CN-121971062-A - Method for judging weak vital signs based on infrared pair tube illumination technology

CN121971062ACN 121971062 ACN121971062 ACN 121971062ACN-121971062-A

Abstract

The invention discloses a method for judging weak vital signs based on infrared pair tube illumination technology, which relates to the technical field of vital sign detection, and is applied to a detection device which can be worn on a dead finger without heart rate and body temperature and touch the dead finger without vital signs, realizes the judgment of the weak vital signs based on optical signals after interaction of infrared light and biological tissues of the finger, and automatically triggers an alarm when the weak vital states such as false death are identified; the method comprises the steps of screening a preliminary effective signal segment based on the time domain stability of an alternating current component signal, calculating a microcirculation physiological coupling coefficient of the preliminary effective signal segment to judge a target signal segment, calculating a normalized cross-correlation function peak value of the alternating current component signal in the target signal segment as cross-correlation peak value intensity, calculating a steady-state volume index according to a direct current component signal mean value, and judging weak vital signs when the cross-correlation peak value intensity and the steady-state volume index meet preset threshold conditions.

Inventors

BAO YUAN
CHEN KANGPING
LI TONG
LI JIAN

Assignees

华康汇(北京)科技有限公司

Dates

Publication Date: 20260505
Application Date: 20260126

Claims (10)

1. The method for judging the weak vital sign based on the infrared pair tube illumination technology is characterized by comprising the following steps of: s1, synchronously collecting a dual-wavelength mixed optical signal reflected by biological tissues, and decomposing a direct current component signal and an alternating current component signal corresponding to each wavelength; s2, based on the time domain stability of the dual-wavelength alternating current component signal, a preliminary effective signal section is screened out from the continuous signal; S3, calculating normalized mutual energy spectrum of the double-wavelength alternating-current component signal segments in the preliminary effective signal segment in a preset physiological frequency band, carrying out weighted summation to obtain a microcirculation physiological coupling coefficient, and judging a target signal segment with physiological rationality according to the microcirculation physiological coupling coefficient; s4, calculating a normalized cross-correlation function of the dual-wavelength alternating-current component signal segment in the target signal segment, and extracting a peak value of the normalized cross-correlation function as cross-correlation peak value intensity; s5, calculating a steady-state volume index according to the average value ratio of the dual-wavelength direct-current component signal segments in the target signal segment through a preset mapping relation; S6, comparing the cross-correlation peak value intensity and the steady-state volume index with corresponding preset thresholds respectively, and judging that weak vital signs exist when the comparison results of the cross-correlation peak value intensity and the steady-state volume index meet preset conditions.
2. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein S1 comprises: synchronously driving a first light emitting device emitting a preset first wavelength and a second light emitting device emitting a preset second wavelength at a preset sampling frequency; Synchronously receiving the dual-wavelength mixed optical signals subjected to biological tissue action through a single photoelectric detector, and converting the dual-wavelength mixed optical signals into mixed analog electric signals; Performing transimpedance amplification, gain adjustment and analog-to-digital conversion on the mixed analog electric signal to obtain a mixed discrete digital sequence; Separating a first discrete digital sequence corresponding to a first wavelength and a second discrete digital sequence corresponding to a second wavelength from the mixed discrete digital sequence according to driving time sequences of the first light emitting device and the second light emitting device; Filtering the first discrete digital sequence and the second discrete digital sequence by adopting a low-pass digital filter with a preset cut-off frequency to obtain a first-wavelength direct-current component signal and a second-wavelength direct-current component signal; Subtracting the first wavelength direct current component signal from the first discrete digital sequence to obtain a first wavelength alternating current component signal, and subtracting the second wavelength direct current component signal from the second discrete digital sequence to obtain a second wavelength alternating current component signal.
3. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein the step S2 comprises: Sliding an analysis window for a preset duration on a continuous sequence of the first wavelength alternating current component signal and the second wavelength alternating current component signal with a preset step length; For each analysis window position, respectively intercepting and obtaining a first window segment of the first wavelength alternating current component signal and a second window segment of the second wavelength alternating current component signal; Respectively calculating stability indexes of the first window segment and the second window segment, wherein the stability indexes are obtained based on the inverse of normalized root mean square error between each window segment and the corresponding window segment after smoothing treatment; comparing the stability indexes of the first window segment and the second window segment with preset stability thresholds respectively; And when the stability indexes of the first window segment and the second window segment are larger than the stability threshold, extracting the first wavelength alternating current component signal segment and the second wavelength alternating current component signal segment corresponding to the current analysis window position, and the first wavelength direct current component signal segment and the second wavelength direct current component signal segment in the same time interval together to form a preliminary effective signal segment.
4. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein the step S3 comprises: performing short-time Fourier transform on the first-wavelength alternating-current component signal segments and the second-wavelength alternating-current component signal segments contained in each preliminary effective signal segment to obtain a corresponding first time-frequency matrix and a corresponding second time-frequency matrix; within a preset physiological frequency band, calculating normalized mutual energy spectrum on each time frame and frequency point according to the first time-frequency matrix and the second time-frequency matrix; Carrying out weighted summation on normalized mutual energy spectrums in a preset physiological frequency band based on a preset physiological characteristic weighting function to obtain a microcirculation physiological coupling coefficient of the preliminary effective signal section; When the microcirculation physiological coupling coefficient is larger than or equal to a preset physiological coupling threshold value, determining that the preliminary effective signal section has physiological rationality, and determining the preliminary effective signal section as a target signal section.
5. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein S4 comprises: for each target signal segment, calculating a normalized cyclic cross-correlation function sequence of the included first wavelength alternating current component signal segment and the second wavelength alternating current component signal segment within a preset time delay range; Extracting the peak value with the largest absolute value in the normalized cyclic cross-correlation function sequence; determining a significance threshold based on statistical properties of the normalized cyclic cross-correlation function sequence; if the absolute value of the peak value is larger than the significance threshold value, the absolute value of the peak value is used as the cross-correlation peak value intensity of the target signal segment; if the absolute value of the peak value is less than or equal to the significance threshold, the cross-correlation peak intensity of the target signal segment is set to a zero value.
6. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein the step S5 comprises: Respectively extracting a first wavelength direct current component signal segment and a second wavelength direct current component signal segment contained in each target signal segment; Respectively calculating average values of the first wavelength direct current component signal segment and the second wavelength direct current component signal segment after a preset head-tail transition region is removed; Calculating the ratio of the average value of the first wavelength direct current component signal segment to the average value of the second wavelength direct current component signal segment, and mapping the ratio into a corresponding steady-state volume index according to a preset mapping relation.
7. The method for determining weak vital signs based on infrared pair-tube illumination technology according to claim 1, wherein the step S6 comprises: comparing the cross-correlation peak intensity corresponding to each target signal segment with a preset intensity threshold; Comparing the steady-state volume index corresponding to each target signal segment with a preset lower limit threshold value and an upper limit threshold value; when the cross-correlation peak intensity is larger than the intensity threshold value and the steady-state volume index is within a numerical value interval defined by the lower limit threshold value and the upper limit threshold value, determining that the target signal segment has an instant weak vital sign at the corresponding moment.
8. The method for judging weak vital signs based on infrared pair-tube illumination technology according to claim 7, wherein the accumulated number of times of judging that the instantaneous weak vital signs exist is counted in a sliding time window of a preset time length; If the accumulated times are larger than a preset times threshold and the judgment result at the current moment is that the instantaneous weak vital sign exists, judging that the weak vital sign exists continuously, and triggering an alarm signal; And if the accumulated times are smaller than or equal to the times threshold, not triggering or canceling the triggered alarm signals.
9. The method for judging weak vital signs based on infrared pair tube illumination technology according to claim 8, wherein the triggering alarm signal is a triggering acoustic and optical alarm device.
10. The method for determining a weak vital sign based on an infrared pair-tube illumination technique according to claim 1, further comprising generating visual indication information, wherein the visual indication information is used for representing a determination result of the weak vital sign.

Description

Method for judging weak vital signs based on infrared pair tube illumination technology Technical Field The invention relates to the technical field of vital sign detection, in particular to a method for judging weak vital signs based on infrared pair tube illumination technology. Background Vital sign monitoring is a key technology in the fields of clinical medicine, emergency medicine and health management. Under extreme conditions such as sudden cardiac arrest, severe trauma, drowning, individuals may enter a "dead-like" condition, i.e., the traditional examination method is unaware of the signs of life, but weak vital activity still exists. The weak vital signs can be identified timely and accurately, and the method has important significance for starting rescue and reducing mortality. Infrared detection technology, particularly a method based on the principle of photoplethysmography, has become an important technical means in the field of noninvasive vital sign monitoring. This technique generally irradiates a biological tissue with light having a specific wavelength, and detects a change in a light absorption or scattering signal due to a change in blood volume to obtain a physiological parameter such as heart rate. The method has the advantages of no wound, continuity and simple operation, and plays an important role in the scenes of conventional health monitoring, sports physiology, clinical monitoring and the like. However, in extreme physiological and clinical states such as "death," deep shock, severe blood loss, or post-operative deep sedation, an individual's vital signs may become extremely weak, their corresponding physiological signal amplitude decreases significantly, and may exhibit atypical or nearly vanishing periodic characteristics. In such a scenario, the background noise caused by the tissue itself, ambient light or motion is relatively enhanced, resulting in a dramatic deterioration in the signal-to-noise ratio of the effective physiological signal. Conventional signal processing methods generally rely on clear identification and amplitude analysis of periodic pulse waveforms, whose analysis performance and discrimination reliability pose serious challenges when the signal is weak or disturbed in periodicity. Therefore, in order to realize effective monitoring of vital signs under wider extreme conditions, development of a new method capable of performing robust discrimination on weak and possibly aperiodic vital sign signals under an environment with extremely low signal-to-noise ratio is needed to improve the detection capability and reliability of the related monitoring equipment under a critical state. Disclosure of Invention Based on the shortcomings of the prior art, the invention aims to provide a weak vital sign judging method based on infrared pair tube illumination technology so as to solve the technical problems. In order to achieve the purpose, the invention provides the following technical scheme that the method for judging the weak vital signs based on the infrared pair tube illumination technology comprises the following steps: s1, synchronously collecting a dual-wavelength mixed optical signal reflected by biological tissues, and decomposing a direct current component signal and an alternating current component signal corresponding to each wavelength; s2, based on the time domain stability of the dual-wavelength alternating current component signal, a preliminary effective signal section is screened out from the continuous signal; S3, calculating normalized mutual energy spectrum of the double-wavelength alternating-current component signal segments in the preliminary effective signal segment in a preset physiological frequency band, carrying out weighted summation to obtain a microcirculation physiological coupling coefficient, and judging a target signal segment with physiological rationality according to the microcirculation physiological coupling coefficient; s4, calculating a normalized cross-correlation function of the dual-wavelength alternating-current component signal segment in the target signal segment, and extracting a peak value of the normalized cross-correlation function as cross-correlation peak value intensity; s5, calculating a steady-state volume index according to the average value ratio of the dual-wavelength direct-current component signal segments in the target signal segment through a preset mapping relation; S6, comparing the cross-correlation peak value intensity and the steady-state volume index with corresponding preset thresholds respectively, and judging that weak vital signs exist when the comparison results of the cross-correlation peak value intensity and the steady-state volume index meet preset conditions. The present invention is further configured such that the S1 includes: synchronously driving a first light emitting device emitting a preset first wavelength and a second light emitting device emitting a preset second wavelength a