Vehicle Driving Assistance Device

Abstract

To provide a vehicle operation support device capable of executing appropriate traffic lane deviation prevention control taking into consideration a risk that an own vehicle deviates from a traffic lane.SOLUTION: When a pre-intervention in-phase condition that steering operation force equal to or more than a predetermined value, in a direction to return an own vehicle 100 deviating from a traffic lane to the traffic lane is input into the own vehicle by a driver when a straight lane deviation condition or an inner curved lane deviation condition is met while the own vehicle is traveling on a straight road is not met, a vehicle operation support device 10 sets target steering force by setting steering force at a reference value as intervention steering force. On the other hand, when the pre-intervention in-phase condition is met when the straight lane deviation condition or the inner curved lane deviation condition is met, the vehicle operation support device does not execute the traffic lane deviation prevention control or sets the target steering force by setting the steering force less than the reference value as the intervention steering force and executes the traffic lane deviation prevention control.SELECTED DRAWING: Figure 14

Description

[Technical field]

[0001] The present invention relates to a vehicle driving assistance device. [Background technology]

[0002] 2. Description of the Related Art Vehicle driving assistance devices are known that provide driving assistance such as lane departure prevention control, which autonomously steers the vehicle to prevent the vehicle from deviating from its lane, and lane keeping control, which autonomously steers the vehicle to keep the vehicle in the center of the lane.

[0003] In addition, while lane keeping control is being performed, the driver may intentionally input a steering force to the vehicle in order to cause the vehicle to deviate from the center of the lane. In this case, it is desirable to stop the lane keeping control. Therefore, a vehicle driving assistance device is also known that is configured to stop lane keeping control when a steering force equal to or greater than a predetermined cancellation threshold is input to the vehicle by the driver while lane keeping control is being performed.

[0004] Furthermore, whether it is desirable to stop the lane keeping control when the driver inputs a steering force to the vehicle varies depending on the driving conditions of the vehicle, and therefore, a vehicle driving assistance device configured to change the cancellation threshold value depending on the driving conditions of the vehicle is also known. More specifically, a vehicle driving assistance device configured to change the cancellation threshold value depending on the driving conditions of the vehicle, such as whether the road on which the vehicle is traveling is a straight road or a curved road, and whether the steering force in the left or right direction is input to the vehicle by the driver when the vehicle is traveling on a curved road, is also known.

[0005] This vehicle driving assistance device is configured to stop lane keeping control when the vehicle is traveling on a straight road and a steering force equal to or greater than a cancel threshold set to a reference value is input to the vehicle by the driver, while the vehicle is traveling on a curved road and the lane keeping control is stopped if the driver inputs to the vehicle a steering force in a direction that causes the vehicle to travel along the curved road and that is equal to or greater than the cancel threshold set to a value smaller than the reference value, and to stop lane keeping control when the driver inputs to the vehicle a steering force in a direction opposite to the direction that causes the vehicle to travel along the curved road and that is equal to or greater than the cancel threshold set to a value greater than the reference value (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. WO2020 / 230301 Summary of the Invention

[0007] As for lane departure prevention control, as described above, it is preferable to determine whether or not to execute lane departure prevention control depending on the driving conditions of the vehicle, and to change the steering force (intervention steering force) autonomously applied to the vehicle by the lane departure prevention control.

[0008] However, since lane departure prevention control is a control that prevents the vehicle from departing from its lane, it is desirable to determine whether or not to execute lane departure prevention control and to change the intervention steering force, taking into account the risk of the vehicle departing from its lane when lane departure prevention control is not executed or when the intervention steering force is changed.

[0009] An object of the present invention is to provide a vehicle driving assistance device capable of executing appropriate lane departure prevention control taking into consideration the risk of the host vehicle deviating from its lane.

[0010] The vehicle driving assistance device according to the present invention includes a control device that performs lane departure prevention control to prevent the host vehicle from departing from a lane by autonomously steering the host vehicle. During execution of the lane departure prevention control, the control device sets a target steering force based on an intervention steering force that is autonomously set as a steering force for returning the host vehicle to the lane and a driver requested steering force that is set based on a steering operation force input to the host vehicle by the driver of the host vehicle, and autonomously steers the host vehicle by applying a steering force equivalent to the target steering force to the host vehicle. do.

[0011] The control device detects a straight lane departure condition indicating that the host vehicle may depart from a lane while traveling on a straight road. The matter When the pre-intervention in-phase condition is not satisfied, the lane departure prevention control is started, a steering force of a reference value greater than zero is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed. The matter If the pre-intervention in-phase condition is satisfied when the condition is satisfied, the lane departure prevention control is not executed, or the lane departure prevention control is started, a steering force smaller than the reference value is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed. Furthermore, when an inside-of-curve lane departure condition is satisfied that there is a possibility that the host vehicle will depart from a lane on the inside of the curve while traveling on a curved road and the pre-intervention in-phase condition is not satisfied, the control device starts the lane departure prevention control, sets a steering force of a reference value greater than zero as the intervention steering force, sets the target steering force, and executes the lane departure prevention control. On the other hand, when the inside-of-curve lane departure condition is satisfied and the pre-intervention in-phase condition is satisfied, the control device does not execute the lane departure prevention control, or starts the lane departure prevention control, sets a steering force smaller than the reference value as the intervention steering force, sets the target steering force, and executes the lane departure prevention control. When a pre-intervention in-phase condition is satisfied that the host vehicle may depart from a lane from the outside of a curved road while traveling on a curved road and the pre-intervention in-phase condition is not satisfied, the control device starts the lane departure prevention control, sets the reference value of the steering force as the intervention steering force, sets the target steering force, and executes the lane departure prevention control. When a post-intervention in-phase condition is satisfied that the driver has inputted an in-phase steering operation force greater than a predetermined value to the host vehicle during an avoidance control period that is a period from when the host vehicle is returned to the lane by the lane departure prevention control after the pre-intervention in-phase condition is satisfied and the pre-intervention in-phase condition is not satisfied when the curb outside lane departure condition is satisfied and the lane departure prevention control is started, the control device sets a steering force greater than the reference value as the intervention steering force, sets the target steering force, and executes the lane departure prevention control.

[0014] If the pre-intervention in-phase condition is satisfied when the straight lane departure condition or the inside of a curve lane departure condition is satisfied, it is presumed that the driver himself is trying to return the vehicle to the lane, so the departure risk (the risk that the vehicle deviates from the lane more than is tolerable) is small even if lane departure prevention control is not executed, and even if lane departure prevention control is executed, the departure risk is also small even if the intervention steering force is small. According to the present invention, in this case, lane departure prevention control is not executed, or lane departure prevention control is executed with a steering force smaller than the reference value as the intervention steering force.

[0017] As described above, according to the present invention, appropriate lane departure prevention control can be executed while taking into account the risk of departure.

[0019] If the post-intervention in-phase condition is satisfied during the avoidance control period after the curve outside lane departure condition is satisfied and lane departure prevention control is started, it is inferred that the vehicle has deviated from the lane even though the driver himself is trying to return the vehicle to the lane, and therefore the departure risk is high. According to the present invention, in this case, lane departure prevention control is executed by setting a steering force larger than the reference value as the intervention steering force. Therefore, appropriate lane departure prevention control that takes the departure risk into consideration can be executed.

[0027] The components of the present invention are not limited to the embodiments of the present invention described below with reference to the drawings. Other objects, other features, and associated advantages of the present invention will be easily understood from the description of the embodiments of the present invention. [Brief description of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram showing a vehicle driving assistance device according to an embodiment of the present invention and a vehicle (host vehicle) on which the device is mounted. [Diagram 2] FIG. 2 is a diagram showing a scene in which a vehicle traveling on a straight road deviates from its lane on the left side. [Diagram 3] FIG. 3 is a diagram showing the left distance and the right distance. [Figure 4]FIG. 4 is a diagram showing a scene in which the vehicle traveling on a straight road deviates from the lane on the right side. [Diagram 5] FIG. 5 is a diagram showing a situation in which a vehicle traveling on a left curve deviates from its lane on the inside of the curve. [Figure 6] FIG. 6 is a diagram showing a situation in which a vehicle traveling on a left curve deviates from its lane on the outside of the curve. [Figure 7] FIG. 7 is a diagram showing a situation in which the vehicle traveling on a right curve deviates from the lane on the inside of the curve. [Figure 8] FIG. 8 is a diagram showing a situation in which the vehicle traveling on a right curve deviates from the lane on the outside of the curve. [Figure 9] FIG. 9 is a diagram showing an example of functions of the vehicle driving support device according to the embodiment of the present invention. [Figure 10] FIG. 10 is a diagram showing an example of functions of the vehicle driving support device according to the embodiment of the present invention. [Figure 11] FIG. 11 is a diagram showing an example of functions of the vehicle driving support device according to the embodiment of the present invention. [Figure 12] FIG. 12 is a diagram showing an example of functions of the vehicle driving support device according to the embodiment of the present invention. [Figure 13] FIG. 13 is a flowchart showing a routine executed by the vehicle driving assistance device according to the embodiment of the present invention. [Figure 14] FIG. 140 is a flowchart showing a routine executed by a vehicle driving assistance device according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Hereinafter, a vehicle driving support device according to an embodiment of the present invention will be described with reference to the drawings. As shown in Fig. 1, a vehicle driving support device 10 according to an embodiment of the present invention is mounted on a vehicle (host vehicle 100).

[0030] <ecu> The vehicle driving assistance device 10 includes an ECU 90 as a control device. ECU is an abbreviation for electronic control unit. The ECU 90 includes a microcomputer as a main part. The microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, an interface, and the like. The CPU is configured to realize various functions by executing instructions, programs, or routines stored in the ROM.

[0031] <Drive unit, etc.> In addition, the host vehicle 100 is equipped with a drive device 21, a braking device 22, and a steering device 23.

[0032] <Drive unit> The drive device 21 is a device that outputs a drive force (drive torque) provided to the host vehicle 100 to make the host vehicle 100 travel, and is, for example, an internal combustion engine, a motor, etc. The drive device 21 is electrically connected to the ECU 90. The ECU 90 can control the operation of the drive device 21 to control the drive force output from the drive device 21.

[0033] <Brake device> The braking device 22 is a device that outputs a braking force (braking torque) applied to the host vehicle 100 in order to brake the host vehicle 100, and is, for example, a hydraulic brake device. The braking device 22 is electrically connected to the ECU 90. The ECU 90 can control the operation of the braking device 22 to control the braking force output from the braking device 22.

[0034] <Steering system> The steering device 23 is a device that outputs a steering force (steering torque) applied to the host vehicle 100 in order to steer the host vehicle 100, and is, for example, a power steering device. The steering device 23 is electrically connected to the ECU 90. The ECU 90 can control the operation of the steering device 23 to control the steering force output from the steering device 23.

[0035] <Sensors, etc.> Furthermore, the vehicle 100 is equipped with an accelerator pedal 31, an accelerator pedal operation amount sensor 32, a brake pedal 33, a brake pedal operation amount sensor 34, a steering wheel 35, a steering shaft 36, a steering angle sensor 37, a steering torque sensor 38, a vehicle speed detection device 50 and a surrounding information detection device 60.

[0036] <Accelerator pedal operation amount sensor> The accelerator pedal operation amount sensor 32 is a sensor that detects the amount of operation of the accelerator pedal 31. The accelerator pedal operation amount sensor 32 is electrically connected to the ECU 90. The accelerator pedal operation amount sensor 32 transmits information on the detected amount of operation of the accelerator pedal 31 to the ECU 90. The ECU 90 obtains the amount of operation of the accelerator pedal 31 (accelerator pedal operation amount AP) based on that information.

[0037] The ECU 90 calculates a required driving force (required driving torque) based on the accelerator pedal operation amount AP and the traveling speed (host vehicle speed) of the host vehicle 100. The required driving force is a driving force that is required to be output from the drive device 21. The ECU 90 controls the operation of the drive device 21 so that a driving force equivalent to the required driving force is output.

[0038] <Brake pedal operation amount sensor> The brake pedal operation amount sensor 34 is a sensor that detects the operation amount of the brake pedal 33. The brake pedal operation amount sensor 34 is electrically connected to the ECU 90. The brake pedal operation amount sensor 34 transmits information on the detected operation amount of the brake pedal 33 to the ECU 90. The ECU 90 obtains the operation amount of the brake pedal 33 (brake pedal operation amount BP) based on the information.

[0039] The ECU 90 acquires a required braking force (required braking torque) by calculation based on the brake pedal operation amount BP. The required braking force is a braking force that is required to be output by the braking device 22. The ECU 90 controls the operation of the braking device 22 so that a braking force corresponding to the required braking force is output.

[0040] <Steering angle sensor> The steering angle sensor 37 is a sensor that detects the rotation angle of the steering shaft 36 with respect to the neutral position. The steering angle sensor 37 is electrically connected to the ECU 90. The steering angle sensor 37 transmits information on the detected rotation angle of the steering shaft 36 to the ECU 90. The ECU 90 acquires the rotation angle (steering angle θs) of the steering shaft 36 based on the information.

[0041] <Steering torque sensor> The steering torque sensor 38 is a sensor that detects the torque input to the vehicle 100 by the driver of the vehicle 100 (in this example, the torque input to the steering shaft 36 via the steering wheel 35). The steering torque sensor 38 is electrically connected to the ECU 90. The steering torque sensor 38 transmits information on the detected torque to the ECU 90. The ECU 90 acquires the torque input to the steering shaft 36 by the driver via the steering wheel 35 (driver steering operation force TQ_D) based on the information.

[0042] <Vehicle speed detection device> The vehicle speed detection device 50 is a device that detects the traveling speed of the host vehicle 100, and is, for example, a wheel speed sensor. The vehicle speed detection device 50 is electrically connected to the ECU 90. The vehicle speed detection device 50 transmits information on the detected traveling speed of the host vehicle 100 to the ECU 90. The ECU 90 acquires the traveling speed of the host vehicle 100 (host vehicle speed V) based on the information.

[0043] The ECU 90 calculates and obtains a driver requested steering force TQ_Dreq (requested steering torque) based on the obtained steering angle θs, driver steering operation force TQ_D, and vehicle speed V. The driver requested steering force TQ_Dreq (driver requested steering force) is a steering force that is requested to be output from the steering device 23. Except when executing lane departure prevention control described later, the ECU 90 sets the driver requested steering force TQ_Dreq as a target steering force TQtgt, and performs normal steering control that controls the operation of the steering device 23 so that a steering force equivalent to the target steering force TQtgt is output from the steering device 23.

[0044] <Peripheral information detection device> The surrounding information detection device 60 is a device that detects information about the surroundings of the vehicle 100, and in this example, includes an image sensor 61 and a radio wave sensor 62. The image sensor 61 is, for example, a camera. The radio wave sensor 62 is, for example, a radar sensor (such as a millimeter wave radar). The surrounding information detection device 60 may also include a sonic sensor such as an ultrasonic sensor (clearance sonar) or an optical sensor such as a laser radar (LiDAR).

[0045] <Image sensor> The image sensor 61 is electrically connected to the ECU 90. The image sensor 61 captures an image of the surroundings of the vehicle 100 and transmits information of the captured image to the ECU 90. The ECU 90 can obtain information (surroundings detection information IS) regarding the surroundings of the vehicle 100 based on the image information (image information II).

[0046] <Radio wave sensor> The radio wave sensor 62 is electrically connected to the ECU 90. The radio wave sensor 62 transmits radio waves and receives radio waves reflected by objects (reflected waves). The radio wave sensor 62 transmits information related to the transmitted radio waves and received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 62 detects objects present in the vicinity of the vehicle 100, and transmits information related to the detected objects to the ECU 90. The ECU 90 can acquire information (periphery detection information IS) related to objects such as structures present in the vicinity of the vehicle 100 based on the information (radio wave information).

[0047] <Overview of operation of vehicle driving assistance device> Next, an outline of the operation of the vehicle driving support device 10 will be described. When a lane departure condition is met that indicates that the host vehicle 100 may deviate from the host lane LN (the lane in which the host vehicle 100 is traveling) while the host vehicle 100 is traveling, the vehicle driving support device 10 executes lane departure prevention control to autonomously steer the host vehicle 100 to prevent the host vehicle 100 from deviating from the host lane LN as shown in Fig. 2, unless a control unnecessary condition described later is met.

[0048] The vehicle driving assistance device 10 determines that the lane departure condition is met when the host vehicle 100 reaches a left departure judgment line LL while the host vehicle 100 is traveling, and determines that the lane departure condition is met when the host vehicle 100 reaches a right departure judgment line LR. More specifically, the vehicle driving assistance device 10 determines that the lane departure condition is met when the left distance DL becomes zero while the host vehicle 100 is traveling, or determines that the lane departure condition is met when the right distance DR becomes zero.

[0049] The left departure judgment line LL is a line extending along the left edge of the own lane LN (in the example shown in FIG. 2, the left lane marking 200L), and the right departure judgment line LR is a line extending along the right edge of the own lane LN (in the example shown in FIG. 2, the right lane marking 200R). The vehicle driving assistance device 10 acquires the left lane marking 200L and the right lane marking 200R based on the surrounding detection information IS.

[0050] Also, as shown in Figure 3, the left distance DL is the distance between the left front end of the vehicle 100 and the left departure judgment line LL, and the right distance DR is the distance between the right front end of the vehicle 100 and the right departure judgment line LR.

[0051] Here, when executing lane departure prevention control, it is preferable to determine whether or not to execute lane departure prevention control depending on the driving conditions of the vehicle, such as whether the vehicle 100 is driving on a straight road or a curved road and what steering force the driver is applying to the vehicle 100, and to change the steering force (system intervention steering force) that is autonomously set as the steering force to return the vehicle 100 to the lane LN by the lane departure prevention control.

[0052] However, since lane departure prevention control is a control to prevent the vehicle 100 from departing from its own lane LN, it is desirable to determine whether or not to execute lane departure prevention control and to change the system intervening steering force, taking into consideration the risk of the vehicle 100 departing from its own lane LN when lane departure prevention control is not executed or when the system intervening steering force is changed.

[0053] Therefore, the vehicle driving support device 10 is configured to execute lane departure prevention control as follows.

[0054] In this example, three thresholds, a first threshold TQ1, a second threshold TQ2, and a third threshold TQ3, are prepared as thresholds (control unnecessary determination thresholds) related to the driver steering operation force TQ_D in order to determine whether execution of lane departure prevention control is unnecessary (i.e., whether the control unnecessary condition is satisfied). The first threshold TQ1 is set to a value greater than zero and the smallest value among the three thresholds, the second threshold TQ2 is set to a value greater than the first threshold TQ1, and the third threshold TQ3 is set to a value greater than the second threshold TQ2, i.e., the largest value among the three thresholds.

[0055] <Left-side deviation while driving on a straight road> <Before lane departure prevention control begins> As shown in FIG. 2, when the host vehicle 100 reaches the left departure judgment line LL while traveling on a straight road (i.e., when the left distance DL becomes zero), the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D (in-phase steering force) greater than or equal to a first threshold value TQ1 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) greater than or equal to a second threshold value TQ2 has been detected (whether or not it has been input to the host vehicle 100).

[0056] In other words, the vehicle driving assistance device 10 determines whether or not a "control-free condition in which the pre-intervention in-phase condition is satisfied when the straight lane departure condition is satisfied" is satisfied, and whether or not a "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the straight lane departure condition is satisfied" is satisfied.

[0057] The straight lane departure condition here is a condition that the vehicle 100 reaches the left departure judgment line LL while traveling on a straight road. The pre-intervention in-phase condition used when the straight lane departure condition is satisfied is a condition that an in-phase driver steering operation force TQ_D equal to or greater than a first threshold value TQ1 is detected (input to the vehicle 100). The pre-intervention opposite-phase condition used when the straight lane departure condition is satisfied is a condition that an opposite-phase driver steering operation force TQ_D equal to or greater than a second threshold value TQ2 is detected (input to the vehicle 100).

[0058] Also, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the direction (departure avoidance direction) that returns the host vehicle 100, which has deviated from the host lane LN, into the host lane LN, and in the scene shown in Fig. 2, it is the driver steering operation force TQ_D in the right direction (i.e., clockwise). On the other hand, the opposite-phase driver steering operation force TQ_D (opposite-phase steering operation force) is the driver steering operation force TQ_D in the direction (departure direction) that causes the host vehicle 100 to deviate from the host lane LN, and in the scene shown in Fig. 2, it is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise).

[0059] When the control unnecessary condition is satisfied, the vehicle driving assistance device 10 continues the normal steering control without executing the lane departure prevention control. As described above, the normal steering control is a control in which a required steering force is obtained by calculation based on the steering angle θs, the driver steering operation force TQ_D, and the vehicle speed V, and a steering force corresponding to the required steering force is output from the steering device 23.

[0060] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When starting lane departure prevention control, the vehicle driving assistance device 10 sets a target value of the system intervention steering force (target system intervention steering force TQ_Stgt), sets a target steering force TQtgt based on the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0061] Specifically, after starting lane departure prevention control, the vehicle driving assistance device 10 sets a reference value (reference steering force TQbase) as a target value of the system intervention steering force (target system intervention steering force TQ_Stgt) unless a large reduction condition and a small reduction condition described below are satisfied. Then, when the direction of the driver requested steering force TQ_Dreq at that time is the same as the direction of the target system intervention steering force TQ_Stgt, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and when the direction of the driver requested steering force TQ_Dreq at that time is different from the direction of the target system intervention steering force TQ_Stgt, the vehicle driving assistance device 10 sets a value obtained by subtracting the driver requested steering force TQ_Dreq from the target system intervention steering force TQ_Stgt as the target steering force TQtgt. Then, the vehicle driving assistance device 10 causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (to be applied to the host vehicle 100).

[0062] The reference steering force TQbase is the steering force that is required to be applied to the vehicle 100 in order to drive the vehicle 100 along a predetermined route and return it to the vehicle lane LN when the driver steering operation force TQ_D is zero, taking into account the steering angle θs, the vehicle speed V, the judgment line crossing angle θL, etc., and is obtained, for example, by an arithmetic formula with the steering angle θs, the vehicle speed V, the judgment line crossing angle θL, etc. as parameters, or by applying the steering angle θs, the vehicle speed V, the judgment line crossing angle θL, etc. to a lookup table (map) prepared in advance.

[0063] The judgment line crossing angle θL is the angle between the vertical center line of the host vehicle 100 (a line extending in the front-rear direction through the center in the width direction of the host vehicle 100) and the left departure judgment line LL. When the host vehicle 100 is facing toward the right departure judgment line LR, the judgment line crossing angle θL is the angle between the vertical center line of the host vehicle 100 and the right departure judgment line LR.

[0064] As described above, when there is a possibility that the vehicle 100 traveling on a straight road will deviate to the left side of the lane LN (when the straight lane departure condition is met), if the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the lane LN, it is presumed that the driver himself is operating the steering wheel 35 in an attempt to return the vehicle 100 to the lane LN. Therefore, since the departure risk (the possibility that the vehicle 100 will deviate from the lane LN more than an acceptable degree) is small, the vehicle driving assistance device 10 will not execute lane departure prevention control even if the driver's steering force TQ_D at that time is relatively small (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the first threshold value TQ1).

[0065] On the other hand, when there is a possibility that the vehicle 100 traveling on a straight road will deviate to the left of the vehicle lane LN (when the straight lane departure condition is met) and the driver operates the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the vehicle lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control. However, if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is equal to or greater than the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle lane LN, and therefore lane departure prevention control is not executed.

[0066] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0067] The vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D or an opposite-phase driver steering force TQ_D greater than a predetermined value (zero in this example) has been detected (input to the vehicle 100) during the period (avoidance control period) between the start of lane departure prevention control and the time when the left and right front wheels of the vehicle 100 are returned to the vehicle's lane LN.

[0068] In other words, the vehicle driving assistance device 10 determines whether or not "the significant reduction condition, in which the post-intervention in-phase condition is satisfied during the avoidance control period when the straight lane departure condition is satisfied and lane departure prevention control is initiated" is satisfied, and whether or not "the small reduction condition, in which the post-control inverse-phase condition is satisfied during the avoidance control period when the straight lane departure condition is satisfied and lane departure prevention control is initiated" is satisfied.

[0069] When the vehicle 100 reaches the left departure judgment line LL, the straight lane departure condition is established, and lane departure prevention control is initiated, the post-intervention in-phase condition used during the avoidance control period is the condition that an in-phase driver steering force TQ_D greater than a predetermined value (zero in this example) is detected (input to the vehicle 100).

[0070] In addition, when the vehicle 100 reaches the left departure judgment line LL, the straight lane departure condition is established, and lane departure prevention control is initiated, the reverse phase condition after the start of control that is used during the avoidance control period is the condition that a reverse phase driver steering force TQ_D that is greater than a predetermined value (zero in this example) is detected (input to the vehicle 100).

[0071] When the significant reduction condition is met, the vehicle driving assistance device 10 subtracts a predetermined value (significant reduction value dTQlarge) from the reference steering force TQbase to obtain a value (small steering force TQsmall) as a target value of the system intervention steering force (target system intervention steering force TQ_Stgt) (TQ_Stgt=TQbase-dTQsmall).The vehicle driving assistance device 10 then sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (add it to the host vehicle 100).

[0072] The steering force applied to the vehicle 100 at this time is a steering force in a direction to return the vehicle 100 to the vehicle lane LN, and in this example, the steering force has a magnitude equivalent to the reference steering force TQbase. That is, in this example, the large reduction value dTQlarge is set so that the target steering force TQtgt becomes a value equal to the reference steering force TQbase.

[0073] The significant reduction value dTQlarge is a value according to the driver steering operation force TQ_D, and in particular, the greater the driver steering operation force TQ_D, the greater the value. In this example, a lookup table (map) according to the departure risk determined by "(1) whether the driver steering operation force TQ_D is an in-phase steering force or an opposite-phase steering force, (2) whether the road on which the vehicle 100 is traveling is a straight road or a curved road, (3) if the road on which the vehicle 100 is traveling is a curved road, whether the vehicle 100 has deviated from the host lane LN from the inside of the curved road or the outside of the curved road, and (4) whether the vehicle 100 is in an avoidance control period or a return control period described later" is prepared in advance, and the significant reduction value dTQlarge is obtained by applying the driver steering operation force TQ_D to the lookup table selected according to the departure risk at that time.

[0074] On the other hand, when the small reduction condition is satisfied, the vehicle driving assistance device 10 subtracts a predetermined value (small reduction value dTQsmall) smaller than the large reduction value dTQlarge from the reference steering force TQbase (large steering force TQlarge) and sets the result as the target value of the system intervention steering force (target system intervention steering force TQ_Stgt) (TQ_Stgt=TQbase-dTQlarge). In this way, the target system intervention steering force TQ_Stgt (large steering force TQlarge) set when the opposite-phase driver steering operation force TQ_D is input to the host vehicle 100 is larger than the target system intervention steering force TQ_Stgt (small steering force TQsmall) set when the same-phase driver steering operation force TQ_D is input to the host vehicle 100 as described above. Then, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0075] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN if the driver requested steering force TQ_Dreq is smaller than the target system intervention steering force TQ_Stgt, and is a steering force in a direction to cause the host vehicle 100 to deviate from the host lane LN if the driver requested steering force TQ_Dreq is greater than the target system intervention steering force TQ_Stgt.

[0076] The small reduction value dTQsmall is also a value according to the driver steering operation force TQ_D at that time, and in particular, the larger the driver steering operation force TQ_D is, the larger the value becomes, but as described above, it is a value smaller than the large reduction value dTQlarge. Also, the small reduction value dTQsmall is obtained by applying the driver steering operation force TQ_D to a lookup table selected according to the departure risk at that time.

[0077] Also, if neither the large reduction condition nor the small reduction condition is met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0078] Thereafter, the vehicle driving assistance device 10 determines whether a driver steering force TQ_D greater than a predetermined value (zero in this example) has been detected (input to the vehicle 100) during the period (return control period) between when the left and right front wheels of the vehicle 100 return to the vehicle's lane LN due to the lane departure prevention control and when the lane departure prevention control is terminated.

[0079] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the straight lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0080] The post-intervention steering condition used during the return control period when the vehicle 100 reaches the left departure judgment line LL, the straight lane departure condition is established, and lane departure prevention control is started is a condition that a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected (input to the vehicle 100). Note that this post-intervention steering condition does not include a condition for determining whether the detected driver steering operation force TQ_D is an in-phase torque or an opposite-phase torque.

[0081] When the significant reduction condition is met, the vehicle driving assistance device 10 sets the value (small steering force TQsmall) obtained by subtracting a predetermined value (significant reduction value dTQlarge) from the reference steering force TQbase as the target value of the system intervention steering force (target system intervention steering force TQ_Stgt). Then, if the direction of the driver steering operation force TQ_D is the same as the direction of the system intervening steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervening steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervening steering force TQ_S, it sets the difference between the target system intervening steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23 (adds it to the host vehicle 100).

[0082] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0083] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0084] <Rearing to the right while driving on a straight road> <Before lane departure prevention control begins> On the other hand, as shown in FIG. 4, when the host vehicle 100 reaches the right departure judgment line LR while traveling on a straight road (i.e., when the right distance DR becomes zero), the vehicle driving assistance device 10 determines whether an in-phase driver steering force TQ_D (in-phase steering force) greater than or equal to the first threshold value TQ1 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) greater than or equal to the second threshold value TQ2 is detected.

[0085] In other words, the vehicle driving assistance device 10 determines whether or not a "control-free condition in which the pre-intervention in-phase condition is satisfied when the straight lane departure condition is satisfied" is satisfied, and whether or not a "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the straight lane departure condition is satisfied" is satisfied.

[0086] The straight lane departure condition here is a condition that the vehicle 100 reaches the right departure judgment line LR while traveling on a straight road. The pre-intervention in-phase condition used when the straight lane departure condition is satisfied is a condition that an in-phase driver steering operation force TQ_D equal to or greater than a first threshold value TQ1 is detected (input to the vehicle 100). The pre-intervention opposite-phase condition used when the straight lane departure condition is satisfied is a condition that an opposite-phase driver steering operation force TQ_D equal to or greater than a second threshold value TQ2 is detected (input to the vehicle 100).

[0087] As described above, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the direction (departure avoidance direction) that returns the host vehicle 100, which has deviated from the host lane LN, into the host lane LN, and is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise) in the scene shown in Fig. 4. The opposite-phase driver steering operation force TQ_D is the driver steering operation force TQ_D in the direction (departure direction) that causes the host vehicle 100 to deviate from the host lane LN, and is the driver steering operation force TQ_D in the right direction (i.e., clockwise) in the scene shown in Fig. 4.

[0088] When the control non-required condition is satisfied, the vehicle driving assistance device 10 continues normal steering control without executing lane departure prevention control.

[0089] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When the vehicle driving assistance device 10 starts lane departure prevention control, the vehicle driving assistance device 10 sets the base steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt, unless the large reduction condition and the small reduction condition described below are satisfied.

[0090] As described above, when there is a possibility that the vehicle 100 traveling on a straight road will deviate from the lane LN (when the straight lane departure condition is met), if the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the lane LN, it is presumed that the driver himself is operating the steering wheel 35 in an attempt to return the vehicle 100 to the lane LN. Therefore, since the risk of departure is small, the vehicle driving assistance device 10 will not execute lane departure prevention control even if the driver steering force TQ_D at that time is relatively small (i.e., if the driver steering force TQ_D at that time is greater than or equal to the first threshold value TQ1).

[0091] On the other hand, when there is a possibility that the vehicle 100 traveling on a straight road will deviate from the host lane LN (when the straight lane departure condition is met) and the driver operates the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the host lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control. However, if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is equal to or greater than the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the host lane LN, and therefore lane departure prevention control is not executed.

[0092] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0093] After the start of lane departure prevention control, the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D or an opposite-phase driver steering force TQ_D greater than a predetermined value (zero in this example) is detected during the avoidance control period.

[0094] In other words, the vehicle driving assistance device 10 determines whether or not "the significant reduction condition, in which the post-intervention in-phase condition is satisfied during the avoidance control period when the straight lane departure condition is satisfied and lane departure prevention control is initiated" is satisfied, and whether or not "the small reduction condition, in which the post-control inverse-phase condition is satisfied during the avoidance control period when the straight lane departure condition is satisfied and lane departure prevention control is initiated" is satisfied.

[0095] When the vehicle 100 reaches the right departure judgment line LR, the straight lane departure condition is established, and lane departure prevention control is initiated, the post-intervention in-phase condition used during the avoidance control period is the condition that an in-phase driver steering force TQ_D greater than a predetermined value (zero in this example) is detected.

[0096] In addition, when the vehicle 100 reaches the right departure judgment line LR, the straight lane departure condition is established, and lane departure prevention control is initiated, the reverse phase condition after the start of control that is used during the avoidance control period is the condition that a reverse phase driver steering force TQ_D that is greater than a predetermined value (zero in this example) is detected.

[0097] When the significant reduction condition is met, the vehicle driving assistance device 10 subtracts a predetermined value (significant reduction value dTQlarge) from the reference steering force TQbase to obtain a value (small steering force TQsmall) as a target value of the system intervention steering force (target system intervention steering force TQ_Stgt).The vehicle driving assistance device 10 then sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0098] At this time, the steering force applied to the vehicle 100 is a steering force in a direction to return the vehicle 100 to the vehicle lane LN, and in this example, the steering force has a magnitude equivalent to the reference steering force TQbase. That is, in this example, the large reduction value dTQlarge is set so that the target steering force TQtgt becomes a value equal to the reference steering force TQbase.

[0099] On the other hand, when the small reduction condition is satisfied, the vehicle driving assistance device 10 subtracts a predetermined value (small reduction value dTQsmall) smaller than the large reduction value dTQlarge from the reference steering force TQbase (large steering force TQlarge) and sets the result as the target value of the system intervention steering force (target system intervention steering force TQ_Stgt). Therefore, the target system intervention steering force TQ_Stgt (large steering force TQlarge) set when the driver steering operation force TQ_D of the opposite phase is input to the vehicle 100 is larger than the target system intervention steering force TQ_Stgt (small steering force TQsmall) set when the driver steering operation force TQ_D of the same phase is input to the vehicle 100 as described above. Then, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt (apply it to the host vehicle 100).

[0100] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN if the driver requested steering force TQ_Dreq is smaller than the target system intervention steering force TQ_Stgt, and is a steering force in a direction to cause the host vehicle 100 to deviate from the host lane LN if the driver requested steering force TQ_Dreq is greater than the target system intervention steering force TQ_Stgt.

[0101] Also, if neither the large reduction condition nor the small reduction condition is met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0102] Thereafter, the vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the return control period.

[0103] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the straight lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0104] The post-intervention steering condition used during the return control period when the vehicle 100 reaches the right departure judgment line LR, the straight lane departure condition is established, and lane departure prevention control is started is a condition that a driver steering operation force TQ_D larger than a predetermined value (zero in this example) is detected. Note that this post-intervention steering condition does not include a condition for determining whether the detected driver steering operation force TQ_D is an in-phase torque or an opposite-phase torque.

[0105] When the significant reduction condition is met, the vehicle driving assistance device 10 sets the value (small steering force TQsmall) obtained by subtracting a predetermined value (significant reduction value dTQlarge) from the reference steering force TQbase as the target value of the system intervention steering force (target system intervention steering force TQ_Stgt). Then, if the direction of the driver steering operation force TQ_D is the same as the direction of the system intervening steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervening steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervening steering force TQ_S, it sets the difference between the target system intervening steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23 (adds it to the host vehicle 100).

[0106] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0107] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0108] As described above, when the vehicle 100 is traveling on a straight road and the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the own lane LN while the vehicle 100 is being returned to the own lane LN by lane departure prevention control (during the avoidance control period), it is presumed that the driver himself is operating the steering wheel 35 in an attempt to return the vehicle 100 to the own lane LN, so even if the system intervening steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0109] On the other hand, when the vehicle 100 is traveling on a straight road and the driver operates the steering wheel 35 in a direction that causes the vehicle 100 to deviate from the host lane LN while the vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is difficult to imagine that the driver is intentionally attempting to cause the vehicle 100 to deviate from the host lane LN. Therefore, if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering force TQ_D, the risk of deviation is high, so the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0110] Furthermore, when the vehicle 100 is traveling on a straight road and the driver operates the steering wheel 35 after the vehicle 100 has been returned to the own lane LN by lane departure prevention control (during the return control period), it is presumed that the driver is attempting to drive the vehicle 100 within the own lane LN, regardless of whether the steering wheel 35 is operated to the left or right. Therefore, even if the system intervening steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and further, significantly reducing the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0111] <Deviating to the inside while driving on a left curve> <Before lane departure prevention control begins> Also, as shown in FIG. 5, when the host vehicle 100 reaches the left departure judgment line LL (curve inside departure judgment line) while traveling on a left curve road, the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D (in-phase steering force) greater than or equal to a first threshold value TQ1 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) greater than or equal to a second threshold value TQ2 is detected.

[0112] In other words, the vehicle driving assistance device 10 determines whether or not the "control-free condition in which the pre-intervention in-phase condition is satisfied when the lane departure condition on the inside of a curve is satisfied" is satisfied, and whether or not the "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the lane departure condition on the inside of a curve is satisfied" is satisfied.

[0113] The inside lane departure condition here is a condition that the vehicle 100 reaches a left departure judgment line LL (inside lane departure judgment line) while traveling on a left curve road. The pre-intervention in-phase condition and the pre-intervention out-of-phase condition used when the vehicle 100 reaches the left departure judgment line LL and the inside lane departure condition is satisfied are the same as the pre-intervention in-phase condition and the pre-intervention out-of-phase condition used when the straight lane departure condition is satisfied, respectively, but may be different conditions by using different values ​​as the predetermined values ​​used to judge whether the conditions are satisfied or not.

[0114] In the scene shown in Figure 5, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the right direction (i.e., clockwise), and the in-phase driver steering operation force TQ_D (inverse phase steering operation force) is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise).

[0115] When the control non-required condition is satisfied, the vehicle driving assistance device 10 continues normal steering control without executing lane departure prevention control.

[0116] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When the vehicle driving assistance device 10 starts lane departure prevention control, the vehicle driving assistance device 10 sets the base steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt, unless the large reduction condition and the small reduction condition described below are satisfied.

[0117] As described above, when there is a possibility that the vehicle 100 traveling on a left curve will deviate from the left side of the vehicle lane LN (when the lane departure condition on the inside of the curve is met), if the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the vehicle lane LN, it is presumed that the driver is operating the steering wheel 35 in an attempt to return the vehicle 100 to the vehicle lane LN. Therefore, since the risk of departure is small, the vehicle driving assistance device 10 will not execute lane departure prevention control even if the driver's steering force TQ_D at that time is relatively small (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the first threshold value TQ1).

[0118] On the other hand, when there is a possibility that the vehicle 100 traveling on a left curve will deviate from the left side of the vehicle's lane LN (when the lane departure condition on the inside of the curve is met) and the driver is operating the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the vehicle's lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle's lane LN, and therefore does not execute lane departure prevention control.

[0119] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0120] After the start of lane departure prevention control, the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D greater than a predetermined value (in this example, zero) or an out-of-phase driver steering force TQ_D greater than a predetermined value (in this example, zero) is detected during the avoidance control period.

[0121] In other words, the vehicle driving assistance device 10 determines whether or not "the significant reduction condition, that is, the post-intervention in-phase condition is satisfied during the avoidance control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is initiated" is satisfied, and whether or not "the small reduction condition, that is, the post-intervention out-of-phase condition is satisfied during the avoidance control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is initiated" is satisfied.

[0122] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. Then, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0123] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN, and in this example, the steering force has a magnitude equivalent to the reference steering force TQbase.

[0124] On the other hand, when the small reduction condition is satisfied, the vehicle driving support device 10 sets the large steering force TQlarge as the target system intervention steering force TQ_Stgt. Then, the vehicle driving support device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0125] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN if the driver requested steering force TQ_Dreq is smaller than the target system intervention steering force TQ_Stgt, and is a steering force in a direction to cause the host vehicle 100 to deviate from the host lane LN if the driver requested steering force TQ_Dreq is greater than the target system intervention steering force TQ_Stgt.

[0126] Also, if neither the large reduction condition nor the small reduction condition is met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0127] Thereafter, the vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the return control period.

[0128] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is started" is satisfied.

[0129] The post-intervention steering condition used during the return control period when the inside of a curve lane departure condition is met and lane departure prevention control is initiated is the same as the post-intervention steering condition used during the return control period when the straight lane departure condition is met and lane departure prevention control is initiated, but may be a different condition, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0130] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0131] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0132] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0133] As described above, when the vehicle 100 is traveling on a left curve and deviates from the vehicle's lane LN from the inside of the curve, and the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the vehicle's lane LN while the vehicle 100 is being returned to the lane LN by lane departure prevention control (during the avoidance control period), it is presumed that the driver is operating the steering wheel 35 in an attempt to return the vehicle 100 to the lane LN. Therefore, even if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0134] On the other hand, if the vehicle 100 is traveling on a left curve and deviates from the vehicle's lane LN from the inside of the curve, and the driver operates the steering wheel 35 in a direction that causes the vehicle 100 to deviate from the vehicle's lane LN while the vehicle 100 is being returned to the lane LN by lane departure prevention control (during the avoidance control period), it is difficult to imagine that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle's lane LN. Therefore, if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering force TQ_D, the risk of deviation is high, so the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0135] Furthermore, in a situation where the vehicle 100 is traveling on a left curve and deviates from the vehicle's lane LN from the inside of the curve, and the driver operates the steering wheel 35 after the vehicle 100 is returned to the vehicle's lane LN by lane departure prevention control (during the return control period), it is presumed that the driver is attempting to make the vehicle 100 travel within the vehicle's lane LN, regardless of whether the steering wheel 35 is operated to the left or to the right. Therefore, even if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0136] <Outside deviation while driving on a left curve> <Before lane departure prevention control begins> On the other hand, as shown in FIG. 6, when the host vehicle 100 reaches the right departure judgment line LR (curve outside departure judgment line) while traveling on a left curve road, the vehicle driving assistance device 10 determines whether an in-phase driver steering force TQ_D (in-phase steering force) greater than or equal to the third threshold value TQ3 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) greater than or equal to the second threshold value TQ2 is detected.

[0137] In other words, the vehicle driving assistance device 10 determines whether or not the "control-free condition in which the pre-intervention in-phase condition is satisfied when the curve outside lane departure condition is satisfied" is satisfied, and whether or not the "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the curve outside lane departure condition is satisfied" is satisfied.

[0138] The curve outside lane departure condition here is a condition that the vehicle 100 reaches the right departure judgment line LR (curve outside departure judgment line) while traveling on a left curve road. The pre-intervention in-phase condition used when the vehicle 100 reaches the right departure judgment line LR and the curve outside lane departure condition is satisfied is different from the pre-intervention in-phase condition used when the straight lane departure condition or the curve inside lane departure condition is satisfied, and is a condition that an in-phase driver steering operation force TQ_D of equal to or greater than the third threshold value TQ3 is detected. The pre-intervention out-of-phase condition used when the vehicle 100 reaches the right departure judgment line LR and the curve outside lane departure condition is satisfied is different from the pre-intervention out-of-phase condition used when the straight lane departure condition or the curve inside lane departure condition is satisfied, and is a condition that an out-of-phase driver steering operation force TQ_D of equal to or greater than the second threshold value TQ2 is detected.

[0139] In the scene shown in Figure 6, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise), and the opposite-phase driver steering operation force TQ_D (opposite-phase steering operation force) is the driver steering operation force TQ_D in the right direction (i.e., clockwise).

[0140] When the control non-required condition is satisfied, the vehicle driving assistance device 10 continues normal steering control without executing lane departure prevention control.

[0141] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When the vehicle driving assistance device 10 starts lane departure prevention control, the vehicle driving assistance device 10 sets the base steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt, unless the large reduction condition and the small reduction condition described below are satisfied.

[0142] As described above, when there is a possibility that the host vehicle 100 traveling on a left curved road will deviate from the right side of the host lane LN (when the curve outside lane departure condition is met), if the driver operates the steering wheel 35 in a direction to return the host vehicle 100 to the host lane LN, it is presumed that the driver is operating the steering wheel 35 in an attempt to return the host vehicle 100 to the host lane LN, but the amount of operation of the steering wheel 35 is insufficient and the host vehicle 100 has deviated to the outside of the left curved road. Therefore, since the risk of departure is high, the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering operation force TQ_D at that time is considerably large (i.e., if the driver's steering operation force TQ_D at that time is equal to or greater than the third threshold value TQ3), it is presumed that the driver is intentionally attempting to cause the host vehicle 100 to deviate from the host lane LN, and therefore lane departure prevention control is not executed.

[0143] On the other hand, when there is a possibility that the vehicle 100 traveling on a left curve will deviate from the right side of the vehicle lane LN (when the curve's outside lane departure condition is met) and the driver is operating the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the vehicle lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle lane LN, and therefore does not execute lane departure prevention control.

[0144] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0145] The vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the avoidance control period after the start of lane departure prevention control.

[0146] In other words, the vehicle driving assistance device 10 determines whether or not the "small reduction condition, that is, the post-intervention steering condition is satisfied during the avoidance control period when the curve outside lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0147] The post-intervention steering conditions used during the avoidance control period when the vehicle 100 reaches the right departure judgment line LR, the outside lane departure condition of the curve is met, and lane departure prevention control is initiated are the same as the post-intervention steering conditions used during the avoidance control period when the straight lane departure condition or the inside lane departure condition of the curve is met, and lane departure prevention control is initiated, but different conditions may be used, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0148] When the small width reduction condition is satisfied, the vehicle driving assistance device 10 sets the large steering force TQlarge as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0149] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0150] On the other hand, if the small reduction condition is not satisfied, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0151] Thereafter, the vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the return control period.

[0152] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the curve outside lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0153] The post-intervention steering conditions used during the return control period when the vehicle 100 reaches the right departure judgment line LR, the outside lane departure condition of the curve is met, and lane departure prevention control is initiated are the same as the post-intervention steering conditions used during the return control period when the straight lane departure condition or the inside lane departure condition of the curve is met, and lane departure prevention control is initiated, but different conditions may be used, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0154] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0155] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0156] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0157] As described above, when the host vehicle 100 is traveling on a left curve and deviates from the host lane LN from the outside of the curve, if the driver operates the steering wheel 35 in a direction to return the host vehicle 100 to the host lane LN while the host vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is presumed that although the driver is operating the steering wheel 35 in an attempt to return the host vehicle 100 to the host lane LN, the amount of operation of the steering wheel 35 is insufficient and the host vehicle 100 has deviated to the outside of the left curve. Therefore, since the risk of departure is high, the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0158] On the other hand, if the vehicle 100 is traveling on a left curve and deviates from the host lane LN from the outside of the curve, and the driver operates the steering wheel 35 in a direction that causes the vehicle 100 to deviate from the host lane LN while the vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is difficult to imagine that the driver is intentionally attempting to cause the vehicle 100 to deviate from the host lane LN.Therefore, if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering force TQ_D, the risk of deviation is high, so the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0159] Furthermore, in a situation where the vehicle 100 is traveling on a left curve and deviates from the vehicle's lane LN from the outside of the curve, and the driver operates the steering wheel 35 after the vehicle 100 is returned to the vehicle's lane LN by lane departure prevention control (during the return control period), it is presumed that the driver is attempting to make the vehicle 100 travel within the vehicle's lane LN, regardless of whether the steering wheel 35 is operated to the left or to the right. Therefore, even if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0160] <Deviation to the inside while driving on a right curve> <Before lane departure prevention control begins> Also, as shown in FIG. 7, when the host vehicle 100 reaches the right departure judgment line LR (curve inside departure judgment line) while traveling on a right curve road, the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D (in-phase steering force) equal to or greater than a first threshold value TQ1 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) equal to or greater than a second threshold value TQ2 is detected.

[0161] In other words, the vehicle driving assistance device 10 determines whether or not the "control-free condition in which the pre-intervention in-phase condition is satisfied when the lane departure condition on the inside of a curve is satisfied" is satisfied, and whether or not the "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the lane departure condition on the inside of a curve is satisfied" is satisfied.

[0162] The inside lane departure condition here is a condition that the vehicle 100 reaches a right departure judgment line LR (inside lane departure judgment line) while traveling on a right curve road. The pre-intervention in-phase condition and the pre-intervention out-of-phase condition used when the vehicle 100 reaches the right departure judgment line LR and the inside lane departure condition is satisfied are the same as the pre-intervention in-phase condition and the pre-intervention out-of-phase condition used when the straight lane departure condition is satisfied, respectively, but may be different conditions by using different values ​​as the predetermined values ​​used to judge whether the conditions are satisfied or not.

[0163] In the scene shown in Figure 7, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise), and the opposite-phase driver steering operation force TQ_D (opposite-phase steering operation force) is the driver steering operation force TQ_D in the right direction (i.e., clockwise).

[0164] When the control non-required condition is satisfied, the vehicle driving assistance device 10 continues normal steering control without executing lane departure prevention control.

[0165] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When the vehicle driving assistance device 10 starts lane departure prevention control, the vehicle driving assistance device 10 sets the base steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt, unless the large reduction condition and the small reduction condition described below are satisfied.

[0166] As described above, when there is a possibility that the vehicle 100 traveling on a right curve will deviate from the right side of the vehicle lane LN (when the lane departure condition on the inside of the curve is met), if the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the vehicle lane LN, it is presumed that the driver is operating the steering wheel 35 in an attempt to return the vehicle 100 to the vehicle lane LN. Therefore, since the risk of departure is small, the vehicle driving assistance device 10 will not execute lane departure prevention control even if the driver's steering force TQ_D at that time is relatively small (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the first threshold value TQ1).

[0167] On the other hand, when there is a possibility that the vehicle 100 traveling on a right curve will deviate from the right side of the vehicle lane LN (when the lane departure condition on the inside of the curve is met) and the driver operates the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the vehicle lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle lane LN, and therefore does not execute lane departure prevention control.

[0168] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0169] After the start of lane departure prevention control, the vehicle driving assistance device 10 determines whether or not an in-phase driver steering force TQ_D greater than a predetermined value (in this example, zero) or an out-of-phase driver steering force TQ_D greater than a predetermined value (in this example, zero) is detected during the avoidance control period.

[0170] In other words, the vehicle driving assistance device 10 determines whether or not "the significant reduction condition, that is, the post-intervention in-phase condition is satisfied during the avoidance control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is initiated" is satisfied, and whether or not "the small reduction condition, that is, the post-intervention out-of-phase condition is satisfied during the avoidance control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is initiated" is satisfied.

[0171] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. Then, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0172] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN, and in this example, the steering force has a magnitude equivalent to the reference steering force TQbase.

[0173] On the other hand, when the small reduction condition is satisfied, the vehicle driving support device 10 sets the large steering force TQlarge as the target system intervention steering force TQ_Stgt. Then, the vehicle driving support device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0174] At this time, the steering force applied to the host vehicle 100 is a steering force in a direction to return the host vehicle 100 to the host lane LN if the driver requested steering force TQ_Dreq is smaller than the target system intervention steering force TQ_Stgt, and is a steering force in a direction to cause the host vehicle 100 to deviate from the host lane LN if the driver requested steering force TQ_Dreq is greater than the target system intervention steering force TQ_Stgt.

[0175] Also, if neither the large reduction condition nor the small reduction condition is met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0176] Thereafter, the vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the return control period.

[0177] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the lane departure condition on the inside of the curve is satisfied and lane departure prevention control is started" is satisfied.

[0178] The post-intervention steering condition used during the return control period when the inside of a curve lane departure condition is met and lane departure prevention control is initiated is the same as the post-intervention steering condition used during the return control period when the straight lane departure condition is met and lane departure prevention control is initiated, but may be a different condition, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0179] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0180] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0181] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0182] As described above, when the vehicle 100 is traveling on a right curve and deviates from the vehicle's lane LN from the inside of the curve, if the driver operates the steering wheel 35 in a direction to return the vehicle 100 to the vehicle's lane LN while the vehicle 100 is being returned to the lane LN by lane departure prevention control (during the avoidance control period), it is presumed that the driver is operating the steering wheel 35 in an attempt to return the vehicle 100 to the lane LN, so even if the system intervening steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervening steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0183] On the other hand, if the vehicle 100 is traveling on a right curve and deviates from the host lane LN from the inside of the curve, and the driver operates the steering wheel 35 in a direction that causes the vehicle 100 to deviate from the host lane LN while the vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is difficult to imagine that the driver is intentionally attempting to cause the vehicle 100 to deviate from the host lane LN.Therefore, if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering force TQ_D, the risk of deviation is high, so the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0184] Furthermore, in a situation where the vehicle 100 is traveling on a right-curve road and deviates from the vehicle's lane LN from the inside of the curve, and the driver operates the steering wheel 35 after the vehicle 100 is returned to the vehicle's lane LN by lane departure prevention control (during the return control period), it is presumed that the driver is attempting to make the vehicle 100 travel within the vehicle's lane LN, regardless of whether the steering wheel 35 is operated to the left or to the right. Therefore, even if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0185] <Outside deviation while driving on a right curve> <Before lane departure prevention control begins> On the other hand, as shown in FIG. 8, when the host vehicle 100 reaches the left departure judgment line LL (curve outside departure judgment line) while traveling on a right curve road, the vehicle driving assistance device 10 determines whether an in-phase driver steering force TQ_D (in-phase steering force) greater than or equal to the third threshold value TQ3 or an opposite-phase driver steering force TQ_D (opposite-phase steering force) greater than or equal to the second threshold value TQ2 is detected.

[0186] In other words, the vehicle driving assistance device 10 determines whether or not the "control-free condition in which the pre-intervention in-phase condition is satisfied when the curve outside lane departure condition is satisfied" is satisfied, and whether or not the "control-free condition in which the pre-intervention out-of-phase condition is satisfied when the curve outside lane departure condition is satisfied" is satisfied.

[0187] The curve outside lane departure condition here is a condition that the vehicle 100 reaches the left departure judgment line LL (curve outside departure judgment line) while traveling on a right curve road. The pre-intervention in-phase condition used when the vehicle 100 reaches the left departure judgment line LL and the curve outside lane departure condition is satisfied is different from the pre-intervention in-phase condition used when the straight lane departure condition or the curve inside lane departure condition is satisfied, and is a condition that an in-phase driver steering operation force TQ_D of equal to or greater than the third threshold value TQ3 is detected. The pre-intervention out-of-phase condition used when the vehicle 100 reaches the left departure judgment line LL and the curve outside lane departure condition is satisfied is different from the pre-intervention out-of-phase condition used when the straight lane departure condition or the curve inside lane departure condition is satisfied, and is a condition that an out-of-phase driver steering operation force TQ_D of equal to or greater than the second threshold value TQ2 is detected.

[0188] In addition, in the scene shown in Figure 8, the in-phase driver steering operation force TQ_D (in-phase steering operation force) is the driver steering operation force TQ_D in the right direction (i.e., clockwise), and the in-phase driver steering operation force TQ_D (inverse phase steering operation force) is the driver steering operation force TQ_D in the left direction (i.e., counterclockwise).

[0189] When the control non-required condition is satisfied, the vehicle driving assistance device 10 continues normal steering control without executing lane departure prevention control.

[0190] On the other hand, when the control unnecessary condition is not satisfied, the vehicle driving assistance device 10 starts lane departure prevention control. When the vehicle driving assistance device 10 starts lane departure prevention control, the vehicle driving assistance device 10 sets the base steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt, unless the large reduction condition and the small reduction condition described below are satisfied.

[0191] As described above, when there is a possibility that the host vehicle 100 traveling on a right curve will deviate from the left side of the host lane LN (when the curve outside lane departure condition is met), if the driver operates the steering wheel 35 in a direction to return the host vehicle 100 to the host lane LN, it is presumed that the driver is operating the steering wheel 35 in an attempt to return the host vehicle 100 to the host lane LN, but the amount of operation of the steering wheel 35 is insufficient and the host vehicle 100 has deviated to the outside of the right curve. Therefore, since the risk of departure is high, the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering force TQ_D at that time is considerably large (i.e., if the driver's steering force TQ_D at that time is equal to or greater than the third threshold value TQ3), it is presumed that the driver is intentionally attempting to cause the host vehicle 100 to deviate from the host lane LN, and therefore the lane departure prevention control is not executed.

[0192] On the other hand, when there is a possibility that the vehicle 100 traveling on a right curve will deviate to the left side of the vehicle's lane LN (when the curve's outside lane departure condition is met) and the driver is operating the steering wheel 35 in a direction that will cause the vehicle 100 to deviate from the vehicle's lane LN, the risk of departure is high, so the vehicle driving assistance device 10 basically executes lane departure prevention control, and if the driver's steering force TQ_D at that time is relatively large (i.e., if the driver's steering force TQ_D at that time is greater than or equal to the second threshold value TQ2), it is presumed that the driver is intentionally attempting to cause the vehicle 100 to deviate from the vehicle's lane LN, and therefore does not execute lane departure prevention control.

[0193] <After lane departure prevention control begins> When the vehicle driving assistance device 10 starts the lane departure prevention control, it monitors the driver's steering operation force TQ_D while the lane departure prevention control is being executed.

[0194] The vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the avoidance control period after the start of lane departure prevention control.

[0195] In other words, the vehicle driving assistance device 10 determines whether or not the "small reduction condition, that is, the post-intervention steering condition is satisfied during the avoidance control period when the curve outside lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0196] The post-intervention steering conditions used during the avoidance control period when the vehicle 100 reaches the left departure judgment line LL, the outside lane departure condition of the curve is met, and lane departure prevention control is initiated are the same as the post-intervention steering conditions used during the avoidance control period when the straight lane departure condition or the inside lane departure condition of the curve is met and lane departure prevention control is initiated, but different conditions may be used, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0197] When the small width reduction condition is satisfied, the vehicle driving assistance device 10 sets the large steering force TQlarge as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0198] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0199] On the other hand, if the small reduction condition is not satisfied, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0200] Thereafter, the vehicle driving assistance device 10 determines whether or not a driver steering operation force TQ_D greater than a predetermined value (zero in this example) is detected during the return control period.

[0201] In other words, the vehicle driving assistance device 10 determines whether or not the "significant reduction condition, that is, the post-intervention steering condition is satisfied during the return control period when the curve outside lane departure condition is satisfied and lane departure prevention control is started" is satisfied.

[0202] The post-intervention steering conditions used during the return control period when the vehicle 100 reaches the left departure judgment line LL, the outside lane departure condition of the curve is met, and lane departure prevention control is initiated are the same as the post-intervention steering conditions used during the return control period when the straight lane departure condition or the inside lane departure condition of the curve is met and lane departure prevention control is initiated, but different conditions may be used, for example, by using a different value as the predetermined value used to determine whether the condition is met.

[0203] When the significant reduction condition is satisfied, the vehicle driving assistance device 10 sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. If the direction of the driver steering operation force TQ_D is the same as the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the sum of the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and if the direction of the driver steering operation force TQ_D is different from the direction of the system intervention steering force TQ_S, the vehicle driving assistance device 10 sets the difference between the target system intervention steering force TQ_Stgt and the driver requested steering force TQ_Dreq as the target steering force TQtgt, and causes the steering device 23 to output a steering force equivalent to the target steering force TQtgt.

[0204] Furthermore, when the direction of the driver steering force TQ_D is different from the direction of the system intervening steering force TQ_S, if the driver requested steering force TQ_Dreq is greater than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is the same as the direction of the driver steering force TQ_D, and if the driver requested steering force TQ_Dreq is smaller than the system intervening steering force TQ_S, the direction of the steering force applied to the host vehicle 100 is opposite to the direction of the driver steering force TQ_D.

[0205] On the other hand, if the significant reduction condition is not met, as described above, the vehicle driving assistance device 10 sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt, sets the target system intervention steering force TQ_Stgt as the target steering force TQtgt, and outputs a steering force equivalent to the target steering force TQtgt from the steering device 23.

[0206] As described above, when the host vehicle 100 is traveling on a right curve and deviates from the host lane LN from the outside of the curve, if the driver operates the steering wheel 35 in a direction to return the host vehicle 100 to the host lane LN while the host vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is presumed that although the driver is operating the steering wheel 35 in an attempt to return the host vehicle 100 to the host lane LN, the amount of operation of the steering wheel 35 is insufficient and the host vehicle 100 has deviated to the outside of the left curve. Therefore, since the risk of departure is high, the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0207] On the other hand, if the vehicle 100 is traveling on a right curve and deviates from the host lane LN from the outside of the curve, and the driver operates the steering wheel 35 in a direction that causes the vehicle 100 to deviate from the host lane LN while the vehicle 100 is being returned to the host lane LN by lane departure prevention control (during the avoidance control period), it is difficult to imagine that the driver is intentionally attempting to cause the vehicle 100 to deviate from the host lane LN.Therefore, if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering force TQ_D, the risk of deviation is high, so the vehicle driving assistance device 10 reduces the amount by which the system intervention steering force TQ_S is reduced.

[0208] Furthermore, in a situation where the vehicle 100 is traveling on a right-curve road and deviates from the vehicle's lane LN from the outside of the curve, and the driver operates the steering wheel 35 after the vehicle 100 is returned to the vehicle's lane LN by lane departure prevention control (during the return control period), it is presumed that the driver is attempting to make the vehicle 100 travel within the vehicle's lane LN, regardless of whether the steering wheel 35 is operated to the left or to the right. Therefore, even if the system intervention steering force TQ_S is significantly reduced in accordance with the driver steering operation force TQ_D, the risk of departure is small, and furthermore, significantly reducing the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D can avoid the driver feeling uncomfortable about the operation of the steering wheel 35. Therefore, the vehicle driving assistance device 10 significantly reduces the system intervention steering force TQ_S in accordance with the driver steering operation force TQ_D.

[0209] As an example, the vehicle driving assistance device 10 is configured to determine whether or not to execute lane departure prevention control as shown in FIG. 9(A), and to apply a steering force to the host vehicle 100 by the lane departure prevention control.

[0210] That is, the vehicle driving assistance device 10 recognizes (image recognition) the positional relationship between the left lane marking 200L and the vehicle 100 and the positional relationship between the right lane marking 200R and the vehicle 100 based on the image information II, and calculates (steering force calculation) the target system intervention steering force TQ_Stgt based on the result of the image recognition and the steering angle θs, etc. The vehicle driving assistance device 10 also performs departure risk judgment based on the result of the image recognition and the driver steering operation force TQ_D.

[0211] Then, the vehicle driving assistance device 10 performs a control non-execution selection to select not to execute lane departure prevention control based on the result of the departure risk assessment, or, if it is not selected not to execute lane departure prevention control, performs a steering force adjustment to adjust the target system intervention steering force TQ_Stgt by setting any one of the base steering force TQbase, the small steering force TQsmall, and the large steering force TQlarge as the target system intervention steering force TQ_Stgt based on the result of the departure risk assessment, and calculates a target control amount (control amount calculation) for the steering device 23 based on the adjusted target system intervention steering force TQ_Stgt, etc.

[0212] Then, the vehicle driving assistance device 10 performs control amount adjustment to adjust the target control amount calculated by the control amount calculation based on the result of the deviation risk judgment, and provides the adjusted target control amount to the steering device 23 to output a steering force from the steering device 23.

[0213] Alternatively, the vehicle driving assistance device 10 may be configured to determine whether or not to execute lane departure prevention control as shown in (B) of FIG. 9 or any of FIGS. 10 to 12, and to apply a steering force to the vehicle 100 through the lane departure prevention control.

[0214] In addition, a condition (alarm condition) may be prepared that is met before the straight lane departure condition, the inside lane departure condition of a curve, or the outside lane departure condition of a curve is met (i.e., before the vehicle 100 reaches the left departure judgment line LL or the right departure judgment line LR), and when the alarm condition is met, a buzzer may sound to notify the driver that there is a possibility that the vehicle 100 may depart from the lane LN.

[0215] In addition, when the control-exemption condition is met, lane departure prevention control is not not executed, but is executed, and the target system intervening steering force TQ_Stgt may be set as described above to execute lane departure prevention control.

[0216] In addition, when the host vehicle 100 is traveling on a straight road and there is a possibility that the host vehicle 100 will deviate from the host lane LN and the lane departure prevention control is started, the lane departure prevention control may be stopped when the in-phase driver steering operation force TQ_D becomes equal to or greater than the first threshold value TQ1 or when the opposite-phase driver steering operation force TQ_D becomes equal to or greater than the second threshold value TQ2 after the start of the lane departure prevention control. Similarly, when the host vehicle 100 is traveling on a curved road and there is a possibility that the host vehicle 100 will deviate from the host lane LN from the inside of the curve and the lane departure prevention control is started, the lane departure prevention control may be stopped when the in-phase driver steering operation force TQ_D becomes equal to or greater than the first threshold value TQ1 or when the opposite-phase driver steering operation force TQ_D becomes equal to or greater than the second threshold value TQ2 after the start of the lane departure prevention control. Furthermore, when the vehicle is traveling on a curved road in lane LN and there is a possibility that the vehicle will deviate from the lane LN from the outside of the curve and lane departure prevention control is initiated, the lane departure prevention control may be stopped after the start of lane departure prevention control when the in-phase driver steering force TQ_D becomes equal to or greater than a third threshold value TQ3, or when the opposite-phase driver steering force TQ_D becomes equal to or greater than a second threshold value TQ2.

[0217] <Effects> As described above, the vehicle driving assistance device 10 can execute appropriate lane departure prevention control that takes into consideration the risk of the host vehicle 100 deviating from the host lane LN.

[0218] In particular, when lane departure prevention control is being executed, if the departure risk is low and therefore the significant reduction condition is met, the system intervening steering force TQ_S is significantly reduced, making it easier for the driver to operate the steering wheel 35, whereas if the departure risk is high and the small reduction condition is met, the reduction amount of the system intervening steering force TQ_S is reduced, making it harder for the driver to operate the steering wheel 35. Therefore, appropriate lane departure prevention control can be executed in consideration of the risk of departure of the host vehicle 100 from the host lane LN.

[0219] <Specific operation of the vehicle driving support device> Next, a specific operation of the vehicle driving support device 10 will be described. The CPU of the ECU 90 of the vehicle driving support device 10 executes the routine shown in Fig. 13 at a predetermined calculation cycle. Therefore, at a predetermined timing, the CPU starts the process from step 1300 of the routine shown in Fig. 13, and proceeds to step 1305 to determine whether the value of the control execution flag X is "0". The value of the control execution flag X is set to "1" when lane departure prevention control is being executed, and is set to "0" when lane departure prevention control is not being executed.

[0220] If the CPU determines "Yes" in step 1305, it proceeds to step 1310 and determines whether or not a lane departure condition (straight lane departure condition, inside lane departure condition, or outside lane departure condition) is satisfied. If the CPU determines "Yes" in step 1310, it proceeds to step 1315 and determines whether or not a control no longer required condition is satisfied. If the CPU determines "Yes" in step 1315, it proceeds directly to step 1395 and temporarily ends the processing of this routine. In this case, lane departure prevention control is not executed.

[0221] On the other hand, if the CPU determines "No" in step 1315, the process proceeds to step 1320, where the CPU sets the value of the control execution flag X to "1." Next, the CPU proceeds to step 1395, where the process of this routine is temporarily terminated. In this case, lane departure prevention control is executed.

[0222] Moreover, if the CPU judges "No" at step 1305 or step 1310, the CPU proceeds directly to step 1395 and temporarily ends the processing of this routine.

[0223] Furthermore, the CPU executes the routine shown in Fig. 14 at a predetermined calculation cycle. Therefore, at a predetermined timing, the CPU starts the process from step 1400 of the routine shown in Fig. 14, and advances the process to step 1405, where it is determined whether the value of the control execution flag X is "1".

[0224] If the CPU judges "Yes" in step 1405, it proceeds to step 1410 and judges whether the control end condition is satisfied. The control end condition is satisfied when the host vehicle 100 is returned to the host lane LN by the lane departure prevention control and the yaw angle θy of the host vehicle 100 falls within a predetermined angle range. The yaw angle θy is the angle between the longitudinal center line of the host vehicle 100 and the center line of the host lane LN.

[0225] If the CPU judges "Yes" in step 1410, the CPU proceeds to step 1415 and judges whether or not the significant reduction condition is satisfied. If the CPU judges "Yes" in step 1415, the CPU proceeds to step 1420 and sets the small steering force TQsmall as the target system intervention steering force TQ_Stgt. Next, the CPU proceeds to step 1440 and sets (calculates) the target steering force TQtgt based on the target system intervention steering force TQ_Stgt set in step 1420 and the driver request steering force TQ_Dreq at that time. Next, the CPU proceeds to step 1445 and sends a steering command to the steering device 23 to output a steering force equivalent to the target steering force TQtgt. As a result, the steering force equivalent to the target steering force TQtgt is output from the steering device 23. Next, the CPU proceeds to step 1495 and ends the processing of this routine.

[0226] On the other hand, if the CPU judges "No" in step 1415, the process proceeds to step 1425, where it judges whether or not the small width reduction condition is satisfied. If the CPU judges "Yes" in step 1425, the process proceeds to step 1430, where it sets the large steering force TQlarge as the target system intervention steering force TQ_Stgt. Next, the CPU proceeds to step 1440, where it sets (calculates) the target steering force TQtgt based on the target system intervention steering force TQ_Stgt set in step 1430 and the driver request steering force TQ_Dreq at that time. Next, the CPU proceeds to step 1445, where it sends a steering command to the steering device 23 to output a steering force equivalent to the target steering force TQtgt. As a result, the steering force equivalent to the target steering force TQtgt is output from the steering device 23. Next, the CPU proceeds to step 1495, where it temporarily ends the processing of this routine.

[0227] On the other hand, if the CPU determines "No" in step 1425, the process proceeds to step 1435, where the CPU sets the reference steering force TQbase as the target system intervention steering force TQ_Stgt. Next, the CPU proceeds to step 1440, where the CPU sets (calculates) the target steering force TQtgt based on the target system intervention steering force TQ_Stgt set in step 1435 and the driver requested steering force TQ_Dreq at that time. Next, the CPU proceeds to step 1445, where the CPU sends a steering command to the steering device 23 to output a steering force equivalent to the target steering force TQtgt. As a result, the steering force equivalent to the target steering force TQtgt is output from the steering device 23. Next, the CPU proceeds to step 1495, where the CPU temporarily ends the process of this routine.

[0228] On the other hand, if the CPU determines "No" in step 1410, the process proceeds to step 1445, where it ends the lane departure prevention control. Next, the CPU proceeds to step 1450, where it sets the value of the control execution flag X to "0." Next, the CPU proceeds to step 1495, where it temporarily ends the process of this routine.

[0229] If the CPU determines "No" in step 1405, the CPU proceeds to step 1495 and temporarily ends the processing of this routine.

[0230] The specific operation of the vehicle driving assistance device 10 has been described above.

[0231] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0232] 10...vehicle driving assistance device, 23...steering device, 35...handle, 36...steering shaft, 37...steering angle sensor, 38...steering torque sensor, 60...peripheral information detection device, 61...image sensor, 62...radio wave sensor, 90...ECU, 100...own vehicle< / ecu>

Claims

[Claim 1] A control device is provided that performs lane departure prevention control to prevent the host vehicle from departing from a lane by autonomously steering the host vehicle, During execution of the lane departure prevention control, the control device sets a target steering force based on an intervention steering force that is autonomously set as a steering force for returning the host vehicle to the lane and a driver requested steering force that is set based on a steering operation force input to the host vehicle by a driver of the host vehicle, and autonomously steers the host vehicle by applying a steering force equivalent to the target steering force to the host vehicle. A vehicle driving assistance device, The control device includes: when a straight lane departure condition is satisfied that the host vehicle may depart from a lane while traveling on a straight road, if a pre-intervention in-phase condition is not satisfied that an in-phase steering force, which is a steering force equal to or greater than a predetermined value greater than zero and which is a steering force in a direction to return the host vehicle that has deviated from the lane back into the lane, is input to the host vehicle by a driver of the host vehicle, the pre-intervention in-phase condition being not satisfied, starting the lane departure prevention control, setting a steering force of a reference value greater than zero as the intervention steering force to set the target steering force, and executing the lane departure prevention control; When the straight lane departure condition is satisfied, if the pre-intervention in-phase condition is satisfied, the lane departure prevention control is not executed, or the lane departure prevention control is started, a steering force smaller than the reference value is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed; when an inside-of-curve lane departure condition is satisfied indicating that there is a possibility that the host vehicle will depart from the lane on the inside of the curve while traveling on a curved road, if the pre-intervention in-phase condition is not satisfied, the lane departure prevention control is started, a steering force of a reference value greater than zero is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed; When the pre-intervention in-phase condition is satisfied when the curve inside lane departure condition is satisfied, the lane departure prevention control is not executed, or the lane departure prevention control is started, a steering force smaller than the reference value is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed. In a vehicle driving assistance device, The control device includes: when a curve outside lane departure condition is satisfied indicating that there is a possibility that the host vehicle will depart from the lane from the outside of the curve road while traveling on a curve road, if the pre-intervention in-phase condition is not satisfied, the lane departure prevention control is started, the steering force of the reference value is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed; when the curve outside lane departure condition is satisfied, if a condition that the pre-intervention in-phase condition is not satisfied is satisfied and the lane departure prevention control is started, and then during an avoidance control period that is a period until the lane departure prevention control returns the host vehicle to the lane, a post-intervention in-phase condition that the in-phase steering operation force larger than a predetermined value is satisfied, a steering force larger than the reference value is set as the intervention steering force to set the target steering force, and the lane departure prevention control is executed. Vehicle driving assistance device.

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