Vehicle driving support device and driving support method

Abstract

To provide a vehicle driving support device capable of performing a collision avoidance support operation for avoiding a collision between an own vehicle and another vehicle on a collision course at appropriate timing.SOLUTION: A driving support ECU determines whether another vehicle traveling to generate a collision course phenomenon with respect to an own vehicle exists, based on position information on the other vehicle positioned in a diagonally front area of the own vehicle. The ECU determines whether a predetermined performance condition for performing a collision avoidance support operation is established when it is determined that the other vehicle exists on the collision course, and performs the collision avoidance support operation when it is determined that the performance condition is established. The ECU changes the performance condition based on an approach direction determination result on whether the other vehicle on the collision course is approaching from a direction of a driver's seat side of the own vehicle or from a direction of a front passenger seat side and also based on a visual recognition determination result on whether there is a higher probability that the driver of the own vehicle is visually recognizing the other vehicle on the collision course.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a vehicle driving assistance device and a driving assistance method that can reduce the possibility of a collision between a host vehicle and another vehicle due to a collision course phenomenon. [Background technology]

[0002] Conventionally, when the collision course phenomenon causes the driver of a vehicle to become aware of "other vehicles that are highly likely to collide with the vehicle (other vehicles on a collision course)" late, devices have been known that detect such other vehicles and perform collision avoidance assistance operations (e.g., automatic braking operations) at a predetermined timing (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-58827 A [Patent Document 2] JP 2018-206210 A Summary of the Invention

[0004] However, with conventional devices, there were cases where the collision avoidance support operation was performed even when the driver was aware of another vehicle on the collision course, resulting in the driver feeling that the collision avoidance support operation was unnecessary or becoming distrustful of the collision avoidance support operation.

[0005] The present invention has been made to solve the above problems. That is, one of the objects of the present invention is to provide a vehicle driving support device that can execute a collision avoidance support operation for avoiding a collision between the host vehicle and another vehicle on a collision course at a more appropriate timing.

[0006] One aspect of the vehicle driving assistance device of the present invention (hereinafter also referred to as the "device of the present invention") is as follows: The controller (10) acquires other vehicle information, which is information about the position of another vehicle (OV) located in a diagonally forward area of ​​the host vehicle (HV) relative to the host vehicle, and when it determines based on the other vehicle information that there is another vehicle on a collision course that is traveling in a manner that causes a collision course phenomenon with the host vehicle (S310, S315: Yes), it determines whether or not an execution condition for executing a collision avoidance support operation to avoid a collision between the host vehicle and the other vehicle on the collision course is established (S360), and starts execution of the collision avoidance support operation when it determines that the execution condition is established (S365).

[0007] The controller: an approach direction determination result as to whether the other vehicle on the collision course is approaching from the direction of the driver's seat side of the host vehicle or from the direction of the passenger's seat side of the host vehicle; And, a visual recognition determination result as to whether or not there is a high probability that the driver of the vehicle visually recognizes another vehicle on the collision course; and changing the execution conditions (S320 to S330, S340, and S345) based on at least one of the above.

[0008] The driver's field of vision diagonally forward changes significantly depending on whether a vehicle structure (e.g., an A-pillar) is significantly included in the field of vision. That is, the driver's field of vision diagonally forward differs significantly depending on whether the other vehicle on the collision course is approaching from the driver's seat side or the passenger seat side. Therefore, whether the driver can see the other vehicle on the collision course also differs depending on the direction from which the other vehicle is approaching on the collision course. Therefore, if the execution condition is changed depending on the approach direction determination result, the collision avoidance driving operation can be started at a more appropriate timing.

[0009] Furthermore, if the execution conditions are changed in accordance with the visual recognition determination result as to whether or not the driver is visually recognizing another vehicle on the collision course, the collision avoidance driving operation can be started at a more appropriate timing.

[0010] In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses with respect to the configuration of the invention corresponding to the embodiments. However, each component of the present invention is not limited to the embodiments defined by the names and / or symbols. The present invention also covers a vehicle driving assistance method and a program thereof. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of a vehicle driving assistance device according to an embodiment of the present invention; [Diagram 2] FIG. 1 is a diagram for explaining the collision course phenomenon. [Diagram 3] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 4] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Diagram 5] This is a routine executed by the CPU of the driving assistance ECU shown in FIG. [Figure 6] 13(A) and 13(B) are diagrams showing the driver's line of sight. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A vehicle driving support device DS (hereinafter referred to as "device DS") according to an embodiment of the present invention includes the components shown in Fig. 1 and is applied to (mounted on) a host vehicle. The host vehicle may be any of a vehicle powered by an internal combustion engine, a vehicle powered by an electric motor, a hybrid vehicle, and the like.

[0013] In this specification, an "ECU" is an electronic control device (control unit) equipped with a microcomputer including a CPU (processor), ROM, RAM, an interface, etc. An ECU is also called a controller or a computer. The multiple ECUs shown in FIG. 1 are connected to each other via a CAN (Controller Area Network) so that they can exchange information with each other. Some or all of these multiple ECUs may be integrated into one ECU.

[0014] As described later in detail, when a "vehicle on a collision course" exists, the driving assistance ECU 10 executes a "collision avoidance control / collision damage reduction control" as a driving assistance control. The "vehicle on a collision course" is a vehicle that the driver of the host vehicle finds difficult to recognize as a vehicle that is likely to collide with the host vehicle due to the collision course phenomenon. As shown in FIG. 2, the collision course phenomenon is a phenomenon in which the host vehicle HV and the other vehicle OV are both moving in a uniform linear motion toward a point P where they intersect with each other, and the angle θ between a straight line L1 parallel to the front-rear axis of the host vehicle HV and a straight line L2 passing through the driver of the host vehicle HV and the other vehicle OV is maintained at a substantially constant angle, so that the driver of the host vehicle HV erroneously recognizes the other vehicle OV as if it is stationary. When the collision course phenomenon occurs, the driver of the host vehicle HV does not perform a collision avoidance driving operation, or the execution of the collision avoidance driving operation is delayed.

[0015] 1 again, the front camera device 20 includes a front camera 21 and an image ECU 22. The front camera 21 has a left-right viewing angle indicated by lines G1 and G2 in FIG. 2, and captures images of scenes in the front and diagonally forward directions of the vehicle every time a predetermined time elapses to obtain image data. The image ECU 22 generates camera information by analyzing the image data from the front camera 21, and transmits the camera information to the driving assistance ECU 10. The camera information includes the image data itself and information such as the "position, relative longitudinal speed, relative lateral speed, and type of the captured object relative to the vehicle." Thus, the camera information includes other vehicle information that specifies the position of other vehicles located in the diagonally forward area of ​​the vehicle relative to the vehicle.

[0016] The radar device 30 is a well-known device that acquires information about targets present in the forward and diagonally forward directions of the vehicle using millimeter-wave band radio waves, and includes a radar 31 and a radar ECU 32. The radar 31 transmits millimeter waves within a detection range indicated by lines R1 and R2 in FIG. 2 every time a predetermined time elapses, and receives millimeter waves reflected by the targets. The radar 31 transmits information about the transmitted and received millimeter waves to the radar ECU 32. The radar ECU 32 acquires radar information based on the information from the radar 31, and transmits the radar information to the driving assistance ECU 10. The radar information includes the distance to the target, the direction of the target, and the relative speed of the target. Thus, the radar information includes other vehicle information that identifies the position of other vehicles located in the diagonally forward area of ​​the vehicle relative to the vehicle.

[0017] The driver monitoring device (driver monitor) 40 acquires driver gaze information indicating the state of the driver of the vehicle (including the driver's facial orientation with respect to the vehicle and the gaze direction with respect to the front of the driver's face, etc.), and acquires the "driver's gaze direction in the left-right direction with respect to the front-rear axis of the vehicle (hereinafter referred to as the "front-rear axis gaze direction")" and the "driver's gaze direction in the up-down direction (hereinafter referred to as the "up-down gaze direction")" based on the driver gaze information. The driver monitoring device 40 includes a driver monitor camera 41 and a driver monitor ECU 42. The driver monitoring device 40 itself is well known and is disclosed in, for example, JP 2019-87143 A, JP 2019-87029 A, JP 2016-38866 A, and JP 2013-152700 A.

[0018] The driver monitor camera 41 is disposed in a suitable position (for example, above the steering column) in front of the driver's seat of the vehicle. The driver monitor camera 41 captures the face of the driver at predetermined intervals, generates face image data, and transmits it to the driver monitor ECU 42.

[0019] The driver monitor ECU 42 generates a face image based on face image data from the driver monitor camera 41, rotates the generated face image, and acquires the driver's face direction based on the rotation angle of the face image when the coincidence rate between the rotated face image and pre-stored "face shape data when the driver faces forward" is maximized.

[0020] Furthermore, the driver monitor ECU 42 identifies a face area from the generated face image of the driver, and detects face parts by extracting feature points of the face parts such as the eyes, nose, and mouth. The driver monitor ECU 42 then detects the position of the Purkinje image (corneal reflection image) and the position of the pupil center, and obtains the gaze direction of the driver relative to the front and the front of the face based on the positional relationship between the Purkinje image and the pupil center. After that, the driver monitor ECU 42 obtains the driver's longitudinal gaze direction and up and down gaze direction based on the driver's facial orientation direction and the gaze direction relative to the front and the front of the face, and transmits the obtained information to the driving assistance ECU 10.

[0021] The brake ECU 50 controls a braking device of the vehicle (not shown) by driving a brake actuator 51 based on a brake pedal operation amount BP detected by a brake pedal operation amount sensor 73 (described later). That is, the brake ECU 50 adjusts the braking force applied to the host vehicle so that the deceleration (magnitude of negative acceleration) of the host vehicle increases as the brake pedal operation amount BP increases. Furthermore, the brake ECU 50 adjusts the braking force in response to an instruction (instruction signal) from the driving assistance ECU 10, and applies automatic braking to the host vehicle.

[0022] The warning ECU 60 causes the warning display device 61 to display a warning and causes the warning sound generating device 62 to generate a warning sound in response to an instruction (instruction signal) from the driving assistance ECU 10. The warning ECU 60, the warning display device 61, and the warning sound generating device 62 are also referred to as an attention calling device or an alarm device.

[0023] The driving assistance ECU 10 receives detection values ​​(output values) of the following "sensors and switches." An accelerator pedal operation amount sensor 71 that detects the amount of operation AP of the accelerator pedal of the host vehicle. An accelerator switch 72 that outputs an ON signal when the accelerator pedal of the host vehicle is depressed and outputs an OFF signal when the accelerator pedal is released. A brake pedal operation amount sensor 73 detects an operation amount BP of the brake pedal of the host vehicle. A brake switch 74 that outputs an ON signal when the brake pedal of the host vehicle is depressed and outputs an OFF signal when the brake pedal is released. A vehicle speed sensor 75 detects the speed of the host vehicle (i.e., host vehicle speed Vh). An acceleration sensor 76 that detects the acceleration Gh of the host vehicle in the longitudinal direction. A steering angle sensor 77 detects a steering angle St of the host vehicle. The steering angle St becomes "0" when a steering wheel of the host vehicle (not shown) is in a neutral position.

[0024] (Overview of operation) The device DS determines whether or not another vehicle is present on the collision course based on at least the other vehicle information. When the device DS determines that another vehicle is present on the collision course, the device DS changes the execution conditions of the collision avoidance support operation for the other vehicle on the collision course based on the determination result (approach direction determination result) of whether the other vehicle is approaching the host vehicle from "the passenger side where the driver of the host vehicle can relatively easily see the other vehicle" or "the driver side where the driver of the host vehicle can relatively hardly see the other vehicle."

[0025] Furthermore, the device DS judges whether or not the probability (likelihood) that the driver visually recognizes another vehicle on the collision course is high based on the driver's line of sight relative to the front-rear axis and whether or not a vehicle structure (e.g., an A-pillar) is present in the line of sight relative to the front-rear axis of the driver, and changes the execution conditions of the collision avoidance support operation for the other vehicle based on the level of the visual recognition probability (visual recognition judgment result). In addition, the device DS judges whether or not the driver is performing a collision avoidance driving operation (e.g., deceleration operation) to avoid a collision with another vehicle on the collision course, and changes the execution conditions of the collision avoidance support operation for the other vehicle based on the presence or absence of the collision avoidance driving operation (driving operation judgment result). In this way, the device DS changes the execution conditions of the collision avoidance support operation based on the approach direction judgment result, the visual recognition judgment result, and the driving operation judgment result, thereby changing the start timing of the collision avoidance support operation for the other vehicle on the collision course.

[0026] (Specific operation) The CPU of the driving assistance ECU 10 (hereinafter simply referred to as "CPU") executes a routine shown in the flowchart of FIG. 3 every time a predetermined time (calculation period) dt elapses.

[0027] When an appropriate time arrives, the CPU starts processing from step 300 (hereinafter, "step" is abbreviated as "S") in Fig. 3 and proceeds to S305, where it determines whether or not a target has been detected based on the camera information and radar information. If a target has not been detected, the CPU proceeds directly from S305 to S395 and ends this routine for the time being.

[0028] If a target object is detected, the CPU proceeds from S305 to S310, where it determines whether or not a collision course phenomenon is occurring (whether or not another vehicle is present on the collision course), and sets the value of the collision course flag XC based on the result. The value of this flag XC is set to "0" by an initialization routine executed by the CPU when the ignition key switch of the vehicle (not shown) is changed from the OFF position to the ON position. When the value of the collision course flag XC is "1", it indicates that a collision course phenomenon is occurring (another vehicle is present on the collision course).

[0029] More specifically, when the CPU proceeds to S310, it starts processing of the collision course phenomenon judgment subroutine shown in Fig. 4 from S400 and proceeds to S410, where it judges whether the detected target is another vehicle and whether the other vehicle (hereinafter referred to as "target vehicle") is located within a forward front range of the host vehicle. This forward front range is a strip-shaped area having the body width of the host vehicle that is set in the direction in which the host vehicle is estimated to travel.

[0030] If the target vehicle is located within the forward range of the vehicle, the collision course phenomenon does not occur. In this case, the CPU proceeds from S410 to S420, sets the value of the collision course flag XC to "0", and then proceeds to S315 in FIG. 3 via S495.

[0031] On the other hand, if the target vehicle is not located within the front range in front of the host vehicle, the CPU proceeds from S410 to S430, and determines whether the host vehicle is substantially performing uniform linear motion based on the host vehicle speed Vh, the host vehicle acceleration Gh, and the steering angle St. That is, the CPU determines that the host vehicle is performing uniform linear motion when the host vehicle speed Vh is greater than "0", the magnitude of the acceleration Gh is smaller than a small predetermined threshold Ghth, and the magnitude of the steering angle St is smaller than a small predetermined threshold Stth.

[0032] If the host vehicle is substantially performing uniform linear motion, the CPU proceeds from S430 to S440, and acquires the current position of the target vehicle relative to the host vehicle based on the host vehicle speed Vh, steering angle St, camera information, radar information, etc. Furthermore, the CPU determines whether the target vehicle is substantially performing uniform linear motion based on the previously acquired history of the target vehicle's position relative to the host vehicle, the host vehicle's movement history, and the current position of the target vehicle relative to the host vehicle (i.e., based on the change over time in the absolute position of the target vehicle).

[0033] When the target vehicle is substantially performing uniform linear motion, the CPU proceeds from S440 to S450 and determines whether the target vehicle is located within a forward diagonal range of the host vehicle. This forward diagonal range includes a range in which the angle from the front of the front-rear axis of the host vehicle to the right is "a range from a first angle "θ1-α1" to a second angle "θ1+α1"," and a range in which the angle from the front of the front-rear axis of the host vehicle to the left is "a range from a third angle "θ2-α2" to a fourth angle "θ2+α2." Note that θ1 and θ2 may be equal to each other, for example, 45°. α1 and α2 may be equal to each other, for example, 10°.

[0034] If the target vehicle is located within the diagonal range in front of the vehicle, the CPU proceeds from S450 to S460 and determines whether or not the background image of the target vehicle changes over time based on the camera information. More specifically, the CPU generates a frame in which the target vehicle is enlarged or reduced to a certain size based on the camera information, and determines whether or not the image of the object other than the target vehicle in the frame (i.e., the background image) changes over time.

[0035] For example, as shown in Fig. 2, when another vehicle OV is traveling on a collision course, the background image of the other vehicle OV includes a building B1 when time t is t0, but includes a building B2 when time t is t1. In such a case, the CPU determines that the background image is changing over time.

[0036] If the result of each of steps S430 to S450 is "Yes" and the background image is changing over time, it can be assumed that the collision course phenomenon is occurring. In other words, it can be determined that the target vehicle is another vehicle on the collision course. Therefore, in this case, the CPU proceeds from S460 to S470 and sets the value of the collision course flag XC to "1". The CPU then proceeds to S495, and then to S315 in FIG. 3.

[0037] If the CPU determines "No" in any of steps S430 to S460, the process proceeds from the step where it determined "No" to S420, and then to S315 in FIG.

[0038] 3, the CPU judges whether the value of the collision course flag XC is "1." If the value of the collision course flag XC is "0," the CPU proceeds directly from S315 to S395. In this case, normal collision avoidance control (control to avoid collision with a target located in the traveling direction of the host vehicle) is executed.

[0039] On the other hand, if the value of the collision course flag XC is "1", the CPU proceeds from S315 to S320, and determines, based on the camera information and radar information, whether or not another vehicle on the collision course is approaching the vehicle (more precisely, the point where the traveling direction of the vehicle and the traveling direction of the other vehicle on the collision course intersect) from the driver's side (the right side in the case of a right-hand drive vehicle). The result of the determination as to whether the other vehicle on the collision course is approaching the host vehicle from the driver's seat side or the passenger's seat side is also referred to as an approach direction determination result.

[0040] For example, if the vehicle is a right-hand drive vehicle, the distance between the driver's seat and the right A-pillar, which is a vehicle structure that blocks the driver's view, is shorter than the distance between the driver's seat and the left A-pillar, which is a vehicle structure that blocks the driver's view. Therefore, the driver's view to the right diagonally forward is blocked over a relatively wide area compared to the view to the left diagonally forward. For this reason, when another vehicle on the collision course is approaching from the driver's seat side, it is more likely that the driver will not be able to see (not notice) the other vehicle on the collision course compared to when the other vehicle on the collision course is approaching from the passenger seat side. This is also true when the vehicle is a left-hand drive vehicle.

[0041] Therefore, if another vehicle on the collision course is approaching from the driver's seat side, the CPU proceeds from S320 to S325 and sets the collision time threshold TTCth, which will be described later, to "a value obtained by adding a positive predetermined value A to the standard threshold Tn." This relatively speeds up the timing at which the collision avoidance support operation, which will be described later, is executed. The CPU then proceeds to S335.

[0042] On the other hand, if the other vehicle on the collision course is approaching from the passenger side, the CPU proceeds from S320 to S330, and sets the collision time threshold TTCth to the "standard threshold Tn." After that, the CPU proceeds to S335.

[0043] When the CPU proceeds to S335, it determines whether or not the driver is visually recognizing another vehicle on the collision course (there is a high probability that the driver has visually recognized the other vehicle), and sets the value of the visual recognition flag XW based on the result (visual recognition determination result). The value of the visual recognition flag XW is set to "0" in the initialization routine described above. When the value of the visual recognition flag XW is "1", it indicates that the driver is visually recognizing another vehicle on the collision course (there is a high probability that the driver has visually recognized the other vehicle). Therefore, the visual recognition flag XW indicates the determination result (visual recognition determination result) as to whether or not there is a high probability that the driver of the vehicle is visually recognizing another vehicle on the collision course.

[0044] More specifically, when the CPU proceeds to S335, it starts processing the visibility determination subroutine shown in FIG. 5 from S500, proceeds to S505, and determines whether the current time is immediately after "the point at which the value of the collision course flag XC changes from '0' to '1' (hereinafter also referred to as the 'start point of the collision course phenomenon')."

[0045] If the current time is immediately after the start of the collision course phenomenon, the CPU proceeds from S505 to S510 and sets (resets) the value of the timer Timer to "0." The timer Timer is a timer that measures the accumulated time during which the driver is presumed to be visually recognizing another vehicle on the collision course. Next, the CPU proceeds to S515 and sets the value of the visual recognition flag XW to "0," and then proceeds to S520. On the other hand, if the current time is not immediately after the start of the collision course phenomenon, the CPU proceeds directly from S505 to S520.

[0046] In S520, the CPU acquires the positions (actually, the directions) of other vehicles on the collision course relative to the own vehicle based on the camera information and radar information.

[0047] Next, the CPU acquires the longitudinal line of sight direction and the vertical line of sight direction from the driver monitoring device 40 in S525.

[0048] Next, the CPU proceeds to S530, where it determines whether or not the other vehicle on the collision course is located within the line of sight range of the driver of the host vehicle (that is, whether or not the driver is in a state where he or she can visually see the other vehicle on the collision course).

[0049] More specifically, when the following condition 1 and condition 2 are both satisfied, the CPU determines that the other vehicle on the collision course is located within the line of sight of the driver of the host vehicle.

[0050] (Condition 1) The vertical line of sight of the driver Dr of the vehicle is within a first angle range AR1 when the driver Dr is looking outside the vehicle (see FIG. 6A). This first angle range is a range that is above an angle D1 downward from the horizontal direction HL and below an angle D2 upward from the horizontal direction HL.

[0051] (Condition 2) When the "angle (left-right angle) of the line of sight of the driver Dr of the vehicle HV with respect to the front FD of the vehicle HV" is angle θ3, the other vehicle is located on the collision course within a second angle range AR2 (see FIG. 6B) in which the angle from the front FD of the vehicle HV to the left or right is from angle "θ3-β1" to angle "θ3+β1". β1 is, for example, 15°.

[0052] If another vehicle on the collision course is located within the line of sight of the driver of the vehicle, the CPU proceeds from S530 to S535 and determines whether or not there is a "vehicle structure (obstruction) of the vehicle" that blocks the driver's view within the line of sight of the driver of the vehicle (the above-mentioned second angle range AR2). A typical example of such a vehicle structure of the vehicle is the A-pillar (see A-pillar BS shown in FIG. 6B).

[0053] However, even if another vehicle is located on the collision course within the line of sight direction range (second angle range AR2) of the driver of the vehicle, if a vehicle structure of the vehicle is located within that line of sight direction range, the driver of the vehicle cannot see the other vehicle on the collision course.

[0054] In other words, if the result of S530 is "Yes" and there is no "vehicle structure of the own vehicle" that blocks the driver's view within the line of sight direction range (second angle range AR2) of the own vehicle, it can be estimated that the driver is looking at another vehicle on the collision course. Therefore, in this case, the CPU proceeds from S535 to S540 and increases the value of the timer Timer by a predetermined time (calculation period) dt. As is clear from the above, if the driver of the own vehicle continues to look in a direction other than the other vehicle on the collision course, the value of the timer Timer does not increase. In contrast, if the driver continues to look at the other vehicle on the collision course or looks at it intermittently, the value of the timer Timer gradually increases. Therefore, if the value of the timer Timer is equal to or greater than the visual recognition determination time threshold Tth, it can be estimated that the driver of the own vehicle is visually recognizing (visually recognizing) the other vehicle on the collision course.

[0055] Therefore, the CPU proceeds from S540 to S545 and determines whether the value of the timer Timer is equal to or greater than the visual recognition determination time threshold Tth. If the value of the timer Timer is equal to or greater than the visual recognition determination time threshold Tth, the CPU proceeds from S545 to S550 and sets the value of the visual recognition flag XW to "1." The CPU then proceeds to S595 and then to S340 in FIG. 3.

[0056] If the CPU judges "No" in any of steps S530, S535, and S545, it proceeds directly from the step where it judged "No" to S595, and then proceeds to S340 in Fig. 3. In this way, if there is a high probability that the driver of the host vehicle has visually recognized (visually recognized) another vehicle on the collision course, the value of the visual recognition flag XW is set to "1", and if not, the value of the visual recognition flag XW is set to "0".

[0057] When the CPU proceeds to S340, it determines whether the value of the viewing flag XW is "1". If the value of the viewing flag XW is "1", the CPU proceeds from S340 to S345, where it reduces the collision time threshold TTCth by a positive predetermined value B. This relatively delays the timing at which the collision avoidance assistance operation is performed. The CPU then proceeds to S350. On the other hand, if the value of the viewing flag XW is not "1", the CPU proceeds directly from S340 to S350.

[0058] In S350, the CPU determines whether or not the driver of the host vehicle is performing a collision avoidance driving operation. This determination result in S350 is also referred to as a driving operation determination result. More specifically, the CPU determines that the driver of the host vehicle is performing a collision avoidance driving operation when the signal from the brake switch 74 is an on signal. Note that the CPU may determine that the driver of the host vehicle is performing a collision avoidance driving operation in any of the following cases (when the driver of the host vehicle is performing a deceleration operation to decelerate the host vehicle). When the signal from the accelerator switch 72 is an OFF signal. - The accelerator pedal operation amount AP decreases over time. - When the brake pedal operation amount BP increases over time.

[0059] If the driver of the host vehicle is performing a collision avoidance driving maneuver, the CPU proceeds from S350 to S355, where it reduces the collision time threshold TTCth by a positive predetermined value C. This relatively delays the timing at which the collision avoidance assistance operation is performed. The CPU then proceeds to S360. In contrast, if the driver of the host vehicle is not performing a collision avoidance driving maneuver, the CPU proceeds directly from S350 to S360.

[0060] In S360, the CPU determines whether a predetermined execution condition for executing a collision avoidance support operation for avoiding a collision with another vehicle on the collision course is satisfied. More specifically, in S360, the CPU determines whether a time to collision (TTC) is equal to or less than a collision time threshold TTCth. The time to collision (TTC) is obtained by dividing a distance DP between the host vehicle and a point P where the host vehicle and the other vehicle on the collision course intersect with each other by a vehicle speed Vh of the host vehicle (see FIG. 2).

[0061] If the time to collision TTC is equal to or less than the collision time threshold TTCth, the execution condition is met. In this case, the CPU proceeds from S360 to S365 and executes the collision avoidance support operation (collision avoidance control / collision damage mitigation control). More specifically, the CPU transmits an instruction signal to the brake ECU 50 to operate the brake actuator 51, thereby applying a braking force to the host vehicle so that the host vehicle stops before a point P where the host vehicle intersects with another vehicle on the collision course, thereby decelerating the host vehicle (executing automatic braking). Furthermore, the CPU transmits an instruction signal to the alarm ECU 60 to cause the alarm display device 61 to display an alarm and the alarm sound generation device 62 to generate an alarm sound.

[0062] On the other hand, if the time to collision TTC is greater than the collision time threshold TTCth, the CPU proceeds directly from S360 to S395 and ends this routine for the time being.

[0063] As described above, according to an embodiment of the present invention, the execution conditions (TTCth) of the collision avoidance support operation are changed based on the approach direction judgment result, the visual recognition judgment result, and the driving operation judgment result, so that the collision avoidance support operation can be started at an appropriate timing.

[0064] The present invention is not limited to the above embodiment and modified examples, and various modified examples can be adopted within the scope of the present invention. For example, the above device DS may change the execution conditions of the collision avoidance support operation based on at least one or any two of the approach direction determination result, the visual recognition determination result, and the driving operation determination result. That is, any one or any two of the process groups S320 to S330 in FIG. 3, the process group S335 to S345 in FIG. 3, and the process groups S350 and S355 in FIG. 3 can be omitted. In this case, the default value of the collision time threshold TTCth is set to the standard threshold Tn.

[0065] Furthermore, the collision initiation assistance operation may not include automatic braking, and may be only "warning and alarm sound", or only a warning. Alternatively, only "warning and alarm sound" may be executed when the time to collision TTC becomes equal to or less than a first collision time threshold TTCth1, and "automatic braking" may be executed when the time to collision TTC becomes equal to or less than a second collision time threshold TTCth2 that is smaller than the first collision time threshold TTCth1. In this case, each of the first collision time threshold TTCth1 and the second collision time threshold TTCth2 may be changed as described above based on at least one or any two of the approach direction determination result, the visual confirmation determination result, and the driving operation determination result.

[0066] Further, for example, the present invention is applicable to an autonomous vehicle in which the driving mode has transitioned from autonomous driving to driving by a driver. [Explanation of symbols]

[0067] 10...driving assistance ECU, 20...front camera device, 30...radar device, 40...driver monitoring device, 50...brake ECU, 60...alarm ECU.

Claims

1. A driving assistance device for a vehicle, comprising: a controller that acquires other vehicle information, which is information about the position of another vehicle located in a diagonally forward area of ​​the host vehicle relative to the host vehicle; when it is determined based on the other vehicle information that there is another vehicle on a collision course that is traveling in a manner that causes a collision course phenomenon with the host vehicle, it determines whether or not an execution condition for executing a collision avoidance assistance operation for avoiding a collision between the host vehicle and the other vehicle on the collision course is satisfied; and when it is determined that the execution condition is satisfied, it starts execution of the collision avoidance assistance operation. The controller: an approach direction determination result as to whether the other vehicle on the collision course is approaching from the direction of the driver's seat side of the host vehicle or from the direction of the passenger's seat side of the host vehicle; And, a visual recognition determination result as to whether or not there is a high probability that the driver of the vehicle visually recognizes another vehicle on the collision course; and modifying the execution condition based on at least one of the following: Driving assistance device.

2. The vehicle driving assistance device according to claim 1, The controller: The execution condition is changed based on a driving operation determination result as to whether the driver is performing a collision avoidance driving operation to avoid the collision. Driving assistance device.

3. The vehicle driving assistance device according to claim 1 or 2, The controller: The execution condition is changed based on the visual recognition determination result, Further, the controller Acquire the driver's line of sight direction; measuring a cumulative time during which another vehicle is located on the collision course within a line-of-sight direction range that is determined based on the line-of-sight direction and a vehicle structure of the host vehicle is not located within the line-of-sight direction range; When the cumulative time is equal to or greater than a predetermined threshold, it is determined that the probability that the driver of the host vehicle has visually recognized another vehicle on the collision course is high, and when the cumulative time is less than the predetermined threshold, it is determined that the probability that the driver of the host vehicle has visually recognized another vehicle on the collision course is low. The visual recognition determination result is obtained by Driving assistance device.

4. The vehicle driving assistance device according to claim 1, The controller: The execution condition is changed based on the approach direction determination result and the visibility determination result, Further, the controller changing the execution condition so that a timing for starting execution of the collision avoidance support operation is earlier when the other vehicle on the collision course approaches from the direction of the driver's seat side than when the other vehicle on the collision course approaches from the direction of the passenger's seat side; changing the execution condition so that a timing for starting execution of the collision avoidance support operation is earlier when the probability that the driver visually recognizes another vehicle on the collision course is low, compared with a case where the probability that the driver visually recognizes another vehicle on the collision course is high; It was configured as follows: Driving assistance device.

5. acquiring other vehicle information which is information regarding a position of another vehicle located in a diagonally forward area of ​​the host vehicle relative to the host vehicle; a step of determining whether or not an execution condition for executing a collision avoidance assistance operation for avoiding a collision between the host vehicle and the other vehicle on the collision course is established when it is determined based on the other vehicle information that there is a other vehicle on the collision course that is traveling in a manner that causes a collision course phenomenon with the host vehicle; starting execution of the collision avoidance assist operation when it is determined that the execution condition is satisfied; A vehicle driving assistance method comprising: An approach direction determination result as to whether the other vehicle on the collision course is approaching from the direction of the driver's seat side of the host vehicle or from the direction of the passenger's seat side of the host vehicle, and a visual recognition determination result as to whether or not there is a high probability that the driver of the vehicle visually recognizes another vehicle on the collision course; modifying the execution condition based on at least one of A driving assistance method comprising:

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