KR102289031B1 - Method And Apparatus for Vital Signal by Using Radar - Google Patents

Abstract

Disclosed are a method and a device for detecting a vital signal using a radar. An embodiment of the present invention provides a method and a device for detecting a vital signal using a radar, which use a continuous wave (CW) type radar signal to perform band-pass filtering from a received signal to a heartbeat frequency band, a respiration frequency band, and a heart movement frequency band, respectively, thereby accurately measuring a respiration rate, heart rate, and heart movement of a human body from the received signal.

Description

Method And Apparatus for Vital Signal by Using Radar

One embodiment of the present invention relates to a method and apparatus for detecting a vital signal using a radar.

The content described below merely provides background information related to the present embodiment and does not constitute the prior art.

UWB (Ultra WideBand) is a radio technology that uses a wideband frequency, and has various advantages such as high distance resolution, transparency, strong immunity to narrowband noise, and coexistence with other devices that share a frequency.

UWB radar technology refers to a radar technology that transmits an impulse signal of a very short duration with a wideband characteristic in the frequency domain and receives a signal reflected from an object or person to recognize the surrounding situation.

The UWB radar system generates an impulse signal having a time width of several nano-several picoseconds in the signal generator and radiates it at a wide angle or a narrow band angle through a transmitting antenna. The radiated signal is reflected by various objects or people in the environment, and the reflected signal is converted into a digital signal through a receiving antenna and ADC.

Research is underway to utilize UWB radar in many fields. Currently, it is being applied in various fields, such as a medical device for measuring respiration and heart rate, a portable radar device for rescue at a disaster site, and a people counting device that counts the number of people in a certain area. However, the degree of movement according to the heartbeat compared to the movement according to the breathing of a person has a lot of difficulty in measuring the heart rate because the area of the heart movement is small and the signal size is significantly smaller.

The conventional heart rate/respiration measurement apparatus employs a method of attaching a sensor to the user's body in order to measure the user's heart rate and respiration, and measuring the user's heart rate and respiration from the sensor. However, when the sensor is attached to the user's body, there is a disadvantage that the user's movement is not free and a lot of noise is generated according to the user's movement. Accordingly, a device for wirelessly measuring a user's heartbeat and respiration in a short distance using a radar without attaching a sensor to the user's body has been developed and used.

A radar signal may be transmitted to the user using the RF sensor, and a heartbeat signal and a respiration signal of the user may be detected using a Doppler shift of a signal reflected from the user. However, the user's biosignal reflected from the user includes noise according to the user's movement or various noises other than the heartbeat signal or the respiration signal.

Conventionally, as a method for detecting heartbeat and respiration signals, there is a method of detecting heartbeat and respiration signals by selecting a reference signal. That is, if the reference signal of the heartbeat and respiration signal to be detected is preset and then the reference signal is removed from the biosignal, only the noise signal remains. Therefore, the noise signal is removed from the biosignal again to detect the heartbeat signal and the respiration signal. can However, there is a problem in setting the reference signal because it is necessary to assume that the reference signal must include signals of all possible frequency bands and that the characteristics of heartbeat and respiration signals for each user are similar to each other.

In addition, since it is not measuring a contact-type signal that attaches a sensor to the user's body, the amplitude and phase of the signal may change frequently depending on the distance between the RF sensor and the user, so it is necessary to correct the change. There is a problem in that predetermined adaptive filter coefficients must be set for each.

Therefore, there is a need for a technique for more accurately detecting a heartbeat signal and a respiration signal of a user using a radar.

In this embodiment, the heartbeat frequency band, respiration frequency band, and heart movement frequency band are filtered from the reflected signal received using a continuous wave (CW) type radar signal, and the respiration rate and heart rate, which are vital signals of the body, are filtered from the reflected signal. , An object of the present invention is to provide a method and an apparatus for detecting vital signals using radar that can accurately measure body movements.

According to one aspect of the present embodiment, the radar unit for transmitting a radar beam in a preset direction and receiving a reflected signal reflected in response to the radar beam from a body existing in the preset direction; and a control unit for filtering the reflected signal into each preset frequency band and sensing the movement of the heart in the body, the movement of the diaphragm in the body, and the movement of the body based on the filtered signal A vital signal detection device is provided.

According to another aspect of the present embodiment, the process of transmitting a radar beam in a preset direction; receiving a reflected signal reflected in response to the radar beam from a body existing within the preset direction; generating a filtering signal by filtering the reflected signal into each preset frequency band; detecting a movement of the heart in the body based on the filtering signal; detecting a movement of the diaphragm in the body based on the filtering signal; and detecting the movement of the body based on the filtering signal.

As described above, according to the present embodiment, the heartbeat frequency band, the respiration frequency band, and the heart movement frequency band are filtered from the reflected signal received using the continuous wave (CW) type radar signal, and the vital body of the body is obtained from the reflected signal. It has the effect of accurately measuring the signals such as respiration rate, heart rate, and body movement.

1 is a view showing a vital signal detecting apparatus according to the present embodiment.
2 is a view showing a vital signal sensing device to which a dielectric resonant oscillator (DRO) according to the present embodiment is applied.
3 is a diagram illustrating phase noise characteristics according to the present embodiment.
4 is a view for explaining a CW radar according to the present embodiment.
5A, 5B, and 5C are diagrams illustrating a dielectric resonant oscillator (DRO) according to the present embodiment.

Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings.

1 is a view showing a vital signal detecting apparatus according to the present embodiment.

The vital signal detecting apparatus 100 according to the present embodiment detects a vital signal using a radar beam. The vital signal detecting apparatus 100 detects breathing according to the movement of the diaphragm, heartbeat according to the movement of the heart, and body movement by using the vital signal.

The vital signal detecting apparatus 100 senses the heart rate by sensing the movement of the heart. The vital signal sensing device 100 senses the movement of the diaphragm to detect respiration. The vital signal detection apparatus 100 detects the movement of the sensory body.

The vital signal sensing device 100 measures the heartbeat, the number of respirations, and the body movement by measuring the Doppler effect on the movement of the heart, the movement of the diaphragm, and the movement of the body. The vital signal sensing apparatus 100 measures the Doppler effect on the heart movement, the chest diaphragm movement when breathing, and the Doppler effect on the body movement to measure respiration.

The vital signal detection apparatus 100 according to the present embodiment includes a radar unit 110 and a control unit 120 . Components included in the vital signal sensing device 100 are not necessarily limited thereto.

Each component included in the vital signal sensing device 100 may be connected to a communication path connecting a software module or a hardware module inside the device to organically operate with each other. These components communicate using one or more communication buses or signal lines.

Each component of the vital signal sensing apparatus 100 shown in FIG. 1 means a unit for processing at least one function or operation, and may be implemented as a software module, a hardware module, or a combination of software and hardware.

The radar unit 110 emits a radar beam to a body located in a preset direction and distance, and receives a reflected signal reflected from the body in response to the radar beam. The controller 120 filters the reflected signal into each preset frequency band, and then detects the movement of the heart, the movement of the diaphragm in the body, and the movement of the body based on the filtered signal.

2 is a view showing a vital signal sensing device to which a dielectric resonant oscillator (DRO) according to the present embodiment is applied.

The radar unit 110 included in the vital signal detection apparatus 100 transmits a continuous wave (CW) radar beam. The vital signal sensing apparatus 100 uses a dielectric resonator oscillator (DRO) 112 to transmit a CW radar beam.

The radar unit 110 emits a continuous wave (CW) type radar beam to the body. Then, the radar unit 110 receives the reflected signal reflected in response to the radar beam from the body, the heart existing in the body, and the diaphragm existing in the body.

The radar unit 110 includes a dielectric resonator oscillator (DRO). The radar unit 110 uses a dielectric resonance oscillator (DRO) 112 to emit a CW-type radar beam to the body.

The dielectric resonance oscillator (DRO) 112 outputs a CW-type radar beam based on a reference signal input from the outside. The dielectric resonant oscillator (DRO) 112 amplifies (eg, up- or down-converts) the frequency of the CW-type radar beam and then sends it to the body. The dielectric resonant oscillator (DRO) 112 improves phase noise by using a dielectric resonator (DR) when oscillating and outputting a CW type radar beam.

The controller 120 detects the movement of the heart, the movement of the diaphragm, and the movement of the object based on the difference between the oscillation frequency and the frequency of the reflected signal (Doppler frequency) using the modulation frequency of the Doppler frequency.

The control unit 120 according to the present embodiment includes a breathing signal detection unit 130 , a heart signal detection unit 140 , and a motion signal detection unit 150 . Components included in the control unit 120 are not necessarily limited thereto.

The respiration signal detector 130 detects a respiration signal corresponding to the movement of the diaphragm based on a frequency difference (Doppler Frequency) between the first oscillation frequency and the reflected signal. Respiratory signal detection unit 130 counts the movement of the diaphragm to calculate the number of respiration. Respiratory signal detection unit 130 according to the present embodiment includes a first active filter 132, a first DSP (134). Components included in the breathing signal detection unit 130 are not necessarily limited thereto.

The first active filter #1 132 generates a first filtering signal obtained by filtering only the range (eg, 1 Hz) of the first frequency band corresponding to the movement of the diaphragm among the reflected signals. The first DSP (Digital Signal Processor #1) 134 detects only the respiration signal corresponding to the movement of the diaphragm based on a frequency difference between the FFT (Fast Fourier Transform) transform of the first filtering signal and the first oscillation frequency. do.

The heart signal detector 140 detects a heart signal corresponding to the movement of the heart based on a difference in frequency between the second oscillation frequency and the reflected signal. The heart signal detector 140 counts the movement of the heart and calculates the number of heartbeats. The heart signal detector 140 according to the present embodiment includes a second active filter 142 and a second DSP 144 . Components included in the heart signal detector 140 are not necessarily limited thereto.

The second active filter (Active Filter #2) 142 filters only the range of the second frequency band corresponding to the movement of the heart among the reflected signals (eg, 1 Hz to 10 Hz when the 24 GHz band is used for the transmission signal). Generates a filtered signal. The second DSP (Digital Signal Processor #2) 144 detects only the heart signal corresponding to the movement of the heart based on a frequency difference between the FFT (Fast Fourier Transform) transform of the second filtering signal and the second oscillation frequency. do.

The motion signal detector 150 detects a motion signal corresponding to the movement of the body based on the difference between the third oscillation frequency and the frequency of the reflected signal. The motion signal detector 150 according to the present embodiment includes a third active filter 152 and a third DSP 154 . Components included in the motion signal detection unit 150 are not necessarily limited thereto.

The third active filter (Active Filter #3) 152 filters only the range of the third frequency band corresponding to the movement of the body among the reflected signals (eg, 10 Hz or more when the transmit signal is used in the 24 GHz band). generate a signal The third DSP (Digital Signal Processor #3) 154 detects only the motion signal corresponding to the movement of the body based on the difference in frequency between the FFT (Fast Fourier Transform) transform of the third filtering signal and the third oscillation frequency. do.

3 is a diagram illustrating phase noise characteristics according to the present embodiment.

Phase noise characteristics for each type of microwave oscillator are as shown in FIG. 3 . Referring to the graph shown in FIG. 3 , the phase noise characteristics are superior in the order of a phase-locked loop oscillator (PLL), a dielectric resonant oscillator (DRO), and a free-running oscillator. it can be seen that

Among the frequency bands for the Doppler effect on respiration/heartbeat, the available frequency bands are 5.8GHz, 10.5GHz, 24GHz, and 60GHz bands. 0.1 to several Hz.

Since the frequency range to be measured is very low, the phase noise characteristics of the local oscillator of the radar sensor should be very good, and the frequency range to be measured should not be affected by the phase noise. In general, in the case of a microwave signal generator used in a radar sensor, an excellent phase noise characteristic can be obtained by applying a phase-locked loop (PLL) oscillator. However, when a phase-locked loop (PLL) oscillator is applied, an expensive phase-locked loop (PLL) circuit must be applied, thereby increasing the cost of the device.

Therefore, in the case of a free-running oscillator, since a microstrip-line resonator using a PCB board or a resonator inside the MMIC are used, the Q value of the resonator is low to several hundred, so the phase The noise characteristics are lowered.

In order to improve the shortcomings of the free-running oscillator, a dielectric resonator (DRO) using a dielectric resonator (DR) with a Q value of tens of thousands instead of a micro strip line using a PCB board or when using a resonator inside an MMIC. (112) can be used to improve the phase noise. Since the dielectric resonant oscillator (DRO) 112 uses a low-cost dielectric resonator (DR), it can be implemented at a lower cost than a phase-locked loop (PLL) oscillator and has a simpler design.

4 is a view for explaining a CW radar according to the present embodiment.

To compare CW (Continuous Wave) and FMCW (Frequency Modulation Continuous Wave Radar), CW radar _{measures Doppler frequency (f speed} ). Since the CW modulation method detects only the Doppler frequency range, it can limit the Doppler frequency band, so that the frequency resolution may be relatively low due to the low measurement frequency. In other words, in the CW modulation method, when a time domain is changed to a frequency domain, a Fast Fourier Transform (FFT) is applied, and the number of FFTs is the number divided by the frequency resolution from the maximum Doppler frequency to be measured.

In the FMCW modulation method, since the F _distance frequency is _{much larger than the f speed} frequency, there is a problem in that the distance is limited for heart/respiration measurement. Normal cardiac / respiratory Doppler frequency has a 0.1 Hz to several bands, is determined according to the use frequency band and the chirp (Chirp) setting conditions, _distance F frequency has a few hundred KHz band of about several tens of KHz in the case 1m. In other words, the frequency detection resolution must be very precise for heart/respiration measurement. Compared to the CW method, the FMCW method has a hardware limitation, and in order to increase the frequency resolution, there is a limitation due to the number of FFTs.

5A, 5B, and 5C are diagrams illustrating a dielectric resonant oscillator (DRO) according to the present embodiment.

In general, the heart rate takes 0.8 seconds for ventricular relaxation of 0.5 seconds and ventricular contraction of 0.3 seconds, with a resting heart rate of 75 beats per minute (0.8 seconds) and during high-intensity exercise 180 beats per minute (0.33 seconds).

At rest, the left ventricle has a diameter of 30/48 mm (left ventricular ejection fraction of 60%) and a movement of 18 mm during contraction/relaxation of the left ventricle. During high-intensity exercise, left ventricle diameter during contraction/relaxation of the left ventricle: 57/64 mm (left ventricular ejection fraction of 21%), and movement of 7 mm. Normally, it moves about 10 to 15% of the size of the heart (about 10 cm in diameter).

In the case of respiration, in general, an adult performs a breathing exercise about 18 times per minute. Normally, the movement distance of the diaphragm during respiration is about 5±1mm for auditory damage (yes) and 6±2mm for sensory damage (no). During abdominal respiration, the movement distance of the diaphragm is about 14±5mm for auditory damage (yes) and 17±6mm for sensory damage (no). The Doppler frequency fd during respiration is expressed by Equation 1.

Table 1 shows the size and movement speed of the diaphragm during respiration.

The dielectric resonant oscillator (DRO) 112 generates a microstrip resonance using a resonator network. The dielectric resonant oscillator (DRO) 112 can be configured in a frequency variable format by using a resonator only with a microstrip using a resonator network, and using a varactor together.

The dielectric resonant oscillator (DRO) 112 includes one amplifier (Transistor).

The amplifier includes an input terminal (Gate) connected to a resonance network (Resonator Network), an amplification terminal (Drain) connected to a bias network (Bias Network), and a current withdrawal terminal (Source) connected to a feedback element (Feedback Element).

One side of the contact point between the bias network and the amplification stage (Drain) is connected to a matching network (Matching Network) to transmit and output a CW type radar beam.

The above description is merely illustrative of the technical idea of this embodiment, and various modifications and variations will be possible by those skilled in the art to which this embodiment belongs without departing from the essential characteristics of the present embodiment. Accordingly, the present embodiments are intended to explain rather than limit the technical spirit of the present embodiment, and the scope of the technical spirit of the present embodiment is not limited by these embodiments. The protection scope of this embodiment should be interpreted by the following claims, and all technical ideas within the equivalent range should be interpreted as being included in the scope of the present embodiment.

100: vital signal detection device
110: radar unit
112: dielectric resonant oscillator (DRO)
130: breathing signal detection unit
132: first active filter
134: first DSP
140: heart signal detection unit
142: second active filter
144: second DSP
150: motion signal detection unit
152: third active filter
154: third DSP

Claims (13)

a radar unit that emits a radar beam to a body positioned in a preset direction and distance, and receives a reflected signal reflected from the body in response to the radar beam;
After filtering the reflected signal to each preset frequency band, based on the filtered signal, a control unit for detecting the movement of the heart in the body, the movement of the diaphragm in the body, and the movement of the body,
The radar unit, by using a dielectric resonator oscillator (DRO: Dielectric Resonator Oscillator) configured in a frequency-variable type using a varactor, emits the radar beam in the CW form of which the oscillation frequency is variable to the body,
The control unit is
Respiratory signal detection unit for detecting a respiration signal corresponding to the movement of the diaphragm based on the first oscillation frequency and the frequency difference (Doppler Frequency) of the reflected signal;
a heart signal detector configured to detect a heart signal corresponding to the movement of the heart based on a difference between a second oscillation frequency different from the first oscillation frequency and a frequency difference of the reflected signal; and
and a motion signal detector configured to detect a motion signal corresponding to the movement of the body based on a difference between a third oscillation frequency different from the second oscillation frequency and a frequency difference of the reflected signal,
The respiration signal detector detects a respiration signal corresponding to the size of the diaphragm during respiration, the minimum and maximum moving speed of the diaphragm according to normal respiration, abdominal respiration, resting heartbeat and heartbeat during exercise Vital signal detection device. According to claim 1,
The radar unit emits the radar beam in a continuous wave (CW) form to the body, and then the reflected signal reflected from the body, the heart existing in the body, and the diaphragm existing in the body in response to the radar beam receive,
The control unit uses a modulation frequency of the Doppler frequency to detect the movement of the heart, the movement of the diaphragm, and the movement of the body based on the difference between the oscillation frequency and the frequency of the reflected signal (Doppler Frequency) Vital signal, characterized in that detection device. delete According to claim 1,
The breathing signal detection unit,
a first active filter (Active Filter#1) for generating a first filtering signal by filtering only a range (eg, 1 Hz) of a first frequency band corresponding to the movement of the diaphragm among the reflected signals;
A first DSP (Digital Signal Processor) that detects only the respiration signal corresponding to the movement of the diaphragm based on a frequency difference between the FFT (Fast Fourier Transform) transformed value of the first filtering signal and the first oscillation frequency
Vital signal detection device comprising a. 5. The method of claim 4,
The heart signal detector,
a second active filter (Active Filter #2) for generating a second filtering signal obtained by filtering only a range of a second frequency band (eg, 1 Hz to 10 Hz) corresponding to the movement of the heart among the reflected signals;
A second digital signal processor (DSP) that detects only the heart signal corresponding to the movement of the heart based on a difference in frequency between the second oscillation frequency and the FFT (Fast Fourier Transform) transform of the second filtering signal
Vital signal detection device comprising a. 6. The method of claim 5,
The motion signal detection unit,
a third active filter (Active Filter#3) for generating a third filtering signal obtained by filtering only a range of a third frequency band (eg, 10 Hz or higher) corresponding to the movement of the body among the reflected signals;
A third digital signal processor (DSP) that detects only the motion signal corresponding to the movement of the body based on a frequency difference between a value obtained by converting the third filtering signal by FFT (Fast Fourier Transform) and the third oscillation frequency
Vital signal detection device comprising a. delete According to claim 1,
The dielectric resonant oscillator (DRO),
Vital signal sensing device, characterized in that outputting the radar beam in the form of CW based on a reference signal input from the outside, amplifying the frequency of the radar beam in the form of CW, and then firing it to the body. 9. The method of claim 8,
The dielectric resonant oscillator (DRO),
A device for detecting a vital signal, characterized in that when oscillating and outputting the CW type radar beam, phase noise is improved by using a dielectric resonator (DR). 10. The method of claim 9,
The dielectric resonant oscillator (DRO),
It includes a single amplifier (Transistor), wherein the amplifier is connected to an input terminal (Gate) connected to a resonance network (Resonator Network), an amplifier terminal (Drain) connected to a bias network (Bias Network), and a feedback element (Feedback Element) Including a current drawing terminal (Source),
One side of the contact point of the bias network and the amplification stage (Drain) is connected to a matching network (Matching Network), Vital signal detection apparatus, characterized in that the transmission and output of the CW type of the radar beam. According to claim 1,
The respiration signal detector counts the movement of the diaphragm to calculate the number of respirations,
The heart signal detection unit Vital signal detection device, characterized in that calculating the number of heart beats by counting the movement of the heart. A vital signal detection method, wherein the method is performed by a control unit of a vital signal detection device, the method comprising:
Transmitting a radar beam in a preset direction;
receiving a reflected signal reflected in response to the radar beam from a body existing within the preset direction;
generating a filtering signal by filtering the reflected signal into each preset frequency band;
detecting a movement of the heart in the body based on the filtering signal;
detecting a movement of the diaphragm in the body based on the filtering signal; and
Detecting the movement of the body based on the filtering signal,
In the process of transmitting the radar beam, using a dielectric resonator oscillator (DRO: Dielectric Resonator Oscillator) configured in a frequency variable type using a varactor to emit the radar beam in the CW form of which the oscillation frequency is variable to the body. control,
The process of detecting the movement of the heart detects the movement of the heart based on a difference between a first oscillation frequency and a frequency of the reflected signal (Doppler Frequency) using a modulation frequency of the Doppler frequency,
In the process of detecting the movement of the diaphragm, the movement of the diaphragm is sensed based on a frequency difference between a second oscillation frequency different from the first oscillation frequency and the reflected signal using a modulation frequency of the Doppler frequency,
The process of detecting the movement of the body includes detecting the movement of the body based on a difference between a third oscillation frequency different from the second oscillation frequency and a frequency of the reflected signal using a modulation frequency of the Doppler frequency,
In the process of detecting the movement of the diaphragm, the size of the diaphragm during respiration according to normal respiration, abdominal respiration, resting heart rate and heart rate during exercise, and the minimum and maximum speed of movement of the diaphragm. A method for detecting vital signals. 13. The method of claim 12,
The process of receiving the reflected signal includes receiving the reflected signal reflected from the body, the heart existing in the body, and the diaphragm.

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