JP2002002518A - Vehicle steering assist device - Google Patents

Abstract

An object of the present invention is to provide a steering assist device for a vehicle capable of performing steering assistance satisfying more drivers in both the corrected steering area and the directional steering area. It is to be. An object of the present invention is to provide a steering assist device for a vehicle that assists a driver in steering operation, wherein a traveling region of the vehicle is a region where the steering operation is performed to correct a deviation of the traveling line of the vehicle in a lane. A travel steering area determining means for determining which of a correction steering area and a direction steering area to perform a steering operation to change the traveling direction of the vehicle in accordance with the turning of the travel lane; This is achieved by a steering assist device for a vehicle, comprising: steering assist control means for changing the degree of steering assist for a driver's steering operation according to the determination result of the means.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle steering assist system, and more particularly, to a vehicle steering assist system for assisting a driver to steer a vehicle in a lane.

[0002]

2. Description of the Related Art Conventionally, a vehicle steering system is provided in which a steering force is applied to a steering wheel operated by a driver so that the vehicle travels along a target line in a lane to assist the driver in steering. A support device has been proposed (JP-A-11-105728). In this vehicle steering assist device, a steering torque for causing a traveling line, into which the vehicle is guided by a driver's steering operation, to approach one target line selected from a plurality of preset target lines in the lane is generated. I have. This steering torque assists the driver's operation of the steering wheel, and assists the driver in steering.

According to such a vehicle steering assist system,
The driver's intention is relatively reflected on the vehicle traveling along the line, and steering assist for the driver that prevents the vehicle from deviating from the lane can be performed.

[0004]

When a driver steers a vehicle, it is necessary to drive the vehicle along a desired line on a road having a large curve radius R (a gentle curve) such as a straight road. The driver does not need to largely operate the steering wheel, but only needs to operate the steering wheel to such an extent that the traveling line of the vehicle does not greatly deviate from the desired line. On the other hand, on a road with a small curve radius R (a sharp curve), in order for the vehicle to travel along a desired line, the driver operates the steering wheel largely to change the traveling direction of the vehicle according to the curve of the road. Must be changed to For example, when the vehicle travels on an S-shaped curve, as shown in FIG. 1, the fluctuation of the steering angle in the S-shaped curve is much larger than the fluctuation of the steering angle before and after the S-shaped curve.

[0005] Here, an area in which a steering operation is mainly performed to correct the deviation of the vehicle's travel line in the lane is called a corrected steering area. In addition, an area in which a steering operation is performed to positively change the traveling direction of the vehicle according to a turn of the road is referred to as a direction steering area.

In a corrected steering area such as a road having a large curve radius R, the manner of operating the steering wheel does not greatly differ depending on the driver. Further, in this region, as long as the vehicle is traveling substantially in the center of the lane, the traveling line of the vehicle with a large steering angle is generally rarely changed. That is, it is difficult for the driver's preference to be reflected in the operation of the steering wheel.

On the other hand, in a direction steering area such as a road having a small curve radius R, the driver's preference of the traveling line such as whether he wants to drive in the center of the lane or so-called out-of-in-out. Thus, the manner of operating the steering wheel can be greatly changed.

In such a situation, irrespective of the correction steering area and the direction steering area, a plurality of target lines are fixedly set so that the traveling line of the vehicle approaches the one of the target lines. In a conventional steering assist device that performs steering assist to give a steering torque by the assist characteristic, some drivers may interfere with their steering operation and steering assist and feel that the steering assist is troublesome, or conversely, In some cases, steering support may be insufficient.

[0009] For example, in a steering assist device that provides a steering assist that applies a relatively large steering torque so that a traveling line of a vehicle approaches a target line with certainty, when the vehicle travels in a modified steering area, the steering assist system is often used. The driver does not have any particular dissatisfaction if the target line on which the vehicle is about to travel is approximately in the center of the lane, and the operation of the steering wheel by the driver is assisted by the steering torque given above, and the driver is driven. The driver can perform the steering operation with a relatively small load. However, when the vehicle travels in the direction steering area, some drivers may be dissatisfied with the target line on which the vehicle is to travel, and the driver operates the steering wheel according to his / her preference. In this case, the driver interferes with the relatively large steering torque to which the operation is applied, and the driver may feel the steering support troublesome.

On the other hand, in a steering assist device in which the degree of steering assist (depending on the magnitude of the steering torque and the width of the permissible range of the target line) is relatively small, when the vehicle travels in the direction steering area, Even if the driver operates the steering wheel according to the driver's preference, the driver does not have a great sense of hindrance to the operation of the steering wheel due to the steering assist, and provides a relatively satisfactory steering assist to the driver. It is possible to do. However, when the vehicle travels in the correction steering region, the driver may feel that the steering support is insufficient because the degree of the steering support is relatively small.

[0011] Further, some drivers may want to reliably support the steering operation in a direction steering region in which the steering wheel must be largely operated. In the steering assist device in which the degree of the steering assist is relatively small, when the vehicle travels in the direction steering region, the steering assist has a feeling of shortage.

As described above, the conventional steering assist device is
In both the modified steering region and the directional steering region in which the manner of operating the steering wheel is basically different, it is not possible to provide steering support that is satisfactory to more drivers.

[0013] Therefore, an object of the present invention is to focus on differences in driver's preference characteristics and driving loads due to the difference between the steering regions, that is, the directional steering region and the corrected steering region. It is an object of the present invention to provide a steering assist device for a vehicle capable of performing steering assist satisfying a driver.

[0014]

According to a first aspect of the present invention, there is provided a steering assist system for a vehicle for assisting a driver in performing a steering operation. A corrected steering area, which is an area where a steering operation is performed to correct the deviation of the vehicle's traveling line in the lane, and an area where the steering operation is performed to change the traveling direction of the vehicle according to the turning lane. A driving area determining means for determining which one of the directional steering areas is provided, and steering assist control means for changing a degree of steering support for a driver's steering operation according to a result of the determination by the driving area determining means. It is composed of

In the correction steering region, the amount of the steering operation by the driver and its fluctuation are generally small. In the direction steering region, the amount of steering operation by the driver and its fluctuation are generally large. In the vehicle steering assist device as described above, the degree of the steering assist is changed between the corrected steering region and the directional steering region in which the behavior of the driver's steering operation is basically different as described above. Steering support for the driver's steering operation can be performed with a degree of steering support corresponding to the behavior of the driver's steering operation.

The degree of the steering assist means the strength of restraining the running position of the vehicle so that the vehicle does not deviate from the lane. For example, the magnitude of the steering torque given to bring the traveling line of the vehicle closer to the target line indicates the degree of steering support, and the greater the steering torque, the greater the degree of steering support. Also, the allowable range of the target line to which the traveling line of the vehicle should be close indicates the degree of steering support,
The wider the allowable range is, the smaller the strength of restraining the running position of the vehicle is, and the smaller the degree of steering support is.

Since the behavior of the driver's steering operation changes according to the shape of the road on which the vehicle travels, the present invention provides a steering assist system for a vehicle according to the present invention. The area determination means has road shape acquisition means for acquiring information representing the road shape of the road on which the vehicle travels, and based on the information representing the road shape of the road on which the vehicle travels acquired by the road shape acquisition means. Thus, it can be configured to determine whether the traveling area of the vehicle is the correction steering area or the direction steering area.

The road shape acquiring means represents the road shape supplied from outside the vehicle even if the information representing the road shape of the road on which the vehicle travels is autonomously acquired by a device mounted in the vehicle. Information may be obtained.

The road shape obtaining means for obtaining information representing the road shape which influences the behavior of the driver's steering operation may be, specifically, a curve radius of a road on which the vehicle travels. Can be obtained as information representing the road shape.

Further, as set forth in claim 4, the road shape obtaining means can be configured to obtain a change rate of a curve radius of a road on which a vehicle travels as information representing the road shape. .

From the viewpoint of providing a specific method of changing the degree of the steering support, the present invention provides, in a steering support apparatus for each vehicle, the steering support control means, The degree of the steering assist can be changed by switching the magnitude of the steering torque for bringing the traveling line of the vehicle closer to the target line.

Further, from a similar viewpoint, the present invention provides the steering assist device for each vehicle, wherein the steering assist control means applies a steering torque to bring the traveling line of the vehicle closer to the target line. The degree of the steering assist can be changed by changing the allowable range.

The present invention is described in claim 7 from the viewpoint of enabling the steering operation to meet the driver's desire as much as possible in a direction steering region in which the amount of steering operation by the driver or its change is large. As described above, in the steering support device for each vehicle, the steering support control unit includes:
The degree of steering support when the traveling area of the vehicle is the directional steering area is configured to be smaller than the degree of steering assistance when the traveling area of the vehicle is the corrected steering area.

In such a vehicle steering assist system, the degree of the steering assist in the directional steering region is smaller than the extent of the steering assist in the corrected steering region, so that the vehicle travels in the directional steering region so as not to deviate from the lane. The strength of restraining the position is smaller than that in the correction steering area. Since such restraint is reduced, the driver can perform a steering operation according to his / her wish in a directional steering region where the amount of steering operation and its fluctuation are relatively large.

As described above, in the direction steering region where the amount of steering operation and its variation are relatively large, even if the degree of steering support is reduced, the steering operation can be performed in consideration of factors such as road shape and road surface condition. In some cases, it is preferable to increase the degree of steering support in terms of ease of operation. In consideration of such a case, according to the present invention, in the vehicle steering assist device, the degree of the steering assist is increased when the traveling region of the vehicle is the directional steering region. A support amount increasing area determining means for determining whether or not the vehicle should be in an area to be determined, wherein the assist amount increasing area determining means determines that the traveling area of the vehicle is an area in the directional steering area in which the degree of steering assistance should be increased. When performed, the steering assist control means may be configured to increase the degree of steering assist in the direction steering region.

According to a ninth aspect of the present invention, in the vehicle steering assist device, the assist amount increasing area determining means includes: According to a ninth aspect of the present invention, it can be configured to determine whether or not the region is to increase the degree of the steering support based on a curve radius of a road on which the vehicle travels.

According to another aspect of the present invention, from the same viewpoint, in the vehicle steering assist device, the assist amount increasing area determining means may determine a curve radius of a road on which the vehicle travels. It can be configured to determine whether or not the region is to increase the degree of the steering support based on the change rate.

From the viewpoint of considering the ease of steering operation based on the road surface condition, the present invention provides a vehicle steering assist device as set forth in claim 11, wherein the road surface condition of the road on which the vehicle runs is provided. Road surface state obtaining means for obtaining a road surface state for detecting the distance, and the support amount increasing area determining means should increase the degree of the steering support based on the road surface state of the road obtained by the road surface state obtaining means. It can be configured to determine whether or not it is an area.

The road surface condition of the road affects the ease of steering operation, and can be represented by, for example, the unevenness of the road surface, the material of the road surface, the slip ratio of the road surface, and the like.

When the degree of the steering assist changes as described above, particularly when the degree of the steering assist is reduced, the driver who performs the steering operation feels strange. From the viewpoint of reducing such discomfort, the present invention is directed to claim 1.
As described in 2, in the steering assist device for each vehicle, when the steering assist control means reduces the degree of the steering assist, the steering assist for assisting the driver in responding to the reduction in the degree of the steering assist. It is configured to have a transition support means.

In such a vehicle steering assist system, a driver who performs a steering operation when the degree of steering assist is reduced is supported. With this support, the driver can feel less discomfort when reducing the degree of the steering support.

In view of the fact that the feeling of discomfort can be reduced by adapting the driver's operational feeling to the reduced degree of steering support when the degree of steering support is reduced, the present invention relates to claim 13. As described, in the steering assist device for a vehicle, the steering assist transition assisting means includes means for gradually reducing the degree of steering assist from the degree of steering assist before reduction to the degree of steering assistance after reduction. It can be configured as follows.

Further, from the viewpoint that the driver is prepared for the reduction in the degree of steering assistance, the feeling of discomfort can be reduced. In the steering assist device of
The steering assist shift assisting means may be configured to include an informing means for informing the driver of the fact that the degree of the steering assist is reduced before the degree is reduced.

In particular, when the driver can perform the steering operation in a state where the degree of the steering assist is relatively large, the present invention can be used to assist the driver in responding to the reduction of the degree of the steering assist as described above. As described in claim 15, in the steering assist device for each vehicle, a period measuring means for measuring a period during which the steering assist for the driver's steering operation is performed with the degree of the steering assist before reduction. Determining means for determining whether or not the period obtained by the period measuring means has reached a predetermined period; and determining that the period obtained by the period measuring means has reached the predetermined period. And control means for enabling the steering support transition support means when the determination is made.

The above-mentioned predetermined period is set to a period during which the driver can be considered to be used to the steering operation in a state where the degree of the steering assist is relatively large. Since the predetermined period only needs to reflect the degree of familiarity of the driver with the steering assist, the specific period can be set using the travel distance and the travel time. In addition, when setting using a time, it is preferable to set according to the driving time except the stop.

According to another aspect of the present invention, there is provided a steering assist system for a vehicle for assisting a driver to perform a steering operation. Road shape obtaining means for obtaining a change rate, steering assist control means for reducing the degree of steering support for the driver's steering operation as the change rate of the curve radius of the road obtained by the road shape obtaining means increases, It is comprised so that it may have.

As the rate of change of the curve radius of the road increases, the fluctuation of the steering operation by the driver increases. In such a region where the fluctuation of the steering operation is large, the behavior of the steering operation can be largely changed by the driver. By reducing the degree of the steering assist as the rate of change of the curve radius of the road increases, the restraint by the steering assist becomes smaller even if various drivers perform a steering operation as desired.

The steering support control means may reduce the degree of the steering support stepwise or may continuously change the degree of the steering support.

[0039]

Embodiments of the present invention will be described below with reference to the drawings.

A vehicle steering assist system according to one embodiment of the present invention is configured, for example, as shown in FIG.

In FIG. 2, a steering angle sensor 26 for detecting a steering angle θ with respect to a rotation axis of a steering handle 20 operated by a driver is provided, and an automatic steering unit is provided. The automatic steering unit includes a gear mechanism 25 provided for the rotation axis of the steering handle 20 and a drive motor (actuator) 3 that drives the gear mechanism to apply a steering torque to the rotation axis.
It has 0.

The steering assist device includes a camera 11 for projecting a road ahead of the vehicle, and an image processing unit 12 for extracting a white line as a boundary of a lane based on image information from the camera 11.
And a control unit (ECU) 10. The control unit 10 detects the position of the vehicle in the lane width direction (traveling line position) in the traveling lane based on the shape difference between the white lines on both sides of the traveling lane extracted by the image processing unit 2 and extracts the position. The shape of the lane in which the vehicle travels is recognized based on the shape of the white line thus determined, and based on the recognition result, it is determined whether the area in which the vehicle travels is the correction steering area or the direction steering area.

The control unit 10 holds a preset steering assist pattern for each of the above-described modified steering area and direction steering area. This steering assist pattern can be represented in the form of a ball-in-track, for example, as shown in FIG. In this format, the V-shaped line represents the characteristics of the steering torque, and V
The vertex of the character corresponds to the target line. The steeper the V-shaped gradient, the more the vehicle seen on the ball moves to the target line (V
(The top of the character).

The control unit 10, to generate thereby calculating the target steering angle theta _T to match the traveling line of the vehicle to the target line according to the steering assist pattern corresponding to the corrective steering area or direction steering region of the determination result Determine the required steering torque. Then, the control unit 10 outputs a control signal to the drive motor 30 as the steering torque determined above occurs until theta detected steering angle from the steering angle sensor 26 coincides with the target steering angle theta _T. Since the steering torque can be controlled by the current value supplied to the drive motor 30, the control signal controls the current value supplied to the drive motor 30.

The control unit 10 receives a wheel speed pulse based on the wheel rotation from the wheel speed sensor 13 and calculates a friction coefficient μ of the road surface based on a change in the wheel speed pulse during braking. . Then, as will be described later, the slip ratio μ can be considered when determining the steering assist pattern.

As shown in FIG. 2, information on the road shape at the position where the vehicle is detected by the GPS 14 is supplied from the map database 15 to the control unit 10, and the control unit 10 It is also possible to determine whether the region is the correction steering region or the direction steering region based on the correction steering region. Further, information about the shape of the road and information such as the start point and end point of the direction steering area are received by the road-to-vehicle communication device 16 from the communication facility installed on the road, and the control unit 10 corrects the steering area based on the information. It is also possible to determine whether it is in the direction steering area.

The control unit 10 controls the steering support according to the procedure shown in FIG. 4, for example.

In FIG. 4, the control unit 10 acquires a parameter for determining a steering area (corrected steering area or directional steering area) (S1). As parameters for determining the steering area, the operating state of the steering handle 20 of the driver, the presence or absence of operation of a switch provided on the steering handle 20, etc., information indicating the lane (road) shape, the start point of each area, the end Information or the like representing a point can be used. For example, the lane shape recognized based on the shape of the white line extracted by the image processing unit 12 is acquired as a parameter for determining the steering area.

Next, based on the obtained parameters, it is determined whether the area in which the vehicle travels is either the correction steering area or the direction operation area (S2). When it is determined that the traveling area is the corrected steering area while the vehicle is traveling on a road having a relatively large curve R, the steering assist pattern B is selected and set (S4). The steering assist pattern B is a pattern in which the degree of steering assist is relatively large. For example, as shown in FIG. 5C, the steering assist pattern B is represented in the form of a ball-in-track in which the V-shaped gradient is relatively steep. Steering assist pattern.

On the other hand, when it is determined that the traveling area is the direction steering area while the vehicle is traveling on a road with a small curve radius R, it is further determined whether or not the area is the support amount increasing area. (S3). This support amount increase area will be described later. Here, if it is determined that the traveling area is not the support amount increase area (NO in S3), the steering support pattern A1
Is selected and set (S5). This steering assist pattern A
1 is a pattern in which the degree of steering assistance is relatively small,
For example, as shown in FIG. 5A, a steering assist pattern represented by a ball-in-track pattern having a flat central portion and a relatively small depth is obtained. The steering assist pattern shown in FIG. 5A allows the operation of the steering handle 20 to be performed without giving a steering torque within a predetermined width in the lane, and when the vehicle is located near the boundary of the lane, The steering torque is applied so as to prevent deviation from the steering wheel. In this case, the flat part of the steering assist pattern can be regarded as the allowable range of the target line.

Further, when it is determined that the traveling area of the vehicle is the direction steering area and the support increasing area (Y in S3).
ES), the steering support pattern A2 is selected and set (S)
6). As described above, in the direction steering region, a steering assist pattern (see FIG. 5A) is selected in which the degree of steering assist is relatively small while respecting the operation of the steering wheel 20 by the driver. Depending on the road surface condition, it may be difficult to operate the steering wheel, and it may be preferable to increase the degree of steering support. As described above, an area where the degree of steering assist is relatively small, but it is preferable to increase the degree of steering assist, is referred to as an assist increasing area. Accordingly, the determination of the support increase area is based on the road shape (curve R, change rate of curve R, friction coefficient μ of road surface).
And so on.

For example, as shown in FIG. 5B, the steering assist pattern A2 selected in the increased assist area has a V-shape in which the flat portion shown in FIG. 5A is slightly inclined. The steering assist pattern is expressed in the form of a ball-in-track.

As a result of the above processing, when the vehicle travels in the direction steering area where the curve radius R is relatively small, the steering assist pattern A1 having a small degree of steering assist (see FIG. 5).
(A), the steering assist pattern B (see FIG. 5 (c)) having a large degree of steering assistance further increases the direction steering area when the vehicle travels in the modified steering area having a relatively large curve radius R. Even when the vehicle travels in the support increase area, the steering support pattern A2 (see FIG. 5B) is smaller than the degree of the steering support of the steering support pattern B but is larger than the degree of the steering support of the steering support pattern A1. ) Is selected and set.

When the steering assist pattern is selected and set according to the corrected steering area and the direction steering area as described above, the vehicle travels along the target line based on the selection and the set steering assist pattern. steering angle theta _T is computed required to (S7). In the steering assist pattern shown in FIG. 5A, the target line has a predetermined width (FIG. 5A).
(Corresponding to the flat part of (a)), and as long as the vehicle exists in the width, the necessary steering angle θ _T is zero (θ _T = 0).
Is set to

Then, it is determined whether or not the detected steering angle θ from the steering angle sensor 26 becomes the required steering angle θ _T calculated as described above (θ = θ _T ) (S8). Detected when the steering angle theta is not the steering angle theta _T required, the indicated value of the steering torque to be added based on the steering assist pattern selected as described above, specifically, the drive motor 3
Is calculated (S9). And
The drive motor 30 is controlled based on the calculated torque instruction value (current value) (S10).

Hereinafter, the above-described processing is sequentially repeated. As a result, the steering torque according to the steering assist pattern selected based on the determination result of the traveling area as described above is given to the steering handle 20, and the driver receives the steering torque of the steering handle 20 while receiving the assist of the steering torque. Operation will be performed.

As described above, the degree of the steering assist is small in the direction steering region where the manner of the steering operation can be variously varied depending on the driver (see FIG. 5A). Even if the corresponding steering operation is performed, there is no great sense of hindrance to the steering operation due to the steering support, and the steering support is less likely to be bothersome. On the other hand, the degree of steering assist is large in the modified steering region where the driver's preference and driving skill are hardly reflected in the manner of steering operation (FIG. 5).
(Refer to (b)), the driver can perform the steering operation while receiving the steering support without feeling a shortage of the steering support or a hindrance to the steering operation.

Further, even in the direction steering area, particularly in the assist amount increasing area, the degree of the steering assist is increased (see FIG. 5B). Even in this case, it is possible to provide a more reliable steering operation.

The steering assist pattern determined according to the running area of the vehicle is not limited to the above example. For example, a steering assist pattern A1 as shown in FIG. 5D in the direction steering area and a steering assist pattern A2 as shown in FIG. 5E in the further assist amount increasing area of the direction steering area are further modified. FIG. 5 in the steering area
The steering assist patterns B as shown in (f) may be respectively selected and set. In this case, the steering torque for bringing the traveling line of the vehicle closer to the target line in the order of the steering assist patterns A1, A2, and B becomes large (V
The steepness of the character).

For example, in the direction steering area, FIG.
The steering assist pattern A1 as shown in FIG. 5 (g) has a steering assist pattern A2 as shown in FIG. 5 (h) in the further assist amount increasing region of the direction steering region, and the steering assist pattern A2 as shown in FIG. The steering support pattern B as shown in
Each can be selected and set.
In this case, in the direction steering region other than the support amount increasing region, substantial steering support is not performed, and the operation is left to the driver's steering operation.

In the above-described process (see FIG. 4), the processes of obtaining the steering region determination parameter (S1), determining the steering region (S2), and determining the support amount increasing region (S3) are specifically described below. For example, it can be performed according to the procedure shown in FIG.

In FIG. 6, the control unit 10 fetches image data corresponding to a white line serving as a boundary of a traveling lane from the image processing unit 12 (S11), and recognizes the shape of the white line (lane shape) from the image data (S11). S12). Then, the change rate (dR / dL) of the curve radius R of the lane ahead of the vehicle is detected based on the recognized shape of the white line (S13). The rate of change of the curve radius R of this lane (dR
/ DL) is obtained as a steering area determination parameter (S1 in FIG. 4).

When the rate of change (dR / dL) of the curve radius R of the lane on which the vehicle is traveling is obtained in this manner, the rate of change (dR / dL) of the curve radius R is set to the first threshold (dR / dL).
dL) It is determined whether it is smaller than _TH1 (S2)
1). This determination result is a determination result of whether the region is the correction steering region or the direction steering region (S2 in FIG. 4). The rate of change (dR / dL) of the curve radius R is equal to a first threshold (dR / d
L) If it is smaller than _TH1 (YES in S21), it is determined that the steering is in the corrected steering region where the fluctuation of the steering operation is small. In this case, the steering support pattern B is selected and set (S4 in FIG. 4).

On the other hand, the rate of change of the curve radius R (dR /
dL) is the first threshold (dR / dL) _TH1When it is over
(NO in S21), fluctuation of steering operation is relatively large
It is determined that the vehicle is in the threshold steering region. In this case,
In addition, the rate of change of the curve radius R (dR / dL) is
One threshold (dR / dL)_TH1Greater second threshold
(DR / dL)_TH2Determined if greater than
(S31). The result of this determination is the support in the direction steering area.
The result of the determination as to whether or not the area is an increase in the amount of assistance is shown in FIG.
S3).

Change rate of the curve radius R (dR / dL)
Is smaller than a second threshold (dR / dL) _TH2 (S
31 (NO at 31), the steering assist pattern A1 is selected and set, assuming that the steering operation variation is not extremely large but is a relatively large directional steering area (S5 in FIG. 4). On the other hand, if the change rate (dR / dL) of the curve radius R is equal to or more than the second threshold value (dR / dL) _TH2 (YES in S31), the support amount increase region where the fluctuation of the steering operation becomes extremely large. Is determined. In this case, selection and setting of the steering assist pattern A2 are performed (S6 in FIG. 4).

As described above, the corrected steering area and the directional steering area, which are characterized based on the operating state of the steering wheel 20 of the driver, are the rate of change (dR / dL) of the curve radius of the lane in which the vehicle travels. Can be determined based on Further, in the direction steering region, particularly, in the assist amount increasing region in which it is preferable to increase the degree of the steering assist, the determination can be made based on the change rate (dR / dL) of the curve radius.

The basis for determining the corrected steering area and the direction steering area
Reference first threshold (dR / dL) _TH1And direction steering
Is a criterion for judging whether or not the region is the support amount increase region in the
Threshold (dR / dL)_TH2Is, for example, a curved road, straight
More driver steer as the vehicle travels along the path
It can be determined in consideration of the manner of the switching operation.

When the determination of the steering area is performed based on the change rate (dR / dL) of the curve R of the traveling lane as described above, for example, for the road shown in FIG. The determination of the steering area is performed. In this case, an area in which the amount by which the steering wheel 20 is actually operated becomes large is determined as the direction steering area.

In the above-described example, the determination of the direction steering area and the correction steering area is made based on the rate of change (dR / dL) of the curve radius R. However, the determination can be made based on the curve radius R itself. . In this case, for example, the correction steering area and the direction steering area are determined for the road shown in FIG. That is, the steering handle 2
A region where the turning angle of 0 is large is determined as the direction steering region.

In the above-described processing (see FIG. 6), the rate of change (dR /
Although the determination as to whether or not the region is the support amount increase region is performed based on dL), the determination may be performed based on the magnitude of the curve radius R itself as described above. Further, the support amount increase region is a region in which it is considered that the driver has difficulty in driving, and from this viewpoint, the determination can be made based on another factor. For example, as described above, the friction coefficient μ of the road surface is determined based on the fluctuation of the wheel speed pulse from the wheel speed sensor 13 at the time of braking, and it is determined whether or not the vehicle is in the support amount increasing region based on the friction coefficient μ. Can also be performed.

The steering support described above (FIG. 4 or FIG. 6)
When the driver performs the steering operation while receiving the vehicle, the vehicle enters the directional steering area after traveling in the corrected steering area for a relatively long time, and the driver who has provided relatively high steering support may be unable to perform the steering operation. A sudden decrease in the degree of assistance may make the steering operation uncomfortable. In order to alleviate the driver's uncomfortable feeling of the steering operation due to such a decrease in the degree of the steering support, the control unit 10 can perform processing according to, for example, a procedure as shown in FIG.

In FIG. 8, similarly to the above-described example (see FIG. 4), a parameter (for example, a change rate of the curve R) for determining the steering area is obtained (S1), and the steering area is determined based on the parameter. A determination (S2) is made. As a result, when it is determined that the vehicle is in the correction steering region, it is further determined whether or not a predetermined flag is set to 1 (S211). If this flag has not been set to 1 (NO in S211), the flag is set to 1 (S212), and the timer T is started (S21).
3).

Then, it is determined whether or not the timer T has reached a predetermined time T _TH (S214). This timer T
_Has not yet reached the predetermined time T _TH (S21).
No. 4), similarly to the above-described example (see FIG. 4), the selection and setting of the steering assist pattern B assigned to the corrected steering area are performed (S4), and the steering assist processing according to the steering assist pattern B is performed. (S7 to S10 in FIG. 4) are executed. As a result, the driver receives a relatively high degree of steering support.

Thereafter, the flag is set to 1 (S21).
2) and the start processing of the timer T (S213) are skipped, and the above-described processing is repeatedly executed (S1, S2
2, S211, S214, S4 and S7 to S7 in FIG.
S10). In the process, when it is determined that the timer T has reached the predetermined time T _TH (YES in S214), the control unit 10 determines the remaining distance (or time) of the corrected steering area, that is, the distance to the direction steering area. (Or time) is less than or equal to a predetermined value. This determination can be made, for example, based on the shape of the white line ahead of the vehicle recognized based on the image data from the image processing unit 12, or based on the map information and the current position of the vehicle.

If the remaining distance (or time) of the corrected steering area is not less than the predetermined value, this determination (S2
While performing 15), the above-described processing is repeatedly executed. In this process, when it is determined that the remaining distance (or time) of the correction steering area has become equal to or less than a predetermined value (S21).
Then, the driver is alerted (S21).
6), a steering assist pattern in which the torque gradient of the assist pattern B (the V-shaped gradient in the steering assist patterns (c), (f), and (i) in FIG. 5) is reduced by a predetermined value is set (S217).

Thereafter, until it is determined that the vehicle has entered the directional steering area, the above-described processing is repeatedly performed while performing the warning (S216) and the processing for reducing the torque gradient of the steering assist pattern (S217). In the warning, for example, a pulse-like drive current is supplied to the drive motor 30 so that a slight torque is intermittently applied to the steering handle 20 in the curve direction of the vehicle. Alternatively, the driver may be notified of the steering direction by voice, display, or the like.

As shown in FIG. 9, the driver can prepare to enter the directional steering area by the above-mentioned alarm (☆) at a position a predetermined distance before the directional steering area and reduce the steering torque. By gradually reducing the operating feeling, the operating feeling of the steering handle 20 gradually approaches the operating feeling in the direction steering region.

In this state, when it is determined that the traveling area of the vehicle is the direction steering area (direction steering area in S2), it is determined whether the flag is zero (S2).
218). In this case, since the flag has already been set to 1 (NO in S218), the flag is reset to zero (S219), and the timer is reset (S220). Then, the above-described processing (see FIG. 4)
Similarly to the above, the determination result of whether or not it is the support amount increase area (Y in S3
ES or NO), a steering assist pattern A1 or A2 is set (S5 or S6), and further, a steering assist process according to the set steering assist pattern (FIG. 4)
S7 to S10) are performed. Thereafter, in a state in which the flag reset processing (S219) and the timer reset processing (S220) are skipped, the processing is executed according to the same procedure as described above, and the driver is assisted in steering in the direction steering area. .

As described above, before the vehicle shifts from the corrected steering area to the directional steering area, a warning is issued to the driver, or the steering assist pattern to be gradually performed in the directional steering area is provided. Therefore, even if the vehicle enters the directional steering area from the corrected steering area and the steering support pattern changes abruptly, the uncomfortable feeling of the operation of the steering wheel 20 by the driver can be minimized.

In the above example, the operation control pattern may not be changed stepwise (S217). In this case, at least the driver can prepare in advance to shift to the direction steering region in which the steering assist pattern is changed.

In the above example, the alarm (S216)
May not be performed. In this case, at least the driver's operation sensation of the steering wheel 20 gradually approaches the operation sensation in the direction steering region.

In the above-described example, the processing in S1 and S2 in FIG. 4 corresponds to the traveling area determination means, and the processing in S4 to S10 in FIG. 4 corresponds to the steering support control means. The processing in S11 to S13 in FIG. 6 corresponds to a road shape acquisition unit.

Further, S3 in FIG. 4 (S3 in FIG. 6)
The processing in 31) corresponds to the support amount increase area determining means, and the function of the control unit 10 for calculating the road surface slip ratio based on the fluctuation of the wheel speed pulse from the wheel speed sensor 13 corresponds to the road surface state obtaining means.

Further, the processing in S216 and S217 in FIG. 8 corresponds to the steering support transition support means.
Corresponds to the notifying means, and the processing in S217 corresponds to means for gradually reducing the degree of the steering support. Further, the timer T shown in FIG. 8 corresponds to the time measuring means, the processing in S214 corresponds to the determining means, and the path of YES in S214 corresponds to the control means.

[0085]

As described above, according to the present invention as set forth in claims 1 to 15, the behavior (characteristics) of the driver's steering operation is basically different between the modified steering area and the directional steering area. Because the degree of steering support can be changed,
The steering assist for the driver's steering operation can be performed with the degree of the steering support corresponding to the behavior (characteristic) of the driver's steering operation in each region.
As a result, it is possible to perform steering support that satisfies more drivers in both the correction steering area and the direction steering area.

Further, according to the present invention, there is provided a steering assist device for a vehicle.
The degree of steering assist becomes smaller in an area where the change rate of the curve radius of the road is large and the behavior of the steering operation can be largely changed by the driver, and the steering assist can be performed even if various drivers perform the steering operation as desired. Is smaller. As a result, a steering assist that satisfies more drivers in both the corrected steering area where the rate of change of the curve radius of the road is relatively small and the directional steering area where the rate of change of the curve radius of the road is relatively large. Can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an example of a change characteristic of a steering angle when a vehicle passes an S-shaped curve.

FIG. 2 is a diagram illustrating a configuration example of a steering assist device according to an embodiment of the present invention.

FIG. 3 is a diagram illustrating an example in which a steering assist pattern is represented in a ball-in-track format.

FIG. 4 is a flowchart illustrating an example of a processing procedure related to steering assistance.

FIG. 5 is a diagram showing an example of a steering assist pattern.

FIG. 6 is a flowchart illustrating an example of a specific processing procedure of a steering area determination parameter acquisition processing, a steering area determination processing, and a support amount increase area determination processing in the steering support processing.

FIG. 7 is a diagram illustrating an example of a determination result of a correction steering area and a direction steering area.

FIG. 8 is a flowchart illustrating another example of a processing procedure related to steering assistance.

9 is a diagram for explaining a stepwise change of a steering assist pattern and a warning performed by the processing according to the processing procedure shown in FIG. 8;

[Explanation of symbols]

 Reference Signs List 10 control unit (ECU) 11 camera 12 image processing unit 13 wheel speed sensor 14 GPS 15 map database 16 road-vehicle communication device 20 steering handle 25 gear mechanism 26 steering angle sensor 30 drive motor

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) B62D 113: 00 B62D 113: 00 137: 00 137: 00

Claims (16)

[Claims] 1. A steering assist system for a vehicle, which assists a driver in steering operation, in which a traveling region of the vehicle is a region in which a steering operation is performed to correct a deviation of a traveling line of the vehicle in a lane. A travel region determining means for determining which of a region and a direction steering region is a region in which a steering operation is performed to change the traveling direction of the vehicle in accordance with the turning of the traveling lane; A steering assist device for a vehicle, comprising: steering assist control means for changing a degree of steering assist for a driver's steering operation according to a result. 2. The steering assist system for a vehicle according to claim 1, wherein said traveling area determination means includes road shape acquisition means for acquiring information representing a road shape of a road on which the vehicle travels, and said road shape acquisition means. A vehicle steering assist device for determining whether the traveling region of the vehicle is the corrected steering region or the directional steering region based on the information representing the road shape of the road on which the vehicle travels obtained by the means. 3. The vehicle steering assist system according to claim 2, wherein the road shape acquiring means acquires a curve radius of a road on which the vehicle travels as information representing the road shape. . 4. The vehicle steering assist device according to claim 2, wherein the road shape obtaining means obtains a rate of change of a curve radius of a road on which the vehicle travels as information representing the road shape. Steering support device. 5. A steering assist system for a vehicle according to claim 1, wherein said steering assist control means switches a magnitude of a steering torque for bringing a traveling line of the vehicle closer to a target line. A vehicle steering assist device that changes the degree of steering. 6. The steering assist system for a vehicle according to claim 1, wherein the steering assist control means is configured to allow the steering line to approach a target line by applying a steering torque. A steering assist device for a vehicle in which the degree of steering assist is changed by changing the steering angle. 7. The steering assist system for a vehicle according to claim 1, wherein the steering assist control means determines a degree of the steering assist when the traveling region of the vehicle is a directional steering region. A steering assist device for a vehicle, wherein the degree of steering assist in the case of a correction steering area is made smaller than the degree of steering assist. 8. A steering assist system for a vehicle according to claim 7, wherein when the traveling area of the vehicle is a direction steering area, an increase in the amount of assistance for determining whether or not the degree of steering assistance is to be increased. When the assist amount increasing area determining means determines that the traveling area of the vehicle is an area in the directional steering area in which the degree of steering assistance should be increased, the steering assist control means includes: A vehicle steering assist device configured to increase the degree of steering assist in a region. 9. The steering assist system for a vehicle according to claim 8, wherein the assist amount increasing area determining means is an area for increasing the degree of steering assist based on a curve radius of a road on which the vehicle travels. A steering assist device for a vehicle, which determines whether or not the vehicle is steered. 10. The steering assist device for a vehicle according to claim 8, wherein the assist amount increasing area determining means determines an amount of the steering assist to be increased based on a change rate of a curve radius of a road on which the vehicle travels. A vehicle steering assist device that determines whether or not there is a vehicle. 11. A steering assist system for a vehicle according to claim 8, further comprising: a road surface condition acquisition unit for acquiring a road surface condition for detecting a road surface condition of a road on which the vehicle travels; A steering assist device for a vehicle, which is configured to determine whether or not it is an area where the degree of steering assist should be increased based on the road surface condition of the road acquired by the road condition acquiring means. 12. A steering assist system for a vehicle according to claim 1, wherein when the steering assist control means reduces the degree of the steering support, the driver assists the driver in responding to the reduction in the degree of the steering assist. A vehicle steering assist device having a steering assist transition assisting means. 13. A steering assist system for a vehicle according to claim 12, wherein said steering assist shift assisting means gradually reduces the degree of steering assist from the degree of steering assistance before reduction to the degree of steering assistance after reduction. A vehicle steering assist device having means. 14. A vehicle steering assist system according to claim 12, wherein said steering assist transition assisting means has a notifying means for notifying a driver of the fact that the degree of the steering assist is reduced before the degree of the steering assist is reduced. Steering assist device. 15. The vehicle steering assist device according to claim 12, wherein a period measuring means for performing a steering assist for a driver's steering operation at a degree of the steering assist before the reduction and measuring a traveling period. Determining means for determining whether the period obtained by the period measuring means has reached a predetermined period; and determining that the period obtained by the period measuring means has reached the predetermined period. And a control means for enabling the steering support transition support means when the determination is made. 16. A steering assist system for a vehicle for assisting a driver in steering operation, comprising: a road shape obtaining means for obtaining a change rate of a curve radius of a road on which the vehicle travels; A steering assist device for a vehicle, comprising: steering assist control means for reducing the degree of steering assist for a driver's steering operation as the rate of change of the curve radius increases.