CN113143238A

CN113143238A - Blood pressure measuring method based on pressure signal and PPG signal

Info

Publication number: CN113143238A
Application number: CN202110417301.4A
Authority: CN
Inventors: 王怡; 盛奕冰
Original assignee: Yanhe Intelligent Technology Hangzhou Co ltd
Current assignee: Yanhe Intelligent Technology Hangzhou Co ltd
Priority date: 2021-04-19
Filing date: 2021-04-19
Publication date: 2021-07-23
Anticipated expiration: 2041-04-19
Also published as: CN113143238B

Abstract

The invention discloses a blood pressure measuring method based on a pressure signal and a PPG signal, which comprises the steps of controlling an air pump to uniformly and linearly inflate an air bag structure, collecting the PPG signal of a detected part by a PPG detection part in the inflating process of the air pump, detecting the pressure signal in the air bag structure by a sensor component, simultaneously receiving the pressure signal and the PPG signal by an information processing part, determining a pressure characteristic by the information processing part through the pressure signal, and determining the PPG characteristic by the information processing part through the PPG signal; the information processing part determines an original blood pressure value through the pressure characteristic; and the information processing part carries out calibration compensation on the original blood pressure value through the PPG characteristic and the pressure characteristic to obtain a final blood pressure value, and the measurement is finished. According to the blood pressure measuring method, the PPG signal and the pressure signal are acquired simultaneously in the inflation and pressure boosting processes, the original average pressure, diastolic pressure and systolic pressure in the pressure signal are acquired through amplitude change, the blood pressure is calibrated by combining PPG characteristics, the offset of the pressure value in the pressure signal is reduced, and the measuring accuracy is improved.

Description

Blood pressure measuring method based on pressure signal and PPG signal

Technical Field

The invention relates to a blood pressure measuring method, in particular to a boosting type blood pressure measuring method combining a pressure signal and a PPG signal.

Background

Blood pressure is an important physiological parameter reflecting human vital signs, and along with the aging development trend of China, hypertension becomes a main risk factor for coronary heart disease, stroke and even death of people in China. Hypertension has seriously threatened the physical health of residents in China, so that the change of the blood pressure becomes an important concern for clinical medical treatment and daily health management.

The blood pressure measurement is mainly divided into noninvasive blood pressure detection and invasive blood pressure detection, and the invasive blood pressure detection is commonly used in clinic and operation, so that the accuracy is more reliable, but the wound and the pain are caused. The noninvasive blood pressure detection is mainly used in daily health management, daily physical examination and the like. The traditional oscillography is relatively reliable theoretically, the change of the oscillation amplitude of the pulse wave is detected in a boosting or reducing mode, and the blood pressure value is calculated by an amplitude coefficient method.

However, in the actual measurement process, the pressure may have a certain offset, so that the measurement result has a deviation. The PPG signal is also an important physiological signal used in blood pressure detection, and its change can characterize the state of blood vessels, and the blood flow can change the absorption of light, so as to explore its relation with blood pressure, but the accuracy of blood pressure detection using the PPG signal alone is low, so a blood pressure measuring method combining the pressure signal and the PPG signal is needed.

Disclosure of Invention

The invention aims to provide a pressure-boosting blood pressure measuring method combining a pressure signal and a PPG signal, which is used for simultaneously acquiring the PPG signal and the pressure signal in the inflation and pressure boosting processes, acquiring the original average pressure, diastolic pressure and systolic pressure in the pressure signal through amplitude variation, and calibrating the blood pressure by combining PPG characteristics, so that the offset of the pressure value in the pressure signal is reduced, and the measuring accuracy is improved.

In order to realize the purpose of the invention, the invention adopts the following technical scheme: a blood pressure measuring method based on a pressure signal and a PPG signal is applied to a blood pressure measuring device, and the blood pressure monitoring device comprises a main body and an air bag structure connected with the main body; the main body is internally provided with an air pump, a photoplethysmography (PPG) detection part, a sensor assembly and an information processing part, and the air pump is communicated with the air bag structure and used for inflating the air bag structure; the PPG detection part is connected with the information processing part, and the sensor assembly is connected with the information processing part; the main body is fixed on a detected part through the air bag structure, and the PPG detected part is positioned on the outer surface of the main body and is in contact with the detected part;

the blood pressure measuring method comprises the following steps:

the air pump is controlled to uniformly and linearly inflate the air bag structure, and the PPG detection part acquires PPG signals of the detected part and sends the PPG signals to the information processing part in the inflating process of the air pump; meanwhile, the sensor assembly detects a pressure signal in the airbag structure and sends the pressure signal to an information processing part;

the information processing part receives the pressure signal and the PPG signal at the same time, the information processing part determines a pressure characteristic through the pressure signal, and the information processing part determines the PPG characteristic through the PPG signal;

the information processing part determines an original blood pressure value through the pressure characteristic;

the information processing part carries out calibration compensation on the original blood pressure value through the PPG characteristic and the pressure characteristic to obtain a final blood pressure value, and the measurement is finished;

wherein the uniform linear inflation increases the value of air pressure in the balloon structure at a uniform rate.

Preferably, the information processing unit obtains a final blood pressure value by performing calibration compensation on the raw blood pressure value using the PPG characteristic and the pressure characteristic, and includes:

performing first compensation on original diastolic pressure and original systolic pressure in an original blood pressure value by using a PPG (photoplethysmography) characteristic or coefficient method to obtain a first compensated blood pressure value, wherein the first compensated blood pressure value comprises the first compensated diastolic pressure and the first compensated systolic pressure; determining a second compensation parameter by the length of time between the original diastolic pressure and the original systolic pressure; and performing secondary compensation on the primary systolic pressure by using the secondary compensation parameter to obtain secondary compensated systolic pressure and obtain a final blood pressure value, wherein the final blood pressure value comprises primary compensated diastolic pressure and secondary compensated systolic pressure.

Preferably, the information processing part determines the PPG signature from the PPG signal, and the information processing part determines the pressure signature from the pressure signal, including

Acquiring a first pulse wave in the PPG signal through filtering processing,

determining, by amplitude processing, a PPG feature contained in the first pulse wave;

acquiring a second pulse wave in the pressure signal through filtering processing;

and determining pressure characteristics contained in the second pulse wave through amplitude processing, and obtaining a second amplitude curve corresponding to the amplitude characteristics in the second pulse wave.

Preferably, the filtering process includes:

removing the baseline drift in the original signal through high-pass filtering to obtain a pulse wave signal containing high-frequency noise; removing high-frequency noise in the pulse wave signal through low-pass filtering to obtain a target pulse wave;

the raw signal is the PPG signal or the pressure signal; the target pulse wave is the first pulse wave corresponding to the PPG signal or the second pulse wave corresponding to the pressure signal.

Preferably, the amplitude processing includes:

filtering and smoothing input pulse waves through median filtering and mean filtering, wherein the input pulse waves comprise a first pulse wave and a second pulse wave;

detecting and judging the rising and falling processes of the input pulse wave subjected to the filtering smoothing processing, and determining a peak point and a valley point; and the difference value between the peak value point and the valley value point is an amplitude value, and each amplitude value corresponds to one pulse oscillation frequency.

Preferably, after the determining, by the second amplitude processing, the pressure characteristic included in the second pulse wave and obtaining a second amplitude curve corresponding to the amplitude characteristic in the second pulse wave, the blood pressure measuring method further includes:

and performing interpolation fitting on the second amplitude curve to obtain a fitted amplitude curve corresponding to the signal length of the pressure signal.

Preferably, the information processing unit determines the raw blood pressure value by the pressure characteristics, including

And determining an average pressure through the fitted amplitude curve, wherein the average pressure is a pressure value corresponding to the maximum amplitude in the amplitudes, determining the positions of the original diastolic pressure and the original systolic pressure corresponding to the average pressure according to a preset proportionality coefficient, and determining the values of the original diastolic pressure and the original systolic pressure according to the positions.

Preferably, the first compensation is performed on the original diastolic pressure and the original systolic pressure in the original blood pressure value by using a PPG characteristic or coefficient method, so as to obtain a first compensated blood pressure value, including,

determining whether the PPG feature is within a preset range,

when the PPG feature is located in the preset range, setting a compensation position of standard diastolic pressure through the PPG feature, determining a first compensation coefficient, and calculating by using the first compensation coefficient to obtain a first compensated blood pressure value;

and when the PPG feature is not in the preset range or the corresponding PGG feature cannot be extracted, extracting a time length feature in the second pulse wave, determining the first compensation coefficient according to the time length feature, and calculating to obtain the first compensated blood pressure value.

Preferably, before the controlling the air pump to uniformly and linearly inflate the balloon structure, the blood pressure measuring method further comprises:

the PPG detection part detects an initial PPG signal and transmits the initial PPG signal to the information processing part, the information processing part judges whether the blood pressure measuring device is in a wearing state or not through the initial PPG signal, and the information processing part enters an inflation stage after judging that the blood pressure measuring device is in the wearing state.

Drawings

Fig. 1 is a schematic structural view of a blood pressure measuring device according to the present invention.

Fig. 2 is a schematic diagram of module connection of the blood pressure measuring device in the embodiment.

Fig. 3 is a connection diagram of respective modules in the embodiment.

Fig. 4 is an overall flow chart of the embodiment.

FIG. 5 is a main flowchart of a signal processing section of the embodiment.

Fig. 6(a) is a baseline charge signal curve.

FIG. 6(b) shows the PGG signal after baseline shift removal.

FIG. 6(c) is the pressure signal after baseline drift removal.

FIG. 7 is an initial blood pressure value calculated in the pressure signal by the amplitude factor method.

Fig. 8 shows the characteristic points of the pulse oscillation and maximum amplitude of the PPG signal.

Fig. 9 shows the PPG signal amplitude change and the maximum feature point of the amplitude change.

Reference numerals: 10. a main body; 101. an information processing unit; 2. an air bag structure; 3. an air pump; 5. a sensor assembly; 6. a PPG detection unit.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Fig. 1 to 2 are schematic structural views of a blood pressure measuring device in the present embodiment, the blood pressure monitoring device includes a main body 10 and an airbag structure 2 connected to the main body 10; the main body 10 is provided with an air pump 3, a photoplethysmography (PPG) detection part 6, a sensor assembly 5 and an information processing part 101. Fig. 3 is a schematic structural diagram and a module connection diagram of the interior of the blood pressure measuring device in the embodiment, wherein the air pump 3 is communicated with the air bag structure 2 and is used for inflating the air bag structure 2; the PPG detector 6 is connected to the information processor 101, and the sensor unit 5 is connected to the information processor 101; the main body 10 is fixed to a site to be measured by the airbag structure 2, and the PPG detector 6 is located on an outer surface of the main body 10 and is in contact with the site to be measured.

As shown in fig. 4, the blood pressure measuring method in this embodiment mainly includes the following steps:

s1: pressurizing to obtain a pressure signal and a PPG signal;

s2: signal processing;

s3: calculating the original blood pressure;

s4: and calibrating and compensating to obtain a final blood pressure value.

At step S1: the pressurization to obtain the pressure signal and the PPG signal is preceded by a preparation step SO: and the PPG calibration is used for determining that the blood pressure measuring device is worn correctly. Wherein S0 includes:

the PPG detection unit 6 detects an initial PPG signal and transmits the initial PPG signal to the information processing unit 101, and the information processing unit 101 determines whether the blood pressure measurement device is in a wearing state according to the initial PPG signal, and enters an inflation stage after the information processing unit 101 determines that the blood pressure measurement device is in the wearing state. Otherwise, the wrong information is prompted to not measure the blood pressure. When the blood pressure is actually measured, the pressure signal and the PPG signal are simultaneously acquired in the boosting process and are processed in real time, and when a result is output, the measurement is overtime or the pressure is overlarge, the measurement is finished.

Step S1: pressurizing to obtain a pressure signal and a PPG signal, including

The air pump 3 is controlled to uniformly and linearly inflate the airbag structure 2, and during the inflation process of the air pump 3, the PPG detection part 6 acquires PPG signals of the detected part and sends the PPG signals to the information processing part 101; meanwhile, the sensor assembly 5 detects a pressure signal in the airbag structure 2 and sends the pressure signal to the information processing unit 101, and the information processing unit 101 receives the pressure signal and the PPG signal at the same time.

In the inflation pressurization process, the inflation process is controlled by a PID method to keep uniform linearity, so that the inflation rate is kept stable; the PID control method forms deviation through a target value and an actual output value, linearly combines proportion, integral and differential of the deviation to form a control quantity, and controls a controlled object by specifically adopting the following formula:

where Kp is a proportional coefficient, Ki is an integral coefficient, Kd is a differential coefficient, and e (t) is a deviation signal.

As shown in fig. 4 to 9, S2: signal processing, including

S21: extracting a PPG signal;

s22: a pressure signal is extracted.

The information processing part 101 determines a pressure characteristic from the pressure signal, and the information processing part 101 determines the PPG characteristic from the PPG signal; the information processing unit 101 determines an original blood pressure value from the pressure characteristics; the information processing unit 101 performs calibration compensation on the raw blood pressure value by using the PPG characteristic and the pressure characteristic to obtain a final blood pressure value, and the measurement is completed.

In step S21, a first pulse wave in the PPG signal is obtained through a filtering process, and a PPG feature included in the first pulse wave is determined through an amplitude process.

Acquiring a second pulse wave in the pressure signal through a filtering process in step S22; and determining pressure characteristics contained in the second pulse wave through amplitude processing, and obtaining a second amplitude curve corresponding to the amplitude characteristics in the second pulse wave.

Specifically, the process of S21 extracting the PPG signal is as follows:

and removing the baseline drift in the original signal by utilizing high-pass filtering and low-pass filtering to obtain a first pulse wave. The high-pass filtering mainly removes the baseline drift, extracts the pulse wave signals containing high-frequency noise, and processes the pulse wave signals to be smoother through the low-pass filtering so as to facilitate the peak value/valley value detection.

The peak/valley detection is to detect the change process of the pulse wave signal, identify the ascending and descending processes of the pulse wave signal, acquire corresponding peak points and valley points through two threshold values, wherein one is the ascending length and the other is the ascending height, avoid identifying some wrong peak values or valley points, record the time positions corresponding to the peak values and the valley values at the same time, and the amplitude is the difference value between the peak values and the valley values.

At S22, a second pulse wave is extracted from the pressure signal by the same method as described above, and an amplitude characteristic is obtained

Amplitude processing is performed next: the original amplitude may have a large oscillation phenomenon, which is related to the actual measurement state. The amplitude processing of the PPG signal mainly comprises filtering smoothing and feature identification; besides filtering smoothing and feature recognition, interpolation fitting is also needed for the pressure signal, so that the pressure signal corresponds to the original signal length, and the positions of the initial diastolic pressure and systolic pressure and the corresponding blood pressure values can be conveniently calculated.

The filtering and smoothing mainly comprises median filtering and mean filtering.

The median filtering is mainly to sort the elements in the amplitude sequence under the window length by setting the window length, and to obtain the middle value of the sorted sequence as the amplitude of the point.

The main process of median filtering includes: firstly, setting the window length of a filter, namely the length n of a sequence transmitted every time, and taking (n-1)/2 elements before and after the current position as the center from an original sequence to form a sequence with the length n; then sorting n elements in the sequence from large to small; and taking the middle element of the sorted sequence as the return value of the current position.

The average filtering is to set a window length, calculate an average value for elements in the amplitude sequence under the window length, and use the average value as the amplitude of the point.

The main process of mean filtering includes: firstly, setting the window length of a filter, namely the length m of a sequence transmitted every time, and taking (n-1)/2 elements before and after the current position as the center from an original sequence to form a sequence with the length n; then calculating the average value of n elements in the sequence; and taking the average value as the return value of the current position.

PPG signal feature identification:

the feature identification of the PPG signal is mainly based on the feature of amplitude and the feature of amplitude change, and in the PPG signal which is actually acquired, the signal intensity of the front half part is slightly stronger and the pressure loss of the front part of the pressure signal can be compensated. Therefore, the PPG signal characteristics of the first half part are mainly acquired, the related characteristic points are acquired through the intensity of the amplitude and the intensity of amplitude change, and the initial blood pressure value in the pressure signal is calibrated by calculating the blood pressure value corresponding to the related characteristic points. And the obtained pulse wave quantity is taken as a critical condition, so that the influence of excessive compensation on the blood pressure calculation accuracy caused by extremely weak PPG signals is avoided.

Pressure signal feature identification:

after the pressure signal is subjected to median filtering and mean filtering, namely filtering smoothing, the amplitude curve is processed to be more complete and smooth in an interpolation fitting mode and corresponds to the length of the original signal, so that the diastolic pressure and the systolic pressure can be conveniently identified by using the amplitude proportion. The linear interpolation method mainly uses the linear relation of the known points to calculate the data corresponding to the unknown points among the known points. Given the points (x0, y0), (x1, y1), the corresponding y value at the interpolation point x is obtained by an equal proportion method, and the formula is as follows:

through the conversion, the following can be obtained:

since the original amplitude sequence does not necessarily start from the start position until the end of the maximum length position of the data, the head and tail data need to be filled in first. Firstly, extending an original amplitude sequence, wherein the initial position is 1, and the initial amplitude is 0; the end position is the length of the original data sequence and the end amplitude is also 0. Then, a scaling factor k and an offset b are determined. Assuming that the magnitude sequence is y (n), the magnitude position sequence is x (n), and i denotes a certain sequence point. According to the above transformation formula:

b(i-1)＝y(i-1)-k(i-1)*x(i-1)

the scaling coefficient k and the offset b are calculated by the above transformation formula, and the amplitude y corresponding to the x position point between x (i) and x (i-1) can be calculated.

S3: calculating the original blood pressure;

The specific process is as follows:

fig. 7 is a schematic diagram of a pressure curve corresponding to a pulse wave signal, and peak/valley detection and amplitude calculation are performed to smooth and filter an amplitude curve. And the obtained maximum amplitude point is the average pressure position, and the corresponding pressure value is the average pressure. And searching the amplitude curve positions of the diastolic pressure and the systolic pressure in the amplitude curve by a proportionality coefficient method, and further acquiring the corresponding pressure values. Fig. 7 shows that the mean pressure and the initial diastolic and systolic pressures calculated from the mean pressure are both high.

S4: and (3) calibrating and compensating to obtain a final blood pressure value:

The specific process is as follows:

for the feature identification of the PPG signal, whether the feature position is a reasonable range or not needs to be judged mainly depending on the amplitude feature and the change feature of the amplitude after the feature of the PPG signal is obtained, and the false detection of the feature value caused by the sudden change of the PPG pulse wave amplitude value caused by the early inflation process and the pulse intensity change after the later pressure value reaches a certain degree is mainly eliminated.

First calibration compensation:

and judging whether the PPG feature is in a preset range, namely a reasonable position.

The specific process is as follows:

if the characteristic position is a reasonable position, setting a compensation position of the standard diastolic pressure through the comparison and fusion of the characteristics, further adjusting a compensation coefficient, and compensating the initially calculated blood pressure value to obtain a blood pressure value after the first compensation. If the characteristic position is an unreasonable position or the corresponding PPG characteristic cannot be extracted, performing first compensation by using a coefficient method, namely acquiring a position which occupies the specific proportion of the maximum amplitude in the boosting process and recording as a reference position of diastolic pressure. And the compensation reference value is adaptively adjusted according to the time length characteristics of the diastolic pressure, the average pressure and the systolic pressure. Different proportions are set simultaneously to compensate for the diastolic and systolic pressures for the first time.

compensate_DBP＝(f-DBP₀)*s_DBP

compensate_SBP＝(f-DBP₀)*s_SBP

Wherein DBP0 is the DBP initially calculated, f is the PPG signal characteristic value, SDBP and SSBP are the compensation coefficients respectively corresponding to the DBP and SBP of the compensation, and the blood pressure value after the first compensation is calculated according to the above formula.

And (3) second calibration compensation:

and then, obtaining a secondary compensation parameter through linear transformation according to the position relation (time length) between the original diastolic pressure and the systolic pressure, wherein the primary diastolic pressure is only compensated for the first time because the deviation of the original diastolic pressure is relatively small, and the secondary compensation is mainly used for the systolic pressure (sbp). The characteristic value is the time difference s between the original diastolic pressure and the systolic pressure, and a secondary compensation value is obtained through linear parameter transformation, namely:

compensate2＝s*m+n

compensate is the result of the second compensation, s is the time difference between the diastolic pressure and the systolic pressure calculated initially, m is the scaling factor of the linear transformation, and n is the offset of the linear transformation.

Fig. 8 and 9 show the variation of pulse oscillations in the PPG signal, and fig. 4 shows the original PPG pulse signal, where the peak/valley detection is used to obtain the amplitude of each pulse wave, and the PPG pulse oscillations are more unstable than the pulse oscillations of the pressure signal. And calculating the pulse frequency, judging whether a reasonable range exists or not, avoiding the situation that the signal is poor to acquire wrong characteristic points, then acquiring amplitude characteristics, and taking the maximum amplitude value as an example to acquire a corresponding pressure value.

Fig. 8 shows the amplitude variation of the pulse amplitude in the PPG signal, and it can be seen from the graph that the PPG pulse signal of this embodiment is extremely unstable and the sudden concussion phenomenon is severe. And acquiring the signal characteristics of the first half section of pulse wave, and acquiring a corresponding pressure value by taking the maximum value of amplitude variation as an example.

Through the PPG signal characteristics in fig. 8 and 9, a proportional parameter is set according to the PPG signal characteristic point and the corresponding blood pressure value, and the initially calculated SBP and DBP in the pressure signal are compensated. And acquiring the average pressure value of the two position points as a DBP compensation reference value, calibrating the original DBP and performing first compensation on the SBP through a certain proportion parameter. And then, performing secondary compensation on the SBP according to the relationship between the initial SBP and the DBP in the pressure signal to obtain a final result. In this embodiment, the initial calculated blood pressure value is 164/101, the blood pressure value after the first compensation is 134/74, and the final blood pressure value after the second compensation of SBP is 116/74.

The foregoing is a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.

Claims

1. A blood pressure measurement method based on a pressure signal and a PPG signal is characterized in that:

the blood pressure measuring method is applied to a blood pressure measuring device, and the blood pressure monitoring device comprises a main body (10) and an air bag structure (2) connected with the main body (10); an air pump (3), a photoplethysmography (PPG) detection part (6), a sensor assembly (5) and an information processing part (101) are arranged in the main body (10), and the air pump (3) is communicated with the air bag structure (2) and used for inflating the air bag structure (2); the PPG detection part (6) is connected with the information processing part (101), and the sensor assembly (5) is connected with the information processing part (101); the main body (10) is fixed on a detected part through the air bag structure (2), and the PPG detection part (6) is positioned on the outer surface of the main body (10) and is in contact with the detected part;

the blood pressure measuring method comprises the following steps:

the air pump (3) is controlled to uniformly and linearly inflate the air bag structure (2), and in the inflating process of the air pump (3), the PPG detection part (6) acquires PPG signals of the detected part and sends the PPG signals to the information processing part (101); meanwhile, the sensor assembly (5) detects a pressure signal in the airbag structure (2) and sends the pressure signal to an information processing part (101);

the information processing part (101) receives the pressure signal and the PPG signal at the same time, the information processing part (101) determines a pressure characteristic through the pressure signal, and the information processing part (101) determines the PPG characteristic through the PPG signal;

the information processing unit (101) determines a raw blood pressure value from the pressure characteristics;

the information processing part (101) carries out calibration compensation on the original blood pressure value through the PPG characteristic and the pressure characteristic to obtain a final blood pressure value, and the measurement is finished;

wherein the uniform linear inflation is such that the value of the gas pressure in the balloon structure (2) increases at a uniform rate.

2. A blood pressure measuring method according to claim 1, characterized in that:the information processing part (101) passes through the The PPG characteristic and the pressure characteristic carry out calibration compensation on the original blood pressure value to obtain a final blood pressure valueThe method comprises the following steps:

performing first compensation on original diastolic pressure and original systolic pressure in an original blood pressure value by using a PPG (photoplethysmography) characteristic or coefficient method to obtain a first compensated blood pressure value, wherein the first compensated blood pressure value comprises the first compensated diastolic pressure and the first compensated systolic pressure;

determining a second compensation parameter by the length of time between the original diastolic pressure and the original systolic pressure;

and performing secondary compensation on the primary systolic pressure by using the secondary compensation parameter to obtain secondary compensated systolic pressure and obtain a final blood pressure value, wherein the final blood pressure value comprises primary compensated diastolic pressure and secondary compensated systolic pressure.

3. A blood pressure measuring method according to claim 1, characterized in that: the above-mentionedThe information processing part (101) passes through The PPG signal determines the PPG characteristic, and the information processing part (101) determines the pressure characteristic through the pressure signalComprises that

Acquiring a first pulse wave in the PPG signal through filtering processing,

4. A blood pressure measuring method according to claim 3, characterized in that: the filtering process includes:

5. A blood pressure measuring method according to claim 3, characterized in that: the amplitude processing comprises:

6. A blood pressure measuring method according to claim 3, characterized in that: in the above-mentionedBy a second amplitude value processing, determining The pressure characteristics contained in the second pulse wave and a second amplitude curve corresponding to the amplitude characteristics in the second pulse wave are obtainedThereafter, the blood pressure measuring method further includes:

7. The blood pressure measuring method according to claim 6, characterized in that:the information processing part (101) passes through the Determining raw blood pressure values from pressure characteristicsComprises that

8. A blood pressure measuring method according to claim 2, characterized in that: the above-mentionedUsing PPG feature or coefficient method pairs Performing first compensation on the original diastolic pressure and the original systolic pressure in the original blood pressure value to obtain a first compensated blood pressure value,comprises the steps of (a) preparing a mixture of a plurality of raw materials,

determining whether the PPG feature is within a preset range,

9. A blood pressure measuring method according to claim 1, characterized in that: in the above-mentionedControl the air pump (3) to The air bag structure (2) is uniformly and linearly inflatedPreviously, the blood pressure measuring method further includes:

the PPG detection part (6) detects an initial PPG signal and transmits the initial PPG signal to the information processing part (101), the information processing part (101) judges whether the blood pressure measuring device is in a wearing state or not according to the initial PPG signal, and the information processing part (101) enters an inflation stage after judging that the blood pressure measuring device is in the wearing state.