阅读说明：本技术 一种基于雷达测量的人体呼吸频率计算方法 (Human body respiratory frequency calculation method based on radar measurement ) 是由 张雅勤 于 2020-07-21 设计创作，主要内容包括：本发明涉及雷达信号处理技术,其公开了一种基于雷达测量的人体呼吸频率计算方法,实时、准确地计算呼吸频率,计算复杂度低。该方法包括以下步骤：a.接收使用超宽带雷达向目标人体所处自由空间发射电磁波而反射回来的回波信号；b.对回波信号的距离维信息进行傅里叶变换,然后进行极大值搜索,提取以极大值为中心的预设距离内的数据,得到人体的回波序列；c.通过人体回波序列的频谱图计算参考呼吸频率；d.计算人体回波序列平均幅度差,并结合参考呼吸频率计算准确的呼吸频率。(The invention relates to a radar signal processing technology, and discloses a human body respiratory frequency calculation method based on radar measurement. The method comprises the following steps: a. receiving an echo signal reflected by transmitting electromagnetic waves to a free space where a target human body is located by using an ultra-wideband radar; b. fourier transform is carried out on the distance dimension information of the echo signal, then maximum value search is carried out, data within a preset distance with the maximum value as the center are extracted, and an echo sequence of the human body is obtained; c. calculating a reference respiratory frequency through a spectrogram of a human body echo sequence; d. and calculating the average amplitude difference of the human body echo sequence, and calculating the accurate respiratory frequency by combining the reference respiratory frequency.)

1. A human body respiratory frequency calculation method based on radar measurement is characterized by comprising the following steps:

a. receiving an echo signal reflected by transmitting electromagnetic waves to a free space where a target human body is located by using an ultra-wideband radar;

b. fourier transform is carried out on the distance dimension information of the echo signal, then maximum value search is carried out, data within a preset distance with the maximum value as the center are extracted, and an echo sequence of the human body is obtained;

c. calculating a reference respiratory frequency through a spectrogram of a human body echo sequence;

d. and calculating the average amplitude difference of the human body echo sequence, and calculating the accurate respiratory frequency by combining the reference respiratory frequency.

2. The method of claim 1, wherein the calculating the respiratory rate of the human body based on the radar measurement,

the step c specifically comprises the following steps:

c1. smoothing the human body echo sequence;

c2. and calculating a spectrogram of the smoothed human body echo sequence, finding out all peak values in the frequency range of 0.1-0.6Hz in the spectrogram, and taking a frequency value corresponding to the maximum peak as fa.

3. The method of claim 2, wherein the calculating the respiratory rate of the human body based on the radar measurement,

the step d specifically comprises the following steps:

d1. performing trend elimination processing on the smoothed human body echo sequence;

d2. calculating the average amplitude difference of the human body echo sequence after trend elimination, and finding out all valley points in the frequency range of 0.1-0.6 Hz;

d3. calculating an accurate breathing frequency value:

if only 1 valley point is found, and the frequency value corresponding to the valley point is recorded as fb, the respiratory frequency is 60 × fb bpm;

if the number of the found valley points is more than 1, the frequency values corresponding to the valley points are respectively fb₁、fb₂、…fb_nCalculating the absolute value of the difference from fa, and obtaining the frequency value fb when the absolute value is minimum_iThen the breathing rate is 60 fb_ibpm。

Technical Field

The invention relates to a radar signal processing technology, in particular to a human body respiratory frequency calculation method based on radar measurement.

Background

Respiration is the most fundamental life activity for human life. The respiratory rate contains important physiological information, and the respiratory rate measurement is widely applied to the fields of rescue living body detection, medical patient monitoring, cardiopulmonary function observation, motion effect evaluation, sleep quality monitoring and the like. Household products on the market can only measure heart rate, and can not detect breathing simultaneously, and medical products need wear detection device for measuring breathing, and the comfort level is not high.

The comfort of the user can be improved by adopting a non-contact measurement technology to measure the breathing frequency, and the ultra-wideband radar is a good choice. Ultra-wideband radar has received increasing attention in the field of respiratory monitoring due to its non-contact, long-range, and transparent characteristics.

When a human body breathes, the surface of the chest generates periodic fluctuation along with the respiration, and the ultra-wideband radar can capture echo signals of the fluctuation. However, the ultra-wideband radar is easily interfered by human body movement, other objects in a room, and the like, so that an algorithm with real-time performance, accuracy and low calculation complexity is needed for calculating the respiratory frequency.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the human body respiratory frequency calculation method based on radar measurement is provided, the respiratory frequency is accurately calculated in real time, and the calculation complexity is low.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a human body respiratory frequency calculation method based on radar measurement comprises the following steps:

a. receiving an echo signal reflected by transmitting electromagnetic waves to a free space where a target human body is located by using an ultra-wideband radar;

b. fourier transform is carried out on the distance dimension information of the echo signal, then maximum value search is carried out, data within a preset distance with the maximum value as the center are extracted, and an echo sequence of the human body is obtained;

c. calculating a reference respiratory frequency through a spectrogram of a human body echo sequence;

d. and calculating the average amplitude difference of the human body echo sequence, and calculating the accurate respiratory frequency by combining the reference respiratory frequency.

As a further optimization, step c specifically includes:

c1. smoothing the human body echo sequence;

c2. and calculating a spectrogram of the smoothed human body echo sequence, finding out all peak values in the frequency range of 0.1-0.6Hz in the spectrogram, and taking a frequency value corresponding to the maximum peak as fa.

As a further optimization, step d specifically includes:

d1. performing trend elimination processing on the smoothed human body echo sequence;

d2. calculating the average amplitude difference of the human body echo sequence after trend elimination, and finding out all valley points in the frequency range of 0.1-0.6 Hz;

d3. calculating an accurate breathing frequency value:

if only 1 valley point is found, and the frequency value corresponding to the valley point is recorded as fb, the respiratory frequency is 60 × fb bpm;

if the number of the found valley points is more than 1, the frequency values corresponding to the valley points are respectively fb₁、fb₂、…fb_nCalculating the absolute value of the difference from fa, and obtaining the frequency value fb when the absolute value is minimum_iThen the breathing rate is 60 fb_ibpm。

The invention has the beneficial effects that:

the requirement on the data length is greatly reduced, and the respiratory frequency can be calculated by at least two complete respiratory cycles, so that the calculation real-time performance is ensured; in addition, on the basis of the respiratory frequency provided by the spectrum analysis, the respiratory frequency with higher precision is obtained by adopting the average amplitude difference function, so that frequency doubling or frequency division errors are avoided, and the calculation accuracy is improved; the method has low calculation complexity and small storage space requirement.

Drawings

FIG. 1 is a flowchart of a method for calculating respiratory rate of a human body based on radar measurement according to the present invention;

FIG. 2 is a schematic diagram of a received human echo sequence;

FIG. 3 is a human echo sequence spectrum diagram;

fig. 4 is an average amplitude difference diagram of a human echo sequence.

Detailed Description

The invention aims to provide a human body respiratory frequency calculation method based on radar measurement, which can accurately calculate the respiratory frequency in real time and has low calculation complexity. As shown in fig. 1, the implementation steps include: a. receiving an echo signal reflected by transmitting electromagnetic waves to a free space where a target human body is located by using an ultra-wideband radar; b. fourier transform is carried out on the distance dimension information of the echo signal, then maximum value search is carried out, data within a preset distance with the maximum value as the center are extracted, and an echo sequence of the human body is obtained; c. calculating a reference respiratory frequency through a spectrogram of a human body echo sequence; d. and calculating the average amplitude difference of the human body echo sequence, and calculating the accurate respiratory frequency by combining the reference respiratory frequency.