Driving assistance devices

Abstract

To provide a driving support device capable of obtaining arousal improvement effects without considerably changing a cardiac rate by paying attention to a change of subjective arousal and a change of the cardiac rate in a sound image representation of engine sound.SOLUTION: In a driving support device, a sound image change of engine sound is used for improving arousal of a driver driving a vehicle. When the vehicle travels, dummy engine sound is output as engine sound, arousal reduction of the driver is detected or predicted, thereby determining output timing, and a sound image due to the dummy engine sound is changed in the determined output timing.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device that improves the driver's alertness. [Background technology]

[0002] In recent years, the number of traffic accidents and fatalities has tended to decrease compared to several years ago. According to statistics from the Tokyo Metropolitan Police Department, there were 381,002 traffic accidents and 3,215 fatalities in fiscal 2019. A survey of fatalities by type of traffic accident revealed that distracted driving accounts for approximately 40% of traffic accident fatalities. Furthermore, the rate of decline in distracted driving cases has been small in recent years, while cases of overworked driving have actually increased. It is necessary to prevent a decline in alertness, which affects the concentration required for distracted or overworked driving, from occurring due to microsleep and fatigue, before it impairs safe driving. In the past, a common method of preventing a decrease in driver alertness was to alert the driver by presenting a warning sound from the driver assistance system, but this could lead to the driver finding the warning sound annoying and disabling the driver assistance system. Additionally, a practical system has been developed that vibrates the steering wheel to alert the driver when the vehicle is about to depart its lane due to a decrease in alertness, but this is not applicable in situations where the driver does not need to keep their hands on the steering wheel, such as when using autonomous driving technology. Based on these previous examples, we focused on a method that increases the driver's alertness by making the sound image of environmental sounds that the driver hears constantly, particularly engine sounds, move to make the driver aware of the discomfort and increase the driver's alertness, as a means of simultaneously reducing the impact of increased driver annoyance and preventing a decrease in driver alertness. Patent Document 1 describes a method of waking up the driver by changing the engine sound, and Patent Document 2 describes a method of periodically increasing and decreasing the engine speed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-23086 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-68799 Summary of the Invention [Problem to be solved by the invention]

[0004] However, experiments have revealed that changes in engine sound or periodic increases and decreases in engine speed, as described in Patent Documents 1 and 2, do not provide a sufficient awakening effect.

[0005] The present invention aims to provide a driving assistance device that focuses on changes in subjective arousal level and heart rate in the sound image representation of engine sound, and that can achieve the effect of improving arousal level without causing a large change in heart rate. [Means for solving the problem]

[0006] The driving support device of the present invention described in claim 1 uses the change in the sound image of the engine sound to improve the level of awareness of the driver who is driving the vehicle. The sound image change includes at least one of left-right and up-down directions relative to the driver by using a plurality of speakers, and the sound pressure of the speakers is changed alternately left-right or up-down. It is characterized by the following. The present invention as set forth in claim 2 is characterized in that, in the driving assistance device as set forth in claim 1, a pseudo engine sound is output as the engine sound while the vehicle is traveling, the output timing is determined by detecting or predicting a decrease in the driver's alertness, and the sound image produced by the pseudo engine sound is changed at the determined output timing. The present invention of claim 3 is characterized in that, in the driving assistance device of claim 2, the pseudo engine sound is output at a frequency according to the speed of the vehicle, and the sound image change is performed at the frequency at the output timing. The present invention as set forth in claim 4 is characterized in that, in the driving assistance device as set forth in claim 3, the frequency is changed in accordance with torque. The present invention as set forth in claim 5 is the driving assistance device as set forth in claim 2, pseudoThe engine sound is output at a frequency according to the operation of a drivetrain device of the vehicle by the driver, and the sound image is changed at the frequency at the output timing. Claim 6 The invention as described comprises claims 1 to Claim 5 In the driving assistance device described in any one of the above, the vehicle is driven by a drive motor 10. [Effects of the Invention]

[0007] According to the driving assistance device of the present invention, it is possible to obtain the effect of improving the level of alertness without causing a large change in the heart rate. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a block diagram showing a driving assistance device according to an embodiment of the present invention in terms of function realization means; [Figure 2] Figure 1 shows the test sound patterns of the engine sound and warning sound presented in this experiment. [Figure 3] Diagram showing KSS indicators [Figure 4] Graph showing average KSS scores [Figure 5] Graph showing the amount of change in KSS [Figure 6] Graph showing changes in heart rate DETAILED DESCRIPTION OF THE INVENTION

[0009] The driving assistance device according to the first embodiment of the present invention uses a change in the sound image of the engine sound to improve the level of awareness of the driver who is driving the vehicle. By using a plurality of speakers, the sound image change includes at least one of the left-right direction and the up-down direction with respect to the driver, and the sound pressure of the speakers is changed alternately left-right or up-down. This is what is done. According to this embodiment, the effect of improving the level of wakefulness can be obtained without causing a large change in the heart rate. Furthermore, by changing the sound image in at least one of the left-right and up-down directions, it is possible to obtain an awakening effect.

[0010] In the second embodiment of the present invention, in the driving assistance device according to the first embodiment, a pseudo engine sound is output as an engine sound when the vehicle is traveling, the output timing is determined by detecting or predicting a decrease in the driver's alertness, and the sound image produced by the pseudo engine sound is changed at the determined output timing. According to this embodiment, by using a pseudo engine sound that allows the driver to recognize the driving state, it is possible to obtain the effect of improving the driver's level of alertness without causing a large change in the heart rate.

[0011] A third embodiment of the present invention is a driving assistance device according to the second embodiment, in which a pseudo engine sound is output at a frequency according to the vehicle speed, and the sound image is changed at the frequency at the output timing. According to this embodiment, by changing the sound image at a frequency that corresponds to the speed of the vehicle, it is possible to obtain the effect of improving the level of wakefulness without causing a large change in the heart rate.

[0012] A fourth embodiment of the present invention is a driving assistance device according to the third embodiment, in which the frequency is changed in accordance with the torque. According to this embodiment, by changing the frequency depending on the torque, it is possible to more easily grasp the driving condition and obtain the effect of improving the level of alertness without causing a large change in the heart rate.

[0013] In the fifth embodiment of the present invention, in the driving assistance device according to the second embodiment, a pseudo engine sound is output at a frequency according to the operation of a drivetrain device of the vehicle by the driver, and the sound image is changed at the frequency at the output timing. According to this embodiment, by changing the sound image at a frequency corresponding to the operation of a drivetrain device by the driver, it is possible to obtain the effect of improving the wakefulness without causing a large change in the heart rate.

[0014] The present invention No. 6 The embodiments are as follows: No. 5 In the driving assistance device according to any one of the above embodiments, the vehicle is driven by a drive motor. According to this embodiment, in a vehicle that runs on a drive motor that does not make engine noise, it is possible to obtain the effect of improving alertness without causing a large change in heart rate, and by emitting a pseudo engine sound while driving, it is possible to reduce the physiological effects of driving noises such as wind noise and road noise, or high-frequency sounds emitted by the inverter. [Example]

[0015] A driving assistance device according to an embodiment of the present invention will now be described. FIG. 1 is a block diagram showing a driving support device according to this embodiment in terms of function realization means. The driving assistance device according to this embodiment is suitable for electric vehicles and fuel cell vehicles that run on the drive motor 10 without using an internal combustion engine, but is also effective when running on the drive motor 10 in hybrid vehicles that use either an engine or the drive motor 10 alternatively. The driving support device according to this embodiment includes a driving state detection means 1, pseudo engine sound generating means 2; pseudo The device includes engine sound output means 3, output timing determination means 4, and sound image change means 5. The driving condition detection means 1 detects the driving condition, for example, from the rotation speed and torque of the drive motor 10. The vehicle speed can be detected from the rotation speed of the drive motor 10 used to drive the vehicle, and the acceleration / deceleration state of the vehicle and the inclination state of the road surface can be detected from the torque of the drive motor 10. pseudo The engine sound generating means 2 generates the sound of an internal combustion engine, and generates a frequency corresponding to the running state detected by the running state detecting means 1. That is, by generating a frequency corresponding to the rotation speed of the drive motor 10, a sound corresponding to the vehicle speed can be generated. pseudo In addition, by generating a frequency according to the torque of the drive motor 10, it is possible to generate engine sounds according to the acceleration / deceleration state of the vehicle and the inclination state of the road surface. pseudo Engine sounds can be generated. pseudo The engine sound output means 3 includes: pseudo Generated by engine sound generation means 2 pseudoThe engine sound is output to the speaker 11. The speaker 11 is arranged inside the vehicle, and it is preferable that at least a pair of sound sources is arranged on the left and right or above and below the driver. The output timing determination means 4 determines the output timing based on a signal from the alertness reduction detection / prediction means 12. The alertness reduction detection / prediction means 12 detects or predicts the driver's drowsiness or drowsiness at the wheel. Examples of the alertness reduction detection / prediction means 12 include detection using a pupil detection sensor, detection by detecting biological signals and analyzing fluctuations in body surface pulsation, prediction from the vehicle driving state such as lane departure, and prediction from road conditions such as continued straight driving. The sound image changing means 5 changes the sound image of the pseudo engine sound at the timing determined by the output timing determining means 4. It is preferable to change the sound image at a frequency that corresponds to the vehicle speed at the output timing, and it is also preferable to change the sound image at a frequency that corresponds to the vehicle speed and torque at the output timing.

[0016] By changing the sound image with the sound image changing means 5, pseudo The engine sound output means 3 alternately changes the sound pressure of the speakers 11 arranged on the left and right of the driver, or alternately changes the sound pressure of the speakers 11 arranged above and below the driver. The sound image change may be diagonally upward and downward from the driver, or diagonally downward and upward from the driver. Such diagonal sound image change is due to a sound image change in the left-right direction and a sound image change in the up-down direction. As long as the sound image change includes at least one of the left-right direction and the up-down direction from the driver, a sound image change in the front-back direction may also be included.

[0017] In FIG. 1, the driving condition detection means 1 is described as detecting the rotation speed and torque of the drive motor 10, but in addition to or instead of detecting the rotation speed and torque of the drive motor 10, it may also detect the operation of the vehicle's drive system devices by the driver. When detecting the operation of a drivetrain device, pseudoThe engine sound generating means 2 generates a frequency according to the operation of the drivetrain device. The driving state detection means 1 detects the rotation speed and torque of the drive motor 10, as well as the operation of the drive system devices of the vehicle by the driver. pseudo By generating engine sounds, it is possible to output a frequency that corresponds to the vehicle's driving state, taking into account the driver's driving intentions, and by changing the sound image at the frequency at the output timing, it is possible to achieve an improved level of alertness without significantly changing the heart rate. Here, the drivetrain devices of the vehicle are, for example, an acceleration device, a deceleration device, and a driving mode change device, more specifically, an accelerator pedal, a brake pedal, and a shift lever. The shift lever not only selects forward or reverse, but also sets an eco mode that suppresses power output and a regenerative setting mode that adjusts the strength of regenerative braking.

[0018] The results of the demonstration experiment of the present invention will be explained using FIGS. In the experiment, the effect of improving the level of arousal by expressing the sound image of the engine sound was verified using a driving simulator (hereinafter referred to as DS).

[0019] Experimental scenario In this experiment, we aimed to verify the change in the participants' level of alertness when they were first lowered and then presented with the engine sound or warning sound.To this end, we set up the following experimental scenario, simulating the situation of being in a vehicle in a fully autonomous driving state. Driving simulator software: Foru8 UC-Win / Road DrivingSin Driving course: Straight highway with three lanes on each side Driving scene: Night Indoor illuminance: 10lx or less Escort vehicle: Yes (appears randomly) Driving method: Automatic driving mode, constant speed of 100km / h Travel time: 30 minutes At 25 minutes into the drive, the engine sound that had been continuously presented to the driver was switched to the sound that will be explained later, and the changes in alertness and heart rate before and after the sound was presented were evaluated. The evaluation indexes will be explained later. In the experiment, the number of times the sound could be presented per run was limited to one, so each participant was presented with five sounds.

[0020] About the presentation Figure 2 shows the test sound patterns of the engine sound and warning sound presented in this experiment. The five engine sound and warning sound patterns presented 25 minutes after the start of driving were shown in Figure 2. The engine sound was presented to the experiment participants using headphones (SONY MDR-V6). The sound pressure of the reference engine sound was adjusted to 65 dB. The increase or decrease in sound pressure during presentation of the sound was 8 dB. The minimum sound pressure for the sound image presentation of Pattern 3 was 0 dB, so that the sound image could be clearly seen moving left and right. The engine sound used as the presentation sound was generated by sampling the engine sound output from the driving simulator as stereo data on a PC (OS: Windows 10) at a sampling frequency of 44.1 kHz, and the sound pressure was adjusted using SoundEngine Free Ver. 5.23. Warning sounds and voice warnings were generated using WaveGene Ver. 1.50 and the Text-to-Speech function of Windows 10, and edited using SoundEngine Free. The sound pressure of the presentation sound was set to 73 dB. One type of sound was randomly selected for each run. The order in which the sounds were presented to each participant was counterbalanced to counteract any learning effects that may result from the order of presentation.

[0021] Evaluation indicators To verify the changes in arousal levels in this experiment, two types of indices were used: subjective and objective. The subjective evaluation index used was the Kalorinska Sleepiness Scale (KSS). Figure 3 shows the KSS index. Every five minutes during the experiment, the experimenter silently presented the participants with a table showing the KSS scale, and the participants were asked to rate it by pointing at it. If the participant fell asleep and it was difficult to rate them, they were given a score of 10. Heart rate was used as the objective evaluation index. Assuming that changes in engine sound and the presentation of warning sounds would have physiological effects, the RR interval of the electrocardiogram was measured and converted to heart rates per minute. The level of stimulation given to the experimental participants was then evaluated based on the change in heart rate before and after the presentation of the sounds. Heart rate was measured in real time on a laptop using a Union Tool WHS-1 and RRI Analyzer 2. For each evaluation index, the experimental results of 10 participants were averaged and compared. To test for significant differences between experimental conditions, a Tukey-Kramer multiple comparison test was used.

[0022] Experiment participants The participants were 10 male students aged 18 to 22. To account for changes in arousal levels due to circadian rhythms, the time of the experiment was uniform for each participant. Furthermore, to accurately assess the arousal effect of the presented sounds, participants were instructed to refrain from consuming foods and beverages containing caffeine or other stimulants after waking up on the day of the experiment. This experiment was conducted between November 2020 and February 2021 in the Kazuya Ito Laboratory at Ichinoseki National College of Technology, the author's former affiliation. The purpose and content of the experiment were explained to participants via consent forms, and their consent was obtained before the experiment was conducted.

[0023] Results for KSS changes FIG. 4 is a graph showing the average KSS value, and FIG. 5 is a graph showing the amount of change in KSS. Figure 4 shows the average KSS for 10 people before and after the presentation of the sound, and Figure 5 shows the change in KSS in the same way. The warning sound of pattern 5 had the largest change in KSS, while the sound image representation of pattern 3 was roughly the same as that of pattern 5. The change in KSS was small between pattern 1, in which the engine sound pressure increases and becomes constant, and pattern 2, in which the engine sound pressure decreases and becomes constant. Furthermore, the change in KSS for pattern 4, in which the engine sound pressure was increased and decreased cyclically, was somewhere between that of pattern 1 and pattern 3. There was one experimental participant whose KSS score was 10 before the presentation of the sound, but the KSS did not change even after the presentation of the sound.

[0024] Heart rate variability results FIG. 6 is a graph showing changes in heart rate. Figure 6 shows the average value for 10 people regarding the difference in average heart rate one minute before and one minute after the presentation of the sound. It was confirmed that the sound image representation of Pattern 3 tended to cause less of an increase in heart rate compared to Pattern 5. Unlike the other patterns, the reduction in sound pressure of Pattern 2 showed a tendency to decrease heart rate. However, the test results showed no significant difference.

[0025] Impact on listeners In terms of subjective arousal, the engine sound image presentation showed a similar arousal effect to the warning sound presentation, but no significant effect was observed in heart rate changes. Furthermore, the number of participants whose heart rate increased by more than 10% after the presentation of the sound presentation was six for the warning sound in Pattern 5, compared with two for the sound image presentation in Pattern 3. This may be due to differences in the orienting reflex (OR) and defensive reflex (DR) to stimuli. OR has been shown to increase perceptual sensitivity due to interest in the novelty of stimuli, thereby increasing information acquisition and information processing, and is associated with heart rate suppression. DR has also been shown to decrease perceptual sensitivity to stimuli and promote heart rate acceleration. This suggests that changes in the engine sound image may have the effect of increasing arousal by increasing information processing through OR. On the other hand, it is possible that whether a response to a stimulus is OR or DR depends on the level of interest in or concern with the engine sound. Furthermore, in experiments using actual vehicles, it is possible that participants who experienced OR in the driving simulator experiment may also experience DR. [Industrial Applicability]

[0026] The driving assistance device according to the present invention is particularly suitable for electric vehicles and fuel cell vehicles that are driven by a drive motor. [Explanation of symbols]

[0027] 1. Driving condition detection means 2 pseudo Engine sound generation means 3 pseudo Engine sound output means 4. Output timing determination method 5. Sound image change means 10 Drive motor 11 Speaker 12. Measures for detecting / predicting hypovigilance

Claims

1. The change in the sound image of the engine sound is used to increase the driver's awareness while driving the vehicle. The sound image change includes at least one of left-right and up-down directions relative to the driver by using a plurality of speakers, and the sound pressure of the speakers is changed alternately left-right or up-down. A driving assistance device characterized by:

2. outputting a pseudo engine sound as the engine sound while the vehicle is running; determining an output timing by detecting or predicting a decrease in the driver's alertness; The sound image produced by the pseudo engine sound is changed at the determined output timing.

2. The driving assistance device according to claim 1.

3. outputting the pseudo engine sound at a frequency corresponding to the speed of the vehicle; The sound image is changed at the frequency at the output timing.

3. The driving assistance device according to claim 2.

4. The frequency is changed according to the torque.

4. The driving assistance device according to claim 3.

5. outputting the pseudo engine sound at a frequency corresponding to an operation of a drivetrain device of the vehicle by the driver; The sound image is changed at the frequency at the output timing.

3. The driving assistance device according to claim 2.

6. The vehicle is driven by a drive motor.

6. The driving assistance device according to claim 1, wherein the driving assistance device is a vehicle.

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