Driving assistance method and driving assistance device

Abstract

The present invention, when executing assistance control for overtaking in which a host vehicle (V) traveling along a first lane (L1) overtakes a preceding vehicle (Vx) traveling ahead of the host vehicle (V) by travelling along a second lane (L2) adjacent to the first lane (L1), involves: setting a first proposal condition that is for proposing a first lane change from the first lane (L1) to the second lane (L2) by the host vehicle (V) and includes a condition that a prescribed first entry space (A1) allowing the host vehicle (V) to enter the second lane (L2) should be detected, and a second proposal condition that is for proposing a second lane change of returning from the second lane (L2) to the first lane (L1) by the host vehicle (V) after overtaking the preceding vehicle (Vx) and includes a condition that a prescribed second entry space (A2) allowing the host vehicle (V) to enter the first lane (L1) should be detected; and setting the length (D2) of the second entry space (A2) in the travel direction longer than the length (D1) of the first entry space (A1) in the travel direction.

Description

Driving assistance method and driving assistance device

[0001] The present invention relates to a driving assistance method and a driving assistance device.

[0002] A vehicle control device is known that, when a preceding vehicle is traveling in front of the host vehicle in a first lane in which the host vehicle is traveling and it is determined that an overtaking start condition is met, in which the host vehicle begins to overtake the preceding vehicle, moves the host vehicle from the first lane to a second lane adjacent to the first lane, and after the host vehicle has moved to the second lane, determines whether a return condition is met, and if it is determined that the return condition is met, moves the host vehicle from the second lane to the first lane, and if it is determined that the return condition is not met, causes the host vehicle to continue traveling along the second lane (Patent Document 1).

[0003] Japanese Patent Application Laid-Open No. 2021-88281

[0004] Because the above-mentioned return condition specifies only the traffic conditions in the first lane, a lane change to return to the original first lane is executed regardless of the conditions in the second lane. In contrast, because the above-mentioned overtaking start condition specifies the traffic conditions in the first and second lanes, in the above-mentioned conventional technology, a lane change from the first lane to the second lane to overtake a leading vehicle is more difficult to execute than a lane change to return to the original first lane. Therefore, in the above-mentioned conventional technology, there is a problem that the host vehicle travels for a long time under conditions in which it is difficult to overtake the leading vehicle, and the opportunity to overtake the leading vehicle is lost.

[0005] The problem to be solved by the present invention is to provide a driving assistance method and a driving assistance device that can prevent a host vehicle from missing an opportunity to overtake a leading vehicle.

[0006] The present invention solves the above problem by setting a first proposal condition for the host vehicle to make a first lane change from the first lane to the second lane when performing overtaking assistance control to overtake a preceding vehicle traveling in front of the host vehicle in a first lane by traveling in a second lane adjacent to the first lane, the first proposal condition including a condition under which a predetermined first entry space for the host vehicle to enter the second lane is detected, and a second proposal condition for the host vehicle to make a second lane change from the second lane back to the first lane after overtaking the preceding vehicle, the second proposal condition including a condition under which a predetermined second entry space for the host vehicle to enter the first lane is detected, and making the length of the second entry space in the direction of travel longer than the length of the first entry space in the direction of travel.

[0007] According to the present invention, it is possible to prevent the host vehicle from missing an opportunity to overtake the leading vehicle.

[0008] 1 is a block diagram showing an example of an embodiment of a driving assistance system according to the present invention. FIG. 2 is a front view showing a part of the input device of FIG. 1. FIG. 3 is a plan view showing an example of autonomous lane change control executed by the driving assistance system of FIG. 1. FIG. 4 is a plan view (part 1) showing an example of overtaking assist control executed by the driving assistance system of FIG. 1. FIG. 5 is a block diagram showing state transitions of the driving assistance device of FIG. 1. FIG. 6 is a plan view showing an example of a first approach space set by the driving assistance device of FIG. 1. FIG. 7 is a plan view showing an example of a second approach space set by the driving assistance device of FIG. 1. FIG. 8 is a diagram showing an example of thresholds of first and second distances set by the driving assistance device of FIG. 1. FIG. 9 is a plan view showing another example of the first approach space set by the driving assistance device of FIG. 1. FIG. 10 is a plan view showing another example of the second approach space set by the driving assistance device of FIG. 1. FIG. 11 is a flowchart showing an example of a processing procedure executed in the driving assistance system of FIG. 1 when suggesting that the driver change lanes. FIG. 12 is a flowchart showing an example of a processing procedure executed in the driving assistance system of FIG. 1 when a lane change is suggested to the driver. 10 is a flowchart showing another example of the processing procedure executed in the driving assistance system of FIG. 1 when execution of a lane change is suggested to the driver.

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the following description, it is assumed that vehicles drive on the left side of the road in countries that have laws stipulating left-hand traffic. In countries that have laws stipulating right-hand traffic, vehicles drive on the right side of the road, so the terms right and left in the following description should be interpreted as symmetrical.

[0010] [Configuration of Driving Assistance System] Fig. 1 is a block diagram showing an example of an embodiment of a driving assistance system according to the present invention. The driving assistance system drives a vehicle from its current location to a destination set by the vehicle's occupant through autonomous driving control. The autonomous driving control is the autonomous control of the vehicle's driving operations, and driving operations include all driving operations such as acceleration, deceleration, starting, stopping, and steering. The driving assistance system also provides information related to the autonomous driving control to the vehicle's occupant.

[0011] 1, a driving assistance system 10 of this embodiment includes an imaging device 11, a distance measuring device 12, an on-board sensor 13, a map database 14, a vehicle position detecting device 15, a navigation device 16, an input device 17, an actuator 18, a display device 19, and a driving assistance device 20. The devices that make up the driving assistance system 10 are communicably connected via a CAN (Controller Area Network) or other on-board LAN, and exchange information with each other.

[0012] The imaging device 11 is a camera equipped with an imaging element such as a CCD, and captures images of objects around the vehicle to generate an image including the objects. The imaging device 11 may be an infrared camera, a stereo camera, or the like. In order to prevent blind spots where the objects cannot be captured, multiple imaging devices 11 are provided on the front grille, side mirrors, rear bumper, etc. of the vehicle.

[0013] The ranging device 12 detects the relative distance and relative speed between the vehicle and an object. The ranging device 12 includes a laser radar, a millimeter-wave radar, a LiDAR (light detection and ranging) unit, etc. To prevent blind spots where an object cannot be detected, a plurality of ranging devices 12 are provided on one vehicle.

[0014] The objects detected by the imaging device 11 and the distance measuring device 12 are objects that exist on the road and its surroundings, including lane boundaries, center lines, road markings, medians, guardrails, curbs, road signs, traffic lights, crosswalks, etc. The objects also include obstacles that may affect the traveling of the host vehicle, such as other automobiles (other vehicles), motorcycles, bicycles, pedestrians, etc. Note that the host vehicle is not particularly limited.

[0015] The driving assistance device 20 acquires image information from the imaging device 11 and acquires position information of objects from the distance measuring device 12, and recognizes objects around the vehicle and the driving environment. The driving assistance device 20 acquires information at predetermined time intervals (for example, every 0.1 to 1 millisecond). The driving assistance device 20 may recognize the driving environment by integrating or synthesizing the information acquired from the imaging device 11 and the distance measuring device 12.

[0016] The on-board sensors 13 detect the driving state of the vehicle. The on-board sensors 13 include a vehicle speed sensor, an acceleration sensor, a yaw rate sensor, a steering angle sensor, and the like. The on-board sensors 13 also include a touch sensor (capacitive sensor) that detects whether the driver is holding the steering wheel. Any known sensor can be used without any particular limitations, and the arrangement and number of sensors can be set appropriately within a range that allows appropriate detection of the driving state of the vehicle. The driving assistance device 20 acquires the detection results of each sensor at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0017] The map database 14 is a storage medium that stores map information and is provided inside or outside the vehicle. The driving assistance device 20 acquires map information from the map database 14 as needed. The map information includes information on nodes corresponding to specific points on roads (such as intersections) where the vehicle's traveling direction changes, and links corresponding to road sections connecting the nodes. The node information includes location information and information on entering and exiting intersections, and the link information includes road width, road curvature radius, road shoulder structures, road traffic regulations, etc. The map information may be high-precision map information that can grasp the movement trajectory for each lane.

[0018] The vehicle position detection device 15 is a positioning system that detects the current position of the vehicle, and calculates the current position of the vehicle from, for example, radio waves received from a satellite for the GPS (Global Positioning System). Alternatively, the vehicle position detection device 15 may estimate the current position of the vehicle from vehicle speed information and acceleration information acquired from the on-board sensor 13, and calculate the current position of the vehicle by comparing the estimated current position with map information.

[0019] The navigation device 16 refers to map information and calculates a driving route from the current position of the vehicle detected by the vehicle position detection device 15 to the destination set by the occupant. The driving route includes information on at least the road on which the vehicle is traveling, the driving lane, and the direction of travel of the vehicle, and is displayed, for example, as a linear diagram. The calculated driving route is acquired by the driving assistance device 20.

[0020] The input device 17 is a device through which the occupant inputs instructions to the driving assistance device 20, and includes button switches that can be manually operated by the driver, a touch panel arranged on the display device 19, a microphone that can input voice commands by the driver, etc. Fig. 2 is a front view showing a part of the input device 17, and shows some of the button switches provided on the spokes of the steering wheel, etc. The input device 17 shown in Fig. 2 is used to set ON / OFF, etc., of the autonomous driving control (particularly autonomous speed control and autonomous steering control) by the driving assistance device 20.

[0021] As shown in FIG. 2, the input device 17 includes a main switch 171 , a resume / accelerate switch 172 , a set / coast switch 173 , a cancel switch 174 , a vehicle distance adjustment switch 175 , and a lane change assist switch 176 .

[0022] The main switch 171 is a switch that turns on / off the power supply of the system that realizes autonomous driving control of the driving assistance device 20. The resume / accelerate switch 172 is a switch that stops (OFF) the autonomous speed control and then resumes the autonomous speed control at the set speed before stopping, or increases the set speed. The set / coast switch 173 is a switch that starts the autonomous speed control at the traveling speed, or decreases the set speed. The cancel switch 174 is a switch that stops (OFF) the autonomous speed control. The distance adjustment switch 175 is a switch that sets the distance from the preceding vehicle. The lane change assistance switch 176 is a switch that instructs (agrees to) start a lane change when the driving assistance device 20 has confirmed with the driver that the lane change should be started.

[0023] 2 , a turn signal lever of a turn signal or other switches of in-vehicle equipment may also be used as the input device 17. For example, when the driving assistance device 20 suggests whether or not to automatically change lanes, if the driver operates the turn signal lever, the vehicle will change lanes in the direction in which the turn signal lever was operated, rather than the suggested lane change. The setting information input to the input device 17 is acquired by the driving assistance device 20.

[0024] 1 , the actuator 18 is a device that converts an electrical control signal input from the driving assistance device 20 into mechanical work, and includes a servo motor, a hydraulic motor, a hydraulic cylinder, etc. The actuator 18 operates the drive device and steering device of the host vehicle.

[0025] The display device 19 provides information to the occupants of the vehicle. The display device 19 is, for example, a liquid crystal display provided on the instrument panel, a projector such as a head-up display, and may include an input device for the occupant to input instructions to the driving assistance device 20, and a speaker as an output device.

[0026] The driving assistance device 20 controls and cooperates with the devices that make up the driving assistance system 10 to perform autonomous driving control of the vehicle. The driving assistance device 20 performs autonomous control of driving behavior using devices mounted on the vehicle, and controls the driving behavior within a predetermined range. Driving behavior that is not controlled by the driving assistance device 20 is manually operated by the driver. Note that when the driver drives the vehicle manually, the driving assistance device 20 does not perform autonomous control of driving behavior, and the driving behavior of the vehicle is controlled by the driver's operation.

[0027] The driving assistance device 20 is, for example, a computer, and includes a CPU (Central Processing Unit) which is a processor, a ROM (Read Only Memory) in which programs are stored, and a RAM (Random Access Memory) which functions as an accessible storage device. The CPU is an operating circuit for executing the programs stored in the ROM and realizing the functions of the driving assistance device 20.

[0028] [Functions of the Driving Assistance Device] A program for autonomous driving control of the vehicle is stored in the ROM of the driving assistance device 20, and autonomous driving control is performed by the CPU of the driving assistance device 20 executing the program. For convenience, Fig. 1 shows an assistance unit 21 and a setting unit 22 as functional blocks for performing autonomous driving control.

[0029] The support unit 21 reads various information such as image information of an image captured by the imaging device 11, position information of an object measured by the distance measuring device 12, detection information detected by the on-board sensor 13, map information stored in the map database 14, current position information detected by the vehicle position detection device 15, and information on a driving route set by the navigation device 16, and recognizes the current state of the driving environment around the vehicle based on this various information. Furthermore, the support unit 21 makes various determinations for executing autonomous driving control based on the recognized current state of the driving environment. The setting unit 22 sets conditions for the support unit 21 to make determinations.

[0030] The support unit 21 drives the host vehicle by autonomous driving control based on the determination result and provides necessary information to the occupants of the host vehicle. For example, the support unit 21 generates a driving trajectory for the host vehicle to drive along a driving route based on image information acquired from the imaging device 11 and position information of an object acquired from the distance measuring device 12, and generates a control signal to operate the actuator 18 so that the host vehicle drives along the driving trajectory. The support unit 21 also generates notification information to notify the occupants of the host vehicle about the autonomous driving control and outputs the notification information to the display device 19.

[0031] The support unit 21 performs autonomous driving control, which includes autonomous speed control for autonomously controlling the driving speed of the vehicle itself and autonomous steering control for autonomously controlling the steering operation of the vehicle itself. The autonomous speed control includes vehicle-to-vehicle control and constant-speed driving. That is, when a preceding vehicle is detected by the distance measuring device 12 or the like, the support unit 21 performs vehicle-to-vehicle control to maintain a vehicle-to-vehicle distance according to the driving speed, with the driving speed set by the driver as the upper limit, and causes the vehicle itself to follow the preceding vehicle. On the other hand, when a preceding vehicle is not detected by the distance measuring device 12 or the like, the support unit 21 performs constant-speed driving at the driving speed set by the driver.

[0032] When autonomous speed control is performed, the driver operates the resume / accelerate switch 172 or the set / coast switch 173 shown in Fig. 2 to input a desired traveling speed. The driver also sets a desired inter-vehicle distance by operating the inter-vehicle distance adjustment switch 175 shown in Fig. 2.

[0033] In inter-vehicle distance control, the actuator 18 controls the operation of the engine, brakes, and other drive devices while feeding back the detection results of the distance measuring device 12 so as to maintain a set inter-vehicle distance with a set travel speed as the upper limit. On the other hand, in constant speed control, the actuator 18 controls the operation of the engine, brakes, and other drive devices while feeding back the detection results of the vehicle speed sensor so as to maintain a set travel speed.

[0034] In the autonomous steering control, when a predetermined condition is met during execution of the autonomous speed control, the actuator 18 controls the operation of the steering device. The support unit 21 executes lane keeping control, autonomous lane change control, and overtaking support control as autonomous steering control.

[0035] Lane keeping control is a control that keeps the vehicle traveling along the lane in which it is traveling.In lane keeping control, the steering device is controlled by actuator 18 so that the vehicle travels near the center of the lane, and assists the driver in steering.

[0036] Autonomous lane change control is a control that uses autonomous driving control to change lanes from the lane in which the vehicle is traveling to an adjacent lane in a direction corresponding to the driver's operation. In autonomous lane change control, when the driver operates the turn signal lever, the turn signal is flashed, and when preset lane change initiation conditions are met, the lane change control (hereinafter also referred to as LCP), which is a series of processes for an automated lane change, is initiated. The turn signal lever is a rod-shaped operating member attached to the side of the steering column, and can be operated in the direction along the rotation direction of the steering wheel (turn signal) and in the directions forward and backward (high / low beam).

[0037] When the turn signal lever is operated clockwise along the direction of rotation, the turn signal on the right side of the vehicle's direction of travel will flash, and when the turn signal lever is operated counterclockwise, the turn signal on the left side of the vehicle's direction of travel will flash. If the driver wants to change lanes to the adjacent lane on the left side of the vehicle's direction of travel using autonomous lane change control, the driver does not turn the steering wheel but operates the turn signal lever in the direction corresponding to the left turn signal (counterclockwise), and if the driver wants to change lanes to the adjacent lane on the right side of the vehicle's direction of travel using autonomous lane change control, the driver operates the turn signal lever in the direction corresponding to the right turn signal (clockwise).

[0038] The support unit 21 determines whether a lane change start condition is met based on the recognized current state of the driving environment. Examples of the lane change start conditions include, but are not limited to, the lane keep mode of the hands-on mode, the driver continuously holding (touching) the steering wheel for a predetermined time (e.g., 5 to 20 seconds) or more, the vehicle traveling at a predetermined speed (e.g., 50 to 80 km / h) or more, the existence of a lane in the direction of the lane change, the lane to which the lane is to be changed has space for a lane change, the type of lane boundary line is one that allows a lane change, the radius of curvature of the road on which the vehicle is traveling is a predetermined radius (e.g., 200 to 300 m) or more (i.e., the road is not a sharp curve), and the driver has operated the turn signal lever within one second.

[0039] The lane keeping mode of the hands-on mode, which will be described in detail later, refers to a state in which autonomous speed control and lane keeping control are being executed and the driver's holding of the steering wheel is detected.

[0040] Furthermore, the autonomous lane change control may be started by an operation by the driver, or may be started when the execution of the autonomous lane change control is proposed to the driver by the assistance unit 21 and the driver accepts this proposal. Acceptance of the execution of the autonomous lane change control is input, for example, by the turn signal lever or the lane change assistance switch 176. Alternatively, the autonomous lane change control may be started when the driver does not reject the proposal within a predetermined time (for example, by operating the turn signal lever or steering wheel in the opposite direction to the proposed direction).

[0041] Fig. 3 is a plan view showing an example of autonomous lane change control executed by the driving assistance system 10 of Fig. 1. In the driving scene shown in Fig. 3, a two-lane road with lanes L1 and L2 on each side extends left and right in the drawing. On the road shown in Fig. 3, the host vehicle is assumed to travel from left to right in the drawing.

[0042] In the driving scene shown in Fig. 3, the host vehicle V is traveling at position P1 on lane L1, heading toward destination X located ahead on lane L2. In addition, in the driving scene shown in Fig. 3, the power of the system that realizes autonomous driving control is ON, predetermined conditions described below are satisfied, so autonomous lane change control is executable, and after the host vehicle V travels from position P1 to position P2 along driving trajectory T1, at position P2, the driver of the host vehicle V operates the turn signal lever of the host vehicle V to flash the right turn signal of the host vehicle V.

[0043] In this case, the support unit 21 detects a space for the host vehicle V to enter in a lane L2 (adjacent lane) adjacent to the lane L1 (host lane) based on image information captured by the imaging device 11 and position information of the object measured by the distance measuring device 12. In the driving scene shown in Fig. 3, there are no other vehicles traveling in the lane L2, so a space for the host vehicle V to enter in the lane L2 is detected. Therefore, the lane change start condition is satisfied if the autonomous driving control mode is a lane keeping mode in a hands-on mode, a hands-on determination is in progress, the traveling speed of the host vehicle V is equal to or greater than a predetermined speed, the type of the lane boundary line between the lanes L1 and L2 is a type that allows lane changes, the radius of curvature of the road is equal to or greater than a predetermined radius, and it has been within one second since the driver operated the turn signal lever.

[0044] When the lane change initiation condition is satisfied, the assistance unit 21 initiates the LCP by autonomous lane change control. This LCP includes a lateral movement of the host vehicle V into an adjacent lane (i.e., lane L2) and a lane change maneuver (hereinafter referred to as LCM) in which the host vehicle V actually moves across the lane boundary line into lane L2. Specifically, the assistance unit 21 generates a travel trajectory T2 shown in FIG. 3 and generates a control signal for operating the actuator 18 so that the host vehicle V travels along the travel trajectory T2 from position P2 to position P6.

[0045] The assistance unit 21 starts lateral movement to lane L2 at position P3 and starts LCM at position P4. While traveling from position P3 to position P4, the actuator 18 rotates the steering wheel of the host vehicle V to the right (clockwise) in the direction of travel. After crossing the lane boundary line, while traveling to position P5, the actuator 18 rotates the steering wheel of the host vehicle V to the left (counterclockwise) in the direction of travel, and at position P5, the steering wheel returns to the neutral position and the turn signal is turned off. The driving assistance device 20 completes LCM at position P5 and completes LCP at position P6 to resume lane keeping control. This completes lane change control from lane L1 to lane L2. While autonomous lane change control is being performed, the assistance unit 21 notifies the driver using the display device 19 that a lane change is being performed.

[0046] The LCP based on the autonomous lane change control described above is also executed when the driving assistance device 20 proposes the execution of autonomous lane change control to the driver and the driver accepts this proposal by operating the lane change assistance switch 176. In this case, however, the blinking of the turn signal is controlled by the driving assistance device 20. That is, the driving assistance device 20 keeps the turn signal blinking while traveling from position P3 to position P5, and turns the turn signal off at position P5.

[0047] The overtaking assist control is a combination of lane keeping control and autonomous lane change control, and is autonomous lane change control in a driving scene in which the vehicle is overtaking a preceding vehicle in the vehicle's own lane. Figures 4A and 4B are plan views showing an example of a driving scene in which the support unit 21 executes the overtaking assist control. The driving scene shown in Figures 4A and 4B is the same as the driving scene shown in Figure 2, except that the preceding vehicle Vx is traveling at position Px in lane L1.

[0048] 4A , when a preceding vehicle Vx slower than the host vehicle V is present ahead in the lane L1 and a predetermined overtaking suggestion condition is satisfied, the support unit 21 presents overtaking information to the driver using the display device 19. The overtaking information is information that suggests to the driver that the host vehicle V should overtake the preceding vehicle Vx.

[0049] The support unit 21 starts the LCP described above when the driver, in response to the presentation of the overtaking information, operates a switch provided on the steering wheel to agree to the execution of overtaking and when a preset overtaking start condition is satisfied. The driver may also agree to the execution of overtaking by operating the turn signal lever to the right or left.

[0050] The support unit 21 determines whether the overtaking suggestion condition and the overtaking start condition are satisfied based on the recognized driving environment. Note that the overtaking support control may include a function of starting an LCP for overtaking the preceding vehicle Vx when the driver operates the turn signal lever, even if the overtaking information is not presented.

[0051] The overtaking suggestion conditions include, but are not limited to, the following: the vehicle is in lane keeping mode in hands-off mode; the vehicle V's traveling speed is a predetermined speed (e.g., 50 to 80 km / h) or higher; there is a lane in the direction of the lane change; there is space in the lane to which the lane change is to be made in 5 seconds; the lane boundary line is a type that allows for lane changes; the radius of curvature of the road on which the vehicle V is traveling is a predetermined radius (e.g., 200 to 300 m) or higher (i.e., it is not a sharp curve); the vehicle V's traveling speed is slower than the set speed by a predetermined speed (e.g., 5 km / h) or more; the traveling speed of the preceding vehicle Vx is slower than the set speed by a predetermined speed (e.g., 10 km / h) or more; the inter-vehicle distance between the vehicle V and the preceding vehicle Vx is below a threshold value that is preset based on the speed difference between the vehicle V and the preceding vehicle Vx; and the traveling speed of the preceding vehicle Vx in the lane to which the lane change is to be made satisfies a predetermined condition.

[0052] The lane keeping mode of the hands-off mode, which will be described in detail later, refers to a mode in which autonomous speed control and lane keeping control are active and the driver does not need to hold the steering wheel. The condition that the speed of the preceding vehicle in the destination lane satisfies a predetermined condition varies depending on the type of destination lane. For example, when changing lanes from the left lane to the right lane on a multi-lane road with left-hand traffic, the speed of the host vehicle V in the left lane must be faster than the speed of the preceding vehicle in the right lane by a predetermined speed (e.g., 5 km / h) or more. Conversely, when changing lanes from the right lane to the left lane on a multi-lane road with left-hand traffic, the speed difference between the host vehicle V and the preceding vehicle in the left lane must be within a predetermined speed difference (e.g., 5 km / h). The condition regarding the relative speed difference between the host vehicle V and the preceding vehicle in the adjacent lane is reversed on roads with right-hand traffic.

[0053] When the driver agrees to the presentation of overtaking information and a predetermined overtaking start condition is satisfied, the support unit 21 flashes the turn signal through overtaking support control and starts the LCP. The overtaking start condition is not particularly limited, but may include, in addition to the overtaking suggestion condition, being within 10 seconds of operating the switch (lane change support switch 176) that agrees to the start of autonomous lane change control.

[0054] 4A , a lane L2 exists to the right of a straight lane L1, and there is space in lane L2 for the host vehicle V to enter. This space still exists five seconds later. Therefore, the overtaking suggestion condition is satisfied if the following conditions are met: the host vehicle V is in lane-keeping mode in hands-off mode, the host vehicle V is traveling at 60 km / h or faster, a lane change from lane L1 to lane L2 is possible, the host vehicle V's traveling speed is 5 km / h or slower than the set speed, the preceding vehicle Vx's traveling speed is 10 km / h or slower than the set speed, and the inter-vehicle distance between the host vehicle V and the preceding vehicle Vx is below a threshold value that is preset based on the speed difference between the host vehicle V and the preceding vehicle Vx. If the overtaking suggestion condition is satisfied, the support unit 21 displays overtaking information using the display device 19 while the host vehicle V is traveling at position Q1.

[0055] When the driver is presented with the overtaking information and agrees to execute the overtaking, the assistance unit 21 determines whether or not the overtaking start condition is met. In the driving scene of FIG. 4A , the overtaking suggestion condition is met, so a hands-on determination is being made, and if it is within 10 seconds of the operation of the lane change assistance switch 176, the overtaking start condition is met. In the driving scene shown in FIG. 4A , it is assumed that the driver inputs consent to the execution of overtaking assistance control while the host vehicle V is traveling at position Q2 along the traveling trajectory T3. If the overtaking start condition is met, LCP is initiated by overtaking assistance control, and lateral movement to an adjacent lane and LCM are executed.

[0056] Specifically, the driving assistance device 20 generates a driving trajectory T4 shown in FIG. 4A , follows the driving trajectory T4, travels from position Q3 to position Q7, and changes lanes from lane L1 to lane L2. The assistance unit 21 starts flashing the turn signal at position Q3, starts lateral movement to lane L2 at position Q4, and starts LCM at position Q5. The assistance unit 21 turns off the turn signal at position Q6 to complete LCM. Then, at position Q7, the assistance unit 21 completes LCP and starts lane keeping control. The host vehicle V travels in lane L2 under lane keeping control and overtakes the preceding vehicle Vx.

[0057] After the preceding vehicle Vx has been overtaken by the overtaking assist control, if the overtaking suggestion conditions are satisfied again, the support unit 21 suggests to the driver to return to the original lane L1 via the display device 19. If the driver accepts this suggestion by operating the lane change assist switch 176 and if the overtaking start conditions are satisfied, the support unit 21 starts the LCP to return the host vehicle V to the original lane L1 by the overtaking assist control, as shown in FIG.

[0058] Specifically, when the overtaking suggestion condition is satisfied, the support unit 21 presents overtaking information using the display device 19 when the host vehicle V is traveling at position Q7. Then, when the driver inputs consent to the execution of overtaking assist control while the host vehicle V is traveling at position Q8, the support unit 21 generates the traveling trajectory T5 shown in FIG. 4B , travels from position Q9 to position Q13 following the traveling trajectory T5, and changes lanes from lane L2 to the original lane L1. The support unit 21 starts flashing the turn signal at position Q9, starts lateral movement to lane L1 at position Q10, and starts LCM at position Q11. The support unit 21 turns off the turn signal at position Q12 and completes LCM. Then, the support unit 21 completes LCP at position Q13 and starts lane keeping control.

[0059] 5 is a block diagram showing state transitions of the functions established in the driving assistance device 20. The system shown in FIG.

[0060] First, when the main switch is turned on from the system-off state shown in Fig. 5, the system enters a standby state. The main switch is a switch that turns on / off the power supply of the system that realizes the autonomous speed control and autonomous steering control of the driving assistance device 20, and is provided on the steering wheel, for example.

[0061] From the standby state, the autonomous speed control is activated by turning on the set coast switch 173 or the resume accelerate switch 172. This starts the constant speed control or vehicle distance control described above, and the driver can drive the host vehicle V by simply operating the steering wheel without stepping on the accelerator or brake.

[0062] 5 is satisfied during execution of autonomous speed control, the system transitions to lane keeping mode of the autonomous steering control / hands-on mode. This condition (1) includes the following: lane boundary lines on both sides of the host vehicle V are detected, the driver is holding the steering wheel, the host vehicle V is traveling near the center of the lane, the turn signal is not activated, and the wipers are not operating at high speed (HI).

[0063] The hands-on mode is a mode in which the autonomous steering control does not operate unless the driver holds the steering wheel, while the hands-off mode is a mode in which the autonomous steering control operates even if the driver takes their hands off the steering wheel. The driver's holding of the steering wheel is detected by a touch sensor on the steering wheel.

[0064] 5 is satisfied while the lane keeping mode of the autonomous steering control hands-on mode is being executed, the system transitions to the lane keeping mode of the autonomous steering control hands-off mode. This condition (2) includes the availability of high-precision map information of the road on which the vehicle is traveling, the current position of the host vehicle V being detected by the host vehicle position detection device 15, and the absence of an intersection, merging point, tunnel, or sharp curve with a curvature radius of 100 Rm or less within a predetermined distance (for example, 500 to 800 m) ahead of the host vehicle V.

[0065] Conversely, if condition (3) in Fig. 5 is met while the lane keeping mode of the autonomous steering control hands-off mode is being executed, the mode transitions to the lane keeping mode of the autonomous steering control hands-on mode. This condition (3) can be met when the host vehicle V is traveling on a road other than a motorway, when the traveling speed of the host vehicle V exceeds the speed limit, when the driver is holding the steering wheel and depressing the accelerator pedal, etc.

[0066] When the lane-keeping mode of the autonomous steering control / hands-off mode is being executed, if the condition (4) in Fig. 5 is satisfied, the autonomous steering control is stopped and the system transitions to the autonomous speed control. An example of this condition (4) is when the driver is operating the steering wheel.

[0067] Furthermore, if the condition (5) in Fig. 5 is satisfied while the lane keeping mode of the autonomous steering control / hands-off mode is being executed, the autonomous steering control and autonomous speed control are stopped and the system transitions to a standby state. This condition (5) can be satisfied when the driver operates the brakes or when the driver operates the cancel switch 174 in Fig. 2.

[0068] 5 is satisfied while the autonomous steering control / hands-on mode is being executed, the autonomous steering control is stopped and transition is made to autonomous speed control. This condition (6) can be satisfied when the driver operates the steering wheel or turn signal lever, or when lane boundary lines on at least one side of the host vehicle V are not detected.

[0069] Furthermore, if the condition (7) in Fig. 5 is satisfied while the autonomous steering control / hands-on mode is being executed, the autonomous steering control and autonomous speed control are stopped and the vehicle transitions to a standby state. This condition (7) can be satisfied when the driver operates the brakes or when the driver operates the cancel switch 174 in Fig. 2.

[0070] If condition (8) in Fig. 5 is met while autonomous speed control is being executed, the vehicle transitions to the standby state. This condition (8) can be met when the driver operates the brakes or when the driver operates a cancel switch to turn off autonomous speed control.

[0071] 5 is satisfied while the lane keep mode of the autonomous steering control hands-off mode is being executed, the system transitions to the lane change mode of the autonomous steering control hands-on mode. Examples of this condition (9) include the driver operating the lane change assist switch 176 in response to a lane change suggestion from the driving assistance system 10, or the driver operating the turn signal lever to execute autonomous lane change control.

[0072] If the condition (10) in Fig. 5 is satisfied while the lane change mode of the autonomous steering control hands-on mode is being executed, the autonomous steering control hands-on mode will transition to the lane keep mode. An example of this condition (10) is when the driving speed exceeds the speed limit before the start of the LCP.

[0073] When the main switch is turned off in any of the following states: autonomous steering control hands-off mode, autonomous steering control hands-on mode, autonomous speed control, or standby mode, the system is turned off.

[0074] When the driving assistance device 20 of this embodiment detects a leading vehicle (hereinafter also referred to as a first leading vehicle) in the host vehicle's lane using the imaging device 11 or the like, it determines whether or not to execute overtaking assistance control to overtake the first leading vehicle, which is traveling in front of the host vehicle V in the first lane in which the host vehicle V is traveling, by traveling in a second lane adjacent to the first lane, based on the traveling speed of the first leading vehicle detected by the distance measuring device 12 or the like. In this case, the driving assistance device 20 sets, by the function of the setting unit 22, a lane change proposal condition (overtaking proposal condition) to be executed in the overtaking assistance control.

[0075] The setting unit 22 sets a first proposal condition that proposes a first lane change for the host vehicle V from the first lane to the second lane, and a second proposal condition that proposes a second lane change for the host vehicle V to return from the second lane to the first lane after overtaking a first preceding vehicle. The first proposal condition includes a condition that a predetermined first entry space for the host vehicle V to enter the second lane is detected, and the second proposal condition includes a condition that a predetermined second entry space for the host vehicle V to enter the first lane is detected. In addition, the length of the second entry space in the traveling direction of the host vehicle V (hereinafter simply referred to as the traveling direction) is set to be longer than the length of the first entry space in the traveling direction.

[0076] 6A is a plan view showing an example of a first entry space set by the setting unit 22, and the driving scene shown in Fig. 6A is the same as the driving scene shown in Fig. 4A except for the driving position of the host vehicle V. When performing overtaking assist control to overtake a first preceding vehicle Vx traveling in front of the host vehicle V in the lane L1 on which the host vehicle V is traveling by traveling in a lane L2 adjacent to the lane L1, the setting unit 22 sets, as one of the first proposed conditions, a condition under which a first entry space A1 through which the host vehicle V will enter the lane L2 is detected.

[0077] If an obstacle or the like is present in lane L2 and the first entry space A1 is not detected in lane L2, the support unit 21 determines that the overtaking proposal condition is not met. On the other hand, if the first entry space A1 is detected in lane L2, the execution of the first lane change is proposed when all other conditions set as the first proposal condition are met. Specifically, the display device 19 is used to request the driver of the host vehicle V to agree to the execution of the first lane change.

[0078] 6B is a plan view showing an example of a second entry space set by the setting unit 22. The driving scene shown in FIG. 6B is the same as the driving scene shown in FIG. 4B except for the driving position of the host vehicle V. When executing overtaking assist control, the setting unit 22 sets, as one of the second proposed conditions, a condition under which a second entry space A2 into which the host vehicle V enters the lane L1 is detected. As shown in FIGS. 6A and 6B , the length D2 in the traveling direction of the second entry space A2 is longer than the length D1 in the traveling direction of the first entry space A1.

[0079] The first approach space A1 can be set to an appropriate range within a range that allows the host vehicle V to enter lane L2 (second lane) without coming into contact with an obstacle, and the length D1 of the first approach space A1 in the traveling direction is, for example, the sum of the normal driving distance (e.g., 15 to 30 m) for the host vehicle V to change lanes to an adjacent lane and the distance (e.g., 5 to 10 m) for avoiding contact with a following vehicle traveling in the adjacent lane. In this case, the front end of the first approach space A1 is set at a position corresponding to a position forward of the host vehicle V on lane L1 (first lane) the normal driving distance for changing lanes, and the rear end of the first approach space A1 is set at a position corresponding to a position rearward of the host vehicle V on lane L1 the distance for avoiding contact with a following vehicle.

[0080] The difference between the length D2 of the second entry space A2 in the traveling direction and the length D1 of the first entry space A1 in the traveling direction can be set to an appropriate value within a range in which the host vehicle V can appropriately change lanes from lane L2 to lane L1, for example, 5 to 30 m. Alternatively, the length D2 of the second entry space A2 in the traveling direction may be set by multiplying the length D1 of the first entry space A1 in the traveling direction by a predetermined coefficient (for example, 1.5 to 3.0).

[0081] Furthermore, when the position of the host vehicle V is used as a reference, the position of the front end of the second entry space A2 may be forward of the position of the front end of the first entry space A1. Also, when the position of the host vehicle V is used as a reference, the position of the rear end of the second entry space A2 may be rear of the position of the rear end of the first entry space A1. In other words, the distance between the host vehicle V and the front end of the second entry space A2 may be longer than the distance between the host vehicle V and the front end of the first entry space A1, and the distance between the host vehicle V and the rear end of the second entry space A2 may be longer than the distance between the host vehicle V and the rear end of the first entry space A1.

[0082] In the driving scene shown in Figure 6A, there are no other vehicles traveling on lane L2 and a first entry space A1 is detected on lane L2, so if all other conditions set as the first proposal conditions are met, the assistance unit 21 suggests to the driver that they perform a lane change from lane L1 to lane L2 (first lane change).

[0083] On the other hand, in the driving scene shown in FIG. 6B , a first leading vehicle Vx is present traveling on lane L1, and the first leading vehicle Vx is included in the second entry space A2 on lane L1. Therefore, the second entry space A2 is not detected, and the assistance unit 21 determines that the second proposal condition is not satisfied. Therefore, the assistance unit 21 does not suggest to the driver that the driver change lanes from lane L2 to lane L1 (second lane change). As a result, when another leading vehicle (not shown) is present ahead of the first leading vehicle Vx, the host vehicle V can continue traveling on lane L2 without returning to lane L1, and smoothly overtake the other leading vehicle. In other words, the host vehicle V can be prevented from missing an opportunity to overtake the leading vehicle.

[0084] When a leading vehicle (hereinafter also referred to as a second leading vehicle) traveling in the second lane is present, the setting unit 22 may set the length of the first entry space in the traveling direction to a first distance corresponding to the speed difference between the host vehicle V and the second leading vehicle, and may set the length of the second entry space in the traveling direction to a second distance corresponding to the speed difference between the host vehicle V and the first leading vehicle. In this case, the setting unit 22 sets the second distance so that the second distance is longer than the first distance when the speed difference between the host vehicle V and the first leading vehicle and the speed difference between the host vehicle V and the second leading vehicle are the same value. In other words, when the speed difference between the host vehicle V and another vehicle traveling in the lane to which the lane is to be changed is the same, the setting unit 22 sets the second distance set as the second proposal condition to be longer than the first distance set as the first proposal condition.

[0085] FIG. 7 is a diagram showing an example of thresholds for the first distance and the second distance set by the setting unit 22. The horizontal axis of the graph shown in FIG. 7 indicates the speed difference with another vehicle (first preceding vehicle or second preceding vehicle) traveling in the lane to which the host vehicle V is about to change lanes. In the positive direction of the horizontal axis (right side of the graph), the traveling speed of the other vehicle (leading vehicle) is faster, and in the negative direction of the horizontal axis (left side of the graph), the traveling speed of the host vehicle V is faster. On the other hand, the vertical axis of the graph shown in FIG. 7 indicates the length of the entry space to be detected. The positive direction of the vertical axis (upper side of the graph) indicates the length of the entry space ahead of the host vehicle V, and the negative direction of the vertical axis (lower side of the graph) indicates the length of the entry space behind the host vehicle V.

[0086] The setting unit 22 sets the first distance based on, for example, thresholds B1 and B2 shown in Fig. 7, and sets the second distance based on thresholds C1 and C2. In this case, as shown in Fig. 7, when the speed difference between the host vehicle V and another vehicle (first leading vehicle or second leading vehicle) traveling in the lane to which the host vehicle V is about to change lanes is within a predetermined range, the second distance is set to be longer than the first distance for the same speed difference.

[0087] The predetermined range can be set to an appropriate value within a range in which an appropriate lane change can be suggested for the host vehicle V. The predetermined range is, for example, a range of 0 to 30 km / h for the speed difference between the host vehicle V and the other vehicle (preceding vehicle), which corresponds to the range of −30 km / h to 30 km / h on the horizontal axis when shown in the graph of Fig. 7. In other words, the positive side of the horizontal axis corresponds to the case in which the host vehicle V is slower than the other vehicle, and the negative side of the horizontal axis corresponds to the case in which the host vehicle V is faster than the other vehicle.

[0088] 8A is a plan view showing another example of the first entry space set by the setting unit 22. The driving scene shown in Fig. 8A is similar to the driving scene shown in Fig. 6A except that the second preceding vehicle Vy is traveling in lane L2. In the driving scene shown in Fig. 8A, the second preceding vehicle Vy is detected by the imaging device 11 and the distance measuring device 12 of the host vehicle V, and the value of the speed difference between the traveling speed of the host vehicle V acquired from the vehicle speed sensor (on-board sensor 13) and the detected traveling speed of the second preceding vehicle Vy is assumed to be the speed difference Z shown in Fig. 7.

[0089] In this case, the setting unit 22 sets a first entry space A3 in which the length of the space ahead of the host vehicle V is length D3 and the length of the space behind the host vehicle V is length D4, and sets, as the first proposed condition, a condition under which the first entry space A3 in which the host vehicle V enters the lane L2 is detected. The lengths D3 and D4 correspond to the values ​​of the thresholds B1 and B2 for the speed difference Z shown in FIG. 7 , respectively, and the sum of the lengths D3 and D4 is the first distance.

[0090] In the driving scene shown in Figure 8A, the second preceding vehicle Vy is not included in the first entry space A3 of lane L2, and the first entry space A3 is detected in lane L2, so if all other conditions set as the first proposal conditions are met, the assistance unit 21 suggests to the driver that they perform a lane change from lane L1 to lane L2 (first lane change).

[0091] 8B is a plan view showing another example of the second entry space set by the setting unit 22. The driving scene shown in Fig. 8B is similar to the driving scene shown in Fig. 6B except that the second preceding vehicle Vy is traveling in lane L2. In the driving scene shown in Fig. 8B, the first preceding vehicle Vx is detected by the imaging device 11 and the distance measuring device 12 of the host vehicle V, and the value of the speed difference between the traveling speed of the host vehicle V acquired from the vehicle speed sensor (on-board sensor 13) and the detected traveling speed of the first preceding vehicle Vx is assumed to be the speed difference Z shown in Fig. 7.

[0092] In this case, the setting unit 22 sets a second entry space A4 in which the length of the space ahead of the host vehicle V is length D5 and the length of the space behind the host vehicle V is length D6, and sets, as the second proposed condition, a condition under which the second entry space A4 in which the host vehicle V enters the lane L1 is detected. The lengths D5 and D6 correspond to the values ​​of the thresholds C1 and C2 for the speed difference Z shown in FIG. 7, respectively, and the sum of the lengths D5 and D6 is the second distance.

[0093] In the driving scene shown in Figure 8B, the first preceding vehicle Vx is included in the second entry space A4 in lane L1, so the second entry space A4 is not detected in lane L1. Therefore, the assistance unit 21 does not suggest to the driver that the driver change lanes from lane L2 to lane L1 (second lane change). In this way, the second entry space A4 shown in Figure 8B, like the second entry space A2 shown in Figure 6B, has the effect of preventing the host vehicle V from losing an opportunity to overtake the preceding vehicle.

[0094] The assistance unit 21 determines whether a first proposal condition is satisfied based on an image captured by the imaging device 11, and if it determines that the first proposal condition is satisfied, it proposes to the driver of the host vehicle V that the host vehicle V execute a first lane change. If a first operation by the driver agreeing to execute the first lane change in response to this proposal is detected, the assistance unit 21 starts the first lane change. On the other hand, if a first operation in response to the proposal to execute the first lane change is not detected, the assistance unit 21 continues to propose the execution of the first lane change. Furthermore, if a first operation in response to the proposal to execute the first lane change is not detected, the assistance unit 21 may cancel the proposal to execute the first lane change and cancel the overtaking assist control.

[0095] Similarly, after traveling in the second lane and overtaking the first preceding vehicle, the assistance unit 21 determines whether a second proposal condition is satisfied, and if it determines that the second proposal condition is satisfied, suggests to the driver that the second lane change be performed. If a second operation by the driver agreeing to perform the second lane change in response to this proposal is detected, the assistance unit 21 starts the second lane change. On the other hand, if a second operation in response to the proposal to perform the second lane change is not detected, the assistance unit 21 continues to suggest the second lane change. Furthermore, if a second operation in response to the proposal to perform the second lane change is not detected, the assistance unit 21 may cancel the proposal to perform the second lane change and cancel the overtaking assist control.

[0096] Furthermore, the assistance unit 21 determines whether a first proposal condition is satisfied, and if it is determined that the first proposal condition is satisfied, it proposes to the driver of the host vehicle V that the host vehicle V execute a first lane change. If the assistance unit 21 has continuously proposed the execution of the first lane change for a first predetermined time since the assistance unit 21 proposed the execution of the first lane change, the assistance unit 21 may determine whether a first operation by the driver agreeing to the execution of the first lane change has been detected within the first predetermined time since the assistance unit 21 proposed the execution of the first lane change. If it is determined that the first operation has not been detected within the first predetermined time since the assistance unit 21 proposed the execution of the first lane change, the assistance unit 21 starts the first lane change regardless of whether the driver agrees.

[0097] Similarly, after traveling in the second lane and overtaking the first preceding vehicle, the assistance unit 21 determines whether a second proposal condition is satisfied, and if it determines that the second proposal condition is satisfied, suggests to the driver that the second lane change be made. If the assistance unit 21 continues to propose the second lane change for a second predetermined time after proposing the second lane change, the assistance unit 21 may determine whether a second operation by the driver agreeing to the second lane change is detected within the second predetermined time after the proposal. If it determines that a second operation is not detected within the second predetermined time after the proposal to make the second lane change, the assistance unit 21 starts the second lane change regardless of whether the driver agrees. The first and second predetermined times can be set as appropriate within a range that allows the driver to consider the proposal to make a lane change, for example, 5 to 10 seconds.

[0098] 9 to 11, the procedure for processing information by the driving assistance device 20 will be described. The processing described below is executed by a processor (CPU) included in the driving assistance device 20 at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0099] 9 is a flowchart showing an example of a processing procedure executed by the driving assistance system 10 when suggesting to the driver to execute a lane change. First, in step S1, the driving assistance device 20 determines whether autonomous lane change control is executable. That is, the driving assistance device 20 determines whether the execution conditions for autonomous lane change control are satisfied from the driving environment recognized by the function of the assistance unit 21.

[0100] If it is determined that autonomous lane change control is not possible, the process proceeds to step S6, where execution of the routine is terminated without suggesting execution of a lane change. In other words, the driving assistance device 20 does not execute overtaking assistance control. On the other hand, if it is determined that autonomous lane change control is possible, the process proceeds to step S2.

[0101] In step S2, the driving assistance device 20 determines whether the first proposal condition is satisfied. That is, the driving assistance device 20 determines whether a preceding vehicle Vx traveling in the own lane is detected by the imaging device 11 or the like, whether the set speed of the own vehicle V is faster than the traveling speed of the preceding vehicle Vx by a predetermined speed (e.g., 10 km / h) or more, whether there is space in the adjacent lane that the own vehicle V can enter, etc. If it is determined that the first proposal condition is satisfied, the process proceeds to step S3, and the driving assistance device 20 proposes to the driver to execute the first lane change.

[0102] On the other hand, if it is determined that the first proposal condition is not satisfied, the process proceeds to step S4, where it is determined whether the second proposal condition is satisfied. If it is determined that the second proposal condition is satisfied, the process proceeds to step S5, where the driving assistance device 20 proposes to the driver that the second lane change be performed. On the other hand, if it is determined that the second proposal condition is not satisfied, the process proceeds to step S6.

[0103] 10 is a flowchart showing an example of a processing procedure executed by the driving assistance system 10 when a lane change is suggested to the driver. First, in step S11, the driving assistance device 20 determines whether autonomous lane change control is feasible, as in step S1. If it is determined that autonomous lane change control is not feasible, the process proceeds to step S19, where the suggestion to make the first lane change (or the second lane change) is canceled.

[0104] On the other hand, if it is determined that autonomous lane change control is executable, the process proceeds to step S12, where the driving assistance device 20 determines whether or not the driver has input an operation to accept the proposal. If it is determined that the driver has input an operation to accept the proposal, the process proceeds to step S13, where the first lane change (or second lane change) is initiated. On the other hand, if it is determined that the driver has not input an operation to accept the proposal, the process proceeds to step S14.

[0105] In step S14, the driving assistance device 20 determines whether the first proposal condition is satisfied. If it is determined that the first proposal condition is satisfied, the process proceeds to step S15, where the proposal to execute the first lane change continues. On the other hand, if it is determined that the first proposal condition is not satisfied, the process proceeds to step S16, where the process determines whether the execution of the first lane change is being proposed. If it is determined that the execution of the first lane change is being proposed, the process proceeds to step S19. On the other hand, if it is determined that the execution of the first lane change is not being proposed, the process proceeds to step S17.

[0106] In step S17, the driving assistance device 20 determines whether the second proposal condition is satisfied. If it is determined that the second proposal condition is satisfied, the driving assistance device 20 proceeds to step S18 and continues to propose the execution of the second lane change. On the other hand, if it is determined that the second proposal condition is not satisfied, the driving assistance device 20 proceeds to step S19.

[0107] Next, Fig. 11 is a flowchart showing another example of the processing procedure executed by the driving assistance system 10 when a lane change is suggested to the driver, and is obtained by adding steps S20 and S21 to the flowchart shown in Fig. 10. In the following explanation, explanations of steps S11 to S19 that overlap with Fig. 10 will be omitted.

[0108] If it is determined in step S14 that the first proposal condition is satisfied, the flow proceeds to step S20 in the flowchart shown in Fig. 11. In step S20, the driving assistance device 20 determines whether or not a first predetermined time has elapsed. If it is determined that the first predetermined time has not elapsed, the flow proceeds to step S15. On the other hand, if it is determined that the first predetermined time has elapsed, the flow proceeds to step S13, where the first lane change is executed regardless of the driver's operation.

[0109] Furthermore, if it is determined in step S17 that the second proposal condition is satisfied, the flow proceeds to step S21 in the flowchart shown in Fig. 11. In step S21, the driving assistance device 20 determines whether or not a second predetermined time has elapsed. If it is determined that the second predetermined time has not elapsed, the flow proceeds to step S18. On the other hand, if it is determined that the second predetermined time has elapsed, the flow proceeds to step S13, where the second lane change is executed regardless of the driver's operation.

[0110] According to this embodiment, in a vehicle driving assistance method executed by a driving assistance device 20 of a host vehicle V, when the driving assistance device 20 executes overtaking assistance control to overtake a first preceding vehicle Vx traveling ahead of the host vehicle V in a first lane in which the host vehicle V is traveling by traveling in a second lane adjacent to the first lane, the driving assistance device 20 sets a first proposal condition for the host vehicle V to propose a first lane change from the first lane to the second lane, and the host vehicle V is positioned in the second lane. and a second proposal condition for proposing a second lane change in which the host vehicle V returns from the second lane to the first lane after overtaking the first preceding vehicle Vx, the second proposal condition including a condition in which a predetermined second entry space A2 into which the host vehicle V will enter is detected in the first lane, wherein a length D2 of the second entry space A2 in the traveling direction of the host vehicle V is longer than a length D1 of the first entry space A1 in the traveling direction. This makes it possible to prevent the host vehicle V from losing an opportunity to overtake the preceding vehicle.

[0111] In the vehicle driving assistance method of this embodiment, when a second leading vehicle Vy traveling in the second lane is present, the driving assistance device 20 sets the length of the first entry space A3 in the traveling direction to a first distance corresponding to the speed difference between the host vehicle V and the second leading vehicle Vy, sets the length of the second entry space A3 in the traveling direction to a second distance corresponding to the speed difference between the host vehicle V and the first leading vehicle, and sets the second distance so that the second distance is longer than the first distance when the speed difference between the host vehicle V and the first leading vehicle Vx and the speed difference between the host vehicle V and the second leading vehicle Vy are the same value. This makes it possible to set an entry space appropriate for the driving scene.

[0112] In the vehicle driving assistance method of this embodiment, the driving assistance device 20 determines whether the first proposal condition is satisfied, and if it determines that the first proposal condition is satisfied, proposes to the driver of the host vehicle V that the host vehicle V execute the first lane change, and when a first operation by the driver agreeing to execute the first lane change is detected, starts the first lane change, thereby enabling the first lane change to be executed.

[0113] In the vehicle driving assistance method of this embodiment, after the vehicle travels in the second lane and overtakes the first preceding vehicle Vx, the driving assistance device 20 determines whether the second proposal condition is satisfied, and if it determines that the second proposal condition is satisfied, proposes to the driver that the second lane change be performed, and if a second operation by the driver agreeing to the execution of the second lane change is detected, starts the second lane change, thereby enabling the second lane change to be performed.

[0114] In the vehicle driving assistance method of this embodiment, the driving assistance device 20 determines whether the first proposal condition is satisfied, and if it determines that the first proposal condition is satisfied, proposes to the driver of the host vehicle V to execute the first lane change, and if the proposal to execute the first lane change has continued for a first predetermined time since the proposal, determines whether a first operation by the driver to agree to the execution of the first lane change has been detected within the first predetermined time since the proposal to execute the first lane change, and if it determines that the first operation has not been detected within the first predetermined time since the proposal to execute the first lane change, starts the first lane change. This makes it possible to avoid a situation in which an opportunity to overtake a leading vehicle is missed due to waiting for the driver's consent.

[0115] In the vehicle driving assistance method of this embodiment, after traveling in the second lane and overtaking the first preceding vehicle Vx, the driving assistance device 20 determines whether the second proposal condition is met, and if it determines that the second proposal condition is met, proposes to the driver to execute the second lane change, and if the proposal to execute the second lane change has continued for a second predetermined time since the proposal, determines whether a second operation by the driver to agree to the execution of the second lane change has been detected within the second predetermined time since the proposal, and starts the second lane change if it determines that the second operation has not been detected within the second predetermined time since the proposal to execute the second lane change. This makes it possible to avoid a situation in which an opportunity to overtake a preceding vehicle is missed due to waiting for the driver's consent.

[0116] Further, according to this embodiment, when overtaking assistance control is executed to overtake a first preceding vehicle Vx traveling ahead of the host vehicle V in a first lane in which the host vehicle V is traveling by traveling in a second lane adjacent to the first lane, a lane change proposal condition executed in the overtaking assistance control includes a first proposal condition for the host vehicle V to propose a first lane change from the first lane to the second lane, in which a predetermined first entry space A1 for the host vehicle V to enter the second lane is detected. and a second proposal condition that proposes a second lane change in which the host vehicle V returns from the second lane to the first lane after overtaking the first preceding vehicle Vx, the second proposal condition including a condition in which a predetermined second entry space A2 into which the host vehicle V enters is detected in the first lane, wherein a length D2 of the second entry space A2 in the traveling direction of the host vehicle V is longer than a length D1 of the first entry space A1 in the traveling direction. This makes it possible to prevent the host vehicle V from losing an opportunity to overtake a preceding vehicle.

[0117] 10...driving assistance system, 11...imaging device, 12...distance measuring device, 13...on-board sensor, 14...map database, 15...vehicle position detection device, 16...navigation device, 17...input device, 171...main switch, 172...resume / accelerate switch, 173...set / coast switch, 174...cancel switch, 175...distance adjustment switch, 176...lane change assistance switch, 18...actuator, 19...display device, 20...driving assistance device, 21...support Support unit, 22...setting unit, A1, A3...first approach space, A2, A4...second space, B1, B2...first distance threshold, C1, C2...second distance threshold, D1, D2, D3, D4, D5, D6...length, L1, L2...lane, P1, P2, P3, P4, P5, P6, Q1, Q2, Q3, Q4, Q5, Q6, Q7, Q8, Q9, Q10, Q11, Q12, Q13...position, T1, T2, T3, T4, T5...travel trajectory, V...host vehicle, Vx, Vy...preceding vehicle, X...destination, Z...speed difference

Claims

1. A vehicle driving assistance method executed by a driving assistance device of a host vehicle, wherein when the driving assistance device executes overtaking assistance control to overtake a first preceding vehicle traveling in front of the host vehicle in a first lane in which the host vehicle is traveling by traveling in a second lane adjacent to the first lane, the driving assistance device sets the following as proposal conditions for a lane change to be executed in the overtaking assistance control: a first proposal condition for the host vehicle to propose a first lane change from the first lane to the second lane, the first proposal condition including a condition that a predetermined first entry space for the host vehicle to enter is detected in the second lane; and a second proposal condition for the host vehicle to propose a second lane change from the second lane to the first lane after overtaking the first preceding vehicle, the second proposal condition including a condition that a predetermined second entry space for the host vehicle to enter is detected in the first lane, and wherein the length of the second entry space in the direction of travel of the host vehicle is longer than the length of the first entry space in the direction of travel.

2. The vehicle driving assistance method described in claim 1, wherein, when there is a second leading vehicle traveling in the second lane, the driving assistance device sets the length of the first entry space in the direction of travel to a first distance corresponding to the speed difference between the host vehicle and the second leading vehicle, sets the length of the second entry space in the direction of travel to a second distance corresponding to the speed difference between the host vehicle and the first leading vehicle, and sets the second distance so that the second distance is longer than the first distance when the speed difference between the host vehicle and the first leading vehicle and the speed difference between the host vehicle and the second leading vehicle are the same value.

3. A driving assistance method for a vehicle as described in claim 1 or 2, wherein the driving assistance device determines whether the first proposal condition is met, and if it determines that the first proposal condition is met, proposes to the driver of the vehicle that the first lane change be made, and when a first operation by the driver agreeing to make the first lane change is detected, starts the first lane change.

4. The driving assistance method for a vehicle described in claim 3, wherein the driving assistance device determines whether the second proposal condition is met after traveling in the second lane and overtaking the first preceding vehicle, and if it determines that the second proposal condition is met, proposes to the driver that the second lane change be performed, and when a second operation by the driver agreeing to the execution of the second lane change is detected, starts the second lane change.

5. The driving assistance device determines whether the first proposal condition is met, and if it determines that the first proposal condition is met, proposes to the driver of the vehicle that the vehicle make the first lane change, and if the first lane change has been proposed for a first predetermined time since the proposal, determines whether a first operation by the driver to accept the first lane change has been detected between the proposal of the first lane change and the first predetermined time having elapsed, and if it determines that the first operation has not been detected between the proposal of the first lane change and the first predetermined time having elapsed, starts the first lane change.

6. The driving assistance method for a vehicle described in claim 5, wherein the driving assistance device, after traveling in the second lane and overtaking the first preceding vehicle, determines whether the second proposal condition is met, and if it determines that the second proposal condition is met, proposes to the driver to execute the second lane change, and if the execution of the second lane change is continuously proposed for a second predetermined time after the execution of the second lane change is proposed, determines whether a second operation by the driver to agree to the execution of the second lane change is detected between the proposal of the execution of the second lane change and the elapse of the second predetermined time, and starts the second lane change when it determines that the second operation is not detected between the proposal of the execution of the second lane change and the elapse of the second predetermined time.

7. A vehicle driving assistance device comprising: a setting unit that sets, when performing overtaking assistance control to overtake a first preceding vehicle traveling in front of the host vehicle in a first lane in which the host vehicle is traveling, by traveling in a second lane adjacent to the first lane, as proposed conditions for a lane change to be performed in the overtaking assistance control: a first proposal condition to propose that the host vehicle make a first lane change from the first lane to the second lane, the first proposal condition including a condition that a predetermined first entry space for the host vehicle to enter into the second lane is detected; and a second proposal condition to propose that the host vehicle make a second lane change from the second lane back to the first lane after overtaking the first preceding vehicle, the second proposal condition including a condition that a predetermined second entry space for the host vehicle to enter into is detected in the first lane, wherein the length of the second entry space in the direction of travel of the host vehicle is longer than the length of the first entry space in the direction of travel.

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