A system for detecting the biological information of vehicle occupants

Abstract

To provide a system capable of more accurately estimating the blood pressure even of a passenger with small hands. [Solution] A system for detecting biometric information of an occupant of a mobile body includes an electrocardiogram sensor mounted on the steering wheel of the mobile body and detecting the occupant's electrocardiogram signal, a pulse wave sensor mounted on the seat belt of the mobile body's seat and detecting the occupant's pulse wave signal, a PTT estimation unit that estimates the occupant's pulse wave propagation time using the electrocardiogram signal and the pulse wave signal, and a blood pressure estimation unit that estimates at least one of the occupant's blood pressure and blood pressure fluctuations using the estimated pulse wave propagation time.

Description

[Technical Field]

[0001] The present disclosure relates to a system for detecting biometric information of an occupant of a vehicle. [Background technology]

[0002] Various devices have been proposed that use sensors placed inside the vehicle cabin to detect the driver's biological information. For example, Patent Document 1 discloses a technology that uses electrodes and an optical sensor placed on the steering wheel to acquire the driver's electrocardiogram signal and pulse wave signal, and uses these to estimate the driver's blood pressure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-279185 Summary of the Invention [Problem to be solved by the invention]

[0004] In the technology of Patent Document 1, both the electrodes and the optical sensor are located on the steering wheel, so the driver needs to touch both the electrodes and the optical sensor at the same time. However, for drivers with relatively small hands, it may be difficult to touch both the electrodes and the optical sensor at the same time, which may result in an inaccurate blood pressure estimation. [Means for solving the problem]

[0005] The present disclosure can be realized in the following forms.

[0006] (1) According to one aspect of the present disclosure, there is provided a system for detecting biological information of an occupant of a vehicle, the system including: an electrocardiogram sensor provided on a steering wheel of the vehicle and detecting an electrocardiogram signal of the occupant; a pulse wave sensor provided on a seat belt of a seat of the vehicle and detecting a pulse wave signal of the occupant; a PTT estimation unit that estimates a pulse wave transit time of the occupant using the electrocardiogram signal and the pulse wave signal; and a blood pressure estimation unit that estimates at least one of blood pressure and blood pressure fluctuations of the occupant using the estimated pulse wave transit time. According to this form of system, the system is equipped with an electrocardiogram sensor attached to the steering wheel to detect the occupant's electrocardiogram signal, and a pulse wave sensor attached to the seat belt to detect the occupant's pulse wave signal, and the PTT estimation unit estimates the pulse wave propagation time using the electrocardiogram signal and the pulse wave signal, and the blood pressure estimation unit estimates at least one of blood pressure and blood pressure fluctuations using the estimated pulse wave propagation time.Therefore, compared to a configuration in which both the electrocardiogram sensor and the pulse wave sensor are attached to the steering wheel, at least one of blood pressure and blood pressure fluctuations can be estimated even for occupants with relatively small hands. (2) In the system of the above form, the seat belt may have a shoulder belt portion and a lap belt portion, and the pulse wave sensor may be provided in the lap belt portion of the shoulder belt portion and the lap belt portion. In this system, the pulse wave sensor is provided on the lap belt, which is the shoulder belt and lap belt, and therefore the accuracy of the detected pulse wave signal can be improved compared to a system in which the pulse wave sensor is provided on the shoulder belt, because the lap belt is more likely to fit closely to the occupant's body than the shoulder belt and is less likely to twist. (3) The system of the above form may further include a height acquisition unit that acquires height information of the occupant, a distance estimation unit that uses the height information to estimate a first distance from the occupant's heart to the electrocardiogram sensor and a second distance from the heart to the pulse wave sensor, and a correction unit that corrects the estimated pulse wave propagation time using the first distance and the second distance, and the blood pressure estimation unit may estimate at least one of the occupant's blood pressure and blood pressure fluctuations using the corrected pulse wave propagation time. According to this form of system, a correction unit is provided that corrects the estimated pulse wave propagation time using a first distance from the occupant's heart to the electrocardiogram sensor and a second distance from the heart to the pulse wave sensor, and the blood pressure estimation unit estimates at least one of blood pressure and blood pressure fluctuations using the corrected pulse wave propagation time.Therefore, at least one of blood pressure and blood pressure fluctuations can be estimated more accurately than in a configuration in which the blood pressure estimation unit uses an uncorrected pulse wave propagation time. (4) The system of the above form may further include a height estimation unit that estimates the height of the occupant using an image of the occupant acquired by an imaging device provided on the moving body and position information of the seat acquired by a position sensor provided on the seat, and the height acquisition unit may acquire the estimated height as the height information. According to the system of this aspect, the height acquisition unit acquires the height estimated by the height estimation unit as height information, which eliminates the need to input height information into the system in advance. (5) The system of the above aspect may further include a height memory unit that stores the height information of the occupant, and the height acquisition unit may acquire the height information stored in the height memory unit. According to this type of system, the height acquisition unit acquires height information stored in the height storage unit, so that more accurate height information can be acquired. (6) In the system of the above form, the blood pressure estimation unit may estimate the blood pressure of the occupant, and the system may further include an alarm unit that alerts the occupant when the estimated blood pressure falls outside a predetermined first range. According to this embodiment of the system, the notification unit is provided to notify the occupant when their blood pressure falls outside the first range, allowing the occupant to recognize that their blood pressure has fallen outside the first range. By setting the first range to the lower limit and upper limit of blood pressure within which the occupant is likely to be healthy, the occupant who has been notified can recognize that their blood pressure has fallen outside the blood pressure range within which the occupant is likely to be healthy. (7) In the system of the above form, the system may further include a vehicle stopping unit that transitions the moving body to a stopped state when the estimated blood pressure exceeds a predetermined second range that is wider than the first range. According to this type of system, the system is equipped with a vehicle stopping unit that transitions the moving body to a stopped state when the blood pressure exceeds the second range. Therefore, by setting the second range between the upper and lower blood pressure limits at which the occupant is likely to be able to continue driving, if the occupant's blood pressure falls outside the blood pressure range at which the occupant is likely to be able to continue driving, the vehicle can be transitioned to a stopped state, thereby preventing the occurrence of an accident. (8) The system of the above form may further include a blood pressure memory unit that stores the estimated blood pressure, and a range determination unit that determines the first range and the second range using the stored blood pressure. According to this form of system, a range determination unit is provided that determines the first and second ranges using stored blood pressures, so that more appropriate first and second ranges can be determined compared to configurations in which fixed first and second ranges are used.

[0007] The present disclosure may be realized in various forms, such as a vehicle equipped with a system, a method for estimating at least one of blood pressure and blood pressure, and a program for executing the method. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram illustrating a schematic configuration of a system for detecting biological information of a vehicle occupant according to an embodiment of the present disclosure. [Figure 2] 1 is a diagram illustrating a schematic configuration of a system for detecting biological information of a vehicle occupant according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is a block diagram showing the configuration of a control device. [Figure 4] 10 is a flowchart showing the steps of a blood pressure estimation process. [Figure 5] FIG. 10 is a block diagram showing the configuration of a control device in a system according to a second embodiment. [Figure 6] FIG. 10 is a block diagram showing the configuration of a control device in a system according to a third embodiment. [Figure 7] 10 is a flowchart showing the steps of a blood pressure estimation process executed by a system according to a third embodiment. [Figure 8] FIG. 10 is a block diagram showing the configuration of a control device in a system according to a fourth embodiment. [Figure 9] 10 is a flowchart showing the steps of a blood pressure estimation process executed by a system according to a fourth embodiment. [Figure 10] FIG. 11 is a block diagram showing the configuration of a control device in a system according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] A. First embodiment: <Overall structure> 1 and 2 are diagrams showing a schematic configuration of a system 1 (hereinafter also referred to as system 1) for detecting biological information of a vehicle occupant P according to one embodiment of the present disclosure. FIG. 1 shows the system 1 as viewed from the left of the vehicle, and FIG. 2 shows the system 1 as viewed from the front of the vehicle. In FIG. 2, the steering wheel SR, the imaging device 40, and the control device 100 shown in FIG. 1 are omitted. The system 1 is used to detect information relating to blood pressure, among the biological information of the vehicle occupant P. As shown in FIGS. 1 and 2, the system 1 includes an electrocardiogram sensor 10, a pulse wave sensor 20, and the control device 100.

[0010] In this disclosure, the direction along the vehicle's traveling direction is referred to as the "front-rear direction." The vertical direction as seen by the driver in the vehicle is referred to as the "up-down direction." The "up-down direction" may also be referred to as the "height direction." The direction along the left-right direction (width direction) of the vehicle is referred to as the "left-right direction." The "front-rear direction," "up-down direction," and "left-right direction" are directions that intersect with each other.

[0011] <Configuration of electrocardiogram sensor 10> The electrocardiogram sensor 10 shown in FIG. 1 detects an electrocardiogram signal of an occupant P. In this embodiment, the electrocardiogram sensor 10 is a pair of electrodes provided on the steering wheel SR. The electrocardiogram sensor 10 is provided on a rim portion of the steering wheel SR that is gripped by the occupant P. The electrocardiogram signal is detected when the occupant P grips both of the pair of electrodes. The electrocardiogram signal is transmitted to a control device 100, which will be described later.

[0012] <Configuration of pulse wave sensor 20> The pulse wave sensor 20 shown in FIG. 2 detects a pulse wave signal of the occupant P. The pulse wave sensor 20 is provided on a seat belt 45. Specifically, the pulse wave sensor 20 is provided on a surface of a webbing WB of the seat belt 45. The webbing WB is a belt-shaped member made of polyamide or the like. The seat belt 45 in this embodiment is a so-called three-point seat belt. The seat belt 45 includes a shoulder belt portion 26 and a lap belt portion 27. When the seat belt 45 is worn by the occupant P, the shoulder belt portion 26 extends from an anchor 28 to a buckle 29. The anchor 28 is a member for guiding the seat belt 45, which is unwound from a retractor 30, toward the occupant P. The retractor 30 is a device for retracting the seat belt 45. The buckle 29 is provided on the side of the seat 43 and is a member for fastening a tongue (not shown) of the seat belt 45. When worn, the shoulder belt portion 26 covers from one shoulder of the occupant P to the abdomen on the other side. When worn, the lap belt portion 27 extends from the buckle 29 to the underplate 31. The underplate 31 is provided on the right side of the seat 43 and is a member for fastening the seat belt 45. When worn, the lap belt portion 27 covers the abdomen of the occupant P so as to cross the left and right direction.

[0013] In this embodiment, the pulse wave sensor 20 is provided in the lap belt 27 out of the shoulder belt 26 and the lap belt 27. The pulse wave sensor 20 is provided in the lap belt 27 so as to be located near the center of the abdomen of the occupant P in the left-right direction when the occupant P is wearing the lap belt 27.

[0014] In this embodiment, the pulse wave sensor 20 is configured as a pressure sensor. The pulse wave sensor 20 detects minute body movements associated with changes in the occupant P's pulse rate as changes in pressure applied to the pulse wave sensor 20. The sensor element of the pulse wave sensor 20 includes, for example, carbon nanotubes. The sensor element may be manufactured by printing carbon nanotubes onto the surface of the seat belt 45, or by sewing a substrate such as a nonwoven fabric impregnated with a carbon nanotube solution to the seat belt 45. Carbon nanotubes have higher sensitivity than conventional sensor elements made of metal materials and can therefore detect even smaller pressure changes. The detected pressure change is transmitted to the control device 100, described below, as a pulse wave signal of the occupant P.

[0015] <Configuration of the control device 100> 3 is a block diagram showing the configuration of the control device 100. The control device 100 is configured as a computer including a CPU 110 and a memory 120. The CPU 110 reads and executes a control program pre-stored in the memory 120, thereby causing a PTT estimation unit 101, a height estimation unit 102, a height acquisition unit 103, a distance estimation unit 104, a correction unit 105, and a blood pressure estimation unit 106 to function.

[0016] The PTT estimation unit 101 estimates the pulse transmission time (PTT) of the occupant P. The PTT is estimated using the electrocardiogram signal detected by the electrocardiogram sensor 10 and the pulse wave signal detected by the pulse wave sensor 20. Specifically, the PTT is estimated by calculating the time difference between the peak of the R wave in the electrocardiogram signal and the peak in the pulse wave signal.

[0017] The height estimation unit 102 estimates the height of the occupant P. Specifically, the height estimation unit 102 estimates the height of the occupant P using imaging data output from the imaging device 40 shown in FIG. 1 and position information of the seat 43 output from a position sensor 46 provided in the seat 43. The imaging device 40 is provided in front of the seat 43, captures an image of the occupant P seated in the seat 43, and outputs the imaging data to the height estimation unit 102. The position sensor 46 is provided on a seat rail below the seat 43, and outputs position information of the seat 43 in the fore-and-aft direction to the height estimation unit 102. The height estimation unit 102 acquires a reference height. The reference height is a value estimated as the height of the occupant P when the top edge position of the headrest 47 of the seat 43 coincides with the top edge position of the occupant P's head. The reference height is pre-stored in the memory 120 in association with the seat position information. Next, the height estimation unit 102 estimates the height of the occupant P using the positional relationship between the top of the occupant P's head and the top of the headrest 47 in the image capture, the seat position information, and the reference height. The relationship between the unit distance during image capture and the actual length can be obtained from the position information of the seat 43. The height estimation unit 102 uses this relationship to convert the difference between the top of the head and the top of the headrest 47 in the image capture into the actual length. The height estimation unit 102 estimates the height of the occupant P by adding or subtracting this length from the reference height.

[0018] 3 acquires height information of the occupant P. In this embodiment, the height acquisition unit 103 acquires the height estimated by the height estimation unit 102 as the height information.

[0019] The distance estimation unit 104 estimates a first distance L1 and a second distance L2 using height information. As shown in FIG. 1, the first distance L1 is the distance from the electrocardiogram sensor 10 to the heart H when the occupant P is gripping the steering wheel SR. More specifically, the first distance L1 is the distance that includes a path inside the body of the occupant P from the electrocardiogram sensor 10 to the heart H. As shown in FIG. 2, the second distance L2 is the distance from the pulse wave sensor 20 to the heart H when the occupant P is wearing a seat belt 45. More specifically, the second distance L2 is the distance that includes a path inside the body of the occupant P from the pulse wave sensor 20 to the heart H. The first distance L1 and the second distance L2 are pre-stored in the memory 120 in association with the height information.

[0020] The correction unit 105 shown in FIG. 3 corrects the PTT estimated by the PTT estimation unit 101 using the first distance L1 and the second distance L2. The electrocardiogram sensor 10 detects the electrocardiogram signal at the position of the occupant P's hands, and the pulse wave sensor 20 detects the pulse wave signal at the occupant P's abdomen. Therefore, the electrocardiogram signal and the pulse wave signal are acquired at different positions. As a result, the PTT estimated by the PTT estimation unit 101 contains an error. The correction unit 105 corrects the PTT using the first distance L1 and the second distance L2, assuming that the electrocardiogram signal and the pulse wave signal are detected near the heart H, to reduce the error. Specifically, the correction unit 105 calculates a first propagation time, which is the time it takes for the electrocardiogram signal to propagate from the heart H to the electrocardiogram sensor 10, using the first distance L1 and the propagation speed of the electrocardiogram signal. Correction unit 105 also uses second distance L2 and the propagation velocity of the pulse wave signal to calculate a second propagation time, which is the time it takes for the pulse wave signal to propagate from heart H to pulse wave sensor 20. The propagation velocities of the electrocardiogram signal and the pulse wave signal are stored in advance in memory 120. Correction unit 105 calculates a correction time, which is the absolute value of the difference between the first propagation time and the second propagation time. Correction unit 105 corrects the PTT by subtracting the correction time from the PTT. The corrected PTT is stored in chronological order in memory 120.

[0021] The blood pressure estimation unit 106 estimates at least one of the blood pressure and blood pressure fluctuation of the occupant P using the PTT corrected by the correction unit 105. The blood pressure estimation unit 106 estimates the blood pressure of the occupant P using the correlation between the PTT and blood pressure stored in advance in the memory 120. The blood pressure estimation unit 106 also estimates the blood pressure fluctuation using the PTT of the occupant P stored in chronological order in the memory 120. "Blood pressure fluctuation" includes an increase in blood pressure and a decrease in blood pressure. For example, a decrease in the PTT in chronological order indicates an increase in blood pressure. Conversely, a decrease in the PTT in chronological order indicates a decrease in blood pressure. At least one of the blood pressure and blood pressure fluctuation estimated by the blood pressure estimation unit 106 may be stored in chronological order in the memory 120.

[0022] <Blood pressure estimation process> 4 is a flowchart showing the steps of the blood pressure estimation process executed by the system 1. The blood pressure estimation process is executed when the ignition switch of the vehicle is turned on and the occupant P fastens the seat belt 45 and grips the steering wheel SR with both hands.

[0023] The electrocardiogram sensor 10 detects the electrocardiogram signal of the occupant P (step S100). The pulse wave sensor 20 detects the pulse wave signal of the occupant P (step S110). The PTT estimation unit 101 estimates the PTT using the electrocardiogram signal and the pulse wave signal (step S120). The height estimation unit 102 estimates the height of the occupant P (step S130). The height acquisition unit 103 acquires the estimated height as height information (step S140). The distance estimation unit 104 estimates the first distance L1 and the second distance L2 using the height information (step S150). The correction unit 105 corrects the estimated PTT using the first distance L1 and the second distance L2 (step S160). The blood pressure estimation unit 106 estimates at least one of blood pressure and blood pressure fluctuations using the corrected PTT (step S170).

[0024] The above-described blood pressure estimation process is repeatedly executed until the ignition switch of the vehicle is turned off. Note that the processes of steps S100 and S110 may be executed in parallel.

[0025] According to the system 1 of the first embodiment described above, the pulse wave propagation time is estimated using the electrocardiogram sensor 10 provided on the steering wheel SR and the pulse wave sensor 20 provided on the seat belt 45, and the blood pressure is estimated using the estimated pulse wave propagation time. Therefore, compared to a configuration in which both the electrocardiogram sensor 10 and the pulse wave sensor 20 are provided on the steering wheel SR, it is possible to estimate the blood pressure of an occupant P with relatively small hands.

[0026] Furthermore, according to the system 1 of the first embodiment, the pulse wave sensor 20 is provided in the lap belt portion 27 of the shoulder belt portion 26 and the lap belt portion 27 of the seat belt 45, and therefore the accuracy of the detected pulse wave signal can be improved compared to a configuration in which the pulse wave sensor 20 is provided in the shoulder belt portion 26. This is because the lap belt portion 27 is more likely to fit closely to the body of the occupant P than the shoulder belt portion 26 and is less likely to twist.

[0027] Furthermore, according to the system 1 of the first embodiment, the height acquisition unit 103 acquires height information of the occupant P, the distance estimation unit 104 estimates the first distance L1 and the second distance L2 using the height information, the correction unit 105 corrects the PTT using the first distance L1 and the second distance L2, and the blood pressure estimation unit 106 estimates at least one of blood pressure and blood pressure fluctuations using the corrected PTT.Therefore, compared to a configuration in which the blood pressure estimation unit 106 estimates at least one of blood pressure and blood pressure fluctuations using an uncorrected PTT, it is possible to correct errors in the PTT caused by the electrocardiogram sensor 10 and the pulse wave sensor 20 being located at different positions from each other, and it is possible to more accurately estimate at least one of blood pressure and blood pressure fluctuations.

[0028] Furthermore, according to the system 1 of the first embodiment, the height estimation unit 102 estimates the height of the occupant P using an image of the occupant P acquired by the imaging device 40 and position information of the seat 43 acquired by the position sensor 46. Therefore, compared to a configuration that does not have the height estimation unit 102, the PTT can be corrected without inputting height information into the system 1 in advance.

[0029] Furthermore, according to the system 1 of the first embodiment, the pulse wave sensor 20 is provided on the lap belt 27 so as to be located near the center of the abdomen of the occupant P in the left-right direction when the pulse wave sensor 20 is worn, which reduces noise in the detected pulse wave signal compared to when the pulse wave sensor 20 is located off-center of the lap belt 27. This is because the portion of the lap belt 27 located near the center of the abdomen in the left-right direction is more likely to fit tightly against the body of the occupant P than other portions of the lap belt 27.

[0030] Furthermore, according to the system 1 of the first embodiment, the sensor element of the pulse wave sensor 20 contains carbon nanotubes, which increases the sensitivity of the sensor compared to a configuration in which the sensor element does not contain carbon nanotubes. This allows the pulse wave sensor 20 to detect pulse waves with high sensitivity even when worn over clothing.

[0031] Furthermore, in the system 1 of the first embodiment, the pulse wave sensor 20 is configured as a pressure sensor, and therefore is less affected by ambient brightness than an optical sensor. Therefore, the pulse wave sensor 20 can detect a pulse wave signal regardless of the time of day or the ambient brightness.

[0032] B. Second embodiment: 5 is a block diagram showing the configuration of a control device 100b in a system 1b of the second embodiment. The control device 100b of the second embodiment differs from the control device 100 of the first embodiment in that it does not have a height estimation unit 102 and further includes a height storage unit 121. Configurations not described below are the same as those in the system 1 of the first embodiment.

[0033] The height storage unit 121 stores height information of the occupant P. The height information may be input in advance through a user interface of the vehicle or may be input in advance by an external device such as a smartphone. The height storage unit 121 may also store height information of multiple occupants P for each occupant P.

[0034] The height acquisition unit 103 of the second embodiment acquires the height stored in the height storage unit 121 as height information instead of the height estimated by the height estimation unit 102. The acquired height information is used by the distance estimation unit 104 to estimate the first distance L1 and the second distance L2, as in the first embodiment.

[0035] In the blood pressure estimation process of the second embodiment, step S130 for estimating height shown in Fig. 4 is omitted. In addition, in step S140, the height acquisition unit 103 acquires the height stored in the height storage unit 121 as height information instead of the estimated height.

[0036] According to the system 1b of the second embodiment described above, the height memory unit 121 stores the height information of the occupant P, and the height acquisition unit 103 acquires the height information stored in the height memory unit 121. This allows the correction unit 105 to correct the PTT using more accurate height information. This allows for higher accuracy of the estimated blood pressure and blood pressure fluctuations.

[0037] C. Third embodiment: 6 is a block diagram showing the configuration of a control device 100c in a system 1c of the third embodiment. The control device 100c in the third embodiment differs from the control device 100 in the first embodiment in that it further includes a notification unit 107. Configurations not described below are the same as those in the system 1 of the first embodiment.

[0038] The notification unit 107 notifies the occupant P when the blood pressure estimated by the blood pressure estimation unit 106 falls outside a predetermined first range. The first range is set as a blood pressure range within which the physical condition of the occupant P is likely to be healthy. In other words, the physical condition of the occupant P whose blood pressure falls outside the first range is likely to be different from when healthy. The first range is set by, for example, determining it through an experiment. The first range is stored in advance in the memory 120. The notification is made by sound, video, vibration, or a combination thereof. Therefore, the notification unit 107 is configured with a speaker, a monitor, a vibration device, etc.

[0039] 7 is a flowchart showing the steps of the blood pressure estimation process executed by the system 1c of the third embodiment. The blood pressure estimation process of the third embodiment differs from the blood pressure estimation process of the first embodiment in that step S171 is executed instead of step S170, and in that steps S310 and S320 are further included. The other steps are the same as the blood pressure estimation process of the first embodiment, and therefore their description will be omitted.

[0040] 7, the blood pressure estimation unit 106 estimates blood pressure (step S171). The blood pressure estimation unit 106 may further estimate blood pressure fluctuations. That is, this differs from step S170 in the first embodiment in that only blood pressure fluctuations are not estimated.

[0041] The notification unit 107 determines whether the blood pressure is outside the first range (step S310). If the blood pressure is outside the first range (step S310: Yes), the notification unit 107 notifies the occupant P (step S320). If the blood pressure is not outside the first range (step S310: No), the blood pressure estimation process ends.

[0042] According to the system 1c of the third embodiment described above, the notification unit 107 notifies the occupant P when the estimated blood pressure falls outside the predetermined first range, so that the occupant P can know that the blood pressure has fallen outside the first range. By receiving such notification, the occupant P can recognize that his or her physical condition is likely to be different from when he or she is healthy.

[0043] D. Fourth embodiment: 8 is a block diagram showing the configuration of a control device 100d in a system 1d of the fourth embodiment. The control device 100d in the fourth embodiment differs from the control device 100c of the third embodiment in that it further includes a vehicle stopping unit 108. Configurations not described below are the same as those in the system 1c of the third embodiment.

[0044] The vehicle stopping unit 108 functions by the CPU 110 reading and executing a control program pre-stored in the memory 120. The vehicle stopping unit 108 transitions the vehicle to a stopped state when the blood pressure estimated by the blood pressure estimation unit 106 falls outside a second range that is wider than the first range. The second range is set as a blood pressure range in which the occupant P is likely to be able to continue driving. In other words, the physical condition of the occupant P whose blood pressure falls outside the second range is likely to prevent the occupant P from continuing driving. The second range is set by, for example, determining it through experiments. The second range is pre-stored in the memory 120. When the estimated blood pressure falls outside the second range, the vehicle stopping unit 108, for example, instructs an ECU installed in the vehicle to perform autonomous driving and stops the vehicle at a nearby roadside, parking lot, or the like.

[0045] 9 is a flowchart showing the steps of the blood pressure estimation process executed by the system 1d of the fourth embodiment. The blood pressure estimation process of the fourth embodiment differs from the blood pressure estimation process of the third embodiment in that it further includes steps S410 and S420. The other steps are the same as the blood pressure estimation process of the third embodiment, and therefore their description will be omitted.

[0046] 9, following the processing of step S310 or step S320, the vehicle stopping unit 108 determines whether the blood pressure is outside the second range (step S410). If the blood pressure is outside the second range (step S410: Yes), the vehicle stopping unit 108 transitions the vehicle to a stopped state (step S420). If the blood pressure is not outside the second range (step S410: No), the blood pressure estimation process ends.

[0047] The processes of steps S410 and S420 described above may be performed without the processes of steps S310 and S320.

[0048] According to the fourth embodiment system 1d described above, the vehicle stopping unit 108 transitions the vehicle to a stopped state when the estimated blood pressure falls outside the predetermined second range, thereby suppressing the occurrence of an accident caused by an occupant P who is likely not in a condition to continue driving.

[0049] E. Fifth embodiment: 10 is a block diagram showing the configuration of a control device 100e in a system 1e according to the fifth embodiment. The control device 100e according to the fifth embodiment differs from the control device 100d according to the fourth embodiment in that it includes a blood pressure storage unit 122 and a range determination unit 109. The configurations not described below are the same as those in the system 1d according to the fourth embodiment, and therefore will not be described again.

[0050] The blood pressure storage unit 122 stores the blood pressure estimated by the blood pressure estimation unit 106. The blood pressure is stored, for example, linked to the occupant P. The blood pressure is also stored, for example, in chronological order. The blood pressure is also stored, for example, linked to time.

[0051] The range determination unit 109 functions by the CPU 110 reading and executing a control program pre-stored in the memory 120. The range determination unit 109 determines the first and second ranges using blood pressures stored in the blood pressure storage unit 122. The range determination unit 109 determines the first and second ranges using, for example, the average or median of the stored blood pressures. The range determination unit 109 calculates the average and median of blood pressures using blood pressures stored in a time series, for example, for one to two weeks. The average and median of blood pressures may be pre-stored in the blood pressure storage unit 122. The first and second ranges range, for example, from a value obtained by adding a predetermined margin to the median of blood pressure to a value obtained by subtracting the predetermined margin from the median of blood pressure. The predetermined margin for determining the first range is, for example, 15 mmHG. The predetermined margin for determining the second range is, for example, 30 mmHG. The first and second ranges may be determined using, for example, the average value (μ) and standard deviation (σ) of blood pressure stored in memory. Specifically, the first range is set as μ±2σ. The second range is set as μ±3σ. The standard deviation of blood pressure may be calculated by the range determination unit 109 or may be stored in advance in the blood pressure storage unit 122. The first and second ranges are not limited to the above ranges and may be set as any ranges.

[0052] According to the system 1e of the fifth embodiment described above, the blood pressure memory unit 122 stores the estimated blood pressure, and the range determination unit 109 determines the first range and the second range using the stored blood pressure. Therefore, the first range and the second range can be determined to be more appropriate values ​​compared to a configuration in which the first range and the second range are determined without using the stored blood pressure.

[0053] F. Other Embodiments: (F1) The system 1b of the second embodiment may be configured in combination with each of the system 1c of the third embodiment, the system 1d of the fourth embodiment, and the system 1e of the fifth embodiment.

[0054] (F2) In each of the above embodiments, at least a part of the configuration of the control devices 100, 100b, 100c, 100d, and 100e may not be mounted on the vehicle. That is, at least a part of the configuration of the control devices 100, 100b, 100c, 100d, and 100e may be configured by a server or the like external to the vehicle, and the server or the like may communicate with a communication device mounted on the vehicle to realize the systems 1, 1b, 1c, 1d, and 1e.

[0055] (F3) In each of the above embodiments, the pulse wave sensor 20 may be any sensor such as a photoelectric sensor attached to the seat belt 45 or a millimeter wave radar sensor.

[0056] (F4) In each of the above embodiments, at least one of the electrocardiogram signal and the pulse wave signal may be subjected to noise removal processing. Noise may be caused, for example, by vibrations caused by the vehicle traveling. The PTT estimation unit 101 may estimate the PTT using the electrocardiogram signal and the pulse wave signal that have been subjected to noise removal processing. This configuration allows for more accurate estimation of the PTT.

[0057] (F5) In the first embodiment, the blood pressure estimation unit 106 estimates at least one of the blood pressure and the blood pressure fluctuation using the PTT corrected by the correction unit 105. However, the present disclosure is not limited to this. The blood pressure estimation unit 106 may estimate at least one of the blood pressure and the blood pressure fluctuation using the uncorrected PTT.

[0058] (F6) In the first embodiment, the pulse wave sensor 20 is provided in the lap belt portion 27 of the seat belt 45, but the present disclosure is not limited to this. The pulse wave sensor 20 may be provided in the shoulder belt portion 26 of the seat belt 45. Furthermore, the pulse wave sensor 20 may be provided in both the shoulder belt portion 26 and the lap belt portion 27 of the seat belt 45.

[0059] (F7) In the above embodiments, the first distance L1 and the second distance L2 are estimated using height information, but the present disclosure is not limited to this. The first distance L1 and the second distance L2 may be stored in advance in memory 120. For example, the first distance L1 and the second distance L2 are measured directly by the occupant P and input via the vehicle's user interface, and then stored. With this configuration, the PTT can be corrected more accurately using more accurate first distance L1 and second distance L2.

[0060] (F8) In the third embodiment, the notification unit 107 notifies the occupant P when the blood pressure exceeds the first range. However, the present disclosure is not limited to this. The notification unit 107 may also notify the occupant P when the blood pressure exceeds a predetermined first threshold. The notification unit 107 may also notify the occupant P when the blood pressure falls below a predetermined second threshold. The first threshold and the second threshold are boundary values ​​between a blood pressure value at which the physical condition of the occupant P is likely to differ from that of a healthy occupant and a blood pressure value at which the occupant P is likely to be healthy. The first threshold is greater than the second threshold. The physical condition of the occupant P whose blood pressure exceeds the first threshold is likely to differ from that of a healthy occupant. The physical condition of the occupant P whose blood pressure is below the second threshold is likely to differ from that of a healthy occupant. The first threshold and the second threshold are set, for example, by experimentally determining them. The first threshold and the second threshold are pre-stored in the memory 120. This configuration makes it possible to notify the occupant P when the blood pressure of the occupant P is likely to differ from that of a healthy occupant. The first and second thresholds may be determined using blood pressures stored in the blood pressure storage unit 122. The first threshold may be, for example, a value obtained by adding a predetermined margin to the median of the stored blood pressures. The first threshold may be, for example, a value obtained by adding 15 mmHG to the median of the stored blood pressures. For example, the first threshold may be a value obtained by subtracting a predetermined margin from the median of the stored blood pressures. The second threshold may be, for example, a value obtained by subtracting 15 mmHG from the median of the stored blood pressures. The first and second thresholds may also be set using the mean (μ) and standard deviation (σ) of blood pressures. For example, the first threshold is set as μ + 2σ, and the second threshold is set as μ - 2σ. The first and second thresholds are not limited to the above values ​​and may be set to any arbitrary values. The first and second thresholds may be determined by the range determination unit 109, which functions when the CPU 110 executes a program stored in the memory 120. The first threshold and the second threshold may be determined by a threshold determination unit (not shown) that functions when the CPU 110 executes a control program stored in the memory 120.

[0061] (F9) In the fourth embodiment, the vehicle stopping unit 108 transitions the vehicle to a stopped state when the blood pressure falls outside the second range. However, the present disclosure is not limited to this. The vehicle stopping unit 108 may transition the vehicle to a stopped state when the blood pressure exceeds a predetermined third threshold. The vehicle stopping unit 108 may also transition the vehicle to a stopped state when the blood pressure falls below a predetermined fourth threshold. The third threshold is greater than the fourth threshold. The third threshold and the fourth threshold are boundary values ​​between a blood pressure value at which the occupant P is likely to be unable to continue driving and a blood pressure value at which the occupant P is likely to be able to continue driving, respectively. An occupant P whose blood pressure exceeds the third threshold is likely to be unable to continue driving. An occupant P whose blood pressure is below the fourth threshold is likely to be unable to continue driving. The third threshold and the fourth threshold are set, for example, by experimentally determining them. The third threshold and the fourth threshold are pre-stored in the memory 120. With this configuration, when it is likely that the occupant P will be unable to continue driving, the vehicle is stopped, thereby preventing an accident from occurring. The third and fourth thresholds may be determined using blood pressures stored in the blood pressure storage unit 122. The third threshold is, for example, a value obtained by adding a predetermined margin to the median of the stored blood pressures. The third threshold is, for example, a value obtained by adding 30 mmHG to the median of the stored blood pressures. The fourth threshold is, for example, a value obtained by subtracting a predetermined margin from the median of the stored blood pressures. The fourth threshold is, for example, a value obtained by subtracting 30 mmHG from the median of the stored blood pressures. The third and fourth thresholds may also be set using the mean (μ) and standard deviation (σ) of blood pressure. For example, the third threshold is set as μ + 3σ, and the fourth threshold is set as μ - 3σ. The third and fourth thresholds are not limited to the above values ​​and may be set to any arbitrary values. The range determination unit 109 may determine the third and fourth thresholds. The third threshold and the fourth threshold may be determined by a threshold determination unit (not shown) that functions when the CPU 110 executes a control program stored in the memory 120.

[0062] (F10) In each of the above embodiments, the correction unit 105 may further correct the PTT using respiratory information of the occupant. The respiratory information is information related to the respiratory state of the occupant and includes whether the occupant is exhaling or inhaling. The respiratory information is acquired, for example, by a sensor attached to the seat belt 45. When the occupant is exhaling, the cardiac output may decrease, causing the PTT to be longer than normal. On the other hand, when the occupant is inhaling, the cardiac output may increase, causing the PTT to be shorter than normal. Here, the correction unit 105 corrects the PTT so that it is shorter when the occupant is exhaling, and corrects the PTT so that it is longer when the occupant is inhaling. This embodiment reduces PTT errors due to respiration, allowing the blood pressure estimation unit 106 to estimate at least one of blood pressure and blood pressure fluctuations using the more accurately corrected PTT.

[0063] (F11) In each of the above embodiments, the systems 1, 1b, 1c, 1d, and 1e may be installed on any moving object other than a vehicle. Such moving objects include, for example, ships, airplanes, spacecraft, and so-called flying cars. Furthermore, the moving object does not necessarily have to be a moving object, but may also be an object that realizes virtual movement, such as a simulator.

[0064] The present disclosure is not limited to the above-described embodiments and can be realized in various configurations without departing from the spirit thereof. For example, the technical features in the embodiments corresponding to the technical features in each aspect described in the Summary of the Invention section can be appropriately replaced or combined to solve some or all of the above-described problems or achieve some or all of the above-described effects. Furthermore, if a technical feature is not described as essential in this specification, it can be appropriately deleted. [Explanation of symbols]

[0065] 1, 1b, 1c, 1d, 1e...system, 10...electrocardiogram sensor, 20...pulse wave sensor, 26...shoulder belt section, 27...lap belt section, 28...anchor, 29...buckle, 30...retractor, 31...underplate, 40...imaging device, 43...seat, 45...seat belt, 46...position sensor, 47...headrest, 100, 100b, 100c, 100d, 10 0e...control device, 101...PTT estimation unit, 102...height estimation unit, 103...height acquisition unit, 104...distance estimation unit, 105...correction unit, 106...blood pressure estimation unit, 107...notification unit, 108...vehicle stopping unit, 109...range determination unit, 110...CPU, 120...memory, 121...height storage unit, 122...blood pressure storage unit, H...heart, L1...first distance, L2...second distance, P...occupant, SR...steering

Claims

1. A system for detecting biological information of a vehicle occupant, an electrocardiogram sensor provided on a steering wheel of the vehicle to detect an electrocardiogram signal of the occupant; a pulse wave sensor provided on a seat belt of a seat of the vehicle to detect a pulse wave signal of the occupant; a PTT estimation unit that estimates a pulse wave transit time of the occupant using the electrocardiogram signal and the pulse wave signal; a blood pressure estimation unit that estimates at least one of the occupant's blood pressure and blood pressure fluctuations using the estimated pulse wave transit time; A system comprising:

2. 10. The system of claim 1, The seat belt has a shoulder belt portion and a lap belt portion, the pulse wave sensor is provided in the lap belt portion out of the shoulder belt portion and the lap belt portion; system.

3. 3. The system of claim 2, a height acquisition unit that acquires height information of the occupant; a distance estimation unit that estimates a first distance from the heart of the occupant to the electrocardiogram sensor and a second distance from the heart to the pulse wave sensor using the height information; a correction unit that corrects the estimated pulse wave transit time using the first distance and the second distance; Further provided with the blood pressure estimation unit estimates at least one of the blood pressure and the blood pressure fluctuation of the occupant using the corrected pulse wave transit time. system.

4. 4. The system of claim 3, a height estimation unit that estimates a height of the occupant using an image of the occupant acquired by an imaging device provided in the moving body and position information of the seat acquired by a position sensor provided in the seat, The height acquisition unit acquires the estimated height as the height information. system.

5. 4. The system of claim 3, a height storage unit that stores the height information of the occupant, The height acquisition unit acquires the height information stored in the height storage unit. system.

6. 6. A system according to claim 4 or 5, the blood pressure estimation unit estimates the blood pressure of the occupant; The system comprises: The vehicle control system further includes a notification unit that notifies the occupant when the estimated blood pressure falls outside a predetermined first range. system.

7. 7. The system of claim 6, The system further includes a vehicle stopping unit that transitions the moving body to a stopped state when the estimated blood pressure falls outside a predetermined second range that is wider than the first range.

8. 8. The system of claim 7, a blood pressure storage unit that stores the estimated blood pressure; a range determination unit that determines the first range and the second range using the stored blood pressure; The system further comprises:

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