Lane deviation prevention device and method

Abstract

To provide a lane deviation prevention device and method which can avoid the possibility that a driver feels uneasiness or troublesome when a vehicle travels on a narrow road with no center lines.SOLUTION: The present invention relates to a lane deviation prevention device including a drive support ECU so constituted as to execute (S50) yaw moment application control that a yaw moment for preventing deviation of an own vehicle from a lane is applied to the vehicle when the vehicle is determined (S10) to have the possibility of deviation of the vehicle from tha lane on the basis of information acquired by a target information acquisition device for acquiring information on a target around the vehicle, wherein the drive support ECU reduces (S70) the yaw moment, as compared with the case where it is determined that the vehicle travels on a road with center lines and possibly deviates from the lane to an out-of-road direction, when it is determined (S10 to S30) that the vehicle travels on a road with no center lines and possibly deviates from the lane to the out-of-road direction.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a lane departure suppression device and method for vehicles such as automobiles.

Background Art

[0002] As one of the driving assistance devices for vehicles such as automobiles, there is known a lane departure suppression device that applies a yaw moment to suppress the departure of the vehicle from the lane when it is determined that the vehicle may deviate from the lane.

[0003] For example, in Patent Document 1 below, when the speed at which the vehicle approaches the lane boundary is low, a yaw moment is applied to the vehicle, and when the speed at which the vehicle approaches the lane boundary is high, the yaw moment is applied and the vehicle is braked. A lane departure suppression device is described. According to the lane departure suppression device described in Patent Document 1 below, compared with the case where the control mode of returning the vehicle to the center of the lane does not change according to the speed at which the vehicle approaches the lane boundary, the driver can feel anxious or annoyed. The risk can be reduced.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] 〔Problems to be Solved by the Invention〕 When a vehicle travels on a narrow road without a center line, if the same yaw moment is applied as when the vehicle travels on a road with a center line, the driver may feel that the control of returning the vehicle to the center of the lane is excessive, There is a risk of feeling anxious or annoyed.

[0006] The present invention provides an improved lane departure suppression device and method that, when there is a risk of the vehicle deviating from the lane, suppress the vehicle from deviating from the lane while further reducing the risk of the driver feeling anxiety or annoyance. 〔Means for Solving the Problems and Effects of the Invention〕

[0007] According to the present invention, there is provided a lane departure suppression device (100) including a target information acquisition device (18) that acquires information on targets around the vehicle (102), and a control unit (driving support ECU 10) configured to execute yaw moment application control (S50) for applying a yaw moment (My) that suppresses the vehicle from deviating from the lane to the vehicle when it is determined that there is a risk of the vehicle deviating from the lane based on the information on the targets acquired by the target information acquisition device (S10).

[0008] When it is determined that the vehicle is traveling on a road without a center line and there is a risk of deviating from the lane in the off-road direction (S10 to S30), the control unit (driving support ECU 10) is configured to reduce the yaw moment (S70) compared to when it is determined that the vehicle is traveling on a road with a center line and there is a risk of deviating from the lane in the off-road direction.

[0009] Further, according to the present invention, there is provided a lane departure suppression method including a step (S10) of determining whether there is a risk of the vehicle deviating from the lane based on information on targets around the vehicle (102) acquired by the target information acquisition device (18), and a step (S50) of executing yaw moment application control for applying a yaw moment that suppresses the vehicle from deviating from the lane to the vehicle when it is determined that there is a risk of the vehicle deviating from the lane.

[0010] The driving control method further includes a step (S20, S30) of determining whether the vehicle is traveling on a road without a center line, and a step (S70) of reducing the yaw moment when it is determined that the vehicle is traveling on a road without a center line and there is a risk of deviating from the lane in the off-road direction, compared to when it is determined that the vehicle is traveling on a road with a center line and there is a risk of deviating from the lane in the off-road direction.

[0011] According to the above driving control device and method, when it is determined that the vehicle is running on a road without a center line and there is a risk of deviating from the lane in the off-road direction, compared with the case where it is determined that the vehicle is running on a road with a center line and there is a risk of deviating from the lane in the off-road direction, the yaw moment for suppressing the vehicle from deviating from the lane is reduced.

[0012] Therefore, compared with the case where the yaw moment is not reduced, the yaw moment applied to the vehicle is reduced. Thus, it is possible to reduce the risk that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance. Even when it is determined that the vehicle is running on a road without a center line and there is a risk of deviating from the lane in the off-road direction, since the reduced yaw moment is applied to the vehicle, the risk of the vehicle deviating from the lane can be reduced compared with the case where the yaw moment is not applied. 〔Aspect of the Invention〕

[0013] In one aspect of the present invention, when the control unit (driving support ECU 10) determines that only the information of the demarcation line (white line 112) on the side where the vehicle may deviate as the demarcation line of the road within a predetermined range from the vehicle is acquired by the target information acquisition device (18) (S20), it is configured to determine that the road is a road without a center line (S70).

[0014] According to the above aspect, when it is determined that only the information of the demarcation line on the side where the vehicle may deviate as the demarcation line of the road within a predetermined range from the vehicle is acquired, it is determined that the road is a road without a center line. Therefore, in a situation where only the information of the demarcation line on the side where the vehicle may deviate is acquired, the yaw moment applied to the vehicle is reduced. Accordingly, it is possible to reduce the risk that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance.

[0015] In another aspect of the present invention, when the control unit (driving support ECU 10) determines that the information on the lane lines on both sides of the vehicle is acquired as the lane lines of the road within a predetermined range from the vehicle by the target information acquisition device (18) and the interval between the lane lines on both sides is equal to or greater than the reference interval (S20, S30), the road is configured to be determined as a road without a center line (S70).

[0016] Generally, since the width of the lane is within a predetermined width range, when the information on the lane lines on both sides of the vehicle is acquired and the interval between the lane lines on both sides is equal to or greater than the reference interval, the road is considered to be a road without a center line whose width exceeds the predetermined width range.

[0017] According to the above aspect, when the information on the lane lines on both sides of the vehicle is acquired as the lane lines of the road within a predetermined range from the vehicle and it is determined that the interval between the lane lines on both sides is equal to or greater than the reference interval, the road is determined to be a road without a center line. Therefore, when the road is a road without a center line, it can be determined.

[0018] Furthermore, in another aspect of the present invention, the control unit (driving support ECU 10) is configured to gradually reduce the yaw moment applied to the vehicle after a predetermined time has elapsed since the start of the yaw moment application control (S72) (S74).

[0019] According to the above aspect, until a predetermined time has elapsed since the start of the yaw moment application control, the yaw moment applied to the vehicle is not reduced, and the yaw moment applied to the vehicle is gradually reduced after a predetermined time has elapsed since the start of the yaw moment application control. Therefore, until a predetermined time has elapsed, it is possible to effectively suppress the vehicle from deviating from the lane. In addition, after a predetermined time has elapsed, the yaw moment is gradually reduced, and it is possible to reduce the risk that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance.

[0020] In the present application, "lane" means a driving area where a vehicle can travel, and refers to the area between the white lines defining the driving area, the boundaries of the road, etc. "Outside the road" means the side of the non-driving area with respect to the boundary between the driving area where a vehicle can travel and the non-driving area where a vehicle cannot travel. "Deviating outside the road" means that the preset reference position of the vehicle moves from the driving area to the non-driving area.

[0021] In the above description, for the purpose of assisting the understanding of the present invention, the names and / or symbols used in the embodiments corresponding to the embodiments to be described later are attached in parentheses to the configuration of the invention. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and / or symbols attached in parentheses. Other objects, other features and accompanying advantages of the present invention will be easily understood from the description of the embodiments of the present invention described with reference to the following drawings.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Mode for Carrying Out the Invention

[0023] With reference to the attached drawings below, the vehicle driving control device and driving control method according to embodiments of the present invention will be described in detail.

[0024] As shown in FIG. 1, the driving control device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 is a vehicle capable of autonomous driving and includes a drive ECU 20, a brake ECU 30, an electric power steering ECU 40, and a meter ECU 50. An ECU means an electronic control unit (Electronic Control Unit) mainly including a microcomputer. In the following description, the vehicle 102 is referred to as the host vehicle as necessary to distinguish it from other vehicles. Also, the electric power steering is referred to as EPS.

[0025] The microcomputer of each ECU includes a CPU, a ROM, a RAM, a readable and writable non-volatile memory (N / M), and an interface (I / F), etc. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Further, these ECUs are connected to each other so as to be able to exchange data (communicate) via a CAN (Controller Area Network) 104. Therefore, the detection values of sensors (including switches) connected to a specific ECU are also transmitted to other ECUs.

[0026] The driving support ECU 10 is a central control device that performs driving support driving control such as lane departure suppression control and inter-vehicle distance control. In the embodiment, the driving support ECU 10 cooperates with other ECUs to execute lane departure suppression control, as will be described in detail later. In the embodiment, as part of the lane departure suppression control, yaw moment application control is executed, as will be described in detail later.

[0027] The driving support ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a switch 16. The camera sensor 12 and the radar sensor 14 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 18 that acquires target information around the vehicle 102.

[0028] Each camera device of the camera sensor 12 includes, although not shown in the figure, a camera unit that photographs the surroundings of the vehicle 102, and a recognition unit that analyzes the image data obtained by the camera unit to recognize targets such as white lines on the road and other vehicles. The recognition unit supplies information about the recognized targets to the driving support ECU 10 at predetermined time intervals.

[0029] Each radar device of the radar sensor 14 includes a radar transceiver and a signal processing unit (not shown). The radar transceiver emits radio waves in the millimeter wave band (hereinafter referred to as "millimeter waves"), and receives the millimeter waves (i.e., reflected waves) reflected by solid objects (e.g., other vehicles, bicycles, etc.) existing within the radiation range. The signal processing unit is 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, etc., and supplies information representing the distance between the host vehicle and the solid object, the relative speed between the host vehicle and the solid object, and the relative position (direction) of the solid object with respect to the host vehicle to the driving support ECU 10 at predetermined time intervals. Note that, instead of or in addition to the radar sensor 14, LiDAR (Light Detection And Ranging) may be used.

[0030] The switch 16 is provided at a position operable by the driver, such as a steering wheel not shown in FIG. 1, and is configured to be operated by the driver. The driving support ECU 10 executes lane departure suppression control when the switch 16 is on, as will be described in detail later.

[0031] The drive ECU 20 is connected to a drive device 22 that accelerates the vehicle 102 by applying a driving force to the drive wheels 24. The drive ECU 20 normally controls the drive device 22 so that the driving force generated by the drive device 22 changes according to the driving operation by the driver, and when receiving a command signal from the driving support ECU 10, controls the drive device 22 based on the command signal.

[0032] The brake ECU 30 is connected to a braking device 32 that decelerates the vehicle 102 by applying a braking force to the wheels 34. The brake ECU 30 normally controls the braking device so that the braking force generated by the braking device 32 changes according to the braking operation by the driver, and when receiving a command signal from the driving support ECU 10, performs automatic braking by controlling the braking device 32 based on the command signal.

[0033] Therefore, the brake ECU 30 and the braking device 32 cooperate with each other to function as an automatic braking device 36, can control the braking force of the entire vehicle 102, and can also individually control the braking force of each wheel. When a braking force is applied to the wheels by lane departure suppression control or the like, a brake lamp (not shown in FIG. 1) is lit.

[0034] The EPS-ECU 40 is connected to an EPS device 42. The EPS-ECU 40 controls the EPS device 42 in a manner known in the art based on the steering torque Ts and the vehicle speed V detected by a driving operation sensor 60 and a vehicle state sensor 70, which will be described later, thereby controlling the steering assist torque and reducing the driver's steering burden. Further, the EPS-ECU 40 can steer the steered wheels 44 as necessary by controlling the EPS device 42. Therefore, the EPS-ECU 40 and the EPS device 42 function as an automatic steering device 46 that automatically steers the steered wheels as necessary.

[0035] The meter ECU 50 is connected to a touch panel type display 52 that displays the status of control by the driving support ECU 10 and an alarm device 54 that issues an alarm. The display 52 may be, for example, a multi-information display on which meters and various types of information are displayed, or may be a display of a navigation device. When the display 52 receives a signal from the driving support ECU 10, it may be configured to display the status of the lane departure suppression control.

[0036] The alarm device 54 is activated when it is determined that the vehicle 102 may deviate from the lane, and issues an alarm as one of the lane departure suppression controls, that is, issues an alarm indicating that the vehicle 102 may deviate from the lane. The alarm device 54 may be any of an alarm device that emits a visual alarm such as an alarm lamp, an alarm device that emits an auditory alarm such as an alarm buzzer, and an alarm device that emits a tactile alarm such as vibration of a seat, or any combination thereof.

[0037] The driving operation sensor 60 and the vehicle state sensor 70 are also connected to the CAN 104. Information detected by the driving operation sensor 60 and the vehicle state sensor 70 (referred to as sensor information) is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 can be appropriately used in each ECU. Note that the sensor information is information of a sensor connected to a specific ECU and may be transmitted from the specific ECU to the CAN 104.

[0038] The driving operation sensor 60 includes a drive operation amount sensor that detects the operation amount of the accelerator pedal, a braking operation amount sensor that detects the master cylinder pressure or the stepping force on the brake pedal, and a brake switch that detects the presence or absence of the operation of the brake pedal. Further, the driving operation sensor 60 includes a steering angle sensor that detects the steering angle θ, a steering torque sensor that detects the steering torque, a turn signal switch that indicates the presence or absence and the direction of the operation of the turn signal lever, and the like. Note that the steering angle θ becomes a positive value when the vehicle turns left.

[0039] The vehicle state sensor 70 includes a vehicle speed sensor that detects the vehicle speed V of the vehicle 102, a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, a lateral acceleration sensor that detects the lateral acceleration of the vehicle, and a yaw rate sensor that detects the yaw rate of the vehicle, and the like.

[0040] In the embodiment, the ROM of the driving support ECU 10 stores a lane departure suppression control program corresponding to the flowcharts shown in FIGS. 2 and 3. The lane departure suppression method according to the embodiment is executed by executing lane departure suppression control according to the flowchart shown in FIG. 2. <Lane Departure Suppression Control (FIG. 2)>

[0041] Next, the lane departure suppression control in the embodiment will be described with reference to the flowchart shown in FIG. 2. The lane departure suppression control according to the flowchart shown in FIG. 2 is repeatedly executed by the CPU of the driving support ECU 10 at predetermined time intervals in a situation where the switch 16 is on. In the following description, the lane departure suppression control is referred to as "this control".

[0042] First, in step S10, the CPU determines whether the vehicle 102 is about to deviate from the lane and whether the start condition of the yaw moment application control is satisfied based on the information of the target acquired by the target information acquisition device 18 and the like. When a negative determination is made, this control ends once, and when an affirmative determination is made, this control proceeds to step S20. The start condition of the yaw moment application control may be a start condition known in the art, such as the start conditions described in Japanese Patent Application Laid-Open No. 2023-65900 and Japanese Patent Application Laid-Open No. 2020-11562.

[0043] In step S20, the CPU determines, based on the information of the target acquired by the target information acquisition device 18, whether the white lines on both sides of the vehicle are detected as lane lines within a predetermined range from the vehicle 102. When a negative determination is made, this control proceeds to step S40. When an affirmative determination is made, this control proceeds to step S30. Note that a negative determination is also made when only the white line on the left side of the vehicle is detected.

[0044] In step S30, the CPU determines whether the distance between the white lines on both sides of the vehicle 102 is less than the reference distance, that is, whether the width of the lane is less than the reference value of the width. The reference value may be the maximum lane width at which a plurality of vehicles do not run side by side, for example, a positive constant such as 4.5 m. When an affirmative determination is made, this control proceeds to step S50. When a negative determination is made, this control proceeds to step S40.

[0045] In step S40, the CPU determines whether there is an oncoming vehicle traveling in the adjacent lane and approaching the vehicle 102 or another vehicle traveling in the same lane and attempting to overtake the vehicle 102. When an affirmative determination is made, this control proceeds to step S70. When a negative determination is made, this control proceeds to step S50.

[0046] In step S50, the CPU executes a standard yaw moment application control for applying a standard yaw moment Myn to the vehicle to suppress the vehicle 102 from deviating from the lane. For example, the CPU calculates a standard target steering angle θtn necessary to reduce the risk according to the risk of the vehicle 102 deviating from the lane. Further, the CPU controls the automatic steering device 46 so that the steering angle θ becomes the standard target steering angle θtn by outputting a command signal to the EPS·ECU 40 and steers the steering wheel 44 to apply the standard yaw moment Myn to the vehicle.

[0047] In step S60, the CPU determines whether the end condition of the standard yaw moment application control is satisfied based on the information of the target acquired by the target information acquisition device 18 and the like, such that there is no risk of the vehicle 102 deviating from the lane. When a negative determination is made, this control returns to step S50. When an affirmative determination is made, the standard yaw moment application control ends and this control temporarily ends. Note that the end condition of the yaw moment application control may also be a known end condition in the art, such as the end conditions described in, for example, Japanese Unexamined Patent Application Publication No. 2023-65900 and Japanese Unexamined Patent Application Publication No. 2020-11562.

[0048] In step S70, the CPU executes reduced yaw moment application control to apply a reduced yaw moment to the vehicle to suppress the vehicle 102 from deviating from the lane according to the subroutine shown in FIG. 3.

[0049] In step S80, the CPU determines whether the end condition of the reduced yaw moment application control is satisfied based on the information of the target acquired by the target information acquisition device 18 and the like. When a negative determination is made, this control returns to step S70. When an affirmative determination is made, the reduced yaw moment application control ends and this control temporarily ends. Note that the end condition of the reduced yaw moment application control may be an end condition in which the application of the yaw moment continues longer compared to the standard yaw moment application control. Further, the end condition of the reduced yaw moment application control may include that the absolute value of the yaw angle of the vehicle is less than or equal to a determination reference value (a positive constant) to confirm that the traveling direction of the vehicle is substantially along the lane. <Reduced Yaw Moment Application Control (FIG. 3)>

[0050] Next, with reference to FIG. 3, the reduced yaw moment application control in step S70 will be described.

[0051] In step S71, the CPU calculates a standard target steering angle θtn necessary to reduce the risk of the vehicle 102 deviating from the lane in a manner known in the art according to the risk.

[0052] In step S72, the CPU determines whether or not a first predetermined time has elapsed since the application of a standard yaw moment Myn to the vehicle 102 was started by controlling the steering angle θ in step S78 described later. When a negative determination is made, this control proceeds to step S75, and when an affirmative determination is made, this control proceeds to step S73. The first predetermined time may be a fixed time, or may be the time until the risk of the vehicle 102 deviating from the lane decreases to a preset yaw moment reduction start reference value.

[0053] In step S73, the CPU determines whether or not a second predetermined time longer than the first predetermined time has elapsed since the application of a standard yaw moment Myn to the vehicle 102 was started by controlling the steering angle θ in step S78 described later. When an affirmative determination is made, this control proceeds to step S76, and when a negative determination is made, this control proceeds to step S74. The second predetermined time may also be a fixed time, or may be the time until the risk of the vehicle 102 deviating from the lane further decreases below the yaw moment reduction start reference value.

[0054] In step S74, the CPU reduces and corrects the standard target steering angle θtn so that the magnitude of the standard target steering angle θtn becomes smaller. The reduction and correction of the standard target steering angle θtn may be achieved by multiplying the standard target steering angle θtn by a positive correction coefficient smaller than 1 or subtracting a positive correction reduction amount from the standard target steering angle θtn.

[0055] In step S75, the CPU sets the target steering angle θt to the standard target steering angle θtn.

[0056] In step S76, the CPU calculates a gradually increasing steering angle θtr whose sign is opposite to that of the standard target steering angle θtn and whose magnitude gradually increases.

[0057] In step S77, the CPU sets the target steering angle θt to the sum θtn + θtr of the standard target steering angle θtn and the gradually increasing steering angle θtr.

[0058] In step S78, the CPU controls the automatic steering device 46 by outputting a command signal to the EPS·ECU 40 so that the steering angle θt becomes the target steering angle θt, thereby applying a yaw moment My to the vehicle. The yaw moment My is the same as the standard yaw moment Myn applied in step S50 until the first predetermined time elapses, and gradually becomes smaller than the standard yaw moment until the second predetermined time elapses after the first predetermined time has elapsed. Further, after the second predetermined time has elapsed, the yaw moment My becomes the sum of the standard yaw moment Myn that gradually decreases and the yaw moment Myr that gradually increases in the direction opposite to the standard yaw moment.

[0059] Therefore, after the second predetermined time has elapsed since the start of the yaw moment application control, the yaw moment Myr in the direction opposite to the standard yaw moment Myn gradually increases, so the yaw angle of the vehicle with respect to the lane is gradually reduced, and the vehicle gradually approaches a state of traveling along the lane. <Operation of the Embodiment>

[0060] Next, with reference to FIGS. 4 to 6, the operation of the embodiment will be described for the case where the host vehicle 102 travels on a left-hand traffic road with different lane conditions and there is a risk of deviating from the lane in the off-road direction. In FIGS. 4 to 6, 110 indicates the road on which the vehicle 102 travels, and 112 indicates the white line on the left side of the host vehicle 102. 114 indicates the center line, and 116 indicates the own lane between the left white line 112 and the center line 114. Further, 118 indicates an oncoming vehicle traveling in the direction opposite to the host vehicle 102, and 120 indicates the white line on the left side of the oncoming vehicle. <C1: When the dividing lines on both sides are detected and the width is less than the reference value (FIG. 4)>

[0061] In this case, in steps S20 and S30, an affirmative determination is made, and in step S50, by executing the standard yaw moment application control, the standard yaw moment Myn is applied to the vehicle 102. Therefore, compared with the case where a reduced yaw moment is applied to the vehicle (S70), it is possible to effectively suppress the vehicle 102 from deviating from the lane.

[0062] In addition, since the center line 114, which is the right side dividing line, is also detected, even if there is a risk that the vehicle may deviate from the right side dividing line due to the standard yaw moment application control, the yaw moment application control for suppressing the deviation is performed. Therefore, there is no sense of discomfort that the vehicle is about to cross the right side dividing line or that the vehicle is approaching an oncoming vehicle. <C2: When the dividing lines on both sides are detected, but the width is equal to or greater than the reference value (Figure 5)>

[0063] In this case, the road on which the vehicle 102 travels is likely to be a road without a center line. In step S20, an affirmative determination is made, but in step S30, a negative determination is made. Therefore, if there is no oncoming vehicle or the like, in step S40, an affirmative determination is made, so in step S70, by executing the reduced yaw moment application control, the reduced yaw moment My is applied to the vehicle 102.

[0064] Therefore, compared with the case where the standard yaw moment Myn is applied to the vehicle (S50), the suppression of deviation is performed gently, so it is possible to suppress the vehicle's orientation from changing excessively in the direction of the dividing line 114 on the side opposite to the deviation side and the yaw angle with respect to the lane from becoming excessive. Therefore, compared with the case where the yaw moment My is not reduced, it is possible to reduce the risk that the vehicle approaches the right side dividing line excessively or that the vehicle occupants feel a sense of discomfort that the vehicle approaches an oncoming vehicle or the like excessively.

[0065] In particular, according to the embodiment, until the first predetermined time elapses from the start of the application of the yaw moment, the yaw moment is the standard yaw moment, and until the second predetermined time elapses after the first predetermined time elapses from the start of the application of the yaw moment, the yaw moment is gradually reduced. Further, after the second predetermined time elapses, the yaw moment My becomes the sum of a standard yaw moment Myn that gradually decreases and a yaw moment Myr that gradually increases in the direction opposite to the standard yaw moment.

[0066] Therefore, as indicated by the solid arrow in FIG. 5, in a situation where the deviation of the vehicle is suppressed by the yaw moment application control, it is possible to prevent the direction of the vehicle from excessively changing in the direction of the partition line 114 on the side opposite to the deviation side, and to gradually reduce the yaw angle with respect to the lane. <C3: When only the left partition line is detected (FIG. 6)>

[0067] In this case, in step S20, a negative determination is made. Therefore, if there is no oncoming vehicle or the like, in step S40, an affirmative determination is made. Accordingly, in the same manner as in the case of C2 above, in step S70, by executing the reduced yaw moment application control, the reduced yaw moment My is applied to the vehicle 102.

[0068] Therefore, as indicated by the solid arrow in FIG. 6, in the same manner as in the case of C2 above, in a situation where the deviation of the vehicle is suppressed, it is possible to prevent the direction of the vehicle from excessively changing in the direction opposite to the deviation direction, and to gradually reduce the yaw angle with respect to the lane.

[0069] In addition, in the cases of C2 and C3 above, when there is no oncoming vehicle traveling in the direction opposite to that of the vehicle 102, a negative determination is made in step S40. Therefore, similar to the case of C1 above, in step S50, standard yaw moment application control is executed. Therefore, compared to the case where a reduced yaw moment is applied to the vehicle from the beginning of the start of yaw moment application (S70), it is possible to effectively suppress the vehicle 102 from deviating from the lane. Also, since there is no oncoming vehicle or the like, the passengers in the vehicle will not feel any discomfort due to the vehicle approaching an oncoming vehicle or the like.

[0070] As can be understood from the above description, according to the present invention, when it is determined that the vehicle 102 is traveling on a road 110 without a center line 114 and there is a risk of deviating from the lane 116 in the off-road direction (S10 to S30), compared to when it is determined that there is a risk of deviating from the lane 116 in the off-road direction while traveling on a road with a center line, the yaw moment My for suppressing the vehicle from deviating from the lane is reduced.

[0071] Therefore, compared to the case where the yaw moment is not reduced, the yaw moment applied to the vehicle is reduced, so it is possible to reduce the risk that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance. Even when it is determined that the vehicle is traveling on a road without a center line and there is a risk of deviating from the lane in the off-road direction, since a reduced yaw moment is applied to the vehicle, compared to the case where the yaw moment is not applied, it is possible to suppress the vehicle from deviating from the lane.

[0072] Also, when it is determined that only the information of the lane line 112 on the side where the vehicle may deviate is acquired as the lane line of the road 110 within a predetermined range from the vehicle 102 (S20), it is determined that the road is a road without a center line (S70). Therefore, in a situation where only the information of the lane line on the side where the vehicle may deviate is acquired, the yaw moment applied to the vehicle is reduced. Accordingly, it is possible to reduce the possibility that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance.

[0073] Also, when the information of the lane lines 112 and 114 on both sides of the vehicle is acquired as the lane lines of the road 110 and it is determined that the interval between the lane lines on both sides is equal to or greater than the reference interval (S20, S30), it is determined that the road is a road without a center line (S70). Therefore, when the road is a road without a center line, this can be determined.

[0074] Furthermore, until a predetermined time has elapsed since the start of the yaw moment application control (S72), the yaw moment applied to the vehicle is not reduced, and the yaw moment applied to the vehicle is gradually reduced after a predetermined time has elapsed since the start of the yaw moment application control (S74). Therefore, until a predetermined time has elapsed, it is possible to effectively suppress the vehicle from deviating from the lane. Also, after a predetermined time has elapsed, the yaw moment is gradually reduced, and it is possible to reduce the possibility that the driver feels that the control for turning the vehicle in the direction opposite to the direction of deviating from the lane is excessive and feels anxiety or annoyance.

[0075] Although the present invention has been described in detail with respect to specific embodiments above, it is obvious to those skilled in the art that the present invention is not limited to the above-described embodiments, and various other embodiments are possible within the scope of the present invention.

[0076] For example, in the above-described embodiment, in step S40, it is determined whether there is an oncoming vehicle approaching vehicle 102 while traveling in an adjacent lane or another vehicle attempting to overtake vehicle 102 while traveling in its own lane. However, step S40 may be omitted.

[0077] Also, in the above-described embodiment, in step S70, until the first predetermined time has elapsed since the start of the application of the yaw moment, the yaw moment is the standard yaw moment, and when the first predetermined time has elapsed since the start of the application of the yaw moment, the standard yaw moment is gradually reduced. However, the standard yaw moment may be gradually reduced from the start of the application of the yaw moment.

[0078] Also, in the above-described embodiment, in step S70, when the second predetermined time has elapsed since the start of the application of the yaw moment, an increasing steering angle θtr is calculated whose sign is opposite to that of the standard target steering angle θtn and whose magnitude gradually increases, and the target steering angle θt is set to the sum θtr + θtr of the standard target steering angle θtn and the increasing steering angle θtr. However, the calculation of the increasing steering angle θtr may be omitted, and the target steering angle θt may be set only to the standard target steering angle θtn.

[0079] Also, in the above-described embodiment, when an affirmative determination is made in step S30, this control proceeds to step S50. However, when an affirmative determination is made in step S30, it is determined whether there is a vehicle traveling area on the side opposite to vehicle 102 with respect to the right white line, and when an affirmative determination is made, this control proceeds to step S50, and when a negative determination is made, this control may proceed to step S40.

[0080] Furthermore, in the above-described embodiment, the application of the yaw moment My is performed by controlling the automatic steering device 46 so that the steering angle θ becomes the standard target steering angle θtn and steering the steering wheel 44. However, at least a part of the yaw moment My may be generated by the difference in the driving and braking forces of the left and right wheels.

Explanation of Reference Numerals

[0081] 10… Driving support ECU, 12… Camera sensor, 14… Radar sensor, 16… Switch, 18… Target information acquisition device, 20… Drive ECU, 30… Brake ECU, 36… Automatic braking device, 40… Meter ECU, 100… Driving control device, 102… Vehicle

Claims

1. In a lane departure suppression device including a target information acquisition device that acquires information on targets around a vehicle, and a control unit configured to execute yaw moment application control for applying a yaw moment to the vehicle to suppress the vehicle from deviating from a lane when it is determined based on the target information acquired by the target information acquisition device that the vehicle may deviate from the lane, the control unit is configured such that when it is determined that the vehicle is traveling on a road without a center line and may deviate from the lane in the off-road direction, the yaw moment is reduced as compared with when it is determined that the vehicle is traveling on a road with a center line and may deviate from the lane in the off-road direction. A lane departure suppression device.

2. In the lane departure suppression device according to claim 1, the control unit is configured to determine that the road is a road without a center line when it is determined that the target information acquisition device has acquired only information on the lane line on the side where the vehicle may deviate as a lane line of the road within a predetermined range from the vehicle. A lane departure suppression device.

3. In the lane departure suppression device according to claim 1, the control unit is configured to determine that the road is a road without a center line when it is determined that the target information acquisition device has acquired information on the lane lines on both sides of the vehicle as lane lines of the road within a predetermined range from the vehicle and the interval between the lane lines on both sides is equal to or greater than a reference interval. A lane departure suppression device.

4. In the lane departure suppression device according to claim 1, the control unit is configured to gradually reduce the yaw moment applied to the vehicle after a predetermined time has elapsed since the start of the yaw moment application control. A lane departure suppression device.

5. A lane departure suppression method including a step of determining whether or not the vehicle may deviate from the lane based on information on targets around the vehicle acquired by a target information acquisition device, and a step of executing yaw moment application control for applying a yaw moment to the vehicle to suppress the vehicle from deviating from the lane when it is determined that the vehicle may deviate from the lane. A step of determining whether the vehicle is traveling on a road without a center line, and when it is determined that the vehicle is traveling on a road without a center line and there is a risk of deviating from the lane in the off-road direction, reducing the yaw moment compared to when it is determined that the vehicle is traveling on a road with a center line and there is a risk of deviating from the lane in the off-road direction. A lane departure suppression method further including the step of

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