JP6074976B2 - Lane maintenance support device - Google Patents

Description

  The present invention relates to a lane keeping assist device.

  Patent Document 1 below discloses a lane keeping assist device that increases the assist torque generated by the motor on the steering shaft as the lateral deviation from the center position of the lane increases. In this lane keeping assist device, the assist torque is reduced when the lateral deviation amount is reduced by the driver's steering.

JP 2006-264623 A

However, in the above prior art, the assist torque is reduced after the lateral deviation amount is reduced. Therefore, when the driver loosens the steering force when the strong assist torque is applied, the steering wheel suddenly Will cause the driver to feel uncomfortable. Further, since the vehicle behavior changes suddenly due to a sudden rotation of the steering wheel, the driver may feel uncomfortable.
The present invention pays attention to the above problem, and an object of the present invention is to provide a lane keeping assist device that suppresses the driver's uncomfortable feeling when the driver loosens the steering force during the lane keeping assist control. .

To achieve the above object, the present invention additionally calculates a reaction force command value corresponding to the lateral displacement of the vehicle with respect to the traffic lane, controls the steering reaction force actuator in accordance with the additional reaction force command value, additional only when the direction of the reaction force command value and the direction of the steering in the same direction, and so as to calculate a correction value for reducing-added reaction force command value.

  Therefore, in the present invention, it is possible to suppress the driver's uncomfortable feeling when the driver relaxes the steering force during the lane keeping assist control.

1 is an overall system diagram of a steering mechanism according to a first embodiment. 3 is a flowchart illustrating a flow of control performed in the lane keeping support controller according to the first embodiment. 4 is a graph showing a right deviation lateral displacement deviation of Example 1. 4 is a graph showing a left deviation lateral displacement deviation of Example 1. 6 is a map showing a setting of a decrease gain according to the lateral displacement of the first embodiment. 6 is a map showing a setting of a correction gain according to an additional reaction force torque command value of the first embodiment. 6 is a map showing a setting of a correction gain according to a yaw angle according to the first embodiment. 6 is a map showing a setting of a correction gain according to the curvature of the first embodiment. 6 is a map showing a setting of a correction gain according to the vehicle speed of the first embodiment. It is a whole system diagram of the steering mechanism of Example 2. FIG. 6 is an overall system diagram of a steering mechanism according to a third embodiment. The block diagram of the lane maintenance assistance controller of Example 3 is shown. The block diagram of the lane maintenance assistance controller of Example 3 is shown. 10 is a time chart of Example 3. It is a graph which shows the relationship between the steering force of the steering wheel by the driver of Example 3, and the lateral acceleration of the own vehicle. 10 is a time chart of Example 3. It is a whole system figure of the steering mechanism of other examples.

[Example 1]
[overall structure]
FIG. 1 is an overall system diagram of the steering mechanism. The steering mechanism according to the first embodiment includes a steering wheel 1 to which a steering force is input by a driver, a steering shaft 2 connected to the steering wheel 1, a pinion 3 connected to the tip of the steering shaft 2, and a rack that meshes with the pinion 3. 4, a steering motor 6 that is connected to the rack 4 via a pinion 5 to give a steering torque, a tie rod 7 that is connected to both ends of the rack 4, and a steered wheel 8 that is attached to the tie rod 7. Have.

  As a control system of the steering mechanism, a steering angle sensor 9 that detects the steering angle θh of the steering wheel 1, a vehicle speed sensor 10 that detects the vehicle speed V of the host vehicle, a camera 11 that captures the outside of the vehicle, and a steering motor 6 A steering motor torque sensor 12 for detecting output torque, a lane keeping assist controller 13 for controlling an additional reaction force torque to be added to a steering reaction force torque acting on the steering wheel 1 so that the host vehicle maintains a running lane, And a steering controller 14 for controlling the steered motor 6.

  The main function of the steered motor 6 is to provide steering assistance that reduces the steering force of the driver by applying torque in the same direction as the steering force input to the steering wheel 1 by the driver. In the first embodiment, in addition to this function, when the host vehicle is about to protrude from the traveling lane, torque is output so that the host vehicle returns to the center of the traveling lane regardless of the direction of the steering force of the driver. That is, the magnitude of the reaction force acting on the steering wheel 1 by the steering motor 6 can be made variable.

The camera 11 has an image processing function, and the travel lane width Wlane, the yaw angle δ with respect to the travel lane of the host vehicle, the lateral displacement X of the host vehicle from the center of the travel lane, the travel lane The curvature ρ is detected. The lateral displacement X is detected as a positive value on the right side and a negative value on the left side with respect to the center of the lane.
The lane keeping support controller 13 includes a travel lane width Wlane, yaw angle δ, lateral displacement X, curvature ρ detected by the camera 11, a vehicle speed V detected by the vehicle speed sensor 10 via the steering controller 14, and a steering motor torque sensor. The turning motor torque Tt detected by 12 is input. Based on these input values, the additional reaction force torque command value N * is calculated.

  The additional reaction force torque command value N * is a reaction force that acts on the steering wheel 1 to urge the driver to steer in a direction to return the vehicle to the center of the traveling lane when the own vehicle is about to protrude from the traveling lane. Show. Based on this additional reaction force torque command value N *, the reaction force acting on the steering wheel 1 is controlled by the turning motor 6. Actually, the additional reaction force torque command value N * calculated by the lane keeping support controller 13 is input to the steering controller 14 and the steering motor 14 is controlled by the steering controller 14.

  The steering controller 14 includes the vehicle speed V detected by the vehicle speed sensor 10, the steering motor torque Tt detected by the steering motor torque sensor 12, the yaw angle δ detected by the camera 11 via the lane keeping assist controller, and the lateral displacement X. The curvature ρ and the additional reaction force torque command value N * are input.

[Lane maintenance support control processing]
FIG. 2 is a flowchart showing a flow of control performed in the lane keeping support controller 13.
In step S1, each sensor value is read and the process proceeds to step S2.

In step S2, the right deviation lateral displacement deviation ΔXR is calculated, and the process proceeds to step S3. The right deviation lateral displacement deviation ΔXR indicates the deviation amount of the host vehicle with respect to the lane marker on the right side of the traveling lane. The right deviation lateral displacement deviation ΔXR is obtained by the following equation (1).
ΔXR = X-XR * (However, ΔXR ≧ 0) ... (1)
Here, XR * is a lateral displacement threshold value set for the deviation to the right side of the lane, and is obtained by the following equation (2).
XR * = (Wlane / 2)-(Wcar / 2)-Xoffset… (2)
Here, Wcar is the vehicle width of the host vehicle, and Xofset is a margin for the lane marker position.

  FIG. 3 is a graph showing the right deviation lateral displacement deviation ΔXR. As shown in FIG. 3, when the lateral displacement X is equal to or less than the lateral displacement threshold XR *, the right deviation lateral displacement deviation ΔXR is 0 (zero), but when the lateral displacement X exceeds the lateral displacement threshold XR *, the lateral displacement X is The larger the deviation is, the larger the right deviation lateral displacement deviation ΔXR is.

In step S3, a left deviation lateral displacement deviation ΔXL is calculated, and the process proceeds to step S4. The left deviation lateral displacement deviation ΔXL indicates the deviation amount of the host vehicle with respect to the lane marker on the left side of the traveling lane. The left deviation lateral displacement deviation ΔXL is obtained by the following equation (3).
ΔXL = X-XL * (However, ΔXL ≦ 0)… (3)
Here, XL * is a lateral displacement threshold value set for the deviation to the right side of the lane, and is obtained by the following equation (4).
XL * =-{(Wlane / 2)-(Wcar / 2)-Xoffset}… (4)

  FIG. 4 is a graph showing the left deviation lateral displacement deviation ΔXL. As shown in FIG. 4, when the lateral displacement X is greater than or equal to the lateral displacement threshold XL *, the right deviation lateral displacement deviation ΔXL is 0 (zero), but when the lateral displacement X falls below the lateral displacement threshold XL *, the lateral displacement X is The left deviation lateral displacement deviation ΔXL is set to be smaller as the distance is smaller.

In step S4, an additional reaction force torque command value N * is calculated, and the process proceeds to step S5. The additional reaction force torque command value N * is obtained from the right departure reaction force torque command value NR * and the left departure reaction force torque command value NL *. The right departure reaction force torque command value NR * and the left departure reaction force torque command value NL * are obtained by the following equations (5) and (6).
NR * = (Kc_L1 × Lv_L1 × ΔXR)… (5)
NL * = (Kc_L1 × Lv_L1 × ΔXL)… (6)
Here, Kc_L1 is a feedback gain determined by vehicle specifications, and Lv_L1 is a correction gain according to the vehicle speed V.
The additional reaction force torque command value N * is obtained by the following equation (7).
N * = NR * + NL *… (7)

  When the host vehicle is traveling inside the travel lane, ΔXR = ΔXL = 0, and the additional reaction force torque command value N * = 0. When the host vehicle deviates from the driving lane to the right side, ΔXR> 0 and ΔXL = 0, and the additional reaction force torque N *> 0. When the host vehicle deviates from the driving lane to the left side, ΔXR = 0 and ΔXL <0 and the additional reaction force torque N * <0. When the additional reaction torque N *> 0, a reaction force is generated to rotate the steering wheel 1 to the left. When the additional reaction torque N * <0, the steering wheel 1 is rotated to the right. Reaction force is generated.

  In step S5, it is determined whether or not the direction of the additional reaction force torque command value N * and the steering direction are the same direction, the process proceeds to step S6 if the direction is the same direction, and the process proceeds to step S12 if the direction is the other direction. To do.

  In step S6, a decrease gain α corresponding to the lateral displacement X is calculated. FIG. 5 is a map showing the setting of the decrease gain α according to the lateral displacement X. As shown in FIG. 5, the reduction gain α is set to increase as the lateral displacement X increases.

  In step S7, a correction gain β1 corresponding to the additional reaction force torque command value N * is calculated, and the process proceeds to step S8. FIG. 6 is a map showing the setting of the correction gain β1 according to the additional reaction force torque command value N *. As shown in FIG. 6, the correction gain β1 is set to be larger than 1 as the magnitude of the additional reaction force torque command value N * increases.

  In step S8, a correction gain β2 corresponding to the yaw angle δ is calculated, and the process proceeds to step S9. FIG. 7 is a map showing the setting of the correction gain β2 according to the yaw angle δ. As shown in FIG. 7, the correction gain β2 is set to be larger than 1 as the yaw angle δ increases.

  In step S9, a correction gain β3 corresponding to the road surface curvature ρ is calculated, and the process proceeds to step S10. FIG. 8 is a map showing the setting of the correction gain β3 according to the curvature ρ. As shown in FIG. 8, the correction gain β3 is set to be smaller than 1 as the curvature ρ increases.

  In step S10, a correction gain β4 corresponding to the vehicle speed V of the host vehicle is calculated, and the process proceeds to step S11. FIG. 9 is a map showing the setting of the correction gain β4 according to the vehicle speed V. As shown in FIG. 9, the correction gain β3 is set to be larger than 1 as the vehicle speed V increases.

In step S11, an additional reaction force torque command value reduction process is performed according to the reduction gain α, the correction gain β, and the steering angular velocity θh ′. The steering angular velocity θh ′ can be obtained from the steering angle θh detected by the steering angle sensor 9. The correction gain β is obtained by the following equation (8).
β = β1 × β2 × β3 × β4… (8)
Further, the additional reaction force torque N * after the additional reaction force torque command value reduction process is obtained by the following equation (9).
N * = N *-(α × β × θh ')… (9)
In step S12, the steered motor 6 is controlled based on the additional reaction force torque N *.

[Lane maintenance support control operation]
In the flowchart of FIG. 2, the process proceeds from step S1 to step S2 to step S4, and an additional reaction force torque command value N * is calculated. When the host vehicle is traveling inside the travel lane, ΔXR = ΔXL = 0, and the additional reaction force torque command value N * = 0. For this reason, the steering of the driver is not hindered. On the other hand, when the own vehicle deviates from the driving lane to the right side, ΔXR> 0 and ΔXL = 0, and when the own vehicle deviates to the left side, ΔXR = 0 and ΔXL <0. That is, as the deviation amount increases, the magnitude of the additional reaction force torque command value N * increases, and the additional reaction force torque is generated so as to encourage steering in a direction to return the host vehicle to the traveling lane.

When the direction of the additional reaction force torque command value N * and the steering direction are the same, the process proceeds from step S5 → step S6 → step S7 → step S8 → step S9 → step S10 → step S11 → step S12.
When the direction of the additional reaction force torque command value N * and the steering direction are the same direction, a correction gain β for correcting the decrease gain α calculated in step S6 is obtained. The correction gain β is corrected so that the amount of decrease in the additional reaction force torque command value N * increases as the correction gain β exceeds 1.

When the direction of the additional reaction force torque command value N * is different from the steering direction, the process proceeds from step S5 to step S12.
When the direction of the additional reaction force torque command value N * is different from the steering direction, the additional reaction force torque command value reduction process is not performed.

[Action]
Conventionally, when the lateral displacement of the host vehicle with respect to the traveling lane increases, there is a motor that applies a torque to the steering shaft connected to the steering wheel in a direction in which the host vehicle returns to the traveling lane. At this time, as the lateral displacement of the host vehicle decreases, the torque applied by the motor is controlled to decrease. However, with this control, if the driver loosens the steering force when a strong torque is applied, the steering wheel may suddenly rotate, and the driver may feel uncomfortable. Further, since the vehicle behavior changes suddenly due to a sudden rotation of the steering wheel, the driver may feel uncomfortable.

  Therefore, in the first embodiment, when the direction of the additional reaction force torque command value N * is the same as the steering direction, the amount of decrease in the additional reaction force torque command value N * is increased. When the direction of the additional reaction force torque command value N * is the same as the steering direction, the steering direction of the driver is a direction that avoids the departure of the traveling lane. By reducing the additional reaction force torque command value N * in the same direction, it is possible to suppress a sense of discomfort during steering.

  When the steering speed θh ′ is high, the driver may be trying to avoid emergency. In that case, if the additional reaction force torque N is large, the steering may be hindered. Therefore, in the first embodiment, the amount of decrease in the additional reaction force torque command value N * increases as the steering speed θh ′ increases. Therefore, it is possible to suppress the inhibition of steering during emergency avoidance.

  Also, when the lateral displacement X is large, there is a possibility that the lane is deviated by the driver's intention such as changing the lane. In that case, if the additional reaction force torque N is large, the steering may be hindered. Therefore, in Example 1, the amount of decrease in the additional reaction force torque command value N * is increased as the lateral displacement X is increased. Therefore, it is possible to suppress the inhibition of steering when the driver departs from the lane.

  Further, when the additional reaction force torque command value N * is large, if the decrease gain α is not large, the ratio of the decrease amount to the additional reaction force torque command value N * is small, and the uncomfortable feeling during steering cannot be sufficiently suppressed. Therefore, in the first embodiment, the amount of decrease in the additional reaction force torque command value N * increases as the additional reaction force torque command value N * increases. Therefore, the uncomfortable feeling at the time of steering can be suppressed.

  Further, when the yaw angle δ of the host vehicle with respect to the traveling lane is large, there is a possibility that the lane is deviated by the driver's intention such as changing the lane. In that case, if the additional reaction force torque N is large, the steering may be hindered. Therefore, in the first embodiment, the amount of decrease in the additional reaction force torque command value N * increases as the yaw angle δ increases. Therefore, it is possible to suppress the inhibition of steering when the driver departs from the lane.

  Further, when the curvature ρ of the traveling lane is large, it is easy to deviate from the traveling lane. Therefore, in Example 1, the amount of decrease in the additional reaction force torque command value N * is reduced as the curvature ρ increases. Therefore, it is possible to travel with the lane departure suppressed even in a scene that easily deviates from the traveling lane.

  Further, if the steering amount increases when the vehicle speed V of the host vehicle is high, the vehicle behavior may become unstable. Therefore, the amount of decrease in the additional reaction force torque command value N * increases as the vehicle speed V increases. Therefore, instability of vehicle behavior can be suppressed.

[effect]
The effects of Example 1 are listed below.
(1) A steering wheel 1 (steering means) to which a steering force is input by a driver, a steering angle sensor 9 that detects a steering angle θh of the steering wheel 1, and a steering motor that generates a steering reaction force to the steering wheel 1 6 (steering reaction force actuator), a camera 11 (lateral displacement detecting means) that detects the lateral displacement X of the host vehicle with respect to the traveling lane, and a steering direction and a steering speed are obtained from the steering angle θh. The steering reaction force torque generated by the rudder motor 6 is calculated, and the steering actuator is controlled using the steering reaction force torque as an additional reaction force torque command value N *. The direction of the additional reaction force torque command value N * and the steering direction Lane maintenance support controller 13 (steering direction detection means, steering speed detection means, additional reaction force control means, correction value calculation means) for calculating a correction value for decreasing the additional reaction force torque command value N * based on the comparison of The lane keeping support controller 13 sets the magnitude of the correction value according to the lateral displacement X and the steering speed θh ′.
Therefore, the uncomfortable feeling during steering due to the sudden rotation of the steering wheel 1 can be suppressed.

(2) The lane keeping support controller 13 sets the magnitude of the correction value according to the magnitude of the additional reaction force torque command value N *.
Therefore, it is possible to ensure an appropriate ratio of the reduction amount with respect to the magnitude of the additional reaction force torque command value N *.

(3) The camera 11 (yaw angle detection means) detects the yaw angle δ of the host vehicle relative to the traveling lane, and the lane keeping support controller 13 sets the magnitude of the correction value according to the yaw angle δ. .
Therefore, when there is a possibility that the yaw angle δ is large and the driver is deviating from the lane due to the driver's intention, such as changing the lane, the amount of decrease in the additional reaction force torque command value N * is increased, and Inhibition can be suppressed.

(4) The camera 11 (curvature detecting means) detects the curvature ρ of the traveling lane, and the lane keeping support controller 13 sets the magnitude of the correction value according to the curvature ρ of the traveling lane.
Therefore, even in a scene where the curvature ρ is large and easily deviates from the travel lane, it is possible to travel while suppressing the lane departure.

(5) The vehicle speed sensor 10 (vehicle speed detection means) that detects the vehicle speed V of the host vehicle is provided, and the lane keeping support controller 13 sets the magnitude of the correction value according to the vehicle speed V.
Therefore, instability of vehicle behavior can be suppressed.

[Example 2]
FIG. 10 is an overall system diagram of the steering mechanism. The steering mechanism of the second embodiment is a so-called steer-by-wire system in which transmission of force between the steering wheel 1 and the steered wheels 8 is cut off.

  The steering mechanism of the second embodiment includes a steering wheel 1 to which a steering force is input by a driver, a steering shaft 2 connected to the steering wheel 1, a pinion shaft 20 cut from the steering shaft 2, and a tip of the pinion shaft 20. It has a connected pinion 3, a rack 4 meshing with the pinion 3, a tie rod 7 connected to both ends of the rack 4, and a steering wheel 8 attached to the tie rod 7.

  A mechanical backup 24 is provided between the steering shaft 2 and the pinion shaft 20. The mechanical backup 24 normally cuts off the torque transmission between the steering shaft 2 and the pinion shaft 20, but enables the torque transmission between the steering shaft 2 and the pinion shaft 20 when the system is abnormal. Yes.

  The steering shaft 2 is provided with a reaction force motor 29, and the reaction force motor 29 generates a steering reaction force on the steering wheel 1. The pinion shaft 20 is provided with a steered motor 30, and the steered wheel 8 is steered by the steered motor 30.

  Further, as a braking device, it has a brake disc 22 and a wheel cylinder 23 provided on the steering wheel 8 and the rear wheel 21, and a brake hydraulic pressure control unit 33 for controlling the brake hydraulic pressure supplied to the wheel cylinder 23. .

  Further, as a control system, a steering angle sensor 9 that detects the steering angle θh of the steering wheel 1, a steering torque sensor 25 that detects the steering torque input to the steering wheel by the driver, and a pinion angle that detects the rotation angle of the pinion 3 A sensor 27, a turning torque sensor 26 for detecting the torque acting on the pinion shaft 20, a reaction force motor rotation angle sensor 31 for detecting the rotation angle of the reaction force motor 29, and a rotation angle of the turning motor 30 are detected. Steering motor rotation angle sensor 32, axial force sensor 28 for detecting the axial force acting on the tie rod 7, vehicle speed sensor 10 for detecting the vehicle speed V of the host vehicle, camera 11 for photographing the outside of the vehicle, and the host vehicle traveling An additional reaction force torque added to the steering reaction force torque acting on the steering wheel 1 to maintain the lane, a lane keeping support controller 13 for controlling the braking force of each wheel, and a reaction force mode And a steering controller 14 for controlling the motor 29 and the steering motor 30.

The camera 11 has an image processing function, and detects a travel lane width Wlane, a yaw angle δ with respect to the travel lane, a lateral displacement X from the center of the travel lane, and a curvature ρ of the travel lane from an image taken in front of the host vehicle. The lateral displacement X is detected as a positive value on the right side and a negative value on the left side with respect to the center of the lane.
The lane keeping support controller 13 inputs the travel lane width Wlane, yaw angle δ, lateral displacement X, curvature ρ detected by the camera 11 and the vehicle speed V detected by the vehicle speed sensor 10 via the steering controller 14. Based on these input values, the additional reaction force torque command value N * and the target brake fluid pressure of each wheel are calculated.

The additional reaction force torque command value N * is a reaction force that acts on the steering wheel 1 to urge the driver to steer in a direction to return the vehicle to the center of the traveling lane when the own vehicle is about to protrude from the traveling lane. Show. Based on this additional reaction force torque command value N *, the reaction force applied to the steering wheel 1 by the reaction force motor 29 is controlled. Actually, the additional reaction force torque command value N * calculated by the lane keeping support controller 13 is input to the steering controller 14, and the reaction controller 29 is controlled by the steering controller 14.

  The steering controller 14 includes a vehicle speed V detected by the vehicle speed sensor 10, a steering angle θh detected by the steering angle sensor 9, a steering torque input to the steering wheel by the driver detected by the steering torque sensor 25, and a steering torque sensor. The torque acting on the pinion shaft 20 detected by 26, the rotation angle of the pinion 3 detected by the pinion angle sensor 27, the rotation angle of the reaction force motor 29 detected by the reaction force motor rotation angle sensor 31, and the turning motor rotation The rotation angle of the steering motor 30 detected by the angle sensor 32, the axial force acting on the tie rod 7 detected by the axial force sensor 28, the rotation angle of the reaction force motor 29 detected by the reaction force motor rotation angle sensor 31, The yaw angle δ, lateral displacement X, curvature ρ, and additional reaction force torque command value N * detected by the camera 11 are input via the lane keeping support controller. The axial force acting on the tie rod 7 changes according to the road surface reaction force acting on the steering wheel 8, and the axial force may be regarded as the road surface reaction force.

  The steering controller 14 sets a target turning angle of the steered wheels 8 according to the steering angle θh and the steering torque input to the steering wheel 1, and controls the steering motor 30 according to the target turning angle. Further, the steering controller 14 sets a target steering reaction torque to be applied to the steering wheel 1 in accordance with the axial force input to the tie rod 7, and controls the reaction force motor 29 in accordance with the target steering reaction torque.

  The reaction force motor 29 applies a steering reaction force to the steering wheel 1 according to the target steering reaction force torque calculated by the steering controller 14 and the additional reaction force torque command value N * calculated by the lane keeping assist controller 13. It will be. In the second embodiment, as in the first embodiment, when the direction of the additional reaction force torque command value N * is the same as the steering direction, the additional reaction force torque command value N * is reduced. Is performed only for the additional reaction force torque command value N * and not for the target steering reaction torque.

[effect]
The effect of Example 2 will be described.
(6) The steered wheel 8 (steered wheel) from which the transmission of force from the steering wheel 1 is cut off, and the axial force sensor 28 (road surface reaction force detecting means) that detects the road surface reaction force input to the steered wheel 8 The steering controller 14 calculates a target steering reaction force torque generated by the reaction force motor 29 (steering reaction force actuator) according to the road surface reaction force, and uses the target steering reaction force torque as a reaction force command value. The motor 29 was controlled.

  Therefore, the reduction process is performed only on the additional reaction force torque command value N * calculated by the lane keeping assist controller 13, and the reduction process is not performed on the target steering reaction torque calculated by the steering controller 14. Therefore, the reduction process does not affect the steering reaction force torque according to the road surface reaction force, and the driver can feel the steering reaction force according to the road surface reaction force, so that the steering feeling can be improved. .

Example 3
FIG. 11 is an overall system diagram of the steering mechanism. The steering mechanism of the third embodiment is a so-called steer-by-wire system in which transmission of force between the steering wheel 1 and the steered wheels 8 is cut off.

  The steering mechanism according to the third embodiment includes a steering wheel 1 to which a steering force is input by a driver, a steering shaft 2 connected to the steering wheel 1, a reaction force motor 29 that generates a steering reaction force on the steering shaft 2, and a steering wheel. A steering motor 30 that steers the steered wheels 8 according to the steering force of the driver input to 1, a pinion 5 provided on the rotating shaft of the steering motor 30, a rack 4 that meshes with the pinion 5, and a rack A tie rod 7 connected to both ends of 4 and a steering wheel 8 attached to the tie rod 7 are provided.

  Further, as a control system, a steering angle sensor 9 that detects the steering angle θh of the steering wheel 1, a steering torque sensor 25 that detects the steering torque input to the steering wheel 1 by the driver, and a pinion that detects the rotation angle of the pinion 5 Angle sensor 27, reaction force motor torque sensor 34 for detecting torque of reaction force motor 29, steering motor torque sensor 35 for detecting torque of steering motor 30, and vehicle speed sensor 10 for detecting vehicle speed V of the host vehicle And a camera 11 for photographing the outside of the vehicle, a blinker switch 36 for detecting that the blinker is operated, and an additional reaction applied to the steering reaction torque that acts on the steering wheel 1 so that the host vehicle maintains the traveling lane. A lane keeping support controller 13 that controls the force torque and braking force of each wheel, and a steering controller 14 that controls the reaction force motor 29 and the steering motor 30 are provided. To have.

The camera 11 has an image processing function, and detects a travel lane width Wlane, a yaw angle δ with respect to the travel lane, a lateral displacement X from the center of the travel lane, and a curvature ρ of the travel lane from an image taken in front of the host vehicle. The lateral displacement X is detected as a positive value on the right side and a negative value on the left side with respect to the center of the lane.
The lane keeping support controller 13 obtains information on the travel lane width Wlane, yaw angle δ, lateral displacement X, curvature ρ detected by the camera 11, the vehicle speed V detected by the vehicle speed sensor 10 via the steering controller 14, and the blinker switch 36 information. input. Based on these input values, the additional reaction force command current i is calculated.

  The additional reaction force command current i is an additional reaction force torque N that acts on the steering wheel 1 to urge the driver to steer the vehicle back to the center of the driving lane when the own vehicle is about to protrude from the driving lane. Is a command current for generating the force by the reaction force motor 29. The reaction force motor 29 is driven by the additional reaction force command current i to control the reaction force acting on the steering wheel 1. Actually, the additional reaction force command current i calculated by the lane keeping support controller 13 is input to the steering controller 14, and the steering reaction force command current for realizing the target steering reaction torque according to the road surface reaction force by the steering controller 14 is realized. Is added with the additional reaction force command current i to control the steered motor 30.

  The steering controller 14 controls the steering wheel by the vehicle speed V detected by the vehicle speed sensor 10, ON / OFF of the winker from the winker switch 36, the steering angle θh detected by the steering angle sensor 9, and the driver detected by the steering torque sensor 25. The input steering torque, the torque of the reaction motor 29 detected by the reaction force motor torque sensor 34, the torque of the steering motor 30 detected by the steering motor torque sensor 35, and the pinion 5 detected by the pinion angle sensor 27 And the yaw angle δ, lateral displacement X, and curvature ρ detected by the camera 11 via the lane keeping support controller.

  The steering controller 14 sets a target turning angle of the steered wheels 8 according to the steering angle θh and the steering torque input to the steering wheel 1, and controls the steering motor 30 according to the target turning angle. Further, the steering controller 14 sets a target steering reaction torque to be applied to the steering wheel 1 in accordance with the torque of the reaction force motor 29, and controls the reaction force motor 29 in accordance with the target steering reaction torque.

  The reaction force motor 29 applies a steering reaction force to the steering wheel 1 according to the steering reaction force command current calculated by the steering controller 14 and the additional reaction force command current i calculated by the lane keeping support controller 13. Become.

[Calculation of additional reaction force torque]
FIG. 12 is a block diagram of the lane keeping support controller 13. FIG. 12 shows a block diagram of a portion for obtaining the additional reaction force torque command value N * from the lateral displacement X and the yaw angle δ.

  The lane keeping support controller 13 includes a lateral displacement gain map 13a, a yaw angle gain map 13b, a road surface condition gain 13c, multipliers 13d and 13e, a select high calculator 13f, a rate limiter 13g, and an upper / lower limit limiter 13h.

  The lateral displacement gain map 13a obtains the additional reaction force torque N corresponding to the lateral displacement X. The lateral displacement gain map 13a is set so that the additional reaction force torque N increases as the lateral displacement X increases. FIG. 12 shows a map when the lateral displacement X is positive. However, when the lateral displacement X is negative, only the additional reaction force torque N is negative, and the magnitude of the absolute value lateral displacement X is positive. The same value as when.

  The yaw angle gain map 13b calculates an additional reaction force torque N corresponding to the yaw angle δ with respect to the travel lane of the host vehicle. The yaw angle gain map 13b is set so that the additional reaction force torque N increases as the yaw angle δ increases. FIG. 12 shows a map when the yaw angle δ is positive, but when the yaw angle δ is negative, the additional reaction force torque N is only negative, and the magnitude of the lateral displacement X is positive. The same value as when.

  The road surface condition gain 13c sets a road surface state gain Ge according to the curvature ρ of the traveling lane, the vehicle speed V, and the turn signal ON / OFF. The road surface condition gain Ge is set so that the gain is increased to increase the additional reaction force torque N to suppress lane departure when the curvature of the traveling lane is large or the vehicle speed V is large, and when the turn signal switch is ON. Assuming that the lane has been changed, the gain is reduced to reduce the additional reaction force torque N so that the lane can be easily changed.

The multiplier 13d multiplies the additional reaction force torque N obtained from the lateral displacement X by the road surface condition gain Ge. The multiplication unit 13e multiplies the additional reaction force torque N obtained from the yaw angle δ by the road surface condition gain Ge.
The select high computing unit 13f has a value obtained by multiplying the additional reaction force torque N obtained from the lateral displacement X by the road surface condition gain Ge, and a value obtained by multiplying the additional reaction force torque N obtained from the yaw angle δ by the road surface condition gain Ge. Of these, the larger value is selected and output. Here, absolute values are compared.

When the change in the additional reaction force torque N is greater than a predetermined value, the rate limiter 13g calculates and outputs the additional reaction force torque N so that the change in the additional reaction force torque N is within a predetermined value.
The upper / lower limiter 13h calculates the additional reaction force torque N so that the additional reaction force torque N is within a predetermined value, and outputs the calculated additional reaction force torque N as the additional reaction force torque command value N *.

[Correction of additional reaction force torque]
FIG. 13 is a block diagram of the lane keeping support controller 13. FIG. 13 shows a block diagram of a portion for correcting the additional reaction force command current i calculated so that the reaction force motor 29 outputs the additional reaction force torque command value N *. FIG. 13A shows a block diagram when the additional reaction force torque command value N * and the steering angular velocity θh ′ are in the same direction, and FIG. 13B shows the additional reaction force torque command value N * and the steering angular velocity θh. The block diagram when 'and the reverse direction is shown.

  When the additional reaction force torque command value N * and the steering angular velocity θh ′ are in the same direction, the value obtained after correction for reducing the additional reaction force command current i as shown in FIG. When the additional reaction force torque command value N * and the steering angular velocity θh ′ are in opposite directions, the additional reaction force command current i is used as it is as the final additional reaction force command as shown in FIG. Output as current i '.

  The lane keeping support controller 13 includes a differentiator 13i, a lateral displacement correction map 13j, an additional reaction force command current correction map 13k, a yaw angle correction map 13l, a curvature correction map 13m, multipliers 13n to 13q, and a subtractor 13r. Yes.

The differentiator 13i differentiates the steering angle θh and outputs a steering angular velocity θh ′.
The lateral displacement correction map 13j calculates a correction gain γ1 set according to the lateral displacement X. As shown in the frame of the lateral displacement correction map 13j in FIG. 13, the lateral displacement correction map is set so that the correction gain γ1 increases as the size of the lateral displacement X increases.

  The additional reaction force command current correction map 13k calculates a correction gain γ2 set according to the additional reaction force command current i. As shown in the frame of the additional reaction force command current correction map 13k in FIG. 13, the additional reaction force command current correction map is set so that the correction gain γ2 becomes larger than 1 as the magnitude of the additional reaction force command current i * increases. Is set.

  The yaw angle correction map 13l calculates a correction gain γ3 set according to the yaw angle δ with respect to the travel lane of the host vehicle. The yaw angle correction map is set so that the correction gain γ3 becomes larger as 1 as the yaw angle δ increases as shown in the frame of the yaw angle correction map 13l in FIG.

  The curvature correction map 13m calculates a correction gain γ4 set according to the curvature ρ of the traveling lane. As shown in the frame of the curvature correction map 13m in FIG. 13, the curvature correction map is set so that the correction gain γ4 becomes smaller than 1 as the magnitude of the curvature ρ increases.

  The multipliers 13n to 13q apply correction gains γ1, γ2, γ3, and γ4 to the steering angular velocity θ ′. The subtractor 13r outputs a value obtained by subtracting a value obtained by multiplying the steering angular velocity θ ′ by the correction gain γ1, γ2, γ3, γ4 from the additional reaction force command current i as a final additional reaction force command current i ′.

[Action]
FIG. 14A is a diagram showing a state from when the own vehicle tries to depart from the lane to the right and returns to the center of the lane again. FIG. 14B is a time chart from when the host vehicle tries to depart from the lane to the right until it returns to the lane center again. In FIG. 14B, the solid line shows a time chart when the process of reducing the additional reaction force command current i is performed when the direction of the additional reaction force torque command value N * and the steering angular velocity θh ′ are the same direction. The dotted line shows a time chart when the reduction process is not performed.

  As shown in FIG. 14B, when the steering direction (direction of the steering angular velocity θh ′) is opposite to the direction of the additional reaction force torque (the direction of the additional reaction force torque command value N *), the additional reaction force Since the reduction process of the command current i is not performed, an additional reaction force torque acts in a direction to return the host vehicle to the center of the lane, thereby suppressing lane departure of the host vehicle.

  Further, when the steering direction (the direction of the steering angular velocity θh ′) is the same as the direction of the additional reaction force torque (the direction of the additional reaction force torque command value N *), the additional reaction force command current i is not reduced. Sometimes (dotted line), the steering torque by the driver and the additional reaction force torque are combined to make a sudden steering, and the vehicle behavior becomes unstable.

  On the other hand, when the direction of steering (the direction of the steering angular velocity θh ′) is the same as the direction of the additional reaction force torque (the direction of the additional reaction force torque command value N *), the additional reaction force command current i is reduced. When (solid line), the additional reaction force torque decreases, the steering can be smoothed, and the vehicle behavior can be stabilized.

  FIG. 15 is a graph showing the relationship between the steering force of the steering wheel 1 by the driver and the lateral acceleration of the host vehicle. The thin solid line shows the relationship when the additional reaction force torque N is not applied. The thick solid line shows the process of reducing the additional reaction force command current i when the steering direction (the direction of the steering angular velocity θh ′) is the same as the direction of the additional reaction force torque (the direction of the additional reaction force torque command value N *). The relationship when performed (Example 3) is shown. The dotted line indicates that the additional reaction force command current i is reduced when the direction of steering (the direction of the steering angular velocity θh ′) is the same as the direction of the additional reaction force torque (the direction of the additional reaction force torque command value N *). The relationship when there was no is shown (comparative example).

  When steering wheel 1 is steered in the lane departure direction (when the steering direction and the direction of the additional reaction force torque are opposite: points P0 → P1 → P2), both the example 3 and the comparative example are drivers. The steering force is added by the additional reaction force torque.

  When the steering wheel 1 starts to be steered toward the center of the lane (point P2 → P4 or point P2 → P5), the steering force in Example 3 is lower than the comparative example (the steering ratio is larger). ). The steering feeling can be improved for the driver when the steering control ratio is large.

  In addition, when steering the steering wheel 1 toward the center of the lane (point P4 → P0 or point P5 → P0), the lateral acceleration change with respect to the steering force change can be made smaller in the third embodiment than in the comparative example. The operation can be relaxed.

  FIG. 16A is a diagram illustrating a state in which the host vehicle is about to travel a curve. FIG. 16B is a time chart when the host vehicle travels along a curve. In FIG. 16B, the solid line is a time chart when correction is performed according to the curvature ρ of the traveling lane, and the dotted line is a time chart when correction is not performed according to the curvature ρ.

  While driving on a curve, the vehicle tends to deviate outside the curve, but the steering direction at that time is the lane center direction. Therefore, when the correction according to the curvature ρ is not performed, the additional reaction force torque N becomes small during curve traveling, and the lane departure cannot be sufficiently suppressed. Therefore, in the third embodiment, a correction gain γ4 set according to the curvature ρ of the traveling lane is calculated. The curvature correction map is set so that the correction gain γ4 becomes smaller than 1 as the curvature ρ in FIG. As a result, it is possible to prevent the additional reaction force torque from becoming too small during a curve run and to suppress lane departure.

[effect]
(7) The additional reaction force torque is calculated so that the host vehicle moves toward the center of the lane according to the lateral displacement X of the host vehicle with respect to the driving lane or the yaw angle δ with respect to the driving lane of the host vehicle, and the steering direction and the additional reaction force torque are obtained. When the direction is the same, the correction is made so that the additional reaction force torque is reduced.
As a result, when the steering wheel 1 is about to start steering from the lane departure direction to the lane center direction, the steering ratio can be increased and the steering feeling of the driver can be improved. In addition, the lateral acceleration change with respect to the steering force change when the steering wheel 1 is steered toward the center of the lane can be reduced, and the operation during the switchback can be made gradual.
(8) The magnitude of the correction gain that reduces the additional reaction force torque during curve driving has been reduced so that the additional reaction force torque does not become too small.
Thereby, the lane departure during curve driving can be suppressed.

[Other Examples]
The best mode for carrying out the present invention has been described with reference to the embodiments based on the drawings. However, the specific configuration of the present invention is not limited to the embodiments, and does not depart from the gist of the invention. Such design changes are included in the present invention.

For example, in the embodiment, by processing the image captured by the camera, the travel lane width Wlane, the yaw angle δ relative to the travel lane of the host vehicle, the lateral displacement X of the host vehicle from the center of the travel lane, the curvature ρ of the travel lane, etc. I was asking. This may be detected by a laser or the like, or may be detected based on the relationship between road information acquired in advance or received from the outside and the vehicle position obtained from the GPS.
In the first embodiment, the additional reaction force torque command value N * is obtained from the lateral displacement X. However, it may be obtained from the lateral displacement X and the yaw angle δ using the map shown in FIG.

1 Steering wheel (steering means)
6 Steering motor (steering reaction force actuator)
8 Steering wheel (steering wheel)
9 Steering angle sensor (steering direction detection means, steering speed detection means)
10 Vehicle speed sensor (vehicle speed detection means)
11 Camera (lateral displacement detection means, yaw angle detection means, curvature detection means)
13 Lane maintenance support controller (additional reaction force control means, correction value calculation means)
14 Steering controller (steering reaction force control means)
28 Axial force sensor (Road reaction force detection means)
29 Reaction force motor (steering reaction force actuator)

Claims (6)

Steering means to which a steering force is input by a driver;
Steered wheels to which force is transmitted from the steering means;
Steering direction detecting means for detecting the steering direction of the steering means;
Steering speed detection means for detecting the steering speed of the steering means;
A steering motor capable of generating torque for reducing the steering force of the driver ;
Lateral displacement detecting means for detecting the lateral displacement of the host vehicle relative to the traveling lane;
A command value of an additional reaction force, which is a torque for prompting steering in a direction to return the host vehicle to the traveling lane, is calculated according to the lateral displacement , and the steering motor is controlled according to the additional reaction force command value. Additional reaction force control means;
Correction value calculation means for calculating a correction value for decreasing the additional reaction force command value only when the direction of the additional reaction force command value and the direction of the steering are the same direction;
With
The lane keeping assist device, wherein the correction value calculating means increases the correction value as the lateral displacement or the steering speed increases. Steering means to which a steering force is input by a driver;
Steered wheels from which the transmission of force from the steering means is cut off,
Steering direction detecting means for detecting the steering direction of the steering means;
Steering speed detection means for detecting the steering speed of the steering means;
A steering reaction force actuator for generating a steering reaction force acting on the steering means;
Road surface reaction force detecting means for detecting road surface reaction force input to the steered wheels;
Lateral displacement detecting means for detecting the lateral displacement of the host vehicle relative to the traveling lane;
The steering in accordance with the road surface reaction force reaction force command value, and calculates a command value of the additional reaction force to be added to the steering reaction force in the direction to return to the running lane of the host vehicle in response to the lateral displacement, the additional reaction Steering reaction force control means for controlling the steering reaction force actuator in accordance with a force command value and the steering reaction force command value;
Correction value calculation means for calculating a correction value for decreasing the additional reaction force command value only when the direction of the additional reaction force command value and the direction of the steering are the same direction;
With
The lane keeping assist device, wherein the correction value calculating means increases the correction value as the lateral displacement or the steering speed increases. In the lane keeping assist device according to claim 1 or 2,
The lane keeping assist device, wherein the correction value calculation means increases the correction value as the additional reaction force command value increases. The lane keeping assist device according to any one of claims 1 to 3,
Yaw angle detection means for detecting the yaw angle of the host vehicle with respect to the travel lane,
The lane keeping assist device, wherein the correction value calculating means increases the correction value as the yaw angle increases. The lane keeping assist device according to any one of claims 1 to 4,
Curvature detection means for detecting the curvature of the travel lane,
The lane keeping assist device according to claim 1, wherein the correction value calculating means decreases the correction value as the curvature of the travel lane increases. In the lane keeping assist device according to any one of claims 1 to 5,
Vehicle speed detecting means for detecting the vehicle speed of the host vehicle,
The lane keeping assist device, wherein the correction value calculating means increases the correction value as the vehicle speed increases.

Images