Electrocardiographic waveform processing device, electrocardiographic waveform processing method, and electrocardiographic waveform processing program

Abstract

An electrocardiographic waveform processing device (30) includes: a first assessment unit (34) that performs first filter processing on an electrocardiographic waveform with a bandpass filter of a first frequency band and performs first assessment to assess whether the sum of the absolute values of a first waveform obtained through the first filter processing is less than a first threshold value, for each portion of the first waveform; a second assessment unit (36) that performs second filter processing on the electrocardiographic waveform with a bandpass filter of a second frequency band that differs from the first frequency band and performs second assessment to assess whether the sum of the absolute values of a second waveform obtained through the second filter processing is less than a second threshold value, for each portion of the second waveform; and a third assessment unit (38) that assesses the portions of the electrocardiographic waveform that have passed at least the first assessment or the second assessment to be designated portions that have high reliability.

Description

Electrocardiographic waveform processing device, electrocardiographic waveform processing method, and electrocardiographic waveform processing program

[0001] The present disclosure relates to an electrocardiogram waveform processing device, an electrocardiogram waveform processing method, and an electrocardiogram waveform processing program.

[0002] Japanese Patent Application Laid-Open Publication No. 2010-142456 describes a technology that calculates an RRI (RR-Interval: the time interval between peaks of adjacent R waves) from a heart rate signal, determines whether the calculated RRI is an abnormal value, and if it is determined that the RRI is an abnormal value, recalculates the R wave by comparing it with adjacent RRIs, and recalculates the RRI based on the recalculated R wave.

[0003] The technology described in Japanese Patent Application Laid-Open No. 2010-142456 has the problem that when noise is superimposed on the electrocardiogram waveform and the calculated RRI becomes an abnormal value for a continuous period of time, even if the R wave is recalculated by comparing it with an adjacent RRI, the R wave cannot be calculated properly because the adjacent RRI itself is also an abnormal value.

[0004] The present disclosure provides an electrocardiogram waveform processing device, an electrocardiogram waveform processing method, and an electrocardiogram waveform processing program that can accurately determine highly reliable portions of an electrocardiogram waveform.

[0005] The electrocardiogram waveform processing device according to the first aspect includes a first determination unit that performs a first filtering process by applying a band-pass filter of a first frequency band to an electrocardiogram waveform and performs a first determination by determining, for each portion of the first waveform, whether the sum of absolute values ​​of the first waveform that has undergone the first filtering process is smaller than a first threshold value; a second determination unit that performs a second filtering process by applying a band-pass filter of a second frequency band different from the first frequency band to the electrocardiogram waveform and performs a second determination by determining, for each portion of the second waveform, whether the sum of absolute values ​​of the second waveform that has undergone the second filtering process is smaller than a second threshold value; and a third determination unit that determines, in the electrocardiogram waveform, a portion for which at least one of the first determination and the second determination is positive, as a specific portion with high reliability.

[0006] In a second aspect, in the first aspect, the first frequency band is a frequency band that is approximate to a frequency band of an R wave included in the electrocardiogram waveform, and the second frequency band is a frequency band that includes a frequency band higher than the frequency band of the R wave.

[0007] A third aspect is the first or second aspect, wherein the first frequency band is 10 to 40 Hz and the second frequency band is 30 to 150 Hz.

[0008] In a fourth aspect, in any of the first to third aspects, the third judgment unit judges a portion of the electrocardiogram waveform where both the first judgment and the second judgment are positive to be the specific portion.

[0009] A fifth aspect is any of the first to fourth aspects, wherein the first judgment unit judges whether or not the sum of the absolute values ​​of the first waveform is smaller than the first threshold value and greater than a third threshold value that is smaller than the first threshold value, and the second judgment unit judges whether or not the sum of the absolute values ​​of the second waveform is smaller than the second threshold value and greater than a fourth threshold value that is smaller than the second threshold value.

[0010] A sixth aspect is any of the first to fifth aspects, further including an output unit that calculates an RRI from the specific portion of the electrocardiogram waveform and determines and outputs the subject's physical condition at the specific portion from the calculated RRI, or calculates an RRI from the electrocardiogram waveform and determines the subject's physical condition for each portion from the calculated RRI, and adds the reliability determination result for each portion made by the third determination unit to the determined physical condition of the subject and outputs it.

[0011] In a seventh aspect of the electrocardiographic waveform processing method, a computer executes processing including: performing a first filtering process to apply a band-pass filter of a first frequency band to an electrocardiographic waveform; performing a first determination to determine, for each portion of the first waveform, whether a sum of absolute values ​​of the first waveform that has undergone the first filtering process is smaller than a first threshold value; performing a second filtering process to apply a band-pass filter of a second frequency band different from the first frequency band to the electrocardiographic waveform; performing a second determination to determine, for each portion of the second waveform, whether a sum of absolute values ​​of the second waveform that has undergone the second filtering process is smaller than a second threshold value; and determining, as a specific portion of the electrocardiographic waveform, a portion for which at least one of the first determination and the second determination is affirmative.

[0012] An electrocardiographic waveform processing program according to an eighth aspect causes a computer to execute processing including: performing a first filtering process to apply a band-pass filter of a first frequency band to an electrocardiographic waveform; performing a first determination to determine, for each portion of the first waveform, whether a sum of absolute values ​​of the first waveform that has undergone the first filtering process is smaller than a first threshold value; performing a second filtering process to apply a band-pass filter of a second frequency band different from the first frequency band to the electrocardiographic waveform; performing a second determination to determine, for each portion of the second waveform, whether a sum of absolute values ​​of the second waveform that has undergone the second filtering process is smaller than a second threshold value; and determining, in the electrocardiographic waveform, a portion for which at least one of the first determination and the second determination is affirmative, as a specific portion with high reliability.

[0013] In the first aspect, a specific portion of the electrocardiogram waveform with high reliability is determined by applying a band-pass filter to the electrocardiogram waveform for two different frequency bands and determining whether the sum of the absolute values ​​of the waveform is smaller than a threshold value. This makes it possible to accurately determine a highly reliable portion of the electrocardiogram waveform (a portion with a small amount of superimposed noise) even when a state in which noise is superimposed on the electrocardiogram waveform continues.

[0014] In the second aspect, the first frequency band is set to a frequency band that is close to the frequency band of R waves included in the electrocardiogram waveform, so that the amount of noise that significantly affects the calculation of the RRI can be properly evaluated in the first determination using the first frequency band. Furthermore, although R wave components are mixed into the first determination, the second frequency band is set to a band that includes a frequency band higher than the frequency band of R waves (a band that is less likely to be mixed with R wave components), so that the amount of noise itself can be properly evaluated in the second determination using the second frequency band. Therefore, the highly reliable portion of the electrocardiogram waveform can be accurately determined.

[0015] In the third aspect, the first frequency band is 10 to 40 Hz and the second frequency band is 30 to 150 Hz, so that, similar to the second aspect, it is possible to accurately determine the highly reliable portion of the electrocardiogram waveform.

[0016] In the fourth aspect, a portion of the electrocardiogram waveform where both the first and second determinations are positive is determined to be a specific portion, thereby making it possible to more accurately determine a highly reliable specific portion of the electrocardiogram waveform.

[0017] In a fifth aspect, it is determined whether the sum of the absolute values ​​of the first waveform is smaller than the first threshold and larger than a third threshold that is smaller than the first threshold, and it is also determined whether the sum of the absolute values ​​of the second waveform is smaller than the second threshold and larger than a fourth threshold that is smaller than the second threshold. This makes it possible to prevent the interrupted portion from being erroneously determined as a highly reliable specific portion when the electrocardiogram waveform is temporarily interrupted for some reason.

[0018] In the sixth aspect, when an RRI is calculated from a specific portion of an electrocardiogram waveform and the subject's physical condition at the specific portion is determined and output from the calculated RRI, the subject's physical condition can be accurately determined and output from a highly reliable specific portion of the electrocardiogram waveform. Furthermore, when an RRI is calculated from an electrocardiogram waveform and the subject's physical condition is determined for each portion from the calculated RRI, and the determined subject's physical condition is output together with the reliability determination result for each portion by the third determination unit, the portion of the output subject's physical condition with high accuracy can be determined from the reliability determination result for each portion. Therefore, according to the sixth aspect, an accurate determination result of the subject's physical condition can be obtained.

[0019] Like the first aspect, the seventh aspect can accurately determine the highly reliable part of the electrocardiogram waveform (the part with a small amount of superimposed noise) even when noise is continuously superimposed on the electrocardiogram waveform.

[0020] Like the first aspect, the eighth aspect can accurately determine the highly reliable parts of the electrocardiogram waveform (parts with a small amount of superimposed noise) even when noise is continuously superimposed on the electrocardiogram waveform.

[0021] FIG. 1 is a front view of a steering wheel according to a first embodiment; FIG. 2 is a cross-sectional view of the rim portion as viewed in the circumferential direction of the steering wheel; FIG. 3 is a functional block diagram of a steering ECU according to the first embodiment; FIG. 4 is a flowchart showing an example of electrocardiogram waveform processing; FIG. 5 is a diagram showing an example of an electrocardiogram waveform; (A) is a diagram showing an example of a first waveform that has undergone first filtering processing, and (B) is a diagram showing an example of a second waveform that has undergone second filtering processing; FIG. 6 is a front view of a steering wheel according to a second embodiment; and FIG. 7 is a functional block diagram of a mobile terminal according to the second embodiment.

[0022] Hereinafter, an example of an embodiment of the present disclosure will be described in detail with reference to the drawings.

[0023] [First Embodiment] Fig. 1 shows a steering wheel 12 according to a first embodiment. The steering wheel 12 is disposed in front of a seat (driver's seat) in which a vehicle occupant (driver) sits. In Figs. 1 and 2, the front side of the vehicle is indicated by an arrow FR, the upper side of the vehicle is indicated by an arrow UP, and the right side in the vehicle width direction is indicated by an arrow HR. The radial direction of the steering wheel 12 is indicated by an arrow R, and the circumferential direction of the steering wheel 12 is indicated by an arrow L.

[0024] As shown in FIG. 1, the steering wheel 12 includes an annular rim portion 14 serving as a grip portion, a boss portion 16 located in the center, and stay portions 18. The steering wheel 12 is provided with a metal core. The core is made up of a rim core portion 20 (see FIG. 2) of the rim portion 14, a boss core portion (not shown) of the boss portion, and a stay core portion (not shown) of the stay portions 18, and the rim core portion 20 is formed in an annular (ring-like) shape. In the steering wheel 12, the rim core portion 20 and the boss core portion are connected via the stay core portion, and the core portion forms a framework that integrates the rim portion 14, boss portion 16, and stay portions 18.

[0025] The vehicle is provided with a steering shaft (not shown), which is axially aligned along the longitudinal direction of the vehicle and rotatably supported by the vehicle body. The steering wheel 12 is supported by the steering shaft, with the boss core portion of the boss portion 16 fixed to the rear end of the steering shaft, and is rotatable integrally with the steering shaft. Therefore, when the steering wheel 12 is rotated, the steering shaft is rotated and the vehicle is steered.

[0026] 2, the rim portion 14 has a generally circular (or generally elliptical) cross section in the radial direction of the steering wheel 12, and a base body 22 formed in an annular shape from a resin material such as urethane as an insulating material is disposed within the rim portion 14. The rim portion 14 has a rim core metal portion 20 housed within the base body 22 by insert molding, and the rim core metal portion 20 is covered by the base body 22.

[0027] A decorative portion 24 serving as a contact portion is disposed on the outer periphery of the base body 22, and the entire circumference of the base body 22 in the radial cross section of the steering wheel 12 and the entire circumference (entire area) of the steering wheel 12 are covered with the decorative portion 24. A resin material such as urethane is used as an insulating material for the decorative portion 24, and the rim portion 14 of the steering wheel 12 is decorated with the decorative portion 24. The decorative portion 24 may be made of leather such as tanned leather.

[0028] A touch sensor 28 including a sensor electrode 32 is embedded between the base 22 and the decorative portion 24 in the rim portion 14 of the steering wheel 12. The sensor electrode 32 is formed in a generally strip-like shape from a sheet-like or film-like conductive material. The touch sensor 28 may include a shield electrode formed in a generally strip-like shape from an insulating material, similar to the sensor electrode 32, with the sensor electrode 32 disposed on one side of the strip-like insulating material and the shield electrode disposed on the other side. The sensor electrode 32 (as well as the shield electrode) of the touch sensor 28 may be formed from a conductive cloth in which a conductive material such as a metal is attached to the surface of a stretchable fabric woven with warp and weft threads.

[0029] 1, the touch sensors 28 (sensor electrodes 32) are arranged in the rim portion 14 in a range of approximately halfway around the circumference of the steering wheel 12, with their longitudinal direction aligned with the circumferential direction of the steering wheel 12. Also, as shown in FIG. 2, the touch sensors 28 are wrapped around approximately the entire outer circumference of the base body 22, with each sensor electrode 32 positioned radially outward from the rim portion 14 and their width direction aligned with the circumferential direction of the rim portion 14.

[0030] As a result, the touch sensor 28 is wrapped around the outer peripheral surface of the base body 22 over substantially the entire circumference of the steering wheel 12 and the rim portion 14, and is covered by the decorative portion 24. Furthermore, when the steering wheel 12 is in the straight-ahead steering position (the position shown in FIG. 1 ), one of the two touch sensors 28 is located on the right side of the vehicle and the other is located on the left side of the vehicle, and they are electrically separated. The two touch sensors 28 are each connected to a steering ECU 30 built into the boss portion 16 of the steering wheel 12, for example. Note that the two touch sensors 28 are processed in the same way by the steering ECU 30, and the following description will focus on the configuration corresponding to one touch sensor 28.

[0031] Although not shown, the steering ECU 30 includes a CPU (Central Processing Unit), memories such as ROM (Read Only Memory) and RAM (Random Access Memory), non-volatile storage units such as HDD (Hard Disk Drive) and SSD (Solid State Drive), a communication I / F (Interface) unit, and an input / output I / F unit, which are communicatively connected to each other via a bus. The input / output I / F unit is connected to a touch sensor 28 via an A / D converter, as well as to a display unit such as an in-vehicle display and an audio output unit such as an in-vehicle speaker. In the first embodiment, the steering ECU 30 is an example of an electrocardiogram waveform processing device according to the present disclosure.

[0032] An electrocardiographic waveform processing program is stored in the ROM or storage unit of the steering ECU 30. The electrocardiographic waveform processing program is read from the ROM or storage unit and loaded into memory, and the loaded electrocardiographic waveform processing program is executed by the CPU, whereby the steering ECU 30 functions as an electrocardiographic waveform acquisition unit 33, a first determination unit 34, a second determination unit 36, a third determination unit 38, and an output unit 40 shown in Fig. 3 and performs electrocardiographic waveform processing, which will be described later.

[0033] The electrocardiogram waveform acquisition unit 33 acquires the electrocardiogram waveform of the subject (driver) detected by the touch sensor 28 as digital electrocardiogram waveform data via an A / D converter (not shown).

[0034] The first determination unit 34 performs a first filtering process by applying a band-pass filter (BPF) of a first frequency band to the electrocardiographic waveform data acquired by the electrocardiographic waveform acquisition unit 33, and then performs a first determination to determine, for each portion of the first waveform, whether the sum S1 of absolute values ​​of the first waveform after the first filtering process is smaller than a threshold TH1_2 and larger than a threshold TH1_1 that is smaller than the threshold TH1_2. Note that the first frequency band is a frequency band that approximates the frequency band of R waves included in the electrocardiographic waveform (e.g., 0.4 to 40 Hz), e.g., 10 to 40 Hz. The threshold TH1_2 is an example of a first threshold in the present disclosure, and the threshold TH1_1 is an example of a third threshold in the present disclosure.

[0035] The second determination unit 36 ​​performs a second filtering process on the electrocardiographic waveform data acquired by the electrocardiographic waveform acquisition unit 33, applying a band-pass filter (BPF) of a second frequency band different from the first frequency band, and performs a second determination process to determine, for each portion of the second waveform, whether the sum of the absolute values ​​of the second waveform after the second filtering process is smaller than a threshold value TH2_2 and larger than a threshold value TH2_1 that is smaller than the threshold value TH2_2. The second frequency band is a frequency band that includes a frequency band higher than the frequency band of an R wave included in the electrocardiographic waveform, and an example of this is 30 to 150 Hz. The threshold value TH2_2 is an example of a second threshold value in the present disclosure, and the threshold value TH2_1 is an example of a fourth threshold value in the present disclosure.

[0036] The third judgment unit 38 judges that a portion of the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33, for which both the first judgment by the first judgment unit 34 and the second judgment by the second judgment unit 36 ​​are positive, is a specific portion with a high degree of reliability.

[0037] An in-vehicle user interface (UI) unit 42 including a display unit such as an in-vehicle display and an audio output unit such as an in-vehicle speaker is connected to the output unit 40. The output unit 40 calculates an RRI from a specific portion of the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33 that has a high reliability determined by the third determination unit 38, determines the subject's physical condition, more specifically, drowsiness and fatigue level, at the specific portion from the calculated RRI, and outputs the determined drowsiness and fatigue level of the subject via the in-vehicle UI unit 42. In this aspect, for example, when the evaluation value of the subject's drowsiness calculated from the specific portion of the electrocardiogram waveform determined to have a high reliability becomes equal to or greater than a first predetermined value, or when the evaluation value of the subject's fatigue level calculated from the specific portion becomes equal to or greater than a second predetermined value, a warning urging the subject to take a rest is output from the in-vehicle UI unit 42.

[0038] Furthermore, if there is an administrator who manages the physical condition of the subject, the output unit 40 may transmit the determined drowsiness level, fatigue level, etc. of the subject to the administrator terminal 46 via the communication unit 44. In this aspect, a DCM (Data Communication Module) mounted on a vehicle or the like can be used as the communication unit 44. In this aspect, for example, when the evaluation value of the subject's drowsiness calculated from a specific portion of the electrocardiogram waveform determined to have high reliability becomes equal to or greater than a first predetermined value, or when the evaluation value of the subject's fatigue level calculated from the specific portion becomes equal to or greater than a second predetermined value, a warning is output from the administrator terminal 46 to prompt the administrator to take action.

[0039] Next, as an operation of the first embodiment, electrocardiogram waveform processing executed by the steering ECU 30 while the ignition switch of the vehicle in which the steering ECU 30 is installed is turned on will be described with reference to FIG.

[0040] In step 100 of the electrocardiogram waveform processing, the electrocardiogram waveform acquisition unit 33 acquires an electrocardiogram waveform detected by the touch sensor 28 within a predetermined time period in the past. The predetermined time period may be, for example, about one second. An example of an electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33 is shown in FIG. 5 . For example, when the vehicle vibrates relatively strongly while in motion or when the subject performs a steering operation on the vehicle, the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33 is superimposed with relatively large noise that makes it difficult to distinguish the R-wave peak, as shown in FIG. 5 as "noise from which the R-wave peak cannot be acquired."

[0041] In step 102, the first determination unit 34 performs first filtering by applying a 10 to 40 Hz BPF to the electrocardiogram waveform acquired in step 100. Note that Fig. 6A shows an example of the first waveform after the first filtering. In step 104, the first determination unit 34 calculates the sum S1 of the absolute values ​​of the first waveform after the first filtering.

[0042] In step 106, the first determination unit 34 determines whether the sum S1 of the absolute values ​​of the first waveform is smaller than the threshold value TH1_2 and greater than a threshold value TH1_1 that is smaller than the threshold value TH1_2. If the determination in step 106 is affirmative, the process proceeds to step 108, where the first determination unit 34 sets the flag Flag1 to "true" (a value indicating "true"), and then proceeds to step 112. If the determination in step 106 is negative, the process proceeds to step 110, where the first determination unit 34 sets the flag Flag1 to "false" (a value indicating "false"), and then proceeds to step 112.

[0043] In step 112, the second determination unit 36 ​​performs second filtering by applying a BPF of 30 to 150z to the electrocardiogram waveform acquired in step 100. Note that FIG. 6B shows an example of the second waveform after the second filtering. In step 114, the second determination unit 36 ​​calculates the sum S2 of the absolute values ​​of the second waveform after the second filtering.

[0044] In step 116, the second determination unit 36 ​​determines whether the sum S2 of the absolute values ​​of the second waveform is smaller than the threshold value TH2_2 and greater than a threshold value TH2_1 that is smaller than the threshold value TH2_2. If the determination in step 116 is affirmative, the process proceeds to step 118, where the second determination unit 36 ​​sets the flag Flag2 to "true" (a value indicating "true"), and then proceeds to step 122. If the determination in step 116 is negative, the process proceeds to step 120, where the second determination unit 36 ​​sets the flag Flag2 to "false" (a value indicating "false"), and then proceeds to step 122.

[0045] In step 122, the third determination unit 38 determines whether both the flag Flag1 and the flag Flag2 are set to "true," i.e., whether both the first determination in step 106 and the second determination in step 116 are affirmative. As shown in Fig. 6 by the notation "large integral value → large noise → low reliability," if the amplitude of at least one of the first waveform and the second waveform is large, it can be determined that the electrocardiogram waveform contains relatively large noise that makes it difficult to identify the peak of the R wave.

[0046] Therefore, if the determination in step 122 is negative, the third determination unit 38 determines that the reliability of the portion of the electrocardiogram waveform within the predetermined time period in the past, acquired in step 100, is "low," and the process proceeds to step 130. Then, in step 130, the output unit 40 outputs information indicating that the reliability of the portion of the electrocardiogram waveform within the predetermined time period in the past, acquired in step 100, is low, and the process returns to step 100. In this case, the in-vehicle UI unit 42 and the administrator terminal 46 are prevented from outputting a warning regarding drowsiness or fatigue level from the portion of the electrocardiogram waveform determined to have low reliability.

[0047] 6 , when the amplitudes of the first and second waveforms are small, it can be determined that the electrocardiogram waveform is one in which the peak of the R wave can be easily identified. Therefore, if the determination in step 122 is affirmative, the third determination unit 38 determines that the portion of the electrocardiogram waveform within the predetermined time period in the past, acquired in step 100, is a specific portion with a "high" reliability, and the process proceeds to step 124. Then, in step 124, the output unit 40 outputs information indicating that the portion of the electrocardiogram waveform within the predetermined time period in the past, acquired in step 100, has a high reliability.

[0048] In step 126, the output unit 40 determines the peak of an R wave from the specific portion of the electrocardiogram waveform determined to have high reliability by the third determination unit 38, and calculates the RRI from the determined peak of the R wave. In step 128, the output unit 40 determines the subject's physical condition (sleepiness and fatigue level) based on the fluctuation of the RRI calculated in step 126, and outputs the result of the determination of the subject's physical condition to the in-vehicle UI unit 42 or the administrator terminal 46. As a result, a warning is output from the in-vehicle UI unit 42 or the administrator terminal 46, for example, when the evaluation value of the subject's sleepiness calculated from the specific portion of the electrocardiogram waveform determined to have high reliability is equal to or greater than a first predetermined value, or when the evaluation value of the subject's fatigue level calculated from the specific portion is equal to or greater than a second predetermined value.

[0049] As described above, the steering ECU 30 according to this embodiment includes a first determination unit 34, a second determination unit 36, and a third determination unit 38. The first determination unit 34 performs a first filtering process by applying a band-pass filter of a first frequency band to the electrocardiogram waveform, and performs a first determination by determining, for each portion of the first waveform, whether the sum of absolute values ​​of the first waveform after the first filtering process is smaller than a threshold value TH1_2. The second determination unit 36 ​​performs a second filtering process by applying a band-pass filter of a second frequency band different from the first frequency band to the electrocardiogram waveform, and performs a second determination by determining, for each portion of the second waveform, whether the sum of absolute values ​​of the second waveform after the second filtering process is smaller than a threshold value TH2_2. The third determination unit 38 determines a portion of the electrocardiogram waveform for which at least one of the first and second determinations is affirmative as a specific portion with high reliability. This makes it possible to accurately determine the highly reliable portion of the electrocardiogram waveform (the portion with a small amount of superimposed noise) even when noise continues to be superimposed on the electrocardiogram waveform.

[0050] In this embodiment, the first frequency band is a frequency band that is close to the frequency band of R waves included in the electrocardiogram waveform, and the second frequency band is a frequency band that includes a frequency band higher than the frequency band of R waves, thereby making it possible to accurately determine the highly reliable portion of the electrocardiogram waveform.

[0051] In this embodiment, the first frequency band is 10 to 40 Hz, and the second frequency band is 30 to 150 Hz, which allows highly reliable portions of the electrocardiogram waveform to be determined with high accuracy.

[0052] In this embodiment, the third determination unit 38 determines a portion of the electrocardiogram waveform for which both the first determination and the second determination are positive as the specific portion, thereby making it possible to more accurately determine a highly reliable specific portion of the electrocardiogram waveform.

[0053] In this embodiment, the first determination unit 34 determines whether the sum of the absolute values ​​of the first waveform is smaller than a threshold value TH1_2 and larger than a threshold value TH1_1 that is smaller than the threshold value TH1_2, and the second determination unit 36 ​​determines whether the sum of the absolute values ​​of the second waveform is smaller than a second threshold value TH2_2 and larger than a threshold value TH2_1 that is smaller than the second threshold value TH2_2. This makes it possible to prevent the interrupted portion from being erroneously determined to be a highly reliable specific portion, for example, when the electrocardiogram waveform is temporarily interrupted due to the subject taking their hands off the steering wheel 12.

[0054] In this embodiment, the steering ECU 30 further includes an output unit 40 that calculates an RRI from a specific portion of the electrocardiogram waveform, and determines and outputs the physical condition of the subject at the specific portion from the calculated RRI, thereby enabling the physical condition of the subject to be determined with high accuracy.

[0055] Second Embodiment Next, a second embodiment of the present disclosure will be described. Note that the same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0056] 7, in the second embodiment, an electrocardiogram waveform transmission unit 50 and a portable terminal 52 are provided instead of the steering ECU 30. The electrocardiogram waveform transmission unit 50 is provided on the steering wheel 12 and includes an A / D converter that converts the analog electrocardiogram waveform signal input from the touch sensor 28 into digital electrocardiogram waveform data, and a wireless communication unit that transmits the electrocardiogram waveform data to the portable terminal 52 by wireless communication.

[0057] The mobile terminal 52 is a smartphone or tablet terminal carried by the subject, and although not shown, includes a CPU, memory such as ROM and RAM, a non-volatile storage unit (storage) such as an HDD or SSD, a wireless communication unit, a display, a touch panel, and a speaker. In the second embodiment, the mobile terminal 52 is an example of an electrocardiogram waveform processing device according to the present disclosure.

[0058] An electrocardiographic waveform processing program is stored (installed) as an application program in the storage unit of the mobile terminal 52. The electrocardiographic waveform processing program is read from the storage unit and loaded into memory, and the loaded electrocardiographic waveform processing program is executed by a CPU in the mobile terminal 52, whereby the mobile terminal 52 functions as an electrocardiographic waveform receiving unit 54, a first determination unit 34, a second determination unit 36, a third determination unit 38, and an output unit 40 shown in Fig. 8 and performs electrocardiographic waveform processing. Note that the terminal UI unit 56 shown in Fig. 8 is composed of a display and speaker of the mobile terminal 52, and the communication unit 58 is composed of a wireless communication unit of the mobile terminal 52.

[0059] The electrocardiographic waveform receiving unit 54 receives the electrocardiographic waveform data transmitted from the electrocardiographic waveform transmitting unit 50. The first determining unit 34, the second determining unit 36, the third determining unit 38, and the output unit 40 are configured similarly to those in the first embodiment. The electrocardiographic signal processing executed by the mobile terminal 52 according to the second embodiment is also the same as the electrocardiographic signal processing executed by the steering ECU 30 according to the first embodiment ( FIG. 4 ), and therefore a description thereof will be omitted. In the second embodiment, for example, when the subject's drowsiness assessment value calculated from a specific portion of the electrocardiographic waveform determined to have high reliability exceeds a first predetermined value, or when the subject's fatigue assessment value calculated from the specific portion exceeds a second predetermined value, a warning is output from the terminal UI unit 56 or the administrator terminal 46. Thus, the electrocardiographic waveform processing program according to the present disclosure may be an application program installed in the storage unit of the mobile terminal 52.

[0060] In the above embodiment, the first determination unit 34 performs the processes of steps 102 to 110, and then the second determination unit 36 ​​performs the processes of steps 112 to 120. However, the present disclosure is not limited to the first determination unit 34 and the second determination unit 36 ​​performing the processes in the above order, and the first determination unit 34 may perform the above process after the second determination unit 36 ​​has performed the above process.

[0061] In the above embodiment, the third determination unit 38 determines, as a highly reliable specific portion, a portion of the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33 for which both the first determination by the first determination unit 34 and the second determination by the second determination unit 36 ​​are positive. However, the present disclosure is not limited to this, and the third determination unit 38 may determine, as a highly reliable specific portion, a portion of the electrocardiogram waveform for which at least one of the first determination and the second determination is positive.

[0062] In the above embodiment, the output unit 40 calculates an RRI from a specific portion of the electrocardiogram waveform acquired by the electrocardiogram waveform acquisition unit 33 that has a high reliability determined by the third determination unit 38, and determines and outputs the physical condition of the subject at the specific portion from the calculated RRI. However, the present disclosure is not limited to this. The output unit 40 may calculate an RRI from the electrocardiogram waveform, determine the subject's physical condition, more specifically, drowsiness and fatigue level, for each portion of the electrocardiogram waveform from the calculated RRI, and add the determination result of the reliability of each portion of the electrocardiogram waveform by the third determination unit 38 to data representing the determined physical condition of the subject, and output the data to at least one of the in-vehicle UI unit 42, the terminal UI unit 56, and the administrator terminal 46. In this case, at least one of the in-vehicle UI unit 42, the terminal UI unit 56, and the administrator terminal 46 can be configured to output a warning or the like when the subject's drowsiness evaluation value becomes equal to or greater than a first predetermined value, or when the subject's fatigue evaluation value becomes equal to or greater than a second predetermined value, and the reliability assessment result for each part of the electrocardiogram waveform indicates high reliability.

[0063] Furthermore, although the above describes a state in which the electrocardiogram waveform processing program according to the present disclosure is pre-stored (installed) in the ROM or memory unit of the steering ECU 30, or in the memory unit of the mobile terminal 52, the electrocardiogram waveform processing program according to the present disclosure can also be provided in a form in which it is recorded on a non-temporary recording medium such as an HDD, SSD, or DVD.

[0064] The disclosure of Japanese Patent Application No. 2024-048057, filed on March 25, 2024, is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An electrocardiogram waveform processing device comprising: a first determination unit that performs a first filtering process by applying a band-pass filter of a first frequency band to an electrocardiogram waveform, and performs a first determination that determines, for each portion of the first waveform, whether a sum of absolute values ​​of the first waveform that has undergone the first filtering process is smaller than a first threshold value; a second determination unit that performs a second filtering process by applying a band-pass filter of a second frequency band different from the first frequency band to the electrocardiogram waveform, and performs a second determination that determines, for each portion of the second waveform, whether a sum of absolute values ​​of the second waveform that has undergone the second filtering process is smaller than a second threshold value; and a third determination unit that determines, in the electrocardiogram waveform, a portion for which at least one of the first determination and the second determination is affirmative, as a specific portion with high reliability.

2. An electrocardiogram waveform processing device as described in claim 1, wherein the first frequency band is a frequency band that is close to the frequency band of R waves contained in the electrocardiogram waveform, and the second frequency band is a frequency band that includes a frequency band higher than the frequency band of the R waves.

3. An electrocardiogram waveform processing device according to claim 1, wherein the first frequency band is 10 to 40 Hz, and the second frequency band is 30 to 150 Hz.

4. An electrocardiogram waveform processing device according to claim 1, wherein the third determination unit determines a portion of the electrocardiogram waveform for which both the first determination and the second determination are affirmative as the specific portion.

5. An electrocardiogram waveform processing device as described in claim 1, wherein the first judgment unit judges whether the sum of the absolute values ​​of the first waveform is smaller than the first threshold and greater than a third threshold that is smaller than the first threshold, and the second judgment unit judges whether the sum of the absolute values ​​of the second waveform is smaller than the second threshold and greater than a fourth threshold that is smaller than the second threshold.

6. An electrocardiogram waveform processing device as described in claim 1, further comprising an output unit that calculates an RRI from the specific portion of the electrocardiogram waveform and determines and outputs the subject's physical condition at the specific portion from the calculated RRI, or calculates an RRI from the electrocardiogram waveform and determines the subject's physical condition for each portion from the calculated RRI, and adds the reliability determination result for each portion made by the third determination unit to the determined physical condition of the subject and outputs it.

7. An electrocardiogram waveform processing method in which a computer executes processes including: performing a first filtering process to apply a band-pass filter of a first frequency band to an electrocardiogram waveform; performing a first determination to determine, for each portion of the first waveform, whether the sum of absolute values ​​of the first waveform that has passed through the first filtering process is smaller than a first threshold value; performing a second filtering process to apply a band-pass filter of a second frequency band different from the first frequency band to the electrocardiogram waveform; performing a second determination to determine, for each portion of the second waveform, whether the sum of absolute values ​​of the second waveform that has passed through the second filtering process is smaller than a second threshold value; and determining, in the electrocardiogram waveform, portions for which at least one of the first determination and the second determination is affirmative, as specific portions with high reliability.

8. An electrocardiogram waveform processing program for causing a computer to execute a process including: performing a first filtering process to apply a band-pass filter of a first frequency band to an electrocardiogram waveform; performing a first determination to determine for each portion of the first waveform whether the sum of absolute values ​​of the first waveform that has passed through the first filtering process is smaller than a first threshold value; performing a second filtering process to apply a band-pass filter of a second frequency band different from the first frequency band to the electrocardiogram waveform; performing a second determination to determine for each portion of the second waveform whether the sum of absolute values ​​of the second waveform that has passed through the second filtering process is smaller than a second threshold value; and determining that a portion of the electrocardiogram waveform for which at least one of the first determination and the second determination is affirmative is a specific portion with high reliability.

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