Vehicle travel control device and method

Abstract

To provide a travel control device and method capable of reducing a risk of a collision between an own vehicle and a preceding vehicle even in a situation where the own vehicle is to aimlessly start together with the start of a vehicle on an adjacent lane when the preceding vehicle and the own vehicle are stopping.SOLUTION: A vehicle travel control device includes a driving support ECU configured to execute risk reduction control to reduce a risk of a collision between an own vehicle and a control object existing in front of the own vehicle in a travel direction when it is determined that there is the risk, and execute override control to suppress the execution of the risk reduction control based on a driving operation of a driver of the own vehicle. When it is determined that the own vehicle performs an aimless start to start together with the start of another vehicle existing on an adjacent lane regardless of existence of the preceding vehicle in a resting state in front of the own vehicle on the own lane (S40), the driving support ECU performs at least one of facilitating the execution of the risk reduction control and making it difficult to execute the override control (S60, S80).SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a vehicle cruise control device and method for a vehicle such as an automobile, and more particularly to a cruise control device and method that reduces the risk of a vehicle colliding with a controlled object. [Background technology]

[0002] One type of driving control device is known that, when there is a risk of the vehicle colliding with a controlled object, reduces the risk of collision by implementing risk reduction control such as automatic braking of the vehicle or issuing an alarm, but performs override control to suppress the execution of risk reduction control when the driver performs driving operations such as acceleration.

[0003] The following Patent Document 1 describes a driving control device that switches whether or not to perform override control, which suppresses the execution of risk reduction control, depending on whether the controlled object is another vehicle or a pedestrian or bicycle. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-37804 Summary of the Invention

[0005] [Problem to be solved by the invention] In a situation where risk reduction control is performed, it is not easy to determine whether a driving operation such as acceleration is based on the driver's intention or an erroneous operation or a careless driving operation. For example, when a preceding vehicle and the subject vehicle are stopped, the subject vehicle may start moving carelessly, following the start of a vehicle in an adjacent lane. In such a situation, if it is determined that the starting driving operation is based on the driver's intention, risk reduction control is not performed, and the risk of the subject vehicle colliding with the preceding vehicle cannot be reduced.

[0006] The present invention provides an improved driving control device and method that can reduce the risk of a vehicle colliding with a preceding vehicle even in a situation where the preceding vehicle and the vehicle itself are stopped and the vehicle itself starts moving aimlessly due to the start of a vehicle in an adjacent lane. [Means for solving the problems and effects of the invention]

[0007] According to the present invention, there is provided a vehicle driving control device (100) including a control unit (driving assistance ECU10) configured to, when it is determined that there is a risk of a collision between a host vehicle (102) and a control object present ahead in the direction of travel of the host vehicle (S50), execute risk reduction control to reduce the risk (S100, S130), and execute override control to suppress the execution of risk reduction control based on the driving operation of the driver of the host vehicle (S40, S60 to S80, S120).

[0008] When the control unit (driving assistance ECU10) determines that the host vehicle has started off in a random manner, triggered by the start of another vehicle in an adjacent lane, even though there is a stationary preceding vehicle ahead of the host vehicle in the host lane (S40), the control unit (driving assistance ECU10) is configured to perform at least one of making it easier to execute risk reduction control and making it harder to execute override control (S60, S80).

[0009] Furthermore, according to the present invention, there is provided a vehicle driving control method including steps of: determining that there is a risk of a collision between a host vehicle (102) and a control object located ahead in the direction of travel of the host vehicle (S50); executing risk reduction control to reduce the risk (S100, S130); and executing override control to suppress the execution of risk reduction control based on the driving operation of the driver of the host vehicle (S40, S60 to S80, S120).

[0010] The driving control method further includes a step (S40) of determining whether or not a careless start has occurred, in which the host vehicle has started due to the triggering of the start of another vehicle in an adjacent lane, despite the presence of a stationary preceding vehicle ahead of the host vehicle in the host lane, and a step (S60, S80) of performing at least one of making it easier to execute risk reduction control and making it harder to execute override control when it is determined that a careless start has occurred.

[0011] According to the above-described cruise control device and method, when it is determined that an intentional start has occurred, at least one of the following is performed: making the risk reduction control easier to execute and making the override control harder to execute. Therefore, in the case of an intentional start in which the host vehicle starts due to the start of another vehicle in an adjacent lane, even though there is a preceding vehicle that is stationary in front of the host vehicle in the same lane, the risk reduction control can be made easier to execute and / or making the override control harder to execute. Therefore, even in a situation in which the preceding vehicle and the host vehicle are stopped and the host vehicle starts to start due to the start of a vehicle in an adjacent lane, the risk of the host vehicle colliding with the preceding vehicle can be reduced. [Mode of the Invention]

[0012] In one aspect of the present invention, when the control unit (driving assistance ECU 10) determines that a careless start has been made (S40), it is configured to make it easier to execute the risk reduction control by relaxing the conditions for executing the risk reduction control compared to when it is not determined that a careless start has been made (S60, S80).

[0013] According to the above aspect, when it is determined that a careless start has been made, the conditions for executing risk reduction control are relaxed compared to when it is not determined that a careless start has been made, making it easier to execute risk reduction control compared to when the conditions for executing risk reduction control are not relaxed.

[0014] In another aspect of the present invention, when it is determined that a careless start has been performed (S40), the control unit (driving assistance ECU 10) is configured to make it more difficult to execute override control (S60, S80) by making the conditions for executing override control stricter than when it is not determined that a careless start has been performed.

[0015] According to the above aspect, when it is determined that a careless start has been made, the conditions for executing override control are made stricter compared to when it is not determined that a careless start has been made, making it more difficult to execute override control compared to when the conditions for executing override control are not made stricter.

[0016] Furthermore, in another aspect of the present invention, the control unit (driving assistance ECU10) is configured to determine (S40, S45) that an intentional start has been made when the host vehicle starts (S43) within a reference time after the second condition is met in a situation where a first condition (S41) that a stopped preceding vehicle is present in front of the host vehicle within a first distance range from the host vehicle in the host lane, a second condition (S42) that another vehicle that was stopped in front of the host vehicle within a second distance range from the host vehicle in an adjacent lane has started to move, and a third condition (S44) that there is no possibility that the host vehicle will change lanes out of the host lane are met.

[0017] According to the above aspect, when the first to third conditions are met, and the host vehicle starts moving within a reference time after the second condition is met, it is determined that the host vehicle has started moving unintentionally. The first condition is that a stopped preceding vehicle is present ahead of the host vehicle within a first distance range from the host vehicle in the host lane. The second condition is that another vehicle that was stopped ahead of the host vehicle within a second distance range from the host vehicle in an adjacent lane has started moving. The third condition is that there is no possibility that the host vehicle will change lanes out of the host lane.

[0018] Therefore, it is possible to appropriately determine whether or not a careless start has occurred, compared to when any of the first to third conditions is not required, or when it is not required that the vehicle has started moving within a reference time after the second condition is met.

[0019] In the above description, to facilitate understanding of the present invention, the names and / or symbols used in the embodiments described below are enclosed in parentheses for the configurations of the invention corresponding to those embodiments. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and / or symbols enclosed in parentheses. Other objects, features, and attendant advantages of the present invention will be easily understood from the following description of the embodiments of the present invention, which will be given with reference to the drawings. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic configuration diagram showing an embodiment of a vehicle travel control device according to the present invention; [Figure 2] 4 is a flowchart corresponding to a driving control program in the embodiment. [Figure 3] 3 is a flowchart showing a careless start determination control routine executed in step S40 of FIG. 2. [Figure 4] FIG. 1 is a diagram showing a situation in which the vehicle, a preceding vehicle, and an adjacent vehicle are stopped in front of a pedestrian crossing. [Figure 5] 5 is a diagram showing an example of changes in the vehicle speeds of the subject vehicle, a preceding vehicle, and an adjacent vehicle in the situation shown in FIG. 4. FIG. [Figure 6] This figure shows a situation in which (A) the vehicle in question, the preceding vehicle, and the adjacent vehicle, which had been stopped, start moving at almost the same time, and (B) the preceding vehicle remains stationary, the adjacent vehicle that had been stopped starts moving, and the vehicle in question starts moving while changing lanes toward the adjacent vehicle. DETAILED DESCRIPTION OF THE INVENTION

[0021] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cruise control device according to an embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0022] As shown in Fig. 1, a cruise control device 100 according to an embodiment of the present invention is applied to a vehicle 102 and includes a driving assistance ECU 10. The vehicle 102 is an autonomously driven vehicle and includes a drive ECU 20, a brake ECU 30, and a meter ECU 50. The ECU stands for an electronic control unit that includes a microcomputer as its main component. To distinguish the vehicle 102 from other vehicles, the vehicle 102 will be referred to as the host vehicle 102 as necessary.

[0023] The microcomputer of each ECU includes a CPU, ROM, RAM, read / write non-volatile memory (N / M), and an interface (I / F). The CPU performs various functions by executing instructions (programs, routines) stored in the ROM. Furthermore, these ECUs are interconnected via a Controller Area Network (CAN) 104 to enable data exchange (communication). Therefore, the detected values of sensors (including switches) connected to a specific ECU are transmitted to other ECUs.

[0024] The driving assistance ECU 10 is a central control device that performs driving assistance driving control such as cruise control, adaptive cruise control, and lane keeping control. In the embodiment, the driving assistance ECU 10 executes driving control for the vehicle 102 in cooperation with other ECUs, as will be described in detail later. In the embodiment, when the driving assistance ECU 10 determines that there is a risk of the host vehicle colliding with a control object present ahead in the traveling direction of the host vehicle, the driving assistance ECU 10 executes risk reduction control to reduce the risk. In addition, the driving assistance ECU 10 executes override control to suppress the execution of risk reduction control based on the driving operation of the driver of the host vehicle.

[0025] The driving assistance ECU 10 is connected to a camera sensor 12, a radar sensor 14, and a setting operation device 16. The camera sensor 12 and the radar sensor 14 each include a plurality of camera devices and a plurality of radar devices. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 18 that acquires target information around the vehicle 102.

[0026] Although not shown in the figure, each camera device of the camera sensor 12 includes a camera unit that captures images of the surroundings of the vehicle 102 and a recognition unit that analyzes image data captured by the camera unit to recognize targets such as white lines on the road and other vehicles. The recognition unit supplies information about the recognized targets to the driving assistance ECU 10 at predetermined time intervals.

[0027] Each radar device of the radar sensor 14 includes a radar transmitting / receiving unit and a signal processing unit (not shown). The radar transmitting / receiving unit emits millimeter-wave radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves reflected by a three-dimensional object (e.g., another vehicle, a bicycle, etc.) within the emission range (i.e., reflected waves). The signal processing unit supplies information indicating 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 with respect to the vehicle to the driving assistance ECU 10 at predetermined time 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 transmitting the millimeter waves to receiving the reflected waves. Note that a LiDAR (Light Detection and Ranging) may be used instead of or in addition to the radar sensor 14.

[0028] The setting operator 16 is provided in a position operable by the driver, such as a steering wheel (not shown in Fig. 1), and is designed to be operated by the driver. Although not shown in Fig. 1, the setting operator 16 includes a driving assistance switch. As will be described in detail later, the driving assistance ECU 10 executes driving control when the driving assistance switch is on.

[0029] The drive ECU 20 is connected to a drive device 22 that accelerates the vehicle 102 by applying a driving force to drive wheels 24. The drive ECU 20 normally controls the drive device 22 so that the driving force generated by the drive device 22 changes in response to the driving operation by the driver, and when it receives a command signal from the driving assistance ECU 10, it controls the drive device 22 based on the command signal.

[0030] The braking ECU 30 is connected to a braking device 32 that applies braking force to wheels 34 to decelerate the vehicle 102. The braking ECU 30 normally controls the braking device so that the braking force generated by the braking device 32 changes in response to the braking operation by the driver, and when it receives a command signal from the driving assistance ECU 10, it controls the braking device 32 based on the command signal to perform automatic braking.

[0031] Therefore, the brake ECU 30 and the brake device 32 work together to function as an automatic braking device 36. When braking force is applied to the wheels by cruise control or the like, a brake lamp (not shown in FIG. 1) is turned on.

[0032] A touch panel display 52 that displays the status of control by the driving assistance ECU 10 and an alarm device 54 that issues alarms are connected to the meter ECU 50. The display 52 may be, for example, a multi-information display that displays meters and various information, or may be the display of a navigation device 80 described below. As described below, the display 52 displays the status of driving control when it receives a signal from the driving assistance ECU 10.

[0033] The warning device 54 is activated when it is determined that the vehicle 102 is at risk of colliding with a control object such as an obstacle, and issues a warning as one of the risk reduction controls for reducing the risk of collision, i.e., issues a warning that the vehicle 102 is at risk of colliding with a control object. The warning device 54 may be any of a warning device that issues a visual warning such as a warning lamp, a warning device that issues an auditory warning such as a warning buzzer, or a warning that issues a tactile warning such as seat vibration, or any combination thereof.

[0034] The driving operation sensors 60 and the vehicle condition sensors 70 are also connected to the CAN 104. Information detected by the driving operation sensors 60 and the vehicle condition sensors 70 (referred to as sensor information) is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 can be used appropriately in each ECU. Note that the sensor information may be information from a sensor connected to a specific ECU and transmitted to the CAN 104 from that specific ECU.

[0035] The driving operation sensor 60 includes a driving operation amount sensor that detects the amount of accelerator pedal operation, a braking operation amount sensor that detects the master cylinder pressure or the force applied to the brake pedal, a brake switch that detects whether the brake pedal is operated, a steering angle sensor that detects the steering angle, a steering torque sensor that detects the steering torque, etc.

[0036] The vehicle state sensor 70 includes a vehicle speed sensor that detects the vehicle speed V of the vehicle 102, a longitudinal acceleration sensor that detects the longitudinal acceleration of the vehicle, a lateral acceleration sensor that detects the lateral acceleration of the vehicle, and a yaw rate sensor that detects the yaw rate of the vehicle.

[0037] Furthermore, the navigation device 80 is also connected to the CAN 104. The navigation device 80 includes a GPS receiver that detects the position of the vehicle 102, a storage device that stores map information and road information, and a communication device that acquires the latest map information and road information from an external device. In particular, the road information may include information on locations where the vehicle may temporarily stop, such as intersections and crosswalks. Note that the navigation device 80 does not necessarily have to be provided.

[0038] In this embodiment, the ROM of the driving assistance ECU 10 stores a driving control program corresponding to the flowcharts shown in FIGS. <Driving control (Fig. 2)>

[0039] Next, the driving control in this embodiment will be described with reference to the flowchart shown in Fig. 2. The driving control according to the flowchart shown in Fig. 2 is repeatedly executed at predetermined time intervals by the CPU of the driving assist ECU 10 while the driving assist switch is on. Note that when the driving control starts, the flags Faoa, Faob, and Fas are initialized to 0.

[0040] First, in step S10, the CPU determines whether the driver has operated the accelerator pedal based on the amount of operation of the accelerator pedal detected by the driving operation amount sensor of the driving operation sensor 60. If a positive determination is made, in step S20, the flag Faoa is set to 1. If a negative determination is made, in step S30, the flag Faoa is set to 0. When Faoa is 1, it indicates that it has been determined that the driver has operated the accelerator pedal, and when Faoa is 0, it indicates that it has not been determined that the driver has operated the accelerator pedal. Note that it may be determined that the driver has operated the accelerator when the accelerator opening is equal to or greater than a reference opening or when the accelerator opening speed is equal to or greater than a reference opening speed.

[0041] In step S40, the CPU performs a careless start determination in accordance with the routine shown in Fig. 3, which will be described later in detail. When it is determined that the host vehicle 102 has started carelessly, the flag Fas is set to 1, and when it is determined that the host vehicle 102 has not started carelessly, the flag Fas is reset to 0.

[0042] In step S50, the CPU determines whether there is a possibility that the host vehicle will collide with the preceding vehicle, based on the distance between the host vehicle and the preceding vehicle and the relative speed of the host vehicle with respect to the preceding vehicle, which are detected, for example, by the camera sensor 12 or the radar sensor 14. If it is determined that there is no possibility of collision, this control is temporarily terminated, and if it is determined that there is a possibility of collision, this control proceeds to step S60.

[0043] In step S60, the CPU determines whether the flag Fas is 1, that is, whether it was determined in step S40 that the host vehicle 102 started moving aimlessly. If a positive determination is made, the control proceeds to step S80, and if a negative determination is made, the control proceeds to step S70.

[0044] In step S70, the CPU sets the warning reference value TTCa of the collision prediction time TTC, which is used to determine whether or not a warning needs to be issued, to a standard value TTCan (a positive constant), and also sets the flag Faob to 1. Note that the flag Faob being 1 means that the accelerator override is enabled.

[0045] In step S80, the CPU sets the warning reference value TTCa of the collision prediction time TTC to a value TTCah (positive constant) greater than the standard value TTCan, and resets the flag Faob to 0. Note that the flag Faob being 0 means that the accelerator override is disabled.

[0046] In step S90, the CPU calculates a collision prediction time TTC, which is a predicted time until the vehicle 102 collides with the preceding vehicle. The collision prediction time TTC is calculated, for example, according to the following formula (1) based on the distance Dr between the host vehicle and the preceding vehicle based on the detection result by the target information acquisition device 18 and the relative speed Vr of the host vehicle with respect to the preceding vehicle. The collision prediction time TTC is an index that indicates the likelihood that the host vehicle will collide with the preceding vehicle, and the smaller its value, the higher the likelihood (risk) of the host vehicle colliding with the preceding vehicle. TTC=Dr / Vr (1)

[0047] Furthermore, the CPU determines whether the collision prediction time TTC is equal to or less than the warning reference value TTCa, i.e., whether it is necessary to issue a warning that the host vehicle may collide with the preceding vehicle. If a negative determination is made, the control proceeds to step S140, and if a positive determination is made, the control proceeds to step S100.

[0048] In step S100, the CPU outputs a command signal to the meter ECU 50 to display on the display 52 a warning that the vehicle may collide with the preceding vehicle, and activates the warning device 54 to issue a warning that the vehicle may collide with the preceding vehicle.

[0049] In step S110, the CPU determines whether the collision prediction time TTC is equal to or less than the automatic braking reference value TTCb, that is, whether automatic braking by the automatic braking device 36 is necessary to reduce the risk of collision. If a negative determination is made, the control proceeds to step S140, and if a positive determination is made, the control proceeds to step S120.

[0050] In step S120, the CPU determines whether the flag Faoa or the flag Faob is 0. If a negative determination is made, the control proceeds to step S140, and if a positive determination is made, the control proceeds to step S130.

[0051] In step S130, the CPU outputs a command signal to the brake ECU 30 to cause the automatic braking device 36 to brake the host vehicle automatically in order to reduce the risk of a collision.

[0052] In step S140, the CPU determines whether or not the conditions for ending this control are met. If a negative determination is made, the control returns to step S90, and if a positive determination is made, this control is temporarily terminated.

[0053] It may be determined that the termination condition for this control is met when any of the following E1 to E3 is met. E1: There is no longer a risk of your vehicle colliding with the vehicle ahead. E2: The leading vehicle has started moving. E3: Your vehicle changed lanes.

[0054] As can be seen from the above explanation, in this embodiment, the risk reduction control for reducing the risk of the host vehicle colliding with the preceding vehicle is the issuance of a warning by the activation of the warning device 54 and the automatic braking by the automatic braking device 36. <Intentional starting detection control (Fig. 3)>

[0055] Next, the careless start determination control executed in the above-mentioned step S40 will be described with reference to the flowchart shown in FIG.

[0056] In step S41, the CPU determines whether or not there is a stationary preceding vehicle in the own lane (whether or not the first condition is established). If a negative determination is made, the control proceeds to step S46, and if a positive determination is made, the control proceeds to step S42.

[0057] It may be determined that there is a stationary preceding vehicle in the own lane when all of the following A1 to A3 are met. A1: The vehicle ahead is within the lane. A2: The preceding vehicle is present within a range of a reference distance (positive constant) from the host vehicle. A3: The vehicle ahead is stopped.

[0058] In step S42, the CPU determines whether or not a vehicle stopped in the adjacent lane has started moving (whether or not the second condition is met). If a negative determination is made, the control proceeds to step S46, and if a positive determination is made, the control proceeds to step S43.

[0059] It may be determined that a vehicle stopped in the adjacent lane has started moving when all of the following conditions B1 to B4 are met. B1: In the previous cycle, the adjacent vehicle was within the adjacent lane. B2: In the previous cycle, the adjacent vehicle was located within a reference range from the host vehicle. The reference range may be a range of a predetermined distance (a positive constant) from the side of the host vehicle to the front of the host vehicle. B3: In the previous cycle, the adjacent vehicle was stopped. B4: In the current cycle, the adjacent vehicle is moving forward.

[0060] In step S43, the CPU determines whether the host vehicle has started moving within a reference time after the second condition is satisfied. If a negative determination is made, the control proceeds to step S46, and if a positive determination is made, the control proceeds to step S44. Note that, although the host vehicle was stopped in the previous cycle, the host vehicle may be determined to have started moving when it is moving forward in the current cycle.

[0061] In step S44, the CPU determines whether or not the exclusion condition for the careless start determination is satisfied. If a negative determination is made, in step S45, it is determined that the start of the host vehicle is a careless start, and the flag Fas is set to 1. In contrast, if a positive determination is made, in step S46, it is determined that the start of the host vehicle is not a careless start, and the flag Fas is reset to 0.

[0062] It may be determined that the exclusion conditions for the careless start determination are met when all of the following C1 to C3 are met. In particular, when the following C1 and C2 are not met, this is a third condition that there is no possibility that the host vehicle 102 will change lanes outside the host vehicle lane. C1: The turn signal is operated towards the adjacent vehicle. C2: The steering angle θ is greater than or equal to the reference steering angle (positive constant) toward the adjacent vehicle. C3: The time elapsed since the adjacent vehicle started traveling is equal to or greater than a reference elapsed time (a positive constant). <Operation and Effects of the Embodiment> <When the vehicle starts moving aimlessly (Fig. 4, Fig. 5)>

[0063] 4 shows a situation in which the subject vehicle 102, a leading vehicle 110, and an adjacent vehicle 112 are stopped in front of a crosswalk 114. The leading vehicle 110 is located ahead of the subject vehicle 102 in the subject vehicle lane 116, and the adjacent vehicle 112 is located diagonally ahead of the subject vehicle 102 in the adjacent lane 118. The leading vehicle 110 remains stationary, but as indicated by the arrow, the stopped adjacent vehicle 112 starts moving, which causes the subject vehicle 102 to also start moving.

[0064] 4, affirmative determinations are made in steps S41 to S43, negative determinations are made in step S44, and the flag Fas is set to 1 in step S45. Also, affirmative determinations are made in steps S10, S50, and S60. Therefore, in step S80, the warning reference value TTCa of the collision prediction time TTC is set to a value TTCah that is larger than the standard value TTCan, and the flag Faob is reset to 0.

[0065] Therefore, a positive determination is more likely to be made in step S90, and an alarm is issued earlier in step S100. Furthermore, if a positive determination is made in step S110, a positive determination is made in step S120, and therefore automatic braking in step S130 is executed without being prohibited, and automatic braking of the host vehicle 102 prevents a collision with the leading vehicle 110.

[0066] FIG. 5 shows an example of changes in the vehicle speeds of the host vehicle 102, the preceding vehicle 110, and the adjacent vehicle 112 in the situation shown in FIG.

[0067] In FIG. 5, assume that adjacent vehicle 112 starts moving at time t1, the driver of host vehicle 102 presses the accelerator pedal at time t2 to start increasing the accelerator opening, and host vehicle 102 starts moving immediately thereafter.

[0068] At time t3 immediately after the host vehicle 102 starts moving, the flag Fas is set to 1, and step S80 is executed, whereby the warning reference value TTCa of the predicted collision time TTC is set to a value TTCah that is larger than the standard value TTCan, and the flag Faob is reset to 0. Therefore, the issuance of a warning is initiated at time t4, which is earlier than time t5 at which the issuance of a warning is initiated when the flag Fas is 0.

[0069] Also, at time t6, the driver of the host vehicle 102 further depresses the accelerator pedal, increasing the accelerator opening, and immediately thereafter at time t7, the determination in step S110 becomes positive. Since the determination in step S120 is positive, step S130 is executed, and the host vehicle 102 is automatically braked, thereby preventing a collision with the leading vehicle 110.

[0070] In a conventional driving control device, step S40 and steps S60 to S80 are not executed, and in step S120, it is determined whether the flag Faoa is 0 or not, but it is not determined whether the flag Faob is 0 or not.

[0071] Therefore, if the determination in step S110 is positive, a negative determination is made in step S120 and step S130 is not executed, so that the host vehicle 102 is not automatically braked even at time t7, as shown by the dashed line in Figure 5. Therefore, it is not possible to prevent the host vehicle from colliding with the leading vehicle 110. <When the preceding vehicle also starts moving (Fig. 6(A))>

[0072] FIG. 6(A) shows a situation in which the vehicle 102, the preceding vehicle 110, and the adjacent vehicle 112, which have been stopped, start moving at approximately the same time, as indicated by the arrows.

[0073] 6(A), a negative determination is made in step S41, and the flag Fas is reset to 0 in step S46. Therefore, even if a positive determination is made in step S10, a negative determination is made in step S60, and therefore, in step S70, the reference value TTCa of the collision prediction time TTC is set to the standard value TTCan, and the flag Faob is set to 1.

[0074] Since the collision prediction time TTC does not become a small value, a negative determination is made in step S90, and no warning is issued (step S100) or automatic braking (step S130) is performed. Furthermore, since the reference value TTCa is set to the standard value TTCan, even if a positive determination is made in step S90, the issuance of a warning will not be initiated early. Furthermore, even if a positive determination is made in step S90, a negative determination is made in step S120, and therefore automatic braking of the host vehicle will not be performed. <When changing lanes (Fig. 6(B))>

[0075] Figure 6(B) shows a situation in which the preceding vehicle 110 remains stationary, the adjacent vehicle 112 that was stopped starts moving, as indicated by the arrow, and the vehicle 102 starts moving while changing lanes toward the adjacent vehicle 112.

[0076] In the situation shown in Fig. 6(B), affirmative determinations are made in steps S41 to S44, and in step S46, the flag Fas is reset to 0. Therefore, even if a positive determination is made in step S10, a negative determination is made in step S60, so in step S70, the reference value TTCa of the collision prediction time TTC is set to the standard value TTCan, and the flag Faob is set to 1.

[0077] 6A, no warning is issued (step S100) and no automatic braking is performed (step S130). Even if a positive determination is made in step S90, the issuance of a warning is not initiated early. Furthermore, even if a positive determination is made in step S90, a negative determination is made in step S120, and therefore automatic braking of the vehicle is not performed.

[0078] As can be seen from the above description, according to the cruise control device and method of the present invention, when it is determined that an intentional start has occurred (S40), at least one of the following is performed: making the risk reduction control easier to execute and making the override control harder to execute (S60, S80). Therefore, in the case of an intentional start in which the host vehicle starts due to the start of another vehicle in an adjacent lane, even though there is a preceding vehicle that is stationary in front of the host vehicle in the same lane, the risk reduction control can be made easier to execute and / or making the override control harder to execute. Therefore, even in a situation in which the preceding vehicle and the host vehicle are stopped and the host vehicle starts due to the start of a vehicle in an adjacent lane, the risk of the host vehicle colliding with the preceding vehicle can be reduced.

[0079] Furthermore, according to the cruise control device and method of the present invention, when it is determined that a careless start has been performed (S40), the conditions for executing the risk reduction control are relaxed (S60, S80) compared to when it is not determined that a careless start has been performed. Therefore, it is possible to make the risk reduction control easier to execute compared to when the conditions for executing the risk reduction control are not relaxed.

[0080] Furthermore, according to the cruise control device and method of the present invention, when it is determined that a careless start has been performed (S40), the conditions for executing the override control are made stricter (S60, S80) than when it is not determined that a careless start has been performed. Therefore, it is possible to make it more difficult to execute the override control than when the conditions for executing the override control are not made stricter.

[0081] Furthermore, according to the cruise control device and method of the present invention, when the host vehicle starts moving within a reference time after the second condition is met in a situation where the first to third conditions are met, it is determined that a careless start has occurred (S40, S45). The first condition is that a stopped preceding vehicle is present ahead of the host vehicle within a first distance from the host vehicle in the host lane (S41). The second condition is that another vehicle that was stopped ahead of the host vehicle within a second distance from the host vehicle in an adjacent lane has started moving (S42). The third condition is that there is no possibility that the host vehicle will change lanes out of the host lane (S44). Therefore, it is possible to more appropriately determine whether a careless start has occurred compared to when any of the first to third conditions is not met or when it is not required that the host vehicle has started moving within the reference time after the second condition is met.

[0082] Although the present invention has been described in detail above with reference to specific embodiments, it will be apparent to those skilled in the art that the present invention is not limited to the above-described embodiments, and that various other embodiments are possible within the scope of the present invention.

[0083] For example, in the above-described embodiment, when it is determined that the host vehicle has started in a careless manner, that is, the host vehicle has started in response to the start of another vehicle in an adjacent lane, both of the processes are performed to make the risk reduction control more likely to be executed and to make the override control less likely to be executed. That is, in step S80, the warning reference value TTCa is set to a value TTCah that is greater than the standard value TTCan, and the flag Faob is reset to 0. However, only one of the processes may be performed: making the risk reduction control more likely to be executed and making the override control less likely to be executed.

[0084] Furthermore, in the above-described embodiment, the risk reduction control is the issuance of an alarm (step S100) and automatic braking (step S130), but the risk reduction control may be either the issuance of an alarm or automatic braking, or may include automatic steering to reduce the risk of the host vehicle colliding with a preceding vehicle in addition to the issuance of an alarm and / or automatic braking.

[0085] In the above-described embodiment, when it is determined that a careless start has been performed (S40), the warning reference value TTCa is set to a value TTCah that is greater than the standard value TTCan, thereby relaxing the conditions for executing the risk reduction control (S60, S80). However, the relaxation of the conditions for executing the risk reduction control may be performed by other means, such as by reducing the automatic braking reference value TTCb.

[0086] Furthermore, in the above-described embodiment, the override control that suppresses the execution of the risk reduction control is executed based on the accelerator operation (S10) of the driver of the host vehicle. However, the override control may be executed based on driving operations such as braking operations and steering operations in addition to the accelerator operation of the driver of the host vehicle. [Explanation of symbols]

[0087] 10... driving assistance ECU, 12... camera sensor, 14... radar sensor, 18... target information acquisition device, 22... drive device, 32... braking device, 36... automatic braking device, 100... cruise control device, 102... vehicle, 110... preceding vehicle, 112... adjacent vehicle

Claims

1. A vehicle travel control device including a control unit configured to, when it is determined that there is a risk of a collision between a host vehicle and a control object present ahead in a traveling direction of the host vehicle, execute a risk reduction control to reduce the risk, and execute an override control to suppress the execution of the risk reduction control based on a driving operation of a driver of the host vehicle, The control unit is configured to at least one of make the risk reduction control easier to execute and make the override control harder to execute when it determines that the host vehicle has started off in a random manner, in which the host vehicle has started off due to the triggering of the start of another vehicle in an adjacent lane, even though there is a stationary preceding vehicle in front of the host vehicle in the host lane.

2. 2. The vehicle driving control device according to claim 1, wherein the control unit is configured to make it easier to execute the risk reduction control when it determines that the careless start has been performed, by relaxing the conditions for executing the risk reduction control compared to when it is not determined that the careless start has been performed.

3. 2. The vehicle driving control device according to claim 1, wherein the control unit is configured to make it more difficult to execute the override control when it determines that the careless start has been performed, by making the execution conditions for the override control stricter than when it is not determined that the careless start has been performed.

4. 2. The vehicle driving control device according to claim 1, wherein the control unit: A first condition is that a stopped preceding vehicle is present in front of the host vehicle within a first distance range in the host vehicle's lane; A second condition is that another vehicle that has been stopped in front of the vehicle in the adjacent lane within a second distance range from the vehicle starts moving. A third condition is that there is no possibility that the vehicle will change lanes outside the vehicle's own lane; and and determining that the vehicle has started moving unintentionally when the vehicle starts moving within a reference time after the second condition is satisfied in a situation where the second condition is satisfied.

5. A vehicle travel control method including: when it is determined that there is a risk of a collision between a host vehicle and a control object present ahead in a traveling direction of the host vehicle, executing a risk reduction control to reduce the risk; and executing an override control to suppress the execution of the risk reduction control based on a driving operation of a driver of the host vehicle, The vehicle driving control method further includes a step of determining whether or not a careless start has been performed, in which the host vehicle starts due to the triggering of the start of another vehicle in an adjacent lane, even though there is a stationary preceding vehicle in front of the host vehicle in the host lane, and a step of performing at least one of making it easier to execute the risk reduction control and making it harder to execute the override control when it is determined that the careless start has been performed.

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