Disclosure of Invention
The embodiment of the application provides a blood pressure measuring device and a blood pressure measuring method, which are used for solving the problems of larger error of blood pressure detection results and low detection precision in the prior art.
In view of this, a first aspect of the embodiments of the present application provides a blood pressure measurement device for measuring blood pressure of a measured object, including:
the pulse wave signal detection module is used for detecting pulse wave signals of the tested object;
The three-dimensional pressure detection module is used for detecting the three-dimensional pressure applied to the pulse wave signal detection module by the detected object and generating a three-dimensional pressure signal; and
And the signal processing module is used for calculating the blood pressure of the tested object according to the pulse wave signal and the three-dimensional pressure signal.
In the blood pressure measurement process, a user can press a finger on the pulse wave signal detection module and gradually increase the pressure; in this process, the pressure between the finger and the pulse wave signal detection module is a three-dimensional vector force, and the three-dimensional vector force can affect the arterial blood movement of the finger tip, so that the blood pressure value of the user can be accurately calculated by combining the pressure value between the finger and the pulse wave signal detection module and the pulse wave signal reflecting the change of the blood volume in the finger.
Optionally, the pulse wave signal is a photoplethysmogram pulse wave signal.
Optionally, the pulse wave signal detection module includes: an optical emission unit for emitting an optical signal to a measured object; the light receiving unit is used for receiving the light signal reflected by the tested object and converting the light signal into an electric signal to be output; and the signal conditioning module is used for receiving the electric signal output by the light receiving unit and detecting and obtaining the photoplethysmography pulse wave signal.
Optionally, the emission angle of the light signal emitted by the light emitting unit to the object to be measured is 35 ° or less, and the receiving angle of the light signal reflected by the object to be measured received by the light receiving unit is 35 ° or less.
Optionally, the window length of the light emitting unit or the light receiving unit is 2mm, and the depth is 4mm.
Optionally, a fresnel lens is placed above the light emitting unit or the light receiving unit.
Optionally, a distance between the light emitting unit and the light receiving unit is in a range of 2.5mm to 5.5 mm.
Optionally, the three-dimensional pressure detection module includes: an arm beam and at least three force sensors; at least two force sensors of the at least three force sensors are arranged on different sides of the arm beam, and at least one force sensor is arranged on the lower bottom surface of the arm beam; the pulse wave signal detection module is arranged on the upper bottom surface of the arm beam.
Optionally, the at least three force sensors are orthogonally placed on the side and lower bottom surfaces of the arm beam.
Optionally, the three-dimensional pressure detection module is driven in a pulse mode.
Optionally, the signal processing module is further configured to:
Generating a pulse wave curve based on the pulse wave signal, wherein the pulse wave curve is a change curve of amplitude of the pulse wave signal relative to time;
Generating a pressure curve based on the three-dimensional pressure signal, the pressure curve being a change curve of an absolute value of the three-dimensional pressure with respect to time;
Fitting a relation curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure by adopting at least one of a polynomial, a single Gaussian or a double Gaussian algorithm; and
And calculating the blood pressure of the tested object based on the relation curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure and the generated blood pressure calculation model.
Optionally, the signal processing module is further configured to: detecting absolute values of pressure components of the three-dimensional pressure in three orthogonal directions according to the three-dimensional pressure signals; and
And fitting the absolute value of the three-dimensional pressure according to the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions.
Optionally, the signal processing module fits the absolute value of the three-dimensional pressure using the following formula:
Wherein P is the absolute value of the three-dimensional pressure, k is a linear coefficient, b is a correction value, A, B, C is the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions, respectively.
Optionally, the blood pressure calculation model is generated by machine learning training data; the training data includes pulse wave profile data, pressure profile data, and blood pressure data corresponding to the pulse wave profile data and the pressure profile data.
In a second aspect, an embodiment of the present application provides a blood pressure measurement method, applied to a blood pressure measurement device, including:
the pulse wave signal detection module detects a pulse wave signal of a detected object;
The three-dimensional pressure detection module detects a three-dimensional pressure signal corresponding to the three-dimensional pressure applied to the pulse wave signal detection module by the detected object; and
And the signal processing module calculates the blood pressure of the tested object according to the pulse wave signal and the three-dimensional pressure signal.
The three-dimensional pressure detection module is used for detecting the three-dimensional pressure signal corresponding to the three-dimensional pressure applied to the pulse wave signal detection module by the user, so that the three-dimensional pressure value between the user and the pulse wave signal detection module can be calculated, and the blood pressure of the user can be accurately calculated.
Optionally, the pulse wave signal is a photoplethysmogram pulse wave signal.
Optionally, the pulse wave signal detection module detects a pulse wave signal of the detected object, and further includes: the light emitting unit emits light signals to the object to be measured; the light receiving unit receives the light signal reflected by the tested object and converts the light signal into an electric signal to be output; and the signal conditioning module receives the electric signal output by the light receiving unit and detects and obtains the photoplethysmography pulse wave signal.
Optionally, the signal processing module calculates, according to the pulse wave signal and the three-dimensional pressure signal, a blood pressure of the measured object, and further includes:
Generating a pulse wave curve based on the pulse wave signal, wherein the pulse wave curve is a change curve of amplitude of the pulse wave signal relative to time;
Generating a pressure curve based on the three-dimensional pressure signal, the pressure curve being a change curve of an absolute value of the three-dimensional pressure with respect to time;
Fitting a relation curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure by adopting at least one of a polynomial, a single Gaussian or a double Gaussian algorithm; and
And calculating the blood pressure of the tested object based on the relation curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure and the generated blood pressure calculation model.
Optionally, the generating a pressure curve based on the three-dimensional pressure signal further includes:
Detecting absolute values of pressure components of the three-dimensional pressure in three orthogonal directions according to the three-dimensional pressure signals; and
And fitting the absolute value of the three-dimensional pressure according to the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions.
Optionally, the fitting of the absolute values of the three-dimensional pressure according to the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions uses the following formula:
Wherein P is the absolute value of the three-dimensional pressure, k is a linear coefficient, b is a correction value, A, B, C is the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions, respectively.
Optionally, the blood pressure calculation model is generated by machine learning training data; the training data includes pulse wave profile data, pressure profile data, and blood pressure data corresponding to the pulse wave profile data and the pressure profile data.
Detailed Description
The following description of the embodiments of the present application will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are some, but not all embodiments of the present application.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this specification and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.
In addition, unless a specified order is explicitly stated in the context of the present application, the process steps described herein may be performed in a different order than specified, i.e., each step may be performed in a specified order, substantially concurrently, in reverse order, or in a different order.
In the prior art, when the finger pressure oscillometric method is used for measuring the blood pressure of the user, only one-dimensional pressure sensor is used for detecting the vertical downward pressure applied by the user on the blood pressure measuring device, however, the inventor finds that the pressure applied by the user in the blood pressure measuring process is not only a component in the vertical direction, and if only the vertical downward pressure component is detected and used for calculating the blood pressure value of the user, the measured blood pressure value result has obvious error.
In order to improve accuracy of a blood pressure detection result, in a first aspect, an embodiment of the present application provides a blood pressure measurement device for measuring blood pressure of a measured object. The blood pressure measurement device may be integrated in various types of wearable devices, examples of which may include: smart watches, smart bracelets, smart armbands, smart finger rings, wireless headsets, and the like, and are not limited thereto.
Fig. 1 is a schematic structural diagram of a blood pressure measurement device according to an embodiment of the present application; the blood pressure measurement device 100 includes: a pulse wave signal detection module 110, a three-dimensional pressure detection module 120, and a signal processing module 130. The pulse wave signal detection module 110 may detect a pulse wave signal of the detected object; the three-dimensional pressure detection module 120 may detect a three-dimensional pressure signal corresponding to the three-dimensional pressure applied to the pulse wave signal detection module 110 by the measured object; the signal processing module 130 may calculate the blood pressure of the measured object according to the detected pulse wave signal and the three-dimensional pressure signal.
When measuring blood pressure, the user can press the finger on the pulse wave signal detection module 110 and gradually increase the pressure; in this process, the pressure applied by the finger to the pulse wave signal detection module 110 is usually a three-dimensional vector force, and if only the pressure component vertically downward is detected and the pressure component horizontally is ignored, the actual pressure value between the finger and the pulse wave signal detection module 110 cannot be obtained, so that a larger error exists in the blood pressure detection result. Therefore, the blood pressure measuring device 100 in the embodiment of the application adopts the three-dimensional pressure detecting module 120 to detect the three-dimensional pressure between the finger and the pulse wave signal detecting module 110, thereby improving the accuracy of the blood pressure detecting result.
In one possible embodiment, the pulse wave signal is a photoplethysmography (Photo Plethysmo Graphy, PPG) signal, i.e., a PPG signal.
Fig. 2 is a schematic structural diagram of a pulse wave signal detection module according to an embodiment of the present application; the pulse wave signal detection module 200 includes: the light emitting unit 210, the light receiving unit 220, and the signal conditioning module 230. Wherein the light emitting unit 210 may emit light signals to the user's finger; the light receiving unit 220 may receive the light signal reflected by the finger of the user and convert the light signal into an electrical signal containing pulse wave information, i.e. a PPG original signal; the signal conditioning module 230 may receive the PPG raw signal output by the light receiving unit 220, and detect the PPG signal.
Specifically, the light emitting unit 210 may be a light emitting element such as a light emitting diode (LightEmittingDiode, LED), an organic light emitting diode, a phosphor, etc., and may be capable of emitting a detection light such as a visible light (e.g., green light or red light) or an infrared light of a specific wavelength to a user's finger; the light receiving unit 220 may be a photoelectric conversion element such as a photodiode (PhotonicDiode, PD), a phototransistor, an avalanche photodiode, or a photomultiplier tube, and is capable of receiving the detection light reflected by or transmitted through the finger of the user and converting it into the PPG original signal.
The signal conditioning module 230 may include a current/voltage amplifying circuit, a filtering circuit, etc., to convert the received PPG original signal from a current signal to a voltage signal, amplify the voltage signal, and the filtering circuit may filter the amplified voltage signal to filter a direct current component, i.e. a signal component without pulse wave information, while retaining an alternating current component containing pulse wave information, and finally generate a PPG signal.
In one possible embodiment, the light emitting unit 210 emits the light signal to the user's finger at an emission angle of 35 ° or less, and the light receiving unit 220 receives the light signal reflected by the user's finger at an reception angle of 35 ° or less.
Limiting the emission angle of the light emitting unit and the receiving angle of the light receiving unit to a smaller angle range can enable the light receiving unit to receive a light signal with enough intensity, reduce noise such as ambient light contained in the light signal, and the like, and is beneficial to improving the signal quality of the PPG signal.
Preferably, the emission angle at which the light emitting unit 210 emits the light signal is 30 ° or less, and the reception angle at which the light receiving unit 220 receives the reflected light signal is 30 ° or less.
In one possible embodiment, the window length of the light emitting unit 210 and the light receiving unit 220 is 2mm and the depth is 4mm.
The proper windowing length and depth are selected to limit the emission angle of the light emitting unit and the receiving angle of the light receiving unit within proper angle ranges, so that noise such as ambient light and the like contained in the light receiving unit can be reduced while the light receiving unit can receive a light signal with enough intensity, and the signal quality of the PPG signal is improved.
Fig. 3 is a schematic structural diagram of a light emitting unit and a light receiving unit according to an embodiment of the present application; wherein, the LED320, as a light emitting unit, can emit a light signal of a specific wavelength to a user's finger; the PD330, as a light receiving unit, may receive light signals transmitted and/or reflected by a user's finger. A light-transmitting cover plate 310 is disposed above the LEDs 320 and the PD330, and a finger can be pressed against the upper surface of the light-transmitting cover plate 310 when a user performs blood pressure measurement.
In one possible embodiment, a Fang Fangzhi fresnel lens on the LED320 and PD330 may be provided to focus the detection light emitted by the LED320 and the detection light received by the PD330 that is transmitted and/or reflected by the user's finger; specifically, a fresnel lens may be separately disposed above the LED320 and the PD330, or a fresnel lens may be simultaneously disposed above the LED320 and the PD 330.
The light emitting unit is enabled to collimate the emitted light signals, the light receiving unit is enabled to collimate the received light signals, and the signal quality of the measured PPG signals is improved.
In one possible embodiment, the distance between the LED320 and the PD330 is in the range of 2.5mm to 5.5 mm.
The light emitting unit and the light receiving unit are placed at proper intervals, so that the detection light emitted by the light emitting unit is fully received by the light receiving unit after being reflected by the finger of a user; the distance between the light emitting unit and the light receiving unit may be specifically determined according to the wavelength of the detection light emitted by the light emitting unit, for example, when the wavelength of the detection light is short, the distance between the light emitting unit and the light receiving unit may be set to be small; when the wavelength of the detection light is long, the distance between the light emitting unit and the light receiving unit may be set to be large.
The number of the light emitting units may be one or a plurality of light emitting units; when a plurality of light emitting units exist, light signals with different wavelengths can be emitted to the measured object respectively; the light emitting unit may be a light emitting element formed by packaging a plurality of different light sources together. In addition, the number of the light receiving units may be one or more, and may be used to obtain at least one PPG signal. For example, the pulse wave signal detection module may include two light emitting units, one of which is a green LED and the other of which is a red LED, and cause the green LED and the red LED to emit green light and red light in a time-sharing manner, and sequentially receive the green light and the red light reflected by the finger of the user by one PD; or two PDs are respectively arranged to receive green light and red light reflected by the fingers of the user.
The kind, number, and positional relationship of the light emitting units and the light receiving units may be specifically determined according to the actual application scene, the detection purpose, the installation position and the size of the pulse wave signal detection module, and the like, which is not limited by the embodiment of the present application.
In addition, the pulse wave signal detection module may not only adopt a PPG method, that is, measure the PPG signal of the measured object based on optical technology, but also adopt a method based on acoustics or electromagnetism, for example, an electret microphone or a millimeter wave radar sensor, etc. to detect the pulse wave signal.
Fig. 4A and 4B are schematic diagrams of a three-dimensional structure and a schematic diagram of a bottom view of a three-dimensional pressure detection module according to an embodiment of the present application, respectively; the three-dimensional pressure detection module 400 includes an arm beam 410, strain gages 420, 430, 440, and 450 placed on four sides of the arm beam, and a piezoelectric sensor 460 placed on a lower bottom surface of the arm beam.
Wherein, the origin of the coordinate axis is located at the geometric center of the three-dimensional pressure detection module 400, the x-axis and the y-axis are parallel to the bottom surface of the three-dimensional pressure detection module 400, and the z-axis is perpendicular to the bottom surface of the three-dimensional pressure detection module 400; the strain gauge 420 and the strain gauge 440 are placed in the positive and negative directions of the x-axis, respectively; strain gauge 430 and strain gauge 450 are placed in the positive and negative directions of the y-axis, respectively; piezoelectric sensor 460 is placed in the negative direction of the z-axis and is used to detect a pressure component along the negative direction of the z-axis. The arm beam 410 may be used as a strain matrix, and when the arm beam 410 deforms under the action of the three-dimensional pressure applied by the user, the strain gauge 420, the strain gauge 430, the strain gauge 440 and the strain gauge 450 also deform (stretch or compress) accordingly, and meanwhile, the resistance value of the strain gauge is also changed, so that the voltage applied to the strain gauge is changed, and finally, the three-dimensional pressure signal is generated. The four strain gages may be made of a metal material or a semiconductor material, and the three-dimensional pressure detection module 400 may be integrated inside the wearable device.
It should be noted that the three-dimensional pressure detection module may be implemented not only in the form shown in fig. 4A and 4B, but also in the form of a force sensor such as a piezoelectric thin film sensor, a millimeter wave radar sensor, or an acceleration sensor, or in the form of a combination of force sensors; the number, type, placement position, and the like of the force sensors in the three-dimensional pressure detection module may be set according to the actual application scenario, detection purpose, position, size, and the like of the three-dimensional pressure detection module, and for example, when the three-dimensional pressure detection module is configured in such a manner that an arm beam is used as a strain body and strain gauge is attached, one, two, or four strain gauges may be provided on four side surfaces of the arm beam, respectively, and connection may be performed in a wheatstone bridge configuration.
Fig. 5A is a schematic diagram of the overall three-dimensional structure of a pulse wave signal detection module and a three-dimensional pressure detection module according to an embodiment of the present application; the pulse wave signal detection module 510 may be substantially the same as the pulse wave signal detection module 200 shown in fig. 2, and the three-dimensional pressure detection module 520 may be substantially the same as the three-dimensional pressure detection module 400 shown in fig. 4A or 4B. The pulse wave signal detection module 510 is placed on the upper bottom surface of the arm beam 521 of the three-dimensional pressure detection module 520; the pulse wave signal detection module 510 may further include: a pressing plate 511 against which a user can press a finger when measuring blood pressure; the light-transmitting cover plate 512 may transmit and irradiate the light signal emitted from the light emitting unit in the pulse wave signal detection module 510 to the user's finger, and transmit and receive the light signal reflected or transmitted by the user's finger to the light receiving unit. When the user presses the finger against the pressing plate 511, the lower three-dimensional pressure detection module 520 may detect the three-dimensional pressure between the finger and the pulse wave signal detection module 510.
Fig. 5B is a schematic circuit diagram of the whole circuit structure of the pulse wave signal detection module and the three-dimensional pressure detection module according to the embodiment of the application. The three-dimensional pressure detection module can work in a pulse drive bridge mode, for example, three-dimensional pressure between a user finger and the pulse wave signal detection module is detected at a frequency of 10 times per second, so that static power consumption of the system is saved; three power supplies are used for driving the three-way bridge respectively so as to respectively detect and obtain pressure signals corresponding to pressure components of three-dimensional pressure applied to the pulse wave signal detection module by a user in three different directions; the strain gauge or piezoelectric sensor in the three-dimensional pressure detection module is connected with the resistor in a Wheatstone bridge structure, and amplified by the amplifier, so that small resistance value change can be measured.
Fig. 6 is a schematic structural diagram of a signal processing module according to an embodiment of the present application; also, the signal processing module 600 shown in fig. 6 may be an example of the signal processing module 130 shown in fig. 1.
The signal processing module 600 includes: the pulse wave curve generating module 610 may generate a pulse wave curve based on the PPG signal output by the signal conditioning module 230 shown in fig. 2, where the pulse wave curve may be a change curve of the amplitude of the pulse wave signal with respect to time; the pressure curve generation module 620 may generate a pressure curve based on the three-dimensional pressure signal detected by the three-dimensional pressure detection module 520 shown in fig. 5A, wherein the pressure curve may be a change curve of an absolute value of the three-dimensional pressure with respect to time; the blood pressure calculation module 630 may fit a relationship curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure by using a polynomial, single gaussian or double gaussian algorithm, and calculate the blood pressure of the measured object according to the relationship curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure and a pre-generated blood pressure calculation model; the blood pressure calculation model may be generated by machine learning training data, and the training data may include pulse wave profile data, pressure profile data, and blood pressure data corresponding to the pulse wave profile data and the pressure profile data.
The three-dimensional pressure between the detected object and the pulse wave signal detection module is a vector with both size and direction; here, the absolute value of the three-dimensional pressure may be the magnitude of the force having an equivalent relationship with the pressure value of the arterial blood pressure of the user.
Fig. 7 is a schematic structural diagram of a pressure curve generating module according to an embodiment of the present application; the pressure curve generation module 700 shown in fig. 7 may be one example of the pressure curve generation module 620 shown in fig. 6. The pressure curve generation module 700 includes: the pressure component obtaining module 710 may calculate, according to the three-dimensional pressure signal detected by the three-dimensional pressure detecting module 520 shown in fig. 5A, absolute values of pressure components of the three-dimensional pressure applied to the pulse wave signal detecting module 510 by the user in three orthogonal directions, that is, magnitudes of the pressure components in the three orthogonal directions; the three-dimensional pressure value fitting module 720 may fit the absolute values of the three-dimensional pressure according to the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions.
In one possible implementation, the three-dimensional pressure value fitting module 720 may fit the absolute value of the three-dimensional pressure using the following formula:
Where P is the absolute value of the three-dimensional pressure, k is a linear coefficient, b is a correction value, A, B, C is the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions, respectively.
Fig. 8A and 8B are schematic diagrams of a pulse wave curve and a pressure curve according to an embodiment of the present application. The schematic diagram of the pulse wave curve shown in fig. 8A may be a periodic variation curve generated based on the PPG signal output by the signal conditioning module 230 shown in fig. 2, where pulse wave information is included; the horizontal axis of the pulse wave curve is denoted as time and the vertical axis is denoted as the amplitude of the PPG signal.
Because the blood at the pressed position in the finger is gradually extruded to other positions in the process that the finger is pressed above the pulse wave signal detection module and the pressure is gradually increased by the user, the amplitude of the pulse wave signal can show a change trend from small to large to small.
The schematic diagram of the pressure curve shown in fig. 8B may be a non-periodic variation curve generated based on the three-dimensional pressure signal corresponding to the three-dimensional pressure applied to the pulse wave signal detection module 510 by the user detected by the three-dimensional pressure detection module 520 shown in fig. 5A; the horizontal axis of the pressure curve is expressed as time and the vertical axis is expressed as the absolute value of the three-dimensional pressure.
Because the user's finger may appear to shake slightly during the gradual increase in pressure, the applied pressure does not increase uniformly, but rather exhibits some fluctuation.
In a second aspect, as shown in fig. 9, a flowchart of a blood pressure measurement method according to an embodiment of the present application is provided, and the method can be applied to the blood pressure measurement device 100 shown in fig. 1; the blood pressure measuring method specifically comprises the following steps:
Step S101: the pulse wave signal detection module 110 detects a pulse wave signal of a subject.
Step S102: the three-dimensional pressure detection module 120 detects a three-dimensional pressure signal corresponding to the three-dimensional pressure applied to the pulse wave signal detection module 110 by the subject.
Step S103: the signal processing module 130 calculates the blood pressure of the measured object according to the pulse wave signal and the three-dimensional pressure signal.
In the above blood pressure measurement process, the pulse wave signal detection module 110 and the three-dimensional pressure detection module 120 may synchronously start detection and synchronously end detection. The three-dimensional pressure detection module 120 can detect the three-dimensional pressure applied to the pulse wave signal detection module 110 by the user, thereby improving the accuracy of the blood pressure detection result.
As a possible embodiment, the pulse wave signal is a PPG signal measured by photoplethysmography.
Specifically, as shown in fig. 10, the pulse wave signal detection module for detecting the pulse wave signal of the detected object may include the following steps, which are described below in conjunction with the schematic structural diagram of the pulse wave signal detection module shown in fig. 2:
step S201: the light emitting unit 210 emits an optical signal to the object to be measured.
Step S202: the light receiving unit 220 receives the light signal reflected by the object to be measured and converts it into an electrical signal to be output.
Step S203: the signal conditioning module 230 receives the electrical signal output by the light receiving unit 220, and detects the PPG signal.
The number of the light emitting units may be one or a plurality of light emitting units; when a plurality of light emitting units exist, light signals with different wavelengths can be emitted to the measured object respectively; the light emitting unit may be a light emitting element formed by packaging a plurality of different light sources together. In addition, the number of the light receiving units may be one or more, and may be used to obtain at least one PPG signal.
As shown in fig. 11, the calculation of the blood pressure of the measured object by the signal processing module according to the pulse wave signal and the three-dimensional pressure signal may specifically include the following steps, which are described below in conjunction with the schematic structural diagram of the signal processing module shown in fig. 6:
step S301: the pulse wave curve generating module 610 generates a pulse wave curve based on the pulse wave signal, wherein the pulse wave curve is a change curve of the amplitude of the pulse wave signal with respect to time.
Step S302: the pressure curve generation module 620 generates a pressure curve based on the three-dimensional pressure signal, the pressure curve being a change curve of an absolute value of the three-dimensional pressure with respect to time.
The pulse wave curve and the pressure curve may be generated simultaneously; wherein the horizontal axis of the pulse wave curve may be denoted as time and the vertical axis may be denoted as the amplitude of the PPG signal; the horizontal axis of the pressure curve may be expressed as time and the vertical axis may be expressed as an absolute value of the three-dimensional pressure.
Step S303: the blood pressure calculation module 630 fits a relationship curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure by using a polynomial, single gaussian or double gaussian algorithm, and calculates the blood pressure of the measured object based on the relationship curve between the amplitude of the pulse wave signal and the absolute value of the three-dimensional pressure and the generated blood pressure calculation model.
As a possible implementation manner, the blood pressure calculation model may be generated by performing machine learning on training data; the training data includes pulse wave profile data, pressure profile data, and blood pressure data corresponding to the pulse wave profile data and the pressure profile data.
Specifically, as shown in fig. 12, the generating a pressure curve based on the three-dimensional pressure signal may include the following steps, which are described below in conjunction with the schematic structural diagram of the pressure curve generating module shown in fig. 7:
step S401: the pressure component acquisition module 710 calculates absolute values of pressure components of the three-dimensional pressure in three orthogonal directions from the three-dimensional pressure signal.
Step S402: the three-dimensional pressure value fitting module 720 fits the absolute values of the three-dimensional pressure based on the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions.
As one possible implementation, the three-dimensional pressure value fitting module 720 fits the absolute value of the three-dimensional pressure according to the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions, specifically using the following formula:
Where P is the absolute value of the three-dimensional pressure, k is a linear coefficient, b is a correction value, A, B, C is the absolute values of the pressure components of the three-dimensional pressure in three orthogonal directions, respectively.
Finally, it should be noted that: the above embodiments are only for illustrating the technical solution of the present application, and not for limiting the same; although the application has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the application.