Lane departure prevention system

Abstract

To provide a lane departure prevention device that is less likely to interfere with the driver's intentional steering actions. [Solution] The lane departure prevention device (DS) performs a lane departure prevention operation that automatically steers the steering wheels to prevent the vehicle from deviating from its lane when a predetermined starting condition is met that is met when there is a possibility that the vehicle may deviate from its lane. The lane departure prevention device determines whether a specific condition is met that is met when there is a possibility that a moving object may suddenly enter the lane from outside the lane. If the lane departure prevention device determines that the specific condition is met, it will not perform the lane departure prevention operation even if the starting condition is met.

Description

Technical Field

[0001] The present invention relates to a lane departure prevention device that executes lane departure prevention control for preventing (restraining) the host vehicle from deviating from its own lane, which is the lane in which the host vehicle is traveling.

Background Art

[0002] When a conventional lane departure prevention device predicts that the host vehicle will deviate from the traveling road (its own lane) beyond the boundary of the traveling road, and there is an object (e.g., a pedestrian) outside the boundary, the device controls the host vehicle so that the maximum movement position when the host vehicle moves to the deviating side is "a position closer to the traveling road side than the boundary" (see Patent Document 1). Thereby, contact between the object existing outside the boundary and the host vehicle can be avoided.

Prior Art Documents

Patent Documents

[0003] <好

Patent Document 1

Summary of the Invention

[0004] When the driver of the host vehicle recognizes that there may be a moving object (e.g., a pedestrian) jumping out into the lane (i.e., its own lane) in which the host vehicle is traveling, the driver changes the position of the host vehicle to a position closer to the center of the road on which the host vehicle is traveling. That is, in this case, the driver steers the host vehicle so as to deviate from its own lane to the oncoming lane. However, since a conventional lane departure prevention device performs a lane departure prevention operation (automatic steering) even in such a case, the driver of the host vehicle may feel bothered by the lane departure prevention operation.

[0005] The present invention has been made to solve such problems. That is, one object of the present invention is to provide a lane departure prevention device that has a low possibility of hindering the driver's intentional steering operation in the above-described case.

[0006] One embodiment of the lane departure prevention device according to the present invention is: The system includes a controller (10) that, when a predetermined starting condition is met (step 510: Yes) which is established when there is a possibility that the vehicle may deviate from its own lane, performs a lane departure prevention operation (step 550) by automatically steering the steering wheels of the vehicle in its own lane to prevent the vehicle from deviating from its own lane.

[0007] Furthermore, the controller, If a specific condition is met that is likely to occur when a moving object is about to jump out of the lane into the lane from outside the lane (steps 320, 330, and 380), the system is configured to suppress the lane departure prevention operation (steps 390 and 540: No). Suppression of the lane departure prevention operation can be achieved by not performing the lane departure prevention operation (step 540: No). Furthermore, when a specific condition is met, suppression of the lane departure prevention operation can be achieved by changing the override threshold to a smaller value (steps 640, 530, 535, and 525: No).

[0008] In this configuration, if a driver perceives a high probability of a moving object suddenly appearing in their lane and steers their vehicle away from the lane towards the center of the road, that steering action is less likely to be hindered by the function of the lane departure prevention device. Therefore, the likelihood of the driver finding the lane departure prevention action bothersome can be reduced.

[0009] In the above description, to aid in understanding the present invention, the names and / or reference numerals used in the embodiments described later are indicated in parentheses for the components of the invention corresponding to those embodiments. However, the components of the present invention are not limited to the embodiments defined by the above names and / or reference numerals. The present invention also extends to lane departure prevention methods and programs thereof. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a lane departure prevention device according to the first embodiment of the present invention. [Figure 2] Figure 1 is a diagram illustrating the operation of the lane departure prevention device. [Figure 3] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 4] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 5] This is the routine executed by the CPU of the driver assistance ECU shown in Figure 1. [Figure 6] This is a routine executed by the CPU of the driver assistance ECU according to the second embodiment of the present invention. [Modes for carrying out the invention]

[0011] (First Embodiment) The "lane departure prevention device DS (hereinafter referred to as "first device DS")" according to the first embodiment of the present invention has the components shown in Figure 1 and is applied to (mounted on) the vehicle HV. The vehicle HV may be any of the following: a vehicle powered by an internal combustion engine, a vehicle powered by an electric motor (i.e., an electric vehicle), and a hybrid vehicle.

[0012] In this specification, "ECU" refers to an electronic control unit (control device) equipped with a microcomputer. The microcomputer includes a CPU (processor), ROM, RAM, writable non-volatile memory, and interfaces, etc. An ECU is also referred to as a controller or computer. The multiple ECUs shown in Figure 1 are connected to each other via a CAN (Controller Area Network) so that they can exchange information. Some or all of these multiple ECUs may be integrated into a single ECU.

[0013] The driver assistance ECU 10 performs lane departure prevention control, as described later. The driver assistance ECU 10 is connected to the components described below (camera, sensors, switches, ECUs, and devices, etc.) and transmits and receives information or signals between them. The driver assistance ECU 10 may be composed of multiple ECUs.

[0014] The vehicle surrounding sensors 20 include a front camera 21, a front radar 22, a rear camera 23, a left rear radar 24, and a right rear radar 25.

[0015] The front camera 21 captures the scene in front of the vehicle HV at predetermined intervals and acquires forward image data. The driver assistance ECU 10 recognizes the "left boundary line LL and right boundary line RL" on the road based on the forward image data (see Figure 2). The boundary lines are lane markings (e.g., white lines). The area between the left boundary line LL and the right boundary line RL is the lane in which the vehicle HV is traveling (i.e., the vehicle's lane HL).

[0016] Furthermore, the driver assistance ECU 10 can acquire the "lane width RW of the vehicle's own lane HL, approach distance Ds, and yaw angle θ" shown in Figure 2, based on forward image data. The approach distance Ds is the distance from the reference point P on the vehicle HV to the boundary line on the side from which the vehicle HV is about to deviate from its own lane HL. The reference point P on the vehicle HV is the center point between the left front wheel and the right front wheel of the vehicle HV. For convenience, the side from which the vehicle HV is about to deviate from its own lane HL is referred to as the "deviation side". The yaw angle θ is the angle formed between the direction of the boundary line and the longitudinal axis direction of the vehicle HV (i.e., the direction in which the vehicle HV is facing). Furthermore, the driver assistance ECU 10 calculates the "deviation margin distance Dy (=Ds+Df)" as the sum of the approach distance Ds and a predetermined correction distance Df. The correction distance Df may be "0", a positive value, or a negative value.

[0017] In addition, the driver assistance ECU 10 can acquire information about objects located in front of the vehicle HV based on forward image data (i.e., forward camera object information). The forward camera object information includes the position of the object relative to the vehicle HV and the type of object.

[0018] The front radar 22 acquires information about an object located in front of the host vehicle HV (i.e., front radar information) using radio waves in the millimeter wave band. The front radar information includes the position of the object relative to the host vehicle HV (i.e., the distance between the host vehicle HV and the object and the azimuth of the object with respect to the host vehicle HV) and the relative speed of the object.

[0019] The driving support ECU 10 generates front fusion object information by integrating the front camera object information and the front radar information.

[0020] The rear camera 23 captures an image of the scene behind the host vehicle HV every time a predetermined time elapses and acquires rear image data. The driving support ECU 10 acquires information about an object located behind the host vehicle HV (i.e., rear camera object information) based on the rear image data. The rear camera object information includes the position of the object relative to the host vehicle HV and the type of the object.

[0021] The left rear radar 24 acquires information about an object located in the left rear and rear of the host vehicle HV (i.e., left rear radar information) using radio waves in the millimeter wave band. The right rear radar 25 acquires information about an object located in the right rear and rear of the host vehicle HV (i.e., left rear radar information) using radio waves in the millimeter wave band. The driving support ECU 10 generates rear fusion object information by integrating the rear camera object information, the left rear radar information, and the right rear radar information.

[0022] The vehicle state sensor 30 includes a vehicle speed sensor 31, a steering angle sensor 32, and a steering torque sensor 33. The vehicle speed sensor 31 outputs a signal indicating the speed of the host vehicle HV (i.e., the vehicle speed) Vh. The steering angle sensor 32 outputs a signal indicating the steering angle Sa of the host vehicle HV. The steering torque sensor 33 outputs a signal indicating the steering torque Tq of the host vehicle HV. The steering torque Tq is the torque applied to the steering mechanism by the driver of the host vehicle HV operating a steering wheel (not shown).

[0023] The driver monitor ECU 40 is connected to a driver monitor camera 41 that captures the face of the driver of the vehicle's hybrid vehicle at predetermined intervals and acquires facial image data. Based on the facial image data, the driver monitor ECU 40 transmits driver information to the driver assistance ECU 10 indicating the state in which the driver is operating the vehicle's hybrid vehicle.

[0024] The steering motor 50 drives the steering mechanism (not shown) of the vehicle HV in response to instructions from the driver assistance ECU 10, thereby changing the steering angle of the vehicle HV. In other words, when the steering motor 50 is driven, the steering wheels are steered.

[0025] The display device 61 displays a predetermined alarm mark. The speaker 62 emits an alarm sound.

[0026] The communication device 70 communicates with external devices of the vehicle HV (for example, an external server 110, a communication terminal CP carried by a pedestrian PD, communication devices of other vehicles, and roadside devices, etc.) and obtains various information from the external devices. In the following, pedestrians and cyclists will be referred to as "pedestrians, etc.," and other vehicles and motorcycles will be referred to as "other vehicles, etc." Furthermore, movable objects including pedestrians, etc. and other vehicles, etc. may be referred to as "moving objects."

[0027] The navigation ECU 80 is connected to a GPS receiver 81, a map information storage device 82, and a display 83. The navigation ECU 80 estimates the current position of the vehicle HV based on the GPS signal received by the GPS receiver 81. The map information storage device 82 stores map information. The display 83 displays various information.

[0028] (Summary of operation) The first device DS determines the left departure restriction line LD as a line obtained by moving the left boundary line LL by a correction distance Df to the outside (left side) of the vehicle lane HL. The first device DS determines the right departure restriction line RD as a line obtained by moving the right boundary line RL by a correction distance Df to the outside (right side) of the vehicle lane HL. If the first device DS anticipates that the vehicle lane HL will deviate outward (left side) from the left departure restriction line LD, it changes the steering angle of the vehicle lane HL so that the vehicle HV proceeds to the right. If the first device DS anticipates that the vehicle lane HL will deviate outward (right side) from the right departure restriction line RD, it changes the steering angle of the vehicle lane HL so that the vehicle HV proceeds to the left. This operation of changing the steering angle is called the lane departure prevention operation. The control that prevents the vehicle HV from deviating from the vehicle lane HL by the lane departure prevention operation is called the lane departure prevention control.

[0029] When a driver of a hybrid vehicle (HV) is passing through an intersection without traffic lights (IS), if they perceive the possibility of a moving object potentially darting into their lane (HL), they often steer the vehicle to deviate from their lane (HL) into the oncoming lane (OL). However, conventional lane departure prevention systems steer the wheels in a way that counteracts such steering by the driver. Therefore, when the HV approaches an intersection without traffic lights (IS), the first device DS determines that there is a possibility of a moving object, including a pedestrian, darting into the HV's lane (HL) if such an object is present near the intersection (IS). If the first device determines that there is a possibility of a pedestrian darting into the HV's lane (HL), it temporarily suspends or stops the lane departure prevention control (i.e., the lane departure prevention operation). Consequently, the first device DS prevents the driver's intentional steering from being hindered by the lane departure prevention control.

[0030] (Specific operation) The CPU of the driver assistance ECU 10 executes the routines shown in Figures 3 to 5 at predetermined intervals. In the following, "step" will be denoted as "S". The values ​​of each flag described below are set to "0" in an initialization routine (not shown) executed by the CPU when the vehicle's HV is started.

[0031] At a predetermined time, the CPU starts processing from S300 in Figure 3 and proceeds to S310, where it determines whether the value of the lane departure tolerance flag XP is "0".

[0032] If the value of the lane departure tolerance flag XP is "0", the CPU proceeds from S310 to S320 and determines whether the vehicle HV is approaching the target intersection based on the vehicle speed Vh and the "current position and map information of the vehicle HV" obtained via the navigation ECU 80. For example, if it is expected that the vehicle HV will reach the target intersection within a first time threshold (e.g., 5 seconds), the CPU determines that the vehicle HV is approaching the target intersection. The CPU may also determine that the vehicle HV is approaching the target intersection if the distance between the vehicle HV and the target intersection falls within a first distance threshold. The target intersection is the "intersection IS that has a blind spot BA for the vehicle HV and has no traffic lights" as shown in Figure 2. The blind spot BA is also the blind spot for the driver of the vehicle HV.

[0033] If the CPU determines that its own vehicle HV is approaching the target intersection, it proceeds from S320 to S330 and determines, based on the forward fusion object information, whether the lane width RW of its own lane HL is less than or equal to the lane width threshold RWth (for example, 2.5m). In other words, in S330, the CPU determines whether its own vehicle HV is traveling on an urban road where there is a high probability that a moving object will suddenly appear in its own lane HL.

[0034] If the lane width RW is less than or equal to the lane width threshold RWth, the CPU proceeds from S330 to S340 and determines, based on the forward fusion object information, whether or not there is an oncoming lane OL on the road that the vehicle HV is currently traveling on. In other words, the CPU determines whether or not there is enough space to deviate the vehicle HV from its own lane HL.

[0035] If an oncoming lane OL exists, the CPU proceeds from S340 to S350 and determines, based on the forward fusion object information, whether or not there is an oncoming vehicle OV that would obstruct the movement of the vehicle HV when the vehicle HV deviates from its own lane HL into the oncoming lane OL. Specifically, the CPU determines that if the time until the vehicle HV approaches the oncoming vehicle OV closest is within the second time threshold (for example, 8 seconds), then there is an oncoming vehicle OV that would obstruct the movement of the vehicle HV while it is deviating from its lane into the oncoming lane OL.

[0036] If there are no oncoming vehicles (OV) obstructing the lane departure of the HV vehicle, the CPU proceeds from S350 to S360 and determines, based on the rear fusion object information, whether or not there are any other vehicles (i.e., overtaking vehicles) attempting to overtake the HV vehicle. Specifically, the CPU recognizes as overtaking vehicles any other vehicles located behind the HV vehicle that are predicted to catch up to the HV vehicle within a predetermined time.

[0037] If there are no vehicles to overtake, the CPU proceeds from S360 to S370 and determines, based on the driver information, whether the driver of the HV is driving the HV properly. If the driver of the HV is distracted, drowsy, or unconscious, the CPU determines that the driver of the HV is not driving the HV properly.

[0038] If the driver of the vehicle HV is operating the vehicle HV properly, the CPU proceeds from S370 to S380 and determines whether or not a moving object exists in the vicinity of the target intersection (for example, within a predetermined radius (for example, 10m) from the center point Q of the target intersection IS). In this case, the moving object may be a pedestrian or another vehicle, but it may be only a pedestrian. The determination in S380 is made based on information indicating the position of the moving object obtained by communication from an external server 110. Note that the communication terminal CP carried by the pedestrian and the communication device of the other vehicle transmits information that identifies their current position to the server 110. Therefore, the server 110 holds information indicating their current position.

[0039] At this time, the CPU may determine whether or not a moving object exists in the blind spot for the vehicle HV in the vicinity of the target intersection. Information indicating the range of the blind spot for the vehicle HV in the vicinity of the target intersection can be obtained from the vehicle's current position and "map information stored in the map information storage device or information distributed from the server 110". In this case, the condition determined in S380 can be said to be the first condition, which is met when information indicating that a moving object is located in the blind spot for the vehicle HV is obtained.

[0040] Furthermore, in S380, the CPU may also acquire information indicating the direction of movement of moving objects present in the vicinity of the target intersection, and determine whether or not those moving objects are moving toward the current lane HL.

[0041] Furthermore, in S380, the CPU may determine, based on the forward image data, whether or not a moving object is reflected in the convex mirror (i.e., traffic mirror or road mirror) installed in front of the vehicle HV. This also allows the CPU to determine whether or not a moving object exists in the blind spot of the vehicle HV near the target intersection.

[0042] If a moving object is present in the vicinity of the target intersection IS, the CPU proceeds from S380 to S390, sets the value of the lane departure permission flag XP to "1", and then proceeds to S395 to terminate this routine. The fulfillment of all conditions in S320, S330, and S380 means that a specific condition has been met. This specific condition is met when there is a possibility that a moving object may suddenly emerge into the vehicle's lane from a blind spot relative to the vehicle HV.

[0043] On the other hand, if the CPU determines "No" in any of steps S310 to S380, it proceeds directly to S395 from the step in which it determined "No". The conditions determined in S320 and S330 (i.e., the conditions that are met when the lane width of the vehicle's own lane is less than or equal to the lane width threshold and the vehicle is approaching a target intersection that has a blind spot) are also referred to as the "second condition" for convenience.

[0044] At a predetermined time, the CPU starts processing from S400 in Figure 4 and proceeds to S410 to determine whether the value of the lane departure tolerance flag XP is "1". If the value of the lane departure tolerance flag XP is "1", the CPU proceeds from S410 to S420 to determine whether the vehicle HV has passed through the target intersection based on the "current position and map information of the vehicle HV". If the vehicle HV has passed through the target intersection, the CPU proceeds from S420 to S430 and sets the value of the lane departure tolerance flag XP to "0". After that, the CPU proceeds to S495 to provisionally terminate this routine. If the CPU determines "No" in either step S410 or S420, it proceeds directly to S495 from the step in which it determined "No".

[0045] At a predetermined timing, the CPU starts processing from S500 in Figure 5 and proceeds to S505 to determine whether the value of the LDA operation execution flag XLDA is "0". If the value of the LDA operation execution flag XLDA is "0", the CPU proceeds from S505 to S510 to determine whether the conditions for starting the lane departure prevention operation have been met.

[0046] The conditions for initiating the lane departure prevention operation are met when both of the following conditions 1 and 2 are satisfied (i.e., when it is predicted that the vehicle HV will deviate from its own lane HL). (Condition 1) The deviation margin distance Dy is less than or equal to the reference distance Dref. (Condition 2) The yaw angle θ is the angle in which the vehicle HV deviates from its own lane HL by crossing the approach boundary line. The approach boundary line is the boundary line that is closer to the vehicle HV, of the left boundary line LL and the right boundary line RL.

[0047] If the conditions for starting the lane departure prevention operation are not met, the CPU proceeds directly from S510 to S520. Conversely, if the conditions for starting the lane departure prevention operation are met, the CPU proceeds from S510 to S515 and sets the value of the LDA operation execution flag XLDA to "1".

[0048] Next, the CPU proceeds to S520 to determine whether the value of the LDA operation execution flag XLDA is "1". If the value of the LDA operation execution flag XLDA is "0", the CPU proceeds directly from S520 to S595 and terminates this routine. In this case, the lane departure prevention operation (automatic steering to prevent lane departure) is not performed.

[0049] In contrast, if the value of the LDA operation execution flag XLDA is "1", the CPU proceeds from S520 to S525 to determine whether the value of the override flag XOR is "0". If the value of the override flag XOR is "1", the CPU proceeds directly from S525 to S595. In this case as well, the lane departure prevention operation is not performed.

[0050] In contrast, if the value of the override flag XOR is "0", the CPU proceeds from S525 to S530 to determine whether the absolute value of the steering torque Tq is greater than or equal to the override threshold (OR threshold) Tqth. If the absolute value of the steering torque Tq is greater than or equal to the override threshold Tqth, the CPU proceeds from S530 to S535 to set the value of the override flag XOR to "1", and proceeds to S595. In this case as well, the lane departure prevention operation is not performed. The value of the flag XOR is reset to "0" when a predetermined override termination condition is met (for example, when the vehicle HV remains in its own lane HL for a certain period of time or longer).

[0051] In response to this, if the absolute value of the steering torque Tq is not equal to or greater than the threshold Tqth, the CPU proceeds from S530 to S540 to determine whether the value of the lane departure tolerance flag XP is "0".

[0052] If the value of the lane departure tolerance flag XP is "0", the CPU proceeds from S540 to S545 to determine the target torque Tqtgt, which is the target control amount for preventing lane departure. The target torque Tqtgt is calculated to be "a value that directs the vehicle HV toward the center line of the vehicle lane HL". For example, if the vehicle HV is deviating to the left from the left departure restriction line LD, the target torque Tqtgt will be a value corresponding to the steering torque that directs the vehicle HV toward the right. If the vehicle HV is deviating to the right from the right departure restriction line RD, the target torque Tqtgt will be a value corresponding to the steering torque that directs the vehicle HV toward the left. The method of calculating the target torque Tqtgt itself is well known and is disclosed in Japanese Patent Publication No. 2018-79835 and Japanese Patent Publication No. 2020-11562, etc.

[0053] Next, the CPU proceeds to S550, where it drives the steering motor 50 to generate a steering assist torque that matches the target torque Tqtgt. As a result, a "lane departure prevention operation" (i.e., automatic steering to prevent lane departure) is performed to prevent the vehicle HV from deviating from the lane departure restriction line on the side of the deviation. After that, the CPU proceeds to S595.

[0054] In contrast, if the value of the lane departure tolerance flag XP is "1", the CPU proceeds directly from S540 to S595. Therefore, in this case, the lane departure prevention operation is not performed. In other words, when the value of the lane departure tolerance flag XP is "1", the lane departure prevention control is temporarily stopped (suspended).

[0055] By the way, when the CPU proceeds to S505, if the value of the LDA operation execution flag XLDA is "1", the CPU proceeds from S505 to S555 to determine whether or not the conditions for terminating the lane departure prevention operation have been met.

[0056] The lane departure prevention operation terminates when both conditions 3 and 4 are met. (Condition 3) The deviation margin distance Dy is greater than the value obtained by adding a positive value Dm to the reference distance Dref. (Condition 4) The yaw angle θ is in the opposite direction to the direction in which the vehicle HV deviates from its own lane HL by crossing the approach boundary line.

[0057] If the conditions for terminating the lane departure prevention operation are met, the CPU proceeds from S555 to S560 and sets the value of the LDA operation execution flag XLDA to "0". After that, the CPU proceeds to S520. On the other hand, if the conditions for terminating the lane departure prevention operation are not met, the CPU proceeds directly from S555 to S520.

[0058] As explained above, if the specific conditions that apply when there is a possibility that a moving object will suddenly enter the lane from outside the lane are met (see the "Yes" judgments in S320, S330, and S380, and S390), the first device DS will not perform the lane departure prevention operation (S540: No). Therefore, if the driver recognizes that there is a high possibility that a moving object will suddenly enter the lane and steers the vehicle HV away from the lane towards the center of the road, the lane departure prevention operation will be suppressed (i.e., stopped). Thus, such steering by the driver will not be easily hindered by the function of the lane departure prevention device.

[0059] (Second Embodiment) The "lane departure prevention device (hereinafter referred to as the "second device")" according to the second embodiment of the present invention changes the override threshold Tqth and the correction distance Df when certain conditions are met. That is, the CPU of the driver assistance ECU 10 of the second device differs from the CPU of the first device DS in that, in addition to the flowcharts shown in Figures 3 to 5, it executes the routine shown in Figure 6 at predetermined intervals. Note that the CPU of the second device does not perform the processing in S540 in Figure 5, and if it determines "No" in S530, it proceeds to S545.

[0060] At a predetermined time, the CPU starts processing from S600 in Figure 6 and proceeds to S610, where it determines whether the value of the lane departure tolerance flag XP is "1".

[0061] If the value of the lane departure tolerance flag XP is "0", the CPU proceeds from S610 to S620 and sets the value of the override threshold Tqth to the first value (standard value) TqStd. Next, the CPU proceeds to S630 and sets the value of the correction distance Df to the standard distance DfStd. After that, the CPU proceeds to S695 and terminates this routine.

[0062] In contrast, if the value of the lane departure tolerance flag XP is "1", the CPU proceeds from S610 to S640 and sets the value of the override threshold Tqth to the second value TqSmall. The second value TqSmall is smaller than the first value TqStd. Next, the CPU proceeds to S650 and sets the value of the correction distance Df to the expanded distance DfLarge. The expanded distance DfLarge is larger than the standard distance DfStd. After that, the CPU proceeds to S695 and terminates this routine.

[0063] As a result, when the value of the lane departure tolerance flag XP is "1" (i.e., when a specific condition is met), the CPU is more likely to determine "Yes" in S530 of Figure 5. That is, when the magnitude of the driver's steering torque Tq reaches a smaller value than before the specific condition was met (the second value TqSmall), the override flag XOR is set to "1" (S535), and as a result the lane departure prevention operation is not performed (S525: No). Therefore, when a specific condition is met, the lane departure prevention operation is suppressed.

[0064] Furthermore, if the value of the lane departure tolerance flag XP is "1" (i.e., if a specific condition is met), the correction distance Df is set to a larger value than before the specific condition was met (i.e., the expanded distance DfLarge). Therefore, when the specific condition is met, the departure margin distance Dy (=Ds+Df) also becomes larger than when the specific condition is not met. As a result, the CPU becomes less likely to determine "Yes" at S510 in Figure 5. In other words, when the specific condition is met, the conditions for starting the lane departure prevention operation are changed to conditions that are less likely to be met, so the lane departure prevention operation will not start until the vehicle HV deviates significantly from its own lane HL. Therefore, when the specific condition is met, the lane departure prevention operation is suppressed.

[0065] Thus, even with the second device, if the driver perceives a high probability of a moving object suddenly appearing in their lane and steers their vehicle (HV) away from their lane towards the center of the road, that steering action will be less likely to be hindered by the function of the lane departure prevention device.

[0066] The present invention is not limited to the embodiments and modifications described above, and various modifications can be adopted within the scope of the present invention. For example, the present invention is applicable to an autonomous vehicle that has transitioned from autonomous driving to driver-operated driving mode.

[0067] The specific condition was determined to be met when all of the determination conditions in S320, S330, and S380 were met, but the determination condition in S330 is not mandatory. Furthermore, from the routine shown in Figure 3, at least one of the processes from S340 to S370 may be omitted. The first device DS and the second device may be equipped with LiDAR as a vehicle surrounding sensor. The second device does not have to perform the processes in S630 and S650, or it does not have to perform the processes in S620 and S640. Furthermore, the target intersection where it is determined in S320 of Figure 3 whether or not the vehicle is approaching does not necessarily have to have a blind spot for the vehicle. Furthermore, the specific condition only needs to be a condition that is met when there is a possibility that a moving object will suddenly jump into the vehicle's lane, and the moving object does not necessarily have to be located in a blind spot for the vehicle before it suddenly jumps into the vehicle's lane. [Explanation of Symbols]

[0068] 10...Driver assistance ECU, 20...Vehicle surrounding sensors, 30...Vehicle condition sensors, 50...Steering motor.

Claims

1. A lane departure prevention device equipped with a controller that performs a lane departure prevention operation in which, when a predetermined starting condition is met that occurs when there is a possibility that the vehicle may deviate from its own lane, the controller automatically steers the steering wheels of the vehicle in its own lane to prevent the vehicle from deviating from its own lane, The aforementioned controller, The system is configured to suppress the lane departure prevention operation when certain conditions are met, which are conditions that occur when there is a possibility that a moving object will suddenly enter the lane from outside the lane. Lane departure prevention device.

2. In the lane departure prevention device according to claim 1, The aforementioned controller, The system is configured to suppress the lane departure prevention operation by not performing the lane departure prevention operation when the aforementioned specific conditions are met. Lane departure prevention device.

3. In the lane departure prevention device according to claim 1, The aforementioned controller, The system is configured to discontinue the lane departure prevention operation if the magnitude of the steering torque applied by the driver of the vehicle to the steering wheel during the lane departure prevention operation exceeds an override threshold. Furthermore, the controller, The system is configured to suppress the lane departure prevention operation by changing the override threshold to a value smaller than the value before the specified condition was met when the specified condition is met. Lane departure prevention device.

4. In the lane departure prevention device according to claim 1, The aforementioned controller, The system is configured to determine that the specific condition is met when a first condition is met, which is met when information is obtained indicating that the moving object is outside the vehicle's lane and in a blind spot relative to the vehicle. Lane departure prevention device.

5. In the lane departure prevention device according to claim 4, The aforementioned controller, In addition to the first condition, the system is configured to determine that the specific condition is met when the second condition is met, which is met when the lane width of the vehicle is less than or equal to a predetermined lane width threshold and the vehicle is approaching an intersection having a blind spot. Lane departure prevention device.

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