Driver's physical and mental state determination method and system thereof

Abstract

To provide a method and system for determining an operator's mental and physical condition from both of heart rate data and aspiration data of an operator to be measured.SOLUTION: The method and system determine an operator's mental and physical condition by using time variation of a heart rate and aspiration measured for an operator during operation of a railroad vehicle and calculating an RSA value as a respiratory sinus arrhythmia (RSA) component of the heart rate on the basis of this association. The system measures the time variation in a simulation operation interval including a tension task and determines each reference value concerning physiological indexes, in advance. While measuring time variation in a real operation interval, in a case where the RSA value is lower than a reference RSA value at a specific position for determining an operator's mental and physical condition, the system determines a tension state of the operator on the basis of a variation width from a reference value of each physiological index. Furthermore, the system comprises: a measurement unit including a sensor for measuring time variation; and a control unit for calculating the physiological index.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method and a system for determining the mental and physical state of a driver during railway vehicle operation, and more particularly, to a method and a system for determining the mental and physical state of a driver from both measured heart rate and respiration data of the driver.

Background Art

[0002] The autonomic nervous system of humans is composed of the sympathetic nervous system and the parasympathetic nervous system, which balance to maintain the mental and physical state in a normal condition and cope with various daily lives. Here, heart rate variability (HRV) includes both components reflecting the activity of the sympathetic nervous system that reflects the mental and physical tension state and the activity of the parasympathetic nervous system that leads this function to a sedative state. Therefore, a system has been proposed that determines the activity state of the autonomic nervous system of a driver from the change in the driver's heart rate during vehicle operation and reflects it in the vehicle operation control or gives an alarm.

[0003] For example, Patent Document 1 discloses a method for detecting a change in the driver's heart rate and determining the activity state of the driver's autonomic nervous system. Here, the driver's heart rate is measured by electrodes provided on the steering wheel portion of the vehicle, the gripping state of the steering wheel provided with a plurality of electrodes is detected, and further, the driver is imaged to detect the posture, so that the activity state of the autonomic nervous system, that is, the state requiring attention in vehicle operation such as a sense of tension, drowsiness, anxiety, fatigue, and absent-mindedness (inattentiveness) can be determined from the heart rate and the state of the driver.

[0004] Also, regarding respiration, like the heart rate, it has a relationship with the autonomic nervous system. However, since respiration can be changed by human will, it is very difficult to determine the activity state of the driver's autonomic nervous system from only the biological cycle information of the measured respiration.

[0005] For example, Patent Document 2 discloses a method for determining the degree of psychological restlessness of a driver by measuring changes in the driving state in accordance with changes in breathing. A breathing signal is extracted from a body pressure signal from a pressure sensor provided on the back of the seat and driving state quantities of an accelerator and a brake. However, since the body pressure signal includes body pressure fluctuations based on operations of the accelerator and the brake, it is stated that body pressure fluctuations are removed from the body pressure signal by the driving state quantities to obtain an accurate breathing signal.

[0006] Also, Patent Document 3 discloses a wakefulness determination method for performing determination of wakefulness, which is an index of the activity state of the autonomic nerves such as "drowsiness", by numerically filtering the measured heartbeats for the appearance of respiratory fluctuations in the inter-beat interval (RRI) and detecting whether the variation state of the RRI is that of the normal driving state or a simple increase or simple decrease corresponding to a rapid change in mental load. Here, a reference line f(n) corresponding to the variation of the RRI is changed between the normal state and the state of simple increase or simple decrease, and the variance RRVn of the RRI with respect to this reference line f(n) is calculated, and it is stated that wakefulness is detected based on the variance RRVn.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0008] It has been proposed to extract the component corresponding to respiratory sinus arrhythmia (RSA) from the measured heart rate variability (HRV) and determine the activity state of the autonomic nervous system. Here, it is difficult to determine the activity state of the driver's autonomic nervous system from only the measured biological cycle information of respiration or heart rate alone. However, by measuring the respiratory variation simultaneously with the heart rate and performing predetermined filtering to remove noise, it is expected that both the heart rate and respiration data can be analyzed together to obtain an evaluation of the response to various situations during vehicle driving.

[0009] The present invention has been made in view of the above circumstances, and an object thereof is to provide a method and a system for determining the mental and physical state of a driver from both the measured heart rate and respiration data of the driver.

Means for Solving the Problems

[0010] The method for determining the mental and physical state of a driver during vehicle driving according to the present invention is a method for calculating the RSA value as the respiratory sinus arrhythmia (RSA) component of the heart rate from the time variations of the measured heart rate and respiration of the driver during railway vehicle driving and determining the mental and physical state. The time variations are measured in a simulated driving section including a stress task, and for physiological indices including respiratory length and / or respiratory amplitude and RSA value, together with a reference RSA value serving as a reference for each driver, each reference value including a reference respiratory length and / or a reference respiratory amplitude is determined in advance. While measuring the time variations in the actual operation section, when the RSA value is lower than the reference RSA value at a specific position for determining the mental and physical state, the tension state of the driver is determined from the variation range from each of the reference values of the physiological indices.

[0011] According to such a feature, the mental and physical state of the driver can be more clearly determined from both the measured heart rate and respiration data of the driver.

[0012] In the above-described invention, together with the reference RSA value, a reference heart rate is determined in accordance with the reference respiratory length and / or the reference respiratory amplitude, and in the determination of the state of tension, the variation width of the heart rate from the reference heart rate and / or the variation width of the RSA value from the reference RSA value are further combined for determination.

[0013] In the above-described invention, the reference value may be determined as the arithmetic mean through the simulated operation section of the corresponding physiological index.

[0014] In the above-described invention, in the determination of the state of tension, it may include discrimination of the magnitude of the variation width with respect to the standard deviation of the physiological index through the simulated operation section.

[0015] In the above-described invention, the RSA value may be calculated from the heart beats corresponding to one respiration of the respiration.

[0016] In the above-described invention, one or more are selected from the physiological indexes further including the heart rate, the heart rate change rate, and the respiratory length change rate for each driver together with the respiratory length as specific physiological indexes, and each reference value is determined from the measurement in the simulated operation section for the specific physiological indexes, and in the determination of the state of tension, the determination is made based on the variation width with respect to the corresponding reference value for the specific physiological indexes.

[0017] In the above-described invention, the simulated operation section includes non-tension tasks, one or more are selected from the physiological indexes corresponding to the non-tension tasks for each driver together with the respiratory length as second specific physiological indexes, and each reference value is determined from the measurement in the simulated operation section for the second specific physiological indexes, and when the RSA value is higher than the reference RSA value, the determination is made based on the variation width with respect to the corresponding reference value for the second specific physiological indexes.

[0018] In the above-described invention, it may be characterized in that the variation range from the reference RSA value is corrected by multiplying by a correction coefficient determined by comparing the respiratory waveform and the respiratory waveform and the heartbeat fluctuation waveform during one breath corresponding to each breath of the heartbeat fluctuation waveform.

[0019] In the above-described invention, it may be characterized in that the simulated operation section is provided by a driving simulator. According to such a feature, the temporal variations of the heartbeat and respiration in the simulated operation section can be easily measured, and the physical and mental state of the driver can be easily determined.

[0020] In the above-described invention, it may be characterized in that the temporal variation of the respiration is obtained by measuring the chest circumference or abdominal circumference of the driver. According to such a feature, respiration data can be easily obtained, and the physical and mental state of the driver can be easily determined.

[0021] Further, a system for determining the physical and mental state of a driver during vehicle operation according to the present invention is a system for calculating an RSA value as a respiratory sinus arrhythmia (RSA) component of the heartbeat from the correspondence using the temporal variations of the heartbeat and respiration measured in a driver during railway vehicle operation and determining the physical and mental state, including a measurement unit including a sensor for measuring the temporal variation, and a control unit for calculating physiological indexes including respiratory length and / or respiratory amplitude and RSA value from the temporal variation measured by the measurement unit, wherein the control unit determines, from the temporal variation measured in a simulated operation section including a stress task by the measurement unit, for each of the physiological indexes, reference values of a reference RSA value, a reference respiratory length and / or a reference respiratory amplitude as a reference for each driver, and while measuring the temporal variation in an actual operation section by the measurement unit, at a specific position for determining the physical and mental state, when the RSA value is lower than the reference RSA value, the stress state of the driver is determined from the variation range from each of the reference values of the physiological indexes.

[0022] According to such a feature, the physical and mental state of the driver can be more clearly determined from both the heartbeat and respiration data of the driver to be measured.

[0023] In the above-described invention, together with the reference RSA value, a reference heart rate is determined in accordance with the reference respiratory length and / or the reference respiratory amplitude, and in the determination of the state of tension, the variation range of the heart rate from the reference heart rate and / or the variation range of the RSA value from the reference RSA value are further combined for determination.

[0024] In the above-described invention, the control unit selects one or more from the physiological indices further including the heart rate, the heart rate change rate, and the respiratory length change rate for each driver and stores them as specific physiological indices, determines each reference value from the measurement in the simulated driving section for the specific physiological indices, and in the determination of the state of tension, makes a determination based on the variation range from the corresponding reference value for the specific physiological indices.

[0025] In the above-described invention, based on the time variation measured in the simulated driving section further including a non-tension task by the measurement unit, the control unit selects one or more for each driver together with the respiratory length from the physiological indices corresponding to the non-tension task and stores them as second specific physiological indices, determines each reference value for the second specific physiological indices, and when the RSA value is higher than the reference RSA value at a specific position for the determination of the mental and physical state, makes the determination based on the variation range from the corresponding reference value for the second specific physiological indices.

Brief Description of the Drawings

[0026]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0027] Hereinafter, specific embodiments of a method for determining the mental and physical state of a driver during vehicle operation and its system according to a typical example of the present invention will be described with reference to FIGS. 1 to 5.

[0028] As shown in FIG. 1, a determination system 1 for the mental and physical state of a driver during vehicle operation includes a waveform measurement unit 10 that measures the time variations of the driver's heartbeat and respiration as waveforms respectively, and a control unit 20 that receives and analyzes the waveform data of the time variations from the waveform measurement unit 10.

[0029] The waveform measurement unit 10 is, for example, a stretchable belt-shaped wearable device that can be worn on the driver's chest or abdomen, and includes a heartbeat measurement sensor 11 that measures the heartbeat and a respiration measurement sensor 12 that measures the respiration state. Here, the heartbeat measurement sensor 11 can acquire the time variation of the heartbeat, that is, the heart rate variability waveform HRV, by a plurality of electrocardiogram electrodes or the like. In addition, the respiration measurement sensor 12 can acquire a respiration waveform that is the time variation of respiration by a displacement sensor or the like that detects a change in the driver's chest circumference or abdominal circumference, that is, the perimeter length around the chest or abdomen. Thereby, the waveform measurement unit 10 can be, for example, a wearable sensor, and can measure the time variations of the heartbeat and respiration simultaneously and in the vicinity without restricting the driver's movement.

[0030] The control unit 20 controls the operation of the entire determination system 1 and includes a control device 21, a determination device 22, and a storage device 23. The control device 21 can command the waveform measurement unit 10 to measure the time variations of the heartbeat and respiration and receive the waveform data thereof. The determination device 22 can analyze the waveform data transferred from the control device 21 to determine the physical and mental state of the driver. The storage device 23 can store the programs executed by the determination device 22 and the waveform data received from the waveform measurement unit 10. The control unit 20 may further include an output device (not shown) such as a monitor.

[0031] The determination device 22 measures, by a predetermined determination program, the time variations of the heartbeat and respiration in the waveform data measured by, for example, the waveform measurement unit 10, and obtains, as physiological indexes, the heart rate (heartbeat interval), the heartbeat amplitude, the respiration length, and the respiration amplitude, together with the RSA value as the RSA (respiratory sinus arrhythmia) component, and can comprehensively determine the physical and mental state of the driver, particularly the state of tension or the state of non-tension, using these time variations. Note that the heartbeat interval is obtained as the reciprocal of the heart rate. In addition, regarding the heartbeat amplitude and the respiration amplitude among these physiological indexes, normalization is performed including the measurement method and the method of quantifying the amplitude. For example, one value may be obtained for each respiration for these amplitudes, and the amplitudes may be represented as relative values with respect to 1 when the driver is in the physical and mental state closest to the normal state.

[0032] Here, the relative magnitude and change of the RSA value are said to indicate the activity state of the parasympathetic nervous system, and when the state of tension is increased, the RSA value tends to be relatively lowered. Therefore, a reference RSA value serving as a reference value for the RSA value is determined, and it can also be determined that the driver is in a state of tension when the measured RSA value has decreased from the reference RSA value. However, it is difficult to determine the state of tension with high accuracy by a determination using only such an RSA value as an index.

[0033] Therefore, in this embodiment, the determination of the state of tension is made as follows. As described above, the RSA value tends to decrease in a state of tension. Therefore, when the RSA value is lower than the reference RSA value, the probability that the driver's mental and physical state is in a state of tension increases. Thus, when the RSA value is decreased from the reference RSA value, the relative strength of the state of tension is determined by the respiratory length and / or respiratory amplitude, which are respiratory components. When the state of tension is increased, both the respiratory length and the respiratory amplitude tend to decrease. Therefore, when the respiratory length and the respiratory amplitude are smaller than the predetermined reference respiratory length and reference respiratory amplitude, there is a high possibility that the state of tension is stronger than the reference state of tension (the state of tension corresponding to the reference RSA value), and the strength of the state of tension is determined based on the variation range from the reference respiratory length and reference respiratory amplitude. That is, the determination is made using the respiratory length and respiratory amplitude, which are values related to respiration, triggered by the RSA value, which is a value related to the heartbeat.

[0034] Here, the reference RSA value, the reference respiratory length, and the reference respiratory amplitude are each determined for each driver by measuring the temporal variations of the heartbeat and respiration in a simulated driving section including tasks that impose tension. That is, the variations in the heartbeat and respiration in response to tension vary from driver to driver, and the accuracy of the determination of the state of tension is ensured by determining the reference values for each individual driver.

[0035] In addition, in the determination of the state of tension, in addition to the respiratory length and respiratory amplitude, the heart rate, heart rate amplitude, and RSA value may be added. For example, a reference heart rate is also determined for the heart rate, and the variation range of the heart rate from the reference heart rate is discriminated and combined in the determination. Similarly, the variation range of the heart rate amplitude from the reference heart rate amplitude and the variation range of the RSA value from the reference RSA value may also be combined in the determination. By these means, an improvement in the determination accuracy can be expected.

[0036] Note that the method of determining the reference values (reference RSA value, reference respiratory length, reference respiratory amplitude, reference heart rate, reference heart rate amplitude) varies depending on what kind of tension state one wants to determine. For example, when only a relatively strong tension state is to be determined, the reference values may be set small (or large for heart rate). Also, by using the values corresponding to specific tasks in the simulated driving section as the reference values, it becomes possible to determine the strength of the tension state relatively compared to the tension state regarding that specific task.

[0037] Furthermore, the correlations between each physiological index of RSA value, respiratory length, respiratory amplitude, heart rate, and heart rate amplitude in the tension state or non - tension state are confirmed to vary among drivers. Such a tendency can be derived from the results in the above - mentioned simulated driving section, and based on the strong correlation, that is, the tendency of reproducibility of changes, physiological indices can be selected and their combinations determined, thereby determining the mental and physical state of the driver during vehicle operation. According to this, a clearer state determination becomes possible, so that not only the tension state but also the determination in the non - tension state can be made in the same way.

[0038] Next, an example of actually determining the mental and physical state of a driver using the determination system 1 will be described.

[0039] Here, the mental and physical state of the driver during railway vehicle operation, particularly the tension state, was determined. For this purpose, using the above - mentioned determination system 1, the heart rate and respiration of the driver during vehicle operation were measured in a simulated driving section including tasks that impose tension (tension tasks), and the time variations were obtained.

[0040] During the simulation operation period, in order to measure the driver's heartbeat and respiration during the driving operation, a simulated driving was carried out using a driving simulator. Specifically, a simple railway driving simulator composed of a large TV monitor and a one-handle type controller was used. In the simulated driving, the driver repeated the driving task a predetermined number of times while taking breaks. As the driving task, a driving section between four stations with a required time of about 10 minutes was set. The driving task included tasks that caused stress such as a driving operation to stop the running vehicle at a predetermined position. In addition, in order to concentrate on the simulated driving, the driver was instructed to drive at the specified speed limit according to the timetable. Here, the measurement results of the simulated driving repeatedly performed by one driver will be described.

[0041] As shown in FIG. 2, first, for the measured waveform data, the heart rate variability waveform HRV and the respiration waveform BW were arranged on the same time axis. The heart rate variability waveform HRV was cut out for each time range corresponding to the respiration section T delimited by the respiration start point S in the respiration waveform BW. At this time, there was synchrony between the heart rate variability waveform HRV and the respiration section T. Then, the amplitude of the heart rate variability waveform HRV in each respiration section T was defined as the RSA value. That is, the RSA value was obtained from the heartbeats corresponding to one respiration. Regarding the RSA value, it is preferable to define line segment data connecting the points on the heart rate variability waveform HRV corresponding temporally to each respiration start point S, and obtain it after performing a conversion process of subtracting this line segment data from the heart rate variability waveform HRV. By such a conversion process, components of the blood pressure fluctuation system affected by both the sympathetic nerve and the parasympathetic nerve can be removed.

[0042] For example, here, the arithmetic means of the RSA value, heart rate, respiration length, and respiration amplitude obtained through the above-described simulated operation period were used as the respective reference values, and for each of those other than the respiration amplitude, the standard deviation from such average value was obtained. The reference values were respectively called the reference RSA value, reference heart rate, reference respiration length, and reference respiration amplitude. Also, from the simulated operation period, the RSA value, heart rate, respiration length, and respiration amplitude corresponding to the positions during the stop operation (the point 20 seconds before stopping at the station) and the positions during the station stop where it is difficult to get tense were extracted, and these were used as comparison targets and scored as follows by comparing with the reference values.

[0043] That is, as shown in FIG. 3, when the RSA value is greater than or equal to the standard deviation with respect to the reference RSA value, +1 point is set; when it is greater than or equal to twice the standard deviation, +2 points are set; when it is less than the standard deviation, -1 point is set; and when it is less than twice the standard deviation, -2 points are set. The results other than 0 points were shown as the appearance rates during the stop operation and during the station stop, respectively. That is, regarding the fluctuation range from the reference RSA value, the score was given by discriminating the magnitude of the RSA value with respect to the standard deviation and twice its value. As a result, it was found that the RSA value tends to be small during the stop operation that is prone to tension. However, even during the station stop that is not prone to tension, the RSA value often becomes small, and it was found that it is difficult to determine the tension state only by the RSA value.

[0044] Also, as shown in FIG. 4(a), when the heart rate is greater than or equal to the standard deviation with respect to the reference heart rate, +1 point is set; when it is greater than or equal to twice the standard deviation, +2 points are set; when it is less than the standard deviation, -1 point is set; and when it is less than twice the standard deviation, -2 points are set. The results other than 0 points were shown as the appearance rates during the stop operation and during the station stop, respectively. Regarding the heart rate, it tended to increase during the stop operation that is prone to tension.

[0045] As shown in FIG. 4(b), when the respiratory length is greater than or equal to the standard deviation with respect to the reference respiratory length, +1 point is set; when it is greater than or equal to twice the standard deviation, +2 points are set; when it is less than the standard deviation, -1 point is set; and when it is less than twice the standard deviation, -2 points are set. The results other than 0 points were shown as the appearance rates during the stop operation and during the station stop, respectively. Regarding the respiratory length, it tended to decrease during the stop operation that is prone to tension.

[0046] As shown in FIG. 4(c), when the respiratory amplitude is twice or more with respect to the reference respiratory amplitude, +1 point is set; when it is half or less of the reference value, -1 point is set. The results other than 0 points were shown as the appearance rates during the stop operation and during the station stop, respectively. Regarding the respiratory amplitude, it tended to decrease during the stop operation that is prone to tension.

[0047] However, it was found that it is even more difficult to determine the state of tension solely by any of the heart rate, respiratory length, and respiratory amplitude than by the above-described determination using the RSA value.

[0048] Therefore, the scores of RSA, heart rate, respiratory length, and respiratory amplitude were converted in sign so that the ones more likely to occur in a tense state were made positive. That is, the scores of the RSA value, respiratory length, and respiratory amplitude were multiplied by -1, and the respective scores were summed up for a comprehensive determination.

[0049] As shown in Fig. 5, in the comprehensive determination, for the determination with a score of "3", it was almost during the stop operation, and the driver's mental and physical state was considered to be in a relatively strong state of tension. On the other hand, in the determination with a negative score, there were almost no cases during the stop operation, and it was considered very likely that the state of tension was relatively weak.

[0050] As described above, it is possible to determine the relative strength or weakness of the state of tension regarding the mental and physical state of the driver from both the measured heart rate and respiratory data of the driver. In particular, since the determination is made based on the difference between a reference value and a predetermined value such as using the reference RSA value and the standard deviation, the determination can be made only by the relative numerical change in the heart rate fluctuation waveform and the respiratory waveform. That is, the accuracy as the absolute value of the measured value is not required. Therefore, the detailed calculation method of the RSA value is not particularly limited as long as it is determined consistently from the simulated driving to the determination of the driver's mental and physical state. Also, it is meaningful to determine the driver's mental and physical state from both the heart rate and respiratory data, and even by simply combining the discrimination of one of the respiratory length or respiratory amplitude with the determination by the RSA value, the mental and physical state can be determined more accurately than by the determination using only the RSA value. Further, it is preferable to make a determination by combining both the respiratory length and the respiratory amplitude, and furthermore, it is also possible to make a determination by combining the heart rate, the RSA value, and the heart rate amplitude as described above.

[0051] In addition, as described above, since the measured values do not require accuracy as absolute values, for obtaining the respiratory waveform, a simple measurement method that only detects changes in the driver's chest circumference or abdominal circumference can be used, and a wearable sensor can be used for the measurement.

[0052] Also, in the above example, the RSA values, heart rates, heart rate amplitudes, respiratory lengths, and respiratory amplitudes during the stop operation and at station stops were extracted from the simulated driving section for determination. However, by using the reference values and standard deviations obtained in the simulated driving section, it is also possible to measure the temporal variations in the driver's heart rate and respiration in the actual operation section in the same way and determine the driver's physical and mental state. That is, by calculating the reference RSA value, reference respiratory length, reference respiratory amplitude, their respective standard deviations, and further the reference heart rate and reference heart rate amplitude in the simulated driving and storing them in the storage device 23, it is possible to determine the driver's physical and mental state in real time at a specific position in other driving sections such as subsequent actual operation sections. The specific position is the position where the driver's physical and mental state is to be determined and is the position on the time axis where the temporal variations in the heart rate and respiration are measured. However, it is also possible to make the position in space by corresponding the position in space within the driving section and the time axis. In particular, in the case of railways, the planned running of the vehicle on the running section is determined. For example, it is possible to determine the driver's physical and mental state even immediately before a specific section such as a station or a level crossing, and it is also possible to issue an alarm in some cases. As described above, since these reference values and standard deviations include individual differences of the driver, they are determined and used for each driver.

[0053] In the above example, the reference RSA value, reference heart rate, reference heart rate amplitude, reference respiratory length, and reference respiratory amplitude were determined as the arithmetic mean over the simulated driving section, but they may be determined by other means. For example, if the reference RSA value is determined as the maximum value of the values obtained in the simulated driving section, the reference RSA value can be assumed to be in a nearly complete relaxation state. Then, the driver's physical and mental state can be determined by stepwise scoring the tension state based on the reduced variation width of the RSA value from the reference RSA value and combining the discrimination of the variation width from the reference values such as the respiratory length in the same way as above.

[0054] Furthermore, when determining the physical and mental state by combining the fluctuation range of the RSA value from the reference RSA value, there is also a method to correct such a fluctuation range. First, each of the respiratory waveform and the heartbeat fluctuation waveform corresponding to one breath is defined as the respiratory waveform during one breath and the heartbeat fluctuation waveform during one breath. At this time, the respiratory waveform during one breath and the heartbeat fluctuation waveform during one breath are compared, and a correction coefficient is determined such that the higher the correlation between them, the closer to 1, and the lower the correlation, the closer to 0. Such a correction coefficient can be calculated, for example, using the correlation coefficient or the phase difference between the respiratory waveform during one breath and the heartbeat fluctuation waveform during one breath. If the correlation coefficient is used, the absolute value of the correlation coefficient can be used as the correction coefficient. If the phase difference is used, the absolute value of (π - phase difference) / π can be used as the correction coefficient. These two integrated values may also be used as the correction coefficient. Then, the correction is performed by multiplying the correction coefficient applied to the fluctuation range from the reference RSA value, and the determination is made in the same manner as above. Since the higher the correlation between the respiratory waveform during one breath and the heartbeat fluctuation waveform during one breath, the higher the reliability as the RSA value tends to be, by making such a correction, the reliability of the RSA value can be reflected, and the physical and mental state of the driver can be accurately determined.

[0055] Also, in the above-described embodiments, the state of tension at a certain point in time was determined based on the temporal fluctuations of the heartbeat and respiration at that time. However, it is also possible to determine the mental and physical state based on the temporal context. For example, when the RSA value is extremely high (e.g., 4 times or more the reference RSA value) and then, in the next respiration interval T (see FIG. 2), the fluctuation range (gap) from the reference RSA value is significantly lower than the standard deviation, it can be determined that the driver is in an extremely tense state or is psychologically unstable. Also, when breathing regularly, it is likely to be in a moderately tense state that is preferable for driving operations or in a state of reduced arousal. Therefore, when the gap of the breath length from the reference breath length is 10% or less in any of four consecutive respiration intervals T, it is regarded as regular breathing. Furthermore, when the heart rate is constant or increasing at a value greater than the reference heart rate, it is determined as moderate tension, and when it is constant or decreasing at a value less than the reference heart rate, it can be determined as a weaker state of tension (or a state of reduced arousal). Also, when taking a deep breath, such as when the respiration amplitude exceeds twice the reference respiration amplitude or the breath length is more than twice the standard deviation of the reference breath length, it can also be determined that there has been a switch in the mental and physical state around that time.

[0056] Here, among the five physiological indices obtained by adding the respiration length change rate and the heart rate change rate to the three physiological indices of the RSA value, the respiration length, and the heart rate, there are differences in the tendency to reproduce changes in response to a tension task for each individual driver being measured. On the other hand, it has been found that the change in response to a tension task is constant for the respiration length regardless of the individual driver. Therefore, by determining the state of tension using the respiration length and other physiological indices that are combined with it and that have a high tendency to reproduce changes in response to different tension tasks for each individual driver, a more accurate determination becomes possible.

[0057] That is, in the determination system 1, in the control unit 20, for each driver, one or more physiological indexes showing the reproduction tendency of changes in the respiratory rate change rate, heart rate (heartbeat interval), and heart rate change rate (heartbeat interval change rate) RSA value in response to the stress task, that is, repeating the same change, are selected and stored as specific physiological indexes together with the respiratory rate. Such selection may be performed by automatically filtering with a preset change range, or other known methods may be used. Then, together with the reference RSA value and reference respiratory rate for each driver, each reference value for the specific physiological index is determined in the same manner as described above. Then, in the determination of the stress state, in the same manner as above, the variation range from the corresponding reference value for the specific physiological index including the respiratory rate is combined for determination.

[0058] Fig. 6(a) shows an example of the appearance rates of the non-stress tendency and stress tendency for each physiological index in response to the stress task in a simulated driving including a plurality of stress tasks and non-stress tasks. The left side of the bar graph for each physiological index indicates the appearance rate showing an error determined to be in the non-stress state tendency, that is, determined to be in the non-stress state despite being a stress task, and the right side of the bar graph indicates the appearance rate determined to be in the stress state tendency, that is, showing the correct answer.

[0059] Note that the heartbeat interval change rate and respiratory rate change rate are calculated and evaluated as follows. Specifically, in advance, the heartbeat interval calculated when the driver is estimated to be in the psychosomatic state closest to the normal state is defined as "1". Then, when the differences between the 2nd to 4th heartbeat intervals (the difference from the 1st heartbeat interval in the case of the 2nd) and the previous time among the 4 continuously calculated heartbeat intervals per breath are all "0.25" or less, it is evaluated that the heartbeat interval is stable and regular, and this is used for the determination of the psychosomatic state. That is, the reference heartbeat interval change rate is defined as "0.25" or less, and the change rate per breath of the 4 continuously calculated heartbeat intervals is evaluated respectively. The respiratory rate change rate can be calculated and evaluated in the same manner as the heartbeat interval change rate.

[0060] According to this, along with the respiratory cycle, there is a tendency to show the correct answer in the heart rate interval. Therefore, as described above, compared with the comprehensive determination B (see Fig. 6(b)) that combines the variation width of the respiratory cycle with respect to the reference respiratory cycle and the variation width of the respiratory cycle change rate with respect to the reference respiratory cycle change rate, the comprehensive determination A (see Fig. 6(b)) that combines the variation width of the respiratory cycle with respect to the reference respiratory cycle and the variation width of the heart rate interval with respect to the reference heart rate interval shows the tendency of the tense state more correctly.

[0061] Although it was difficult to determine the non-tense state, in the same manner as above, for the second specific physiological index with a high tendency to reproduce changes for non-tense tasks (for example, when the train stops) that vary for each driver, the respiratory cycle was also selected and included, and the tense state can be determined using these.

[0062] As described above, representative embodiments according to the present invention have been described, but the present invention is not necessarily limited thereto and can be appropriately changed by those skilled in the art. That is, those skilled in the art will be able to find various alternative embodiments and modified examples without departing from the scope of the appended claims.

Explanation of Signs

[0063] 1 Determination system 10 Waveform measurement unit 11 Heart rate measurement sensor 12 Respiratory measurement sensor 20 Control unit 21 Control device 22 Determination device 23 Storage device

Claims

1. A method for determining the mental and physical state by calculating the RSA value as the respiratory sinus arrhythmia (RSA) component of the heartbeat from this correspondence using the time variation of the heartbeat and respiration measured in the driver during railway vehicle operation, measuring the time variation in a simulated driving section including a stress task, and determining, for each driver, respective reference values including a reference respiratory length, a reference respiratory amplitude, and a reference RSA value together with the reference RSA value serving as a reference for the physiological index composed of the respiratory length, the respiratory amplitude, and the RSA value, while measuring the time variation in the actual operation section, at a specific position for determining the mental and physical state, when the RSA value is lower than the reference RSA value, giving positive and negative signs to the variation widths from the reference RSA value, the reference respiratory length, and the reference respiratory amplitude for the RSA value, the respiratory length, and the respiratory amplitude respectively, normalizing, and determining the stress state of the driver before and after the stop operation by the total value. A method for determining the mental and physical state of a driver during vehicle operation, characterized in that.

2. Determining a reference heart rate and a reference heart rate amplitude in accordance with the reference respiratory length and the reference respiratory amplitude, The method for determining the mental and physical state of a driver during vehicle operation according to claim 1, further comprising giving positive and negative signs to one or more of the variation width of the heart rate from the reference heart rate and the variation width of the heart rate amplitude from the reference heart rate amplitude, normalizing, and summing to the value.

3. The reference RSA value, the reference respiratory length, the reference heart rate, and the reference heart rate amplitude are determined as the arithmetic means of the RSA value, the respiratory length, the heart rate, and the heart rate amplitude respectively through the simulated driving section. The method for determining the mental and physical state of a driver during vehicle operation according to claim 2, characterized in that.

4. The standard deviations of the RSA value, the respiratory length, and the heart rate through the simulated driving section are obtained, and when the variation width with respect to the standard deviation is small, it is not summed to the value. The method for determining the mental and physical state of a driver during vehicle operation according to claim 3, characterized in that.

5. The RSA value is calculated from the heartbeat corresponding to one respiration of the respiration. The method for determining the mental and physical state of a driver during vehicle operation according to any one of claims 1 to 4, characterized in that.

6. A correction coefficient determined by comparing the respiratory waveform and the respiratory waveform and the heartbeat fluctuation waveform during one breath corresponding to each breath of the heartbeat fluctuation waveform is multiplied by the width of the variation from the reference RSA value for the RSA value to obtain the variation width from the reference RSA value. The method for determining the mental and physical state of a driver during vehicle operation according to claim 2, characterized in that.

7. The method for determining the mental and physical state of a driver during vehicle operation according to any one of claims 1 to 6, characterized in that the simulated driving section is provided by a driving simulator.

8. The method for determining the mental and physical state of a driver during vehicle operation according to any one of claims 1 to 7, characterized in that the time variation of the respiration is obtained by measuring the chest circumference or abdominal circumference of the driver.

9. A system for calculating an RSA value as a respiratory sinus arrhythmia (RSA) component of the heartbeat from this correspondence using the time variation of the heartbeat and respiration measured in a driver during railway vehicle operation and determining the mental and physical state, A measurement unit including a sensor for measuring the time variation, A control unit that calculates physiological indexes including respiratory length, respiratory amplitude, and RSA value from the time variation measured by the measurement unit, The control unit, From the time variation measured in a simulated driving section including a stress task by the measurement unit, for each driver, a reference value including a reference RSA value, a reference respiratory length, and a reference respiratory amplitude is determined, and While measuring the time variation in the actual operation section by the measurement unit, when the RSA value is lower than the reference RSA value at a specific position for determining the mental and physical state, the RSA value, the respiratory length, and the respiratory amplitude are respectively the reference RSA value, the reference respiratory length, and the reference respiratory amplitude. A system for determining the mental and physical state of a driver during vehicle operation, characterized in that the positive and negative of the variation width from are given and normalized, and the total value is used to determine the stress state of the driver before and after the parking operation.

10. Determine a reference heart rate and a reference heart rate amplitude in accordance with the reference respiratory length and the reference respiratory amplitude, The system for determining the mental and physical state of a driver during vehicle operation according to claim 9, characterized in that the positive and negative are further given and normalized for any one or more of the variation width of the heart rate from the reference heart rate and the variation width of the heart rate amplitude from the reference heart rate amplitude, and the values are summed.

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