Driving assistance device

Abstract

To provide a driving support device capable of reducing possibility that a driver feels that notification control and / or deceleration control is troublesome.SOLUTION: The driving assistance device is configured to perform notification control for notifying the driver of the presence of the obstacle when a contact risk between the obstacle and the vehicle is equal to or greater than a first threshold value, and to perform deceleration control for decelerating the vehicle when the contact risk is equal to or greater than a second threshold value greater than the first threshold value. Further, the driving support device is configured to specify a recognition level of the driver with respect to the notification by the notification control, and change a control mode of at least one of the notification control and the deceleration control based on the recognition level.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a driving assistance device that performs notification control to notify a driver of the presence of an obstacle and deceleration control to decelerate a vehicle to reduce the risk of contact with the obstacle. [Background technology]

[0002] Conventionally, there are known driving assistance devices that execute deceleration control when the risk of contact with an obstacle increases. For example, the driving assistance device described in Patent Document 1 (hereinafter referred to as the "conventional device") executes deceleration control when both of the following execution conditions 1 and 2 are met in order to avoid executing unnecessary deceleration control. Execution condition 1: A collision between the vehicle and an obstacle is predicted within a range from the center of the vehicle that is smaller in width than the estimated path of the vehicle. Execution condition 2: The obstacle is located within a predetermined range from the center of the vehicle's estimated path. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-182768 Summary of the Invention

[0004] A driving assistance device is known that performs a notification control to notify a driver of the presence of an obstacle before executing a deceleration control. If the deceleration control is executed when the driver is sufficiently aware of the notification of the notification control, the driver may find the deceleration control annoying. Similarly, if the notification control is continued when the driver is sufficiently aware of the notification of the notification control, the driver may find the notification control annoying.

[0005] The present invention has been made to address the above-mentioned problems. That is, one of the objects of the present invention is to provide a driving assistance device that can reduce the possibility that the driver will find the notification control and / or deceleration control annoying.

[0006] The driving assistance device of the present invention (hereinafter referred to as "the device of the present invention") is configured to perform notification control to notify the driver of the presence of an obstacle (OB) when the risk of contact between the obstacle (OB) and the vehicle (VA) is equal to or greater than a first threshold (steps 525, 535, and 540), and to perform deceleration control to decelerate the vehicle when the risk of contact is equal to or greater than a second threshold that is greater than the first threshold (steps 560 and 570). Furthermore, the driving assistance device Identifying the driver's awareness level regarding the notification by the notification control (steps 400 to 495); changing a control mode of at least one of the notification control and the deceleration control based on the recognition level (steps 520 to 540, steps 555 to 570); It is structured as follows.

[0007] According to the device of the present invention, the control mode of at least one of the notification control and the deceleration control is changed based on the recognition level. By changing the control mode when the recognition level is high so that it is more suppressed than when the recognition level is low, it is possible to reduce the possibility that the same notification control and deceleration control will be executed when the driver is aware of the notification target as when the driver is not aware of the notification target. Therefore, it is possible to reduce the possibility that the driver will find the notification control and the deceleration control annoying. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic system configuration diagram of a driving assistance device according to an embodiment of the present invention; [Figure 2] 1 is an explanatory diagram illustrating an outline of an operation of a driving assistance device according to an embodiment of the present invention; [Figure 3] 2 is a flowchart of a notification determination routine executed by a CPU of the ECU shown in FIG. 1. [Figure 4] 2 is a flowchart of a recognition level identification routine executed by a CPU of the ECU shown in FIG. 1. [Figure 5]2 is a flowchart of a control execution routine executed by a CPU of the ECU shown in FIG. 1. DETAILED DESCRIPTION OF THE INVENTION

[0009] As shown in FIG. 1, a driving assistance device 10 according to this embodiment (hereinafter referred to as "the device 10") is applied to a vehicle VA.

[0010] The device 10 includes the components shown in FIG. 1. In this specification, "ECU 20" refers to an electronic control device that includes a microcomputer as its main component. The ECU 20 is also referred to as a control unit, a controller, and a computer. The microcomputer includes a CPU (processor), a ROM, a RAM, an interface, and the like. The functions realized by the ECU 20 may be realized by multiple ECUs.

[0011] The rear camera 22 captures a rearward image by capturing an image of the scenery behind the vehicle VA. The driver's seat camera 24 captures a driver's seat image by capturing an image of a predetermined area of ​​the driver's seat of the vehicle VA. The predetermined area is set to include the face of an occupant (i.e., the driver) sitting in the driver's seat. The ECU 20 captures a rearward image and a driver's seat image from the rear camera 22 and the driver's seat camera 24, respectively.

[0012] The shift position sensor 26 detects the set position SP of a shift lever (not shown) mounted on the vehicle VA. The driver can set the shift lever to any of a forward position (D range), a reverse position (R range), a neutral position (N range), and a parking position (P range). The acceleration sensor 28 detects the acceleration G in the longitudinal direction of the vehicle VA. The ECU 20 acquires the detection values ​​from the shift position sensor 26 and the acceleration sensor 28, respectively, and identifies the set position SP of the shift lever and the acceleration G of the vehicle VA.

[0013] The power train actuator 30 changes the driving force generated by a drive device (e.g., an internal combustion engine and / or an electric motor) of the vehicle VA. The brake actuator 32 changes the braking force applied to the vehicle VA. The display device 34 displays a notification screen 200 (see FIG. 2), which will be described later. The speaker 36 produces a notification sound, which will be described later.

[0014] <Notification control> When an obstacle OB having a TTC (Time To Collision) of less than or equal to the first threshold time T1th is present behind the vehicle VA while the vehicle VA is reversing (see time t1 in FIG. 2), the ECU 20 executes normal notification control to notify the driver of the presence of this obstacle. Specifically, the ECU 20 displays a notification screen 200 (see FIG. 2) on the display device 34 and causes the speaker 36 to emit a predetermined notification sound. A rear image is displayed on the notification screen 200. As shown in FIG. 2, on the notification screen 200, a notification target image 205 representing an image of an obstacle OB (hereinafter referred to as "notification target") having a TTC of less than or equal to the first threshold time T1th is surrounded by a rectangle 210, thereby highlighting the notification target image 205.

[0015] TTC represents the time it takes for the obstacle OB to come into contact with the vehicle VA. It can also be expressed as representing the risk of contact between the obstacle OB and the vehicle VA. The shorter the TTC, the higher the risk of contact. TTC is obtained by dividing the distance between the obstacle OB and the vehicle VA by the relative speed of the obstacle OB with respect to the vehicle VA. The distance and the relative speed are obtained based on a rear image. TTC is sometimes referred to as a contact risk index value or contact time.

[0016] <Deceleration control> If the vehicle VA further moves backward after the above-mentioned notification control is executed and the TTC becomes equal to or shorter than the second threshold time T2th, which is shorter than the first threshold time T1th (see time t2 in FIG. 2), the ECU 20 performs deceleration control to decelerate the vehicle VA.

[0017] (Overview of operation) The ECU 20 determines the driver's awareness level regarding the notification of the notification control, and changes the control mode of at least one of the notification control and the deceleration control based on the awareness level. Specifically, when the awareness level is high, the ECU 20 suppresses at least one of the notification control and the deceleration control more than when the awareness level is low.

[0018] As a result, when the recognition level is high, the notification control and / or deceleration control are executed at a more restrained level than when the recognition level is low. Therefore, even though the driver is aware of the presence of the obstacle OB, the possibility that the notification control and / or deceleration control will be executed at the same control level as when the driver is not aware of the presence of the obstacle OB can be reduced. Therefore, the possibility that the driver will find the notification control and / or deceleration control annoying can be reduced.

[0019] The ECU 20 identifies the recognition level based on the following viewpoints 1 to 3. Viewpoint 1: The viewing time Tm representing the time during which the driver views the notification screen 200 (see FIG. 2). Viewpoint 2: Display state of the notification target image 205 (see FIG. 2) Viewpoint 3: Driver's line of sight to the notification target image 205

[0020] More specifically, after the notification control is executed (after time t1 in FIG. 2), the ECU 20 determines whether the following first to fourth conditions are met, thereby identifying the recognition level.

[0021] <First condition> The first condition is satisfied when the looking time Tm is equal to or greater than a threshold looking time Tmth. The first condition is based on the above-mentioned viewpoint 1. The ECU 20 determines whether the driver is viewing the notification screen 200 based on the driver's seat image.

[0022] <Second condition> The second condition is met when there is one notification target image 205 on the notification screen 200. The second condition is a condition based on the above-mentioned viewpoint 2. Note that all obstacles OB having a TTC equal to or less than the first threshold time T1th are to be notified on the notification screen 200. When there are multiple objects to be notified, each of the multiple notification object images 205 is highlighted using a rectangle 210.

[0023] <Third Condition> The third condition is met when the display ratio R is equal to or greater than the threshold ratio Rth. The third condition is a condition based on the above-mentioned viewpoint 2. The display ratio R represents the ratio of the portion of the notification target that is displayed as the notification target image 205 to the entire obstacle OB that is the notification target.

[0024] The ECU 20 stores in advance an overall area representing the overall area of ​​each type of notification object (vehicle, person, tree, etc.). The ECU 20 identifies the type of notification object based on the rear image and acquires the overall area of ​​that type. The ECU 20 then identifies the display area of ​​the notification object image 205 based on the distance between the notification object and the vehicle VA (more specifically, the rear camera 22) and the number of pixels of the notification object image 205. The ECU 20 acquires the display ratio R by dividing the identified display area by the acquired overall area.

[0025] <Fourth Condition> The fourth condition is met when the driver's line of sight is directed toward the notification target image 205 on the notification screen 200. The fourth condition is a condition based on the above-mentioned viewpoint 3. The ECU 20 determines whether the driver's line of sight is directed toward the notification target image 205 based on the driver's seat image.

[0026] <Awareness Level 1> If at least one of the first to third conditions is not met, the ECU 20 specifies the recognition level as "1." If the first condition is not met, the viewing time Tm is short, and therefore it is highly likely that the driver does not recognize the notification target. If the second condition is not met, there are a plurality of notification targets, and it is highly likely that the driver has not recognized all of the notification targets. If the third condition is not met, the display ratio R is low, and therefore it is highly likely that the driver is not aware of the notification target. In this embodiment, the recognition level is specified (set) to one of "1," "2," and "3." The recognition level "1" is the lowest recognition level, and the recognition level "3" is the highest recognition level.

[0027] When the TTC of the obstacle OB present behind the vehicle VA is equal to or shorter than the first threshold time T1th, the ECU 20 executes normal notification control. In the normal notification control, the notification screen 200 is displayed on the display device 34 and a notification sound is emitted from the speaker 36, as described above. Thereafter, if the ECU 20 determines that the recognition level is "1," it continues the normal notification control. Thereafter, if the TTC of the obstacle OB becomes the second threshold time T2th and the recognition level is "1," the ECU 20 executes normal deceleration control. In the normal deceleration control, the ECU 20 sets the target deceleration Gtgt to the normal target deceleration Gn.

[0028] <Cognitive Level 2 and Cognitive Level 3> When all of the first to third conditions are met, the ECU 20 determines whether the fourth condition is met. When the fourth condition is not met, there is a higher possibility that the driver does not recognize the notification target than when the fourth condition is met. Therefore, when all of the first to third conditions are met but the fourth condition is not met, the ECU 20 determines the recognition level as "2." When the first to fourth conditions are met, the ECU 20 determines the recognition level as "3."

[0029] If the ECU 20 determines that the recognition level is "2" before the TTC becomes equal to or less than the second threshold time T2th, the ECU 20 switches from the normal notification control to the first suppression notification control. Specifically, in the first suppression notification control, the notification screen 200 is displayed on the display device 34, but no notification sound is emitted from the speaker 36. Therefore, the first suppression notification control is a more suppressed control than the normal notification control. In other words, the notification strength (control strength) of the first suppression notification control is weaker than that of the normal notification control.

[0030] If the recognition level is "2" when the TTC becomes equal to or less than the second threshold time T2th, the ECU 20 executes suppressed deceleration control. In the suppressed deceleration control, the ECU 20 sets the target deceleration Gtgt to a suppressed target deceleration Gs that is smaller than the normal target deceleration Gn. Therefore, the suppressed deceleration control is a more suppressed control than the normal deceleration control. In other words, the strength of deceleration (control strength) of the suppressed deceleration control is weaker than that of the normal deceleration control.

[0031] If the ECU 20 determines that the recognition level is "3" before the TTC becomes equal to or less than the second threshold time T2th, the ECU 20 switches from normal notification control to second suppression notification control. Specifically, in the second suppression notification control, the rectangle 210 is not displayed on the notification screen 200, and therefore the notification target image 205 is not highlighted. Note that in the second suppression notification control, similar to the first suppression notification control, no notification sound is emitted from the speaker 36. Therefore, the second suppression notification control is a more suppressed control than the first suppression notification control. In other words, the notification strength (control strength) of the second suppression notification control is weaker than that of the first suppression notification control.

[0032] If the recognition level is "3" when the TTC becomes equal to or less than the second threshold time T2th, the ECU 20 does not execute deceleration control. Since deceleration control is not executed when the recognition level is "3," it can also be expressed as executing control that is more restrained than suppressed deceleration control. In other words, the strength of deceleration (control strength) when the recognition level is "3" is weaker than suppressed deceleration control.

[0033] As described above, as the recognition level increases, the notification control and deceleration control are suppressed. This reduces the possibility that notification control and deceleration control that are the same as when the driver does not recognize the notification target (stronger control strength) are executed even when the driver recognizes the notification target. This reduces the possibility that the driver finds the notification control and deceleration control annoying.

[0034] (Specific operation) The CPU of the ECU 20 of the device 10 executes the routines shown in the flowcharts of FIGS. 3 to 5 each time a predetermined time period has elapsed.

[0035] <Notification determination routine> When an appropriate time arrives, the CPU starts the process from step 300 in Fig. 3, and the process proceeds to step 305. In step 305, the CPU determines whether or not the notification flag Xno is "0".

[0036] The notification flag Xno is set to "1" when notification control is executed, and is set to "0" when notification control is not executed. The notification flag Xno is set to "0" in an initialization routine. The initialization routine is executed by the CPU when the ignition key switch (not shown) of the vehicle VA is changed from the OFF position to the ON position.

[0037] If the notification flag Xno is “1”, the CPU determines “Yes” in step 305 and the process proceeds to step 310 .

[0038] In step 310, the CPU determines whether the set position SP of the shift lever is in the reverse position (R range).

[0039] If the set position SP is the reverse position, the CPU determines "Yes" in step 310 and executes steps 315 and 320.

[0040] Step 315: The CPU recognizes the obstacle OB based on the reversing image. Step 320: The CPU determines whether the TTC of the obstacle OB is less than or equal to the first threshold time T1th.

[0041] If TTC is greater than the first threshold time T1th, the CPU determines "No" in step 320. Thereafter, the process proceeds to step 395, and the CPU temporarily ends this routine.

[0042] On the other hand, if the TTC is equal to or less than the first threshold time T1th, the CPU determines "Yes" in step 320, and the process proceeds to step 325. In step 325, the CPU sets the notification flag Xno to "1" and sets the viewing time timer TM to "0." The viewing time timer TM is a timer for counting the viewing time Tm. Furthermore, in step 325, the CPU sets the recognition level to "1." Thereafter, the process proceeds to step 395, and the CPU temporarily ends this routine.

[0043] If the notification flag Xno is "1" when the process proceeds to step 305, the CPU determines whether the termination condition is met. If any of the following conditions E1 to E3 is met, the termination condition is met. Condition E1: The vehicle VA stops. Condition E2: A predetermined time has elapsed since the start of deceleration control. Condition E3: The driver operates the brake pedal (not shown).

[0044] If the termination condition is not met, the CPU determines "No" in step 330. Thereafter, the process proceeds to step 395, where the CPU temporarily terminates this routine.

[0045] If the termination condition is met, the CPU determines "Yes" in step 330, and the process proceeds to step 335. In step 335, the CPU sets the notification flag Xno to "0" and sets the visual recognition time timer TM to "0." Furthermore, in step 335, the CPU sets the deceleration flag Xde to "0" and sets the recognition level to "1." Thereafter, the process proceeds to step 395, and the CPU temporarily terminates this routine.

[0046] The deceleration flag Xde is set to "1" when deceleration control is executed, and is set to "0" when deceleration control is not executed. The deceleration flag Xde is set to "0" in the initialization routine.

[0047] When the process proceeds to step 310, if the set position SP is not the reverse position, the CPU determines "No" in step 310 and the process proceeds to step 335.

[0048] <Cognitive Level Identification Routine> When an appropriate time arrives, the CPU starts the process from step 400 in Fig. 4, and the process proceeds to step 405. In step 405, the CPU determines whether or not the notification flag Xno is "1".

[0049] If the notification flag Xno is "1", the CPU determines "Yes" in step 405, and the process proceeds to step 410. In step 410, the CPU determines whether the deceleration flag Xde is "0".

[0050] If the deceleration flag Xde is "0", the CPU determines "Yes" in step 410, and the process proceeds to step 415. In step 415, the CPU determines whether the set position SP is the reverse position.

[0051] If the set position SP is the reverse position, the CPU determines "Yes" in step 415, and the process proceeds to step 420. In step 420, the CPU determines whether the driver's line of sight is directed toward the notification screen 200 (i.e., whether the driver is viewing the notification screen 200).

[0052] If the driver's line of sight is directed toward the notification screen 200, the CPU determines "Yes" in step 420 and executes steps 425 and 430. Step 425: The CPU adds "1" to the viewing time timer TM. Step 430: The CPU determines whether the viewing time timer TM is equal to or greater than the threshold value TMth. The threshold value TMth is set to the value of the viewing time timer TM when the viewing time Tm is equal to or greater than the threshold viewing time Tmth.

[0053] If the looking time timer TM is less than the threshold value TMth (i.e., if the looking time Tm is less than the threshold looking time Tmth), the first condition is not met. In this case, the CPU determines "No" in step 430, and the process proceeds to step 435. In step 435, the CPU sets the recognition level to "1." Thereafter, the process proceeds to step 495, and the CPU temporarily ends this routine.

[0054] When the process proceeds to step 430, if the looking time timer TM is equal to or greater than the threshold value TMth (i.e., if the looking time Tm is equal to or greater than the threshold looking time Tmth), the first condition is met. In this case, the CPU determines “Yes” in step 430, and the process proceeds to step 440.

[0055] In step 440, the CPU determines whether or not there is one notification target image 205.

[0056] If there are multiple notification target images 205, the second condition is not met. In this case, the CPU determines "No" in step 440 and sets the recognition level to "1" in step 435. Thereafter, the process proceeds to step 495, where the CPU temporarily ends this routine.

[0057] The second condition is met if there is one notification target image 205. In this case, the CPU determines "Yes" in step 440, and the process proceeds to step 445.

[0058] In step 445, the CPU determines whether the display ratio R of the notification target image 205 is equal to or greater than the threshold ratio Rth. If the display ratio R is less than the threshold ratio Rth, the third condition is not met. In this case, the CPU determines "No" in step 445 and sets the recognition level to "1" in step 435. Thereafter, the process proceeds to step 495, and the CPU temporarily ends this routine.

[0059] If the display ratio R is equal to or greater than the threshold ratio Rth, the third condition is met. In this case, all of the first to third conditions are met. The CPU determines "Yes" in step 445, and the process proceeds to step 450.

[0060] In step 450, the CPU determines whether the driver's gaze is directed toward the notification target image 205. Specifically, the CPU identifies the direction of the driver's face and the direction of the driver's gaze based on the driver's seat image. Furthermore, the CPU acquires the height distance between the driver's eyes and the display device 34 based on the driver's seat image. The CPU identifies the driver's gaze position on the notification screen 200 based on the driver's face direction, the direction of the gaze, and the height distance. If the gaze position is included in the "range obtained by enlarging the notification target image 205 based on a predetermined magnification factor," the CPU determines that the driver's gaze is directed toward the notification target image 205.

[0061] If the driver's line of sight is not directed toward the notification target image 205, the fourth condition is not met. In this case, the CPU determines "No" in step 450, and the process proceeds to step 455. In step 455, the CPU sets the recognition level to "2." Thereafter, the process proceeds to step 495, and the CPU temporarily ends this routine.

[0062] If the driver's line of sight is directed toward the notification target image 205, the fourth condition is met. In this case, the CPU determines "Yes" in step 450, and the process proceeds to step 460. In step 460, the CPU sets the recognition level to "3." Thereafter, the process proceeds to step 495, and the CPU temporarily ends this routine.

[0063] If the notification flag Xno is "0" when the process proceeds to step 405, the CPU determines "No" in step 405, and the process proceeds to step 465. In step 465, the CPU determines whether the above-mentioned termination condition is met.

[0064] If the termination condition is not met, the CPU determines "No" in step 465. Thereafter, the process proceeds to step 495, and the CPU temporarily terminates this routine.

[0065] If the termination condition is met, the CPU determines "Yes" in step 465, and the process proceeds to step 470. Step 470 is the same process as step 335 shown in Figure 3, so its description will be omitted. Thereafter, the process proceeds to step 495, and the CPU temporarily ends this routine.

[0066] If the deceleration flag Xde is "1" when the process proceeds to step 410, the CPU determines "No" in step 410, and the process proceeds to step 465. Therefore, if the deceleration flag Xde is "1", the recognition level is not newly determined. If the control mode of the deceleration control is changed due to a change in the recognition level after the deceleration control is executed, the driver may feel uncomfortable with the deceleration control. In this embodiment, once the deceleration control is executed, the recognition level is not newly determined, and therefore the control mode of the deceleration control is not changed. This reduces the possibility that the driver will feel uncomfortable with the deceleration control.

[0067] When the process proceeds to step 415, if the set position SP is not the reverse position, the CPU determines "No" in step 415 and the process proceeds to step 470.

[0068] <Control execution routine> When an appropriate time arrives, the CPU starts the process from step 500 in Fig. 5, and the process proceeds to step 505. In step 505, the CPU determines whether or not the notification flag Xno is "1".

[0069] If the notification flag Xno is "1", the CPU determines "Yes" in step 505, and the process proceeds to step 510. In step 510, the CPU determines whether the deceleration flag Xde is "0".

[0070] If the deceleration flag Xde is “0”, the CPU determines “Yes” in step 510 and executes steps 515 and 520 . Step 515: The CPU identifies an obstacle OB having a TTC equal to or less than the first threshold time T1th as an object to be notified. Step 520: The CPU determines whether the notification level is "1".

[0071] If the notification level is "1", the CPU determines "Yes" in step 520, and the process proceeds to step 525. In step 525, the CPU executes normal notification control to notify the driver of the presence of the obstacle OB that is the notification target identified in step 515.

[0072] If the notification level is not "1" (i.e., if the notification level is "2" or "3"), the CPU determines "No" in step 520, and the process proceeds to step 530. In step 530, the CPU determines whether the notification level is "2".

[0073] If the notification level is "2", the CPU determines "Yes" in step 530, and the process proceeds to step 535. In step 535, the CPU executes first suppression notification control.

[0074] If the notification level is not "2" (that is, if the notification level is "3"), the CPU determines "No" in step 530, and the process proceeds to step 540. In step 540, the CPU executes second suppression notification control.

[0075] After the CPU executes notification control in any one of step 525, step 535, and step 540, the process proceeds to step 545. In step 545, the CPU determines whether or not the TTC is equal to or less than the second threshold time T2th.

[0076] If TTC is greater than the second threshold time T2th, the CPU determines "No" in step 545. Thereafter, the process proceeds to step 595, and the CPU temporarily ends this routine.

[0077] If TTC is equal to or less than the second threshold time T2th, the CPU determines "Yes" in step 545 and executes steps 550 and 555. Step 550: The CPU sets the deceleration flag Xde to “1”. Step 555: The CPU determines whether the notification level is "1".

[0078] If the notification level is "1", the CPU determines "Yes" in step 555, and the process proceeds to step 560. In step 560, the CPU executes normal deceleration control. Specifically, the CPU controls the powertrain actuator 30 and the brake actuator 32 so that the acceleration G matches the normal target deceleration Gn. Thereafter, the process proceeds to step 595, and the CPU temporarily ends this routine.

[0079] If the notification level is not "1" (i.e., if the notification level is "2" or "3"), the CPU determines "No" in step 555, and the process proceeds to step 565. In step 565, the CPU determines whether the notification level is "2". If the notification level is "2", If "Gs=Gs", the CPU determines "Yes" in step 565, and the process proceeds to step 570. In step 570, the CPU executes suppression deceleration control. Specifically, the CPU controls the powertrain actuator 30 and the brake actuator 32 so that the acceleration G matches the suppression target deceleration Gs. Thereafter, the process proceeds to step 595, and the CPU temporarily ends this routine.

[0080] If the notification level is not "2" (i.e., if the notification level is "3"), the CPU determines "No" in step 565. Thereafter, the process proceeds to step 595, and the CPU temporarily ends this routine. As a result, if the notification level is "3", deceleration control is not executed.

[0081] If the deceleration flag Xde is "1" when the process proceeds to step 510, the CPU determines "No" in step 510, and the process proceeds to step 575. In step 575, the CPU determines whether or not the above-mentioned termination condition is met. Note that in step 575, the CPU may determine that the termination condition is met even when the set position SP is not the reverse position.

[0082] If the termination condition is not met, the CPU determines "No" in step 575, and the process proceeds to step 515. On the other hand, if the termination condition is met, the CPU determines "Yes" in step 575, and the process proceeds to step 580. Step 580 is the same process as step 335 shown in Figure 3, so its description will be omitted. Thereafter, the process proceeds to step 595, and the CPU temporarily ends this routine.

[0083] According to this embodiment, the notification control and deceleration control are suppressed as the driver's awareness level increases. This reduces the possibility that notification control and deceleration control with strong control strength are executed even though the driver is aware of the notification target. Therefore, it reduces the possibility that the driver will find the notification control and deceleration control annoying.

[0084] (First Modification) In the above embodiment, the control modes of both the notification control and the deceleration control are changed based on the recognition level, but the control mode of either the notification control or the deceleration control may be changed based on the recognition level.

[0085] (Second Modification) In the above embodiment, deceleration control is not executed when the recognition level is "3" (see "No" in step 565 shown in FIG. 5), but deceleration control that is more suppressed than the suppressed deceleration control may be executed when the recognition level is "3." In this deceleration control, the target deceleration Gtgt is set to a target deceleration Gs' that is smaller than the suppressed target deceleration Gs.

[0086] (Third Modification) The thresholds used in the first to fourth conditions of the above embodiment (the "threshold viewing time Tmth" of the first condition, the "number of notification target images 205" of the second condition, the "threshold ratio Rth" of the third condition, and the "magnification ratio" of the fourth condition) may be changeable based on the driver's specification. In other words, the ease with which the first to fourth conditions are met may be changeable (the criteria for raising or lowering the recognition level may be changeable based on the driver's specification).

[0087] (Fourth Modification) In the above embodiment, the TTC is used as the index value of the contact risk, but this is not limiting. For example, the distance between the obstacle OB and the vehicle VA may be used as the index value of the contact risk.

[0088] (Fifth Modification) The method of suppressing notification control is not limited to the method described in the above embodiment. For example, notification control may be suppressed depending on the color of rectangle 210. Specifically, rectangle 210 may be displayed in red during normal notification control, in yellow during first suppression notification control, and in white during second suppression notification control.

[0089] (Sixth Modification) In the above embodiment, the target deceleration Gtgt of the deceleration control is set to a smaller value as the recognition level increases, but the method of suppressing the deceleration control is not limited to this. For example, the deceleration control may be suppressed by delaying the start timing of the deceleration control as the recognition level increases. Specifically, the second threshold time T2th may be set to a smaller value as the recognition level increases.

[0090] (Seventh Modification) In the above embodiment, the notification control and deceleration control are executed when the vehicle VA is moving backward, but the notification control and deceleration control may also be executed when the vehicle VA is moving forward.

[0091] (Eighth Modification) In the above embodiment, the recognition level is set to "2" or "3" when all of the first to third conditions are met, but the recognition level may be set to "2" or "3" when at least one of the first to third conditions is met. Furthermore, the determination of the fourth condition is not essential.

[0092] (Ninth Modification) In the above embodiment, once deceleration control is executed, the recognition level is not newly determined, but this is not limiting. Even if deceleration control is executed once, the recognition level may be newly determined and the control mode of deceleration control may be changed.

[0093] The device 10 can be applied to vehicles such as internal combustion engine vehicles, hybrid vehicles, plug-in hybrid vehicles, fuel cell vehicles, and electric vehicles. Furthermore, the device 10 can also be applied to autonomous vehicles. [Explanation of symbols]

[0094] 10...driving assistance device, 20...ECU, 22...rear camera, 24...driver's seat camera, 30...power train actuator, 32...brake actuator, 34...display device, 36...speaker

Claims

1. A driving assistance device configured to perform notification control to notify a driver of the presence of an obstacle when a contact risk between an obstacle and a vehicle is equal to or greater than a first threshold, and to perform deceleration control to decelerate the vehicle when the contact risk is equal to or greater than a second threshold that is greater than the first threshold, The driving assistance device Identifying the driver's awareness level regarding the notification by the notification control; changing a control mode of at least one of the notification control and the deceleration control based on the recognition level; A driving assistance device configured as follows.

2. The driving assistance device according to claim 1, The driving assistance device In the notification control, a notification screen for notifying the driver of the presence of the obstacle is displayed on a display device disposed in the vehicle, identifying the recognition level based on a visual recognition state of the notification screen by the driver; When the recognition level is high, at least one of the notification control and the deceleration control is suppressed compared to when the recognition level is low. A driving assistance device configured as follows.

3. The driving assistance device according to claim 2, The driving assistance device is configured to weaken the strength of deceleration of the deceleration control when the recognition level is high compared to when the recognition level is low. Driving assistance device.

4. The driving assistance device according to claim 2, The driving assistance device is configured to identify the recognition level based on at least one of the viewing time the driver spends viewing the notification screen, the display state of the obstacle on the notification screen, and the driver's line of sight toward the obstacle displayed on the notification screen.

5. The driving assistance device according to claim 1, The driving assistance device is configured to change a criterion for determining whether to raise or lower the recognition level based on a designation by the driver.

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