Lane Departure Prevention Device

Abstract

To provide a lane deviation prevention device for reducing the risk of feeling inconvenience in lane deviation prevention control when lane deviation is performed by driving based on a driver's intention.SOLUTION: A lane deviation prevention device performs lane deviation prevention control when a vehicle has the risk of deviating from a lane, but does not perform the lane deviation prevention control when an index value indicating the strength of a lane deviation intention in a driver is equal to or more than a reference value regardless of the risk that the vehicle may deviate from the lane. When an obstacle is not detected ahead of a travel direction of the vehicle and also a visual line direction of the driver is the same as a direction in which the vehicle may deviate from the lane (S160), and when the obstacle is detected (S120), the reference value is reduced (S180) compared with a case where the obstacle is not detected and also when the visual line direction of the driver is not the same as the direction in which the vehicle may deviate from the lane (S130).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a lane departure prevention device for a vehicle such as an automobile. [Background technology]

[0002] The lane departure prevention device detects the vehicle's position relative to the lane using a vehicle position detection device, and when it determines that there is a risk of the vehicle deviating from the lane based on the detected vehicle position, it executes lane departure prevention control, such as at least one of automatic steering of the steered wheels and issuing an alarm.

[0003] When the driver's line of sight is deviated from the front of the vehicle's traveling direction as if the driver is looking aside, there is a risk that the driver will not recognize the situation ahead of the vehicle's traveling direction. Therefore, when the driver's line of sight is deviated from the front of the vehicle's traveling direction, it is preferable that the lane departure prevention performance be improved compared to when the driver's line of sight is not deviated from the front of the vehicle's traveling direction.

[0004] For example, the following Patent Document 1 describes that the higher the degree of driver's line of sight deviation, the higher the threshold value for determining whether to stop the lane departure prevention control, making it more difficult to stop the lane departure prevention control. This type of lane departure prevention device can expand the lane departure prevention range and speed up the timing of issuing an alarm. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-222055 A Summary of the Invention

[0006] [Problem to be solved by the invention] However, when the driver intends to depart from the lane, the degree of the driver's gaze deflection increases. For example, when changing lanes or avoiding obstacles, the driver turns his or her gaze in a direction other than the forward direction of the vehicle in order to check for safety, which may increase the degree of gaze deflection.

[0007] However, in conventional lane departure prevention devices such as the lane departure prevention device described in Patent Document 1, lane departure prevention control is executed even in a situation where the degree of line of sight deviation increases due to driving based on the driver's intention. Therefore, the driver may feel bothered by the lane departure prevention control.

[0008] The main objective of the present invention is to provide an improved lane departure prevention device that makes it difficult for lane departure prevention control to be executed when the driver departs from the lane due to driving based on the driver's intention, thereby reducing the risk that the driver will find the lane departure prevention control annoying. [Means for solving the problems and effects of the invention]

[0009] According to the present invention, when it is determined that the vehicle (50) is likely to deviate from the lane (S20) based on the vehicle position detection device (exterior camera sensor 11) that detects the position of the vehicle relative to the lane (54) and the position of the vehicle detected by the vehicle position detection device, at least one of lane departure prevention control is executed (S60), which includes automatic steering of the steered wheels (24) and issuing of an alarm. , based on the driver's steering operation The index value showing the strength of the driver's intention to depart the lane is Index value and a control unit (LDA·ECU10) configured not to execute lane departure prevention control when the detected deviation is equal to or greater than the reference value (S40).

[0010] The lane departure prevention device (100) further includes an obstacle detection device (exterior camera sensor 11, radar sensor 12) that detects obstacles present ahead of the vehicle in the traveling direction, and a gaze detection device (interior camera sensor 13) that detects the direction of the driver's gaze. A device for determining the driver's level of alertness (in-vehicle camera sensor 13); The control unit (LDA·ECU10) includes: The driver's level of alertness is equal to or higher than the alertness reference value (S110) and No obstacles are detected by the obstacle detection device (S120) And the direction of the driver's line of sight detected by the line of sight detection device is the same as the direction in which the vehicle is likely to deviate from the lane (S160); and The driver's level of alertness is equal to or exceeds the alertness standard value, and If an obstacle is detected by the obstacle detection device (S120), The driver's level of alertness is equal to or exceeds the alertness standard value, and Compared with a case where no obstacle is detected by the obstacle detection device and the direction of the driver's line of sight detected by the line of sight detection device is not the same as the direction in which the vehicle is likely to deviate from the lane, Index value Reduce the reference value (S180) Further, when the driver's wakefulness is less than the wakefulness reference value (S110), the control unit (LDA·ECU10) executes lane departure prevention control regardless of whether the index value is equal to or greater than the index value reference value (S150, S30, S60). It is configured as follows.

[0011] According to the above configuration, The driver's level of alertness is equal to or exceeds the alertness standard value, and When no obstacle is detected and the driver's line of sight is in the same direction as the vehicle is likely to deviate from its lane, and The driver's level of alertness is equal to or exceeds the alertness standard value, and If an obstacle is detected, The driver's level of alertness is equal to or exceeds the alertness standard value, and Compared with a case where an obstacle is not detected and the direction of the driver's gaze is not the same as the direction in which the vehicle is likely to deviate from the lane, Index value The reference value is reduced. Therefore, the index value showing the strength of the driver's intention to depart the lane is Index value Since it becomes easier to determine that the vehicle speed is equal to or greater than the reference value and the lane departure prevention control becomes harder to execute, it is possible to reduce the possibility that the driver will feel annoyed by the lane departure prevention control. In a situation where the driver's alertness is below the alertness reference value, it is possible to reduce the risk of the index value reference value being reduced and of lane departure prevention control not being executed as a result. Furthermore, according to the above configuration, when the driver's alertness is less than the alertness reference value, the lane departure prevention control is executed regardless of whether the index value is equal to or greater than the index value reference value. Therefore, even if the driver's alertness decreases and the vehicle is more likely to deviate from the lane, the lane departure prevention control can prevent the vehicle from deviating from the lane.

[0012] In the above description, in order to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are added in parentheses to the configurations of the invention corresponding to those 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. [Brief description of the drawings]

[0013] [Figure 1] 1 is a schematic diagram showing an embodiment of a lane departure prevention device according to the present invention; [Diagram 2] 4 is a flowchart showing a lane departure prevention control routine in the embodiment. [Diagram 3] 4 is a flowchart showing a reference value control routine in the embodiment. [Figure 4] FIG. 1 is a diagram showing a situation in which a vehicle is traveling at an angle relative to the longitudinal direction of a lane. [Diagram 5] 2 is a map for calculating a standard value Tscn and a reduced value Tscr of the reference value Tsc of the steering torque Ts based on the vehicle speed V. [Figure 6] 11 is a map for calculating a standard value θscn and a reduced value θscr of a reference value θsc of a steering angle θ based on a vehicle speed V. [Figure 7] 11 is a map for calculating a reference value Tc for an elapsed time based on a vehicle speed V. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A lane departure prevention device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0015] <Configuration> 1, a lane departure prevention device 100 according to an embodiment is applied to a vehicle 50, and includes a lane departure prevention ECU 10, an electric power steering ECU 20, and a steering ECU 40. In this specification, lane departure prevention is referred to as LDA (abbreviation of Lane Departure Alert with Control) as necessary, and electric power steering is referred to as EPS (abbreviation of Electric Power Steering) as necessary.

[0016] These ECUs 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 transmit and receive information to each other. Each microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, an interface, and the like. The CPU is adapted to realize various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into one ECU.

[0017] As will be described in detail later, the ROM of the LDA·ECU 10 stores a program for lane departure prevention control corresponding to the flowchart shown in Fig. 2, and the CPU executes lane departure prevention control according to the program. Also, the ROM of the LDA·ECU 10 stores a program for reference value control corresponding to the flowchart shown in Fig. 3, and the CPU executes reference value control according to the program.

[0018] To the LDA·ECU 10, an exterior camera sensor 11, a radar sensor 12, an interior camera sensor 13, a vehicle speed sensor 14, an LDA switch 15, and an alarm device 16 are connected.

[0019] The exterior camera sensor 11 includes a camera unit and a recognition unit that recognizes white lines and obstacles on the road by analyzing image data captured by the camera unit. The camera sensor 11 (camera unit) captures images of the scenery ahead of the vehicle 50. The camera sensor 11 (recognition unit) repeatedly supplies information about the recognized white lines and obstacles to the LDA·ECU 10 at every predetermined calculation period.

[0020] As shown in Fig. 4, the camera sensor 11 is capable of recognizing white lines 56L and 56R, which are boundaries of a lane 54 (called lane boundaries), and detecting the relative positional relationship 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 center 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 of the vehicle in the lane width direction, and the lateral speed of the vehicle refers to the speed of the center of gravity of the vehicle in the lane width direction. These are found based on the relative positional relationship between the white lines detected by the camera sensor 11 and the vehicle.

[0021] The radar sensor 12 includes a radar transmitting / receiving unit and a signal processing unit (not shown), and the radar transmitting / receiving unit emits millimeter-wave band radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (e.g., other vehicles, bicycles, guardrails, roadside structures, etc.) within the emission range. The signal processing unit acquires information (hereinafter referred to as peripheral 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., based on the phase difference between the transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from transmitting the millimeter waves to receiving the reflected waves, and supplies the information to the LDA·ECU 10 at predetermined time intervals.

[0022] The in-vehicle camera sensor 13 is installed in front of the driver's seat and captures the face of the driver. A plurality of camera sensors 13 may be provided so as to capture the driver from a plurality of directions. The vehicle includes a camera unit and a determination unit that determines the degree of eye opening, the direction of gaze, the speed of blinking, etc. of the driver by recognition processing of the face image captured by the camera unit. The image recognition processing may be a known pattern recognition method such as a neural network or a support vector machine. In this embodiment, the determination unit determines that the driver's level of awakening is higher as the degree of eye opening of the driver increases, the speed of movement in the direction of gaze increases, and the blinking speed increases.

[0023] The vehicle speed sensor 14 detects the vehicle speed V of the vehicle 50, and repeatedly supplies a signal indicating the vehicle speed V to the LDA·ECU 10 at a predetermined control period. The LDA switch 15 is operated by the driver, and supplies a signal indicating whether it is on or off to the LDA·ECU 10. The fact that the LDA switch 15 is on means that lane departure prevention control is being executed.

[0024] The warning device 16 is activated when the LDA·ECU 10 determines that the vehicle 50 is at risk of deviating from the lane 54, and issues a warning as one of the lane departure prevention controls, i.e., issues a warning that the vehicle 50 is at risk of deviating from the lane. The warning device 16 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 tactile warning such as seat vibration, or any combination thereof.

[0025] 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 LDA·ECU 10 determines that the vehicle 50 is at risk of deviating from its lane, the EPS·ECU 20 performs automatic steering of the steered wheels 24 to prevent the vehicle from deviating from its lane, as another type of lane departure prevention control.

[0026] 1, a steering shaft 30 to which a steering wheel 28 operated by a driver is integrally connected is provided with a torque sensor 32 for detecting a steering torque Ts and a steering angle sensor 34 for detecting a steering angle θ. A signal indicative of the steering torque Ts detected by the torque sensor 32 and a signal indicative of the steering angle θ detected by the steering angle sensor 34 are input to the EPS·ECU 20.

[0027] The EPS·ECU 22 controls the steering assist torque and reduces the steering burden on the driver by controlling the EPS device 22 in a manner known in the art based on the steering torque Ts and the vehicle speed V detected by the vehicle speed sensor 14. A signal indicating the steering torque Ts is input from the EPS·ECU 20 to the LDA·ECU 10 via the CAN 52.

[0028] The steering ECU 40 is connected to a turn signal lever 42 and turn signal lamps 44L, 44R operated by the driver. When the turn signal lever 42 is tilted in the left turn direction of the vehicle 50, the steering ECU 40 causes the front and rear turn signal lamps 44L on the left side of the vehicle 50 to flash, and when the turn signal lever 42 is tilted in the right turn direction of the vehicle 50, the steering ECU 40 causes the front and rear turn signal lamps 44R on the right side of the vehicle 50 to flash. Tilt information of the turn signal lever 42 is input from the steering ECU 40 to the LDA·ECU 10 via the CAN 52.

[0029] <Lane Departure Prevention Control Routine> Next, a lane departure prevention control routine in this embodiment will be described with reference to the flowchart shown in Fig. 2. The lane departure prevention control according to the flowchart shown in Fig. 2 is repeatedly executed by the CPU of the LDA·ECU 10 at a predetermined control period when the LDA switch 15 is on. In the following description, the lane departure prevention control will simply be referred to as "control".

[0030] First, in step S10, the CPU determines whether or not the flag Foff is 1, that is, whether or not the lane departure prevention control is not being executed. If the CPU makes a negative determination, the control proceeds to step S70, and if the CPU makes a positive determination, the control proceeds to step S20. The flag Foff is initialized to 0 at the start of the control, and is thereafter set to 0 or 1 according to the flowchart shown in FIG. 2, as described later.

[0031] In step S20, the CPU determines whether or not there is a risk that the vehicle will deviate from the lane in a manner known in the art, based on the relative position of the vehicle 50 with respect to the lane 54 detected by the exterior camera sensor 11. If the CPU determines that the vehicle is likely to deviate from the lane, it temporarily terminates control, and if the CPU determines that the vehicle is likely to deviate from the lane, it advances control to step S30.

[0032] In this case, the determination as to whether or not there is a risk that the vehicle 50 will deviate from the lane may be performed, for example, in the following manner. First, as shown in Fig. 4, an angle (inclination angle) θy between the longitudinal direction 60 of the lane 54 and the traveling direction 62 of the vehicle is estimated based on image information of the front of the vehicle 50. A 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. Note that the angle θy is the same as the inclination angle with respect to the white lines 56L and 56R, and is therefore also the skew angle of the vehicle 50.

[0033] Also, a distance Dy (not shown) in the lane width direction between the white line 56L (first lane boundary) on the side where the vehicle 50 is approaching and the center of gravity 50A 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.

[0034] In step S30, it is determined whether or not the flag Fns is 1, that is, whether or not the stop of the lane departure prevention control is disabled. If the CPU makes a positive determination, the control proceeds to step S50, and if the CPU makes a negative determination, the control proceeds to step S40. The flag Fns is initialized to 0 at the start of the control, and is thereafter set to 0 or 1 according to the flowchart shown in FIG. 3, which will be described later.

[0035] In step S40, the CPU determines whether or not the driver intends to depart from the lane. If the CPU determines that the driver intends to depart from the lane, the CPU temporarily ends the control according to the flowchart shown in Fig. 2. If the CPU determines that the driver intends to depart from the lane, the CPU resets the flag Foff to 0 in step S50.

[0036] In this case, the CPU determines that the driver intends to depart from the lane beyond the lane boundary when the driver tilts the turn signal lever 42 in the lane departure direction or steers the vehicle in the lane departure direction. The steering operation may be determined based on whether the magnitude of the steering torque Ts detected by the torque sensor 32 is equal to or greater than a reference value Tsc or whether the magnitude of the steering angle θ is equal to or greater than a reference value θsc. The magnitude of the steering torque Ts and the magnitude of the steering angle θ are index values ​​that indicate the strength of the driver's intention to depart from the lane, and the reference values ​​Tsc and θsc are index value reference values ​​for determining the strength of the driver's intention to depart from the lane. The reference values ​​Tsc and θsc are switched between standard values ​​Tscn and θscn and reduced values ​​Tscr and θscr smaller than the standard values, respectively, by reference value control according to the flowchart shown in FIG. 3, as will be described later.

[0037] The reference values ​​Tscn and Tscr may be positive constants, but the steering resistance when the steered wheels are turned by the driver's steering operation becomes smaller as the vehicle speed V increases. Therefore, as shown in Fig. 5, the reference values ​​Tscn and Tscr are variably set according to the vehicle speed so as to become smaller as the vehicle speed V increases. Therefore, it is possible to properly determine whether the driver intends to depart from the lane and cross the lane boundary, compared to a case in which the reference values ​​Tscn and Tscr are constant regardless of the vehicle speed.

[0038] Furthermore, for example, when the vehicle 50 is subjected to a lateral force due to a crosswind or a lateral inclination of the road surface, or when the vehicle 50 unnecessarily skews with respect to the lane 54 due to driver inattention or the like, and there is a risk that the vehicle 50 will deviate from the lane 54, the magnitude of the skew angle θy of the vehicle 50 is small. In contrast, when the driver intends to deviate from the lane, the magnitude of the skew angle θy of the vehicle 50 is large. Therefore, even when the magnitude of the skew angle θy of the vehicle 50 is equal to or greater than the reference angle θyc (a positive constant), the CPU determines that the driver intends to deviate from the lane by crossing the lane boundary.

[0039] Note that the reference values ​​θscn and θscr may be positive constants, but the steering amount when changing the moving direction of the vehicle becomes smaller as the vehicle speed V increases. Therefore, as shown in Fig. 6, the reference values ​​θscn and θscr are variably set according to the vehicle speed so as to become smaller as the vehicle speed V increases. Therefore, it is possible to properly determine whether the driver intends to depart from the lane and cross the lane boundary, compared to a case where the reference values ​​θscn and θscr are constant regardless of the vehicle speed.

[0040] In step S60, the CPU executes lane departure prevention control. That is, the CPU activates the warning device 16 to issue a warning that the vehicle 50 is at risk of 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 deviate from the lane.

[0041] In step S70, the CPU calculates a reference value Tc for the elapsed time by referring to the map shown in Fig. 7 based on the vehicle speed V. As shown in Fig. 7, the reference value Tc is variably set according to the vehicle speed so that the higher the vehicle speed V, the shorter the reference value Tc is.

[0042] In step S80, the CPU determines whether the driver has released the intention to depart from the lane. If the CPU determines yes, the control proceeds to step S100, and if the CPU determines no, the control proceeds to step S90. The CPU determines that the driver has released the intention to depart from the lane when the driver returns the turn signal lever 42 to the non-tilted position (neutral position) or when the driver performs a steering operation to release the lane change.

[0043] In step S90, the CPU determines whether or not the lane departure prevention control return condition is satisfied. If the CPU determines that the lane departure prevention control is not satisfied, the CPU returns the control to step S60. If the CPU determines that the lane departure prevention control is satisfied, the CPU returns the control to step S60. If the CPU determines that the lane departure prevention control is satisfied, the CPU sets the flag Foff to 1 in step S100.

[0044] In this case, the CPU determines that the control recovery condition is met at the earlier of the following points in time A and B. Time point A: The time point when the determination in step S40 changes from a negative determination to a positive determination, that is, when it is determined that a time equal to or longer than the reference time Tc has elapsed since the time point when the driver's intention to depart the lane changes from "no" to "yes." Time point B: When it is determined that the vehicle 50 has crossed the lane boundary and completed the lane change, that is, when it is determined that the entire vehicle 50 has moved into the lane to which the lane change is to be made, based on the relative positional relationship between the vehicle 50 and the white line.

[0045] <Reference value control routine> Next, a reference value control routine in the embodiment will be described with reference to the flowchart shown in Fig. 3. The reference value control according to the flowchart shown in Fig. 3 is repeatedly executed by the CPU of the LDA·ECU 10 at a predetermined control period when the LDA switch 15 is on.

[0046] First, in step S110, the CPU determines whether the driver's wakefulness level is determined by the in-vehicle camera 13. Arousal level The CPU judges whether the detected value is equal to or greater than the reference value, that is, judges whether the driver is awake or not. If the CPU judges negative, the CPU advances the reference value control to step S140, and if the CPU judges positive, the CPU advances the reference value control to step S120.

[0047] In step S120, the CPU determines whether or not an obstacle such as a stopped vehicle has been detected ahead in the traveling direction of the vehicle 50 by the exterior image capturing camera sensor 11 and / or the radar sensor 12. If the CPU makes a positive determination, it advances the reference value control to step S180, and if the CPU makes a negative determination, it advances the reference value control to step S130.

[0048] In step S130, the CPU determines whether or not the direction of the driver's line of sight determined by the in-vehicle camera 13 is opposite to the direction in which there is a risk of lane departure of the vehicle 50. If the CPU makes a negative determination, it advances the reference value control to step S160, and if the CPU makes a positive determination, it advances the reference value control to step S140.

[0049] In step S140, the CPU refers to the map shown in FIG. 5 based on the vehicle speed V, The index value is the reference value. The reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to standard values ​​Tscn and θscn, respectively.

[0050] In step S150, the CPU sets the flag Fns to 1. That is, the CPU disables the stopping of the lane departure prevention control so that the lane departure prevention control is not stopped.

[0051] In step S160, the CPU determines whether or not the direction of the driver's line of sight determined by the in-vehicle camera 13 is the same as the direction in which there is a risk of the vehicle 50 deviating from the lane. If the CPU makes a positive determination, it advances the reference value control to step S180, and if the CPU makes a negative determination, for example, if it determines that the direction of the driver's line of sight is the traveling direction of the vehicle 50, it advances the reference value control to step S170.

[0052] In step S140, the CPU refers to the map shown in FIG. 5 based on the vehicle speed V, The index value is the reference value. The reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to standard values ​​Tscn and θscn, respectively.

[0053] In step S180, similarly to step S140, the CPU refers to the maps shown in FIGS. 5 and 6 based on the vehicle speed V, thereby The index value is the reference value. The reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to reduced values ​​Tscr and θscr, respectively.

[0054] In step S190, the CPU resets the flag Fns to 0. That is, the CPU allows the stop of the lane departure prevention control.

[0055] <Operation of the Embodiment> As described above, when there is a risk that the vehicle may deviate from the lane and the driver has no intention of lane departure, in steps S20 and S40, a positive determination and a negative determination are respectively made, and in step S60, the lane departure prevention control is executed.

[0056] In the determination as to whether the driver has an intention of lane departure in step S40, a determination as to whether the magnitude of the steering torque Ts is equal to or greater than the reference value Tsc and a determination as to whether the magnitude of the steering angle θ is equal to or greater than the reference value θsc are made. The reference values Tsc and θsc are variably set according to the situation as follows by the reference value control according to the flowchart shown in FIG. 3.

[0057] <C1. When no obstacle is detected and the driver's line of sight is neither in the same direction nor in the opposite direction as the direction in which the vehicle may deviate from the lane> In steps S120, S130, and S160, a negative determination is made. Therefore, in step S170, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are respectively set to the standard values Tscn and θscn.

[0058] <C2. When no obstacle is detected and the driver's line of sight is in the opposite direction to the direction in which the vehicle may deviate from the lane> In step S120, a negative determination is made, and in step S130, a positive determination is made. Therefore, in step S140, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are respectively set to the standard values Tscn and θscn.

[0059] <C3. When no obstacle is detected and the driver's line of sight is in the same direction as the direction in which the vehicle may deviate from the lane> In steps S120 and S130, a negative determination is made, and in step S160, an affirmative determination is made. Therefore, in step S180, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to the reduced values Tscr and θscr, respectively.

[0060] <When an obstacle is detected> In step S120, an affirmative determination is made. Therefore, similar to the case of C3, in step S180, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to the reduced values Tscr and θscr, respectively.

[0061] <When the driver is not awake> In step S110, a negative determination is made. Therefore, in step S140, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to the standard values Tscn and θscn, respectively.

[0062] Note that in the cases of C1, C3, and C4 above, in step S190, the flag Fns is reset to 0, so the stop of the lane departure prevention control is allowed. On the other hand, in the cases of C2 and C5 above, in step S150, the flag Fns is set to 1 In step S30, a positive determination is made. so that the stop of the lane departure prevention control is invalidated so that the lane departure prevention control is not stopped In step S60, lane departure prevention control is executed. is.

[0063] As can be understood from the above description, in the cases of C3 and C4 above, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to the reduced values Tscr and θscr, respectively. Therefore, in step S40, an affirmative determination is more likely to be made, so it becomes difficult to execute the lane departure prevention control. Therefore, compared with the case where the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are not set to the reduced values Tscr and θscr, respectively, it is possible to reduce the risk that the driver feels annoyance due to the execution of the lane departure prevention control.

[0064] Although the present invention has been described in detail above with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the above-described embodiments, and that various other embodiments are possible within the scope of the present invention.

[0065] For example, in the above-described embodiment, lane departure prevention control involves issuance of a warning by activation of the warning device 16 and automatic steering of the steered wheels 24 by the EPS device 22. However, one of the issuance of a warning and the automatic steering of the steered wheels 24 may be omitted.

[0066] In the above embodiment, when positive determinations are made in steps S130 and S160, the reference value control proceeds to steps S140 and S180, respectively. However, the reference value control may be modified so that when positive determinations are made a predetermined number of times consecutively in steps S130 and S160, the reference value control proceeds to steps S140 and S180, respectively.

[0067] In the above embodiment, when the positive determination is made in step S120 and step S160, the reference value Tsc of the steering torque Ts and the reference value θsc of the steering angle θ are set to the reduction values ​​Tscr and θscr, respectively, in step S180. However, the likelihood of the positive determination in step S120 and step S160 may be determined, and the reduction amount of the reference value may be variably set according to the likelihood of the positive determination so that the higher the likelihood, the greater the reduction amount of the reference value.

[0068] In the above-described embodiment, the reference value Tsc for the steering torque Ts, the reference value θsc for the steering angle θ, and the reference value Tc for the elapsed time are variably set according to the vehicle speed, as shown in Fig. 5 to Fig. 7. However, at least one of the reference values ​​Tsc, θsc, and Tc may be constant regardless of the vehicle speed V. [Explanation of symbols]

[0070] 10...Lane departure prevention ECU (LDA·ECU), 11...Exterior camera sensor, 12...Radar sensor, 13...Interior camera sensor, 14...Vehicle speed sensor, 16...Warning device, 20...Electric power steering ECU (EPS·ECU), 22...EPS device, 24...Steering wheel, 28...Steering wheel, 32...Torque sensor, 34...Steering angle sensor, 40...Steering ECU, 42...Blinker lever, 44L, 44R...Blinker lamp, 50...Vehicle, 54...Lane, 56L, 56R...White line, 100...Lane departure prevention device

Claims

[Claim 1] a vehicle position detection device that detects a position of a vehicle relative to a lane; and a control unit that, when it is determined that the vehicle is at risk of deviating from the lane based on the position of the vehicle detected by the vehicle position detection device, executes lane departure prevention control of at least one of automatic steering of steered wheels and issuing of an alarm, and, even if it is determined that the vehicle is at risk of deviating from the lane, does not execute the lane departure prevention control when an index value that is calculated based on the driver's steering operation and indicates the strength of the driver's intention to deviate from the lane is equal to or greater than a reference index value, The lane departure prevention system further includes an obstacle detection device that detects an obstacle present ahead in a traveling direction of the vehicle, a gaze detection device that detects a direction of the driver's gaze, and a device that determines a level of alertness of the driver, the control unit is configured to reduce the index value reference value when the driver's alertness is equal to or greater than the alertness reference value, no obstacle is detected by the obstacle detection device, and the direction of the driver's gaze detected by the gaze detection device is the same as a direction in which the vehicle may deviate from a lane, and when the driver's alertness is equal to or greater than the alertness reference value and an obstacle is detected by the obstacle detection device, compared to when the driver's alertness is equal to or greater than the alertness reference value, no obstacle is detected by the obstacle detection device, and the direction of the driver's gaze detected by the gaze detection device is not the same as a direction in which the vehicle may deviate from a lane, Furthermore, the control unit is configured to execute the lane departure prevention control when the driver's alertness is less than the alertness reference value, regardless of whether the index value is greater than or equal to the index value reference value.

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