JP2005021452A - Pulse wave measuring module and pulse wave measuring method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To measure a pulse in reducing the effect of noise generating in everyday life. <P>SOLUTION: A pressure measuring means 11 obtains several pressure measurements by measuring the pressures caused by contact in various locations including vascular position in human body and other positions. A blood vessel positioning means 129 determines the vascular position based on several pressure measurements. A first extract means 129 extracts at least a first pressure measurement value obtained in the vascular location determined from several pressure measurements. A first representative value determination means determines a first representative value from a first pressure measurement. The second extract means 129 extracts at least a second pressure measurement value obtained in a vascular location determined from several pressure measurements. The second representative value determination means determines a second representative value from a second pressure measurement. A difference calculation means 129 calculates a difference between the first representative value and the second representative value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a pulse wave measurement module and a pulse wave measurement method for the purpose of health management by sleep state measurement, autonomic nervous system state measurement, mental load measurement, etc., especially for the influence of measurement data due to disturbance in daily life. The present invention relates to a pulse wave measurement module and a pulse wave measurement method to be reduced.
[0002]
[Prior art]
Heart rate is an index that reflects various human conditions, and is useful not only for medical purposes but also for ergonomic use such as sleep state measurement, autonomic nervous system state measurement, and mental load measurement. . The increase in heart rate is caused by the activation of the sympathetic nervous system associated with mental load such as exercise and tension, and posture change. It is said that the fluctuation component of the heartbeat also reflects the activity of the autonomic nervous system.
[0003]
The heart rate is measured mainly by two types of methods: one obtained from the R wave interval of the electrocardiogram and one that captures a peripheral blood flow change as a pulse wave. For electrocardiogram measurement, it is necessary to wear a total of three electrodes, ie, two electrodes sandwiching the heart and an indifferent electrode, and it is difficult for a general healthy person to use in daily life.
[0004]
Since the pulse wave fluctuates in synchronization with the heartbeat, the heartbeat can be acquired from this peak interval. Further, it can be used widely such as differentiating the waveform twice and detecting the degree of arteriosclerosis from the waveform. There are mainly two types of pulse wave measurement methods: photoelectric and pressure. The photoelectric method can be measured basically simply by attaching a light transmitting / receiving device to the finger pad, palm, earlobe, etc. (see, for example, Patent Document 1, Patent Document 2, or Patent Document 3). . In addition, the pressure method, which is another method, acquires a change in the pressure of the skin on an artery such as a wrist with a minute pressure sensor (see, for example, Patent Document 4).
[0005]
[Patent Document 1]
Japanese Patent No. 2770371
[0006]
[Patent Document 2]
Japanese Patent No. 3243970
[0007]
[Patent Document 3]
Japanese Patent No. 3208538
[0008]
[Patent Document 4]
Japanese Patent No. 3029912
[0009]
[Problems to be solved by the invention]
In the case of a pulse wave, measurement is simple, but on the other hand, since measurement is performed at the periphery, countermeasures against artifacts are very important because they are easily affected by arm movement and the like. In patent document 4, the countermeasure against an artifact is performed using the several pressure sensor. However, in Patent Document 4, since the process is simplified, a pulse wave cannot be obtained with sufficient accuracy. In Patent Document 4, it is assumed that the artifact is uniform for each sensor, and the case where the artifact is not uniform for each sensor is not considered.
[0010]
An object of the present invention is to provide a pulse wave measurement module and a pulse wave measurement system that can reduce the influence of disturbances that occur in daily life and can measure a pulse even in various situations, in view of the above-described conventional technology. And
[0011]
[Means for Solving the Problems]
The pulse wave measurement module of the present invention is a pulse wave measurement module that measures a pulse wave of a human body in contact with a human body, and measures the pressure due to contact at a plurality of positions including the position of a blood vessel on the human body and other positions. Pressure measurement means for obtaining a plurality of pressure measurement values, blood vessel position determination means for determining the position of the blood vessel based on the plurality of pressure measurement values, and at least one obtained at the position of the blood vessel determined from the plurality of pressure measurement values A first extraction means for extracting one first pressure measurement value; a first representative value determination means for determining a first representative value from the first pressure measurement value; and a plurality of pressure measurement values other than the determined blood vessel position. Second extraction means for extracting at least one second pressure measurement value obtained; second representative value determination means for determining a second representative value from the second pressure measurement value; a first representative value and a second representative Difference calculation to calculate the difference with the value It is provided with means.
[0012]
The pulse wave measurement module of the present invention is a pulse wave measurement module that measures the pulse wave of the human body by contacting the human body, and measures the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions. Pressure measurement means for obtaining a plurality of pressure measurement values, blood vessel position determination means for determining a blood vessel position based on the plurality of pressure measurement values, and a blood vessel position determined from the plurality of pressure measurement values. A first extraction means for extracting at least one first pressure measurement value; a first representative value determination means for determining a first representative value from the first pressure measurement value; and a blood vessel position determined from the plurality of pressure measurement values And a second extraction means for extracting at least one second pressure measurement value obtained at a position other than the position, a second representative value determination means for determining a second representative value from the second pressure measurement value, and a first representative value, The difference from the second representative value And it includes a difference calculation means that out.
[0013]
Furthermore, the pulse wave measurement module of the present invention is a pulse wave measurement module that measures the pulse wave of the human body by contacting the human body, and measures the pressure due to the contact at a plurality of positions including the position of the blood vessel on the human body and other positions. Pressure measurement means for obtaining a plurality of pressure measurement values, blood vessel position determination means for determining a blood vessel position based on the plurality of pressure measurement values, and pressure measurement values obtained at other than the determined blood vessel position. A regression line determining means for determining a regression line that relates the position and the pressure measurement value, a pressure measurement value obtained at the determined blood vessel position, and a pressure measurement determined from the regression line at the position where the pressure measurement value was obtained Difference calculation means for calculating a difference from the value is provided.
[0014]
Still further, the pulse wave measurement module of the present invention is a pulse wave measurement module that measures the pulse wave of the human body in contact with the human body, and determines the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions. A pressure measuring means for obtaining a plurality of pressure measurement values by measuring, a calculating means for calculating a cross-correlation function between the two positions based on the plurality of pressure measurement values, and between the two positions based on the cross-correlation function A phase difference acquisition unit for acquiring a phase difference between the pressure measurement values of the first phase and a phase shift unit for shifting the phase of the waveform corresponding to the pressure measurement value at at least one of the two positions in order to remove the phase difference And adding means for adding the pressure measurement values at the two positions from which the phase difference has been removed.
[0015]
The pulse wave measurement method of the present invention is a pulse wave measurement method for measuring a pulse wave of a human body in contact with the human body, by measuring the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions. A plurality of pressure measurements are obtained, a blood vessel position is determined based on the plurality of pressure measurements, and at least one first pressure measurement obtained at the determined blood vessel position is extracted from the plurality of pressure measurements. , Determining a first representative value from the first pressure measurement value, extracting at least one second pressure measurement value obtained from other than the determined blood vessel position from the plurality of pressure measurement values, and extracting the second representative pressure measurement value from the second pressure measurement value 2 representative values are determined, and a difference between the first representative value and the second representative value is calculated.
[0016]
The pulse wave measurement method of the present invention is a pulse wave measurement method for measuring a pulse wave of a human body in contact with a human body, and measures pressure due to contact at a plurality of positions including the position of a blood vessel on the human body and other positions. To obtain a plurality of pressure measurement values, determine a position of the blood vessel based on the plurality of pressure measurement values, and obtain at least one first pressure measurement value obtained at the determined blood vessel position from the plurality of pressure measurement values. Extracting, determining a first representative value from the first pressure measurement value, extracting at least one second pressure measurement value obtained at a position other than the determined blood vessel position and position from the plurality of pressure measurement values; A second representative value is determined from the measured value, and a difference between the first representative value and the second representative value is calculated.
[0017]
Furthermore, the pulse wave measurement method of the present invention is a pulse wave measurement method for measuring a pulse wave of a human body in contact with the human body, and measures pressure due to contact at a plurality of positions including the position of a blood vessel on the human body and other positions. Regression to obtain a plurality of pressure measurement values, determine the position of the blood vessel based on the plurality of pressure measurement values, and relate the position and the pressure component based on the pressure measurement values obtained at other than the determined blood vessel position A straight line is determined, and the difference between the pressure measurement value obtained at the determined blood vessel position and the pressure measurement value determined from the regression line at the position where the pressure measurement value is obtained is calculated.
[0018]
Still further, the pulse wave measurement method of the present invention is a pulse wave measurement method for measuring a pulse wave of a human body in contact with the human body, wherein the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions is measured. Measure to obtain a plurality of pressure measurements, calculate a cross-correlation function between the two positions based on the plurality of pressure measurements, and based on the cross-correlation function, the phase difference between the pressure measurements between the two positions In order to remove the phase difference, the phase of the waveform corresponding to the pressure measurement value at at least one of the two positions is shifted, and the pressure measurement value at the two positions from which the phase difference is removed is obtained. to add.
[0019]
Here, the representative value is one value extracted from one or more pressure measurement values, and the extraction method is not limited. For example, an average value of one or more pressure measurement values can be a representative value. It is also conceivable to arbitrarily extract one value from one or more pressure measurement values. Further, the average value here is, for example, a value calculated by addition average, geometric average, median, or mode, and represents a representative value obtained by a predetermined calculation from one or more pressure measurement values (amplitude correspondence values). Is. Here, the average value when there is one pressure measurement value is the pressure measurement value itself.
[0020]
As described above, the pressure measurement values corresponding to the pressure values at a plurality of positions on the human body are measured, the pressure measurement values on the blood vessel and other pressure values are obtained, and the pressure measurement values due to the disturbance on the blood vessel are obtained. Only the pressure measurement value due to the pulsation can be extracted, and the influence of the artifact can be reduced. In addition, the influence of noise can be reduced by taking into account the phase difference of the pressure waveform of the pressure measurement value corresponding to the pressure value at a plurality of positions on the human body.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a pulse wave measurement module and a pulse wave measurement system of the present invention will be described with reference to the drawings.
FIG. 1 is a functional block diagram of a sensor module 10 and a display terminal 20 constituting the pulse wave measurement system of the present invention. The pulse wave measurement system includes a sensor module 10 and a display terminal 20.
The sensor module 10 includes a pressure sensor array 11 and a signal processing data storage communication unit 12. The pressure sensor array 11 includes a plurality of pressure sensors 111, 112, and 113. In FIG. 1, only three pressure sensors 111, 112, and 113 are depicted, but this number is not limited to three.
The signal processing data storage communication unit 12 includes pressure sensors 111, 112, 113, amplifiers 121, 122, 123, filters 124, 125, 126, multiplexer 127, A / D converter 128, DSP 129, CPU 130, memory 131, Bluetooth (registration). (Trademark) module 132 and battery 133.
The display terminal 20 includes a Bluetooth module 201, a processing unit 202, and a display unit 203. In the example of FIG. 1, the display terminal 20 includes an arm belt 21, and the arm belt 21 fixes the display terminal 20 to the arm. The display terminal 20 may have a clock function.
[0022]
The pressure sensors 111, 112, and 113 detect the pressure applied to the contact surface in contact with the skin. The pressure sensors 111, 112, and 113 convert the detected pressure into an electrical signal and output it as an analog signal.
The amplifiers 121, 122, and 123 are connected to the corresponding pressure sensors 111, 112, and 113 as shown in FIG. Each amplifier 121, 122, 123 receives the output signal of the corresponding pressure sensor 111, 112, 113 and amplifies the output signal.
The filters 124, 125, and 126 are connected to corresponding amplifiers 121, 122, and 123, respectively, as shown in FIG. Each filter 124, 125, 126 filters the output signal of the corresponding amplifier 121, 122, 123 to remove unnecessary frequency band components other than the band that sufficiently includes the pulsation period component. The multiplexer 127 receives the signals from the filters 124, 125, and 126 and combines these input signals to create a multiplexed signal. The A / D converter 128 converts the multiplexed signal into a digital signal. The DSP 129 performs data processing to be described later based on the signal from the A / D converter 128 and acquires pulse data.
The CPU 130 performs control related to the obtained pulse data. For example, the CPU 130 stores the pulse data in the memory 131. The memory 131 stores and accumulates pulse data. In addition, the CPU 130 instructs the Bluetooth module 132 to transmit the pulse data to the display terminal 20 at a predetermined timing. The Bluetooth module 132 realizes communication by Bluetooth, which is one of short-range wireless communication systems. The Bluetooth module 132 implements short-range wireless communication with the Bluetooth module 201 included in the display terminal 20.
[0023]
The Bluetooth module 201 is similar to the Bluetooth module 132 described above, and realizes short-range wireless communication with the Bluetooth module 132 included in the sensor module 10.
The processing unit 202 processes the pulse data received by the Bluetooth module 201 so as to be displayed on the display unit 203. The display unit 203 inputs the processed data to the processing unit 202 and displays matters related to the pulse data.
[0024]
FIG. 2 is a perspective view of the sensor module 10 of FIG.
The sensor module 10 includes a layer of the pressure sensor array 11 in which the pressure sensors 111, 112, and 113 are arranged in a two-dimensional array, and a layer of the signal processing data storage and communication unit 12. The pressure sensor array 11 detects pressure by a piezoresistive type or a capacitance type. Further, the pressure sensor array 11 and the signal processing data storage communication unit 12 are mounted on the sensor module 10 by using a MEMS (Micro-Electro-Mechanical Systems) technique.
[0025]
FIG. 3 is a schematic diagram in which the sensor module 10 of FIG. 2 is mounted on the skin. The sensor module 10 is formed in a patch type and is mounted so as to be placed on the arterial blood vessel of the wrist.
[0026]
FIG. 4 is a diagram showing a positional relationship between the sensor module 10 of FIG. 2 and an artery. The sensor module 10 is mounted on the wrist so that the row direction or column direction of the pressure sensors of the pressure sensor array 11 is as parallel as possible to the blood vessel.
[0027]
FIG. 5 is a graph showing an example of a pressure waveform measured by the sensor module of FIG. 2 when there is no artifact. FIG. 5 shows a change in amplitude over time, which is a pressure measurement value corresponding to a pressure value obtained by a pressure sensor on the position y-axis in FIG. 4. Artifacts are disturbances caused by the body and cause unnecessary signal components.
Waveform data measured by the pressure sensor array 11 when the sensor module 10 is attached to the wrist as shown in FIG. 4 is synchronized with the pulsation in the pressure sensor located on the artery as shown in FIG. 5 when there is no artifact. As a result, a large amplitude can be obtained. On the other hand, as can be seen from FIG. 5, the pressure sensor located outside the artery does not seem to be synchronized with the pulsation, but only a very small amplitude can be obtained.
[0028]
Thus, when there is no artifact, the pulsation can be obtained accurately, and the pulse can be accurately measured based on this. Next, a method for removing such artifacts and reducing noise that is a disturbance not caused by the body will be described.
[0029]
6 is a diagram showing a pressure sensor on an artery among the pressure sensors of the pressure sensor array constituting the sensor module of FIG. In FIG. 6, the pressure sensor on the artery is shaded.
As shown in FIG. 6, the pressure sensors are arranged in rows and columns in a direction perpendicular to the artery and a direction parallel to the artery as a column. For example, in the first row, amplitude values corresponding to the pressure values detected by the pressure sensors, such as A (1,1), A (2,1)... A (8,1), are obtained. Since the pressure sensor array 11 of FIG. 6 includes 8 × 8 = 64 pressure arrays, the amplitude value detected by the last pressure sensor up to the 8th row is indicated as A (8,8).
[0030]
As shown in FIG. 7 of the next figure, the detected amplitude value of the pressure sensor arranged on the artery is larger than that of the pressure sensor arranged outside the artery. Therefore, referring to the amplitude value detected by the pressure sensor, the sensor module 10 can determine the position of the artery. For example, if a predetermined threshold value is set and the amplitude value detected by the pressure sensor is equal to or greater than the threshold value, the pressure sensor is on the artery, and if it is less than the threshold value, it is determined that the pressure sensor is not on the artery. Good.
[0031]
Moreover, you may determine with the pressure sensor which detected the upper amplitude value among the amplitude values which all the pressure sensors detected being on the blood vessel. For example, the upper amplitude value is larger than the average value of the amplitude values detected by all the pressure sensors.
[0032]
Actually, after the sensor module 10 is mounted, the signal processing data storage communication unit 12 acquires pressure data (amplitude value) from all the pressure sensors for a while (for example, for 10 seconds) under a resting state. Based on the amplitude value of the pressure waveform obtained there, the signal processing data storage communication unit 12 determines whether or not each pressure sensor is on a blood vessel.
[0033]
FIG. 7 is a graph showing an example of a pressure waveform in the first row of the pressure sensor of FIG. 6 when the artifact is uniform. This graph corresponds to an average of amplitude values during a predetermined period and an amplification of the average value. FIG. 7 shows an amplitude value obtained by the pressure sensor arranged in the eighth row in FIG. By referring to the amplitude distribution shown in FIG. 7, it is possible to grasp the position of the blood vessel.
[0034]
FIG. 8 is a flowchart of artifact removal and noise reduction by the pulse wave measurement system of FIG. Here, it is assumed that the artifact is uniform. Since each pressure sensor is small, it is a good approximation that artifacts due to the body are applied uniformly to each pressure sensor. The processing relating to the flowchart of FIG. 8 is executed by the DSP 129.
First, as shown in FIG. 3, the sensor module 10 is mounted on the arterial blood vessel of the wrist, and the blood vessel position is measured (S11). In this blood vessel position measurement, the blood vessel position is determined by the method described above with reference to FIG.
[0035]
An average value of amplitude values obtained from each pressure sensor arranged in a direction substantially orthogonal to the blood vessel and other than the blood vessel position determined in step S11 is calculated (S12). For example, the amplitude value obtained from each pressure sensor is averaged for each row in which the pressure sensors of the pressure sensor array 11 are arranged. Specifically, in the pressure sensors arranged in the first row shown in FIG. 6, A (1,1), A (2,1), A (3,1), A (7,1), And the average value Aa1 of A (8,1) is calculated. Similarly, the average value is calculated for each of the second and subsequent rows.
As a modified example, in step S12, the average value of the amplitude values obtained from the pressure sensors arranged in the direction substantially orthogonal to the blood vessel and other than the blood vessel position determined in step S11 may be calculated. Good. Specifically, in the pressure sensors arranged in the first row shown in FIG. 6, A (1,1), A (2,1), A (3,1), A (4,1), An average value Aa1 ′ of A (5,1), A (6,1), A (7,1), and A (8,1) is calculated. Similarly, the average value is calculated for each of the second and subsequent rows.
[0036]
An average value is calculated from the amplitude values obtained from the pressure sensors arranged in the direction substantially perpendicular to the blood vessel and at the blood vessel position determined in step S11 (S13). For example, similarly to step S12, the amplitude value obtained from each pressure sensor is averaged for each row in which the pressure sensors of the pressure sensor array 11 are arranged. Specifically, the pressure sensors arranged in the first row shown in FIG. 6 calculate the average value Ab1 of A (4,1), A (5,1), and A (6,1). . Similarly, the average value is calculated for each of the second and subsequent rows.
[0037]
The difference between the average value obtained in step S12 and the average value obtained in step S13 is calculated (S14). For example, as described above, the difference between the average value of the amplitude value at the blood vessel position and the average value of the amplitude value at other than the blood vessel position is calculated for each row. Specifically, Ab1-Aa1 is calculated.
Through the calculations from step S11 to step S14 described above, it is possible to remove pressure artifacts and obtain pressure data that reflects only blood pressure fluctuations. Moreover, in said step S12 and step S13, although the average value of the amplitude value of each pressure sensor is calculated, this can be variously modified. For example, step S12 and step S13 may be executed using the amplitude value of one of the pressure sensors as a representative value instead of the average value. Further, step S12 and step S13 may be executed by using the average value of the amplitude values of several pressure sensors as representative values instead of all the pressure sensors in each row. Furthermore, the average value is a value calculated by, for example, addition average, geometric average, median, or mode, and represents a representative value obtained by a predetermined calculation from the amplitude values of one or more pressure sensors. Here, the average value when the amplitude value of a certain pressure sensor is one is the amplitude value itself. In this specification, the average value is used in the above meaning.
[0038]
Next, by adding the amplitude values detected by the pressure sensor, the following process for reducing the influence of noise, which is a disturbance not caused by the body, is performed.
First, the cross-correlation between pressure sensors adjacent in the blood vessel direction is calculated (S15), and the phase difference of the amplitude between the pressure sensors is obtained from the shift of the peak of the cross-correlation function (S16). For example, when the average of amplitude values detected by the pressure sensor is obtained for each row as described above, the cross-correlation is calculated between adjacent rows, and the phase difference is obtained from the shift of the cross-correlation peak. Specifically, in the above case, the phase difference t between Ac1 and Ac2 _Ac12 Ask for.
[0039]
After correcting the phase difference obtained in step S16, the pressure waveform (amplitude distribution) is added. That is, by shifting the phase of one of the pressure waveforms detected by the adjacent pressure sensors by the phase difference obtained between the adjacent pressure sensors so that there is no phase difference between them, the amplitude value at each pressure sensor Is added. For example, if the average of the amplitude values detected by the pressure sensor for each row is obtained as described above, the pressure waveform in either row is eliminated so as to eliminate the phase difference between the amplitude values obtained between adjacent rows. Shift and add. Specifically, in the above case, the waveform of Ac2 is changed to the phase difference t. _Ac12 Is added to Ac1.
[0040]
This addition is repeated between the pressure sensors or between the rows of the pressure sensor array 11 to obtain one time-dependent pressure waveform from the pressure sensor array 11. The obtained pressure waveform is regarded as a pulse waveform, and the peak of the pulse waveform is detected. The pulse is calculated from the time interval between the peaks (S17).
[0041]
In FIG. 8, noise removal (S15, S16) is performed after artifact removal (S12, S13, S14), but artifact removal may be performed after noise removal. For example, take the average of the amplitude values of the pressure sensor for each column, calculate the cross-correlation between those adjacent columns, calculate the phase difference of the amplitude between the columns, and average the columns by the pressure sensor so that there is no phase difference Shift the phase of the pressure waveform obtained in. After that, the pressure sensor column is divided into a column almost on the blood vessel and the other columns, and the average value of the amplitude obtained from the column on the blood vessel and the average value of the amplitude obtained from the column outside the blood vessel Calculate the difference between Based on the obtained pressure waveform depending on the time of the difference, the peak of the pulse waveform is detected, and the pulse is calculated from the time interval between the peaks.
[0042]
Hereinafter, as a specific example, a method of calculating the cross-correlation function in step S15 and obtaining the phase difference of the pressure waveform between the rows will be described.
FIG. 9 is a graph showing how the phase difference is determined based on the cross-correlation function of the pressure waveform between rows.
The cross-correlation between the rows is calculated based on the amplitude value using the time t of the pressure average value for each row of the pressure sensor array 11 after artifact removal obtained in step S14 as a variable. Here, as a specific example, the cross-correlation between the first and second rows of the pressure sensor array 11 is calculated. Assume that the pressure average value in the first row is Ac1 (t), the pressure average value in the second row is Ac2 (t), and the respective distributions shown in FIG. 9 are exhibited. Ac1 (t) and Ac2 (t) shown in FIG. 9 have similar waveforms except for the phase difference due to the pressure sensor detecting the pressure at different positions. Usually, a plurality of waveforms having such a phase difference are obtained in step S14.
[0043]
Two cross-correlation functions of Ac1 (t) and Ac2 (t) are expressed as φ _Ac1Ac2 (T)
φ _Ac1Ac2 (T) = Ac1 (t) * Ac2 (t)
(* Is a convolution operator)
It is expressed. When calculating by substituting Ac1 (t) and Ac2 (t) in FIG. 9 into the above equation, the cross-correlation function φ _Ac1Ac2 (T) has the waveform shown in FIG. φ _Ac1Ac2 (T) is the phase difference t between Ac1 (t) and Ac2 (t) from the position t = 0 as shown in FIG. _Ac12 The function has a peak at a position shifted by the amount. Therefore, φ _Ac1Ac2 When the peak of (t) is detected, the phase difference t _Ac12 Can be acquired (S15).
[0044]
Next, the phase of Ac2 (t) is shifted and added so as to eliminate the phase difference between Ac1 (t) and Ac2 (t). If the added waveform is Ac (t)
Ac (t) = Ac1 (t) + Ac2 (t + t _Ac12 )
Is required. Thereafter, similarly, Ac2 (t) and Ac3 (t), Ac3 (t) and Ac4 (t), etc. are added. Or you may add the pressure waveform of a subsequent line on the basis of Ac1 (t) like Ac1 (t) and Ac3 (t), Ac1 (t) and Ac4 (t).
[0045]
FIG. 10 is a flowchart of artifact removal and noise reduction by a regression line by the pulse wave measurement system of FIG. Steps similar to those in FIG. 8 are denoted by the same reference numerals and description thereof is omitted.
Processing for artifact removal and noise reduction when artifacts are not uniform will be described. Here, it is assumed that the artifact is a linear function (linear) with respect to the position. Since each pressure sensor is composed of a rigid body, when the artifact is not uniform, it is considered that the artifact due to the external pressure due to the movement of the body is linear. Therefore, when the artifact is not uniform, it is a good approximation to consider that the artifact is applied as a linear function in the vertical and horizontal directions of each pressure sensor. 10 is the same as that in FIG. 8 and is executed by the DSP 129.
First, as described with reference to FIG. 8, the blood vessel position is measured (S11), and the blood vessel position is determined.
Based on the amplitude value obtained from each pressure sensor arranged in a direction substantially perpendicular to the blood vessel and other than the blood vessel position determined in step S11, a regression line that relates the position and the amplitude value is determined using the position as a variable. (S22). For example, the regression line is determined based on the amplitude value obtained from each pressure sensor for each row where the pressure sensors of the pressure sensor array 11 are arranged. Specifically, in the pressure sensors arranged in the first row shown in FIG. 6, A (1,1), A (2,1), A (3,1), A (7,1), Based on A and (8, 1), a regression line A1 (y) is obtained from the horizontal position y and the amplitude value. The regression line A1 (y) is
A1 (y) = p × y + c (p and c are constants)
It is expressed as A1 (y) is an estimated value of an amplitude value due to an artifact with respect to the horizontal direction y in the first row. Similarly, the regression line is calculated for each row in the second and subsequent rows.
[0046]
A difference between the amplitude value of the pressure sensor at the blood vessel position and the artifact value corresponding to the position is calculated from the regression line corresponding to the position (S23). Thereafter, for example, an average is acquired for each row of the difference data. The value after the difference calculation is a value from which the artifact is removed.
Through the above calculation from step S11 to step S23, it is possible to obtain pressure data that removes linear function artifacts and reflects only blood pressure fluctuations.
The steps for reducing the influence of noise, which is a disturbance that is not caused by the subsequent body, are the same as steps S15, S16, and S17 described with reference to FIG. 8, and even when there is a linear function artifact, The influence of noise can be reduced.
[0047]
As described above, the sensor module 10 in which a plurality of minute pressure sensors are arranged in an array estimates a signal due to a disturbance based on signals from sensors other than those under the artery, and separates the pulse wave signal and the signal due to the disturbance into the disturbance. Robust pulse wave measurement is possible.
[0048]
FIG. 11 is a graph showing an example of a pressure waveform in the first row of the pressure sensor of FIG. 6 when artifacts are not uniform. The straight line indicated by the dotted line in FIG. 11 is the regression line calculated in step S22 in FIG. A curve indicated by a solid line is an amplitude value detected by each pressure sensor.
[0049]
FIG. 12 is a view showing a modification of the sensor module 10 in which the pressure sensors of FIG. 1 are arranged in a circle on the pressure sensor array 31.
In the sensor module 10 shown in FIG. 2, since the pressure sensors are arranged in a matrix, when the positional relationship between the pressure sensor placement direction and the blood vessel direction of the arterial blood vessel of the wrist is to be set, the sensor module 10 is placed on the wrist. When mounting, it is necessary to consider the arrangement direction of the pressure sensor of the sensor module 10.
[0050]
If the pressure sensors 311, 312, and 313 are arranged in a circular shape on the pressure sensor array 31 as shown in FIG. 12, there is an effect that it is not necessary to arrange the sensor module 30 in consideration of the arrangement direction of the pressure sensors. . When the user attaches the sensor module 30 to the wrist, the sensor module 30 can be attached without worrying about the arrangement direction of the pressure sensor.
The configuration and operation of other sensor modules 30 are the same as those of the sensor module 10 described above. The same applies to the display terminal 20. Further, artifact removal and noise reduction by the pulse wave measurement system including the sensor module 30 can be achieved by the procedures described with reference to FIGS. 8 and 10 and related drawings.
[0051]
FIG. 13 is a diagram illustrating an example of a pulse wave measurement system in which the sensor module 10 and the display terminal 20 of FIG.
Although FIG. 1 shows a configuration in which data can be exchanged between the Bluetooth module 132 of the sensor module 10 and the Bluetooth module 201 of the display terminal 20, it is not limited to this configuration. For example, as shown in FIG. 13, the sensor module 10 may be attached to the wrist part of the wrist belt 21 of the wristwatch and integrated with the display terminal 20. In this case, the sensor module 10 and the display terminal 20 may be connected by wire, and data exchange may be performed via the wire.
[0052]
Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.
[0053]
【The invention's effect】
According to the pulse wave measurement module and the pulse wave measurement system of the present invention, it is possible to reduce the influence of disturbances that occur in daily life and to measure the pulse even in various situations.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a sensor module and a display terminal that constitute a pulse wave measurement system of the present invention.
FIG. 2 is a perspective view of the sensor module of FIG.
FIG. 3 is a schematic diagram in which the sensor module of FIG. 2 is mounted on the skin.
4 is a diagram showing a positional relationship between the sensor module of FIG. 2 and an artery.
FIG. 5 is a graph showing an example of a pressure waveform measured by the sensor module of FIG. 2 when there is no artifact.
6 is a view showing a pressure sensor on an artery among the pressure sensors of the pressure sensor array constituting the sensor module of FIG. 2;
7 is a graph showing an example of a pressure waveform in the first row of the pressure sensor in FIG. 6 when the artifact is uniform.
8 is a flowchart of artifact removal and noise reduction by the pulse wave measurement system of FIG.
FIG. 9 is a graph showing how a phase difference is determined based on a cross-correlation function of pressure waveforms between rows.
10 is a flowchart of artifact removal and noise reduction by a regression line by the pulse wave measurement system of FIG.
11 is a graph showing an example of a pressure waveform in the first row of the pressure sensor of FIG. 6 when artifacts are not uniform.
12 is a view showing a modified example of a sensor module in which the pressure sensors of FIG. 1 are arranged in a circle on the pressure sensor array.
13 is a diagram showing an example of a pulse wave measurement system in which the sensor module and the display terminal of FIG. 1 are integrated by an arm belt.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Sensor module, 11 ... Pressure sensor array, 12 ... Signal processing data storage communication part, 20 ... Display terminal, 21 ... Arm belt, 30 ... Sensor module, 31 ... Pressure sensor array, 111, 112, 113, 311, 312, 313 ... Pressure sensor, 121, 122, 123 ... Amplifier, 124, 125, 126 ... Filter, 127 ... Multiplexer, 128 A / D converter, 129 ... DSP, 130 ... CPU, 131 ... memory, 132, 201 ... Bluetooth module, 133 ... battery, 202 ... processing unit, 203 ...・ Display

Claims (13)

In the pulse wave measurement module that measures the pulse wave of the human body in contact with the human body,
Pressure measuring means for measuring a pressure at a plurality of positions including a position of a blood vessel on the human body and other positions to obtain a plurality of pressure measurement values;
A blood vessel position determining means for determining the position of the blood vessel based on the plurality of pressure measurement values;
First extraction means for extracting at least one first pressure measurement value obtained at the determined blood vessel position from the plurality of pressure measurement values;
First representative value determining means for determining a first representative value from the first pressure measurement value;
A second extracting means for extracting at least one second pressure measurement value obtained from a position other than the determined blood vessel position from the plurality of pressure measurement values;
Second representative value determining means for determining a second representative value from the second pressure measurement value;
A pulse wave measurement module comprising difference calculation means for calculating a difference between the first representative value and the second representative value. In the pulse wave measurement module that measures the pulse wave of the human body in contact with the human body,
Pressure measuring means for measuring a pressure at a plurality of positions including a position of a blood vessel on the human body and other positions to obtain a plurality of pressure measurement values;
A blood vessel position determining means for determining the position of the blood vessel based on the plurality of pressure measurement values;
First extraction means for extracting at least one first pressure measurement value obtained at the determined blood vessel position from the plurality of pressure measurement values;
First representative value determining means for determining a first representative value from the first pressure measurement value;
A second extraction means for extracting at least one second pressure measurement value obtained from a position other than the determined blood vessel position and the position from the plurality of pressure measurement values;
Second representative value determining means for determining a second representative value from the second pressure measurement value;
A pulse wave measurement module comprising difference calculation means for calculating a difference between the first representative value and the second representative value. Further comprising blood vessel direction determining means for determining an extension direction of the blood vessel based on the determined position of the blood vessel,
The first representative value determining means and the second representative value determining means are respectively configured to determine a first representative value and a second representative value from the pressure measurement values at positions in a predetermined direction other than a direction parallel to the determined blood vessel extension direction, respectively. The pulse wave measurement module according to claim 1 or 2, wherein a representative value is determined. The pulse wave measurement module according to claim 3, wherein the predetermined direction is a direction orthogonal to the determined extension direction of the blood vessel. 5. The first representative value determining means and the second representative value determining means obtain an average value from the pressure measurement value, and extract the average value as the representative value. The pulse wave measurement module according to any one of the above. In the pulse wave measurement module that measures the pulse wave of the human body in contact with the human body,
Pressure measuring means for measuring a pressure at a plurality of positions including a position of a blood vessel on the human body and other positions to obtain a plurality of pressure measurement values;
A blood vessel position determining means for determining the position of the blood vessel based on the plurality of pressure measurement values;
A regression line determining means for determining a regression line relating the position and the pressure measurement value based on the pressure measurement value obtained at a position other than the determined blood vessel position;
And a difference calculating means for calculating a difference between the pressure measurement value obtained at the determined blood vessel position and the pressure measurement value determined from the regression line at the position where the pressure measurement value is obtained. The pulse wave measurement module. Further comprising blood vessel direction determining means for determining an extension direction of the blood vessel based on the determined position of the blood vessel,
The regression line determining means determines the regression line based on the pressure measurement value in a predetermined direction other than a direction parallel to the determined blood vessel extension direction,
The difference calculation means is determined from the pressure measurement value obtained at the determined blood vessel position at the position in the predetermined direction and the regression line determined based on the pressure measurement value in the predetermined direction. The pulse wave measurement module according to claim 6, wherein a difference from the pressure measurement value is calculated. The pulse wave measurement module according to claim 7, wherein the predetermined direction is a direction orthogonal to the determined extension direction of the blood vessel. In the pulse wave measurement module that measures the pulse wave of the human body in contact with the human body,
Pressure measuring means for measuring a pressure at a plurality of positions including a position of a blood vessel on the human body and other positions to obtain a plurality of pressure measurement values;
Calculation means for calculating a cross-correlation function between two positions based on the plurality of pressure measurement values;
A phase difference acquisition means for acquiring a phase difference of pressure measurement values between the two positions based on the cross-correlation function;
Phase shift means for shifting a phase of a waveform corresponding to a pressure measurement value at at least one of the two positions in order to remove the phase difference;
A pulse wave measurement module comprising addition means for adding pressure measurement values at the two positions from which the phase difference has been removed. In the pulse wave measuring method for measuring the pulse wave of the human body in contact with the human body,
Measuring the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions to obtain a plurality of pressure measurements;
Determining a position of the blood vessel based on the plurality of pressure measurements;
Extracting from the plurality of pressure measurements at least one first pressure measurement obtained at the determined blood vessel position;
Determining a first representative value from the first pressure measurement,
Extracting at least one second pressure measurement value obtained from other than the determined blood vessel position from the plurality of pressure measurement values;
Determining a second representative value from the second pressure measurement,
A pulse wave measuring method, wherein a difference between the first representative value and the second representative value is calculated. In the pulse wave measuring method for measuring the pulse wave of the human body in contact with the human body,
Measuring the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions to obtain a plurality of pressure measurements;
Determining a position of the blood vessel based on the plurality of pressure measurements;
Extracting from the plurality of pressure measurements at least one first pressure measurement obtained at the determined blood vessel position;
Determining a first representative value from the first pressure measurement,
Extracting from the plurality of pressure measurement values at least one second pressure measurement value obtained at a position other than the determined position and position of the blood vessel;
Determining a second representative value from the second pressure measurement,
A pulse wave measuring method, wherein a difference between the first representative value and the second representative value is calculated. In the pulse wave measuring method for measuring the pulse wave of the human body in contact with the human body,
Measuring the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions to obtain a plurality of pressure measurements;
Determining a position of the blood vessel based on the plurality of pressure measurements;
Based on the pressure measurement obtained at other than the determined blood vessel position, a regression line relating the position and the pressure component is determined,
A pulse wave measuring method comprising calculating a difference between the pressure measurement value obtained at the determined blood vessel position and the pressure measurement value determined from the regression line at the position where the pressure measurement value is obtained . In the pulse wave measuring method for measuring the pulse wave of the human body in contact with the human body,
Measuring the pressure due to contact at a plurality of positions including the position of the blood vessel on the human body and other positions to obtain a plurality of pressure measurements;
Calculating a cross-correlation function between two positions based on the plurality of pressure measurements;
Based on the cross-correlation function, obtain a phase difference of pressure measurements between the two positions;
Shifting the phase of the waveform corresponding to the pressure measurement at at least one of the two positions to remove the phase difference;
A pulse wave measuring method characterized by adding pressure measurement values at the two positions from which the phase difference has been removed.

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