KR20230123699A - Non-contact biosignal measurement system and method - Google Patents

Abstract

The present invention, a MIMO antenna for transmitting and receiving a FMCW type radar signal; Storing raw data obtained by sampling a plurality of chirp signals received by a plurality of receiving antennas after the radar signals transmitted from the plurality of transmitting antennas of the MIMO antenna are reflected by N samples per chirp Raw data collection unit to do; With the raw data stored in the raw data collection unit, two-dimensional data consisting of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) is generated and accumulated on the time axis of the chirp period to form a 3D radar cube Cube generation unit that converts to; a position measuring unit that acquires angle and distance information by performing Range-Fast Fourier Transform (RFFT) and digital beamforming on the data of the 3D radar cube, and specifies a position of a person using the angle and distance information; and a bio-signal detector for obtaining a respiration waveform based on a distance between a person at a specific position and the MIMO antenna in the position measurer.

Description

Non-contact biosignal measurement system and method {NON-CONTACT BIOSIGNAL MEASUREMENT SYSTEM AND METHOD}

The present invention relates to a non-contact bio-signal measuring system and method, and more particularly to a non-contact bio-signal measuring system and method for measuring a bio-signal of a specific target in a non-contact manner using a radar.

BACKGROUND OF THE INVENTION Bio-signals such as respiratory rate and heart rate are one of the factors that can most easily diagnose the state of health of the human body and the presence or absence of health abnormalities. Existing heart rate/respiration measurement devices adopt a method of attaching a sensor to the user's body and measuring the user's heart rate and respiration from the sensor in order to measure the user's heart rate and respiration. However, in the case of the method of attaching the sensor to the body, there is a disadvantage in that the user's movement is not free, a lot of noise is generated according to the user's movement, and it may cause fear to the user. In addition, it was difficult for the general public to measure bio-signals through existing heart rate/respiration measuring devices due to sensor attachment locations and equipment accessibility.

In particular, recently, there is a need to diagnose sleep apnea, which is a disease in which breathing is temporarily stopped during sleep, and furthermore, there is a need to monitor the health status by measuring the actual number or volume of breathing during sleep.

In this regard, Korean Patent Registration No. 10-2289031 discloses a method and apparatus for detecting vital signals using radar. The prior art document uses a CW (Continuous Wave) type radar signal to band-pass filter the received signal into a heart rate frequency band, a respiratory frequency band, and a heart movement frequency band, respectively. , It is characterized by providing a method and apparatus for detecting vital signals using a radar capable of accurately measuring heart movements.

As described above, a number of prior literatures for non-contact measurement of biosignals using radar have been proposed. However, since the prior art measures bio-signals based on distance, it may be difficult to accurately measure signals from people at the same distance as noise. In addition, in order to solve this problem, the method of launching a radar beam to a person located in a predetermined direction and distance has limitations in easy use by ordinary people because it is difficult to set the equipment installation location and the user's location.

Korean Patent Registration No. 10-2289031

An object of the present invention is to measure a user's biosignal in a non-contact manner using an FMCW radar.

Another object of the present invention is to provide a non-contact bio-signal measurement system without difficulty in measuring bio-signals even when installed and used by ordinary people.

In order to achieve the above object, the present invention provides a MIMO antenna for transmitting and receiving FMCW type radar signals; Storing raw data obtained by sampling a plurality of chirp signals received by a plurality of receiving antennas after the radar signals transmitted from the plurality of transmitting antennas of the MIMO antenna are reflected by N samples per chirp Raw data collection unit to do; With the raw data stored in the raw data collection unit, two-dimensional data consisting of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) is generated and accumulated on the time axis of the chirp period to form a 3D radar cube Cube generation unit that converts to; a position measuring unit that obtains angle and distance information by performing Range-Fast Fourier Transform (RFFT) and digital beamforming operations on the data of the 3D radar cube, and specifies a person's position with the angle and distance information; and a bio-signal detector for obtaining a respiration waveform based on a distance between a person at a specific position and the MIMO antenna in the position measurer.

Preferably, the bio-signal detection unit performs digital beamforming operation to extract data including angle and distance information of a specific person from the position measuring unit from a 3D radar cube, and obtains a breathing waveform with the extracted data. there is.

Preferably, the MIMO antenna is composed of a plurality of transmit antennas and a plurality of receive antennas, and the bio-signal detection unit obtains angle and distance information of a specific person from among a plurality of channels composed of the transmit antennas and the receive antennas. A digital beamforming operation may be performed using only a channel for receiving data including data.

Preferably, the MIMO antenna may be disposed on a rear surface of a target to be measured.

Preferably, the bio-signal detector may detect the number of peaks of the measured respiration waveform or perform FFT to monitor the number of respirations per minute.

Preferably, the bio-signal detection unit may monitor the number of breaths per minute by filtering a respiration waveform into a respiration frequency band.

Preferably, the bio-signal detector may obtain a heartbeat waveform as a difference between a respiration waveform before and after filtering into a respiration frequency band.

Preferably, the bio-signal detection unit may monitor the heart rate per minute by detecting the number of peaks of the measured heart rate waveform.

Preferably, the raw data collection unit may maintain storage of raw data received within 20 seconds and delete other raw data.

In addition, the present invention samples a plurality of chirp signals received by a plurality of receiving antennas after reflecting radar signals transmitted from a plurality of transmitting antennas of a MIMO antenna by N per chirp, and obtains raw data Raw data collection step of acquiring and storing ; The raw data stored in the raw data collection step generates two-dimensional data composed of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) and accumulates on the time axis of the chirp period to obtain a 3D radar cube Cube generation step of converting to; A position measurement step of obtaining angle and distance information by performing Range-Fast Fourier Transform (RFFT) and digital beamforming on the data of the 3D radar cube, and specifying a position of a person with the angle and distance information; and a biological signal detection step of acquiring a respiration waveform based on the distance between a person at a specific location and the MIMO antenna in the location measurement step.

According to the present invention, there is an advantage in that a person's bio-signal can be measured in a non-contact manner using the FMCW radar.

In addition, the present invention has an advantage in that it is possible to accurately measure the biosignal because it is possible to remove noise interference caused by people around by measuring the biosignal of a person at a specific location using a MIMO antenna and digital beamforming.

1 shows a configuration diagram of a non-contact biosignal measurement system according to an embodiment of the present invention.
2 shows a configuration diagram of a MIMO antenna according to an embodiment of the present invention.
3 shows a method for obtaining raw data by a raw data collection unit according to an embodiment of the present invention.
4 shows a method of converting raw data into a 3D cube by a cube generator according to an embodiment of the present invention.
5 shows transmission and reception channels of a MIMO antenna according to an embodiment of the present invention.
6 shows a respiratory rate extraction algorithm according to an embodiment of the present invention.
7 shows a heart rate extraction algorithm according to an embodiment of the present invention.
8 shows a flowchart of a non-contact biosignal measurement method according to an embodiment of the present invention.

Hereinafter, the present invention will be described in detail with reference to the contents described in the accompanying drawings. However, the present invention is not limited or limited by exemplary embodiments. The same reference numerals in each figure indicate members performing substantially the same function.

The objects and effects of the present invention can be naturally understood or more clearly understood by the following description, and the objects and effects of the present invention are not limited only by the following description. In addition, in describing the present invention, if it is determined that a detailed description of a known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description will be omitted.

1 shows a configuration diagram of a non-contact biosignal measurement system 10 according to an embodiment of the present invention. Referring to FIG. 1, the non-contact biosignal measuring system 10 includes a MIMO antenna 100, a raw data collection unit 300, a cube generator 500, a position measurement unit 700, and a biosignal detection unit 900. can include

The non-contact bio-signal measurement system 10 may measure bio-signals such as a person's respiratory rate and heart rate in a non-contact manner using a frequency modulated continuous wave (FMCW) radar. The non-contact biosignal measurement system 10 transmits an FMCW radar signal from a transmitter and receives and analyzes a signal reflected back from a person to measure a person's biosignal.

Since the non-contact bio-signal measurement system 10 uses an FMCW radar signal, there is a difference from using a uwb radar signal in measuring a bio-signal using an existing radar. Specifically, FMCW has a frequency domain of 60 GHz to 63 GHz, and in the case of uwb radar, the frequency domain is less than 10 GHz. uwb radar is a pulsed wave radar whereas FMCW radar uses a continuous wave radar. Therefore, the non-contact biosignal measurement system 10 can measure biosignals more accurately than those using uwb radar.

The non-contact biosignal measurement system 10 may output an FMCW radar signal, receive the reflected signal, amplify, frequency synthesize, filter, and digitally sample and convert the reflected signal into an FMCW digital radar signal.

The MIMO antenna 100 may transmit and receive FMCW type radar signals. MIMO is an abbreviation of multiple input multiple output, and the MIMO antenna 100 means a technology capable of minimizing channel loss and interference between users by increasing communication capacity using multiple antennas. The MIMO antenna 100 separates signals at the same frequency to generate an effect of increasing channel capacity. The MIMO antenna 100 may implement beamforming technology using multiple channels.

2 shows a configuration diagram of a MIMO antenna 100 according to an embodiment of the present invention. Referring to FIG. 4 , the MIMO antenna 100 may include a plurality of transmit antennas 110 and a plurality of receive antennas 130 . The MIMO antenna 100 may form a plurality of transmit/receive channels using the transmit antenna 110 and the receive antenna 130. Preferably, the MIMO antenna 100 includes three transmit antennas 110 and four transmit/receive channels. It may be configured as a receiving antenna 130. The MIMO antenna 100 may form 12 transmission/reception channels using the transmission antenna 110 and the reception antenna 130 .

The MIMO antenna 100 may be placed on the back of a target to be measured. According to this embodiment, it is possible to increase the accuracy of bio-signal measurement by minimizing the movement of an object or person between a target to be measured and the MIMO antenna 100 . However, since the signal transmitted from the MIMO antenna 100 passes through the object to be measured, noise caused by an object or person in front of the object to be measured may occur, but this can be solved by RFFT and digital beamforming calculation. That is, it is possible to minimize the influence caused by objects or people around a target to be measured through rear arrangement of the MIMO antenna 100, RFFT, and digital beamforming calculations.

3 shows a method for obtaining raw data by the raw data collection unit 300 according to an embodiment of the present invention. Referring to FIG. 2, the raw data collection unit 300 converts a plurality of chirp signals received by a plurality of receiving antennas by reflecting radar signals transmitted from a plurality of transmission antennas of the MIMO antenna 100 into one Raw data obtained by sampling N per chirp may be stored.

The raw data collection unit 300 may maintain storage of raw data received within 20 seconds and delete raw data stored for more than 20 seconds. In order to measure the respiratory rate and heart rate, the frequency detection resolution must be very precise. However, when the frequency resolution is increased in the FMCW method, a large amount of computation is required for FFT calculation, which may cause hardware limitations. Accordingly, the raw data collection unit 300 may store a total of 4 respiration data assuming that the general public breathes once every 5 seconds on average. The raw data collection unit 300 can save data storage space by storing only 4 breath data, that is, 20 seconds of raw data. In addition, since the raw data collection unit 300 processes only data within 20 seconds, it is possible to solve the hardware limitation problem in calculating the respiratory rate and heart rate.

4 shows a method of converting raw data into a 3D cube by the cube generator 500 according to an embodiment of the present invention. Referring to FIG. 3, the cube generator 500 generates two-dimensional data composed of data corresponding to an ADC sampling index and a receiving antenna index (Rx index) with raw data stored in the raw data collection unit and can be converted into a 3D radar cube by accumulating on the time axis of the chirp period. Since the cube generation unit 500 stores only raw data within 20 seconds in the raw data collection unit 300, only 3D radar cubes with a period of 20 seconds can be maintained.

The position measurement unit 700 obtains angle and distance information by performing Range-Fast Fourier Transform (RFFT) and digital beamforming operations on the data of the 3D radar cube, and can specify the position of a person using the angle and distance information. . More specifically, the location measurement unit 700 may obtain distance information by performing RFFT. The position measuring unit 700 may measure an angle between the MIMO antenna 100 and a person by performing a digital beamforming operation.

The position measurement unit 700 performs Fast Fourier Transform (FFT) transformation on the 3D radar cube obtained from the cube generation unit 500 to obtain a range index, angle index, and chirp index. ) to a 3D cube with axes. The position measurement unit 700 may perform FFT in the following manner.

First, the position measurement unit 700 may perform a first Fourier transform to generate range data, which is a coefficient value for each range index, by Fourier transforming the FMCW digital radar signal in units of sampling periods. Next, the position measurement unit 700 collects the result of the first Fourier transform from the M number of receiving antennas, performs a Fourier transform in units of the receiving antenna distance, and performs a second Fourier transform for generating each data that is a coefficient value for each angle index. can be performed. Finally, the position measuring unit 700 collects the results of the second Fourier transform for C chirps, performs a Fourier transform in units of chirp cycles, and generates time-specific data that is a coefficient value for each chirp index. Performs a third Fourier transform can do.

The position measurement unit 700 may extract distance and angle information from the converted 3D cube. The location measurement unit 700 may specify the location of a person using the strength of a signal in the converted 3D cube.

The position measurement unit 700 may include a clutter removal module. The clutter removal module may perform a clutter removal algorithm by subtracting a range-angle map generated for each chirp in the 3D data cube on the time axis of the chirp period. The position measuring unit 700 can distinguish between a person and an object through the clutter removal module, and can clearly distinguish between a person whose biosignal is to be measured and an object that is not a measurement target.

The clutter removal module uses the fact that the intensity of the signal varies on the time axis of the chirp period when the target is a person in the distance-each map, and the intensity of the signal is maintained constant on the time axis of the chirp period when the target is an object. If the distance-each map generated for the chirp of is subtracted from each other on the time axis, the part where the target is a person remains, and the part where the target is an object can be offset with each other and disappear.

The bio-signal detector 900 may obtain a breathing waveform based on a distance between a person at a specific position in the location measurer 700 and the MIMO antenna. The bio-signal detection unit 900 may perform filtering in a breathing frequency range to extract a breathing waveform.

The biosignal detection unit 900 may perform digital beamforming operation to extract data including angle and distance information of a specific person from the 3D radar cube in the position measuring unit, and obtain a breathing waveform with the extracted data.

Beamforming is a technology for concentrating radio signals in a specific direction by changing the amplitude and phase of multiple supplied signals. Digital beamforming is to control the amplitude and phase of signals transmitted and received through an array antenna in a baseband, and signals in a specific direction can be transmitted and received strongly and signals in other directions can be transmitted and received weakly.

The bio-signal detector 900 may selectively obtain information on a location specified in the position measurer 700 using digital beamforming technology. The bio-signal detection unit 900 can improve the accuracy of bio-signal measurement by partially removing noise generated when the measurer's respiration overlaps with the movements of people around him. The bio-signal detector 900 can accurately obtain angle information as well as distance information of a person whose bio-signal is to be measured using digital beamforming.

5 shows transmission and reception channels of the MIMO antenna 100 according to an embodiment of the present invention. Referring to FIG. 5 , the biosignal detector 900 uses only a channel for receiving data including angle and distance information of a specific person among 12 channels composed of a transmission antenna 110 and a reception antenna 130 to digitally A beamforming operation may be performed.

The biosignal detection unit 900 may selectively acquire only signals of channels including data to be obtained based on an Elevation (EL) axis and an Azimuth (AZ) axis among a plurality of channels formed by the MIMO antenna 100 . Through this, the bio-signal detector 900 can implement digital beamforming.

6 shows a respiratory rate extraction algorithm according to an embodiment of the present invention. Referring to FIG. 6 , the bio-signal detector 900 may monitor the respiratory rate per minute by detecting the number of peaks of the measured respiratory waveform. The bio-signal detector 900 may extract a peak (a point at which the amplitude rises and then falls) of the respiratory waveform using a paek detection algorithm. The biosignal detector 900 may measure the respiratory rate per minute by converting the number of peaks per 20 seconds into the number of peaks per minute.

The bio-signal detector 900 may detect the number of peaks by filtering the respiration waveform in the respiration frequency band. If the bio-signal detection unit 900 uses the distance information obtained from the position measurement unit 700 as it is, the breathing signal includes heartbeat signals and noise, which may reduce accuracy when detecting the number of peaks. can do.

7 shows a heart rate extraction algorithm according to an embodiment of the present invention. Referring to FIG. 7 , the bio-signal detector 900 may obtain a heartbeat waveform as a difference between a respiration waveform before and after filtering into a respiration frequency band. Since there is a difference between the respiratory frequency and the heartbeat frequency, only the heartbeat signal remains when the signal filtered by the respiratory frequency is subtracted from the signal before filtering. Using this, the bio-signal detector 900 may extract a heartbeat signal. The bio-signal detector 900 may perform filtering based on the heartbeat frequency in order to extract a more accurate heartbeat waveform.

The bio-signal detector 900 may monitor the heart rate per minute by detecting the number of peaks of the measured heart rate waveform. A method of detecting the number of peaks of a heartbeat waveform may be the same as a method of detecting the number of peaks of a respiration waveform.

In another embodiment of the present invention, the non-contact biosignal measuring method may include a raw data collection step, a cube creation step, a location measurement step, and a biosignal detection step.

In the raw data collection step, the radar signals transmitted from the plurality of transmission antennas of the MIMO antenna are reflected and the plurality of chirp signals received by the plurality of reception antennas are sampled N per chirp to generate raw data can be obtained and stored. The raw data collection step refers to an operation performed by the raw data collection unit 300 described above.

The cube generation step generates two-dimensional data composed of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) of the raw data stored in the raw data collection step, and accumulates them on the time axis of the chirp period. It can be converted into a 3D radar cube. The cube generating step refers to an operation performed by the cube generating unit 500 described above.

In the position measurement step, RFFT (Range-Fast Fourier Transform) and digital beamforming operation are performed on the data of the 3D radar cube to obtain angle and distance information, and the position of the person can be specified using the angle and distance information. The location measurement step refers to an operation performed by the location measurement unit 700 described above.

In the bio-signal detection step, a breathing waveform may be obtained based on a distance between a person at a specific position and the MIMO antenna in the position measurement step. The bio-signal detection step refers to an operation performed by the bio-signal detection unit 900 described above.

8 shows a flowchart of a non-contact biosignal measurement method according to an embodiment of the present invention. Referring to FIG. 8 , the entire process of the non-contact biosignal measurement method will be described below.

First, raw data is collected by sampling the signal reflected from the target by the FMCW radar signal transmitted through the receiver of the MIMO antenna. Next, the raw data is rearranged to generate a 3D radar cube having ADC sampling index, receiving antenna index (Rx index), and chirk index as axes. At this time, in order to solve the hardware limitation problem according to the amount of computation, only the 3D radar cube corresponding to the last 20 seconds is maintained and other data is deleted. Subsequently, RFFT and digital beamforming (DBF) may be performed on the 3D radar cube to obtain distance information of a person at a specific location. Finally, biosignals such as respiratory rate and heart rate are measured using the obtained distance information.

Although the present invention has been described in detail through representative embodiments, those skilled in the art will understand that various modifications are possible to the above-described embodiments without departing from the scope of the present invention. will be. Therefore, the scope of the present invention should not be limited to the described embodiments and should not be defined, and should be defined by all changes or modifications derived from the claims and equivalent concepts as well as the claims to be described later.

10: Non-contact biosignal measurement system
100: MIMO antenna
110: transmit antenna
130: receiving antenna
300: raw data collection unit
500: cube creation unit
700: position measuring unit
900: biosignal detection unit

Claims (10)

MIMO antenna for transmitting and receiving FMCW type radar signals;
Stores raw data obtained by sampling a plurality of chirp signals received by a plurality of receiving antennas after reflecting radar signals transmitted from a plurality of transmitting antennas of the MIMO antenna by N samples per chirp Raw data collection unit to do;
With the raw data stored in the raw data collection unit, two-dimensional data consisting of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) is generated and accumulated on the time axis of the chirp period to form a 3D radar cube Cube generation unit that converts to;
a position measurement unit that obtains angle and distance information by performing Range-Fast Fourier Transform (RFFT) and digital beamforming operations on the data of the 3D radar cube, and specifies a position of a person using the angle and distance information; and
A non-contact bio-signal measurement system comprising: a bio-signal detector for acquiring a breathing waveform based on a distance between a person at a specific position in the location-measuring unit and the MIMO antenna.
According to claim 1,
The bio-signal detector,
Non-contact biosignal measurement system, characterized in that by performing a digital beamforming operation, the position measurement unit extracts data including angle and distance information of a specific person from a 3D radar cube, and obtains a breathing waveform with the extracted data.
According to claim 2,
The MIMO antenna,
It consists of a plurality of transmit antennas and a plurality of receive antennas,
The bio-signal detector,
Non-contact biometric, characterized in that performing a digital beamforming operation using only a channel through which the position measuring unit receives data including angle and distance information of a specific person among a plurality of channels composed of the transmitting antenna and the receiving antenna signal measurement system
According to claim 1,
The MIMO antenna,
A non-contact biosignal measurement system characterized in that it is disposed on the back of the target to be measured.

According to claim 1,
The bio-signal detector,
A non-contact biosignal measurement system characterized in that the number of peaks of the measured respiration waveform is detected or FFT is performed to monitor the number of respirations per minute.
According to claim 5,
The bio-signal detector,
A non-contact biosignal measurement system characterized in that monitoring the number of breaths per minute by filtering the respiratory waveform into the respiratory frequency band.
According to claim 5,
The bio-signal detector,
A non-contact bio-signal measurement system characterized in that a heartbeat waveform is obtained as a difference between a breathing waveform before and after filtering into a breathing frequency band.
According to claim 6,
The bio-signal detector,
A non-contact biosignal measurement system characterized in that the heart rate per minute is monitored by detecting the number of peaks of the measured heart rate waveform.
According to claim 1,
The raw data collection unit,
A non-contact biosignal measuring system characterized by maintaining the storage of raw data received within 20 seconds and deleting other raw data.
Radar signals transmitted from a plurality of transmit antennas of a MIMO antenna are reflected and a plurality of chirp signals received by a plurality of receive antennas are sampled N per chirp to acquire and store raw data raw data collection step;
The raw data stored in the raw data collection step generates two-dimensional data composed of data corresponding to the ADC sampling index and the receiving antenna index (Rx index) and accumulates on the time axis of the chirp period to obtain a 3D radar cube Cube generation step of converting to;
A position measurement step of obtaining angle and distance information by performing a range-fast Fourier transform (RFFT) and digital beamforming operation on the data of the 3D radar cube, and specifying a position of a person with the angle and distance information; and
A bio-signal detection step of obtaining a breathing waveform based on the distance between a person at a specific position and the MIMO antenna in the location-measuring step; non-contact bio-signal measurement method comprising a.