Lane Keeping Control Device

Abstract

Lane keeping control device for performing lane keeping control to guide a carrier vehicle towards a target guidance point defined on a lane in which the carrier vehicle is traveling, comprising the lane keeping control device: a track width detection unit that is designed to detect the track width of the lane; an interruption unit that is configured to interrupt the lane keeping control when the lane width detection unit detects that the lane width is gradually increasing during lane keeping control; a turn signal operation detection unit designed to detect that a turn signal of the carrier vehicle is being operated; and a prevention unit that is set up to prevent the interruption unit from interrupting the lane keeping control in order to continue the lane keeping control in a case of a specific condition in which the lane width detection unit detects that the lane is gradually increasing, and the turn signal operation detection unit does not detect that the turn signal is being operated, characterized by the fact that the target guidance point is set at a midpoint between the left and right sides of the track width, which is detected by the track width detection unit, and The lane keeping control in this specific state continues by setting the target guidance point based on a lane width at a position further away than a position in a normal state.

Description

TECHNICAL AREA

[0001] The technology revealed here relates to a lane keeping control device. TECHNICAL BACKGROUND

[0002] The number of vehicles, particularly motor vehicles, that employ torque assist for lane keeping while driving is increasing. Such torque assist is designed to perform steering in the opposite direction (i.e., towards a centered position) to a lane deviation, thus assisting lane keeping and preventing lane deviation. Steering effort in the direction where torque assist is used for lane keeping is reduced, and thus the driver is naturally guided back to the centered position. Naturally, the strength of the torque assist is limited within a range that the driver can manage without being prevented from actively steering to change lanes.

[0003] In such a lane-keeping control system, a camera or similar device is typically used to detect the lane width of the lane in which the host vehicle or carrier vehicle is traveling. A target guidance point is then set so that the carrier vehicle travels along a path formed by connecting the midpoints of the detected lane widths.

[0004] During lane keeping control, the lane ahead in which the vehicle is traveling might branch off (e.g., fork). In this case, the lane width detected by the lane width detection unit gradually increases at the branching section. It is proposed to interrupt the lane keeping control if the lane width gradually increases in this way because the vehicle is on the branching section and it is unclear which road the driver intends to travel on if no turn signal is activated (see patent document 1).

[0005] Further teachings relevant to the prior art, which also deal with the technology considered here, can be cited in patent documents 2 to 7. LIST OF REFERENCES, PATRONAGE DOCUMENT Patent document 1: JP 2015 - 115 040 A Patent document 2: DE 10 2014 225 752 A1; Patent document 3: DE 10 2007 051 260 A1; Patent document 4: DE 11 2011 100 180 B4; Patent document 5: DE 60 2004 008 541 T2; Patent document 6: US 2011 / 0 010 021 A1; Patent Document 7: JP 2008 – 268 157 A DISPLAY TECHNICAL PROBLEM

[0006] The lane-keeping assist system abruptly stops working as the lane width gradually increases due to a junction often doesn't reflect the driver's intentions. Most junctions are secondary roads leading off a main road. The driver of a vehicle using lane-keeping assist on the main road usually intends to continue on the main road. If they intend to turn onto the secondary road, they will typically use a turn signal to exit the main road.

[0007] The technology disclosed herein was developed taking into account the above circumstances, and one of its objectives is to provide a lane keeping control device capable of continuing lane keeping control as far as possible as the lane width gradually increases. PRESENTATION OF THE INVENTION

[0008] To solve this problem, the technology disclosed herein employs the following solution. In particular, the device disclosed herein is a lane keeping control device or lane keeping assistant for performing lane keeping control to guide a carrier vehicle towards a target guidance point defined on a lane in which a carrier vehicle is traveling, wherein the lane keeping control device comprises: a lane width detection unit configured to detect the lane width of a lane; an interruption unit configured to interrupt the lane keeping control when the lane width detection unit detects that the lane width is gradually increasing during lane keeping control; a turn signal operation detection unit configured to detect that a turn signal of the carrier vehicle is being operated; and a prevention unit configured to prevent the interruption unit fromThe lane keeping control is interrupted in order to resume it in a specific condition where the lane width detection unit detects that the lane width is gradually increasing, and the turn signal operation detection unit does not detect that the turn signal is being activated. According to the embodiment of the invention, the target guidance point is set at a midpoint between the left and right sides of the lane width detected by the lane width detection unit, and the lane keeping control is continued in this specific condition by setting the target guidance point at a position further away than it would be in a normal state. In this case, the lane keeping control can continue further away than the section where the lane width gradually increases.

[0009] The solution described above can provide more options for implementing lane keeping assist. Lane keeping assist continues as long as the turn signal is not activated. In other words, lane keeping assist does not continue when changing lanes. This prevents unintentional lane keeping assist activation by the driver.

[0010] Possible embodiments based on the above solution, which are not part of the invention, are described below.

[0011] A non-inventive track width detection unit detects a distance, as a track width, between the left and right white lines of the lane.

[0012] A lane width detection unit (not according to the invention) detects a distance, as a lane width, between the left and right white lines of the lane; the target guidance point is set at a midpoint between the left and right sides of the lane width detected by the lane width detection unit; and if the left or right white line of the lane is a dotted line segment, the lane keeping control continues in that specific state by considering the other of the white lines as a reference and setting the target guidance point. In this case, the other of the white lines is effectively used in such a way that the lane keeping control can continue.

[0013] A lane width detection unit (not according to the invention) detects a distance, as a lane width, between the left and right white lines of the lane; the target guidance point is set at a midpoint between the left and right sides of the lane width detected by the lane width detection unit; and if the left or right white line of the lane is a dotted line segment, the lane keeping control continues in that specific state by considering the dotted line segment as a reference and setting the target guidance point. In this case, the dotted line is effectively used in such a way that the lane keeping control can continue.

[0014] A storage unit (not according to the invention) is provided, configured to store the track width detected by the track width detection unit immediately before the track width increases, and the lane keeping control in this specific state is continued by setting the target guidance point based on the track width stored in the storage unit. In this case, the track width detected immediately before the track width increases is effectively used to allow the lane keeping control to continue.

[0015] In addition to the lane keeping control device according to claim 1, a lane keeping control device for performing lane keeping control to guide a carrier vehicle towards a target guidance point is claimed, wherein the target guidance point is defined on a lane in which a carrier vehicle is traveling, wherein the lane keeping control device comprises: a lane width detection unit configured to detect the lane width of a lane; an interruption unit configured to interrupt the lane keeping control when the lane width detection unit detects that the lane width is gradually increasing during the lane keeping control; a turn signal operation detection unit configured to detect that a turn signal of the carrier vehicle is being operated;and a prevention unit configured to prevent the interruption unit from interrupting the lane keeping control in order to continue the lane keeping control in a specific condition in which the lane width detection unit detects that the lane is gradually increasing, and the turn signal operation detection unit does not detect that the turn signal is being activated. According to this embodiment of the invention according to claim 2, the lane keeping control device is characterized in that the lane width detection unit detects a distance, as a lane width, between the left and right white lines of the lane; the target guidance point is set at a midpoint between the left and right sides of the lane width detected by the lane width detection unit;And if the left or right white line of the lane is a dotted line segment, lane keeping control continues by setting the target guidance point based on a lane width immediately before the dotted line segment and a lane width immediately after the dotted line segment. In this case, the dotted line and the lane width immediately before the dotted line segment are effectively used to allow lane keeping control to continue.

[0016] A lane keeping control device not according to the invention comprises a camera configured to capture an image of the front of the carrier vehicle; a turn signal switch configured to detect a turn signal operation performed by a driver; and a controller configured to perform lane keeping control, wherein the controller receives a signal of an image captured by the camera and outputs a control signal to an electric power steering device to guide the carrier vehicle towards a target guidance point defined on the lane in which the carrier vehicle is currently traveling, based on the signal from the image.The controller interrupts the lane keeping control when it detects that the lane is gradually increasing, based on the image captured by the camera during lane keeping control, and the controller prevents an interruption of the lane keeping control in order to continue the lane keeping control in a specific state in which the controller detects that the lane is gradually increasing, based on the image captured by the camera during lane keeping control, and the controller does not receive a turn signal operating signal from the turn signal switch. ADVANTAGES OF THE INVENTION

[0017] The technology revealed here can provide increased possibilities for implementing lane keeping control. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a block diagram showing an example of a vehicle control system comprising a lane keeping control device. Fig. Figure 2 is a diagram to illustrate a sketch of a lane keeping control system. Fig. Figure 3 is a flowchart showing a control process of an example of a lane keeping control system. DESCRIPTION OF EXECUTION FORMS

[0018] Fig. Figure 1 is a block diagram showing the control system of a vehicle (for example, a passenger car) with a lane keeping assist device. As shown in the figure, the control system includes a controller (control unit) U, which uses a microcomputer. Signals from a vehicle speed sensor 1, a yaw rate sensor 2, a steering angle sensor 3, a camera 4 that captures an image of the front of the vehicle, a turn signal switch 5, and map data (a navigation device) 6 are input to the controller U. The controller U controls an electric power steering device 11 during lane keeping assist. The camera 4 detects white lines (lane markings) that are the boundaries on both sides of the lane in which the vehicle is traveling.

[0019] Fig. Figure 2 represents a situation in which a vehicle V is traveling as a carrier vehicle on a main road 20. The main road 20 has a single lane on one side. The lane in which the vehicle V is traveling is indicated by reference numeral 21. The opposite lane is indicated by reference numeral 22. A center line between lanes 21 and 22 is indicated by reference numeral 23. Lane 21 is defined by center line 23 as one white line and the other white line 21a. Lane 22 is defined by center line 23 as one white line and the other white line 22a.

[0020] Main road 20 curves to the right in front of vehicle V. A side road 30 branches off from the immediate vicinity of the beginning of this curve; this side road is almost straight in relation to main road 20. Side road 30 is defined by a left white line 30a and a right white line 30b. Side road 30 has a single lane. Its width is narrower than that of main road 20.

[0021] A dotted line 41 is planned at the boundary between main road 20 and junction 30 (shown). The dotted line 41 is depicted along the center line 23. In other words, the dotted line 41 turns right along the curve of the center line 23 to serve as an extension of the white line 21a on the left side of lane 21, and to indicate an entrance to junction 30.

[0022] Before the dotted line 41, the camera of vehicle V recognizes the width of lane 21 as a lane width H1, which is the space between the center line 23 and the white line 21a. The center position of this lane width H1 is used as the target guidance point, thus enabling lane keeping control.

[0023] Near the boundary with the junction road 30, the track gauge is H2. The center line 23 and a section of the extended white line 30a of the junction road 30 are recognized as a single track gauge. The track gauge H2 gradually increases from one side closer to vehicle V to the other farther away from vehicle V over a length that corresponds to the dotted line 41. A track gauge in a section further away than the dotted line 41 is recognized as H3. This track gauge H3 is generally the same as the track gauge H1.

[0024] When the lane width gradually increases, as shown by lane width H2, the lane keeping control in patent document 1 is stopped (interrupted). In the technology disclosed here, even if the lane width gradually increases, as shown by lane width H2, the vehicle continues to travel on main road 20 (lane 21) and the lane keeping control then resumes if no turn signal is used or activated, or if no turn signal is used for the left direction to change to the branch road 30.

[0025] The continuation of lane keeping control for driving in lane 21 is explained. In this embodiment, the target guidance point along the center line 23 with track width H1 is defined as a single track width before the dotted line 41, and the lane keeping control is continued. It is noted that the lane keeping control can be implemented, for example, using the prior art techniques disclosed in patent document 1, unexamined Japanese patent applications No. 2016-011060 and No. 2016-148893, filed by the applicant of this application.

[0026] A concrete example of the lane keeping control system revealed here is given with reference to a [document / document] in [reference]. Fig. The flowchart shown in section 3 explains this. In the following explanation, Q represents a step. First, in step Q1, it is determined whether a LAS switch (a manually operated switch that determines whether lane keeping assist is activated) (not shown) is turned on. If the determination in Q1 is NO, lane keeping assist is not activated, and the process starts again.

[0027] If the determination in Q1 is YES, signals from sensors 1 to 6 are read in Q2. Then, in Q3, a target driving line is determined based on the lane. Fig. 2 corresponds to the target lane, a line between the vehicle V and the lane guidance point. The lane guidance point is the midpoint between the center line 23 and the white line 21a. In addition to the exact midpoint, the midpoint includes positions close to the midpoint: positions deviating towards the center line 23 and positions deviating towards the white line 21a. After Q3, in Q4, steering torque assistance is applied to drive along the target lane, thus executing lane keeping control.

[0028] After Q4, Q5 will determine whether the track width gradually increases. In other words, in Fig. 2. The track width H2 is detected. If the determination in Q5 is NO, the process reverses, i.e., the process continues with lane keeping control. If the determination is YES, a track width that is positioned just before the track width begins to gradually increase is stored in Q6. In other words, in Fig. 2. The track gauge H1 is stored.

[0029] After Q6, Q7 determines whether a branch road exists on a section where the lane width gradually increases, based on the map data. If Q7 determines yes, Q8 determines whether the turn signal (a direction indicator) is not activated. If Q8 determines yes, Q9 determines the destination lane based on the center line 23 and the lane width stored in Q6. In other words, the lane is determined, with the destination point being the midpoint between the center line 23 and the stored lane width. Then, Q10 executes lane keeping control, ensuring the vehicle travels along the destination lane determined in Q9. Fig. 2. The lane keeping control continues for driving on lane 21 of main road 20.

[0030] If the determination in Q7 is NO, or the determination in Q8 is NO, the lane keeping control is stopped in Q11. It is noted that after Q11, the lane keeping control is restarted when the lane width on which the vehicle V is now traveling is clearly confirmed. In this case, the lane keeping control can be restarted under the condition that a driver's intention to restart is confirmed, e.g., a restart switch is turned on.

[0031] The following is conceivable in addition to the embodiment described above, if the track width gradually increases and the lane keeping control continues.

[0032] (1) Lane keeping control can be continued with the distance between the center line 23 and the dotted line 41 as the lane width. In other words, the dotted line 41 is considered one of the white lines for control purposes.

[0033] (2) The lane keeping control can continue, assuming a predetermined track width along the dotted line 41 (for example, assuming track width H, which is positioned directly in front of the dotted line 41).

[0034] (3) The lane keeping control may continue, assuming a track gauge that is slightly further away than the dotted line 41 (the track gauge H3 in Fig. 2).

[0035] (4) The lane keeping control can be continued assuming a track width (for example, assuming an arithmetic mean of the track widths, or in particular assuming a track width that is half the sum of H1 and H3 in Fig. 2 is) based on the track gauge positioned immediately before the dotted line 41 (the track gauge H1 in Fig. 2) and the track gauge positioned directly after the dotted line 41 (the track gauge H3 in Fig. 2).

[0036] Although the embodiment described above, the technology disclosed herein is not limited to the embodiment described above, but can be appropriately modified within the scope of protection described in the claims. For example, assuming that the lane width gradually increases and it can be determined based on the map data that the road currently being driven on is a main road with a wider width than a road located near the currently driven road, it can be determined that the main road is a road that a driver intends to travel on, so that the lane keeping control continues. The lane width can be controlled using the approach as well as with the white lines and the dotted lines.The purpose of the technique disclosed herein is not limited to what is specifically stated, but also implicitly includes providing for what is expressed as substantially preferred or advantageous. INDUSTRIAL APPLICABILITY

[0037] The technology revealed here can ensure a sufficient means of executing the vehicle's lane keeping control. REFERENCE MARK LIST U Controller 1 vehicle speed sensor 2 Yaw speed sensors 3 Steering angle sensor 4 cameras 5 turn signal switches 6 Map data (navigation device) V vehicle 20 Main Street 21 lanes 21a white line 22 lanes 22a white line 23 Center boundary line 30 Junction 30a white line 30b white line 41 dotted line H1 gauge (positioned directly in front of the dotted line) H2 gauge (gradually increasing) H3 gauge (positioned directly after the dotted line)

Claims

[1] A lane keeping control device for performing lane keeping control for guiding a host vehicle toward a target guidance point set on a lane on which the host vehicle is traveling, the lane keeping control device comprising: a track width detection unit configured to detect a track width of the lane; an interruption unit configured to interrupt the lane keeping control when the lane width detection unit detects that the lane gradually increases during the lane keeping control; a turn signal operation detection unit configured to detect that a turn signal of the host vehicle is being operated; and a prevention unit configured to prevent the interruption unit from interrupting the lane keeping control to continue the lane keeping control in a case of a specific state in which the lane width detection unit detects that the lane is gradually increasing and the turn signal operation detection unit does not detect that the turn signal is being operated, characterized by , that the guidance point is set at a middle position between left and right sides of the track width detected by the track width detection unit, and the lane keeping control in the specific state is continued by setting the guidance point based on a lane width at a position farther away than a position of a normal state. [2] A lane keeping control device for performing lane keeping control for guiding a host vehicle toward a target guidance point set on a lane on which the host vehicle is traveling, the lane keeping control device comprising: a track width detection unit configured to detect a track width of the lane; an interruption unit configured to interrupt the lane keeping control when the lane width detection unit detects that the lane gradually increases during the lane keeping control; a turn signal operation detection unit configured to detect that a turn signal of the host vehicle is being operated; and a prevention unit configured to prevent the interruption unit from interrupting the lane keeping control to continue the lane keeping control in a case of a specific state in which the lane width detection unit detects that the lane is gradually increasing and the turn signal operation detection unit does not detect that the turn signal is being operated, characterized by , that the lane width detection unit detects a distance, as a lane width, between left and right white lines of the lane, the guidance point is set at a middle position between left and right sides of the track width detected by the track width detection unit, and when the left or right white line of the lane is a dotted line section, the lane keeping control continues in the specific state based on a lane width immediately before the dotted line section and a lane width immediately after the dotted line section.

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