EP4033472A1

EP4033472A1 - Vehicle alarm device

Info

Publication number: EP4033472A1
Application number: EP21207753.1A
Authority: EP
Inventors: Hiromitsu Nishizawa
Original assignee: Suzuki Motor Corp
Current assignee: Suzuki Motor Corp
Priority date: 2021-01-20
Filing date: 2021-11-11
Publication date: 2022-07-27
Also published as: JP2022111582A

Abstract

[Problem to be Solved] To properly output an alarm so as to reduce discomfort imparted to a driver.

[Solution] A vehicle alarm device of the present invention has an alarm control unit that outputs an alarm when time to collision between a vehicle and a collision object is equal to or less than a predetermined time to collision threshold. The alarm control unit prohibits output of the alarm when there is no deceleration of the collision object and a brake operation of the vehicle is recognized. Alternatively, the alarm control unit prohibits output of the alarm when a deceleration of the vehicle is equal to or greater than a predetermined deceleration threshold.

Description

[Technical Field]

The present invention relates to a vehicle alarm device configured to output an alert in accordance with time to collision related to collision of an ego vehicle with a collision object.

[Background Art]

Vehicles such as automobiles may have mounted therein a vehicle alarm device that raises an alarm to urge a driver to perform a brake operation when there is an increased probability (hereinafter referred to as "probability of collision" as necessary) of the vehicle colliding with a collision object located in front of the vehicle. Typically, the probability of collision is determined based on the time to collision (hereafter referred to as "TTC" as necessary). The TTC is a value obtained by dividing a relative distance between an ego vehicle and a collision object by a relative speed between the ego vehicle and the collision obj ect.
Furthermore, when relative distances between an ego vehicle and a preceding vehicle located in front of the ego vehicle, i.e., inter-vehicle distances, in countries around the world are compared, the inter-vehicle distances tend to vary depending on traffic conditions in a country, national practices in a country, and the like. For example, the inter-vehicle distance in India tends to be less than the inter-vehicle distance in Japan. Therefore, when a vehicle alarm device designed for Japan is used in India, the vehicle alarm device may excessively issue alarms. Such an excessive alarm may cause discomfort to the driver. It is also important to avoid the vehicle alarm device issuing unnecessary alarms, regardless of the differences in countries. Therefore, the vehicle alarm device is required to suppress excessive alarms which would cause discomfort of the driver.
An example of the vehicle alarm device that can satisfy such requirements may include a driving assist device (see, for example, Patent Literature 1), including a first sensor that detects an obstacle in front of a vehicle, a second sensor that detects the intention to perform a brake operation by a driver in the vehicle, an alarm device that issues an alarm, and a controller. The controller is configured to predict whether or not the vehicle and the obstacle detected by the first sensor will collide. The controller is also configured to determine whether or not the brake operation of the driver is predicted based on the intention of the brake operation detected by the second sensor. The controller is further configured to issue an alarm by controlling the alarm device when it is determined that the vehicle and the obstacle will collide but the brake operation of the driver is not predicted, and configured to prohibit issuing the alarm when it is determined that the vehicle and the obstacle will collide and the brake operation of the driver is predicted.

[Citation List]

[Patent Literature]

[Patent Literature 1] JP 2018-045569 A

[Summary of Invention]

[Problem to be Solved by the Invention]

However, in the configuration of simply prohibiting issuance of an alarm when the brake operation of the driver is predicted as in the above example of the vehicle alarm device, there is a possibility that the alarm is not issued when the driver intuitively predicts a collision between the ego vehicle and the collision object and senses a risk of the collision. In this case, the driver may feel unease, and this may also become a cause of discomfort of the driver.
In light of such circumstances, it is desirable in the vehicle alarm device to properly issue an alarm so as to reduce the discomfort of the driver.

[Means for Solving the Problem]

In order to solve the problem, a vehicle alarm device according to one aspect includes: a collision information acquisition unit configured to acquire a relative distance between a vehicle and a collision object located in an advance direction of the vehicle, a relative speed between the vehicle and the collision object, and time to collision based on the relative distance and the relative speed; an alarm control unit configured to execute alarm output control for outputting an alarm when an acquisition value of the time to collision acquired by the collision information acquisition unit is equal to or less than a predetermined time to collision threshold; and a brake operation recognition unit configured to recognize a brake operation by a driver of the vehicle. The vehicle alarm device includes an object deceleration determination unit configured to determine whether or not there is deceleration of the collision object based on an acquisition value of the relative speed acquired by the collision information acquisition unit. The alarm control unit is configured to execute alarm prohibition control for prohibiting output of the alarm when the object deceleration determination unit determines that there is no deceleration of the collision object and the brake operation recognition unit recognizes the brake operation.
In order to solve the problem, a vehicle alarm device according to another aspect includes: a collision information acquisition unit configured to acquire a relative distance between a vehicle and a collision object located in an advance direction of the vehicle, a relative speed between the vehicle and the collision object, and time to collision based on the relative distance and the relative speed; an alarm control unit configured to execute alarm output control for outputting an alarm when an acquisition value of the time to collision acquired by the collision information acquisition unit is equal to or less than a predetermined time to collision threshold; and a vehicle deceleration acquisition unit configured to acquire a deceleration of the vehicle. The vehicle alarm device includes a vehicle deceleration determination unit that determines whether or not an acquisition value of the deceleration acquired by the vehicle deceleration acquisition unit is equal to or greater than a predetermined deceleration threshold. The alarm control unit is configured to execute alarm prohibition control for prohibiting output of the alarm when the vehicle deceleration determination unit determines that the acquisition value of the deceleration is equal to or greater than the predetermined deceleration threshold.

[Advantageous Effect of Invention]

The vehicle alarm device according to one aspect can properly issue an alarm so as to reduce discomfort of a driver.

[Brief Description of the Drawings]

[Figure 1] Figure 1 is a block diagram of a vehicle including a vehicle alarm device according to a first embodiment.
[Figure 2] Figure 2 is a plan view schematically showing the vehicle and another vehicle as a collision object according to the first embodiment.
[Figure 3] Figure 3 is a graph showing the relationship between an acquisition value of a count of brake operation during driving by a specific driver and an acquisition value of a relative distance between the vehicle and the another vehicle in the vehicle alarm device according to the first embodiment.
[Figure 4] Figure 4 is a flowchart showing one example of a control method of the vehicle alarm device according to the first embodiment.
[Figure 5] Figure 5 is a block diagram of a vehicle including a vehicle alarm device according to a second embodiment.
[Figure 6] Figure 6 is a graph showing the relationship between an acquisition value of time to collision between the vehicle and the another vehicle during AEB control and an acquisition value of deceleration of the vehicle in the vehicle alarm device according to the second embodiment.
[Figure 7] Figure 7 is a flowchart showing one example of a control method of the vehicle alarm device according to the second embodiment.

[Mode for Carrying Out the Invention]

Vehicle alarm devices according to first and second embodiments will be described together with vehicles mounted therewith. In each embodiment, the vehicle mounted with the vehicle alarm device (hereinafter simply referred to as "alarm device" as necessary) is an automobile. However, such vehicles are not limited to automobiles.

[First Embodiment]

Description is given on the vehicle alarm device and the vehicle according to the first embodiment.

Outline of Vehicle Alarm Device and Vehicle

With reference to Figure 1 to Figure 3, a vehicle alarm device 20 and a vehicle 10 according to the present embodiment are generally configured as follows. With reference to Figure 1 and Figure 2, the vehicle alarm device 20 has a collision information acquisition unit 21. The collision information acquisition unit 21 is configured to acquire collision information related to a collision predicted based on the relationship between the vehicle 10, i.e., ego vehicle 10, and a collision object P located in an advance direction of the vehicle 10.
As shown in Figure 2, in many cases, the collision object P is another vehicle P other than the vehicle 10. Moreover, in many cases, the advance direction of the own vehicle 10 is a front side from the own vehicle 10 (indicated by a one-headed arrow F). However, the collision object may be a moving object other than the another vehicle. The advance direction of the vehicle may be a rear side from the vehicle.
Referring to Figure 1 and Figure 2, the collision information includes a relative distance (m) between the vehicle 10 and the another vehicle P. The collision information includes a relative speed (m/sec) between the vehicle 10 and the another vehicle P. The collision information includes time to collision (hereafter referred to as "TTC" as necessary) (sec) based on the relative distance and the relative speed. Therefore, the collision information acquisition unit 21 can acquire an acquisition value A of the relative distance, an acquisition value B of the relative speed, and an acquisition value C of the TTC.
The alarm device 20 has an alarm control unit 22. The alarm control unit 22 is configured to execute alarm output control for outputting an alarm when the acquisition value C of the TTC acquired by the collision information acquisition unit 21 is equal to or less than a predetermined TTC threshold C1. The alarm device 20 has a brake operation recognition unit 23. The brake operation recognition unit 23 is configured to recognize a brake operation by a driver (not illustrated) of the vehicle 10.
The alarm device 20 has an object deceleration determination unit 24. The object deceleration determination unit 24 is configured to determine whether or not there is deceleration of the another vehicle P based on the acquisition value B of the relative speed acquired by the collision information acquisition unit 21. The alarm control unit 22 executes alarm prohibition control for prohibiting output of the alarm in a case in which the object deceleration determination unit 24 determines that there is no deceleration of the another vehicle P and the brake operation recognition unit 23 recognizes the brake operation.
Furthermore, the vehicle alarm device 20 and the vehicle 10 according to the present embodiment can generally be configured as follows. With reference to Figure 1 to Figure 3, the vehicle alarm device 20 has a brake count acquisition unit 25. The brake count acquisition unit 25 is configured to acquire the count (or the number) of brake operation by the driver of the vehicle 10. The alarm control unit 22 executes alarm prohibition control for prohibiting output of the alarm in a case in which the acquisition value A of the relative distance acquired by the collision information acquisition unit 21 is equal to or greater than a predetermined relative distance threshold A1. The relative distance threshold A1 is changed based on the relationship between the acquisition value A of the relative distance and the acquisition value D of the count of brake operation acquired by the brake count acquisition unit 25. Note that in Figure 3, a horizontal axis A represents the acquisition value of the relative distance (m), and a vertical axis D represents the acquisition value of the count or the number of times of brake operation. In Figure 3, a solid line J indicates characteristics of relative distance - count of brake operation during driving by a specific driver as an example.

Details of Vehicle

With reference to Figure 1, the vehicle 10 can be configured in details as follows. The vehicle 10 has an object detection device 11. The object detection device 11 is configured to detect the presence of the collision object P, that is, the presence of the another vehicle P in particular. The object detection device 11 is also configured to detect a relative distance between the vehicle 10 and the collision object P. The object detection device 11 includes a sonar sensor. However, the object detection device may include, in place of the sonar sensor or in addition to the sonar sensor, a camera, a millimeter wave radar, an infrared laser radar, a LiDAR (Light Detection and Ranging), or the like.
The vehicle 10 typically has four wheels 12. The vehicle 10 has wheel speed sensors 13 configured to detect rotation speed (sec^-1) of the wheels 12. However, the vehicle can also have a vehicle speed sensor configured to detect a travel speed of the vehicle in place of the wheel speed sensors or in addition to the wheel speed sensors.
The vehicle 10 has a sound output device 14 configured to output, as the aforementioned alarm, sound information such as buzzer sound, speech sound, or the like. For example, the sound output device 14 can include a speaker. The vehicle 10 also has a display output device 15 configured to output, as the alarm, visual information such as characters, figures, illustrations, light or the like. For example, the display output device 15 can be a display with a liquid crystal panel, an organic electro luminescence (EL) panel, or the like, an instrument panel, a lamp, or the like.
The vehicle 10 has a brake device 16 used for braking. The brake device 16 has brakes 16a configured to slow down or stop the wheels 12. The brake device 16 has a fluid pressure unit 16b configured to adjust braking force of each of the brakes 16a. The brake device 16 has a brake pedal 16c for operating the fluid pressure unit 16b so as to adjust braking force of each of the brakes 16a. The brake device 16 has a fluid pressure sensor 16d configured to detect operation of the brake pedal 16c by the driver. However, the brake device may have a stroke sensor in place of the fluid pressure sensor or in addition to the fluid pressure sensor.

Details of Vehicle Alarm Device

With reference to Figure 1 to Figure 3, the vehicle alarm device 20 according to the present embodiment can be configured in details as follows. The vehicle alarm device 20 is configured to include electronic components, such a CPU (central processing unit), a RAM (random access memory), a ROM (read only memory), a flash memory, an input interface, and an output interface, and an electrical circuit with the electronic components arranged thereon. The ROM stores programs to activate the functions of the alarm device 20, together with various control constants and various maps. Therefore, when the CPU executes the programs stored in the ROM, the functions of the alarm device 20 can be activated. However, the vehicle alarm device is not limited to this configuration.
Referring to Figure 1 and Figure 2, the collision information acquisition unit 21 of the alarm device 20 can be an autonomous emergency braking unit (hereinafter referred to as "AEB unit" as necessary). The AEB unit 21 controls the brake device 16 directly or indirectly to execute the AEB control when there is a possibility that the vehicle 10 may collide with the collision object P.
The collision information acquisition unit 21 is configured to acquire a detection value of the relative distance detected by the object detection device 11. The collision information acquisition unit 21 is configured to acquire detection values of the wheel speeds detected by the wheel speed sensors 13. The collision information acquisition unit 21 calculates the vehicle speed (m/sec, km/h) of the vehicle 10 based on the acquisition values of the wheel speeds so as to acquire the vehicle speed of the vehicle 10. However, the collision information acquisition unit can also acquire a detection value of the vehicle speed detected by the vehicle speed sensor.
The collision information acquisition unit 21 calculates a relative speed between the vehicle 10 and the collision object P based on an acquisition value E of the vehicle speed of the vehicle 10 and the acquisition value A of the relative distance so as to acquire the relative speed. The collision information acquisition unit 21 calculates the TTC based on the following (Expression 1) related to the acquisition value A of the relative distance and the acquisition value B of the relative speed so as to acquire the TTC. In other words, the acquisition value C of the TTC is obtained by the following (Expression 1). $C = A/B$
The alarm device 20 has a TTC determination unit 26. The TTC determination unit 26 determines whether or not the acquisition value C of the TTC acquired by the collision information acquisition unit 21 is equal to or less than a predetermined TTC threshold C1.
The alarm device 20 has a vehicle speed determination unit 27. The vehicle speed determination unit 27 determines whether or not the acquisition value E of the vehicle speed of the vehicle 10 acquired by the collision information acquisition unit 21 is equal to or less than a predetermined vehicle speed threshold E1. For example, the vehicle speed threshold E1 can be in a range of about 20km/h to about 30km/h. However, the vehicle speed threshold is not limited to this range.
The alarm device 20 has a relative distance determination unit 28. The relative distance determination unit 28 determines whether or not the acquisition value A of the relative distance acquired by the collision information acquisition unit 21 is equal to or less than the predetermined relative distance threshold A1.
The brake operation recognition unit 23 is configured to determine whether or not operation of the brake pedal 16c by the driver has been recognized. Specifically, the brake operation recognition unit 23 is able to determine whether or not the operation of the brake pedal 16c by the driver is detected by the fluid pressure sensor 16d of the brake device 16. The brake operation recognition unit 23 recognizes the brake operation of the driver when the operation of the brake pedal 16c is detected by the fluid pressure sensor 16d of the brake device 16.
The object deceleration determination unit 24 is configured to determine whether or not there is deceleration of the collision object P based on the acquisition value E of the vehicle speed of the vehicle 10 and the acquisition value B of the relative speed acquired by the collision information acquisition unit 21. For example, the object deceleration determination unit 24 can determine that the collision object P is decelerating when the acquisition value B of the relative speed decreases and the acquisition value E of the vehicle speed of the vehicle 10 is approximately constant or decreases. For example, the object deceleration determination unit 24 can determine that the collision object P is not decelerating when the acquisition value B of the relative speed increases. For example, the object deceleration determination unit 24 can determine that there is no deceleration of the collision object P when the acquisition value B of the relative speed decreases and the acquisition value E of the vehicle speed of the vehicle 10 increases.
The brake count acquisition unit 25 is configured to store the brake operation recognized by the brake operation recognition unit 23. The brake count acquisition unit 25 accumulates the recognized brake operation that have been stored so as to acquire the count of the brake operation. The alarm device 20 has a relative distance threshold change unit 29 that changes the relative distance threshold A1 based on the relationship between the acquisition value A of the relative distance and the acquisition value D of the count of the brake operation acquired by the brake count acquisition unit 25.
As shown in Figure 3, as a first case, for example, the relative distance threshold change unit 29 can set the relative distance threshold A1 to be small when the acquisition value D of the count of the brake operation is large even if the acquisition value A of the relative distance is small. In this first case, the alarm is less likely to be output even when the vehicle 10 approaches the collision object P.
On the other hand, for example, as a second case, the relative distance threshold change unit 29 can set the relative distance threshold A1 to be larger than the threshold in the first case when the acquisition value D of the count of the brake operation is smaller even if the acquisition value A of the relative distance is larger than the relative distance in the first case. In this second case, as compared with the first case, the alarm is more likely to be output even when the vehicle 10 is away from the collision object P

Control Method of Vehicle Alarm Device

With reference to Figure 4, one example of a control method of the vehicle alarm device 20 according to the present embodiment will be described. First, it is determined whether or not the acquisition value C of the TTC is equal to or less than the predetermined TTC threshold C1 (step S1). When the acquisition value C of the TTC is greater than the predetermined TTC threshold C1 (NO), the vehicle 10 performs normal driving (step S2).
When the acquisition value C of the TTC is equal to or less than the prescribed TTC threshold C1 (YES), it is determined whether or not the acquisition value E of the vehicle speed of the vehicle 10 is equal to or less than the vehicle speed threshold E1 (step S3). When the acquisition value E of the vehicle speed of the vehicle 10 is greater than the vehicle speed threshold E1 (NO), an alarm is output (step S4).
When the acquisition value E of the vehicle speed of the own vehicle 10 is equal to or less than the vehicle speed threshold E1 (YES), it is determined whether or not operation of the brake pedal 16c by the driver is recognized (step S5). When the operation of the brake pedal 16c by the driver is not recognized (NO), an alarm is output (step S4).
When the operation of the brake pedal 16c by the driver is recognized (YES), it is determined whether or not there is deceleration of the collision object P (step S6). When there is deceleration of the collision object P (YES), an alarm is output (step S4). When there is no deceleration of the collision object P (NO), output of the alarm is prohibited (step S7).
As described in the foregoing, the vehicle alarm device 20 according to the present invention includes: the collision information acquisition unit 21 configured to be able to acquire a relative distance between the vehicle 10 and the collision object P located in an advance direction of the vehicle 10, a relative speed between the vehicle 10 and the collision object P, and time to collision based on the relative distance and the relative speed; the alarm control unit 22 configured to be able to execute alarm output control for outputting an alarm when the acquisition value C of the time to collision acquired by the collision information acquisition unit 21 is equal to or less than the time to collision threshold C1; and the brake operation recognition unit 23 configured to be able to recognize brake operation by a driver of the vehicle 10. The vehicle alarm device 20 includes the object deceleration determination unit 24 configured to be able to determine whether or not there is deceleration of the collision object P based on the acquisition value B of the relative speed acquired by the collision information acquisition unit 21. The alarm control unit 22 is configured to execute alarm prohibition control for prohibiting output of the alarm when the object deceleration determination unit 24 determines that there is no deceleration of the collision object P and the brake operation recognition unit 23 recognizes the brake operation.
In general, when a collision object does not decelerate even in a state in which the brake operation of a vehicle is not performed, decrease in a relative distance between the vehicle and the collision object rarely occurs. In such a case, the driver is less likely to intuitively predict a collision between the vehicle and the collision object and to sense a risk of collision. Hence, there is no chance of the driver feeling unease due to the alarm not being output.
In this connection, in the vehicle alarm device 20 according to the present embodiment, output of an alarm is prohibited when the collision object P does not decelerate even if the brake operation of the vehicle 10 is not performed as described before, whereas when there is a possibility that the relative distance between the vehicle 10 and the collision object P decreases, the alarm is output to urge the driver to perform stronger brake operation. This makes it possible to suppress excessive alarms causing discomfort of the driver and to prevent the driver from feeling unease relating to the alarm not being output. Therefore, it is possible to properly output an alarm so as to reduce discomfort of the driver.
The vehicle alarm device 20 according to the present embodiment includes the brake count acquisition unit 25 configured to be able to acquire the count of brake operation by the driver of the vehicle 10. The alarm control unit 22 is configured to be able to execute alarm prohibition control for prohibiting output of the alarm when the acquisition value A of the relative distance acquired by the collision information acquisition unit 21 is equal to or greater than the prescribed relative distance threshold A1. The relative distance threshold A1 is changed based on the relationship between the acquisition value A of the relative distance and the acquisition value D of the count of the brake operation acquired by the brake count acquisition unit 25.
In such a vehicle alarm device 20, it is determined whether or not the alarm is output in accordance with the relative distance between the vehicle 10 and the collision object P in consideration of the characteristics of the brake operation by the driver. Therefore, it is possible to more properly output an alarm so as to reduce discomfort imparted to the driver.

[Second Embodiment]

Description is given on a vehicle alarm device and a vehicle according to the second embodiment.

Outline of Vehicle Alarm Device and Vehicle

With reference to Figure 5 and Figure 6, a vehicle alarm device 40 and a vehicle 30 according to the present embodiment are generally configured as follows. With reference to Figure 5, the vehicle alarm device 40 has a collision information acquisition unit 41. The collision information acquisition unit 41 is generally configured in a similar manner to the collision information acquisition unit 21 in the first embodiment.
The vehicle alarm device 40 has an alarm control unit 42. The alarm control unit 42 is able to execute alarm output control like the alarm control unit 22 in the first embodiment. The alarm device 40 has a vehicle deceleration acquisition unit 43. The vehicle deceleration acquisition unit 43 is configured to acquire a deceleration (m/s²) of the vehicle 30.
With reference to Figure 5 and Figure 6, the alarm device 40 has a vehicle deceleration determination unit 44. The vehicle deceleration determination unit 44 determines whether or not an acquisition value F of the deceleration acquired by the vehicle deceleration acquisition unit 43 is equal to or greater than a predetermined deceleration threshold F1. The alarm control unit 42 executes alarm prohibition control for prohibiting output of the alarm when the vehicle deceleration determination unit 44 determines that the acquisition value F of the deceleration is equal to or greater than the deceleration threshold F1. Note that in Figure 6, a horizontal axis C represents the acquisition value (sec) of the TTC, and a vertical axis F represents the acquisition value (m/s²) of the deceleration of the vehicle 30. In Figure 6, a solid line K indicates TTC - deceleration characteristics during AEB control.
Furthermore, the vehicle alarm device 40 and the vehicle 30 according to the present embodiment can generally be configured as follows. In the vehicle alarm device 40, the deceleration threshold F1 is set to increase as the acquisition value C of the TTC decreases.
The alarm device 40 has a brake count acquisition unit 45. The brake count acquisition unit 45 is generally configured in a similar manner to the brake count acquisition unit 25 in the first embodiment. Like the alarm control unit 22 in the first embodiment, the alarm control unit 42 executes alarm prohibition control for prohibiting output of the alarm when the acquisition value A of the relative distance acquired by the collision information acquisition unit 41 is equal to or greater than a predetermined relative distance threshold A1. As in the alarm device 20 in the first embodiment, the relative distance threshold A1 is changed based on the relationship between the acquisition value A of the relative distance and the acquisition value D of the count of brake operation acquired by the brake count acquisition unit 45.

Details of Vehicle

With reference to Figure 5, the vehicle 30 according to the present embodiment can be configured in details as follows. The vehicle 30 in the present embodiment has an object detection device 31, wheels 32, wheel speed sensors 33, a sound output device 34, a display output device 35 and a brake device 36, which are configured in a similar manner to the object detection device 11, the wheels 12, the wheel speed sensors 13, the sound output device 14, the display output device 15 and the brake device 16 in the first embodiment, respectively. In addition, the brake device 36 according to the present embodiment has brakes 36a, a fluid pressure unit 36b, a brake pedal 36c, and a fluid pressure sensor 36d configured in a similar manner to the brakes 16a, the fluid pressure unit 16b, the brake pedal 16c, and the fluid pressure sensor 16d in the first embodiment, respectively.

Details of Vehicle Alarm Device

With reference to Figure 5 and Figure 6, the vehicle alarm device 40 according to the present embodiment can be configured in details as follows. Like the vehicle alarm device 20 according to the first embodiment, the vehicle alarm device 40 is configured to include electronic components and an electrical circuit.
With reference to Figure 5, the collision information acquisition unit 41 is configured specifically in a similar manner to the collision information acquisition unit 21 according to the first embodiment. The alarm device 40 has a TTC determination unit 46. Specifically, the TTC determination unit 46 according to the present embodiment is configured in a similar manner to the TTC determination unit 26 according to the first embodiment. The alarm device 40 has a vehicle speed determination unit 47. The vehicle speed determination unit 47 according to the present embodiment is configured in a manner similar to the vehicle speed determination unit 27 according to the first embodiment.
The alarm device 40 has a relative distance determination unit 48. The relative distance determination unit 48 according to the present embodiment is configured in a manner similar to the relative distance determination unit 28 according to the first embodiment. The alarm device 40 has a relative distance threshold change unit 49. The relative distance threshold change unit 49 according to the present embodiment is configured in a manner similar to the relative distance threshold change unit 29 according to the first embodiment.
Furthermore, the vehicle deceleration acquisition unit 43 of the alarm device 40 calculates deceleration of the vehicle 30 based on an acquisition value E of the vehicle speed of the vehicle 30 acquired by the collision information acquisition unit 41 so as to acquire the deceleration of the vehicle 30. The vehicle deceleration determination unit 44 increases the deceleration threshold F1 as the acquisition value C of the time to collision decreases.

Control Method of Vehicle Alarm Device

With reference to Figure 7, an example of a control method of the vehicle alarm device 40 according to the present embodiment will be described. First, it is determined whether or not the acquisition value C of the TTC is equal to or less than the predetermined TTC threshold C1 (step S11). When the acquisition value C of the TTC is greater than the predetermined TTC threshold C1 (NO), the vehicle 30 performs normal driving (step S12).
When the acquisition value C of the TTC is equal to or less than the predetermined TTC threshold C1 (YES), it is determined whether or not the acquisition value E of the vehicle speed of the vehicle 30 is equal to or less than the vehicle speed threshold E1 (step S13). When the acquisition value E of the vehicle speed of the vehicle 30 is greater than the vehicle speed threshold E1 (NO), an alarm is output (step S14).
When the acquisition value E of the vehicle speed of the vehicle 30 is equal to or less than the vehicle speed threshold E1 (YES), it is determined whether or not the acquisition value F of the deceleration is equal to or greater than the predetermined deceleration threshold F1 (step S15). When the acquisition value F of the deceleration is less than the predetermined deceleration threshold F1 (NO), an alarm is output (step S14). When the acquisition value F of the deceleration is equal to or greater than the predetermined deceleration threshold F1 (YES), output of the alarm is prohibited (step S16).
As described in the foregoing, the vehicle alarm device 40 according to the present embodiment includes: the collision information acquisition unit 41 configured to be able to acquire a relative distance between the vehicle 30 and the collision object P located in an advance direction of the vehicle 30, a relative speed between the vehicle 30 and the collision object P, and time to collision based on the relative distance and the relative speed; the alarm control unit 42 configured to be able to execute alarm output control for outputting an alarm when the acquisition value C of the time to collision acquired by the collision information acquisition unit 41 is equal to or less than the time to collision threshold C1; and the vehicle deceleration acquisition unit 43 configured to be able to acquire a deceleration of the vehicle 30. The vehicle alarm device 40 includes the vehicle deceleration determination unit 44 that determines whether or not the acquisition value F of the deceleration acquired by the vehicle deceleration acquisition unit 43 is equal to or greater than the predetermined deceleration threshold F1. The alarm control unit 42 is configured to execute alarm prohibition control for prohibiting output of the alarm when the vehicle deceleration determination unit 44 determines that the acquisition value F of the deceleration is equal to or greater than the deceleration threshold F1.
In general, when a vehicle rapidly decelerates, it is often the case in which the driver actively tries to stop the vehicle with the driver's intention. Accordingly, decrease in a relative distance between the vehicle and the collision object rarely occurs. In such a case, the driver is less likely to intuitively predict a collision between the vehicle and the collision object and to sense a risk of collision. Hence, there is no chance of the driver feeling unease due to the alarm not being output.
In this connection, in the vehicle alarm device 40 according to the present embodiment, output of an alarm is prohibited when the vehicle 30 rapidly decelerates, whereas when there is a possibility that the relative distance between the vehicle 30 and the collision object P decreases, the alarm is output to urge the driver to perform stronger brake operation. This makes it possible to suppress excessive alarms causing discomfort of the driver and to prevent the driver from feeling unease relating to the alarm not being output. Therefore, it is possible to properly output an alarm so as to reduce discomfort caused to the driver.
In the vehicle alarm device 40 according to the present embodiment, the deceleration threshold F1 is arranged to increase as the acquisition value C of the time to collision decreases.
In general, as the time to collision increases, the possibility of collision decreases, and as the time to collision decreases, the probability of collision increases. In this connection, in the vehicle alarm device 40 according to the present embodiment, the deceleration threshold F1 decreases when the probability of collision decreases, so that excessive alarm output can be suppressed, and when the probability of collision increases, the deceleration threshold F1 increases, so that an alarm can be reliably output a the situation in which the driver intuitively predicts a collision between the vehicle 30 and the collision object P and senses a risk of the collision. Therefore, it is possible to properly output an alarm so as to reduce discomfort caused to the driver.
The vehicle alarm device 40 according to the present embodiment can execute alarm prohibition control in accordance with the relative distance as in the case of the first embodiment. Therefore, as in the first embodiment, the vehicle alarm device 40 according to the present embodiment can provide the advantageous effects associated with the alarm prohibition control in accordance with the relative distance.
Although the embodiments of the present invention have been described in the foregoing, the present invention is not limited to the embodiments disclosed. Modifications and changes in the present invention are possible based on the technical scope of the present invention.

[Reference Signs List]

10...Vehicle, Ego vehicle
20...Vehicle alarm device, 21...Collision information acquisition unit, Autonomous emergency braking unit, AEB unit, 22...Alarm control unit, 23...Brake operation recognition unit, 24...Object deceleration determination unit, 25...Brake count acquisition unit
30...Vehicle, Ego vehicle
40...vehicle alarm device, 41...Collision information acquisition unit, Autonomous emergency braking unit, AEB unit, 42...Alarm control unit, 43...Vehicle deceleration acquisition unit, 44...Vehicle deceleration determination unit, 45...Brake count acquisition unit
A... Acquisition value of relative distance, Horizontal axis, B...Acquisition value of relative speed, C...Acquisition value of time to collision, Acquisition value of TTC, Horizontal axis, C1...Time to collision threshold, TTC threshold, D...Acquisition value of count of brake operation, Vertical axis, E...Acquisition value of vehicle speed, E1...vehicle speed threshold, F...Acquisition value of deceleration, Vertical axis, F1...Deceleration threshold
P...Collision object, Another vehicle

Claims

A vehicle alarm device, comprising:
a collision information acquisition unit configured to acquire a relative distance between a vehicle and a collision object located in an advance direction of the vehicle, a relative speed between the vehicle and the collision object, and time to collision based on the relative distance and the relative speed;

an alarm control unit configured to execute alarm output control for outputting an alarm when an acquisition value of the time to collision acquired by the collision information acquisition unit is equal to or less than a predetermined time to collision threshold; and

a brake operation recognition unit configured to recognize a brake operation by a driver of the vehicle, wherein:
the vehicle alarm device includes an object deceleration determination unit configured to determine whether or not there is deceleration of the collision object based on an acquisition value of the relative speed acquired by the collision information acquisition unit; and

the alarm control unit is configured to be able to execute alarm prohibition control for prohibiting output of the alarm when the object deceleration determination unit determines that there is no deceleration of the collision object and the brake operation recognition unit recognizes the brake operation.
A vehicle alarm device, comprising:
a collision information acquisition unit configured to acquire a relative distance between a vehicle and a collision object located in an advance direction of the vehicle, a relative speed between the vehicle and the collision object, and time to collision based on the relative distance and the relative speed;

an alarm control unit configured to execute alarm output control for outputting an alarm when an acquisition value of the time to collision acquired by the collision information acquisition unit is equal to or less than a predetermined time to collision threshold; and

a vehicle deceleration acquisition unit configured to acquire a deceleration of the vehicle, wherein:
the vehicle alarm device includes a vehicle deceleration determination unit that determines whether or not an acquisition value of the deceleration acquired by the vehicle deceleration acquisition unit is equal to or greater than a predetermined deceleration threshold; and

the alarm control unit is configured to be able to execute alarm prohibition control for prohibiting output of the alarm when the vehicle deceleration determination unit determines that the acquisition value of the deceleration is equal to or greater than the predetermined deceleration threshold.
The vehicle alarm device according to claim 2, wherein
the deceleration threshold is arranged to increase as the acquisition value of the time to collision decreases.
The vehicle alarm device according to any one of claims 1 to 3, comprising
a brake count acquisition unit configured to acquire a count of brake operation by the driver of the vehicle, wherein:
the alarm control unit is configured to be able to execute the alarm prohibition control that prohibits output of the alarm when an acquisition value of the relative distance acquired by the collision information acquisition unit is equal to or greater than a predetermined relative distance threshold; and

the relative distance threshold is changed based on relationship between the acquisition value of the relative distance and an acquisition value of the count of the brake operation acquired by the brake count acquisition unit.