Lane departure prevention system

Abstract

To provide a lane deviation prevention device which can effectively reduce a risk that a vehicle and a trailer will deviate from a lane by determining the risk that the vehicle and the trailer will deviate from the lane under the consideration of the size of the trailer.SOLUTION: A lane deviation prevention device 100 includes: a target information acquisition device 13 which acquires information on a target around a vehicle 60; and a control unit 10 which executes lane deviation prevention control so as to reduce a risk when determining that there is the risk that the vehicle exceeds a deviation determination reference line on the basis of the information acquired by the target information acquisition device. The control unit is configured to change the deviation determination reference line so as to easily determine that there is the risk when the vehicle 60 tows a trailer as compared with when the vehicle does not tow the trailer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lane departure prevention device for vehicles such as automobiles.

Background Art

[0002] A lane departure prevention device detects the position of a vehicle with respect to a lane, and when it is determined that there is a risk that the vehicle will deviate from the lane based on the detected position of the vehicle, at least one of lane departure prevention control such as issuing an alarm and automatically steering the steering wheels is executed.

[0003] A vehicle may tow a trailer. When the vehicle tows a trailer, the vehicle turns more widely when traveling on a curve than when it does not tow a trailer. Therefore, as described in Patent Document 1 below, for example, when a vehicle tows a trailer and travels on a curve, a lane departure allowance on the outside of the curve is calculated, and lane departure prevention control is executed while allowing departure up to the allowance. A lane departure prevention device is known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] 〔Problems to be Solved by the Invention〕 When a vehicle tows a trailer, depending on the size of the trailer, the trailer may deviate from the lane even if the vehicle does not deviate from the lane. In the conventional lane departure prevention device as described above, lane departure prevention control is executed without considering the size of the trailer, so the risk of the trailer deviating from the lane cannot be effectively reduced.

[0006] The present invention provides a lane departure prevention device that can effectively reduce the risk of a vehicle and trailer deviating from their lane compared to conventional devices by determining the risk of the vehicle and trailer deviating from their lane, taking into account the size of the trailer.

[0007] [Means for solving the problem and the effects of the invention] According to the present invention, a lane departure prevention device (100) is provided, which includes a target information acquisition device (13) that acquires information about targets around a vehicle (60), and a control unit (LDA·ECU10) that, when it is determined based on the information acquired by the target information acquisition device that there is a risk that the vehicle will cross a departure judgment reference line (76), executes lane departure prevention control (S100) to reduce the risk.

[0008] The control unit (LDA·ECU10) is used when the vehicle (60) is towing the trailer (80) When a vehicle is approaching a deviation judgment reference line (76), if the target information acquisition device (13) determines, based on the information acquired, that another vehicle is located in a predetermined area (70) located to the rear and side of the vehicle on the side of the deviation judgment reference line, lane departure prevention control is executed to suppress the vehicle from approaching the deviation judgment reference line (S130). It is structured in such a way.

[0009] According to the above configuration, the vehicle tows the trailer. When a vehicle is approaching a lane departure detection line, and the target information acquisition device determines, based on the information acquired by the vehicle, that another vehicle is located in a predetermined area to the rear and side of the lane departure detection line relative to the vehicle, lane departure prevention control is executed to suppress the vehicle from approaching the lane departure detection line. Therefore, it is possible to suppress the vehicle from moving in a direction that approaches the deviation judgment reference line while towing the trailer, thus reducing the risk of the vehicle and trailer colliding with other vehicles in the predetermined area compared to a case where the vehicle's approach to the deviation judgment reference line is not suppressed. It can be reduced.

[0010] [Aspects of the Invention] In one embodiment of the present invention, The control unit (LDA·ECU10) is more likely to determine that the above risk exists when the vehicle (60) is towing the trailer (80) compared to when the vehicle is not towing the trailer. Deviation judgment reference line (76) Change ruyo It is structured in such a way. According to the above embodiment, when a vehicle is towing a trailer, the lane departure detection baseline is changed to make it easier to determine that the above-mentioned risk exists compared to when the vehicle is not towing a trailer. Therefore, because it is easier to determine that the above-mentioned risk exists, lane departure prevention control can be executed earlier when a vehicle is towing a trailer compared to when the vehicle is not towing a trailer. Consequently, the risk of the vehicle and trailer deviating from the lane can be reduced more effectively than in the conventional method. This invention other In one embodiment, the control unit (LDA·ECU10) is configured to change the deviation judgment reference line (76) so that the greater the difference between the two widths, the closer the deviation judgment reference line (76) gets to the center of the lane (64) when the width (W2) of the trailer (80) is greater than the width (W1) of the vehicle (60) (S60).

[0011] According to the above embodiment, when the width of the trailer is greater than the width of the vehicle, the deviation detection reference line is changed so that the greater the difference between the two widths, the closer the deviation detection reference line is to the center of the lane. Therefore, compared to the case where the deviation detection reference line is not changed so that the greater the difference between the two widths, it is possible to more easily determine that there is a risk of the vehicle and trailer crossing the deviation detection reference line.

[0012] Furthermore, the deviation detection baseline may be modified, for example, to move closer to the center of the lane by half the difference between the two widths.

[0016] In another embodiment of the present invention, the control unit (LDA·ECU10) is configured to variably set the length of a predetermined region (70) based on the length of the trailer (S50), such that the length of the predetermined region (70) increases as the length of the trailer (L2) increases.

[0017] According to the above embodiment, the length of the predetermined area is variably set based on the length of the trailer, such that the length of the predetermined area increases as the length of the trailer increases. Therefore, compared to the case where the length of the predetermined area is constant, the risk of the vehicle and trailer colliding with other vehicles in the predetermined area can be reduced even when the trailer is long.

[0018] In another embodiment of the present invention, the control unit (LDA·ECU10) is configured to determine the positional relationship between the front and rear corners of the trailer (80) and the vehicle based on information acquired by the target information acquisition device (13) when the vehicle (60) is towing the trailer (80), and to calculate the width (W2) and length (L2) of the trailer based on the positional relationship (S230~S290).

[0019] According to the above aspect, when the vehicle is traveling while towing a trailer, based on the information acquired by the target information acquisition device, the positional relationship between the front end corner and the rear end corner of the trailer with respect to the vehicle is specified, and the width and length of the trailer are calculated based on this positional relationship. Therefore, information on the width and length of the trailer can be acquired based on the information acquired by the target information acquisition device, and the necessity of acquiring information on the width and length of the trailer before the vehicle starts traveling while towing the trailer can be eliminated.

[0020] In the above description, in order to assist in understanding the present invention, names and / or symbols used in the embodiments are added in parentheses to the components of the invention corresponding to the embodiments described later. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and / or symbols added in parentheses. Other objects, other features, and attendant advantages of the present invention will be easily understood from the description of the embodiments of the present invention described while referring to the following drawings.

Brief Description of the Drawings

[0021] [Figure 1] It is a schematic configuration diagram showing an embodiment of a lane departure prevention device according to the present invention. [Figure 2] It is a flowchart showing a lane departure prevention control routine in an embodiment. [Figure 3] It is a flowchart showing a trailer width and length calculation control routine in an embodiment. [Figure 4] It is a diagram showing a situation where the vehicle is traveling while tilted with respect to the longitudinal direction of the lane. [Figure 5] It is a diagram showing a predetermined area (A) when not towing and a predetermined area (B) when towing. [Figure 6] It is a diagram showing a situation where the vehicle is traveling while towing a trailer and making a curve.

Modes for Carrying Out the Invention

[0022] An embodiment of the lane departure prevention device according to the present invention will be described in detail below with reference to the attached diagrams.

[0023] <Structure> As shown in Figure 1, the lane departure prevention device 100 according to this embodiment is applied to a vehicle 60 and comprises a lane departure prevention ECU 10, an electric power steering ECU 20, a drive ECU 40, and a braking ECU 50. In this specification, lane departure prevention is referred to as LDA (Lane Departure Alert with Control) as needed, and electric power steering is referred to as EPS (Electric Power Steering) as needed.

[0024] These ECUs are Electric Control Units (ECCUs) that primarily consist of a microcomputer and are connected to each other via a Controller Area Network (CAN) 62, enabling them to send and receive information. Each microcomputer includes a CPU, ROM, RAM, non-volatile memory, and interfaces. The CPU implements various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs may be integrated into a single ECU.

[0025] As will be explained in detail later, the ROM of the LDA·ECU10 stores a program for lane departure prevention control corresponding to the flowchart shown in Figure 2, and the CPU executes lane departure prevention control according to this program. In addition, the ROM of the LDA·ECU10 stores a program for calculating the width and length of the trailer, corresponding to the flowchart shown in Figure 3, and the CPU executes calculating the width and length of the trailer according to this program.

[0026] The LDA ECU 10 is connected to a camera sensor 12, a radar sensor 14, an LDA switch 16, a warning device 18, and a display device 19. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 13 that acquires information about targets around the vehicle 60. The vehicle 60 is an autonomous vehicle, and lane departure prevention control may be performed when the autonomous driving mode is deactivated.

[0027] The camera sensor 12 includes a plurality of camera devices, each camera device comprising a camera unit and a recognition unit that analyzes image data captured by the camera unit to recognize landmarks such as road markings and other vehicles. The camera sensor 12 supplies information about the recognized landmarks to the LDA / ECU 10 at predetermined intervals. In this embodiment, the camera sensor 12 includes door mirror cameras installed on the left and right door mirrors 62 of the vehicle 60 to photograph the rear and side of the vehicle (see Figure 6).

[0028] As shown in Figure 4, the camera sensor 12 recognizes the white lines 66L and 66R, which are the boundaries of the lane 64 (referred to as lane boundaries), and can detect the positional relationship of the vehicle relative to the lane 64 based on the relationship between the white lines and the position of the vehicle 60. Here, the position of the vehicle 60 is the position of the vehicle's center of gravity 60A, but it may also be the center position in a plan view of the vehicle. The lateral position of the vehicle, which will be described later, represents the position of the center of gravity in the lane width direction, and the lateral speed of the vehicle represents the speed of the center of gravity in the lane width direction. These are determined based on the relative positional relationship between the white lines and the vehicle detected by the camera sensor 12.

[0029] The radar sensor 14 includes multiple radar devices, each of which is equipped with a radar transceiver and a signal processing unit (not shown). The radar transceiver emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by three-dimensional objects (e.g., other vehicles, bicycles, etc.) within its emission range. The signal processing unit supplies information representing the relative distance and relative speed between the vehicle and the three-dimensional object, and the relative position (direction) of the three-dimensional object to the vehicle, to the driver assistance ECU 10 at predetermined intervals, based on the phase difference between the emitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the emission of the millimeter waves to the reception of the reflected waves. LiDAR (Light Detection And Ranging) may be used instead of the radar sensor 14.

[0030] The LDA switch 16 is operated by the driver and supplies a signal to the LDA ECU 10 indicating whether it is on or off. When the LDA switch 16 is on, it means that lane departure prevention control is being performed.

[0031] The warning device 18 is activated when the LDA ECU 10 determines that there is a risk of the vehicle 60 deviating from the lane 64, and issues a warning as one of the lane departure prevention control measures, that is, a warning that there is a risk of the vehicle 60 deviating from the lane. The warning device 18 may be a warning device that emits a visual warning such as a warning lamp, a warning device that emits an auditory warning such as a warning buzzer, or a warning device that emits a tactile warning such as seat vibration, or any combination thereof.

[0032] The display device 19 displays the control status by the LDA / ECU 10, etc. The display device 19 may be, for example, a head-up display or a multi-information display that displays meters and various information, or it may be a display for a navigation system.

[0033] The EPS / ECU 20 controls the EPS device 22, thereby steering the steering wheels 24 as needed. Therefore, the EPS / ECU 20 and the EPS device 22 constitute an automatic steering system 26 that automatically steers the steering wheels 24 as needed. When the LDA / ECU 10 determines that there is a risk of the vehicle 50 deviating from its lane, the EPS / ECU 20 automatically steers the steering wheels 24 to prevent the vehicle from deviating from its lane, as another lane departure prevention control.

[0034] As shown in Figure 1, a torque sensor 32 for detecting steering torque Ts is provided on the steering shaft 30, to which the steering wheel 28 operated by the driver is integrally connected. The signal indicating the steering torque Ts detected by the torque sensor 32 is input to the EPS-ECU 20. Based on the steering torque Ts and the vehicle speed V detected by a vehicle speed sensor (not shown), the EPS-ECU 20 controls the steering assist torque by controlling the EPS device 22 in a manner known in the art, thereby reducing the driver's steering burden. The signal indicating the steering torque Ts is input from the EPS-ECU 20 to the LDA-ECU 10 via CAN 62.

[0035] The drive ECU 40 is connected to a drive unit 42 that accelerates the vehicle 60 by applying driving force to the drive wheels, which are not shown in Figure 1. Under normal circumstances, the drive ECU 40 controls the drive unit 42 so that the driving force generated by the drive unit 42 changes in accordance with the driver's driving operation, and when it receives a command signal from the LDA·ECU 10, it controls the drive unit 42 based on the command signal. The drive unit 42 may be any drive unit known in the art.

[0036] The braking ECU 50 is connected to a braking device 52 that decelerates the vehicle 60 by applying braking force to the wheels, which are not shown in Figure 1. Under normal circumstances, the braking ECU 50 controls the braking device 52 so that the braking force generated by the braking device 52 changes in accordance with the driver's braking operation. When it receives a command signal from the LDA·ECU 10, it performs automatic braking by controlling the braking device 52 based on the command signal.

[0037] <Lane Departure Prevention Control Routine> Next, the lane departure prevention control routine in the embodiment will be described with reference to the flowchart shown in Figure 2. The lane departure prevention control according to the flowchart shown in Figure 2 is repeatedly executed by the CPU of the LDA·ECU10 at a predetermined control cycle when the LDA switch 16 is ON. In the following description, the lane departure prevention control will be simply referred to as "this control".

[0038] First, in step S10, the CPU determines whether or not the vehicle 12 is towing the trailer 80, as shown in Figure 5(B). If the CPU determines that it is in the correct position, it proceeds to step S30; if it determines that it is in the correct position, it proceeds to step S20. In Figures 5(B) and 6, 82 indicates a coupling device that connects the rear end of the vehicle 60 to the front end of the trailer 80.

[0039] In step S20, the CPU sets a predetermined area 70 located in the lane 68 adjacent to the lane 64 in which the vehicle 12 is traveling, and which is located to the rear and side of the vehicle 12, as shown in Figure 5(A), as the area 72 for when the vehicle is not towed. If there are adjacent lanes on both sides of lane 64, the predetermined area is set in both adjacent lanes.

[0040] In step S30, the CPU determines whether flag F is 1, that is, whether the width W2 and length L2 (see Figure 6) of the trailer 80 are known. The width W2 and length L2 are calculated according to the flowchart shown in Figure 3, as described later. If the CPU makes a positive determination, it proceeds to step S50; if it makes a negative determination, it proceeds to step S40. Flag F is initialized to 0 at the start of this control and thereafter remains at 0 or is set to 1 according to the flowchart shown in Figure 3, as described later.

[0041] In step S40, the CPU sets the predetermined area 70 to the standard area 74 during towing, as shown in Figure 5(B). In contrast, in step S50, the CPU changes the length Lp of the predetermined area 70 according to the length L2 of the trailer 80, such that the length Lp of the predetermined area 70 increases as the length L2 of the trailer 80 increases.

[0042] In step S60, the CPU determines whether the width W2 of the trailer 80 is greater than the width W1 of the vehicle 12. If the CPU determines that it is greater than the width W2 of the trailer 80, it proceeds to step S80; if it determines that it is greater than the width W1 of the trailer 80, it proceeds to step S70.

[0043] In step S70, the CPU sets the deviation judgment reference line 76 (see Figure 4) to a preset standard position. In contrast, in step S80, the CPU changes the position of the deviation judgment reference line so that it moves closer to the center of the lane by (W2-W1) / 2 from the preset standard position; in other words, the greater the difference between the two widths, the closer the deviation judgment reference line moves to the center of the lane. Note that in Figure 4, the deviation judgment reference line 76 is located outside the white lines 66L and 66R, which are the boundaries of the lane 64, but the deviation judgment reference line 76 may also be located inside or on the white lines 66L and 66R.

[0044] In step S90, the CPU determines, based on the relative position of the vehicle 60 with respect to the lane detected by the camera sensor 12, whether or not there is a risk of the vehicle deviating from the lane, in a manner known in the art. If the CPU determines that there is a risk, it proceeds to step S110; if it determines that there is a risk, it proceeds to step S100.

[0045] In this case, the determination of whether or not there is a risk of the vehicle 60 deviating from the lane may be made, for example, in the following manner. First, as shown in Figure 4, the angle θy of the direction of travel 60B of the vehicle with respect to the longitudinal direction 64A of the lane 64 is estimated based on the image information in front of the vehicle 60. The angle θy is a positive value when the direction of travel 60B of the vehicle 60 is to the right of the longitudinal direction 64A of the lane 64. The speed Vy of the vehicle 60 moving in a direction perpendicular to the longitudinal direction 64A of the lane 64 is estimated as Vsinθy based on the angle θy and the vehicle speed V.

[0046] Furthermore, the distance Dy (not shown) in the lane width direction between the lane departure judgment reference line 76 on the side the vehicle 60 is approaching and the vehicle's center of gravity is estimated. In addition, if Δt is a predetermined time, and Dy-VyΔt is less than or equal to a predetermined reference value Dyc (a positive constant), it may be determined that there is a risk of the vehicle 60 deviating from the lane.

[0047] Furthermore, if the turn signal lever (not shown in Figure 1) is in the activated position, or if the driver is performing a lane change steering operation, it is determined that the driver has an intention to deviate from the lane, and therefore it is determined that there is no risk of lane departure.

[0048] In step S100, the CPU performs lane departure prevention control to reduce the risk of the vehicle 60 deviating from its lane. Specifically, the CPU activates the warning device 18 to issue a warning that the vehicle 60 is likely to deviate from its lane, and displays this information on the display device 19. Furthermore, if the risk of lane departure increases, the CPU outputs an automatic steering command signal to the EPS / ECU 22, causing the EPS device 22 to automatically steer the steering wheels 24 to prevent the vehicle 60 from deviating from its lane.

[0049] In step S110, the CPU determines whether the vehicle 60 and trailer 80 are making a lane change without turning. If the CPU determines it is not, it terminates this control; if it determines it is, it proceeds to step S120. Note that the vehicle 60 and trailer 80 may be determined to be making a lane change without turning if no steering operation is performed in which the absolute value of the steering angle θ is greater than or equal to the steering judgment reference value (a positive constant), and the vehicle 60 and trailer 80 are gradually moving laterally to the lane so as to cross the lane boundary.

[0050] In step S120, the CPU determines whether or not another vehicle is present in the predetermined area 70. If the CPU determines that no other vehicle is present, it terminates this control; if it determines that no other vehicle is present, it proceeds to step S130.

[0051] In step S130, the CPU performs lane departure prevention control in the same manner as in step S100 to reduce the risk of the vehicle 60 and trailer 80 crossing the lane boundary. In this case, the display device 19 may display a message such as, "There is a following vehicle to the rear and side, so changing your line of sight is dangerous."

[0052] <Trailer width and length calculation control routine> Next, the trailer width and length calculation control routine will be explained with reference to the flowchart shown in Figure 3. The control shown in the flowchart in Figure 3 is repeatedly executed by the CPU of the LDA·ECU10 at a predetermined control cycle when the LDA switch 16 is ON and flag F is 0. In the following explanation, the trailer width and length calculation control will be simply referred to as "this calculation control".

[0053] First, in step S210, the CPU determines whether or not a trailer has been detected. If the CPU determines that the trailer has not been detected, it terminates this calculation control; if it determines that the trailer has not been detected, it proceeds to step S220. For example, if the trailer 80 is being photographed by the camera sensor 12 that photographs the rear of the vehicle, it may be determined that the trailer has been detected.

[0054] In step S220, the CPU determines whether the driver has input information regarding the width W2 and length L2 (see Figure 6) of the trailer 80. If the CPU determines that the information has been entered, it proceeds to step S300; if it determines that the information has been entered, it proceeds to step S230.

[0055] In step S230, the CPU determines whether the absolute value of the steering angle θ is less than or equal to the reference value θ0 (a positive constant) for determining whether the vehicle 60 and trailer 80 are substantially in a straight-ahead state. If the CPU makes a negative determination, it proceeds to step S250; if it makes a positive determination, it proceeds to step S240.

[0056] In step S240, the CPU calculates the width W2 of the trailer 80. For example, the direction of the front corner of the trailer 80 relative to the rear corner of the vehicle 60 is determined based on the image of the front corner of the trailer taken by the camera sensor 12 that photographs the rear of the vehicle. Also, the distance from the rear corner of the vehicle 60 to the front corner of the trailer 80 is determined based on the detection result by the radar sensor 14 provided at the rear corner of the vehicle 60. Furthermore, the width W2 of the trailer is calculated based on the direction of the front corner of the trailer relative to the rear corner of the vehicle 60 and the distance from the rear corner of the vehicle 60 to the front corner of the trailer.

[0057] In step S250, the CPU determines whether the absolute value of the steering angle θ is greater than or equal to the lower limit criterion value θ1 (a positive constant greater than θ0) for curve driving determination and less than or equal to the upper limit criterion value θ2 (a positive constant greater than θ1) for curve driving determination. If the CPU determines it is negative, it terminates this control; if it determines it is positive, it proceeds to step S260.

[0058] Alternatively, instead of determining the absolute value of the steering angle θ, it may be determined whether the absolute value of the hitch angle φ is greater than or equal to the lower limit reference value φ1 (a positive constant) and less than or equal to the upper limit reference value φ2 (a positive constant greater than φ1). The hitch angle φ is the angle formed by the longitudinal centerline 60B of the vehicle 60 and the longitudinal centerline 80A of the trailer 80 (see Figure 6).

[0059] In step S260, the CPU determines the position P21 of the front corner of the trailer 80 based on the detection results from the camera sensor 12 installed on the door mirror 62 of the vehicle 60 and the radar sensor 14 provided at the rear corner of the vehicle 60, as shown in Figure 6.

[0060] In step S270, the CPU estimates the hitch angle φ based on the steering angle θ. If a hitch angle sensor is provided, the hitch angle φ may be the value detected by the hitch angle sensor.

[0061] In step S280, as shown in Figure 6, the CPU determines the direction of the rear corner of the trailer 80 relative to the vehicle 60 based on the detection results from the camera sensor 12 installed on the door mirror 62 of the vehicle 60. Furthermore, the CPU determines the position P22 of the rear corner of the trailer 80 based on the direction of the rear corner of the trailer 80 relative to the vehicle 60, the width W2 of the trailer 80, and the hitch angle φ. In Figure 6, the dashed line indicated by reference numeral 12 shows an example of the boundary of the imaging range by the camera sensor 12 installed on the door mirror 62.

[0062] In step S290, the CPU calculates the length L2 of the trailer based on the center P11 of the coupling device 82 that connects the front end of the trailer 80 to the rear end of the vehicle 60, the position P12 of the rear end corner of the vehicle 60, the position P21 of the front end corner of the trailer 80, and the position P22 of the rear end corner of the trailer 80.

[0063] Note that if the width W2 of the trailer 80 has already been calculated, steps S230 and S240 are omitted. Similarly, if the length L2 of the trailer 80 has already been calculated, steps S250 to S290 are omitted.

[0064] In step S300, the CPU sets flag F to 1 and terminates this arithmetic control.

[0065] As can be seen from the above explanation, according to the embodiment, when the vehicle 60 is towing the trailer 80 (step S10), the lane departure judgment reference line is changed to make it easier to determine that the vehicle is likely to cross the lane departure judgment reference line 76 compared to when the vehicle is not towing the trailer (step S80). Therefore, since it is easier to determine that the above risk exists, lane departure prevention control (step S100) can be executed earlier when the vehicle is towing the trailer compared to when the vehicle is not towing the trailer. Accordingly, the risk of the vehicle and trailer deviating from the lane can be reduced more effectively than in the conventional method.

[0066] Furthermore, according to the embodiment, when the width W2 of the trailer 80 is greater than the width W1 of the vehicle 60 (step S60), the deviation judgment reference line 76 is changed so that the greater the difference between the two widths (W2-W1), the closer the deviation judgment reference line 76 is to the center of the lane 64. Therefore, compared to the case where the deviation judgment reference line is not changed so that the greater the difference between the two widths, it is possible to more easily determine that there is a risk of the vehicle and trailer crossing the deviation judgment reference line.

[0067] In particular, in this embodiment, the deviation detection line 76 is modified to move closer to the center of the lane by half (W2-W1) / 2 of the difference between the two widths. Therefore, the deviation detection line 76 can be moved closer to the center of the lane without being excessive or insufficient in accordance with the difference between the two widths.

[0068] Furthermore, according to the embodiment, when a vehicle 60 is towing a trailer 80 and approaching a departure judgment reference line 76, and the object information acquisition device 13 determines that another vehicle is present in a predetermined area 70 located to the rear and side of the vehicle on the side of the departure judgment reference line, lane departure prevention control (step S130) is executed to suppress the vehicle from approaching the departure judgment reference line.

[0069] Therefore, since it is possible to suppress the vehicle from moving in a direction that approaches the deviation judgment reference line while towing the trailer, the risk of the vehicle and trailer colliding with other vehicles in the predetermined area can be reduced compared to the case where the vehicle's approach to the deviation judgment reference line is not suppressed.

[0070] Furthermore, according to the embodiment, the length of the predetermined area is variably set based on the length of the trailer so that the length Lp of the predetermined area 70 increases as the length L2 of the trailer 80 increases (step S50). Therefore, compared to the case where the length of the predetermined area is constant, the risk of the vehicle and trailer colliding with other vehicles in the predetermined area can be reduced even when the length of the trailer is long.

[0071] Furthermore, according to the embodiment, when the vehicle 60 is towing the trailer 80, the positional relationship between the front and rear corners of the trailer and the vehicle is determined based on the information acquired by the target information acquisition device 13, and the width W2 and length L2 of the trailer are calculated based on this positional relationship (steps S210 to S290). Therefore, information on the width and length of the trailer can be obtained based on the information acquired by the target information acquisition device, eliminating the need to acquire information on the width and length of the trailer before the vehicle starts towing the trailer.

[0072] In particular, in this embodiment, the trailer width W2 is calculated based on information acquired by the target information acquisition device 13 when the vehicle 60 is towing the trailer 80 and traveling substantially in a straight line (steps S210 to S240). Therefore, since information on the hitch angle φ is not required, the trailer width W2 can be calculated more easily and accurately compared to the case where the trailer width W2 is calculated based on information acquired by the target information acquisition device 13 when the vehicle 60 is towing the trailer 80 and traveling around a curve.

[0073] Although the present invention has been described in detail above with respect to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the embodiments described above, and that various other embodiments are possible within the scope of the present invention.

[0074] For example, in the above embodiment, in step S80, the position of the deviation judgment reference line is changed so that the deviation judgment reference line moves closer to the center of the lane by (W2-W1) / 2 relative to a preset standard position. However, by reducing the reference value Dyc in the judgment in step S90 by, for example, (W2-W1) / 2, an equivalent process may be performed to change the position of the deviation judgment reference line so that the greater the difference (W2-W1) between the width W2 of the trailer 80 and the width W1 of the vehicle 12, the closer the deviation judgment reference line moves to the center of the lane.

[0075] Furthermore, in the above-described embodiment, in steps S110 to S130, lane departure prevention control is performed when the vehicle 60 and trailer 80 change lanes without turning towards another vehicle when another vehicle is present to their rear and side. However, lane departure prevention control in the case of a lane change without turning, i.e., steps S40, S50 and steps S110 to S130, may be omitted. In that case, steps S250 to S290 of the flowchart shown in Figure 3 may also be omitted.

[0076] Furthermore, in the above-described embodiment, the width W2 and length L2 of the trailer 80 are calculated based on the detection results of the camera sensor 12 that photographs the rear of the vehicle, the radar sensor 14 provided at the rear end corner of the vehicle 60, and the camera sensor 12 installed on the door mirror 62. However, the width W2 and length L2 of the trailer 80 may be calculated in any manner known in the art. For example, the position P21 of the front end corner and the position P22 of the rear end corner of the trailer 80 may be determined based on the detection results of a plurality of camera sensors provided on the vehicle 60.

[0077] In the above-described embodiment, the trailer width W2 is calculated based on information acquired by the target information acquisition device 13 when the vehicle 60 is towing the trailer 80 and traveling substantially in a straight line. However, the trailer width W2 may also be calculated based on information acquired by the target information acquisition device 13 and the hitch angle φ when the vehicle 60 is towing the trailer 80 and traveling around a curve.

[0078] Furthermore, in the above-described embodiment, in steps S60 to S80, if the vehicle 12 is towing a trailer 80 and the width W2 of the trailer 80 is greater than the width W1 of the vehicle 12, the position of the deviation judgment reference line is changed to move closer to the center of the lane by (W2-W1) / 2. However, steps S60 to S80 may be omitted.

[0079] Furthermore, in the above-described embodiment, lane departure prevention control includes the activation of the warning device 18 to issue a warning, display on the display device 19, and automatic steering by the EPS device 22. However, at least one of the following may be omitted: the issuance of a warning, display on the display device 19, and automatic steering. [Explanation of Symbols]

[0080] 10...Lane Departure Prevention ECU, 12...Camera Sensor, 13...Target Information Acquisition Device, 14...Laser Sensor, 18...Warning Device, 20...Electric Power Steering ECU, 22...EPS Device, 24...Steering Wheel, 40...Drive ECU, 42...Drive System, 50...Brake ECU, 52...Brake System, 64...Lane, 68...Adjacent Lane, 70...Designated Area, 76...Departure Judgment Reference Line, 80...Trailer, 100...Lane Departure Prevention Device

Claims

1. A lane departure prevention device includes a target information acquisition device that acquires information about targets around a vehicle, and a control unit that, when it is determined based on the information acquired by the target information acquisition device that there is a risk that the vehicle will cross a departure judgment reference line, executes lane departure prevention control to reduce the risk, The control unit is configured to perform lane departure prevention control in such a way that when the vehicle is towing a trailer and approaching the departure judgment reference line, and the control unit determines, based on information acquired by the target information acquisition device, that another vehicle is present in a predetermined area located to the rear and side of the departure judgment reference line relative to the vehicle, the vehicle is prevented from approaching the departure judgment reference line.

2. A lane departure prevention device according to claim 1, wherein the control unit is configured to change the departure determination reference line when the vehicle is towing the trailer, to make it easier to determine that the risk of departure is present compared to when the vehicle is not towing the trailer.

3. A lane departure prevention device according to claim 2, wherein the control unit is configured to change the departure judgment reference line when the width of the trailer is greater than the width of the vehicle, such that the greater the difference between the two widths, the closer the departure judgment reference line is to the center of the lane.

4. A lane departure prevention device according to claim 1, wherein the control unit is configured to variably set the length of the predetermined area based on the length of the trailer, such that the length of the predetermined area increases as the length of the trailer increases.

5. A lane departure prevention device according to claim 4, wherein the control unit is configured to determine the positional relationship between the front and rear corners of the trailer and the vehicle based on information acquired by the target information acquisition device when the vehicle is towing the trailer, and to calculate the width and length of the trailer based on the positional relationship.

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