WO2023090045A1

WO2023090045A1 - Driver state assessment device

Info

Publication number: WO2023090045A1
Application number: PCT/JP2022/039161
Authority: WO
Inventors: 祐介伊東
Original assignee: 矢崎総業株式会社
Priority date: 2021-11-18
Filing date: 2022-10-20
Publication date: 2023-05-25
Also published as: JP7348254B2; JP2023074523A

Abstract

[Problem] To provide a driver state determination device that can divide changes in the autonomic nerve state of a driver during driving into a change caused by an intrinsic factor and a change caused by an extrinsic factor to thereby make determination. [Solution] A driver state determination device 1 comprises: a pulse sensor 3 that detects the heartbeat of the driver; an illuminance sensor 2 that detects an ambient illuminance value; and a computational processing unit 4 that determines the autonomic state of the driver on the basis of heartbeat variation obtained from the results of the detection by the heartbeat sensor 3 and a change in ambient brightness obtained from the result of the detection by the illuminance sensor 2. The computational processing unit 4 determines that the sympathetic nerve of the autonomic nerves has been activated by an extrinsic factor when the heartbeat variation of the driver increases, the ambient brightness changes from a bright condition to a dark condition and thereafter does not change from the dark condition, and the heartbeat variation of the driver starts to decrease. Meanwhile, the computational processing unit 4 determines that the parasympathetic of the autonomic nerves has been activated by an intrinsic factor when the ambient brightness does not change from the dark condition and the heartbeat variation of the driver does not start to decrease.

Description

Driver condition determination device

The present invention relates to a driver's state determination device.

Conventionally, for the purpose of assisting the safe driving of a driver of a car, etc., a method of analyzing the psychological state of the driver by having the driver wear a cerebral blood flow sensor, a heart rate sensor, a respiratory sensor, etc. (see, for example, Patent Document 1) ) and an apparatus for estimating a driver's condition using an electrodermal activity sensor (see, for example, Patent Document 2).

JP 2017-225647 A JP 2009-172292 A

By the way, the driver's autonomic nervous system changes over time due to fatigue, drowsiness, stress, poor physical condition, etc. If drowsiness or poor physical condition occurs while driving, it may not be possible to drive safely, so it is possible to estimate the driver's condition by monitoring changes in the state of the autonomic nervous system. .

However, changes in the state of the autonomic nervous system may be caused not only by internal factors such as drowsiness and poor physical condition, but also by external factors such as environmental changes around the driver. For example, when a vehicle enters a tunnel, the surroundings become dark, and the parasympathetic nerves of the autonomic nervous system are activated, causing drowsiness. I have something to do. Conventionally, when estimating changes in the autonomic nervous state of a driver, it is only determined whether or not internal factors have occurred, and changes in the autonomic nervous state due to external factors are not considered. There is room for improvement in accurately determining changes in neural conditions.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and is a driver state determination device capable of distinguishing whether a change in the autonomic nervous state of a driver during driving is an internal factor or an external factor. intended to provide

In order to achieve the above object, a driver condition determination device according to the present invention includes a pulse sensor that detects the heartbeat of a driver during driving of a vehicle, an illumination sensor that detects an illumination value around the driver, an illuminance value detected by the illuminance sensor and an illuminance holding unit that determines a change in ambient brightness based on a preset threshold; an arithmetic processing unit that determines the state of the driver's autonomic nerves based on the change in ambient brightness determined by the illuminance holding unit, and outputs the determination result according to the determination result; The unit determines a light condition when the illuminance value detected by the illuminance sensor is greater than the threshold value, and determines a dark condition when the illuminance value is less than the threshold value, and the arithmetic processing unit determines that heart rate variability of the driver increases, and After changing from the light condition to the dark condition, if the driver's heart rate variability starts to decrease without changing from the dark condition, the sympathetic nerve among the autonomic nerves is activated by an external factor. and if there is no change from the dark condition and the heart rate variability of the driver has not turned to decrease, it is determined that the parasympathetic nerves among the autonomic nerves have been activated due to an internal factor. Characterized by

According to the driver's state determination device according to the present invention, it is possible to separate and determine whether the change in the autonomic nervous state of the driver during driving is an internal factor or an external factor.

FIG. 1 is a block diagram showing a schematic configuration of the driver's condition determination device according to the embodiment. FIG. 2 is a schematic diagram showing an example of a driver state determination device mounted on a vehicle. FIG. 3 is a schematic diagram of an electrocardiographic waveform and a heartbeat interval used in the driver's condition determination device. FIG. 4 is a schematic diagram showing an example of heart rate variability used in the driver's condition determination device. FIG. 5 is a schematic diagram showing an example of a Poincare plot using autocorrelation of heart rate variability. FIG. 6 is a schematic diagram showing an example of an index of dispersion evaluation of a plot by a Poincaré plot. FIG. 7 is a schematic diagram showing an example of an index for concentrated evaluation of plots by Poincaré plots. FIG. 8 is a schematic diagram showing an example of changes in L/T values under light and dark conditions during a cognitive task. FIG. 9 is a schematic diagram showing an example of change in L/T value with respect to change in illuminance. FIG. 10 is a flow chart showing part of the driver's condition determination processing executed by the driver's condition determination device. FIG. 11 is a flow chart diagram showing another part of the driver's state determination processing executed by the driver's state determination device.

A driver's condition determination device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In addition, this invention is not limited by embodiment shown below. Components in the following embodiments include components that can be easily assumed by those skilled in the art, or components that are substantially the same. Also, the constituent elements in the following embodiments can be omitted, replaced, and changed in various ways without departing from the scope of the invention.

[Embodiment]
The driver state determination device 1 according to the present embodiment is mounted in a vehicle such as an automobile, for example, and uses a pulse sensor and an illumination sensor to determine the autonomic nerve state of the driver during driving. Autonomic nerves are nerves that generally control the movement of internal organs, blood vessels, etc. of the human body and regulate the internal environment. The sympathetic nerve controls "the nerve when you are awake, the nerve when you are tense," and the parasympathetic nerve controls "the nerve when you are asleep, and the nerve when you are relaxed." These two nerves act in opposition to each other on one organ. A driver's state determination device 1 of the present embodiment includes an illumination sensor 2, a pulse sensor 3, an arithmetic processing unit 4, and an information reporting unit 5, as shown in FIG.

The illuminance sensor 2 is a known illuminance sensor, and is arranged, for example, on the dashboard 101 inside the vehicle 100 shown in FIG. The illuminance sensor 2 is composed of, for example, a light receiving element (not shown) such as a photodiode or a phototransistor, converts light incident on the light receiving element into a current value, and outputs the current value to the arithmetic processing unit 4 . The arithmetic processing unit 4 converts the current value output from the illuminance sensor 2 into an illuminance value and holds the illuminance value. For example, the arithmetic processing unit 4 holds the detection time (detection time) of the illuminance value together with the illuminance value.

The heartbeat sensor 3 is composed of, for example, a known electrocardiogram sensor. An electrocardiographic sensor acquires the electrical activity state of the heart of a human being, etc., and is often used for electrophysiological examinations. The pulsation sensor 3 is arranged, for example, on the steering wheel 102 of the vehicle 100 so as to be in direct contact with the driver's skin, and detects the electrocardiogram of the driver who grips the steering wheel 102 while driving the vehicle. The heartbeat sensor 3 may be a heartbeat sensor with high temporal resolution as long as it can detect the time between beats (heartbeat interval) in the movement (beat) of the human heart. The heartbeat sensor may perform non-contact detection using the Doppler effect using radio waves, or may detect heartbeats using a piezoelectric element. FIG. 3 shows an example of an electrocardiogram waveform and a heartbeat interval output from the heartbeat sensor 3 when the heartbeat sensor 3 is an electrocardiographic sensor. The electrocardiographic waveform has time (seconds) on the horizontal axis and magnitude of voltage (mV) on the vertical axis, and is composed of P, QRS, and T waves. Heart beat is controlled by both sympathetic nerves and parasympathetic nerves, and heart rate variability is used as the state of autonomic nerves. The heart rate variability means, for example, the variation in the interval of the R wave with the highest voltage value in the electrocardiographic waveform shown in FIG. Assuming that this R-wave interval is RRI (RR Interval), the RRI indicates the time required for the heart to operate one beat (heartbeat interval). Plotting the continuous RRI is the heart rate variability shown in FIG. The arithmetic processing unit 4 converts the voltage value output from the pulse sensor 3 into heart rate variability and holds it.

The arithmetic processing unit 4 determines the state of the driver's autonomic nerves based on heart rate fluctuations obtained from the detection results of the pulse sensor 3 and changes in ambient brightness determined by the illuminance holding unit 12, which will be described later. and outputs the determination result according to the determination result. The arithmetic processing unit 4 has a processing circuit (not shown) that implements various processing functions in the driver's condition determination device 1 . A processing circuit is implemented by, for example, a processor. A processor means a circuit such as a CPU (Central Processing Unit), an MPU (Micro Processing Unit), an ASIC (Application Specific Integrated Circuit), and an FPGA (Field Programmable Gate Array). The arithmetic processing unit 4 realizes each processing function by, for example, executing a program read from a storage circuit (storage section) (not shown). The arithmetic processing unit 4 includes a heart rate variability calculator 10 , a heart rate fluctuation analyzer 11 , an illuminance holder 12 , a state determiner 13 , and a determination result holder 14 . The heart rate variability calculation unit 10, the heart rate fluctuation analysis unit 11, the illuminance holding unit 12, the state determination unit 13, and the determination result holding unit 14 may all be configured by hardware, or may be partially configured by hardware. and the other part may be composed of software.

The heartbeat variability calculation unit 10 reads the heartbeat interval from the electrocardiographic waveform detected by the heartbeat sensor 3, and calculates the heartbeat variability from the change in the heartbeat interval. In the case of continuous electrocardiographic waveforms, by continuously acquiring RRIs, it is possible to capture the elapsed time during which the electrocardiogram is being detected and changes in heartbeat intervals within the elapsed time. It is normal for heart rate variability not to take a constant value due to fluctuations due to autonomic nerve activity such as respiration or blood pressure fluctuation. When autonomic nerve activity is suppressed by drugs or the like, or when autonomic nerve activity decreases due to stress, poor physical condition, etc., the fluctuation disappears and approaches a constant value. The heart rate variability calculation unit 10 calculates heart rate variability based on the above method even when the heart rate is calculated using a device other than an electrocardiographic sensor.

The heartbeat variability analysis unit 11 analyzes the heartbeat variability in a predetermined section from the heartbeat variability obtained by the heartbeat variability calculation unit 10 . As a method of analysis, a Poincaré plot (see FIG. 5) using autocorrelation of heart rate variability is used. A Poincaré plot is obtained by plotting the RRI (n-th) at a given time on the horizontal axis and the RRI (n+1-th) at the next time on the vertical axis. Points plotted in a predetermined interval with small heart rate fluctuations (small fluctuations) due to tension, stress, etc. are concentrated. For example, Poincaré plots of healthy subjects with no underlying disease are distributed in an elliptical shape with a straight line RRI(n+1)=RRI(n) as the major axis. At this time, as a method of evaluating the concentration and dispersion of the point group, the L/T value is used, where L and T are the standard deviations of the distribution in the long axis and short axis directions of the ellipse. As shown in FIG. 6, if the L/T value is large, the ellipse extends in the major axis direction and the point cloud is dispersed. On the other hand, as shown in FIG. 7, when the L/T value is small, the point cloud is close to a perfect circle and concentrated. Therefore, when the L/T value is large, the heart rate variability is large, and when the L/T value is small, the heart rate variability is small. Heartbeat fluctuation analysis section 11 outputs the calculated L/T value to state determination section 13 . When the Poincare plot is used, the predetermined interval constituting the Poincare plot is an arbitrary time such as 1 minute or 3 minutes, but it may be an interval in which the illuminance value detected by the illuminance sensor 2 is constant.

The illuminance holding unit 12 holds the illuminance value detected by the illuminance sensor 2 . In addition, the illuminance holding unit 12 holds the time when the driver is driving the vehicle and the average illuminance value detected by the illuminance sensor 2 at that time. In addition, the illuminance holding unit 12 determines the ambient brightness based on a preset threshold value and the illuminance value detected by the illuminance sensor 2 . When the illuminance value detected by the illuminance sensor 2 is greater than the threshold, the illuminance holding unit 12 determines that the ambient brightness is bright (light condition). On the other hand, when the illuminance value detected by the illuminance sensor 2 is smaller than the threshold, the illuminance holding unit 12 determines that the ambient brightness is dark (dark condition). If the illuminance holding unit 12 compares the illuminance value detected by the illuminance sensor 2 with the threshold value and determines that they are the same, it determines that the ambient brightness has not changed. The illuminance holding unit 12 is composed of, for example, a RAM (Random Access Memory) or the like.

The state determination unit 13 uses the L/T value calculated by the heartbeat fluctuation analysis unit 11 and the ambient brightness determined by the illuminance holding unit 12 to determine whether changes in the driver's autonomic nerve state are caused by external factors. determine whether it is due to internal factors. Further, when the change in the autonomic nervous state of the driver is due to an internal factor, the state determination unit 13 determines whether the change is due to stress or poor physical condition or due to drowsiness or relaxation.

There are two types of influences of external factors, for example, the following two types of influences (1) and (2) of illuminance brightness among environmental changes around the driver.
(1) Changes in the state of autonomic nerves that occur immediately after changes in illuminance: Changes in the illuminance around the driver change the state of the autonomic nerves. Generally, when it gets bright, the sympathetic nerves of the autonomic nerves are activated, and when it gets dark, the parasympathetic nerves of the autonomic nerves are activated.
(2) Changes in the state of the autonomic nervous system during driving in an illuminance environment: When the surroundings of the driver are bright while driving, the parasympathetic nervous system of the autonomic nervous system is activated, and when it is dark, the sympathetic nervous system of the autonomic nervous system is activated.
The above (1) and (2) are seemingly contradictory, but (1) simply shows the reaction of the human body caused by changes in the surrounding brightness, and (2) shows a highly sophisticated situation while driving a vehicle. It shows that when the surroundings are bright, it is easy to see, and when it is dark, it becomes difficult to see, and this manifests itself as stress.

Regarding (2) above, Fig. 8 shows the relationship between the L/T value and the illuminance conditions during the cognitive task. In the illustrated graph, the horizontal axis represents the illuminance condition, and the vertical axis represents the L/T value. In the graph shown, two subjects A and B performed two cognitive tasks, for example, a search task of finding an image that differs only by one from a group of images displayed on the display, and a number reading aloud to the number two before. It shows the change in the L/T value with respect to the illuminance conditions when the 2-back task of answering verbally is performed at the same time. Both subjects A and B had lower L/T values under the dark condition than under the light condition, suggesting that sympathetic nerve activity is caused by internal factors such as stress and tension. In other words, when the surroundings of the driver are bright, the parasympathetic nerves are activated, and when it is dark, the sympathetic nerves are activated. Also, although the absolute value of the L/T value varies depending on individual differences, the degree of decrease in the L/T value is approximately the same. It can be determined whether the L/T value has decreased without relative comparison.

Regarding (1) above, FIG. 9 shows changes in the L/T value with respect to changes in the illuminance environment. In the illustrated example, effects such as driver stress, irritation, and sleepiness during driving are ignored. When the illuminance environment changes from section A (bright condition) to section B (dark condition) shown in FIG. Since the dark condition continues, the sympathetic nerve among the autonomic nerves is activated. On the other hand, when the illuminance environment changes from section B (dark conditions) to section C (bright conditions) shown in FIG. In , the light condition continues, so the parasympathetic nerves of the autonomic nerves are activated.

The judgment result holding unit 14 holds information corresponding to the judgment result of the driver's autonomic nerve state judged by the state judging unit 13 . The determination result holding unit 14 stores, for example, a ROM (Read Only Memory) holding the average value and the variance value of the L/T values acquired during the driver's daily driving, the above-described threshold value, and the and a RAM that holds an illuminance value for each predetermined interval specified in advance.

The information notification unit 5 notifies the notification target including the driver of the notification information based on the determination result by the arithmetic processing unit 4 . When the determination result is input from the state determination unit 13 of the arithmetic processing unit 4, the information notification unit 5 issues a warning or the like to the driver, who is the notification target, to assist the driver in safe driving. The notification information is to alert or warn the driver. The target of notification is, in principle, the driver, but it may be a person other than the driver. The information notification unit 5 may use a device (for example, a navigation monitor, etc.) pre-installed in the vehicle, or may be added to the vehicle. The information notification unit 5 is, for example, an audio output device that outputs sound or voice, and may generate a warning sound or the like for the driver. The information notification unit 5 is, for example, a meter display that displays characters, icons, etc., a navigation monitor, a head-up display, or the like, and may display a warning to the driver. Further, the information notification unit 5 may be a device that is arranged on a seat or the like and generates vibration, or may be a device that warns the driver in a seated state by vibration. In principle, the information notification unit 5 notifies the driver of the notification information. The configuration may be such that both are notified at the same time. Here, the external device may be a mobile terminal such as a smart phone owned by the driver or a person other than the driver (for example, a family member).

Next, the algorithm for determining the driver's state executed by the arithmetic processing unit 4 will be described with reference to FIGS. 10 and 11. FIG.

In FIG. 10, in step S1, the state determination unit 13 compares the L/T values corresponding to the preceding and succeeding predetermined intervals among the plurality of L/T values calculated by the heartbeat fluctuation analysis unit 11.

In step S2, the state determination unit 13 determines whether the L/T value has increased from the result of the comparison in step S1. As a result of this determination, if the L/T value has increased, the process proceeds to step S3, while if the L/T value has not increased, the process proceeds to step S20 in FIG.

In step S3, the illuminance holding unit 12 determines changes in ambient brightness based on the illuminance value detected by the illuminance sensor 2 and a preset threshold value. The illuminance holding unit 12 determines that the illuminance value detected by the illuminance sensor 2 is bright when the illuminance value is larger than the threshold, and determines that the illuminance value is smaller than the threshold as the dark condition. When the illuminance value detected by the illuminance sensor 2 and the threshold value are the same, for example, illuminance values with different detection times are extracted from the plurality of illuminance values held by the illuminance holding unit 12, and the illuminance value is may be compared with a threshold value. The illuminance value with different detection times may be, for example, the illuminance value at the previous detection time or the illuminance value at the later detection time with respect to the detection time of the illuminance value that is the same as the threshold.

In step S4, the state determination unit 13 determines whether or not the ambient brightness has changed from the bright condition to the dark condition based on the determination result in step S3. As a result of this determination, if the light condition has changed from the dark condition, the process proceeds to step S5. If the bright condition has not changed from the dark condition, the process proceeds to step S12.

In step S5, when the L/T value increases and the light condition changes to the dark condition, the state determination unit 13 determines that there is a possibility that the state of the autonomic nervous system has changed due to an environmental change, that is, an external factor. judge. This change in the state of the autonomic nervous system is presumed to be due to the activation of the parasympathetic nervous system of the driver's autonomic nervous system in response to the change in the darkness, as described in (1) above.

In step S6, the state determination unit 13 turns on the flag.

In step S7, the state determination unit 13 compares the L/T values corresponding to three predetermined intervals after the flag is turned on among the plurality of L/T values calculated by the heartbeat fluctuation analysis unit 11.

In step S8, the illuminance holding unit 12 determines changes in ambient brightness based on the illuminance value detected by the illuminance sensor 2 and a preset threshold value. The illuminance holding unit 12 determines that the illuminance value detected by the illuminance sensor 2 is bright when the illuminance value is larger than the threshold, and determines that the illuminance value is smaller than the threshold as the dark condition. If the illuminance value detected by the illuminance sensor 2 and the threshold value are the same, the process is the same as step S3. As a result of the determination in step S8, if the dark condition has not changed, the process proceeds to step S9. S13) and returns to step S1.

In step S9, the state determination unit 13 determines whether or not the L/T value has turned to decrease based on the result of comparison in step S7. If the L/T value has turned to decrease, the flag is reset (step S10), and proceed to step S11. On the other hand, if the L/T value has not started to decrease, the state determination unit 13 resets the flag (step S14) and proceeds to step S15.

In step S11, the state determination unit 13 determines that after the L/T value has increased and the surrounding brightness has changed from the light condition to the dark condition, the L/T value has not changed from the dark condition and the L/T value has decreased. In the case of a change, it is determined that the sympathetic nerve among the autonomic nerves has been activated by an external factor, and the process returns to step S1.

In step S12, if the L/T value has increased and the ambient brightness has not changed from the light condition to the dark condition, the state determination unit 13 determines that internal factors, such as relaxation, may cause the driver to It is determined that there is a possibility that the autonomic nerve state has changed, and the process returns to step S1.

In step S15, the state determination unit 13 determines that after the L/T value has increased and the ambient brightness has changed from the light condition to the dark condition, the L/T value has not changed from the dark condition and the L/T value has decreased. If not, it is determined that the sympathetic nerves of the driver's autonomic nerves have been activated due to internal factors, and the process returns to step S1. In other words, after the L/T value increases and changes from the light condition to the dark condition, if the L/T value does not change from the dark condition and the L/T value does not turn to decrease, the internal It is determined that a change in the autonomic nerve state has occurred due to an underlying factor.

In FIG. 11, in step S20, the state determination unit 13 determines whether the L/T value has decreased from the result of the comparison in step S1 of FIG. As a result of this determination, if the L/T value has decreased, the process proceeds to step S21, whereas if the L/T value has not decreased, the process returns to step S1 in FIG.

In step S21, the illuminance holding unit 12 determines changes in ambient brightness based on the illuminance value detected by the illuminance sensor 2 and a preset threshold value. The illuminance holding unit 12 determines that the illuminance value detected by the illuminance sensor 2 is bright when the illuminance value is larger than the threshold, and determines that the illuminance value is smaller than the threshold as the dark condition. If the illuminance value detected by the illuminance sensor 2 and the threshold value are the same, the process is the same as step S3.

In step S22, the state determination unit 13 determines whether or not the ambient brightness has changed from the dark condition to the bright condition based on the determination result in step S21. As a result of this determination, when the dark condition→bright condition is changed, the process proceeds to step S23, while when the dark condition→bright condition is not changed, the process proceeds to step S30.

In step S23, when the L/T value decreases and the dark condition changes to the bright condition, the state determination unit 13 determines that there is a possibility that the state of the autonomic nervous system has changed due to an environmental change, that is, an external factor. judge. This change in the autonomic nerve state is presumed to be due to the activation of the sympathetic nerve among the autonomic nerves of the driver in response to the change in brightness, as described in (1) above.

In step S24, the state determination unit 13 turns on the flag.

In step S25, the state determination unit 13 compares the L/T values corresponding to three predetermined intervals after the flag is turned on among the plurality of L/T values calculated by the heartbeat fluctuation analysis unit 11.

In step S26, the illuminance holding unit 12 determines changes in ambient brightness based on the illuminance value detected by the illuminance sensor 2 and a preset threshold value. The illuminance holding unit 12 determines that the illuminance value detected by the illuminance sensor 2 is bright when the illuminance value is larger than the threshold, and determines that the illuminance value is smaller than the threshold as the dark condition. If the illuminance value detected by the illuminance sensor 2 and the threshold value are the same, the process is the same as step S3. As a result of the determination in step S26, if the condition has not changed from the bright condition, the process proceeds to step S27. S31) and returns to step S1.

In step S27, the state determination unit 13 determines whether or not the L/T value has turned to increase based on the result of the comparison in step S25. If the L/T value has turned to increase, the flag is reset (step S28) and proceeds to step S29. On the other hand, if the L/T value has not started to increase, the state determination unit 13 resets the flag (step S32) and proceeds to step S33.

In step S29, the state determination unit 13 determines that after the L/T value has decreased and the surrounding brightness has changed from the dark condition to the bright condition, the L/T value has not changed from the bright condition and the L/T value has increased. If it is reversed, it is determined that the parasympathetic nerve among the autonomic nerves has been activated by an external factor, and the process returns to step S1.

In step S30, if the L/T value has decreased and the ambient brightness has not changed from the dark condition to the bright condition, internal factors such as stress and poor physical condition are factors, It is determined that there is a possibility that the driver's autonomic nerve state has changed.

In step S33, after the L/T value has decreased and the ambient brightness has changed from the dark condition to the bright condition, the state determination unit 13 determines that the L/T value has not changed from the bright condition and the L/T value has increased. If not, it is determined that the sympathetic nerves of the driver's autonomic nerves have been activated due to internal factors, and the process proceeds to step S34. In other words, after the L/T value has decreased and changed from the dark condition to the bright condition, if the L/T value has not changed from the bright condition and the L/T value has not turned to increase, the internal It is determined that a change in the autonomic nerve state has occurred due to an underlying factor.

In step S34, the state determination unit 13 outputs notification information corresponding to the determination result to the information notification unit 5 based on the determination result in step S33, and causes the information notification unit 5 to notify the notification information. , the process returns to step S1 in FIG. If the information notification unit 5 is a display mounted on the vehicle 100, the notification information is, for example, display information that prompts the driver to stop and take a rest. The internal factors in the present embodiment are divided into cases of relaxation and the like and cases of stress, poor physical condition and the like, but the notification information may have the same content or may have different content. may

In the present embodiment, if the autonomic nerve state changes due to an external factor, the tendency of the L/T value will then reverse (increase→decrease or decrease→increase), so a flag is set (ON) at the start of the change. , L/T values corresponding to three predetermined intervals after the flag ON are compared. From the result of the comparison, if the change in the L/T value is reversed from the initial trend, it is determined that the change in the autonomic nerve state is caused by an external factor, and if not, it is determined that the change in the autonomic nerve state is caused by an internal factor. On the other hand, after comparing the L/T values corresponding to the three predetermined intervals after the flag is turned on, if the surrounding brightness has not changed, the flag is reset and the process returns to step S1.

As described above, the driver condition determination device 1 according to the present embodiment includes the heartbeat sensor 3 that detects the heartbeat of the driver during driving, the illuminance sensor 2 that detects the illuminance value around the driver, An arithmetic processing unit 4 that determines the state of the driver's autonomic nerves based on heart rate fluctuations obtained from the detection results of the motion sensor 3 and changes in ambient brightness determined by the illuminance holding unit 12 . The arithmetic processing unit 4 detects that after the driver's heart rate variability increases and the surrounding brightness changes from the light condition to the dark condition, the dark condition does not change and the driver's heart rate variability turns to decrease. In this case, it is determined that the sympathetic nerve among the autonomic nerves is activated by an external factor. On the other hand, if there is no change from the dark condition and the heart rate variability of the driver has not started to decrease, it is determined that the parasympathetic nerves among the autonomic nerves have been activated due to an internal factor.

With the above configuration, when the L/T value increases and the illuminance value decreases (light condition→dark condition), the environmental change, that is, the external factor, causes a change in the state of the autonomic nervous system. It is possible to accurately determine a change in the driver's autonomic nerve state due to an external factor by determining whether or not. In addition, if the L/T value increases and the illuminance value does not change or increases (dark condition → light condition), internal factors such as relaxation will cause changes in the autonomic nervous state. By determining whether or not this applies, it is possible to accurately determine changes in the autonomic nervous state of the driver due to internal factors. That is, it is possible to accurately determine whether the change in the driver's autonomic nerve state is due to an external factor or an internal factor. In addition, the arithmetic processing unit 4 can be applied to the ECU (Engine Control Unit) mounted on the vehicle 100, and the device can be configured simply by adding a pulsation sensor, thereby reducing costs without using a high-spec ECU. can be suppressed. It is also possible to use a heart rate sensor or the like mounted on a wearable terminal, and by using the terminal, it is possible to eliminate the annoyance of the driver wearing a sensor on his/her body.

Further, the driver's state determination device 1 does not change the illuminance value (light condition→light condition) after the driver's L/T value decreases and the illuminance value increases (dark condition→light condition). , and when the L/T value of the driver turns to increase, it is determined that the parasympathetic nerve among the autonomic nerves is activated by an external factor. As a result, it can be easily determined that the change in the driver's autonomic nerve state is caused by an external factor.

Further, the driver's state determination device 1 does not change the illuminance value (light condition→light condition) after the driver's L/T value decreases and the illuminance value increases (dark condition→light condition). , and the L/value of the driver does not turn to an increase, it is determined that the sympathetic nerve among the autonomic nerves has been activated due to an internal factor. As a result, it can be easily determined that the change in the driver's autonomic nerve state is caused by an internal factor.

In addition, the driver's condition determination device 1 further includes an information notification unit 5 that provides notification information to notification targets including the driver based on the determination result of the arithmetic processing unit 4 . When the arithmetic processing unit 4 determines that the state of the autonomic nervous system has changed due to an internal factor, the information notification section 5 notifies notification information corresponding to the determination result. From this, it is presumed that the change in the driver's autonomic nervous state is due to internal factors such as stress and poor physical condition, and the information notification unit 5 notifies the driver to stop and take a rest. , can effectively assist the driver's safe driving.

In addition, when the arithmetic processing unit 4 determines that the autonomic nerve state has changed due to an external factor, the driver's condition determination device 1 does not perform notification by the information notification unit 5 . As a result, the driver is not notified of changes in the autonomic nervous state due to, for example, entering and exiting a tunnel, and annoyance to the driver can be suppressed. This is because the driver wants to know changes in the autonomic nerve state due to internal factors.

[Modification]
In the above embodiment, the change in the autonomic nervous state of the driver is determined based on the L/T value of the Poincaré plot. RMSSD) or the like, or a method used in combination with other methods. As a result, changes in the autonomic nerve state of the driver can be determined with higher accuracy.

In the above embodiment, the illuminance sensor 2 is arranged with respect to the vehicle. The configuration may be such that the illuminance value is obtained by In this case, there is no need to provide a new illuminance sensor, and an increase in cost can be suppressed.

Further, in the above embodiment, in step S12 of FIG. 10 and step S30 of FIG. 11, the state determination unit 13 determines that there is a possibility that the autonomic nerve state of the driver has changed due to an internal factor, and Although it returns to step S1, it is not limited to this. For example, the state determination unit 13 may accumulate and hold the possibility determination results in steps S12 and S30, and add them to the determination elements. For example, the number of times it is determined that there is the above possibility is counted, and when the accumulated number of times exceeds a threshold, it is determined as a change in the driver's autonomic nervous state due to an internal factor.

Further, in the above embodiment, in step S7 of FIG. 10 and step S25 of FIG. Although the L/T values corresponding to the predetermined section are compared, it is not limited to this. The number of predetermined intervals for confirming changes in the L/T value is not limited to three, and any number of intervals other than three may be used. Further, in steps S3 and S8 in FIG. 10 and steps S21 and S26 in FIG. 11, the illuminance holding unit 12 detects changes in ambient brightness based on the illuminance value detected by the illuminance sensor 2 and a preset threshold value. is determined, but is not limited to this. For example, in steps S3 and S21, the state determination unit 13 may compare the illuminance values in the same section as the predetermined section compared in step S1. In this case, the state determination unit 13 reads the average illuminance values of the times corresponding to the same section from the illuminance holding unit 12 . Further, in steps S8 and S26, the state determination unit 13 may compare the illuminance values of the three predetermined sections compared in step S7 and the same section, and determine whether or not the illuminance value has changed. . In this case, the state determination unit 13 reads the average illuminance values of the times corresponding to the same section from the illuminance holding unit 12 .

In addition, in the above embodiment, as a means of analyzing heartbeat fluctuations, there is a method of treating time-series changes in heartbeats as waves and analyzing them in the frequency domain, but this is not considered suitable for the present invention. The reason for this is that the discrete Fourier transform used for analysis requires a certain number of data or more, so it is not suitable for analysis for a short period of time such as one minute. Changes in illuminance occur not only during the day, evening, and night, but also through temporary changes such as in tunnels.

Also, in the above embodiment, the case where the present invention is applied to the driver's condition determination device 1 has been described, but the above effects can be obtained even if it is applied to the driver's condition determination system.

Also, in the above embodiment, the arithmetic processing unit 4 is described as having each processing function realized by a single processor, but the present invention is not limited to this. The arithmetic processing unit 4 may realize each processing function by combining a plurality of independent processors and executing a program by each processor. Moreover, the processing functions of the arithmetic processing unit 4 may be appropriately distributed or integrated in a single or a plurality of processing circuits. Further, the processing functions of the arithmetic processing unit 4 may be implemented entirely or in part by a program, or may be implemented by hardware such as wired logic.

In addition, in the above embodiment, the driver's state determination device 1 is applied to vehicles such as automobiles, but is not limited to this, and may be applied to ships, aircraft, etc. other than vehicles, for example.

The program executed by the processor described above is pre-installed in a memory circuit or the like and provided. This program may be recorded in a computer-readable storage medium and provided as an installable or executable file for these devices. Also, this program may be provided or distributed by being stored on a computer connected to a network such as the Internet and downloaded via the network.

REFERENCE SIGNS LIST 1 driver state determination device 2 illuminance sensor 3 pulsation sensor 4 arithmetic processing unit 5 information reporting unit 10 heart rate variability calculation unit 11 heart rate fluctuation analysis unit 12 illuminance storage unit 13 state determination unit 14 determination result storage unit 100 vehicle

Claims

a heartbeat sensor for detecting the heartbeat of the driver while driving the vehicle;
an illuminance sensor that detects an illuminance value around the driver;
an illuminance holding unit that determines a change in ambient brightness based on the illuminance value detected by the illuminance sensor and a preset threshold value;
determining the state of the autonomic nerves of the driver based on the heartbeat variability obtained from the detection result of the heartbeat sensor and the change in ambient brightness determined by the illuminance holding unit; and an arithmetic processing unit that outputs the determination result,
The illuminance holding unit determines a light condition when the illuminance value detected by the illuminance sensor is greater than the threshold value, and determines a dark condition when the illuminance value is smaller than the threshold value,
The arithmetic processing unit is
After the driver's heart rate variability increases and changes from the light condition to the dark condition,
determining that the sympathetic nerves of the autonomic nerves have been activated by an external factor when there is no change from the dark condition and the heart rate variability of the driver starts to decrease;
If there is no change from the dark condition and the heart rate variability of the driver has not turned to decrease, it is determined that the parasympathetic nerve among the autonomic nerves has been activated due to an internal factor.
A driver's state determination device characterized by:
The arithmetic processing unit is
after the driver's heart rate variability decreases and changes from the dark condition to the light condition;
determining that the sympathetic nerve among the autonomic nerves has been activated by the external factor when there is no change from the light condition and the heart rate variability of the driver turns to increase;
If there is no change from the light condition and the heart rate variability of the driver has not turned to increase, it is determined that the sympathetic nerve among the autonomic nerves has been activated by the internal factor.
The driver's condition determination device according to claim 1.
further comprising an information notification unit that notifies notification information to a notification target including the driver based on a determination result by the arithmetic processing unit;
The arithmetic processing unit is
When it is determined that the autonomic nerves are activated by the internal factor, the information notification unit notifies notification information corresponding to the determination result,
The driver's state determination device according to claim 1 or 2.