JP2010030504A - Vehicle steering controller and vehicle steering control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle steering device previously suppressing actual vehicle behavior to a deviation side and suppressing incompatible sense given to a driver. <P>SOLUTION: In the vehicle adopting a steer-by-wire system, as the one's own vehicle approaches to a lane end part reference set relative to deviation from a center in a width direction of a traveling lane where the one's own vehicle travels to a position offset to at least one side of left and right sides in the width direction, control is performed such that steering reaction force relative to steering wheel steering by the driver to the traveling lane end part side becomes heavy and vehicle behavior to the deviation side is previously suppressed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a technique related to vehicle steering control. In particular, the present invention relates to a vehicle steering control device and a vehicle steering control method that are effective in supporting the maintenance of the traveling lane of the vehicle.

Conventionally, as a technique for assisting lane maintenance by steering control, there is a technique described in Patent Document 1, for example.
This technique detects an angular deviation (yaw angle) between the traveling direction of the vehicle and the traveling lane, and controls steering in a direction to cancel the angular deviation. This prevents the vehicle from deviating from the travel lane.
Moreover, there exists a technique of patent document 2 as a similar technique.
Japanese Patent No. 3729494 Japanese Patent No. 3246428

The prior art as described above performs feedback control of the steered wheels in a direction that cancels the generated angular deviation. That is, the control is performed to suppress the angular deviation after an angular deviation that is a vehicle behavior toward the departure side occurs. For this reason, the control intervention becomes behind. As a result, in order to ensure the effect of preventing lane departure, the control amount may have to be increased. And, the greater the amount of control that intervenes to maintain the lane, the greater the uncomfortable feeling to the driver.
Here, the vehicle behavior toward the departure side is a vehicle behavior in which the host vehicle travels toward the lane edge side that is relatively closer to the host vehicle.
The present invention has been made paying attention to the above points, and it is an object to suppress in advance the actual vehicle behavior toward the departure side.

  In order to solve the above-described problem, the present invention relates to a traveling lane as the host vehicle approaches a lane edge reference that is a position offset from the center in the width direction of the traveling lane in which the host vehicle travels to at least one of the left and right sides in the width direction. The steering reaction force against the steering of the steering wheel by the driver toward the end is heavily controlled.

  According to the present invention, the vehicle behavior toward the departure side is suppressed in advance by making it difficult to cut the handle toward the departure side (the lane edge side). As a result, for example, it is possible to support lane keeping while suppressing a control amount to intervene to prevent departure by feedback control. In addition, a reduction in the control amount for the vehicle behavior toward the departure side that has occurred also leads to a reduction in discomfort given to the driver.

Next, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system schematic configuration diagram of a host vehicle to which the lane keeping assist device of the present embodiment is applied.
The host vehicle of this embodiment employs a steer-by-wire system. That is, the turning angle of the steered wheels can be controlled independently of the steering state of the steering wheel. Further, the steering reaction force of the steering wheel can be controlled independently of the steered state of the steered wheels.

(Constitution)
First, the configuration will be described with reference to FIG.
The steering input shaft 30 is connected to the handle 12 operated by the driver. The steering input shaft 30 is provided with a handle angle sensor 1 that detects the steering angle of the handle 12. The handle angle sensor 1 outputs the detected steering angle signal to the steering controller 11.
A first intermediate shaft 31 is connected to the steering input shaft 30 via the steering torque sensor 2. The steering torque sensor 2 detects the steering torque input to the steering input shaft 30 and outputs the torque signal to the steering controller 11.

  The steering reaction force actuator 3 is connected to the first intermediate shaft 31. The steering reaction force actuator 3 applies a steering reaction force to the first intermediate shaft 31 based on a command from the steering controller 11. A steering reaction force motor angle sensor 4 is provided on the steering reaction force motor of the steering reaction force actuator 3. The steering reaction force motor angle sensor 4 detects the rotational angle position of the steering reaction force motor and outputs the detection signal to the steering controller 11.

  A second intermediate shaft 32 is connected to the first intermediate shaft 31 via the mechanical backup device 10. The mechanical backup device 10 is in a state in which torque transmission between the first intermediate shaft 31 and the second intermediate shaft 32 is cut off in a normal state. Further, the mechanical backup device 10 connects the first intermediate shaft 31 and the second intermediate shaft 32 based on a command from the steering controller 11 to enable torque transmission.

  The second intermediate shaft 32 is connected to the steering output shaft 33 via the steering torque sensor 7. The steering actuator 5 is connected to the second intermediate shaft 32. The turning actuator 5 rotates and displaces the second intermediate shaft 32 based on a command from the steering controller 11. A steering actuator angle sensor 6 is provided in the steering motor of the steering actuator 5. The steered actuator angle sensor 6 detects the rotational angle position of the motor of the steered actuator 5 and outputs a detection signal to the steering controller 11.

  The steering output shaft 33 is connected to the rack shaft 34 via a rack and pinion mechanism. That is, the pinion connected to the steering output shaft 33 meshes with the rack of the rack shaft 34. The rack shaft 34 is disposed with its axis directed in the vehicle width direction. Then, by rotating the steering output shaft 33, the rack shaft 34 is displaced in the axial direction toward the vehicle width direction. Reference numeral 8 denotes a pinion angle sensor 8 that detects the rotation angle of the pinion and outputs it to the steering controller 11.

  The left and right ends of the rack shaft 34 are connected to the knuckle via the left and right tie rods 35, respectively. Reference numeral 36 denotes a knuckle arm protruding from the knuckle. The knuckle rotatably supports the front wheel 13 which is a steering wheel. The tie rod axial force sensor 9 is provided on the tie rod 35. The tie rod axial force sensor 9 detects the axial force of the tie rod 35 and outputs a detection signal to the steering controller 11.

In addition, the host vehicle state parameter 14 is input to the steering controller 11. The own vehicle state parameter 14 is, for example, a vehicle speed detected by the vehicle speed detecting means or a friction coefficient estimated value of the running road surface detected by the road surface friction coefficient estimating means.
The steering controller 11 controls the steering actuator 5 based on a command from the lane keeping support controller 15 so as to obtain a steering command value, and also performs a steering reaction so as to obtain a command value for applying a steering reaction force. The force actuator 3 is controlled.

Further, each of the front wheel 13 and the rear wheel 40 is provided with a brake unit. Each brake unit includes a brake disk 22 and a wheel cylinder 23 that frictionally clamps the brake disk 22 to supply a braking force (braking force) by supplying hydraulic pressure. A pressure control unit 24 is connected to each wheel cylinder 23 of these brake units, and the brake unit individually applies braking to each wheel by the hydraulic pressure supplied from the pressure control unit 24.
A vehicle steering control device is provided as a lane keeping assist device for the host vehicle having the above system configuration.

The configuration will be described next.
A monocular camera with an image processing function is installed in the vehicle. This monocular camera with an image processing function is an external recognition means 16 for detecting the position of the host vehicle. A monocular camera with an image processing function images a road surface ahead of the host vehicle. The state of the road surface is determined from the captured camera image, and a signal related to the position of the host vehicle in the travel lane on which the host vehicle travels is output to the lane keeping support controller 15. The signal related to the position of the host vehicle in the travel lane is information regarding the yaw angle θ, which is an angular deviation in the traveling direction of the host vehicle with respect to the travel lane, the lateral displacement X from the center of the travel lane, and the curvature ρ of the travel lane.

Further, a direction indicating switch 17 is provided. A signal from the direction indicating switch 17 is output to the lane keeping support controller 15 as determination information as to whether or not the driver changes the driving lane.
Further, the lane keeping support controller 15 receives signals from the steering controller 11 such as the current steering state and tire steering state.
The lane keeping support controller 15 calculates a control amount for keeping the host vehicle in the traveling lane based on the input signal, and outputs it to at least the steering controller 11.

Next, the processing of the lane keeping support controller 15 will be described with reference to FIG.
The lane keeping support controller 15 is repeatedly executed every predetermined sampling period.
First, in step S100, various data from each sensor and controller are read. From the sensors, the wheel speed Vw, the steering angle δ, the steering angular velocity δ ′, the steering torque τ, and the signal of the direction indicating switch 17 are read. From the external recognition means 16, the yaw angle θ of the vehicle with respect to the travel lane of the host vehicle, the lateral displacement X from the center of the travel lane, and the curvature ρ of the travel lane are read.

Subsequently, in step S110, the left and right lane edge reference threshold values XLt and XRt are set based on the following equations (1) and (2).
Here, as shown in FIG. 3, the right lane edge reference threshold value XRt specifies the position of the lane edge reference LXR set for the right departure. The left lane edge reference threshold XLt specifies the position of the lane edge reference LXL set for the left departure.
XRt = (Wlane / 2)-(Wcar / 2)
-Xoffset (1)
XLt = − ((Wlane / 2) − (Wcar / 2)
-Xoffset) (2)

Further, the left and right lane width direction offset threshold values XLt2 and XRt2 are set based on the following.
XRt2 = (Wlane / 2)-(Wcar / 2)
-Xoffset2 (1)
XLt2 = − ((Wlane / 2) − (Wcar / 2)
-Xoffset2) (2)
Here, the lateral displacement X from the travel lane center Ls is positive when the host vehicle C is on the right side of the center with respect to the travel lane L, and is negative when the vehicle is located on the left side. For this reason, the right lane edge reference threshold value XRt and the lane width direction offset threshold value XRt2 side are positive.

Further, as shown in FIG. 3, Wlane is the travel lane width, and Wcar is the vehicle width of the host vehicle C.
Xoffset and Xoffset2 are margins for the position of the traveling lane edge Le (white line or shoulder). The margin allowances Xoffset and Xoffset2 may be changed according to the travel lane width Wlane, the vehicle speed, and the like. For example, the margins Xoffset and Xoffset2 are made smaller as the travel lane width Wlane is narrower. Also, different margins Xoffset and Xoffset2 may be used for the left and right lane edge reference LXL, LXR.

Further, the margin allowances Xoffset and Xoffset2 may be zero or negative values. Further, the left and right lane edge reference LXL, LXR may be fixed values. Further, the margin allowances Xoffset and Xoffset2 may be the same value. In this case, the left and right lane edge reference threshold values XLt and XRt are the same as the left and right lane width direction offset threshold values XLt2 and XRt2.
Next, in step S120, the yaw angle deviation ΔθR with respect to the right departure is calculated based on the following equation.
ΔθR = θ (when θ> 0)
ΔθR = 0 (when θ ≤ 0)
Here, the yaw angle θ of the vehicle with respect to the travel lane is positive when the yaw angle is on the right side and negative when the yaw angle is on the left side, as shown in FIG. Further, since ΔθR is a yaw angle deviation set only for the right deviation, as shown in FIG. 5A, when ΔθR ≦ 0, ΔθR = 0 is set (only positive values are taken). To do).

Next, in step S130, a yaw angle deviation ΔθL with respect to the left departure is calculated based on the following equation.
ΔθL = θ (when θ <0)
ΔθL = 0 (when θ ≧ 0)
Here, since ΔθL is the yaw angle deviation set only for the left deviation, as shown in FIG. 5B, when ΔθL ≧ 0, ΔθL = 0 (only negative values are taken). ).
Next, in step S140, a first target correction turning angle φY1 * is calculated. The first target correction turning angle φY1 * is a control amount for canceling the yaw angle θ of the vehicle with respect to the traveling lane. That is, it is a control amount for angle deviation for making the traveling lane and the traveling direction of the vehicle parallel.

The calculation of the first target correction turning angle φY1 * will be described.
First, the first target turning angle φY1_R * for the right departure and the first target turning angle φY1_L * for the left departure are calculated by the following equations, respectively.
φY1_R * = − (Kc_Y × Ky_R × Kv_Y × ΔθR)
φY1_L * = − (Kc_Y × Ky_L × Kv_Y × ΔθL)
Here, Kc_Y is a feedback gain determined by vehicle specifications. Kv_Y is a correction gain according to the vehicle speed.

Ky_R and Ky_L are feedback gains that are individually set according to the lateral displacement of the host vehicle with respect to the traveling lane, as shown in FIGS. 6 (a) and 6 (b). Then, the feedback gain Ky_R for the right departure is set to increase as the right lane edge reference LXR is approached. Further, the feedback gain Ky_L for the left departure is set to increase as it approaches the left lane edge reference LXL. Further, the first target turning angles φY1_R * and φY1_L * are positive for rightward turning and negative for leftward turning.
Here, instead of XLt and XRt, lane width direction offset threshold values XLt2 and XRt2 may be used as the boundary between the minimum values of the feedback gains Ky_R and Ky_L.

Next, based on the following formula, the first target turning angle φY1 * is calculated as the sum of the first target turning angle φY1_R * for the right departure and the first target turning angle φY1_L * for the left departure.
φY1 * = φY1_R * + φY1_L *
If the yaw angle is on the right side, ΔθL = 0 is set in step S130. Accordingly, the first target turning angle φY1_L * for the left departure is 0, and only the first target turning angle φY1_R * for the right departure is employed. Similarly, if the yaw angle is on the left side, ΔθR = 0 is set in step S120. Therefore, the first target turning angle φY_R * for the right departure is 0, and only the first target turning angle φY_L * for the left departure is employed.

As a result, when the yaw angle is generated on the departure side, control is performed to positively prevent the departure. On the other hand, when the yaw angle is generated toward the departure avoidance side, the direction of the vehicle can be adjusted gently with respect to the traveling lane without a sense of incongruity.
Next, in step S150, the steering reaction force actuator 3 is controlled so that the steering wheel position corresponding to the first target correction turning angle φY1 * becomes a neutral position of the steering reaction force.

  For example, a reaction force center correction value corresponding to the deviation between the handle position corresponding to the first target turning angle φY1 * position and the actual handle position is calculated. Then, a command is output to the steering controller 11 so as to apply a steering reaction force corresponding to the reaction force center correction value. The steering controller 11 controls the steering reaction force actuator 3 so as to output a steering reaction force corresponding to the reaction force center correction value.

Next, in step S160, a steering angle reference value δR * for a right departure and a steering angle reference value δL * for a left departure are calculated. The steering angle reference values δR * and δL * are reference values used to calculate the amount of increase toward the lane edge by steering of the driver's steering wheel.
Here, by the process of step S150, the steering reaction force becomes the neutral position (the steering torque becomes zero) at the steering wheel position (steering angle) where the traveling lane and the traveling direction of the host vehicle are parallel. For this reason, regardless of whether the driving lane is a straight road or a curved road, the direction in which the traveling lane and the traveling direction of the host vehicle are parallel is changed from the direction in which the driver approaches the left or right end of the driving lane. Whether the vehicle is steered can be detected by the sign of the steering torque τ.

The steering angle reference value δR * for the right departure is calculated for each case as follows.
That is,
1) When the steering torque τ ≦ τth (when the steering torque is not applied to the right), the steering angle reference value δR * for the right departure is updated with the actual steering angle value δ as in the following equation.
δR * = δ
2) When the steering torque τ> τth, the steering angle reference value δR * for the right departure is not updated (held).

Similarly, the steering angle reference value δL * for the left departure is calculated for each case as follows.
That is,
1) When the steering torque τ ≧ −τth (when the steering torque is not applied to the left), the steering angle reference value δL * for the left departure is updated with the actual steering angle value δ as shown in the following equation.
δL * = δ
2) When the steering torque τ <−τth, the steering angle reference value δL * for the left deviation is not updated (held).

Here, τth is a steering torque threshold for determining driver steering, and is set as an absolute value (positive value). The steering torque τ is a positive value when the steering torque is applied to the right, a negative value when the steering torque is applied to the left, and the steering angle δ is a positive value when steering in the right direction. Value, and leftward steering is a negative value.
Based on the above calculation, the actual steering angle value δ when a steering torque equal to or greater than the steering torque threshold τht is detected becomes the steering angle reference value δR * for the right departure or the steering angle reference value δL * for the left departure.

Next, in step S170, the amount of steering increase to the lane edge side by the steering operation of the driver is calculated based on the following equation.
The amount of steering increase ΔδR toward the right lane edge reference side is calculated by the following equation.
ΔδR = δ−δR * (when δ> δR *)
ΔδR = 0 (when δ ≦ δR *)
Similarly, the amount of steering increase ΔδL toward the left lane edge reference side is calculated by the following equation.
ΔδL = δ−δL * (when δ <δL *)
ΔδL = 0 (when δ ≧ δL *)
As a result, the amount of steering of the steering wheel toward the left and right lane edge reference sides can be extracted as the amount of steering increase.

Next, in step S180, a second target correction turning angle φY2 * is calculated. The second target turning angle φY2 * is a control amount for suppressing in advance the movement of the vehicle toward the departure side.
The second target turning angle φY2 * is calculated by calculating the second target turning angle φY2_R * for the right departure and the second target turning angle φY2_L * for the left departure and taking the sum thereof. The turning angle φY2 * is calculated.
First, the second target turning angle φY2_R * for the right departure and the second target turning angle φY2_L * for the left departure are calculated by the following equations, respectively.

That is, the second target turning angle φY2_R * for the right departure is calculated by the following formula.
1) When steering torque τ ≧ τth (when steering torque is applied to the right)
φY2_R * = − (Kc_g × Kg_R × KρL_R × ΔδR)
2) When steering torque τ <τth φY2_R * = 0

Further, the second target turning angle φY2_L * for the left departure is calculated by the following formula.
1) When steering torque τ ≦ −τth (when steering torque is applied to the left)
φY2_L * = − (Kc_g × Kg_L × KρL_L × ΔδL)
2) When steering torque τ> −τth φY2_L * = 0
Here, Kc_g is a gear ratio coefficient between the steering angle (steering wheel angle) and the tire angle (steering wheel turning angle) determined by the specifications of the vehicle.

Kg_R and Kg_L are steering suppression gains with respect to the amount of steering increase toward the traveling lane edge side by driver steering. Kg_R and Kg_L are individually set according to the lateral displacement with respect to the traveling lane as shown in FIGS. 7 (a) and 7 (b).
Here, the steering suppression gain Kg_R for the right departure is set to increase as it approaches the right traveling end reference. The steering suppression gain Kg_L for the left departure is set so as to increase as it approaches the left traveling end reference. However, the maximum value of these steering suppression gains is 1.0. By setting the maximum value to 1.0, the second target turning angle becomes an upper limit value for canceling the amount of increase in steering by the driver. That is, the steering response of the tire angle with respect to the steering angle (steering wheel angle) can be lowered only when the driver steers to the departure side, and lane keeping support can be performed appropriately without feeling of restraint or discomfort. Note that the lane edge reference threshold values XLt and XRt may be used as the minimum threshold value instead of XLt2 and XRt2.

Kρ is a value as shown in FIG.
That is, the curve correction gain KρL_R for the right departure and the curve for the left departure are divided into three types according to the direction of the curvature ρ (curve direction of the traveling lane L) and using individual maps as follows. A correction gain KρL_L is set.
When it is determined that the curvature ρ <0 (right curve):
KρL_R: Read from a curve IN side correction gain map as shown in FIG.
KρL_L: Read from the curve OUT side correction gain map as shown in FIG.

When it is determined that the curvature ρ> 0 (left curve), KρL_R: read from a curve OUT side correction gain map as shown in FIG.
KρL_L: Read from a curve IN side correction gain map as shown in FIG.
When it is determined that the curvature ρ = 0 (straight road) KρL_R = 1.0 (no correction)
KρL_L = 1.0 (no correction)
Here, the curvature ρ of the lane L is the reciprocal of the turning radius, ρ = 0 on a straight road, and the absolute value of the curvature ρ increases as the curve becomes tighter (the turning radius decreases). The left curve is positive and the right curve is negative.

  As shown in FIG. 8A, the curve IN side correction gain map is a map in which the correction gain decreases as the absolute value of the curvature ρ increases as the absolute value of the curvature ρ increases to a predetermined value or more. And the gain of control with respect to the travel lane edge Le located inside the curved road among the left and right travel lane edges Le is corrected so as to decrease in accordance with the increase in the absolute value of the curvature ρ.

Further, as shown in FIG. 8B, the curve OUT side correction gain map is a map in which the correction gain increases as the absolute value of the curvature ρ increases as the absolute value of the curvature ρ increases to a predetermined value or more. . And the gain of control with respect to the traveling lane edge Le located outside the curved road among the left and right traveling lane edges Le is corrected so as to increase in accordance with the increase in the absolute value of the curvature ρ.
However, Kρ = 1 may be set unconditionally.
Then, the second target corrected turning angle φY2 * is calculated as the sum of the second target turning angle φY2_R * for the right departure and the second target turning angle φY2_L * for the left departure as shown in the following equation.
φY2 * = φY2_R * + φY2_L *

Next, in step S190, a final target correction turning angle φY * for lane keeping support is calculated. In the present embodiment, the final target corrected turning angle φY is calculated as the sum of the first target turning angle φY1 * calculated in step S140 and the first target turning angle φY2 * calculated in step S180, as in the following equation. * Is calculated.
φY * = φY1 * + φY2 *
Next, in step S200, the final target turning angle φ * of the vehicle is calculated. At this time, correction for the final target correction turning angle φY * is performed.

First, the turning angle φ0 corresponding to the driver's steering operation (steering angle δ) is calculated. The turning angle φ0 corresponding to the driver's steering operation (steering angle δ) is (Kc_g × δ). Kc_g is a gear ratio coefficient determined by the specifications of the vehicle.
Then, the final target target turning angle φY * for lane keeping support calculated in step S190 is added as in the following equation. That is, the final target turning angle φ * of the vehicle is calculated by correcting the final target turning angle φY * for lane keeping support.
φ * = φ0 + φY *

However, if the direction indicating switch 17 is ON and the direction indicated by the direction indicating switch 17 coincides with the steering direction of the steering wheel, the final target target steering for lane keeping support is performed. Calculation is performed as follows without adding the angle φY *.
φ * = φ0
Next, in step S210, a command for the final target turning angle φ * is output to the steering controller 11.
The steering controller 11 drives the turning actuator 5 so that the turning angle becomes the final target turning angle φ *. As a result, the turning angle of the front wheel that is the steered wheel becomes the final target turning angle φ *.

In step S220, the first target correction steering reaction force τY1 * is calculated as a steering reaction force for lane keeping support. The first target correction steering reaction force τY1 * is a steering reaction force with respect to the steady steering input of the driver. The first target steering reaction force τY1 * is calculated according to the steering torque τ applied by the driver to the lane edge side.
First, a first target steering reaction force τY1_R * for a right departure and a first target steering reaction force τY1_L * for a left departure are calculated for each case as follows.

First, the first target steering reaction force τY1_R * for the right departure is calculated by the following equation.
1) When steering torque τ ≧ τth (when steering torque is applied to the right)
τY1_R * = Kt_R × (τ−τth)
2) When steering torque τ <τth
τY1_R * = 0

Further, the first target steering reaction force τY1_L * for the left departure is calculated by the following equation.
1) When steering torque τ ≦ −τth (when steering torque is applied to the left)
τY1_L * = Kt_L × (τ + τth)
2) When steering torque τ> −τth
τY1_L * = 0

  Here, Kt_R and Kt_L are first target steering reaction force calculation gains with respect to the steering torque toward the traveling lane edge by the driver's steering. These Kt_R and Kt_L are gains individually set according to the lateral displacement with respect to the traveling lane as shown in FIGS. 9 (a) and 9 (b). The first target steering reaction force calculation gain Kt_R for the right departure is set so as to increase as the right lane edge reference is approached. The first target steering reaction force calculation gain Kt_L for the left departure is set to increase as the left lane edge reference is approached. However, the first target steering reaction force calculation gains Kt_R and Kt_L have a maximum value of 1.0. As a result, the first target steering reaction force has an upper limit for canceling the steering torque due to driver steering. That is, the steering reaction force can be increased only when the driver steers to the departure side. If a steering reaction force greater than the steering torque by the driver is generated, the steering wheel is repelled by the generated reaction force, that is, returned. However, by setting the upper limit as described above, control within the range where the steering reaction force is “heavy” is possible. Here, the gain 1.0 is a position where the force is balanced by the steering torque input by the driver. The above balance means that the handle stops. Thus, it is possible to appropriately perform lane keeping support without feeling of restraint or discomfort.

Next, the first target corrected steering reaction force τY1 * is calculated as the sum of the first target steering reaction force τY1_R * for the right departure and the first target steering reaction force τY1_L * for the left departure as shown in the following equation.
τY1 * = τY1_R * + τY1_L *
Here, τY1 *, τY1_R *, and τY1_L * are positive values when the steering reaction force is generated to the left and negative values when the steering reaction force is generated to the right.

Next, in step S230, a second target correction steering reaction force τY2 * is calculated. The second target correction steering reaction force τY2 * is a steering reaction force for lane keeping support and is a steering reaction force with respect to a driver's transient steering input. The second target correction steering reaction force τY2 * is calculated according to the steering angular velocity δ ′ that the driver steers to the lane edge side.
The calculation will be described.
First, a second target steering reaction force τY2_R * for a right departure and a second target steering reaction force τY2_L * for a left departure are calculated for each case as follows.

That is, the second target steering reaction force τY2_R * for the right departure is calculated by the following equation.
1) When the steering angular velocity δ ′ ≧ δ′th (when steering to the right)
τY2_R * = Ks_R × (δ′−δ′th)
2) When the steering angular velocity δ '<δ'th
τY2_R * = 0

Further, the second target steering reaction force τY2_L * for the left departure is calculated.
1) When the steering angular velocity δ'≤ -δ'th (when steering to the left)
τY2_L * = Ks_L × (δ ′ + δ′th)
2) Above when steering angular velocity δ '>-δ'th
τY2_L * = 0

  Here, Ks_R and Ks_L are second target steering reaction force calculation gains with respect to the steering angular velocity toward the lane edge side by driver steering. The second target steering reaction force calculation gains Ks_R and Ks_L are individually set according to the lateral displacement with respect to the travel lane as shown in FIGS. Then, the second target steering reaction force calculation gain Ks_R for the right departure is set to increase as the right lane edge reference is approached. The second target steering reaction force calculation gain Ks_L for the left departure is set to increase as the left lane edge reference is approached. As a result, the steering reaction force can be increased only when the driver steers to the departure side, and lane keeping support can be performed appropriately without feeling restrained or uncomfortable.

Next, the second target corrected steering reaction force τY2 * is calculated as the sum of the second target steering reaction force τY2_R * for the right departure and the second target steering reaction force τY2_L * for the left departure as shown in the following equation. .
τY2 * = τY2_R * + τY2_L *
Here, τY2 *, τY2_R *, and τY2_L * are positive values when the steering reaction force is generated to the left and negative values when the steering reaction force is generated to the right. Further, the steering angular velocity δ ′ is a positive value for steering in the right direction and a negative value for steering in the left direction.

Next, in step S240, a final target correction steering reaction force τY * for lane keeping support is calculated. In the present embodiment, the final target corrected steering reaction force is calculated as the sum of the first target correction steering reaction force τY1 * calculated in step S220 and the second target correction steering reaction force τY2 * calculated in step S230 based on the following equation. The force τY * is calculated.
τY * = τY1 * + τY2 *

Next, in step S250, a final target steering reaction force τY is calculated. At this time, correction for the final target correction steering reaction force τY * is performed. That is, the normal target steering reaction force τY0 (conventional steering reaction force of the SBW system) is corrected by adding the final target correction steering reaction force τY * for lane keeping support as shown in the following equation. The corrected value is defined as the final target steering reaction force τY. Subsequently, this final target steering reaction force τY is output to the steering controller 11. The steering controller 11 drives the steering reaction force actuator 3 so that the final target steering reaction force τY is obtained.
τY = τY0 + τY *

However, when the direction indicating switch 17 is ON, and the indicated direction of the direction indicating switch 17 matches the steering direction of the steering wheel, the final target correction steering reaction force τY * is not added. In other words, without correction, the calculation is performed as follows.
τY = τY0
The normal target steering reaction force τY0 is a target steering reaction force that simulates road surface input and is calculated according to the steering angle, the steering angular velocity, the tie rod axial force, and the like.

(Operation / Action)
For example, it is assumed that the driver steers the steering wheel to the right while the host vehicle is traveling in parallel along the traveling lane.
At this time, the left and right steering wheels are steered to the right. At this time, the actual turning angle of the steered wheels is suppressed to a turning angle that is smaller than the turning angle corresponding to the steering angle by a turning correction amount (final target correction turning angle φY *). This steering correction amount is determined by the position of the host vehicle from the right lane edge reference, as shown in FIG. That is, when the host vehicle is far from the right lane edge reference LXR, that is, the right lane edge, the steering correction amount is small and the suppression amount is small. On the other hand, as the host vehicle approaches the right lane edge reference LXR, that is, the right lane edge, the steering correction amount increases and the suppression amount increases. As a result, as the host vehicle approaches the right lane edge reference LXR, that is, the right lane edge, the steered wheels are less likely to be steered with respect to steering.

As a result, the movement of the vehicle toward the departure side is suppressed in advance in a feedforward manner.
At this time, the steering correction amount has an upper limit on a steering angle corresponding to steering wheel steering. This prevents the driver from turning to the opposite side of the steering direction of the driver steering by the steering correction according to the steering correction amount.
Further, a steering reaction force for preventing a departure in the direction opposite to the steering direction is applied to the steering wheel of the driver. The steering reaction force for preventing departure is determined by the position of the host vehicle from the right lane edge reference LXR. That is, when the host vehicle is far from the right lane edge reference LXR, that is, the right lane edge, the steering reaction force for preventing departure is small. On the other hand, as the host vehicle approaches the right lane edge reference LXR, that is, the right lane edge, the steering reaction force for preventing departure increases and the steering torque increases. As a result, the closer the host vehicle is to the right lane edge reference LXR, that is, the right lane edge, the more difficult it is to steer the steering wheel to the departure side, and the steering amount by the driver to the departure side is suppressed. .

At this time, the steering reaction force for departure prevention has the steering torque as an upper limit, thereby preventing the steering wheel from turning to the opposite side of the driver's steering.
Further, as the steering reaction force, the steering reaction force is corrected according to the steering angular velocity of the steering wheel. The steering reaction force according to the steering angular velocity becomes larger as it approaches the lane edge reference. As a result, the steering reaction force becomes transiently heavy and the steering wheel is quickly operated toward the departure side only when the driver approaches the end of one lane and the steering wheel is steered by the driver to the lane end side (departure side). To suppress.

Further, in addition to the above operation, when the vehicle actually has an angular deviation in the left-right direction with respect to the traveling lane, feedback control is performed in a direction to cancel the angular deviation. As a result, the host vehicle can maintain traveling along the traveling lane.
At this time, as a result of suppressing the steering toward the departure side by the steering correction amount, the control amount of the feedback control in the direction to cancel the angular deviation in the departure direction is not suppressed by the steering correction amount. Compared to this, it becomes smaller.

In addition, feedback control in a direction to cancel the angle deviation, that is, control so as to be parallel to the traveling lane, and this actual turning angle (parallel to the traveling lane) becomes the center of the steering reaction force (SAT). The steering reaction force center (road surface reaction force center) is offset.
As a result, as shown in FIG. 12, the steering torque becomes zero in a state parallel to the traveling lane. As a result, even when traveling on a curved road, it is possible to detect which lane end side the driver has steered the steering wheel in the direction along the traveling lane by the steering torque.

Here, the correspondence of the configuration will be described with reference to FIG.
The front wheel 13 constitutes a steering wheel.
Step S110 constitutes a reference setting unit. The external environment recognition means 16 constitutes a lateral displacement acquisition means. Steps S170 and S180 constitute a turning suppression means. Steps S200 and S210 and the steering controller 11 constitute steering control means. The second target correction turning angle φY2 * constitutes a turning correction amount.
Steps S120 to S140 constitute angle control amount calculation means. The first target correction turning angle φY1 * constitutes an angle deviation control amount.
Steps S240 and S250 and the steering controller 11 constitute reaction force generation control means.
Step S150 constitutes a steering reaction force center position correcting means.
Steps S220 to S230 constitute steering reaction force correction means.

(Effect of 1st Embodiment)
(1) The steering suppression means calculates a steering correction amount for suppressing steering of the steered wheels relative to steering of the steering wheel as the host vehicle approaches the lane edge reference. And a steering control means correct | amends steering of the steering wheel with respect to steering of a steering wheel according to a steering correction amount.
As a result, the vehicle behavior toward the departure side (running lane edge side) is suppressed in advance in a feedforward manner.
As a result, it becomes possible to support lane keeping while suppressing the control amount for suppressing the vehicle behavior occurring in the implementation for preventing deviation by feedback control.
Suppressing the amount of control to intervene to prevent a departure can provide lane maintenance support while suppressing a sense of incongruity given to the driver.
Moreover, since it acts only when the driver intervenes in steering, it is possible to perform lane maintenance support without a sense of restraint or discomfort.

(2) The turning suppression means obtains the turning correction amount according to the position of the host vehicle with respect to the lane edge reference. That is, the steering suppression means sets the degree of suppression of steering with respect to driver steering in the lane edge reference direction according to the lateral position of the host vehicle with respect to the lane edge reference. The steered correction amount is increased as the position of the host vehicle is closer to the lane edge reference.
As a result, when the vehicle travels near the center of the travel lane with a low risk of departure, or when operating on the departure avoidance side, the degree of suppression of turning can be set small or eliminated. As a result, when the vehicle travels near the center of the travel lane with a low risk of departure or when the vehicle is operated to the departure avoidance side, the occurrence of unnecessary restraint or the like is suppressed.
On the other hand, the degree of turning suppression increases as the departure risk increases, so that when a departure avoidance operation is required, it is possible to appropriately ensure the departure prevention effect.

(3) The turning correction amount calculated by the turning suppression means has the upper limit of the turning angle of the steered wheel according to the steering amount of the steering wheel. Then, the steering control means corrects the steering correction amount in the direction opposite to the steering direction of the steered wheels by steering the steering wheel.
As a result of the amount of steering cut by the driver becoming the upper limit value of the steering correction amount, the steered wheels are not steered in the direction opposite to the driver steering direction.
In other words, only when the driver steers to the departure side, the steering response of the steering angle of the steered wheel with respect to the steering angle (handle angle) is reduced. As a result, it is possible to perform lane maintenance support without a sense of incongruity.
Further, the steering control means corrects the steering by a steering correction amount in the direction opposite to the steering direction of the steered wheels by steering the steering, thereby realizing the suppression of the steering.

(4) The angle control amount calculation means calculates an angle deviation control amount that reduces the angle deviation in the traveling direction of the host vehicle with respect to the travel lane. And a steering control means correct | amends the steering of the steering wheel with respect to steering of a steering wheel according to the steering correction amount and the control amount for angle deviations.
Thus, in addition to the suppression of the steering, feedback control is performed so that the host vehicle travels in the direction along the travel lane.
By performing feedback control so as to reduce the angle deviation, departure can be avoided, but the amount of feedback control for avoiding this departure can be suppressed by suppressing the steering. As a result, it is possible to suppress the driver's uncomfortable feeling when avoiding departure.

(5) The steering suppression means determines whether or not the steering of the steering wheel toward the lane edge reference side is based on a steering wheel steering angle position where the host vehicle travels parallel to the traveling lane.
Thereby, even if the traveling lane is a curved road, it is possible to suppress the steering for the departure from the direction in which the traveling lane and the traveling direction of the host vehicle are parallel (the direction along the curve).

(6) Steering reaction force center position correcting means corrects the steering reaction force center position so that the steering wheel steering angle position at which the host vehicle travels in parallel with the traveling lane becomes the center of the steering reaction force. Then, the steering suppression means and the steering reaction force correction means determine the steering angle position of the steering wheel where the host vehicle travels in parallel with the travel lane, based on the steering torque by the steering wheel after the correction by the steering reaction force center position correction means. To do.

That is, the steering reaction force center position correction means makes the steering reaction force a neutral position (steering torque becomes zero) at a steering wheel position (steering angle) where the traveling lane and the traveling direction of the host vehicle are parallel. As a result, regardless of whether the driving lane is a straight road or a curved road, the direction in which the traveling lane and the traveling direction of the host vehicle are parallel is changed so that the driver approaches the lane edge reference on either the left or right lane. Whether the vehicle is steered (steadyly) can be detected by the sign of the steering torque.
Note that the steering angular velocity can be detected only transiently.
In addition, since the steering angle reference value that is parallel to the traveling lane can be set, it is possible to easily detect the driver's additional amount in the departure direction.

(7) The steering reaction force correction means makes the steering reaction force with respect to steering of the steering wheel by the driver heavier as the host vehicle approaches the lane edge reference when steering the steering wheel toward the lane edge reference side. A steering reaction force correction amount is calculated. The reaction force generation control unit corrects the steering reaction force applied to the steering wheel according to the steering reaction force correction amount.
As a result, steering to the departure side becomes heavy. As a result, the movement of the vehicle toward the departure side can be suppressed in advance. For this reason, the deviation prevention effect can be ensured without increasing the control amount by the feedback control too much. In addition, it is possible to provide lane maintenance support with no sense of incongruity.
Moreover, since it acts only when the driver intervenes in steering, it is possible to perform lane maintenance support without a sense of restraint or discomfort.

(8) The steering reaction force correction means calculates a steering reaction force correction amount for increasing the steering reaction force with respect to the steering according to the lateral position of the host vehicle with respect to the lane edge reference. The steering reaction force correction amount is increased as it approaches the lane edge reference.
This makes it possible to set the steering reaction force addition amount to be small or to eliminate it when traveling near the center of the travel lane with little risk of departure or when operating on the departure avoidance side. For this reason, there is no extra sense of restraint during traveling near the center of the travel lane with a low risk of departure or when operating on the departure avoidance side.
On the other hand, since the additional amount (correction amount) of the steering reaction force is set larger as the departure risk increases, the departure prevention effect can be appropriately ensured when the departure avoidance operation is necessary.

(9) The steering reaction force correction means calculates a steering reaction force correction amount to be added in a direction to cancel the steering torque in accordance with the steering torque increased by the driver toward the lane edge reference side. The absolute value of the steering reaction force correction amount has the upper limit of the absolute value of the steering torque.
The steering reaction force correction amount has an upper limit value for canceling the steering torque by the driver. As a result, the steering wheel is not repelled in the opposite direction by the steering reaction force against the driver's steering input.
That is, the upper limit is the position where the torque is balanced and the handle stops. As a result, only when the driver steers to the departure side, the steering reaction force constantly becomes heavy and the lane keeping support without any sense of incongruity can be performed.

(10) The steering reaction force correction means calculates a steering reaction force correction amount for increasing the steering reaction force with respect to the steering in accordance with the steering angular velocity of the steering wheel toward the lane edge reference side.
As a result, only when the driver steers the steering wheel toward the departure side, the steering reaction force becomes transiently heavy. And it is possible to perform lane maintenance support without a sense of incongruity.
Furthermore, by combining a steady term according to the steering torque and a transient term according to the steering angular velocity, it is possible to cope with changes firmly without being too heavy in a steady manner, without restraint or discomfort. Lane maintenance support can be performed.

(11) The steering reaction force correction means corrects the steering reaction force center so that the steering angle position where the traveling direction of the host vehicle is parallel to the traveling lane is the steering reaction force center. The reaction force correction amount is calculated.
As a result, the steering reaction force becomes the neutral position (the steering torque becomes zero) at the steering wheel position (steering angle) where the traveling lane and the traveling direction of the host vehicle are parallel. For this reason, regardless of whether the driving lane is a straight road or a curved road, the direction in which the traveling lane and the traveling direction of the host vehicle are parallel is the direction in which the driver approaches the left or right lane edge side. Whether the steering is (steady) can be detected by the sign of the steering torque.
Then, the steering reaction force correction amount can be calculated based on the steering wheel position in the direction in which the traveling lane and the traveling direction of the host vehicle are parallel to each other.
Note that the steering angular velocity can be detected only transiently.

(Modification)
(1) The steering suppression means is a steering correction amount for suppressing the steering only when the traveling direction of the host vehicle is directed to the lane edge reference side rather than parallel or parallel to the traveling lane. May be calculated.
In this case, even if the host vehicle is in a position approaching the left and right lane edge reference, if the traveling direction of the host vehicle is away from the lane edge reference, the left or right lane edge When the steering wheel is steered to the reference side, steering is not suppressed.
Accordingly, it is possible to avoid unnecessary turning suppression by performing the turning suppression only when the vehicle is moving in the departure direction.

(2) The steering reaction force correction means may calculate the steering reaction force correction amount when the traveling direction of the host vehicle is directed to the lane edge reference side rather than parallel or parallel to the traveling lane. good.
In this case, even if the host vehicle is in a position approaching the left and right lane edge reference, if the traveling direction of the host vehicle is away from the lane edge reference, the left or right lane edge When the steering wheel is steered to the part reference side, the steering reaction force is not increased.
Thus, it is possible to avoid unnecessarily increasing the steering reaction force by performing the control to increase the steering reaction force only when the host vehicle is moving in the departure direction.

It is a figure explaining the system configuration of the vehicle concerning a 1st embodiment based on the present invention. It is a figure explaining the process of the lane maintenance assistance controller which concerns on 1st Embodiment based on this invention. It is a top view explaining the relationship of each value which concerns on 1st Embodiment based on this invention. It is a top view explaining the relationship of each value which concerns on 1st Embodiment based on this invention. It is a figure which shows the relationship between yaw angle (theta) and yaw angle deviation. It is a figure which shows the relationship of the gain Ky_R and Ky_L with respect to the horizontal position of the own vehicle. It is a figure which shows the relationship of the steering suppression gain with respect to the horizontal position of the own vehicle. It is a conceptual diagram which shows the curve correction gain with respect to a curve curvature. It is a figure explaining the relationship of the 1st target steering reaction force calculation gain with respect to the lateral position of the own vehicle. It is a figure explaining the relationship of the 2nd target steering reaction force calculation gain with respect to the lateral position of the own vehicle. It is a conceptual diagram which illustrates the relationship of a steering correction amount. It is a figure which shows the example of the center position of the steering reaction force during curve road travel. It is the figure which summarized the correspondence of the structure.

Explanation of symbols

3 Steering reaction force actuator 5 Steering actuator 11 Operation controller 12 Handle 13 Front wheel (steering wheel)
15 Lane Keeping Support Controller 16 Outside Recognizing Means Le Traveling Lane End X Lateral Displacement LXR, LXL Lane End Reference XRt, XLt Lane End Reference Threshold XRt2, XLt2 Lane Width Offset Offset δ Steering Angle δ ′ Steering Angular Speed τ Steering Torque θ Yaw angle ρ Curvature φ * Final target turning angle φ0 Steering angle φY * Final target correction turning angle φY1 * First target correction turning angle φY2 * Second target correction turning angle Kg_R, Kg_L Rudder suppression gain Ky_R, Ky_L Feedback gain KρL_R, KρL_L Curve correction gain τY Final target steering reaction force τY * Final target correction steering reaction force τY0 Target steering reaction force τY1 * First target correction steering reaction force τY2 * Second target correction steering reaction Force Kt_R, Kt_L First target steering reaction force calculation gain Ks_R, Ks_L Second target steering reaction force calculation gain

Claims (9)

In a vehicle steering control device comprising: a steering wheel steered by a driver; and a reaction force generation control unit that controls a steering reaction force applied to the steering wheel.
A lane edge reference that is a position that is offset to at least one of the width direction left and right from the width direction center of the traveling lane in which the host vehicle travels is provided,
Lateral displacement acquisition means for acquiring information on the lateral displacement of the host vehicle relative to the traveling lane;
Steering reaction force for increasing the steering reaction force against the steering of the steering wheel toward the lane edge reference side by the driver as the host vehicle approaches the lane edge reference side based on the information acquired by the lateral displacement acquisition means. A steering reaction force correcting means for calculating a correction amount;
The reaction force generation control means corrects the steering reaction force applied to the steering wheel according to the steering reaction force correction amount.   The steering reaction force correction means calculates a steering reaction force correction amount for increasing the steering reaction force with respect to the steering according to the lateral position of the host vehicle with reference to the lane edge reference, and corrects the steering reaction force correction. 2. The vehicle steering control device according to claim 1, wherein the amount is increased as the own vehicle is closer to the lane edge reference.   The steering reaction force correction means calculates a steering reaction force correction amount to be added in a direction to cancel the steering torque according to the steering torque increased by the driver toward the lane edge reference side, and determines the steering reaction force correction amount. The vehicle steering control device according to claim 1 or 2, wherein the absolute value has an upper limit on the absolute value of the steering torque.   The steering reaction force correcting means corrects a steering reaction force correction amount for increasing a steering reaction force with respect to the steering in accordance with a steering angular velocity of steering the steering toward the lane edge reference side. The vehicle steering control device according to any one of claims 1 to 3.   The steering reaction force correction means determines whether or not the steering of the steering wheel toward the lane edge reference side is based on the position of the steering angle at which the traveling direction of the host vehicle is parallel to the traveling lane. The vehicle steering control device according to any one of claims 1 to 4. Steering reaction force center position correction means for correcting the steering reaction force center position via the reaction force generation control means so that the steering angle of the steering wheel where the host vehicle travels in parallel with the traveling lane becomes the center of the steering reaction force ,
The steering reaction force correction means determines a steering angle position of the steering wheel at which the host vehicle travels in parallel with the travel lane, based on the steering torque generated by the steering wheel after the correction by the steering reaction force center position correction means. The vehicle steering control device according to claim 5.   The steering reaction force correction means calculates the steering reaction force correction amount when the traveling direction of the host vehicle is directed to the lane edge reference side rather than parallel or parallel to the traveling lane. The vehicle steering control device according to any one of claims 1 to 6. Angle control amount calculation means for calculating an angle deviation control amount for reducing the angle deviation of the traveling direction of the own vehicle with respect to the travel lane when the own vehicle is located at the lane center side at least with respect to the lane edge reference. With
8. The steering control device according to claim 1, wherein the steering control unit corrects a steering amount of the steered wheel with respect to steering of the steering wheel according to a steering correction amount and a control amount for angle deviation. The vehicle steering control device described in 1.   A steering control method for a vehicle, characterized in that as the own vehicle approaches at least one traveling lane edge side, a steering reaction force against steering by a driver toward the traveling lane edge side is controlled more heavily.

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