tc based on the acceleration data AC1 to AC5 received in the target period Tc at times T1 to T5, and determines the determination distance Lth. Compare.
Here, in the case of L ≦ Lth, the movement presence / absence determination unit 36 determines that the transmission terminal TX1 does not move during the target period Tc, and the position calculation unit 35 receives the reception measured within the target period Tc at times T1 to T5. Among the field strengths RS, the maximum reception field strength RSimax is selected for each reception terminal RXi.

Specifically, for the receiving terminal RX1, RS13 is selected as RS1max, for the receiving terminal RX2, RS21 is selected as RS2max, for the receiving terminal RX3, RS32 is selected as RS3max, and for the receiving terminal RX4, RS45 is selected as RS4max.
The position calculation unit 35 calculates the terminal position from the RS13, RS21, RS32, and RS45 selected in this way.

  On the other hand, when L> Lth, the movement presence / absence determination unit 36 determines that the transmission terminal TX1 has moved during the target period Tc, and the position calculation unit 35 calculates the latest received electric field strength RSinew measured at time T5, that is, RS15, The terminal position is calculated from RS25, RS35, and RS45.

[Effect of the second embodiment]
Thus, in the present embodiment, when calculating the position of the transmission terminal 10, the maximum received electric field strength RSimax selected from the target period Tc is used according to whether the transmission terminal 10 has moved, or the latest received electric field strength is used. Since the selection of whether to use RSINEW, when the transmitting terminal 10 is stopped, the terminal position can be calculated with high accuracy based on the received electric field strength measured in the past, and the transmitting terminal 10 starts moving. In this case, the latest terminal position can be calculated without being influenced by the past received electric field strength.

  In the present embodiment, the transmission terminal 10 sequentially transmits the acceleration data measured at the transmission interval by the acceleration sensor 14 by radio waves, and the reception terminal 20 receives the acceleration data by the radio waves. 34, the acceleration data obtained at the receiving terminal 20 is sequentially stored. Based on the acceleration data obtained during the target period Tc among the acceleration data stored in the storage unit 34 by the movement presence / absence determination unit 36, Since the presence / absence of movement of the transmission terminal 10 in the target period Tc is determined, the presence / absence of movement of the transmission terminal 10 can be accurately determined.

  In the present embodiment, the movement presence / absence determination unit 36 of the arithmetic device 30 calculates determination element data including the movement distance L or the movement speed V of the transmission terminal 10 from the acceleration data obtained from the transmission terminal 10. Although the case where the presence / absence of movement of the transmission terminal 10 is determined based on the determination element data has been described as an example, the presence / absence of movement of the transmission terminal 10 may be determined using the acceleration data itself obtained from the transmission terminal 10.

  In this case, in the movement presence / absence determination unit 36, the acceleration data received during the target period Tc is acquired from the reception result data of each receiving terminal 20 regarding the transmission ID, and the acceleration data in a specific direction is acquired from these acceleration data. If the acceleration data AC is larger than the determination acceleration ACth, it may be determined that there is movement. At this time, in consideration of errors and variations, the acceleration data AC after statistical processing such as an average value of a plurality of acceleration data AC may be compared with the determination acceleration ACth. As the value of the determination acceleration ACth, a value obtained by dividing the determination speed Vth by the acceleration data acquisition interval, that is, a value obtained by dividing the determination distance Lth by the acceleration data acquisition interval twice may be used. As a result, the processing burden and required time for calculating the determination element data can be saved.

[Third Embodiment]
Next, a position detection system according to a third embodiment of the present invention will be described with reference to FIG. FIG. 23 is a block diagram showing a configuration of a position detection system according to the third embodiment, and the same or equivalent parts as those in FIG. 1 described above are denoted by the same reference numerals.

  In the first and second embodiments, the case where the target period Tc for selecting the maximum received electric field strength RSimax from the received electric field strengths measured in the past is set to a certain length has been described as an example. This Embodiment demonstrates the case where the period length of the object period Tc is changed according to the moving speed of the transmission terminal 10. FIG.

Compared to the first embodiment, in the present embodiment, as shown in FIG. 23, the target period changing unit 37 is added to the arithmetic unit 30 and the acceleration sensor 14 is added to the transmission terminal 10. ing.
The target period changing unit 37 of the arithmetic device 30 has a function of changing the period length of the target period Tc.
The position calculation unit 35 calculates the terminal position based on the maximum received electric field strength when the movement presence / absence determination unit 36 determines that the transmission terminal 10 has not moved, and when it is determined that the transmission terminal 10 has moved. The terminal unit is calculated based on the latest received electric field strength among the received electric field strengths stored in the storage unit 34.

The acceleration sensor 14 of the transmission terminal 10 includes a general acceleration sensor that measures acceleration, and has a function of measuring the acceleration applied to the transmission terminal 10 and outputting it to the transmission control unit 11.
Other configurations in the position detection system 1 according to the present embodiment are the same as those in the first embodiment, and a detailed description thereof is omitted here.

[Operation of Third Embodiment]
Next, with reference to FIG. 24, operation | movement of the position detection system 1 concerning this Embodiment is demonstrated. FIG. 24 is a flowchart illustrating the target period changing process in the arithmetic device according to the third embodiment.

The transmission terminal 10 acquires acceleration data measured by the acceleration sensor 14 at a certain transmission interval or when an arbitrary event occurs, and transmits radio waves including the acceleration data and a transmission ID unique to itself.
The receiving unit 22 of the receiving terminal 20 receives the radio wave from the transmitting terminal 10 via the antenna 21, demodulates the radio wave, extracts the transmission ID and acceleration data, and measures the received electric field strength of the radio wave. Further, the measurement time is acquired.

The communication processing unit 23 of the reception terminal 20 transmits the reception result data in which the reception ID is added to the set of the transmission ID, acceleration data, received electric field strength, and measurement time from the communication line 40 to the arithmetic device 30. .
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34.

  The arithmetic unit 30 periodically executes the target period changing process of FIG. 24. First, the target period changing unit 37 selects a transmission ID in which the reception result data from each receiving terminal 20 is prepared, and the transmission The acceleration data AC received during the target period Tc is acquired from the reception result data of each receiving terminal 20 regarding the ID (step 300), and the moving speed V of the transmitting terminal 10 during the target period Tc is calculated from the acceleration data AC. (Step 301).

  In general, the moving speed V of the transmission terminal 10 can be obtained by first-order integrating acceleration data AC. At this time, the moving speed V obtained during the calculation of the second order integration when calculating the moving distance L in the second embodiment may be used. Since each receiving terminal 20 receives the same acceleration data from the transmitting terminal 10, the acceleration data received by any receiving terminal 20 may be used for calculating the moving speed V.

  Next, the target period changing unit 37 sets the new target period Tc ′ corresponding to the obtained moving speed V of the transmission terminal 10 as the target period calculation model registered in the storage unit 34 in advance, for example, the moving speed V. Calculation is made with reference to a function or table showing the relationship with the target period Tc (step 302).

  FIG. 25 is a graph showing a target period calculation model. As the moving speed V of the transmission terminal 10 increases, the past position of the transmission terminal 10 deviates greatly from the latest position, and the contribution ratio of the past received electric field strength to the calculation of the latest position of the transmission terminal 10 tends to decrease. It is believed that there is. For this reason, the moving speed V and the target period length Tc can be shown as an inversely proportional graph as shown in FIG. For the function or table showing this graph, the relationship between the terminal speed can be calculated within a certain error range by experimentally changing the moving speed V and the target period length Tc in advance.

Thereafter, the target period changing unit 37 changes the original target period Tc to a new target period Tc ′ (step 303), and ends a series of target period changing processes.
Thereby, the target period Tc ′ after the change is used in the subsequent position calculation process and target period change process.

[Operation Example of Third Embodiment]
Next, with reference to FIG. 26, an operation example of the position detection system according to the present embodiment will be described. FIG. 26 is an explanatory diagram of an operation example of the position calculation operation according to the third embodiment.
Here, four receiving terminals RX1, RX2, RX3, RX4 are installed, and the received electric field strength RS is measured every time T1 to T5.

  Specifically, the receiving terminal RX1 measures RS11 to RS15 at times T1 to T5, the receiving terminal RX2 measures RS21 to RS25 at times T1 to T5, and the receiving terminal RX3 at times T1 to T5. RS31 to RS35 are measured, and at the receiving terminal RX4, RS41 to RS45 are measured at times T1 to T5. In particular, in FIG. 26, the magnitude of the received electric field strength is indicated by the size of a circle.

In addition, acceleration data is measured at the transmission terminal TX1 and transmitted to the reception terminals RX1 to RX4, and acceleration data AC1 to AC5 are received at times T1 to T5.
When the current time is after T5, the target period Tc before the change is set at times T1 to T5.
Therefore, the target period changing unit 37 calculates the moving speed V of the transmission terminal TX1 in the target period Tc based on the acceleration data AC1 to AC5 received in the target period Tc at times T1 to T5, and creates a new target period. The length is changed to Tc ′. Here, when the moving speed V increases, the time T3 to T5, which is shorter than the original target period Tc, becomes the target period Tc ′.

Thereby, after that, the position calculation unit 35 selects the maximum received electric field strength RSimax for each receiving terminal RXi from the received electric field strengths RS measured within the target period Tc between times T3 and T5.
Specifically, for the receiving terminal RX1, RS13 is selected as RS1max, for the receiving terminal RX2, RS24 is selected as RS2max, for the receiving terminal RX3, RS34 is selected as RS3max, and for the receiving terminal RX4, RS45 is selected as RS4max.
The position calculation unit 35 calculates the terminal position from the RS13, RS24, RS34, and RS45 selected in this way.

[Fourth Embodiment]
Next, a position detection system according to a fourth embodiment of the present invention will be described.
In the second embodiment, the calculation device 30 calculates the movement distance L of the transmission terminal 10 based on the acceleration data notified from the transmission terminal 10, and based on the movement distance L, the presence / absence of movement of the transmission terminal 10 is determined. The case of determination has been described as an example.
In the present embodiment, the transmission terminal 10 measures acceleration data, calculates the determination element data consisting of the movement distance L or the movement speed V, and transmits the calculation apparatus 30 based on the determination element data notified from the transmission terminal 10. A case where it is determined whether or not the terminal 10 has moved will be described.

  The configuration of the position detection system 1 according to the present embodiment is the same as that shown in FIG. Further, the position calculation process of the position detection system 1 according to the present embodiment is the same as that in FIG. 21 described above, but a process equivalent to step 200 and step 201 is executed in the transmission terminal 10.

  That is, in the transmission control unit 11 of the transmission terminal 10, the acceleration data measured by the acceleration sensor 14 is held for the target period, and the movement distance L or the movement speed V in the target period Tc from the past data for the target period Tc. Is determined, and a radio wave including the determination element data and a transmission ID unique to itself is transmitted.

The communication processing unit 23 of the reception terminal 20 transmits reception result data in which the reception ID is added to the set of the transmission ID, the moving distance L, the reception electric field strength, and the measurement time from the communication line 40 to the arithmetic device 30. To do.
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34.
Thereafter, the movement presence / absence determination unit 36 acquires the determination element data from the reception result data in the storage unit 34 and determines whether the transmission terminal 10 is moving. For this determination method, the same method as in the second embodiment described above may be used.

[Effect of the fourth embodiment]
As described above, according to the present embodiment, the transmission terminal 10 calculates the determination element data including the movement distance L or the movement speed V, and the calculation device 30 transmits the determination element data based on the determination element data notified from the transmission terminal 10. Therefore, it is possible to calculate the movement distance L or the movement speed V more accurately. Usually, since the transmission interval of radio waves is in units of seconds in order to suppress power consumption of the transmission terminal 10, a certain amount of error is included in the movement distance calculated from the acceleration data obtained at this transmission interval. According to the present embodiment, since the acceleration data can be acquired and the movement distance L can be calculated at a cycle shorter than the transmission interval, the movement distance L can be calculated more accurately. Therefore, the presence or absence of movement can be accurately determined, and as a result, the position detection accuracy can be improved.

  Further, in the present embodiment, as an example of the case where the transmission terminal 10 calculates the movement distance from the acceleration data and notifies the calculation device 30 of the determination element data used for determining whether the calculation device 30 moves or not, the calculation device 30 is notified. However, the present invention is not limited to this. For example, as the determination element data, the transmission terminal 10 may calculate the movement speed from the acceleration data and notify the calculation device 30 of the movement speed. The same effect as the case of notifying the moving distance can be obtained.

[Fifth Embodiment]
Next, a position detection system according to a fifth embodiment of the present invention will be described.
In the fourth embodiment, determination element data consisting of the movement distance L or movement speed V is calculated by the transmission terminal 10 and transmitted by radio waves, and based on the determination element data notified from the transmission terminal 10 by the arithmetic device 30. The case where the presence / absence of movement of the transmission terminal 10 is determined as an example. In the present embodiment, a case will be described in which acceleration data is measured by the transmission terminal 10, the presence / absence of movement of the transmission terminal 10 itself is determined, and the determination result is transmitted by radio waves.

  The configuration of the position detection system 1 according to the present embodiment is the same as that shown in FIG. Further, the position calculation process of the position detection system 1 according to the present embodiment is the same as that in FIG. 21 described above, but a process equivalent to steps 200 to 202 is executed by the transmission terminal 10.

  That is, the transmission control unit 11 of the transmission terminal 10 holds acceleration data measured by the acceleration sensor 14 for the target period Tc, acquires acceleration data for the target period Tc (step 200), and sets the target period. The travel distance L is calculated as the determination element data of the transmitting terminal 10 at Tc (step 201). Thereafter, the transmission control unit 11 determines whether or not the transmission terminal 10 has moved by comparing the obtained movement distance L with the determination distance Lth (step 202), and the obtained movement presence / absence determination data and its own The radio wave including the transmission ID is transmitted.

  At this time, instead of the movement distance L and the determination distance Lth, the movement speed V and the determination speed Vth may be used. The calculation method of the movement distance L and the movement speed V and the values of the determination distance Lth and the determination speed Vth are the same as those in the second embodiment, and a description thereof is omitted here.

The communication processing unit 23 of the receiving terminal 20 sends the reception result data obtained by adding its own reception ID to the set of these transmission ID, movement presence / absence determination data, reception electric field strength, and measurement time from the communication line 40 to the arithmetic device 30. Send.
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34. Thereafter, the movement presence / absence determination unit 36 acquires movement presence / absence determination data from the reception result data in the storage unit 34 and performs the movement presence / absence determination of the transmission terminal 10.
Thereby, the determination process in the movement presence determination part 36 of the arithmetic unit 30 can be simplified.

[Effect of Fifth Embodiment]
As described above, in the present embodiment, the transmission terminal 10 determines whether or not there is movement, and the arithmetic device 30 determines whether or not the transmission terminal 10 moves based on the movement presence / absence determination data notified from the transmission terminal 10. Therefore, the presence / absence of movement of the transmission terminal 10 can be accurately determined, and as a result, the position detection accuracy can be improved.

  Usually, the interval at which radio waves are transmitted from the transmission terminal 10 to the computing device 30 is longer than the detection interval of acceleration data in order to suppress power consumption at the transmission terminal 10, and the amount of data transmitted from the transmission terminal 10 is also large. Limited. On the other hand, the transmission terminal 10 can process a lot of acceleration data at short intervals. For this reason, compared with the case where the calculation device 30 determines whether or not the transmission terminal 10 has moved, it is possible to accurately determine whether or not the transmission terminal 10 has moved, and as a result, the position detection accuracy can be improved.

  In the present embodiment, the transmission control unit 11 of the transmission terminal 10 calculates determination element data including the movement distance L or the movement speed V of the transmission terminal 10 from the acceleration data measured by the acceleration sensor 14, and this determination is performed. Although the case where the presence / absence of movement of the transmission terminal 10 is determined based on element data has been described as an example, the presence / absence of movement of the transmission terminal 10 may be determined using the acceleration data itself.

  In this case, the transmission control unit 11 may determine that there is movement if the acceleration data AC in a specific direction among the obtained acceleration data is larger than the determination acceleration ACth. At this time, in consideration of errors and variations, the acceleration data AC after statistical processing such as an average value of a plurality of acceleration data AC may be compared with the determination acceleration ACth. As the value of the determination acceleration ACth, a value obtained by dividing the determination speed Vth by the acceleration data acquisition interval, that is, a value obtained by dividing the determination distance Lth by the acceleration data acquisition interval twice may be used. As a result, the processing burden and required time for calculating the determination element data can be saved.

[Sixth Embodiment]
Next, a position detection system according to a sixth embodiment of the present invention will be described.
In the second embodiment, the calculation device 30 calculates the movement distance L of the transmission terminal 10 based on the acceleration data notified from the transmission terminal 10, and based on the movement distance L, the presence / absence of movement of the transmission terminal 10 is determined. The case of determination has been described as an example.
In the present embodiment, on the assumption that the transmission terminal 10 is attached to a person, acceleration data is measured by the transmission terminal 10 to determine the presence / absence of walking, and the computing device 30 determines the presence / absence of walking notified from the transmission terminal 10 The case where the presence / absence of movement of the transmission terminal 10 is determined based on the data will be described.

  The configuration of the position detection system 1 according to the present embodiment is the same as that shown in FIG. Further, the position calculation process of the position detection system 1 according to the present embodiment is the same as that in FIG. 21 described above, but a process equivalent to step 200 and step 201 is executed in the transmission terminal 10.

  That is, the transmission control unit 11 of the transmission terminal 10 holds acceleration data measured by the acceleration sensor 14 for a detection period necessary for detecting a walking pattern, and searches for a walking pattern from past data for these detection periods. To do. In general, it is known that acceleration data changes in a specific pattern when a person walks. The transmission control unit 11 determines the presence / absence of walking according to the presence / absence of this walking pattern, and transmits a radio wave including the obtained walking presence / absence determination data and a transmission ID unique to itself.

The communication processing unit 23 of the receiving terminal 20 sends the reception result data obtained by adding its own reception ID to the set of the transmission ID, the walking presence / absence determination data, the received electric field strength, and the measurement time from the communication line 40 to the arithmetic device 30. Send.
The terminal control unit 31 of the arithmetic device 30 receives the reception result data from each receiving terminal 20 and sequentially stores it in the storage unit 34.
Thereafter, the movement presence / absence determination unit 36 acquires walking presence / absence determination data from the reception result data in the storage unit 34 and performs the movement presence / absence determination of the transmission terminal 10.

[Effect of Fifth Embodiment]
As described above, according to the present embodiment, the transmission terminal 10 determines the presence / absence of walking, and the arithmetic device 30 determines the presence / absence of movement of the transmission terminal 10 based on the walking presence / absence determination data notified from the transmission terminal 10. Therefore, particularly in an application in which the transmission terminal 10 is attached to a person, the presence or absence of movement of the transmission terminal 10 can be accurately determined, and as a result, position detection accuracy can be improved.

  Moreover, although this Embodiment demonstrated as an example the case where the presence or absence of a walk was determined from the acceleration data measured with the acceleration sensor 14, it is not limited to this. For example, instead of the acceleration sensor 14, a walking sensor may be provided, and the presence or absence of movement of the transmission terminal 10 may be determined based on the detection result of the walking sensor. This walking sensor may be a general sensor that is used in a pedometer or the like and detects the number of steps taken by a person walking.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Position detection system, 10 ... Transmission terminal, 11 ... Transmission control part, 12 ... Transmission part, 13 ... Antenna, 14 ... Acceleration sensor, 20 ... Reception terminal, 21 ... Antenna, 22 ... Reception part, 23 ... Communication processing part , 30 ... arithmetic device, 31 ... terminal control unit, 32 ... operation input unit, 33 ... screen display unit, 34 ... storage unit, 35 ... position calculation unit, 36 ... movement presence / absence determination unit, 37 ... target period changing unit, 40 ... communication line, 50 ... room.

Claims (11)

A transmitting terminal that transmits radio waves at a certain transmission interval;
A plurality of receiving terminals that receive the radio waves from the transmitting terminal and measure the received electric field strength;
An operation having a storage unit that sequentially stores the received electric field strengths obtained at these receiving terminals, and a position calculation unit that calculates the terminal position of the transmitting terminal based on the received electric field strengths stored in the storage unit Equipment and
The position calculating unit selects, for each receiving terminal, the maximum received electric field strength of the received electric field strengths obtained during the target period for the terminal position calculation from the received electric field strengths stored in the storage unit. Then, the terminal position is calculated from these maximum received electric field strengths. The position detection system according to claim 1,
The arithmetic device further includes a movement presence / absence determination unit that determines whether or not the transmission terminal has moved in the target period,
The position calculation unit calculates the terminal position based on the maximum received electric field strength when the movement presence / absence determination unit determines that the transmission terminal does not move, and determines that the transmission terminal has moved In the position detection system, the terminal position is calculated based on the latest received electric field strength among the received electric field strengths stored in the storage unit. In the position detection system according to claim 1 or 2,
The arithmetic device further includes a target period changing unit that calculates a moving speed of the transmitting terminal in the target period and changes a length of the target period according to the obtained moving speed. Detection system. The position detection system according to claim 2,
The transmission terminal sequentially transmits acceleration data measured by an acceleration sensor using the radio wave,
The receiving terminal receives the acceleration data by the radio wave,
The storage unit sequentially stores the acceleration data obtained by the receiving terminal,
The movement presence / absence determination unit includes determination element data including a movement distance or a movement speed of the transmission terminal in the target period from the acceleration data obtained in the target period among the acceleration data stored in the storage unit. A position detection system characterized by determining whether or not the transmitting terminal has moved during the target period based on the determination element data calculated and obtained. The position detection system according to claim 2,
The transmission terminal sequentially transmits acceleration data measured by an acceleration sensor using the radio wave,
The receiving terminal receives the acceleration data by the radio wave,
The storage unit sequentially stores the acceleration data obtained by the receiving terminal,
The movement presence / absence determination unit determines whether or not the transmission terminal moves in the target period from the acceleration data obtained in the target period among the acceleration data stored in the storage unit. Position detection system. The position detection system according to claim 3.
The transmission terminal sequentially transmits acceleration data measured by an acceleration sensor using the radio wave,
The receiving terminal receives the acceleration data by the radio wave,
The storage unit sequentially stores the acceleration data obtained by the receiving terminal,
The target period changing unit calculates the moving speed from acceleration data obtained in the target period among the acceleration data stored in the storage unit. The position detection system according to claim 2,
The transmitting terminal sequentially stores acceleration data measured by an acceleration sensor, calculates determination element data consisting of a movement distance or a movement speed of itself in the target period based on the acceleration data, and the obtained determination element data Are sequentially transmitted by the radio waves,
The receiving terminal receives the determination element data by the radio wave,
The storage unit sequentially stores the determination element data obtained at the receiving terminal,
The position detection system, wherein the movement presence / absence determination unit determines whether the transmission terminal has moved based on the determination element data stored in the storage unit. The position detection system according to claim 2,
The transmission terminal sequentially holds acceleration data measured by an acceleration sensor, determines the presence or absence of self movement in the target period based on the acceleration data, and sequentially transmits determination data indicating the determination result by the radio wave,
The receiving terminal receives the determination data by the radio wave,
The storage unit sequentially stores the determination data obtained by the receiving terminal,
The position detection system, wherein the movement presence / absence determination unit determines whether or not the transmission terminal has moved based on the latest determination data among the determination data stored in the storage unit. A step in which the transmitting terminal transmits radio waves at a certain transmission interval;
A plurality of receiving terminals receiving the radio waves from the transmitting terminal and measuring received electric field strength;
A step of sequentially storing the received electric field strength obtained by the receiving terminal in a storage unit of the arithmetic device;
A position calculating step of calculating a terminal position of the transmitting terminal based on the received electric field strength stored in the storage unit,
The position calculating step selects, for each receiving terminal, the maximum received electric field strength of the received electric field strengths obtained during the target period to be subjected to terminal position calculation among the received electric field strengths stored in the storage unit. Then, the terminal position is calculated from these maximum received electric field strengths. The position detection method according to claim 9.
The movement presence / absence determination unit of the arithmetic device further includes a movement presence / absence determination step of determining whether the transmission terminal has moved in the target period,
The position detection step calculates the terminal position based on the maximum received electric field strength when it is determined by the movement presence / absence determination step that the transmission terminal does not move, and when the transmission terminal is determined to have moved In the position detection method, the terminal position is calculated based on the latest received electric field strength among the received electric field strengths stored in the storage unit. In the position detection method according to claim 9 or 10,
The target period changing unit of the arithmetic device further includes a target period changing step of calculating the moving speed of the transmitting terminal in the target period and changing the length of the target period according to the obtained moving speed. A position detection method characterized by.

Images