Lane deviation suppression device, lane deviation suppression method and lane deviation suppression program

Abstract

To provide a lane deviation suppression device capable of suppressing an own vehicle from re-deviating from a traffic lane under an influence of a travel environment immediately after completion of control for suppressing deviation of the own vehicle from the traffic lane.SOLUTION: A processor of a lane deviation suppression device starts a lane deviation suppression process to control an own vehicle to suppress lane deviation when a first condition, for determining that the own vehicle is highly likely to deviate outward from a lane L1, is met based on information acquired from an on-vehicle sensor. Then, when a predetermined second condition is met, the processor ends execution of the lane deviation suppression process. The processor sets the second condition based on information related to a travel environment to suppress the own vehicle from re-deviating from the traffic lane under an influence of the travel environment within a predetermined period after completion of the lane deviation suppression process with the own vehicle traveling toward a central portion in a width direction of the traffic lane as a result of the execution of the lane deviation suppression process.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a lane departure prevention device, a lane departure prevention method, and a lane departure prevention program that prevent a vehicle from departing from a lane in which the vehicle is traveling. [Background technology]

[0002] A lane departure prevention device has been proposed that prevents a vehicle from departing from the lane it is traveling in (see, for example, Patent Document 1 below). The processor of the lane departure prevention device of Patent Document 1 (hereinafter referred to as the "conventional device") executes lane departure prevention processing that controls the vehicle (drive devices and / or braking devices of each wheel) so that the vehicle returns to the original lane when the vehicle enters the shoulder of the road from the lane it is traveling in (when the vehicle deviates from the lane). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-210412 Summary of the Invention

[0004] As described above, when the processor of the conventional device executes the lane departure prevention process, the host vehicle moves toward the center of the original lane width. Here, for example, in a situation where the lane width is relatively narrow, if the lane departure prevention process is terminated while the host vehicle is moving from the left edge of the lane toward the center, there is a risk that the host vehicle will deviate again from the right edge of the lane (the edge opposite to the previous lane). Furthermore, there is a risk that the host vehicle will deviate again from the lane due to influences of lane cant or crosswinds immediately after the lane departure prevention process is terminated. Thus, there is a possibility that the host vehicle will deviate again from the lane due to influences of the vehicle's driving environment immediately (within a short period of time) after the processor terminates the lane departure prevention process. Conventional devices are not provided with a means for suppressing such re-departure.

[0005] One of the objects of the present invention is to provide a lane departure prevention device that can prevent the vehicle from re-departing from the lane due to the influence of the driving environment immediately after control to prevent the vehicle from deviating from the lane has been completed.

[0006] In order to solve the above problems, the lane departure prevention device (1) of the present invention comprises: an on-board sensor (20) for acquiring information about the driving environment (W, C) of the host vehicle (V), as well as information about the lateral position and lateral speed of the host vehicle in the lane (L1) in which the host vehicle is traveling; a processor (10) configured to, when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on information acquired from the on-board sensor is satisfied, start a lane departure prevention process (P1, P2) for controlling the host vehicle so as to prevent the host vehicle from deviating from the lane, and thereafter, when a predetermined second condition is satisfied, terminate execution of the lane departure prevention process; Equipped with. The processor: setting the second condition based on information about the running environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the running environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process; It is configured as follows.

[0007] The vehicle control method of the present invention further includes an information acquisition step of acquiring information about a driving environment of the host vehicle, and information about a lateral position and a lateral speed of the host vehicle in a lane in which the host vehicle is traveling; a vehicle control step configured to start a lane departure prevention process for controlling the host vehicle so as to prevent the host vehicle from departing from the lane when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on the information acquired in the information acquisition step is met, and thereafter, to end the execution of the lane departure prevention process when a predetermined second condition is met; Includes. The vehicle control step includes: and setting the second condition based on information about the driving environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the driving environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process. It is configured as follows.

[0008] In addition, the lane departure prevention program of the present invention is The computer installed in the vehicle an information acquisition step of acquiring information about the driving environment of the host vehicle, and information about the lateral position and lateral speed of the host vehicle in the lane in which the host vehicle is traveling; a vehicle control step configured to start a lane departure prevention process for controlling the host vehicle so as to prevent the host vehicle from departing from the lane when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on the information acquired in the information acquisition step is met, and thereafter, to end the execution of the lane departure prevention process when a predetermined second condition is met; Execute the following. The vehicle control step includes: and setting the second condition based on information about the driving environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the driving environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process. It is configured as follows.

[0009] The processor of the lane departure prevention device according to the present invention executes lane departure prevention processing to prevent the host vehicle from deviating from the lane when there is a high possibility that the host vehicle will deviate from the lane (when the first condition is met). As a result, the host vehicle begins to move toward the center of the lane in the width direction. The processor then terminates the lane departure prevention processing when a predetermined termination condition is met (when the second condition is met). Here, within a predetermined period (short period) after the lane departure prevention processing is terminated, the host vehicle may deviate (re-depart) from one end or the other of the lane due to the influence of the driving environment (e.g., lane width, cant, crosswind, etc.). According to the present invention, the second condition is set according to the driving environment. This prevents the above-mentioned re-departure.

[0010] In one aspect of the present invention, a lane departure prevention device includes: the second condition is established when a lateral speed (vy) of the host vehicle when the host vehicle is heading toward the center of the lane exceeds a predetermined target value (vyd), The information about the driving environment includes information about the width (W) of the lane, The processor assigns a smaller value to the target value as the width of the lane decreases.

[0011] If the lane width is relatively narrow and the host vehicle moves from one end of the lane toward the center and the lane departure prevention process is terminated while the lateral speed is relatively high, there is a high possibility that the host vehicle will deviate from the other end of the lane. According to the lane departure prevention device of this aspect, the target value of the lateral speed (the condition for terminating the lane departure prevention process (second condition)) is set according to the lane width, so that the host vehicle is prevented from deviating from the other end of the lane immediately after the control for suppressing departure of the host vehicle from one end of the lane is terminated.

[0012] In a lane departure prevention device according to another aspect of the present invention, The information about the driving environment includes information about the cant (C) of the lane, The processor: When the one end of the lane is lower than the other end, the greater the difference in elevation, the greater the correction value added to the target value; when the one end of the lane is higher than the other end, the greater the difference in elevation, the greater the value subtracted from the target value.

[0013] When one end (the other end) of a lane is lower than the other end (the other end), the host vehicle is likely to proceed toward the one end (the other end) of the lane due to the influence of gravity (the lateral component of gravitational acceleration) acting laterally due to the inclination. As a result, the host vehicle is likely to deviate from the one end (the other end) of the lane. According to this aspect, the target value of the lateral speed is corrected depending on the magnitude of the cant (height difference), so that the host vehicle is prevented from deviating from the lane due to the cant immediately after the lane departure prevention process is completed. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram of a lane departure suppression device according to one embodiment of the present invention. [Figure 2] FIG. 2 is a plan view showing a situation in which departure of the host vehicle from the left edge of the lane is suppressed. [Figure 3] FIG. 3 is a plan view showing a situation in which the lane departure prevention function prevents the host vehicle from departing from the right edge of the lane. [Figure 4] 4A shows a map M1 that defines the relationship between the lane width W and the target value vyd. FIG. 4B shows a map M2 that defines the relationship between the lane cant C and the correction value vyc. [Figure 5] FIG. 5 is a flowchart of a program executed by the CPU to realize the lane departure prevention function. [Figure 6] FIG. 6 is a flowchart of a program executed by the CPU to correct the target value vyd. DETAILED DESCRIPTION OF THE INVENTION

[0015] (Summary) 1, a lane departure prevention device 1 according to one embodiment of the present invention is applied to a vehicle V (hereinafter referred to as "host vehicle") equipped with an automatic driving function. The lane departure prevention device 1 has a lane departure prevention function that controls the host vehicle (an alarm device 30 and a steering device 40, which will be described later) so as to prevent the host vehicle from departing from the lane in which it is traveling when the automatic driving function is disabled.

[0016] (Specific configuration) As shown in FIG. 1, the lane departure suppression device 1 includes an ECU 10, an on-vehicle sensor 20, a notification device 30, and a steering device 40.

[0017] The ECU 10 comprises a microcomputer including a CPU 10a, a ROM 10b (rewritable non-volatile memory), a RAM 10c, a timer 10d, etc. The CPU realizes various functions by executing programs (instructions) stored in the ROM. The ECU 10 is connected to other ECUs via a CAN (Controller Area Network).

[0018] The on-board sensors 20 include a camera 21, a vehicle speed sensor 22, and an acceleration sensor 23.

[0019] The camera 21 includes an imaging device. The imaging device may have, for example, a built-in CCD. The imaging device is installed at the front of the vehicle and is directed forward. The imaging device captures images of the area ahead of the vehicle at a predetermined frame rate to acquire image data. The camera 21 also includes an image analysis device. The image analysis device acquires image data from the imaging device, analyzes the image data, and recognizes (identifies) objects present within the field of view. The image analysis device recognizes, for example, the lane markings BR and BL of the lane L1 in which the vehicle is traveling. The image analysis device acquires the shape of the lane markings BR and BL (the curvature of the lane L1) and the spacing between the lane markings BR and BL (the width W of the lane L1) as lane marking information. The image analysis device also acquires the lateral position of the vehicle's center of gravity G in the lane L1 (the distance between the center of gravity G and the lane marking BR and the distance between the center of gravity G and the lane marking BL) as position information based on the positions (coordinates) of the lane markings BR and BL within the field of view of the imaging device. The image analysis device provides the ECU 10 with the lane marking information and the position information.

[0020] The vehicle speed sensor 22 acquires the speed vs of the host vehicle (forward speed (absolute value) relative to the lane L1) based on the number of rotations of the wheels per unit time. The vehicle speed sensor 22 then provides the acquired speed vs to the ECU 10.

[0021] The acceleration sensor 23 includes a piezoelectric element. When the host vehicle accelerates (or decelerates) in the longitudinal and lateral directions, the piezoelectric element deforms in the longitudinal and lateral directions of the host vehicle, and the output voltage of the piezoelectric element changes in accordance with the deformation. The acceleration sensor 23 acquires the longitudinal and lateral accelerations of the host vehicle based on the output voltage of the piezoelectric element. The acceleration sensor 23 then provides these accelerations to the ECU 10. When the host vehicle is stationary or traveling straight at a constant speed, the output (acceleration information) of the acceleration sensor 23 indicates gravitational acceleration. That is, the inclination angle (gradient) of the road surface can be calculated based on the output of the acceleration sensor 23. When the host vehicle is accelerating (decelerating) or turning, the inclination angle (gradient) of the road surface can be calculated based on acceleration information obtained by removing the influence of the host vehicle's behavior on the output of the acceleration sensor 23.

[0022] The notification device 30 includes an image display device and an audio device. The image display device is disposed, for example, on an instrument panel (near the speed display device). The image display device displays an image in accordance with a command received from the ECU 10. The audio device reproduces sound in accordance with a command received from the ECU 10.

[0023] The steering device 40 adjusts the steering angle of the steered wheels (left front wheel and right front wheel). The steering device 40 includes a steering ECU and a steering mechanism. The steering device 40 also includes an actuator (e.g., an electric motor) that drives the steering mechanism to change the steering angle, and a steering angle sensor that acquires the steering angle φ (actual steering angle) of the steered wheels. The ECU 10 determines a target value φd of the steering angle φ (actual steering angle) of the steered wheels based on various information acquired from the on-board sensor 20. Note that the steering angle φ when the host vehicle is traveling straight is "0 (deg)." The steering angle φ when the host vehicle is turning right is positive (>0), and the steering angle φ when the host vehicle is turning left is negative (<0). For example, the ECU 10 increases the target value φd when the steering wheel is turned right, and decreases the target value φd when the steering wheel is turned left. Furthermore, when there is a high possibility that the host vehicle will deviate from the lane L1, the ECU 10 determines the target value φd so that the host vehicle will move toward the center in the width direction of the lane L1. The steering ECU acquires the target value φd from the ECU 10 and controls the actuator so that the steering angle φ output from the steering angle sensor coincides with the target value φd.

[0024] (Activated) As will be described below, the ECU 10 executes lane departure prevention processing (hereinafter referred to as "LDA processing") when there is a high possibility that the host vehicle will deviate from the lane L1.

[0025] (LDA processing) When the ignition switch is on, the ECU 10 sequentially acquires various pieces of information from the on-board sensor 20 at a predetermined cycle. Specifically, the ECU 10 acquires lane marking information and position information from the camera 21 (image analysis device). The ECU 10 also acquires the speed vs from the vehicle speed sensor 22. The ECU 10 also acquires the steering angle φ (actual steering angle) from the steering ECU. Based on this information, the ECU 10 calculates a predicted trajectory PT of the host vehicle in the lane L1 (for example, the trajectory of the center of gravity G of the host vehicle or the periphery of the host vehicle) and acquires a point X where the predicted trajectory PT intersects with the lane marking BR or the lane marking BL. The ECU 10 calculates the time ΔT until the center of gravity G (or the periphery of the host vehicle) reaches (intersects with) the point X. In this embodiment, if the time ΔT is equal to or less than a threshold ΔTth, it is determined that there is a high possibility that the host vehicle will deviate from the lane L1. When the time ΔT is equal to or less than the threshold value ΔTth (when the start condition for the LDA processing (first condition of the present invention) is met), the ECU 10 executes the following warning processing P1 and automatic steering processing P2 as the LDA processing.

[0026] (Alarm processing P1) The ECU 10 transmits a predetermined warning command to the notification device 30 to notify the driver that there is a high possibility that the vehicle will deviate from the lane L1. The image display device of the notification device 30 displays an image (icon) corresponding to the warning command. The audio device of the notification device 30 reproduces a sound (beep) corresponding to the warning command.

[0027] (Automatic steering process P2) The ECU 10 transmits to the ECU 10 a steering command (target value of the steering angle) according to the direction of the predicted trajectory PT relative to the lane L1. Specifically, when the predicted trajectory PT intersects with the lane marking BL (first situation (FIG. 2)), the ECU 10 sets the target value φd so that the host vehicle turns right (so that the steering angle φ increases), and transmits this to the steering ECU. On the other hand, when the predicted trajectory PT intersects with the lane marking BR (second situation (FIG. 3)), the ECU 10 sets the target value φd so that the host vehicle turns left (so that the steering angle φ decreases), and transmits this to the steering ECU.

[0028] These target values φd are, for example, predetermined fixed values. Alternatively, for example, in the first situation, a value obtained by adding a predetermined value α (deg) to the current target value φd may be adopted as the new target value φd, and in the second situation, a value obtained by subtracting the predetermined value α (deg) from the current target value φd may be adopted as the new target value φd.

[0029] Alternatively, a value according to the time ΔT may be assigned to the target value φd. For example, a map defining the relationship between the time ΔT and the target value φd is stored in the ROM 10b, and the ECU 10 determines the target value φd by referring to the map. In the first situation, the target value φd corresponding to the time ΔT1 is "α1 (deg)", and the target value φd corresponding to the time ΔT2 longer than the time ΔT1 is "+α2 (deg)" which is smaller than "+α1 (deg)". In the second situation, the target value φd corresponding to the time ΔT1 is "-α1 (deg)", and the target value φd corresponding to the time ΔT2 longer than the time ΔT1 is "-α2 (deg)" which is larger than "-α1 (deg)".

[0030] Also, for example, a value corresponding to the angle β between a tangent to the forecasted trajectory PT at point X where the forecasted trajectory PT intersects with the lane marking BL (BR) and a tangent to the lane marking BL (BR) at point X may be assigned to the target value φd. In this case, in the first situation, the larger the absolute value of the angle β, the larger the value (>0) assigned to the target value φd. Also, in the second situation, the larger the absolute value of the angle β, the smaller the value (<0) assigned to the target value φd.

[0031] When there is a high possibility that the host vehicle will depart from lane L1, the LDA processing (alarm processing P1 and automatic steering processing P2) is executed, causing the host vehicle to start moving toward the center of lane L1 in the width direction. In other words, the component of the host vehicle's velocity vector vt that moves toward the center of lane L1 in the width direction (lateral velocity vy) starts to increase. ECU 10 terminates execution of the LDA processing when a predetermined termination condition (second condition of the present invention) is met. In this embodiment, the termination condition is deemed to be met when the lateral velocity vy reaches a target value vyd described below.

[0032] When the LDA process starts, the ECU 10 acquires the width W and cant C of the lane L1 based on information acquired from the on-board sensor 20. Specifically, the ECU 10 acquires the X coordinates (lateral positions) of the bottom ends (ends on the host vehicle side) of the lane markings BL and BR in the image data from the camera 21. The ECU 10 calculates the width W of the lane L1 based on this information. The ECU 10 also acquires the lateral acceleration ya from the acceleration sensor 23. The ECU 10 also acquires the steering angle φ from the steering ECU and acquires the turning radius r based on the steering angle φ. The ECU 10 may also acquire the turning radius r from a yaw rate sensor (not shown). The ECU 10 corrects the acceleration ya based on the turning radius r and the speed vs. That is, the ECU 10 eliminates the effect of the turning of the host vehicle on the acceleration ya. The ECU 10 then calculates the cant C based on the corrected acceleration ya.

[0033] Next, the ECU 10 sets the target value vyd based on the width W and the cant C. A map M1 (see FIG. 4A) that defines the relationship between the width W and the target value vyd is stored in the ROM 10b, and the ECU 10 obtains the target value vyd by referring to the map M1. The map M1 is designed so that the target value vyd decreases as the width W decreases.

[0034] Furthermore, the ECU 10 corrects the target value vyd obtained as described above based on the cant C. Specifically, when the left edge of the lane L1 is lower than the right edge in the first situation (FIG. 2(B)), the ECU 10 adds a predetermined correction value vyc (>0) to the target value vyd. When the left edge of the lane L1 is higher than the right edge in the first situation (FIG. 2(C)), the ECU 10 subtracts a predetermined correction value vyc (>0) from the target value vyd. When the right edge of the lane L1 is lower than the left edge in the second situation (FIG. 3(B)), the ECU 10 adds a predetermined correction value vyc (>0) to the target value vyd. When the right edge of the lane L1 is higher than the left edge in the second situation (FIG. 3(C)), the ECU 10 subtracts a predetermined correction value vyc (>0) from the target value vyd. A map M2 (see FIG. 4B) that defines the relationship between the cant C and the correction value vyc is stored in the ROM 10b, and the ECU 10 determines the correction value vyc by referring to the map M2. The map M2 is designed so that the correction value vyc increases as the cant C (the difference in elevation between the left and right edges of the lane L1) increases.

[0035] While performing the LDA process, the ECU 10 sequentially acquires the velocity vector vt of the host vehicle in the lane L1. Specifically, the ECU 10 sequentially calculates the traveling direction of the host vehicle in the lane L1 (the angle γ between a line parallel to the width direction of the lane L1 and a line passing through the center of the host vehicle in the width direction) based on information acquired from the camera 21 (the positions of the lane markings BL and BR in the image and their extending directions), and sequentially acquires the velocity vs from the vehicle speed sensor 22. The ECU 10 then acquires the lateral component of the velocity vector vt as the lateral velocity vy (= vt × cos γ). The ECU 10 terminates the execution of the LDA process when the lateral velocity vy increases through the LDA process and reaches a target value vyd (when a termination condition is met).

[0036] Next, with reference to Figures 5 and 6, we will explain the program PR1 (main routine (Figure 5)) and program PR2 (subroutine (Figure 6)) executed by the CPU 10a (hereinafter simply referred to as "CPU") of the ECU 10 to realize the above-mentioned lane departure prevention function.

[0037] (Program PR1) When the ignition switch is in the ON state, the CPU starts executing the program PR1 at a predetermined cycle. The CPU starts executing the program PR1 from step 100 and proceeds to step 101.

[0038] In step 101, the CPU acquires a predicted time ΔT until the host vehicle deviates from the lane L1, and determines whether the predicted time ΔT is equal to or less than a threshold value ΔTth. If the CPU determines that the predicted time ΔT is equal to or less than the threshold value ΔTth (101: Yes), the CPU proceeds to step 102. On the other hand, if the CPU does not determine that the predicted time ΔT is equal to or less than the threshold value ΔTth (101: No), the CPU proceeds to step 108, where it ends execution of the program PR1.

[0039] The CPU starts the LDA process in step 102. Next, the CPU proceeds to step 103.

[0040] In step 103, the CPU refers to the map M1 to obtain the target value vyd of the lateral speed vy. Then, the CPU proceeds to step 104.

[0041] In step 104, the CPU obtains the cant C of the lane L1 based on the information obtained from the on-board sensor 20. Next, the CPU proceeds to step 105.

[0042] In step 105, the CPU executes a program PR2, which will be described later, to correct the target value vyd.

[0043] In step 106, the CPU determines whether the lateral speed vy (actual measured value) exceeds the target value vyd. If the CPU determines that the lateral speed vy exceeds the target value vyd (106: Yes), the CPU proceeds to step 107. On the other hand, if the CPU does not determine that the lateral speed vy exceeds the target value vyd (106: No), the CPU returns to step 106. That is, the CPU continues the LDA processing until the lateral speed vy exceeds the target value vyd.

[0044] The CPU ends the execution of the LDA process in step 107. Next, the CPU proceeds to step 108, where it ends the execution of the program PR1.

[0045] (Program PR2) The CPU starts execution of the program PR2 from step 200, and proceeds to step 201. In step 201, the CPU refers to the map M2 to obtain the correction value vyc. Next, the CPU proceeds to step 202.

[0046] In step 202, the CPU determines whether or not the situation is such that there is a high possibility that the host vehicle will deviate from the left edge of lane L1 (first situation). If the CPU determines that the situation is the first situation (202: Yes), the process proceeds to step 203. On the other hand, if the CPU does not determine that the situation is the first situation (202: No), the process proceeds to step 207.

[0047] In step 203, the CPU determines whether the left edge of lane L1 is lower than the right edge based on information acquired from the on-board sensor 20. If the CPU determines that the left edge of lane L1 is lower than the right edge (203: Yes), the CPU proceeds to step 205. On the other hand, if the CPU does not determine that the left edge of lane L1 is lower than the right edge (203: No), the CPU proceeds to step 204.

[0048] In step 204, the CPU determines whether the right edge of lane L1 is lower than the left edge based on information acquired from the on-board sensor 20. If the CPU determines that the right edge of lane L1 is lower than the left edge (204: Yes), the CPU proceeds to step 206. On the other hand, if the CPU does not determine that the right edge of lane L1 is lower than the left edge (204: No), the CPU proceeds to step 211, where it terminates execution of program PR2 and proceeds to step 106 of program PR1.

[0049] In step 205, the CPU adds the correction value vyc (the value obtained from map M2) to the target value vyd (the value obtained from map M1) and adopts the result as the target value vyd. Next, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0050] In step 206, the CPU subtracts the correction value vyc (the value obtained from map M2) from the target value vyd (the value obtained from map M1) and adopts the result as the target value vyd. Next, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0051] In step 207, the CPU determines whether the right edge of lane L1 is lower than the left edge based on information acquired from the on-board sensor 20. If the CPU determines that the right edge of lane L1 is lower than the left edge (207: Yes), the CPU proceeds to step 209. On the other hand, if the CPU does not determine that the right edge of lane L1 is lower than the left edge (207: No), the CPU proceeds to step 208.

[0052] In step 208, the CPU determines whether the left edge of lane L1 is lower than the right edge, based on information acquired from the on-board sensor 20. If the CPU determines that the left edge of lane L1 is lower than the right edge (208: Yes), the CPU proceeds to step 210. On the other hand, if the CPU does not determine that the left edge of lane L1 is lower than the right edge (208: No), the CPU proceeds to step 211, where it terminates execution of program PR2 and proceeds to step 106.

[0053] In step 209, the CPU adds the correction value vyc (the value obtained from map M2) to the target value vyd (the value obtained from map M1) and adopts the result as the target value vyd. Next, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0054] In step 210, the CPU subtracts the correction value vyc (the value obtained from map M2) from the target value vyd (the value obtained from map M1) and adopts the result as the target value vyd. Next, the CPU J proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0055] (effect) When there is a high possibility that the host vehicle will deviate from the lane L1 (ΔT<ΔTth), the ECU 10 of the lane departure prevention device 1 executes lane departure prevention processing (alarm processing P1 and automatic steering processing P2) to prevent the departure. As a result, the host vehicle begins to move toward the center of the lane L1 in the width direction. Then, when a predetermined termination condition is met (when the lateral speed vy exceeds the target value vyyd), the ECU 10 terminates the lane departure prevention processing. Here, within a predetermined period (short period) after the lane departure prevention processing is terminated, the host vehicle may deviate (re-depart) from one end or the other end of the lane L1 due to the influence of the lane width W and cant C. According to this embodiment, the ECU 10 determines the target value vyd in accordance with the width W and cant C. This suppresses the above-mentioned re-departure.

[0056] The present invention is not limited to the above-described embodiment, and various modifications can be adopted within the scope of the present invention, as described below.

[0057] <Variation 1> In the above embodiment, ECU 10 acquires the width W and cant C of lane L1 as information about the driving environment of the host vehicle, and determines the target value vyd based on this information. Alternatively (or in addition), ECU 10 may acquire information about the direction and strength of a crosswind, for example, and determine the target value vyd based on this information. Specifically, when a crosswind is blowing from the right side (left side) to the left side (right side) in the first situation (second situation), ECU 10 may assign a larger value to the target value vyd as the wind speed increases. Conversely, when a crosswind is blowing from the left side (right side) to the right side (left side) in the first situation (second situation), ECU 10 may assign a smaller value to the target value vyd as the wind speed increases.

[0058] <Variation 2> In the above embodiment, the target value vyd obtained by referring to the map M1 is corrected using the correction value vyc obtained by referring to the map M2, but this correction process may be omitted. [Explanation of symbols]

[0059] 1... lane departure prevention device, 10... ECU, 20... vehicle-mounted sensor, 30... alarm device, 40... braking device

Claims

1. an on-board sensor for acquiring information about the driving environment of the host vehicle, as well as information about the lateral position and lateral speed of the host vehicle in the lane in which the host vehicle is traveling; a processor configured to, when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on information acquired from the on-board sensor is satisfied, start a lane departure prevention process for controlling the host vehicle so as to prevent the host vehicle from deviating from the lane, and thereafter, when a predetermined second condition is satisfied, terminate execution of the lane departure prevention process; A lane departure prevention device comprising: The processor: setting the second condition based on information about the running environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the running environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process; A lane departure prevention device configured as follows.

2. The lane departure prevention device according to claim 1, the second condition is established when a lateral speed of the host vehicle when the host vehicle is heading toward the center of the lane exceeds a predetermined target value, the information about the driving environment includes information about the width of the lane, the processor assigns a smaller value to the target value as the width of the lane becomes smaller; A lane departure prevention device configured as follows.

3. 3. The lane departure prevention device according to claim 2, The information about the driving environment further includes information about the cant of the lane, When the one end of the lane is lower than the other end, the processor adds a larger correction value to the target value as the difference in elevation increases, and when the one end of the lane is higher than the other end, the processor subtracts a larger value from the target value as the difference in elevation increases. A lane departure prevention device configured as follows.

4. an information acquisition step of acquiring information about the driving environment of the host vehicle, and information about the lateral position and lateral speed of the host vehicle in the lane in which the host vehicle is traveling; a vehicle control step configured to start a lane departure prevention process for controlling the host vehicle so as to prevent the host vehicle from departing from the lane when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on the information acquired in the information acquisition step is met, and thereafter, to end the execution of the lane departure prevention process when a predetermined second condition is met; A lane departure suppression method comprising: The vehicle control step includes: and setting the second condition based on information about the driving environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the driving environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process. The lane departure prevention method is configured as follows.

5. The computer installed in the vehicle an information acquisition step of acquiring information about the driving environment of the host vehicle, and information about the lateral position and lateral speed of the host vehicle in the lane in which the host vehicle is traveling; a vehicle control step configured to start a lane departure prevention process for controlling the host vehicle so as to prevent the host vehicle from departing from the lane when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end of the lane in the width direction to the outside of the lane based on the information acquired in the information acquisition step is met, and thereafter, to end the execution of the lane departure prevention process when a predetermined second condition is met; A lane departure prevention program that executes The vehicle control step includes: and setting the second condition based on information about the driving environment so that the host vehicle is prevented from re-departing from the lane due to the influence of the driving environment within a predetermined period after the lane departure prevention process is terminated while the host vehicle is moving toward the center in the width direction of the lane due to the execution of the lane departure prevention process. This is a lane departure prevention program designed to:

Images