JP7597011B2 - Driving Support Devices - Google Patents

Description

The present invention relates to a driving assistance device for vehicles such as automobiles.

In lane departure prevention control performed by a vehicle driving assistance device, the vehicle's position relative to the lane is detected, and when it is determined based on the detected vehicle position that there is a risk that the vehicle will depart from the lane, at least one of automatic steering of the steered wheels and issuance of an alarm is performed.

One type of lane departure prevention device is known that sets a virtual lane marking when the vehicle passes through a specific area without lane markings, such as an intersection, and issues an alarm if it is determined that the vehicle is at risk of crossing the virtual marking and deviating from the lane. For example, this type of lane departure prevention device is described in Patent Document 1 below, and this type of lane departure prevention device can reduce the risk of the vehicle deviating from the lane when passing through a specific area.

International Publication No. 2011-064825

[Problem to be solved by the invention]
However, in certain areas, such as intersections, other vehicles may be stopped and waiting to turn right or left, and drivers may intentionally cross the imaginary lane markings to avoid a collision with the other vehicles.

Conventional lane departure prevention devices, such as the one described in Patent Document 1, automatically steer the wheels and issue a warning even in the above-mentioned situations, which inevitably annoys the driver.

Conversely, in a situation where the driver's level of alertness is low, such as when the driver is fatigued from driving for a long period of time, it is preferable to automatically steer the steered wheels or issue an alarm if there is a risk that the vehicle will cross the imaginary dividing line and deviate from the lane when passing through a specific area.

The main objective of the present invention is to provide a driving assistance device that can reduce the risk of a vehicle unintentionally departing from its lane when passing through a specific area, and that reduces the risk of the driver feeling annoyed when the vehicle intentionally deviates from its lane.

[Means for solving the problems and effects of the invention]
According to the present invention, there is provided a driving assistance device (100) including a control unit (driving assistance ECU 10) that executes lane departure prevention control of at least one of automatic steering of steered wheels (24) and issuance of an alarm when it is determined that there is a risk that a vehicle (50) will deviate from the lane by crossing a dividing line of a lane (54).

The control unit is configured to set standard virtual dividing lines (76L, 76R) (S50) when it is determined that there are no other vehicles (84, 86) that would be an obstacle when the vehicle passes through a specific area (intersection 70) without lane markings (S40), and to set corrected virtual dividing lines (78L, 78R) (S60) that pass through a position away from the other vehicles with respect to the standard virtual dividing lines when it is determined that there are other vehicles that would be an obstacle when the vehicle passes through the specific area (S40).Furthermore, when it is determined that the driver's level of alertness is reduced (S20), or when it is determined that there is a risk that the vehicle will cross the set virtual dividing line and deviate from the lane (S70), it is configured to execute at least one lane departure prevention control (S80).

According to the above configuration, when it is determined that there are no other vehicles that would be an obstacle to the vehicle passing through a specific area without lane markings, a standard virtual marking is set. In contrast, when it is determined that there are other vehicles that would be an obstacle to the vehicle passing through a specific area, a modified virtual marking is set so as to pass through a position away from the other vehicles with respect to the standard virtual marking. Furthermore, when it is determined that the driver's level of alertness is reduced, at least one lane departure prevention control is executed when it is determined that there is a risk that the vehicle will cross the set virtual marking and deviate from the lane.

Therefore, in a situation where there is another vehicle that is an obstacle in a specific area, even if the driver intentionally drives the vehicle along a route away from the other vehicle so as not to collide with the other vehicle, the risk of the vehicle being determined to cross the modified virtual dividing line is reduced. Therefore, the risk of unnecessary lane departure prevention control being executed is reduced, and the risk of the driver feeling annoyed by the lane departure prevention control can be reduced compared to when the modified virtual dividing line is not set.

In addition, according to the above configuration, when it is determined that the driver's level of alertness is low and that there is a risk that the vehicle will cross a set virtual dividing line and deviate from the lane, at least one of lane departure prevention controls is executed. Therefore, when there is a risk that the vehicle will cross a virtual dividing line and deviate from the lane when passing through a specific area, the risk of the vehicle crossing the virtual dividing line and deviating from the lane can be reduced by at least one of automatic steering of the steered wheels and issuance of an alarm.

In the above description, in order to aid in understanding the present invention, the names and/or symbols used in the embodiments described below are added in parentheses to the configuration of the invention corresponding to the embodiments. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and/or symbols added in parentheses. 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 described below with reference to the drawings.

1 is a schematic configuration diagram showing a driving assistance device according to an embodiment of the present invention; A diagram showing a situation in which a vehicle is traveling at an angle relative to the longitudinal direction of the lane. 5 is a flowchart showing a lane departure prevention control routine at an intersection according to the embodiment. FIG. 13 is a diagram showing a case where a vehicle passes through an intersection going straight through and where there are no waiting vehicles to turn right or left. FIG. 1 is a diagram showing a case where a vehicle passes through an intersection in which a vehicle is waiting to turn right while going straight. FIG. 1 is a diagram showing a case where a vehicle passes straight through an intersection where a vehicle is waiting to turn left. 1 is a diagram showing a case where a vehicle passes through an intersection by turning right at an intersection where there are no waiting vehicles to turn right or left; 1 is a diagram showing a case where a vehicle is turning right and passing through an intersection where a vehicle is waiting to turn left. FIG. 1 is a diagram showing a case where a vehicle is turning left when passing through an intersection where there are no waiting vehicles to turn right or left; 1 is a diagram showing a case where a vehicle is turning left and passing through an intersection where a vehicle waiting to turn right is present; 13 is a flowchart showing a modified example of a lane departure prevention control routine at an intersection.

The driving assistance device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

<Configuration>
1, a driving assistance device 100 according to the embodiment is applied to a vehicle 50 equipped with an electric power steering ECU 20, and includes a driving assistance ECU 10. In this specification, the electric power steering is referred to as EPS (short for Electric Power Steering) as necessary.

The driving assistance ECU 10 and the EPS ECU 20 are electronic control units that include a microcomputer as a main component, and are connected to each other via a CAN (Controller Area Network) 52 so that they can send and receive information to each other. Each microcomputer includes a CPU, ROM, RAM, non-volatile memory, an interface, etc. The CPU is configured to realize various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into a single ECU.

As will be described in detail later, the ROM of the driving assistance ECU 10 stores a program for lane departure prevention control, and the CPU executes lane departure prevention control in accordance with the program. The driving assistance ECU 10 is connected to a forward-viewing camera sensor 12, a radar sensor 14, an interior-viewing camera sensor 16, and an alarm device 18.

The forward-facing camera sensor 12 includes a camera unit and a recognition unit that analyzes image data captured by the camera unit to recognize landmarks such as white lines on the road. The camera unit captures the scenery ahead of the vehicle 50. The recognition unit supplies information about the recognized landmarks to the driving assistance ECU 10 at predetermined time intervals.

As shown in FIG. 2, the camera sensor 12 recognizes the white lines 56L and 56R that divide the lane 54, and is also capable of detecting the relative position of the vehicle with respect to the lane 54 based on the relationship between the white lines and the position of the vehicle 50. Here, the position of the vehicle 50 refers to the position of the center of gravity 50A of the vehicle, but may also be the central position of the vehicle in a plan view. The lateral position of the vehicle, which will be described later, refers to the position of the center of gravity in the lane width direction, and the lateral speed of the vehicle refers to the speed of the center of gravity in the lane width direction. These are found based on the relative positional relationship between the white lines detected by the camera sensor 12 and the vehicle.

The radar sensor 14 includes a radar transmitter/receiver and a signal processor (not shown). The radar transmitter/receiver emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by a three-dimensional object (e.g., another vehicle) within the emission range. The signal processor supplies the driving assistance ECU 10 with information (hereinafter referred to as three-dimensional object information) indicating the distance between the vehicle and the three-dimensional object, the relative speed between the vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the vehicle, etc., at predetermined time intervals, based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from transmitting the millimeter wave to receiving the reflected wave.

The driving assistance ECU 10 combines the target information provided by the camera sensor 12 with the three-dimensional object information provided by the radar sensor 14 to obtain highly accurate three-dimensional object information. Therefore, the camera sensor 12 and the radar sensor 14 function as an obstacle detection device that detects obstacles such as other vehicles stopped in front of the vehicle 12. Note that a LiDAR (Light Detection And Ranging) may be used instead of the camera sensor 12.

The driving assistance ECU 10 also determines whether or not there is a risk that the vehicle 50 will deviate from the lane based on the target object information provided by the camera sensor 12. In this case, the determination of whether or not there is a risk that the vehicle 50 will deviate from the lane by crossing a dividing line may be performed, for example, as follows. First, as shown in FIG. 2, an angle θy between the longitudinal direction 60 of the lane 54 and the vehicle's traveling direction 62 is estimated based on image information ahead of the vehicle 50. The angle θy is a positive value when the vehicle 50's traveling direction 62 is to the left of the longitudinal direction 60 of the lane 54. The moving speed Vy of the vehicle 50 in a direction perpendicular to the longitudinal direction 60 of the lane 54 is estimated as Vsinθy based on the angle θy and the vehicle speed V.

The distance Dy (not shown) in the lane width direction between the white line on the side that the vehicle 50 is approaching (white line 56L in the case of FIG. 2) and the center of gravity of the vehicle is estimated. Furthermore, when Dy-VyΔt is equal to or less than a preset reference value Dyc (a positive constant), where Δt is a preset time, it may be determined that the vehicle 50 is at risk of deviating from the lane. Note that, if the lane is curved, the above estimation and determination may be performed in the tangent direction of the lane at the center of gravity of the vehicle.

The in-vehicle camera sensor 16 is mounted on the dashboard or steering column and includes a camera unit that captures the driver's face and an image processing unit that processes image data of the driver's face captured by the camera unit. The image processing unit supplies image data of the driver's face to the driving assistance ECU 10 at predetermined time intervals. Thus, the in-vehicle camera sensor 16 functions as a driver monitor camera.

The CPU of the driving assistance ECU 10 judges the driver's level of alertness based on the driver's facial image data information, such as the driver's eye closing rate per minute, eye opening state, blinking frequency, or eye movement. The level of alertness is the degree to which the driver is alert, rather than in a state of drowsiness due to lack of sleep or the like. There are no particular limitations on the method of judging the level of alertness, and any method known in the art may be adopted. In addition, at least one of the driver's grip pressure on the steering wheel, pressing force on the armrest, heart rate, electromyographic information, and brain wave pattern may be taken into consideration when judging the level of alertness.

The warning device 18 is activated when the driving assistance ECU 10 determines that the vehicle 50 is at risk of deviating from its lane, and issues a warning as part of lane departure prevention control, i.e., issues a warning that the vehicle 50 is at risk of a collision. The warning device 18 may be any of a warning device that issues a visual warning such as a warning lamp, a warning device that issues an auditory warning such as a warning buzzer, a warning device that issues a physical warning such as seat vibration, or any combination thereof.

The EPS-ECU 20 can steer the steered wheels 24 as necessary by controlling the EPS device 22. Thus, the EPS-ECU 20 and the EPS device 22 constitute a steering device 26 that automatically steers the steered wheels 24 as necessary. When the driving assistance ECU 10 determines that it is necessary to correct the driving path of the vehicle 50, the EPS-ECU 20 performs automatic steering of the steered wheels 24 to correct the driving path of the vehicle 50 as another type of lane departure prevention control.

As shown in FIG. 1, a torque sensor 32 that detects steering torque Ts is provided on a steering shaft 30 to which a steering wheel 28 operated by a driver is integrally connected. A signal indicating the steering torque Ts detected by the torque sensor 32 is input to the EPS ECU 20. The EPS ECU 22 controls the steering assist torque by controlling the EPS device 22 in a manner known in the art based on the steering torque Ts and the vehicle speed detected by a vehicle speed sensor not shown in FIG. 1, thereby reducing the steering burden on the driver. The signal indicating the steering torque Ts is input from the EPS ECU 20 to the driving assistance ECU 10 via the CAN 52.

As part of the lane departure prevention control, the ROM of the driving assistance ECU 10 stores a program for lane departure prevention control at an intersection that corresponds to the flowchart shown in FIG. 2, and the CPU executes lane departure prevention control at an intersection in accordance with the program.

<Lane Departure Prevention Control Routine at Intersections>
Next, a lane departure prevention control routine at an intersection according to the embodiment will be described with reference to the flowchart shown in Fig. 3. The lane departure prevention control according to the flowchart shown in Fig. 3 is repeatedly executed by the CPU of the driving assistance ECU 10 at a predetermined control period when a lane departure prevention control switch, not shown in Fig. 1, is on. In the following description, the lane departure prevention control at an intersection will be simply referred to as "control".

First, in step S10, the CPU determines whether the vehicle 50 is passing through an intersection, that is, whether the vehicle is about to pass through the intersection or has already passed through the intersection. If the CPU makes a negative determination, it temporarily ends control, and if the CPU makes a positive determination, it advances control to step S20.

In step S20, the CPU determines whether the driver's wakefulness level, determined as described above, has fallen below a reference value based on the image data of the driver's face provided by the in-vehicle camera sensor 16. If the CPU determines that the driver's wakefulness level is not below a reference value, the CPU ends control once, and if the CPU determines that the driver's wakefulness level is not below a reference value, the CPU advances control to step S30.

In step S30, the CPU determines whether the driver intends to drive the vehicle through the intersection in a straight line, a right turn, or a left turn, based on the position of the turn signal lever (not shown in FIG. 1).

In step S40, the CPU determines whether there is another vehicle in the intersection that may be an obstacle to vehicle 50 traveling in the direction of travel identified in step S30. If the CPU determines that the other vehicle is in the intersection, the control proceeds to step S60. If the CPU determines that the other vehicle is in the intersection, the control proceeds to step S50.

In step S50, the CPU sets standard virtual lane lines in the intersection area for the vehicle 50 to travel in the travel direction of the vehicle 50 identified in step S30, as will be described later with reference to a specific example. The standard virtual lane lines may be set to smoothly connect the outer and inner lane lines of the lane in which the vehicle 50 is currently traveling, and the outer and inner lane lines of the lane in which the vehicle 50 will travel after passing through the intersection.

In step S60, the CPU sets a modified virtual lane marking in the intersection area for the vehicle 50 to travel in the direction of travel identified in step S30, as will be described later with reference to a specific example. The modified virtual lane marking is set to pass through a position farther away from other vehicles than the standard virtual lane marking.

In step S70, the CPU determines whether or not there is a risk that the vehicle will cross the imaginary dividing line and deviate from the lane, in a manner known in the art, based on the relative positional relationship of the vehicle 50 with respect to the target detected by the camera sensor 12. If the CPU determines that the vehicle is in danger of crossing the imaginary dividing line and deviating from the lane, it temporarily terminates control, and if the CPU determines that the vehicle is in danger of crossing the imaginary dividing line and deviates from the lane, it proceeds to step S80.

In particular, when left and right side camera sensors and a rear camera sensor are provided in addition to the forward-facing camera sensor 12, an overhead image of the entire circumference of the vehicle may be generated by processing image data captured by each camera sensor in a manner known in the art. Furthermore, virtual lane markings may be superimposed on the overhead image, and it may be determined whether or not there is a risk that the vehicle will cross the virtual lane markings and deviate from the lane based on the position and direction of movement of the vehicle relative to the virtual lane markings on the overhead image.

In step S80, the CPU executes lane departure prevention control. That is, the CPU activates the warning device 18 to issue a warning that the vehicle 50 is at risk of crossing the imaginary dividing line and departing from the lane. The CPU also outputs an automatic steering command signal to the EPS ECU 22, causing the EPS device 22 to automatically steer the steered wheels 24 so that the vehicle 50 does not cross the imaginary dividing line and depart from the lane.

<Example of lane departure prevention control at intersections>
Next, specific examples C1 to C9 of lane departure prevention control at an intersection performed in a situation where the driver's level of alertness is low will be described with reference to Figures 4 to 10. In Figures 4 to 10, reference numeral 70 denotes an intersection, reference numeral 72 denotes an outer dividing line of the road, and reference numeral 74 denotes a center dividing line (inner dividing line). Furthermore, reference numerals 76L and 76R denote standard imaginary dividing lines on the left and right, respectively, and reference numerals 78L and 78R denote modified imaginary dividing lines on the left and right, respectively.

<C1: Case where the vehicle 50 is traveling straight and there are no waiting vehicles in the intersection (FIG. 4)>
4 shows a case where the vehicle 50 passes through an intersection 70 in a straight line without any waiting vehicles making a right or left turn. In this case, standard imaginary demarcation lines 76L and 76R on the left and right sides are set based on the outer demarcation line 72 and the inner demarcation line 74 of the lane 80 in which the vehicle 50 is currently traveling, and the outer demarcation line 72 and the inner demarcation line 74 of the lane 82 in which the vehicle 50 will travel after passing the intersection 70. As shown in FIG. 4, the left imaginary demarcation line 76L is set as a straight line that smoothly connects the outer demarcation lines 72 of the lanes 80 and 82, and the right imaginary demarcation line 76R is set as a straight line that smoothly connects the inner demarcation lines 74 of the lanes 80 and 82.

<C2: When the vehicle 50 is traveling straight and there is a vehicle waiting to turn right in the intersection (FIG. 5)>
5 shows a case where the vehicle 50 passes straight through the intersection 70 where a waiting vehicle 84 is turning right. In this case, the corrected imaginary lane lines 78L and 78R are set to pass through positions farther away from the waiting vehicle 84 than the standard imaginary lane lines 76L and 76R on the left and right sides, respectively, except for both ends. As shown in FIG. 5, the corrected imaginary lane lines 78L and 78R are curved in such a way that they bulge out in a direction away from the waiting vehicle 84, relative to the standard imaginary lane lines 76L and 76R on the left and right sides, respectively.

<C3: When the vehicle 50 is traveling straight and there is a vehicle waiting to turn left in the intersection (FIG. 6)>
6 shows a case where the vehicle 50 passes straight through an intersection 70 where a waiting vehicle 86 is making a left turn. In this case, the corrected imaginary lane lines 78L and 78R are set to pass through positions farther away from the waiting vehicle 86 than the standard imaginary lane lines 76L and 76R on the left and right sides, respectively, except for both ends. As shown in FIG. 6, the corrected imaginary lane lines 78L and 78R are curved in a direction that bulges out in a direction away from the waiting vehicle 86 with respect to the standard imaginary lane lines 76L and 76R on the left and right sides, respectively.

<C4: When the vehicle 50 is turning right and there are no waiting vehicles in the intersection (FIG. 7)>
7 shows a case where the vehicle 50 passes through an intersection 70 by turning right when there are no waiting vehicles to turn right or left. In this case, standard imaginary demarcation lines 76L and 76R on the left and right sides are set based on the outer demarcation line 72 and the inner demarcation line 74 of the lane 80 in which the vehicle 50 is currently traveling, and the outer demarcation line 72 and the inner demarcation line 74 of the lane 88 in which the vehicle 50 will travel after turning right and passing through the intersection 70. As shown in FIG. 7, the left imaginary demarcation line 76L is set as an arc line connecting the outer demarcation lines 72 of the lanes 80 and 88, and the right imaginary demarcation line 76R is set as an arc line connecting the inner demarcation lines 74 of the lanes 80 and 88.

<C5: When the vehicle 50 is turning right and there is a vehicle waiting to turn left in the intersection (FIG. 8)>
Fig. 8 shows a case where the vehicle 50 turns right when passing through an intersection 70 where a waiting vehicle 86 is making a left turn. In this case, the modified imaginary lane lines 78L and 78R are set at positions farther away from the waiting vehicle 86 than the standard imaginary lane lines 76L and 76R on the left and right sides, respectively, except for both ends. As shown in Fig. 8, the modified imaginary lane lines 78L and 78R form curves that are deformed in a direction away from the waiting vehicle 86 with respect to the standard imaginary lane lines 76L and 76R on the left and right sides, respectively.

<C6: When the vehicle 50 is turning left and there are no waiting vehicles in the intersection (FIG. 9)>
9 shows a case where the vehicle 50 passes through an intersection 70 by turning left when there are no waiting vehicles to turn right or left. In this case, standard imaginary demarcation lines 76L and 76R on the left and right sides are set based on the outer demarcation line 72 and the inner demarcation line 74 of the lane 80 in which the vehicle 50 is currently traveling, and the outer demarcation line 72 and the inner demarcation line 74 of the lane 90 in which the vehicle 50 will travel after turning left and passing through the intersection 70. As shown in FIG. 9, the left imaginary demarcation line 76L is set as an arc line connecting the outer demarcation lines 72 of the lanes 80 and 90, and the right imaginary demarcation line 76R is set as an arc line connecting the inner demarcation lines 74 of the lanes 80 and 90.

<C7: When the vehicle 50 is turning left and there is a vehicle waiting to turn right in the intersection (FIG. 10)>
Fig. 10 shows a case where the vehicle 50 turns left to pass through an intersection 70 where a waiting vehicle 84 is turning right. In this case, the modified imaginary lane lines 78L and 78R are set at positions farther away from the waiting vehicle 84 than the standard imaginary lane lines 76L and 76R on the left and right sides, respectively, except for both ends. As shown in Fig. 10, the modified imaginary lane lines 78L and 78R form curves that are deformed in a direction away from the waiting vehicle 84 with respect to the standard imaginary lane lines 76L and 76R on the left and right sides, respectively.

In the above cases C1, C4, and C6, a determination is made as to whether the vehicle 50 is likely to cross the standard imaginary dividing lines 76L and 76R, and whether the vehicle will deviate from the lane when passing through the intersection 70. When it is determined that the vehicle 50 is likely to cross the standard imaginary dividing line 76L or 76R, the warning device 18 is activated to issue a warning, and the steered wheels 24 are automatically steered to correct the vehicle's travel route so that the vehicle 50 does not cross the standard imaginary dividing line 76L or 76R.

In contrast, in the above cases C2, C3, C5, and C7, a determination is made as to whether the vehicle 50 is likely to cross the revised imaginary dividing lines 78L and 78R, and whether the vehicle will deviate from the lane as the vehicle passes through the intersection 70. When it is determined that the vehicle 50 is likely to cross the revised imaginary dividing lines 78L and 78R, the warning device 18 is activated to issue a warning, and the steered wheels 24 are automatically steered to correct the vehicle's travel route so that the vehicle 50 does not cross the revised imaginary dividing lines 78L and 78R.

As can be seen from the above description, according to the embodiment, when it is determined that there are no other vehicles 84, 86 that would be an obstacle when the vehicle 50 passes through the intersection 70, which is a specific area without lane markings (S40), the standard virtual markings 76L or 76R are set (S50). In contrast, when it is determined that there is another vehicle that would be an obstacle when the vehicle passes through the specific area (S40), the corrected virtual markings 78L and 78R are set so as to pass through a position away from the other vehicles with respect to the standard virtual markings (S60). Furthermore, when it is determined that the driver's level of alertness is reduced (S20), or when it is determined that there is a risk that the vehicle will cross the set virtual markings and deviate from the lane (S70), automatic steering of the steered wheels and issuance of an alarm, i.e., lane departure prevention control, is executed (S80).

Therefore, in a situation where there is another vehicle obstructing the intersection, even if the driver intentionally drives the vehicle along a route away from the other vehicle so as not to collide with the other vehicle, the risk of the vehicle being determined to cross the modified virtual dividing line is reduced. Therefore, the risk of unnecessary lane departure prevention control being executed is reduced, and the risk of the driver feeling annoyed by the lane departure prevention control can be reduced compared to when the modified virtual dividing line is not set.

In addition, according to the embodiment, when it is determined that the driver's level of alertness is low (S20) and it is determined that there is a risk that the vehicle will cross a set virtual dividing line and deviate from the lane (S70), lane departure prevention control is executed (S80). Therefore, in a situation in which the driver's level of alertness is low, when there is a risk that the vehicle will cross a virtual dividing line and deviate from the lane when passing through a specific area, the lane departure prevention control is executed to reduce the risk that the vehicle will cross the virtual dividing line and deviate from the lane.

In particular, according to the embodiment, the vehicle's travel direction at the intersection intended by the driver is identified (S30), and standard virtual demarcation lines 76L and 76R or modified virtual demarcation lines 78L and 78R are set for the identified travel direction (S50, S60). This makes it possible to avoid unnecessary setting of standard virtual demarcation lines or modified virtual demarcation lines for a vehicle travel direction that is not intended by the driver.

In the embodiment, the determination of whether the driver's alertness has fallen below the reference value is performed between steps S10 and S30. However, as shown in FIG. 11 as a modification example, the determination of whether the driver's alertness has fallen below the reference value (step S65) may be performed between steps S50 and S60 and step S70. However, according to the embodiment, the above determination is performed prior to steps S40 to S60, so that it is possible to avoid unnecessary setting of the standard virtual lane line or the modified virtual lane line in a situation where the driver's alertness has not fallen below the reference value.

Although the present invention has been described in detail above with respect to a specific embodiment, the present invention is not limited to the above-described embodiment, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present invention.

For example, in the above embodiment, lane departure prevention control involves issuance of an alarm by activation of the alarm device 18 and automatic steering of the steered wheels 24 by the EPS device 22. However, either issuance of an alarm or automatic steering of the steered wheels 24 may be omitted.

In addition, in the above-described embodiment, the specific intersection where there are no lane markings is an intersection, but the specific area may be an area other than a crossroads, such as a T-junction or a Y-junction.

In addition, in the above embodiment, virtual lane lines are set when the vehicle turns right or left at a crossroads, but the setting of virtual lane lines at a crossroads may be limited to when the vehicle travels straight.

In addition, in the above embodiment, it is determined in step S20 whether the driver's alertness has decreased, but the determination of whether the driver's alertness has decreased may be omitted.

Furthermore, in the above embodiment, the driving direction of the vehicle at the intersection intended by the driver is identified in step S30, and standard virtual demarcation lines 76L, 6R and modified virtual demarcation lines 78L, 78R are set for the driving direction identified in steps S50 and S60. However, step S30 may be omitted, and standard virtual demarcation lines and modified virtual demarcation lines may be set for all directions in which the vehicle may travel.

Furthermore, if the corrected virtual dividing line excessively extends beyond the outer or inner dividing line, the lane departure prevention control may be modified so that an alarm is output to temporarily stop the vehicle until the corrected virtual dividing line stops excessively.

10... Driving assistance ECU, 12... Front camera sensor, 14... Radar sensor, 16... Interior camera sensor, 18... Warning device, 20... Electric power steering ECU, 22... EPS device, 24... Steering wheels, 50... Vehicle, 54... Lane, 56, 58... White lines, 70... Intersection, 76L, 76R... Standard virtual dividing lines, 78L, 78R... Modified virtual dividing lines, 100... Lane departure prevention device

Claims (1)

A driving assistance device including a control unit that performs lane departure prevention control of at least one of automatic steering of steered wheels and issuance of an alarm when it is determined that a vehicle is at risk of crossing a lane marking and departing from the lane,
The control unit is configured to set a standard virtual dividing line when it determines that there are no other vehicles that would be an obstacle to the vehicle passing through a specific area without lane markings, and to set a corrected virtual dividing line that passes through a position away from the other vehicles with respect to the standard virtual dividing line when it determines that there are other vehicles that would be an obstacle to the vehicle passing through the specific area, and further to execute at least one of the lane departure prevention controls when it determines that the driver's alertness has decreased and that there is a risk that the vehicle will deviate from the lane by crossing the set virtual dividing line.

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