Driving assistance method and driving assistance device

Abstract

In the present invention, when autonomous lane-change control is executed in response to a driver of a vehicle (V) operating a direction indicator lever of a direction indicator of the vehicle (V) to change lanes from a current lane in which a vehicle (V) is traveling to an adjacent lane in the direction corresponding to the operation performed by the driver, and it is determined that an adjacent lane does not exist in the direction corresponding to the operator performed by the driver, the driver is not notified that a lane change by the autonomous lane-change control cannot be executed.

Description

Driving assistance method and driving assistance device

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

[0002] An automated driving device is known that automatically changes lanes when a lane change command is issued and lane change permission conditions are met (see Patent Document 1). The automated driving device determines whether a road area designated as the target lane is a shoulder area, and if it determines that the road area designated as the target lane is a shoulder area, it prohibits the lane change and issues a message or alarm to that effect.

[0003] JP 2018-140750 A

[0004] For example, if a vehicle is traveling in the left lane of a two-lane road with left-hand traffic and this left lane branches off ahead into a main lane heading to the right of the vehicle's direction of travel and a branch lane heading to the left of the vehicle's direction of travel, when the vehicle is about to enter the branch lane, the driver operates the turn signal lever to flash the left turn signal just before the branch point, thereby indicating to other vehicles around that the vehicle is entering the branch lane. If the above-mentioned conventional technology is applied to this driving scenario, the operation of the turn signal lever will be recognized as an instruction to change lanes to the adjacent lane, and the driver will be notified that they cannot change lanes to the left of the vehicle's direction of travel because there is no lane on the left side of the vehicle's direction of travel.

[0005] However, in the above driving scenario, the driver is aware that he or she cannot change lanes to the left of the direction of travel before the branch point, and there is a problem in that when he or she indicates to other vehicles around that he or she is entering the branch line from the main line, the driver is notified of unnecessary information that he or she cannot change lanes to the adjacent lane.

[0006] The problem to be solved by the present invention is to provide a driving assistance method and a driving assistance device that can suppress notification of unnecessary information to the driver.

[0007] The present invention solves the above problem by not notifying the driver that a lane change cannot be performed using autonomous lane change control when autonomous lane change control is executed 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 response to the driver's operation of the vehicle's turn signal lever.

[0008] According to the present invention, it is possible to prevent unnecessary information from being notified to the driver.

[0009] 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 block diagram showing state transitions of the driving assistance device of FIG. 1. FIG. 5 is a plan view showing an example of a driving scene in which autonomous driving control is executed by the driving assistance system of FIG. 1. FIG. 6 is a flowchart showing an example of a processing procedure in the driving assistance system of FIG. 1.

[0010] 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.

[0011] [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 occupant through autonomous driving control. 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 occupant.

[0012] 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.

[0013] 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.

[0014] 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.

[0015] 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 travel of the vehicle, such as other automobiles (other vehicles), motorcycles, bicycles, pedestrians, etc. Note that the vehicle (host vehicle) is not particularly limited.

[0016] 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.

[0017] The on-board sensors 13 detect the vehicle's driving state. 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 vehicle's driving state. The driving assistance device 20 acquires the detection results of each sensor at predetermined time intervals (for example, every 0.1 to 1 millisecond).

[0018] 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 direction of travel 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 .

[0023] 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.

[0024] 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.

[0025] 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 vehicle.

[0026] The display device 19 provides information to the vehicle occupants. 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 occupants to input instructions to the driving assistance device 20, and a speaker as an output device.

[0027] 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 operation by the driver.

[0028] 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.

[0029] [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 a determination unit 21 and an assistance unit 22 extracted as functional blocks for performing autonomous driving control.

[0030] The determination 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 determination unit 21 makes various determinations based on the recognized current state of the driving environment so that the assistance unit 22 can execute autonomous driving control.

[0031] The support unit 22 drives the vehicle under autonomous driving control based on the determination result of the determination unit 21, and provides necessary information to the vehicle occupants. For example, the support unit 22 generates a driving trajectory for the vehicle to drive along a driving route based on image information acquired by the imaging device 11 and position information of an object acquired by the distance measuring device 12, and generates a control signal for operating the actuator 18 so that the vehicle drives along the driving trajectory. The support unit 22 also generates notification information for notifying the vehicle occupants about the autonomous driving control, and outputs the notification information to the display device 19.

[0032] The assistance unit 22 performs autonomous driving control, which includes autonomous speed control for autonomously controlling the vehicle's driving speed and autonomous steering control for autonomously controlling the vehicle's steering operation. 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 assistance unit 22 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 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 assistance unit 22 performs constant-speed driving at the driving speed set by the driver.

[0033] 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.

[0034] 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.

[0035] 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 22 executes lane keeping control and autonomous lane change control as the autonomous steering control.

[0036] 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 operations.

[0037] 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 made to flash, and when a preset lane change initiation condition is 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).

[0038] 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).

[0039] The determination 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 keeping 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 speed being a predetermined speed (e.g., 50 to 80 km / h) or more, there being a lane in the direction of the lane change, there being space in the lane to which the lane is to be changed that allows for a lane change, the type of lane boundary line being a type that allows for a lane change, the radius of curvature of the road on which the vehicle is traveling being a predetermined radius (e.g., 200 to 300 m) or more (i.e., the road is not a sharp curve), and the driver operating the turn signal lever within one second.

[0040] 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.

[0041] Furthermore, in the autonomous lane change control, the turn signal may be flashed when the driver operates a switch other than the turn signal lever (hereinafter also referred to as a lane change switch), and the LCP may be started when a preset lane change start condition is satisfied. In other words, in this embodiment, an instruction to execute autonomous lane change control is output to the driving assistance device 20 in response to the driver's operation of the turn signal lever or lane change switch.

[0042] The lane change switch is, for example, a button switch attached to the steering wheel, and specifically, the lane change assist switch 176 shown in Fig. 2. When the driving assist device 20 confirms with the driver that the driver wants to start a lane change and the lane change assist switch 176 is operated, an instruction to approve the start of the lane change is output to the driving assist device 20 (determination unit 21), and the determination unit 21 determines whether or not a lane change start condition is met.

[0043] Hereinafter, an operation of the turn signal lever will be referred to as a first operation, and an operation of the lane change switch will be referred to as a second operation. The direction corresponding to an operation performed by the driver will also be referred to as a corresponding direction. For example, if the driver operates the turn signal lever in a direction (counterclockwise) corresponding to the left turn signal, the corresponding direction will be the left direction of travel. Furthermore, the direction corresponding to the first operation performed by the driver will also be referred to as a first direction, and the direction corresponding to the second operation performed by the driver will also be referred to as a second direction.

[0044] The autonomous lane change control may be started by an operation by the driver, or may be started when the driving assistance device 20 proposes to the driver that the autonomous lane change control be executed and the driver accepts the proposal. The consent to the execution of the autonomous lane change control is input, for example, by using a turn signal lever.

[0045] 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, and lane L1 branches into lane L1, which is a main lane, and lane L3, which is a branch lane, at branch point Z. On the road shown in Fig. 3, a vehicle travels from left to right in the drawing.

[0046] In the driving scene shown in Fig. 3, vehicle V is traveling at position P1 on lane L1, heading toward destination X1 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 vehicle V travels from position P1 to position P2 along driving trajectory T1, at position P2, the driver of vehicle V operates the turn signal lever of vehicle V to flash the right turn signal of vehicle V.

[0047] In this case, the determination unit 21 detects a space in lane L2 (adjacent lane) in the corresponding direction to lane L1 (the vehicle's own 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 Figure 3, there are no other vehicles traveling in lane L2, so a space in lane L2 for vehicle V to enter is detected. Therefore, the lane change start condition is met if the autonomous driving control mode is the lane keeping mode of the hands-on mode, hands-on determination is in progress, the vehicle's traveling speed is equal to or greater than a predetermined speed, the type of lane boundary line between 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.

[0048] When the lane change initiation condition is satisfied, the assistance unit 22 initiates the LCP by autonomous lane change control. This LCP includes a lateral movement of the vehicle V into an adjacent lane (i.e., lane L2) and a lane change maneuver (hereinafter referred to as LCM) in which the vehicle V actually crosses the lane boundary line and moves into lane L2. Specifically, the assistance unit 22 generates a travel trajectory T2 shown in FIG. 3 and generates a control signal to operate the actuator 18 so that the vehicle V travels along the travel trajectory T2 from position P2 to position P6.

[0049] The assistance unit 22 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 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 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 22 notifies the driver using the display device 19 that a lane change is being performed.

[0050] The LCP based on the autonomous lane change control described above is executed in the same way for both the first operation and the second operation. However, in the case of the second operation, 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.

[0051] 4 is a block diagram showing state transitions of the functions established in the driving assistance device 20. The system shown in FIG.

[0052] First, when the main switch is turned on from the system-off state shown in Fig. 4, 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.

[0053] From the standby state, the autonomous speed control is started 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 vehicle V by simply operating the steering wheel without stepping on the accelerator or brake.

[0054] 4 is satisfied during autonomous speed control, the system transitions to lane keeping mode of the autonomous steering control / hands-on mode. This condition (1) includes the following: the driver is holding the steering wheel while lane boundaries on both sides of the vehicle V are detected; the vehicle V is traveling near the center of the lane; the turn signal is not activated; the wipers are not operating at high speed (HI); etc.

[0055] 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.

[0056] 4 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 vehicle being detected by the 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 vehicle.

[0057] Conversely, if condition (3) in Fig. 4 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 vehicle V is traveling on a road other than a motorway, when the traveling speed of the vehicle V exceeds the speed limit, when the driver is holding the steering wheel and depressing the accelerator pedal, etc.

[0058] When the lane-keeping mode of the autonomous steering control / hands-off mode is being executed, if the condition (4) in Fig. 4 is met, 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.

[0059] Furthermore, if the condition (5) in Fig. 4 is met 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 vehicle transitions to a standby state. This condition (5) can be met when the driver operates the brakes or when the driver operates the cancel switch 174 in Fig. 2.

[0060] If condition (6) in Fig. 4 is met while autonomous steering control / hands-on mode is being executed, autonomous steering control is stopped and transition is made to autonomous speed control. This condition (6) can be met when the driver operates the steering wheel or turn signal lever, or when lane boundary lines on at least one side of the vehicle V are not detected.

[0061] Furthermore, if the condition (7) in Fig. 4 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.

[0062] If condition (8) in Fig. 4 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.

[0063] 4 is satisfied while the lane keep mode of the autonomous steering control hands-off mode is being executed, the mode 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.

[0064] If the condition (10) in Fig. 4 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.

[0065] 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.

[0066] In principle, the support unit 22 notifies the occupant of whether or not a lane change can be performed by the autonomous lane change control as notification information related to the autonomous driving control. In the driving scene shown in Figure 2, if a space for the vehicle V to enter the lane L2 is not detected, the support unit 22 notifies the occupant using the display device 19 that a lane change cannot be performed. However, this basic notification may provide the occupant with unnecessary information.

[0067] Figure 5 is a plan view showing an example of a driving scene in which autonomous driving control is executed by the driving assistance system 10 of Figure 1. The driving scene shown in Figure 5 is similar to the driving scene shown in Figure 3, except that the vehicle V is heading toward destination X2 located ahead on lane L3. Because lane L3, which is a branch lane, is not adjacent to lane L1, the vehicle V enters lane L3 by manual driving by the driver or autonomous driving control other than autonomous lane change control.

[0068] For example, when using autonomous driving control to head toward destination X2 shown in FIG. 5 , if vehicle V wishes to promptly alert surrounding vehicles that it is entering lane L3, which is a branch lane, with the main switch of the autonomous driving control ON and autonomous lane change control executable, after vehicle V has autonomously driven from position P1 to position P2 along driving trajectory T1, the driver of vehicle V operates the turn signal lever to flash the turn signal at position P2. The driver of vehicle V flashes the turn signal on the left side of vehicle V to alert surrounding vehicles that vehicle V is entering lane L3, which is a branch lane. This steering wheel operation transitions autonomous driving control to a standby state.

[0069] The driver of vehicle V then drives vehicle V along travel path T3 to position P7 with the left turn signal flashing, and at position P7 turns the steering wheel to the left (counterclockwise) in the direction of travel to change the direction of travel of vehicle V. While turning the steering wheel to the left in the direction of travel, the driver causes vehicle V to enter lane L3 at position P8. Then, after passing position P8, the driver turns the steering wheel to the right (clockwise) in the direction of travel and again operates the turn signal lever to turn off the turn signal. The driver returns the steering wheel to the neutral position at position P9, completing vehicle V's entry into lane L3 (branch lane).

[0070] In the driving scene shown in Fig. 5, autonomous lane change control is executable until the steering wheel is turned at position P7, and therefore, when the driver operates the turn signal lever at position P2, an instruction to execute autonomous lane change control to change lanes to the adjacent lane on the left side of the traveling direction is output to the driving assistance device 20. Therefore, in the driving scene shown in Fig. 5, the driver of vehicle V is notified by the assistance unit 22 that a lane change to the left cannot be executed between positions P2 and P7.

[0071] This notification is unnecessary information for the driver and makes the driver feel uncomfortable (or uncomfortable) because the driver operated the turn signal lever to indicate to surrounding vehicles that vehicle V is entering lane L3, and the driver is naturally aware that changing lanes to the left is not possible at position P2.

[0072] 5, when vehicle V is traveling under autonomous driving control toward destination X1 (not shown) located ahead on lane L2, a similar problem occurs when vehicle V enters lane L3, which is a branch lane, from vehicle L1 to travel to destination X2, which is located ahead on lane L3 and is different from destination X1, in order to avoid traffic congestion ahead. That is, the driver of vehicle V operates the turn signal lever at position P2 shown in FIG. 5 to flash the left turn signal light of vehicle V and alert surrounding vehicles that vehicle V is entering lane L3, which is a branch lane. However, in response to this operation, the assistance unit 22 notifies unnecessary information that a lane change to the left cannot be executed.

[0073] Therefore, in order to prevent unnecessary information from being notified to the driver, in the present invention, when there is no adjacent lane in the direction corresponding to the first operation performed by the driver, the driver is exceptionally not notified that a lane change cannot be performed by autonomous lane change control. The processing in the driving assistance device 20 will be specifically described below.

[0074] First, the determination unit 21 determines whether autonomous lane change control is executable based on the recognized driving environment around the vehicle V. If it is determined that autonomous lane change control is not executable, the driving assistance device 20 terminates the autonomous lane change control and transitions to autonomous speed control or terminates autonomous driving control. On the other hand, if it is determined that autonomous lane change control is executable, the determination unit 21 determines whether a first operation of the turn signal lever has been detected.

[0075] If it is determined that the first operation of the turn signal lever is not detected, the determination unit 21 repeats the detection process, for example, until the first operation is detected. On the other hand, if it is determined that the first operation of the turn signal lever is detected, such as when a signal output to the driving assistance device 20 is detected during operation of the turn signal lever, the determination unit 21 determines whether or not an adjacent lane exists in the first direction corresponding to the first operation.

[0076] The determination unit 21 determines whether or not an adjacent lane exists in the first direction based on the image information output from the imaging device 11, the position information of the object output from the distance measuring device 12, the high-precision map information output from the map database 14, etc. For example, the determination unit 21 obtains information about the lanes of the road on which the vehicle V is traveling from the high-precision map information, recognizes which lane of the road the vehicle V is traveling in based on the image information and the position information of the object, and determines whether or not an adjacent lane exists in the first direction of the lane on which the vehicle V is traveling based on the obtained information about the lane.

[0077] If it is determined that an adjacent lane exists in the first direction, the determination unit 21 determines whether the vehicle V can change lanes to the adjacent lane in the first direction by autonomous lane change control. That is, the determination unit 21 determines whether a space for the vehicle V to enter the adjacent lane in the first direction is detected based on the recognized driving environment.

[0078] If it is determined that the vehicle V can change lanes to the adjacent lane in the first direction, the assistance unit 22 executes a lane change using autonomous lane change control executed in response to the first operation (hereinafter also referred to as first autonomous lane change control), and causes the vehicle V to travel from its own lane to the adjacent lane in the first direction. On the other hand, if it is determined that the vehicle V cannot change lanes to the adjacent lane in the first direction, the assistance unit 22 notifies the driver using the display device 19 that a lane change using the first autonomous lane change control cannot be executed.

[0079] On the other hand, if it is determined that there is no adjacent lane in the first direction, the assistance unit 22 does not notify the driver that a lane change cannot be performed using the first autonomous lane change control. In this case, the assistance unit 22 may cancel the first autonomous lane change control or may notify the driver to perform manual driving.

[0080] As an example, in the driving scene shown in Fig. 5 , when the turn signal lever is operated to flash the turn signal at position P2, the determination unit 21 determines whether or not an adjacent lane exists to the left of the traveling direction of the vehicle V (first direction). Because there is no adjacent lane to the left of lane L1 shown in Fig. 5 , the determination unit 21 outputs a determination result to the assistance unit 22 that there is no adjacent lane to the left of the traveling direction of the vehicle V. In response to the input determination result, the assistance unit 22 terminates the autonomous lane change control without notifying the driver that a lane change cannot be performed using the first autonomous lane change control.

[0081] When the determination unit 21 determines that autonomous lane change control is executable based on the recognized driving environment around the vehicle V, and when an instruction to execute autonomous lane change control is input, the determination unit 21 may determine whether the instruction is an execution instruction based on the first operation or the second operation. If it is determined that the execution instruction is based on the first operation, the assistance unit 22 executes the above-described processing. On the other hand, if it is determined that the execution instruction is based on the second operation, the determination unit 21 determines whether a lane change to an adjacent lane in a second direction is possible by autonomous lane change control executed in response to the second operation (hereinafter also referred to as second autonomous lane change control).

[0082] If it is determined that a lane change to an adjacent lane in the second direction is possible through autonomous lane change control, the assistance unit 22 executes a lane change through second autonomous lane change control and causes the vehicle V to travel from the own lane to the adjacent lane in the second direction. On the other hand, if it is determined that a lane change to an adjacent lane in the second direction is not possible through autonomous lane change control, the assistance unit 22 notifies the driver that a lane change through the second autonomous lane change control is not possible.

[0083] In the second autonomous lane change control, an instruction to change lanes in a direction where there is no adjacent lane is not input. The second autonomous lane change control is executed when the driver accepts the execution of the second autonomous lane change control by operating the lane change switch in response to a lane change suggestion from the driving assistance system 10, and the driving assistance system 10 does not suggest to the driver that they change lanes in a direction where there is no adjacent lane. In other words, the driving assistance system 10 recognizes that there is an adjacent lane in the direction of the lane change at the stage of suggesting a lane change to the driver.

[0084] [Processing in Driving Assistance System] The procedure for processing information by the driving assistance device 20 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of the processing procedure executed in the driving assistance system 10, and the processing described below is executed at predetermined time intervals (for example, every 0.1 to 1 millisecond) by a processor (CPU) included in the driving assistance device 20.

[0085] 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 conditions for executing autonomous lane change control are met from the driving environment recognized by the function of the determination unit 21. If it is determined that autonomous lane change control is not executable (step S1: No), the autonomous lane change control is terminated. On the other hand, if it is determined that autonomous lane change control is executable (step S1: Yes), the process proceeds to step S2.

[0086] In step S2, the driving assistance device 20 determines whether or not operation of the turn signal lever by the driver has been detected. That is, the driving assistance device 20 detects a signal output to the driving assistance device 20 when the turn signal lever is operated, using the function of the determination unit 21. If it is determined that operation of the turn signal lever by the driver has not been detected (step S2: No), the autonomous lane change control is terminated. On the other hand, if it is determined that operation of the turn signal lever by the driver has been detected (step S2: Yes), the process proceeds to step S3.

[0087] In step S3, the driving assistance device 20 determines whether or not an adjacent lane exists in the direction corresponding to the operation of the turn signal lever, based on the driving environment recognized by the function of the determination unit 21. If it is determined that an adjacent lane exists in the direction corresponding to the operation of the turn signal lever (step S3: Yes), the process proceeds to step S4.

[0088] In step S4, the driving assistance device 20 determines whether or not a lane change to an adjacent lane in a direction (corresponding direction) corresponding to the operation of the turn signal lever is possible. If it is determined that a lane change to an adjacent lane in the corresponding direction is possible (step S4: Yes), the driving assistance device 20 proceeds to step S5, where a lane change is executed by autonomous lane change control. On the other hand, if it is determined that a lane change to an adjacent lane in the corresponding direction is not possible (step S4: No), the driving assistance device 20 proceeds to step S6, where the driver is notified that a lane change by autonomous lane change control cannot be executed.

[0089] On the other hand, if it is determined that there is no adjacent lane in the direction corresponding to the operation of the turn signal lever (step S3: No), the process proceeds to step S7. In step S7, the driving assistance device 20, using the function of the assistance unit 22, does not notify the driver that a lane change cannot be performed using autonomous lane change control, and in the subsequent step S8, stops the autonomous lane change control and notifies the driver to perform manual driving.

[0090] [Embodiment of the Present Invention] According to the present embodiment, there is provided a driving assistance method executed by a driving assistance device 20 of a vehicle V, in which, in response to a first operation of a turn signal lever of a turn signal of the vehicle V performed by a driver of the vehicle V, first autonomous lane change control is executed to change the lane from the lane in which the vehicle V is traveling to an adjacent lane in a first direction corresponding to the first operation, and if the driving assistance device 20 determines that there is no adjacent lane in the first direction corresponding to the first operation performed by the driver, the driving assistance device 20 does not notify the driver that the lane change cannot be performed by the first autonomous lane change control. This makes it possible to prevent unnecessary information from being notified to the driver.

[0091] In the driving assistance method of this embodiment, when the first autonomous lane change control is executed in response to the first operation, if the adjacent lane does not exist in the first direction corresponding to the first operation performed by the driver, the driving assistance device 20 cancels the first autonomous lane change control and notifies the driver to perform manual driving. This allows autonomous driving control to be executed in line with the intention of the driver who performed the first operation.

[0092] In the driving assistance method of this embodiment, when the first autonomous lane change control is executed in response to the first operation, if the adjacent lane is present in the first direction corresponding to the first operation performed by the driver, the control device 20 determines whether the lane change can be executed by the first autonomous lane change control, and if it determines that the lane change cannot be executed by the first autonomous lane change control, notifies the driver that the lane change cannot be executed by the first autonomous lane change control. This makes it possible to notify information in line with the driver's intention to execute a lane change by autonomous lane change control.

[0093] In the driving assistance method of the present embodiment, when second autonomous lane change control is executed to change the lane from the own lane to the adjacent lane in a second direction corresponding to a second operation performed by the driver on a switch other than the turn signal lever, the driving assistance device 20 determines whether the lane change can be executed by the second autonomous lane change control, and when it determines that the lane change cannot be executed by the second autonomous lane change control, notifies the driver that the lane change cannot be executed by the second autonomous lane change control. This makes it possible to notify information in line with the driver's intention to execute a lane change by autonomous lane change control.

[0094] Furthermore, according to the present embodiment, when first autonomous lane change control is executed in response to a first operation of a turn signal lever of a turn signal of the vehicle V performed by a driver of the vehicle V to change lanes from the lane in which the vehicle V is traveling to an adjacent lane in a first direction corresponding to the first operation, if it is determined that there is no adjacent lane in the first direction corresponding to the first operation performed by the driver, the driving assistance device 20 is provided, which includes an assistance unit 22 that does not notify the driver that the lane change cannot be performed by the first autonomous lane change control. This makes it possible to prevent unnecessary information from being notified to the driver.

[0095] 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...determination unit, 22...assistance unit, L1, L2, L3...lane, P1, P2, P3, P4, P5, P6, P7, P8, P9...position, T1, T2, T3...driving trajectory, V...vehicle, X1, X2...destination, Z...branch point

Claims

1. A driving assistance method executed by a driving assistance device of a vehicle, wherein, in response to a first operation of a turn signal lever of a turn signal indicator of the vehicle performed by a driver of the vehicle, the driving assistance device executes first autonomous lane change control to change lanes from the lane in which the vehicle is traveling to an adjacent lane in a first direction corresponding to the first operation, and if it determines that the adjacent lane does not exist in the first direction corresponding to the first operation performed by the driver, the driving assistance device does not notify the driver that the lane change cannot be performed by the first autonomous lane change control.

2. The driving assistance method described in claim 1, wherein, when the first autonomous lane change control is executed in response to the first operation, if the adjacent lane does not exist in the first direction corresponding to the first operation performed by the driver, the driving assistance device cancels the first autonomous lane change control and notifies the driver to perform manual driving.

3. The driving assistance method described in claim 1 or 2, wherein, when the first autonomous lane change control is executed in response to the first operation, if the adjacent lane is present in the first direction corresponding to the first operation performed by the driver, the driving assistance device determines whether the lane change can be executed by the first autonomous lane change control, and if it determines that the lane change cannot be executed by the first autonomous lane change control, notifies the driver that the lane change cannot be executed by the first autonomous lane change control.

4. The driving assistance method described in any one of claims 1 to 3, wherein, when second autonomous lane change control is executed to change lanes from the own lane to the adjacent lane in a second direction corresponding to a second operation performed by the driver on a switch different from the turn signal lever, the driving assistance device determines whether the lane change can be executed by the second autonomous lane change control, and when it determines that the lane change cannot be executed by the second autonomous lane change control, notifies the driver that the lane change cannot be executed by the second autonomous lane change control.

5. A driving assistance device comprising: an assistance unit that, when first autonomous lane change control is executed to change lanes from the lane in which the vehicle is traveling to an adjacent lane in a first direction corresponding to a first operation performed by the driver of the vehicle on a turn signal lever of the vehicle's turn indicator, does not notify the driver that the lane change cannot be performed by the first autonomous lane change control if it is determined that there is no adjacent lane in the first direction corresponding to the first operation performed by the driver.

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