CN-121154127-B - Non-contact type cardiopulmonary coupling analysis method and system based on millimeter wave perception

CN121154127BCN 121154127 BCN121154127 BCN 121154127BCN-121154127-B

Abstract

The invention provides a non-contact cardiopulmonary coupling analysis method and a non-contact cardiopulmonary coupling analysis system based on millimeter wave perception, wherein the method comprises the steps of continuously sending millimeter wave frequency modulation signals to a subject, receiving initial echo signals, converting the initial echo signals to obtain converted echo signals, and positioning the distance position between the converted echo signals and a target; the method comprises the steps of calculating a first phase of a converted echo signal of each time point of a distance position of a target, calculating a second phase of the converted echo signal of each time point and a radial displacement signal based on the first phase of each time point and a time point before the time point, calculating a respiratory displacement signal and a heartbeat displacement signal based on the radial displacement signal, calculating a respiratory instantaneous phase of each time point based on the respiratory displacement signal, selecting at least one target time period based on the respiratory instantaneous phase, calculating a heartbeat accompanying change value of the target time period based on the heartbeat displacement signal of the target time period, and calculating a modulation index based on the heartbeat accompanying change values of all the target time periods.

Inventors

ZHOU ANFU
KANG LE
HUA YOUWEI
An Congkai

Assignees

北京邮电大学

Dates

Publication Date: 20260505
Application Date: 20250721

Claims (9)

1. A non-contact cardiopulmonary coupling analysis method based on millimeter wave perception is characterized by comprising the following steps: continuously transmitting millimeter wave frequency modulation signals to the direction of a subject, receiving initial echo signals, performing distance dimension fast Fourier transform on the initial echo signals to obtain converted echo signals, and positioning the distance position between the converted echo signals and a target through a peak value searching algorithm; Calculating a first phase of a converted echo signal at each time point of a distance position of a target, calculating a first phase difference based on the first phase of each time point and a time point before the time point, calculating a second phase difference based on the first phase difference, calculating a second phase based on the second phase difference, and calculating a radial displacement signal based on the second phase; Calculating a respiratory displacement signal and a heartbeat displacement signal based on the radial displacement signal, calculating a respiratory instantaneous phase at each time point based on the respiratory displacement signal, and selecting at least one target time period based on the respiratory instantaneous phase; calculating a heartbeat accompanying change value of a target time period based on heartbeat displacement signals of the target time period, and calculating PAC intensity values based on the heartbeat accompanying change values of all the target time periods; The PAC intensity value is calculated using the following formula: Wherein, the The PAC intensity value is indicated as such, The number of target time periods is indicated, A heartbeat-associated change value representing a target period i; Calculating a modulation index based on the PAC intensity value, and calculating the modulation index by adopting the following formula: Wherein, the The PAC intensity value is indicated as such, The number of target time periods is indicated, Representing the modulation index.
2. The method according to claim 1, wherein in the step of calculating the first phase for the converted echo signal at each time point of the distance position of the target, the first phase is calculated using the following formula: Wherein, the A first phase representing a point in time t, Representing the imaginary part of the converted echo signal, Representing the real part of the converted echo signal.
3. The non-contact cardiopulmonary coupling analysis method based on millimeter wave sensing according to claim 1, wherein in the step of calculating the second phase difference based on the first phase difference, the first phase difference is compared with a preset phase difference threshold value; If the first phase difference is larger than a preset phase difference threshold value, calculating a second phase difference by adopting the following formula: ; if the first phase difference is smaller than a preset phase difference threshold value, calculating a second phase difference by adopting the following formula; ; Wherein, the A first phase difference is indicated and a second phase difference is indicated, Representing a second phase difference; if the first phase difference is equal to the preset phase difference threshold value, the second phase difference is equal to the first phase difference.
4. The millimeter wave perception based non-contact cardiopulmonary coupling analysis method according to claim 1, wherein in the step of calculating a radial displacement signal based on the second phase, the radial displacement signal is calculated using the following formula: Wherein, the A radial displacement signal representing a point in time t, A second phase representing a point in time t, Representing the center wavelength of the millimeter wave fm signal.
5. The non-contact cardiopulmonary coupling analysis method based on millimeter wave sensing according to any one of claims 1 to 4, wherein the step of calculating a respiratory displacement signal and a heartbeat displacement signal based on the radial displacement signal comprises: processing the radial displacement signal by adopting a zero phase shift low-pass filter to extract a respiratory displacement signal; Calculating a residual signal based on the radial displacement signal and the respiratory displacement signal; And processing the residual signal by adopting a zero phase shift low-pass filter to extract a heartbeat displacement signal.
6. The method according to claim 5, wherein in the step of calculating a respiratory instantaneous phase at each time point based on the respiratory displacement signal, performing hilbert transform on the respiratory displacement signal to obtain an analysis signal, and calculating a respiratory instantaneous phase based on the analysis signal; The instantaneous phase of respiration is calculated using the following formula: ; Wherein, the The instantaneous phase of the breath at time point t is indicated, An analytic signal representing the point in time t, Representation of A function.
7. The method according to claim 1, wherein in the step of selecting at least one target time period based on the respiratory instantaneous phase, the range of the respiratory phase is divided into a preset number of phase intervals on average, the target phase intervals are selected, if the respiratory instantaneous phase falls into the target phase intervals, a time point corresponding to the respiratory instantaneous phase is taken as a target time point, and the target time period is determined based on the target time point.
8. The non-contact cardiopulmonary coupling analysis method based on millimeter wave sensing according to claim 1, wherein in the step of calculating the heartbeat accompanying variation value of the target time period based on the heartbeat displacement signal of the target time period, an average heartbeat instantaneous amplitude is calculated for each time point in each target time period, and the heartbeat accompanying variation value of each target time period is calculated based on the average heartbeat instantaneous amplitude of each target time period; The heartbeat-related variation value is calculated using the following formula: Wherein, the A heartbeat-accompanied variation value representing the target period k, Representing the average heartbeat instantaneous amplitude for the target time period k, The number of target time periods is indicated, Representing the average heartbeat instantaneous amplitude for any one of the target time periods i.
9. A non-contact cardiopulmonary coupling analysis system based on millimeter wave perception, characterized in that the system comprises a computer device, the computer device comprising a processor and a memory, the memory storing computer instructions, the processor being adapted to execute the computer instructions stored in the memory, the system implementing the steps implemented by the method according to any one of claims 1-8 when the computer instructions are executed by the processor.

Description

Non-contact type cardiopulmonary coupling analysis method and system based on millimeter wave perception Technical Field The invention relates to the technical field of millimeter wave perception, in particular to a non-contact type heart-lung coupling analysis method and system based on millimeter wave perception. Background The human body is a highly integrated and complex living system in which there is a constant and dynamic interaction between the cardiovascular system and the respiratory system, a phenomenon known as cardiopulmonary coupling (Cardiopulmonary Coupling, CPC). The physiological basis of cardiopulmonary coupling involves multiple layers including, but not limited to, integrated regulation of the central nervous system (e.g., interaction of the brain stem respiratory and cardiovascular centers), dynamic balance of the autonomic nervous system (sympathetic and parasympathetic), baroreceptor reflex (e.g., arterial baroreceptors and pulmonary stretch receptors), chemoreceptor reflex (response to changes in oxygen and carbon dioxide levels in the blood), and direct mechanical effects of hemodynamics (e.g., effects of respiratory motion on intrathoracic pressure and venous reflux, and thus cardiac output). Currently, cardiopulmonary coupling analysis is typically based on synchronously acquired multi-lead physiological parameters such as electrocardiographic signals (ECG), respiratory airflow signals (measured by nasal cannula or mask), chest-abdomen movement signals (measured by respiratory straps), pulse wave signals (PPG), continuous or intermittent blood pressure, etc. By performing time domain (such as statistical quantization of RSA), frequency domain (such as coherence analysis of heart rate variability and respiratory frequency), time-frequency domain (such as wavelet transform coherence) or nonlinear dynamics analysis (such as phase synchronization and information entropy) on the signals, characteristic parameters reflecting interaction are extracted, so that strength and mode of cardiopulmonary coupling are quantized, and some advanced methods can even judge the directionality of interaction (such as modulation of heart rate by respiration or weak influence of heart rate on respiratory rhythm). However, the prior art cardiopulmonary coupling analysis method generally requires contact wearing of the device on the subject, is limited to contact wearing, and has certain limitations. Disclosure of Invention In view of the foregoing, embodiments of the present invention provide a non-contact cardiopulmonary coupling analysis method and system based on millimeter wave sensing, so as to eliminate or improve one or more drawbacks of the prior art. One aspect of the present invention provides a non-contact cardiopulmonary coupling analysis method based on millimeter wave sensing, the method comprising the steps of: continuously transmitting millimeter wave frequency modulation signals to the direction of a subject, receiving initial echo signals, performing distance dimension fast Fourier transform on the initial echo signals to obtain converted echo signals, and positioning the distance position between the converted echo signals and a target through a peak value searching algorithm; Calculating a first phase of a converted echo signal at each time point of a distance position of a target, calculating a first phase difference based on the first phase of each time point and a time point before the time point, calculating a second phase difference based on the first phase difference, calculating a second phase based on the second phase difference, and calculating a radial displacement signal based on the second phase; Calculating a respiratory displacement signal and a heartbeat displacement signal based on the radial displacement signal, calculating a respiratory instantaneous phase at each time point based on the respiratory displacement signal, and selecting at least one target time period based on the respiratory instantaneous phase; calculating a heartbeat accompanying change value of a target time period based on heartbeat displacement signals of the target time period, and calculating PAC intensity values based on the heartbeat accompanying change values of all the target time periods; And calculating a modulation index based on the PAC intensity value. By adopting the scheme, millimeter waves are sent to a subject, echo cardiopulmonary coupling analysis is carried out, and the direct modulation effect of respiration on the mechanical strength of heart beat is revealed through the index of Modulation Index (MI), so that the scheme does not need to be worn by the subject on one hand, and on the other hand, the mechanical displacement amplitude of the chest and abdomen wall directly caused by heart beat and respiration is introduced as the core characteristic of the cardiopulmonary coupling analysis, so that a direct means is provided for quantifying the actual mechanical strength of heart