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

Abstract

The present invention relates to a lane departure suppression device, a lane departure suppression method, and a lane departure suppression program. When a first condition for determining that there is a high likelihood that the own vehicle is departing from one end of the lane in the width direction of the lane toward the outside of the lane is satisfied, lane departure suppression processing for controlling the own vehicle so as to suppress departure of the own vehicle from the lane is started. When a predetermined second condition is satisfied, the execution of the lane departure suppression processing is terminated. The processor sets the second condition on the basis of information relating to the traveling environment so as to suppress a situation in which the own vehicle is re-departed from the lane due to the influence of the traveling environment within a predetermined period after the completion of the lane departure suppression processing.

Description

Technical Field

[0001] The present invention relates to a lane departure suppression device, a lane departure suppression method, and a lane departure suppression program for suppressing a host vehicle from departing from a lane in which the host vehicle is traveling. Background Art

[0002] There has been proposed a lane departure suppression device for suppressing a host vehicle from departing from a lane in which the host vehicle is traveling (for example, refer to Japanese Patent Application Laid-Open No. 2007-210412). A processor of the lane departure suppression device (hereinafter referred to as "conventional device") of Japanese Patent Application Laid-Open No. 2007-210412 performs lane departure suppression processing for controlling the host vehicle (a driving device and / or a braking device of each wheel) in such a manner that the host vehicle returns to the original lane when the host vehicle has entered a shoulder from the lane in which the host vehicle is traveling (when the host vehicle has departed from the lane). Summary of the Invention

[0003] As described above, by the processor of the conventional device performing lane departure suppression processing, the host vehicle travels toward the center side in the width direction of the original lane. Here, for example, in a situation where the width of the lane is relatively small, when the lane departure suppression processing is ended in a state where the host vehicle travels from the left end side of the lane toward the center side, it is possible that the host vehicle departs again from the right end (the end on the opposite side from the previous time) of the lane immediately thereafter. In addition, it is possible that the host vehicle departs again from the lane due to the influence of the camber of the lane and a crosswind immediately after the lane departure suppression processing is ended. In this way, it is possible that the host vehicle departs again from the lane due to the influence of the driving environment of the host vehicle (within a short period) immediately after the processor ends the lane departure suppression processing. The conventional device does not have a means for suppressing such re-departure.

[0004] One object of the present invention is to provide a lane departure suppression device that can suppress a situation where the host vehicle departs again from the lane due to the influence of the driving environment immediately after the control for suppressing the departure of the host vehicle from the lane is ended.

[0005] In order to solve the above problems, a lane departure suppression device (1) of the present invention includes an in-vehicle sensor (20) and a processor (10).

[0006] The in-vehicle sensor (20) is configured to acquire information related to a driving environment (W, C) of the host vehicle (V), and information related to a lateral position and a lateral speed on a lane (L1) on which the host vehicle is traveling.

[0007] The processor (10) is configured to start lane departure suppression processing (P1, P2) for controlling the host vehicle in a manner that suppresses the departure of the host vehicle from the lane when a first condition for determining that there is a high possibility that the host vehicle departs from one end in the width direction of the lane to the outside of the lane is satisfied, based on information acquired from the in-vehicle sensors. After that, the execution of the lane departure suppression processing is ended when a predetermined second condition is satisfied.

[0008] The processor is configured to

[0009] set the second condition based on information related to the driving environment in a manner that suppresses the situation where the host vehicle is affected by the driving environment and departs from the lane again within a predetermined period after the lane departure suppression processing is ended while the host vehicle is traveling toward the central portion side in the width direction of the lane by the execution of the lane departure suppression processing.

[0010] In addition, the lane departure suppression method of the present invention includes an information acquisition step and a vehicle control step.

[0011] In the information acquisition step, information related to the driving environment of the host vehicle and information related to the lateral position and lateral speed on the lane on which the host vehicle is traveling are acquired.

[0012] The vehicle control step is configured to start lane departure suppression processing for controlling the host vehicle in a manner that suppresses the departure of the host vehicle from the lane when a first condition for determining that there is a high possibility that the host vehicle departs from one end in the width direction of the lane to the outside of the lane is satisfied, based on the information acquired in the information acquisition step. After that, the execution of the lane departure suppression processing is ended when a predetermined second condition is satisfied.

[0013] The vehicle control step is configured to include the following steps:

[0014] set the second condition based on information related to the driving environment in a manner that suppresses the situation where the host vehicle is affected by the driving environment and departs from the lane again within a predetermined period after the lane departure suppression processing is ended while the host vehicle is traveling toward the central portion side in the width direction of the lane by the execution of the lane departure suppression processing.

[0015] In addition, the lane departure suppression program of the present invention causes a computer provided in the host vehicle to execute the information acquisition step and the vehicle control step.

[0016] In the information acquisition step, information related to the driving environment of the host vehicle and information related to the lateral position and lateral speed on the lane on which the host vehicle is traveling are acquired.

[0017] The vehicle control step is configured such that, based on the information acquired in the information acquisition step, when a first condition for determining that there is a high possibility that the host vehicle will deviate from one end in the width direction of the lane to the outside of the lane is satisfied, a lane departure suppression process for controlling the host vehicle in a manner that suppresses the departure of the host vehicle from the lane is started, and thereafter, when a predetermined second condition is satisfied, the execution of the lane departure suppression process is ended.

[0018] The vehicle control step is configured to include the following steps:

[0019] The second condition is set based on the information related to the driving environment in such a manner as to suppress the situation where the host vehicle is affected by the driving environment and deviates from the lane again within a predetermined period (short period) after the lane departure suppression process is ended while the host vehicle is traveling toward the central portion side in the width direction of the lane by the execution of the lane departure suppression process.

[0020] The processor of the lane departure suppression device of the present invention executes a lane departure suppression process for suppressing the departure when there is a high possibility that the host vehicle will depart from the lane (when the first condition is satisfied). As a result, the host vehicle starts to travel toward the central portion side in the width direction of the lane. Thereafter, the processor ends the lane departure suppression process when a predetermined end condition (when the second condition is satisfied). Here, there is a possibility that within a predetermined period (short period) after the lane departure suppression process is ended, the host vehicle is affected by the driving environment (e.g., the width of the lane, the roll angle, the crosswind, etc.) and departs from one end or the other end of the lane (re-departs). According to the present invention, the second condition is set according to the driving environment. Thereby, the re-departure as described above is suppressed.

[0021] In a lane departure suppression device according to an aspect of the present invention,

[0022] The second condition is configured to be satisfied when the lateral speed (vy) of the host vehicle when traveling toward the central portion side of the lane exceeds a predetermined target value (vyd).

[0023] The information related to the driving environment includes information related to the width (W) of the lane.

[0024] The smaller the width of the lane, the smaller the value assigned by the processor to the target value.

[0025] Assume that when traveling from one end of a lane to the central part laterally under the condition that the width of the lane is relatively small and ending the lane departure suppression process when the lateral speed is relatively high, there is a high possibility that the host vehicle will depart from the other end of the lane. According to the lane departure suppression device of the present technical solution, the target value of the lateral speed is set according to the width of the lane (the condition for ending the lane departure suppression process (the second condition)). Therefore, the situation where the host vehicle departs from the other end of the lane immediately after ending the control for suppressing the departure of the host vehicle from one end of the lane is suppressed.

[0026] In the lane departure suppression device of another technical solution of the present invention,

[0027] The information related to the driving environment includes information related to the roll angle (C) of the lane.

[0028] The processor,

[0029] When the one end side of the lane is lower than the other end side, the greater the height difference, the greater the correction value added to the target value. When the one end side of the lane is higher than the other end side, the greater the height difference, the greater the value subtracted from the target value.

[0030] When one end side (the other end side) of the lane is lower than the other end side (one end side), due to this inclination, the host vehicle is affected by the gravity acting laterally (the lateral component of the gravitational acceleration) and is likely to travel toward the one end side (the other end side) of the lane. Therefore, the host vehicle is likely to depart from one end (the other end) of the lane. According to the present technical solution, the target value of the lateral speed is corrected according to the magnitude of the roll angle (height difference). Therefore, the situation where the host vehicle departs from the lane due to the roll angle immediately after ending the lane departure suppression process is suppressed. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Hereinafter, the features, advantages, and technical and industrial significance of the exemplary embodiments of the present invention will be described with reference to the drawings. In the drawings, the same reference numerals denote the same elements, and:

[0032] Figure 1 is a block diagram of a lane departure suppression device according to an embodiment of the present invention.

[0033] Figure 2A is a top view showing a situation of suppressing the departure of the host vehicle from the left end of the lane.

[0034] Figure 2B is a top view showing a situation of suppressing the departure of the host vehicle from the left end of the lane.

[0035] Figure 2C is a top view showing a situation of suppressing the departure of the host vehicle from the left end of the lane.

[0036] Figure 3A It is a top view showing a situation where the lane departure of the host vehicle from the right end of the lane is suppressed by the lane departure suppression function.

[0037] Figure 3B It is a top view showing a situation where the lane departure of the host vehicle from the right end of the lane is suppressed by the lane departure suppression function.

[0038] Figure 3C It is a top view showing a situation where the lane departure of the host vehicle from the right end of the lane is suppressed by the lane departure suppression function.

[0039] Figure 4A It is a map M1 that defines the relationship between the lane width W and the target value vyd.

[0040] Figure 4B It is a map M2 that defines the relationship between the lane roll angle C and the correction value vyc.

[0041] Figure 5 It is a flowchart of a program executed by the CPU to implement the lane departure suppression function.

[0042] Figure 6 It is a flowchart of a program executed by the CPU to correct the target value vyd. Detailed implementation mode

[0043] (Overview)

[0044] As Figure 1 shown, the lane departure suppression device 1 according to an embodiment of the present invention is applied to a vehicle V (hereinafter referred to as the "host vehicle") equipped with an autonomous driving function. The lane departure suppression device 1 has a lane departure suppression function, which is a function of controlling the host vehicle (the notification device 30 and the steering device 40 described later) in a manner that suppresses the host vehicle from departing from the lane in a state where the autonomous driving function is invalidated.

[0045] (Specific configuration)

[0046] As Figure 1 shown, the lane departure suppression device 1 includes an ECU 10, an in-vehicle sensor 20, a notification device 30, and a steering device 40.

[0047] The ECU 10 includes a microcomputer including a CPU 10a, a ROM 10b (rewritable non-volatile memory), a RAM 10c, a timer 10d, etc. The CPU implements various functions by executing programs (instructions) stored in the ROM. The ECU 10 is connected to other ECUs via a CAN (Controller Area Network).

[0048] The vehicle-mounted sensor 20 includes a camera 21, a vehicle speed sensor 22, and an acceleration sensor 23.

[0049] The camera 21 includes a photographing device. The photographing device incorporates, for example, a CCD. The photographing device is provided at the front of the host vehicle and faces the front of the host vehicle. The photographing device photographs the front area of the host vehicle at a predetermined frame rate and acquires image data. The camera 21 also includes an image analysis device. The image analysis device acquires the image data from the photographing device, analyzes the image data, and identifies the target objects present within the viewing angle. The image analysis device, for example, identifies the dividing lines BR and BL of the lane L1 on which the host vehicle is traveling. The image analysis device acquires the shape of the dividing lines BR and BL (the curvature of the lane L1) and the interval between the dividing lines BR and BL (the width W of the lane L1) as dividing line information. In addition, the image analysis device acquires the lateral position of the center of gravity G of the host vehicle on the lane L1 (the distance between the center of gravity G and the dividing line BR and the distance between the center of gravity G and the dividing line BL) as position information based on the positions (coordinates) of the dividing lines BR and BL within the viewing angle of the photographing device. The image analysis device provides the dividing line information and the position information to the ECU 10.

[0050] The vehicle speed sensor 22 acquires the speed vs of the host vehicle (the forward speed (absolute value) relative to the lane L1) based on the rotational speed of the wheels per unit time. And the vehicle speed sensor 22 provides the acquired speed vs to the ECU 10.

[0051] The acceleration sensor 23 includes a piezoelectric element. When the vehicle itself accelerates (or decelerates) in the longitudinal direction and the width direction, the piezoelectric element deforms in the longitudinal direction of the vehicle itself and the width direction of the vehicle itself. Along with this deformation, the output voltage of the piezoelectric element changes. The acceleration sensor 23 obtains the longitudinal and lateral accelerations of the vehicle itself based on the output voltage of the piezoelectric element. And the acceleration sensor 23 provides these accelerations to the ECU 10. In addition, in the state where the vehicle itself is stationary or moving straight at a constant speed, the output (acceleration information) of the acceleration sensor 23 represents the gravitational acceleration. That is, the inclination angle (gradient) of the road surface can be calculated based on the output of this acceleration sensor 23. In addition, when the vehicle itself accelerates (decelerates) or turns, the inclination angle (gradient) of the road surface can be calculated based on the acceleration information obtained by eliminating the influence of the movement of the vehicle itself on the output of the acceleration sensor 23.

[0052] The notification device 30 includes an image display device and an audio device. The image display device is arranged, for example, on the instrument panel (near the speed display device). The image display device displays an image according to an instruction obtained from the ECU 10. The audio device emits a sound according to an instruction obtained from the ECU 10.

[0053] 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 further includes an actuator (such as an electric motor) that drives the steering mechanism to change the steering angle, and a steering angle sensor that obtains the steering angle φ (actual steering angle) of the steered wheels. The ECU 10 determines the target value φd of the steering angle φ (actual steering angle) of the steered wheels based on various information obtained from the in-vehicle sensor 20. In addition, the steering angle φ in the state where the vehicle itself is moving straight is "0 (deg)". The steering angle φ is positive (>0) when the vehicle itself turns right, and the steering angle φ is negative (<0) when the vehicle itself turns left. For example, when the steering wheel rotates in the right direction, the ECU 10 increases the target value φd, and when the steering wheel rotates in the left direction, the ECU 10 decreases the target value φd. In addition, when the possibility that the vehicle itself deviates from the lane L1 is high, the ECU 10 determines the target value φd in such a way that the vehicle itself travels toward the central part side in the width direction of the lane L1. The steering ECU obtains this 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.

[0054] (Operation)

[0055] As described below, when the possibility that the vehicle itself deviates from the lane L1 is high, the ECU 10 executes lane departure suppression processing (hereinafter, referred to as "LDA processing").

[0056] (LDA Processing)

[0057] When the ignition switch is in the ON state, the ECU 10 sequentially acquires various information from the vehicle-mounted sensors 20 at a predetermined cycle. Specifically, the ECU 10 acquires the lane line information and the position information from the camera 21 (image analysis device). In addition, the ECU 10 acquires the speed vs from the vehicle speed sensor 22. In addition, the ECU 10 acquires the steering angle φ (actual steering angle) from the steering ECU. Based on this information, the ECU 10 calculates the predicted trajectory PT of the host vehicle on the lane L1 (for example, the trajectory of the center of gravity G of the host vehicle or the outer periphery of the host vehicle), and acquires the point X where the predicted trajectory PT intersects the lane line BR or the lane line BL. The ECU 10 calculates the time ΔT until the center of gravity G (or the outer periphery of the host vehicle) reaches the point X (intersects the point X). In the present embodiment, when the time ΔT is equal to or less than the threshold value ΔTth, it is regarded as a state where the possibility of the host vehicle leaving the lane L1 is high. When the time ΔT is equal to or less than the threshold value ΔTth (when the start condition of the LDAs process (the first condition of the present invention) is satisfied), the ECU 10 executes the following alarm process P1 and automatic steering process P2 as the LDA process.

[0058] (Alarm Process P1)

[0059] In order to notify the driver that the possibility of the host vehicle leaving the lane L1 is high, the ECU 10 sends a predetermined alarm command to the notification device 30. The image display device of the notification device 30 displays an image (icon) corresponding to the alarm command. In addition, the sound device of the notification device 30 emits a sound (alarm sound) corresponding to the alarm command.

[0060] (Automatic Steering Process P2)

[0061] The ECU 10 sends a steering command (target value of the steering angle) corresponding to the direction of the predicted trajectory PT with respect to the lane L1 to the steering ECU. Specifically, when the predicted trajectory PT intersects the lane line BL (the first situation ( Figure 2A , Figure 2B , Figure 2C ))), the ECU 10 sets the target value φd in such a way that the host vehicle turns right (the way the steering angle φ increases), and sends it to the steering ECU. On the other hand, when the predicted trajectory PT intersects the lane line BR (the second situation ( Figure 3A , Figure 3B , Figure 3C ))), the ECU 10 sets the target value φd in such a way that the host vehicle turns left (the way the steering angle φ decreases), and sends it to the steering ECU.

[0062] 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 used 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 used as the new target value φd.

[0063] Alternatively, a value corresponding 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 this map. Further, in the first situation, the target value φd corresponding to the time ΔT1 is “+α1 (deg)”, and the target value φd corresponding to a 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 a time ΔT2 longer than the time ΔT1 is “−α2 (deg)” which is larger than “−α1 (deg)”.

[0064] Alternatively, for example, a value corresponding to the angle β may be assigned to the target value φd, where the angle β is the angle between the tangent of the predicted trajectory PT at the point X where the predicted trajectory PT intersects the dividing line BL (BR) and the tangent of the dividing line BL (BR) at the point X. In this case, in the first situation, the larger the absolute value of the angle β, the larger the value (>0) that can be assigned to the target value φd. Further, in the second situation, the larger the absolute value of the angle β, the smaller the value (<0) that can be assigned to the target value φd.

[0065] When the possibility of the host vehicle departing from the lane L1 is high, by executing the LDA process (the alarm process P1 and the automatic steering process P2), the host vehicle starts to travel toward the center side in the width direction of the lane L1. In other words, the component (lateral speed vy) in the direction toward the center side in the width direction of the lane L1 as a component of the speed vector vt of the host vehicle starts to increase. The ECU 10 ends the execution of the LDA process when a predetermined end condition (the second condition of the present invention) is satisfied. In the present embodiment, when the lateral speed vy reaches the target value vyd described below, it is regarded that the end condition is satisfied.

[0066] At the time point when ECU10 starts the LDA process, based on the information obtained from in-vehicle sensor 20, it obtains the width W and the roll angle C of lane L1. Specifically, ECU10 obtains the X coordinates (lateral positions) of the lower ends (ends on the own-vehicle side) of dividing line BL and dividing line BR in the image data from camera 21 respectively. ECU10 calculates the width W of lane L1 based on this information. In addition, ECU10 obtains the lateral acceleration ya from acceleration sensor 23. In addition, ECU10 obtains the steering angle φ from the steering ECU, and based on this steering angle φ, it obtains the turning radius r. In addition, ECU10 may also obtain the turning radius r from a yaw rate sensor (not shown). ECU10 corrects the acceleration ya based on the turning radius r and the speed vs. That is, ECU10 eliminates the influence of the turning of the own vehicle on the acceleration ya. After that, ECU10 calculates the roll angle C based on the corrected acceleration ya.

[0067] Next, ECU10 sets the target value vyd based on the width W and the roll angle C. A map M1 (refer to Figure 4A ) that defines the relationship between the width W and the target value vyd is stored in ROM10b, and ECU10 refers to this map M1 to obtain the target value vyd. In addition, the map M1 is designed such that the smaller the width W, the smaller the target value vyd.

[0068] Furthermore, ECU10 corrects the target value vyd obtained as described above based on the roll angle C. Specifically, in the first situation, when the left end of lane L1 is lower than the right end ( Figure 2B ), ECU10 adds a predetermined correction value vyc (>0) to the target value vyd. In addition, in the first situation, when the left end of lane L1 is higher than the right end ( Figure 2C ), ECU10 subtracts a predetermined correction value vyc (>0) from the target value vyd. In addition, in the second situation, when the right end of lane L1 is lower than the left end ( Figure 3B ), ECU10 adds a predetermined correction value vyc (>0) to the target value vyd. In addition, in the second situation, when the right end of lane L1 is higher than the left end ( Figure 3C ), ECU10 subtracts a predetermined correction value vyc (>0) from the target value vyd. In addition, a map M2 (refer to Figure 4B ) that defines the relationship between the roll angle C and the correction value vyc is stored in ROM10b, and ECU10 refers to this map M2 to determine the correction value vyc. The map M2 is designed such that the larger the roll angle C (the height difference between the left and right ends of lane L1), the larger the correction value vyc.

[0069] While the ECU 10 is performing the LDA process, it successively obtains the velocity vector vt of the host vehicle on lane L1. Specifically, the ECU 10 successively calculates the traveling direction of the host vehicle on lane L1 (the angle γ between the straight line parallel to the width direction of lane L1 and the straight line passing through the center of the width direction of the host vehicle) based on the information obtained from the camera 21 (the positions of the dividing lines BL and BR in the image and their extending directions), and successively obtains the vehicle speed vs from the vehicle speed sensor 22. After that, the ECU 10 obtains the lateral component of the velocity vector vt as the lateral velocity vy (vt × cos γ). When the lateral velocity vy increases through the LDA process and reaches the target value vyd (when the end condition is satisfied), the ECU 10 ends the execution of the LDA process.

[0070] Next, referring to Figure 5 and Figure 6 , the program PR1 (main routine ( Figure 5 )) and the program PR2 (subroutine ( Figure 6 )) executed by the CPU 10a of the ECU 10 (hereinafter simply referred to as "CPU") to achieve the above-mentioned lane departure suppression function will be described.

[0071] (Program PR1)

[0072] When the ignition switch is in the ON state, the CPU starts the execution of program PR1 at a predetermined cycle. The CPU starts the execution of program PR1 from step 100 and makes the process enter step 101.

[0073] In step 101, the CPU obtains the predicted time ΔT until the host vehicle departs from lane L1 and determines whether the predicted time ΔT is less than or equal to the threshold value ΔTth. When the CPU determines that the predicted time ΔT is less than or equal to the threshold value ΔTth (101: "Yes"), it makes the process enter step 102. On the other hand, when the CPU does not determine that the predicted time ΔT is less than or equal to the threshold value ΔTth (101: "No"), it makes the process enter step 108, and in this step 108, it ends the execution of program PR1.

[0074] In step 102, the CPU starts the LDA process. Next, the CPU makes the process enter step 103.

[0075] In step 103, the CPU refers to the map M1 and obtains the target value vyd of the lateral velocity vy. Next, the CPU makes the process enter step 104.

[0076] In step 104, the CPU obtains the roll angle C of lane L1 based on the information obtained from the in-vehicle sensor 20. Next, the CPU makes the process enter step 105.

[0077] In step 105, the CPU executes the following program PR2 to correct the target value vyd.

[0078] In step 106, the CPU determines whether the lateral velocity vy (measured value) exceeds the target value vyd. When the CPU determines that the lateral velocity vy exceeds the target value vyd (106: "Yes"), the process proceeds to step 107. On the other hand, when the CPU does not determine that the lateral velocity vy exceeds the target value vyd (106: "No"), the process returns to step 106. That is, the CPU continues the LDA process until the lateral velocity vy exceeds the target value vyd.

[0079] In step 107, the CPU terminates the execution of the LDA process. Then, the CPU makes the process proceed to step 108, where the execution of program PR1 is terminated.

[0080] (Program PR2)

[0081] The CPU starts the execution of program PR2 from step 200 and makes the process proceed to step 201. In step 201, the CPU refers to the map M2 to obtain the correction value vyc. Then, the CPU makes the process proceed to step 202.

[0082] In step 202, the CPU determines whether the situation is such that the possibility of the host vehicle departing from the left end of lane L1 is high (the first situation). When the CPU determines that it is the first situation (202: "Yes"), the process proceeds to step 203. On the other hand, when the CPU does not determine that it is the first situation (202: "No"), the process proceeds to step 207.

[0083] In step 203, based on the information obtained from in-vehicle sensor 20, the CPU determines whether the left end of lane L1 is lower than the right end. When the CPU determines that the left end of lane L1 is lower than the right end (203: "Yes"), the process proceeds to step 205. On the other hand, when the CPU does not determine that the left end of lane L1 is lower than the right end (203: "No"), the process proceeds to step 204.

[0084] In step 204, based on the information obtained from in-vehicle sensor 20, the CPU determines whether the right end of lane L1 is lower than the left end. When the CPU determines that the right end of lane L1 is lower than the left end (204: "Yes"), the process proceeds to step 206. On the other hand, when the CPU does not determine that the right end of lane L1 is lower than the left end (204: "No"), the process proceeds to step 211, where the execution of program PR2 is terminated and the process proceeds to step 106 of program PR1.

[0085] In step 205, the CPU uses the value obtained by adding the correction value vyc (obtained from mapping M2) to the target value vyd (the value obtained from mapping M1) as the target value vyd. Then, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0086] In step 206, the CPU uses the value obtained by subtracting the correction value vyc (obtained from mapping M2) from the target value vyd (the value obtained from mapping M1) as the target value vyd. Then, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0087] In step 207, the CPU determines whether the right end of lane L1 is lower than the left end based on the information obtained from in-vehicle sensor 20. If the CPU determines that the right end of lane L1 is lower than the left end (207: "Yes"), it proceeds to step 209. On the other hand, if the CPU does not determine that the right end of lane L1 is lower than the left end (207: "No"), it proceeds to step 208.

[0088] In step 208, the CPU determines whether the left end of lane L1 is lower than the right end based on the information obtained from in-vehicle sensor 20. If the CPU determines that the left end of lane L1 is lower than the right end (208: "Yes"), it proceeds to step 210. On the other hand, if the CPU does not determine that the left end of lane L1 is lower than the right end (208: "No"), it proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0089] In step 209, the CPU uses the value obtained by adding the correction value vyc (obtained from mapping M2) to the target value vyd (the value obtained from mapping M1) as the target value vyd. Then, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0090] In step 210, the CPU uses the value obtained by subtracting the correction value vyc (obtained from mapping M2) from the target value vyd (the value obtained from mapping M1) as the target value vyd. Then, the CPU proceeds to step 211, where it ends the execution of program PR2 and proceeds to step 106.

[0091] (Effect)

[0092] When the ECU 10 of the lane departure suppression device 1 determines that there is a high possibility that the host vehicle will depart from the lane L1 (ΔT < ΔTth), it executes lane departure suppression processing (alarm processing P1 and automatic steering processing P2) to suppress such departure. As a result, the host vehicle starts to travel toward the center side in the width direction of the lane L1. Further, when a predetermined end condition is satisfied (when the lateral speed vy exceeds the target value vyyd), the ECU 10 ends the lane departure suppression processing. Here, there is a possibility that within a predetermined period (a short period) after the lane departure suppression processing is ended, the host vehicle may depart from one end or the other end of the lane L1 (redepart) due to the influence of the width W and the roll angle C of the lane. According to the present embodiment, the ECU 10 determines the target value vyd based on the width W and the roll angle C. Thereby, such redeparture is suppressed.

[0093] 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.

[0094] <Modification 1>

[0095] In the above-described embodiment, the ECU 10 acquires the width W and the roll angle C of the lane L1 as information related to the driving environment of the host vehicle, and determines the target value vyd based on this information. As an alternative (or addition), the ECU 10 may, for example, also acquire information related to the direction and intensity of a crosswind, and determine the target value vyd based on this information. Specifically, in the first situation (second situation), when a crosswind is blowing from the right side (left side) toward the left side (right side), the greater the wind speed, the greater the value that the ECU 10 may assign to the target value vyd. Conversely, in the first situation (second situation), when a crosswind is blowing from the left side (right side) toward the right side (left side), the greater the wind speed, the smaller the value that the ECU 10 may assign to the target value vyd.

[0096] <Modification 2>

[0097] In the above-described embodiment, the correction value vyc obtained using the reference map M2 is used to correct the target value vyd obtained using the reference map M1, but this correction process may be omitted.

Claims

1. A lane departure suppression device includes an in-vehicle sensor and a processor. The in-vehicle sensor is configured to obtain information related to the driving environment of the host vehicle and information related to the lateral position and lateral speed on the lane on which the host vehicle is traveling. The processor is configured to, based on the information obtained from the in-vehicle sensor, start lane departure suppression processing for controlling the host vehicle in a manner that suppresses the departure of the host vehicle from the lane when a first condition for determining that there is a high possibility that the host vehicle departs from one end in the width direction of the lane to the outside of the lane is satisfied, and then end the execution of the lane departure suppression processing when a predetermined second condition is satisfied. The processor is configured to set the second condition based on the information related to the driving environment in a manner that suppresses the situation where the host vehicle is affected by the driving environment and departs from the lane again within a predetermined period after the lane departure suppression processing is ended while the host vehicle is traveling toward the central portion side in the width direction of the lane due to the execution of the lane departure suppression processing.

2. The lane departure suppression device according to claim 1, wherein the second condition is configured to be satisfied when the lateral speed of the host vehicle when traveling toward the central portion side of the lane exceeds a predetermined target value. The information related to the driving environment includes information related to the width of the lane. The processor is configured to assign a smaller value to the target value as the width of the lane is smaller.

3. The lane departure suppression device according to claim 2, wherein the information related to the driving environment further includes information related to the bank angle of the lane. The processor is configured to add a larger correction value to the target value as the height difference is larger when one end side of the lane is lower than the other end side, and subtract a larger value from the target value as the height difference is larger when one end side of the lane is higher than the other end side.

4. A lane departure suppression method includes an information acquisition step and a vehicle control step. In the information acquisition step, information related to the driving environment of the host vehicle and information related to the lateral position and lateral speed on the lane on which the host vehicle is traveling are acquired. The vehicle control step is configured to, based on the information acquired in the information acquisition step, start lane departure suppression processing for controlling the host vehicle in a manner that suppresses the departure of the host vehicle from the lane when a first condition for determining that there is a high possibility that the host vehicle departs from one end in the width direction of the lane to the outside of the lane is satisfied, and then end the execution of the lane departure suppression processing when a predetermined second condition is satisfied. The vehicle control step is configured to include the following steps: The second condition is set based on information related to the driving environment in such a manner as to suppress a situation in which the host vehicle is affected by the driving environment and re-departs from the lane within a predetermined period after the lane departure suppression process is ended while the host vehicle is traveling toward the center side in the width direction of the lane by execution of the lane departure suppression process.

5. A lane departure suppression program, causing a computer provided in the host vehicle to execute an information acquisition step and a vehicle control step, wherein, in the information acquisition step, information related to the driving environment of the host vehicle and information related to the lateral position and lateral speed on the lane on which the host vehicle is traveling are acquired, the vehicle control step is configured to start a lane departure suppression process for controlling the host vehicle in such a manner as to suppress departure of the host vehicle from the lane when a first condition for determining that there is a high possibility that the host vehicle departs from the outside of the lane toward one end in the width direction of the lane is satisfied, and then end the execution of the lane departure suppression process when a predetermined second condition is satisfied, the vehicle control step is configured to include the following steps: The second condition is set based on information related to the driving environment in such a manner as to suppress a situation in which the host vehicle is affected by the driving environment and re-departs from the lane within a predetermined period after the lane departure suppression process is ended while the host vehicle is traveling toward the center side in the width direction of the lane by execution of the lane departure suppression process.

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