Lane departure prevention device

Abstract

A lane departure prevention device executes automatic steering control when an automatic steering execution condition is satisfied, the automatic steering control being control that automatically applies a steering force to a host vehicle to return the host vehicle to a lane. In addition, the lane departure prevention device executes alarm control when an alarm execution condition is determined to be satisfied on the basis of an actual running state of the host vehicle, the alarm control being control that performs an alarm for notifying a driver of the host vehicle that the host vehicle is likely to depart from the lane. On the other hand, the lane departure prevention device executes the alarm control when the alarm execution condition is determined to be satisfied on the basis of a running state of the host vehicle achieved by the automatic steering control, while the automatic steering control is being executed.

Description

Technical Field

[0001] This invention relates to a lane departure prevention device. Background Technology

[0002] A lane departure prevention device is known, wherein the lane departure prevention device performs alarm control and automatic steering control as lane departure prevention control for preventing the vehicle from deviating from the lane. The alarm control is a control that notifies the driver of the vehicle of the situation when the vehicle is about to deviate from the lane. The automatic steering control is an automatic steering control that automatically applies steering force to the vehicle to bring the vehicle back into the lane. Summary of the Invention

[0003] As such lane departure prevention devices, there are known lane departure prevention devices that separately set a determination value for determining whether to start alarm control and a determination value for determining whether to start automatic steering control (for example, see Japanese Patent Application Publication No. 2005-242483).

[0004] Warning control is used to prompt the driver to perform a driving operation (departure avoidance operation) to bring the vehicle back into the lane when it is about to deviate from the lane. On the other hand, automatic steering control is not used to prompt the driver to perform a departure avoidance operation, but to automatically apply steering force to bring the vehicle back into the lane. Since these controls have different purposes, it is advantageous to set separate judgment values ​​for determining whether to start warning control and for determining whether to start automatic steering control.

[0005] However, if such a threshold is set independently, an alarm may sound, for example, sometimes after autopilot control has been initiated. In such cases, since the vehicle will eventually return to its lane via autopilot control, the driver may feel that an unnecessary alarm has been issued. That is, the driver may become annoyed by the alarm.

[0006] The purpose of this invention is to provide a lane departure prevention device that reduces the likelihood of drivers becoming annoyed by warnings that inform them that the vehicle may be deviating from its lane.

[0007] The lane departure prevention device of the present invention includes a control device that performs alarm control and automatic steering control. The alarm control is to notify the driver of the vehicle that the vehicle may be deviating from the lane. The automatic steering control is to automatically apply steering force to the vehicle that may be deviating from the lane so that the vehicle returns to (is in) the lane.

[0008] In the lane departure prevention device of the present invention, the control device is configured to execute the automatic steering control when the automatic steering execution condition is met. Furthermore, the control device is configured to execute the alarm control when the alarm execution condition is determined to be met based on the actual driving state of the vehicle, even when the automatic steering control is not being executed. On the other hand, the control device is configured to execute the alarm control when the alarm execution condition is determined to be met based on the driving state of the vehicle achieved through the automatic steering control while the automatic steering control is being executed.

[0009] In determining whether a vehicle will deviate from its lane, if the vehicle's future driving state can be predicted, then determining whether the vehicle will deviate from its lane based on its future driving state is more accurate than determining whether the vehicle will deviate from its lane based on its actual driving state (i.e., its driving state at that point in time). Furthermore, when automatic steering control is in effect, braking force is automatically applied to the vehicle, so the future driving state of the vehicle under automatic steering control can be predicted.

[0010] According to the present invention, when automatic steering control is being performed, the determination of whether the alarm execution conditions are met is based on the vehicle's driving state achieved through the automatic steering control. Therefore, it is possible to more accurately determine whether the vehicle will deviate from its lane. Thus, alarm control is only executed when the probability of the vehicle deviating from its lane is high, and not executed when the probability is low, thereby reducing the likelihood of the driver becoming annoyed by the alarms under alarm control.

[0011] Furthermore, in the lane departure prevention device of the present invention, the control device may be configured to determine that the alarm execution condition is met when the position of the vehicle, predicted based on the actual driving state of the vehicle, reaches a predetermined determination line after a predetermined time, even when the automatic steering control is not being executed. Alternatively, in this case, the control device may be configured to determine that the alarm execution condition is met when the position of the vehicle, predicted based on the driving state of the vehicle achieved through the automatic steering control, reaches the determination line while the automatic steering control is being executed.

[0012] According to the present invention, when automatic steering control is being performed, the alarm execution condition is determined to be met when the vehicle's position reaches the determination line after a predetermined time, based on the vehicle's driving state as determined by automatic steering control. That is, the alarm execution condition is determined based on the vehicle's driving state as determined by automatic steering control. Therefore, when automatic steering control is being performed, it is possible to more accurately determine whether the vehicle will deviate from its lane. Thus, alarm control is only executed when the probability of the vehicle deviating from its lane is high, and not executed when the probability is low, thereby reducing the likelihood of the driver becoming annoyed by alarms under alarm control.

[0013] In the lane departure prevention device of the present invention, the control device may be configured to determine that the alarm execution condition is met when the vehicle reaches a determination line set based on the actual driving state of the vehicle, even when the automatic steering control is not being executed. Alternatively, in this case, the control device may be configured to determine that the alarm execution condition is met when the vehicle reaches a determination line set based on the driving state of the vehicle achieved through the automatic steering control, even when the automatic steering control is being executed.

[0014] According to the present invention, when automatic steering control is being performed, an alarm execution condition is determined to be met when the vehicle reaches a determination line set based on the vehicle's driving state achieved through automatic steering control. That is, the alarm execution condition is determined based on the vehicle's driving state achieved through automatic steering control. Therefore, when automatic steering control is being performed, it is possible to more accurately determine whether the vehicle will deviate from its lane. Thus, alarm control is only executed when the probability of the vehicle deviating from its lane is high, and not executed when the probability is low, thereby reducing the likelihood of the driver becoming annoyed by alarms under alarm control.

[0015] The constituent elements of this invention are not limited to the embodiments described below with reference to the accompanying drawings. Other objects, features, and incidental advantages of the invention should be readily understood from the description of the embodiments thereof. Attached Figure Description

[0016] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements, and wherein:

[0017] Figure 1 This is a diagram illustrating a lane departure prevention device according to an embodiment of the present invention and a vehicle (this vehicle) equipped with the lane departure prevention device.

[0018] Figure 2 This diagram illustrates a scenario where the vehicle is moving in a direction that deviates from its lane.

[0019] Figure 3 This is a diagram illustrating a scenario where the predicted vehicle position reaches the first predicted position determination line.

[0020] Figure 4 This diagram illustrates a scenario where steering force is applied to the vehicle via automatic steering control to return the vehicle to its lane.

[0021] Figure 5 This is a diagram illustrating a scenario where the predicted vehicle position reaches the second predicted position determination line.

[0022] Figure 6 This is a diagram showing a road with guardrails on the left side of the lane.

[0023] Figure 7 This is a flowchart illustrating the routines performed by the lane departure prevention device according to an embodiment of the present invention.

[0024] Figure 8 This is a flowchart illustrating the routines performed by the lane departure prevention device according to an embodiment of the present invention. Detailed Implementation

[0025] Hereinafter, a lane departure prevention device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the lane departure prevention device 10 according to the embodiment of the present invention is mounted on the vehicle 100.

[0026] <ECU>

[0027] The lane departure prevention device 10 includes an ECU 90 as a control device. ECU is short for Electronic Control Unit. The ECU 90 has a microcomputer as its main component. The microcomputer includes a CPU, ROM, RAM, non-volatile memory, and interfaces. The CPU performs various functions by executing instructions, programs, or routines stored in the ROM.

[0028] <Driver, etc.>

[0029] In addition, the vehicle 100 is equipped with a drive unit 21, a braking unit 22 and a steering unit 23.

[0030] <Driver>

[0031] The drive unit 21 is a device that outputs the driving torque (driving force) applied to the vehicle 100 to make the vehicle 100 move, such as an internal combustion engine or a motor. The drive unit 21 is electrically connected to the ECU 90. The ECU 90 can control the driving torque output from the drive unit 21 by controlling the operation of the drive unit 21.

[0032] <Brake Device>

[0033] Braking device 22 is a device that outputs braking torque (braking force) to brake the vehicle 100. Braking device 22 is electrically connected to ECU 90. ECU 90 can control the braking torque output from braking device 22 by controlling the operation of braking device 22.

[0034] <Steering gear>

[0035] The steering device 23 is a device that outputs steering torque (steering force) applied to the vehicle 100 for steering purposes, such as a power steering system. The steering device 23 is electrically connected to the ECU 90. The ECU 90 can control the steering torque output from the steering device 23 by controlling the operation of the steering device 23.

[0036] <Sensors, etc.>

[0037] Furthermore, the vehicle 100 is equipped with an accelerator pedal 31, an accelerator pedal operation sensor 32, a brake pedal 33, a brake pedal operation sensor 34, a steering wheel 35, a steering shaft 36, a steering angle sensor 37, a steering torque sensor 38, a grip status detection device 40, a vehicle motion detection device 50, a surrounding information detection device 60, a driver posture acquisition device 70, and an alarm device 80.

[0038] <Accelerator pedal operation sensor>

[0039] The accelerator pedal operation amount sensor 32 is a sensor that detects the operation amount of the accelerator pedal 31. The accelerator pedal operation amount sensor 32 is electrically connected to the ECU 90. The accelerator pedal operation amount sensor 32 sends the detected operation amount information of the accelerator pedal 31 to the ECU 90. The ECU 90 uses this information to obtain the operation amount of the accelerator pedal 31 as the accelerator pedal operation amount AP.

[0040] Based on the accelerator pedal operation amount AP and the vehicle speed 100 (vehicle speed SPD), ECU90 calculates the required drive torque (required drive force). The required drive torque is the drive torque that the drive unit 21 is required to output. ECU90 controls the operation of drive unit 21 to output the required drive torque.

[0041] <Brake pedal operation sensor>

[0042] The brake pedal operation amount sensor 34 is a sensor that detects the operation amount of the brake pedal 33. The brake pedal operation amount sensor 34 is electrically connected to the ECU 90. The brake pedal operation amount sensor 34 sends the detected brake pedal operation amount information to the ECU 90. Based on this information, the ECU 90 obtains the brake pedal operation amount BP as the brake pedal operation amount BP.

[0043] Based on the brake pedal operation amount BP, ECU90 calculates the required braking torque (required braking force). The required braking torque is the braking torque that the braking device 22 is required to output. ECU90 controls the operation of the braking device 22 to output the required braking torque.

[0044] <Steering Angle Sensor>

[0045] The steering angle sensor 37 is a sensor that detects the rotation angle of the steering shaft 36 relative to the neutral position. The steering angle sensor 37 is electrically connected to the ECU 90. The steering angle sensor 37 sends the detected rotation angle information of the steering shaft 36 to the ECU 90. The ECU 90 obtains the rotation angle of the steering shaft 36 as the steering angle θ based on this information.

[0046] <Steering Torque Sensor>

[0047] The steering torque sensor 38 is a sensor that detects the torque input by the driver DR of the vehicle 100 to the steering shaft 36 via the steering wheel 35. The steering torque sensor 38 is electrically connected to the ECU 90. The steering torque sensor 38 sends the detected torque information to the ECU 90. Based on this information, the ECU 90 obtains the torque input by the driver DR to the steering shaft 36 via the steering wheel 35 (driver input torque).

[0048] <Holding Status Detection Device>

[0049] The grip state detection device 40 is a device for detecting the grip state of the driver DR on the steering wheel 35. In this example, it is a touch sensor 41 installed on the steering wheel 35.

[0050] <Touch Sensor>

[0051] Touch sensor 41 is a sensor that detects when driver DR touches steering wheel 35. Touch sensor 41 is electrically connected to ECU 90. When touch sensor 41 detects that driver DR has touched steering wheel 35, it sends information (signals) related to the portion of steering wheel 35 touched by driver DR to ECU 90. ECU 90 can identify the portion of steering wheel 35 touched by driver DR based on this information (signals) and determine whether driver DR is in a state where he / she can perform driving operations on vehicle 100 based on the identified portion of steering wheel 35. For example, a state in which driver DR can perform driving operations on vehicle 100 is when driver DR holds the appropriate portion of steering wheel 35 with both hands for driving operations.

[0052] <Vehicle Motion Detection Device>

[0053] The vehicle motion detection device 50 is a device for detecting the motion of the vehicle 100. In this example, it includes a vehicle speed detection device 51, a longitudinal acceleration sensor 52, a lateral acceleration sensor 53, and a yaw rate sensor 54.

[0054] <Vehicle speed detection device>

[0055] The vehicle speed detection device 51 is a device for detecting the driving speed (vehicle speed) of the vehicle 100, such as a wheel speed sensor. The vehicle speed detection device 51 is electrically connected to the ECU 90. The vehicle speed detection device 51 sends the detected vehicle speed information of the vehicle 100 to the ECU 90. The ECU 90 obtains the vehicle speed SPD of the vehicle 100 based on this information.

[0056] Based on the acquired steering angle θ, driver input torque, and vehicle speed SPD, ECU90 calculates the required steering torque. The required steering torque is the steering torque required to be output by steering device 23. Except when performing automatic steering control as described later, ECU90 controls the operation of steering device 23 by outputting the required steering torque from steering device 23.

[0057] <Longitudinal Accelerometer>

[0058] The longitudinal acceleration sensor 52 is a sensor that detects the longitudinal acceleration of the vehicle 100. The longitudinal acceleration sensor 52 is electrically connected to the ECU 90. The longitudinal acceleration sensor 52 sends the detected acceleration information to the ECU 90. Based on this information, the ECU 90 obtains the longitudinal acceleration of the vehicle 100 as the longitudinal acceleration GX.

[0059] <Transverse Accelerometer>

[0060] The lateral acceleration sensor 53 is a sensor that detects the lateral (width) acceleration of the vehicle 100. The lateral acceleration sensor 53 is electrically connected to the ECU 90. The lateral acceleration sensor 53 sends the detected acceleration information to the ECU 90. Based on this information, the ECU 90 obtains the lateral acceleration of the vehicle 100 as the lateral acceleration GY.

[0061] <Yaw Rate Sensor>

[0062] Yaw rate sensor 54 is a sensor that detects the yaw rate YR of the vehicle 100. Yaw rate sensor 54 is electrically connected to ECU 90. Yaw rate sensor 54 sends the detected yaw rate YR information to ECU 90. ECU 90 obtains the yaw rate YR of the vehicle 100 based on this information. The yaw rate YR is used, for example, to determine the steering force applied to the vehicle 100 when the vehicle 100 is automatically rotated by automatic steering control as described later.

[0063] <Surrounding Information Detection Device>

[0064] The surrounding information detection device 60 is a device for detecting information about the surroundings of the vehicle 100. In this example, it includes an image sensor 61 and an electromagnetic wave sensor 62. The image sensor 61 is, for example, a camera. The electromagnetic wave sensor 62 is, for example, a radar sensor (millimeter-wave radar, etc.). In addition, the surrounding information detection device 60 may also include an ultrasonic sensor (gap sonar) or an optical sensor (LiDAR).

[0065] <Image Sensor>

[0066] Image sensor 61 is electrically connected to ECU 90. Image sensor 61 captures images of the surroundings of vehicle 100 and sends information related to the captured images to ECU 90. ECU 90 can then obtain surrounding information (surroundings detection information INF_D) based on this information (image information).

[0067] <Electronic Wave Sensor>

[0068] The radio wave sensor 62 is electrically connected to the ECU 90. The radio wave sensor 62 transmits radio waves and receives radio waves reflected from objects (reflected waves). The radio wave sensor 62 sends information (detection results) related to the transmitted and received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 62 detects objects present in the vicinity of the vehicle 100 and sends information (detection results) related to the detected objects to the ECU 90. The ECU 90 can then obtain information (peripheral detection information INF_D) related to the objects present in the vicinity of the vehicle 100 based on this information (radio wave information).

[0069] <Driver posture acquisition device>

[0070] The driver posture acquisition device 70 is a device for detecting the consciousness state of the driver DR, and in this example, it is the driver monitoring camera 71. The driver monitoring camera 71 is installed inside the vehicle 100 so as to face the driver DR in a manner that can capture the driver DR's face.

[0071] <Driver monitoring camera>

[0072] The driver monitoring camera 71 is a camera that captures images of the driver DR's face. The driver monitoring camera 71 is electrically connected to the ECU 90. The driver monitoring camera 71 sends information (image data) related to the captured image of the driver DR's face to the ECU 90. The ECU 90 can determine, based on this information, whether the driver DR is in a state where he / she can operate the vehicle 100. For example, the state in which the driver DR can operate the vehicle 100 is when the driver DR is facing the steering wheel 35 and the driver DR's eyes are open (i.e., the driver DR is awake).

[0073] Alarm Device

[0074] The alarm device 80 is used to notify the driver DR that "the vehicle 100 may deviate from lane LN". In this example, it includes a display device 81, an audio device 82 and a vibration device 83.

[0075] <Display Device>

[0076] Display device 81 is a device for displaying images, such as a combination instrument cluster, head-up display (HUD), or human-machine interface (HMI). Display device 81 is electrically connected to ECU 90. ECU 90 enables display device 81 to display various images.

[0077] <Audio Equipment>

[0078] The audio device 82 is a device that outputs broadcast sounds, buzzer sounds, and other electronic sounds; for example, it is a loudspeaker or a buzzer. The audio device 82 is electrically connected to the ECU 90. The ECU 90 enables the audio device 82 to output various sounds or electronic sounds.

[0079] <Vibration Device>

[0080] Vibration device 83 is a device that applies vibration to the driver's DR, such as a vibrator built into the steering wheel 35 or the driver's seat. Vibration device 83 is electrically connected to ECU 90. ECU 90 can apply vibration to the driver's DR by activating vibration device 83.

[0081] <Summary of Lane Departure Prevention Device Operation>

[0082] Next, a general overview of the operation of the lane departure prevention device 10 will be explained. For example, in situations such as... Figure 2 As shown, after vehicle 100 begins to move toward the left dividing line 201 (left dividing line 201L), if driver DR does not perform appropriate driving operations, vehicle 100 will deviate from lane LN.

[0083] Therefore, when the lane departure prevention device 10 determines that the vehicle 100 may deviate from lane LN, it executes lane departure prevention control to prevent the vehicle 100 from deviating from lane LN. In this example, the lane departure prevention control includes automatic steering control and warning control.

[0084] Automatic steering control is the control that automatically applies steering force to the vehicle 100 as it is about to deviate from lane LN, so that the vehicle 100 returns to (is in) lane LN. Warning control is the control that provides an alert to the driver DR informing them that "the vehicle 100 may deviate from lane LN". The automatic steering control and warning control described above will be explained below.

[0085] Furthermore, in this example, the alarm under alarm control is triggered by at least one of the following: an image display on the display device 81 indicating that the vehicle 100 may deviate from lane LN and / or the illumination of a light on the display device 81; an audio output from the audio device 82 indicating that the vehicle 100 may deviate from lane LN and / or the output of a buzzer sound from the audio device 82; and vibration of the steering wheel 35 and / or the driver's seat via the vibration device 83.

[0086] <Automatic steering control>

[0087] The lane departure prevention device 10 performs automatic steering control when the automatic steering execution condition C_LDP is met. In this example, the automatic steering execution condition C_LDP is met when the automatic steering permission condition C_AS is met and the lane departure condition (first departure condition C_D1) is met.

[0088] The automatic steering allowance condition C_AS is a condition used to determine whether the requirements for performing automatic steering control in an appropriate manner are met. In this example, the automatic steering allowance condition C_AS is established when the lane departure prevention device 10 detects the lane divider 200 and the current vehicle speed SPD_N (the current vehicle speed SPD of the vehicle 100) is within the predetermined speed range R_TH and the driver DR has not performed an overtaking operation.

[0089] Lane dividers 200 divide lane LN, which in this example are the dividing line 201 on the left side of lane LN (left dividing line 201L), the dividing line 201 on the right side of lane LN (right dividing line 201R), the road end such as grass or dirt on the left side of lane LN (left road end), the road end such as grass or dirt on the right side of lane LN (right road end), the guardrail on the left side of lane LN (left guardrail), and the guardrail on the right side of lane LN (right guardrail).

[0090] The lane departure prevention device 10 can detect the left dividing line 201L, the right dividing line 201R, the left end of the road, the right end of the road, the left guardrail, and the right guardrail based on the surrounding detection information INF_D.

[0091] Additionally, overtaking operations are, for example, operations on the steering wheel 35 used to prevent the vehicle 100 from deviating from lane LN (lane deviation of the vehicle 100).

[0092] On the other hand, the first deviation condition C_D1 is as follows Figure 3 This condition is met when the position of the vehicle 100 (predicted vehicle position POS_P) reaches the first predicted position determination line LIN1_P after a predetermined time T, as shown. In this example, the predetermined time T is a time that is pre-determined as appropriate for determining the start timing of lane departure prevention control.

[0093] The first predicted position determination line LIN1_P is along lane divider 200 (in... Figure 3 In the example shown, the line extends from the left dividing line 201L. The lane departure prevention device 10 sets the first predicted position determination line LIN1_P in the following manner: if automatic steering control is started when the predicted vehicle position POS_P reaches the first predicted position determination line LIN1_P, the vehicle 100 can avoid lane departure through automatic steering control while ensuring the driving safety of the vehicle 100.

[0094] When setting the first predicted position determination line LIN1_P, the lane departure prevention device 10 considers the distance between the lane divider 200 and the current position of the vehicle 100 (current vehicle position POS_N) (dragrer distance DIS_200), the current vehicle speed SPD (current vehicle speed SPD_N), the steering performance of the steering device 23, the permissible lateral acceleration of the vehicle 100, and the type of lane divider 200 (whether the lane divider 200 is a dividing line 201, a flat object such as the end of the road, or a three-dimensional structure such as a guardrail).

[0095] Furthermore, the lane departure prevention device 10 obtains a predicted vehicle position POS_P based on the current vehicle position POS_N (the current position of the vehicle 100), the current vehicle speed SPD_N (the current vehicle speed SPD), the current lateral acceleration GY_N (the current lateral acceleration GY of the vehicle 100), and a predetermined time T. Specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P by calculation based on the following formula (1) based on the current vehicle position POS_N, the current vehicle speed SPD_N, the current lateral acceleration GY_N, and the predetermined time T.

[0096] POS_P=POS_N+SPD_N×T+1 / 2×GY_N×T 2 ···(1)

[0097] Furthermore, in this example, the lane departure prevention device 10 obtains the current vehicle position POS_N based on the surrounding detection information INF_D and the position of the lane divider 200.

[0098] When automatic steering control is initiated, the lane departure prevention device 10 controls the operation of the steering device 23 to apply steering force to the vehicle 100 in a manner that causes the vehicle 100 to return to lane LN. Thus, as Figure 4 As shown, this vehicle is returning to lane LN from lane 100.

[0099] Furthermore, as described above, the lane departure prevention device 10 determines whether the first deviation condition C_D1 is met based on whether the predicted vehicle position POS_P reaches the first predicted position determination line LIN1_P. However, it can also be configured to set a determination line other than the first predicted position determination line LIN1_P (the first current position determination line LIN1_N), and determine whether the first deviation condition C_D1 is met based on whether the current vehicle position POS_N reaches the first current position determination line LIN1_N.

[0100] In this case, the lane departure prevention device 10 sets a first predicted position determination line LIN1_P as described above, and in parallel obtains the distance (predicted lateral movement distance DIS_P) that the vehicle 100 moves in the lateral direction during the period from the current time point to the elapsed predetermined time T. The line obtained by moving the first predicted position determination line LIN1_P towards the lane LN side by the predicted lateral movement distance DIS_P is set as the first current position determination line LIN1_N.

[0101] Furthermore, the lane departure prevention device 10 calculates the predicted lateral movement distance DIS_P based on the following formula (2) which is based on the current vehicle speed SPD_N, the current lateral acceleration GY_N, and the predetermined time T.

[0102] DIS_P = SPD_N×T + 1 / 2×GY_N×T 2 ···(2)

[0103] <Alarm Control>

[0104] In addition, the lane departure prevention device 10 performs alarm control when the alarm execution condition C_LDA is met.

[0105] Here, the alarm execution condition C_LDA is established if the lane departure condition (second departure condition C_D2) is met. The second departure condition C_D2 is established if... Figure 5 The prediction holds true when the vehicle position POS_P reaches the second prediction position decision line LIN2_P, as shown.

[0106] The second predicted position determination line LIN2_P is along lane divider 200 (in Figure 5 The example shown is a line extending from the left dividing line 201L, and is as follows: if alarm control is initiated when the predicted vehicle position POS_P reaches this line, the driver DR will notice the alarm under the alarm control, and the driver DR can sufficiently avoid lane departure of the vehicle 100 by operating the steering wheel 35.

[0107] Therefore, the lane departure prevention device 10 sets the second predicted position determination line LIN2_P in the following manner: if alarm control is started when the predicted vehicle position POS_P reaches the second predicted position determination line LIN2_P, the lane departure of the vehicle 100 can be avoided by the lane departure avoidance operation (driving operation to avoid the vehicle 100 from lane LN) performed by the driver DR while ensuring the driving safety of the vehicle 100.

[0108] When setting the second predicted position determination line LIN2_P, the lane departure prevention device 10 considers the distance of the lane divider 200 (the distance between the lane divider 200 and the current vehicle position POS_N), the current vehicle speed SPD_N, the driver DR's driving operation ability (especially the driver DR's steering wheel operation ability), and the type of lane divider 200 (whether the lane divider 200 is a dividing line 201, a flat object at the end of the road, or a three-dimensional structure such as a guardrail).

[0109] Furthermore, when automatic steering control is not executed, the lane departure prevention device 10 determines whether the alarm execution condition C_LDA is met based on the actual driving state of the vehicle 100. More specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P based on the actual driving state of the vehicle 100. More specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P based on the current vehicle position POS_N, the current vehicle speed SPD_N, the current lateral acceleration GY_N, and the predetermined time T, as described above. Specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P by calculation based on the above formula (1) based on the current vehicle position POS_N, the current vehicle speed SPD_N, the current lateral acceleration GY_N, and the predetermined time T.

[0110] On the other hand, when the lane departure prevention device 10 is performing automatic steering control, it determines whether the alarm execution condition C_LDA is met based on the driving state of the vehicle 100 achieved through automatic steering control. More specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P based on the driving state of the vehicle 100 achieved through automatic steering control. More specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P based on the current vehicle position POS_N (the current position of the vehicle 100), the current vehicle speed SPD_N (the current vehicle speed SPD), the predicted lateral acceleration GY_P (the lateral acceleration GY of the vehicle 100 achieved through automatic steering control), and a predetermined time T. Specifically, the lane departure prevention device 10 obtains the predicted vehicle position POS_P by calculation based on the following formula (3) based on the current vehicle position POS_N, the current vehicle speed SPD_N, the predicted lateral acceleration GY_P, and the predetermined time T.

[0111] POS_P=POS_N+SPD_N×T+1 / 2×GY_P×T 2 ···(3)

[0112] Additionally, in this example, the deviation condition C_DP can be avoided if the autopilot enable condition C_AS is met.

[0113] Furthermore, as described above, the lane departure prevention device 10 determines whether the second deviation condition C_D2 is met by predicting whether the vehicle position POS_P reaches the second predicted position determination line LIN2_P. However, it can also be configured to set a determination line other than the second predicted position determination line LIN2_P (the second current position determination line LIN2_N), and determine whether the second deviation condition C_D2 is met by whether the current vehicle position POS_N reaches the second current position determination line LIN2_N.

[0114] In this case, the lane departure prevention device 10 sets a second predicted position determination line LIN2_P as described above, and obtains a predicted lateral movement distance DIS_P in parallel with it. The line obtained by moving the second predicted position determination line LIN2_P towards lane LN by the predicted lateral movement distance DIS_P is set as the second current position determination line LIN2_N.

[0115] In addition, in this case, the lane departure prevention device 10 calculates the predicted lateral movement distance DIS_P based on the above formula (2) which is based on the current vehicle speed SPD_N, the current lateral acceleration GY_N and the predetermined time T, without performing automatic steering control.

[0116] On the other hand, when the lane departure prevention device 10 is performing automatic steering control, it calculates the predicted lateral movement distance DIS_P based on the following formula (4) based on the current vehicle speed SPD_N, the predicted lateral acceleration GY_P and the predetermined time T.

[0117] DIS_P = SPD_N × T + 1 / 2 × GY_P × T 2 ···(4)

[0118] <Effect>

[0119] According to the lane departure prevention device 10, the first predicted position determination line LIN1_P and the second predicted position determination line LIN2_P are set considering various factors. Therefore, sometimes the predicted vehicle position POS_P reaches the first predicted position determination line LIN1_P first, and sometimes it reaches the second predicted position determination line LIN2_P first. Therefore, when the predicted vehicle position POS_P reaches the second predicted position determination line LIN2_P, sometimes the predicted vehicle position POS_P reaches the first predicted position determination line LIN1_P, and sometimes it does not reach the first predicted position determination line LIN1_P. That is, when the predicted vehicle position POS_P reaches the second predicted position determination line LIN2_P, sometimes automatic steering control is being executed, and sometimes it is not.

[0120] Typically, when autopilot control is in operation, the lateral acceleration GY changes due to the steering force applied to the vehicle 100 via autopilot control. Therefore, when obtaining the predicted vehicle position POS_P after a predetermined time T, the method of obtaining the predicted vehicle position POS_P using the lateral acceleration GY implemented through autopilot control yields a more accurate predicted vehicle position POS_P compared to obtaining the predicted vehicle position POS_P using the lateral acceleration GY at that time point (current lateral acceleration GY_N). Therefore, when autopilot control is in operation, this method of obtaining the predicted vehicle position POS_P using the lateral acceleration GY implemented through autopilot control reduces the likelihood that the driver DR will become annoyed by alarms under alarm control.

[0121] According to the lane departure prevention device 10, when autopilot control is not in effect, the predicted vehicle position POS_P is obtained using the current lateral acceleration GY_N; however, when autopilot control is in effect, the predicted vehicle position POS_P is obtained using the predicted lateral acceleration GY_P. Therefore, it is possible to reduce the likelihood that the driver (DR) will become annoyed by the alarm under warning control.

[0122] Furthermore, the lane departure prevention device 10 can be configured to consider whether the driver DR is capable of driving the vehicle 100 when setting the second predicted position determination line LIN2_P. More specifically, the lane departure prevention device 10 can be configured to set the second predicted position determination line LIN2_P at a position away from lane LN when the driver DR is capable of driving the vehicle 100, compared to when the driver DR is not capable of driving the vehicle 100. Furthermore, the state where the driver DR is capable of driving the vehicle 100 is defined as the driver DR holding the steering wheel 35 with both hands at a suitable position for driving, the driver DR facing the steering wheel 35, and the driver DR's eyes open (i.e., the driver DR is awake).

[0123] Furthermore, the lane departure prevention device 10 can be configured to consider whether the lane divider 200 is a three-dimensional structure 202 when setting the second predicted position determination line LIN2_P. More specifically, the lane departure prevention device 10 can be configured to set the second predicted position determination line LIN2_P closer to lane LN when the lane divider 200 is a three-dimensional structure 202, compared to when the lane divider 200 is not a three-dimensional structure 202. Here, as... Figure 6As shown, the three-dimensional structure 202 is, for example, a guardrail. The lane departure prevention device 10 can detect the three-dimensional structure 202 based on the surrounding detection information INF_D.

[0124] Furthermore, the lane departure prevention device 10 can be configured to consider whether there is an object 300 outside the lane divider 200 that could potentially contact the vehicle 100 when setting the second predicted position determination line LIN2_P. More specifically, the lane departure prevention device 10 can be configured to set the second predicted position determination line LIN2_P closer to lane LN when there is an object 300 outside the lane divider 200 that could potentially contact the vehicle 100, compared to when there is no object 300 outside the lane divider 200 that could potentially contact the vehicle 100. Here, as Figure 2 As shown, object 300 includes pedestrian 301, other vehicles 302, etc. Lane departure prevention device 10 can detect object 300 based on surrounding detection information INF_D. When object 300 is detected, for example, if object 300 is within a predetermined range in front of the vehicle 100's direction of travel, lane departure prevention device 10 determines that there is an object 300 outside the lane divider 200 that may come into contact with the vehicle 100.

[0125] <How the Lane Departure Prevention Device Works>

[0126] Next, the specific operation of the lane departure prevention device 10 will be explained. The CPU of the ECU 90 of the lane departure prevention device 10 executes according to a predetermined calculation cycle. Figure 7 The example shown. Therefore, when the predetermined timing is reached, the CPU starts from... Figure 7 The example shown begins processing at step 700, proceeding to step 705 to obtain the predicted vehicle position POS_P. Next, the CPU proceeds to step 710 to set the first predicted position determination line LIN1_P. Then, the CPU proceeds to step 715 to determine whether the first deviation condition C_D1 is met.

[0127] If the CPU determines "yes" in step 715, the process proceeds to step 720 to determine whether the automatic steering permission condition C_AS is met.

[0128] If the CPU determines "yes" in step 720, it proceeds to step 725 to execute automatic steering control. Then, the CPU proceeds to step 795, temporarily terminating the current routine.

[0129] On the other hand, if the CPU determines "no" in step 715 or step 720, the process will proceed directly to step 795, temporarily ending the routine.

[0130] Then, the CPU executes according to the predetermined calculation cycle. Figure 8 The example shown. Therefore, when the predetermined timing is reached, the CPU starts from... Figure 8 The routine shown begins processing at step 800, which then proceeds to step 805, where it is determined whether autopilot control is being performed.

[0131] If the CPU determines "yes" in step 805, it proceeds to step 810 to obtain the predicted vehicle position POS_P by performing the calculation based on equation (3) above (using the calculation of the predicted lateral acceleration GY_P). Then, the CPU proceeds to step 820.

[0132] On the other hand, if the CPU determines "no" in step 805, it proceeds to step 815 to obtain the predicted vehicle position POS_P by performing the calculation based on the above formula (1) (using the calculation of the current lateral acceleration GY_N). Then, the CPU proceeds to step 820.

[0133] When the CPU advances the process to step 820, it sets the second predicted position determination line LIN2_P. Then, the CPU advances the process to step 825 to determine whether the alarm execution condition C_LDA is met.

[0134] If the CPU determines "yes" in step 825, it proceeds to step 830 to execute alarm control. Then, the CPU proceeds to step 895, temporarily terminating the current routine.

[0135] On the other hand, if the CPU determines "no" in step 825, the process proceeds directly to step 895, temporarily terminating the current routine. In this case, alarm control is not performed.

[0136] The above describes the specific operation of the lane departure prevention device 10.

[0137] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention.

Claims

1. A lane departure prevention device, The lane departure prevention device includes a control unit that performs alarm control and automatic steering control. The alarm control is used to notify the driver of the vehicle that the vehicle may be deviating from its lane. The automatic steering control is used to automatically apply steering force to the vehicle to keep it within its lane if it is likely to deviate from the lane. The control device is configured such that, If the conditions for automatic steering are met, the automatic steering control will be executed. If the automatic steering control is not executed, but the alarm execution conditions are met based on the actual driving state of the vehicle, the alarm control is executed. While the automatic steering control is being executed, if the alarm execution condition is met based on the vehicle's driving state determined by the automatic steering control, the alarm control is executed. The control device is configured such that, The autopilot execution condition is met when both the autopilot permission condition and the first deviation condition are met. The automatic steering permission conditions are met when lane dividers are detected, the vehicle's current speed is within a predetermined speed range, and the driver of the vehicle does not perform any steering wheel operation (i.e., overtaking) to prevent the vehicle from deviating from the lane. The first deviation condition is met when the predicted position of the vehicle, i.e., the vehicle position, reaches the first predicted position determination line after a predetermined time. The first predicted position determination line is a line extending along the lane divider. The first predicted position determination line is set such that if the automatic steering control is initiated when the predicted vehicle position reaches the first predicted position determination line, the automatic steering control can prevent the vehicle from deviating from its lane while ensuring the vehicle's driving safety. The alarm execution condition is met if the second deviation condition is met. The second deviation condition is met when the predicted vehicle position reaches the second predicted position determination line. The second predicted position determination line is a line extending along the lane divider and is configured such that if the alarm control is initiated when the predicted vehicle position reaches the second predicted position determination line, lane departure of the vehicle can be avoided by driving operations performed by the driver to prevent the vehicle from deviating from its lane while ensuring the driving safety of the vehicle.

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