Attention warning system and attention warning method

Abstract

To transfer to a driver of an own vehicle the level of risk of collision, which changes over time, between the own vehicle and a preceding vehicle in a mode of high consistency with a subjective view of the driver.SOLUTION: An attention calling system comprises: a THW acquisition section for acquiring an inter-vehicle time, which is a value resulting from dividing an inter-vehicle distance between an own vehicle and a preceding vehicle by a vehicle speed of the own vehicle, iteratively at predetermined time intervals; a TTC acquisition section for acquiring a collision margin time, which is a value resulting from dividing the inter-vehicle distance by a relative speed between the own vehicle and the preceding vehicle, iteratively at predetermined time intervals; and a notification section which outputs, to a crew member of the own vehicle, an approach alarm notifying the crew member of an approach to the preceding vehicle based on the inter-vehicle time and the collision margin time. The notification section determines a saliency level, which is a degree of saliency of the approach alarm, in accordance with the inter-vehicle time and the collision margin time and outputs the approach alarm at the determined saliency level.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an attention calling system and an attention calling method for calling the attention of a vehicle driver. [Background technology]

[0002] In recent years, efforts to provide access to sustainable transport systems that take into consideration vulnerable transport participants have become more active. To achieve this, we are focusing on research and development into preventive safety technologies to further improve road safety and convenience.

[0003] Patent document 1 describes that when a preceding vehicle and a following vehicle are traveling in front of and behind the vehicle, braking control of the vehicle is performed based on the rear-end collision risk Rf calculated from the time gap THWf between the vehicle and the preceding vehicle and the time to collision TTCf, and the rear-end collision risk Rf with the following vehicle calculated from the time gap THWr between the vehicle and the following vehicle and the time to collision TTCr.

[0004] Patent Document 2 describes that automatic braking is initiated when the time to collision (TTC) with the preceding vehicle falls below a predetermined threshold, and that the threshold is changed depending on the relative speed with the preceding vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-262629 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-10893 Summary of the Invention [Problem to be solved by the invention]

[0006] In preventive safety technology, from the standpoint of driver acceptability and understanding, it is a challenge to communicate to the driver of the vehicle the magnitude of the risk of contact between the vehicle and the preceding vehicle, which may change over time, in a manner similar to how the driver intuitively grasps the behavior of the preceding vehicle. In order to solve the above-mentioned problems, the present application aims to communicate to the driver of the vehicle the magnitude of the collision risk between the vehicle and a preceding vehicle, which changes over time, in a manner that is highly consistent with the driver's subjective perception, thereby contributing to the development of a sustainable transportation system. [Means for solving the problem]

[0007] One aspect of the present invention includes a THW acquisition unit that repeatedly acquires, at predetermined time intervals, a time to collision (TTC) ... When the inter-vehicle time becomes equal to or less than a first threshold, the saliency level is set to a first level magnitude that monotonically increases as the inter-vehicle time decreases, and when the inter-vehicle time is equal to or less than the first threshold and the time to collision becomes equal to or less than a second threshold, the saliency level is set to a third level magnitude obtained by adding a second level that monotonically increases as the time to collision decreases to the first level, The aforementioned setting The system outputs the proximity warning with a predetermined level of prominence. Book According to another aspect of the invention, the notification unit calculates the first level that monotonically increases with the inverse of the time to collision, and calculates the second level that monotonically increases with the inverse of the time to collision. According to another aspect of the present invention, the notification unit sets the second level to a larger value as the value of the time headway when the time to collision becomes equal to or smaller than a second threshold value decreases. According to another aspect of the present invention, the notification unit sets the second level to a smaller value when the host vehicle is accelerating than when the host vehicle is not accelerating. Another aspect of the present invention is an attention-attention method executed by a computer of an attention-attention system, the method comprising: a THW acquisition step of repeatedly acquiring, at predetermined time intervals, a time to collision (TTC) ... When the inter-vehicle time becomes equal to or less than a first threshold, the saliency level is set to a first level magnitude that monotonically increases as the inter-vehicle time decreases, and when the inter-vehicle time is equal to or less than the first threshold and the time to collision becomes equal to or less than a second threshold, the saliency level is set to a third level magnitude obtained by adding a second level that monotonically increases as the time to collision decreases to the first level, The aforementioned setting and outputting the proximity warning with a predetermined level of saliency. [Effects of the Invention]

[0008] According to the present invention, the magnitude of the collision risk between the host vehicle and a preceding vehicle, which changes over time, can be communicated to the driver of the host vehicle in a manner that is highly consistent with the driver's subjective perception. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing the configuration of an attention calling system according to one embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing an example of a scene that the host vehicle encounters while traveling on a road. [Figure 3] FIG. 3 is a diagram for explaining an example of the time transition of the saliency level in the scene shown in FIG. [Figure 4] FIG. 4 is a diagram showing the difference in time transition of the saliency level between when the host vehicle is accelerating and when it is not accelerating. [Figure 5] FIG. 5 is a flowchart showing the procedure of the process of the attention calling method executed by the attention calling system. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing the configuration of an attention calling system 1 according to one embodiment of the present invention. The attention warning system 1 is installed in the host vehicle 2 and issues an approach warning to notify the driver of the host vehicle 2's approach to a preceding vehicle. Here, the term "host vehicle" refers to a vehicle in which the attention warning system 1 is installed.

[0011] The host vehicle 2 includes a vehicle speed sensor 3 that detects the vehicle speed of the host vehicle 2, an object detection device 4 that detects objects ahead of the host vehicle 2, and an HMI (Human Machine Interface) device 5 arranged in the cabin of the host vehicle 2. The object detection device 4 may include, for example, a camera, radar, lidar, and / or sonar. The HMI device 5 is, for example, a speaker. However, the speaker is just one example, and the HMI device 5 may be any device that can issue an approach warning in various ways to occupants, including the driver of the host vehicle 2. In addition to a speaker, the HMI device 5 may also be, for example, an electric seat belt that is provided in the driver's seat of the host vehicle 2 and can change the tension (or fastening force) of the seat belt, a vibration device that is provided in the steering wheel of the host vehicle 2 and can impart vibrations of various intensities to the steering wheel, or a display device.

[0012] The attention warning system 1 includes a processor 10 and a memory 11. The memory 11 is, for example, configured with a volatile and / or non-volatile semiconductor memory and / or a hard disk drive. The processor 10 is, for example, a computer including a CPU. The processor 10 may be configured to include a ROM in which a program is written, a RAM for temporarily storing data, and the like. The processor 10 includes, as functional elements or functional units, a THW acquisition unit 13, a TTC acquisition unit 14, and a notification unit 15.

[0013] These functional elements of the processor 10 are realized, for example, by the processor 10, which is a computer, executing a program 12 stored in a memory 11. The program 12 can be stored in any computer-readable storage medium. Alternatively, all or part of the functional elements of the processor 10 can be configured by hardware including one or more electronic circuit components.

[0014] The THW acquisition unit 13 repeatedly acquires, at predetermined time intervals, the THW (Time Headway) between the host vehicle 2 and a preceding vehicle traveling ahead of the host vehicle 2. For example, the THW acquisition unit 13 acquires, at predetermined time intervals, the current inter-vehicle distance between the preceding vehicle and the host vehicle 2 from the object detection device 4, and acquires the current vehicle speed of the host vehicle 2 from the vehicle speed sensor 3. Then, the THW acquisition unit 13 acquires the value obtained by dividing the current inter-vehicle distance by the current vehicle speed of the host vehicle 2 as the current THW.

[0015] The TTC acquisition unit 14 repeatedly acquires the current TTC (Time to Collision) of the host vehicle 2 relative to the preceding vehicle at predetermined time intervals. For example, the TTC acquisition unit 14 acquires the current inter-vehicle distance between the preceding vehicle and the host vehicle 2 from the object detection device 4 at predetermined time intervals. Then, the TTC acquisition unit 14 calculates the current relative speed between the preceding vehicle and the host vehicle 2 from the time change of the inter-vehicle distance acquired at the predetermined time intervals, and acquires the value obtained by dividing the current inter-vehicle distance by the calculated current relative speed as the current TTC.

[0016] The notification unit 15 outputs an approach warning to the occupants of the host vehicle 2 via the HMI device 5, notifying them of the approach of the host vehicle 2 to a preceding vehicle, based on the THW and TTC repeatedly acquired by the THW acquisition unit 13 and the TTC acquisition unit 14.

[0017] In this embodiment, in particular, the notification unit 15 determines the saliency level, which is the degree of saliency of the proximity warning, in accordance with the THW and TTC, and outputs the proximity warning of the determined saliency level by the HMI device.

[0018] As a result, the warning system 1 outputs an approach warning at a saliency level determined based on the THW, which indicates the sense of proximity to the preceding vehicle, and the TTC, which indicates the sense of approach to the preceding vehicle, so that the magnitude of the collision risk between the own vehicle and the preceding vehicle, which changes over time, can be communicated to the driver of the own vehicle in a manner that is highly consistent with the driver's subjective opinion.

[0019] Here, the degree of prominence of the proximity warning refers to the degree to which the proximity warning attracts or attracts a person's attention.

[0020] For example, when a proximity alarm is output as sound or vibration, the salience level is determined by the intensity, frequency, frequency change period, and repetition period of the sound or vibration. For a proximity alarm given as sound or vibration, the salience level is higher the greater the intensity, the higher the frequency, the shorter the frequency change period, and the shorter the repetition period.

[0021] Alternatively, when the approach warning is output as tension of the electric seat belt, the saliency level is determined by the magnitude of the tension, and the greater the tension, the higher the saliency level of the approach warning.

[0022] Alternatively, when the proximity warning is output as a graphic element such as a character or a figure displayed on a display device, the conspicuousness level may be determined by the brightness, the cycle of brightness change, the cycle of blinking, or the color of the displayed graphic element. For example, the higher the brightness, the shorter the cycle of brightness change or blinking, or the closer the color is to a warm color from a cool color, the higher the conspicuousness level of the proximity warning.

[0023] Specifically, when THW is equal to or less than a first threshold T1, the notification unit 15 sets the saliency level to a first level magnitude that monotonically increases as THW decreases, and when THW is equal to or less than the first threshold T1 and TTC is equal to or less than a second threshold T2, the notification unit 15 sets the saliency level to a third level magnitude obtained by adding a second level that monotonically increases as TTC decreases to the first level.

[0024] As a result, until the TTC becomes equal to or less than the second threshold T2, a proximity warning is output at a salience level corresponding only to the THW, thereby preventing the driver from being annoyed by excessive proximity warnings during a period when the risk of contact between the preceding vehicle and the host vehicle 2 is relatively low. On the other hand, during a period when the TTC becomes equal to or less than the second threshold T2 and the risk of contact becomes imminent, a proximity warning is output at a salience level to which a level corresponding to the TTC is added, thereby conveying to the driver a sense of imminent risk of contact.

[0025] For example, the notification unit 15 calculates the first level so that it monotonically increases with the inverse of the inter-vehicle time, and calculates the second level so that it monotonically increases with the inverse of the time to collision. As a result, the saliency level does not increase linearly as the THW and TTC decrease, but rather the rate of increase increases as the THW and TTC decrease, so that the saliency level can change in a manner that more closely matches the driver's subjective feelings or sensations as the preceding vehicle approaches, thereby further increasing the driver's acceptability or persuasiveness of the proximity warning.

[0026] More specifically, the notification unit 15 calculates the first level value Lf, the second level value Ls, and the third level value Lt using the following equations. Lf=k1 / THW (1) Ls = k2 × k3 × (1 / TTC-1 / T2) (2) Lt = Lf + Ls (3) In the above equation, k1, k2, and k3 are proportionality coefficients.

[0027] Then, the notification unit 15 sets the saliency level SL as follows: When TTH≦T1 and TTC>T2: SL=Lf; When TTH≦T1 and TTC≦T2: SL=Lt (4)

[0028] When setting the saliency level, the notification unit 15 may set the second level Ls to a larger value as the value of THW becomes smaller when the TTC becomes equal to or smaller than the second threshold T2. As a result, the smaller the inter-vehicle distance when the TTC becomes equal to or smaller than the second threshold T2, the higher the saliency level of the subsequent proximity warning can be, thereby conveying to the driver a sense of imminent contact risk.

[0029] For example, the notification unit 15 calculates the proportionality coefficient k2 in equation (2) using the following equation. k2=1-T3 / C1 (5) Here, T3 is the value of THW when TTC becomes equal to or less than the second threshold T2, and C1 is a coefficient.

[0030] The notification unit 15 may also set the second level Ls to a smaller value when the host vehicle 2 is accelerating than when the host vehicle is not accelerating. As a result, when the driver is intentionally accelerating the host vehicle 2, such as when the host vehicle 2 is attempting to overtake a preceding vehicle, the saliency level of the proximity warning is lower than when the host vehicle 2 is not accelerating, thereby preventing the driver from being annoyed by excessive proximity warnings.

[0031] For example, the notification unit 15 determines the proportionality coefficient k3 in the equation (2) as follows: When the host vehicle 2 is not accelerating: k3=1, and When vehicle 2 is accelerating: k3<1 (e.g., k3=0.8) (6)

[0032] For example, the notification unit 15 can determine that the host vehicle 2 is accelerating when the acceleration value calculated from the vehicle speed value acquired at predetermined time intervals from the vehicle speed sensor 3 is equal to or greater than a predetermined threshold. Alternatively, the notification unit 15 can determine that the host vehicle 2 is accelerating when the change in the amount of depression of the accelerator pedal is equal to or greater than a predetermined threshold, based on information from an accelerator pedal sensor (not shown) provided in the host vehicle 2.

[0033] Next, an example of the time transition of the saliency level of the approach warning output by the notification unit 15 will be described using FIGS. 2 and 3. FIG. 2 is a diagram showing an example of a scene encountered by the host vehicle 2 during road travel. FIG. 3 is a diagram for explaining an example of the time transition of the saliency level in the scene shown in FIG. 2.

[0034] In FIG. 2, diagrams showing the positions of the host vehicle 2 traveling on the road 25 and the preceding vehicle 20 at times t0, t1, t2, and t3 are arranged side by side from the uppermost row to the lowermost row. In FIG. 3, the horizontal axis represents time, the vertical axis represents the saliency level, and the graphs 30, 31, and 32 show the time change of the saliency level.

[0035] In the scene shown in FIG. 2, at time t0, the host vehicle 2 is traveling at a constant speed V10 and the preceding vehicle 20 is traveling at a constant speed V20 (uppermost row of FIG. 2). Here, the vehicle speed V20 of the preceding vehicle 20 is slightly lower than the vehicle speed V10 of the host vehicle 2 (V20 < V10), and the THW between the preceding vehicle 20 and the host vehicle 2 gradually decreases.

[0036] Then, the THW between the preceding vehicle 20 and the host vehicle 2 reaches the first threshold value T1 at time t1 Crossing (second row of FIG. 2) and further decreases with the passage of time. Thereafter, while the host vehicle 2 continues to travel at a constant speed, the preceding vehicle 20 starts to decelerate from the vehicle speed V20, and the TTC between the preceding vehicle 20 and the host vehicle 2 crosses the second threshold value T2 at time t2 (third row of FIG. 2) and further decreases. Thereafter, after the vehicle speed of the preceding vehicle 20 reaches V21 (< V20), at time t3, the host vehicle 2 starts to decelerate from the vehicle speed V10, and the TTC starts to increase (lowermost row of FIG. 2).

[0037] The graphs 30, 31, and 32 shown in FIG. 3 show the time changes of the respective saliency levels for three cases where the value of the THW when the TTC crosses the second threshold value T2 at time t2 is different depending on, for example, the magnitude of the speed difference between the vehicle speed V10 of the host vehicle 2 and the vehicle speed V20 of the preceding vehicle 20.

[0038] The value of THW when TTC crosses the second threshold T2 is largest in graph 32 shown in Figure 3, smallest in graph 30, and intermediate between them in graph 31. Here, the saliency level during the period from time t1 to t2 is set to the first level Lf of equation (1), which is proportional to the reciprocal of THW, so graph 32, which has the largest THW at time t2, shows the lowest saliency level compared to the other graphs 30 and 31. Note that graphs 30, 31, and 32 are merely schematic representations of changes in saliency level, and the actual saliency level may change in a curved manner.

[0039] As described above, the notification unit 15 sets the second level Ls shown in equation (2) to a larger value as the value of THW when TTC becomes equal to or smaller than the second threshold T2, using the proportionality coefficient k2 shown in equation (5).Therefore, the slope in the period from time t2 to t3 is greatest in graph 30 and smallest in graph 32.

[0040] It should be noted that the host vehicle 2 starts to decelerate at time t3, and therefore the saliency levels of the graphs 30, 31, and 32 each start to decrease from time t3 (not shown).

[0041] In the scene shown in Fig. 2, the cause of the TTC crossing the second threshold T2 at time t2 is assumed to be deceleration of the preceding vehicle 20, but it may also be acceleration of the host vehicle 2. Fig. 4 is a diagram showing the difference in the time progression of the saliency level between when the host vehicle 2 is accelerating and when it is not accelerating at time t2 when the TTC crosses the second threshold T2. The vertical and horizontal axes in Fig. 4 are the same as those in Fig. 3.

[0042] Graph 30 shown in Fig. 4 is the same as graph 30 shown in Fig. 3, and shows the time progression of the saliency level in the scene of Fig. 2 where the host vehicle 2 is traveling at a constant speed at time t2. In contrast, graph 40 shown in Fig. 4 shows the time progression of the saliency level in the case where the host vehicle 2 is accelerating at time t2.

[0043] As described above, the notification unit 15 sets the second level Ls shown in equation (2) to a smaller value when the vehicle 2 is accelerating than when the vehicle is not accelerating, using the proportionality coefficient k3 shown in equation (6), so the slope of graph 40 during the period from time t2 to t3 is smaller than that of graph 30.

[0044] Next, the operational procedure of the attention calling system 1 will be described. 5 is a flowchart showing the procedure of the process of the attention method executed by the processor 10, which is the computer of the attention system 1. This process is repeatedly executed at predetermined time intervals.

[0045] When the process starts, the notification unit 15 determines whether or not there is a preceding vehicle ahead of the host vehicle 2 based on information from the object detection device 4 that detects an object ahead of the host vehicle 2 (S100). If there is no preceding vehicle ahead of the host vehicle 2 (NO in S100), the notification unit 15 ends this process.

[0046] On the other hand, if there is a preceding vehicle ahead of the host vehicle 2 (S100, YES), the THW acquisition unit 13 acquires the THW between the host vehicle and the preceding vehicle (S102), and the TTC acquisition unit 14 acquires the TTC between the host vehicle and the preceding vehicle (S104). As described above, this process shown in FIG. 5 is repeatedly executed at predetermined time intervals, so that the THW and TTC are repeatedly acquired at the predetermined time intervals by steps S102 and S104. Here, steps S102 and S104 correspond to the THW acquisition step and the TTC acquisition step, respectively, in the present disclosure. Furthermore, the processes from step S106 to step S126, which will be described later, correspond to the notification step in the present disclosure.

[0047] Next, the notification unit 15 determines whether the THW acquired in step S102 is equal to or less than the first threshold T1 (S106). If the THW is not equal to or less than the first threshold T1 (NO in S106), the notification unit 15 ends this process.

[0048] On the other hand, if THW is equal to or less than the first threshold value T1 (S106, YES), the notification unit 15 calculates the first level Lf by the above-mentioned formula (1) (S108).

[0049] Next, the notification unit 15 determines whether the TTC acquired in step S104 is equal to or less than the second threshold value T2 (S110). If the TTC is greater than the second threshold value T2 (S108, NO), the notification unit 15 determines whether the TTC calculated in step S108 is equal to or less than the second threshold value T2 (S110). First Level Lf is set as the salience level SL (S114), and a proximity alarm is output at the set salience level SL (S126), after which the process ends.

[0050] On the other hand, if the TTC is equal to or less than the second threshold T2 (S110, YES), the notification unit 15 calculates the coefficient k2 used to calculate the second level Ls using the above-mentioned equation (5) (S112).

[0051] Next, the notification unit 15 determines whether the host vehicle 2 is accelerating (S116). Then, according to the above-mentioned formula (6), when the host vehicle 2 is not accelerating (S116, NO), the notification unit 15 sets the second level Ls of A coefficient k3 used in the calculation is set to 1 (S118), and if the host vehicle 2 is accelerating (S116, YES), the coefficient k3 is set to a value smaller than 1, for example, 0.8 (S120).

[0052] Next, the notification unit 15 calculates the second level Ls and the third level Lt using the above-mentioned formulas (2) and (3) (S122), sets the calculated third level Lt as the saliency level SL (S124), and outputs a proximity alarm at the set saliency level SL (S126), after which the process ends.

[0053] The present invention is not limited to the configurations of the above-described embodiments, and can be implemented in various forms without departing from the spirit of the invention.

[0054] [Configuration supported by the above embodiment] The above-described embodiment supports the following configurations.

[0055] (Configuration 1) An attention warning system comprising a THW acquisition unit that repeatedly acquires, at predetermined time intervals, a time to collision interval, which is the value obtained by dividing the inter-vehicle distance between the host vehicle and a preceding vehicle by the vehicle speed of the host vehicle; a TTC acquisition unit that repeatedly acquires, at predetermined time intervals, a time to collision interval, which is the value obtained by dividing the inter-vehicle distance by the relative speed between the host vehicle and the preceding vehicle; and a notification unit that outputs an approach warning to occupants of the host vehicle based on the inter-vehicle time and the time to collision interval, to notify them of the approach of the preceding vehicle, wherein the notification unit determines a salience level, which is the degree of salience of the approach warning, in accordance with the inter-vehicle time and the time to collision interval, and outputs the approach warning of the determined salience level. According to the warning system of configuration 1, an approach warning is output at a saliency level based on the inter-vehicle time, which indicates the sense of proximity to the preceding vehicle, and the collision margin time, which indicates the sense of approach to the preceding vehicle, so that the magnitude of the collision risk between the own vehicle and the preceding vehicle, which changes over time, can be communicated to the driver of the own vehicle in a manner that is highly consistent with the driver's subjective opinion.

[0056] (Configuration 2) The warning system described in Configuration 1, wherein the notification unit sets the salience level to a first level magnitude that monotonically increases as the time to collision decreases when the time to vehicle headway becomes equal to or less than a first threshold, and sets the salience level to a third level magnitude that is the first level plus a second level that monotonically increases as the time to collision decreases when the time to vehicle headway is equal to or less than the first threshold and the time to collision is equal to or less than a second threshold. According to the warning system of configuration 2, an approach warning is output at a saliency level corresponding only to the THW until the TTC becomes equal to or less than the second threshold T2, thereby preventing the driver from being annoyed by excessive approach warnings during a period when the risk of contact between the preceding vehicle and the vehicle 2 is relatively low.

[0057] (Configuration 3) The warning system described in Configuration 2, wherein the notification unit calculates the first level, which monotonically increases with the inverse of the inter-vehicle time, and calculates the second level, which monotonically increases with the inverse of the time to collision. According to the attention warning system of configuration 3, the salience level does not increase linearly with the decrease in THW and TTC, but rather the rate of increase increases as THW and TTC decrease, so that the salience level can change in a manner that is closer to the driver's subjective feelings or sensations as the preceding vehicle approaches. As a result, the driver's acceptability or understanding of the proximity warning can be further improved.

[0058] (Configuration 4) The warning system described in Configuration 2 or 3, wherein the notification unit sets the second level to a larger value as the value of the inter-vehicle time when the collision time to collision becomes equal to or less than a second threshold value becomes smaller. Configuration 4 Notes arousal According to the system, the smaller the inter-vehicle distance when the TTC falls below the second threshold T2, the more salient the subsequent proximity warning will be, thereby conveying to the driver a sense of imminent risk of contact.

[0059] (Configuration 5) An attention warning system according to any one of configurations 2 to 4, wherein the notification unit sets the second level to a smaller value when the vehicle is accelerating than when the vehicle is not accelerating. According to the warning system of configuration 5, when the driver intentionally accelerates the vehicle, for example when the vehicle is trying to overtake a preceding vehicle, the saliency level of the approach warning is lower than when the vehicle is not accelerating, thereby preventing the driver from being annoyed by excessive approach warnings.

[0060] (Configuration 6) An attention warning method executed by a computer of an attention warning system, comprising: a THW acquisition step of repeatedly acquiring, at predetermined time intervals, a time to collision (TTC) which is the value obtained by dividing the inter-vehicle distance between the subject vehicle and a preceding vehicle by the vehicle speed of the subject vehicle; a TTC acquisition step of repeatedly acquiring, at predetermined time intervals, a time to collision (TTC) which is the value obtained by dividing the inter-vehicle distance by the relative speed between the subject vehicle and the preceding vehicle; and a notification step of outputting an approach warning to an occupant of the subject vehicle notifying them of an approach to the preceding vehicle based on the inter-vehicle time and the time to collision, wherein in the notification step, a salience level which is the degree of salience of the approach warning is determined in accordance with the inter-vehicle time and the time to collision, and the approach warning of the determined salience level is output. composition 6 According to this warning method, an approach warning is output at a saliency level based on the inter-vehicle time, which indicates the sense of proximity to the preceding vehicle, and the collision margin time, which indicates the sense of approach to the preceding vehicle, so that the magnitude of the collision risk between the own vehicle and the preceding vehicle, which changes over time, can be communicated to the driver of the own vehicle in a manner that is highly consistent with the driver's subjective opinion. [Explanation of symbols]

[0061] 1...attention warning system, 2...own vehicle, 3...vehicle speed sensor, 4...object detection device, 5...HMI device, 10...processor, 11...memory, 12...program, 13...THW acquisition unit, 14...TTC acquisition unit, 15...alarm unit, 20...preceding vehicle, 25...road 25.

Claims

1. a THW acquisition unit that repeatedly acquires a time headway, which is a value obtained by dividing the inter-vehicle distance between the host vehicle and a preceding vehicle by the vehicle speed of the host vehicle, at predetermined time intervals; a TTC acquisition unit that repeatedly acquires, at predetermined time intervals, a time to collision that is a value obtained by dividing the inter-vehicle distance by a relative speed between the host vehicle and the preceding vehicle; a notification unit that outputs an approach warning to an occupant of the vehicle to notify the occupant of the vehicle of an approach to the preceding vehicle based on the inter-vehicle time and the time to collision; Equipped with The notification unit A salience level, which is a degree of salience of the proximity alarm, is set as follows: When the time headway becomes equal to or less than a first threshold, the saliency level is set to a first level magnitude that monotonically increases as the time headway decreases; When the inter-vehicle time is equal to or less than a first threshold value and the time to collision is equal to or less than a second threshold value, a second level that monotonically increases as the time to collision decreases is set to a third level obtained by adding the first level to the second level, outputting the proximity warning at the set salience level; Attention warning system.

2. The notification unit calculating the first level that monotonically increases with the reciprocal of the inter-vehicle time; calculating the second level that monotonically increases with the reciprocal of the time to collision; The warning system according to claim 1 .

3. The notification unit sets the second level to a larger value as the value of the time headway when the time to collision becomes equal to or less than a second threshold becomes smaller. The warning system according to claim 1 .

4. the notification unit sets the second level to a smaller value when the host vehicle is accelerating than when the host vehicle is not accelerating. The warning system according to any one of claims 1 to 3.

5. An attention method executed by a computer of an attention system, a THW acquisition step of repeatedly acquiring a time headway, which is a value obtained by dividing the inter-vehicle distance between the host vehicle and a preceding vehicle by the vehicle speed of the host vehicle, at predetermined time intervals; a TTC acquisition step of repeatedly acquiring a time to collision (Time to Collision) at predetermined time intervals, the time to collision being a value obtained by dividing the inter-vehicle distance by a relative speed between the host vehicle and the preceding vehicle; a notification step of outputting an approach warning to an occupant of the host vehicle to notify the occupant of the host vehicle of an approach to the preceding vehicle based on the inter-vehicle time and the time to collision; and In the notification step, A salience level, which is a degree of salience of the proximity alarm, is set as follows: When the time headway becomes equal to or less than a first threshold, the saliency level is set to a first level magnitude that monotonically increases as the time headway decreases; When the inter-vehicle time is equal to or less than a first threshold value and the time to collision is equal to or less than a second threshold value, a second level that monotonically increases as the time to collision decreases is set to a third level obtained by adding the first level to the second level, outputting the proximity warning at the set salience level; How to get attention.

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