Lane departure prevention system

Abstract

To provide a lane deviation prevention device which does not execute lane deviation suppression control in a state where the lane deviation suppression control has to be restricted, and suppresses lane deviation in a state where the lane deviation is prohibited by regulations.SOLUTION: A lane deviation prevention device includes a control unit that executes at least one type of lane deviation suppression control between warning issuance and automatic steering (S30) when it is determined that the risk or fact of lane deviation of a vehicle exists and a driver does not have an intention to perform the lane deviation (S10, S20), and does not execute the lane deviation suppression control when it is determined that the risk or fact of the lane deviation of the vehicle exists and the driver has an intention to perform the lane deviation. The control unit executes at least warning issuance of the lane deviation suppression control (S80 or S90) when it is determined that a lane on which the vehicle travels is a lane of "no straddling" or "no passing" (S40, S50) even if it is determined that the risk or fact of the lane deviation of the vehicle exists and the driver has an intention to perform the lane deviation (S10, S20).SELECTED DRAWING: Figure 2

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 based on the detected position of the vehicle that there is a risk that the vehicle will deviate from the lane, it performs at least one of lane departure suppression control such as issuing an alarm and automatically steering the steering wheel.

[0003] Even when it is determined that there is a risk that the vehicle will deviate from the lane, if the driver intends to deviate from the lane such as changing lanes, it is necessary to restrict the lane departure suppression control. The presence or absence of the intention to deviate from the lane is determined by the driver's steering operation, the operation of the wiper lever by the driver, the inclination angle of the vehicle with respect to the lane, that is, the skew angle, and the like.

[0004] For example, Patent Document 1 below describes that when a steering speed equal to or higher than a reference value, a steering torque equal to or higher than a reference value, and / or a change amount of the steering torque equal to or higher than a reference value are detected, the lane departure suppression control is restricted. According to this type of lane departure prevention device, in a situation where the driver attempts to deviate from the lane such as changing lanes, it is possible to reduce the risk that the driver will be bothered by unnecessary alarms and the risk that the automatic steering will interfere with the driver's driving operation.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] 〔Problems to be Solved by the Invention〕 In the lane departure prevention device described in Patent Document 1 above, even if there is a risk of the vehicle deviating from its lane when it is traveling in a no-passing zone or no-overtaking zone, if it is determined that the driver has an intention to deviate from the lane, the lane departure suppression control is restricted. Therefore, even though lane departure is prohibited by law, the warning to suppress lane departure and automatic steering are not performed, and thus the lane departure cannot be effectively suppressed so that the vehicle travels in accordance with the law.

[0007] The present invention provides an improved lane departure prevention device that does not perform lane departure prevention control in situations where lane departure prevention control should be restricted, and can suppress lane departure in situations where lane departure is prohibited by law.

[0008] [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 (16) that acquires target information around a vehicle (102), and a control unit (driving support ECU 10) configured to determine whether there is a risk or actual occurrence of lane departure of the vehicle based on the target information acquired by the target information acquisition device, wherein the control unit is configured to perform at least one of lane departure suppression control, such as issuing a warning and automatic steering, when it is determined that there is a risk or actual occurrence of lane departure of the vehicle and the driver does not intend to deviate from the lane (S10, S20), and not perform lane departure suppression control when it is determined that there is a risk or actual occurrence of lane departure of the vehicle and the driver intends to deviate from the lane.

[0009] The control unit (driving support ECU 10) determines that there is a risk or actual fact of the vehicle deviating from its lane and that the driver has the intention to deviate from the lane. In the situation (S10, S20), Based on landmark information, the lane in which the vehicle is traveling is a lane where crossing the line is prohibited or overtaking is prohibited. Furthermore, there is no vehicle ahead of the vehicle. When this is determined (S40, S50, S60), The system issues a warning and performs automatic steering (S80). If, based on the target information, it is determined that the lane the vehicle is traveling in is a no-passing or no-crossing lane and that there is a vehicle ahead of the vehicle (S40, S50, S60), the system issues a warning but does not perform automatic steering (S90). It is structured in such a way.

[0013] the above Configuration According to the system, in situations where there is a risk or actual risk of a vehicle deviating from its lane and the driver is determined to have the intention to deviate from the lane (hereinafter referred to as "the above situation" as needed), if, based on landmark information, it is determined that the lane the vehicle is traveling in is a no-passing or no-exit lane and there is no vehicle ahead of the vehicle, then the system can suppress lane departure by issuing a warning and automatically steering the vehicle to ensure it travels in accordance with the law.

[0014] In contrast, in the above situation, if, based on the landmark information, it is determined that the lane the vehicle is traveling in is a lane where overtaking is prohibited and there is a vehicle ahead of the vehicle, a warning will be issued, but automatic steering will not be performed. Therefore, lane departure can be suppressed by issuing a warning, and the risk of automatic steering interfering with the driver's driving operations can be reduced.

[0015] [Aspects of the Invention] This invention one In one embodiment, the control unit (driving support ECU 10) is configured not to perform lane departure suppression control when it determines, based on landmark information, that the lane in which the vehicle is traveling is neither a lane where crossing is prohibited nor a lane where overtaking is prohibited (S40, S50) in a situation where there is a risk or fact that the vehicle is likely to deviate from its lane and the driver has an intention to deviate from the lane (S10, S20).

[0016] According to the above embodiment, in the above situation, if it is determined based on the landmark information that the lane the vehicle is traveling in is neither a no-passing lane nor a no-passing lane, lane departure prevention control will not be performed. Therefore, the risk of the driver being bothered by unnecessary warnings and the risk of automatic steering interfering with the driver's driving operations can be reduced.

[0017] Furthermore, in another embodiment of the present invention, the control unit (driving support ECU 10) is configured to determine that the driver intends to deviate from the lane when it determines that the turn signal lever is tilted in the direction of lane departure or when it determines that steering operations are being performed in the direction of lane departure (S20).

[0018] According to the above embodiment, when the turn signal lever is tilted in the direction of lane departure or when steering is performed in the direction of lane departure, it can be determined that the driver intends to deviate from the lane.

[0019] Furthermore, in another embodiment of the present invention, the warning includes information that the vehicle is not permitted to deviate from its lane because the lane is a no-passing or no-exit lane (S80, S90).

[0020] According to the above configuration, compared to cases where signs such as "no overtaking" and warnings such as "risk of lane departure" are displayed separately and unrelated to each other, drivers can easily and clearly understand not only that there is a risk of lane departure or that lane departure has occurred, but also the reasons why lane departure is not permitted.

[0021] In this application, "No overtaking" will be referred to as "No overtaking" as needed, and "No overtaking or no overtaking" will be referred to as "No lane departure" as needed.

[0022] In the above description, to aid in understanding the present invention, the names and / or reference numerals used in the embodiments of the invention corresponding to those embodiments are indicated in parentheses. However, the components of the present invention are not limited to the components of the embodiments corresponding to the names and / or reference numerals indicated in parentheses. Other objects, other features, and incidental advantages of the present invention will be readily apparent from the description of embodiments of the present invention, which will be written with reference to the following drawings. [Brief explanation of the drawing]

[0023] [Figure 1] This is a schematic diagram showing a lane departure prevention device according to the first embodiment. [Figure 2] This is a flowchart of the lane departure prevention control routine of the first embodiment. [Figure 3]It is a flowchart showing a lane departure prevention control routine of the second embodiment. [Figure 4] It is a diagram showing a situation where the vehicle runs while being inclined with respect to the longitudinal direction of the lane. [Figure 5] It is a diagram showing a start sign and an end sign of a prohibited overhang section. [Figure 6] It is a diagram showing a start sign and an end sign of a prohibited overtaking section.

Mode for Carrying Out the Invention

[0024] The lane departure prevention device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0025] [First Embodiment] As shown in FIG. 1, a lane departure prevention device 100 according to a first embodiment of the present invention is applied to a vehicle 102 and includes an operation support ECU 10. The vehicle 102 may be a vehicle capable of autonomous driving and includes an electric power steering ECU 20, a meter ECU 30, and a steering ECU 40. An ECU means an electronic control device (Electronic Control Unit) having a microcomputer as a main part. In the following description, the vehicle 102 is referred to as the host vehicle 102 as necessary to distinguish it from other vehicles, and the electric power steering is referred to as EPS.

[0026] The microcomputer of each ECU includes a CPU, a ROM, a RAM, a readable and writable non-volatile memory (N / M), an interface (I / F), and the like. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Further, these ECUs are connected to each other via a CAN (Controller Area Network) 104 so as to be able to exchange data (communicate). Therefore, detection values of sensors (including switches) connected to a specific ECU are also transmitted to other ECUs.

[0027] The driver assistance ECU 10 is a central control unit that performs driver assistance controls such as lane departure prevention control and adaptive cruise control. In this embodiment, the driver assistance ECU 10 works in cooperation with other ECUs to perform lane departure prevention control, as will be described in detail later.

[0028] The driver assistance ECU 10 is connected to a camera sensor 12 and a radar sensor 14. The camera sensor 12 includes multiple camera sensors that capture images of at least the area in front of the vehicle. The radar sensor 14 includes multiple radar sensors that acquire information on targets present in at least the area in front of the vehicle. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 16 that acquires target information around the vehicle 102.

[0029] Each camera sensor of the camera sensor 12, although not shown in the figure, includes a camera unit that photographs the area around the vehicle 102 and a recognition unit that analyzes the image data obtained from the camera unit to recognize landmarks such as road lines, road signs, and other vehicles. The recognition unit supplies information about the recognized landmarks to the driver assistance ECU 10 at predetermined intervals.

[0030] In particular, in the embodiment shown in Figure 4, the camera sensor 12 can detect the positional relationship of the vehicle 102 with respect to the white lines 72L and 72R, which are the boundaries of the lane 70 (referred to as lane boundaries). Here, the position of the vehicle 102 is the position of the vehicle's reference position 102A, which may be the position of the vehicle's center of gravity or 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 reference position in the lane width direction, and the lateral speed of the vehicle represents the speed of the reference position 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.

[0031] Each radar sensor in the radar sensor 14 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 radiation range. The signal processing unit supplies information representing the distance between the vehicle and the three-dimensional object, the 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 transmitted millimeter waves and the received reflected waves, the attenuation level of the reflected waves, and the time from the transmission of the millimeter waves to the reception of the reflected waves. Note that LiDAR (Light Detection And Ranging) may be used instead of the radar sensor 14.

[0032] Furthermore, a setting control 18 is connected to the driver assistance ECU 10, and the setting control 18 is located in a position where it can be operated by the driver. Although not shown in Figure 1, the setting control 18 includes a lane departure prevention control switch, and the driver assistance ECU 10 performs lane departure prevention control when the lane departure prevention control switch is turned on.

[0033] The EPS / ECU 20 is connected to the EPS device 22. Based on the steering torque Ts and vehicle speed V detected by the driving operation sensor 50 and vehicle condition sensor 60 (described later), the EPS / ECU 20 controls the steering assist torque in a manner known in the art, thereby reducing the driver's steering burden. Furthermore, by controlling the EPS device 22, the EPS / ECU 20 can steer the steering wheels as needed. Therefore, the EPS / ECU 20 and the EPS device 22 function as an automatic steering system that automatically steers the steering wheels as needed.

[0034] The meter ECU 30 is connected to a display unit 32, turn signals 34R and 34L, and a buzzer 36 that sounds an alarm. The display unit 32 may be, for example, a head-up display or a multi-information display that shows meters and various information, or it may be a display for a navigation device not shown. A speaker may be connected to the meter ECU 30 instead of, or together with, the buzzer 36.

[0035] A turn signal lever 42, located on the steering column (not shown), is connected to the steering ECU 40. When the turn signal lever 42 is tilted vertically, corresponding to the right turn and left turn directions, a signal is supplied to the meter ECU 30, causing the right and left turn signal lamps 34R and 34L to flash, respectively.

[0036] The driving operation sensor 50 and the vehicle condition sensor 60 are connected to CAN 104. Information detected by the driving operation sensor 50 and the vehicle condition sensor 60 (referred to as sensor information) is transmitted to CAN 104. The sensor information transmitted to CAN 104 can be used as appropriate by each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to CAN 104 from that specific ECU.

[0037] The driving operation sensor 50 includes a drive operation amount sensor for detecting the amount of operation on the accelerator pedal, a braking operation amount sensor for detecting master cylinder pressure or the force applied to the brake pedal, and the like. Furthermore, the driving operation sensor 50 includes a steering angle sensor for detecting the steering angle θ, a steering torque sensor for detecting the steering torque Ts, and the like.

[0038] The vehicle condition sensor 60 includes a vehicle speed sensor for detecting the vehicle speed of the vehicle 102, a longitudinal acceleration sensor for detecting the longitudinal acceleration of the vehicle, a lateral acceleration sensor for detecting the lateral acceleration of the vehicle, and a yaw rate sensor for detecting the yaw rate of the vehicle.

[0039] When the lane departure prevention switch on the driver's setting device 18 is turned ON, the CPU of the driver assistance ECU 10 executes lane departure prevention control according to the flowchart shown in Figure 2. Note that the lane departure prevention control according to the flowchart shown in Figure 2 is the lane departure prevention control for Japan, and its program is stored in the ROM of the driver assistance ECU 10.

[0040] <Lane Departure Prevention Control Program in the First Embodiment> Next, the lane departure prevention control program of the first embodiment will be described with reference to the flowchart shown in Figure 2. In the first embodiment, the lane departure prevention method of the first embodiment is executed by performing lane departure prevention control according to the flowchart shown in Figure 2.

[0041] First, in step S10, the CPU determines whether there is a risk of lane departure or whether lane departure has actually occurred. That is, based on the relative position of the vehicle 102 with respect to the lane detected by the camera sensor 12, the CPU determines, in a manner known in the art, whether there is a risk of the vehicle deviating from the lane or whether the vehicle has deviated from the lane. If the CPU makes a negative determination, it terminates this control; if it makes a positive determination, it proceeds to step S20.

[0042] In this case, the determination of whether or not there is a risk of the vehicle 102 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 102B of the vehicle with respect to the longitudinal direction 70A of the lane 70 is estimated based on the image information in front of the vehicle 102. The speed Vy of the vehicle 102 moving in a direction perpendicular to the longitudinal direction 70A of the lane 70 is estimated as Vsinθy based on the angle θy and the vehicle speed V.

[0043] Furthermore, the distance Dy (not shown) in the lane width direction between the lane departure judgment reference line 74 on the side the vehicle 102 is approaching and the vehicle's reference position 102A is estimated. In addition, if Δt is a preset time, and Dy-VyΔt is less than or equal to a preset reference value Dyc (a positive constant), it may be determined that there is a risk of the vehicle 102 deviating from the lane. Note that in Figure 4, the lane departure judgment reference line 74 is located outside the white lines 72L and 72R, which are the boundaries of the lane 70, but the lane departure judgment reference line 74 may be located inside or on the white lines 72L and 72R.

[0044] In step S20, the CPU determines whether the driver intends to deviate from the lane, in a manner known in the art. If the CPU determines that the driver does not intend to deviate from the lane, it proceeds to step S40; if it determines that the driver does not intend to deviate, it proceeds to step S30.

[0045] For example, it may be determined that the driver intends to deviate from the lane when the turn signal lever 42 is tilted in the direction of lane departure or when steering is performed in the direction of lane departure. Whether or not steering is performed in the direction of lane departure may be determined, for example, based on the steering torque Ts, or based on the steering torque Ts and the yaw rate of the vehicle.

[0046] In step S30, the CPU activates the buzzer 36 to emit a warning sound and displays a warning on the display 32 indicating that the vehicle 102 is in danger of deviating from its lane or has deviated from its lane. Furthermore, if the degree of lane departure risk or lane departure increases, the CPU outputs an automatic steering command signal to the EPS / ECU 20 to perform automatic steering to prevent the vehicle 102 from deviating from its lane or to resolve the lane departure situation of the vehicle 102. The warning may be a visual warning such as a display 32 or warning lamp, an auditory warning such as a buzzer 36 or speaker, or a tactile warning such as seat vibration, or any combination thereof.

[0047] In step S40, the CPU determines, based on the information supplied by the camera sensor 12, whether the lane in which the vehicle 102 is currently traveling is a lane where crossing is prohibited. If the CPU determines that it is correct, it proceeds to step S60; if it determines that it is incorrect, it proceeds to step S50.

[0048] In this case, a lane may be determined to be a lane where crossing is prohibited from the time the start sign 80A or 80B of the no-crossing section shown in Figure 5 (A) or (B) is detected until any of the end signs 80C to 80E of the no-crossing section shown in Figure 5 (C) to (E) is detected. If a lane is a no-crossing lane, it is possible to overtake a preceding vehicle as long as vehicle 102 does not cross the lane.

[0049] In step S50, the CPU determines, based on the information supplied by the camera sensor 12, whether the lane in which the vehicle 102 is currently traveling is a no-passing lane. If the CPU determines that it is not a no-passing lane, it terminates this control; if it determines that it is a no-passing lane, it proceeds to step S60.

[0050] In this case, a lane may be determined to be a no-passing lane from the time the start sign 82A or 82B of the no-passing section shown in Figure 6 (A) or (B) is detected until any of the end signs 82C to 82E of the no-passing section shown in Figure 6 (C) to (E) is detected. Also, although not shown in the figure, a lane may be determined to be a no-passing lane when the right lane boundary line is yellow.

[0051] In step S60, the CPU determines, based on the information supplied by the camera sensor 12 and the radar sensor 14, whether or not there is a preceding vehicle to be overtaken in front of the vehicle 102. If the CPU determines that there is no vehicle to be overtaken, it proceeds to step S90; if it determines that there is no vehicle to be overtaken, it proceeds to step S70.

[0052] In this case, if there is a preceding vehicle within a range of less than or equal to the reference distance from vehicle 102, and the preceding vehicle is a vehicle other than a stationary vehicle or a light vehicle (e.g., a bicycle), and the relative speed of the vehicle with respect to the preceding vehicle is a positive value, then it may be determined that there is a preceding vehicle to be overtaken. The above reference distance may be a constant positive value, or it may be set to be variable according to the speed of the vehicle, such that it increases as the speed of the vehicle increases.

[0053] In step S70, the CPU determines whether the turn signal lamp 34R or 34L on the lane departure side is flashing. If the CPU determines that it is positive, it terminates this control; if it determines that it is negative, it proceeds to step S80.

[0054] In step S80, the CPU issues a warning on the display unit 32, which includes information that lane departure is not permitted because the lane is a lane where lane departure is prohibited. The CPU also performs automatic steering to prevent vehicle 102 from deviating from the lane or to resolve the lane departure situation of vehicle 102.

[0055] In step S90, the CPU, as in step S80, issues a warning on the display unit 32 that lane departure is not permitted because the lane is a no-passing or no-crossing lane, but does not perform automatic steering.

[0056] Furthermore, the warnings in steps S80 and S90 may include, for example, "You cannot cross the lane because it is a no-crossing lane," if the lane is a no-crossing lane, and may include, for example, "You cannot overtake or cross the lane because it is a no-passing lane."

[0057] <Operation of the first embodiment> Next, we will explain the operation of the first embodiment in various cases where there is a risk of lane departure or a lane departure has occurred, and an affirmative determination is made in step S10, but the circumstances differ.

[0058] <A. When the driver has no intention of deviating from the lane> Since the driver has no intention of deviating from the lane, a negative determination is made in step S20, and in step S30, lane departure suppression control is executed. That is, when the buzzer 36 is activated, an alarm sound is emitted, and the display 32 displays that there is a risk that the vehicle will deviate from the lane or that there is a fact of lane departure. Also, when the risk of lane departure or the degree of lane departure becomes higher, automatic steering is performed.

[0059] <B. When the driver has an intention of deviating from the lane and the lane is not prohibited from lane departure> Positive determinations are made in steps S10 and S20, but negative determinations are made in steps S40 and S50. Therefore, neither of steps S80 and S90 is executed, so lane departure suppression control is not executed. Accordingly, in a situation where the driver intentionally deviates from the lane, such as when changing lanes, overtaking, moving onto a branch road or an intersection road, it is possible to prevent the driver from feeling annoyed due to the unnecessary execution of lane departure suppression control and the automatic steering from interfering with the driver's driving operation.

[0060] <C. When the driver has an intention of deviating from the lane but the lane is prohibited from lane departure> Positive determinations are made in steps S10 and S20, and a positive determination is made in step S40 or S50. Therefore, in principle, when step S80 or S90 is executed, lane departure suppression control is executed. Accordingly, even when it is determined that there is a risk or a fact of the vehicle deviating from the lane and the driver has an intention of deviating from the lane, when it is determined that the lane on which the vehicle is traveling is a lane prohibited from lane departure, at least the issuance of an alarm in the lane departure suppression control is executed. Therefore, when the lane on which the vehicle is traveling is a lane prohibited from lane departure, it is possible to suppress lane departure so that the vehicle travels in accordance with the regulations, at least by issuing an alarm.

[0061] In particular, when the lane is a lane where lane departure is prohibited, the warning includes, for example, "Lane departure is not allowed because it is prohibited", and when the lane is a lane where overtaking is prohibited, the warning includes, for example, "Overtaking and lane departure are not allowed because overtaking is prohibited". Therefore, compared to a case where, for example, the display of signs such as lane departure prohibition and the issuance of warnings such as the risk of lane departure are performed individually without mutual relation, in addition to the fact that there is a risk of lane departure or the fact of lane departure, the driver can easily and clearly understand the reason why lane departure is not allowed.

[0062] <C-1. When there is no preceding vehicle and the turn signal lamp is operating> In steps S60 and S70, a negative determination and an affirmative determination are respectively made. Therefore, similar to the case of B above, neither step S80 nor step S90 is executed, so the lane departure suppression control is not executed. Accordingly, in a situation where the driver intentionally deviates from the lane, such as lane change, overtaking, or shifting to a branch road or an intersection road, it is possible to prevent the driver from feeling annoyance due to the unnecessary execution of the lane departure suppression control and the automatic steering interfering with the driver's driving operation.

[0063] <C-2. When there is no preceding vehicle and the turn signal lamp is not operating> Since a negative determination is made in steps S60 and S70, warning issuance and automatic steering are performed in step S80. Therefore, the driver can easily and clearly recognize that lane departure is not allowed because the lane is a lane where lane departure is prohibited, and the steering to be performed to prevent or eliminate lane departure can be assisted by the automatic steering.

[0064] <C-3. When there is a preceding vehicle> Since a positive determination is made in step S60, a warning is issued in step S90. Therefore, the driver can easily and clearly recognize that the lane is a lane where lane departure is prohibited, and that lane departure is not permitted. In addition, since automatic steering is not performed, the risk of automatic steering interfering with the driver's steering operation can be reduced, and in particular, it is possible to avoid the vehicle approaching the preceding vehicle due to automatic steering.

[0065] [Second Embodiment] The lane departure prevention device according to the second embodiment is applied to vehicles operating in Europe, but has a configuration similar to that shown in Figure 1. The ROM of the driver assistance ECU 10 stores the lane departure prevention control program of the second embodiment, which corresponds to the flowchart shown in Figure 3.

[0066] The lane departure prevention control according to the flowchart shown in Figure 3 is also executed by the CPU of the driver assistance ECU 10 when the lane departure prevention switch on the setting control unit 18, which is not shown in Figure 1, is turned ON. In the second embodiment, the lane departure prevention method of the second embodiment is executed by executing the lane departure prevention control according to the flowchart shown in Figure 3.

[0067] As can be seen from comparing Figure 3 with Figure 2, steps S10 to S30 and steps S60 to S90 are executed in the same way as steps S10 to S30 and steps S60 to S90 in the first embodiment. Step S40 in the first embodiment is not executed, and if a positive determination is made in step S20, step S55, which corresponds to step S50 in the first embodiment, is executed.

[0068] In step S55, the CPU of the driver assistance ECU 10 determines, based on the information supplied from the camera sensor 12, whether the lane in which the vehicle 102 is currently traveling is a no-passing lane. If the CPU determines that it is not a no-passing lane, it terminates this control; if it determines that it is a no-passing lane, it proceeds to step S60.

[0069] In this case, the lane may be determined to be a no-passing lane from the time the start sign 82F of the no-passing zone shown in Figure 6(F) is detected until the end sign 82G of the no-passing zone shown in Figure 6(G) is detected. When a lane is a no-passing lane, overtaking is prohibited regardless of whether the vehicle crosses the lane or not. Furthermore, if the vehicle is a large vehicle, the lane may be determined to be a no-passing lane from the time the start sign of the no-passing zone shown in Figure 6(H) is detected until the end sign of the no-passing zone, which is not shown in Figure 6, is detected.

[0070] Furthermore, since step S40 in the first embodiment is not performed, the warnings in steps S80 and S90 may include, for example, "Overtaking is prohibited, so you cannot overtake or cross the line."

[0071] As can be seen from the above explanation, the lane departure prevention device of the second embodiment operates in the same manner as the lane departure prevention device of the first embodiment, except that step S40 is not performed and the warnings in steps S80 and S90 are warnings based solely on the prohibition of overtaking.

[0072] Therefore, in the second embodiment as well, when the lane in which the vehicle is traveling is a lane where overtaking is prohibited, lane departure can be suppressed to ensure that the vehicle travels in accordance with the law, at least by issuing a warning.

[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, if step S70 is omitted and a negative determination is made in step S60, step S80 may be executed.

[0075] Furthermore, if step S60 is omitted and an affirmative determination is made in step S40 or S50, step S70 may be executed. In step S70, if an affirmative determination is made, lane departure prevention control is not executed, and if a negative determination is made, step S80 or S90 may be executed. Also, if steps S60 and S70 are omitted and an affirmative determination is made in step S40 or S50, step S80 or S90 may be executed.

[0076] Furthermore, in step S10, the determination of whether or not lane departure has actually occurred may be omitted, and only the determination of whether or not there is a risk of lane departure may be made. Additionally, the issuance of a warning and / or automatic steering, which are performed as lane departure prevention control, may be omitted. [Explanation of symbols]

[0077] 10…Driving support ECU, 12…Camera sensor, 14…Radar sensor, 16…Target information acquisition device, 32…Display unit, 34R, 34L…Turn signal lamp, 36…Buzzer, 42…Turn signal lever, 80A, 80B…No overtaking zone start sign, 80C~80E…No overtaking zone end sign, 82A, 82B…No overtaking zone start sign, 82C~82E…No overtaking zone end sign, 100…Lane departure prevention device, 102…Own vehicle

Claims

1. A lane departure prevention device comprising: a target information acquisition device that acquires target information around a vehicle; and a control unit configured to determine whether there is a risk or actual occurrence of lane departure of the vehicle based on the target information acquired by the target information acquisition device, wherein the control unit is configured to perform at least one of lane departure suppression control, such as issuing a warning and automatic steering, when it is determined that there is a risk or actual occurrence of lane departure of the vehicle and the driver does not intend to deviate from the lane, and not perform the lane departure suppression control when it is determined that there is a risk or actual occurrence of lane departure of the vehicle and the driver intends to deviate from the lane, The control unit is configured to issue a warning and perform automatic steering when it determines, based on the landmark information, that there is a risk or fact of the vehicle deviating from its lane and the driver intends to deviate from the lane, and when it determines that the lane the vehicle is traveling in is a lane where overtaking is prohibited and there is no vehicle ahead of the vehicle, and when it determines, based on the landmark information, that the lane the vehicle is traveling in is a lane where overtaking is prohibited and there is a vehicle ahead of the vehicle, it issues a warning but does not perform automatic steering.

2. A lane departure prevention device according to claim 1, wherein the control unit is configured not to perform the lane departure suppression control when it determines, based on the landmark information, that the lane in which the vehicle is traveling is neither a lane where crossing is prohibited nor a lane where overtaking is prohibited, in a situation in which the control unit has determined that there is a risk or fact of the vehicle deviating from its lane and that the driver has the intention to deviate from the lane.

3. A lane departure prevention device according to claim 1, wherein the control unit is configured to determine that the driver has an intention to deviate from the lane when it determines that the turn signal lever is tilted in the direction of lane departure or when it determines that steering operations are being performed in the direction of lane departure.

4. A lane departure prevention device according to claim 1, wherein the warning includes information that the lane is a lane where crossing the lane is prohibited or overtaking is prohibited, and therefore the vehicle is not permitted to deviate from the lane.

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