Vital sign measurement device and vital sign measurement method

Abstract

This vital sign measurement device is provided with: a single infrared sensor (1) that acquires an infrared image of a target object, recognizes a living body from the acquired infrared image, estimates the body temperature and two-dimensional orientation of the recognized living body, and outputs a final vital sign output unit (3); the single radar sensor (2) is synchronized with the infrared sensor in time and is arranged close to the infrared sensor. A signal separation unit (222) that separates the acquired reception signal into a moving object signal and a stationary object signal; and a moving object estimation unit (223) that estimates the distance, velocity, and two-dimensional orientation of the moving object from the moving object signal and detects the moving object. And a radar vital sign estimation unit (224) that estimates the position, respiratory rate, and heart rate of the living body from the stationary object signal on the basis of the detection result of the detected moving object. The final vital sign output unit (3) acquires and outputs the estimated position, respiratory rate, heart rate, and body temperature of the living body.

Description

Technical Field

[0001] The present disclosure relates to vital sign measurement technology. Background Art

[0002] There is a measurement system that combines a single infrared sensor with a plurality of radar sensors to measure the vital signs of a plurality of subjects (see Non-Patent Document 1). In addition, in the present disclosure, the term "vital sign" is used as a term representing the vital sign.

[0003] The infrared sensor in the measurement system has a sensitivity sensor that receives infrared rays emitted from the measured person and outputs the received light signal. The infrared sensor can estimate the number and position of the measured person even under low illumination conditions while taking privacy into consideration.

[0004] The radar sensor in the measurement system has an antenna, which transmits microwaves or millimeter waves toward a person to be measured in the room, receives reflected waves as microwaves or millimeter waves reflected by the person to be measured, and outputs a reception signal of the reflected waves. In addition, the radar sensor has: a first mixer that extracts an in-phase signal included in the reception signal output from the antenna; a second mixer that extracts an orthogonal signal included in the reception signal output from the antenna; and a signal processing device that generates a complex signal including the in-phase signal and the orthogonal signal. Based on the estimation result of the position of the person to be measured by the infrared sensor, the respiratory rate and heart rate of the plurality of persons to be measured are estimated using the plurality of complex signals obtained from the plurality of radar sensors.

[0005] Prior art literature

[0006] Non-patent literature

[0007] Non-patent literature 1: De-Ming Chian, Chao-Kai Wen, Chang-Jen Wang, Ming-Huan Hsu, and Fu-Kang Wang, "Vital Signs Identification System with Doppler Radars and Thermal Camera," IEEE Transactions on Biomedical Circuits and Systems, vol.16, no.1, pp.153-167, Feb. 2022. Summary of the invention

[0008] Problem that the invention aims to solve

[0009] The measurement system disclosed in non-patent document 1 involves measuring the vital signs of multiple subjects sitting densely in a room. In order to detect the vital signs of multiple subjects densely, it is necessary to use multiple radar sensors dispersedly arranged in the room, so the measurement system becomes costly. On the other hand, in elderly care in elderly homes with services, it is usually rare for multiple subjects to measure their vital signs, and in most cases it is sufficient to always measure the vital signs of one elderly person. In this case, there is a problem that the above-mentioned measurement system becomes costly relative to the required performance.

[0010] The present disclosure has been completed based on the recognition of the above problems, and an object of the present disclosure is to provide a vital sign measurement technology capable of detecting the vital signs of a person to be measured using only a single infrared sensor and a single radar sensor.

[0011] Means used to solve problems

[0012] One scheme of the vital sign measuring device of the embodiment of the present disclosure comprises a single infrared sensor, a single radar sensor and a final vital sign output unit, wherein the single infrared sensor comprises: a light receiving unit which receives infrared rays irradiated from an object and obtains an infrared image; a biological body recognition unit which recognizes a biological body from the infrared image obtained in the light receiving unit; and an infrared vital sign estimation unit which estimates the body temperature and two-dimensional orientation of the biological body recognized in the biological body recognition unit, wherein the single radar sensor is synchronized with the infrared sensor in time and is close to the infrared sensor. The single radar sensor is configured to sense the living body, and comprises: a signal acquisition unit, which acquires a reception signal of the reflected wave from an antenna that receives the reflected wave reflected by the target object; a signal separation unit, which separates the reception signal acquired by the signal acquisition unit into a moving object signal and a stationary object signal; a moving object estimation unit, which estimates the distance, speed and two-dimensional orientation of the moving object based on the moving object signal and detects the moving object; and a radar vital sign estimation unit, which estimates the position, breathing frequency and heart rate of the living body based on the stationary object signal based on the detection result of the moving object detected by the moving object estimation unit.

[0013] The final vital sign output unit obtains the position, breathing rate and heart rate of the organism estimated by the radar vital sign estimation unit, obtains the body temperature of the organism estimated by the infrared vital sign estimation unit, and outputs the obtained position, body temperature, breathing rate and heart rate of the organism.

[0014] Effects of the Invention

[0015] According to the vital sign measurement technology of the embodiment of the present disclosure, it is possible to detect the vital sign of the person being measured using only a single infrared sensor and a single radar sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 1 is a diagram showing the overall configuration of a vital sign measurement device according to the first embodiment.

[0017] Figure 2 This is a hardware configuration diagram of the infrared sensor of the vital sign measurement device according to the first embodiment.

[0018] Figure 3 This is a hardware configuration diagram of the radar sensor of the vital sign measurement device according to the first embodiment.

[0019] Figure 4 This is a diagram showing the configuration of the final vital sign output unit 3 of the vital sign measurement device according to the first embodiment.

[0020] Figure 5 1 is a hardware configuration diagram showing the hardware of the vital sign measurement device according to the first embodiment.

[0021] Figure 6 This is a hardware configuration diagram of a computer when the vital sign measurement device is implemented by software or firmware.

[0022] Figure 7 1 is a flowchart showing a vital sign measurement method as a processing procedure of the vital sign measurement device.

[0023] Figure 8 1 is an explanatory diagram showing up-chirped signals Tx(1) to Tx(N) of hit number Q generated by the signal generator 212a.

[0024] Fig. 9 1 is an explanatory diagram showing a Fourier-transformed signal Ssta(r, g, h, c) of N stationary object reception data in a certain transmission cycle c.

[0025] Fig.10 is an explanatory diagram showing beamforming signals BF(r, c) belonging to the same range bin r.

[0026] Fig.11 : is an explanatory diagram showing the change of the circle fitting error E(r) with respect to the distance bin r.

[0027] Fig.12 3 is an explanatory diagram showing the phase change signal θ(c) in the range bin r0.

[0028] Fig.131 is an explanatory diagram showing each vector used for calculating the inner product value corresponding to a certain adjacent beamforming signal point pair of the beamforming signal BF(r, c) belonging to the same range bin r. DETAILED DESCRIPTION

[0029] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, components marked with the same or similar reference numerals in the drawings have the same or similar structures or functions, and repeated descriptions of such components will be omitted.

[0030] Implementation method 1.

[0031] <Structure>

[0032] Figure 1 is a diagram showing the overall structure of the vital sign measuring device according to Embodiment 1, Figure 2 This is a hardware structure diagram of the infrared sensor 1 of the vital sign measuring device. Figure 3 1 is a hardware configuration diagram of a radar sensor 2 of a vital sign measuring device. As described later, in order to perform beamforming with respect to the two-dimensional orientation of the measuring object detected by the infrared sensor 1 by the radar sensor 2, the infrared sensor 1 and the radar sensor 2 are arranged to be synchronized with each other in time and close to each other. A synchronization signal for achieving time synchronization is supplied from a synchronization signal generating unit (not shown) to the infrared sensor 1 and the radar sensor 2.

[0033] (Vital signs measuring device)

[0034] Figure 1 The vital sign measurement device shown includes an infrared sensor 1 , a radar sensor 2 , and a final vital sign output unit 3 .

[0035] (Infrared sensor)

[0036] Figure 2 The infrared sensor 1 shown includes a light receiving unit 11, a biometric recognition unit 12, and an infrared vital sign estimation unit 13. The light receiving unit 11 includes a plurality of light receiving elements arranged in two dimensions, receives infrared rays irradiated from an object, performs photoelectric conversion on the received signal, and outputs the photoelectrically converted signal as an infrared image signal to the biometric recognition unit 12. The biometric recognition unit 12 performs biometric recognition such as human recognition or animal recognition by subjecting the infrared image signal to image recognition processing using machine learning or the like, and outputs the recognition result as a biometric recognition result to the infrared vital sign estimation unit 13. The infrared vital sign estimation unit 13 estimates the body temperature of the detected organism and the two-dimensional position of the organism by using the biometric recognition result. The biometric recognition unit 12 and the infrared vital sign estimation unit 13 are similar to the radar vital sign measurement unit 22 described later, for example, by Figure 6The processor 62 and memory 61 shown are implemented. The memory 61 stores programs for implementing the processing of the biological body recognition unit 12 and the infrared vital sign estimation unit 13 and the learned model. The learned model is a model that has learned the relationship between the infrared image and the biological body. The processor 62 reads out and executes the program stored in the memory 61 to implement the processing of the biological body recognition unit 12 and the infrared vital sign estimation unit 13.

[0037] (Radar sensor)

[0038] Figure 3 The radar sensor 2 shown includes a transceiver 21 and a radar vital sign measuring unit 22 .

[0039] (Send and Receive Department)

[0040] The transceiver unit 21 includes N antennas 211-1 to 211-N, a signal transmitter 212, N circulators 213-1 to 213-N, and N signal receivers 214-1 to 214-N. N is an integer greater than 2. The antennas are respectively transceiver antennas. Figure 3 The radar sensor 2 shown in the figure has N antennas in order to improve the resolution of the received signal by MIMO (Multiple-Input Multiple-Output). Moreover, the antennas are used as both the transmitting antenna and the receiving antenna. However, this is just an example, and the radar sensor 2 may also have a transmitting antenna and a receiving antenna separately.

[0041] When the transmission wave is radiated from the radar sensor 2, one antenna that radiates the transmission wave is selected from the antennas 211-1 to 211-N. The transmission order of the transmission wave in the antenna is determined. For example, the transmission order is determined to be the order of antenna 211-1, antenna 211-2, ..., antenna 211-n. However, this is just an example, and for example, the transmission order may also be determined to be the order of antenna 211-n, ..., antenna 211-2, antenna 211-1.

[0042] (antenna)

[0043] Antenna 211-n (n=1, ..., N) radiates the transmission wave of the transmission signal output from circulator 213-n to the space where the target object exists. The transmission wave radiated from antenna 211-n is reflected by the target object. The target object includes not only the measured person existing in the space, but also the walls of the room forming the space or the stationary objects such as the table existing in the space.

[0044] The antennas 211 - 1 to 211 -N respectively receive reflected waves reflected by the target object, and output reception signals of the reflected waves to the circulator.

[0045] (Signal sending unit)

[0046] The signal transmission unit 212 includes a signal generator 212a and an output destination selection unit 212b. The signal transmission unit 212 sequentially selects one antenna 211-n that radiates a transmission wave from the N antennas. The signal transmission unit 212 outputs a transmission signal to a circulator 213-n connected to the selected antenna 211-n so that the transmission wave is radiated from the selected antenna 211-n to the space where the subject is located.

[0047] (Signal Generator)

[0048] The signal generator 212a generates, for example, a transmission signal whose frequency changes with the passage of time or a pulse transmission signal. The transmission signal whose frequency changes with the passage of time may be, for example, a signal having an up-chirp or a down-chirp. The signal generator 212a outputs the transmission signal to the output destination selection unit 212b.

[0049] (Output destination selection section)

[0050] The output destination selection unit 212 b outputs the transmission signal generated by the signal generator 212 a to the circulator 213 - n connected to the antenna 211 - n which is to radiate the transmission wave next among the N circulators 213 .

[0051] (Circulator)

[0052] The circulator 213-n (n=1, ..., N) outputs the transmission signal output from the output destination selection unit 212b to the antenna 211-n. Also, the circulator 213-n outputs the reception signal output from the antenna 211-n to the signal reception unit 214-n.

[0053] (Signal receiving unit)

[0054] The signal receiving unit 214-n (n=1, ..., N) performs reception processing on the reception signal output from the circulator 213-n. The reception processing includes, for example, down-converting the frequency of the reception signal and converting the frequency-converted reception signal from an analog signal to a digital signal.

[0055] The signal receiving unit 214-n outputs the received data S (t, g, h, q, c) as a digital signal to the radar vital sign measuring unit 22. t is the reception time when the antenna 211-n receives the reflected wave. g is a variable for identifying the antenna 211-n that radiated the transmission wave, and g=1, ..., N. h is a variable for identifying the antenna 211-n that received the reflected wave, and h=1, ..., N. q is a variable for identifying the hit number in a certain transmission cycle, and q=1, ..., Q. Q is an integer greater than or equal to 2. c is a variable for identifying the transmission cycle of the transmission wave based on the antennas 211-1 to 211-N, and c=1, ..., C. C is an integer greater than or equal to 2.

[0056] (Radar Vital Signs Measurement Unit)

[0057] The radar vital sign measuring unit 22 includes a signal acquiring unit 221 , a signal separating unit 222 , a moving object estimating unit 223 , and a radar vital sign estimating unit 224 .

[0058] (Signal Acquisition Department)

[0059] The signal acquisition unit 221 acquires the reception data S (t, g, h, q, c) as the reception signals of the reflected waves from the signal reception units 214 - 1 to 214 -N, respectively, and outputs the reception data S (t, g, h, q, c) to the signal separation unit 222 .

[0060] (Signal separation unit)

[0061] The signal separation unit 222 uses the received data S(t, g, h, q, c) to calculate the stationary object received data Ssta(t, g, h, c) and the moving object received data Smov(t, g, h, q, c), outputs the calculated stationary object received data Ssta(t, g, h, c) to the radar vital signs estimation unit 224, and outputs the calculated moving object received data Smov(t, g, h, q, c) to the moving object estimation unit 223.

[0062] (Moving Object Estimation Unit)

[0063] The moving object estimation unit 223 obtains the moving object reception data Smov(t, g, h, q, c) from the signal separation unit 222 and estimates the two-dimensional position of the moving object. The moving object estimation unit 223 outputs the estimated two-dimensional position of the moving object to the radar vital sign estimation unit 224.

[0064] (Radar Vital Signs Estimation Unit)

[0065] The radar vital sign estimation unit 224 includes a stationary determination unit 2241, a Fourier transform unit 2242, a digital beamforming unit 2243, an existence position determination unit 2244, a respiratory rate estimation unit 2245, and a heart rate estimation unit 2246. The radar vital sign estimation unit 224 estimates the position, respiratory rate, and heart rate of the living body from the stationary object reception data Ssta (t, g, h, c) based on the detection result of the moving object detected by the moving object estimation unit 223.

[0066] (Stationary Determination Unit)

[0067] The stationary determination unit 2241 obtains the two-dimensional position of the moving object from the moving object estimation unit 223 and obtains the two-dimensional position estimation result of the living body from the infrared vital sign estimation unit 13. It determines whether the living body recognized by the infrared vital sign estimation unit 13 is stationary, and outputs a stationary determination flag to the Fourier transform unit 2242 if it is determined to be stationary.

[0068] (Fourier Transformation Unit)

[0069] The Fourier transform unit 2242 performs Fourier transform in the time direction on the stationary object reception data Ssta (t, g, h, c) input from the signal separation unit 222 when the stationary determination flag is obtained from the stationary determination unit 2241. As the Fourier transform, for example, there is a fast Fourier transform (FFT: Fast Fourier Transform) or a discrete Fourier transform (DFT: Discrete Fourier Transform). The Fourier transform unit 2242 outputs each Fourier transformed signal Ssta (r, g, h, c) to the digital shaping unit. r is a variable for identifying the distance bin from the vital sign measurement device. r = 1, ..., R. R is an integer greater than 2.

[0070] (Digital Beamforming Unit)

[0071] The digital beamforming unit 2243 obtains the Fourier transformed signal Ssta(r, g, h, c) from the Fourier transform unit 2242, and obtains the result of the two-dimensional position estimation of the living body from the infrared vital sign estimation unit 13. In the digital beamforming unit 2243, the beamforming signal BFsta(r, c) is calculated by performing digital beamforming on the two-dimensional position of the living body obtained from the infrared vital sign estimation unit 13, and is output to the existence position determination unit 2244.

[0072] (Existence location determination unit)

[0073] The existence position determination unit 2244 obtains the beamforming signal BFsta(r, c). The existence position determination unit 2244 estimates the vital sign feature quantity for each distance bin r based on the beamforming signal BFsta(r, c), and calculates the biological slant range (Slant Range) Rbio based on the magnitude of the vital sign feature quantity. The biological signal B(c) in the biological slant range Rbio is output to the respiratory rate estimation unit 2245 and the heart rate estimation unit 2246.

[0074] (Respiratory rate estimation unit)

[0075] The respiratory rate estimation unit 2245 acquires the biological signal B(c) from the existence position identification unit 2244. The respiratory rate RR of the living body is estimated based on the biological signal B(c).

[0076] (Heart rate estimation unit)

[0077] The heart rate estimation unit 2246 acquires the biological signal B(c) from the existence position identification unit 2244. The heart rate HR of the living body is estimated based on the biological signal B(c).

[0078] exist Figure 3 In the embodiment, it is assumed that the signal acquisition unit 221, the signal separation unit 222, the moving object estimation unit 223, and the radar vital sign estimation unit 224, which are the structural elements of the radar vital sign measurement unit 22, are respectively composed of Figure 5 The dedicated hardware implementation shown. That is, it is assumed that the radar vital sign measuring unit 22 is implemented by a signal acquisition circuit 221C, a signal separation circuit 222C, a mobile object estimation circuit 223C, and a radar vital sign estimation circuit 224C. The signal acquisition circuit 221C, the signal separation circuit 222C, the mobile object estimation circuit 223C, and the radar vital sign estimation circuit 224C correspond to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof.

[0079] (Final vital signs output section)

[0080] Figure 4The final vital sign output unit 3 shown in the figure obtains the body temperature estimation result of the biological body from the infrared sensor 1, obtains the position estimation result, the respiratory rate estimation result, and the heart rate estimation result of the biological body from the radar sensor 2, and outputs them to the outside. The final vital sign output unit 3 can also be implemented by a dedicated processing circuit like the radar vital sign measurement unit 22. In addition, as described below in conjunction with the radar vital sign measurement unit 22, for example, Figure 6 The processor 62 and the memory 61 shown are implemented. The memory 61 stores a program for implementing the processing performed by the final vital sign output unit 3, and the processor 62 reads and executes the program stored in the memory 61 to implement the processing performed by the final vital sign output unit 3.

[0081] The components of the radar vital sign measuring unit 22 are not limited to those implemented by dedicated hardware, and the radar vital sign measuring unit 22 may be implemented by software, firmware, or a combination of software and firmware.

[0082] Software or firmware is stored in the computer's memory in the form of a program. A computer refers to hardware that executes a program, such as a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor).

[0083] Figure 6 This is a hardware configuration diagram of a computer when the radar vital sign measurement unit 22 is implemented by software, firmware, or the like.

[0084] When the radar vital sign measuring unit 22 is implemented by software or firmware, the memory stores a program for causing the computer to execute the processing of the signal acquiring unit 221, the signal separating unit 222, the moving object estimating unit 223, and the radar vital sign estimating unit 224. Then, the processor of the computer executes the program stored in the memory.

[0085] In addition, Figure 5 In FIG. 1 , an example is shown in which the components of the radar vital sign measuring unit 22 are respectively implemented by dedicated hardware. Figure 6 , an example is shown in which the radar vital sign measuring unit 22 is implemented by software or firmware. However, this is just an example, and some components of the radar vital sign measuring unit 22 may be implemented by dedicated hardware, and the remaining components may be implemented by software or firmware.

[0086] <Action>

[0087] Next, refer to Figure 7 right Figure 1The operation of the vital sign measuring device shown will be described. Figure 7 1 is a flowchart showing a vital sign measurement method as a processing procedure of the vital sign measurement device.

[0088] exist Figure 7 In step ST1, the infrared sensor 1 estimates the body temperature and two-dimensional orientation of the biological body. More specifically, the light receiving unit 11 of the infrared sensor 1 receives infrared rays emitted from the object through a plurality of light receiving elements arranged two-dimensionally, performs photoelectric conversion on the received signal, and outputs the photoelectric converted signal as an infrared image signal to the biological body recognition unit 12.

[0089] The biometric recognition unit 12 of the infrared sensor 1 specifies the presence and two-dimensional position of a living body in the infrared image by performing image recognition processing using machine learning or the like on the infrared image signal acquired from the light receiving unit 11. The living body includes a human or an animal.

[0090] The infrared vital sign estimation unit 13 of the infrared sensor 1 estimates the two-dimensional orientation observed from the vital sign measurement device of the living body and the body temperature of the living body based on the biological body recognition result, and outputs the estimated result.

[0091] The signal generator 212 a of the signal transmission unit 212 of the radar sensor 2 generates an up-chirp signal or a down-chirp signal as a transmission signal according to, for example, a frequency modulated continuous wave (FMCW) method or a fast chirp modulation (FCM) method.

[0092] exist Figure 3 In the radar sensor 2 shown, as Figure 8 As shown, the signal generator 212a repeatedly transmits radio waves in the number of hits 1 to Q in each transmission cycle c (c=1, ..., C). In addition, in each hit, the chirped signal Tx(n) is repeatedly generated in the number of antennas 211-1 to 211-N. Therefore, the signal generator 212a generates a total of N×Q×C chirped signals Tx(n). Figure 8 In the example, N=3. The signal generator 212a up-converts the frequency of the generated up-chirped signal Tx(n) (n=1, ..., N) into a high frequency band signal, and outputs the up-converted signal as a transmission signal Tx'(n) to the output destination selection unit 212b. The high frequency band is, for example, a millimeter wave band of about 30 to 300 GHz.

[0093] The output destination selection unit 212b obtains the transmission signal Tx'(n) (n=1,...,N) from the signal generator 212a in each hit q (q=1,...,Q) of each transmission cycle c (c=1,...,C). The output destination selection unit 212b outputs the transmission signal Tx'(n) to the circulator 213-n connected to the antenna 211-n that radiates the next transmission wave among the N circulators 213-1 to 213-N. For example, if the antenna 211-n that radiates the next transmission wave is the antenna 211-1, the output destination selection unit 212b outputs the transmission signal Tx'(1) to the circulator 213-1, and if the antenna 211-n that radiates the next transmission wave is the antenna 211-2, the output destination selection unit 212b outputs the transmission signal Tx'(2) to the circulator 213-2. Furthermore, for example, if the antenna 211 - n in the order of radiating the transmission wave next is the antenna 211 -N, the output destination selection section 212 b outputs the transmission signal Tx′(N) to the circulator 213 -N.

[0094] Upon receiving the transmission signal Tx'(n) from the output destination selection unit 212b, the circulator 213-n (n=1, ..., N) outputs the transmission signal Tx'(n) to the antenna 211-n.

[0095] When receiving the transmission signal Tx'(n) from the circulator 213-n, the antenna 211-n (n=1, . . . , N) radiates the transmission wave, which is the radio wave related to the transmission signal Tx'(n), to the space where the object exists. The transmission wave radiated from the antenna 211-n is reflected by the object. That is, the transmission wave radiated from the antenna 211-n is reflected by the wall forming the space in addition to the object being measured. The reflected wave of the object being measured is sometimes reflected by the wall of the room where the object is located.

[0096] In each hit q (q=1,...,Q) of each transmission cycle c (c=1,...,C), one of the N antennas 211-1 to 211-N radiates the transmission wave into space N times in sequence. Therefore, antennas 211-1 to 211-N respectively receive N×Q reflected waves in each transmission cycle c.

[0097] The antenna 211-n (n=1, ..., N) outputs a reception signal including a reflected wave of the target object to the circulator 213-n. The circulator 213-n (n=1, ..., N) outputs the reception signal output from the antenna 211-n to the signal receiving unit 214-n.

[0098] The signal receiving unit 214-n (n=1, ..., N) performs receiving processing on the N×Q received signals output from the circulator 213-n in each transmission cycle c (c=1, ..., C). As the receiving processing on the received signal, the signal receiving unit 214-n, for example, performs processing of converting the received signal after the frequency conversion from an analog signal to a digital signal in addition to down-converting the frequency of the received signal to the frequency of the intermediate frequency band. The signal receiving unit 214-n outputs the received data S (t, g, h, q, c) as N×Q digital signals to the radar vital sign measuring unit 22 in each transmission cycle c. Thus, in each transmission cycle c (c=1, ..., C), a total of N×N×Q (=G×H×Q) received data S (t, g, h, q, c) are provided to the radar vital sign measuring unit 22 from the signal receiving units 214-1 to 214-N.

[0099] In step ST2, the signal acquisition unit 221 of the radar vital sign measurement unit 22 acquires N×N×Q received data S (t, g, h, q, c) from the signal receiving units 214-1 to 214-N in each transmission cycle c (c=1, . . . , C). The signal acquisition unit 221 outputs the N×N×Q received data S (t, g, h, q, c) to the signal separation unit 222 in each transmission cycle c.

[0100] In step ST3, the signal separation unit 222 separates the moving object signal from the stationary object signal. First, the signal separation unit 222 obtains N×N×Q received data S(t, g, h, q, c) from the signal acquisition unit 221 in each transmission cycle c (c=1, . . . , C). Next, the signal separation unit 222 outputs the stationary object received data Ssta(t, g, h, c) averaged between all hits q (q=1, . . . , Q) for the received data S(t, g, h, q, c) to the radar vital sign estimation unit 224. In addition, the signal separation unit 222 outputs the moving object received data Smov(t, g, h, q, c) obtained by subtracting the stationary object received data Ssta(t, g, h, c) from the received data S(t, g, h, q, c) to the moving object estimation unit 223.

[0101] In step ST4, the moving object estimation unit 223 estimates the position of the moving object. First, the moving object estimation unit 223 obtains N×N×Q moving object reception data Smov (t, g, h, q, c) from the signal separation unit 222 in each transmission cycle c (c=1, . . . , C). The moving object estimation unit 223 performs range Doppler processing on the moving object existing in the space based on the obtained N×N×Q moving object reception data Smov (t, g, h, q, c), thereby estimating the distance from the radar sensor 2 to the moving object and the speed of the moving object. The range Doppler processing itself is a well-known technology, so the detailed description is omitted. For example, if the number of moving objects existing in the space is 1, the distance to 1 moving object and the speed of the moving object are estimated. For example, if the first moving object and the second moving object exist in the space as two moving objects, the distance to the first moving object and the speed of the first moving object, and the distance to the second moving object and the speed of the second moving object are estimated. The moving object estimation unit 223 performs angle measurement based on the estimated results of the distance to the moving object and the speed of the moving object, thereby detecting the two-dimensional direction where the moving object exists. The two-dimensional direction is the azimuth direction of the moving object observed from the vital sign measurement device and the elevation direction of the moving object observed from the vital sign measurement device.

[0102] In step ST5, the stillness determination unit 2241 determines whether the living body detected by the infrared sensor 1 is still. To make this determination, the stillness determination unit 2241 obtains the two-dimensional position of the moving object from the moving object estimation unit 223 and obtains the two-dimensional position estimation result of the living body from the infrared vital sign estimation unit 13. If the error between the two-dimensional position of the moving object obtained from the moving object estimation unit 223 and the two-dimensional position of the living body obtained from the infrared vital sign estimation unit 13 is less than a predetermined threshold, the stillness determination unit 2241 determines that the living body detected by the infrared sensor 1 is moving. On the other hand, if the error is greater than the predetermined threshold, the stillness determination unit 2241 determines that the living body detected by the infrared sensor 1 is still, and outputs a stillness determination flag to the Fourier transform unit 2242.

[0103] When the stillness determination flag is obtained from the stillness determination unit 2241 ("Yes" in step ST5), the processing proceeds to step ST6. In step ST6, the Fourier transform unit 2242 performs Fourier transform on the N×N×Q stationary object reception data Ssta(t, g, h, c) in the time direction in each transmission cycle c. In each transmission cycle c, the N stationary object reception data Ssta(t, g, h=n, c) associated with each antenna 211-n are Fourier transformed by the Fourier transform unit 2242, thereby generating N Fourier transformed signals Ssta(r, g, h, c). Fig. 9As shown, the signal Ssta(r, g, h, c) after the Fourier transform by the Fourier transform unit 2242 is a signal indicating the complex power corresponding to the range bin r. Fig. 9 is an explanatory diagram showing N Fourier transformed signals Ssta(r, g, h, c) in a certain transmission cycle c. Fig. 9 In , the horizontal axis represents the range bin and the vertical axis represents the complex power. The Fourier transform unit 2242 outputs N Fourier transformed signals Ssta (r, g, h, c) to the digital beamforming unit 2243 in each transmission cycle c.

[0104] In step ST7, the digital beamforming unit 2243 performs two-dimensional beamforming on the stationary object signal with respect to the biological body detection orientation in the infrared sensor 1, and calculates the beamforming signal BF(r, c). In order to perform such processing, the digital beamforming unit 2243 obtains the Fourier transformed signal Ssta(r, g, h, c) from the Fourier transform unit 2242, and obtains the biological body two-dimensional orientation estimation result from the infrared vital sign estimation unit 13. The digital beamforming unit 2243 calculates the beamforming signal BF(r, c) by performing digital beamforming on the biological body two-dimensional orientation obtained from the infrared vital sign estimation unit 13, and outputs the calculated beamforming signal BF(r, c) to the existence position determination unit 2244.

[0105] More specifically, the digital beamforming unit 2243 performs a two-dimensional azimuth beamforming process based on DBF (Digital Beam Forming) for each Fourier transformed signal Ssta (r, g, h, c) according to each distance bin r, toward the two-dimensional orientation of the organism obtained from the infrared vital sign estimation unit 13. The two-dimensional orientation here refers to the azimuth direction and the elevation direction. However, this is just an example, and other methods such as the Capon method may also be used for digital beamforming to perform two-dimensional azimuth beamforming. In addition, the two-dimensional azimuth beamforming process itself is a well-known technology, so a detailed description is omitted. In each transmission cycle c, the digital beamforming unit 2243 outputs the beamforming signal BF (r, c) corresponding to each distance bin r to the existence position determination unit 2244.

[0106] The two-dimensional orientation of the living body can be estimated through the processing so far, so in step ST8, the existing position identification unit 2244 estimates the remaining living body slant distance required for estimating the three-dimensional position of the living body. The position identification processing performed by the existing position identification unit 2244 will be specifically described below.

[0107] Although a breathing signal indicating the breathing of the living body and a heartbeat signal indicating the heartbeat of the living body are superimposed on the reflected wave from the living body, most of the beamformed signal BF(r, c) is the power of the breathing signal.

[0108] The breathing signal is a signal that represents the phase variation caused by the reciprocating motion of the chest of a living body. Therefore, the beamforming signal BF(r, c) belonging to the same range bin (slant range bin) r is a time-varying signal. In the complex signal space, Fig.10 As shown, it performs a reciprocating motion in a circle as time passes. Fig.10 is an explanatory diagram showing the time variation of the phase in the beamforming signal BF(r, c) belonging to the same range bin r. Fig.10 In , the beamforming signal BF(r, c) performs a circular reciprocating motion in the complex signal space. Fig.10 In FIG. 1 , 0 represents the beamforming signal BF(r, c) in the transmission cycle c=1 to C, and C 0s are drawn.

[0109] The existing position determination unit 2244 calculates a fitting circle Circ(r) drawn on the complex plane by the time variation of the phase in the beamforming signal BF(r, c) corresponding to each range bin r (r=1, . . . , R). Specifically, the existing position determination unit 2244 assumes that the complex data representing the beamforming signal BF(r, c) of the transmission cycle c (c=1, . . . , C) is s c , and find the evaluation function J(α, β) shown in the following formula (1) to minimize α, β, thereby calculating the optimal fitting circle Circ(r). α is the center of the fitting circle Circ(r), and β is the radius of the fitting circle Circ(r). c The subscript c is a variable indicating the sending loop.

[0110]

[0111] The evaluation function J(α, β) can be expressed in a matrix form as shown in the following equation (2) by transforming the equation.

[0112]

[0113] In formula (2), * is a mathematical symbol representing complex conjugate.

[0114] The existing position identification unit 2244 estimates the parameter vector p shown in equation (2) using the least square method as shown in the following equation (3).

[0115]

[0116] In the formula (3), + is a mathematical symbol representing a pseudo inverse matrix. The "~" displayed above the p character is a symbol indicating that it is an estimated result of the parameter vector p.

[0117] If the estimation result of the parameter vector p is expressed as in the following equation (4), the existence position determination unit 2244 can obtain the center α of the fitting circle Circ(r) and the radius β of the fitting circle Circ(r) as shown in the following equations (5) and (6). If the center α of the fitting circle Circ(r) and the radius β of the fitting circle Circ(r) are obtained, the fitting circle Circ(r) is calculated.

[0118]

[0119] In equations (5) and (6), Re(□) represents the real part of □ which is a complex number, and Im(□) represents the imaginary part of □ which is a complex number.

[0120] Here, the existing position determination unit 2244 calculates the fitting circle Circ(r) using a circle fitting method called Kasa fit. However, this is just an example, and the existing position determination unit 2244 may calculate the fitting circle Circ(r) using a circle fitting method such as Pratt fit, Taubin fit, or Hyper fit.

[0121] Next, the existing position identification unit 2244 calculates the fitting error E(r) which is the error of the fitting circle Circ(r) as shown in the following equation (7).

[0122]

[0123] In formula (7), α(r) is the center of the fitted circle Circ(r), and β(r) is the radius of the fitted circle Circ(r).

[0124] If a breathing signal representing the breathing of a living body and a heartbeat signal representing the heartbeat of a living body are superimposed on the reflected wave, the radius β of the fitting circle Circ(r) becomes larger and the fitting error E(r) becomes smaller. On the other hand, if the reflected wave is a reflected wave formed by a stationary object such as a wall, that is, a direct wave from the stationary object, the radius β of the fitting circle Circ(r) becomes smaller and the fitting error E(r) becomes larger.

[0125] The existence position determination unit 2244 uses the calculated r fitting errors E(r) as vital sign feature quantities and compares the fitting errors E(r) in the direction of the distance bin r. That is, the existence position determination unit 2244 compares the fitting errors E(r) as vital sign feature quantities between the slant distance bins. Based on the comparison result, the existence position determination unit 2244 estimates the distance bin r0 with the smallest fitting error E(r) as the slant distance to the biological body. Fig.11 is an explanatory diagram showing the change of the fitting error E(r) with respect to the distance bin r. Fig.11 In , the fitting error E(r) is shown to be the smallest at the distance bin r0. Fig.11 In , ● represents the fitting error E(r) in the distance bin r=1~R, and R ● are plotted.

[0126] In step ST9, the respiratory rate estimation unit 2245 estimates the respiratory rate RR of the living body. First, the respiratory rate estimation unit 2245 calculates the respiratory rate RR of the living body based on the beamforming signal BF(r0, c) associated with the distance bin r0 where the living body is located in the transmission cycle c=1 to C. Fig.12 The respiratory rate estimation unit 2245 can use, for example, the AD (Arctangent Demodulation) method or the CSD (Complex Signal Demodulation) method as a method for calculating the phase change signal θ(c) related to the position of the biological body. Next, the respiratory rate estimation unit 2245 estimates the respiratory rate RR of the biological body by performing Fourier transform on the phase change signal θ(c). In addition, the method of estimating the respiratory rate RR using the phase change signal θ(c) is a well-known technology, so the detailed description is omitted.

[0127] In step ST10, the heart rate estimation unit 2246 also calculates the heart rate based on the beamforming signal BF(r0, c) associated with the distance bin r0 where the biological subject is located in the transmission cycle c=1 to C. Fig.12 The heart rate estimation unit 2246 can also use the AD method or the CSD method as a method for calculating the phase change signal θ(c) related to the position of the biological body, but it is not necessary to use the same method as the respiratory rate estimation unit 2245. The heart rate estimation unit 2246 estimates the heart rate HR of the biological body by performing Fourier transform or wavelet transform on the phase change signal θ(c). In addition, the method of estimating the heart rate HR using the phase change signal θ(c) itself is a well-known technology, so the detailed description is omitted.

[0128] In step ST11 , the final vital sign output unit 3 obtains the body temperature estimation result of the living body from the infrared sensor 1 , obtains the position estimation result, respiratory rate estimation result, and heart rate estimation result of the living body from the radar sensor 2 , and outputs these results to the outside.

[0129] Implementation method 2.

[0130] In the second embodiment, the structure is the same as that of the first embodiment, but the radius β(r) of the fitting circle Circ(r) is used as the vital sign feature in the existence position determination unit 2244. The existence position determination unit 2244 uses the calculated R fitting circle radii β(r) as the vital sign feature, compares the fitting circle radii β(r) in the direction of the distance bin r, and estimates the distance bin r0 with the largest fitting circle radius β(r) as the slant distance to the biological body.

[0131] Implementation method 3.

[0132] In the third embodiment, the structure is the same as that of the first embodiment, but the occupied angle width W(r) occupied by the beamforming signal BF(r, c) in the transmission cycle c=1 to C on the fitting circle Circ(r) is used as the vital sign feature quantity in the existence position determination unit 2244. The existence position determination unit 2244 uses the calculated R occupied angle widths W(r) as the vital sign feature quantity, compares the occupied angle widths W(r) in the range bin r direction, and estimates the range bin r0 with the largest occupied angle width W(r) as the slant distance to the biological body. Fig.10 The occupied angle width W(r) is shown as an example.

[0133] Implementation method 4.

[0134] In the fourth embodiment, the structure is the same as that of the first embodiment, but the inner product of the radial direction vector A(c) from the circle center α(r) of the fitting circle Circ(r) toward each signal point (time-varying signal point) of the beamforming signal BF(r, c) and the line segment vector B(c) connecting the adjacent signal points of the beamforming signal BF(r, c) is calculated, and the total value I(r) of the inner product values ​​corresponding to all the beamforming signal points is used as the vital sign feature value in the location determination unit 2244. The total value I(r) of the inner product values ​​is calculated by equation (8). When the fitting error of the beamforming signal point with respect to the fitting circle Circ(r) is small, each inner product value becomes smaller, and therefore, as a result, the total value I(r) of the inner product values ​​also becomes smaller.

[0135]

[0136] The existence position determination unit 2244 uses the calculated R inner product sum values ​​I(r) as the vital sign feature, compares the inner product sum values ​​I(r) in the direction of the distance bin r, and estimates the distance bin r0 with the smallest inner product sum value I(r) as the slant distance to the biological body. Fig.13 , examples of each vector used for calculation of the inner product value corresponding to a certain pair of adjacent beamforming signal points are illustrated.

[0137] Furthermore, the embodiments may be combined, or each embodiment may be modified or omitted as appropriate.

[0138] Industrial Applicability

[0139] The vital sign measuring technology disclosed in the present invention can be used as a vital sign measuring device for measuring the vital signs of one elderly person or a small number of elderly people.

[0140] Description of Reference Numerals

[0141] 1 infrared sensor, 2 radar sensor, 3 final vital sign output unit, 11 light receiving unit, 12 biometric recognition unit, 13 infrared vital sign estimation unit, 21 transceiver unit, 22 radar vital sign measurement unit, 61 memory, 62 processor, 211-n antenna, 212 signal transmission unit, 212a signal generator, 212b output destination selection unit, 213-n circulator, 214-n signal reception unit, 221 signal acquisition unit, 221C signal acquisition circuit, 222 signal separation unit, 222C signal separation circuit, 223 moving object estimation unit, 223C moving object estimation circuit, 224 radar vital sign estimation unit, 224C radar vital sign estimation circuit, 2241 stationary determination unit, 2242 Fourier transform unit, 2243 digital beamforming unit, 2244 existence position determination unit, 2245 respiratory rate estimation unit, 2246 heart rate estimation unit.

Claims

1. A vital sign measuring device, wherein: The vital sign measuring device comprises a single infrared sensor, a single radar sensor and a final vital sign output unit. The single infrared sensor has: a light receiving unit that receives infrared rays emitted from a target object to obtain an infrared image; a biological body recognition unit that recognizes a biological body from the infrared image obtained by the light receiving unit; as well as an infrared vital sign estimation unit, which estimates the body temperature and two-dimensional position of the living being identified in the living being recognition unit, The single radar sensor is synchronized with the infrared sensor in time and is disposed close to the infrared sensor to sense the living body. The single radar sensor has: a signal acquisition unit that acquires a reception signal of the reflected wave from an antenna that receives the reflected wave reflected by the target object; a signal separation unit that separates the received signal acquired by the signal acquisition unit into a moving object signal and a stationary object signal; a moving object estimation unit, which estimates the distance, speed and two-dimensional position of the moving object according to the moving object signal, and detects the moving object; as well as a radar vital sign estimation unit that estimates the position, breathing frequency, and heart rate of the living body from the stationary object signal based on the detection result of the moving object detected by the moving object estimation unit, The final vital sign output unit obtains the position, breathing rate and heart rate of the organism estimated by the radar vital sign estimation unit, obtains the body temperature of the organism estimated by the infrared vital sign estimation unit, and outputs the obtained position, body temperature, breathing rate and heart rate of the organism.

2. The vital signs measuring device according to claim 1, wherein: The radar vital sign estimation unit includes a digital beamforming unit. When the two-dimensional direction estimated by the infrared vital sign estimation unit cannot detect the movement of the moving object detected by the moving object estimation unit of the radar sensor, the digital beamforming unit performs digital beamforming on the stationary object signal according to the estimated two-dimensional direction.

3. The vital signs measuring device according to claim 2, wherein: The radar vital sign estimation unit compares vital sign feature quantities between slant range bins in the stationary object signal after beamforming, determines that a living body exists at the slant range bin where the vital sign feature quantity takes a maximum or minimum value, and estimates the respiratory frequency and heart rate at the slant range bin.

4. The vital signs measuring device according to claim 3, wherein: A circle fitting is performed on the complex plane on the time variation signal of the signal at each slant range bin of the stationary object signal after beamforming, and the error between the fitting circle and the time variation signal is used as the vital sign feature.

5. The vital signs measuring device according to claim 3, wherein: A circle fitting is performed on the complex plane on the time variation signal of the signal at each slant range bin of the stationary object signal after beamforming, and the radius of the fitting circle is used as the vital sign feature.

6. The vital signs measuring device according to claim 3, wherein: A circle fitting is performed on the complex plane on the time variation signal of the signal at each slant range bin of the stationary object signal after beamforming, and the occupied angle width of the time variation signal observed from the center of the fitting circle is used as the vital sign feature.

7. The vital sign measuring device according to claim 3, wherein: Perform circle fitting on the complex plane for the time-varying signal of the signal at each slant range bin of the stationary object signal after beamforming, calculate the inner product of the radial direction vector from the center of the fitting circle toward the time-varying signal point and the line segment vector connecting adjacent time-varying signal points, and take the total value of the inner product values ​​corresponding to all the time-varying signal points as the vital sign feature.

8. A method for measuring vital signs, which is a method for measuring vital signs performed by a vital sign measuring device, the vital sign measuring device comprising a single infrared sensor, a single radar sensor and a final vital sign output unit, the single radar sensor comprising a signal acquisition unit, a signal separation unit, a moving object estimation unit and a radar vital sign estimation unit, wherein: The method for measuring vital signs comprises the following steps: The infrared sensor receives infrared rays emitted from the target object to obtain an infrared image, identifies a living body from the obtained infrared image, and estimates the body temperature and two-dimensional position of the identified living body; The signal acquisition unit acquires a reception signal of the reflected wave from an antenna that receives the reflected wave reflected by the target object; The signal separation unit separates the acquired received signal into a moving object signal and a stationary object signal; The moving object estimation unit estimates the distance, speed and two-dimensional orientation of the moving object based on the moving object signal to detect the moving object; The radar vital sign estimation unit estimates the position, breathing frequency and heart rate of the biological body according to the stationary object signal based on the detection result of the detected moving object; as well as The final vital sign output unit obtains the estimated position, respiratory rate, and heart rate of the living body, as well as the estimated body temperature of the living body, and outputs the obtained position, body temperature, respiratory rate, and heart rate of the living body.

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