JP6278202B2 - Lane maintenance control device - Google Patents

Description

  The present invention relates to a lane keeping control device, and more particularly, to a lane keeping control device for performing lane keeping control of a vehicle.

  Conventionally, a lane keeping control device for performing lane keeping control of a vehicle is known. For example, in Patent Document 1, a lateral relative position of a vehicle with respect to a travel reference line is detected, a target steering torque is calculated according to the relative position, and a steering angle is set on a steered wheel of the vehicle based on the target steering torque. An automatic steering device is disclosed. In this device, the curvature of the road on which the vehicle is traveling is estimated, the stabilization control torque for stabilizing the vehicle is calculated based on the reference travel line of the curvature, and the travel reference line and the actual travel line are calculated. Based on the deviation amount, a reference travel line following torque for causing the vehicle to follow the reference travel line is calculated, and the target steering torque is calculated by adding the stabilization control torque and the reference travel line following torque.

JP 2004-149060 A

  However, in the conventional apparatus as described above, since the stabilization control torque is calculated based on the curvature of the road estimated in advance before entering the curve, when the error between the estimated curvature and the actual curvature is large, In addition to road curvature, if there are factors that affect the driving position of the vehicle (for example, road banks), it is possible to calculate appropriate steering torque in real time during curve driving according to those conditions. As a result, there is a possibility that the vehicle cannot be stably traveled along the reference travel line.

  The present invention has been made to solve the above-described problems of the prior art, and provides a lane keeping control device capable of stably driving a vehicle along a target travel line under various situations. The purpose is to do.

In order to achieve the above object, the lane keeping control device of the present invention is a lane keeping control device for performing lane keeping control of a vehicle, wherein the traveling lane of the vehicle has a straight or curved shape. When the traveling lane shape detection means for detecting the vehicle and the traveling lane of the vehicle is a curve, the lane marking of the traveling lane of the vehicle is detected at a detection time interval during curved traveling, and when the traveling lane of the vehicle is a straight line, A lane line detecting means for detecting a lane line of a vehicle travel lane at a detection time interval during straight traveling longer than a detection time interval during curve traveling, and a target travel line of the vehicle based on the lane marking of the vehicle travel lane Target travel line setting means for setting the vehicle, deviation amount detection means for detecting a deviation amount between the target travel line and the current position of the vehicle, and a target for causing the vehicle to travel along the target travel line based on the deviation amount Determine the rudder angle Predetermined and Shimegikaji angle determination means, and a self aligning torque estimating means for estimating a self-aligning torque generated in the front tire of the vehicle when achieving the target steering angle, the relationship between the target steering angle and the basic target torque The basic target torque corresponding to the target rudder angle determined by the target rudder angle determining unit is determined with reference to the map, and the sum of the basic target torque and the self-aligning torque estimated by the self-aligning torque estimating unit is determined. , possess a target torque determining means for determining a target torque applied to the steering of the vehicle, a self-aligning torque estimating means estimates a slip angle of the front tires of the vehicle in the case of achieving the target steering angle, the vehicle the product of a predetermined coefficient and slip angle on the basis of the tire characteristic, to estimate the self aligning torque And features.
In the present invention configured as described above, the self-aligning torque estimating means is generated in the vehicle tire when the target rudder angle determined based on the deviation amount between the target travel line and the current position of the vehicle is achieved. Since the self-aligning torque is estimated and the target torque determining means determines the target torque to be applied to the steering of the vehicle based on the target rudder angle and the self-aligning torque, the vehicle is caused to travel along the target travel line. The target torque required for the vehicle can be accurately determined in real time by taking into account the self-aligning torque that changes from moment to moment depending on the vehicle running conditions (for example, vehicle speed and curvature of the road on which the vehicle is running). Thus, the vehicle can travel along the target travel line stably under various conditions. In addition, since the lane marking of the traveling lane of the vehicle is detected at a time interval according to the shape of the traveling lane, the lane marking of the traveling lane is detected at an appropriate time interval according to the shape of the traveling lane, and the detection result Accordingly, it is possible to control the torque applied to the steering of the vehicle, thereby achieving both improved drive feeling and a sense of security.

In the present invention, it is preferable that self-aligning torque correcting means for correcting the self-aligning torque estimated by the self-aligning torque estimating means based on the vehicle speed is further provided.
In the present invention configured as described above, the self-aligning torque correcting means corrects the estimated self-aligning torque based on the vehicle speed, so that the self-aligning torque can be estimated more accurately. By determining a more appropriate target torque, the vehicle can travel along the target travel line stably under various conditions.

In the present invention, it is preferable that the self-aligning torque correction unit increases the correction amount of the self-aligning torque as the vehicle speed increases.
In the present invention configured as described above, the self-aligning torque that increases as the vehicle speed increases can be estimated more accurately, thereby determining a more appropriate target torque and under various circumstances. The vehicle can travel stably along the target travel line.

Further, in the present invention, preferably, when the deviation amount increases, there is further provided target torque correction means for correcting the target torque determined by the target torque determination means in accordance with the increasing speed of the deviation amount.
In the present invention configured as described above, even when the deviation amount between the target travel line and the current position of the vehicle is increased due to the influence of the bank of the road, the crosswind, etc., the influence is appropriately corrected so as to offset the influence. The target torque can be determined, and thereby the vehicle can travel along the target travel line stably under various conditions.

  According to the lane keeping control device according to the present invention, the vehicle can be stably driven along the target travel line under various situations.

1 is a diagram illustrating a schematic configuration of a vehicle including a lane keeping control device according to an embodiment of the present invention. It is a block diagram which shows the system configuration | structure of the lane keeping control apparatus by embodiment of this invention. It is a flowchart which shows the control content of the lane keeping control apparatus by embodiment of this invention. It is a schematic plan view which shows the vehicle which drive | works a lane used as the object of lane maintenance control.

Hereinafter, a lane keeping control method and a lane keeping control device according to an embodiment of the present invention will be described with reference to the accompanying drawings.
First, the configuration of the lane keeping control device according to the embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a diagram showing a schematic configuration of a vehicle including a lane keeping control device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a system configuration of the lane keeping control device according to the embodiment of the present invention. .

First, as shown in FIG. 1, a lane keeping control device 1 according to an embodiment of the present invention includes an electric power steering mechanism / torque actuator 6 that applies steering assist force to a steering wheel 2 and a steering shaft 4, and the electric power steering. A steering torque controller 8 for giving an instruction of the magnitude of the assist force to the mechanism 6; A rack and pinion type steering gear device 10 is connected to the steering shaft 4 and the left and right steering wheels 12 are steered.
In this embodiment, the steering torque controller 8 provides a predetermined target torque signal to the torque actuator 6 (provides a torque instruction) so that a target torque described later is applied to the steering wheel 2 and the steering shaft 4. ing.

  Next, as shown in FIG. 2, the lane keeping control device 1 according to the embodiment of the present invention includes a vehicle speed sensor 14 for detecting the vehicle speed of the vehicle, a yaw rate sensor 16 for detecting the yaw rate of the vehicle, and the steering wheel 2. A steering angle sensor 18 for detecting the steering angle (see FIG. 1) and a road marking line detection sensor 20 are included. The road lane marking detection sensor 20 includes a camera (not shown) that images the road surface ahead of the vehicle, and detects the lane markings (see LL and LR shown in FIG. 4) of the traveling lane from the captured road image.

  Further, the lane keeping control device 1 has an arithmetic unit 22 provided in the steering torque controller 8, and signals from each sensor are inputted. The arithmetic unit 22 calculates a target torque signal to be given to the electric power steering 6 based on signals from each sensor.

Next, the control content of the lane keeping control device 1 according to the embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing the control contents of the lane keeping control device 1 according to the embodiment of the present invention, and FIG. 4 is a schematic plan view showing a vehicle traveling in the lane targeted for lane keeping control.
First, the control shown in FIG. 3 is executed when an ignition switch (not shown) of the vehicle is turned on and a lane keeping control switch (not shown) is turned on. As shown in FIG. 3, when the lane keeping control is started, in step S1, the arithmetic unit 22 of the lane keeping control device 1 reads the signal output from each sensor.

  Next, in step S2, the arithmetic unit 22 detects whether the travel lane of the vehicle is a straight line or a curved line. Specifically, the arithmetic unit 22 determines that the traveling lane of the vehicle is a curve when the yaw rate detected by the yaw rate sensor 16 is equal to or greater than a predetermined threshold, and when the yaw rate is less than the threshold, It is determined that the traveling lane is a straight line.

As a result, when the travel lane of the vehicle is a curve, the process proceeds to step S3, and the calculation unit 22 sets the time interval for detecting the lane marking of the travel lane of the vehicle by the road lane marking detection sensor as the detection time interval during curve travel. Set to T1.
On the other hand, when the travel lane of the vehicle is not a curve (a straight line), the process proceeds to step S4, and the arithmetic unit 22 sets the time interval for detecting the lane marking of the travel lane of the vehicle by the road lane marking detection sensor. Is set to the detection time interval T2. Here, T2> T1.

  After step S3 or S4, the operation unit 22 proceeds to step S5, where the arithmetic unit 22 determines the travel lane division of the vehicle detected by the road lane line detection sensor at the detection time interval T1 during curve traveling or the detection time interval T2 during linear travel. Based on the line, the target travel line of the vehicle is set. For example, as shown in FIG. 4, the arithmetic unit 22 uses a line connecting the middle point of the left lane line LL and the right lane line LR detected by the road lane line detection sensor as a target travel line LT. Set.

  Next, in step S6, the arithmetic unit 22 detects the amount of deviation between the target travel line set in step S5 and the current position of the vehicle. Specifically, the arithmetic unit 22 detects the amount of deviation between the position in the width direction of the vehicle and the target travel line in the travel lane based on the image ahead of the vehicle imaged by the road marking line detection sensor.

  Next, in step S7, the arithmetic unit 22 determines a target rudder angle for causing the vehicle to travel along the target travel line. Specifically, the arithmetic unit 22 determines the target rudder angle based on the deviation amount between the target travel line and the current position of the vehicle detected in step S6 and the yaw angle of the vehicle with respect to the target travel line.

ここで、Ｍは車両重量、Ｖは車速、βは車体のスリップ角、γはヨーレート、Ｉはヨー軸周りの車両の慣性モーメント、ｌ_f及びｌ_rはそれぞれ車両重心からフロントタイヤ軸及びリアタイヤ軸までの距離、Ｙ_f及びＹ_rはそれぞれフロントタイヤ及びリアタイヤのコーナリングフォースである。
上式により得られた車体のスリップ角βから、フロントタイヤのスリップ角β_fは次式により求めることができる。

ここで、δはフロントタイヤの舵角である。
次に、演算ユニット２２は、予め演算ユニット２２のメモリに記憶されている車両のタイヤ特性（セルフアライニングトルク特性）に基づき、推定したスリップ角が生じた場合にフロントタイヤに発生するセルフアライニングトルクを推定する。
フロントタイヤのスリップ角とセルフアライニングトルクとの関係は、一般に強い非線形性を持つが、車線維持制御は舵角が小さい領域で行われることを考慮すると、以下の線形式によってセルフアライニングトルクＳＡＴを求めることができる。

ここで、αは車両のタイヤ特性に基づいて定めた係数であり、予め演算ユニット２２のメモリに記憶されている。 Next, in step S8, the arithmetic unit 22 estimates the self-aligning torque generated in the vehicle tire when the target steering angle determined in step S7 is achieved.
Specifically, first, the arithmetic unit 22 uses the vehicle speed detected by the vehicle speed sensor 14 and the yaw rate detected by the yaw rate sensor 16 as parameters, and the front tire when the target steering angle determined in step S7 is achieved. Is estimated by an observer (vehicle state model).
Considering that the behavior of the vehicle by the lane keeping control is in the linear region, when the observer is constructed by the linear two-wheel model, the equation of motion of the vehicle model in the horizontal plane is described by the following equation.

Here, M is the vehicle weight, V is the vehicle speed, β is the slip angle of the vehicle body, γ is the yaw rate, I is the inertia moment of the vehicle around the yaw axis, and l _f and l _r are the front tire axis and the rear tire axis from the vehicle center of gravity, respectively. , Y _f and Y _r are the cornering forces of the front tire and the rear tire, respectively.
From the slip angle β of the vehicle body obtained by the above equation, the slip angle β _f of the front tire can be obtained by the following equation.

Here, δ is the steering angle of the front tire.
Next, the arithmetic unit 22 performs self-aligning that occurs in the front tire when an estimated slip angle occurs based on the vehicle tire characteristics (self-aligning torque characteristics) that are stored in the memory of the arithmetic unit 22 in advance. Estimate torque.
Although the relationship between the slip angle of the front tire and the self-aligning torque is generally strongly nonlinear, considering that the lane keeping control is performed in a region where the rudder angle is small, the self-aligning torque SAT is expressed by the following line format. Can be requested.

Here, α is a coefficient determined based on the tire characteristics of the vehicle, and is stored in the memory of the arithmetic unit 22 in advance.

  Next, in step S9, the arithmetic unit 22 corrects the self-aligning torque estimated in step S8 based on the vehicle speed. Specifically, the arithmetic unit 22 increases the correction amount of the self-aligning torque as the vehicle speed detected by the vehicle speed sensor 14 increases, thereby increasing the estimated value of the self-aligning torque.

  Next, in step S10, the arithmetic unit 22 determines a target torque to be applied to the vehicle steering based on the target rudder angle determined in step S7 and the self-aligning torque corrected in step S9. Specifically, the arithmetic unit 22 first refers to a map that shows the relationship between the target rudder angle and the basic target torque stored in advance in the memory of the arithmetic unit 22, and refers to the basic target torque corresponding to the target rudder angle. To decide. Next, the arithmetic unit 22 determines the sum of the basic target torque and the self-aligning torque corrected in step S9 as the target torque.

Next, in step S11, the arithmetic unit 22 determines whether or not the amount of deviation between the target travel line detected in step S6 and the current position of the vehicle has increased. As a result, when the amount of deviation between the target travel line and the current position of the vehicle increases, it is considered that an influence of a bank of roads, crosswinds, and the like has occurred. In this case, the process proceeds to step S12, and the arithmetic unit 22 corrects the target torque determined in step S10 according to the increasing speed of the deviation amount. For example, the arithmetic unit 22 corrects the absolute value of the target torque so that it increases as the deviation rate increases. After step S12, the process returns to step S1.
On the other hand, if the amount of deviation between the target travel line detected in step S6 and the current position of the vehicle has not increased, the arithmetic unit 22 returns to step S1 without correcting the target torque.
Thereafter, until the vehicle ignition switch (not shown) is turned off or the lane keeping control switch (not shown) is turned off, the arithmetic unit 22 repeats the processes of steps S1 to S12.

Next, a modified example of the lane keeping control device 1 will be described.
In the embodiment described above, the arithmetic unit 22 determines that the traveling lane of the vehicle is a curve when the yaw rate detected by the yaw rate sensor 16 is equal to or greater than a predetermined threshold, and when the yaw rate is less than the threshold. Although it has been described that the traveling lane of the vehicle is determined to be a straight line, it may be detected whether the traveling lane of the vehicle is a straight line or a curved line by a different method.
For example, it may be detected whether the travel lane of the vehicle has a straight or curved shape based on map data acquired by the navigation system, an image in front of the vehicle captured by the camera, or the like. .

  Finally, effects of the lane keeping control device 1 according to the embodiment and the modification of the present invention will be described.

First, the arithmetic unit 22 of the lane keeping control device 1 estimates the self-aligning torque generated in the vehicle tire when the target rudder angle determined based on the amount of deviation between the target travel line and the current position of the vehicle is achieved. Since the target torque to be applied to the vehicle steering is determined based on the target rudder angle and the self-aligning torque, the target torque required to drive the vehicle along the target travel line is determined based on the vehicle running state. Self-aligning torque that changes from moment to moment (for example, vehicle speed, road curvature, etc.) can be taken into consideration and can be determined accurately in real time, which makes it stable under various circumstances. Thus, the vehicle can travel along the target travel line.
In addition, since the lane marking of the traveling lane of the vehicle is detected at a time interval according to the shape of the traveling lane, the lane marking of the traveling lane is detected at an appropriate time interval according to the shape of the traveling lane, and the detection result Accordingly, it is possible to control the torque applied to the steering of the vehicle, thereby achieving both improved drive feeling and a sense of security.

  In particular, the arithmetic unit 22 of the lane keeping control device 1 corrects the estimated self-aligning torque based on the vehicle speed, so that the self-aligning torque can be estimated more accurately, whereby a more appropriate target torque is obtained. And the vehicle can travel along the target travel line stably under various conditions.

  Further, since the arithmetic unit 22 of the lane keeping control device 1 increases the correction amount of the self-aligning torque as the vehicle speed increases, the self-aligning torque that increases as the vehicle speed increases can be estimated more accurately. Thus, a more appropriate target torque can be determined, and the vehicle can travel along the target travel line stably under various conditions.

  Further, the arithmetic unit 22 of the lane keeping control device 1 corrects the target torque according to the increasing speed of the deviation amount when the deviation amount between the target travel line and the current position of the vehicle is increased. Even when the amount of deviation between the target travel line and the vehicle's current position is increased due to the effects of banks, crosswinds, etc., the target torque can be appropriately determined so as to offset the effects. Therefore, the vehicle can travel along the target travel line in a stable manner.

DESCRIPTION OF SYMBOLS 1 Lane maintenance control apparatus 2 Steering wheel 4 Steering shaft 6 Actuator 8 Steering torque controller 10 Steering gear apparatus 12 Steering wheel 14 Vehicle speed sensor 16 Yaw rate sensor 18 Steering angle sensor 20 Road marking line detection sensor (lane marking detection means)
22 Arithmetic unit (travel lane shape detection means, target travel line setting means, deviation amount detection means, target rudder angle determination means, self-aligning torque estimation means, target torque determination means, self-aligning torque correction means, target torque correction means )
LL Left marking line LR Right marking line LT Target driving line

Claims (4)

A lane keeping control device for performing lane keeping control of a vehicle,
A traveling lane shape detecting means for detecting whether the traveling lane of the vehicle is a straight line or a curved shape;
When the running lane of the vehicle is a curve, the lane marking of the traveling lane of the vehicle is detected at a detection time interval during curved running, and when the running lane of the vehicle is a straight line, the lane marking of the traveling lane of the vehicle is Lane marking detection means for detecting at a detection time interval during straight running longer than a detection time interval during curve running;
A target travel line setting means for setting a target travel line of the vehicle based on a lane marking of the travel lane of the vehicle;
A deviation amount detecting means for detecting a deviation amount between the target travel line and the current position of the vehicle;
Target rudder angle determining means for determining a target rudder angle for causing the vehicle to travel along the target travel line based on the deviation amount;
Self-aligning torque estimating means for estimating self-aligning torque generated in the front tire of the vehicle when the target rudder angle is achieved;
Referring to a predetermined map for the relationship between the target rudder angle and the basic target torque, the basic target torque corresponding to the target rudder angle determined by the target rudder angle determining means is determined, the basic target torque, the sum of the self aligning torque self-aligning torque estimating means has estimated, possess a target torque determining means for determining a target torque applied to the steering of the vehicle, and
The self-aligning torque estimating means estimates the slip angle of the front tire of the vehicle when the target rudder angle is achieved, and calculates the product of a coefficient determined in advance based on the tire characteristics of the vehicle and the slip angle. A lane keeping control device characterized by estimating self-aligning torque .   2. The lane keeping control device according to claim 1, further comprising self-aligning torque correcting means for correcting the self-aligning torque estimated by the self-aligning torque estimating means based on a vehicle speed.   The lane keeping control device according to claim 2, wherein the self-aligning torque correcting means increases the correction amount of the self-aligning torque as the vehicle speed increases.   Furthermore, when the deviation | shift amount is increasing, it has the target torque correction means which correct | amends the target torque which the said target torque determination means determined according to the increase speed of the deviation | shift amount. The lane keeping control device described in 1.

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