JP4565420B2 - Lane departure prevention device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a lane departure prevention apparatus that intermittently applies steering torque and pseudo sound to notify a driver of a lane departure of a host vehicle.
[0002]
[Prior art]
Conventionally, it is known to predict a lane departure of a vehicle and warn a driver with a false sound. Japanese Patent Application Laid-Open No. 11-34774 proposes a technique for predicting a lane departure of a vehicle and vibrating the steering system within a range in which no vehicle behavior is generated.
[0003]
[Problems to be solved by the invention]
However, when both the excitation of the steering torque and the warning by imitation sound are used together, if these are individually controlled, the judgment of the driver who receives the warning is delayed or uncomfortable.
[0004]
The present invention has been made in view of the above-mentioned problems, and its object is not to delay the judgment of the driver who received the warning or to give a sense of incongruity when warning of a lane departure is made by combining the application of steering torque and a warning by imitation sound. A lane departure prevention device is provided.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, a lane departure prevention apparatus according to the present invention includes a lateral position detection means for detecting a relative lateral position between a lane edge and the host vehicle, and a relative lateral position detected by the lateral position detection means. Based on this, the time until the host vehicle reaches the lane edge is measured, and when the arrival time is shorter than the first predetermined time, intermittent steering is performed in the direction opposite to the lane edge where the host vehicle is approaching. A departure prevention means for performing first alarm control that adds torque and outputs intermittent false sounds in synchronization with the addition of the steering torque , the departure prevention means until the host vehicle reaches the lane edge. When the time is shorter than the second predetermined time shorter than the first predetermined time, the second alarm control is performed to add a continuous steering torque in the direction opposite to the lane edge where the host vehicle is approaching, Steering added in the second alarm control Torque and the upper limit value of the steering torque applied at the first alarm control is set to be higher deviation of the yaw angle is small small for lane edge of the vehicle.
[0006]
The lane departure prevention apparatus according to the present invention includes a lateral position detection unit that detects a relative lateral position between a lane edge and the host vehicle, and the host vehicle is based on the relative lateral position detected by the lateral position detection unit. Measure the time to reach the lane edge, and when the arrival time is shorter than the first predetermined time, add intermittent steering torque in the opposite direction to the lane edge where the host vehicle is approaching, Departure prevention means for performing first alarm control that outputs intermittent pseudo-synchronization in synchronization with the addition of the steering torque, and the departure prevention means has a time until the host vehicle reaches the lane edge. When the vehicle is shorter than the second predetermined time shorter than the predetermined time, the second alarm control is performed to add continuous steering torque in the direction opposite to the lane edge where the host vehicle is approaching. The steering torque to be applied Yaw angle with respect to the end is released before the zero.
[0008]
Preferably, the lateral position detection means further includes a yaw angle detection means for detecting a yaw angle with respect to a lane edge of the host vehicle, and the departure prevention means has a predetermined yaw angle detected by the yaw angle detection means. When the value is equal to or greater than the value, the time until the yaw angle becomes zero is predicted, and the addition of the steering torque is canceled before the predicted time elapses.
[0009]
Preferably, the lateral position detecting means further includes departure detecting means for detecting that the own vehicle has deviated from the lane edge, and the departure preventing means is configured such that the own vehicle deviates from the lane. If so, the addition of the steering torque is continued until the subject vehicle avoids lane departure regardless of the magnitude of the yaw angle.
[0010]
Preferably, the vehicle further includes steering detection means for detecting steering by the driver, and the departure prevention means continues the steering detected by the steering detection means for a predetermined time or more to the lane edge where the host vehicle is approaching. The steering torque is gradually released.
[0011]
Preferably, steering torque detection means for detecting steering torque by a driver is further provided, and the departure prevention means holds the steering torque detected by the steering torque detection means at a predetermined torque or more for a predetermined time or more. Sometimes, the addition of the steering torque is gradually released.
[0012]
Preferably, the vehicle further includes steering angle detection means for detecting a steering angle by the driver, wherein the departure prevention means is configured such that the steering angle detected by the steering angle detection means is a lane edge where the host vehicle is approaching. When steering in the opposite direction at a predetermined angle or more, the addition of the steering torque is gradually released.
[0013]
Preferably, the vehicle further includes operation detection means for detecting a direction instruction operation by a driver, and the departure prevention means performs the direction instruction operation detected by the operation detection means to a lane edge where the host vehicle is approaching. The steering torque is gradually released.
[0014]
【The invention's effect】
As described above, according to the present invention, when the application of the steering torque in the first alarm control and the output of the pseudo sound are synchronized, the application of the steering torque and the alarm sound are used in combination to warn the lane departure. The judgment speed of the driver who received the warning can be increased, and the uncomfortable feeling can be reduced.
[0015]
According to the first aspect of the present invention, the steering torque added in the second alarm control is set to the upper limit value of the steering torque added in the first alarm control, so that the smaller the deviation of the yaw angle with respect to the lane edge of the own vehicle, the smaller. By setting to, overshoot during control can be prevented and controllability can be improved.
[0016]
According to the second aspect of the present invention, the steering torque added in the second alarm control is released before the yaw angle with respect to the lane edge of the host vehicle becomes zero. Overshoot can be prevented and controllability can be improved.
[0017]
According to the invention of claim 3 , when the yaw angle is equal to or larger than a predetermined value, the time until the yaw angle becomes zero is predicted, and the addition of the steering torque is canceled before the predicted time elapses. After that, since it is left to the driver's operation, overshoot during control can be prevented and controllability can be improved.
[0018]
According to the invention of claim 4 , when the own vehicle deviates from the lane, the addition of the steering torque is continued until the own vehicle avoids the lane departure regardless of the magnitude of the yaw angle. Lane departure can be avoided reliably.
[0019]
According to the invention of claim 5 , when the steering by the driver continues to the end of the lane where the host vehicle is approaching for a predetermined time or longer, the addition of the steering torque is gradually released to By giving priority, it is possible to reduce the hunting in control and the uncomfortable feeling experienced by the driver.
[0020]
According to the invention of claim 6, the steering torque by the driver, when it is held for a predetermined time or more at least a predetermined torque by releasing gradually adding the steering torque, give priority to the intention of the driver, the control Hunting and driver discomfort can be reduced.
[0021]
According to the invention of claim 7 , when the steering angle by the driver is steered at a predetermined angle or more in the direction opposite to the lane edge where the host vehicle is approaching, the addition of the steering torque is gradually released. As a result, priority can be given to the driver's intention to reduce hunting in control and a sense of discomfort experienced by the driver.
[0022]
According to the eighth aspect of the present invention, the driver's intention is prioritized by gradually canceling the addition of the steering torque when the direction instruction operation by the driver is performed at the lane edge where the host vehicle is approaching. , Hunting in control and the uncomfortable feeling experienced by the driver can be reduced.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an example in which the lane departure prevention apparatus according to the present invention is mounted on an automobile which is a typical vehicle will be described in detail with reference to the accompanying drawings.
[0024]
The embodiment described below is an example as means for realizing the present invention, and the present invention can be applied to a modified or modified embodiment described below without departing from the spirit of the present invention.
[0025]
FIG. 1 is a diagram showing a system configuration of an automobile on which a lane departure prevention apparatus according to this embodiment is mounted.
[0026]
In the automobile 1 shown in FIG. 1, reference numeral 2 denotes a controller that performs overall control of the entire steering apparatus. Reference numeral 3 denotes an imaging device such as a CCD (Charge Coupled Device) camera that images the imaging area R in front of the automobile 1. Instead of the CCD camera 3, an antenna for detecting a magnetic marker embedded on the road surface may be provided at the lower part of the vehicle body. 4 is a yaw rate sensor that detects the yaw rate of the automobile 1, 5 is a vehicle speed sensor that detects the vehicle speed of the automobile 1, 6 is a winker switch for a driver to perform a direction instruction operation, and 7 is an example of a mechanism that actually steers the automobile 1. A steering actuator such as a motor for driving a steering shaft connected to the steering wheel 8 to apply a steering torque. A steering sensor 9 detects a steering torque and a steering angle driven by a driver or a steering actuator 7. Reference numeral 10 denotes a speaker that emits an alarm sound such as a false sound in order to notify the driver of a lane departure.
[0027]
FIG. 2 is a block diagram of the controller shown in FIG. 1, and each block represented inside the controller 2 represents a control operation performed by the controller 2 by a flow of an input signal. An actual control process by the controller 2 is executed by a CPU (not shown) according to software stored in advance in a ROM (not shown) or the like (details will be described later).
[0028]
As shown in FIG. 2, the controller 2 detects the lateral deviation with respect to the lane edge L (see FIG. 1) of the automobile 1 based on the image of the front imaging area captured by the CCD camera 3, and the vehicle speed. The lateral speed of the automobile 1 is calculated from the captured image, and the yaw angle of the automobile 1 is estimated from the lateral deviation.
[0029]
Further, a predicted departure time TLD until reaching the lane L is calculated from the lateral deviation and the lateral speed. Further, the degree of urgency until an alarm is issued is determined based on whether or not the estimated departure time TLD is equal to or less than the first time T1 or the second time T2, and the presence or absence of the operation of the blinker switch 6 and the steering detected by the steering sensor 9 are determined. A driver's intention to deviate from the lane is determined from the torque and the steering angle θ, and it is determined from the lateral deviation, the yaw angle φ, and the yaw rate detected by the yaw rate sensor 4 whether the driver is performing a lane departure avoidance operation.
[0030]
Then, based on the determination result, when the predicted departure time is shorter than the first time T1, intermittent steering torque is applied in the direction opposite to the lane edge L where the host vehicle is approaching as the first alarm control. Synchronously with this, intermittent alarm sound (imitation sound) is output. Further, in consideration of the driver's reaction delay such as snoozing, when the predicted departure time TLD is shorter than the second time T2 shorter than the first time T1, the lane edge L where the host vehicle is approaching as the second alarm control A continuous steering torque is applied in the opposite direction. The steering torque is applied by the steering actuator 7, and the alarm sound is output using the speaker 10.
[0031]
Next, the control procedure of the controller 2 will be described with reference to FIG. 3 or FIG.
[First Embodiment]
FIG. 3 is a flowchart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
[0032]
As shown in FIG. 3, after the controller 2 updates the input of the CCD camera, various sensors, switches, etc., in step S1, a predicted departure time TLD is calculated.
[0033]
In step S2, it is determined whether the second alarm control intervention is in progress. If the determination is YES and the second alarm control intervention is in progress, the process proceeds to step S11. If the determination is NO and the second alarm control intervention is not in progress, the process proceeds to step S3.
[0034]
In step S3, it is determined whether or not the estimated departure time TLD is less than or equal to a second time T2 (for example, 0.8 seconds) that should intervene in the second alarm control. The determination is YES and the estimated departure time TLD is less than or equal to the second time T2. If so, the process proceeds to step S4. If the determination is NO and the estimated departure time TLD is longer than the second time T2, the process proceeds to step S7.
[0035]
In steps S4 and S5, in order to stop the first alarm control in order to intervene in the second alarm control, the alarm sound is stopped and the steering torque intermittent application control is stopped. In step S6, the second emergency level is high. Start alarm control.
[0036]
In step S7, since the departure prediction time TLD is longer than the second time, it is determined whether the first alarm control is being performed. If the determination in step S7 is YES and the first alarm control is being performed, the process proceeds to step S11, and if the determination is NO and the first alarm control is not being performed, the process proceeds to step S8.
[0037]
In step S8, it is determined whether or not the estimated departure time TLD is equal to or shorter than a first time T1 (for example, 1 to 2 seconds, where T1> T2) to intervene in the first alarm control. If the determination in step S8 is YES and the estimated departure time TLD is less than or equal to the first time T1, the process proceeds to step S9. If the determination is NO and the estimated departure time TLD is longer than the first time T1, no alarm is required. Return.
[0038]
In subsequent steps S9 and S10, since the state should be intervened in the first alarm control, the output of the alarm sound is started and the steering torque is intermittently applied in synchronization therewith.
[0039]
The next steps S11 to S17 are controls during the first or second alarm control. In each of these steps, the driver's driving intention (that is, when intentionally deviating from the lane due to lane change or overtaking) and lane departure If the avoidance state is determined and the driver intentionally departs from the lane or if the lane departure avoidance is sufficient, the first and second alarm controls are stopped (including those that immediately stop and gradually stop). )
[0040]
Specifically, in step S11, based on the steering of the steering wheel 8 by the driver detected by the steering sensor 9 (for example, the steering angle θ and the steering direction), the lane edge L at which the host vehicle is approaching is steered. It is determined whether or not the process is continued for a predetermined time Tθ. If the determination in step S11 is YES and the steering is continued for a predetermined time Tθ, the process proceeds to step S17, and if the determination is NO and the steering is not performed for a predetermined time Tθ, the lane departure by the driver Therefore, the first or second alarm control is continued and the process proceeds to step S12.
[0041]
In step S12, based on the steering torque of the steering wheel 8 by the driver detected by the steering sensor 9, it is determined whether the steering torque is held for a predetermined time Tf at a predetermined torque Fx or higher. If the determination in step S12 is YES and the steering torque is held for a predetermined time Tf or longer, the process proceeds to step S17, and if the determination is NO and the steering torque is not held for a predetermined time Tf or longer, the lane departure by the driver is detected. Since there is no intention, the first or second alarm control is continued and the process proceeds to step S13.
[0042]
In step S13, based on the winker switch operation by the driver, it is determined whether the winker switch operation has been performed on the lane edge L where the host vehicle is approaching.
If the determination in step S13 is YES and the winker operation is performed to the lane end L, the process proceeds to step S17. If the determination is NO and the winker operation is not performed to the lane L, the driver does not intend to depart from the lane. The first or second alarm control is continued and the process proceeds to step S14.
[0043]
In step S14, based on the steering angle θ of the steering wheel 8 by the driver detected by the steering sensor 9, the steering angle θ is steered at a predetermined angle θx or more in a direction opposite to the lane edge L where the host vehicle is approaching. It is determined whether it is done. If the determination in step S14 is YES and the steering angle θ is steered at a predetermined angle θx or more, the process proceeds to step S16, and if the determination is NO and the steering angle θ is not steered at a predetermined angle θx or more, the driver Since the lane departure avoidance due to is insufficient, the first or second alarm control is continued and the process proceeds to step S15.
[0044]
In step S15, based on the yaw angle φ with respect to the lane edge L of the own vehicle, a time Tφ until the yaw angle φ with respect to the lane edge L of the own vehicle becomes zero or less is predicted, and the predicted time Tφ is less than a predetermined time. Determine if there is. If the determination in step S15 is YES and the predicted time Tφ is equal to or shorter than the predetermined time, the process proceeds to step S16. If the determination is NO and the predicted time Tφ is longer than the predetermined time, the first or The second alarm control is continued and the process returns.
[0045]
In step S <b> 16, it is determined whether the host vehicle deviates from the lane edge L from the lateral deviation of the host vehicle with respect to the lane edge L while being steered in a direction to avoid lane departure. If the determination in step S16 is YES and the vehicle deviates from the lane edge L, the return to the lane is necessary, so the first or second alarm control is continued and the determination returns, and the determination deviates from NO. If not, the process proceeds to step S17.
[0046]
In step S <b> 17, the first or second warning control being executed is stopped reflecting the driver's intention to drive and the lane departure avoidance state, and the process returns.
[Time Chart of First Embodiment]
5 to 10 are time charts showing the control procedure of the lane departure prevention apparatus of the first embodiment.
[0047]
FIG. 5 shows the operations of the above steps S8 to S10, and the output of the alarm sound and the intermittent application of the steering torque are synchronized with the start of the first alarm control (TLD ≦ T1). Further, the second alarm control is started after the response delay time TD of the driver after the first alarm control is started.
[0048]
In step S15, if the predicted time Tφ when the yaw angle φ with respect to the lane edge L of the host vehicle is less than or equal to zero is short, the steering torque applied in the second alarm control is set before the yaw angle φ becomes zero. That is, the addition of the steering torque is canceled before the predicted time elapses.
[0049]
By this operation, the judgment speed of the driver who has received the warning can be increased and the uncomfortable feeling can be reduced. In addition, since it is left to the operation of the driver after the release, overshoot during control can be prevented and controllability can be improved.
[0050]
FIG. 6 shows the operation of the above step S16. If the host vehicle deviates from the lane edge L from the lateral position relative to the lane edge L of the host vehicle, the magnitude of the yaw angle φ, that is, the yaw angle φ is less than zero. Regardless of the predicted time Tφ, the second alarm control is continued until the lane departure of the host vehicle is avoided. This operation can reliably avoid lane departure.
[0051]
FIG. 7 shows the operation of step S11 described above. When the steering by the driver (for example, the steering angle θ) continues for a predetermined time Tθ or more to the lane edge L where the host vehicle is approaching, the second alarm control is performed. The addition of steering torque is gradually released. By this operation, priority can be given to the driver's intention, and hunting in control and the uncomfortable feeling experienced by the driver can be reduced.
[0052]
FIG. 8 shows the operation of step S12, and when the steering torque by the driver is maintained at a predetermined torque Fx or more and for a predetermined time Tf or more, the addition of the steering torque in the second alarm control is gradually released. By this operation, priority can be given to the driver's intention, and hunting in control and the uncomfortable feeling experienced by the driver can be reduced.
[0053]
FIG. 9 shows the operation of step S14. When the steering angle θ by the driver is steered at a predetermined angle θx or more in the direction opposite to the lane edge L where the host vehicle is approaching, the second alarm control is performed. The addition of steering torque is gradually released. By this operation, priority can be given to the driver's intention, and hunting in control and the uncomfortable feeling experienced by the driver can be reduced.
[0054]
FIG. 10 shows the operation of step S13, and when the winker operation by the driver is performed on the lane edge L where the host vehicle is approaching, the addition of the steering torque in the second alarm control is gradually released. By this operation, priority can be given to the driver's intention, and hunting in control and the uncomfortable feeling experienced by the driver can be reduced.
[Second Embodiment]
FIG. 4 is a flowchart showing a control procedure of the lane departure prevention apparatus of the second embodiment.
[0055]
In the second embodiment, the steering torque F added in the second alarm control is set to the upper limit value of the steering torque F1 added in the first alarm control, and the yaw angle deviation φ / φ0 with respect to the lane edge L of the host vehicle is smaller. It is set to be smaller.
[0056]
As shown in FIG. 4, after the controller 2 updates the input of the CCD camera, various sensors, switches, and the like, in step S21, a predicted departure time TLD is calculated.
[0057]
In step S2, it is determined whether the lane departure can be avoided, that is, whether the yaw angle φ with respect to the lane edge L of the host vehicle is zero. If the determination in step S2 is YES and lane departure can be avoided, the process proceeds to step S23. If the determination is NO and lane departure cannot be avoided, the process proceeds to step S24.
[0058]
In step S23, since the lane departure could be avoided, the first or second warning control being executed is stopped and the process returns.
[0059]
In step S24, it is determined whether or not the estimated departure time TLD is less than or equal to a second time T2 (for example, 0.8 seconds) that should intervene in the second alarm control. The determination is YES and the estimated departure time TLD is less than or equal to the second time T2. If so, the process proceeds to step S25, and if the determination is NO and the predicted departure time TLD is longer than the second time T2, the process proceeds to step S28.
[0060]
In step S25, in order to intervene in the second alarm control, the alarm sound is stopped, the steering torque intermittent application control is stopped, and the steering torque amount F is set in step S6. This steering torque amount F is calculated from the steering torque F1 added in the first alarm control and the deviation φ / φ0 of the current yaw angle φ with respect to the yaw angle φ0 immediately before the second alarm control intervention (F = F1 × φ / φ0).
[0061]
In step S27, the second alarm control for continuously applying the steering torque F is started.
[0062]
In step S28, it is determined whether or not the estimated departure time TLD is equal to or shorter than a first time T1 (for example, 1 to 2 seconds, where T1> T2) that should intervene in the first alarm control. If the determination in step S28 is YES and the estimated departure time TLD is less than or equal to the first time T1, the process proceeds to step S29. If the determination is NO and the estimated departure time TLD is longer than the first time T1, no alarm is required. Return.
[0063]
In subsequent steps S29, S30, and S31, since the state should be intervened in the first alarm control, the output of the alarm sound is started and the steering torque F is set to the steering torque F1 to be added in the first alarm control. Synchronously, the steering torque F is applied intermittently.
[0064]
In step S32, the yaw angle φ0 immediately before the second alarm control intervention is set to the current yaw angle φ and the process returns (φ0 = φ).
[Time Chart of Second Embodiment]
FIG. 11 is a time chart showing the control procedure of the lane departure prevention apparatus of the second embodiment.
[0065]
FIG. 11 shows the operation of step S30, and with the start of the first alarm control (TLD ≦ T1), an alarm sound is output and the steering torque F1 is intermittently applied in synchronism with this. In step S26, with the start of the second alarm control (TLD ≦ T2), the steering torque F added in the second alarm control is set as the upper limit value, and the steering torque F1 added in the first alarm control is set as the upper limit value. 2 The deviation φ / φ0 of the current yaw angle φ with respect to the yaw angle φ0 immediately before the alarm control intervention is set to become smaller, the steering torque F1 added in the first alarm control, and the yaw just before the second alarm control intervention. It is calculated by a deviation φ / φ0 of the current yaw angle φ with respect to the angle φ0 (F = F1 × φ / φ0).
[Brief description of the drawings]
FIG. 1 is a diagram showing a system configuration of an automobile on which a lane departure prevention apparatus according to an embodiment is mounted.
FIG. 2 is a block diagram of the controller shown in FIG.
FIG. 3 is a flowchart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 4 is a flowchart showing a control procedure of the lane departure prevention apparatus of the second embodiment.
FIG. 5 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 6 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 7 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 8 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 9 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 10 is a time chart showing a control procedure of the lane departure prevention apparatus of the first embodiment.
FIG. 11 is a time chart showing a control procedure of the lane departure prevention apparatus according to the second embodiment.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Car 2 Controller 3 CCD camera 4 Yaw rate sensor 5 Vehicle speed sensor 6 Winker switch 7 Steering actuator 8 Steering wheel 9 Steering sensor 10 Speaker

Claims (8)

Lateral position detecting means for detecting a relative lateral position between the lane edge and the host vehicle;
Based on the relative lateral position detected by the lateral position detecting means, the time until the host vehicle reaches the lane edge is measured, and the host vehicle approaches when the arrival time is shorter than the first predetermined time. And a departure prevention means for performing a first alarm control for adding intermittent steering torque in the opposite direction to the lane edge and outputting intermittent pseudo sound in synchronization with the addition of the steering torque,
When the time until the host vehicle reaches the lane edge is shorter than the second predetermined time, which is shorter than the first predetermined time, the departure prevention means is in a direction opposite to the lane edge where the host vehicle is approaching. The second alarm control for adding continuous steering torque is performed, and the steering torque to be added in the second alarm control is set to the upper limit value of the steering torque to be added in the first alarm control. A lane departure prevention apparatus, characterized in that the lane departure prevention apparatus is set so as to become smaller as the deviation of the vehicle becomes smaller. Lateral position detecting means for detecting a relative lateral position between the lane edge and the host vehicle;
Based on the relative lateral position detected by the lateral position detecting means, the time until the host vehicle reaches the lane edge is measured, and the host vehicle approaches when the arrival time is shorter than the first predetermined time. And a departure prevention means for performing a first alarm control for adding intermittent steering torque in the opposite direction to the lane edge and outputting intermittent pseudo sound in synchronization with the addition of the steering torque,
When the time until the host vehicle reaches the lane edge is shorter than the second predetermined time, which is shorter than the first predetermined time, the departure prevention means is in a direction opposite to the lane edge where the host vehicle is approaching. A second lane control for adding a continuous steering torque is performed, and the steering torque added in the second warning control is canceled before the yaw angle with respect to the lane edge of the host vehicle becomes zero. Prevention device. The lateral position detection means further comprises a yaw angle detection means for detecting a yaw angle with respect to the lane edge of the host vehicle,
The deviation prevention means predicts a time until the yaw angle becomes zero when the yaw angle detected by the yaw angle detection means is equal to or greater than a predetermined value, and the steering torque before the predicted time elapses. The lane departure prevention apparatus according to claim 2 , wherein the addition of is canceled. As the lateral position detection means, the vehicle further comprises deviation detection means for detecting that the host vehicle is deviating from the lane edge,
The departure prevention means, when the host vehicle departs from the lane, continues adding the steering torque until the host vehicle avoids the lane departure regardless of the magnitude of the yaw angle. The lane departure prevention apparatus according to claim 2 or 3 , characterized in that A steering detection means for detecting steering by the driver;
The departure prevention means gradually cancels the addition of the steering torque when the steering detected by the steering detection means continues for a predetermined time or more to the lane edge where the host vehicle is approaching. The lane departure prevention apparatus according to claim 2 . A steering torque detecting means for detecting a steering torque by the driver;
The deviation prevention means gradually releases the addition of the steering torque when the steering torque detected by the steering torque detection means is maintained at a predetermined torque or higher for a predetermined time or longer. lane departure prevention apparatus according to 2. A steering angle detection means for detecting a steering angle by the driver;
The departure prevention means adds the steering torque when the steering angle detected by the steering angle detection means is steered by a predetermined angle or more in a direction opposite to the lane edge where the host vehicle is approaching. The lane departure prevention device according to claim 2 , wherein the lane departure prevention device is gradually released. It further comprises operation detecting means for detecting a direction indicating operation by the driver,
The departure prevention means gradually cancels the addition of the steering torque when the direction indicating operation detected by the operation detection means is performed to a lane edge where the host vehicle is approaching. Item 3. A lane departure prevention apparatus according to item 2 .

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