JP2012239474A - Heartbeat measuring device, heartbeat measuring method and heartbeat measuring program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To continuously measure heartbeat intervals.SOLUTION: A heartbeat measuring device 10 measures a first potential difference signal between a first electrode 11a provided in accordance with one hand of an operator who operates the device on a steering portion of the device and a reference electrode 11c provided on a portion different from the steering portion. The heartbeat measuring device 10 measures a second potential difference signal between a second electrode 11b provided in accordance with the other hand of the operator on the steering portion of the device and the reference electrode 11c. The heartbeat measuring device 10 calculates a differential signal by computing the difference between the first and second potential difference signals. When a change is detected in a manner in which the operator grips the first electrode 11a or the second electrode 11b, at this time point, the heartbeat measuring device 10 corrects the time when the peak of amplitude is detected from the first and second potential difference signals or the differential signal, depending on a change in gripping.

Description

  The present invention relates to a heart rate measuring device, a heart rate measuring method, and a heart rate measuring program.

  It is known that electrocardiogram measurement is effective for capturing changes in sleepiness and arousal level of an operator who operates the apparatus. As an example, in order to detect the drowsiness and arousal level of the driver who drives the vehicle, it has been studied to measure the heart rate of the driver. When measuring the driver's heart rate, measure the potential difference signal between the two electrodes in contact with the driver, and then use the electrocardiogram signal obtained from the potential difference signal to determine the driver's sleepiness and arousal level. A physiological state is detected.

  For example, as an example of a technique for measuring the heart rate of an operator, an electrocardiogram detection device has been proposed that can observe heart rate variability independently even when the operation is performed with one hand while using an electrode structure for measuring with both hands. Yes. In this electrocardiogram detection device, the left hand electrode and the right hand electrode are provided in different regions on the steering handle portion that are likely to be gripped by the left and right hands. Furthermore, the electrocardiogram detection device has a left-hand analog circuit and a right-hand analog circuit that detect signals of the left-hand electrode and the right-hand electrode, respectively, using the sheet electrode as a reference potential. Furthermore, the electrocardiogram detection device includes a difference signal detection circuit and a sum signal detection circuit that detect a difference and a sum of output signals of the left-hand analog circuit and the right-hand analog circuit. The electrocardiograph detects the amplitude of the two-hand detection signal output from the difference signal detection circuit and the one-hand detection signal output from the sum signal detection circuit, so that either hand of the driver grips the steering wheel. A signal indicating whether or not a heartbeat and a heartbeat signal at that time are output.

  Furthermore, an arousal level determination device that determines the arousal level of a subject using a heartbeat signal has also been proposed. This arousal level determination device measures the interval at which the amplitude peak of the heartbeat signal is detected, that is, RRI (RR Interval), which is the interval between the R wave and R wave, and calculates the spectral density corresponding to the fluctuation of RRI. To do. Furthermore, the arousal level determination device calculates a maximum spectral density corresponding to the maximum frequency among the calculated spectral densities. Then, the arousal level determination device determines whether or not the subject is awake based on the fluctuation tendency of the maximum frequency and the maximum spectral density.

JP 2009-142575 A International Publication No. 2008/065724

  However, the above-described conventional technology has a problem in that the heartbeat interval cannot be continuously measured as described below.

  That is, when the driver changes the state of holding the handle with one hand to the other hand or both hands, or when the driver changes the state of holding the handle with both hands to one hand, the shape of the measured R wave is also Change. However, in the above electrocardiogram detection device, it is assumed that the RRI fluctuates regardless of the operator's physiological state before and after the grip method changes when the handle grip method changes in measuring the heart rate. Not. For this reason, in the above-mentioned electrocardiogram detection device, discontinuous RRI is measured before and after the grip method is changed. As described above, when the RRI that fluctuates regardless of the physiological state of the operator is measured, even if the wakefulness determination device described above is used, the wakefulness and sleepiness cannot be accurately determined. .

  The disclosed technique has been made in view of the above, and an object thereof is to provide a heart rate measuring device, a heart rate measuring method, and a heart rate measuring program capable of continuously measuring a heart rate interval.

  The heart rate measuring device disclosed in the present application is a reference electrode provided at a location different from the first electrode provided on the steering portion of the device corresponding to one hand of an operator who operates the device and the steering portion. And a first measuring unit for measuring the first potential difference signal. The heartbeat measuring device is configured to measure a second potential difference signal between a second electrode provided on the steering unit of the device corresponding to the other hand of the operator and the reference electrode. Part. The heartbeat measuring apparatus calculates a difference signal by calculating a difference between a first potential difference signal measured by the first measurement unit and a second potential difference signal measured by the second measurement unit. A calculation unit for calculating; When a change is detected in the manner in which the operator grips the first electrode or the second electrode, the heartbeat measuring device has an amplitude peak from an electrocardiogram signal at the time when the change is detected. A correction unit that corrects the detected time according to the change in the grip; The electrocardiogram signal includes the first potential difference signal, the second potential difference signal, or the difference signal.

  According to one aspect of the heartbeat measuring device disclosed in the present application, there is an effect that heartbeat intervals can be continuously measured.

FIG. 1 is a functional block diagram illustrating the configuration of the heartbeat measuring apparatus according to the first embodiment. FIG. 2 is a diagram illustrating an example of a method for measuring an electrocardiogram signal. FIG. 3A is a diagram illustrating a waveform example of an electrocardiogram signal stored in the waveform storage unit. FIG. 3B is a diagram illustrating a waveform example of an electrocardiogram signal stored in the waveform storage unit. FIG. 3C is a diagram illustrating a waveform example of an electrocardiogram signal stored in the waveform storage unit. FIG. 3D is a diagram illustrating a waveform example of an electrocardiogram signal stored in the waveform storage unit. FIG. 3E is a diagram illustrating a waveform example of the electrocardiogram signal stored in the waveform storage unit. FIG. 4 is a diagram illustrating the time difference of the amplitude peak between the grip patterns. FIG. 5 is a flowchart illustrating the procedure of the heart rate measurement process according to the first embodiment. FIG. 6 is a flowchart illustrating the procedure of the heart rate measurement process according to the first embodiment. FIG. 7 is a flowchart illustrating the procedure of the heart rate measurement process according to the first embodiment. FIG. 8 is a flowchart illustrating the procedure of the heart rate measurement process according to the first embodiment. FIG. 9 is a schematic diagram illustrating an example of a computer that executes a heart rate measurement program according to the first and second embodiments.

  Embodiments of a heart rate measuring device, a heart rate measuring method, and a heart rate measuring program disclosed in the present application will be described below in detail with reference to the drawings. Note that this embodiment does not limit the disclosed technology. Each embodiment can be appropriately combined within a range in which processing contents are not contradictory.

[Configuration of heart rate measurement device]
First, the functional configuration of the heartbeat measuring device according to the present embodiment will be described. FIG. 1 is a functional block diagram illustrating the configuration of the heartbeat measuring apparatus according to the first embodiment. The heartbeat measuring device 10 shown in FIG. 1 uses a first electrode 11a and a second electrode 11b provided on the steering wheel of the vehicle corresponding to the left and right hands of the operator, and a reference electrode 11c for measuring a reference potential. The interval of the heartbeat of the operator is measured from the electrocardiogram signal measured in this manner. In the example of FIG. 1, the case of measuring the heart rate of the driver who drives the vehicle is exemplified, but the same applies to the case where the subject operates other devices such as an aircraft or other steering units such as a mouse and a keyboard. Can be applied to.

  Here, the heart rate measuring apparatus 10 according to the present embodiment is provided at a location different from the handle and the first electrode 11a provided corresponding to one hand of the operator who operates the vehicle on the handle of the vehicle. A first potential difference signal is measured with respect to the reference electrode 11c. Further, the heartbeat measuring device 10 according to the present embodiment measures the second potential difference signal between the second electrode 11b and the reference electrode 11c provided on the vehicle handle corresponding to the other hand of the operator. To do. Furthermore, the heartbeat measuring device 10 according to the present embodiment calculates a difference signal by calculating a difference between the first potential difference signal and the second potential difference signal. In addition, the heartbeat measuring device 10 according to the present embodiment executes the following process when a change in the grip of the operator's hand with respect to the first electrode 11a or the second electrode 11b is detected. . In other words, the heartbeat measuring device 10 according to the present embodiment responds to the change in grip by determining the time when the peak of amplitude is detected from the first potential difference signal, the second potential difference signal, or the difference signal at the time when the change is detected. To correct.

  As described above, the heartbeat measuring device 10 according to the present embodiment, when a change is detected in the manner of gripping, the first potential difference signal, the second potential difference signal, or the difference when the manner of gripping is not changed. Correction is made to the estimated time when the peak of amplitude is measured from the signal. In the above-described conventional technique for determining the arousal level from the spectral density corresponding to the fluctuation of the RRI, for example, when the RRI is about 500 msec (120 beats / minute), the change of about 1/100 to 1/1000 of the RRI is regarded as the fluctuation. . Therefore, the RRI becomes discontinuous before and after the grip method is changed, and if the RRI is apparently changed to 1/100 to 1/1000, the arousal level and sleepiness cannot be accurately determined. In the heartbeat measuring device 10 according to the present embodiment, even when the R wave interval measured from the heartbeat signal fluctuates before and after the grip method changes, the heartbeat interval, so-called RRI, is obtained. (RR Interval) can be corrected appropriately. Therefore, according to the heartbeat measuring apparatus 10 according to the present embodiment, it is possible to continuously measure RRI. Thereby, in the heartbeat measuring device 10 according to the present embodiment, it is possible to suppress a decrease in the arousal level determination accuracy due to the grip change.

  As shown in FIG. 1, the heartbeat measuring device 10 includes a first electrode 11a, a second electrode 11b, a reference electrode 11c, a first measurement unit 12a, a second measurement unit 12b, and a calculation unit. 13 and a measurement unit 14. Furthermore, the heartbeat measuring device 10 includes a waveform storage unit 15, a determination unit 16, a correction amount storage unit 17, and a correction unit 18. The heart rate measuring device 10 is connected to a wakefulness level determining device 20 that determines the wakefulness level and drowsiness from the RRI of the operator measured by the heart rate measuring device 10.

  The first electrode 11a, the second electrode 11b, and the reference electrode 11c are electrodes used to measure an operator's electrocardiogram signal. Among these, the 1st electrode 11a is provided in the position with a high possibility of being gripped with a right hand rather than an operator's left hand on the steering wheel of a vehicle. The second electrode 11b is provided at a position where the possibility of being gripped by the left hand is higher than the right hand of the operator on the handle of the vehicle. The reference electrode 11c is an electrode used for measuring the reference potential. The reference electrode 11c is also referred to as a “reference electrode” or a “reference electrode”.

  The first measurement unit 12a is a processing unit that measures the first potential difference signal between the first electrode 11a and the reference electrode 11c. The second measurement unit 12b is a processing unit that measures the second potential difference signal between the second electrode 11b and the reference electrode 11c. Further, the calculation unit 13 calculates a difference between the first potential difference signal measured by the first measurement unit 12a and the second potential difference signal measured by the second measurement unit 12b, thereby calculating a difference signal. Is a processing unit for calculating.

  For example, when the first electrode 11a is gripped by the operator's right hand, the right electrocardiogram signal, so-called second lead, is measured as the first potential difference signal by the first measurement unit 12a. Further, when the second electrode 11b is gripped by the left hand of the operator, an electrocardiogram signal of the left hand, so-called third lead, is measured as the second potential difference signal by the second measuring unit 12b. Further, when the first electrode 11a is gripped by the operator's right hand and the second electrode 11b is gripped by the operator's left hand, an electrocardiogram signal of both hands, the so-called first lead, is obtained by the calculation unit 13. Measured as a differential signal. Here, the electrocardiogram signal measured when the operator grips with the hand recommended for contact with each electrode has been described. However, the first electrode 11a or the second electrode is not necessarily described. It is not necessary for each electrode to be gripped with the hand recommended for contact with 11b.

  Here, a method for measuring an electrocardiographic signal using the first electrode 11a, the second electrode 11b, and the reference electrode 11c will be described with reference to FIG. FIG. 2 is a diagram illustrating an example of a method for measuring an electrocardiogram signal. As shown in FIG. 2, the 1st electrode 11a is provided in the circular arc part from the 10:00 direction to the 6 o'clock direction among the outer periphery of a handle | steering-wheel. The second electrode 11b is provided on a circular arc portion from the 6 o'clock direction to the 10 o'clock direction on the outer periphery of the handle. On the other hand, the reference electrode 11c is provided on the seat surface of the seat on which the operator of the vehicle is seated, and is grounded so as to be equal to the electric potential of the vehicle. Although the case where the reference electrode 11c is provided on the seat surface of the seat on which the operator is seated is illustrated here, it is not necessarily provided on the seat surface of the seat, and may be provided on the backrest of the seat.

  In such an environment where the first electrode 11a, the second electrode 11b, and the reference electrode 11c are installed, the myocardial action potential of the operator is input from the first electrode 11a to the first measurement unit 12a. In addition, the potential of the vehicle body is input from the reference electrode 11c. The first measuring unit 12a to which these potentials are input amplifies the myocardial action potential when the potential of the vehicle body is used as a reference, and outputs the amplified myocardial action potential as a first potential difference signal.

  In addition, the myocardial action potential of the operator is input from the second electrode 11b to the second measurement unit 12b, and the potential of the vehicle body is input from the reference electrode 11c to the second measurement unit 12b. The second measuring unit 12b to which these potentials are input amplifies the myocardial action potential when the potential of the vehicle body is used as a reference, and outputs the amplified myocardial action potential as a second potential difference signal. Note that, for the first measurement unit 12a and the second measurement unit 12b, an arbitrary amplifier circuit including an operational amplifier, for example, a constant multiplier, or a voltage follower can be used.

  Further, the calculation unit 13 receives the first potential difference signal measured by the first measurement unit 12a and the second potential difference signal measured by the second measurement unit 12b. The calculation unit 13 to which these signals are input calculates a difference signal by calculating a difference between the first potential difference signal and the second potential difference signal. Note that an arbitrary difference calculation circuit including an operational amplifier can be adopted as the calculation unit 13.

  In the example of FIG. 2, an example of electrode installation assuming a case where the operator is right-handed is illustrated, but the disclosed apparatus is not limited to being used by a right-handed operator. For example, when the operator is left-handed, the first electrode 11a is provided in a part of the handle from the 2 o'clock direction to the 6 o'clock direction, and the first electrode 11a is provided in the part from the 6 o'clock direction to the 2 o'clock direction. Two electrodes 11b can also be provided.

  Returning to the description of FIG. 1, the measurement unit 14 is a processing unit that measures a heartbeat interval, so-called RRI, from the difference signal, the first potential difference signal, or the second potential difference signal. As one aspect, the measurement unit 14 selects an electrocardiogram signal that is estimated to be superimposed with the operator's electrocardiogram signal among the difference signal, the first potential difference signal, and the second potential difference signal. Then, the measurement unit 14 measures the RRI of the operator by detecting the amplitude peak from the selected electrocardiogram signal and calculating the time interval of the time when the amplitude peak is detected.

  To explain this, first, the measurement unit 14 calculates the noise level of the differential signal measured by the calculation unit 13. At this time, when the noise level of the difference signal is smaller than the predetermined threshold value N, the measurement unit 14 uses the difference signal for RRI measurement. On the other hand, when the noise level of the difference signal is equal to or higher than the threshold value N, the operator's hand is not gripped by both the first electrode 11a and the second electrode 11b, and an electrocardiogram signal is included in the difference signal. It can be seen that they are not superimposed. Therefore, the measurement unit 14 determines the first potential measured by the first measurement unit 12a in order to further determine whether the ECG signal is superimposed on either the first potential difference signal or the second potential difference signal. The noise level of the potential difference signal is calculated.

  At this time, when the noise level of the first potential difference signal is smaller than the threshold value N, the measurement unit 14 uses the first potential difference signal for RRI measurement. On the other hand, when the noise level of the first potential difference signal is equal to or higher than the threshold value N, the operator's hand is not gripped by the first electrode 11a, and an electrocardiogram signal is superimposed on the first potential difference signal. You can see that it is not. Therefore, the measurement unit 14 calculates the noise level of the second potential difference signal measured by the second measurement unit 12b in order to further determine whether the electrocardiogram signal is superimposed on the second potential difference signal. . Then, when the noise level of the second potential difference signal is smaller than the predetermined threshold N, the measuring unit 14 uses the second potential difference signal for RRI measurement. In addition, when the noise level of the second potential difference signal is equal to or higher than the threshold value N, it cannot be determined which of the difference signal, the first potential difference signal, and the second potential difference signal is superimposed on the electrocardiogram signal. Therefore, RRI measurement is not executed.

  In this way, after selecting an electrocardiogram signal to be used for RRI measurement, the measurement unit 14 detects a point R at which the amplitude is equal to or greater than a threshold, that is, the amplitude peak, from the selected electrocardiogram signal. Thereafter, the measurement unit 14 measures the RRI of the operator by calculating the difference between the time when the amplitude peak was detected this time and the time when the amplitude peak was detected last time. At this time, the measuring unit 14 detects the change in the way the operator grips the first electrode 11a or the second electrode 11b by the discriminating unit 16, which will be described later. Instead, the time corrected by the correction unit 18 described later is used for RRI measurement. Further, the measuring unit 14 does not use the corrected time, but uses the time when the amplitude peak was detected last time without using the corrected time, even if the time when the amplitude peak was detected last time was corrected by the correction unit 18 described later. Used to measure the operator's RRI. Note that the amplitude peak detection method is not limited to the above-described method. For example, the measurement unit 14 may use a method of using a zero cross point where the differential coefficient of the electrocardiogram signal changes from positive to negative, a method of detecting a peak by performing pattern matching on the amplitude waveform, and the like.

  The waveform storage unit 15 is a storage unit that stores the waveform of the electrocardiogram signal. As one mode of the waveform storage unit 15, data in which a waveform of an electrocardiogram signal such as a first potential difference signal, a second potential difference signal, or a difference signal is associated with each grip pattern is stored. Note that the waveform storage unit 15 is referred to by a determination unit 16 described later in order to determine the grip pattern.

  The “grip pattern” refers to a pattern in which the first electrode 11a and the second electrode 11b are gripped by the operator's right hand, left hand, or both hands. An example of this grip pattern includes a pattern in which both the first electrode 11a and the second electrode 11b are gripped by both hands of the operator. Another example includes a pattern in which only the first electrode 11a is gripped by the operator's right hand, left hand, or both hands. A further example includes a pattern in which only the second electrode 11b is gripped by the operator's right hand, left hand, or both hands. These grip patterns include a pattern in which each electrode is gripped with the hand recommended to be in contact with the first electrode 11a or the second electrode 11b, and each electrode with the opposite hand. A gripped pattern is also included.

  In the following, the patterns in which each electrode is gripped by the hand recommended to be in contact with the first electrode 11a or the second electrode 11b are referred to as “two-hand grip”, “right hand grip”, “left hand grip”. May be called. In the following, each pattern in which each electrode is gripped by the hand opposite to the hand recommended to be in contact with the first electrode 11a or the second electrode 11b is referred to as “first electrode + left hand grip”. And “second electrode + right hand grip”. Furthermore, in the following, each pattern in which the same electrode is gripped by both hands of the operator is referred to as “first electrode + strained two-handed grip”, “second electrode + strained two-handed grip”, “first electrode and second May be referred to as “electrode + strained two-handed grip”.

  3A to 3E are diagrams illustrating examples of waveforms of the electrocardiogram signals stored in the waveform storage unit 15. FIG. 3A shows a “two-hand grip” waveform in which the first electrode 11a is gripped by the operator's right hand and the second electrode 11b is gripped by the operator's left hand. FIG. 3B shows a “right hand grip” waveform in which the first electrode 11a is gripped by the right hand of the operator and the second electrode 11b is not gripped. FIG. 3C shows a “left hand grip” waveform in which the first electrode 11a is not gripped and the second electrode 11b is gripped by the left hand of the operator. FIG. 3D shows a waveform of “first electrode + distorted two-hand grip” in which the first electrode 11a is gripped by both hands of the operator and the second electrode 11b is not gripped. FIG. 3E shows a waveform of “first electrode and second electrode + strained two-hand grip” in which the first electrode 11a is gripped by both hands of the operator and the second electrode 11b is gripped by the left hand of the operator. Indicates.

  In the case of the “two-hand grip” shown in FIG. 3A, at least the waveform of the difference signal 31T among the waveforms of the first potential difference signal 31R, the second potential difference signal 31L, and the difference signal 31T is held by the waveform storage unit 15. In the case of the “right hand grip” shown in FIG. 3B, the first potential difference signal 32R excluding the second potential difference signal 32L and the difference signal 32T in which only noise is measured is held by the waveform storage unit 15. In the case of the “left hand grip” shown in FIG. 3C, the waveform storage unit 15 holds the second potential difference signal 33L excluding the first potential difference signal 33R and the difference signal 33T in which only noise is measured. In the case of “first electrode + strained two-hand grip” shown in FIG. 3D, the first potential difference signal 34R except for the second potential difference signal 34L and the difference signal 34T in which only noise is measured is the waveform storage unit. 15 is held. In the case of “first electrode and second electrode + strained two-hand grip” shown in FIG. 3E, at least a difference signal among the waveforms of the first potential difference signal 35R, the second potential difference signal 35L, and the difference signal 35T. The waveform storage unit 15 holds the 35T waveform.

  The waveform of the electrocardiogram signal is the waveform storage unit that represents the waveform of the first potential difference signal, the second potential difference signal, or the difference signal of each grip pattern derived by shifting to the calibration mode before the vehicle starts driving. 15 can be registered. In addition, the waveform of the first potential difference signal, the second potential difference signal, and the difference signal of each grip pattern derived using the first measurement unit, the second measurement unit, and the calculation unit included in another device is stored as a waveform. It is also possible to register in the unit 15.

  The determination unit 16 is a processing unit that uses the waveform storage unit 15 to determine a pattern in which the operator grips the handle. As one aspect, the determination unit 16 determines the similarity between the waveform of the electrocardiogram signal stored for each grip pattern by the waveform storage unit 15 and the waveform of the first potential difference signal, the second potential difference signal, or the difference signal. The pattern in which the operator grips the handle is determined.

  Explaining this, when the difference signal is used for the RRI measurement, the determination unit 16 calculates the difference signal of “two-handed grip” and “first electrode and second electrode + distorted two-handed grip”, and calculates The similarity of the waveform with the difference signal calculated by the unit 13 is calculated. At this time, the determination unit 16 calculates a correlation coefficient between the two difference signals by cumulatively adding the difference of the amplitude value at each time between the two difference signals. When such a correlation coefficient is obtained, the similarity between the two signals increases as the correlation coefficient value decreases. Then, the determination unit 16 calculates the similarity of the “two-hand grip” among the similarities calculated between the difference signals of “two-hand grip” and “first electrode and second electrode + distorted two-hand grip”. When is high, it is determined that the grip pattern is “two-handed grip”. On the other hand, when the similarity between “first electrode and second electrode + strained two-handed grip” is higher, the determination unit 16 determines that the grip pattern is “first electrode and second electrode + strained two-handed grip”. ". Here, the case where the similarity is calculated by accumulating the difference of the amplitude values between the two difference signals is illustrated, but the similarity is obtained by pattern matching the waveform shape between the two difference signals. It may be calculated.

  In addition, when the first potential difference signal is used for RRI measurement, the determination unit 16 performs the following processing. That is, the discriminating unit 16 uses the difference signal of “first electrode + distorted two-handed grip”, “right hand grip” and “first electrode + left hand grip” and the first measurement unit 12a measured by the first measuring unit 12a. The similarity of the waveform with the potential difference signal is calculated. When the similarity between the difference signals of the above three grip patterns and the similarity of “first electrode + distorted two-handed grip” is the maximum, the determination unit 16 determines that the grip pattern Is “first electrode + distorted two-handed grip”. Further, the determination unit 16 determines that the grip pattern is the “right hand grip” when the similarity degree of the “right hand grip” is the maximum. Further, when the similarity of “first electrode + left hand grip” is the maximum, the determination unit 16 determines that the grip pattern is “first electrode + left hand grip”.

  In addition, when the second potential difference signal is used for RRI measurement, the determination unit 16 performs the following processing. That is, the determination unit 16 uses the difference signal of “second electrode + distorted two-hand grip”, “left hand grip” and “second electrode + right hand grip” and the second signal measured by the second measurement unit 12b. The similarity of the waveform with the potential difference signal is calculated. Then, when the similarity between the difference signals of the above three grip patterns and the similarity of “second electrode + distorted two-handed grip” is the maximum, the determination unit 16 determines the grip pattern. Is “second electrode + strained two-handed grip”. Further, the determination unit 16 determines that the grip pattern is the “left hand grip” when the similarity of the “left hand grip” is the maximum. The determination unit 16 determines that the grip pattern is “second electrode + right hand grip” when the similarity of “second electrode + right hand grip” is the maximum.

  When the grip pattern is determined in this way, the determination unit 16 determines whether or not the grip pattern determined this time has changed from the grip pattern determined last time. That is, the determination unit 16 makes a transition to a grip pattern in which the current determination result is different between “two-handed grip”, “right-handed grip”, “left-handed grip”, and “distorted two-handed grip” compared to the previous determined result. It is determined whether or not.

  The correction amount storage unit 17 is a storage unit that stores a correction amount for correcting a time when an amplitude peak is detected. As one aspect of the correction amount storage unit 17, data associated with a combination of grip patterns and a correction amount corresponding to the combination is stored. Note that the correction amount storage unit 17 refers to a correction amount corresponding to a combination of grip patterns before and after the grip method is changed by the correction unit 18 to be described later in order to correct the time when the peak of the amplitude is detected. .

  FIG. 4 is a diagram illustrating the time difference of the amplitude peak between the grip patterns. FIG. 4 shows a first potential difference signal 41R, a second potential difference signal 41L, and a difference signal 41T measured when the grip pattern is “two-hand grip”. Further, FIG. 4 shows a case where the first potential difference signal 42R measured when the grip pattern is “first electrode + left hand grip”, and when the grip pattern is “first electrode + distorted two-hand grip”. A measured first potential difference signal 43R is shown. In the example of FIG. 4, the time difference when the amplitude t is detected from the difference signal 41 </ b> T of “two-hand grip” as a reference is illustrated.

  As shown in FIG. 4, the time difference of the amplitude peak between the first potential difference signal 41R of the “right hand grip” and the difference signal 41T is “δt_R”. Further, the second potential difference signal 41L of the “left hand grip” and the first potential difference signal 42R of the “first electrode + left hand grip” have a time difference of the amplitude peak between the difference signal 41T and “δt_L”. Further, the first potential difference signal 43R of the “first electrode + strained two-hand grip” has a time difference in amplitude peak from the difference signal 41T of “δt_T”.

  For example, when the grip pattern changes from “two-hand grip” to “right hand grip”, the amplitude peak of the first potential difference signal 41R is detected earlier than the difference signal 41T by the time difference “δt_R”. The correction amount may be set to “+ δt_R”. When the grip pattern changes from “two-hand grip” to “left-hand grip”, the amplitude peak of the first potential difference signal 42R is detected later than the difference signal 41T by the time difference “δt_L”. The correction amount may be set to “−δt_L”. Further, when the grip pattern changes from “two-handed grip” to “distorted two-handed grip”, the amplitude peak of the first potential difference signal 43R is detected earlier by the time difference “δt_T” than the difference signal 41T. The correction amount may be “+ δt_T”. Thus, from the time t0 at which the amplitude peak is detected from the reference difference signal 41T, the time at which the amplitude peak is detected from the electrocardiogram signals of the “right hand grip”, “left hand grip” or “distorted two-hand grip”. Each correction amount can be obtained by subtracting.

  Similarly, when the grip pattern changes from “distorted two-handed grip” to “right-handed grip”, “left-handed grip” or “two-handed grip”, the correction amount is obtained as follows. That is, the amplitude peak detection time “t0−δt_T” of the first potential difference signal 43R is subtracted from the amplitude peak detection time t0 of the difference signal 41T, and further the first potential difference signal 41R and the second potential difference signal 41L. Alternatively, it is obtained by adding the detection time of the amplitude peak of the difference signal 41T.

  Similarly, when the grip pattern changes from “right hand grip” to “left hand grip”, “two-handed grip” or “distorted two-handed grip”, the respective correction amounts are obtained as follows. That is, the amplitude peak detection time “t0−δt_R” of the first potential difference signal 41R is subtracted from the amplitude peak detection time t0 of the difference signal 41T, and further, the second potential difference signal 41L, the difference signal 41T, or the first Is obtained by adding the detection time of the amplitude peak of the potential difference signal 43R.

  Similarly, when the grip pattern changes from “left hand grip” to “right hand grip”, “two-handed grip” or “distorted two-handed grip”, the respective correction amounts are obtained as follows. That is, the amplitude peak detection time “t0 + δt_L” of the second potential difference signal 41L is subtracted from the amplitude peak detection time t0 of the difference signal 41T, and further, the first potential difference signal 41R, the difference signal 41T, or the first Is obtained by adding the detection time of the amplitude peak of the potential difference signal 43R.

  Thus, when the time difference between “right hand grip”, “left hand grip” and “distorted two-hand grip” with respect to “two-hand grip” is known, the combination of the grip patterns before and after the grip method changes The correction amount corresponding to can be registered. In the example of FIG. 4, the case where the amplitude t is detected from the difference signal 41 </ b> T of “two-hand grip” is used as a reference, but the time at which the amplitude peak is detected from another electrocardiogram signal is illustrated. It does not matter as a standard.

  When a change is detected in the manner of gripping by the operator by the determination unit 16, the correction unit 18 detects the peak of the amplitude from the first potential difference signal, the second potential difference signal, or the difference signal when the change is detected. It is a processing unit that corrects the time at which the is detected according to the change of the grip.

  As one aspect, the correction unit 18 is a combination of grip patterns before and after a change in the grip method among the correction amounts stored in the correction amount storage unit 17 when a change in the grip pattern is detected by the determination unit 16. The correction amount corresponding to is read. Then, the correction unit 18 corrects the time when the amplitude peak was detected by the measurement unit 14 this time according to the correction amount read out earlier. For example, when the correction amount is a positive value, the correction unit 18 corrects the time when the peak of the amplitude is detected this time to the time obtained by adding the value of the correction amount. Further, when the correction amount is a negative value, the correction unit 18 corrects the time when the amplitude peak is detected this time to the time obtained by subtracting the value of the correction amount. If no change in the grip pattern is detected by the determination unit 16, there is a high possibility that the RRI does not fluctuate regardless of the physiological state of the operator. The recorded time is used as it is for RRI measurement.

  Note that various integrated circuits and electronic circuits can be employed for the measurement unit 14, the determination unit 16, and the correction unit 18. For example, an ASIC (Application Specific Integrated Circuit) is an example of the integrated circuit. Examples of the electronic circuit include a central processing unit (CPU) and a micro processing unit (MPU).

  In addition, a semiconductor memory element or a storage device can be adopted as a storage unit such as the waveform storage unit 15 and the correction amount storage unit 17. For example, examples of the semiconductor memory element include a video random access memory (VRAM), a random access memory (RAM), a read only memory (ROM), and a flash memory. Examples of the storage device include storage devices such as a hard disk and an optical disk.

[Process flow]
Next, a processing flow of the heartbeat measuring apparatus according to the present embodiment will be described. 5 to 8 are flowcharts illustrating the procedure of the heart rate measurement process according to the first embodiment. This heart rate measurement process is a process that is repeatedly executed when the heart rate measurement process is powered on.

  As shown in FIG. 5, the first measurement unit 12a measures the first potential difference signal between the first electrode 11a and the reference electrode 11c, and the second measurement unit 12b uses the second electrode 11b. The second potential difference signal is measured between the reference electrode 11c and the reference electrode 11c (step S101). Subsequently, the calculation unit 13 calculates a difference signal by calculating a difference between the first potential difference signal and the second potential difference signal (step S102).

  Thereafter, the measurement unit 14 calculates the noise level of the difference signal measured by the calculation unit 13 (step S103). At this time, if the noise level of the difference signal is smaller than the predetermined threshold N (Yes at Step S104), the measurement unit 14 selects the difference signal for RRI measurement. Then, the measurement unit 14 detects a point R at which the amplitude is greater than or equal to the threshold, that is, the amplitude peak, from the selected electrocardiogram signal (step S105).

  Subsequently, the determination unit 16 determines the similarity of the waveform between the difference signal of “two-hand grip” and “first electrode and second electrode + distorted two-hand grip” and the difference signal calculated by the calculation unit 13. Is calculated (step S106).

  If the degree of similarity of “two-hand grip” is higher (Yes at step S107), the determination unit 16 determines that the grip pattern is “two-hand grip” (step S108). On the other hand, when the similarity between “first electrode and second electrode + strained two-hand grip” is higher (No at step S107), the determination unit 16 determines that the grip pattern is “first electrode and second electrode grip”. It is determined that it is “electrode + strained two-handed grip” (step S109).

  On the other hand, when the noise level of the difference signal is equal to or higher than the threshold value N (No in step S104), the operator's hand is not gripped in both the first electrode 11a and the second electrode 11b, and the difference signal It can be seen that the ECG signal is not superimposed on. Therefore, as shown in FIG. 6, the measurement unit 14 calculates the noise level of the first potential difference signal measured by the first measurement unit 12a (step S110).

  At this time, when the noise level of the first potential difference signal is smaller than the threshold value N (Yes in step S111), the measurement unit 14 selects the first potential difference signal for RRI measurement. Then, the measurement unit 14 detects a point R at which the amplitude is greater than or equal to a threshold value from the selected electrocardiogram signal, that is, the amplitude peak (step S112).

  Subsequently, the determination unit 16 uses the difference signal of “first electrode + strained two-handed grip”, “right hand grip” and “first electrode + left hand grip” and the first measurement unit 12a to measure the first signal. The similarity between the waveform and the potential difference signal is calculated (step S113).

  Here, when the degree of similarity of “first electrode + distorted two-handed grip” is the maximum (Yes in step S114), the determination unit 16 determines that the grip pattern is “first electrode + distorted two-handed grip”. It discriminate | determines (step S115).

  Further, when the similarity degree of the “right hand grip” is the maximum (No at Step S114 and Yes at Step S116), the determination unit 16 determines that the grip pattern is the “right hand grip” (Step S117).

  When the similarity of “first electrode + left hand grip” is the maximum (No at Step S114 and No at Step S116), the determination unit 16 determines that the grip pattern is “first electrode + left hand grip”. (Step S118).

  On the other hand, when the noise level of the first potential difference signal is equal to or higher than the threshold value N (No in step S111), the operator's hand is not gripped by the first electrode 11a, and the first potential difference signal is It can be seen that the electric signal is not superimposed. Therefore, as shown in FIG. 7, the measurement unit 14 calculates the noise level of the second potential difference signal measured by the second measurement unit 12b (step S119).

  When the noise level of the second potential difference signal is smaller than the predetermined threshold N (Yes at Step S120), the measuring unit 14 uses the second potential difference signal for RRI measurement. And the measurement part 14 detects the point R from which the amplitude becomes more than a threshold value from the selected electrocardiogram signal, ie, the peak of an amplitude (step S121). When the noise level of the second potential difference signal is equal to or higher than the threshold value N (No in step S120), the electrocardiogram signal is superimposed on any of the difference signal, the first potential difference signal, and the second potential difference signal. RRI measurement is not executed because it is not possible to determine whether or not there is.

  Subsequently, the determination unit 16 uses the difference signal of “second electrode + strained two-hand grip”, “left hand grip” and “second electrode + right hand grip”, and the second signal measured by the second measurement unit 12b. The similarity between the waveform and the potential difference signal is calculated (step S122).

  If the similarity between the “second electrode + distorted two-handed grip” is the maximum (Yes at step S123), the determination unit 16 determines that the grip pattern is “second electrode + distorted two-handed grip”. (Step S124).

  When the similarity degree of the “left hand grip” is the maximum (No at Step S123 and Yes at Step S125), the determination unit 16 determines that the grip pattern is “Left hand grip” (Step S126).

  When the similarity of “second electrode + right hand grip” is the maximum (No at step S123 and negative at step S125), the determination unit 16 has the grip pattern “second electrode + right hand grip”. (Step S127).

  When the grip pattern is discriminated as described above, the discriminating unit 16 judges whether or not the grip pattern discriminated this time has changed from the grip pattern discriminated last time, as shown in FIG. S128).

  Here, when the change of the grip pattern is detected (Yes at Step S128), the correction unit 18 executes the following process. That is, the correction unit 18 corrects the time when the amplitude peak is detected by the measurement unit 14 this time according to the correction amount corresponding to the combination of the grip patterns before and after the grip method is changed (step S129). Thereafter, the measurement unit 14 measures the RRI of the operator by calculating the difference between the time corrected by the correction unit 18 and the time at which the amplitude peak was previously detected (step S130).

  On the other hand, when a change in the grip pattern is detected (No at Step S128), the measurement unit 14 performs the process at Step S130 without executing the process at Step S129, that is, the process for correcting the detection time of the amplitude peak. Transition. That is, the measurement unit 14 measures the RRI of the operator by calculating the difference between the time when the amplitude peak was detected this time and the time when the amplitude peak was detected last time (step S130).

  The RRI thus measured is output to the arousal level determination device 20, and the arousal level determination device 20 determines the arousal level and drowsiness.

[Effect of Example 1]
As described above, the heart rate measurement device 10 according to the present embodiment has the first potential difference signal and the second potential difference signal when a change in the grip method is detected and the grip method does not change. Or it correct | amends to the time estimated that the peak of an amplitude is measured from a difference signal. Therefore, in the heartbeat measuring device 10 according to the present embodiment, even if the interval of the R wave measured from the heartbeat signal fluctuates before and after the grip method changes, the heartbeat interval is varied. The so-called RRI can be corrected appropriately. Therefore, according to the heartbeat measuring apparatus 10 according to the present embodiment, it is possible to continuously measure RRI. Thereby, in the heartbeat measuring device 10 according to the present embodiment, it is possible to cause the wakefulness determination device 20 to accurately determine the wakefulness and sleepiness.

  In addition, the heartbeat measuring device 10 according to the present embodiment has the first potential difference signal, the second potential difference signal, or the second potential difference signal for each pattern in which the first electrode 11a and the second electrode 11b are gripped by the right or left hand of the operator. The waveform of the difference signal is stored. Then, the heartbeat measuring device 10 according to the present embodiment has the stored first potential difference signal, second potential difference signal, or difference signal waveform, and first potential difference signal, second potential difference signal, or difference signal waveform. The pattern in which the operator grips the handle is determined from the similarity. In addition, when the change in the grip pattern is detected, the heartbeat measurement device 10 according to the present embodiment can detect the first potential difference signal, the second potential difference signal, or the second potential difference signal according to the patterns before and after the grip change. The time when the amplitude peak is detected from the difference signal is corrected. For this reason, the heart rate measuring apparatus 10 according to the present embodiment can correct the detection time of the amplitude peak by estimating the fluctuation of the RRI from the change of the grip pattern. Therefore, according to the heartbeat measuring device 10 according to the present embodiment, it is possible to prevent the discontinuous RRI from being measured before and after the grip method is changed with a higher probability.

  Furthermore, the heartbeat measuring device 10 according to the present embodiment further stores the waveform of the first potential difference signal, the second potential difference signal, or the difference signal for a pattern in which the same electrode is gripped by both hands of the operator. For this reason, in the heartbeat measuring device 10 according to the present embodiment, it is possible to accumulate the waveforms of the first potential difference signal, the second potential difference signal, or the difference signal in a manner in which the operator grips the handle. Therefore, the heartbeat measuring device 10 according to the present embodiment can correct the detection time of the amplitude peak by estimating the fluctuation of the RRI from the change of the grip pattern in various situations.

  Although the embodiments related to the disclosed apparatus have been described above, the present invention may be implemented in various different forms other than the above-described embodiments. Therefore, another embodiment included in the present invention will be described below.

[Unit of equipment]
In the first embodiment, the case where the heartbeat measurement device 10 and the arousal level determination device 20 are configured separately is exemplified, but the disclosed device is not limited to this, and the heartbeat measurement device 10 and the arousal level determination device. 20 may be integrated and configured.

[Distribution and integration]
In addition, each component of each illustrated apparatus does not necessarily need to be physically configured as illustrated. In other words, the specific form of distribution / integration of each device is not limited to that shown in the figure, and all or a part thereof may be functionally or physically distributed or arbitrarily distributed in arbitrary units according to various loads or usage conditions. Can be integrated and configured. For example, the first measurement unit 12a, the second measurement unit 12b, the calculation unit 13, the measurement unit 14, the determination unit 16, or the correction unit 18 may be connected as an external device of the heart rate measurement device via a network. In addition, by having the first measurement unit 12a, the second measurement unit 12b, the calculation unit 13, the measurement unit 14, the determination unit 16 or the correction unit 18 in different devices, connected to each other through a network, You may make it implement | achieve the function of said heart rate measuring device.

[Heart rate measurement program]
The various processes described in the above embodiments can be realized by executing a prepared program on a computer such as a personal computer or a workstation. Therefore, in the following, an example of a computer that executes a heart rate measurement program having the same function as that of the above embodiment will be described with reference to FIG.

  FIG. 9 is a schematic diagram illustrating an example of a computer that executes a heart rate measurement program according to the first and second embodiments. As illustrated in FIG. 9, the computer 100 includes an operation unit 110 a, a speaker 110 b, a microphone 110 c, a display 120, and a communication unit 130. Further, the computer 100 includes a CPU 150, a ROM 160, an HDD 170, and a RAM 180. These units 110 to 180 are connected via a bus 140.

  As shown in FIG. 9, the HDD 170 stores in advance a heart rate measurement program 170 a that performs the same functions as the measurement unit 14, the determination unit 16, and the correction unit 18 described in the first embodiment. The heart rate measurement program 170a may be integrated or separated as appropriate, as with each component of the measurement unit 14, the determination unit 16, and the correction unit 18 shown in FIG. In other words, all data stored in the HDD 170 need not always be stored in the HDD 170, and only data necessary for processing may be stored in the HDD 170.

  Then, the CPU 150 reads out the heart rate measurement program 170 a from the HDD 170 and develops it in the RAM 180. Accordingly, as shown in FIG. 9, the heart rate measurement program 170a functions as a heart rate measurement process 180a. The heart rate measurement process 180a expands various data read from the HDD 170 in an area allocated to itself on the RAM 180 as appropriate, and executes various processes based on the expanded data. The heartbeat measurement process 180a includes processes executed by the measurement unit 14, the determination unit 16, and the correction unit 18 illustrated in FIG. 1, for example, the processes illustrated in FIGS. In addition, each processing unit virtually realized on the CPU 150 does not always require that all processing units operate on the CPU 150, and only a processing unit necessary for the processing needs to be virtually realized.

  Note that the heart rate measurement program 170a is not necessarily stored in the HDD 170 or the ROM 160 from the beginning. For example, each program is stored in a “portable physical medium” such as a flexible disk inserted into the computer 100, so-called FD, CD-ROM, DVD disk, magneto-optical disk, or IC card. Then, the computer 100 may acquire and execute each program from these portable physical media. In addition, each program is stored in another computer or server device connected to the computer 100 via a public line, the Internet, a LAN, a WAN, etc., and the computer 100 acquires and executes each program from these. It may be.

DESCRIPTION OF SYMBOLS 10 Heartbeat measuring apparatus 11a 1st electrode 11b 2nd electrode 11c Reference electrode 12a 1st measurement part 12b 2nd measurement part 13 Calculation part 14 Measurement part 15 Waveform memory | storage part 16 Discriminating part 17 Correction amount memory | storage part 18 Correction | amendment part 20 Arousal level determination device

Claims (5)

A first potential difference signal between a first electrode provided on the steering unit of the device corresponding to one hand of an operator operating the device and a reference electrode provided at a location different from the steering unit. A first measuring unit for measuring
A second measuring unit for measuring a second potential difference signal between the second electrode provided on the steering unit of the device corresponding to the other hand of the operator and the reference electrode;
A calculation unit that calculates a difference signal by calculating a difference between the first potential difference signal measured by the first measurement unit and the second potential difference signal measured by the second measurement unit;
When a change is detected in how the operator grips the first electrode or the second electrode, the first potential difference signal, the second potential difference signal, or A heart rate measuring apparatus comprising: a correction unit that corrects a time at which an amplitude peak is detected from the difference signal according to a change in the grip. A storage unit for storing a waveform of the first potential difference signal, the second potential difference signal, or the difference signal for each pattern in which the first electrode and the second electrode are gripped by an operator's right hand or left hand; ,
Similarity between the waveform of the first potential difference signal, the second potential difference signal, or the difference signal stored for each pattern by the storage unit, and the waveform of the first potential difference signal, the second potential difference signal, or the difference signal And a determination unit that determines a pattern in which the operator grips the steering unit,
The correction unit is
When a change in grip pattern is detected by the determination unit, an amplitude peak is detected from the first potential difference signal, the second potential difference signal, or the difference signal according to the pattern before and after the grip change. The heartbeat measuring apparatus according to claim 1, wherein the time is corrected.   The storage unit further stores a waveform of the first potential difference signal, the second potential difference signal, or the difference signal for a pattern in which the same electrode is gripped by both hands of the operator. 2. The heartbeat measuring device according to 2. Computer
A first potential difference signal between a first electrode provided on the steering unit of the device corresponding to one hand of an operator operating the device and a reference electrode provided at a location different from the steering unit. And measuring a second potential difference signal between the second electrode provided on the steering unit of the device corresponding to the other hand of the operator and the reference electrode,
Calculating a difference signal by calculating a difference between the first potential difference signal and the second potential difference signal;
When a change is detected in how the operator grips the first electrode or the second electrode, the first potential difference signal, the second potential difference signal, or A heart rate measuring method comprising: performing each process of correcting a time at which an amplitude peak is detected from the difference signal according to a change in the grip. On the computer,
A first potential difference signal between a first electrode provided on the steering unit of the device corresponding to one hand of an operator operating the device and a reference electrode provided at a location different from the steering unit. And measuring a second potential difference signal between the second electrode provided on the steering unit of the device corresponding to the other hand of the operator and the reference electrode,
Calculating a difference signal by calculating a difference between the first potential difference signal and the second potential difference signal;
When a change is detected in how the operator grips the first electrode or the second electrode, the first potential difference signal, the second potential difference signal, or A heart rate measurement program for executing each process of correcting a time when an amplitude peak is detected from the difference signal according to a change in the grip.

Images