Vehicle control device

Abstract

To provide a vehicle control device that can safely suppress vehicle lane departure when vehicle deviation occurs.SOLUTION: A vehicle control device 1 includes: a lane departure suppression device 20A including a lane marking recognition unit 21 configured to recognize lane markings of a lane in which a vehicle is running, a deviation degree calculation unit 22 configured to calculate the degree of deviation of the vehicle from the lane, and a steering control unit 25 configured to perform steering control to execute lane departure suppression control for suppressing the vehicle's deviation from the lane when the degree of deviation calculated by the deviation degree calculation unit 22 is equal to or greater than a deviation threshold; a deflection detection unit 27 configured to detect deflection of the vehicle; and a deviation threshold change unit 23 configured to change the deviation threshold to be smaller than when the vehicle's deflection is not detected, when the vehicle's deflection is detected by the deflection detection unit 27.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a vehicle control device. [Background technology]

[0002] Conventionally, systems that control the behavior of a vehicle to suppress deviation of the vehicle are known. For example, Patent Document 1 discloses a device that performs anti-skid control by controlling the brakes of each wheel when a lateral skid of the vehicle is detected from an estimated yaw rate based on steering angle information and an actual yaw rate by a yaw rate sensor. In the device of Patent Document 1, when a lateral skid caused by oversteering is detected, the device controls to apply the brakes on the opposite side to the deviation more strongly than on the deviation side. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-37905 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the vehicle is in a biased state, the vehicle behavior may become unstable and the vehicle may deviate from its lane. Therefore, it is desirable to control the vehicle behavior so as to prevent the vehicle from deviating from its lane even when the vehicle is in a biased state.

[0005] The present invention has been made in consideration of the above-described circumstances, and has an object to provide a vehicle control device that can safely suppress the vehicle from leaving its lane when the vehicle is deflecting. [Means for solving the problem]

[0006] According to one aspect of the present invention, a vehicle control device includes a lane departure prevention device having a lane departure line recognition unit that recognizes the lane departure lines of the lane in which the vehicle is traveling, a departure degree calculation unit that calculates the degree of departure of the vehicle from the lane, and a steering control unit that performs steering control to execute lane departure prevention control to prevent the vehicle from deviating from the lane when the degree of departure calculated by the departure degree calculation unit is equal to or greater than a departure threshold, a deviation detection unit that detects deviation of the vehicle, and a deviation threshold change unit that changes the deviation threshold to be smaller when deviation of the vehicle is detected by the deviation detection unit than when deviation of the vehicle is not detected. Effect of the Invention

[0007] The vehicle control device according to the present invention can safely prevent the vehicle from leaving its lane even when the vehicle is deflecting. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration of a vehicle control device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a flowchart showing the flow of vehicle control in the first embodiment. [Diagram 3] FIG. 3 is a flowchart illustrating the operation of the steering control for the lane departure suppression control. [Figure 4] FIG. 4 is a flowchart showing the flow of vehicle control in the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] -First embodiment- DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A vehicle control device according to a first embodiment of the present invention will now be described in detail with reference to the drawings. Fig. 1 is a block diagram showing a schematic configuration of the vehicle control device according to the present embodiment.

[0010] 1, the vehicle control device 1 includes, for example, a camera 10 that captures an image of the area in front of the vehicle, a yaw rate sensor 11, a steering angle sensor 12, a wheel speed sensor 13, a controller 20, a steering device 30, and a brake device 40. The vehicle control device 1 may optionally include a selection switch 14 and an alarm device 50.

[0011] The camera 10 is configured to capture an image of the area in front of the vehicle using an image sensor and input the image data to the controller 20. The camera 10 is configured to be able to detect the positions of dividing lines on the road that define the lane in which the vehicle is traveling and adjacent lanes, etc.

[0012] The yaw rate sensor 11 is configured to detect an angular velocity (yaw rate) of the vehicle about a vertical axis. The steering angle sensor 12 is configured to detect a steering angle of the vehicle. The wheel speed sensor 13 is provided on each of the front and rear wheels of the vehicle and configured to detect the wheel speed of each wheel. Information on the yaw rate detected by the yaw rate sensor 11, the steering angle detected by the steering angle sensor 12, and the wheel speed detected by the wheel speed sensor 13 are each input to the controller 20.

[0013] The controller 20 is configured, for example, by a computer including a ROM storing programs and data, a CPU performing arithmetic processing, a RAM storing dynamic data and arithmetic processing results, an input / output interface, etc. The controller 20 is configured to execute functions of a lane marking recognition unit 21, a departure degree calculation unit 22, a departure threshold change unit 23, a steering torque correction unit 24, a steering control unit 25, an override threshold change unit 26, a deflection detection unit 27, a brake control unit 28, etc., and to control the entire control device 1 of the vehicle.

[0014] The lane line recognition unit 21, the departure degree calculation unit 22, the departure threshold change unit 23, the steering torque correction unit 24, the steering control unit 25, and the override threshold change unit 26 constitute a lane departure suppression device 20A that executes lane departure suppression control to suppress the vehicle from deviating from the lane. The deviation detection unit 27 and the brake control unit 28 constitute a skid suppression device 20B that executes skid suppression control to suppress deviation of the vehicle. The lane departure suppression device 20A and the skid suppression device 20B may be implemented integrally as the controller 20, or may be implemented as separate controllers.

[0015] The lane departure prevention device 20A is configured to turn on or off the lane departure prevention control function in response to a manual operation by a user, for example, the user's operation of the selection switch 14. When the lane departure prevention control function is on and it is determined that the vehicle is likely to deviate from the lane in which it is traveling, the lane departure prevention device 20A is configured to suppress the vehicle from deviating from the lane by performing steering control. First, the basic configuration of the lane departure prevention device 20A will be described.

[0016] The marking line recognition unit 21 is configured to recognize marking lines that define the lane (driving lane) in which the vehicle is traveling. For example, the marking line recognition unit 21 performs image processing based on image data of the forward area input from the camera 10, and recognizes left and right marking lines (white lines) that define the lane in which the vehicle is traveling. The marking lines include marking lines of the own lane and adjacent lanes, and marking lines at the lateral ends of the own lane.

[0017] The deviation degree calculation unit 22 is configured to calculate the degree of deviation of the vehicle from the lane. The deviation degree is an index indicating whether or not the vehicle is likely to deviate from the lane in which it is traveling, and the higher the deviation degree, the higher the possibility of deviation from the lane. For example, the deviation degree calculation unit 22 calculates the distance in the lane width direction from the dividing line of the lane in which the vehicle is traveling to the front wheels based on image data of the front area input from the camera 10. Alternatively, the deviation degree calculation unit 22 may be configured to calculate the distance in the lane width direction from the dividing line of the lane in which the vehicle is traveling to the front wheels by estimating the vehicle's position in the lane using a GNSS system or the like.

[0018] The deviation degree calculation unit 22 can determine that the smaller the distance from the lane width direction from the lane line to the front wheel, the closer the vehicle is to the lane center toward the lane line, the higher the risk of the vehicle deviating from the lane, and the higher the degree of deviation of the vehicle. That is, it is defined here that the higher the risk of the vehicle deviating from the lane, the higher the degree of deviation. When the vehicle is approaching a lane line on the right side, the deviation degree calculation unit 22 calculates the degree of deviation of the vehicle based on the distance in the lane width direction between the right lane line and the right front wheel of the vehicle, and when the vehicle is approaching a lane line on the left side, the deviation degree calculation unit 22 calculates the degree of deviation of the vehicle based on the distance in the lane width direction between the left lane line and the left front wheel of the vehicle.

[0019] The departure degree calculation unit 22 may calculate the degree of departure of the vehicle by taking into account the steering angle and / or vehicle speed in addition to the distance from the front wheels of the vehicle to the lane marking. For example, if the steering angle is large or the steering speed is fast and the driver is performing abrupt steering, the degree of departure of the vehicle can be increased. Also, for example, the faster the vehicle speed is, the greater the degree of departure of the vehicle can be.

[0020] The steering control unit 25 is configured to determine that the vehicle is highly likely to deviate from the lane when the degree of departure calculated by the departure degree calculation unit 22 is equal to or greater than a preset departure threshold value, and to perform steering control to execute lane departure suppression control to suppress the vehicle from deviating from the lane. The steering control unit 25, for example, calculates a target steering angle for guiding the vehicle toward the center of the lane in the lane width direction, and outputs a steering angle command corresponding to the target steering angle to the steering device 30.

[0021] The departure threshold changing unit 23 is configured to change a departure threshold for determining whether or not there is a high possibility that the vehicle will deviate from the lane. The steering torque correcting unit 24 is configured to correct the steering torque for the lane departure prevention control. The override threshold changing unit 26 is configured to change an override threshold for determining whether or not the lane departure prevention control has been overridden by the driver's operation intervention. The departure threshold changing unit 23, the steering torque correcting unit 24, and the override threshold changing unit 26 will be described later.

[0022] The steering device 30 has an EPS controller, an EPS actuator, a steering mechanism, etc., and is configured to perform steering control in response to a steering angle command input from the steering control unit 25. For example, the EPS controller refers to a steering angle-steering torque map for each vehicle speed and transmits a torque command to the EPS actuator, and the EPS actuator applies a steering torque to the steering mechanism in response to this. In this way, lane departure suppression control is performed by the steering device 30 providing a front wheel steering angle corresponding to the target steering angle and generating a steering torque (steering assist torque).

[0023] The skid suppression device (deflection suppression device) 20B is configured to execute skid suppression control (deflection suppression control) that suppresses deflection of the vehicle by performing braking control when deflection of the vehicle is detected. The deflection suppression device 20B utilizes a so-called EBD (electronic braking force distribution system) that automatically distributes optimal braking force to the front and rear wheels, and is configured to reduce and maintain the brake force of the rear wheel on the deflected side to suppress deflection of the vehicle when deflection of the vehicle is detected. That is, here, the skid suppression control (deflection suppression control) means control that suppresses deflection of the vehicle by weakening the brake force of the wheel on the deflected side using EBD.

[0024] The deflection detection unit 27 is configured to detect deflection of the vehicle. For example, the deflection detection unit 27 estimates a yaw rate assumed to act on the vehicle based on information on the steering angle detected by the steering angle sensor 12, and calculates a yaw rate estimation value. Also, the deflection detection unit 27 calculates a yaw rate detection value that actually acts on the vehicle based on information on the yaw rate detected by the yaw rate sensor 11. The deflection detection unit 27 compares the yaw rate detection value with the yaw rate estimation value, and can determine that a deflection has occurred in the vehicle, that is, that the vehicle is skidding, when, for example, the difference between the yaw rate detection value and the yaw rate estimation value is equal to or greater than a predetermined value. When the yaw rate detection value and the yaw rate estimation value are substantially the same, it can be determined that there is no deflection in the vehicle. Also, when the vehicle is deflected, the deflection detection unit 27 detects whether the vehicle is deflected to the right or to the left.

[0025] The brake control unit 28 is configured to control the braking force of each wheel so as to suppress the deflection of the vehicle when deflection of the vehicle is detected by the deflection detection unit 27. Specifically, the brake control unit 28 performs braking control so that the braking force of the rear wheel on the deflected side is weaker than the braking force of the rear wheel on the opposite side to the deflected side. If the deflection is not suppressed, the brake control unit 28 further performs control so that the braking force of the inner front wheel is weaker than the braking force of the opposite front wheel.

[0026] As a result, for example, when the vehicle is deflected to the left, the braking force of the left rear wheel is relatively weaker than that of the right rear wheel, and when the vehicle is deflected to the right, the braking force of the right rear wheel is relatively weaker than that of the left rear wheel. The brake control unit 28 calculates the braking force to be generated in each wheel according to the deflection of the vehicle, and outputs a deceleration command according to the braking force to the brake device 40. Note that, when the deflection of the vehicle is not sufficiently suppressed even after the braking control for weakening the braking force of the rear wheel on the deflected side is performed, the braking control for further weakening the braking force of the front wheel on the deflected side may be performed.

[0027] The braking device 40 includes brakes (e.g., disc brakes, drum brakes, etc.) provided on each wheel, a brake actuator connected to the brakes via hydraulic piping, and a brake controller, and is configured to control the hydraulic pressure in accordance with a deceleration command from the brake control unit 28 and to control the braking force of the brakes.

[0028] The notification device 50 is configured to notify the user of the operating state of the lane departure suppression control and the deflection suppression control (side-slip suppression control). For example, the notification device 50 can notify that the lane departure suppression control function is turned on and that the lane departure suppression control is operating. The notification device 50 can also notify that the side-slip suppression control function is turned on and that the side-slip suppression control function is operating. The notification method by the notification device 50 can be a visual method such as a lamp illumination or a text display, an auditory method such as a voice output, and / or a tactile method such as a vibration.

[0029] In this manner, the vehicle control device 1 in this embodiment is configured to execute lane departure suppression control by steering control to suppress departure of the vehicle from the lane, and skid suppression control by brake control to suppress deviation of the vehicle. Usually, the lane departure suppression control and the skid suppression control are executed independently. However, when the vehicle is in a skid, i.e., deviation state, it is considered that the possibility of the vehicle deviating from the lane tends to increase. In such a case, if the lane departure suppression control and the skid suppression control are executed separately, it may be difficult to effectively suppress deviation and departure of the vehicle from the lane.

[0030] For example, when a vehicle is deviating and trying to deviate from a lane, the behavior of the vehicle is more unstable than when the vehicle is not deviating. In such a situation, if steering control is performed at the same timing as in normal lane departure prevention control, the vehicle may not be guided quickly toward the center of the lane. In addition, for example, when a driver brakes the vehicle, the vehicle may deviate depending on the center of gravity of the vehicle or the effectiveness of the brakes. In this case, in the skid prevention control, the braking force of the wheel on the deviating side is weakened as described above, so that the desired braking force may not be obtained.

[0031] Therefore, the vehicle control device 1 in this embodiment is configured to safely suppress the vehicle from deviating from its lane when the vehicle is deflecting. For this reason, the lane departure suppression device 20A further includes a departure threshold changing unit 23, a steering torque correcting unit 24, and an override threshold changing unit 26.

[0032] The deviation threshold changing unit 23 sets the deviation threshold Th for determining whether the vehicle is likely to deviate from the lane to different values depending on whether the vehicle's deviation is detected or not. Specifically, the deviation threshold changing unit 23 makes the deviation threshold Th2 when the vehicle's deviation is detected smaller than the deviation threshold Th1 when the vehicle's deviation is not detected (Th2 < Th1). Thereby, when the vehicle is deviating, it is possible to determine the possibility of the vehicle deviating from the lane at an earlier timing compared to when the vehicle is not deviating. Therefore, the steering control can be started at an earlier timing.

[0033] Also, the deviation threshold changing unit 23 makes the deviation threshold Th2 smaller as the deviation speed of the vehicle increases when the vehicle's deviation is detected. When the deviation speed of the vehicle is high, it is considered that the vehicle behavior is in a more unstable situation, so the possibility of the vehicle deviating from the lane is determined at an even earlier timing. The deviation speed of the vehicle can be calculated, for example, from the change speed of the yaw rate actually acting on the vehicle based on the yaw rate information detected by the yaw rate sensor 11.

[0034] The steering torque correction unit 24 corrects the steering torque applied to the steering mechanism to execute lane departure suppression control by the steering control unit 25 to be larger when the vehicle's deviation is detected than when the vehicle's deviation is not detected. For example, the steering torque correction unit 24 can correct by multiplying the steering torque obtained by referring to the vehicle speed - steering angle - steering torque map by a coefficient (≥1) set appropriately in advance. Alternatively, a vehicle speed - steering angle - steering torque map used when the vehicle's deviation is detected may be prepared separately from the normal steering torque map. Thereby, when the vehicle is deviating and there is a high possibility of the vehicle deviating from the lane, the steering torque is increased to quickly guide the vehicle toward the center of the lane.

[0035] The lane departure suppression device 20A may be configured to detect a deflection by the deflection detection unit 27 when the vehicle is braking while traveling straight. This is to avoid erroneous determination of the deflection or possibility of departure of the vehicle by limiting the detection to when the vehicle is traveling straight. In addition, when braking the vehicle, a moment is generated in the vehicle due to the influence of the center of gravity position of the vehicle and the offset load, etc., which makes the vehicle prone to deflection, and therefore, lane departure suppression control is performed to deal with this. Whether the vehicle is traveling straight or not can be determined based on, for example, the steering angle input from the steering angle sensor 12. Whether the vehicle is braking or not can be determined based on, for example, whether the brake pedal (not shown) of the brake device 40 is being depressed or not.

[0036] Furthermore, the lane departure suppression device 20A may be configured to detect deviation by the deviation detection unit 27 when the vehicle speed is equal to or greater than a predetermined value. This is because deviation tends to be more noticeable when the vehicle is traveling at high speed, and the braking distance is also longer. The predetermined value of the vehicle speed is set in advance to an appropriate value (for example, about 50 to 60 kilometers per hour). The vehicle speed can be calculated based on the wheel speed input from the wheel speed sensor 13, for example.

[0037] The lane departure prevention device 20A has an override function that stops the lane departure prevention control and transfers authority to the driver when the driver intervenes in steering equal to or greater than an override threshold while the lane departure prevention control is being executed. When the steering torque (or steering angle, steering angle speed, etc.) due to the driver's manual steering is equal to or greater than an override threshold, the lane departure prevention control is overridden. When the lane departure prevention control is overridden, the lane departure prevention control is stopped and the vehicle transitions to a manual driving mode.

[0038] Here, the lane departure suppression device 20A is configured to gradually end the steering control for lane departure suppression control by the steering control unit 25 when the driver performs a steering operation of equal to or more than the override threshold in the direction opposite to the direction of the vehicle deviation while the deviation detection unit 27 detects the deviation of the vehicle. For example, when the vehicle is deviation to the left, if the driver performs a steering operation (avoidance operation) of equal to or more than the override threshold to the right in order to eliminate the deviation, the steering control is gradually ended with priority given to the steering operation by the driver. Also, when the vehicle is deviation to the right, if the driver performs a steering operation (avoidance operation) of equal to or more than the override threshold to eliminate the deviation, the steering control is gradually ended with priority given to the steering operation by the driver.

[0039] Here, when the vehicle is deflected and the possibility of deviating from the lane increases from the deflection direction, the lane departure prevention control applies a steering torque in the opposite direction to the deflection direction. If the driver is surprised by the operation of the lane departure prevention control and performs manual steering in the opposite direction to the applied steering torque, thereby overriding the lane departure prevention control, the vehicle behavior may become unstable. For example, when the vehicle is deflected to the left and the lane departure prevention control applies a steering torque in the right direction, which is the opposite direction to the deflection direction, the driver is surprised by the steering torque to the right and performs a steering operation in the left direction, which is the deflection direction, causing an override, and the vehicle may deflect more significantly.

[0040] Therefore, the override threshold change unit 26 is configured to change the override threshold in the vehicle deflection direction to be larger than when the deflection of the vehicle is not detected, when the deflection detection unit 27 detects the deflection of the vehicle. This suppresses override caused by the driver's steering operation in the deflection direction, and when a steering operation larger than the changed override threshold is performed, the driver's intention is prioritized and the system can be switched to the manual driving mode.

[0041] In addition, the override of the lane departure prevention control may include, in addition to the steering override due to steering intervention, an acceleration override due to the driver's acceleration operation intervention, and a deceleration override due to the driver's deceleration operation intervention, but the override threshold change unit 26 particularly changes the override threshold for determining whether or not there is a steering override due to steering intervention.

[0042] The flow of vehicle control in the first embodiment will be described in detail below with reference to the flowcharts of Figures 2 and 3. The processes shown in Figures 2 and 3 are periodically executed by the controller 20. The processes shown in Figures 2 and 3 particularly explain lane departure suppression control when there is a possibility that the vehicle will deviate and deviate from the lane. When there is no deviation of the vehicle but there is a high possibility that it will deviate from the lane, normal lane departure suppression control is executed by the lane departure suppression device 20A, although the explanation is omitted.

[0043] First, in step S101, it is determined whether the vehicle is traveling straight and braking is being applied. If the vehicle is traveling straight and braking is being applied, the process proceeds to step S102, and if the vehicle is not traveling straight and braking is being applied, the process ends.

[0044] In step S102, it is determined whether the vehicle speed is equal to or greater than a predetermined value. If the vehicle speed is equal to or greater than the predetermined value, the process proceeds to step S103, and if the vehicle speed is less than the predetermined value, the process ends.

[0045] In step S103, the deflection detection unit 27 detects deflection of the vehicle while the vehicle is traveling straight at a speed equal to or greater than a predetermined value and braking. If it is determined that the vehicle is deflecting, the process proceeds to step S104, and if it is determined that the vehicle is not deflecting, the process ends.

[0046] In step S104, it is determined whether or not the lane dividing line of the lane in which the vehicle is traveling is recognized by the lane dividing line recognition unit 21. If the lane dividing line of the lane is not recognized, since the lane departure suppression control by the lane departure suppression device 20A cannot be performed, the process proceeds to step S130. In step S130, in order to execute the skid suppression control by the skid suppression device 20B, the brake control unit 28 executes brake control. Thereby, this process ends.

[0047] On the other hand, if it is determined in step S104 that the lane dividing line of the lane is recognized, the process proceeds to step S105 in order to perform the lane departure suppression control by the lane departure suppression device 20A. In step S105, the deviation threshold changing unit 23 sets a deviation threshold Th2 for determining whether or not the vehicle is likely to deviate from the lane when the deviation of the vehicle is detected, to be smaller than the normal deviation threshold Th1 when the deviation of the vehicle is not detected. That is, the deviation threshold Th2 when the deviation of the vehicle is detected is smaller than the normal deviation threshold Th1 (Th2 < Th1). Further, the deviation threshold changing unit 23 decreases the deviation threshold Th2 when the deviation of the vehicle is detected as the deviation speed of the vehicle increases according to the deviation speed of the vehicle.

[0048] In step S106, the deviation degree calculation unit 22 calculates the degree of deviation of the vehicle with respect to the lane. In step S107, it is determined whether or not the degree of deviation calculated in step S106 is equal to or greater than the deviation threshold Th2 when the deviation of the vehicle set in step S105 is detected. If it is determined that the degree of deviation is equal to or greater than the deviation threshold Th2 and the vehicle is likely to deviate from the lane, the process proceeds to step S108. On the other hand, if it is determined that the degree of deviation is less than the deviation threshold Th2 and the vehicle is unlikely to deviate from the lane, this process ends.

[0049] In step S108, it is determined whether or not the lane departure prevention control function is turned on in response to the user's operation of the selection switch 14. If the lane departure prevention control function is not turned on, the process proceeds to step S109, where the lane departure prevention device 20A automatically switches the lane departure prevention control function on. Then, the process proceeds to step S110.

[0050] In step S110, the override threshold change unit 26 changes the override threshold for steering in the direction of the vehicle's deflection so that it is larger than when the vehicle's deflection is not detected. For example, when the vehicle is deflected to the left, the override threshold for steering in the left direction, which is the deflection direction, is made larger than when the vehicle's deflection is not detected, and the override threshold for steering in the right direction, which is the opposite direction to the deflection direction, is not changed. Also, when the vehicle is deflected to the right, the override threshold for steering in the right direction, which is the deflection direction, is made larger than when the vehicle's deflection is not detected, and the override threshold for steering in the left direction, which is the opposite direction to the deflection direction, is not changed.

[0051] In step S111, the steering torque correction unit 24 corrects the steering torque applied to the steering mechanism to execute lane departure prevention control when the vehicle is deflected. For example, the steering torque correction unit 24 can set a coefficient for correcting the steering torque applied to the steering mechanism to execute lane departure prevention control when the vehicle is not deflected, or prepare a vehicle speed-steering angle-steering torque map to be used when the vehicle is deflected. As a result, when the vehicle is deflected and there is a high possibility that the vehicle will depart from the lane, the steering torque applied to the steering mechanism is larger than when the vehicle is not deflected.

[0052] In step S120, the steering control unit 25 controls the steering device 30 to execute the lane departure suppression control when the vehicle is swerving, thereby executing the steering control. Hereinafter, the processing during the execution of the steering control for the lane departure suppression control when the vehicle is swerving in step S120 will be described with reference to the flowchart in FIG.

[0053] In step S121, it is determined whether or not an override has occurred due to steering intervention by the driver during lane departure prevention control. If the steering operation by the driver is equal to or greater than the override threshold changed in step S110, it is determined that the lane departure prevention control has been overridden, and the process proceeds to step S122. In step S122, the steering control is gradually terminated. For example, the steering control unit 25 can gradually terminate the steering control by gradually reducing the steering torque applied to the steering mechanism.

[0054] If the steering operation by the driver is less than the override threshold changed in step S110, the process proceeds to step S123, where it is determined whether or not the termination condition for the lane departure prevention control is satisfied. For example, it can be determined that the termination condition for the lane departure prevention control is satisfied when the vehicle stops or when the degree of departure is less than the departure threshold. If the termination condition for the lane departure prevention control is satisfied, the process proceeds to step S124, where the steering control unit 25 terminates the steering control. If the termination condition for the lane departure prevention control is not satisfied, the process returns to step S121.

[0055] In step S125, the departure threshold when the vehicle is biased, which was set in step S105, and the override threshold when the vehicle is biased, which was set in step S110, are reset to their normal values ​​when the vehicle is not biased.

[0056] In step S126, it is determined whether the lane departure prevention control function has been automatically switched from OFF to ON in order to perform steering control to prevent the vehicle from departing. If the lane departure prevention control function has been switched from OFF to ON by the lane departure prevention device 20A in step S109 described above, the process proceeds to step S127, where the lane departure prevention control function is switched from OFF to ON. This ends the process.

[0057] The vehicle control device 1 according to the first embodiment described above can achieve the following advantageous effects.

[0058] (1) The vehicle control device 1 is equipped with a lane departure prevention device 20A having a lane departure line recognition unit 21 that recognizes the lane departure lines of the lane in which the vehicle is traveling, a departure degree calculation unit 22 that calculates the degree of departure of the vehicle from the lane, and a steering control unit 25 that performs steering control to execute lane departure prevention control to prevent the vehicle from deviating from the lane when the degree of departure calculated by the departure degree calculation unit 22 is equal to or greater than a departure threshold, a deviation detection unit 27 that detects vehicle deviation, and a deviation threshold change unit 23 that changes the deviation threshold to be smaller when vehicle deviation is detected by the deviation detection unit 27 than when vehicle deviation is not detected.

[0059] When a deviation of the vehicle is detected, the deviation threshold Th2 smaller than the normal deviation threshold Th1 when a deviation of the vehicle is not detected can be set to determine whether or not the vehicle is likely to deviate from the lane when a deviation of the vehicle is detected at an earlier timing than when a deviation of the vehicle is not detected. This allows the lane departure suppression control to be started at an earlier timing when there is a possibility that the vehicle will deviate from the lane due to deviation, and makes it possible to safely suppress the vehicle from deviating from the lane when a deviation of the vehicle occurs. When a deviation of the vehicle is not detected, the normal deviation threshold Th1 is used to determine the possibility that the vehicle will deviate from the lane, so that the lane departure suppression control is not started at an unintentionally earlier timing.

[0060] (2) When a deviation of the vehicle is detected, the steering torque correction unit (correction unit) 24 corrects the steering torque applied to the steering mechanism by the steering control unit 25 to execute lane departure suppression control so that the steering torque is larger than when a deviation of the vehicle is not detected. When there is a possibility that the vehicle will deviate from the lane due to deviation, the lane departure suppression control is started at an early timing and the steering torque is increased, thereby assisting the driver's steering operation to more effectively suppress deviation of the vehicle and lane departure.

[0061] (3) The deflection detection unit 27 is configured to detect deflection when the vehicle is braking straight ahead. By detecting the deflection of the vehicle only when the vehicle is braking straight ahead, it is possible to avoid erroneously determining the deflection or possibility of departure of the vehicle. In addition, since a moment is generated in the vehicle due to the influence of the center of gravity position of the vehicle and the offset load during braking, which makes it easier for deflection to occur, it is possible to execute lane departure suppression control in response to such a situation.

[0062] (4) The deviation detection unit 27 is configured to detect deviation when the vehicle speed is equal to or greater than a predetermined value. When the vehicle is traveling at high speed, deviation tends to be more noticeable, so it becomes possible to execute lane departure suppression control in response to such a situation.

[0063] (5) The lane departure prevention device 20A is configured to turn on or off the lane departure prevention control function in response to a manual operation by the user. When the lane departure prevention control function is turned off in response to a manual operation by the user, if a deviation of the vehicle is detected and the deviation degree is equal to or greater than the deviation threshold Th2 changed by the deviation threshold change unit 23, the lane departure prevention device 20A is configured to switch the lane departure prevention control function from off to on to execute lane departure prevention control. For example, even if the lane departure prevention control function is turned off by the operation of the selection switch 14 by the user, the lane departure prevention control function can be switched from off to on as necessary, so that when there is a high possibility that the vehicle will deviate from the lane due to deviation, the necessary lane departure prevention control can be executed. After the lane departure prevention control is terminated, the lane departure prevention control function can be switched from on to off to return to the state in response to the operation of the selection switch 14 by the user.

[0064] (6) The vehicle control device 1 further includes a brake control unit 28 that controls the braking force of each wheel of the vehicle to perform skid suppression control to suppress the deflection of the vehicle when the deflection detection unit 27 detects deflection during straight-line braking of the vehicle.

[0065] (7) The brake control unit 28 is configured to execute skid suppression control when the lane markings are not recognized by the marking line recognition unit 21, and not execute skid suppression control when the lane markings are recognized by the marking line recognition unit 21. When the lane markings of the lane on which the vehicle is traveling cannot be recognized by the marking line recognition unit 21, the lane departure suppression control by the lane departure suppression device 20A cannot be executed, but the deviation of the vehicle can be suppressed by executing the skid suppression control by the brake control unit 28. When the lane markings of the lane are recognized by the marking line recognition unit 21, the skid suppression control is not executed, and only the lane departure suppression control by the lane departure suppression device 20A is executed. This makes it possible to suppress deviation of the vehicle from the lane by steering control. In addition, by not executing the skid suppression control by the brake control unit 28, brake control that weakens the braking force of the wheel on the deflected side relatively to the braking force of the wheel on the opposite side to the deflected side is not executed, so that an unfavorable situation in which the braking force of the wheel on the deflected side is weakened during straight-line braking of the vehicle can be avoided.

[0066] (8) The lane departure suppression device 20A has an override function that stops the lane departure suppression control and transfers authority to the driver when the driver performs steering intervention equal to or greater than the override threshold during execution of the lane departure suppression control. When the driver performs a steering operation equal to or greater than the override threshold in the opposite direction to the vehicle's deflection direction while the deflection detection unit 27 detects the deflection of the vehicle, the lane departure suppression device 20A gradually ends the steering control for the lane departure suppression control by the steering control unit 25. When the driver performs a steering operation in the opposite direction to the direction in which the vehicle is deflected, that is, when the driver performs a steering operation (avoidance operation) in the direction to avoid the deflection of the vehicle, the steering operation by the driver can be prioritized. In addition, in this case, since the steering control for the lane departure suppression control is gradually ended, a smooth transition from the lane departure suppression control to the manual driving mode by the driver can be realized.

[0067] (9) When the deflection detection unit 27 detects a deflection of the vehicle, the override threshold change unit 26 changes the override threshold in the deflection direction of the vehicle to be larger than when the deflection of the vehicle is not detected. As a result, when a steering torque in the direction opposite to the deflection direction is applied by the lane departure prevention control, even if a startled driver performs a steering operation in the deflection direction, the lane departure prevention control is less likely to be overridden, and the lane departure prevention control can be continued. In addition, when a steering operation larger than the changed override threshold is performed, the driver's intention is prioritized and the system can be switched to the manual driving mode.

[0068] (10) When the deviation detection unit 27 detects deviation of the vehicle, the deviation threshold change unit 23 reduces the deviation threshold as the deviation speed of the vehicle increases. As a result, when the deviation speed is high and deviation of the vehicle is significant, the deviation of the vehicle can be determined at an early timing, and lane departure suppression control can be started at an early timing.

[0069] -Second embodiment- A vehicle control device 1 according to a second embodiment of the present invention will be described below. The basic configuration of the vehicle control device 1 according to the second embodiment is similar to that of the first embodiment described above. The following mainly describes the differences from the first embodiment.

[0070] In the first embodiment described above, it is determined whether or not lane markings are recognized, and if the lane markings are not recognized, skid suppression control is executed by the skid suppression device 20B, and if the lane markings are recognized, skid suppression control is not executed, and only lane departure suppression control is executed by the lane departure suppression device 20A. In the second embodiment, regardless of whether the lane markings are recognized or not, if the vehicle is deviating, skid suppression control is executed by the skid suppression device 20B.

[0071] Fig. 4 is a flowchart illustrating the flow of vehicle control in the second embodiment. As shown in Fig. 4, when the vehicle is undergoing straight-line braking (positive determination in step S101), if the vehicle is deflecting (positive determination in step S102) and the vehicle speed is equal to or greater than a predetermined value (positive determination in step S103), the process proceeds to step S130, where brake control unit 28 executes brake control in order to execute skid suppression control by skid suppression device 20B.

[0072] In the next step S104, it is determined whether or not the lane markings of the lane in which the vehicle is traveling have been recognized by the lane marking recognition unit 21. The process from step S105 onwards is the same as the process from step S105 onwards in the flowchart of Fig. 3 described in the first embodiment, and therefore a description thereof will be omitted.

[0073] In the vehicle control device 1 according to the second embodiment described above, in addition to the effects and advantages of the first embodiment described above, the following effects and advantages can be achieved.

[0074] When the deflection detection unit 27 detects deflection during straight-line braking of the vehicle, the brake control unit 28 controls the braking force of each wheel of the vehicle to execute skid suppression control to suppress deflection of the vehicle. When deflection is detected during straight-line braking of the vehicle and there is a high possibility that the vehicle will deviate from the lane, skid suppression control by brake control is executed in addition to lane departure suppression control by steering control, so that deflection of the vehicle and departure from the lane can be effectively suppressed. Even if the skid suppression control executes brake control to weaken the braking force of the wheel on the deflected side relatively to the braking force of the wheel on the opposite side to the deflected side, steering control to guide the vehicle to the center of the lane is also executed, so that deflection can be suppressed quickly. The skid suppression control by brake control ends when the deflection of the vehicle is no longer detected, so that the braking force can be restored to the level corresponding to the driver's brake pedal operation.

[0075] -Variations- (1) In the above-described embodiment, the lane departure prevention device 20A is configured to switch the lane departure prevention control function from OFF to ON and execute lane departure prevention control when a deviation of the vehicle is detected and the degree of departure is equal to or greater than the departure threshold Th2 changed by the departure threshold change unit 23 while the lane departure prevention control function is turned OFF in response to a manual operation by the user. However, this is not limited to this, and the possibility of departure from the lane may be determined using the normal departure threshold Th1. In this case, the change of the departure threshold by the departure threshold change unit 23 can be omitted. In this case, the vehicle control device 1 is equipped with a lane departure prevention device 20A having a lane departure line recognition unit 21 that recognizes the lane departure lines of the lane in which the vehicle is traveling, a departure degree calculation unit 22 that calculates the degree of departure of the vehicle from the lane, and a steering control unit 25 that performs steering control to execute lane departure prevention control to suppress the vehicle from deviating from the lane when the degree of departure calculated by the departure degree calculation unit 22 is equal to or greater than a departure threshold, and a deflection detection unit 27 that detects deviation of the vehicle, and the lane departure prevention device 20A is configured to turn the lane departure prevention control function on or off in accordance with manual operation by the user, and when the lane departure prevention control function is turned off in accordance with manual operation by the user, when deviation of the vehicle is detected and the degree of departure is equal to or greater than a predetermined normal deviation threshold Th1, the lane departure prevention device 20A is configured to switch the lane departure prevention control function from off to on to execute lane departure prevention control.

[0076] By configuring in this manner, even if the lane departure prevention control function is turned off by the user operating the selection switch 14, the lane departure prevention control function can be switched from off to on as necessary, so that the necessary lane departure prevention control can be executed when there is a high possibility that the vehicle will deviate from the lane.

[0077] (2) The lane departure prevention device 20A may be configured to automatically switch the lane departure prevention control function from OFF to ON only when the vehicle is traveling on a highway. When the vehicle is traveling on a highway, the vehicle speed is high and the vehicle is likely to deflect when braking. In such a case, the lane departure prevention control function is automatically switched from OFF to ON, making it possible to execute the necessary lane departure prevention control. Note that whether the vehicle is traveling on a highway can be determined based on information from a navigation system (not shown), for example.

[0078] (3) In the above-described embodiment, when the steering torque correction unit 24 detects a deviation of the vehicle, the steering torque applied to the steering mechanism by the steering control unit 25 to execute the lane departure suppression control is corrected to be larger than when the deviation of the vehicle is not detected. However, this is not limiting, and the correction of the steering torque by the steering torque correction unit 24 may be omitted. Even in this case, when there is a possibility that the vehicle will deviate from the lane due to deviation, the lane departure suppression control is started at an early timing, so that deviation of the vehicle and departure from the lane can be suppressed at an early timing.

[0079] (4) In the above-described embodiment, the deviation of the vehicle is detected when the vehicle is braking while traveling straight at a vehicle speed equal to or greater than a predetermined value. However, the present invention is not limited to this, and the deviation of the vehicle may be detected when the vehicle is not traveling straight, when the vehicle is not braking, or when the vehicle speed is less than a predetermined value.

[0080] (5) In the embodiment described above, when a vehicle deflection is detected by deflection detection unit 27, override threshold change unit 26 changes the override threshold in the vehicle deflection direction to be larger than when no vehicle deflection is detected. However, this is not limited to this, and a configuration may be made in which the override threshold is not changed and the same override threshold is used when a vehicle deflection is detected and when no deflection is detected.

[0081] Although several embodiments of the present invention have been described above, it should be noted that the present invention is not limited to the above-described embodiments, and various modifications and variations are possible within the scope of the present invention. [Explanation of symbols]

[0082] 1 Vehicle control device 20A Lane Departure Prevention Device 21 lane marking recognition unit, 22 departure degree calculation unit, 23 departure threshold change unit, 24 steering torque correction unit, 25 steering control unit, 26 override threshold change unit 20B Side slip prevention device 27 deflection detection unit, 28 brake control unit

Claims

1. A lane departure prevention device having a lane departure line recognition unit that recognizes the lane departure lines of the lane in which a vehicle is traveling, a departure degree calculation unit that calculates the degree of departure of the vehicle from the lane, and a steering control unit that performs steering control to execute lane departure prevention control to prevent the vehicle from deviating from the lane when the degree of departure calculated by the departure degree calculation unit is equal to or greater than a departure threshold; a deviation detection unit that detects deviation of the vehicle, and a deviation threshold change unit that, when deviation of the vehicle is detected by the deviation detection unit, changes the deviation threshold to be smaller than when deviation of the vehicle is not detected.

2. 2. The vehicle control device according to claim 1, further comprising a correction unit that corrects a steering torque applied to a steering mechanism by the steering control unit to execute the lane departure prevention control when a deviation of the vehicle is detected so that the steering torque is larger than when a deviation of the vehicle is not detected.

3. The vehicle control device according to claim 1 , wherein the deflection detection unit is configured to detect deflection during straight-line braking of the vehicle.

4. The vehicle control device according to claim 1 , wherein the deviation detection unit is configured to detect a deviation when a vehicle speed of the vehicle is equal to or greater than a predetermined value.

5. The lane departure prevention device is configured to turn on or off a function of the lane departure prevention control in response to a manual operation by a user, 5. The vehicle control device according to claim 1, wherein when a deviation of the vehicle is detected and the degree of deviation is equal to or greater than the deviation threshold changed by the deviation threshold changing unit while the lane departure prevention control function is turned off in response to a manual operation by a user, the lane departure prevention device switches the lane departure prevention control function from off to on and executes the lane departure prevention control.

6. 4. The vehicle control device according to claim 3, further comprising a brake control unit that controls braking forces of each wheel of the vehicle to perform sideslip prevention control to suppress the deflection of the vehicle when the deflection detection unit detects deflection during straight-line braking of the vehicle.

7. 7. The vehicle control device according to claim 6, wherein the brake control unit is configured to execute the skid suppression control when the lane markings are not recognized by the lane marking recognition unit, and to not execute the skid suppression control when the lane markings are recognized by the lane marking recognition unit.

8. The lane departure prevention device has an override function that stops the lane departure prevention control and transfers authority to the driver when a steering intervention by a driver is greater than or equal to an override threshold during execution of the lane departure prevention control, 2. The vehicle control device according to claim 1, wherein when the driver performs a steering operation equal to or greater than the override threshold in a direction opposite to the direction of the vehicle's deflection while the deflection detection unit detects deflection of the vehicle, the lane departure prevention device gradually terminates the steering control for the lane departure prevention control by the steering control unit.

9. 9. The vehicle control device according to claim 8, further comprising an override threshold change unit that changes the override threshold in the direction of the vehicle deflection when the deflection detection unit detects the vehicle deflection so that the override threshold in the direction of the vehicle deflection is larger than when the vehicle deflection is not detected.

10. The vehicle control device according to claim 1 , wherein the deviation threshold change unit is configured to reduce the deviation threshold as the deviation speed of the vehicle increases when the deviation detection unit detects deviation of the vehicle.

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