JP7794078B2 - Psychological state induction device and psychological state induction method - Google Patents

Description

This disclosure relates to a psychological state induction device and a psychological state induction method.

Technology is known that induces a subject's psychological state by guiding the timing of their breathing. Patent Document 1 discloses technology that allows the driver to distinguish between exhalation periods, inhalation periods, and grace periods through continuous changes in stimuli, such as changes in the brightness or color of light emitted. The grace period is a switching period during which the driver can either exhale or inhale.

Japanese Patent Application Laid-Open No. 2020-62282

The technology disclosed in Patent Document 1 does not precisely time the switch between inhalation and exhalation, as a grace period is provided.

One objective of this disclosure is to provide a psychological state induction device and psychological state induction method that, when inducing the driver's breathing timing through continuous changes in stimuli, allows the driver to more easily predict the timing of switching between exhalation and inhalation.

The above object is achieved by the combination of features recited in the independent claims, and the subclaims define further advantageous embodiments of the disclosure. The reference numerals in parentheses in the claims indicate a correspondence with the specific means described in the embodiments described below as one aspect, and do not limit the technical scope of the present disclosure.

In order to achieve the above object, the first psychological state induction device of the present disclosure includes a rhythm determination unit (205) that determines a target breathing rhythm for changing the psychological state of a vehicle driver to a target psychological state, and a breathing induction control unit (206, 206a, 206b, 206c) that controls stimuli for inducing the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit, wherein the rhythm determination unit determines an inhalation period for inhalation and an exhalation period for exhalation as the target breathing rhythm, and the breathing induction control unit assigns two patterns of continuous stimulus changes with different directions for the same type of stimulus to the inhalation period and the exhalation period, respectively. In addition to the first stimulus, which is applied at regular intervals, the rhythm determination unit also applies a second stimulus, which is an intermittent stimulus at regular intervals, and the target psychological states to be changed by the target respiratory rhythm determined by the rhythm determination unit include at least the driver's awake state and relaxed state. In the case of a target respiratory rhythm that targets an awake state, the respiratory induction control unit sets the period of the intermittent stimulus at regular intervals in the second stimulus to a shorter period than a heartbeat-like period, which is a period within a predetermined range starting from a period of 60 times per minute, while in the case of a target respiratory rhythm that targets a relaxed state, the respiratory induction control unit sets the period of the intermittent stimulus at regular intervals in the second stimulus to a longer period than the heartbeat-like period .
In order to achieve the above object, the second psychological state induction device of the present disclosure includes a rhythm determination unit (205) that determines a target breathing rhythm for changing the psychological state of a vehicle driver to a target psychological state, and a breathing induction control unit (206, 206a, 206b, 206c) that controls stimuli for inducing the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit, wherein the rhythm determination unit determines an inhalation period for inhalation and an exhalation period for exhalation as the target breathing rhythm, and the breathing induction control unit controls a first stimuli control unit (206) that assigns two patterns of continuous stimulus changes with different directions for the same type of stimulus to the inhalation period and the exhalation period, respectively. In addition to the first stimulus, a second stimulus, which is an intermittent stimulus at a fixed interval, is also given, and the target psychological states to be changed by the target respiratory rhythm determined by the rhythm determination unit include the driver's awake state and relaxed state, and a heart rate determination unit (232) is provided for determining the driver's heart rate, and the respiratory induction control unit, based on the heart rate determined by the heart rate determination unit, makes the period of the intermittent stimulus at a fixed interval in the second stimulus shorter than the period of the driver's heart rate in the case of a target respiratory rhythm that targets an awake state, while making the period of the intermittent stimulus at a fixed interval in the second stimulus longer than the period of the driver's heart rate in the case of a target respiratory rhythm that targets a relaxed state.

In order to achieve the above object, a first psychological state induction method of the present disclosure includes a rhythm determination step executed by at least one processor, for determining a target breathing rhythm for changing the psychological state of a vehicle driver to a target psychological state, and a breathing induction control step for controlling stimuli for inducing the driver to breathe in accordance with the target breathing rhythm determined in the rhythm determination step, wherein the rhythm determination step determines an inhalation period for inhalation and an exhalation period for exhalation as the target breathing rhythm, and the breathing induction control step allocates two patterns of continuous stimulus changes with different directions for the same type of stimulus to the inhalation period and the exhalation period, respectively. In addition to the first stimulus, which is applied by directing the force, a second stimulus, which is an intermittent stimulus at regular intervals, is also applied , and the target psychological states to be changed by the target respiratory rhythm determined in the rhythm determination process include at least the driver's awake state and relaxed state. In the respiratory induction control process, in the case of a target respiratory rhythm targeting an awake state, the period of the intermittent stimulus at regular intervals in the second stimulus is made shorter than the heartbeat-like period, which is a period within a predetermined range starting from a period of 60 times per minute, while in the case of a target respiratory rhythm targeting a relaxed state, the period of the intermittent stimulus at regular intervals in the second stimulus is made longer than the heartbeat-like period .
In order to achieve the above object, a second psychological state induction method of the present disclosure includes a rhythm determination step executed by at least one processor, for determining a target respiratory rhythm for changing the psychological state of a vehicle driver to a target psychological state, and a breathing induction control step for controlling stimuli for inducing the driver to breathe in accordance with the target respiratory rhythm determined in the rhythm determination step, wherein the rhythm determination step determines an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed as the target respiratory rhythm, and the breathing induction control step assigns two patterns of continuous stimulus changes with different directions for the same type of stimulus to the inhalation period and the exhalation period, respectively, and causes the changes to be performed. In addition to the first stimulus, a second stimulus, which is an intermittent stimulus at a fixed interval, is also applied. The target psychological states to be changed by the target respiratory rhythm determined in the rhythm determination process include the driver's awake state and relaxed state, and a heart rate identification process is included to identify the driver's heart rate. In the respiratory induction control process, based on the heart rate identified in the heart rate identification process, in the case of a target respiratory rhythm targeting an awake state, the period of the intermittent stimulus at a fixed interval in the second stimulus is made shorter than the period of the driver's heart rate, while in the case of a target respiratory rhythm targeting a relaxed state, the period of the intermittent stimulus at a fixed interval in the second stimulus is made longer than the period of the driver's heart rate.

According to these, a first stimulus is applied in which two patterns of continuous stimulus changes with different directions for the same type of stimulus are assigned to the inhalation period and the exhalation period, respectively. Therefore, by switching the pattern of continuous stimulus changes, the timing of the switch between the inhalation period and the exhalation period becomes easier to understand. Furthermore, by applying a second stimulus, which is an intermittent stimulus at regular intervals, in addition to the first stimulus, the timing of the switch between the inhalation period and the exhalation period becomes easier to predict. As a result, when guiding the driver's breathing timing with continuous stimulus changes, the driver can more easily predict the timing of the switch between inhalation and exhalation.

1 is a diagram illustrating an example of a schematic configuration of a driving assistance system 1. FIG. FIG. 2 is a diagram illustrating an example of a schematic configuration of an HCU 20. FIG. 10 is a diagram for explaining an example of stimulation control in the HCU 20. 10A and 10B are diagrams for explaining the effect of stimulation control in the HCU 20. FIG. 10 is a diagram for explaining an example of stimulation control in the HCU 20. FIG. 10 is a diagram for explaining an example of stimulation control in the HCU 20. FIG. 10 is a diagram for explaining an example of stimulation control in the HCU 20. 10 is a flowchart showing an example of the flow of psychological state guidance related processing in the HCU 20. FIG. 2 is a diagram illustrating an example of a schematic configuration of an HCU 20a.

Multiple embodiments of the disclosure will be described with reference to the drawings. For ease of explanation, parts in multiple embodiments that have the same functions as parts shown in figures used in previous explanations will be assigned the same reference numerals, and their description may be omitted. For parts assigned the same reference numerals, reference may be made to the explanations in other embodiments.

(Embodiment 1)
<General configuration of driving assistance system 1>
The present embodiment will be described below with reference to the drawings. A driving assistance system 1 shown in FIG. 1 is used in an automobile (hereinafter simply referred to as a vehicle). The driving assistance system 1 includes an HMI (Human Machine Interface) system 2, a communication device 3, a locator 4, a map database (hereinafter referred to as a map DB) 5, a surroundings monitoring sensor 6, a driving assistance ECU 7, a vehicle state sensor 8, and a vehicle control ECU 9. The HMI system 2, the communication device 3, the locator 4, the map DB 5, the driving assistance ECU 7, the vehicle state sensor 8, and the vehicle control ECU 9 are connected to, for example, an in-vehicle LAN. In the drawings, the in-vehicle LAN is referred to as LAN. A vehicle equipped with the driving assistance system 1 will be referred to as the host vehicle hereinafter.

The communication device 3 communicates with the center. The communication device 3 communicates with the center via a public communication network. The communication device 3 acquires traffic information, weather information, etc. from the center. Note that the communication device 3 may also be configured to communicate with the center via a roadside device.

Locator 4 is equipped with a GNSS (Global Navigation Satellite System) receiver and an inertial sensor. The GNSS receiver receives positioning signals from multiple artificial satellites. The inertial sensor includes, for example, a gyro sensor and an acceleration sensor. Locator 4 sequentially determines the vehicle position by combining the positioning signals received by the GNSS receiver with the measurement results of the inertial sensor. The vehicle position may also be determined using the travel distance calculated from signals sequentially output by a vehicle speed sensor installed in the vehicle.

Map DB5 is a non-volatile memory that stores map data. Map data includes, for example, link data, node data, and road attribute data. Map data distributed from the center may be received via communication device 3 and stored in map DB5. In this case, map DB5 may be a volatile memory.

The perimeter monitoring sensor 6 detects obstacles around the vehicle. It also detects road markings such as lane markings around the vehicle. The perimeter monitoring sensor 6 may be a perimeter monitoring camera, millimeter-wave radar, sonar, or LIDAR (Light Detection and Ranging/Laser Imaging Detection and Ranging). The perimeter monitoring camera captures images of a predetermined area around the vehicle. Millimeter-wave radar, sonar, and LIDAR transmit probe waves within a predetermined area around the vehicle. Hereinafter, millimeter-wave radar, sonar, and LIDAR will be referred to as probe wave sensors. The perimeter monitoring camera sequentially outputs the captured images to the driving assistance ECU 7 as sensing information. The probe wave sensor sequentially outputs scanning results based on received signals obtained when waves reflected by obstacles are received to the driving assistance ECU 7 as sensing information. The perimeter monitoring sensor 6 may also include a solar radiation sensor that detects solar radiation.

The driving assistance ECU 7 is an electronic control device that provides driving assistance for the vehicle. The driving assistance ECU 7 recognizes the environment surrounding the vehicle. To recognize the surrounding environment, the vehicle position acquired from the locator 4 is used. To recognize the surrounding environment, map data acquired from the map DB 5 is used. To recognize the surrounding environment, sensing information acquired from the perimeter monitoring sensor 6 is used. For example, the driving assistance ECU 7 recognizes the shape and movement state of objects around the vehicle from the sensing information acquired from the perimeter monitoring sensor 6. Then, by combining this recognition result with the vehicle position and map data of the vehicle, a virtual space that reproduces the actual driving environment in three dimensions is generated.

The driving assistance ECU 7 provides driving assistance for the vehicle by controlling acceleration/deceleration and/or steering of the vehicle based on the recognized surrounding environment. Examples of driving assistance include assistance for keeping the vehicle within its lane, assistance for driving the vehicle at a constant speed, and assistance for automatically decelerating the vehicle to avoid obstacles. Furthermore, the driving assistance may be configured to perform automatic driving.

The vehicle state sensors 8 are a group of sensors for detecting the state of the host vehicle. The state of the host vehicle includes the running state and operation state of the host vehicle. The vehicle state sensors 8 include a vehicle speed sensor that detects the speed of the host vehicle. The vehicle state sensors 8 include a steering sensor that detects the steering angle of the host vehicle's steering. The vehicle state sensors 8 include an accelerator position sensor that detects the opening degree of the host vehicle's accelerator pedal. The vehicle state sensors 8 include a brake stroke sensor that detects the amount of depression of the host vehicle's brake pedal. The vehicle state sensors 8 output their detection results to the in-vehicle LAN. The detection results of the vehicle state sensors 8 may also be configured to be output to the in-vehicle LAN via an ECU installed in the host vehicle.

The HMI system 2 includes an HCU (Human Machine Interface Control Unit) 20, an in-vehicle environment sensor 21, a biosensor 22, a respiratory induction device 23, and an operation device 24. The HMI system 2 accepts input operations from the driver. The HMI system 2 monitors the driver's condition. The HMI system 2 presents information and stimuli to the driver.

The interior environment sensors 21 are a group of sensors used to detect the state of the interior environment of the vehicle. The interior environment sensors 21 include a microphone that collects sounds inside the vehicle cabin. The interior environment sensors 21 include an illuminance sensor that detects the brightness inside the vehicle cabin. The interior environment sensors 21 include a vibration sensor that detects the degree of shaking inside the vehicle cabin.

The biosensor 22 measures the driver's biometric information. The biosensor 22 sequentially outputs the measured biometric information to the HCU 20. The biosensor 22 may be installed in the vehicle. In this case, the biosensor 22 may be installed on the steering wheel, driver's seat, etc. The biosensor 22 may also be installed in a wearable device worn by the driver. In this case, the HCU 20 may acquire the measurement results of the biosensor 22 via, for example, short-range wireless communication. Examples of biometric information measured by the biosensor 22 include respiration, pulse rate, heart rate, etc.

Examples of the biosensor 22 include pulse wave sensors such as photoelectric pulse wave sensors and impedance pulse wave sensors that measure heart rate or pulse rate from the waveform of the pulse wave obtained by measurement. Other examples include breathing sensors that detect breathing movements non-contactly using a Doppler sensor that uses microwaves in the GHz band. The breathing sensor may also be a pressure sensor attached to a seat belt or seat back. Furthermore, when estimating breathing from pulse waves, a pulse wave sensor may also be used as the breathing sensor. Note that the biosensor 22 is not limited to those listed here, and other sensors may also be used. Furthermore, the biosensor 22 may be configured to measure biometric information other than breathing, pulse, and heart rate. Examples include sensors that measure brain waves, heart rate fluctuations, sweating, body temperature, blood pressure, and skin conductance.

The breathing induction device 23 stimulates the driver's sensory organs to induce breathing. The breathing induction device 23 may induce breathing by stimulating any of the driver's vision, smell, touch, or hearing. The breathing induction device 23 may induce breathing by combining any of the driver's vision, smell, touch, and hearing. The breathing induction device 23 may induce breathing by presenting stimuli to make the driver aware of the target breathing timing. Alternatively, the breathing induction device 23 may induce breathing by presenting stimuli to make the driver breathe unconsciously. A visual stimulus is called a visual stimulus. A olfactory stimulus is called an olfactory stimulus. A tactile stimulus is called a tactile stimulus. A hearing stimulus is called an auditory stimulus.

An example of a visual stimulus is the light emitted by a light-emitting device such as an LED. Another example of a visual stimulus is the display of a video or other display device. The light emission and display should be located in a position visible to the driver. An example of an olfactory stimulus is the emission of an odorous component from an aroma unit or the like. The odorous component may be emitted from the front or side of the driver. Note that the aroma unit may be used in combination with an air conditioning unit, so that the odorous component is emitted by the air blown from the air conditioning unit. An example of a tactile stimulus is pressure from the driver's seat back. Pressure can be generated by expanding and contracting a bag embedded in the seat back using air pressure. Another example of a tactile stimulus is the blowing of air from an air conditioning unit. The air from the air conditioning unit should be blown from an outlet facing the driver. Further examples of tactile stimuli include vibrations generated by a vibrator and fastening a seat belt. The vibrator may be attached to a member that comes into contact with the driver, such as the steering wheel, the driver's seat back, or the seat surface of the driver's seat. An example of an auditory stimulus is the output of music or environmental sounds from an audio output device. Another example of an auditory stimulus is the output of a beep from a buzzer.

The operation device 24 is a group of switches operated by the driver. For example, the operation device 24 may be a steering switch provided on the spoke of the steering wheel of the vehicle. The operation device 24 may also be a touch switch integrated with a display.

The HCU 20 is primarily composed of a microcomputer equipped with a processor, memory, I/O, and a bus connecting these. The HCU 20 executes control programs stored in the memory to perform various processes, such as processes related to guiding the driver's psychological state (hereinafter referred to as psychological state induction-related processes). The memory referred to here is a non-transitive tangible storage medium that non-temporarily stores computer-readable programs and data. The non-transitive tangible storage medium is realized by semiconductor memory, a magnetic disk, or the like. Details of the psychological state induction-related processes in the HCU 20 will be discussed later.

<General configuration of HCU 20>
Next, the schematic configuration of the HCU 20 will be described with reference to FIG. 2 . The HCU 20 includes, as functional blocks, an environmental state identification unit 201, a driving load estimation unit 202, a driver state identification unit 203, an implementation determination unit 204, a rhythm determination unit 205, a respiratory induction control unit 206, and a target presence/absence determination unit 207 for psychological state induction-related processing. The HCU 20 corresponds to a psychological state induction device. The execution of processing by each functional block of the HCU 20 by a computer corresponds to the execution of a psychological state induction method. Some or all of the functions executed by the HCU 20 may be configured as hardware using one or more ICs or the like. Some or all of the functional blocks included in the HCU 20 may be realized by a combination of software executed by a processor and hardware components.

The environmental condition identification unit 201 identifies the environmental conditions inside and outside the vehicle. The environmental condition identification unit 201 may identify the surrounding environment recognized by the driving assistance ECU 7 as the environmental condition outside the vehicle. The following are examples of identifying the environmental condition outside the vehicle regarding the surrounding environment. The environmental condition identification unit 201 may identify traffic congestion from traffic information received by the communication device 3. The environmental condition identification unit 201 may identify the weather from weather information received by the communication device 3. The environmental condition identification unit 201 may identify the brightness outside the vehicle from the solar radiation detected by the solar radiation sensor. The environmental condition identification unit 201 may identify the environment inside the vehicle from the detection results of the vehicle interior environment sensor 21. The following are examples of identifying the environmental condition inside the vehicle. The environmental condition identification unit 201 may identify the volume of sound inside the vehicle from sound collected by a microphone. The environmental condition identification unit 201 may identify the brightness inside the vehicle from the illuminance detected by an illuminance sensor. The environmental condition determination unit 201 can determine the degree of shaking inside the vehicle from the degree of shaking detected by the vibration sensor.

The driving load estimation unit 202 estimates the driving load of the vehicle. The driving load estimation unit 202 may estimate the level of the driving load of the vehicle from the environmental conditions outside the vehicle identified by the environmental condition identification unit 201. As an example, the driving load estimation unit 202 may estimate a high load when the number of vehicles around the vehicle is equal to or greater than a threshold. The driving load estimation unit 202 may estimate a high load when a bicycle or pedestrian is present in the path of the vehicle. The driving load estimation unit 202 may estimate a high load when the vehicle is traveling on a highway. The driving load estimation unit 202 may estimate a high driving load when the vehicle is traveling on a curved road. The driving load estimation unit 202 may estimate a low load when the situation is not one in which there is a high possibility of sudden driving operations being required, as described above.

The driving load estimation unit 202 may also estimate the level of the driving load of the vehicle based on the detection results of the vehicle state sensor 8. In this case, the driving load estimation unit 202 may estimate the level of the driving load based on the complexity of the driver's driving operations. The complexity of the driver's driving operations may be determined by changes in operation information of the accelerator pedal, brake pedal, and steering wheel of the vehicle. For example, the driving load estimation unit 202 may estimate a high load when the amount of change per unit time of the value detected by the accelerator position sensor is equal to or greater than a threshold. The driving load estimation unit 202 may also estimate a high load when the amount of change per unit time of the value detected by the brake stroke sensor is equal to or greater than a threshold. The driving load estimation unit 202 may also estimate a high load when the amount of change per unit time of the value detected by the steering angle sensor is equal to or greater than a threshold. The driving load estimation unit 202 may also estimate a high load when the amount of change per unit time of the value detected by the vehicle speed sensor is equal to or greater than a threshold.

The driver state identification unit 203 identifies the driver's state. The driver state identification unit 203 has a psychological state identification unit 231 and a heart rate identification unit 232. The psychological state identification unit 231 identifies the driver's psychological state. The psychological state identification unit 231 may identify the driver's psychological state from the sensing results of the biosensor 22. As an example, the psychological state identification unit 231 identifies psychological states such as an "anger state," a "tension state," a "relaxed state," a "mindless (bored) state," and a "concentrated state." The "anger state," "tension state," and "concentrated state" are all states in which the active state tends to be more active than the inactive state. The "anger state" and "tension state" are states in which the unpleasant state tends to be more unpleasant than the pleasant state. The "concentrated state" is a state in which the unpleasant state tends to be less unpleasant than the pleasant state. The "relaxed state" and "mindless state" are both states in which the inactive state tends to be more inactive than the pleasant state. The "relaxed state" is a state in which the pleasant state tends to be more pleasant than the pleasant state. The "inattentive state" is a state in which the unpleasant side of pleasure and unpleasantness is more prevalent. To understand this psychological state, we can refer to Russell's circular model, for example.

The psychological state identification unit 231 may identify the driver's psychological state from the sensing results of the biometric sensor 22, based on the feature amounts of biometric information for each psychological state. These feature amounts may include the heart rate identified by the heart rate identification unit 232. The feature amounts of biometric information for each psychological state may be determined in advance through experiments or the like and stored in the non-volatile memory of the HCU 20. The feature amounts of biometric information for each psychological state may also be determined through machine learning. Note that the biometric information used to identify the psychological state by the psychological state identification unit 231 may be an image of the driver's face (hereinafter referred to as a facial image). In this case, the biometric sensor 22 is a camera.

The psychological state identification unit 231 may identify the driver's psychological state from information about the driver input via the operation device 24. This information may be a response to a medical interview to estimate the driver's psychological state, or information declaring the driver's psychological state.

The implementation determination unit 204 determines whether or not to implement respiratory guidance. The implementation determination unit 204 determines whether or not to implement respiratory guidance using the respiratory guidance device 23. The implementation determination unit 204 may determine whether or not to implement respiratory guidance using the respiratory guidance device 23 depending on the psychological state of the driver identified by the psychological state identification unit 231. As an example, if the driver's psychological state deviates from a target psychological state (hereinafter referred to as the target state), it may determine that respiratory guidance should be implemented. On the other hand, if the driver's psychological state corresponds to the target psychological state, it may determine that respiratory guidance should not be implemented. More specifically, if the driver's psychological state deviates from the target state in the direction of activation or deactivation, it may determine that respiratory guidance should be implemented. For example, if the target state is a "concentration state," it may determine that respiratory guidance should be implemented in the case of a "distracted state." On the other hand, if the driver's psychological state is a "concentration state," it may determine that respiratory guidance should not be implemented. Furthermore, if the target state is a "relaxed state," it may determine that respiratory guidance should be implemented in the cases of an "anger state" or a "tension state." On the other hand, if the driver's psychological state is "relaxed," it can be determined that breathing guidance should not be implemented. This makes it possible to avoid implementing breathing guidance if the driver's psychological state is not deviating from the target state.

The target state may be set in advance as a default. In this case, a psychological state estimated to be suitable for driving may be set as the target state. The target state may be set according to the psychological state of the driver. For example, if the driver's psychological state is "angry" or "tense," the target state may be set to "relaxed." Alternatively, if the driver's psychological state is "absentminded," the target state may be set to "concentrated." The target state may be set by the driver via the operation device 24. The target state may be determined appropriately by the vehicle's system.

The implementation determination unit 204 may determine whether or not to implement respiratory induction by the respiratory induction device 23, depending on input received from the driver via the operation device 24. The implementation determination unit 204 may determine to implement respiratory induction when receiving input via the operation device 24 instructing to implement respiratory induction. On the other hand, the implementation determination unit 204 may determine not to implement respiratory induction when receiving input via the operation device 24 instructing to pause respiratory induction. This makes it possible to start and pause respiratory induction by the respiratory induction device 23 at the timing desired by the driver.

The rhythm determination unit 205 determines a target breathing rhythm for changing the driver's psychological state to the target state. This processing by the rhythm determination unit 205 corresponds to the rhythm determination step. The rhythm determination unit 205 determines an inhalation period and an exhalation period as the target breathing rhythm. The inhalation period is the period during which the driver inhales. In other words, it is the period during which inhalation occurs. The exhalation period is the period during which the driver exhales. In other words, it is the period during which exhalation occurs. The rhythm determination unit 205 performs processing when the implementation determination unit 204 determines that respiratory guidance should be implemented.

The rhythm determination unit 205 may determine a target breathing rhythm according to the target state. For example, if the target state is a "relaxed state," the target breathing rhythm may be set to lengthen the expiratory period relative to the inhalation period. This will give dominance to the parasympathetic nervous system, leading to a "relaxed state." "Lengthening the expiratory period relative to the inhalation period" may mean lengthening the expiratory period relative to the inhalation period. "Lengthening the expiratory period relative to the inhalation period" may mean lengthening the expiratory period relative to the inhalation period relative to a normal driver. Furthermore, if the target state is a "concentrated state," the target breathing rhythm may be set to shorten the expiratory period relative to the inhalation period. This will give dominance to the sympathetic nervous system, leading to a "concentrated state." "Shortening the expiratory period relative to the inhalation period" may mean shortening the expiratory period relative to the inhalation period. "Shortening the expiratory period relative to the inhalation period" may mean shortening the expiratory period relative to the inhalation period relative to a normal driver. This makes it possible to determine a target breathing rhythm that is easy to induce for each target state. Note that the normal inhalation period and exhalation period can be determined from the driver's inhalation period and exhalation period measured when breathing induction is not being performed by the breathing induction device 23. The inhalation period and exhalation period can be measured using the biosensor 22.

The breathing induction control unit 206 controls stimuli (hereinafter referred to as induction stimuli) to induce the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit 205. The breathing induction control unit 206 controls the induction stimuli by controlling the breathing induction device 23. The processing by this breathing induction control unit 206 corresponds to the breathing induction control process.

The respiratory guidance control unit 206 assigns two patterns of continuous stimulus changes with different directions for the same type of stimulus to the inhalation period and the exhalation period, respectively. These stimuli are called first stimuli. Examples of the first stimuli that can be used include tactile, auditory, and visual stimuli. The first stimuli switch the pattern of continuous stimulus changes, making it easier to understand the timing of the switch between the inhalation period and the exhalation period.

The tactile stimulus that corresponds to the first stimulus is a pressure applied to the driver's back and lower back, varying in strength. This tactile stimulus can be achieved by applying pressure from the seatback of the driver's seat. In this case, during the inhalation period, the pressure applied to the lower back can be gradually increased. This will straighten the driver's spine and expand the thorax, encouraging the driver to inhale. During the exhalation period, the pressure applied to the lower back can be gradually decreased. This will relax the driver and encourage the driver to exhale.

The tactile stimulus corresponding to the first stimulus may be the strength of the pressure on the driver's seat surface. The tactile stimulus corresponding to the first stimulus may be the strength of the vibration of the driver's seat. The part of the seat where the vibration occurs may be the seat back or the seat surface. The tactile stimulus corresponding to the first stimulus may be a change in the position of the vibration of the driver's seat. The change in the position of the vibration can be in two patterns: upward or downward. The change in the position of the vibration can be in two patterns: rightward or leftward. The change in the position of the vibration can be in two patterns: concentrated or diffused. To enable the change in the position of the vibration, multiple vibrators can be used. The tactile stimulus corresponding to the first stimulus may be a change in the length of the vibration period of the driver's seat. In addition to seat vibration, the vibration may also be vibration of the steering wheel. Similar to the seat vibration, two patterns of stimulation are possible for the steering wheel vibration. The tactile stimulus corresponding to the first stimulus may be retracting and retracting the driver's seat belt. This tactile stimulus may be realized by a motor that retracts and retracts the seat belt. The tactile stimulus that constitutes the first stimulus may be a combination of these. Furthermore, the tactile stimulus that constitutes the first stimulus may be any other stimulus, as long as it is two patterns of continuous stimulus changes with different directions for the same type of stimulus. The correspondence between the two patterns of continuous tactile stimulus changes with different directions and the inhalation period and exhalation period may be set arbitrarily.

The auditory stimulus that corresponds to the first stimulus is an increase or decrease in volume. The auditory stimulus that corresponds to the first stimulus is the distance of a sound image. The auditory stimulus may be realized by sound output. The distance of a sound image may be realized by using multiple speakers. It is preferable that the auditory stimulus that corresponds to the first stimulus is a combination of an increase or decrease in volume and the distance of a sound image. In this case, during the inhalation period, the volume may be gradually increased and the sound image may be moved closer to the driver's seat. This gives the driver the feeling that he or she is surrounded by sound, encouraging the driver to inhale. During the exhalation period, the volume may be gradually decreased and the sound image may be moved farther away from the driver's seat. This gives the driver the feeling that the sound is receding, encouraging the driver to exhale. The sound may be music, environmental sound, or a beep. Alternatively, these may be combined.

The auditory stimulus that corresponds to the first stimulus may be a change in pitch. The auditory stimulus that corresponds to the first stimulus may be a change in rhythm of sound. The auditory stimulus that corresponds to the first stimulus may be a combination of these. Furthermore, the auditory stimulus that corresponds to the first stimulus may be any other stimulus as long as it is two patterns of continuous stimulus changes with different directions for the same type of stimulus. The correspondence between the two patterns of continuous auditory stimulus changes with different directions and the inhalation period and exhalation period may be set arbitrarily.

The visual stimulus that corresponds to the first stimulus is an increase or decrease in the brightness of the light emitted. In this case, the brightness can be gradually increased during the inhalation period. This gives the driver the feeling that they are enveloped in light, encouraging the driver to inhale. The brightness can be gradually decreased during the exhalation period. This gives the driver the feeling that the light is receding, encouraging the driver to exhale. The visual stimulus that corresponds to the first stimulus may also be an increase or decrease in the brightness of the image.

The visual stimulus corresponding to the first stimulus may be a change in the hue of the light emitted. One example is a change between warm and cool colors. Another example is a change between colored and colorless. The visual stimulus corresponding to the first stimulus may be the distance between the light-emitting position. The distance between the light-emitting position may be achieved by using multiple light-emitting devices. In this case, during the inhalation period, the light-emitting position may be gradually moved closer to the driver's seat. This gives the driver the feeling that the light is approaching, encouraging the driver to inhale. During the exhalation period, the light-emitting position may be gradually moved away from the driver's seat. This gives the driver the feeling that the light is receding, encouraging the driver to exhale. The visual stimulus corresponding to the first stimulus may be the size of the range of the light emitted. The size of the range of the light emitted may be achieved by using multiple light-emitting devices. In this case, during the inhalation period, the light-emitting range may be gradually expanded. This gives the driver the feeling that they are enveloped in light, encouraging the driver to inhale. During the exhalation period, the light-emitting range may be gradually narrowed. This gives the driver the sensation of a receding light, encouraging the driver to exhale. The visual stimulus serving as the first stimulus may be a combination of these. The visual stimulus serving as the first stimulus may also be any other stimulus, as long as it is two patterns of continuous stimulus changes with different directions for the same type of stimulus. The correspondence between the two patterns of continuous visual stimulus changes with different directions and the inhalation period and exhalation period may be set arbitrarily.

The first stimulus may be a combination of tactile, auditory, and visual stimuli. In this embodiment, a case where tactile, auditory, and visual stimuli are used in combination will be described as an example. The tactile stimulus is the strength of pressure on the back. The auditory stimulus is the increase or decrease in volume and the distance of the sound image. The visual stimulus is the size of the range of light emitted. In this example, two types of stimuli are used as auditory stimuli: the increase or decrease in volume and the distance of the sound image. With the above configuration, the driver is given the sensation of being enveloped in light along with the sound, which encourages the driver to inhale. The driver is also given the sensation of the light receding along with the sound, which encourages the driver to exhale.

The first stimulus will now be described using Figure 3. For convenience, Figure 3 uses the strength of pressure on the back as an example of the first stimulus. As shown in Figure 3, during the inhalation period, the tactile stimulus is continuously changed so that the pressure on the back gradually increases. On the other hand, during the exhalation period, the tactile stimulus is continuously changed so that the pressure on the back gradually decreases. When combining multiple types of stimuli as the first stimulus, the respiratory guidance control unit 206 matches the timing at which the direction of change in the stimulus changes across the multiple types of stimuli.

It is preferable that the respiratory guidance control unit 206 assigns two patterns of continuous stimulus changes in opposite directions to the inhalation period and exhalation period as the first stimulus for the same type of stimulus. This makes it easier to understand the change in the stimulus patterns assigned to the inhalation period and exhalation period. The change in strength of the pressure on the back shown in Figure 3 corresponds to two patterns of continuous stimulus changes in opposite directions. Examples of stimulus changes in opposite directions include strength and weakness, increase and decrease, enlargement and reduction, and distance.

The breathing induction control unit 206 preferably applies two patterns of continuous stimulus changes with different directions that are estimated to more easily evoke the driver's inhalation and exhalation, respectively. This makes it easier to induce the driver's inhalation and exhalation. As a result, it becomes possible to more naturally synchronize breathing with the target breathing rhythm. It is estimated that the changes in the strength of the pressure on the back shown in Figure 3 will more easily evoke the driver's inhalation and exhalation, respectively. It is also estimated that increasing and decreasing the volume and the distance of the sound image will more easily evoke the driver's inhalation and exhalation, respectively. It is also estimated that increasing and decreasing the brightness of the light emission and expanding and contracting the range will more easily evoke the driver's inhalation and exhalation, respectively.

In addition to the first stimulus, the breathing induction control unit 206 also generates an intermittent stimulus at regular intervals. This stimulus is called the second stimulus. The second stimulus may be, for example, a tactile stimulus, an auditory stimulus, or a visual stimulus. The first stimulus and the second stimulus are different types of stimuli. By adding the second stimulus to the first stimulus, the driver can more easily predict the timing of the switch between the inhalation period and the exhalation period by relying on the second stimulus. This is because the second stimulus is an intermittent stimulus at regular intervals, and therefore, by combining it with the first stimulus, it becomes easier to measure the timing. As a result, when the driver's breathing timing is guided by continuously changing stimuli, the driver can more easily predict the timing of the switch between inhalation and exhalation. The intensity of the second stimulus may or may not be constant.

The tactile stimulus corresponding to the second stimulus may be vibration of the driver's seat. The part of the seat that generates the vibration may be the seat back or the seat surface. This tactile stimulus may be realized by a vibrator provided in the driver's seat. The tactile stimulus corresponding to the second stimulus may be vibration of the steering wheel. This tactile stimulus may be realized by a vibrator provided in the steering wheel. The tactile stimulus corresponding to the second stimulus may be vibration of the floor of the vehicle. This tactile stimulus may be realized by a vibrator provided on the floor of the vehicle. The tactile stimulus corresponding to the second stimulus may be repeated winding and unwinding of the driver's seat belt. This tactile stimulus may be realized by a motor that winds and unwinds the seat belt.

The second stimulus, which is an auditory stimulus, is the output of sound at regular intervals. Sounds that can be used include beeps, beats, and environmental sounds at regular intervals. Sounds that mimic heartbeats may also be used. The second stimulus, which is a visual stimulus, is a flashing light.

The second stimulus may be a combination of tactile, auditory, and visual stimuli. In this embodiment, an example in which a beat sound is used as the second stimulus will be described. The second stimulus will be described using Figure 3. In Figure 3, a beat sound is used as an example of the second stimulus. As shown in Figure 3, the second stimulus involves outputting a sound intermittently at regular intervals. In the example of Figure 3, the volume of the sound is constant when it is output.

Here, we will use Figure 4 to explain the actual effect of respiratory guidance when a second stimulus is added to the first stimulus. Figure 4 shows the results of a test to evaluate the ease of timing the switch between inhalation and exhalation when respiratory guidance is performed by adding a second stimulus to the first stimulus. For comparison, Figure 4 also uses the results of the ease of timing when respiratory guidance is performed using only the first stimulus. Ten participants participated in the test. Five combinations of inhalation and exhalation periods were used. The first combination was a 2.5-second inhalation period and a 5-second exhalation period. The second combination was a 3-second inhalation period and a 6-second exhalation period. The third combination was a 3.5-second inhalation period and a 7-second exhalation period. The fourth combination was a 24-second inhalation period and an 8-second exhalation period. The fifth combination was a 4.5-second inhalation period and an 8-second exhalation period. The ease of timing was evaluated by the test participants on a 7-point scale from 1 to 8. As shown in Figure 4, adding a second stimulus to the first stimulus makes it significantly easier to synchronize the timing compared to using only the first stimulus. It has also been verified separately that adding a second stimulus to the first stimulus makes it easier to synchronize the timing compared to breathing guidance using a single voice guide. The single voice guide consists of utterances such as "inhale" and "exhale."

It is preferable that the respiratory induction control unit 206 coincides the timing of the presentation of the second stimulus with the timing of the switch between the inhalation period and the exhalation period. An example is shown in Figure 3. This makes it easier to predict the timing of the next switch between inhalation and exhalation. As a result, it becomes easier for the driver to adjust their breathing to match the target breathing rhythm. In this case, the respiratory induction control unit 206 sets the cycle of the second stimulus so that the timing of the presentation of the second stimulus coincides with the timing of the switch between the inhalation period and the exhalation period.

The respiratory induction control unit 206 preferably sets the period of the constant intermittent stimulation of the second stimulus to the same period as the period of the driver's heartbeat. The respiratory induction control unit 206 can achieve this based on the heartbeat identified by the heartbeat identification unit 232. For example, if the heartbeat rate is 60 beats per minute, the stimulation period can also be set to 60 beats per minute. The "same period" referred to here may include an error range that can be considered approximately the same. In this way, the rhythm of the second stimulus becomes the same as the driver's heartbeat. This increases the driver's acceptance of the second stimulus. As a result, the driver is less likely to be distracted by the second stimulus. Hereinafter, the period of the constant intermittent stimulation of the second stimulus will be referred to as the "second stimulus period."

When the target state is an "awake state," the respiratory induction control unit 206 preferably sets the second stimulation period to a period shorter than the period of the driver's heartbeat. The respiratory induction control unit 206 may achieve this based on the heartbeat identified by the heartbeat identification unit 232. The case where the target state is an "awake state" can be rephrased as the case where the target respiratory rhythm targets an "awake state." By providing stimuli with a period shorter than the driver's heartbeat, the psychological state is induced toward an active state. Therefore, with the above configuration, induction into an "awake state" is made easier. On the other hand, when the target state is a "relaxed state," the respiratory induction control unit 206 preferably sets the second stimulation period to a period longer than the period of the driver's heartbeat. The respiratory induction control unit 206 may achieve this based on the heartbeat identified by the heartbeat identification unit 232. The case where the target state is a "relaxed state" can be rephrased as the case where the target respiratory rhythm targets a "relaxed state." By providing stimuli with a longer cycle than the driver's heartbeat, the driver's psychological state is induced to become more inactive. Therefore, with the above configuration, it becomes easier to induce a "relaxed state."

Presenting visual stimuli to the driver may cause distraction to the driver. Therefore, the breathing induction control unit 206 may avoid using visual stimuli as the first and second stimuli when the host vehicle is moving. On the other hand, the breathing induction control unit 206 may use visual stimuli as the first and second stimuli when the host vehicle is stopped. Verification has confirmed that the driver can receive breathing induction more comfortably if visual stimuli are not provided while the vehicle is moving. On the other hand, verification has confirmed that the driver can receive breathing induction more comfortably if visual stimuli are provided while the vehicle is stopped. Therefore, with the above configuration, it is possible to enable the driver to receive breathing induction in a comfortable manner depending on whether the host vehicle is moving or stopped.

The breathing guidance control unit 206 may also be configured to weaken the intensity of the visual stimulation when the vehicle is moving compared to when the vehicle is stopped. This configuration also makes it possible to reduce distraction to the driver while the vehicle is moving.

It is preferable that the respiratory guidance control unit 206 applies a third stimulus, which is a different type of stimulus from the first and second stimuli, at the timing of switching between the inhalation period and the exhalation period. This makes it easier to understand the timing of switching between inhalation and exhalation. The third stimulus can be, for example, an auditory stimulus or an olfactory stimulus.

The auditory stimulus corresponding to the third stimulus is the output of a sound that imitates the sound of air escaping (hereinafter referred to as "escaping sound"). This sound can be output when the inhalation period switches to the exhalation period. This makes it easier for the driver to intuitively recognize the timing when the inhalation period switches to the exhalation period. The olfactory stimulus corresponding to the third stimulus is the emission of an odor component. The odor component can be an aromatic (i.e., a pleasant smell). The odor component can be generated when the exhalation period switches to the inhalation period. This will cause the driver to inhale air at the timing when the inhalation period switches to the inhalation period in order to smell the odor. It is preferable that the odor component be an odor component that corresponds to the target state. For example, if the target state is a "relaxed state," an odor component with a relaxing effect, such as cedrol, can be used.

The third stimulus may be a combination of an auditory stimulus and an olfactory stimulus. The third stimulus may be either an auditory stimulus or an olfactory stimulus alone. Here, the third stimulus will be explained using Figure 5. In Figure 5, the third stimulus will be explained using the output of a drop sound as an example. As shown in Figure 5, the drop sound as the third stimulus is output at the timing when the inhalation period switches to the exhalation period. At the timing when the exhalation period switches to the inhalation period, an aromatic odor component may be output.

When the driving load estimation unit 202 estimates that the driving load is high, it is preferable that the respiratory guidance control unit 206 weaken the intensity of the stimulus to the driver compared to when the driving load is estimated to be low. When the driving load is high, the cognitive load of respiratory guidance may have a significant impact on the driver's driving. In contrast, with the above configuration, when the driving load is high, the cognitive load of respiratory guidance can be reduced. As a result, it is possible to perform respiratory guidance with reduced impact on driving. The stimuli to be weakened in intensity may be all or some of the first stimulus, second stimulus, and third stimulus. A configuration may be adopted in which the stimuli that can be weakened in intensity out of the first stimulus, second stimulus, and third stimulus are weakened. Note that weakening the intensity of the odor component may mean lowering the concentration of the odor component.

Here, using Figure 6, we will explain the stimulation when the driving load is high. Figure 6 will be explained using the example of Figure 3 as a comparison. Of the lines representing changes in stimulation intensity in Figure 6, the dashed line represents the stimulation when the load is low. This change in stimulation intensity when the load is low corresponds to the change in stimulation intensity shown in Figure 3. Of the lines representing changes in stimulation intensity in Figure 6, the solid line represents the change in stimulation intensity when the load is high. As shown in Figure 6, when the load is high, the respiratory guidance control unit 206 weakens the intensity of both the first and second stimulations compared to when the load is low. Although Figure 6 does not mention the third stimulation, if the third stimulation is also performed, the same can be done for the third stimulation.

The target presence/absence determination unit 207 determines the presence or absence of a stimulus (hereinafter referred to as a target stimulus) that is caused by a large environmental noise among the stimuli controlled by the breathing guidance control unit 206. The target presence/absence determination unit 207 determines the presence or absence of a target stimulus based on the environmental state identified by the environmental state identification unit 201. As an example, if the volume of sound collected by the microphone is equal to or greater than a threshold, it may be determined that a target stimulus corresponding to sound is present. If the brightness detected by the sunlight sensor or illuminance sensor is equal to or greater than a threshold, it may be determined that a target stimulus corresponding to light or display is present. If the degree of shaking detected by the vibration sensor is equal to or greater than a threshold, it may be determined that a target stimulus corresponding to vibration is present.

When the target presence/absence determination unit 207 determines that a target stimulus is present, the breathing induction control unit 206 preferably increases the intensity of the target stimulus. For example, if it determines that a sound target stimulus is present, the volume of the sound can be increased. If it determines that a light or display target stimulus is present, the brightness of the light or display can be increased. If it determines that a vibration target stimulus is present, the vibration can be increased. This makes it possible to prevent the driver from having difficulty perceiving the induction stimulus.

Here, using Figure 7, we will explain the stimulation when the intensity of the target stimulus is increased. Of the lines representing changes in stimulus intensity in Figure 7, the dashed dotted line represents the change in intensity of the target stimulus. Of the lines representing changes in stimulus intensity in Figure 7, the solid line represents the change in intensity of stimuli other than the target stimulus. If a stimulus that corresponds to the target stimulus does not correspond to the target stimulus, it will also exhibit the change in intensity shown by the solid line. As shown in Figure 7, the respiratory guidance control unit 206 increases the intensity of the target stimulus compared to when it does not correspond to the target stimulus.

Furthermore, when the breathing induction control unit 206 determines that a target stimulus is present, it may increase the intensity of stimuli other than the target stimulus among the stimuli controlled by the breathing induction control unit 206. For example, when it determines that a target stimulus corresponding to sound is present, the brightness of the light or display may be increased, or the vibration may be strengthened. When it determines that a target stimulus corresponding to light or display is present, the volume of the sound may be increased, or the vibration may be strengthened. When it determines that a target stimulus corresponding to vibration is present, the brightness of the light or display may be increased, or the volume of the sound may be strengthened. In this way, the stimuli complement each other, making it possible to prevent the driver from having difficulty perceiving the induction stimulus.

<Psychological state induction related processing in HCU 20>
Next, an example of the flow of the psychological state induction-related processing in the HCU 20 will be described using the flowchart of Figure 8. The flowchart of Figure 8 may be configured to start, for example, when the power switch of the vehicle is turned on. The power switch is a switch for starting the internal combustion engine or motor generator of the vehicle. When the power switch is turned on, the power of the HCU 20 may also be turned on. Another condition may be that a function for executing the psychological state induction-related processing is set to on via the operation device 24.

First, in step S1, identification of various conditions begins. In S1, the environmental condition identification unit 201 begins identifying the environmental condition of the vehicle. In S1, the driver condition identification unit 203 begins identifying the driver's condition. This driver's condition also includes heart rate. In step S2, the implementation determination unit 204 determines whether or not to implement respiratory guidance. If it is determined that respiratory guidance should be implemented (YES in S2), the process proceeds to step S3. On the other hand, if it is determined that respiratory guidance should not be implemented (NO in S2), the process proceeds to step S11.

In step S3, the rhythm determination unit 205 determines a target breathing rhythm for changing the driver's psychological state to the target state. In step S4, the respiratory induction control unit 206 sets the second stimulation period to the same period as the driver's heartbeat. In S4, this setting can be made based on the heartbeat identified in S1.

In step S5, the respiratory induction control unit 206 resets the second stimulation period, if necessary, depending on the target state. In S5, if the target state is an "awake state," the second stimulation period is reset to a period shorter than the driver's heartbeat period. In S5, if the target state is a "relaxed state," the second stimulation period is reset to a period longer than the driver's heartbeat period.

In step S6, the respiratory induction control unit 206 sets the intensity of the induction stimulus according to the driving state of the vehicle. In S6, when the vehicle is driving, the intensity of the visual stimulus is set to be weaker than when the vehicle is stopped. In S6, when the vehicle is driving, a setting may be made to not provide visual stimulation. If the rhythm determination unit 205 has not determined an induction stimulus including a visual stimulus, S6 may be omitted. Note that when the target presence/absence determination unit 207 determines that a target stimulus is present, the respiratory induction control unit 206 may set the intensity of the target stimulus to be increased. Furthermore, when the respiratory induction control unit 206 determines that a target stimulus is present, the respiratory induction control unit 206 may set the intensity of stimuli other than the target stimulus to be controlled by the target respiratory rhythm to be increased.

In step S7, the breathing induction control unit 206 begins controlling the breathing induction device 23 so that the driver breathes in accordance with the target breathing rhythm determined in S3. In S7, the induction stimulus is controlled according to the settings in S3 to S6.

In step S8, if the timing for implementing breathing guidance has ended (YES in S8), the process proceeds to step S10. As an example, the timing for implementing breathing guidance ends when the psychological state of the driver identified by the psychological state identification unit 231 reaches the target state. On the other hand, if the timing for implementing breathing guidance has not ended (NO in S8), the process proceeds to step S9.

In step S9, if it is time to end the psychological state induction-related processing (YES in S9), the breathing induction control unit 206 ends breathing induction. Then, the psychological state induction-related processing ends. On the other hand, if it is not time to end the psychological state induction-related processing (NO in S9), the process returns to S6 and repeats. An example of when the psychological state induction-related processing ends is when the power switch of the vehicle is turned off. Another example of when the psychological state induction-related processing ends is when the function that executes the psychological state induction-related processing is switched off.

In step S10, the breathing induction control unit 206 pauses breathing induction. In step S11, if it is time to end the psychological state induction-related processing (YES in S11), the psychological state induction-related processing ends. On the other hand, if it is not time to end the psychological state induction-related processing (NO in S11), the process returns to S2 and repeats.

(Embodiment 2)
The configuration of the driving assistance system 1 of the second embodiment is not limited to the configuration of the first embodiment, and may be the configuration of the following second embodiment. An example of the configuration of the second embodiment will be described below with reference to the drawings. The driving assistance system 1 of the second embodiment is similar to the driving assistance system 1 of the first embodiment, except that the driving assistance system 1 includes an HCU 20a instead of the HCU 20.

Here, the general configuration of the HCU 20a will be explained using Figure 9. With regard to psychological state induction-related processing, the HCU 20a has the following functional blocks: an environmental state identification unit 201, a driving load estimation unit 202, a driver state identification unit 203, an implementation determination unit 204, a rhythm determination unit 205, a respiratory induction control unit 206a, and a target presence/absence determination unit 207. The HCU 20a is similar to the HCU 20 of embodiment 1, except that it has a respiratory induction control unit 206a instead of the respiratory induction control unit 206. This HCU 20a also corresponds to a psychological state induction device. Furthermore, the execution of processing by each functional block of the HCU 20a by a computer also corresponds to the execution of a psychological state induction method.

The respiratory induction control unit 206a is similar to the respiratory induction control unit 206, except for some differences in processing. The respiratory induction control unit 206a sets the second stimulation period to a period within a predetermined range starting from a period of 60 beats per minute (hereinafter referred to as a heartbeat-like period). The respiratory induction control unit 206a does not set the second stimulation period based on the heartbeat identified by the heartbeat identification unit 232. The predetermined range referred to here may be an average range for a person's heartbeat during normal times. This range may be set in advance through experiments, etc. For example, normal times may be a state in which both activity/inactivity and comfort/discomfort are intermediate in Russell's circular model. The heartbeat-like period is a period estimated to be the period of a person's heartbeat during normal times. For example, the heartbeat-like period may be set to a period of 60 to 80 beats per minute. As an example, a period of 75 beats per minute may be set.

When the target state is an "awake state," the respiratory induction control unit 206a preferably sets the second stimulation period to a period shorter than the heartbeat-like period. By providing stimulation with a period shorter than the heartbeat pulsation estimated to be a person's normal heartbeat, the driver's psychological state is more likely to be induced toward an active state. Therefore, with the above configuration, it is easier to induce the driver into an "awake state." On the other hand, when the target state is a "relaxed state," the respiratory induction control unit 206 preferably sets the second stimulation period to a period longer than the heartbeat-like period. By providing stimulation with a period longer than the heartbeat pulsation estimated to be a person's normal heartbeat, the driver's psychological state is more likely to be induced toward an inactive state. Therefore, with the above configuration, it is easier to induce the driver into a "relaxed state."

(Embodiment 3)
In the above-described embodiment, the psychological state induction-related processing is performed by the HCU 20, 20a, but this is not necessarily limited to this. For example, the psychological state induction-related processing may be performed by the HCU 20, 20a and another ECU. Alternatively, the psychological state induction-related processing may be performed by an ECU other than the HCU 20, 20a.

The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also within the technical scope of the present disclosure. Furthermore, the control unit and method described in the present disclosure may be implemented by a special-purpose computer comprising a processor programmed to execute one or more functions embodied in a computer program. Alternatively, the device and method described in the present disclosure may be implemented by a special-purpose hardware logic circuit. Alternatively, the device and method described in the present disclosure may be implemented by one or more special-purpose computers configured by combining a processor that executes a computer program with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable, non-transitory tangible recording medium.

(Disclosed technical idea)
This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with subsequent clauses alternatively referencing preceding clauses. Furthermore, some clauses may be written in a multiple dependent form, with subsequent clauses alternatively referencing preceding clauses. These multiple dependent clauses define multiple technical ideas.

Technical thought 1
a rhythm determination unit (205) for determining a target breathing rhythm for changing the psychological state of a driver of a vehicle to a target psychological state;
a breathing induction control unit (206, 206a, 206b, 206c) that controls a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit,
the rhythm determination unit determines, as the target breathing rhythm, an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed;
The respiratory induction control unit is a psychological state induction device that performs a first stimulus, which is a continuous stimulus change of two patterns with different directions for the same type of stimulus, by assigning it to the inhalation period and the exhalation period, respectively, and also performs a second stimulus, which is an intermittent stimulus at a fixed interval.

Technical thought 2
A psychological state induction device according to Technical Idea 1,
The respiratory induction control unit is a psychological state induction device that applies a third stimulus, which is a different type of stimulus from the first stimulus and the second stimulus, at the timing of switching between the inhalation period and the exhalation period.

Technical thought 3
The psychological state induction device according to Technical Idea 1 or 2,
The respiratory induction control unit is a psychological state induction device that assigns two patterns of continuous stimulus changes with opposite directions to the inhalation period and the exhalation period as the first stimulus for the same type of stimulus.

Technical thought 4
A psychological state induction device according to any one of technical concepts 1 to 3,
The breathing induction control unit is a psychological state induction device that performs changes in the two patterns of continuous stimuli with different directions, which are estimated to make the driver more likely to inhale and exhale, respectively.

Technical thought 5
A psychological state induction device according to any one of technical concepts 1 to 4,
The respiratory induction control unit is a psychological state induction device that matches the timing of presenting the second stimulus with the timing of switching between the inhalation period and the exhalation period.

Technical thought 6
A psychological state induction device according to any one of technical concepts 1 to 5,
The respiratory induction control unit is a psychological state induction device that sets the period of the intermittent stimulation at regular intervals in the second stimulation to a heartbeat-like period that is within a predetermined range starting from a period of 60 times per minute.

Technical thought 7
A psychological state induction device according to any one of technical concepts 1 to 5,
the target psychological state to be changed by the target respiratory rhythm determined by the rhythm determination unit includes at least an alertness state and a relaxation state of the driver;
The respiratory induction control unit, in the case of the target respiratory rhythm targeting the awake state, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period shorter than a heartbeat-like period, which is a period within a predetermined range starting from a period of 60 times per minute, while, in the case of the target respiratory rhythm targeting the relaxed state, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period longer than the heartbeat-like period.

Technical thought 8
A psychological state induction device according to any one of technical concepts 1 to 5,
a heartbeat identification unit (232) for identifying the heartbeat of the driver;
The breathing induction control unit is a psychological state induction device that, based on the heart rate identified by the heart rate identification unit, makes the period of the intermittent stimulation at a fixed interval in the second stimulation the same as the period of the driver's heart rate.

Technical thought 9
A psychological state induction device according to any one of technical concepts 1 to 5,
a target psychological state to be changed by the target respiratory rhythm determined by the rhythm determination unit includes an alertness state and a relaxation state of the driver;
a heartbeat identification unit (232) for identifying the heartbeat of the driver;
The respiratory induction control unit, based on the heart rate identified by the heart rate identification unit, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period shorter than the period of the driver's heart rate in the case of the target respiratory rhythm that aims for the awake state, while sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period longer than the period of the driver's heart rate in the case of the target respiratory rhythm that aims for the relaxed state.

Technical thought 10
A psychological state induction device according to any one of technical concepts 1 to 9,
A driving load estimation unit (202) for estimating the level of the driving load of the driver,
The respiratory induction control unit is a psychological state induction device that, when the driving load estimation unit estimates the driving load to be high, weakens the intensity of stimulation to the driver compared to when the driving load is estimated to be low.

Technical thought 11
A psychological state induction device according to any one of technical concepts 1 to 10,
an environmental condition identification unit (201) that identifies an environmental condition inside and outside the vehicle;
a target presence/absence determination unit (207) that determines, based on the environmental condition identified by the environmental condition identification unit, the presence or absence of a target stimulus, which is a stimulus in which the environmental condition becomes a large noise, among stimuli controlled by the respiratory guidance control unit;
The respiratory induction control unit is a psychological state induction device that, when the target presence/absence determination unit determines that the target stimulus is present, increases the intensity of the target stimulus or increases the intensity of stimuli other than the target stimulus among the stimuli controlled by the respiratory induction control unit.

Technical thought 12
Executed by at least one processor,
a rhythm determination step of determining a target breathing rhythm for changing the psychological state of the driver of the vehicle to a target psychological state;
a breathing induction control step of controlling a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined in the rhythm determination step,
the rhythm determining step determines an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed as the target breathing rhythm;
In the respiratory induction control process, in addition to a first stimulus that is a continuous stimulus change of two patterns with different directions for the same type of stimulus, which is assigned to the inhalation period and the exhalation period, respectively, a second stimulus that is an intermittent stimulus at a fixed interval is also performed.

1. Driving assistance system, 2. HMI system, 20, 20a, 20b, 20c. HCU (mental state induction device), 23. Respiratory induction device, 201. Environmental condition identification unit, 202. Driving load estimation unit, 205. Rhythm determination unit, 206, 206a, 206b, 206c. Respiratory induction control unit, 207. Target presence/absence determination unit, 232. Heart rate identification unit

Claims (10)

a rhythm determination unit (205) for determining a target breathing rhythm for changing the psychological state of a driver of a vehicle to a target psychological state;
a breathing induction control unit (206, 206a, 206b, 206c) that controls a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit,
the rhythm determination unit determines, as the target breathing rhythm, an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed;
the respiratory guidance control unit performs a first stimulus that is a continuous stimulus change of two patterns with different directions for the same type of stimulus, by allocating the change to the inhalation period and the exhalation period, respectively, and also performs a second stimulus that is an intermittent stimulus at a fixed interval;
the target psychological state to be changed by the target respiratory rhythm determined by the rhythm determination unit includes at least an alertness state and a relaxation state of the driver;
The respiratory induction control unit, in the case of the target respiratory rhythm targeting the awake state, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period shorter than a heartbeat-like period, which is a period within a predetermined range starting from a period of 60 times per minute, while, in the case of the target respiratory rhythm targeting the relaxed state, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period longer than the heartbeat-like period . a rhythm determination unit (205) for determining a target breathing rhythm for changing the psychological state of a driver of a vehicle to a target psychological state;
a breathing induction control unit (206, 206a, 206b, 206c) that controls a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined by the rhythm determination unit,
the rhythm determination unit determines, as the target breathing rhythm, an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed;
the respiratory guidance control unit performs a first stimulus that is a continuous stimulus change of two patterns with different directions for the same type of stimulus, by allocating the change to the inhalation period and the exhalation period, respectively, and also performs a second stimulus that is an intermittent stimulus at a fixed interval;
a target psychological state to be changed by the target respiratory rhythm determined by the rhythm determination unit includes an alertness state and a relaxation state of the driver;
a heartbeat identification unit (232) for identifying the heartbeat of the driver;
The respiratory induction control unit, based on the heart rate identified by the heart rate identification unit, sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period shorter than the period of the driver's heart rate in the case of the target respiratory rhythm that aims for the awake state, while sets the period of the intermittent stimulation at regular intervals in the second stimulus to a period longer than the period of the driver's heart rate in the case of the target respiratory rhythm that aims for the relaxed state . The psychological state induction device according to claim 1 or 2 ,
The respiratory induction control unit is a psychological state induction device that applies a third stimulus, which is a different type of stimulus from the first stimulus and the second stimulus, at the timing of switching between the inhalation period and the exhalation period. The psychological state induction device according to claim 1 or 2 ,
The respiratory induction control unit is a psychological state induction device that assigns two patterns of continuous stimulus changes with opposite directions to the inhalation period and the exhalation period as the first stimulus for the same type of stimulus. The psychological state induction device according to claim 1 or 2 ,
The breathing induction control unit is a psychological state induction device that performs changes in the two patterns of continuous stimuli with different directions, which are estimated to make the driver more likely to inhale and exhale, respectively. The psychological state induction device according to claim 1 or 2 ,
The respiratory induction control unit is a psychological state induction device that matches the timing of presenting the second stimulus with the timing of switching between the inhalation period and the exhalation period. The psychological state induction device according to claim 1 or 2 ,
A driving load estimation unit (202) for estimating the level of the driving load of the driver,
The respiratory induction control unit is a psychological state induction device that, when the driving load estimation unit estimates the driving load to be high, weakens the intensity of stimulation to the driver compared to when the driving load is estimated to be low. The psychological state induction device according to claim 1 or 2 ,
an environmental condition identification unit (201) that identifies an environmental condition inside and outside the vehicle;
a target presence/absence determination unit (207) that determines, based on the environmental condition identified by the environmental condition identification unit, the presence or absence of a target stimulus, which is a stimulus in which the environmental condition becomes a large noise, among stimuli controlled by the respiratory guidance control unit;
The respiratory induction control unit is a psychological state induction device that, when the target presence/absence determination unit determines that the target stimulus is present, increases the intensity of the target stimulus or increases the intensity of stimuli other than the target stimulus among the stimuli controlled by the respiratory induction control unit. Executed by at least one processor,
a rhythm determination step of determining a target breathing rhythm for changing the psychological state of the driver of the vehicle to a target psychological state;
a breathing induction control step of controlling a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined in the rhythm determination step,
the rhythm determining step determines an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed as the target breathing rhythm;
In the respiratory induction control step, in addition to a first stimulus that is a first stimulus in which two patterns of continuous stimulus changes having different directions are assigned to the inhalation period and the exhalation period, respectively, for the same type of stimulus, a second stimulus that is an intermittent stimulus at a fixed interval is also performed ,
the target psychological state to be changed by the target respiratory rhythm determined in the rhythm determining step includes at least an alertness state and a relaxation state of the driver;
In the respiratory induction control step, in the case of the target respiratory rhythm that aims at the wakeful state, the period of the intermittent stimulation at regular intervals in the second stimulus is set to a period shorter than a heartbeat-like period, which is a period within a predetermined range starting from a period of 60 times per minute, while in the case of the target respiratory rhythm that aims at the relaxed state, the period of the intermittent stimulation at regular intervals in the second stimulus is set to a period longer than the heartbeat-like period . Executed by at least one processor,
a rhythm determination step of determining a target breathing rhythm for changing the psychological state of the driver of the vehicle to a target psychological state;
a breathing induction control step of controlling a stimulus to induce the driver to breathe in accordance with the target breathing rhythm determined in the rhythm determination step,
the rhythm determining step determines an inhalation period during which inhalation is performed and an exhalation period during which exhalation is performed as the target breathing rhythm;
In the respiratory induction control step, in addition to a first stimulus that is a first stimulus in which two patterns of continuous stimulus changes having different directions are assigned to the inhalation period and the exhalation period, respectively, for the same type of stimulus, a second stimulus that is an intermittent stimulus at a fixed interval is also performed ,
a target psychological state to be changed by the target respiratory rhythm determined in the rhythm determining step includes an alertness state and a relaxation state of the driver;
a heart rate determining step of determining the heart rate of the driver,
In the respiratory induction control step, based on the heart rate identified in the heart rate identification step, in the case of the target respiratory rhythm that aims at the awake state, the period of the intermittent stimulation at regular intervals in the second stimulus is made shorter than the period of the driver's heart rate, while in the case of the target respiratory rhythm that aims at the relaxed state, the period of the intermittent stimulation at regular intervals in the second stimulus is made longer than the period of the driver's heart rate .