Vehicle driving support device

Abstract

A vehicle driving support device, in execution of a lane maintenance control, sets a center line passing through a center of a drivable width of a host vehicle in a host lane as a target travel line, and autonomously steers the host vehicle so that a reference point of the host vehicle moves along the target travel line. The vehicle driving support device, in execution of the lane maintenance control, changes a position of the target travel line so that the target travel line becomes a line between the center line and the reference point of the host vehicle, when a steering operation force of a driver becomes a target change start threshold value or more while the driver performs a steering operation for steering the host vehicle.

Description

Technical Field

[0001] This invention relates to a vehicle driving support device. Background Technology

[0002] There are known vehicle driving assistance devices that perform lane-keeping control to autonomously steer the vehicle in a way that keeps it within its lane. Typically, such devices set a target lane in the center of the lane to autonomously steer the vehicle along that lane. However, during lane-keeping control, sometimes the driver wants the vehicle to be positioned to the right or left of the target lane. In this case, while the driver is moving the vehicle to the right or left of the target lane, a large steering force is continuously applied to the steering wheel due to the lane-keeping control-based steering force, which becomes a burden for the driver.

[0003] Therefore, a vehicle driving support device is known that, when detecting a situation during lane keeping control where "the driver wishes to move the vehicle to the right or to the left of the target driving line", the vehicle driving support device presumes the desired position (desired position) of the vehicle and changes the position of the target driving line to that desired position (for example, refer to International Publication No. WO2017 / 022474). Summary of the Invention

[0004] If the system detects that "the driver wants the vehicle to be positioned to the right or left of the target driving line set in the center of the lane," and changes the position of the target driving line to the driver's desired position, then the steering force required by the driver to operate the steering wheel becomes too small when the vehicle is in the driver's desired position, making it difficult for the driver to recognize whether lane keeping control is in operation.

[0005] The purpose of this invention is to provide a vehicle driving support device that, when the driver is driving the vehicle to the right or left of the target driving line during lane keeping control, makes it easy for the driver to recognize that "lane keeping control is being executed (during execution)" and reduces the steering effort required from the driver.

[0006] The vehicle driving support device of the present invention performs lane-keeping control to enable autonomous steering of the vehicle in a manner that allows the vehicle to travel within its lane. In executing the lane-keeping control, the vehicle driving support device of the present invention sets a target driving line as the centerline passing through the center of the vehicle's drivable width within the lane, and performs autonomous steering by moving the vehicle's reference point along the target driving line. The vehicle driving support device of the present invention is configured such that, when a driver performs a steering operation to control the vehicle during the execution of lane-keeping control, if the driver's steering force exceeds a target change initiation threshold, the position of the target driving line is changed such that the target driving line becomes the line between the centerline and the vehicle's reference point.

[0007] When autonomously steering the vehicle using lane keeping control to align it with the center line as the target driving line, the driver sometimes desires to position the vehicle to the right or left of the target driving line. In this case, maintaining alignment between the target driving line and the center line requires significant steering effort from the driver to maintain the desired straight-line position, thus placing a burden on the driver.

[0008] According to the present invention, when the driver moves the vehicle laterally from the target driving line during lane keeping control, the target driving line moves from the center line in the same direction. Therefore, the steering force required by the driver to keep the vehicle straight at the desired position is reduced. Furthermore, when the vehicle is traveling straight at the desired position, the target driving line is set between the center line and the vehicle's reference point. Therefore, a certain degree of steering force based on lane keeping control is applied to the vehicle, making it easier for the driver to recognize that "lane keeping control is in effect."

[0009] Therefore, according to the present invention, when the driver moves the vehicle to the right or left of the center line during lane keeping control, the driver can easily recognize that "lane keeping control is being performed", and the steering effort required from the driver is reduced.

[0010] Furthermore, the vehicle driving support device of the present invention can be configured such that, after the driver's steering force becomes above the target change start threshold and a change in the position of the target driving line is initiated, when the driver's steering force becomes below the target change end threshold, the position of the target driving line is changed in such a way that the target driving line is aligned with the center line.

[0011] When lane keeping control is in effect, a driver may sometimes wish to keep the vehicle positioned to the right or left of the center line, or even closer to the center line.

[0012] According to the present invention, by utilizing the situation where "the driver's steering force decreases when the driver wants to keep the vehicle in the center line position and performs steering operations on the vehicle," the position of the target driving line is returned to the center line position. Therefore, it is possible to keep the vehicle in the center line position when the driver wants to keep it in the center line position.

[0013] Furthermore, the vehicle driving support device of the present invention can be configured such that, after the driver's steering operation force becomes above the target change start threshold and a change in the position of the target driving line begins, when the driver's steering operation force decreases to the target hold start threshold, the change in the position of the target driving line is stopped, and the position of the target driving line is maintained at the position at the time point when the steering operation force decreases to the target hold start threshold.

[0014] If, during lane keeping control, the driver's steering effort exceeds the target change initiation threshold and the target lane is shifting towards the vehicle's reference point, and the vehicle reaches the driver's desired position and begins straight-line travel, then the driver's steering effort will begin to decrease. Therefore, it is possible to determine whether the vehicle has reached the driver's desired position based on the driver's steering effort.

[0015] According to the present invention, after a change in the target driving line begins when the driver's steering force reaches or exceeds the target change initiation threshold, and then decreases the driver's steering force to the target hold initiation threshold, the change in the target driving line is stopped and the target driving line is held at the position at that point in time. Therefore, a suitable target driving line can be set as the target driving line when the vehicle reaches the position desired by the driver.

[0016] Furthermore, the vehicle driving support device of the present invention can be configured such that when the steering operation force is reduced to the target hold start threshold and the position of the target driving line is maintained at the position at the time point when the steering operation force is reduced to the target hold start threshold, the position of the target driving line is changed in such a way that the target driving line is aligned with the center line when the steering operation force becomes below the target change end threshold which is set to a value smaller than the target hold start threshold.

[0017] When a driver is moving the vehicle to the right or left of the center line during lane keeping control, they may sometimes wish to keep the vehicle in the center line.

[0018] According to the present invention, by utilizing the situation where "the driver's steering force decreases when the driver wants to drive the vehicle in the center line position and performs steering operations on the vehicle," the position of the target driving line is returned to the center line position. Therefore, it is possible to drive the vehicle in the center line position when the driver wants to drive it in the center line position.

[0019] The constituent elements of this invention are not limited to the embodiments of the invention described below with reference to the accompanying drawings. Other objects, features, and incidental advantages of the invention will be readily understood from the description of embodiments of the invention. Attached Figure Description

[0020] The features, advantages, and technical and industrial significance of exemplary embodiments of the present invention will be described below with reference to the accompanying drawings, wherein like reference numerals denote like elements, and in the drawings:

[0021] Figure 1 This is a diagram illustrating a vehicle driving support device according to an embodiment of the present invention and a vehicle (the present vehicle) equipped with the vehicle driving support device.

[0022] Figure 2A This diagram illustrates a situation where steering torque is controlled by lane keeping control to keep the vehicle on the target driving line.

[0023] Figure 2B This diagram illustrates a situation where a vehicle that has deviated to the left from the target driving line is steered to the right by lane keeping control, thereby controlling the steering torque to keep the vehicle on the target driving line.

[0024] Figure 2C This diagram illustrates a situation where a vehicle that has deviated to the right from the target driving line is steered to the left by lane keeping control, thereby controlling the steering torque to keep the vehicle on the target driving line.

[0025] Figure 3 This diagram illustrates a situation where the vehicle is traveling to the right of the target lane.

[0026] Figure 4A This diagram illustrates a scenario where, during lane keeping control, the vehicle moves to a position deviating to the right from the target lane, but the driver's steering torque is less than the target change initiation threshold.

[0027] Figure 4B This diagram illustrates a situation where, during lane keeping control, the vehicle moves to a position deviating to the right from the target driving line and the driver's steering torque exceeds the target change initiation threshold, thereby changing the position of the target driving line.

[0028] Figure 4C This diagram illustrates a situation where, during lane keeping control, the vehicle deviates to the right from the target lane to reach the position desired by the driver and changes the position of the target lane.

[0029] Figure 4D This diagram illustrates a situation where, during the execution of lane keeping control, the change in the target driving line is completed and the vehicle is traveling in the position desired by the driver.

[0030] Figure 5A This diagram illustrates a situation where, although the vehicle moves to a position deviating to the left from the driver's desired position during lane keeping control, the driver's steering torque is greater than the target change termination threshold.

[0031] Figure 5B This diagram illustrates a situation where, during lane keeping control, the vehicle moves to a position deviating to the left from the position desired by the driver, and the driver's steering torque falls below the target change termination threshold, thereby changing the position of the target driving line.

[0032] Figure 5C This diagram illustrates the situation where the vehicle reaches the center line and changes its position in the target driving lane during lane keeping control.

[0033] Figure 5D This diagram illustrates a situation where, during the execution of lane keeping control, the target driving line position has been changed and the vehicle is traveling in the position of the center line of the lane.

[0034] Figure 6 It is a timing diagram showing the changes in the driver's steering torque and the target driving line.

[0035] Figure 7 This is a flowchart illustrating the routines executed by the vehicle driving support device according to an embodiment of the present invention.

[0036] Figure 8 This is a flowchart illustrating the routines executed by the vehicle driving support device according to an embodiment of the present invention. Detailed Implementation

[0037] Hereinafter, a vehicle driving support device according to an embodiment of the present invention will be described with reference to the accompanying drawings. Figure 1 As shown, the vehicle driving support device 10 of the embodiment of the present invention is mounted on the vehicle 100.

[0038] <ECU>

[0039] The vehicle driving support device 10 includes an ECU 90 as a control device. ECU is short for Electronic Control Unit. The ECU 90 has a microcomputer as its main component. The microcomputer includes a CPU, ROM, RAM, non-volatile memory, and an interface. The CPU performs various functions by executing instructions, programs, or routines stored in the ROM.

[0040] <Driver, etc.>

[0041] In addition, the vehicle 100 is equipped with a drive unit 21, a braking unit 22 and a steering unit 23.

[0042] <Driver>

[0043] The drive unit 21 is a device that outputs driving torque (driving force) to the vehicle 100 to enable the vehicle 100 to move, such as an internal combustion engine or a motor. The drive unit 21 is electrically connected to the ECU 90. The ECU 90 can control the driving torque output from the drive unit 21 by controlling the operation of the drive unit 21.

[0044] <Brake Device>

[0045] Braking device 22 is a device that outputs braking torque (braking force) to brake vehicle 100, such as a brake system. Braking device 22 is electrically connected to ECU 90. ECU 90 can control the braking torque output from braking device 22 by controlling the operation of braking device 22.

[0046] <Steering gear>

[0047] The steering device 23 is a device that outputs steering torque (steering force) applied to the vehicle 100 to steer the vehicle 100, such as a power steering system. The steering device 23 is electrically connected to the ECU 90. The ECU 90 can control the steering torque output from the steering device 23 by controlling the operation of the steering device 23.

[0048] <Sensors, etc.>

[0049] Furthermore, the vehicle 100 is equipped with an accelerator pedal 31, an accelerator pedal operation sensor 32, a brake pedal 33, a brake pedal operation sensor 34, a steering wheel 35, a steering shaft 36, a steering angle sensor 37, a steering torque sensor 38, a vehicle speed detection device 41, a surrounding information detection device 50, and a driving support switch 61.

[0050] <Accelerator pedal operation sensor>

[0051] The accelerator pedal operation sensor 32 is a sensor that detects the operation amount of the accelerator pedal 31 and is electrically connected to the ECU 90. The accelerator pedal operation sensor 32 sends the detected operation amount information of the accelerator pedal 31 to the ECU 90. The ECU 90 obtains the operation amount of the accelerator pedal 31 (accelerator pedal operation amount) based on this information. The ECU 90 calculates the required drive torque (required drive force) based on the accelerator pedal operation amount and the vehicle speed (vehicle speed). The required drive torque is the drive torque required to be output by the drive unit 21. The ECU 90 controls the operation of the drive unit 21 to output the required drive torque.

[0052] <Brake pedal operation sensor>

[0053] The brake pedal operation amount sensor 34 is a sensor that detects the operation amount of the brake pedal 33 and is electrically connected to the ECU 90. The brake pedal operation amount sensor 34 sends the detected brake pedal operation amount information to the ECU 90. The ECU 90 obtains the brake pedal operation amount (brake pedal operation amount) based on this information. The ECU 90 calculates the required braking torque (required braking force) based on the brake pedal operation amount. The required braking torque is the braking torque that the braking device 22 is required to output. The ECU 90 controls the operation of the braking device 22 to output the required braking torque.

[0054] <Steering Angle Sensor>

[0055] The steering angle sensor 37 is a sensor that detects the rotation angle of the steering shaft 36 relative to the neutral position and is electrically connected to the ECU 90. The steering angle sensor 37 sends the detected rotation angle information of the steering shaft 36 to the ECU 90. The ECU 90 obtains the rotation angle (steering angle θ) of the steering shaft 36 based on this information.

[0056] <Steering Torque Sensor>

[0057] The steering torque sensor 38 is a sensor that detects the torque input by the driver to the steering shaft 36 via the steering wheel 35, and is electrically connected to the ECU 90. The steering torque sensor 38 sends the detected torque information to the ECU 90. Based on this information, the ECU 90 obtains the torque input by the driver to the steering shaft 36 via the steering wheel 35 (driver steering torque TQ_D or steering force).

[0058] <Vehicle speed detection device>

[0059] The vehicle speed detection device 41 is a device for detecting the vehicle speed (vehicle speed) of the vehicle 100, such as a wheel speed sensor. The vehicle speed detection device 41 is electrically connected to the ECU 90. The vehicle speed detection device 41 sends the detected vehicle speed information of the vehicle 100 to the ECU 90. The ECU 90 obtains the vehicle speed (vehicle speed V) of the vehicle 100 based on this information.

[0060] The ECU 90 calculates the driver-required steering torque based on the steering angle θ, the driver's steering torque TQ_D, and the vehicle speed V. The driver-required steering torque is the steering torque that the steering device 23 is required to output. When lane keeping control is not performed as described later, the ECU 90 controls the operation of the steering device 23 in a manner that outputs the driver-required steering torque from the steering device 23.

[0061] <Surrounding Information Detection Device>

[0062] The surrounding information detection device 50 is a device for detecting information about the surroundings of the vehicle 100. In this example, it includes an image sensor 51 and an electromagnetic wave sensor 52. The image sensor 51 is, for example, a camera. The electromagnetic wave sensor 52 is, for example, a radar sensor (millimeter-wave radar, etc.). In addition, the surrounding information detection device 50 may also include an ultrasonic sensor (gap sonar) or an optical sensor (LiDAR).

[0063] <Image Sensor>

[0064] Image sensor 51 is electrically connected to ECU 90. Image sensor 51 captures images of the surroundings of vehicle 100 and sends information related to the captured images to ECU 90. ECU 90 can then obtain surrounding information (surroundings detection information IS) based on this information (image information).

[0065] <Electronic Wave Sensor>

[0066] The radio wave sensor 52 is electrically connected to the ECU 90. The radio wave sensor 52 transmits radio waves and receives radio waves reflected from objects (reflected waves). The radio wave sensor 52 sends information (detection results) related to the transmitted and received radio waves (reflected waves) to the ECU 90. In other words, the radio wave sensor 52 detects objects present in the vicinity of the vehicle 100 and sends information (detection results) related to the detected objects to the ECU 90. The ECU 90 can obtain information (peripheral detection information IS) related to the objects present in the vicinity of the vehicle 100 based on this information (radio wave information).

[0067] <Driving Support Switch>

[0068] The driver assistance switch 61 is a switch that allows the driver to select whether to perform lane keeping control (described later), and it is electrically connected to the ECU 90. When the driver assistance switch 61 is operated in the on state, the ECU 90 determines that lane keeping control is required. On the other hand, when the driver assistance switch 61 is operated in the off state, the ECU 90 determines that lane keeping control is no longer required.

[0069] <Summary of the operation of vehicle driving support devices>

[0070] Next, a summary of the operation of the vehicle driving support device 10 will be explained. In the following explanation, "left" means the left side relative to the direction of travel of the vehicle 100, and "right" means the right side relative to the direction of travel of the vehicle 100.

[0071] like Figure 2A As shown, the vehicle driving support device 10 is configured to perform lane keeping control by autonomously steering the reference point (vehicle reference point Pref) of the vehicle 100 on the target driving line Ltgt. This autonomous steering involves autonomously steering the vehicle 100. The vehicle reference point Pref is simply a point that indicates the position of the vehicle 100; in this example, it is the position at the front end of the vehicle 100, at the center of the vehicle 100 in the width direction.

[0072] The vehicle driving support device 10 sets the center line (center line) through the width that the vehicle 100 can travel on (the drivable width of the vehicle 100) as the target driving line Ltgt. In this example, the vehicle driving support device 10 obtains the left lane marking (left lane marking LML) and the right lane marking (right lane marking LMR) of the vehicle 100 based on the surrounding detection information IS, obtains the distance (lane width LNW) between the left lane marking LML and the right lane marking LMR, uses the lane width LNW as the drivable width of the vehicle 100, and sets the center line (lane center line LNC) through the lane width LNW as the target driving line Ltgt. The lane center line LNC is a line extending along the center of the width of the lane LN. The lane LN is the lane that the vehicle 100 is currently traveling on (driving lane).

[0073] like Figure 2B As shown, when the vehicle reference point Pref deviates to the left from the target driving line Ltgt during lane keeping control, the vehicle driving support device 10 autonomously steers the vehicle 100 to the right, thereby moving the vehicle reference point Pref on the target driving line Ltgt.

[0074] More specifically, the vehicle driving support device 10 obtains the distance (deviation D) between the vehicle reference point Pref and the target driving line Ltgt based on the surrounding detection information IS. When the deviation D is greater than zero and the vehicle reference point Pref is located to the left of the target driving line Ltgt, the device calculates the steering torque for moving the vehicle 100 to the right based on the deviation D, and outputs a steering torque equivalent to the calculated steering torque (system steering torque TQ_S) from the steering device 23.

[0075] On the other hand, such as Figure 2C As shown, when the vehicle reference point Pref deviates to the right from the target driving line Ltgt during lane keeping control, the vehicle driving support device 10 autonomously steers the vehicle 100 to the left, thereby moving the vehicle reference point Pref on the target driving line Ltgt.

[0076] More specifically, the vehicle driving support device 10 obtains the deviation amount D based on the surrounding detection information IS. When the deviation amount D is greater than zero and the vehicle reference point Pref is located to the right of the target driving line Ltgt, the device calculates the steering torque for moving the vehicle 100 to the left based on the deviation amount D, and outputs a steering torque equivalent to the calculated steering torque (system steering torque TQ_S) from the steering device 23.

[0077] Therefore, during the execution of lane keeping control, the vehicle 100 moves along the target driving line Ltgt with its own reference point Pref.

[0078] When setting the target driving line Ltgt as the lane center line LNC so that the vehicle 100 performs lane keeping control in accordance with the target driving line Ltgt, sometimes, such as Figure 3 As shown, the driver may wish to drive the vehicle 100 to the right of the target driving line Ltgt. Alternatively, the driver may sometimes wish to drive the vehicle 100 to the left of the target driving line Ltgt.

[0079] When a driver wants to move the vehicle 100 to the right of the target lane Ltgt during lane keeping control, the driver inputs a clockwise steering torque to the steering wheel 35. This moves the vehicle 100 to the right of the target lane Ltgt. However, since the deviation D is greater than zero, the vehicle driving support device 10 inputs a counter-clockwise system steering torque TQ_S to the steering shaft 36 to make the deviation D zero. Therefore, when the driver wants to move the vehicle 100 further to the right, a larger clockwise steering torque needs to be input to the steering wheel 35.

[0080] In this way, when the driver moves the vehicle 100 to the right from the target driving line Ltgt during the execution of lane keeping control, the deviation D gradually increases, so the system steering torque TQ_S (counterclockwise steering torque) also gradually increases. As a result, the driver's steering torque TQ_D (clockwise steering torque) also gradually increases.

[0081] This also applies when the driver positions the vehicle 100 to the left of the target driving line Ltgt.

[0082] Therefore, when the driver moves the vehicle 100 laterally to the desired position, the steering torque (driver steering torque TQ_D) that the driver needs to input to the steering wheel 35 in order to make the vehicle 100 travel straight in the desired position becomes very large, which is not preferable.

[0083] Therefore, when the vehicle driving support device 10 anticipates that the driver wishes to move the vehicle 100 to the right or left of the target driving line Ltgt during the execution of lane keeping control, it changes the position of the target driving line Ltgt as follows.

[0084] During lane keeping control, the vehicle driving support device 10 monitors the value of the driver's steering torque TQ_D. If the driver's steering torque TQ_D is less than a predetermined value (target change start threshold TQ_C), it maintains the position of the target driving line Ltgt (the original target driving line Ltgt) set at that time point.

[0085] For example, such as Figure 4A As shown, when the deviation amount D is relatively small and the driver's steering torque TQ_D is smaller than the target change initiation threshold TQ_C, the vehicle driving support device 10 maintains the position of the target driving line Ltgt on the lane center line LNC.

[0086] Furthermore, unless otherwise specified in this manual, the driver's steering torque TQ_D refers to the absolute value (magnitude) of the driver's steering torque TQ_D.

[0087] On the other hand, when the driver's steering torque TQ_D increases and reaches the target change initiation threshold TQ_C, the vehicle driving support device 10 begins to change the position of the target driving line Ltgt. In this case, the vehicle driving support device 10 changes the position of the target driving line Ltgt in a manner that "gradually moves the target driving line Ltgt closer to the vehicle's reference point Pref".

[0088] For example, such as Figure 4BAs shown, when the vehicle 100 moves to the right from the target driving line Ltgt and the deviation D becomes relatively large and the driver's steering torque TQ_D reaches the target change start threshold TQ_C, the vehicle driving support device 10 starts to change the position of the target driving line Ltgt, so that the target driving line Ltgt gradually moves towards the vehicle reference point Pref.

[0089] At this time, the vehicle driving support device 10 changes the position of the target driving line Ltgt in such a way that the target driving line Ltgt is located between the lane center line LNC (the original target driving line Ltgt) and the vehicle reference point Pref.

[0090] More specifically, the vehicle driving support device 10 obtains the distance (vehicle separation distance) between the lane center line LNC and the vehicle reference point Pref from the surrounding detection information IS, sets a target position at a distance from the lane center line LNC away from the vehicle reference point Pref by a predetermined proportion of this vehicle separation distance, and changes the position of the target driving line Ltgt in a manner that allows the target driving line Ltgt to reach the target position. In other words, the vehicle driving support device 10 obtains the vehicle separation distance from the surrounding detection information IS, sets a target position at a distance from the lane center line LNC away from the vehicle reference point Pref by a coefficient smaller than '1', and changes the position of the target driving line Ltgt in a manner that allows the target driving line Ltgt to reach the target position.

[0091] Furthermore, at this time, the vehicle driving support device 10 sets an appropriate speed (predetermined change speed) as the speed at which the position of the target driving line Ltgt is changed, and changes the position of the target driving line Ltgt at this predetermined change speed. The vehicle driving support device 10 changes the predetermined change speed, for example, based on parameters such as the rate of change of the distance (vehicle separation distance) between the lane center line LNC and the vehicle reference point Pref. More specifically, the vehicle driving support device 10 sets the predetermined change speed by filtering parameters such as the rate of change of the distance (vehicle separation distance) between the lane center line LNC and the vehicle reference point Pref using, for example, a first-order filter or a time-variable filter.

[0092] Additionally, the vehicle driving support device 10 can also preset an upper limit for the predetermined change speed, and limit the predetermined change speed to the upper limit if the predetermined change speed is greater than this upper limit. For example, the vehicle driving support device 10 can limit the predetermined change speed by making the slope (inclination) of the change in position of the target travel line Ltgt relative to the time axis below a certain slope. That is, the predetermined change speed can also be set by making the shape of the trajectory of the change in position of the target travel line Ltgt relative to the time axis a predetermined shape.

[0093] In addition, while the vehicle driving support device 10 is changing the position of the target driving line Ltgt, it also outputs a system steering torque TQ_S from the steering device 23, which corresponds to the amount of deviation D between the changing target driving line Ltgt and the vehicle reference point Pref.

[0094] Then, when the vehicle 100 finally moves laterally to the position desired by the driver and the driver returns the steering wheel 35 to the neutral position and holds it there, the target driving line Ltgt approaches the vehicle reference point Pref and the deviation D gradually decreases. The system steering torque TQ_S gradually decreases, so the driver's steering torque TQ_D also gradually decreases, eventually reaching the predetermined value (target holding start threshold TQ_L).

[0095] For example, such as Figure 4C As shown, when the vehicle 100 moves to the right to the position desired by the driver and the driver returns the steering wheel 35 to the neutral position and holds it there, the target driving line Ltgt approaches the vehicle's reference point Pref and the deviation D gradually decreases. The system steering torque TQ_S gradually decreases, and therefore the driver's steering torque TQ_D also gradually decreases, eventually reaching the target holding start threshold TQ_L.

[0096] In addition, the target hold start threshold TQ_L can be the same as the target change start threshold TQ_C or a different value, but in this example it is set to the same value as the target change start threshold TQ_C.

[0097] When the driver's steering torque TQ_D decreases and reaches the target hold start threshold TQ_L, the vehicle driving support device 10 stops the change of the target driving line Ltgt and holds the target driving line Ltgt at the position at that time.

[0098] For example, when the driver's steering torque TQ_D decreases and reaches the target hold start threshold TQ_L, such as Figure 4D As shown, the vehicle driving support device 10 stops the change of the position of the target driving line Ltgt and keeps the target driving line Ltgt at the position of that point in time.

[0099] Therefore, the driver can use a smaller driver steering torque TQ_D to move the vehicle 100 to the right or left of the lane center line LNC, and the steering device 23 outputs a system steering torque TQ_S that is larger than zero to a certain extent, thus recognizing the situation of "lane keeping control in progress".

[0100] Subsequently, when the driver is driving the vehicle 100 to the right or left of the lane center line LNC (the original target driving line Ltgt), the driver sometimes wishes to drive the vehicle 100 in the center of the lane LN.

[0101] When the driver wants to center the vehicle 100 in lane LN, they apply torque to the steering wheel 35 in the same direction as the system steering torque TQ_S. Therefore, the driver's steering torque TQ_D decreases. Additionally, the vehicle's reference point Pref approaches the target driving line Ltgt, further reducing the driver's steering torque TQ_D.

[0102] However, even if the driver does not want the vehicle to be centered in lane LN, the vehicle's reference point Pref will sometimes approach the target driving line Ltgt, at which point the driver's steering torque TQ_D will also decrease.

[0103] Therefore, even if the driver's steering torque TQ_D decreases, the vehicle driving support device 10 maintains the position of the target driving line Ltgt until the driver's steering torque TQ_D reaches a predetermined value (target change end threshold TQ_E).

[0104] For example, such as Figure 5A As shown, even if the driver's steering torque TQ_D decreases and the vehicle's reference point Pref approaches the target driving line Ltgt, the vehicle driving support device 10 maintains the position of the target driving line Ltgt at that point in time if the driver's steering torque TQ_D is greater than the target change end threshold TQ_E.

[0105] In addition, the target change end threshold TQ_E is set to a value smaller than the target hold start threshold TQ_L.

[0106] On the other hand, when the driver's steering torque TQ_D decreases and reaches the target change termination threshold TQ_E, the vehicle driving support device 10 ends the maintenance of the target driving line Ltgt's position and begins to change the position of the target driving line Ltgt. When starting to change the position of the target driving line Ltgt, the vehicle driving support device 10 changes (returns) the position of the target driving line Ltgt by gradually moving the target driving line Ltgt toward the lane center line LNC.

[0107] For example, such as Figure 5B As shown, if the vehicle 100 is traveling to the right of the lane center line LNC during lane keeping control and the driver's steering torque TQ_D decreases to reach the target change end threshold TQ_E, then the vehicle driving support device 10 begins to change the position of the target driving line Ltgt, changing the position of the target driving line Ltgt by gradually moving it to the left towards the lane center line LNC.

[0108] At this time, the vehicle driving support device 10 sets the position of the lane center line LNC as the target position and changes the position of the target driving line Ltgt in a way that makes the target driving line Ltgt reach the target position.

[0109] Furthermore, at this time, the vehicle driving support device 10 sets an appropriate speed (predetermined change speed) as the speed at which the position of the target driving line Ltgt is changed, and changes the position of the target driving line Ltgt at this predetermined change speed. The vehicle driving support device 10 sets the predetermined change speed, for example, based on parameters such as the distance between the changing target driving line Ltgt and the vehicle's reference point Pref, and the distance between the changing target driving line Ltgt and the target position. More specifically, the vehicle driving support device 10 sets the predetermined change speed by filtering parameters such as the distance between the changing target driving line Ltgt and the vehicle's reference point Pref, and the distance between the changing target driving line Ltgt and the target position using a first-order filter, a time-variable filter, etc.

[0110] Additionally, the vehicle driving support device 10 can also preset an upper limit value for the predetermined change speed, and limit the predetermined change speed to that upper limit value if the predetermined change speed is greater than the upper limit value. For example, the vehicle driving support device 10 can also limit the predetermined change speed by making the slope (inclination) of the change in position of the target travel line Ltgt relative to the time axis below a certain slope. That is, the predetermined change speed can also be set by making the shape of the trajectory of the change in position of the target travel line Ltgt relative to the time axis a predetermined shape.

[0111] Furthermore, during the period when the position of the target driving line Ltgt is changed, the vehicle driving support device 10 also outputs a system steering torque TQ_S from the steering device 23 corresponding to the "amount of divergence D between the changing target driving line Ltgt and the vehicle reference point Pref".

[0112] Furthermore, when the final target driving line Ltgt aligns with the lane center line LNC, the vehicle driving support device 10 terminates the change in the position of the target driving line Ltgt and maintains the target driving line Ltgt in that position. Thereafter, the vehicle 100 travels along the target driving line Ltgt set at the lane center line LNC.

[0113] For example, such as Figure 5C As shown, when the final target driving line Ltgt aligns with the lane center line LNC, the vehicle driving support device 10 terminates the change in the position of the target driving line Ltgt and maintains the target driving line Ltgt in that position. Therefore, thereafter, as... Figure 5D As shown, this vehicle 100 is traveling along the target driving line Ltgt set at the center line LNC of the lane.

[0114] According to the vehicle driving support device 10, for example, Figure 6 As shown, the position of the target driving line Ltgt is changed according to the driver's steering torque TQ_D.

[0115] exist Figure 6 In the example shown, the driver's steering torque TQ_D begins to increase from time t60. At this time, the target driving line Ltgt is set at a position aligned with the lane center line LNC. Subsequently, until time t61 when the driver's steering torque TQ_D reaches the target hold-start threshold TQ_L, the driver's steering torque TQ_D remains lower than the target change start threshold TQ_C. Therefore, the target driving line Ltgt remains aligned with the lane center line LNC.

[0116] Furthermore, when the driver's steering torque TQ_D increases and reaches the target change initiation threshold TQ_C at time t61, the position of the target travel line Ltgt begins to move to the right. Thereafter, until time t62 when the driver's steering torque TQ_D reaches the target hold initiation threshold TQ_L, the driver's steering torque TQ_D remains above the target change initiation threshold TQ_C. Therefore, the position of the target travel line Ltgt continues to move to the right before time t62.

[0117] Then, when the driver's steering torque TQ_D decreases and reaches the target hold start threshold TQ_L at time t62, the movement of the target travel line Ltgt to the right stops. Afterwards, until the driver's steering torque TQ_D reaches the target change start threshold TQ_C at time t63, the driver's steering torque TQ_D remains below the target hold start threshold TQ_L and above the target change end threshold TQ_E. Therefore, the position of the target travel line Ltgt remains at the position at time t62 during the period from time t62 to time t63.

[0118] Subsequently, when the driver's steering torque TQ_D increases and reaches the target change initiation threshold TQ_C at time t63, the position of the target travel line Ltgt begins to move to the right. Then, until time t64 when the driver's steering torque TQ_D reaches the target hold initiation threshold TQ_L, the driver's steering torque TQ_D remains above the target change initiation threshold TQ_C. Therefore, the position of the target travel line Ltgt continues to move to the right until time t64.

[0119] Then, when the driver's steering torque TQ_D decreases and reaches the target hold start threshold TQ_L at time t64, the movement of the target travel line Ltgt to the right stops. Afterwards, until the driver's steering torque TQ_D reaches the target change end threshold TQ_E at time t65, the driver's steering torque TQ_D remains below the target hold start threshold TQ_L and above the target change end threshold TQ_E. Therefore, the position of the target travel line Ltgt remains at the position at time t64 during the period from time t64 to time t65.

[0120] Then, when the driver's steering torque TQ_D further decreases and reaches the target change end threshold TQ_E at time t65, the position of the target driving line Ltgt begins to move to the left. After that, the position of the target driving line Ltgt continues to move to the left until at time t66 the target driving line Ltgt is aligned with the lane center line LNC.

[0121] Furthermore, when the target travel line Ltgt aligns with the lane center line LNC at time t66, the movement of the target travel line Ltgt stops.

[0122] <Effect>

[0123] The above is a summary of the operation of the vehicle driving support device 10. Therefore, when the driver moves the vehicle 100 laterally from the target driving line Ltgt during lane keeping control, the target driving line Ltgt moves from the lane center line LNC in the same direction, thus reducing the driver's steering torque TQ_D required for the vehicle 100 to travel straight at the position desired by the driver. Furthermore, when the vehicle 100 is traveling straight at the position desired by the driver, the target driving line Ltgt is set between the lane center line LNC and the vehicle reference point Pref. Therefore, to a certain extent, the system steering torque TQ_S based on lane keeping control is applied to the vehicle 100, making it easier for the driver to recognize that "lane keeping control is being executed (lane keeping control is being performed)".

[0124] Therefore, according to the vehicle driving support device 10, when the driver drives the vehicle 100 to the right or left of the lane center line LNC during lane keeping control, it is easy for the driver to recognize that "lane keeping control is being executed", and the driver's steering torque TQ_D required by the driver is smaller.

[0125] <The specific operation of vehicle driving support devices>

[0126] Next, the specific operation of the vehicle driving support device 10 will be explained. When lane keeping control is required, the CPU of the ECU 90 of the vehicle driving support device 10 executes a predetermined calculation cycle. Figure 7 The example shown. Therefore, when the predetermined timing occurs, the CPU... Figure 7 The routine shown begins processing at step 700, which leads to step 705, where it is determined whether the deviation amount D is greater than zero.

[0127] If the CPU determines "yes" in step 705, the process proceeds to step 710, which determines whether the vehicle's reference point Pref is deviated to the right from the target driving line Ltgt.

[0128] If the CPU determines "yes" in step 710, the process proceeds to step 715, whereby it calculates the system steering torque TQ_S required to turn the vehicle 100 left and return the vehicle's reference point Pref to the target driving line Ltgt. Next, the CPU proceeds to step 720, sending a steering torque output command to the steering device 23, causing the system steering torque TQ_S calculated in step 715 to be output from the steering device 23. Then, the CPU proceeds to step 795, temporarily terminating the processing of this routine.

[0129] On the other hand, if the CPU determines "no" in step 710, it proceeds to step 725 to calculate the system steering torque TQ_S required to turn the vehicle 100 to the right and return the vehicle's reference point Pref to the target driving line Ltgt. Next, the CPU proceeds to step 730, sending a steering torque output command to the steering device 23, causing the system steering torque TQ_S calculated in step 725 to be output from the steering device 23. Then, the CPU proceeds to step 795, temporarily terminating the processing of this routine.

[0130] On the other hand, if the CPU determines "no" in step 705, the process will proceed directly to step 795, temporarily ending the processing of this routine.

[0131] Furthermore, when lane-keeping control is required, the CPU executes the operation in a predetermined computation cycle. Figure 8The example shown. Therefore, when the predetermined timing occurs, the CPU... Figure 8 The routine shown begins processing at step 800, which leads to step 805, where it is determined whether the target change start condition is met. The target change start condition is that the driver's steering torque TQ_D is above the target change start threshold TQ_C.

[0132] If the CPU determines "yes" in step 805, it proceeds to step 810 to change the position of the target travel line Ltgt by moving it toward the vehicle's reference point Pref. Then, the CPU proceeds to step 895, temporarily terminating the processing of this routine.

[0133] On the other hand, if the CPU determines "no" in step 805, the process proceeds to step 815 to determine whether the target hold start condition is met. The target hold start condition is that after the driver's steering torque TQ_D becomes above the target change start threshold TQ_C, the driver's steering torque TQ_D decreases to reach the target hold start threshold TQ_L, and the driver's steering torque TQ_D is below the target hold start threshold TQ_L but greater than the target change end threshold TQ_E.

[0134] If the CPU determines "yes" in step 815, it proceeds to step 820, maintaining the position of the target travel line Ltgt at the point where the driver's steering torque TQ_D decreases to reach the target holding start threshold TQ_L. Then, the CPU proceeds to step 895, temporarily terminating the processing of this routine.

[0135] On the other hand, if the CPU determines "no" in step 815, the process proceeds to step 825 to determine whether the target holding termination condition is met. The target holding termination condition is that the driver's steering torque TQ_D decreases to reach the target change termination threshold TQ_E, and the driver's steering torque TQ_D remains below the target change termination threshold TQ_E, and the target driving line Ltgt is inconsistent with the lane center line LNC.

[0136] If the CPU determines "yes" in step 825, it proceeds to step 830 to change the position of the target driving line Ltgt so that it aligns with the lane center line LNC. Then, the CPU proceeds to step 895, temporarily terminating the processing of this routine.

[0137] On the other hand, if the CPU determines "no" in step 825, it proceeds to step 835 to set the target driving line Ltgt in a manner that aligns it with the lane center line LNC. Then, the CPU proceeds to step 895, temporarily terminating the processing of this routine.

[0138] The above describes the specific operation of the vehicle driving support device 10.

[0139] Furthermore, the present invention is not limited to the above-described embodiments, and various modifications can be adopted within the scope of the present invention.

Claims

1. A vehicle driving support device, wherein the vehicle driving support device performs lane keeping control by autonomously steering the vehicle while it is traveling within its own lane. The vehicle driving support device, during the execution of lane keeping control, sets the centerline passing through the center of the vehicle's drivable width within the lane as the target driving line, and performs autonomous steering by moving the vehicle's reference point along the target driving line. The vehicle driving support device is configured such that, when the driver performs a steering operation to control the vehicle during lane keeping control, if the driver's steering force exceeds a target change initiation threshold, the target driving line is changed to a lower line between the center line and the vehicle's reference point. This lower line is obtained by multiplying the distance from the center line towards the vehicle's reference point by a coefficient greater than 0 and less than 1. The vehicle driving support device is configured such that, after the driver's steering force becomes above the target change start threshold and a change in the position of the target driving line begins, when the driver's steering force decreases to the target hold start threshold, the change in the position of the target driving line is stopped, and the position of the target driving line is maintained at the position at the time point when the steering force decreases to the target hold start threshold.

2. The vehicle driving support device according to claim 1, wherein, The vehicle driving support device is configured such that when the steering force is reduced to the target hold start threshold and the position of the target driving line is maintained at the position at the time point when the steering force is reduced to the target hold start threshold, the position of the target driving line is changed in such a way that the target driving line is aligned with the center line when the steering force becomes below the target change end threshold, which is set to a value smaller than the target hold start threshold.

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