Monitoring system

Abstract

To realize a watching system that can reduce noise, and accurately acquire biological information of a person to be measured.SOLUTION: A watching system includes: a first Doppler sensor 10 attached to a building, and directed at a person 44 to be measured; a second Doppler sensor 20 attached to the building, and directed at other than the person 44 to be measured; frequency analysis means for performing frequency analysis on a Doppler signal output from the first Doppler sensor 10, acquiring a first analysis result, performing frequency analysis on a Doppler signal output from the second Doppler sensor 20, and acquiring a second analysis result; and biological information acquisition means for acquiring biological information of the person 44 to be measured, on the basis of a difference between the first analysis result and the second analysis result.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a monitoring system, and more particularly to a monitoring system that measures biological information of a subject using a Doppler sensor. [Background technology]

[0002] Various monitoring systems that measure the biological information of a subject are being studied. Conventional systems that measure cardiac potentials by placing electrodes in contact with the subject place a heavy burden on the subject, so a system that measures biological information without contact using a microwave Doppler sensor is considered promising (see Patent Document 1). A microwave Doppler sensor can obtain biological information such as respiratory rate and heart rate by measuring the subject's body surface and internal movements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-134795 Summary of the Invention [Problem to be solved by the invention]

[0004] However, because microwave Doppler sensors detect minute variations in distance to objects in front of the sensor over a wide range without contact, they have the problem of being susceptible to picking up noise. In particular, since the inventors of the present application are considering installing microwave Doppler sensors inside buildings such as homes, there is concern that the Doppler sensor may detect unexpected movements, such as building sway. If the Doppler sensor detects such noise, the detection accuracy of the subject's biological information will deteriorate.

[0005] The present invention has been made in view of the above-mentioned problems, and its object is to provide a monitoring system that can reduce the noise level and accurately acquire biological information of a subject. [Means for solving the problem]

[0006] In order to solve the above problems, the monitoring system of the present invention includes a first Doppler sensor attached to a building and directed toward the person being measured, a second Doppler sensor attached to the building and directed toward an object other than the person being measured, a frequency analysis means that performs frequency analysis on the Doppler signal output from the first Doppler sensor to obtain a first analysis result and performs frequency analysis on the Doppler signal output from the second Doppler sensor to obtain a second analysis result, and a biometric information acquisition means that acquires biometric information of the person being measured based on the difference between the first analysis result and the second analysis result.

[0007] Here, the first Doppler sensor and the second Doppler sensor may be installed in the same room, or may be installed on a common surface of the room, or may be oriented toward a surface of the room different from the common surface.

[0008] For example, the first Doppler sensor and the second Doppler sensor may be mounted on the ceiling of the room, and the second Doppler sensor may be directed towards the floor of the room.

[0009] The first and second analysis results may indicate signal strength for each frequency, and the biological information acquiring means may identify a frequency at which a difference between the signal strength indicated by the first analysis result and the signal strength indicated by the second analysis result satisfies a predetermined condition. [Effects of the Invention]

[0010] According to the present invention, the biological information of the subject is obtained based on the difference between the first analysis result and the second analysis result, so that the noise level can be reduced and the biological information of the subject can be obtained with high accuracy. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a configuration diagram of a monitoring system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a Doppler sensor. [Figure 3] FIG. 4 is a diagram illustrating an example of the frequency spectrum of a Doppler signal output from a first Doppler sensor. [Figure 4] FIG. 10 is a diagram illustrating an example of the frequency spectrum of a Doppler signal output from a second Doppler sensor. [Figure 5] FIG. 5 is a diagram illustrating the difference between the frequency spectra shown in FIGS. 3 and 4. [Figure 6] FIG. 2 is an operation flow diagram of the monitoring system according to the embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

[0013] FIG. 1 is a configuration diagram of a monitoring system according to an embodiment of the present invention. The monitoring system according to this embodiment is installed in, for example, a building, primarily a home, and a first Doppler sensor 10 and a second Doppler sensor 20 are attached to a ceiling 41 of a room 40 in the home. The first Doppler sensor 10 and the second Doppler sensor 20 are connected to a computer 30 via a wired or wireless connection. The computer 30 includes a CPU, memory, and a communication card, and operates according to a program. The computer 30 may be installed in the room 40 or in another room. The computer 30 may also be a cloud or other computer resource outside the home. In this case, the first Doppler sensor 10 and the second Doppler sensor 20 are connected to the computer 30 via a communication network such as the Internet.

[0014] A bed 43 is placed on the floor 42 of the room 40, and a resident, a subject 44, sleeps on the bed 43. The first Doppler sensor 10 is attached above the bed 43 and faces directly below, i.e., toward the subject 44. Preferably, the first Doppler sensor 10 faces the chest of the subject 44. Meanwhile, the second Doppler sensor 20 is provided facing a portion of the floor 42 other than the subject 44, preferably a portion where the bed 43 is not placed, and the bed 43 is not present within the detection range of the second Doppler sensor 20. Note that, although the subject 44 sleeps on the bed 43 in this example, the present invention is also applicable when the subject 44 sleeps on Japanese-style bedding. The first Doppler sensor 10 and the second Doppler sensor 20 may be attached to the floor or the wall.

[0015] 2 is a configuration diagram of the first Doppler sensor 10 and the second Doppler sensor 20. Each of the first Doppler sensor 10 and the second Doppler sensor 20 includes an oscillator 11, a transmitting antenna 15, a receiving antenna 16, an I / Q detector 12, a filter 13, and an A / D converter 14. The oscillator 11 oscillates a sine wave signal, for example, in the 24 GHz band, and the transmitting antenna 15 emits a weak microwave downward. The microwave reflected by an object such as a subject 44, a bed 43, or a floor 42 is received by the receiving antenna 16, and the received signal is input to the I / Q detector 12. The sine wave signal output from the oscillator 12 is also input to the I / Q detector 12. The sine wave signal from the oscillator 12 is split into two signals with a phase difference of 90 degrees, and each signal is mixed with the received signal, thereby generating the I and Q components of the Doppler signal. High frequency components are removed from the I and Q components by a filter 13, and the components are converted into digital form by an A / D converter 14. The digital I and Q components are transmitted to a computer 30 via a communication module or the like (not shown). Here, it is desirable that the oscillators 11 of the first Doppler sensor 10 and the second Doppler sensor 20 oscillate sine wave signals at frequencies that are sufficiently separated to prevent mutual interference.

[0016] When the computer 30 receives I and Q component data of the Doppler signals from the first Doppler sensor 10 and the second Doppler sensor 20 over a certain period of time, it applies frequency analysis processing such as FFT (Fast Fourier Transform) to calculate the signal strength for each frequency. The frequency analysis processing may be applied to a complex signal over a certain period of time with the I component as the real part and the Q component as the imaginary part, or to data over a certain period of time of the I or Q component with the higher signal strength.

[0017] 3 is a diagram showing a frequency spectrum (analysis result) of the first Doppler sensor 10 generated by the computer 30. As shown in the figure, a peak P1 corresponding to the respiratory rate appears at about 0.2 Hz, and a peak P2 corresponding to the heart rate appears at about 1.1 Hz. However, there is noise around these peaks P1 and P2, and the S / N ratio is not sufficient.

[0018] Fig. 4 is a diagram showing a frequency spectrum (analysis result) related to the second Doppler sensor 20, generated by the computer 30. The peaks P1 and P2 shown in Fig. 3 do not appear because the subject 44 is not present in the measurement range of the second Doppler sensor 20. Fig. 4 shows only a frequency spectrum equivalent to the noise shown in Fig. 3.

[0019] After acquiring the frequency spectra of the first Doppler sensor 10 and the second Doppler sensor 20, the computer 30 calculates the difference between them. FIG. 5 shows the difference between the frequency spectra. The difference spectrum shown in FIG. 5 also shows peaks P1 and P2 at the same positions (frequencies) as peaks P1 and P2 shown in FIG. 3. Furthermore, compared to the frequency spectrum in FIG. 3, the noise around peaks P1 and P2 has lower signal strength. Therefore, the S / N ratio is improved in the difference spectrum. This allows accurate extraction of the heart rate and respiratory rate. To approximate the noises acquired by the first Doppler sensor 10 and the second Doppler sensor 20 as closely as possible, the first Doppler sensor 10 and the second Doppler sensor 20 are preferably mounted on a common surface of the same room, i.e., the same surface (here, the ceiling 41). Furthermore, the first Doppler sensor 10 and the second Doppler sensor 20 are preferably mounted facing a surface (here, the floor, which is the opposing surface) different from the mounting surface (common surface). Without being limited to this, the second Doppler sensor 20 can also be installed in a room other than the room in which the first Doppler sensor 10 is installed.

[0020] 7 is a processing flow diagram in the computer 30. The processing shown in the diagram is realized by the computer 30 executing a biometric information extraction program according to an embodiment of the present invention. The processing shown in the diagram is performed, for example, at regular intervals.

[0021] First, the computer 30 acquires a Doppler signal (first Doppler signal) transmitted from the first Doppler sensor 10 for a certain period of time (S101). For example, the computer 30 acquires a Doppler signal transmitted from the first Doppler sensor 10 from the current time to a time a predetermined time ago. Furthermore, the computer 30 also acquires a Doppler signal (second Doppler signal) transmitted from the second Doppler sensor 20 for a certain period of time (S102). The processing of S101 and S102 may be reversed. For example, the computer 30 acquires a Doppler signal transmitted from the second Doppler sensor 10 from the current time to a time a predetermined time ago. That is, the reception period of the Doppler signal acquired in S101 and the reception period of the Doppler signal acquired in S102 overlap, and are preferably the same.

[0022] Next, the computer 30 performs FFT or other frequency analysis processing on the first Doppler signal (S103). Furthermore, the computer 30 also performs FFT or other frequency analysis processing on the second Doppler signal (S104). The processing of S103 and S104 may be performed in reverse order. Thereafter, the difference between the results of S103 and S104 is calculated (S105). That is, the difference in signal strength is calculated for each frequency. Then, the frequency at which the difference in S105 satisfies a predetermined condition is identified (S106). For example, the frequency at which the difference in S105 is largest and the frequency at which the difference in S105 is second largest may be identified. In this case, for example, the higher frequency may correspond to the heart rate, and the lower frequency may correspond to the respiratory rate.

[0023] The computer 30 then calculates the respiration rate and heart rate by calculating the inverse of the frequency determined in S106 (S107). If the calculated respiration rate and heart rate are not within the normal range, a remote caregiver may be notified or an alarm may be sounded in the home.

[0024] According to the monitoring system described above, by providing a second Doppler sensor 20 directed at an object other than the subject 44 and using the frequency spectrum of this second Doppler sensor 20, it is possible to improve the S / N ratio of the first Doppler sensor 10 directed at the subject 44. This makes it possible to reduce noise and obtain the subject's biological information with high accuracy.

[0025] The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above description, the first Doppler sensor 10 and the second Doppler sensor 20 use microwaves, but they may use electromagnetic waves of other wavelengths, such as millimeter waves.

[0026] In the above explanation, the monitoring system is mainly installed in homes, but it can also be installed in non-residential buildings such as clinics and nursing homes.

[0027] 6 are performed at regular intervals, a vibration sensor may be provided in the room 41, and the processes of S103 to S107 may be performed only when the vibration sensor detects vibrations equal to or greater than a threshold value. This reduces the processing load on the computer 30. [Explanation of symbols]

[0028] 10 first Doppler sensor, 11 oscillator, 12 I / Q detector, 13 filter, 14 A / D converter, 15 transmitting antenna, 16 receiving antenna, 20 second Doppler sensor, 30 computer, 40 room, 43 bed, 44 subject, P1 (respiratory rate) peak, P2 (heart rate) peak.

Claims

1. a first Doppler sensor mounted on the building and directed toward the subject; a second Doppler sensor attached to the building and directed toward a direction other than the subject; a frequency analysis means for performing a frequency analysis on the Doppler signal output from the first Doppler sensor to obtain a first analysis result, and for performing a frequency analysis on the Doppler signal output from the second Doppler sensor to obtain a second analysis result; a biological information acquiring means for acquiring biological information of the subject based on a difference between the first analysis result and the second analysis result; A monitoring system including.

2. The monitoring system according to claim 1, the first Doppler sensor and the second Doppler sensor are provided in the same room; Monitoring system.

3. The monitoring system according to claim 2, the first Doppler sensor and the second Doppler sensor are provided on a common surface of the room; Monitoring system.

4. The monitoring system according to claim 3, the first Doppler sensor and the second Doppler sensor are directed toward a plane different from the common plane in the room; Monitoring system.

5. The monitoring system according to claim 4, the first Doppler sensor and the second Doppler sensor are mounted on a ceiling of the room, and the second Doppler sensor is directed toward a floor of the room. Monitoring system.

6. The monitoring system according to any one of claims 1 to 5, the first and second analysis results indicate signal strength for each frequency; the biological information acquiring means identifies a frequency at which a difference between the signal strength indicated by the first analysis result and the signal strength indicated by the second analysis result satisfies a predetermined condition; Monitoring system.

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