JP4385759B2 - Lane departure prevention device - Google Patents

Description

  The present invention relates to a lane departure prevention apparatus for preventing a departure when a host vehicle is about to depart from a traveling lane during traveling.

As a conventional lane departure prevention device, when the host vehicle tends to depart from the driving lane, it is based on whether or not the steering direction by the driver's operation determined from the steering angle matches the departure direction of the host vehicle. If it is determined whether or not the steering operation is performed by the driver's intention, and if it is determined that the driver does not intend to steer, the deviation from the future lane calculated based on the traveling state of the own vehicle There is known a technique in which a yaw moment is generated in a vehicle to avoid a lane departure by giving a braking force difference between the left and right wheels according to an estimated amount (see, for example, Patent Document 1).
Japanese Unexamined Patent Publication No. 2003-112540 (5th page, FIG. 2)

However, in the above conventional lane departure prevention device, the driver's steering intention is determined according to the steering direction by the driver's operation determined from the steering angle and the departure direction of the host vehicle. When it is determined that there is, the departure avoidance control is not performed. However, even when steering in a deviating direction is detected, the vehicle deviates from the driving lane against the driver's intention due to external forces acting on the host vehicle, such as crosswinds or laterally inclined road surfaces. There is a situation where this is likely to occur, and in this case as well, there is an unresolved problem of wanting to properly operate the departure avoidance control.
Therefore, the present invention has been made paying attention to the unsolved problems of the above-described conventional example, and is a lane departure prevention device capable of appropriately judging a lane departure unintended by the driver and performing departure avoidance control. It is intended to provide.

To achieve the above object, engagement Ru car line departure prevention apparatus of the present invention, in a running state detecting means detects a running state of the vehicle, and calculates a lateral acceleration of the vehicle in the lateral acceleration detecting means, the steering state The detecting means detects the steering state, and based on the traveling state detected by the traveling state detecting means, the departure determining means determines that the host vehicle tends to deviate from the traveling lane, and the departure determining means when the vehicle is determined to be in the deviation tendency from the driving lane, based on the detected lateral acceleration by the steering state detected steering state detecting means and the lateral acceleration detecting means, in deviation intention determining means When it is determined that the departure is contrary to the driver's intention, and the departure intention determination means determines that the departure is contrary to the driver's intention, the departure prevention control means Controlling the vehicle in a direction to avoid the deviation according to the traveling state detected by the running state detecting means. The steering state detecting means detects a steering angle change amount of the steering wheel. Further, the departure intention determination means has a lateral acceleration detected by the lateral acceleration detection means that is equal to or greater than a predetermined value when the departure determination means determines that the host vehicle tends to depart from the driving lane, and When the steering angle change detected by the steering state detecting means is smaller than a predetermined value, it is determined that the deviation is contrary to the driver's intention.

According to the present invention, when the host vehicle tends to deviate from the driving lane, whether or not the deviation is a deviation against the driver's intention is determined based on the steering state (steering angle change amount) and the lateral acceleration. Judgment is made and the braking force of each wheel is controlled so that the host vehicle is controlled in a direction to avoid the departure only when the lane departure is contrary to the driver's intention . Therefore, when the lateral acceleration changes even though the rudder angle does not change, it is determined that an external force such as a crosswind is applied to the host vehicle and the vehicle is likely to deviate from the lane, and departure avoidance control can be performed. It is possible to appropriately prevent lane departure that is contrary to the driver's intention .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an embodiment of the present invention. This vehicle is a rear wheel drive vehicle equipped with an automatic transmission and a conventional differential gear, and the braking device can control the braking force (braking fluid pressure) of the left and right wheels independently of the front and rear wheels.
In the figure, reference numeral 1 is a brake pedal, 2 is a booster, 3 is a master cylinder, 4 is a reservoir, 9 is an engine, and 10 is an automatic transmission. Normally, the master pedal depends on the amount of depression of the brake pedal 1 by the driver. The brake fluid pressure boosted by the cylinder 3 is supplied to the wheel cylinders 6FL to 6RR of the front wheels 5FL, 5FR and the rear wheels 5RL, 5RR. Further, a braking fluid pressure control circuit 7 is interposed between the master cylinder 3 and each wheel cylinder 6FL-6RR. The braking fluid pressure control circuit 7 includes a braking fluid for each wheel cylinder 6FL-6RR. It is also possible to control the pressure individually.

  The brake fluid pressure control circuit 7 uses a brake fluid pressure control circuit used for antiskid control or traction control, for example. In this embodiment, the brake fluid pressure of each wheel cylinder 6FL-6RR is independently set. It is configured so that the pressure can be increased or decreased. The brake fluid pressure control circuit 7 controls the brake fluid pressures of the wheel cylinders 6FL to 6RR in accordance with a brake fluid pressure command value from a control unit 8 described later.

  In addition, this vehicle includes a CCD camera 13 and a camera controller 14 as an external recognition sensor for detecting the position of the host vehicle in the traveling lane for determining the traveling lane departure prevention of the host vehicle. The camera controller 14 detects a lane marker by detecting a lane marker such as a road marking line from a captured image in front of the host vehicle captured by the CCD camera 13, and further detects the yaw angle Φ of the host vehicle with respect to the lane of travel, The lateral displacement X from the center of the lane, the curvature ρ of the traveling lane, the lane width L, and the like can be calculated, and these calculation signals are output to the control unit 8.

Further, the vehicle includes an acceleration sensor 15 as a lateral acceleration detecting means for detecting a lateral acceleration Yg generated in the own vehicle, a master cylinder pressure sensor 16 for detecting an output pressure of the master cylinder 3, that is, a so-called master cylinder pressure Pm, By a steering angle sensor 20 that detects the steering angle θ of the steering wheel 19, wheel speed sensors 21FL to 21RR that detect the rotational speeds of the wheels 5FL to 5RR, that is, so-called wheel speeds Vw _j (j = FL to RR), and direction indicators. A direction indicating switch 22 for detecting a direction indicating operation and a torque sensor 23 for detecting a steering torque _Tstr are provided, and detection signals thereof are output to the control unit 8. The steering angle sensor 20 and the torque sensor 23 correspond to the steering state detection means.

If the detected vehicle traveling state data has left and right directions, the left direction is the positive direction. That is, the yaw angle Φ becomes a positive value when turning left, and the lateral displacement X becomes a positive value when it is shifted to the left from the center of the traveling lane.
Next, the lane departure prevention control process performed by the control unit 8 will be described with reference to the flowcharts of FIGS. This lane departure prevention control process is executed by, for example, a timer interrupt process every 10 msec.

In this lane departure prevention control process, first, in step S1 of FIG. 2, various data from the sensors and controllers are read. Specifically, the lateral acceleration Yg detected by the sensors, the wheel speeds Vw _j , the master cylinder pressure Pm, the steering angle θ, the direction instruction switch signal WS, the steering torque T _str , and the travel lane from the camera controller 14 The vehicle yaw angle Φ, the lateral displacement X from the center of the travel lane, the curvature ρ of the travel lane, and the travel lane width L are read.

Next, the routine proceeds to step S2 calculation, among the wheel speeds Vw _FL ~Vw _RR read in the step S1, before a non-driven wheel left and right wheel speeds Vw _FL, from the average value of Vw _FR of the vehicle the vehicle speed V Then, the process proceeds to step S3.
V = (Vw _FL + Vw _FR ) / 2 (1)
Note that, when the ABS control or the like is operating, the estimated vehicle speed estimated in the ABS control may be used.

In step S3, based on the lateral displacement X, the variation dX of the lateral displacement X, and the distance to the lane (L / 2-X), the estimated departure time until the vehicle departs based on the following equation (2). T _out is calculated, and the process proceeds to step S4.
T _out = (L / 2−X) / dX (2)
The departure prediction time T _out may be predicted based on the yaw angle Φ of the host vehicle, the curvature ρ of the traveling lane, the yaw rate φ of the vehicle, the steering angle θ, and the like.

In step S4, the estimated time of departure T _out was calculated in step S3 it is determined whether the deviation determination threshold Ts is smaller than that when a T _out ≧ Ts is the vehicle is determined not to deviation tendency step S5 , The deviation determination flag _Fout is reset to “0” which means that there is no tendency to deviate, and the process proceeds to step S6.
In step S6, the target yaw moment Ms is set to 0 (zero) based on the following equation (3), and then the process proceeds to step S16 described later.
Ms = 0 (3)

On the other hand, when the determination result in step S4 is T _out <Ts, it is determined that the host vehicle is in a tendency to deviate and the process proceeds to step S7, which means that the deviation determination flag F _out is deviating from “1”. Set to "" and go to step S8.
In step S8, the sign of the lateral displacement X is determined. When X ≧ 0, it is determined that the host vehicle is shifted to the left from the center of the traveling lane, the process proceeds to step S9, and the departure direction _Dout is on the left side. Is set to "1" which means that the process proceeds to step S11 to be described later. When the determination result in step S8 is X <0, the process proceeds to step S10 and the deviation direction _{Dout is set} to the right side. The meaning is set to “2”, and the process proceeds to step S11.

In step S11, it is determined whether or not the lateral acceleration Yg is equal to or greater than a preset threshold Yg _TH .
When the determination result in step S11 is Yg <Yg _TH , the process proceeds to step S12 to determine whether or not the driver is changing the lane. This determination is performed based on the direction indicating switch signal WS and the steering angle θ. When the direction indicating switch 22 is in the ON state, the direction determined by the sign of the direction indicating switch signal WS matches the departure direction D _out. If so, it is determined that the lane change is intentional to the driver. Further, when the steering angle θ is equal to or larger than the steering angle setting value θ _S set in advance when the direction indicating switch 22 is in the OFF state, it is determined that the driver is intentionally changing the lane.

When it is determined in step S12 that the driver intends to change lanes, the process proceeds to step S5. When it is determined that there is no intention to change lanes, the process proceeds to step S13, and the steering angle It is determined whether or not the amount of change Δθ is equal to or greater than a preset steering angle change amount setting value Δθ _S. If Δθ <Δθ _S, it is determined that the steering is not performed by the driver's intention, and the process proceeds to step S15 described later. If Δθ ≧ Δθ _S, it is determined that there is a possibility of steering by the driver's intention. Then, the process proceeds to step S14.

In step S14, it is determined whether the steering angle change amount Δθ is generated by the driver's intention or whether the steering is steered by an external force applied to the host vehicle such as a crosswind. This determination is made based on the sign of the steering torque T _str when the steering angle changes. Specifically, as shown in FIG. 4A, the steering torque T _str when the steering angle changes is obtained. When the force is positive (same direction) with respect to the turning direction, the steering changes due to the driver's intention. As shown in FIG. 4B, when the force is negative (reverse direction) with respect to the turning direction. It is determined that the steering is changed by an external force.

When it is determined that the steering angle change amount Δθ is generated by the driver's intention, the process proceeds to step S5. When it is determined that the steering angle change amount Δθ is not caused by the driver's intention, the process proceeds to step S15.
In step S15, based on the lateral displacement X and its change amount dX, the target yaw moment Ms to be generated in the vehicle is calculated based on the following equation (4), and then the process proceeds to step S16.
Ms = K ₁ · X + K ₂ · dX (4)
Here, K ₁ and K ₂ are gains that vary according to the vehicle speed V, and are calculated with reference to the gain calculation map shown in FIG.

The target yaw moment Ms may be calculated based on the following equation (5) based on the yaw angle Φ, the lateral displacement X, and the forward travel lane curvature ρ with respect to the travel lane of the host vehicle.
Ms = K _a · Φ + K _b · X + K _c · ρ (5)
_{Here, K a, K b, K} c is a gain that varies according to vehicle speed V, K _a, K _b refers to the gain calculation map shown in FIG. 5, K _c is the gain calculation map shown in FIG. 6 To calculate.
In step S16, a target brake hydraulic pressure calculation process for calculating the target brake hydraulic pressure Ps _i (i = FL to RR) of each wheel according to the target yaw moment Ms and the master cylinder hydraulic pressure Pm is performed.

Then, the processing proceeds to step S17, to return from the output of the target brake hydraulic pressures Ps _FL ~Ps _RR calculated at step S16 to the brake hydraulic control circuit 7 to end the timer interrupt process to a predetermined main program .
In the step S16, it performs target brake hydraulic pressure calculation processing shown in FIG. 3, first departure determination flag F _out in step S21 means that there is no the departure tendency "0" to determine whether it is reset.

When the determination result in step S21 is F _out = 0, the process proceeds to step S22, and the front left wheel target braking fluid pressure Ps _FL and the front right wheel target braking fluid pressure Ps _FR are obtained as shown in the following equation (6). Is set to ½ of the front wheel master cylinder pressure Pmf considering the front-rear distribution calculated from the master cylinder hydraulic pressure Pm, and the rear left wheel target braking hydraulic pressure Ps _RL and the rear right wheel as shown in the following equation (7): The target brake hydraulic pressure Ps _RR is set to ½ of the rear wheel master cylinder pressure Pmr in consideration of the front / rear distribution calculated from the master cylinder pressure Pm, and then the target brake hydraulic pressure calculation process is terminated, and a predetermined main Return to the program.
Ps _FL = Ps _FR = Pmf / 2 (6)
Ps _RL = Ps _RR = Pmr / 2 (7)

When the determination result in step S21 is F _out = 1, the process proceeds to step S23 to determine whether or not the absolute value | Ms | of the target yaw moment Ms is smaller than the set value Ms1, and | Ms | <MS1 When it is, the process proceeds to step S24, and based on the following equations (8) and (9), target braking hydraulic pressure differences ΔPs _F and ΔPs _R that cause a difference in braking force between the left and right rear wheels are set as targets. After calculating based on the yaw moment Ms, the process proceeds to step S26 described later.
ΔPs _F = 0 (8)
ΔPs _R = 2 × K _BR × | Ms | / T (9)

On the other hand, when | Ms | ≧ MS1, the process proceeds to step S25, and based on the following equations (10) and (11), a target braking hydraulic pressure difference ΔPs _F that causes a difference in the braking force between the front and rear left and right wheels. And ΔPs _R are calculated based on the target yaw moment Ms, and then the process proceeds to step S26.
ΔPs _F = 2 × K _BF × (| Ms | −Ms1) / T (10)
ΔPs _R = 2 × K _BR × Ms1 / T (11)
Here, T is the same tread for the front and rear wheels. K _BR is a conversion coefficient for converting braking force into braking hydraulic pressure, and is determined by brake specifications.

In step S26, determines whether or not trying to generate the target yaw moment Ms in the negative i.e. leftward, Ms <when it is 0, the process proceeds to step S27, before following the target braking pressure Ps _FL of the left wheel (12 ) is set to the master cylinder pressure Pmf / 2 as shown in the expression before adding the target brake hydraulic pressure difference DerutaPs _F to the master cylinder pressure Pmf / 2 as shown the target braking pressure Ps _FR of the right wheel in the following equation (13) The rear left wheel target braking pressure Ps _RL is set to the rear wheel side master cylinder pressure Pmr / 2 in consideration of the front-rear distribution calculated from the master cylinder pressure Pm as shown in the following equation (14): The target braking pressure Ps _RR of the rear right wheel is set to a value obtained by adding the rear wheel side target braking hydraulic pressure difference ΔPs _R to the rear wheel master cylinder pressure Pmr / 2 as shown in the following equation (15). Finish the calculation process To return to the predetermined main program.
Ps _FL = Pmf / 2 (12)
Ps _FR = Pmf / 2 + ΔPs _F (13)
Ps _RL = Pmr / 2 (14)
Ps _RR = Pmr / 2 + ΔPs _R (15)

On the other hand, front-wheel-side target master cylinder pressure Pmf / 2 as the process proceeds to step S28, indicating the target braking pressure Ps _FL of the front left wheel in the following equation (16) when the judgment result of the step S26 is Ms ≧ 0 The brake hydraulic pressure difference ΔPs _F is set to the added value, the front right wheel target brake pressure Ps _FR is set to the master cylinder pressure Pmf / 2 as shown in the following equation (17), and the rear left wheel target brake pressure Ps _RL Is set to a value obtained by adding the rear-wheel-side target braking hydraulic pressure difference ΔPs _R to the rear-wheel-side master cylinder pressure Pmr / 2 as shown in the following equation (18), and the rear-right wheel target braking pressure Ps _RR is set to the following (19 ) After setting the rear wheel master cylinder pressure Pmr / 2 as shown in the equation, the target brake fluid pressure calculation process is terminated, and the process returns to a predetermined main program.
Ps _FL = Pmf / 2 + ΔPs _F (16)
Ps _FR = Pmf / 2 (17)
Ps _RL = Pmr / 2 + ΔPs _R (18)
Ps _RR = Pmr / 2 (19)

In the lane departure prevention control process of FIG. 2, steps S3 to S5 and S7 to S10 correspond to departure determination means, steps S11 to S14 correspond to departure intention determination means, and steps S15 to S17 are performed. It corresponds to the deviation prevention control means.
Accordingly, it is assumed that the host vehicle is traveling straight along the travel lane in a state where the driver is not performing the steering operation and no external force is applied to the host vehicle. In this case, in the departure prevention control process of FIG. 2, a departure prediction time T _out that satisfies T _out <Ts is calculated in step S3, and therefore, the processing shifts from step S4 to step S5 and the departure determination flag F _out = It becomes 0 and indicates that there is no tendency to deviate, and the target yaw moment Ms is set to “0” in step S6. Thus, the target braking pressure Ps _FL ~Ps _RR of each wheel 5FL~5RR in step S22 in FIG. 3, the master cylinder pressures Pmf and Pmr according to the brake operation of the driver are respectively set, the driver's steering operation The running state corresponding to is continued.

From this state, it is assumed that the vehicle gradually begins to deviate leftward from the center position of the travel lane due to the driver's sideways look. In this case, since the predicted departure time T _out satisfying T _out ≧ Ts is calculated in step S3, the process proceeds from step S4 to step S7, and the departure determination flag F _out = 1 and there is a tendency of departure. It will be in the state which shows. Since no external force is acting on the host vehicle and the lateral acceleration Yg is smaller than the threshold Yg _TH , the process proceeds from step S11 to step S13 through step S12. Since the driver does not perform the steering operation, the process proceeds to step S15 based on the determination in step S13, and the target yaw moment Ms is calculated based on the equation (4). Then, the target braking pressures Ps _{FL to} Ps _{RR of the} wheels 5FL to 5RR are set in step S27 of FIG. 3 so that the target yaw moment Ms is generated in the host vehicle, so that the right direction that is the departure avoidance direction is set. Correct the course to.

It is assumed that the driver is intentionally changing the lane by operating the direction switch. In this case, it is determined in step S12 that the direction of the direction indicating switch 22 matches the departure direction determined by the departure direction flag _Dout , the process proceeds to step S5, and the departure determination flag _Fout = 0. It will be in the state which shows that it does not become a departure tendency. Thus, the target braking pressure Ps _FL ~Ps _RR of each wheel 5FL~5RR in step S22 in FIG. 3, the master cylinder pressure Pm and Pmr corresponding to the brake operation of the driver are respectively set, the driver's steering operation Therefore, the traveling state suitable for the driver's feeling can be continued without operating the departure prevention control.
In this way, when the driver tries to intentionally change the lane by operating the direction indicating switch and tends to deviate from the traveling lane, the departure prevention control is not activated, so the driver feels uncomfortable. It is possible to perform traveling control that matches the driver's feeling without giving it.

It is assumed that an external force such as a cross wind acts on the host vehicle when the driver is not performing a steering operation, and the vehicle tends to deviate leftward from the driving lane against the driver's intention. In this case, generated lateral acceleration Yg such that Yg ≧ Yg _TH, the process proceeds to step S13 by the determination in step S11. Since the steering angle has not changed and the steering change amount Δθ is smaller than the threshold value Δθs, the routine proceeds from step S13 to step S15, and the target yaw moment Ms is calculated based on the above equation (4). . As a result, the target braking pressures Ps _{FL to} Ps _{RR of the} wheels 5FL to 5RR are set in step S27 in FIG. 3 so that the target yaw moment Ms is generated in the host vehicle. Correct the course in the direction.
As described above, even when there is no steering change, when the lateral acceleration is equal to or greater than a predetermined value, it is determined that the deviation is contrary to the driver's intention. When there is a tendency to deviate from the middle lane, the deviation prevention control can be reliably operated to avoid the deviation.

On the other hand, when an external force such as a crosswind acts on the vehicle and the vehicle tends to deviate to the left against the driver's intention, and the steering angle is changing even though the driver is not steering. Since the steering change amount Δθ that satisfies Δθ ≧ Δθs is detected, the process proceeds to step S14 based on the determination in step S13, and the steering torque determines whether the steering change is caused by the driver's steering or the external force. _{Judged by} the sign of T _str . Since the driver is not steering, it is determined that the steering torque T _str detected by the torque sensor 23 is opposite to the steered direction, and a steering change has occurred due to external force. The process proceeds to S15, and the target yaw moment Ms is calculated based on the equation (4). As a result, the target braking pressures Ps _{FL to} Ps _{RR of the} wheels 5FL to 5RR are set in step S27 in FIG. 3 so that the target yaw moment Ms is generated in the host vehicle. Correct the course in the direction.

In this embodiment, the lateral acceleration is detected in step S11, but this step may be omitted. In this case, the determination in step S12 is performed after step S9, and then in steps S13 and S14, it is determined whether or not the steering angle change of the host vehicle is due to an external force.
Therefore, when a change occurs in the steering angle, it is determined from the steering torque detected by the torque sensor whether the change in the steering angle is caused by the driver's steering or the external force. It is possible to reliably detect a change in the rudder angle and generate a yaw moment when the vehicle departs from a lane that is not intended by the driver, thereby performing departure avoidance control without causing the driver to feel uncomfortable.

  As described above, in the present embodiment, when the lateral acceleration of the host vehicle is detected and it is determined that there is a tendency to deviate from the traveling lane based on the traveling state of the host vehicle, the departure is a deviation due to the driver's intention. Or a deviation against the driver's intention, based on the driving state and the lateral acceleration, it is possible to appropriately perform the departure avoidance control when the driver deviates from the lane and the driver does not intend. When the vehicle departs from the lane due to the intention, the departure avoidance control is deactivated, and the driver's uncomfortable feeling can be suppressed.

Further, when the host vehicle tends to deviate from the driving lane, it is judged that the deviation is contrary to the driver's intention when the lateral acceleration is equal to or greater than a predetermined value and the steering angle change amount is smaller than the predetermined value. Since the avoidance control is activated, it is possible to appropriately avoid the lane departure when the lateral acceleration occurs and the vehicle is about to depart from the traveling lane even though the steering angle is not changed.
Furthermore, when the host vehicle tends to deviate from the driving lane, when the steering angle change amount is equal to or greater than a predetermined value and the steering torque is opposite to the steering direction, the deviation is contrary to the driver's intention. Since the departure avoidance control is activated based on the judgment that there is, it is possible to reliably detect that a steering change has occurred due to an external force or the like acting on the host vehicle, and to appropriately avoid the departure from the lane when the driver does not intend to leave the lane. it can.

Further, when the steering torque is a positive value with respect to the turning direction, it is determined that the steering change is caused by the driver's intention, and the departure avoidance control is deactivated. Therefore, the departure avoidance control is activated. A driver's discomfort can be suppressed.
In the above embodiment, the case where the present invention is applied to a rear wheel drive vehicle has been described. However, the present invention can also be applied to a front wheel drive vehicle. In this case, in step S2, among the wheel speeds Vw _FL ~Vw _RR, left and right wheel speeds Vw _RL after a non-driven wheels, may be calculated vehicle speed V of the host vehicle from an average value of Vw _RR.

It is a schematic structure figure showing an embodiment of the present invention. It is a flowchart which shows the lane departure prevention control process performed with the control unit 8 of FIG. 1 in embodiment of this invention. 3 is a flowchart showing a target braking fluid pressure calculation process in the lane departure prevention control process of FIG. 2. It is a figure explaining the change of the steering torque by a driver | operator's steering intention. It is a gain calculation map. It is a gain calculation map.

Explanation of symbols

6FL to 6RR Wheel cylinder 7 Braking fluid pressure control circuit 8 Control unit 9 Engine 13 CCD camera 14 Camera controller 15 Acceleration sensor 16 Master cylinder pressure sensor 20 Steering angle sensor 21FL to 21RR Wheel speed sensor 22 Direction indication switch 23 Torque sensor

Claims (2)

In a lane departure prevention apparatus for controlling the host vehicle so as to avoid a departure from the traveling lane of the host vehicle,
Travel state detection means for detecting the travel state of the host vehicle, lateral acceleration detection means for detecting the lateral acceleration of the host vehicle, steering state detection means for detecting the steering state, and travel detected by the travel state detection means Departure determination means for determining that the host vehicle tends to deviate from the traveling lane based on the state, and when the departure determining means determines that the host vehicle is in a tendency to depart from the driving lane, the steering state Based on the steering state detected by the detection means and the lateral acceleration detected by the lateral acceleration detection means, the departure intention determination means for determining that the departure is contrary to the driver's intention, and the departure intention determination means When it is determined that the deviation is contrary to the driver's intention, the deviation is automatically avoided in accordance with the running condition detected by the running condition detecting means. And a departure prevention control means for controlling both, the steering state detecting means detects a steering angle change amount of the steering wheel, the deviation intention determining means, departure tendency vehicle from the traffic lane by the deviation determining means When the lateral acceleration detected by the lateral acceleration detecting means is greater than or equal to a predetermined value and the steering angle change detected by the steering state detecting means is smaller than a predetermined value, the driver's A lane departure prevention apparatus, characterized in that it is determined that the departure is against the intention . The steering state detection means detects a steering torque of the steering, and the departure intention determination means detects the lateral acceleration detection means when the departure determination means determines that the host vehicle tends to depart from the driving lane. The lateral acceleration detected in step (b) is greater than or equal to a predetermined value, the steering angle change detected by the steering state detection means is greater than or equal to a predetermined value, and the steering torque detected by the steering state detection means is greater than the steering direction. The lane departure prevention apparatus according to claim 1, wherein when the vehicle is in the reverse direction, it is determined that the departure is contrary to the driver's intention.

Images