JP2018112539A - Sensor and position estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sensor or the like capable of estimating the position where a living body exists in a wider range and with high accuracy by using a wireless signal. Observing with a transmitting station 10 having a transmitting antenna, a plurality of receiving stations 20-1 to 20-N each having a receiving array antenna, and a receiving array antenna of each of the plurality of receiving stations 20-1 to 20-N. From each of the first circuit 2 that extracts the biological component that is the signal component transmitted from the transmitting antenna element and reflected by one or more living organisms from the transmitted signal, and the biological component extracted by the first circuit 2. A second circuit 3 that calculates a position spectrum function that is an evaluation function for the position of one or more living organisms as seen from each of a plurality of receiving stations 20-1 to 20-N, and a plurality of position spectrum functions calculated by the second circuit 3. Is integrated into one function, and a third circuit 4 for estimating the position of one or more living organisms by calculating one or more maximum values of the integrated position spectrum function is provided. [Selection diagram] FIG. 6

Description

  The present disclosure relates to a sensor and a position estimation method, and more particularly, to a sensor and a position estimation method for estimating a position of a living body using a radio signal.

  A technique for detecting a detection target using a signal transmitted wirelessly has been developed (see, for example, Patent Document 1 and Non-Patent Document 1).

  Patent Document 1 discloses that the position and state of a person to be detected can be known by analyzing a component including a Doppler shift using Fourier transform. Non-Patent Document 1 discloses a technique for estimating the position of a detection target by using a fluctuation component extracted from propagation channel information and a MUSIC (Multiple Signal Classification) method.

Japanese Patent Laying-Open No. 2015-117972 JP 2010-249712 A JP 2007-155490 A JP 2010-32442 A Special table 2007-518968 gazette Special table 2012-524898 gazette

T.A. MIWA, S.M. OGIWARA, and Y.M. YAMAKOSHI, “Localization of Living-bodies using single-frequency multistatic Doppler radar system,” IEICE Transactions on Communications. E92-B, no. 7, pp. 20468-2476, July 2009.

  However, the techniques disclosed in Patent Literature 1 and Non-Patent Literature 1 have a problem that the range in which the living body can be detected, that is, the detection range becomes narrow when the living body to be detected is stationary.

  The present disclosure has been made in view of the above-described circumstances, and an object thereof is to provide a sensor and a position estimation method that can estimate a position where a living body is present in a wider range and with high accuracy using a radio signal.

  In order to achieve the above object, a sensor or the like according to an aspect of the present disclosure includes one or more transmission stations each having a transmission antenna, a plurality of reception stations each having a reception array antenna, and a plurality of reception stations. A first circuit that extracts a biological component, which is a signal component transmitted from the transmitting antenna and reflected by one or more living bodies, from the signal observed by the receiving array antenna, and extracted by the first circuit A second circuit that calculates a position spectrum function that is an evaluation function for the position of the one or more living bodies viewed from each of the plurality of receiving stations from each of the biological components, and a plurality of the position spectrum functions calculated by the second circuit Are integrated into one function, and one or more local maximum values of the integrated position spectrum function are calculated to estimate the position of the one or more living bodies. And a third circuit.

  According to the sensor or the like of the present disclosure, it is possible to estimate a position where a living body exists over a wider range and with high accuracy using a wireless signal.

2 is a block diagram illustrating a configuration of a sensor according to Embodiment 1. FIG. 6 is a diagram illustrating an example of an arrangement of a transmission station and a reception station in Embodiment 1. [FIG. 3 is a flowchart illustrating sensor position estimation processing according to the first embodiment. It is a flowchart which shows the detail of the position estimation process shown in FIG. It is a figure which shows the estimation possible range of the biological body position in a comparative example. FIG. 5 is a diagram showing an estimation possible range of a living body position in the first embodiment. 6 is a block diagram showing a configuration of a sensor in a modification of the first embodiment. FIG. 6 is a block diagram illustrating a configuration of a sensor according to Embodiment 2. FIG. FIG. 10 is a diagram illustrating an example of an arrangement of transmitting stations and receiving stations in the second embodiment. 6 is a flowchart illustrating details of sensor position estimation processing according to the second embodiment. It is a figure which shows the environment where the experiment in the Example of Embodiment 2 was conducted. It is a figure which shows the cumulative probability distribution of the estimated position error at the time of changing the number of receiving stations in the Example of Embodiment 2. FIG.

(Knowledge that became the basis of this disclosure)
Techniques for detecting a detection target using a signal transmitted wirelessly have been developed (see, for example, Patent Documents 1 to 6 and Non-Patent Document 1).

  For example, Patent Documents 2 to 3 disclose techniques for calculating the presence / absence of an object and a moving direction using a UWB (Ultra Wide Band) radio signal. More specifically, a UWB (Ultra Wide Band) radio signal is transmitted to a predetermined area, and a radio signal reflected by an object to be detected is received by an array antenna. Then, only the signal from the moving object is separated using the Doppler effect, and the presence / absence of the moving object and the moving direction are calculated from the pair of the separated signals.

  In addition, for example, in Patent Documents 4 to 5, by performing arrival direction estimation processing, which is one of array antenna signal processing techniques, on a difference in reception timing at which an antenna receives a UWB signal transmitted from a transmitter, A technique for calculating the direction and position of the transmitter is disclosed.

  For example, Patent Document 6 discloses a technique for estimating the position of an object using a direction estimation algorithm such as the MUSIC method. Specifically, a direction estimation algorithm such as the MUSIC method is applied to each of a plurality of receiving stations that have received a signal transmitted from a transmitting station, and the results are integrated by multiplication or addition. As a result, highly accurate direction estimation is possible.

  However, as a result of detailed studies, the inventors have found that the techniques disclosed in Patent Documents 2 to 6 cannot estimate the position of a living body. That is, according to the methods of Patent Documents 2 to 3, it is found that the presence or absence of a person can be detected, but the direction and position where the person exists cannot be estimated. Further, the techniques disclosed in Patent Documents 4 to 6 are techniques for estimating the position of a transmitter that emits radio waves, and it has been found that position estimation cannot be performed on a living body.

  Japanese Patent Application Laid-Open No. 2004-228561 discloses a technique that can know the position and state of a person to be detected by analyzing a component including a Doppler shift using Fourier transform. Non-Patent Document 1 discloses a technique for estimating the position of a detection target by using a fluctuation component extracted from propagation channel information and the MUSIC method.

  More specifically, in the techniques disclosed in Patent Document 1 and Non-Patent Document 1, a propagation channel between transmission / reception antennas is observed and its time series change is recorded. Thereafter, a Fourier transform process is performed on the propagation channels observed in time series, and a time response is converted into a frequency response. Here, since there are a plurality of transmission / reception antennas, the frequency response is a matrix of complex elements. By applying a direction or position estimation algorithm such as the MUSIC method to this frequency response matrix, the direction and position of the target can be specified. Furthermore, Patent Document 1 shows that even if there are a plurality of objects, detection is possible at the same time.

  However, in the techniques disclosed in Patent Document 1 and Non-Patent Document 1, in a situation where the Doppler effect is very weak, such as when the living body to be detected is stationary, the detectable distance is shortened. There is a problem that the detection range that can be detected becomes narrow. This is because in a situation where the Doppler effect is very weak, the Doppler shift is affected by the internal noise of the receiver, interference waves flying from other than the detection target, and the presence of an object that generates a Doppler shift other than the detection target. This is because it becomes difficult to detect a weak signal. In addition, if the target living body has a special device such as a transmitter, even a living body that is stationary can be detected.

  Accordingly, in view of the above, the inventors have made it possible to determine the position where the living body exists using a wireless signal in a wider range and with high accuracy without having the target living body possess a special device such as a transmitter. We came up with a sensor that can be estimated.

  That is, a sensor according to an aspect of the present disclosure is observed at one or more transmitting stations each having a transmitting antenna, a plurality of receiving stations each having a receiving array antenna, and the receiving array antenna of each of the plurality of receiving stations. From the first signal for extracting a biological component that is a signal component transmitted from the transmitting antenna and reflected by one or more living organisms, and the plurality of biological components extracted by the first circuit, A second circuit for calculating a position spectrum function which is an evaluation function for the position of the one or more living bodies viewed from each of the receiving stations, and a plurality of the position spectrum functions calculated by the second circuit are integrated into one function. And a third circuit for estimating the position of the one or more living bodies by calculating one or more local maximum values of the integrated position spectrum function. .

  With this configuration, estimation is performed by integrating the position spectrum functions obtained from complex transfer functions obtained by a plurality of receiving stations, so that the position where the living body is present can be estimated with a wider range and with high accuracy using radio signals. . For example, even if the signal from the target living body is weak and some of the receiving stations cannot observe the reflected wave from the living body, the complex at the receiving station that was able to observe the reflected wave from the living body. The position of the living body can be estimated using the position spectrum function obtained from the transfer function.

  Further, for example, the one or more transmission stations may be two or more transmission stations, and each of the two or more transmission stations may include a transmission array antenna including two or more elements of the transmission antenna.

  Here, for example, the second circuit further includes a fourth circuit that controls the transmission timing so that none of the two or more transmission stations simultaneously transmit from the transmission array antenna.

  For example, the circuit for estimating the position of the one or more living bodies may be integrated into one function by multiplying or adding the calculated plurality of position spectrum functions to each other.

  Further, for example, the circuit for calculating the position spectrum function may calculate the position spectrum function based on a MUSIC (Multiple Signal Classification) algorithm.

  In addition, the position estimation method according to an aspect of the present disclosure is transmitted from a signal observed by the reception array antenna of each of a plurality of reception stations each having a reception array antenna from transmission antenna elements included in one or more transmission stations. And extracting a biological component that is a signal component reflected by one or more living organisms, and each of the biological components extracted in the extracting step from each of the plurality of receiving stations. A position spectrum function that is an evaluation function for the position; and a plurality of the position spectrum functions calculated in the calculating step are integrated into one function, and one or more local maximum values of the integrated position spectrum function are obtained. And calculating the position of the one or more living organisms by calculation.

  Note that the present disclosure is not only realized as an apparatus, but also realized as an integrated circuit including processing means included in such an apparatus, or realized as a method using processing means constituting the apparatus as a step. Can be realized as a program for causing a computer to execute, or as information, data, or a signal indicating the program. These programs, information, data, and signals may be distributed via a recording medium such as a CD-ROM or a communication medium such as the Internet.

  Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that each of the embodiments described below shows a preferred specific example of the present disclosure. Numerical values, shapes, materials, components, arrangement positions and connection forms of components, steps, order of steps, and the like shown in the following embodiments are merely examples, and are not intended to limit the present disclosure. In addition, among the constituent elements in the following embodiments, constituent elements that are not described in the independent claims indicating the highest concept of the present disclosure are described as optional constituent elements that constitute a more preferable embodiment. Further, in the present specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

(Embodiment 1)
Hereinafter, the position estimation method for the sensor 1 according to the first embodiment will be described with reference to the drawings.

[Configuration of Sensor 1]
FIG. 1 is a block diagram illustrating a configuration of a sensor 1 according to the first embodiment. FIG. 2 is a diagram illustrating an example of the arrangement of transmitting stations and receiving stations in the first embodiment.

  The sensor 1 shown in FIG. 1 includes a transmitting station 10, N receiving stations 20-1 to 20 -N, and a position estimation unit 30. FIG. 2 conceptually shows the arrangement of the transmitting station 10 and the receiving stations 20-1 to 20-4 in the case where the number of N is four, and how signals are transmitted.

[Transmission station 10]
The transmission station 10 has a transmission antenna. Specifically, the transmission station 10 includes a transmitter 11 and a transmission antenna 12 as shown in FIG.

  The transmission antenna 12 is composed of one transmission antenna, that is, one transmission antenna element.

  The transmitter 11 generates a high-frequency signal used for estimating the direction of the living body 40. For example, as illustrated in FIG. 2, the transmitter 11 transmits the generated signal from the transmission antenna 12 as a transmission wave.

[Receiving stations 20-1 to 20-N]
Each of the receiving stations 20-1 to 20-N has a receiving array antenna. Here, N is an integer of 2 or more. As an example, the i-th receiving station 20-i (i is an integer not less than 1 and not more than N) among N receiving stations will be described as an example. All the receiving stations 20-1 to 20-N have the same configuration and perform the same processing.

  The receiving station 20-i includes a receiving antenna 21-i, a receiver 22-i, a complex transfer function calculating unit 23-i, a biological component extracting unit 24-i, and a position spectrum function calculating unit 25-i. Prepare.

<Receiving antenna 21-i>
Receive antenna 21-i is a reception array antenna configured by the receiving antennas i.e. M _R receive antennas elements of M _R element. The reception antenna 21-i receives a high-frequency signal with a reception array antenna. In the present embodiment, for example, as shown in FIG. 2, the receiving antenna 21-i is configured such that a part of the transmission wave transmitted from the transmission antenna 12 is reflected by the living body 40 on the received high-frequency signal. In some cases, the reflected signal is a reflected signal.

<Receiver 22-i>
The receiver 22-i converts the high frequency signal received by the receiving antenna 21-i into a low frequency signal that can be processed. The receiver 22-i transmits the converted low-frequency signal to the complex transfer function calculation unit 23-i.

<Complex transfer function calculator 23-i>
The complex transfer function calculation unit 23-i calculates a complex transfer function representing a propagation characteristic between the reception array antenna and the transmission antenna 12 of the transmission station 10 from a signal observed by the reception array antenna of the reception station 22-i. calculate. More specifically, the complex transfer function calculation unit 23-i from the low frequency of the signal transmitted by the receiver 22-i, the reception array antenna and one transmit antenna elements of the transmitting antenna 12 M _R-number of A complex transfer function representing propagation characteristics with the receiving antenna element is calculated. The complex transfer function calculated by the complex transfer function calculating unit 23-i includes a reflected wave that does not pass through the living body 40, such as a direct wave from the transmitting antenna 12 and a reflected wave derived from a fixed object. In addition, the complex transfer function calculated by the complex transfer function calculating unit 23-i may include a reflected wave that is a signal reflected by the living body 40 from a part of the transmitted wave transmitted from the transmission antenna 12. The amplitude and phase of the reflected wave reflected by the living body 40, that is, the reflected wave passing through the living body 40, always fluctuate due to living body activities such as respiration and heartbeat.

  Hereinafter, description will be made assuming that the complex transfer function calculated by the complex transfer function calculating unit 23-i includes a reflected wave that is a signal reflected by the living body 40.

<Biological component extraction unit 24-i>
The biological component extraction unit 24-i obtains a biological component that is a signal component transmitted from the transmission antenna 12 and reflected by one or more living organisms 40 from a signal observed by the reception array antenna of the receiving station 22-i. Extract. More specifically, the biological component extraction unit 24-i records the complex transfer function calculated by the complex transfer function calculation unit 23-i in a time series in the order in which signals are observed. And the biological component extraction part 24-i extracts the fluctuation | variation component by the influence of the biological body 40 as a biological component among the changes of the complex transfer function recorded in time series. Here, as a method of extracting the fluctuation component due to the influence of the living body, a method of extracting only the component corresponding to the vibration of the living body after conversion to the frequency domain by Fourier transform or the like, or a complex transfer function of two different times There is a method of extracting by calculating the difference of. By these methods, the complex transfer function of the reflected wave passing through the direct wave and the fixed object is removed, and only the complex transfer function component of the reflected wave passing through the living body 40 remains.

In the present embodiment, the receiving antenna elements constituting the receiving array antenna because of M _R number i.e. multiple, the number ie biological components of the variation component through the biological 40 complex transfer function corresponding to the receiving array antennas and multiple Become. Hereinafter, these are collectively referred to as a biological component channel vector.

<Position Spectrum Function Calculation Unit 25-i>
The position spectrum function calculation unit 25-i calculates a position spectrum function, which is an evaluation function for the position of one or more living bodies 40 as viewed from the receiving station 20-i, from the biological components extracted by the biological component extraction unit 24-i. . Here, for example, the position spectrum function calculation unit 25-i may calculate the position spectrum function based on the MUSIC algorithm.

In the present embodiment, the position spectrum function calculation unit 25-i calculates the correlation matrix R _i of the biological component channel vector extracted by the biological component extraction unit 24-i, and uses the obtained correlation matrix R _i. The position spectrum function P _i (θ) with respect to the angle θ _i formed with the direction of the living body 40 viewed from the receiving station 20-i is calculated by a predetermined arrival direction estimation method.

The position spectrum function calculation unit 25-i transmits the calculated position spectrum function P _i (θ) to the position estimation unit 30.

Hereinafter, a procedure until the position spectrum function calculation unit 25-i calculates the position spectrum function P _i (θ) using the MUSIC method will be described using mathematical expressions. It is assumed that the biological component is extracted using Fourier transformation.

When eigenvalue decomposition is performed on the correlation matrix R _i of the biological component channel vector, it can be written as (Equation 1) to (Equation 3) below.

は要素数がＭ_Ｒである固有ベクトル、

は固有ベクトルに対応する固有値であり、

の順であるものとする。Ｌは到来波の数つまり検出対象の生体数である。 Here, _{M R} is the number of antennas of the receiver station 20-i,

Eigenvectors number of elements is M _R,

Is the eigenvalue corresponding to the eigenvector,

It is assumed that the order is L is the number of incoming waves, that is, the number of living bodies to be detected.

  The steering vector or direction vector of the receiving array antenna can be defined by (Equation 4).

Here, k is a wave number. In the MUSIC method, the position spectrum function P _i (θ) is calculated using this steering vector as shown in (Formula 5).

The position spectrum function P _i (θ) takes a maximum value with the denominator being minimized at an angle where the living body is present when viewed from the i-th receiving station 20-i.

  In calculating the position spectrum function, the beam former method may be used instead of the MUSIC method, or the Capon method may be used.

[Position estimation unit 30]
The position estimation unit 30 receives position spectrum functions calculated by the N position spectrum function calculation units 25-1 to 25-N. The position estimation unit 30 integrates a plurality of position spectrum functions calculated by the position spectrum function calculation units 25-1 to 25-N into one function, and calculates one or more maximum values of the integrated position spectrum function. Thus, the position of one or more living bodies 40 is estimated. Here, the position estimation unit 30 integrates the calculated plurality of position spectrum functions into one function by multiplying or adding each other.

In the present embodiment, the position estimation unit 30 integrates N position spectrum functions P _i (θ), and performs position estimation of the living body 40 based on the integrated position spectrum function. More specifically, the position estimation unit 30 acquires each position spectrum function P _i (θ) calculated using, for example, (Equation 5) from the N receiving stations 20-1 to 20 -N. Then, the position estimation unit 30 calculates a position spectrum function P _all (Θ) obtained by integrating the acquired N position spectrum functions P _i (θ) using (Expression 6) and (Expression 7).

  Here, Π represents a multiplication operation.

Each position spectrum function P _i (θ) takes a maximum value at an angle at which the living body 40 exists when viewed from the corresponding receiving station 20-i, but also at other angles including a direction outside the measurement range. Will not be zero. Therefore, by multiplying N position spectrum functions, an evaluation function reflecting the results of all N receiving stations, that is, an integrated position spectrum function can be obtained. And the position of the living body 40 which is the direction of an incoming wave can be estimated by searching for the local maximum value of the integrated position spectrum function P _all (Θ).

[Operation of sensor 1]
A process in which the sensor 1 configured as described above estimates the position of the living body will be described.

  FIG. 3 is a flowchart showing the position estimation process of the sensor 1 according to the first embodiment. FIG. 4 is a flowchart showing details of the position estimation process shown in FIG.

  First, as shown in FIG. 3, the sensor 1 is transmitted from the transmission antenna element of the transmission station 10 from signals observed by the reception array antennas of the plurality of reception stations 20-1 to 20 -N, and 1 A biological component that is a signal component reflected by the living body is extracted (S1). More specifically, as shown in FIG. 4, first, the sensor 1 observes a received signal for a predetermined period at N receiving stations (S11). Next, the sensor 1 calculates a complex transfer function from each of the received signals observed with the receiving array antennas of the N receiving stations (S12). Then, the sensor 1 records each calculated complex transfer function in time series, and extracts a biological component from each recorded time series complex transfer function (S13).

  Next, as shown in FIG. 3, the sensor 1 is a position that is an evaluation function with respect to the position of one or more living bodies 40 viewed from each of the plurality of receiving stations 20-1 to 20 -N from each of the biological components extracted in S <b> 1. A spectrum function is calculated (S2). More specifically, as shown in FIG. 4, first, the sensor 1 calculates the correlation matrix of each biological component extracted in S13 (S21). Next, the sensor 1 calculates the position spectrum function of the living body 40 viewed from each of the N receiving stations using the correlation matrix calculated in S21 (S22).

  Next, as shown in FIG. 3, the sensor 1 integrates a plurality of position spectrum functions calculated in S <b> 2 into one function, and calculates one or more local maximum values of the integrated position spectrum function. The position of the living body is estimated (S3). More specifically, as shown in FIG. 4, first, the sensor 1 integrates by multiplying or adding the N position spectrum functions calculated in S22 (S31). Then, the sensor 1 estimates the position of one or more living bodies 40 by calculating one or more maximum values of the position spectrum integrated in S31 (S32).

[Effects]
According to the sensor 1 and the position estimation method of the present embodiment, the position where the living body is present can be estimated with a wider range and with high accuracy by using a radio signal. In addition, according to the sensor 1 and the position estimation method of the present embodiment, a detection range in which a living body can be detected can be widened by including a plurality of receiving stations. More specifically, according to the sensor 1 and the position estimation method of the present embodiment, a biological component is extracted from information of complex transfer functions obtained by a plurality of receiving stations, and is obtained by calculation from the extracted biological component. The position spectrum function is integrated to estimate the position of the living body. Thereby, the position where the living body exists can be estimated in a wider range without being affected by the obstacle. For example, even if the signal from the target living body is weak and some of the receiving stations cannot observe the reflected wave from the living body, the complex at the receiving station that was able to observe the reflected wave from the living body. The position of the living body can be estimated using the position spectrum function obtained from the transfer function.

  Here, it will be described with reference to FIGS. 5A and 5B that the sensor 1 of the present embodiment can estimate the position of the living body over a wide range.

  FIG. 5A is a diagram illustrating a presumable range of the living body position in the comparative example. FIG. 5B is a diagram showing a presumable range of the living body position in the present embodiment. In the comparative example shown in FIG. 5A, a detection range 60 in which the living body position can be estimated by, for example, a MIMO (Multiple Input Multiple Output) radar using one transmitting station 10 and one receiving station 20-1. The detection range 60 corresponds to a region where a beam output from one transmitting station 10 and a beam output from one receiving station 20-1 overlap. On the other hand, in the present embodiment shown in FIG. 5B, a detection range 70 in which the living body position can be estimated by the sensor 1 using one transmitting station 10 and four receiving stations 20-1 to 20-4 is shown. It can be seen that the detection range 70 is wider than the detection range 60 of the comparative example. The sensor 1 according to the present embodiment integrates the position spectrum function calculated based on the signals received by each of the plurality of receiving stations into one and can estimate the living body position, so that the plurality of receiving stations can be linked. . Thereby, the detection range which can receive the Doppler shift component by a biological body can be expanded. In addition, by linking a plurality of receiving stations, the living body position can be estimated if the living body component can be extracted by some of the plurality of receiving stations, so that the estimation accuracy can be improved.

(Modification)
FIG. 6 is a block diagram illustrating a configuration of the sensor 1a according to the modification of the first embodiment. Elements similar to those in FIG. 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the sensor 1 shown in FIG. 1, a complex transfer function calculation unit 23-i, a biological component extraction unit 24-i, and a position spectrum function calculation unit 25-i are configured in each of the plurality of receiving stations 20-1 to 20-N. However, it is not limited to this. Like the sensor 1a shown in FIG. 6, each of the plurality of receiving stations 20-1 to 20-N includes a complex transfer function calculation unit 23-i, a biological component extraction unit 24-i, and a position spectrum function calculation unit 25-i. May not be configured. In this case, the sensor 1a may include the first circuit 24a and the second circuit 25a instead of the complex transfer function calculation unit 23-i, the biological component extraction unit 24-i, and the position spectrum function calculation unit 25-i. In addition, the sensor 1 a includes a third circuit 30 a that realizes the function of the position estimation unit 30. Other configurations are the same as those of the sensor 1 shown in FIG.

  The first circuit 24a is a circuit that realizes the functions of N complex transfer function calculation units and N biological component extraction units. More specifically, the first circuit 24a is transmitted from the transmission antenna element of the transmission station 10 from signals observed by the reception array antennas of the plurality of reception stations 20-1 to 20-N, and is one or more. A biological component that is a signal component reflected by the living body is extracted.

  The second circuit 25a is a circuit that realizes the functions of N position spectrum function calculation units. More specifically, the second circuit 25a is an evaluation function for the position of one or more living bodies 40 viewed from each of the plurality of receiving stations 20-1 to 20-N from each of the biological components extracted by the first circuit 24a. A certain position spectrum function is calculated.

  The third circuit 30a is a circuit that realizes the function of the position estimation unit 30, integrates a plurality of position spectrum functions calculated by the second circuit 25a into one function, and at least one maximum of the integrated position spectrum functions. The position of one or more living bodies 40 is estimated by calculating the value.

(Embodiment 2)
In the first embodiment, the case where the sensor 1 includes one transmission station has been described. However, the present invention is not limited to this. In the second embodiment, a position estimation method for the sensor 1A including two or more transmitting stations or two or more transmitting antenna elements will be described.

[Configuration of Sensor 1A]
FIG. 7 is a block diagram showing the configuration of the sensor 1A in the second embodiment. FIG. 8 is a diagram illustrating an example of an arrangement of transmitting stations and receiving stations in the second embodiment. Elements similar to those in FIGS. 1 and 2 are given the same reference numerals, and detailed description thereof is omitted.

The sensor 1A illustrated in FIG. 7 includes N _T transmitting stations 10-1 to 10-N _T , N _R receiving stations 20-1 to 20-N _R , a position estimation unit 30A, and a transmission timing control unit. 50. Although FIG. 8, the arrangement of the transmitting station 10-1～10-2 and the reception station 20-1 receiving station 20-4 when _{the N T} is four two Tsude _{the N R,} signal transduction It is shown conceptually.

[Transmission stations 10-1 to 10-N _T ]
Each of the transmission stations 10-1 to 10- _NT has a transmission array antenna including two or more transmission antennas. Here, _NT is an integer of 2 or more. Since, j-th as a representative of the N _T transmit station (j is an integer 1 or more N _T) will be described as an example the transmission station 20-j of. All transmitting stations have the same configuration and perform the same processing. In addition, as for the arrangement of the transmitting stations 10-1 to 10- _NT , it is desirable that the angle between one transmitting station and another transmitting station is not 180 degrees or 90 degrees.

  The transmitting station 10-j includes a transmitting antenna 12-j and a transmitter 11-j.

<Transmitting antenna 12-j>
Transmitting antenna 12-j is a transmission array antenna having a transmission antenna of M _T elements. The transmission antenna 12-j transmits a high-frequency signal with a transmission array antenna. In the present embodiment, the transmission antenna 12-j transmits a transmission wave, which is a high-frequency signal, to a region including the living body 40, for example, as illustrated in FIG.

<Transmitter 11-j>
The transmitter 11-j generates a high-frequency signal used to estimate the position of the living body 40. The transmitter 11-j transmits the generated high-frequency signal to the transmission antenna 12-j as a transmission wave. Here, the transmitter 11-j is controlled by the transmission timing control unit 50 so as not to transmit a transmission wave simultaneously with other transmission stations.

[Transmission timing control unit 50]
The transmission timing control unit 50 is an example of a fourth circuit. The transmission timing control unit 50 controls the transmission timing so that none of the two or more transmission stations 10-1 to 10- _NT simultaneously perform transmission from the transmission array antenna.

[Receiving stations 20-1 to 20-N _R ]
Each receiving station 20-1 to _{20-N R} has a reception array antenna. Here, N _R is an integer of 2 or more. Later, i-th as a representative of the N _R reception station (i is an integer 1 or more N _R) will be described by way of the receiving station 20-i of the examples. All receiving stations have the same configuration and perform the same processing.

  The receiving station 20-i includes a receiving antenna 21-i, a receiver 22-i, a complex transfer function calculating unit 23-i, a biological component extracting unit 24-i, and a position spectrum function calculating unit 25-i. Prepare.

<Receiving antenna 21-i>
Receive antenna 21-i is a reception array antenna configured by the receiving antennas i.e. M _R receive antennas elements of M _R element. The reception antenna 21-i receives a high-frequency signal with a reception array antenna. In this embodiment, the receiving antenna 21-i, for example, as shown in FIG. 8, by the arrangement transmits, to the reception high frequency signal, which is transmitted from one of the transmitting antennas 12-1 to 12-N _T A part of the wave may include a reflected wave that is a signal reflected by the living body 40.

<Receiver 22-i>
The receiver 22-i converts the high frequency signal received by the receiving antenna 21-i into a low frequency signal that can be processed. The receiver 22-i transmits the converted low-frequency signal to the complex transfer function calculation unit 23-i.

<Complex transfer function calculator 23-i>
The complex transfer function calculation unit 23-i uses the reception array antenna and the transmission antennas 12-1 to 12- of the transmission stations 10-1 to 10- _{NT based on} the signals observed by the reception array antenna of the reception station 22-i. calculating the complex transfer function representing the propagation characteristics between one of N _T.

In the present embodiment, a plurality of transmitting stations 10-1 to 10- _NT exist, but the transmission timing control unit 50 receives only signals from at most one transmitting station at a specific time. Therefore, the complex transfer function calculation unit 23-i can calculate a complex transfer function related to a specific transmission station by dividing time.

  In the following description, it is assumed that the complex transfer function calculated by the complex transfer function calculating unit 23-i includes a reflected wave that is a signal reflected by the living body 40.

<Biological component extraction unit 24-i>
Biological component extraction unit 24-i from the observed signals at the receiving antenna array of the receiver station 22-i, is transmitted from one of the transmitting antennas 12-1 to _{12-N T,} and, by one or more biological 40 A biological component that is a reflected signal component is extracted. More specifically, the biological component extraction unit 24-i records the complex transfer function calculated by the complex transfer function calculation unit 23-i in a time series in the order in which signals are observed. And the biological component extraction part 24-i extracts the fluctuation | variation component by the influence of the biological body 40 as a biological component among the changes of the complex transfer function recorded in time series.

  In the present embodiment, since there are a plurality of transmission antenna elements constituting the transmission array antenna and reception antenna elements constituting the reception array antenna, the fluctuation component of the complex transfer function corresponding to the reception array antenna via the living body 40 The number, that is, the biological component is also plural. These are collectively referred to as biological component channel vectors.

<Position Spectrum Function Calculation Unit 25-i>
The position spectrum function calculation unit 25-i calculates a position spectrum function, which is an evaluation function for the position of one or more living bodies 40 as viewed from the receiving station 20-i, from the biological components extracted by the biological component extraction unit 24-i. . Here, for example, the position spectrum function calculation unit 25-i may calculate the position spectrum function based on the MUSIC algorithm.

In the present embodiment, the position spectrum function calculation unit 25-i calculates the correlation matrix R _{i, j} of the biological component channel vector extracted by the biological component extraction unit 24-i, and uses the obtained correlation matrix. The position spectrum function with respect to the angle θ _R formed with the direction of the living body 40 viewed from the receiving station 20-i and the angle θ _T formed with the direction of the living body 40 viewed from the transmitting station 10-j by a predetermined arrival direction estimation method. P _{i, j} (θ _R , θ _T ) is calculated. The position spectrum function calculation unit 25-i transmits the calculated position spectrum function P _{i, j} (θ _R , θ _T ) to the position estimation unit 30A.

Hereinafter, the procedure until the position spectrum function calculation unit 25-i calculates the position spectrum function P _{i, j} (θ _R , θ _T ) using the MUSIC method will be described using mathematical expressions. It is assumed that the biological component is extracted using Fourier transformation.

  When eigenvalue decomposition is performed on the correlation matrix of the biological component channel vector, it can be written as (Equation 8) to (Equation 10) below.

は要素数がＭ_Ｒである固有ベクトル、

は固有ベクトルに対応する固有値であり、

の順であるものとする。Ｌは到来波の数つまり検出対象の生体数である。 Here, _{M R} is the number of antennas of the receiver station 20-i, _{M T} is the number of antennas of the transmitting station 10-j,

Eigenvectors number of elements is M _R,

Is the eigenvalue corresponding to the eigenvector,

It is assumed that the order is L is the number of incoming waves, that is, the number of living bodies to be detected.

  The steering vector, that is, the direction vector of the receiving array antenna can be defined by (Equation 11).

  Similarly, the steering vector of the transmission array antenna can be defined by (Equation 12).

  Here, k is a wave number. Furthermore, the steering vector of transmission / reception is multiplied, and as shown in (Equation 13), the steering vector considering the angle information of both transmission and reception is defined.

Then, when the MUSIC method is applied to the steering vector defined by (Equation 13), as shown in (Equation 14), the position spectrum function P _{i, j} (θ _R , θ _T ) is calculated using this steering vector. be able to.

In the position spectrum function P _{i, j} (θ _T , θ _R ), θ _R is an angle at which the living body 40 exists when viewed from the receiving station 20-i, and θ _T is a living body viewed from the transmitting station 10-j. When 40 is an existing angle, the denominator is minimized and the maximum value is obtained.

  In calculating the position spectrum function, the beam former method may be used instead of the MUSIC method, or the Capon method may be used.

In the present embodiment, each of the plurality of receiving stations has been described as including a complex transfer function calculation unit, a biological component extraction unit, and a position spectrum function calculation unit. However, the present invention is not limited to this. Like the modification of the first embodiment, the sensor 1A is, M _R-number of the first circuit for realizing functions of the complex transfer function calculation unit and the living body component extraction unit, M _R-number of position function of the spectral function calculating unit And a second circuit for realizing the above.

[Position estimation unit 30A]
The position estimation unit 30A, the position spectrum function of the calculated by the position spectral function calculator _{25-1~25-N R N R × N} T is transmitted. The position estimation unit 30A is an example of a third circuit. Position estimating unit 30A integrates a plurality of positions spectral function calculated by the position spectral function calculator 25-1 to 25-N _R respectively in one function, calculates one or more local maximum positions spectral function that integrates By doing so, the position of one or more living bodies 40 is estimated. Here, the position estimation unit 30 integrates the calculated plurality of position spectrum functions into one function by multiplying or adding each other.

In this embodiment, the position estimation unit 30A is, _{N R} number of receiving stations _{20-1~25-N R} are each, for example, position the spectral function _{P i} calculated using (Equation _{14), j} (theta _T, θ _R ) is acquired. Then, the position estimation unit 30A calculates a position spectrum function P _all (Θ _T , Θ _R ) obtained by integrating N _R × N _T using (Expression 15) to (Expression 17).

  Here, Π represents a multiplication operation.

Each position spectrum function P _{i, j} (θ _T , θ _R ) takes a maximum value at an angle at which the living body 40 exists as viewed from the corresponding receiving station 20-i, but includes a direction outside the measurement range. The value does not become 0 at angles other than. Therefore, it is possible to obtain the position spectral function that reflects all the results receiving station N _R × N _T station by multiplying the N _R × N _T number of positions spectral function. Then, the position of the living body 40 that is the direction of the incoming wave can be estimated by searching for the maximum value of the integrated position spectrum function P _all (Θ _T , Θ _R ).

[Operation of sensor 1A]
A process in which the sensor 1A configured as described above estimates the position of the living body will be described.

  FIG. 9 is a flowchart showing details of the position estimation process of the sensor 1A in the second embodiment. FIG. 9 corresponds to the details of the present embodiment of the position estimation process shown in FIG.

First, in S1, the sensor 1A causes a reception signal to be observed for a predetermined period in the _NR receiving stations (S11A). Next, the sensor 1A calculates a complex transfer function representing a propagation characteristic between the transmission antenna element and the reception antenna element from each of the reception signals observed by the reception array antennas of the _NR reception stations (S12A). Then, the sensor 1A records each of the calculated complex transfer functions in time series, and extracts a biological component that is a fluctuation component due to the influence of the living body from each of the recorded complex transfer functions in time series (S13A).

Next, in S2, the sensor 1A calculates a correlation matrix of each biological component extracted in S13A (S21A). Next, the sensor 1 uses the correlation matrix calculated in S21A to determine N _R × N _T for the direction of the living body 40 viewed from each of the N _R receiving stations and the direction of the living body 40 viewed from each of the N _T transmitting stations. The position spectrum function is calculated (S22A).

Next, in S3, the sensor 1A performs integration by multiplying or adding the N _R × N _T position spectrum functions calculated in S22A (S31A). Then, the sensor 1A estimates the position of one or more living bodies 40 by calculating one or more maximum values of the position spectrum integrated in S31A (S32A).

[Effects]
According to the sensor 1A and the position estimation method of the present embodiment, the position where the living body is present can be estimated with a wider range and with high accuracy by using the radio signal.

  In addition, according to the sensor 1 and the position estimation method of the present embodiment, by increasing the number of transmitting stations and the number of receiving stations, the area where the Doppler shift component can be received by the living body is expanded. As a result, even when there are a plurality of living bodies to be detected, there is an effect that the position can be estimated without lowering the accuracy.

(Example)
Here, since evaluation by experiment was performed in order to confirm the effect which concerns on Embodiment 2, it demonstrates as an Example below.

  FIG. 10 is a diagram illustrating an environment in which an experiment in the present example was performed.

  This experiment was conducted in a wooden house 9m wide x 6m long. In this experiment, an 8-element circular sleeve antenna was used as a transmitting antenna constituting a transmitting station indicated by Tx in the figure, and a 4-element linear array antenna was used as a receiving antenna constituting receiving stations indicated by Rx1 to Rx4 in the figure. The transmitting station Tx is arranged at the coordinates (6, 3), and the receiving stations Rx1 to Rx4 are the four corners of the measurement range, that is, the coordinates (1, 5.5), (8, 5), (8.5, 1), (0.5, 0.5). Further, the interval between the transmitting and receiving array elements, that is, the element interval of the 8-element circular sleeve antenna is 0.5 wavelength, the operating frequency is 2.47125 GHz, the antenna height is 115 cm, the sampling frequency is 100 Hz, and the frequency range of the biological activity to be extracted is 0.3 to 3. The measurement time was 3 seconds and 20 seconds. In this experiment, the measurement target was one person, and the measurement target was placed at each of 23 points in the wooden house, that is, in the experimental environment, and the channel was measured.

  FIG. 11 is a diagram illustrating a cumulative distribution function (CDF) of an estimated position error when the number of receiving stations is changed in the present embodiment. The vertical axis represents the cumulative probability distribution (CDF), and the horizontal axis represents the estimated position error. 1Rx indicates the result of measuring the cumulative probability distribution of the estimated position error at one station that is one of the four receiving stations Rx1 to Rx4. Similarly, 2Rx, 3Rx, or 4Rx indicates the result of measuring the cumulative probability distribution of the estimated position error at 2 stations, 3 stations, or 4 stations out of the four receiving stations Rx1 to Rx4.

  From the result shown in FIG. 8, the probability that the estimated position error can be estimated within 1 m is 2 stations higher than 1 station, 3 stations than 2 stations, and 4 stations rather than 3 stations. I know that there is.

  From the above results, it can be seen that the position estimation accuracy is improved by increasing the number of receiving stations.

  As described above, according to the present disclosure, a biological component is extracted from information on complex transfer functions obtained by a plurality of receiving stations, a position spectrum function obtained by calculation from the extracted biological component is integrated, and a living body position is obtained. Is estimated. Thereby, the position where the living body exists using the radio signal can be estimated in a wider range without being affected by the obstacle. For example, even if the signal from the target living body is weak and some of the receiving stations cannot observe the reflected wave from the living body, the complex at the receiving station that was able to observe the reflected wave from the living body. The position of the living body can be estimated using the position spectrum function obtained from the transfer function.

  As described above, the sensor and the position estimation method according to one aspect of the present disclosure have been described based on the embodiments. However, the present disclosure is not limited to these embodiments. Unless it deviates from the gist of the present disclosure, forms in which various modifications conceived by those skilled in the art have been made in the present embodiment, or forms constructed by combining components in different embodiments are also included in the scope of the present disclosure. .

  In addition, the present disclosure can be realized not only as a sensor including such a characteristic component but also as a position estimation method using the characteristic component included in the sensor as a step. It can also be realized as a computer program that causes a computer to execute the characteristic steps included in such a method. Needless to say, such a computer program can be distributed via a computer-readable non-transitory recording medium such as a CD-ROM or a communication network such as the Internet.

  The present disclosure can be used for a sensor and a position estimation method that estimate the position of a living body using a wireless signal, and in particular, a measuring instrument that measures the direction or position of a living body, and a home appliance that performs control according to the direction or position of the living body It can be used for a sensor and a position estimation method mounted on a device, a monitoring device that detects invasion of a living body, and the like.

1, 1a, 1A sensor 10, 10-1, 10-2, 10-N _T transmitter station 11, 11-1, 11- _NT transmitter 12-1, 12- _NT transmitter antenna 20-1, 20- _{2,20-3,20-4,20-N,} 20-N _R receiving station _21-1,21-N, 21-N _R receive antennas _22-1,22-N, 22-N _R receivers 23- 1,23-N, 23-N _R complex transfer function calculation unit 24a first circuit 24-1, 24-N, 24-NR _R biological component extraction unit 25a second circuit 25-1, 25-N, 25-N _R position spectrum function calculation unit 30, 30A Position estimation unit 30a Third circuit 40 Living body 50 Transmission timing control unit 60, 70 Detection range

Claims (6)

One or more transmitting stations each having a transmitting antenna;
A plurality of receiving stations each having a receiving array antenna;
A first circuit for extracting a biological component that is a signal component transmitted from the transmitting antenna and reflected by one or more living organisms from signals observed by the receiving array antenna of each of the plurality of receiving stations;
A second circuit that calculates a position spectrum function that is an evaluation function for the position of the one or more living bodies viewed from each of the plurality of receiving stations, from each of the biological components extracted by the first circuit;
A plurality of the position spectrum functions calculated by the second circuit are integrated into one function, and one or more local maximum values of the integrated position spectrum function are calculated to estimate the position of the one or more living bodies. With 3 circuits,
Sensor. The one or more transmitting stations are two or more transmitting stations;
Each of the two or more transmitting stations has a transmitting array antenna composed of two or more transmitting antennas.
The sensor according to claim 1. And a fourth circuit that controls transmission timing so that none of the two or more transmitting stations simultaneously perform transmission from the transmission array antenna.
The sensor according to claim 2. The circuit for estimating the position of the one or more living bodies integrates the calculated plurality of position spectrum functions into one function by multiplying or adding to each other.
The sensor according to claim 1. The circuit for calculating the position spectrum function calculates the position spectrum function based on a MUSIC (Multiple Signal Classification) algorithm.
The sensor of any one of Claims 1-4. A signal component transmitted from a transmitting antenna element of one or more transmitting stations and reflected by one or more living bodies from signals observed by the receiving array antenna of each of a plurality of receiving stations each having a receiving array antenna. Extracting a biological component;
Calculating a position spectrum function that is an evaluation function for the position of the one or more living bodies viewed from each of the plurality of receiving stations, from each of the biological components extracted in the extracting step;
Integrating the plurality of position spectrum functions calculated in the calculating step into one function and calculating one or more local maximum values of the integrated position spectrum function to estimate the position of the one or more living bodies; Including
Position estimation method.

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