Respiration rate and heart rate measurement method based on millimeter wave radar amplitude and phase information fusion

Abstract

This invention provides a method for measuring respiratory and heart rates based on the fusion of amplitude and phase information from millimeter-wave radar, belonging to the field of millimeter-wave radar signal processing technology. The method involves acquiring amplitude and phase information data from the human body echo signal of millimeter-wave radar; preprocessing the phase and amplitude information data to obtain normalized phase and amplitude information data, respectively; canceling the normalized phase and amplitude information data to obtain a heartbeat signal; performing a weighted summation of the normalized phase and amplitude information data to obtain a respiratory signal; filtering the heartbeat and respiratory signals, and analyzing the time interval between adjacent maxima to obtain the real-time heart rate and real-time respiratory rate, thus completing the measurement of respiratory and heart rates. This invention solves the problems of insufficient accuracy, stability, and anti-interference ability in heart rate and respiratory rate measurement.

Description

Technical Field

[0001] This specification relates to the field of millimeter-wave radar signal processing technology, and in particular to a method for measuring respiratory rate and heart rate based on the fusion of amplitude and phase information from millimeter-wave radar. Background Technology

[0002] Human heart rate and respiratory rate are among the most basic and important vital signs, widely used in medical monitoring, health assessment, sleep monitoring, smart homes, disaster relief, and many other fields. Currently, methods for measuring heart rate and respiratory rate mainly fall into two categories: contact and non-contact.

[0003] Contact-based measurement methods mainly include electrocardiogram (ECG), photoplethysmography (PPG), and breathing belts. These methods typically require sensors to be directly attached to the skin to obtain heart rate and respiratory rate information by measuring electrical signals or pressure changes. For example, ECG collects cardiac electrical activity signals through electrodes, accurately measuring heart rate, but requires electrodes to be attached to specific parts of the body, making it inconvenient to use, and prolonged wear may cause skin discomfort. PPG measures changes in blood volume using optical sensors and is commonly used in wearable devices, but it is easily affected by ambient light, skin color, and motion artifacts. Breathing belts detect respiratory rate by measuring pressure changes caused by the expansion and contraction of the chest and abdomen, but they are uncomfortable to wear and may affect natural breathing. Although contact-based measurement methods have high accuracy, their inherent limitations (such as discomfort, inconvenience, and susceptibility to motion interference) limit their application in certain scenarios, especially in scenarios requiring long-term, non-invasive monitoring.

[0004] Existing methods for measuring human vital signs based on millimeter-wave radar rely solely on the phase information of the radar echo. After unwinding and differential processing of the phase, frequency domain filtering is used to extract heartbeat and respiratory information. While phase is sensitive to minute movements, phase unwinding and noise interference are significant problems, and the signal processing algorithms are highly demanding. Furthermore, chest wall movements caused by heartbeats are significantly weaker than those caused by respiration, with amplitude differences of two orders of magnitude. The heartbeat characteristics contained in the phase are easily masked by respiratory features, leading to failure in heartbeat signal extraction. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the present invention provides a respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion, which solves the problems of insufficient accuracy, stability and anti-interference ability in heart rate and respiratory rate measurement.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention is: a method for measuring respiratory rate and heart rate based on millimeter-wave radar amplitude and phase information fusion, comprising:

[0007] S1: Acquire amplitude and phase information data of millimeter-wave radar human body echo signal;

[0008] S2: Preprocess the phase information data and amplitude information data to obtain normalized phase information data and normalized amplitude information data, respectively;

[0009] S3: Perform cancellation processing on the normalized phase information data and the normalized amplitude information data to obtain the heartbeat signal;

[0010] S4: Weighted summation of normalized phase information data and normalized amplitude information data to obtain the respiratory signal;

[0011] S5: Filter the heartbeat and respiratory signals, analyze the time interval between adjacent maximum points, and obtain the real-time heart rate and real-time respiratory rate respectively, thus completing the measurement of respiratory rate and heart rate.

[0012] Further, S1 includes:

[0013] The maximum value search is performed on the millimeter-wave radar echo signal after the range-dimensional pulse compression processing is completed, and the amplitude information and phase information at the peak are extracted and used as amplitude information data and phase information data, respectively.

[0014] Furthermore, the expressions for the amplitude information data and the phase information data are as follows:

[0015] ;

[0016] in, Indicates the baseband signal of the human body echo. Indicates the sequence number of the peak data. Indicates the first n The amplitude of each peak data point, i.e., amplitude information data. Representing the natural constant in exponential form, Represents the imaginary unit. Indicates the first n The phase of each peak data point, i.e., phase information data.

[0017] Further, S2 includes:

[0018] The phase information data is unwound to obtain unwound phase information data.

[0019] Using a radar echo signal model, the amplitude information data is transformed so that the amplitude change characteristics are linearly proportional to the changes in respiration and heart rate, thus obtaining the transformed amplitude information data.

[0020] The phase information data after unwinding and the amplitude information data after change are subjected to mean-removal processing to obtain mean-removed phase information data and mean-removed amplitude information data, respectively.

[0021] Using typical human respiratory rate and heart rate as references, a bandpass filter is set, and the mean-removed phase information data and mean-removed amplitude information data are filtered respectively to obtain filtered phase information data and filtered amplitude information data.

[0022] The filtered phase information data and the filtered amplitude information data are normalized respectively to obtain normalized phase information data and normalized amplitude information data.

[0023] Furthermore, the expression for the phase information data of the unwinding process is as follows:

[0024] ;

[0025] in, This represents the phase information data from the unwinding process. Indicates the sequence number of the peak data. Indicates the first n The phase of each peak data point.

[0026] Furthermore, the expression for the changed amplitude information data is:

[0027] ;

[0028] ;

[0029] ;

[0030] ;

[0031] ;

[0032] ;

[0033] in, This represents the changed magnitude information data. Indicates the sequence number of the peak data. This represents the proportionality coefficient. This indicates the distance between a human body at rest and a millimeter-wave radar. This indicates the change in distance caused by respiration. This indicates the noise contained in the transformed amplitude. Indicates amplitude signal data, This indicates the distance between the millimeter-wave radar and the human body. This represents the phase information data from the unwinding process. This represents the proportionality coefficient. This indicates the noise contained in the phase. This indicates the change in distance caused by the heartbeat.

[0034] Furthermore, the expression for the normalized phase information data is:

[0035] ;

[0036] in, This represents normalized phase information data. Indicates the sequence number of the peak data. This indicates the change in distance caused by respiration. This indicates the noise contained in the amplitude data after normalization.

[0037] The expression for the normalized amplitude information data is:

[0038] ;

[0039] in, This represents normalized amplitude information data. This indicates the change in distance caused by heartbeats. This indicates the noise contained in the phase data after normalization.

[0040] Furthermore, the expression for the heartbeat signal is:

[0041] ;

[0042] in, Indicates a heartbeat signal. Indicates the sequence number of the peak data. This represents normalized amplitude information data. This represents normalized phase information data. This indicates the change in distance caused by heartbeats. This indicates the noise included in the phase data after normalization. This indicates the noise contained in the amplitude data after normalization.

[0043] The expression for the respiratory signal is:

[0044] ;

[0045] ;

[0046] in, Indicates a breathing signal. This represents the weighting coefficients for the amplitude data. Represents the weighting coefficients of the phase data. This indicates the change in distance caused by respiration.

[0047] Furthermore, the expression for the real-time heart rate is:

[0048] ;

[0049] in, Indicates real-time heart rate. The first signal representing the human heartbeat i The moment when the maximum point is located in the heartbeat data;

[0050] The expression for real-time respiratory rate is:

[0051] ;

[0052] in, Indicates real-time respiratory rate. Indicates the first human respiratory signal i The time at which a maximum point occurs in the respiratory data.

[0053] The beneficial effects of this invention are as follows: This invention provides a method for measuring respiratory and heart rates based on the fusion of amplitude and phase information from millimeter-wave radar. The method involves preprocessing amplitude and phase information data to obtain normalized phase and amplitude information data, canceling the normalized phase and amplitude information data to obtain a heartbeat signal, and then weighted summing the normalized phase and amplitude information data to obtain a respiratory signal. Analysis yields real-time heart rate and real-time respiratory rate. By comprehensively utilizing the amplitude and phase information of millimeter-wave radar echoes, and fully leveraging their complementary advantages, this method effectively reduces the impact of respiratory harmonics on heartbeat information measurement, thereby improving the accuracy, stability, and anti-interference capability of heart rate and respiratory rate measurements. Attached Figure Description

[0054] This specification will be further described by way of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting; in these embodiments, the same reference numerals denote the same structures, wherein:

[0055] Figure 1 This is an exemplary flowchart illustrating a method for measuring respiratory rate and heart rate based on the fusion of amplitude and phase information from millimeter-wave radar, according to some embodiments of this specification.

[0056] Figure 2 This is an exemplary schematic diagram of amplitude information data of human body echo signals according to some embodiments of this specification;

[0057] Figure 3 This is an exemplary schematic diagram of phase information data of human body echo signals according to some embodiments of this specification;

[0058] Figure 4 These are exemplary schematic diagrams of phase data after unwinding processing, as shown in some embodiments of this specification;

[0059] Figure 5 These are exemplary schematic diagrams of transformed amplitude data shown according to some embodiments of this specification;

[0060] Figure 6 These are exemplary schematic diagrams of normalized amplitude and phase data as shown in some embodiments of this specification;

[0061] Figure 7 This is an exemplary schematic diagram of a filtered heartbeat signal according to some embodiments of this specification;

[0062] Figure 8 This is an exemplary schematic diagram of a filtered respiratory signal according to some embodiments of this specification. Detailed Implementation

[0063] The specific embodiments of the present invention are described below to enable those skilled in the art to understand the present invention. However, it should be understood that the present invention is not limited to the scope of the specific embodiments. For those skilled in the art, various changes are obvious as long as they are within the spirit and scope of the present invention as defined and determined by the appended claims. All inventions utilizing the concept of the present invention are protected.

[0064] Example

[0065] Figure 1 This is an exemplary flowchart illustrating a method for measuring respiratory and heart rate based on millimeter-wave radar amplitude and phase information fusion, according to some embodiments of this specification. Figure 1 As shown, the process includes the following steps. In some embodiments, the process may be executed by a processor.

[0066] S1: Acquire amplitude and phase information data of the human body echo signal from millimeter-wave radar.

[0067] Amplitude information data refers to the amplitude of the peak data in the human body echo baseband signal.

[0068] Phase information data is the phase of the peak data in the human body echo baseband signal.

[0069] In some embodiments, the processor can perform a maximum search on the millimeter-wave radar echo signal after the range-dimensional pulse compression processing has been completed, and extract the amplitude information and phase information at the peak, which are respectively used as amplitude information data and phase information data.

[0070] like Figure 2 The image shows the amplitude information of the extracted human echo signal, such as... Figure 3 The image shows the phase information of the extracted human echo signal. The data duration is approximately 60 seconds, and the sampling time interval is... It takes 0.11 seconds.

[0071] In some embodiments, the expressions for amplitude information data and phase information data can be:

[0072] ;

[0073] in, Indicates the baseband signal of the human body echo. Indicates the sequence number of the peak data. Indicates the first n The amplitude of each peak data point, i.e., amplitude information data. Representing the natural constant in exponential form, Represents the imaginary unit. Indicates the first n The phase of each peak data point, i.e., phase information data.

[0074] S2: Preprocess the phase information data and amplitude information data to obtain normalized phase information data and normalized amplitude information data, respectively.

[0075] In some embodiments, the processor can unwrap the phase information data to obtain unwrapped phase information data;

[0076] Using a radar echo signal model, the amplitude information data is transformed so that the amplitude change characteristics are linearly proportional to the changes in respiration and heart rate, thus obtaining the transformed amplitude information data.

[0077] The phase information data after unwinding and the amplitude information data after change are subjected to mean-removal processing to obtain mean-removed phase information data and mean-removed amplitude information data, respectively.

[0078] Using typical human respiratory rate and heart rate as references, a bandpass filter is set, and the mean-removed phase information data and mean-removed amplitude information data are filtered respectively to obtain filtered phase information data and filtered amplitude information data.

[0079] The filtered phase information data and the filtered amplitude information data are normalized respectively to obtain normalized phase information data and normalized amplitude information data.

[0080] In some embodiments, the phase information data from the unwinding process is as follows: Figure 4 As shown.

[0081] In some embodiments, the expression for the phase information data of the unwinding process can be:

[0082] ;

[0083] in, This represents the phase information data from the unwinding process. Indicates the sequence number of the peak data. Indicates the first n The phase of each peak data point.

[0084] The phase of millimeter-wave radar echoes is much more sensitive to changes in distance than the amplitude. The distance change caused by breathing is two orders of magnitude greater than the distance change caused by heartbeats. Therefore, the heartbeat information contained in the amplitude data is basically covered by noise, and its change characteristics are only related to the distance change caused by breathing.

[0085] In some embodiments, the changed amplitude information data is as follows: Figure 5 As shown.

[0086] In some embodiments, the expression for the changed amplitude information data can be:

[0087] ;

[0088] ;

[0089] ;

[0090] ;

[0091] ;

[0092] ;

[0093] in, This represents the changed magnitude information data. Indicates the sequence number of the peak data. This represents the proportionality coefficient. This indicates the distance between a human body at rest and a millimeter-wave radar. This indicates the change in distance caused by respiration. This indicates the noise contained in the transformed amplitude. Indicates amplitude signal data, This indicates the distance between the millimeter-wave radar and the human body. This represents the phase information data from the unwinding process. This represents the proportionality coefficient. This indicates the noise contained in the phase. This indicates the change in distance caused by the heartbeat.

[0094] In some embodiments, the mean of the noise is typically 0. Mean removal processing of the transformed amplitude data and the unwound phase data can eliminate constant terms in the data. and Impact on subsequent processing.

[0095] In some embodiments, the human respiratory rate typically ranges from 0.1 to 0.5 Hz, and the heart rate typically ranges from 0.8 to 2 Hz. Setting the passband of the bandpass filter to 0.1-2 Hz and filtering the amplitude and phase data after mean removal can enhance the vital signs signals contained in the amplitude and phase data and reduce the impact of out-of-band noise on subsequent vital sign signal measurements.

[0096] In some embodiments, normalizing the amplitude and phase data can eliminate the scaling factor. and The influence of this makes the range of amplitude data variation consistent with the range of phase data variation, such as... Figure 6 As shown, the red solid line represents the normalized amplitude data, and the blue dashed line represents the normalized phase data.

[0097] In some embodiments, the expression for the normalized phase information data can be:

[0098] ;

[0099] in, This represents normalized phase information data. Indicates the sequence number of the peak data. This indicates the change in distance caused by respiration. This indicates the noise contained in the amplitude data after normalization.

[0100] In some embodiments, the expression for the normalized amplitude information data can be:

[0101] ;

[0102] in, This represents normalized amplitude information data. This indicates the change in distance caused by heartbeats. This indicates the noise contained in the phase data after normalization.

[0103] S3: The normalized phase information data and normalized amplitude information data are canceled to obtain the heartbeat signal.

[0104] Heartbeat signals are signals that reflect the state of the heartbeat.

[0105] In some embodiments, the expression for the heartbeat signal can be:

[0106] ;

[0107] in, Indicates a heartbeat signal. Indicates the sequence number of the peak data. This represents normalized amplitude information data. This represents normalized phase information data. This indicates the change in distance caused by heartbeats. This indicates the noise included in the phase data after normalization. This indicates the noise contained in the amplitude data after normalization.

[0108] S4: Weighted summation of normalized phase information data and normalized amplitude information data to obtain the respiratory signal.

[0109] Respiratory signals are signals that reflect the respiratory status.

[0110] In some embodiments, the processor uses and The weighting coefficients for amplitude and phase data are represented respectively. By performing a weighted summation, the respiratory signal can be obtained.

[0111] In some embodiments, the expression for the respiratory signal can be:

[0112] ;

[0113] ;

[0114] in, Indicates a breathing signal. This represents the weighting coefficients for the amplitude data. Represents the weighting coefficients of the phase data. This indicates the change in distance caused by respiration.

[0115] S5: Filter the heartbeat and respiratory signals, analyze the time interval between adjacent maximum points, and obtain the real-time heart rate and real-time respiratory rate respectively, thus completing the measurement of respiratory rate and heart rate.

[0116] Real-time heart rate is information that reflects the current heart rate.

[0117] In some embodiments, the human heart rate typically falls within the range of 0.8-2 Hz. Setting the passband of the bandpass filter to 0.8-2 Hz is suitable for the heart rate signal. Filtering can further reduce the impact of residual respiratory signals after cancellation on the heartbeat signal. The filtered heartbeat signal is as follows: Figure 7 As shown. The first signal representing the human heartbeat i The moment when a maximum point occurs in the heartbeat data, such as Figure 7 The blue circle in the middle shows the calculated real-time heart rate of the human body.

[0118] In some embodiments, the expression for real-time heart rate can be:

[0119] ;

[0120] in, Indicates real-time heart rate. The first signal representing the human heartbeat i The moment when the maximum point is located in the heartbeat data.

[0121] Real-time respiratory rate is information that reflects the current rate of breathing.

[0122] In some embodiments, the human respiratory rate typically falls within the range of 0.1-0.5 Hz. Setting the passband of the bandpass filter to 0.1-0.5 Hz is used for the respiratory signal. Filtering can further reduce the impact of out-of-band noise on the respiratory signal. The filtered respiratory signal is as follows: Figure 8 As shown. Indicates the first human respiratory signal i The time at which a maximum point occurs in the respiratory data, such as Figure 8 The blue circle in the middle shows the calculated real-time respiratory rate of the human body.

[0123] In some embodiments, the expression for real-time respiratory rate can be:

[0124] ;

[0125] in, Indicates real-time respiratory rate. Indicates the first human respiratory signal i The time at which a maximum point occurs in the respiratory data.

[0126] In some embodiments of this specification, a method for measuring respiratory and heart rates based on the fusion of amplitude and phase information from millimeter-wave radar is provided. The method involves preprocessing amplitude and phase information data to obtain normalized phase and amplitude information data, canceling the normalized phase and amplitude information data to obtain a heartbeat signal, and then weighted summing the normalized phase and amplitude information data to obtain a respiratory signal. Analysis yields real-time heart rate and real-time respiratory rate. By comprehensively utilizing the amplitude and phase information of millimeter-wave radar echoes, and fully leveraging their complementary advantages, the method effectively reduces the impact of respiratory harmonics on heartbeat information measurement, improving the accuracy, stability, and anti-interference capability of heart rate and respiratory rate measurements.

Claims

1. A method for measuring respiratory rate and heart rate based on millimeter-wave radar amplitude and phase information fusion, characterized in that, include: S1: Acquire amplitude and phase information data of millimeter-wave radar human body echo signal; S2: Preprocess the phase information data and amplitude information data to obtain normalized phase information data and normalized amplitude information data, respectively; including: The phase information data is unwound to obtain unwound phase information data. Using a radar echo signal model, the amplitude information data is transformed so that the amplitude change characteristics are linearly proportional to the changes in respiration and heart rate, thus obtaining the transformed amplitude information data. The phase information data after unwinding and the amplitude information data after change are subjected to mean-removal processing to obtain mean-removed phase information data and mean-removed amplitude information data, respectively. Using typical human respiratory rate and heart rate as references, a bandpass filter is set, and the mean-removed phase information data and mean-removed amplitude information data are filtered respectively to obtain filtered phase information data and filtered amplitude information data. The filtered phase information data and the filtered amplitude information data are normalized respectively to obtain normalized phase information data and normalized amplitude information data; The expression for the normalized phase information data is: ； in, This represents normalized phase information data. Indicates the sequence number of the peak data. This indicates the change in distance caused by respiration. This indicates the noise contained in the amplitude data after normalization. The expression for the normalized amplitude information data is: ； in, This represents normalized amplitude information data. This indicates the change in distance caused by heartbeats. This indicates the noise contained in the phase data after normalization. S3: Perform cancellation processing on the normalized phase information data and the normalized amplitude information data to obtain the heartbeat signal; S4: Weighted summation of normalized phase information data and normalized amplitude information data to obtain the respiratory signal; The expression for the heartbeat signal is: ； in, Indicates a heartbeat signal. Indicates the sequence number of the peak data. This represents normalized amplitude information data. This represents normalized phase information data. This indicates the change in distance caused by heartbeats. This indicates the noise included in the phase data after normalization. This indicates the noise contained in the amplitude data after normalization. The expression for the respiratory signal is: ； ； in, Indicates a breathing signal. This represents the weighting coefficients for the amplitude data. Represents the weighting coefficients of the phase data. This indicates the change in distance caused by respiration; S5: Filter the heartbeat and respiratory signals, analyze the time interval between adjacent maximum points, and obtain the real-time heart rate and real-time respiratory rate respectively, thus completing the measurement of respiratory rate and heart rate.

2. The respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion according to claim 1, characterized in that, S1 includes: The maximum value search is performed on the millimeter-wave radar echo signal after the range-dimensional pulse compression processing is completed, and the amplitude information and phase information at the peak are extracted and used as amplitude information data and phase information data, respectively.

3. The respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion according to claim 1, characterized in that, The expressions for the amplitude information data and the phase information data are: ； in, Indicates the baseband signal of the human body echo. Indicates the sequence number of the peak data. Indicates the first n The amplitude of each peak data point, i.e., amplitude information data. Representing the natural constant in exponential form, Represents the imaginary unit. Indicates the first n The phase of each peak data point, i.e., phase information data.

4. The respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion according to claim 1, characterized in that, The expression for the phase information data obtained from the unwinding process is: ； in, This represents the phase information data from the unwinding process. Indicates the sequence number of the peak data. Indicates the first n The phase of each peak data point.

5. The respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion according to claim 1, characterized in that, The expression for the changed amplitude information data is: ； ； ； ； ； ； in, This represents the changed magnitude information data. Indicates the sequence number of the peak data. This represents the proportionality coefficient. This indicates the distance between a human body at rest and a millimeter-wave radar. This indicates the change in distance caused by respiration. This indicates the noise contained in the transformed amplitude. Indicates amplitude signal data, This indicates the distance between the millimeter-wave radar and the human body. This represents the phase information data from the unwinding process. This represents the proportionality coefficient. This indicates the noise contained in the phase. This indicates the change in distance caused by the heartbeat.

6. The respiratory rate and heart rate measurement method based on millimeter-wave radar amplitude and phase information fusion according to claim 1, characterized in that, The expression for the real-time heart rate is: ； in, Indicates real-time heart rate. The first signal representing the human heartbeat i The moment when the maximum point is located in the heartbeat data; The expression for real-time respiratory rate is: ； in, Indicates real-time respiratory rate. Indicates the first human respiratory signal i The time at which a maximum point occurs in the respiratory data.

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