JP3186662B2 - Lane departure prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing a vehicle from deviating from a traffic lane by applying a steering control torque such that the driver can easily overcome the driver's steering force in a direction for preventing the vehicle from deviating from the traffic lane. The present invention relates to a lane departure prevention device for guiding departure prevention.

[0002]

2. Description of the Related Art In recent years, there has been developed a technology (driving guidance device) for grasping the position and posture of a vehicle with respect to a traveling road, performing automatic traveling control of a vehicle based on the grasp, and guiding a driver to drive. Is being developed. In the case of automatic cruise control, it is necessary to drive a car without relying on the driver at all, and various conditions such as the development of basic facilities (infrastructure) such as roads are premised on the practical application. Become.

[0003] On the other hand, in the case of a driving guide device, it is the driver who drives the vehicle, and the driving guide device informs the driver of a driver's driving error and assists the driver in the direction to eliminate the mistake. It is. Therefore, the driving guidance device has many technologies that can be realized even in the current road environment, and it is desired to develop a driving guidance device with higher practicality.

[0004] One of such driving guide devices is a lane departure prevention device. As this lane departure prevention device, there is a technology (Japanese Patent Laid-Open No. 63-214900) that issues a warning to a driving vehicle when the vehicle is inadvertently deviating from the traveling lane. However, simply issuing a warning may not be effective for a driver who is dozing off. Therefore, the steering control is more positively performed so that the vehicle travels at a certain position (for example, the center position) in the traveling lane. Technology (Japanese
-270005) has also been proposed.

Further, in the case where the vehicle is controlled so as to maintain a fixed position in the traveling lane as described above, when the vehicle attempts to protrude from the traveling lane due to a temporary steering abnormality such as careless steering by a driver. If this control works, it may cause a buffer with other vehicles. For this reason, in such a case, instead of returning the vehicle to a certain position in the traveling lane, a technique of performing steering control so as to maintain a position biased to the side where the vehicle is going to protrude even in the traveling lane ( Japanese Patent Application Laid-Open No. 5-297939 is also proposed.

[0006]

By the way, in the case of the lane departure prevention device which is one of the driving guide devices as described above,
It is necessary to apply a steering control torque through a steering actuator separately from the driver's steering force in order to prevent the vehicle from deviating from the driving lane, but the steering control torque to be applied in this case must be too small. The effect cannot be expected. On the contrary, if it is too large, the steering operation by the driver itself is hindered.

That is, the steering control torque for preventing the lane departure as the driving guide is for guiding the driver's steering operation or assisting the steering in the direction to eliminate the driver's steering error. And the subject to be steered is the driver. Therefore, the main purpose of the application of the steering control torque in this case is to inform the driver that the vehicle is about to deviate from the driving lane, and the steering torque for actually holding the vehicle in the lane is I want to be added by the driver itself.

[0008] In particular, it is difficult to accurately determine whether the vehicle is about to deviate from the driving lane against the driver's will. For example, if the vehicle is likely to deviate from a reference position (for example, the center in the width direction of the lane) in the driving lane, it can be determined that the vehicle is likely to deviate from the driving lane unexpectedly. Then
Even when the driver intends to leave the driving lane, such as when changing lanes, it is determined that the vehicle is deviating from the driving lane.

When a control torque is generated by the steering actuator based on such determination, the steering control is performed in a direction opposing the driver's steering operation when the driver intends to depart from the traveling lane. Torque will be generated, and if the steering control torque is too large, it will interfere with steering operations such as lane change by the driver's intention, and from this point too, make sure that the steering control torque does not become excessive. Want to.

[0010] By the way, it is determined whether or not the vehicle is about to deviate from the traveling lane by determining whether the position of the traveling vehicle (hereinafter referred to as own vehicle) is from a reference position of the traveling lane (generally, a road center line). The determination can be made on the basis of how much the lateral displacement is to the left or right. Further, if the steering control torque to be applied is increased as the lateral shift amount increases, a warning can be issued with a control torque amount corresponding to the degree of lane departure.

However, if the steering control torque applied to the lane in which the vehicle is traveling is increased as the lateral displacement increases, the lane is changed from the traveling lane to another lane adjacent thereto (lane lane). change)
When performing the above, a problem occurs. That is, when a lane change (lane change) is performed, as shown in FIG. 8A, the vehicle 100 deviates from the lane (first lane) 101 that has been traveling up to the lane 101 and enters the lane 101. You will be entering the adjacent lane (second lane) 102,
Focusing on the amount of lateral displacement of the vehicle 100, the vehicle 100 firstly moves toward the second lane 102 in the first lane 101 (right side in this example) as shown by a curve 105 in FIG. 8B.
After increasing the lateral shift amount to the second lane 102 from the first lane 101 (that is, both lanes 101 and 1).
(Exceed the road white line 103 between 02)
As indicated by the curve 106 shown in FIG.
02 is to be reduced. Note that reference numeral 104 indicates a locus around the center of the vehicle.

Therefore, if the setting is made so that a larger steering control torque is applied as the lateral shift amount is larger, FIG.
As shown by a curve 107 shown in FIG. 4D, the vehicle 100 first increases the steering control torque to the lane center side (the left side in this example) in the first lane 101, and from the first lane 101 At the moment when the vehicle gets into the second lane 102, as shown by a curve 108 in FIG. 8 (d), the steering control torque is switched to the lane center side (the right side in this example) in the second lane 102 this time. This steering control torque is
It gradually decreases.

Therefore, at the moment when the vehicle crosses from the first lane 101 to the second lane 102, the steering control torque applied to the vehicle suddenly changes in the opposite direction, which may reduce the ride comfort of the vehicle, May become unstable. The present invention has been made in view of the above-described problems, and can provide a steering control torque in accordance with the amount of lateral displacement of a vehicle without hindering a steering operation by a driver's intention, and when the traveling lane is changed, the vehicle can be controlled. It is an object of the present invention to provide a lane departure prevention device that can guide a driver to avoid a lane departure while preventing a decrease in ride comfort and an unstable behavior.

[0014]

Therefore, in the lane departure prevention device of the present invention, the lateral deviation calculating means calculates the lateral deviation of the traveling position of the vehicle from the reference position of the traveling lane, and the control torque calculating means. Calculating a steering control torque that the driver can easily overcome based on the lateral shift amount calculated by the lateral shift amount calculating unit, and controlling the control torque in a direction in which the control torque calculated by the control torque calculating unit reduces the lateral shift amount. The steering actuator is controlled so as to generate the following. Thereby, prevention of the lane departure of the own vehicle is guided.

On the other hand, the overtaking determination means determines whether or not the own vehicle has overtaken another adjacent driving lane. If the overtaking determination means determines that the own vehicle has overtaken, the sudden change suppressing means includes: Suppress sudden changes in control torque.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 to 7 show a lane departure prevention device as an embodiment of the present invention. The lane departure prevention device (also referred to as a lane guidance system) is provided to prevent the vehicle from deviating from the traveling lane in an automobile. When there is a possibility that the steering torque is different from the steering torque applied by the driver by the steering actuator 21 provided to the vehicle as shown in FIG. 1 (this steering torque is used to distinguish it from the steering torque applied by the driver). Control torque) to warn the driver during steering through a steering wheel (hereinafter also referred to as a steering wheel) 20 of a lane departure.

Of course, the steering control torque itself is also
The main purpose of this steering control torque is to warn the driver through the steering system, and to correct the position of the vehicle that is likely to deviate from the lane. It should be performed by the driver's steering operation that recognizes that the vehicle is likely to depart from the lane due to the application of the control torque.

Therefore, the present lane departure prevention device is not shown in FIG.
As shown in FIG. 1, in order to recognize the position of the host vehicle with respect to the traveling lane, a camera 2 as an image pickup means for picking up an image of a road condition ahead of the vehicle 1 and image information from the image information from the camera 2 are appropriately processed. Information processing means 3 for recognizing the left and right white line positions on the front road, and a lateral shift amount ΔY for calculating a lateral shift amount ΔY with respect to a reference position of a traveling lane (traveling lane) from the white line position image information by the image information processing means 3 It has an amount calculating means 4A.

The lateral deviation ΔY corresponds to a determination parameter relating to the degree that the vehicle 1 is likely to depart from the lane. The lateral displacement amount calculating means 4A is provided as a functional element in the traveling lane estimating means 4 for estimating the relative position of the traveling lane (traveling lane) with respect to the own vehicle. Further, the present lane departure prevention device is provided with the lateral displacement amount calculating means 4A.
Is calculated based on the lateral deviation amount (lateral deviation) ΔY, that is, the degree of departure from the lane.
c, a steering actuator 21 capable of applying the steering control torque Tc to the steering system separately from the steering torque applied by the driver, and a steering control calculated by the control torque calculation unit 5. A control means (controller) 6 for controlling the steering actuator 21 so that the torque Tc is generated in a direction to reduce the lateral shift amount ΔY is provided.

A setting switch (SW) 23 is provided as control torque adjusting means for selecting the operation of the lane departure prevention device and adjusting the control torque level for steering. Therefore, if you want to operate the device, switch 2
Turn on switch 3 if you do not want to operate the device.
3 can be selected according to the driver's preference, and when the switch 23 is turned on, the lane departure prevention control by the present device is strengthened or weakened, that is, the steering control torque Tc given by the steering actuator 21. Level can be increased or decreased.

Further, for example, in the instrument panel (instrument panel), when the switch 23 is on, or
When a control torque for preventing lane departure is applied, an operation display unit 24 for displaying the control torque is provided.
Further, even if the setting switch 23 is turned on, the present lane departure prevention device controls the lane departure prevention if the direction instruction switch (the switch for turning on the turn signal lamp) 26 is in the lighting command state. The torque is set so as not to be applied.

Therefore, the control torque calculating means 5 includes:
An on / off signal from the setting switch 23 and the direction instruction switch 26 is input. Here, the recognition of the position of the host vehicle with respect to the traveling lane, that is, the calculation of the lateral deviation amount ΔY of the host vehicle will be described in detail. In the image information processing means 3, first, as shown in FIG.
, The road white line is extracted from the original image 41, and the image of the extracted road white line is converted into a two-dimensional image 42 as viewed from vertically above.

Next, recognition of the white lines 12L and 12R will be described with reference to FIG. Here, the recognition of the white line 12L as the roadside line at the left end of the traveling lane will be described. However, the same applies to the case where the white line 12R at the right end of the traveling lane is used as a reference. I will call it. Next, in the image information recognizing means 3, as shown in FIG. 3 (a), the camera 2 provided in the vehicle 1 captures monochrome image information in a range in front of the vehicle (for example, 5 m to 30 m) on flat ground, and Some images in the vertical direction on the screen are omitted from the information.
Then, a plurality of horizontal lines 11 are set at equal intervals on this screen.

The capture of the black and white image information is updated every minute control cycle. As shown in FIG. 3 (b), the white line position on the previous screen on each horizontal line 11 is determined. The required range on the left and right (here, 5
0 pixel [dot]) is the white line search area (processing target area)
Set as 10. For the first screen, the white line position on the straight road is used as the previous screen data.

Then, as shown in FIG. 3C, the brightness of each horizontal line is differentiated in the horizontal direction from the left. Reference numeral 14 in the figure is a guardrail. By the way, a normal road surface has low luminance and a small change in luminance. On the contrary,
Since the brightness of the white line 12 is much higher than that of the normal road surface, when the brightness of the road is differentiated in this way, the luminance change is positive at the boundary point from the normal road surface to the white line 12, and the white line 12 changes to the normal road surface. Differential data is obtained such that the luminance change becomes negative at the boundary point of. FIG. 3D shows an example of such differential data.

Then, for each of the data of each horizontal line 11, peaks of the differential values appear in the order of plus and minus from the left, and the interval between the peaks is the white line 12.
Is extracted as a candidate for a white line, and a combination that falls within a reasonable degree (interval between a positive peak and a negative peak is within 30 dots, for example) is extracted.
As shown in FIG. 3E, the midpoint M is set to the white line candidate point 15.
Save as

Then, among these white line candidate points 15,
Only the point closest to the screen center is left as the final candidate point.
This means that, for example, when the vehicle 1 is traveling on the left side, the search area 1
The right side of 0 is a road surface with little change in normal luminance, and the white line candidate point 15 closest to this normal road surface can be determined as the white line 12. Therefore, further to the left of the white line 12,
Objects that cause noise (for example, guardrails 14)
Is present, the white line 12 can be reliably recognized from the image information captured by the camera 2.

Finally, as shown in FIG. 3F, the vertical continuity of the white line candidate points 15 in each horizontal line data is sequentially verified from the bottom of the screen. First, the inclination between the upper and lower ends of the white line 12 on the previous screen is calculated in advance.
Then, assuming that the lowest point 15A is the white line 12, it is verified whether or not the candidate point 15B on the horizontal line 11 which is only one line above is within the range of ± 50 dots of the inclination of the previous white line 12.

If the candidate point 15B falls within this range, it is regarded as a white line. If not, the candidate point 15B is rejected, and the coordinates obtained by interpolation from the above-mentioned inclination are regarded as the white line position. By performing the same operation for each horizontal line for this detection, a continuous white line 12 can be recognized. Such white line recognition work is continuously performed at a required cycle, and the recognition of the white line 12 is updated each time.

The white line 12 as the roadside line at the right end of the traveling lane
The recognition of R is performed in the same manner. In the estimating means 4, the original image 41 thus recognized in each recognition cycle
The upper white lines 12R and 12L are converted into a two-dimensional image 42,
Based on the road centerline LC _R from traveling lane left to the road central line LC _L which can be estimated from the white line 12L traveling lane right edge of the white line 12R can estimate, by performing estimation of a road center line LC, the center line of the road The lateral deviation amount ΔY and the deflection angle β are calculated by the lateral deviation amount calculating means 4A based on the LC.

The declination β is, as shown in FIG. 4, the angle between the tangent to the curved road center line LC and the vehicle center line direction, and is the first detection point ( It is calculated from reference line position information at a perigee in the figure) and reference line position information at a second detection point (shown as apogee in the figure) further away from the vehicle 1 by a predetermined amount from the perigee. be able to.

That is, the declination β is calculated as an angle between a straight line connecting the first detection point and the second detection point and the center line of the vehicle 1. The declination calculated in this way is a declination at an intermediate point between the first detection point and the second detection point (indicated by x in the drawing), and is a declination at least a point ahead of the vehicle 1 by a certain distance or more. . In this example, the point closest to the vehicle on the road center line LC based on the image information from the camera 2 is set as the first detection point, and the position between the own vehicle center line and the road center line LC at the first detection point is determined. The directional distance (the road width direction, the lateral distance of the camera image) is calculated as the lateral deviation amount (lateral deviation) ΔY. Further, the curve radius R is estimated based on the calculated declination β.

Further, the estimating means 4 determines that when the vehicle center line crosses the left or right road white line (that is, the vehicle crosses the lane) and enters the adjacent lane, the vehicle center line moves to the road center of the new lane. On the other hand, the lateral shift amount ΔY of the vehicle center line is calculated. For this reason, the estimating means 4 determines whether the vehicle center line has crossed the road white line,
There is provided an overtaking judging means 7 for judging whether or not the own vehicle has overtaken another adjacent driving lane based on whether or not Y has become larger than one half of the calculated road width. When the overtaking determination means 7 determines that the own vehicle has crossed the other lane, the fact is transmitted to the lateral displacement amount calculating means 4A, and the lateral displacement amount calculating means 4A sets the vehicle center with respect to the road center of the new lane. The lateral displacement amount ΔY of the line is calculated.

The control torque calculating means 5 calculates the steering control torque Tc with a characteristic as shown in FIG. 6 based on the amount of lateral displacement of the vehicle with respect to the reference position of the traveling lane (the center position of the road width). The setting of the steering control torque Tc is performed as follows. In other words, the steering control torque Tc is different from the steering torque used for automatic steering, and the main purpose is to warn the driver.
Since the position of the vehicle is corrected by the driver's steering operation, the steering control torque Tc is limited to a magnitude that does not hinder the driver's steering operation, that is, a magnitude that the driver can easily overcome. I have.

Therefore, even when the steering control torque Tc is applied in a direction to avoid the departure when the vehicle is likely to deviate from the lane, it is sufficient if the driver tries to perform the steering operation in the direction deviating from the lane. You can do this. As a result, emergency steering for retreating the vehicle out of the travel lane can be easily performed, and even if the steering control torque Tc is applied at the time of lane change, it does not hinder lane change. .

In the present lane departure prevention device, a low-pass filter (LPF) 25 is interposed between the control torque calculating means 5 and the controller 6, and the low-pass filter 25 is set by the control torque calculating means 5. Even when the control torque suddenly changes, the output of the control torque calculation information is smoothed so that the control torque actually exerted by the steering actuator 21 does not suddenly change but continues smoothly.

Therefore, for example, the direction indicating switch 26
Is turned on (from off to on), the control torque calculating means 5 may change the steering control torque Tc from a certain value to 0. In this case, the low-pass filter 25 As a result, the command value of the steering control torque Tc input to the controller 6 does not suddenly change to zero but gradually decreases to zero.

Conversely, when the direction indicating switch 26 is turned off (turned from on to off), the control torque calculating means 5 may change the steering control torque Tc from 0 to a certain value. However, also in this case, the command value of the steering control torque Tc input to the controller 6 gradually increases from 0 without sudden increase due to the smoothing process by the low-pass filter 25.

If the vehicle 1 changes lanes (lane change) in a state where the direction indicating switch 26 is not turned on, the steering control torque Tc according to the lateral deviation amount ΔY is set. When the vehicle crosses from the lane (first lane) to another adjacent lane (second lane), the steering control torque for returning to the center of the first lane is relatively large. The steering control torque suddenly changes to a relatively large steering control torque that is to be led to the center of the second lane. However, also in this case, the sudden change of the command value of the steering control torque Tc input to the controller 6 is suppressed by the smoothing process by the low-pass filter 25, so that the low-pass filter 25 can pass over the own vehicle. In this case, it functions as a sudden change suppressing means for suppressing a sudden change in the control torque.

Further, in the present embodiment, the low-pass filter 25 is configured to have a variable time constant. It has been changed to a large time constant. As described above, when the time constant is made larger than the normal time, in the low-pass filter 25, the smoothing of the steering control torque Tc set by the control torque calculating means 5 is further strengthened and input to the controller 6. Variations in the command value of the steering control torque Tc are further suppressed.

Therefore, when the information for determining whether the host vehicle has passed the vehicle is sent, the fluctuation of the control torque is further suppressed for a predetermined period of time as compared with the normal time, and the function of the low-pass filter 25 as the sudden change suppressing means is strengthened. is there.
The image information processing means 3, the traveling lane estimating means 4 (lateral deviation amount calculating means 4A), the control torque calculating means 5, the controller 6 and the like include a CPU, an input / output interface, and an RO.
It is configured as an electronic control unit including M, RAM, and the like.

Further, although not shown in detail, the steering actuator 21 may be any actuator capable of applying a torque to the steering shaft. For example, a small electric torque installed below the torsion bar (on the power steering side) of the steering shaft. It may be constituted by a motor. Since the lane departure prevention device as one embodiment of the present invention is configured as described above, the lane departure prevention process is performed, for example, as shown in FIG.

That is, as shown in FIG. 6, first, it is determined whether or not the control switch 23 is turned on (step A1).
0) If the control switch 23 is not on, the lane departure prevention process is not performed. If the control switch 23 is on, the process proceeds to step A20, where it is determined whether the direction switch 26 is on. Here, the direction indication switch 26
Is ON, the lane departure prevention process is not performed. However, if the direction indicating switch 26 is not ON, step A30 is executed.
The following processing is performed.

That is, first, after adjusting the level of the control torque Tc according to the set level of the control switch 23 (step A30), the control torque calculating means 5 calculates the control torque Tc according to the lateral shift amount ΔY. (Step A
40). Then, the control torque calculating means 5 outputs a control amount corresponding to the control torque Tc calculated in step A40, and outputs an operation display signal to the operation display unit 24 (step A50).

The signals from the control torque calculating means 5 are sent to the controller 6 through a low-pass filter (LPF) 25. In step A60, the overtaking determination means 7 must determine that the own vehicle has overtaken another lane. For example, in the low-pass filter 25, the time constant is set to a normal state, and the steering control torque Tc set by the control torque calculation means 5 is smoothed and output. Based on such a control command value, the steering actuator 21 The operation is displayed, and the fact that the control torque Tc is being applied is displayed on the operation display section 24 (step A80).

By smoothing the steering control torque Tc, even when the control torque set by the control torque calculation means 5 changes suddenly, the control torque actually exerted by the steering actuator 21 does not change suddenly but smoothly. The output of the control torque calculation information is processed so as to be continuous. On the other hand, if the overtaking determination means 7 determines in step A60 that the own vehicle has overtaken the other lane, the low-pass filter 25 sets the control torque in a state where the time constant is large for a predetermined time from this determination time. The control torque for steering Tc set by the calculation means 5 is smoothed and output, and based on such a control command value, the steering actuator 21 is operated and the operation display section 24 supplies the control torque Tc. Are displayed (step A70).

If the steering control torque Tc is smoothed by increasing the time constant in this way, a sudden change in the command value of the steering control torque Tc input to the controller 6 is further suppressed, so that the vehicle changes lanes (lane). Change), and the vehicle steers to another lane, the steering control torque suddenly changes in the opposite direction. However, the low-pass filter 25 performs a strong smoothing process to reduce the command value of the steering control torque Tc input to the controller 6. The sudden change is greatly suppressed, and the low-pass filter 25 largely functions as a sudden change suppressing unit that suppresses a sudden change in the control torque when the own vehicle gets over.

The processing for applying the control torque will be described in further detail. To calculate the control torque, first, the amount of lateral deviation ΔY, which is an index of how much the vehicle deviates from the traveling lane, is calculated. It needs to be calculated. In this device, the traveling lane estimating means 4 estimates the relative position of the traveling lane (traveling lane) with respect to the own vehicle, and calculates the lateral deviation amount ΔY based on the estimated position. Here, camera 2
Of the vehicle center line and the road center line LC at the point (first detection point) closest to the vehicle on the road center line LC based on the image information based on It is calculated as a lateral shift amount (lateral deviation) ΔY.

That is, in the present apparatus, white line recognition is performed for the white line 12L at the left end of the running lane and the white line 12R at the right end of the running lane. Position (in other words, the position of the vehicle with respect to the traveling lane) is estimated.
The recognition of R will be described with reference to the left white line 12L as an example.

First, as shown in FIG.
On a flat ground, the area in front of the vehicle (for example,
m), the monochrome image information is fetched for each minute control cycle, and a plurality of horizontal lines 11 are set at regular intervals on this screen for each cycle. Then, as shown in FIG.
On each horizontal line 11, a required range of the left and right positions of the white line position on the previous screen (for example, left and right 50 pixels [do
t]) is set as a white line search area (processing target area) 10. In the initial screen, a white line position on a straight road is used as previous screen data.

From the image information, as shown in FIG. 3C, the brightness of each horizontal line is differentiated in the horizontal direction from the left, and the differential data of each horizontal line is obtained as shown in FIG. 3D.
From the left], the peaks of the differential values appear in the order of plus and minus from the left, and the interval between the peaks is considered to be appropriate as the white line 12 (the interval from the plus peak to the minus peak is, for example, within 30 dots). ) Are extracted as white line candidates, and the midpoint thereof is stored as a white line candidate point 15 (see FIG. 3E).

Then, among these white line candidate points 15,
Only the point closest to the screen center is left as the final candidate point.
By limiting the white line candidate point 15 to the one closest to the center of the screen in this way, an object that causes noise (for example, the guardrail 14 or a vehicle in another traveling lane) exists outside the white line 12. Even in this case, the white line 12 can be reliably recognized from the image information obtained by the camera 2.

Finally, as shown in FIG. 3 (f), the continuity of the white line candidate points 15 in each horizontal line data in the vertical direction is sequentially verified from the bottom of the screen. First, the inclination between the upper and lower ends of the white line 12 on the previous screen is calculated in advance. If the lowermost point 15A is the white line 12, the candidate point 15B on the upper horizontal line 11 is calculated by the inclination ± 5 of the previous white line 12.
0 dot is compared, and candidate point 1
If 5B is within this range, it is regarded as a white line. If not, the candidate point 15B is rejected, and the coordinates calculated by interpolation from the above-mentioned inclination are regarded as the position of the white line.

By performing such an operation for each horizontal line, continuous white lines 12 can be recognized. Such white line recognition work is continuously performed at a required cycle, and the recognition of the white line 12 is updated each time.
In this manner, the white lines 12L, 1 on the left and right of the traveling lane are periodically repeated.
Recognition of 2R is performed in the same manner.

Then, the estimating means 4 calculates each road center line L
C _L, roads and averages the LC _R centerline LC (= LC _L + _L
C _R ) is calculated. Road center line LC estimated in this way
, The lateral shift amount (lateral deviation) ΔY and declination β and the curvature of the traveling lane (road curvature) are calculated.
The steering control torque T by the control torque calculation means 5 is used.
The calculation of c can be performed according to the lateral deviation amount (lateral deviation) ΔY using, for example, a map as shown in FIG. 7 or another table or an arithmetic expression.

As described above, in the present lane departure prevention device, the driver can control the lane departure (departure from the road center line) by applying the control torque Tc to the extent that the driver can easily overcome in accordance with the lateral deviation amount ΔY. Correction direction is handle 2
It can be sensed from the feeling of steering maintenance of 0 or the like, and the steering operation of the driver allows the vehicle position to be quickly corrected.

The steering control torque Tc itself is effective not only for warning the driver, but also for correcting the vehicle position. The warning by the steering control torque Tc is as follows.
For example, it is also effective for a driver of inattentive driving. In this case, the driver is encouraged to prevent inattentive driving while preventing a deviation from the lane. Moreover, in the present lane departure prevention device, the steering control torque Tc is smoothed by the low-pass filter 25 and output.
The steering control torque generated by the steering actuator 21 is smoothly continuous without abrupt change, and has an advantage that the control of lane departure prevention can be stabilized. Even when a lane change (lane change) is performed to another lane, the steering control torque can be smoothly applied.

That is, when a lane change is performed, as shown by a curve 104 in FIG. 7A, the vehicle 100 is shifted from the traveling lane (first lane) 101 to another adjacent lane. The vehicle enters the (second lane) 102. At this time, while traveling in the lane 101, the lateral deviation amount ΔY with respect to the road center line of the first lane 101 is calculated, and the vehicle crosses the lane. When the vehicle travels in the lane 102, the amount of lateral shift ΔY with respect to the road center line of the second lane 102 is calculated.

Therefore, the lateral deviation amount ΔY gradually increases toward the second lane 102 (to the right in this example) as shown by a curve 105 in FIG. 7B until the vehicle crosses the lane.
After passing through the lane, the curve 106 shown in FIG.
As described above, the amount of lateral displacement with respect to the second lane 102 (the left side in this example) is gradually reduced. The control torque setting means 5 sets a larger steering control torque Tc as the lateral shift amount is larger. Therefore, when the steering control torque Tc is exerted by the steering actuator 21 as it is, a dashed line in FIG. Curves 107, 10
As shown in FIG. 8, at the moment when the vehicle crosses the lane, the steering control torque Tc greatly fluctuates in the opposite direction.

On the other hand, in the present lane departure prevention device,
The low-pass filter 25 as a sudden change suppressing means whose time constant has been changed to a large one has a steering control torque Tc.
Therefore, even if the control torque set by the control torque calculation means 5 changes suddenly, the control torque actually exerted by the steering actuator 21 is as shown in FIG.
As shown by a solid line 109, the image is smoothly continuous without abrupt change. For this reason, even when the vehicle changes lanes (lane change) and crosses another lane, a sudden change in the control torque is reliably suppressed, and there is a risk that the ride comfort of the vehicle will be reduced and the behavior of the vehicle will be unstable. The risk of becoming such is also avoided.

Of course, as long as the vehicle does not enter another lane, the driver is reliably warned to prevent the lane departure by applying the steering control torque corresponding to the amount of the lateral deviation.
The lane departure prevention effect can be secured without any hindrance. Even if the time constant of the low-pass filter 25 is not changed to a large value, for example, as shown by a broken line 109 in FIG. It may be possible to avoid to some extent the risk of lowering the riding comfort of the vehicle and the unstable behavior of the vehicle without any change.

Further, in the present lane departure prevention device, when the driver operates the direction indicator to change lanes, the direction indicator switch 26 is turned on so that the control torque is not applied. Since the processing is performed, in this case, unnecessary application of the control torque is avoided, and the loads on the steering actuator 21 and other members involved in the application of the control torque are reduced.

Of course, also in this case, the low-pass filter 2
5 prevents a sudden change in the control torque, so that the control torque is not suddenly stopped, and a feeling of strange steering due to a sudden change in the control torque is also avoided. Further, the sudden change suppressing means for suppressing the sudden change in the control torque is not limited to the low-pass filter 25, and the change of the calculated value itself may be suppressed in the control torque setting means 5 calculating the control torque.

[0064]

As described in detail above, the lane departure prevention device of the present invention can provide guidance for lane departure prevention by applying a steering control torque without hindering a driver's intention of steering operation. In addition, when the own vehicle gets into an adjacent driving lane, a sudden change in the control torque is suppressed. Therefore, when the lane is changed, the riding comfort of the vehicle is deteriorated due to a sudden change in the steering control torque, and the behavior is unstable. Can be avoided, and guidance for avoiding lane departure can be given while ensuring various performances of the vehicle.

[Brief description of the drawings]

FIG. 1 is a block diagram schematically showing a configuration of a lane departure prevention device as one embodiment of the present invention.

FIG. 2 is a diagram illustrating image processing for driving lane recognition according to an embodiment of the present invention.

FIG. 3 is a schematic diagram illustrating traveling lane recognition according to an embodiment of the present invention in the order of (a) to (f).

FIG. 4 is a schematic plan view illustrating travel lane recognition.

FIG. 5 is a diagram showing a control torque setting map according to the lane departure prevention device as one embodiment of the present invention.

FIG. 6 is a flowchart illustrating an operation for applying a steering control torque of the lane departure prevention device as one embodiment of the present invention.

FIG. 7 is a time chart showing a setting example of a control torque when the vehicle crosses a lane by the lane departure prevention device as one embodiment of the present invention, where (a) shows a traveling position of the vehicle,
(B) and (c) show the amount of lateral displacement of the vehicle, and (d) shows the corresponding control torque.

FIG. 8 is a time chart showing a setting example of a control torque when the vehicle crosses a lane by a conventional lane departure prevention device;
(A) shows the running position of the vehicle, (b) and (c) show the amount of lateral displacement of the vehicle, and (d) shows the corresponding control torque.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 vehicle 2 camera 3 image information processing means 4 running lane estimating means 4A lateral displacement calculating means 5 control torque calculating means 6 control means (controller) 7 getting over determining means 20 steering wheel (handle) 21 steering actuator 22 steering wheel 23 setting switch 24 Operation display section 25 Low-pass filter (sudden change suppression means) 26 Direction switch LC Road center line

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-6-255514 (JP, A) JP-A-7-160995 (JP, A) JP-A-6-300580 (JP, A) JP-A-5-205 170118 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G08G 1/00-9/02 B60R 21/00 620 B62D 6/00-6/06

Claims (1)

(57) [Claims] When the vehicle deviates from the traveling lane, a steering control torque is applied by the steering actuator of the vehicle so that the driver can easily overcome the steering force of the driver in a direction to prevent the deviation. A lane departure prevention device that guides prevention of lane departure of the host vehicle, comprising: a lateral deviation amount calculating unit that calculates a lateral deviation amount of a traveling position of the host vehicle from a reference position of the traveling lane; Control torque calculating means for calculating a control torque based on the lateral shift amount calculated in the step (c), and controlling the steering actuator so that the control torque calculated by the control torque calculating means is generated in a direction to reduce the lateral shift amount. Control means for determining whether or not the host vehicle has crossed another adjacent driving lane; and Characterized in that it includes a suppressing sudden change suppressing means a sudden change of the control torque when the tooth is determined, the lane departure prevention apparatus.