Driving assistance device and computer program

Abstract

To provide a drive support device capable of notifying a driver during driving of information about evaluation of driving operation of the driver without giving an impression of denying the driving of the driver and by a method capable of suppressing a decrease in attention.SOLUTION: A drive support device, which presents behavior stability of a vehicle to a driver by an auditory stimulation, determines the behavior stability of the vehicle based on information indicating the behavior of the vehicle, and outputs the auditory stimulation while changing the auditory stimulation each time the vehicle travels over a predetermined period or a predetermined section in a state where the behavior stability is high.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a driving assistance device, a computer program, and a recording medium for improving vehicle driving skills. [Background technology]

[0002] The level of driving performance of a vehicle varies depending on the driver. The level of driving performance affects ride comfort and traffic safety. In response to this, various devices have been proposed that assess the driver's driving performance, notify the driver of the assessment results, and provide advice.

[0003] For example, Patent Document 1 proposes a driving assistance device that accurately determines a driving operation state and allows a driver to know information about an overall evaluation of the driving operation state in the current drive, thereby improving driving skills in the next drive. Specifically, Patent Document 1 discloses a driving assistance device that includes: a change amount calculation unit that calculates a first related value related to an amount of change in acceleration; a jerk calculation unit that calculates a second related value related to a jerk; a state determination unit that determines whether the driving state is smooth or shaky from the first and second related values ​​according to a predetermined determination criterion using a vibration model; and a comprehensive determination unit that calculates a score for the determination result by the state determination unit in the current drive, divides the score by the number of determinations made by the state determination unit in the current drive to calculate a first evaluation index, and calculates an overall evaluation score of the driving operation state in the current drive based on the first evaluation index. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-198344 Summary of the Invention [Problem to be solved by the invention]

[0005] However, because the driving assistance device described in Patent Document 1 evaluates a series of driving operations performed during the current drive, it is difficult for the driver to understand at what specific point in time the driving operations were evaluated. In contrast, if the evaluation results and advice on driving operations are presented to the driver while driving using audio text or image display, the driver's attention to the surroundings of the vehicle may decrease when checking the evaluation results or the advice. Furthermore, while it is conceivable to notify the driver when the vehicle's behavior becomes unstable while the driver is driving, this may give the impression that the driver's driving is being rejected, and may be less effective in improving the driving skills of drivers who have little motivation to improve their driving skills.

[0006] The present disclosure has been made in consideration of the above-mentioned problems, and an object of the present disclosure is to provide a driving assistance device that can notify a driver while driving of information regarding an evaluation of the driver's driving operation in a manner that does not give the impression that the driver's driving is negative and that can prevent a decrease in attention. [Means for solving the problem]

[0007] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a driving assistance device that presents a vehicle's behavioral stability to a driver through auditory stimulation, the driving assistance device comprising one or more processors and one or more memories communicably connected to the one or more processors, wherein the processor determines the vehicle's behavioral stability based on information indicating the vehicle's behavior, and outputs the auditory stimulation while changing the auditory stimulation each time the vehicle travels for a predetermined period or a predetermined section in a state where behavioral stability is high.

[0008] In order to solve the above problem, according to another aspect of the present disclosure, there is provided a driving assistance device that presents the vehicle's behavioral stability to a driver through auditory stimulation, the driving assistance device including: a behavior stability determination unit that determines the vehicle's behavioral stability based on information indicating the vehicle's behavior; and an output control unit that outputs the auditory stimulation while changing the auditory stimulation each time the vehicle travels for a predetermined period or a predetermined section in a state where behavioral stability is high.

[0009] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a computer program to be applied to a driving assistance device that presents a vehicle's behavioral stability to a driver through auditory stimuli, the computer program causing one or more processors to execute processing including determining the vehicle's behavioral stability based on information indicating the vehicle's behavior, and outputting auditory stimuli while changing the auditory stimuli each time the vehicle travels for a predetermined period or a predetermined section in a state where behavioral stability is high, and a recording medium having the computer program recorded thereon. [Effects of the Invention]

[0010] As described above, according to the present disclosure, it is possible to notify a driver while driving of information regarding an evaluation of the driver's driving operation in a manner that does not give the impression that the driver's driving is being denied and that can prevent a decline in attention. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing a vehicle to which a driving assistance device according to the present disclosure is applied. [Figure 2] 1 is a block diagram illustrating a configuration example of a driving assistance device according to an embodiment of the present disclosure. [Figure 3] FIG. 2 is an explanatory diagram illustrating an example of data conversion processing performed by the driving assistance device according to the first embodiment. [Figure 4] 4 is an explanatory diagram showing an example of a behavior stability determination process according to the embodiment; FIG. [Figure 5] 10 is an explanatory diagram showing an example of changing a threshold value depending on the driving skill of a driver according to the embodiment. FIG. [Figure 6] 10 is an explanatory diagram showing an example of an output pattern of auditory stimulation according to the embodiment. FIG. [Figure 7] 10 is an explanatory diagram showing an example of setting an output pattern of auditory stimulation according to the embodiment. FIG. [Figure 8] FIG. 10 is an explanatory diagram showing an example of condition setting according to the embodiment. [Figure 9] 4 is a flowchart showing a main routine of a control process according to the embodiment. [Figure 10] 10 is a flowchart of a condition setting process according to the embodiment. [Figure 11] 10 is a flowchart of a behavior stability determination process according to the embodiment. [Figure 12] 10 is a flowchart showing another example of the behavior stability determination process according to the embodiment. [Figure 13] 10 is a flowchart showing a basic process for outputting an auditory stimulus according to the embodiment. [Figure 14] 10 is a flowchart illustrating an example of an output change process according to the embodiment. [Figure 15] FIG. 10 is an explanatory diagram illustrating an example of behavior stability determination processing according to the second embodiment. [Figure 16] 10 is a flowchart of a behavior stability determination process according to the embodiment. [Figure 17] 10 is a flowchart illustrating an example of an output change process according to the embodiment. [Figure 18] 13 is a flowchart illustrating an example of an output change process according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0013] <<1. First Embodiment>> <1-1. Overview of driving assistance devices> First, an outline of a driving assistance device according to a first embodiment of the present disclosure will be described. The driving assistance device acquires information indicating the behavior of the vehicle while the vehicle is traveling, determines the behavior stability of the vehicle based on the acquired information, and outputs a predetermined sound according to the determination result. Since the behavior of the vehicle mainly reflects the driver's steering operation state, accelerator operation state, and brake operation state, the driver can intuitively recognize the evaluation of his / her own driving operation state in real time through auditory stimulation.

[0014] The driving assistance device according to this embodiment outputs auditory stimuli while changing the auditory stimuli each time the vehicle travels for a predetermined period or a predetermined section while the vehicle's behavioral stability is high. This allows the driver to intuitively recognize the evaluation of the vehicle's driving operation while traveling in real time through the auditory stimuli. Furthermore, because the auditory stimuli change when the vehicle's behavioral stability is high, the driver does not get the impression that their driving is negative. Furthermore, because the auditory stimuli change successively as the vehicle's behavioral stability continues to be high, the driver does not become accustomed to the stimuli when the vehicle's behavioral stability is high, and the driver's motivation to improve their driving skills can be maintained.

[0015] <1-2. Example of configuration of driving assistance device> First, a configuration example of a driving assistance device 1 according to a first embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic diagram showing a vehicle to which the driving assistance device 1 is applied, and Fig. 2 is a block diagram showing an example of the configuration of the driving assistance device 1.

[0016] The driving assistance device 1 includes an information processing device 50. The information processing device 50 includes one or more processors such as a CPU (Central Processing Unit) and one or more memories such as a RAM (Random Access Memory) or a ROM (Read Only Memory) communicably connected to the processor. A part or all of the information processing device 50 may be configured with updatable firmware or the like, or may be a program module or the like that is executed by instructions from the processor.

[0017] The information processing device 50 functions as a device that controls the operation of the driving assistance device 1 by having one or more processors execute a computer program. The computer program is a computer program that causes the processor to execute the operations, described below, that should be executed by the information processing device 50. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) 55 provided in the information processing device 50, or may be recorded on a recording medium built into the information processing device 50 or any recording medium that can be externally attached to the information processing device 50.

[0018] Recording media for recording computer programs may include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical recording media such as CD-ROMs (Compact Disk Read Only Memory), DVDs (Digital Versatile Disks), and Blu-ray (registered trademark), magneto-optical media such as floptical disks, memory elements such as RAMs and ROMs, and flash memories such as USB (Universal Serial Bus) memories, as well as other media capable of storing programs.

[0019] The driving assistance device 1 also includes a vehicle behavior measurement device 11, an input device 13, and an output device 21. The vehicle behavior measurement device 11, the input device 13, and the output device 21 are communicably connected to an information processing device 50 via a communication bus such as a dedicated line or a CAN (Controller Area Network).

[0020] (1-2-1. Vehicle behavior measurement device) The vehicle behavior measurement device 11 is a device that measures information indicating the behavior of the vehicle. The vehicle behavior measurement device 11 includes, for example, at least one of a vehicle speed sensor, an acceleration sensor, and an angular velocity sensor. The vehicle speed sensor detects, for example, the rotational speed of the vehicle's drive shaft. The acceleration sensor detects at least longitudinal acceleration, which is acceleration in the longitudinal direction of the vehicle body, and lateral acceleration, which is acceleration in the width direction of the vehicle. The acceleration sensor may also detect vertical acceleration, which is acceleration in the height direction of the vehicle body. The angular velocity sensor detects the rate of change of each of the rotation angle around an axis in the longitudinal direction of the vehicle body (roll angle), the rotation angle around an axis in the width direction of the vehicle body (pitch angle), and the rotation angle around an axis in the height direction of the vehicle body (yaw angle). The angular velocity sensor may be a yaw rate sensor that detects the rate of change of the yaw angle.

[0021] The data measured by the vehicle behavior measurement device 11 is data that can change depending on the steering, accelerator, and brake operations by the driver, and is transmitted to the information processing device 50 as information indicating the vehicle behavior. The information processing device 50 is configured to be able to acquire the information measured by the vehicle behavior measurement device 11. The vehicle behavior measurement device 11 may include sensors capable of measuring data that reflect the vehicle behavior, in addition to a vehicle speed sensor, an acceleration sensor, and an angular velocity sensor.

[0022] (1-2-2. Input device) The input device 13 accepts user operation input and transmits it to the information processing device 50. The input device 13 may be, for example, a touch panel display or a dial-type operating device. Alternatively, the input device 13 may be a voice recognition device that accepts input by the voice of the occupant, or an image recognition device that accepts input by gesture.

[0023] In this embodiment, the input device 13 accepts input of information related to the driver's attributes. The information related to the driver's attributes is information related to the driver's driving skills, and includes, for example, at least one of the following information: the driver's age, the number of years since obtaining a license, driving frequency, the number of years since the last driving session, etc. Furthermore, other information that can be used to estimate the driver's driving skills may also be included. This information may be input in the form of a questionnaire in which the driver or the like answers questions presented by the information processing device 50, or data that has been determined or accumulated in advance may be input.

[0024] The input device 13 may also accept input of information about a sound desired as an output sound. For example, the input device 13 may be configured to allow the driver or the like to select a desired sound from among tones or types of sounds presented by the information processing device 50. Specifically, the type of musical instrument sound or sound effect to be output may be selectable. Data about the selected sound is stored in advance in the storage unit 55 of the information processing device 50, but the sound data may be updated or added by communicating with an external server or the like.

[0025] It should be noted that the input device 13 is not an essential component when the control conditions are not changed depending on the driver attributes or when the output sound is made unselectable.

[0026] (1-2-3. Output device) The output device 21 is a device that outputs a sound that can be recognized by the driver. The output device 21 may be a speaker provided in the vehicle, or may be a speaker dedicated to the driving assistance device 1. In this embodiment, the output device 21 is configured as a speaker system including a plurality of speakers 21a to 21d provided in the vehicle. The output of the output device 21 is controlled by the information processing device 50, and the output device 21 makes the driver aware of the behavioral stability of the vehicle through auditory stimulation.

[0027] (1-2-4. Information processing device) The information processing device 50 includes a communication unit 51, a processing unit 53, and a storage unit 55. The processing unit 53 includes an acquisition unit 61, a data processing unit 63, a behavior stability determination unit 65, an output control unit 67, and a condition setting unit 69. The processing unit 53 is a processor such as a CPU, and the acquisition unit 61, the data processing unit 63, the behavior stability determination unit 65, the output control unit 67, and the condition setting unit 69 are functions realized by the processor executing a program. However, part of the acquisition unit 61, the data processing unit 63, the behavior stability determination unit 65, the output control unit 67, and the condition setting unit 69 may be configured using analog circuits.

[0028] (Storage part) The storage unit 55 is configured to include one or more storage elements such as RAM or ROM, etc. The storage unit 55 stores programs executed by the processing unit 53, various parameters used for executing the programs, acquired data, data of calculation results, etc.

[0029] (Communications Department) The communication unit 51 is an interface for transmitting and receiving data and signals to and from the vehicle behavior measurement device 11, the input device 13, and the output device 21.

[0030] (Acquisition Department) The acquisition unit 61 of the processing unit 53 acquires information transmitted from the vehicle behavior measurement device 11 and the input device 13 via the communication unit 51. The information acquired by the acquisition unit 61 includes information indicating the behavior of the vehicle output from the vehicle behavior measurement device 11. The acquisition unit 61 acquires information at a predetermined calculation cycle and stores the acquired information in the storage unit 55.

[0031] (Data Processing Unit) The data processing unit 63 of the processing unit 53 performs predetermined data processing on the information indicating the behavior of the vehicle acquired by the acquisition unit 61. Specifically, the data processing unit 63 performs at least one of smoothing processing, absolute value conversion processing, and differentiation processing on the acquired measurement data of the vehicle speed, acceleration (longitudinal acceleration, lateral acceleration, and vertical acceleration), or angular velocity (angular velocity of yaw angle, roll angle, and pitch angle), and calculates an index value that is a value indicating the magnitude of the behavior of the vehicle.

[0032] For example, the data processing unit 63 performs smoothing, absolute value conversion, and differentiation on the measurement data of vehicle speed, acceleration, or angular velocity to calculate the absolute value of acceleration, the jerk of the absolute value of acceleration (jerk), or the jerk of the absolute value of angular velocity (angular acceleration). The calculated absolute values ​​of acceleration, angular velocity, jerk, or angular acceleration become larger as the vehicle behavior becomes larger, and smaller as the behavior becomes smaller, and are used as index values ​​indicating the magnitude of the vehicle behavior. In particular, by using the absolute value of jerk or angular acceleration as the index value, the influence of changes in vehicle speed, acceleration, or angular velocity due to the trajectory of the road or the acceleration / deceleration of other vehicles is reduced, allowing for more accurate evaluation of changes in vehicle behavior caused by the driver's driving operation state.

[0033] 3 is an explanatory diagram showing an example of data conversion processing by the data processing unit 63. FIG. 3 shows an example in which a lateral jerk value obtained from measurement data of lateral acceleration detected by an acceleration sensor serving as one of the vehicle behavior measurement devices 11 is calculated as an index value indicating the magnitude of vehicle behavior. Specifically, the data processing unit 63 performs smoothing processing and absolute value conversion processing on the measurement data of lateral acceleration detected by the acceleration sensor to convert it into data of the absolute value of lateral acceleration. Furthermore, the data processing unit 63 performs time differentiation processing on the data of the absolute value of lateral acceleration to convert the measurement data of lateral acceleration into data of the absolute value of lateral jerk (lateral jerk) to use it as an index value.

[0034] The data processing unit 63 may calculate one index value using multiple data items selected from the acceleration, angular velocity, jerk, and absolute values ​​of angular acceleration. In this case, the data processing unit 63 may replace the values ​​of each piece of data used with the same index (for example, a value between 0 and 100), and use the average value of the values ​​obtained by replacing all the values ​​of the data used with the same index as the index value. In this case, each type of data may be weighted.

[0035] In this embodiment, an example will be described in which the data processing unit 63 acquires measurement data of the lateral acceleration detected by an acceleration sensor and calculates the lateral jerk as an index value indicating the magnitude of the vehicle behavior.

[0036] (Behavior stability determination unit) The behavior stability determination unit 65 of the processing unit 53 executes a process of determining the behavior stability of the vehicle while the driver is driving the vehicle. In this embodiment, the behavior stability determination unit 65 determines the behavior stability of the vehicle by comparing an index value indicating the magnitude of the vehicle's behavior, which is calculated while the vehicle is traveling, with a predetermined threshold value set by the condition setting unit 69. More specifically, in this embodiment, the behavior stability determination unit 65 determines that the behavior stability of the vehicle is low when the number of times the index value exceeds the predetermined threshold value reaches a predetermined reference number.

[0037] Furthermore, the behavior stability determination unit 65 generates a trigger signal as command information for changing the auditory stimulation each time the vehicle travels for a predetermined period or a predetermined section while the behavior stability of the vehicle is high. In other words, the behavior stability determination unit 65 generates a trigger signal for changing the auditory stimulation each time the predetermined period or predetermined section has elapsed since starting to count the predetermined period or predetermined section without the number of times the index value has exceeded a predetermined threshold reaching a predetermined reference number. The count for the predetermined period or predetermined section is reset and then counted up again when the predetermined period or predetermined section has elapsed and when the number of times the index value has exceeded the predetermined threshold reaches a predetermined reference number.

[0038] The predetermined period or predetermined section for determining whether the vehicle's behavioral stability is maintained at a high level may be, for example, a period defined by a driving time, a section defined by a driving distance, or a section defined by an intersection with a traffic light. By changing the auditory stimulus for each such period or section while the vehicle's behavioral stability is maintained at a high level, the driver can be guided to continue driving operations that result in high vehicle behavioral stability while preventing the driver from adapting to the stimulus that is continuously output.

[0039] The predetermined period or the predetermined section may be a specific section set in advance. For example, to evaluate the stability of the driver's steering operation state, it is preferable to set the section as a straight section with a continuous straight line of at least a predetermined distance, or a turning section with a continuous curve of a certain curvature. To evaluate the driver's accelerator operation state or brake operation state, it is preferable to set the section as a straight section with a continuous straight line of at least a predetermined distance. Furthermore, the predetermined period or the predetermined section may be a section defined by a city, ward, town, village, speed limit, road type (general road, urban expressway, intercity expressway, etc.), etc. Whether or not the vehicle has traveled through these specific sections can be determined based on vehicle position information detected by a position detection system such as a GPS (Global Positioning System) and map data from a navigation system.

[0040] Furthermore, the behavior stability determination unit 65 may determine the behavior stability using one threshold, or may determine the level of behavior stability using multiple thresholds. When determining the behavior stability using one threshold, the behavior stability determination unit 65 can determine that the behavior stability has decreased when the number of times the index value has exceeded the threshold reaches a reference number. When determining the behavior stability using two thresholds, the behavior stability determination unit 65 can determine the degree of decrease in behavior stability based on which of the different thresholds the index value has exceeded the reference number of times. In this case, the behavior stability determination unit 65 may generate different trigger signals depending on which of the thresholds the index value has exceeded the reference number of times, thereby varying the way in which the auditory stimulation is changed.

[0041] The threshold value used to determine the vehicle's behavior stability may be a variable value set based on the level of the driving skill of each driver. The smaller the threshold value, the smaller the vehicle's behavior needs to be to increase the behavior stability, and the more stable the vehicle's behavior can be induced. Instead of or in addition to the threshold value, the reference number of times used to determine the vehicle's behavior stability may also be set based on the level of the driver's driving skill. Note that a method for setting the threshold value for determining the vehicle's behavior stability based on the level of the driver's driving skill will be described in detail in the section on the condition setting unit 69.

[0042] Fig. 4 is an explanatory diagram showing an example of processing by the behavior stability determination unit 65. Fig. 4 shows an example of generating a trigger signal for changing the auditory stimulation each time the vehicle travels for a predetermined period (time) while the behavior stability of the vehicle is high.

[0043] As shown in Fig. 4, behavior stability determination unit 65 determines whether the absolute value (index value) of the lateral jerk exceeds threshold value thre_A while the vehicle is being driven. Behavior stability determination unit 65 counts the number of times that the index value exceeds threshold value thre_A in each of periods seg1 to seg5. In the example shown in Fig. 4, the reference number of times is set to four so that the behavior stability of the vehicle is determined to be low when the number of times that the index value exceeds threshold value thre_A reaches four.

[0044] In the first period seg1 and the fifth period seg5, the predetermined period T elapsed without the index value exceeding the threshold value thre_A, so the behavior stability determination unit 65 generates a trigger signal when the first period seg1 and the fifth period seg5 elapsed. In the second period seg2 and the fourth period seg4, the predetermined period T elapsed without the index value exceeding the threshold value thre_A four times, so the behavior stability determination unit 65 generates a trigger signal when the second period seg2 and the fourth period seg4 elapsed. On the other hand, in the third period seg3, the index value exceeded the threshold value thre_A four times before the predetermined period T elapsed. Therefore, the behavior stability determination unit 65 resets the count of the predetermined period T when the index value exceeded the threshold value thre_A four times and starts counting again.

[0045] Instead of generating a trigger signal when the index value exceeds the threshold value thre_A even once, a trigger signal is generated when the number of times the index value exceeds the threshold value thre_A reaches a reference number. This makes it possible to determine that the vehicle's behavior stability is maintained at a high level if the vehicle's behavior is kept small throughout each period, even if the vehicle's behavior momentarily becomes large. This makes it easier for the driver to feel a sense of accomplishment.

[0046] FIG. 5 shows an example in which a threshold value thre_B smaller than the threshold value thre_A used in FIG. 4 is set when the driver has high driving skills. In this case, even if the value of the lateral jerk (index value) is the same as in FIG. 4, the number of times the index value exceeded the threshold value thre_A before the predetermined period T has elapsed reaches four not only in the third period seg3 but also in the second period seg2 and the fourth period seg4. Therefore, the behavior stability determination unit 65 resets the count for the predetermined period when the number of times the index value exceeded the threshold value thre_A reaches four, and starts counting again. Therefore, for a driver with high driving skills, the number of times the auditory stimulus changes decreases even if the index value shows the same change. This increases the motivation of drivers with high driving skills to change the auditory stimulus, thereby increasing their motivation to improve their driving skills.

[0047] (Output control section) The output control unit 67 of the processing unit 53 executes processing to drive the output device 21 to output auditory stimuli. Specifically, after the start of the processing to output auditory stimuli, the output control unit 67 continuously outputs auditory stimuli from one or more sound sources and changes the auditory stimuli based on a trigger signal generated by the behavior stability determination unit 65. As a result, the auditory stimuli are output while changing each time the vehicle travels for a predetermined period or a predetermined section while the behavior stability of the vehicle is high. This makes the driver aware that the behavior stability of the vehicle is being maintained at a high level, and maintains their motivation to improve their driving skills.

[0048] For example, after the process of outputting auditory stimuli is started, the output control unit 67 continuously outputs auditory stimuli of a predetermined pattern made up of one or more sound sources, and changes the output pattern from one or more sound sources in accordance with a preset rule each time a trigger signal is generated by the behavior stability determination unit 65. Changing the output pattern from the sound sources includes, for example, changing at least one of the volume (including on / off of output), output timing, output order, or pitch of each sound source. Also, changing the output pattern from the sound sources may include increasing the number of sound sources.

[0049] The auditory stimulus to be output may be a sound that does not cause discomfort to the driver, such as a chord consisting of multiple sounds with different pitches, types, or tones. However, the auditory stimulus to be output is not limited to these examples and may be, for example, the sound of winning medals, the sound of applause, or the sound of fireworks. When outputting such auditory stimuli, the output pattern can be changed by, for example, changing the number of medals won, the number of people clapping, or the number of fireworks, or by changing the volume or pitch. Furthermore, when the auditory stimulus is the sound of winning medals, the sound of applause, or the sound of fireworks, the speed of the output sound may be changed.

[0050] Furthermore, the auditory stimuli to be output may be, for example, a combination of a basic pattern sound whose output pattern does not change and a variable pattern sound whose output pattern changes, so as not to cause discomfort or strangeness to the driver even when the auditory stimuli change. In this case, the output control unit 67 may output the basic pattern sound with a constant rhythm and tempo, while changing the output pattern of the variable pattern sound. Note that the rhythm and tempo are examples of elements of changes in auditory stimuli perceived by humans, such as the beat of the periodic progression of the output auditory stimuli and the length of each beat, and other elements of the auditory stimuli may also be changed.

[0051] 6 and 7 are explanatory diagrams showing examples of output patterns of auditory stimuli. In the examples shown in Fig. 6 and 7, the output control unit 67 uses eight sound sources SS1 to SS8 to repeatedly output the eight sound sources SS1 to SS8 in an eighth note rhythm. The auditory stimuli are, for example, drum sounds made up of the eight sound sources SS1 to SS8: open hi-hat, closed hi-hat, clap, kick (bass drum), snare, tom-tom, crash cymbal, and ride cymbal.

[0052] 6 shows the output timing of each sound source SS1 to SS8. In the illustrated output pattern, sound source SS4 is the kick, for example, and is set as a so-called four-on-the-floor, eighth-note rhythm pattern. Flags 1 to 8 are set, each corresponding to a beat, with flags 1 to 4 constituting the first measure and flags 5 to 8 constituting the second measure.

[0053] FIG. 7 shows the setting data for the output timing and volume of each sound source SS1 to SS8. The value of each cell indicates the volume of each sound source SS1 to SS8 output at each beat. For the volume, "0" means muted and "1" means maximum volume. As shown in FIG. 7, the four sound sources SS1 to SS4 are set as sound sources with a basic pattern that does not change regardless of the vehicle's behavioral stability, while the four sound sources SS5 to SS8 are set as sound sources with a changing pattern that changes appropriately when the vehicle has been traveling for a predetermined period with high behavioral stability.

[0054] That is, the output volume of each beat of the sound sources SS5 to SS8 in the change pattern changes in 0.1 increments within the range of "0" to "1" in accordance with the trigger signal generated by the behavior stability determination unit 65. Depending on whether the output volume of each sound source SS5 to SS8 in each beat is set to "0" or "0.1 to 1.0", it is possible to change not only the output volume of each sound source SS5 to SS8 but also the output timing and output order.

[0055] Furthermore, instead of or in addition to changing the output patterns of sound sources SS5 to SS8 of the varying patterns, the tempo (BPM) of the entire auditory stimulation including the basic pattern and the varying patterns may be changed in accordance with the trigger signal generated by behavior stability determination unit 65. The way in which the auditory stimulation is changed based on the trigger signal may be set randomly or may be set in advance by a program.

[0056] (Condition setting section) The condition setting unit 69 of the processing unit 53 sets conditions for determining the behavior stability by the behavior stability determination unit 65. In this embodiment, the condition setting unit 69 sets a threshold value for determining the behavior stability of the vehicle based on information on the attributes of the driver input from the input device 13.

[0057] Specifically, the condition setting unit 69 sets the threshold to a smaller value as the estimated driving skill is higher, and sets the threshold to a larger value as the estimated driving skill is lower, based on information related to the driver's driving skill acquired as information on the driver's attributes. As a result, for example, in the case of a driver with high driving skill and stable vehicle behavior, the threshold is set to a smaller value, and in order to be determined as having high behavior stability, the vehicle behavior needs to be more stable than that of a driver with low driving skill. Therefore, a driver with high driving skill can be guided to further stabilize the vehicle behavior. On the other hand, a driver with low driving skill can be guided to an appropriate level of behavior stability according to the driver's driving skill.

[0058] As information on the driver's attributes related to the driver's driving skills, at least one of the following information acquired via the input device 13 is used: the driver's age, the number of years since obtaining a license, driving frequency, the number of years since the last drive, etc. In other words, if the driver's age is, for example, 70 years or older, the threshold is increased because there is a high possibility that the driver's driving skills have deteriorated. Also, the longer the number of years since obtaining a license, the higher the driving skills are estimated to be, so the threshold is decreased. Also, the more frequently the driver drives, the higher the driving skills are estimated to be, so the threshold is decreased. Also, the longer the number of years since the last drive (number of blank years) is, the higher the possibility that the driving skills have deteriorated, so the threshold is increased.

[0059] Furthermore, the condition setting unit 69 may adjust the threshold value based on data on behavioral stability during past driving by the same driver, in addition to information acquired via the input device 13. For example, the condition setting unit 69 may use information on the number or frequency at which the index value calculated by the data processing unit 63 exceeded the threshold value during past driving by the same driver. In this case, the threshold value is reduced because the fewer the number or frequency at which the index value exceeded the threshold value, the higher the driving skill is estimated to be.

[0060] Furthermore, the condition setting unit 69 may set a reference number of times to be used when the data processing unit 63 calculates an index value indicating the magnitude of the vehicle's behavior, instead of or in addition to the threshold value for determining the vehicle's behavior stability, based on the information on the driver's attributes. Specifically, the condition setting unit 69 decreases the reference number of times as the driver's driving skill estimated from the information on the driver's attributes increases, and increases the reference number as the driver's driving skill decreases. As a result, for example, a driver with high driving skill and stable vehicle behavior needs to maintain a smaller vehicle behavior than a driver with low driving skill in order to be determined to have high behavior stability. Therefore, a driver with high driving skill can be guided to further stabilize the vehicle's behavior. On the other hand, a driver with low driving skill can be guided to an appropriate level of behavior stability according to the driver's driving skill.

[0061] Furthermore, the condition setting unit 69 may set conditions for data processing by the data processing unit 63 based on the information on the driver's attributes. For example, the condition setting unit 69 may set the number of types of data to be used when the data processing unit 63 calculates an index value indicating the magnitude of the vehicle's behavior based on the information on the driver's attributes. Specifically, the condition setting unit 69 increases the number of types of data to be used for calculating the index value as the driver's driving skill estimated from the information on the driver's attributes increases, and decreases the number of types of data to be used for calculating the index value as the estimated driver's driving skill decreases. As a result, for example, in the case of a driver with high driving skill and stable vehicle behavior, the behavior stability is determined based on a larger number of types of data, and the driver can be guided to further stabilize the vehicle's behavior. On the other hand, for a driver with low driving skill, the behavior stability is determined based on a relatively smaller number of data, and the driver can be guided to an appropriate level of behavior stability according to the driver's driving skill.

[0062] Even when the types of data used to calculate the index value are increased or decreased, regardless of the number of types of data used, the driver's steering operation state can be more easily evaluated by preferentially using data on lateral jerk or angular acceleration of yaw angle.Furthermore, the driver's accelerator operation and brake operation state can be more easily evaluated by preferentially using data on longitudinal jerk or angular acceleration of roll angle.

[0063] FIG. 8 is an explanatory diagram showing an example of a method for setting a threshold value and a reference number of times based on information on the attributes of a driver and a method for increasing or decreasing the type of data used to calculate an index value. As shown in Figure 8, when the driver's age is classified as elderly and exceeds a predetermined age, the threshold is increased by a predetermined number and the types of data used to calculate the index value are reduced. Furthermore, the longer the number of years since obtaining a driver's license, the smaller the threshold is increased by a predetermined number and the types of data used to calculate the index value are increased. On the other hand, the shorter the number of years since obtaining a driver's license, the larger the threshold is increased by a predetermined number and the types of data used to calculate the index value are reduced. Furthermore, the more frequently the driver drives, the smaller the threshold is decreased by a predetermined number and the types of data used to calculate the index value are increased. On the other hand, the less frequently the driver drives, the larger the threshold is increased by a predetermined number and the types of data used to calculate the index value are reduced. Furthermore, the longer the number of years since the last drive (number of blank years) is, the larger the threshold is increased by a predetermined number and the types of data used to calculate the index value are reduced.

[0064] For example, when evaluating behavioral stability using a single threshold, the condition setting unit 69 increases or decreases the threshold and increases or decreases the number of types of data based on information about the driver's attributes relative to a preset reference value of the threshold. For example, when calculating an index value from 0 to 100, the reference value of the threshold may be set to 50, and the threshold may be increased or decreased by multiplying it by a coefficient less than or greater than 1 based on each piece of information. Alternatively, when the data usable for evaluating behavioral stability are set to 12, namely, longitudinal acceleration, lateral acceleration, vertical acceleration, angular velocity of yaw angle, angular velocity of pitch angle, angular velocity of roll angle, longitudinal jerk, lateral jerk, vertical jerk, angular acceleration of yaw angle, angular acceleration of pitch angle, and angular acceleration of roll angle, the number of data to be used may be set by increasing or decreasing the number of data by one based on each piece of information. However, the threshold and the number of types of data are increased or decreased within preset maximum and minimum ranges, respectively. In this way, conditions for data processing by the data processing unit 63 and behavioral stability determination processing by the behavior stability determination unit 65 are set.

[0065] Increasing or decreasing the threshold value can be replaced by increasing or decreasing the reference count. Alternatively, both the threshold value and the reference count may be changed. Note that the coefficients used when increasing or decreasing the threshold value or the reference count, and the coefficients used when increasing or decreasing the number of data types, may be constant regardless of the information, or may be weighted according to the information.

[0066] <1-3. Processing operations of driving assistance device> So far, an example of the configuration of the driving assistance device 1 according to this embodiment has been described. Next, a specific example of the processing operation of the driving assistance device 1 will be described. In the following example, an example will be described in which auditory stimuli are output while being changed each time the vehicle travels for a predetermined period (time) with high behavioral stability, using the auditory stimulus output patterns shown in Figures 6 and 7.

[0067] FIG. 9 is a flowchart showing a main routine of processing by the processing unit 53 of the information processing device 50. First, the processing unit 53 determines whether to start execution of a process for presenting the driver's behavior stability through auditory stimuli to the driver (hereinafter also referred to as "auditory stimulus output process") (step S11). The condition for starting execution of the auditory stimulus output process is not particularly limited. For example, if the auditory stimulus output process is constantly executed while the vehicle's driving system is activated, the processing unit 53 may determine to start execution of the auditory stimulus output process when the driving system is activated. Alternatively, the processing unit 53 may determine to start execution of the auditory stimulus output process when it is detected that the driver has sat in the driver's seat based on an output signal from a driver imaging camera or a load sensor installed in the driver's seat. Furthermore, if an occupant such as the driver can switch on / off the execution of the auditory stimulus output process, the processing unit 53 may determine to start execution of the auditory stimulus output process when the execution of the auditory stimulus output process is switched from off to on.

[0068] When it is determined that the execution of the auditory stimulation output process is not to be started (S11 / No), the processing unit 53 repeatedly executes the determination process of step S11. When it is determined that the execution of the auditory stimulation output process is to be started (S11 / Yes), the processing unit 53 executes the condition setting process (step S13).

[0069] FIG. 10 is a flowchart showing a routine for the condition setting process. In the condition setting process, first, the acquisition unit 61 acquires information on the driver's attributes transmitted from the input device 13 (step S31). For example, the acquisition unit 61 acquires at least one of the following information: the driver's age, the number of years since obtaining a driver's license, driving frequency, the number of years since the last driving, etc. This information may be information input in the form of a questionnaire in which the driver answers questions presented by the information processing device 50, or may be information in which data obtained by determining or accumulating this information in advance is input. Furthermore, the acquisition unit 61 may acquire data on evaluations of past driving operation states of the same driver from the storage unit 55.

[0070] Next, the condition setting unit 69 sets the number and type of data to be used in determining the vehicle's behavior stability based on the acquired information on the driver's attributes (step S33). In this embodiment, the number of data to be used in determining the behavior stability is set according to the setting example shown in Fig. 8. For example, the usable data is set to 12, namely, longitudinal acceleration, lateral acceleration, vertical acceleration, angular velocity of yaw angle, angular velocity of pitch angle, angular velocity of roll angle, longitudinal jerk, lateral jerk, vertical jerk, angular acceleration of yaw angle, angular acceleration of pitch angle, and angular acceleration of roll angle, and the number of data to be used in determining the behavior stability is set from these data.

[0071] According to the setting example shown in Fig. 8, the higher the driver's driving skill is estimated to be based on the information on the driver's attributes, the more data to be used, whereas the lower the driver's driving skill is estimated to be, the less data to be used. For example, the condition setting unit 69 sets the number of data to be used by adding or subtracting 1 for each piece of information, with 5 as a reference value, with the minimum number set to 1 and the maximum number set to 12. In this case, the condition setting unit 69 preferentially sets, as data to be used, longitudinal jerk, lateral jerk, angular acceleration of yaw angle, and angular acceleration of pitch angle, which more effectively reflect the influence of the driver's driving operation state. Alternatively, the condition setting unit 69 may set, as data to be used, data corresponding to the behavior to be evaluated, either the longitudinal behavior or the lateral behavior of the vehicle body.

[0072] Next, the condition setting unit 69 sets a threshold value thre_A based on the acquired information on the driver's attributes (step S35). In this embodiment, the threshold value thre_A is set according to the setting example shown in FIG. 8. When calculating one index value using multiple data, each piece of data used is replaced with the same index (for example, a value between 0 and 100), and the average value of all the data used is used as the index value. The condition setting unit 69 determines the threshold value thre_A by multiplying each piece of information by a coefficient greater than or less than 1, with a reference value of 50. However, the method for determining the index value when multiple data are used and the method for setting the threshold value thre_A are not limited to this example.

[0073] According to the setting example shown in Fig. 8, the threshold value thre_A is set to a smaller value as the driver's driving skill is estimated to be higher based on the information on the driver's attributes, while the threshold value thre_A is set to a larger value as the driver's driving skill is estimated to be lower. Also, the reference number C0 may be set instead of or in addition to the threshold value thre_A. In this case, the reference number C0 is set to a smaller value as the driver's driving skill is estimated to be higher based on the information on the driver's attributes, while the reference number C0 is set to a larger value as the driver's driving skill is estimated to be lower.

[0074] If the driver is configured to be able to select the type of sound to be output as auditory stimulation, the condition setting unit 69 sets the type of sound to be output as auditory stimulation to the selected type of sound. As described above, in this embodiment, the type of sound to be output as auditory stimulation is set to the drum sound shown in Figures 6 and 7.

[0075] 9, after performing the condition setting process in step S13, the output control unit 67 of the processing unit 53 starts outputting auditory stimuli (step S15). The output control unit 67 may start outputting auditory stimuli in a preset output pattern of each of the sound sources SS1 to SS8, or may arbitrarily set the output pattern of the auditory stimuli at the start of output. The output control process will be described in detail later together with the output change process.

[0076] Next, the behavior stability determination unit 65 of the processing unit 53 executes a process for determining the behavior stability of the vehicle (step S17). Fig. 11 is a flowchart showing a routine for the behavior stability determination process. First, the behavior stability determination unit 65 resets a timer counter CT that measures a predetermined period and a counting counter C that counts the number of times the behavior of the vehicle has become unstable (step S41).

[0077] Next, the acquisition unit 61 acquires data indicating the behavior of the vehicle transmitted from the vehicle behavior measurement device 11 (step S43). In this embodiment, the acquisition unit 61 acquires data on the vehicle speed, longitudinal acceleration, lateral acceleration, vertical acceleration, angular velocity of the roll angle, angular velocity of the pitch angle, and angular velocity of the yaw angle.

[0078] Next, the data processing unit 63 performs smoothing, absolute value conversion, and differentiation on each piece of acquired data to calculate an index value indicating the magnitude of the vehicle's behavior (step S45). At this time, the data processing unit 63 may perform data processing on only the number and type of data set in the condition setting process of step S13 to calculate the index value. Alternatively, the data processing unit 63 may perform data processing on all data indicating the magnitude of the vehicle's behavior and calculate the index value using only the number and type of data set in the condition setting process of step S13. Furthermore, in this embodiment, the data processing unit 63 replaces each piece of data used with the same index (for example, a value from 0 to 100) and sets the average value of all the data used as the index value.

[0079] Next, the behavior stability determination unit 65 determines whether the calculated index value exceeds a threshold value thre_A (step S47). If the index value exceeds the threshold value thre_A (S47 / Yes), the behavior stability determination unit 65 counts up (increments by 1) the timer counter CT and the counting counter C (step S49). Next, the behavior stability determination unit 65 determines whether the counter value of the counting counter C has reached a reference number of times C0 (step S51). If the counter value of the counting counter C has not reached the reference number of times C0 (S51 / No), the behavior stability determination unit 65 determines whether the counter value of the timer counter CT has reached a designated value for determining a predetermined period of time (step S53). The designated value is set to a value corresponding to an appropriate time period of, for example, 2 to 10 seconds. However, the predetermined period is not limited to the range of 2 to 10 seconds.

[0080] If the counter value of the timer counter CT has not reached the specified value (S53 / No), the processing unit 53 returns to step S43 and continues the behavior stability determination process. On the other hand, if the counter value of the timer counter CT has reached the specified value (S53 / Yes), the processing unit 53 returns to step S41, resets the timer counter CT and the counting counter C, and continues the behavior stability determination process.

[0081] On the other hand, in the above step S51, if the counter value of the counting counter C has reached the reference number C0 (S51 / Yes), the behavior stability determination unit 65 determines whether or not to terminate the auditory stimulus output process (step S55). For example, if the condition for determining in step S11 that the auditory stimulus output process should be started is not met, the behavior stability determination unit 65 determines to terminate the auditory stimulus output process. If it is determined to terminate the auditory stimulus output process (S55 / Yes), the behavior stability determination unit 65 stops the behavior stability determination process and terminates this routine (step S63).

[0082] On the other hand, if it is not determined that the auditory stimulation output process should be terminated (S55 / No), the processing unit 53 returns to step S41, resets both the timer counter CT and the counting counter C, and continues the behavior stability determination process, since it has been determined that the vehicle's behavior stability has become low before the specified period of time has elapsed in which the counter value of the timer counter CT reaches the specified value.

[0083] In the above step S47, if the index value is equal to or less than the threshold value thre_A (S47 / No), the behavior stability determination unit 65 counts up the timer counter CT (step S57). Next, the behavior stability determination unit 65 determines whether the counter value of the timer counter CT has reached a designated value for determining whether a predetermined period has elapsed (step S59).

[0084] If the counter value of the timer counter CT has not reached the specified value (S59 / No), the behavior stability of the vehicle is not yet in a low state, but the predetermined period has not yet elapsed, so the processing unit 53 returns to step S43 and continues the behavior stability determination process. On the other hand, if the counter value of the timer counter CT has reached the specified value (S59 / Yes), the behavior stability determination unit 65 generates a trigger signal for changing the auditory stimulation (step S61).

[0085] Next, the behavior stability determination unit 65 determines whether or not to end the auditory stimulus output process (step S55). If it is determined that the auditory stimulus output process should be ended (S55 / Yes), the behavior stability determination unit 65 stops the behavior stability determination process and ends this routine (step S63). On the other hand, if it is not determined that the auditory stimulus output process should be ended (S55 / No), since the vehicle has been traveling for a predetermined period with high behavior stability, the processing unit 53 returns to step S41, resets both the timer counter CT and the counting counter C, and continues the behavior stability determination process.

[0086] By repeating the processes of steps S41 to S63, behavior stability determination unit 65 determines whether the vehicle has traveled for a predetermined period with high behavior stability, and generates a trigger signal when it determines that the vehicle has traveled for a predetermined period with high behavior stability. In this way, behavior stability determination unit 65 can give output control unit 67 a trigger to change the auditory stimulation when the vehicle has traveled for a predetermined period with high behavior stability.

[0087] An example of a flowchart for a case in which the auditory stimulation is changed each time the vehicle travels a predetermined section while the vehicle's behavioral stability is high, instead of changing the auditory stimulation each time the vehicle travels a predetermined period while the vehicle's behavioral stability is high, is shown in Figure 12. As described above, the predetermined section may be a section defined by a travel distance, or a section defined by an intersection with a traffic light, and may be set based on any appropriate criteria.

[0088] When a predetermined interval is used instead of a predetermined period, time measurement processing using a timer counter CT is unnecessary, so step S57 in the flowchart of Fig. 11 is omitted, and step S41 and step S49 are replaced with step S201 and step S203 in the flowchart of Fig. 12. Furthermore, step S53 and step S57 in the flowchart of Fig. 11 are replaced with step S205 and step S207, which determine whether or not the predetermined interval has been passed.

[0089] Returning to Fig. 9, while the process for determining the behavioral stability of the vehicle is being executed, the output control unit 67 of the processing unit 53 executes a process for changing the auditory stimulus to be output (step S19). Here, the process for outputting the auditory stimulus while changing the auditory stimulus by the output control unit 67 will be described in detail. Below, the basic process for outputting the auditory stimulus in accordance with the rhythm pattern shown in Fig. 6 will be described with reference to Fig. 13, and then the process for changing the auditory stimulus will be described with reference to Fig. 14.

[0090] FIG. 13 is a flowchart showing the basic process of outputting auditory stimulation in accordance with the rhythm pattern shown in FIG. After starting the output control process, the output control unit 67 first sets the beat for outputting sound to the first beat (step S71). Next, the output control unit 67 adjusts the timing for outputting the sound set in the first flag on the first beat (step S73). Next, the output control unit 67 outputs the sound set in the first flag when the adjusted output timing arrives (step S75). Thereafter, until the auditory stimulation output process is terminated, the output of sounds on the first to eighth beats is repeated while setting the beat, adjusting the output timing, and outputting the sound on each beat (steps S71 to S119). When the output control unit 67 determines to terminate the auditory stimulation output process (S119 / Yes), it stops the output control process and terminates this routine (step S121).

[0091] The adjustment of the timing of sound output is a process performed to ensure that the intervals at which eighth note sounds are output are constant. For example, if the processor's processing speed, such as for switching beat settings, is fast and the time lag is negligible to the human sense of time, the output control unit 67 waits for the time corresponding to the beat interval before outputting the sound. On the other hand, if the processor's processing speed is not constant, the output control unit 67 may wait for the sound output so that the elapsed time from the sound output time of the previous beat is equal to the beat interval. For example, if the beat interval is dT, the output control unit 67 stores the time T(n-1) at which the sound was output on the previous beat, and sets the wait time to dT-(Tnow-T(n-1)), which is the time elapsed from the time T(n-1) to the time Tnow at which the wait time is set, from the beat interval dT. This ensures that the intervals at which sounds are output on each beat are constant.

[0092] FIG. 14 is a flowchart showing the process of changing the auditory stimulation (output change process) when the behavior stability determination unit 65 generates a trigger signal. The output control unit 67 determines whether or not a trigger signal has been generated by the behavior stability determination unit 65 (step S131). If a trigger signal has not been generated (S131 / No), the output control unit 67 determines whether or not to end the auditory stimulation output process (step S137), and repeats the determination of step S131 while it is not determined to end the auditory stimulation output process (S137 / No).

[0093] If a trigger signal is generated (S131 / Yes), the output control unit 67 checks the setting of the current beat (step S133). Then, the output control unit 67 changes the output sound for the beats following the current beat (step S135). The way in which the output sound is changed is determined, for example, according to a preset program. For example, the sound sources SS5 to SS8 set in the change pattern may be changed in the order of their sound source numbers, or may be changed randomly. In this case, the output volume level of each of the sound sources SS5 to SS8 may be switched to 0 or 1 to switch between output and stop, or the output volume level may be switched between 0 and 1 to change the volume. In this case, the output volume level may be gradually increased or decreased at equal intervals, may be gradually increased or decreased at unequal intervals, or may be changed randomly. In addition, the output control unit 67 may further add a type of sound source (SS9-) or change the number of bars to be repeated.

[0094] Next, the output control unit 67 determines whether or not to end the auditory stimulus output process (step S137). If it is determined that the auditory stimulus output process should be ended (S137 / Yes), the output control unit 67 stops the output change process and ends this routine (step S139). On the other hand, if it is not determined that the auditory stimulus output process should be ended (S137 / No), the output control unit 67 returns to step S131 and continues the output change process. In this way, the output control unit 67 changes the auditory stimulus every time a trigger signal is generated by the behavior stability determination unit 65 while outputting the auditory stimulus in a predetermined rhythmic pattern.

[0095] 9, the processing unit 53 determines whether to terminate the auditory stimulus output process (step S21) while executing the behavior stability determination process by the behavior stability determination unit 65 (step S17) and the output change process by the output control unit 67 (step S19). For example, if the condition for determining to start the auditory stimulus output process in step S11 is not met, the processing unit 53 determines to terminate the auditory stimulus output process. If it is not determined to terminate the auditory stimulus output process (S21 / No), the processing unit 53 returns to step S17 and repeatedly executes the behavior stability determination process and the output change process. On the other hand, if it is determined to terminate the auditory stimulus output process (S21 / Yes), the processing unit 53 stops the auditory stimulus output process and terminates this routine (step S23).

[0096] <1-4. Effects of this embodiment> As described above, the driving assistance device 1 according to this embodiment acquires information indicating vehicle behavior while the vehicle is traveling, and outputs auditory stimuli while changing the auditory stimuli each time the vehicle travels for a predetermined period while the vehicle's behavioral stability, obtained from the acquired information, is high. This allows the driver to recognize the vehicle's behavioral stability in real time while driving. Furthermore, because the auditory stimuli do not include text information such as display or voice, the driver can intuitively recognize the behavioral stability through the auditory stimuli, thereby preventing a decline in attention. Furthermore, because the auditory stimuli change each time the vehicle travels for a predetermined period while the behavioral stability is high, the driver is not given the impression that their driving is being denied, and the effectiveness of improving their driving skills can be prevented from decreasing. Furthermore, because the driver is exposed to stimulating changes while the vehicle's behavior is stable, this stimulating change motivates the driver to perform driving operations that will result in more stable vehicle behavior.

[0097] Furthermore, the driving assistance device 1 according to this embodiment compares an index value obtained from measurement data acquired while the vehicle is traveling with a predetermined threshold, and uses the number of times the index value exceeds the predetermined threshold as information on the vehicle behavior stability. This prevents the vehicle behavior stability from being determined to have deteriorated when the index value exceeds the threshold only once, and allows the behavior stability due to the driver's driving operation to be correctly evaluated.

[0098] Furthermore, in the driving assistance device 1 according to this embodiment, a threshold value or a reference number of times is set based on information on attributes related to the driver's driving skill. In particular, the higher the driver's driving skill, the lower the threshold value or the lower the reference number of times, and the lower the driver's driving skill, the higher the threshold value or the higher the reference number of times. Therefore, a driver with high driving skill can be guided to a driving operation state that further improves the vehicle's behavior stability. Furthermore, a driver with low driving skill can be guided to a behavior stability level appropriate for the driver's driving skill.

[0099] Furthermore, in the driving assistance device 1 according to this embodiment, the auditory stimulus output process is stopped in a driving environment where the vehicle's behavioral stability is reduced. This prevents the driver from receiving an inaccurate evaluation. Furthermore, it prevents the driver from being guided into an inappropriate driving state based on an inaccurate evaluation.

[0100] Furthermore, the driving assistance device 1 according to this embodiment outputs auditory stimuli by combining a basic sound pattern, whose output pattern does not change, with a variable sound pattern, whose output pattern changes. This allows the auditory stimuli to be changed without causing discomfort or strangeness to the driver, allowing the driver to recognize the stability of the vehicle's behavior.

[0101] In the above embodiment, drum sounds from eight sound sources SS1 to SS8 are used as the output of auditory stimuli. However, as described above, the output of auditory stimuli is not limited to drum sounds and any sound may be output. In this case, the output pattern of auditory stimuli, such as the volume, rhythm, tempo, and output order of the sound sources, may be changed as appropriate for each predetermined period or each predetermined section of travel. This allows the driver to be notified of information regarding the evaluation of the driver's driving performance while driving, without giving the impression that the driver's driving is being negative, and in a manner that can prevent a decline in attention.

[0102] <<2. Second Embodiment>> Next, a driving assistance device according to a second embodiment of the present disclosure will be described. The driving assistance device described in the first embodiment compares an index value indicating the magnitude of the vehicle's behavior with a single threshold value to determine the stability of the vehicle's behavior and change the auditory stimulus (see Figures 4 and 5). In contrast, the driving assistance device according to the second embodiment is configured to compare an index value indicating the magnitude of the vehicle's behavior with multiple threshold values ​​and change the auditory stimulus so that the smaller the maximum index value in each period is, the greater the change made to the auditory stimulus.

[0103] The driving assistance device according to the second embodiment can be configured in the same manner as the driving assistance device 1 according to the first embodiment, except that the auditory stimulation output process is performed using a plurality of thresholds. Below, the processing operations of the driving assistance device according to this embodiment that differ from the processing operations of the driving assistance device 1 according to the first embodiment will be described.

[0104] Fig. 15 is an explanatory diagram showing an example of determining the behavior stability of a vehicle using a first threshold value thre_1 and a second threshold value thre_2 that is smaller than the first threshold value thre_1. Assuming that the value of the lateral jerk (index value) is the same as that in Fig. 4, when the first threshold value thre_1 is set to the same value as the threshold value thre_A shown in Fig. 4, the predetermined period T elapses without the number of times that the index value exceeds the first threshold value thre_1 reaching four in each of the first period seg1, the second period seg2, the fourth period seg4, and the fifth period seg5. Therefore, the behavior stability determination unit 65 generates a trigger signal when each period elapses.

[0105] However, since the predetermined period T elapsed without the index value exceeding the second threshold value thre_2 during the first period seg1 and the fifth period seg5, the behavior stability determination unit 65 generates a second trigger signal when the first period seg1 and the fifth period seg5 elapse. The second trigger signal is a trigger signal indicating that the predetermined period has elapsed without the index value exceeding the relatively small second threshold value thre_2 during each period. Furthermore, during the second period seg2 and the fourth period seg4, although the predetermined period T elapsed without the index value exceeding the first threshold value thre_1 reaching four times, a record of the index value exceeding the second threshold value thre_2 remains. Therefore, the behavior stability determination unit 65 generates a first trigger signal when the second period seg2 and the fourth period seg4 elapse. The first trigger signal is a trigger signal indicating that the vehicle's behavior stability was not determined to be low during each period, but that a record of the index value exceeding the relatively small second threshold value thre_2 was present.

[0106] The output control unit 67 then changes the auditory stimulus in a different way depending on whether the generated trigger signal is a first trigger signal or a second trigger signal. For example, the output control unit 67 changes the auditory stimulus in a different way depending on the trigger signal, such as by changing the number of sound sources that change the output pattern, the range of volume change, or the range of pitch change, so that the driver can recognize the degree of change in the auditory stimulus. Specifically, in the technology disclosed herein, the auditory stimulus is changed when the vehicle's behavioral stability is high, so the change in the auditory stimulus based on the second trigger signal is set to be greater than the change in the auditory stimulus based on the first trigger signal. This allows the driver to intuitively recognize the driving operation status in more detail.

[0107] The number of thresholds that can be set may be three or more. In addition, some or all of the thresholds may be increased or decreased depending on the driving skill of the driver estimated from information related to the driver's attributes, in accordance with the setting example shown in FIG.

[0108] FIG. 16 is a flowchart showing a routine of a behavior determination degree determination process using the first threshold value thre_1 and the second threshold value thre_2, and shows a process that can be replaced with the above-mentioned FIG. First, the behavior stability determination unit 65 resets a timer counter CT that measures a predetermined period and a counting counter C that counts the number of times the vehicle's behavior has become unstable, and turns on a behavior flag that indicates that the index value indicating the magnitude of the behavior is less than or equal to the second threshold value thre_2 (step S141).

[0109] Next, similar to the processing of steps S43 to S45 in FIG. 11, the acquisition unit 61 acquires data indicating the vehicle behavior transmitted from the vehicle behavior measurement device 11 (step S143), and then the data processing unit 63 performs smoothing processing, absolute value conversion processing, and differentiation processing on each of the acquired data, and calculates an index value indicating the magnitude of the vehicle behavior (step S145).

[0110] Next, the behavior stability determination unit 65 determines whether or not the calculated index value exceeds the first threshold value thre_1 (step S147). If the index value exceeds the first threshold value thre_1 (S147 / Yes), the behavior stability determination unit 65 counts up (increments by 1) the counting counter C (step S149). Next, the behavior stability determination unit 65 determines whether or not the counter value of the counting counter C has reached a reference number of times C0 (step S151). If the counter value of the counting counter C has not reached the reference number of times C0 (S151 / No), the processing unit 53 returns to step S143 and continues the behavior stability determination process.

[0111] On the other hand, if the counter value of the counting counter C has reached the reference number C0 (S151 / Yes), the behavior stability determination unit 65 determines whether or not to terminate the auditory stimulus output process (step S153). For example, if the condition for determining in step S11 that the auditory stimulus output process should be started is not met, the behavior stability determination unit 65 determines to terminate the auditory stimulus output process. If it is determined to terminate the auditory stimulus output process (S153 / Yes), the behavior stability determination unit 65 stops the behavior stability determination process and terminates this routine (step S171).

[0112] On the other hand, if it is not determined that the auditory stimulation output process should be terminated (S153 / No), since it has been determined that the vehicle's behavior stability has become low before the predetermined period of time has elapsed in which the counter value of the timer counter CT reaches the specified value, the processing unit 53 returns to step S141, resets both the timer counter CT and the counting counter C, turns on the behavior flag, and continues the behavior stability determination process.

[0113] In the above step S147, if the index value is equal to or less than the first threshold value thre_1 (S147 / No), the behavior stability determination unit 65 counts up the timer counter CT (step S155). Next, the behavior stability determination unit 65 determines whether the obtained index value exceeds the second threshold value thre_2 (step S157). If the index value exceeds the second threshold value thre_2 (S157 / Yes), the behavior stability determination unit 65 turns off the behavior flag (step S159). Next, the behavior stability determination unit 65 determines whether the counter value of the timer counter CT has reached a designated value for determining whether a predetermined period has elapsed (step S161). The designated value is set to a value corresponding to an appropriate time period of, for example, 2 to 10 seconds. However, the predetermined period is not limited to the range of 2 to 10 seconds.

[0114] If the counter value of the timer counter CT has not reached the specified value (S161 / No), the vehicle's behavior stability has not yet reached a low state, but the predetermined period has not yet elapsed, so the processing unit 53 returns to step S143 and continues the behavior stability determination process. On the other hand, if the counter value of the timer counter CT has reached the specified value (S161 / Yes), the behavior stability determination unit 65 generates a first trigger signal for changing the auditory stimulation (step S163).

[0115] Next, the behavior stability determination unit 65 determines whether or not to end the auditory stimulus output process (step S153). If it is determined that the auditory stimulus output process should be ended (S153 / Yes), the behavior stability determination unit 65 stops the behavior stability determination process and ends this routine (step S171). On the other hand, if it is not determined that the auditory stimulus output process should be ended (S153 / No), since the vehicle has been traveling for a predetermined period with high behavior stability, the processing unit 53 returns to step S141, resets both the timer counter CT and the counting counter C, turns on the behavior flag, and continues the behavior stability determination process.

[0116] On the other hand, in the above step S157, if the index value is equal to or less than the second threshold value thre_2 (S157 / No), the behavior stability determination unit 65 determines whether the counter value of the timer counter CT has reached a specified value for determining whether a predetermined period has elapsed, while maintaining the behavior flag setting in the on or off state (step S165).

[0117] If the counter value of the timer counter CT has not reached the specified value (S165 / No), the behavior stability of the vehicle is not yet in a low state, but the predetermined period has not yet elapsed, so the processing unit 53 returns to step S143 and continues the behavior stability determination process. On the other hand, if the counter value of the timer counter CT has reached the specified value (S165 / Yes), the behavior stability determination unit 65 determines whether the current setting of the behavior flag is on (step S167).

[0118] If the behavior flag is set to OFF (S167 / No), the predetermined period T has elapsed without the number of times the index value has exceeded the first threshold thre_1 reaching the reference number, but there is still a record of the index value exceeding the second threshold thre_2, so a first trigger signal is generated (step S163).On the other hand, if the behavior flag is set to ON (S167 / Yes), the predetermined period T has elapsed without the index value exceeding the second threshold thre_2 and without the number of times the index value has exceeded the first threshold thre_1 reaching the reference number, so a second trigger signal is generated (step S169).

[0119] Next, the behavior stability determination unit 65 determines whether or not to end the auditory stimulus output process (step S153). If it is determined that the auditory stimulus output process should be ended (S153 / Yes), the behavior stability determination unit 65 stops the behavior stability determination process and ends this routine (step S169). On the other hand, if it is not determined that the auditory stimulus output process should be ended (S153 / No), since the vehicle has been traveling for a predetermined period with high behavior stability, the processing unit 53 returns to step S141, resets both the timer counter CT and the counting counter C, turns on the behavior flag, and continues the behavior stability determination process.

[0120] By repeating the processes of steps S141 to S171, behavior stability determination unit 65 determines whether the vehicle has traveled for a predetermined period with high behavior stability, and when it determines that the vehicle has traveled for a predetermined period with high behavior stability, generates a first trigger signal or a second trigger signal according to the level of behavior stability. In this way, when the vehicle has traveled for a predetermined period with high behavior stability, behavior stability determination unit 65 can give output control unit 67 a trigger to change the auditory stimulation according to the level of behavior stability.

[0121] FIG. 17 is a flowchart showing the output change process when the behavior stability determining unit 65 generates the first trigger signal or the second trigger signal, and shows the process that can be replaced with the above-mentioned FIG. The output control unit 67 determines whether or not a trigger signal has been generated by the behavior stability determination unit 65 (step S181). If a trigger signal has not been generated (S181 / No), the output control unit 67 determines whether or not to end the auditory stimulation output process (step S191), and repeats the determination of step S181 while it is not determined to end the auditory stimulation output process (S191 / No).

[0122] If a trigger signal is being generated (S181 / Yes), the output control unit 67 checks the setting of the current beat (step S183). Next, the output control unit 67 determines whether the generated trigger signal is a first trigger signal (step S185). If the trigger signal is the first trigger signal (S185 / Yes), the output control unit 67 changes the sound source of one of the output sounds for the beats after the current beat (step S187). On the other hand, if the trigger signal is not the first trigger signal (S185 / No), that is, if the trigger signal is the second trigger signal, the output control unit 67 changes the sound sources of two of the output sounds for the beats after the current beat (step S189).

[0123] The way in which the output sound is changed is determined, for example, according to a preset program. For example, the sound sources SS5 to SS8 set in the change pattern may be changed in the order of their sound source numbers, or may be changed randomly. In this case, the output volume level of each of the sound sources SS5 to SS8 may be switched to 0 or 1 to switch between output and stop, or the output volume level may be switched between 0 and 1 to change the volume. In this case, the output volume level may be gradually increased or decreased at equal intervals, may be gradually increased or decreased at unequal intervals, or may be changed randomly.

[0124] Next, the output control unit 67 determines whether or not to end the auditory stimulus output process (step S191). If it is determined that the auditory stimulus output process should be ended (S191 / Yes), the output control unit 67 stops the output change process and ends this routine (step S193). On the other hand, if it is not determined that the auditory stimulus output process should be ended (S191 / No), the output control unit 67 returns to step S181 and continues the output change process. In this way, the output control unit 67 changes the auditory stimulus in accordance with the first trigger signal or the second trigger signal generated by the behavior stability determination unit 65 while outputting the auditory stimulus in a predetermined rhythmic pattern.

[0125] As described above, in the driving assistance device 1 according to the second embodiment, the behavioral stability level is determined using a plurality of thresholds for determining the behavioral stability of the vehicle, and a trigger signal corresponding to the behavioral stability level is generated, thereby making it possible to provide different changes to the auditory stimulation according to the behavioral stability level. Therefore, in addition to the effects of the driving assistance device 1 according to the above embodiment, it is possible to obtain an effect that the driver can intuitively recognize the driving operation state in more detail. This also motivates the driver to try to improve the behavioral stability of the vehicle, thereby improving the driver's driving skills.

[0126] In addition, the driving assistance device 1 according to the second embodiment may also be configured to change the auditory stimulus each time the vehicle travels a predetermined distance with high behavioral stability, instead of changing the auditory stimulus each time the vehicle travels a predetermined period with high behavioral stability.

[0127] <<3. Third Embodiment>> Next, a driving assistance device according to a third embodiment of the present disclosure will be described. The driving assistance device 1 according to the first and second embodiments outputs auditory stimuli while changing the auditory stimuli each time the vehicle travels for a predetermined period or a predetermined section while the vehicle's behavioral stability is high. Considering a case where the driver drives the vehicle for a long period of time, the driver may become accustomed to the changing pattern of auditory stimuli and adapt to the auditory stimuli. In particular, when the auditory stimuli are output using a basic sound pattern in which the auditory stimuli do not change and a changing sound pattern in which the auditory stimuli change, it is considered that the absence of a change in the basic pattern makes it easier for the driver to adapt to the auditory stimuli.

[0128] Therefore, the driving assistance device 1 of the third embodiment is configured to change the type of auditory stimulation or the basic pattern of sound when the vehicle's driving area changes, when a predetermined period (hereinafter also referred to as the "basic output change period") or predetermined section (hereinafter also referred to as the "basic output change section") set to a longer time or distance has elapsed, or when the user requests a change.

[0129] For example, in the case of the drum sound rhythm illustrated in Figures 6 and 7, the output control unit 67 changes the sound of a basic pattern each time a basic output change period or basic output change section elapses, rather than a sound of a changing pattern that changes each time the vehicle travels for a predetermined period or a predetermined section while the vehicle's behavior stability is high. Furthermore, without being limited to using the drum sound rhythm described above, the output control unit 67 may change the type of auditory stimulus to a different type each time a basic output change period or basic output change section elapses. For example, the output control unit 67 may change the output of an auditory stimulus consisting of a drum sound rhythm to the output of a different type of auditory stimulus, such as a coin acquisition sound, each time a basic output change period or basic output change section elapses.

[0130] Fig. 18 is a flowchart showing an example of the output change processing by the driving assistance device 1 according to this embodiment, which can be replaced with the output change processing shown in Fig. 14. In the example of the processing shown in Fig. 18, processing is executed to change the sound of the basic pattern of the drum sound rhythm shown in Fig. 6 and Fig. 7 every time the basic output change period elapses.

[0131] As shown in Fig. 18, the output change process by the driving assistance device 1 according to this embodiment is the same as the output change process shown in Fig. 14 except that steps S211, S213, and S215 are added to determine whether a predetermined period has elapsed and change the basic pattern sound. Specifically, after starting the auditory stimulation output process, the output control unit 67 resets a second timer counter CT2 for measuring the basic output change period (step S211). The second timer counter CT2 starts counting up after being reset. Note that the timer counter CT for measuring the predetermined period for determining whether the vehicle has traveled for the predetermined period with high behavioral stability is referred to as the first timer counter, and the timer counter for measuring the basic output change period is referred to as the second timer counter CT2.

[0132] Thereafter, the processes of steps S131 to S137 are executed in accordance with the procedure described with reference to the flowchart of Fig. 14. If it is not determined in step S137 that the auditory stimulation output process should be terminated (S137 / No), the output control unit 67 determines whether the counter value of the second timer counter CT2 has reached a second designated value that is set in advance to determine whether the basic output change period has elapsed (step S213). The second designated value may be, for example, 30 minutes or more, but is not particularly limited thereto.

[0133] If the counter value of the second timer counter CT2 has not reached the second specified value (S213 / No), the output control unit 67 returns to step S131 and continues the output change process. On the other hand, if the counter value of the second timer counter CT2 has reached the second specified value (S213 / Yes), the output control unit 67 changes the sound of the basic pattern consisting of the sound sources SS1 to SS4 (step S215). The way in which the sound of the basic pattern is changed is determined, for example, according to a preset program. For example, the rhythm or tempo of the basic pattern is changed to a sound pattern with a different rhythm or tempo. Next, the output control unit 67 returns to step S211, resets the counter value of the second timer counter CT2, and then continues the output change process.

[0134] In addition, when determining that the basic output change section has passed instead of the basic output change period, the driving assistance device 1 can change the basic pattern sound of the auditory stimulation output when it determines that the basic output change section has passed based on the vehicle's position information detected by a position detection system such as GPS and map data of a navigation system.

[0135] As described above, the driving assistance device 1 according to the third embodiment not only changes the auditory stimulation each time the vehicle travels for a relatively short predetermined period or section while the vehicle's behavior stability is high, but also changes the type of auditory stimulation and the basic sound pattern that does not change over a predetermined period or section each time a basic output change period or section that is set to a relatively long time elapses. This prevents the driver from adapting to the auditory stimulation even when driving the vehicle for a long period of time, and helps maintain motivation to improve driving skills.

[0136] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the technology of the present disclosure is not limited to such examples. It is clear that a person skilled in the art of the technology to which the present disclosure pertains can conceive of various modified or altered examples within the scope of the technical ideas described in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure.

[0137] For example, a travel section for evaluating the stability of the vehicle's behavior in the longitudinal direction or the stability of the vehicle's behavior in the lateral direction, or both, may be set in advance, and the driving assistance device 1 may calculate only necessary data from among the longitudinal acceleration, longitudinal jerk, angular velocity of the pitch angle, angular acceleration of the pitch angle, lateral acceleration, lateral jerk, angular velocity of the yaw angle, and angular acceleration of the yaw angle from the start to the end of travel in that section, to evaluate the stability of the desired behavior. This reduces the calculation load on the information processing device 50.

[0138] Furthermore, in each of the above embodiments, the vehicle behavior measurement device 11 of the driving assistance device 1 is a sensor or the like provided in the vehicle, the output device 21 is a speaker system provided in the vehicle, and the information processing device 50 is communicably connected to the vehicle behavior measurement device 11 and the output device 21 via a communication bus such as a CAN, but the technology of the present disclosure is not limited to this example. For example, the driving assistance device 1 may be configured as a mobile terminal device such as a smartphone. Configuring the driving assistance device 1 as a mobile terminal device makes it possible to use auditory stimulation output processing regardless of the vehicle being driven, thereby increasing opportunities for the driver to improve their driving skills and improving their driving skills when driving different vehicle types.

[0139] In this case, a speaker mounted on the mobile terminal device may be used as output device 21, or a speaker system of the vehicle connected to the mobile terminal device via wireless or wired communication means may be used as output device 21. Furthermore, when driving assistance device 1 is configured as a mobile terminal device, sensors such as an acceleration sensor mounted on the mobile terminal device may be used as vehicle behavior measurement device 11. In this case, the information processing device 50 is configured to be able to execute a process of converting the axial direction of the sensor mounted on the mobile terminal device to a predetermined direction so that the vehicle behavior can be accurately estimated using the sensor. For example, when the vehicle is stopped on a horizontal road, the sensor mounted on the mobile terminal device may detect the direction of gravitational acceleration, record information on the deviation between the direction of the gravitational acceleration and the axial direction of the sensor, and convert the axial direction of the sensor to a predetermined direction based on the information on the deviation. Alternatively, during the auditory stimulation output process, a process of guiding the mobile terminal device to be placed in the vehicle so that the axial direction of the sensor mounted on the mobile terminal device coincides with the longitudinal direction or lateral direction of the vehicle may be executed.

[0140] The following aspects also fall within the technical scope of the present disclosure. (1) A driving assistance device in which a processor of the driving assistance device varies the auditory stimulation by changing the rhythm or tempo of the auditory stimulation. (2) A driving assistance device in which the auditory stimuli include sounds of a basic pattern with a constant rhythm and tempo, and the processor of the driving assistance device varies the auditory stimuli by changing the output pattern of sounds other than the basic pattern. [Explanation of symbols]

[0141] 1: driving assistance device, 11: vehicle behavior measurement device, 13: input device, 21: output device, 50: information processing device, 51: communication unit, 53: processing unit, 55: storage unit, 61: acquisition unit, 63: data processing unit, 65: behavior stability determination unit, 67: output control unit, 69: condition setting unit

Claims

1. A driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, one or more processors; and one or more memories communicatively coupled to the one or more processors; the one or more processors: determining a behavior stability of the vehicle based on information indicating the behavior of the vehicle; outputting the auditory stimulus while changing the auditory stimulus every time the vehicle travels for a predetermined period or a predetermined section in a state where the behavioral stability is high; When a predetermined period or a predetermined section has elapsed while the behavior stability is high, command information for changing the auditory stimulation is generated, and the predetermined period or the predetermined section is reset to restart the determination; When it is determined that the behavior stability is not high before the specified period or specified section has elapsed, the driving assistance device resets the specified period or specified section and resumes the determination even before the specified period or specified section has elapsed.

2. A driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, one or more processors; and one or more memories communicatively coupled to the one or more processors; the one or more processors: comparing an index value indicating the magnitude of the vehicle's behavior with a predetermined threshold value, and determining that the vehicle's behavior stability is high when the number of times the index value exceeds the predetermined threshold value is less than a predetermined reference number of times; outputting the auditory stimulus while changing the auditory stimulus every time the vehicle travels for a predetermined period or a predetermined section in a state where the behavioral stability is high; A driving assistance device that increases the change applied to the auditory stimulus as the maximum value of the index value in the predetermined period or predetermined section decreases.

3. A driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, one or more processors; and one or more memories communicatively coupled to the one or more processors; the auditory stimulus is an auditory stimulus output by combining a plurality of sound sources, the one or more processors: determining a behavior stability of the vehicle based on information indicating the behavior of the vehicle; A driving assistance device that outputs the auditory stimulus while changing the auditory stimulus by performing at least one or more of changing the volume of each sound source, changing the output timing of each sound source, changing the output order of each sound source, or changing the pitch of each sound source each time the vehicle travels for a predetermined period or a predetermined section while the behavioral stability is high.

4. A computer program applied to a driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, one or more processors, determining a behavior stability of the vehicle based on information indicating the behavior of the vehicle; outputting the auditory stimulus while changing the auditory stimulus each time the vehicle travels a predetermined period or a predetermined section while the behavioral stability is high, and when the predetermined period or a predetermined section has elapsed while the behavioral stability is high, generating command information to change the auditory stimulus and resetting the predetermined period or the predetermined section to resume the determination, while when it is determined that the behavioral stability is not high before the predetermined period or the predetermined section has elapsed, resetting the predetermined period or the predetermined section and resuming the determination; A computer program that causes a process including the steps of:

5. A computer program applied to a driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, one or more processors, comparing an index value indicating the magnitude of the vehicle's behavior with a predetermined threshold value, and determining that the behavior stability is high when the number of times the index value exceeds the predetermined threshold value is less than a predetermined reference number of times; outputting the auditory stimulus while changing the auditory stimulus each time the vehicle travels for a predetermined period or a predetermined section while the behavioral stability is high, and the smaller the maximum value of the index value in the predetermined period or the predetermined section, the greater the change made to the auditory stimulus; A computer program that causes a process including the steps of:

6. A computer program applied to a driving assistance device that presents vehicle behavior stability to a driver through auditory stimulation, the auditory stimulus is an auditory stimulus output by combining a plurality of sound sources, one or more processors, determining a behavior stability of the vehicle based on information indicating the behavior of the vehicle; outputting the auditory stimulus while changing the auditory stimulus by performing at least one or more of the following each time the vehicle travels for a predetermined period or a predetermined section in a state where the behavioral stability is high: changing the volume of each sound source, changing the output timing of each sound source, changing the output order of each sound source, or changing the pitch of each sound source; A computer program that causes a process including the steps of:

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