JP2013252862A - Traffic lane deviation preventive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lane deviation preventive device advantageous for precisely assisting steering operation for smoothly returning one's own vehicle which tends to deviate from a travel traffic lane to the travel traffic lane.SOLUTION: A traffic lane deviation determining means 38A determines whether or not one's own vehicle tends to deviate from a travel traffic lane. A correcting travel locus calculating means 38C calculates a correcting travel locus being a locus to make the one's own vehicle travel for returning the one's own vehicle to the center line Lc of the travel traffic lane when it is determined that the one's own vehicle tends to deviate from the travel traffic lane. An ideal steering torque calculating means 22B calculates steering torque generated in a steering mechanism 1406 as ideal steering torque when a steering 1402 is operated so that the one's own vehicle travels along the correcting travel locus. A second steering assisting torque determining means 22C determines steering assisting torque so that the steering torque generated in the steering mechanism 1406 coincides with the ideal steering torque when the steering 1402 is operated.

Description

  The present invention relates to a lane departure prevention apparatus for preventing a host vehicle from departing from a traveling lane.

A technique has been proposed for generating an lane departure warning with an indicator or buzzer when it is determined that the vehicle tends to deviate from the driving lane from the position of the white line on the road acquired by the imaging means and the vehicle position. ing.
When the driver recognizes the lane departure warning, the driver operates the steering so that the host vehicle returns to the traveling lane so that the host vehicle does not depart from the traveling lane.
A technique for assisting such a driver's steering operation has been proposed (see Patent Document 1).
In the power steering device that applies a steering assist force to the steering mechanism by an actuator, this technology detects the vehicle's tendency to deviate from the lane, rather than the steering assist force in the direction deviating from the lane. The actuator is controlled so that the steering assist force in the direction of returning to the lane exceeds the steering assist force.
In addition, in order to suppress a driver's sudden steering operation when a lane departure warning occurs, the steering gear ratio is controlled so that the steering operation becomes less responsive when a lane departure warning is generated. The technique to do is proposed (refer patent document 2).

JP 2001-187582 A JP 2009-286154 A

In the former prior art described above, it is preferable to smoothly perform the steering operation when returning the host vehicle to the traveling lane, but the steering operation cannot be suppressed when the driver cuts the steering too far in the direction opposite to the departure direction. Therefore, it cannot be said that it is sufficient for realizing an accurate steering operation.
In the latter prior art, the steering operation can be suppressed when the driver turns the steering too far in the direction opposite to the departure direction, but the steering operation when returning the host vehicle to the original travel lane is also suppressed. Therefore, it cannot be said that it is sufficient to realize an accurate steering operation.
The present invention has been made in view of the above circumstances, and accurately assists the steering operation for smoothly returning the host vehicle to the traveling lane when it is determined that the host vehicle tends to deviate from the traveling lane. An object of the present invention is to provide a lane departure prevention device that is advantageous.

  In order to achieve the above object, the present invention provides a vehicle lane departure prevention device including a power steering device that applies a steering assist torque to a steering system based on a steering operation by a driver, Lane departure determining means for determining whether or not the host vehicle tends to depart from the driving lane based on host vehicle position information indicating the positional relationship of the vehicle, and the host vehicle tends to deviate from the driving lane When the determination is made, a correction that is a trajectory that the host vehicle should travel in order to return the host vehicle to the center line of the travel lane based on the host vehicle position information and the travel state information related to the travel state of the host vehicle A correction travel trajectory calculating means for calculating a travel trajectory, and the steering when the steering is operated so that the host vehicle travels along the correction travel trajectory Ideal steering torque calculation means for calculating the steering torque generated in step 1 as ideal steering torque, and the steering assist torque so that the steering torque generated in the steering system when the steering is operated matches the ideal steering torque. Steering assist torque determining means for determining is provided.

According to the present invention, when it is determined that the host vehicle tends to deviate from the traveling lane, the steering vehicle travels along the correction traveling locus that is the locus that the own vehicle should travel. The steering torque generated in the steering system when operated is calculated as the ideal steering torque. Then, the steering assist torque is determined so that the steering torque generated in the steering system when the steering is operated matches the ideal steering torque.
Therefore, it is advantageous in accurately assisting the steering operation for smoothly returning the host vehicle to the traveling lane.

It is a block diagram which shows the structure of the control system of the vehicle provided with the lane departure prevention apparatus 10 which concerns on embodiment. It is explanatory drawing which shows the 1st assist map which shows the relationship between steering torque and steering assistance torque (motor drive current value). It is a functional block diagram which shows the structure of lane departure determination means 38A. It is a figure explaining the derivation | leading-out procedure of lateral deviation | shift amount yf, yaw angle (theta) f, and road curvature (rho) f. (A) is a figure explaining the case where the own vehicle 2 which tends to deviate from the traveling lane returns to the center line of the traveling lane along the correction traveling locus, and (B) is the own vehicle shown in (A). It is a diagram which shows the ideal steering torque value corresponding to each position. (A), (B), (C) shows the relationship between the steering torque and the steering assist torque (motor drive current value) corresponding to the positions P1, P2, P3 of the host vehicle 2 in FIGS. 5 (A) and 5 (B). It is explanatory drawing which shows the 2nd assist map which shows. 4 is a flowchart for explaining the operation of the lane departure prevention apparatus 10.

Hereinafter, a lane departure prevention apparatus 10 according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIG. 1, the lane departure prevention device 10 of the present embodiment is provided in a vehicle including a power steering device 12.
In the present embodiment, the power steering device 12 includes a steering system 14, a steering torque sensor 16, a power steering motor 18, a vehicle speed sensor 20, and a power steering ECU 22.

The steering system 14 includes a steering 1402 that is operated when the vehicle is steered, a steering shaft 1404 that is coupled to the steering 1402, a steering mechanism 1406 that steers the steering wheel based on the rotation of the steering shaft 1404, and the like. Has been.
The steering torque sensor 16 is provided in the steering mechanism 1406 and detects a steering torque applied to the steering shaft 1404 by the operation of the steering 1402 by the driver.
The power steering motor 18 is an actuator that applies a steering assist torque to the steering mechanism 1406.
The vehicle speed sensor 20 detects the traveling speed of the host vehicle.

The power steering ECU 22 includes a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an interface unit that interfaces with peripheral circuits, and the like, and executes the control program. It works by doing.
When the CPU operates, the power steering ECU 22 operates as a first steering assist torque determining means 22A, a motor control means 22D, an ideal steering torque calculating means 22B described later, and a second steering assist torque determining means described later. 22C is realized.

  The first steering assist torque determining means 22A determines the steering assist torque to be applied to the steering mechanism 1406 based on the steering torque detected by the steering torque sensor 16 and the vehicle speed detected by the vehicle speed sensor 20. It is.

The motor control means 22D controls the driving of the power steering motor 18 so that the steering assist torque determined by the first steering assist torque determination means 22A is applied to the steering mechanism 1406.
Specifically, as shown in FIG. 2, a first assist map indicating the relationship between the steering torque and the steering assist torque (motor drive current value) is determined in advance. The first assist map is, for example, a power It is stored in the ROM of the steering ECU 22 or the like.
The determination of the steering assist torque by the first steering assist torque determination means 22A specifies the steering assist torque (motor drive current value) corresponding to the steering torque detected by the steering torque sensor 16 from the first assist map. Is made by
The drive control of the power steering motor 18 by the motor control means 22D is performed based on the steering assist torque (motor drive current value) determined from the first assist map.
In other words, the power steering device 12 applies steering assist torque to the steering system 14 based on the operation of the steering 1402 by the driver.

More specifically, in FIG. 2, the horizontal axis represents the steering torque, the right steering is indicated by a positive steering torque value, and the left steering is indicated by a negative steering torque value. The vertical axis represents steering assist torque (motor drive current value), right steering is a positive steering assist torque value (motor drive current value), and left steering is a negative steering assist torque value (motor drive). Current value).
When the steering 1402 is operated to the right or left, the absolute value of the steering torque value increases as the amount of operation increases (in other words, the steering 1402 is cut).
In the present embodiment, as shown in FIG. 2, as the absolute value of the steering torque value increases from 0, the absolute value of the steering assist torque value (motor drive current value) increases. When a predetermined threshold value is exceeded, the steering assist torque value (motor drive current value) is a constant value.
In the following, in order to simplify the description, “the absolute value of the steering torque value and the steering assist torque value (motor drive current value) increases or decreases” is simply referred to as “the steering torque value and the steering assist torque”. The value (motor drive current value) increases or decreases ".

Next, the lane departure prevention apparatus 10 will be described.
As shown in FIG. 1, the lane departure prevention apparatus 10 includes a front camera 24, an indicator 26, a buzzer 28, the steering torque sensor 16, the vehicle speed sensor 20, a handle angle sensor 30, and a shift position. A sensor 32, an accelerator opening sensor 34, a yaw rate sensor 36, and a lane departure warning ECU 38 are included.
Further, the lane departure warning ECU 38, the power steering ECU 22, the front camera 24, the indicator 26, the buzzer 28, and the sensors 16, 20, 30, 32, 34, and 36 described above are each a CAN (Controller Area Network) bus 40 and the like. Information and data are exchanged via a conventionally known bus.

The front camera 24 is provided in the vehicle and generates image information by capturing an image of a road state ahead of the vehicle. Therefore, the image information includes white lines as left and right boundary lines that divide the road lane (travel lane).
The indicator 26 is provided at an appropriate location such as an instrument panel in the passenger compartment, and displays a warning indicating that the host vehicle tends to deviate from the traveling lane. As such a warning display, for example, various conventionally known displays such as lighting or blinking a lamp, displaying icons, characters, symbols, and the like can be used.
The buzzer 28 is provided at an appropriate location such as an instrument panel in the passenger compartment, and sounds a warning sound indicating that the host vehicle tends to deviate from the traveling lane.
In the present specification, “the host vehicle tends to depart from the driving lane” means that the host vehicle is approaching one of the two white lines from the driving lane, and the host vehicle. Including a state exceeding the white line (a state deviating from the traveling lane).

The handle angle sensor 30 is provided in the steering system 14 and detects a handle angle (steering angle) that is a rotation angle of the steering 1402.
The shift position sensor 32 detects the position of the shift lever.
The accelerator opening sensor 34 detects the accelerator opening.
The yaw rate sensor 36 detects the yaw rate of the vehicle.

The lane departure warning ECU 38 includes a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an interface unit that interfaces with peripheral circuits, and the like. It works by executing.
The lane departure warning ECU 38 realizes lane departure determination means 38A, lane departure warning means 38B, and correction travel locus calculation means 38C by the operation of the CPU.
The lane departure prevention apparatus 10 includes an ideal steering torque calculation unit 22B configured by the power steering ECU 22 and a second steering assist torque determination unit 22C.
In the present embodiment, the second steering assist torque determining means 22C constitutes “steering assist torque determining means” in the claims.

The lane departure determination means 38A determines whether or not the host vehicle tends to deviate from the traveling lane based on the host vehicle position information including the positional relationship of the host vehicle with respect to the traveling lane.
In the present embodiment, the lane departure determination unit 38A determines, for example, as shown in FIG. 3, a white line recognition unit 42, a lateral deviation amount estimation unit 44, a yaw angle estimation unit 46, and a road curvature estimation unit 48. Part 50.

The white line recognition unit 42 processes image information captured by the front camera 24 and recognizes a white line on the road.
The white line recognizing unit 42 recognizes a white line in an image by a known method (for example, disclosed in Japanese Patent Application Laid-Open No. 11-147481) such as searching for a luminance change in a horizontal direction with respect to captured image information. .
That is, the white line recognizing unit 42 pays attention to the point that the white line has higher luminance than other road surfaces, and the portion where the luminance change in the horizontal direction of the image is 2 within a predetermined distance (distance corresponding to the width of the white line). Assuming that there is a white line between the dots if they are lined up, the white line on the road ahead of the host vehicle is distant by searching a number of white line candidate points in the horizontal direction at each of the vertical positions in the image. Can be recognized.
Then, for example, the white line Lw on the road ahead of the host vehicle 2 can be recognized in plan view as shown in FIG. 4 by geometrically replacing the image with the plan view state.
Thus, when the left and right white lines Lw defining the traveling lane ahead of the host vehicle 2 can be recognized, for example, the center line Lc of the traveling lane ahead of the host vehicle 2 as a straight line or a curve connecting the midpoints of the left and right white lines Lw. Can be estimated.

The lateral deviation amount estimation unit 44 estimates the lateral deviation amount yf in the traveling lane of the host vehicle 2 ahead by a predetermined distance based on the white line Lw recognized by the white line recognition unit 42.
That is, in the lateral deviation amount estimation unit 44, the lateral deviation amount (lateral deviation distance) from the center line Lc of the traveling lane at the center in the width direction of the own vehicle 2 when the own vehicle 2 moves straight ahead a predetermined distance with the current orientation. ) Yf is estimated from the relationship between the traveling lane (center line Lc or white line Lw) estimated as described above and the host vehicle 2.
The lateral displacement amount yf of the host vehicle 2 in front of the predetermined distance is, for example, the center of the left and right sides of the image and the center line of the driving lane in the image at a predetermined height in the image (corresponding to a predetermined distance in front of the host vehicle 2). It can also be determined from the positional relationship with Lc.
Here, the lateral displacement amount yf is host vehicle position information indicating the positional relationship of the host vehicle 2 with respect to the traveling lane.

The yaw angle estimation unit 46 estimates the yaw angle Θf with respect to the traveling lane direction of the host vehicle 2 ahead by a predetermined distance based on the white line Lw recognized by the white line recognition unit 42.
That is, the yaw angle estimation unit 46 determines the angle (yaw angle) Θf between the direction of the traveling lane and the direction of the host vehicle 2 when the host vehicle 2 travels straight ahead a predetermined distance with the current direction as described above. It is estimated from the relationship between the estimated travel lane (center line Lc or white line Lw) and the host vehicle 2.
This yaw angle Θf can be calculated from, for example, the direction of the road center line Lc (or white line Lw) on the road and the direction of the host vehicle 2 in the plan view recognized as described above.
Here, the yaw angle Θf is host vehicle position information indicating the positional relationship of the host vehicle 2 with respect to the traveling lane.

The road curvature estimation unit 48 estimates the road curvature ρf of the traveling lane ahead by a predetermined distance based on the white line Lw recognized by the white line recognition unit 42.
That is, the road curvature estimation unit 48 estimates the road curvature ρf of the traveling lane ahead of the predetermined distance from the shape of the traveling lane (center line Lc or white line Lw) estimated as described above.

The determination unit 50 includes a lateral deviation amount yf estimated by the lateral deviation amount estimation unit 44, a yaw angle Θf estimated by the yaw angle estimation unit 46, a road curvature ρf estimated by the road curvature estimation unit 48, and the vehicle speed sensor 20. The host vehicle 2 travels from the vehicle speed V of the host vehicle 2 detected in step S2, the handle angle α of the host vehicle 2 detected by the handle angle sensor 30, and the yaw rate r of the host vehicle 2 detected by the yaw rate sensor 36. It is determined whether the vehicle tends to depart from the lane.
As described above, in the present embodiment, the determination unit 50 determines the road curvature ρf and the vehicle speed in addition to the lateral deviation amount yf and the yaw angle Θf as the vehicle position information indicating the positional relationship of the vehicle 2 with respect to the traveling lane. In consideration of V, the steering wheel angle α, and the yaw rate r, it is determined whether or not the host vehicle 2 tends to deviate from the traveling lane.
The determination unit 50 may determine whether or not the host vehicle 2 tends to deviate from the travel lane based on only the lateral deviation amount yf and the yaw angle Θf as the host vehicle position information. If it carries out like a form, it will become advantageous when determining whether the own vehicle 2 tends to deviate from a driving | running | working lane more accurately.

As shown in FIG. 1, the correction travel locus calculation means 38C determines that the host vehicle position information (lateral shift amount yf and yaw angle Θf) when it is determined that the host vehicle 2 tends to deviate from the travel lane. And a correction travel locus, which is a locus that the host vehicle 2 should travel in order to return the host vehicle 2 to the center line Lc of the travel lane, based on the travel state information related to the travel state of the host vehicle 2. .
In the present embodiment, the traveling state information includes the vehicle speed V and the road curvature ρf (the curvature radius of the road on which the host vehicle 2 is traveling).
More specifically, the correction travel locus calculation unit 38C calculates the correction travel locus using a combination of a curve such as a clothoid curve and a straight line using the vehicle position information and the travel state information as parameters.
The correction travel trajectory is a travel trajectory that can be smoothly returned to the travel lane when the host vehicle 2 travels in a state where the lateral speed or yaw rate generated in the host vehicle 2 does not exceed a predetermined upper limit value.
The traveling state information may further include a predetermined maximum yaw rate (or maximum lateral acceleration) of the own vehicle 2 and a predetermined maximum turning radius of the own vehicle 2, and the maximum yaw rate (or Use of the maximum lateral acceleration) and the maximum turning radius is advantageous in calculating the correction travel locus more accurately.

The ideal steering torque calculating means 22B calculates the steering torque generated in the steering system 14 as the ideal steering torque when the steering 1402 is operated so that the host vehicle 2 travels along the correction travel locus. is there.
In this case, the calculation of the ideal steering torque by the ideal steering torque calculation means 22B is performed using information obtained from each sensor during vehicle travel.
The information includes the steering torque detected by the steering torque sensor 16, the vehicle speed detected by the vehicle speed sensor 20, the handle angle detected by the handle angle sensor 30, the shift position detected by the shift position sensor 32, the accelerator opening. Information such as the accelerator opening from the degree sensor 34 can be given.

The second steering assist torque determining means 22C determines the steering assist torque so that the steering torque generated in the steering system 14 when the steering 1402 is operated matches the ideal steering torque.
When the determined steering assist torque is applied to the motor control means 22D, the motor control means 22D supplies a motor drive current corresponding to the steering assist torque to the power steering motor 18.
By applying the determined steering assist torque to the steering system 14 (steering mechanism 1406), the operation of the steering 1402 by the driver is assisted so that the steering torque matches the ideal steering torque.
In other words, the second steering assist torque determining means 22C makes the driver feel lighter as the steering torque approaches the ideal steering torque, and increases the operation of the steering 1402 as the steering torque moves away from the ideal steering torque. The steering assist torque is determined so as to feel it.

In the present embodiment, the determination of the steering assist torque by the second steering assist torque determining means 22C is made based on the second assist map. In the present embodiment, the second assist map corresponds to an “assist map” in the claims.
Specifically, as shown in FIGS. 6A, 6B, and 6C, the second assist map shows the relationship between the steering torque and the steering assist torque for each ideal steering torque.
The second assist map is stored, for example, in the ROM of the power steering ECU 22 or the like.
The determination of the steering assist torque by the second steering assist torque determination means 22C specifies the steering assist torque (motor drive current value) corresponding to the steering torque detected by the steering torque sensor 16 from the second assist map. Is made by
The drive control of the power steering motor 18 by the motor control means 22D is performed based on the steering assist torque (motor drive current value) determined from the second assist map.
In the present embodiment, the steering assist torque is determined using the second assist map, but the steering assist torque corresponding to the steering torque may be calculated and determined for each ideal steering torque. good. However, this embodiment is advantageous in reducing the processing for determining the steering assist torque.

Next, the operation of the lane departure prevention apparatus 10 will be described with reference to the flowchart of FIG.
First, FIG. 5 and FIG. 6 necessary for explaining the operation will be described.
FIG. 5A is a diagram for explaining a case where the own vehicle 2 that tends to deviate from the travel lane returns to the center line Lc of the travel lane along the correction travel locus, from the right to the left in the figure. The own vehicle 2 is traveling.
FIG. 5B is a diagram showing ideal steering torque values corresponding to the respective positions of the host vehicle 2 shown in FIG.
In the figure, reference signs P1, P2, and P3 indicate positions of the host vehicle 2 that travel along the correction travel locus.

FIGS. 6A, 6B, and 6C show second assist maps corresponding to the positions P1, P2, and P3 of the host vehicle 2 in FIGS. 5A and 5B.
In the drawing, a thick broken line indicates an ideal steering torque value, and a solid line indicates a steering assist torque value in the second assist map.
A thin broken line indicates a steering assist torque value in the first assist map, and is shown for comparison.

Next, a description will be given with reference to the flowchart of FIG.
First, it is determined by the lane departure determining means 38A whether or not the host vehicle 2 tends to depart from the traveling lane (step S10).
If step S10 is negative, step S10 is repeated.
If step S10 is affirmative, a warning display operation by the indicator 26 and a warning sound by the buzzer 28 are performed by the lane departure warning means 38B.
Next, as shown in FIG. 5A, the correction travel locus calculation means 38C determines that the own vehicle 2 returns to the center line Lc of the travel lane based on the own vehicle position information and the travel state information. A correction travel locus L0, which is a locus to be traveled 2 is calculated (step S14).
Next, the ideal steering torque calculation means 22B shows the steering torque generated by the steering mechanism 1406 when the steering 1402 is operated so as to travel along the correction travel locus L0 in FIG. As shown, the ideal steering torque is calculated (step S16).
Next, the second steering assist torque determining unit 22C determines the steering assist torque so that the steering torque generated by the steering mechanism 1406 when the steering 1402 is operated matches the ideal steering torque (step S18).
Next, the power steering device 10 applies the determined steering assist torque to the steering system 14 (step S20).
Steps S18 and S20 will be described later.
Thereafter, the operations of steps S14 to S20 are repeatedly executed until the host vehicle 2 returns to the center line Lc of the travel lane and the correction steering is finished (step S22).
The determination that the host vehicle 2 has returned to the center line Lc of the travel lane and the correction steering has ended is made based on the determination result by the lane departure determination means 38A, for example.

Steps S18 and S20 will be specifically described with reference to FIGS.
The second steering assist torque determining means 22C determines the steering assist torque based on the second assist map shown in FIGS. 6 (A), 6 (B), and 6 (C).
The second assist map corresponding to the position P1 in FIG. 5A is as shown in FIG.
That is, the host vehicle 2 tends to deviate to the right with respect to the center line Lc of the traveling lane at the position P1, and therefore, the steering 1402 needs to be operated leftward.
In this case, the ideal steering torque value is determined as indicated by a broken line in FIG.
In this second assist map, when the steering 1402 is steered to the left (the steering torque is negative), the steering assist torque becomes the maximum at the ideal steering torque value, and the steering assist torque decreases as the distance from the ideal steering torque increases. It is set to be.
That is, in this case, the second steering assist torque determining unit 22C increases the steering assist torque as the steering torque approaches the ideal steering torque, and decreases the steering assist torque as the steering torque moves away from the ideal steering torque. The steering assist torque is determined.
Accordingly, when the steering 1402 is operated, the steering operation feels lighter as the steering torque approaches the ideal steering torque, and the steering operation feels heavier as the steering torque moves away from the ideal steering torque.

Further, the steering assist torque is applied immediately when the steering 1402 is operated to the left from the neutral position (when the steering torque is changed from 0 to a negative region), in other words, from the initial stage of the operation of the steering 1402. The steering assist torque is set immediately.
Therefore, when the steering 1402 is operated, the steering operation in which the steering torque approaches the ideal steering torque is effectively assisted.
Note that when steering 1402 is steered to the right (a region where the steering torque is positive), the operation assist torque is suppressed as compared with the case of the first assist map indicated by the broken line.
Therefore, when attempting to perform a steering operation that further guides the host vehicle 2 in the departure direction, the driver feels that the steering 1402 suddenly becomes heavy, and the steering operation in the departure direction is effectively suppressed.

The second assist map corresponding to the position P2 in FIG. 5A is as shown in FIG.
That is, the host vehicle 2 tends to approach the center line Lc of the traveling lane at the position P2, and therefore, the steering 1402 needs to be operated to the neutral position.
In this case, the ideal steering torque value is determined as indicated by a broken line in FIG.
In the second assist map, when the steering 1402 is steered near the neutral position (the steering torque is near 0), the steering assist torque is set to be 0 (minimum) as in the first assist map. Yes.
Further, when the steering 1402 is operated leftward or rightward from the neutral position, the steering assist torque is suppressed as compared to the case of the first assist map indicated by the broken line.
Also in this case, when the steering 1402 is operated, the steering operation feels lighter as the steering torque approaches the ideal steering torque (the steering 1402 approaches the neutral position), and the steering torque moves away from the ideal steering torque (the steering 1402 The further away from the neutral position, the heavier the steering operation becomes.
Therefore, if the steering operation for guiding the host vehicle 2 in the leftward or rightward deviating direction is performed, the driver feels that the steering 1402 suddenly becomes heavy, and the steering operation in the deviating direction is effective. To be suppressed.

The second assist map corresponding to the position P3 in FIG. 5A is as shown in FIG.
That is, the host vehicle 2 tends to deviate to the left with respect to the center line Lc of the travel lane at the position P3, and therefore the steering 1402 needs to be operated rightward.
In this case, the ideal steering torque value is determined as indicated by a broken line in FIG.
In this second assist map, when the steering 1402 is steered to the right (the steering torque is positive), the steering assist torque becomes the maximum at the ideal steering torque value, and the steering assist torque decreases as the distance from the ideal steering torque increases. It is set to be.
That is, in this case, the second steering assist torque determining unit 22C increases the steering assist torque as the steering torque approaches the ideal steering torque, and decreases the steering assist torque as the steering torque moves away from the ideal steering torque. The steering assist torque is determined.
Accordingly, when the steering 1402 is operated, the steering operation feels lighter as the steering torque approaches the ideal steering torque, and the steering operation feels heavier as the steering torque moves away from the ideal steering torque.

Further, the steering assist torque is applied immediately when the steering 1402 is operated rightward from the neutral position (when the steering torque is changed from 0 to a positive region), in other words, from the initial stage of the operation of the steering 1402. The steering assist torque is set immediately.
Therefore, when the steering 1402 is operated, the steering operation in which the steering torque approaches the ideal steering torque is effectively assisted.
When the steering 1402 is steered leftward (the region where the steering torque is negative), the operation assist torque is suppressed as compared with the case of the first assist map indicated by the broken line.
Therefore, when attempting to perform a steering operation that further guides the host vehicle 2 in the departure direction, the driver feels that the steering 1402 suddenly becomes heavy, and the steering operation in the departure direction is effectively suppressed.

As described above, according to the present embodiment, when it is determined that the host vehicle 2 tends to deviate from the traveling lane, the host vehicle 2 returns to the center line Lc of the traveling lane. A correction travel locus that is a locus to be traveled is calculated. A steering torque generated in the steering system 14 when the steering 1402 is operated so that the host vehicle 2 travels along the correction travel locus is calculated as an ideal steering torque. Then, the steering assist torque is determined so that the steering torque generated in the steering system 14 when the steering 1402 is operated matches the ideal steering torque.
Therefore, it is advantageous in accurately assisting the steering operation for smoothly returning the host vehicle 2 to the traveling lane.
Therefore, if the driver turns the steering too far in the direction opposite to the departure direction, the steering operation cannot be suppressed, or the steering operation when returning the host vehicle 2 to the original travel lane is also suppressed. There is no inconvenience of turning around, which is advantageous in realizing an accurate steering operation.

  DESCRIPTION OF SYMBOLS 10 ... Lane departure prevention device, 14 ... Steering system, 1402 ... Steering, 22B ... Ideal steering torque calculation means, 22C ... Second steering assist torque determination means (steering assist torque determination means), 38A ... Lane departure determination means, 38B... Lane departure warning means, 38C.

In order to achieve the above object, the present invention includes a power steering device that applies, to a steering system, steering assist torque that is applied in the same direction as the direction in which the steering is operated based on a steering operation by a driver. A lane departure prevention device for a vehicle, wherein the vehicle lane departure determination means determines whether the vehicle tends to deviate from the traveling lane based on own vehicle position information indicating a positional relationship of the own vehicle with respect to the traveling lane. When it is determined that the host vehicle does not tend to deviate from the driving lane, a first steering assist torque to be applied in the same direction as the steering direction is determined based on the steering operation. a first steering assist torque determining means, when the it is determined that there is a tendency that the vehicle deviates from the travel lane, the own vehicle position information and the own A modified traveling locus calculating means said host vehicle calculates the traveling locus for modifying the vehicle is track should travel in order to return to the center line of the traveling lane on the basis of the traveling state information concerning the traveling state of the two, Steering that occurs in the steering system when it is determined that the host vehicle tends to deviate from the travel lane and the steering is operated so that the host vehicle travels along the correction travel locus. Ideal steering torque calculating means for calculating torque as ideal steering torque, and steering torque generated in the steering system when the steering is operated when it is determined that the host vehicle tends to deviate from the driving lane There a second steering assist torque determining means for determining a steering rudder auxiliary torque to match the ideal steering torque, the first steering assist torque determining means and before The second steering assist torque determining means, when the steering said steering in the vicinity of the neutral position, is set an area where each of the first steering assist torque and the second assist torque becomes zero, it It is characterized by.

Claims (7)

A vehicle lane departure prevention device including a power steering device that applies a steering assist torque to a steering system based on a steering operation by a driver,
Lane departure determination means for determining whether or not the host vehicle tends to depart from the traveling lane based on own vehicle position information indicating the positional relationship of the own vehicle with respect to the traveling lane;
When it is determined that the host vehicle tends to deviate from the travel lane, the host vehicle returns to the center line of the travel lane based on the host vehicle position information and the travel state information related to the travel state of the host vehicle. Correction trajectory calculating means for calculating a correction travel trajectory that is a trajectory to be traveled by the host vehicle,
Ideal steering torque calculating means for calculating a steering torque generated in the steering system as an ideal steering torque when the steering is operated so that the host vehicle travels along the correction travel locus;
Steering assist torque determining means for determining the steering assist torque so that a steering torque generated in the steering system when the steering is operated matches the ideal steering torque;
A lane departure prevention device characterized by the above. The determination of the steering assist torque by the steering assist torque determining means is such that the driver feels the steering operation lighter as the steering torque approaches the ideal steering torque, and the steering torque is further away from the ideal steering torque. The steering operation is made to feel heavy,
The lane departure prevention apparatus according to claim 1. The determination of the steering assist torque by the steering assist torque determining means is that the steering assist torque increases as the steering torque approaches the ideal steering torque, and the steering assist torque increases as the steering torque moves away from the ideal steering torque. The torque is made smaller,
The lane departure prevention apparatus according to claim 1. The traveling state information includes a vehicle speed of the host vehicle and a curvature radius of a road on which the host vehicle is traveling.
The lane departure prevention apparatus according to any one of claims 1 to 3, wherein the lane departure prevention apparatus according to any one of claims 1 to 3 is provided. The traveling state information further includes a maximum yaw rate of the host vehicle and a maximum turning radius of the host vehicle.
5. A lane departure prevention apparatus according to claim 4, wherein An assist map showing the relationship between the steering torque and the steering assist torque is determined in advance for each ideal steering torque, and the steering assist torque is determined by the steering assist torque determining means based on the assist map. The
The lane departure prevention apparatus according to any one of claims 1 to 5, wherein the lane departure prevention apparatus according to any one of claims 1 to 5 is provided. Lane departure warning means for performing a warning operation for warning the lane departure tendency of the host vehicle when it is determined that the host vehicle tends to depart from the driving lane;
The lane departure prevention apparatus according to any one of claims 1 to 6, wherein the lane departure prevention apparatus according to any one of claims 1 to 6 is provided.

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