Driving assistance method and driving assistance device

Abstract

According to the present invention, a driving assistance method for suggesting a lane change and executing the lane change by autonomous travel control on the basis of an approval action by a passenger involves making a controller execute processing (S2, S4, S6) that begins suggestion of a lane change to a first adjacent lane when a preceding vehicle that is traveling at a relatively slower speed than a self vehicle has been detected and it has been determined that a first interval that is the interval between the self vehicle and another vehicle that is in the first adjacent lane is at or above a first threshold value, processing (S34) that continues suggestion of the lane change to the first adjacent lane on the condition that the first interval is at or above a second threshold value that is smaller than the first threshold value, and processing (S34) that operates a directional indicator on the first adjacent lane side when a passenger has performed an approval action while suggestion of the lane change to the first adjacent lane is being continued.

Description

[Technical Field]

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

[0002] The following Patent Document 1 describes a driving assistance control device that determines whether there is an opportunity to change lanes, and if it is determined that a lane change is possible, presents the driver with a suggestion to change lanes using autonomous driving. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-71514 Summary of the Invention [Problem to be solved by the invention]

[0004] If there is insufficient space in the adjacent lane after an autonomous driving control lane change to an adjacent lane is proposed, the lane change proposal may be canceled before it is accepted. The present invention aims to reduce the frequency of cancellation of a lane change proposal after proposing a lane change to an adjacent lane using autonomous driving control. [Means for solving the problem]

[0005] According to one aspect of the present invention, there is provided a driving assistance method for proposing a lane change and executing a lane change using autonomous driving control based on an occupant's approval. The driving assistance method causes a controller to perform the following steps: when a preceding vehicle traveling at a speed relatively slower than the vehicle speed of the host vehicle is detected, if it is determined that a first distance, which is a distance between the host vehicle and another vehicle in a first adjacent lane, is equal to or greater than a first threshold; when the first distance is equal to or greater than a second threshold that is smaller than the first threshold, to start proposing a lane change to the first adjacent lane; when the occupant approves the lane change proposal to the first adjacent lane, to activate a turn signal for the first adjacent lane. [Effects of the Invention]

[0006] According to the present invention, it is possible to reduce the frequency of cancellation of a lane change proposal after the lane change proposal to an adjacent lane is made by autonomous driving control. The objects and advantages of the invention will be realized and attained by means of the elements and combinations set forth in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram illustrating an example of a schematic configuration of a vehicle equipped with a driving assistance device according to an embodiment. [Figure 2] FIG. 2 is a diagram illustrating a part of the input device of FIG. [Figure 3] FIG. 2 is a block diagram illustrating an example of a functional configuration of a controller for performing overtaking assistance control and route driving assistance control. [Figure 4] 10 is a flowchart illustrating an example of a process when an overtaking proposal is made. [Figure 5] 10 is a flowchart illustrating an example of a process when a lane return proposal is made. [Figure 6] 10 is a flowchart illustrating an example of a process for proposing a route. [Figure 7]10 is a flowchart illustrating an example of processing when a lane change is executed in a case where an overtaking suggestion is adopted. [Figure 8] 10 is a flowchart illustrating an example of processing when a lane change is executed in a case where a lane return proposal is adopted. [Figure 9] 10 is a flowchart illustrating an example of a process for executing a lane change when a proposed route is adopted. DETAILED DESCRIPTION OF THE INVENTION

[0008] (composition) 1 is a diagram showing an example of a schematic configuration of a vehicle equipped with a driving assistance device according to an embodiment. The driving assistance device 10 equipped in the vehicle 1 includes a sensor 11, a positioning device 12, a map database (map DB) 13, on-board equipment 14, a navigation system 15, a display device 16, an audio output device 17, an input device 18, a vehicle behavior control device 19, and a controller 20. These devices are connected to each other via, for example, a CAN (Controller Area Network) or other on-board LAN for transmitting and receiving information to and from each other.

[0009] The sensor 11 detects the traveling state of the host vehicle 1. For example, the sensor 11 includes a camera that captures images in front of, behind, and on the sides of the host vehicle 1. The sensor 11 also includes a radar that detects obstacles in front of, behind, and on the sides of the host vehicle 1. The sensor 11 also includes a vehicle speed sensor that detects the vehicle speed of the host vehicle 1. The positioning device 12 includes a GPS unit, a gyro sensor, and the like. The positioning device 12 periodically acquires position information of the host vehicle 1 using the GPS unit. The positioning device 12 also detects the current position of the host vehicle 1 based on the position information of the host vehicle 1, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor.

[0010] The map database 13 is a memory that stores three-dimensional high-precision map information including position information of various facilities and specific points, and is accessible from the controller 20. The three-dimensional high-precision map information is map information that is associated as three-dimensional information with detailed and high-precision position information such as curved roads and the size of the curves (for example, curvature or curvature radius), road junctions, branching points, toll booths, and positions where the number of lanes decreases, along with the map information.

[0011] The in-vehicle devices 14 are various devices mounted on the vehicle 1 and are operated by the operation of a passenger (e.g., the driver). Examples of such in-vehicle devices include a steering wheel, an accelerator pedal, a brake pedal, a turn signal, wipers, lights, a horn, and other specific switches. The navigation system 15 acquires current position information of the vehicle 1 from the positioning device 12, and displays the position of the vehicle 1 on a display or the like, superimposing it on map information for navigation. Furthermore, when a destination is set, the navigation system 15 sets a route from the current position of the vehicle 1 to the destination as a target driving route, and executes navigation control to guide the occupant along the target driving route. In this navigation control, the navigation system 15 displays the target driving route on a map on the display and notifies the occupant of the target driving route by voice or the like. The target driving route set by the navigation system 15 is also used in route driving assistance control by the controller 20. The route driving assistance control is control to autonomously drive the vehicle 1 to the destination along the set target driving route.

[0012] The display device 16 includes various displays provided at positions visible to the occupants. The display device 16 notifies the occupants of various pieces of presentation information under the control of the controller 20. The audio output device 17 is a device that outputs auditory information such as a speaker provided in the navigation system 15, a speaker of an audio device, a buzzer, etc. The audio output device 17 notifies the occupants of various pieces of presentation information under the control of the controller 20. The input device 18 is, for example, a button switch that can be manually operated by the occupant to input information, a touch panel arranged on the display screen, or a microphone that can be used for voice input by the occupant. By operating the input device 18, the occupant can input setting information for the information presented by the display device 16 and the audio output device 17.

[0013] FIG. 2 is a diagram illustrating a portion of the input device 18 according to this embodiment. The input device 18 may be, for example, a group of button switches arranged on the spokes of the steering wheel. The input device 18 is used to turn autonomous driving control by the controller 20 on / off. The input device 18 includes a main switch 181, a resume / accelerate switch 182, a set / coast switch 183, a cancel switch 184, a distance adjustment switch 185, and a lane change assist switch 186. The main switch 181 is a switch that turns autonomous driving control by the controller 20 on / off. The resume / accelerate switch 182 is a switch that sets the autonomous driving control to resume at the set speed before turning off the autonomous driving control after turning it off, or that increases the set speed. The set / coast switch 183 is a switch that starts autonomous driving control. To start autonomous driving control, the autonomous driving control is turned on by the main switch 181, and then the set / coast switch 183 is pressed. The set / coast switch 183 is a switch for lowering the set speed. The cancel switch 184 is a switch for canceling autonomous driving control. The distance adjustment switch 185 is a switch for setting the distance from the vehicle ahead. The lane change assistance switch 186 is a switch for instructing (approving) the start of a lane change when the controller 20 has confirmed with the occupant that the lane change should be started. In addition to the button switches shown in FIG. 2, the turn signal lever of a turn signal or other switches of the in-vehicle equipment 14 can also be used as the input device 18.

[0014] The vehicle behavior control device 19 controls the vehicle behavior of the host vehicle 1. For example, when the host vehicle 1 travels at a constant speed at a set speed under autonomous travel control, the vehicle behavior control device 19 controls the operation of the drive mechanism and the brakes to achieve acceleration / deceleration and travel speed so that the host vehicle 1 reaches the set speed. The vehicle behavior control device 19 also controls the operation of the drive mechanism and the brakes in the same way when the host vehicle 1 travels following a preceding vehicle under autonomous travel control. Note that the control of the operation of the drive mechanism includes the operation of the internal combustion engine in an engine vehicle and the operation of the traction motor in an electric vehicle. In addition, in a hybrid vehicle, it includes the torque distribution between the internal combustion engine and the traction motor. In addition, when the vehicle behavior control device 19 performs autonomous steering control, which will be described later, through autonomous driving control, it controls the operation of the steering actuator in addition to controlling the operation of the drive mechanism and brakes to perform steering control of the vehicle 1.

[0015] The controller 20 is one or more electronic control units (ECUs) for controlling the traveling of the host vehicle 1, and includes a processor 21 and peripheral components such as a storage device 22. The processor 21 may be, for example, a CPU or an MPU. The storage device 22 may include a semiconductor storage device, a magnetic storage device, an optical storage device, or the like. The storage device 22 may include memories such as a register, a cache memory, and a ROM and RAM used as a main storage device. The functions of the controller 20 described below are realized, for example, by the processor 21 executing a computer program stored in the storage device 22.

[0016] The controller 20 realizes a driving information acquisition function that acquires information about the driving state of the host vehicle 1, and executes autonomous driving control that autonomously controls the driving speed and / or steering of the host vehicle 1. The driving information acquisition function is a function that acquires driving information about the driving state of the host vehicle 1. For example, the controller 20 acquires, as driving information, image information of the outside of the vehicle captured by the camera of the sensor 11, detection results by radar, and vehicle speed information from a vehicle speed sensor.

[0017] Furthermore, the controller 20 acquires, as the driving information, current position information of the vehicle 1 from the positioning device 12. The controller 20 acquires, as the driving information, a set destination and a target driving route to the destination from the navigation system 15. The controller 20 acquires, as the driving information, position information such as curved roads and the magnitude of the curves (for example, curvature or curvature radius), merging points, branching points, toll gates, and positions where the number of lanes decreases, as well as map information such as lane information, from the map database 13. The controller 20 acquires, as the driving information, operation information of the in-vehicle device 14 by the occupant from the in-vehicle device 14.

[0018] In the autonomous driving control, the controller 20 autonomously controls the driving of the host vehicle 1 without relying on the operation of the occupant. The autonomous driving control includes autonomous speed control that autonomously controls the driving speed of the host vehicle 1 and autonomous steering control that autonomously controls the steering of the host vehicle 1. In autonomous speed control, when a preceding vehicle is detected, the controller 20 follows the preceding vehicle while performing inter-vehicle control to maintain a distance according to the vehicle speed, with the upper limit set by the occupant's vehicle speed or speed limit. On the other hand, when a preceding vehicle is not detected, the controller 20 performs constant speed driving at the vehicle speed or speed limit set by the occupant. The former is also called inter-vehicle control, and the latter is called constant speed control.

[0019] Constant speed control is performed when the forward radar of the sensor 11 or the like detects that there is no preceding vehicle ahead in the lane in which the host vehicle 1 is traveling. In constant speed control, the vehicle behavior control device 19 controls the operation of drive mechanisms such as the engine and brakes while feeding back vehicle speed data from a vehicle speed sensor so as to maintain a set traveling speed. Vehicle distance control is performed when the forward radar of the sensor 11 or the like detects that there is a preceding vehicle ahead in the lane in which the host vehicle 1 is traveling. In vehicle distance control, the vehicle behavior control device 19 controls the operation of drive mechanisms such as the engine and brakes while feeding back vehicle distance data detected by the forward radar so as to maintain a set inter-vehicle distance, with a set traveling speed as the upper limit.

[0020] In the autonomous steering control, the controller 20 controls the operation of the steering actuator based on the driving information acquired by the driving information acquisition function, thereby performing steering control of the host vehicle 1. The autonomous steering control includes lane keeping control, lane change assist control, overtaking assist control, and route driving assist control. In lane keeping control, the controller 20 controls the steering actuator so that the vehicle travels near the center of the lane, for example, to assist the driver in steering the vehicle.

[0021] In the lane change assist control, the controller 20 turns on the turn signal when the driver operates the turn signal lever, and determines whether predetermined lane change start conditions are met based on various driving information acquired by the driving information acquisition function. If the lane change start conditions are met, the controller 20 starts a lane change operation. In a lane change operation, the controller 20 performs a lane change maneuver to move the vehicle 1 laterally to an adjacent lane to which the vehicle is to change lanes (hereinafter, sometimes referred to as a "destination lane"). While the controller 20 is performing a lane change maneuver, the controller 20 displays information indicating that the lane change is being performed automatically on the display device 16. When the lane change maneuver is completed, the controller 20 turns off the turn signal and starts executing a lane keeping function in the lane after the lane change.

[0022] In overtaking assist control, when the controller 20 detects a preceding vehicle slower than the host vehicle 1 ahead in the lane in which the host vehicle 1 is traveling and when predetermined overtaking suggestion conditions are met, the controller 20 suggests to the occupant that they change lanes using autonomous driving control to overtake the preceding vehicle. Hereinafter, a proposal to change lanes to overtake the preceding vehicle may be referred to as an "overtaking proposal." When the occupant approves the overtaking suggestion by operating the lane change assist switch 186 of the input device 18 and predetermined overtaking execution conditions are met, the controller 20 executes an automated lane change. In the automated lane change, the controller 20 executes a lane change operation so that the host vehicle 1 moves into the destination lane.

[0023] Furthermore, when predetermined lane return suggestion conditions are met after the host vehicle 1 has overtaken the preceding vehicle, the controller 20 suggests to the occupant via the display device 16 that the host vehicle 1 perform a lane change using autonomous driving control and return to the original lane before the overtaking. Hereinafter, the suggestion to return to the original lane after overtaking the preceding vehicle may be referred to as a "lane return suggestion." If the occupant approves the lane return suggestion by operating the lane change assist switch 186 of the input device 18, and predetermined lane return execution conditions are met, the controller 20 executes an automated lane change. In the automated lane change, the controller 20 executes a lane change operation so that the host vehicle 1 moves to the original lane. Hereinafter, the function of the controller 20 that executes overtaking assist control may be referred to as an "overtaking assist function."

[0024] In the route driving assistance control, when predetermined route driving execution conditions are met before a driving direction change point such as a branch point, merging point, exit, or toll gate on the target driving route set by the navigation system 15, the controller 20 suggests to the occupant that a lane change be performed using autonomous driving control to drive the vehicle along the target driving route. Hereinafter, the suggestion of a lane change to drive the vehicle along the target driving route may be referred to as a "route driving proposal." When the occupant accepts the route driving proposal by operating the lane change assistance switch 186 of the input device 18 and predetermined route driving execution conditions are met, the controller 20 executes an automated lane change. In the automated lane change, the controller 20 executes a lane change operation so that the host vehicle 1 moves into the destination lane. Hereinafter, the function of the controller 20 that executes the route driving assistance control may be referred to as a "route driving assistance function."

[0025] 3 is a block diagram of an example of a functional configuration for performing overtaking assist control and route driving assist control in the controller 20. The controller 20 includes a preceding vehicle recognition unit 30, a map information acquisition unit 31, a navigation information acquisition unit 32, a self-position information acquisition unit 33, a surrounding situation recognition unit 34, an overtaking proposal determination unit 35, a route driving proposal determination unit 36, an arbitration unit 37, a lane change feasibility determination unit 38, and a lane change state management unit 39. The preceding vehicle recognition unit 30 recognizes a preceding vehicle that is located ahead of the lane in which the host vehicle 1 is traveling based on driving information, and detects the relative speed Vr of the preceding vehicle with respect to the host vehicle 1 (Vr = vehicle speed Vp of the preceding vehicle - vehicle speed Vh of the host vehicle). The map information acquisition unit 31 acquires map information from the map database 13 or a communication device (not shown).

[0026] The navigation information acquisition unit 32 acquires route information relating to a target driving route to the destination from the navigation system 15. The self-position information acquisition unit 33 acquires current position information relating to the current position of the host vehicle 1 from the positioning device 12. The surrounding situation recognition unit 34 recognizes the situation around the host vehicle 1 (e.g., other vehicles and white lines) based on the driving information. In particular, the surrounding situation recognition unit 34 recognizes the distance d between the host vehicle 1 and another vehicle on the destination lane in the direction in which the lane extends. For example, the distance d may be the inter-vehicle distance or inter-vehicle time between the host vehicle 1 and another vehicle in the direction in which the lane extends.

[0027] When the leading vehicle recognition unit 30 recognizes a leading vehicle, the overtaking proposal determination unit 35 determines whether or not a predetermined overtaking proposal condition is satisfied. For example, the overtaking proposal condition may include the following conditions. - The overtaking assistance function is enabled. The relative speed Vr of the preceding vehicle with respect to the host vehicle 1 is less than the threshold speed Vt. The distance d between the vehicle 1 and another vehicle in the destination lane is equal to or greater than the distance threshold Dp. Other conditions for allowing a lane change are met (for example, lane markings do not prohibit lane changes, the road curvature radius is greater than or equal to a threshold, etc.). In the overtaking proposal condition, the interval threshold Dp is set to a relatively long value d1. When the overtaking proposal condition is satisfied, the overtaking proposal determination unit 35 outputs an overtaking proposal request to the arbitration unit 37.

[0028] When overtaking by the overtaking assist control is completed, the overtaking suggestion determination unit 35 determines whether or not predetermined lane return suggestion conditions are met. For example, the lane return suggestion conditions may include the following conditions. - The overtaking assistance function is enabled. The distance d between the vehicle 1 and another vehicle in the destination lane is equal to or greater than the distance threshold Dp. Other lane change permission conditions are met. In the lane return suggestion condition, the distance threshold Dp is set to a value d1. When the lane return proposal condition is satisfied, the overtaking proposal determination unit 35 outputs a lane return proposal request to the arbitration unit 37.

[0029] On the other hand, the route travel suggestion determination unit 36 ​​selects a lane (hereinafter sometimes referred to as a "target lane") in which the vehicle 1 should currently travel in order to travel along the target travel route set by the navigation system 15, and determines whether the lane satisfies predetermined route travel suggestion conditions. For example, the route travel suggestion conditions may include the following conditions.

[0030] - Route driving assistance function is enabled. The lane in which the vehicle 1 is currently traveling is different from the target lane. The distance dr from the current position of the vehicle 1 to the driving direction change point is less than or equal to the distance da and greater than or equal to the distance db. For example, the distance da may be (2300 m + 400 m × N), and the distance db may be (700 m + 400 m × N). The natural number N is the number of lane changes required for the vehicle 1 to move from the lane it is currently traveling in to the target lane. Lane change to the target lane is possible (for example, lane markings do not prohibit lane changes, the curvature radius of the road is greater than or equal to a threshold, etc.). That is, the route travel proposal determination unit 36 ​​determines whether the route travel proposal conditions are met regardless of the distance d in the lane extension direction between the vehicle 1 and another vehicle on the destination lane. If the route travel proposal conditions are met, the route travel proposal determination unit 36 ​​sets a proposal point where a route travel proposal will be presented. When the vehicle 1 reaches the proposal point, the route travel proposal determination unit 36 ​​outputs a route travel proposal request to the arbitration unit 37.

[0031] The arbitration unit 37 arbitrates between the overtaking proposal request output by the overtaking proposal determination unit 35 and the route driving proposal request output by the route driving proposal determination unit 36. If only the overtaking proposal request is output, the overtaking proposal is adopted, and if only the route driving proposal request is output, the route driving proposal is adopted. If both the overtaking proposal request and the route driving proposal request are output, either the overtaking proposal or the route driving proposal is adopted. For example, the route driving proposal may be adopted preferentially. Similarly, the arbitration unit 37 arbitrates between the lane return proposal request output by the overtaking proposal determination unit 35 and the route driving proposal request output by the route driving proposal determination unit 36. The arbitration unit 37 outputs the arbitration result to the lane change feasibility determination unit 38 and the lane change state management unit 39.

[0032] When the arbitration unit 37 adopts the overtaking suggestion, the lane change state management unit 39 outputs overtaking information for presenting the overtaking suggestion to the occupant via the display device 16 or the audio output device 17. Idea If adopted, the lane change state management unit 39 outputs lane return information for presenting the lane return proposal to the occupant via the display device 16 or the audio output device 17. If the arbitration unit 37 adopts the route driving proposal, the lane change state management unit 39 outputs route driving information for presenting the route driving proposal to the occupant via the display device 16 or the audio output device 17.

[0033] When the overtaking suggestion is presented, the lane change state management unit 39 determines whether or not a predetermined overtaking suggestion continuation condition is satisfied. For example, the overtaking suggestion continuation condition may include the following conditions. - The overtaking assistance function is enabled. The relative speed Vr of the preceding vehicle with respect to the host vehicle 1 is less than the threshold speed Vt. The distance d between the host vehicle 1 and another vehicle on the destination lane in the direction of the lane extension is equal to or greater than the distance threshold Dp. Other lane change permission conditions are met. In the overtaking proposal continuation condition, the interval threshold Dp is set to a relatively short value d2. The interval threshold d2 may be a value shorter than the interval threshold d1 (d2 < d1). While the overtaking proposal continuation condition holds, the lane change state management unit 39 continues the overtaking proposal. When the overtaking proposal continuation condition no longer holds, the lane change state management unit 39 cancels the overtaking proposal.

[0034] Similarly, when presenting a lane return proposal, the lane change state management unit 39 determines whether a predetermined lane return proposal continuation condition is satisfied. For example, the lane return proposal continuation condition may include the following conditions. · The overtaking support function is effective. · The interval d in the lane extension direction between the other vehicle on the destination lane and the own vehicle 1 is equal to or greater than the interval threshold Dp. · Other lane change permission conditions are satisfied. In the lane return proposal continuation condition, the interval threshold Dp is set to the value d2. While the lane return proposal Continuation conditions holds, the lane change state management unit 39 continues the lane return proposal. When the lane return proposal continuation condition no longer holds, the lane change state management unit 39 cancels the lane return proposal.

[0035] During the continuation of the overtaking proposal, if the occupant operates the lane change support switch 186 of the input device 18 to approve the overtaking proposal, the lane change state management unit 39 turns on the direction indicator. For example, the lane change state management unit 39 may turn on the direction indicator immediately when the lane change support switch 186 is operated. Also, when the occupant approves the overtaking proposal, the lane change permission determination unit 38 determines whether a predetermined overtaking execution condition is satisfied. The overtaking execution condition may be, for example, the same condition as the overtaking proposal continuation condition. When the occupant approves the overtaking proposal and the overtaking execution condition is satisfied, the lane change state management unit 39 starts an automatic lane change. In the automatic lane change, the lane change state management unit 39 starts a lane change operation so that the own vehicle 1 moves to the destination lane.

[0036] If the occupant approves the lane return proposal by operating the lane change assistance switch 186 of the input device 18 while the lane return proposal is ongoing, the lane change state management unit 39 turns on the turn indicator. For example, the lane change state management unit 39 may turn on the turn indicator immediately when the lane change assistance switch 186 is operated. Furthermore, when the occupant approves the lane return proposal, the lane change feasibility determination unit 38 determines whether a predetermined lane return execution condition is met. The lane return execution condition may be, for example, the same condition as the lane return proposal continuation condition. When the occupant approves the lane return proposal and the lane return execution conditions are satisfied, the lane change state management unit 39 starts an automated lane change. In the automated lane change, the lane change state management unit 39 starts a lane change operation so that the host vehicle 1 moves back to the original lane.

[0037] When the proposed route is presented, the lane change state management unit 39 determines whether or not a predetermined condition for continuing the proposed route is satisfied. For example, the condition for continuing the proposed route may include the following conditions. - Route driving assistance function is enabled. The lane in which the vehicle 1 is currently traveling is different from the target lane. The distance dr from the current position of the vehicle 1 to the driving direction change point is equal to or less than the distance da and equal to or greater than the distance db. The distance d between the host vehicle 1 and another vehicle on the destination lane in the direction of the lane extension is equal to or greater than the distance threshold Dp. In the route travel suggestion continuation condition, the interval threshold Dp is set to a value d2. If the occupant operates the lane change assistance switch 186 of the input device 18 to approve the proposed route while the proposed route is being continued, the lane change feasibility determination unit 38 determines whether a predetermined condition for executing the route is met. The condition for executing the route may be the same as the condition for continuing the proposed route. The lane change feasibility determination unit 38 also determines whether a lane change to the target lane is possible (for example, whether conditions such as lane markings not prohibiting lane changes, or the curvature radius of the road being equal to or greater than a threshold are met).

[0038] When the route travel execution conditions are satisfied and a lane change to the target lane is possible, the lane change state management unit 39 turns on the turn signal and executes a lane change operation. Furthermore, the lane change state management unit 39 starts a lane change operation so that the host vehicle 1 moves to the destination lane, on the condition that the route travel execution conditions are satisfied. The vehicle behavior control device 19 controls the operation of the steering actuator based on a command from the lane change state management unit 39, thereby performing steering control of the host vehicle 1.

[0039] (operation) 4 is a flowchart of an example of processing when proposing to overtake. In step S1, the overtaking proposal determination unit 35 determines whether or not a preceding vehicle exists ahead of the host vehicle 1. If a preceding vehicle exists (step S1: Y), the processing proceeds to step S2. If a preceding vehicle does not exist (step S1: N), the processing ends. In step S2, the overtaking proposal determination unit 35 determines whether the relative speed Vr of the preceding vehicle is less than the threshold speed Vt. If the relative speed Vr is less than the threshold speed Vt (step S2: Y), the process proceeds to step S3. If the relative speed Vr is not less than the threshold speed Vt (step S2: N), the process ends. In step S3, the overtaking proposal determination unit 35 sets the interval threshold Dp to a value d1.

[0040] In step S4, the overtaking proposal determination unit 35 determines whether the distance d between the vehicle 1 and another vehicle in the destination lane is equal to or greater than the distance threshold Dp. If the distance d is equal to or greater than the distance threshold Dp (step S4: Y), the process proceeds to step S5. If the distance d is not equal to or greater than the distance threshold Dp (step S4: N), the process ends. In step S5, the overtaking suggestion determination unit 35 determines whether the overtaking support function is enabled. If the overtaking support function is enabled (step S5: Y), the process proceeds to step S6. If the overtaking support function is not enabled (step S5: N), the process ends. In step S6, the overtaking proposal determination unit 35 outputs the overtaking proposal request to the arbitration unit 37. In step S7, the arbitration unit 37 arbitrates between the overtaking proposal request and the route traveling proposal request, after which the process ends.

[0041] 5 is a flowchart of an example of processing when proposing to return to the lane. In step S10, the overtaking proposal determination unit 35 sets the interval threshold Dp to a value d1. In step S11, the overtaking proposal determination unit 35 determines whether the distance d between the vehicle 1 and another vehicle in the destination lane is equal to or greater than the distance threshold Dp. If the distance d is equal to or greater than the distance threshold Dp (step S11: Y), the process proceeds to step S12. If the distance d is not equal to or greater than the distance threshold Dp (step S11: N), the process ends. In step S12, the overtaking suggestion determination unit 35 determines whether the overtaking support function is enabled. If the overtaking support function is enabled (step S12: Y), the process proceeds to step S13. If the overtaking support function is not enabled (step S12: N), the process ends. In step S13, the overtaking proposal determination unit 35 outputs a lane return proposal request to the arbitration unit 37. In step S14, the arbitration unit 37 arbitrates between the lane return proposal request and the route travel proposal request, after which the processing ends.

[0042] 6 is a flowchart of an example of a process for proposing a route. In step S20, the route travel proposal determination unit 36 ​​selects a target lane for traveling along the target travel route. In step S21, the route travel suggestion determination unit 36 ​​determines whether the route travel support function is enabled. If the route travel support function is enabled (step S21: Y), the process proceeds to step S22. If the route travel support function is not enabled (step S21: N), the process ends. In step S22, the route travel proposal determination unit 36 ​​determines whether the driving lane of the host vehicle 1 differs from the target lane. If the driving lane of the host vehicle 1 differs from the target lane (step S22: Y), the process proceeds to step S23. If the driving lane of the host vehicle 1 does not differ from the target lane (step S22: N), the process ends.

[0043] In step S23, the route travel proposal determination unit 36 ​​determines whether or not a lane change to the target lane is possible. If a lane change to the target lane is possible (step S23: Y), the process proceeds to step S24. If a lane change to the target lane is not possible (step S23: N), the process ends. In step S24, the route travel suggestion determination unit 36 ​​determines whether the distance dr from the current position of the vehicle 1 to the travel direction change point is equal to or less than the distance da and equal to or greater than the distance db. If the distance dr is equal to or less than the distance da and equal to or greater than the distance db (step S24: Y), the process proceeds to step S25. If the distance dr is not equal to or less than the distance da and equal to or greater than the distance db (step S24: N), the process ends. In step S25, the route travel proposal determination unit 36 ​​outputs a route travel proposal request to the arbitration unit 37. In step S26, the arbitration unit 37 arbitrates between the overtaking proposal request and the route travel proposal request, or between the lane return proposal request and the route travel proposal request. Thereafter, the processing ends.

[0044] 7 is a flowchart showing an example of processing for executing a lane change when an overtaking suggestion is adopted. In step S30, the lane change state management unit 39 presents the overtaking suggestion to the occupant. In step S31, the lane change state management unit 39 sets the distance threshold Dp to a value d2. In step S32, the lane change state management unit 39 determines whether the relative speed Vr of the preceding vehicle is less than the threshold speed Vt. If the relative speed Vr is less than the threshold speed Vt (step S32: Y), the process proceeds to step S33. If the relative speed Vr is not less than the threshold speed Vt (step S32: N), the process proceeds to step S37. In step S33, the lane change state management unit 39 determines whether the overtaking support function is enabled. If the overtaking support function is enabled (step S33: Y), the process proceeds to step S34. If the overtaking support function is not enabled (step S33: N), the process proceeds to step S37.

[0045] In step S34, the lane change state management unit 39 determines whether the distance d between the vehicle 1 and another vehicle on the destination lane is equal to or greater than the distance threshold Dp. If the distance d is equal to or greater than the distance threshold Dp (step S34: Y), the process proceeds to step S35. If the distance d is not equal to or greater than the distance threshold Dp (step S34: N), the process proceeds to step S37. In step S35, the lane change state management unit 39 determines whether the occupant has accepted the overtaking proposal. If the occupant has accepted the overtaking proposal (step S35: Y), the process proceeds to step S36. If the occupant has not accepted the overtaking proposal (step S35: N), the process returns to step S32. In step S36, the lane change possibility determination unit 38 determines whether the overtaking execution condition is met. If the overtaking execution condition is met, the lane change state management unit 39 executes an automated lane change to move the host vehicle 1 into the destination lane. Then, the processing ends. In step S37, the lane change state management unit 39 cancels the overtaking proposal. Then, the processing ends.

[0046] 8 is a flowchart of an example of processing when a lane change is executed when a lane return suggestion is adopted. In step S40, the lane change state management unit 39 presents the lane return suggestion to the occupant. In step S41, the lane change state management unit 39 sets the gap threshold Dp to a value d2. In step S42, the lane change state management unit 39 determines whether the overtaking support function is enabled. If the overtaking support function is enabled (step S42: Y), the process proceeds to step S43. If the overtaking support function is not enabled (step S42: N), the process proceeds to step S46.

[0047] In step S43, the lane change state management unit 39 determines whether the distance d between the vehicle 1 and another vehicle on the destination lane is equal to or greater than the distance threshold Dp. If the distance d is equal to or greater than the distance threshold Dp (step S43: Y), the process proceeds to step S44. If the distance d is not equal to or greater than the distance threshold Dp (step S43: N), the process proceeds to step S46. In step S44, the lane change state management unit 39 determines whether the occupant has accepted the overtaking proposal. If the occupant has accepted the overtaking proposal (step S44: Y), the process proceeds to step S45. If the occupant has not accepted the overtaking proposal (step S45: N), the process returns to step S42. In step S45, the lane change possibility determination unit 38 determines whether the lane return execution condition is met. If the lane return execution condition is met, the lane change state management unit 39 executes an automated lane change to return the host vehicle 1 to the original lane before overtaking. Then, the process ends. In step S46, the automated lane change is canceled. Then, the process ends.

[0048] 9 is a flowchart of an example of processing when a lane change is executed when a proposed route is adopted. In step S50, the lane change state management unit 39 presents the proposed route to the occupant. In step S51, the lane change state management unit 39 sets the interval threshold Dp to a value d2. In step S52, the lane change state management unit 39 determines whether the route driving assistance function is enabled. If the route driving assistance function is enabled (step S52: Y), the process proceeds to step S53. If the route driving assistance function is not enabled (step S52: N), the process proceeds to step S62. In step S53, the lane change state management unit 39 determines whether the driving lane of the host vehicle 1 differs from the target lane. If the driving lane of the host vehicle 1 differs from the target lane (step S53: Y), the process proceeds to step S54. If the driving lane of the host vehicle 1 does not differ from the target lane (step S53: N), the process proceeds to step S62.

[0049] In step S54, the lane change state management unit 39 determines whether the distance dr from the current position of the vehicle 1 to the driving direction change point is equal to or less than the distance da and equal to or greater than the distance db. If the distance dr is equal to or less than the distance da and equal to or greater than the distance db (step S54: Y), the process proceeds to step S55. If the distance dr is not equal to or less than the distance da and equal to or greater than the distance db (step S54: N), the process proceeds to step S62. In step S55, the lane change state management unit 39 determines whether the occupant has approved the proposed route. If the occupant has approved the proposed route (step S55: Y), the process proceeds to step S56. If the occupant has not approved the proposed route (step S55: N), the process returns to step S52. In steps S56 to S58, the lane change possibility determination unit 38 executes the same processing as the processing in steps S52 to S54. If the distance dr to the driving direction change point is equal to or less than the distance da and equal to or greater than the distance db (step S58: Y), the processing proceeds to step S59.

[0050] In step S59, the lane change possibility determination unit 38 determines whether or not a lane change to the target lane is possible. If a lane change to the target lane is possible (step S59: Y), the process proceeds to step S60. If a lane change to the target lane is not possible (step S59: N), the process returns to step S56. In step S60, the lane change possibility determination unit 38 determines whether the distance d between the vehicle 1 and another vehicle on the destination lane is equal to or greater than the distance threshold Dp. If the distance d is equal to or greater than the distance threshold Dp (step S60: Y), the process proceeds to step S61. If the distance d is not equal to or greater than the distance threshold Dp (step S60: N), the process returns to step S56. In step S61, the lane change state management unit 39 executes an automated lane change to move the host vehicle 1 to the destination lane. Then, the process ends. In step S62, the lane change state management unit 39 cancels the automated lane change. Then, the process ends.

[0051] (Effects of the embodiment) (1) The controller 20 performs driving assistance control to propose a lane change and execute a lane change by autonomous driving control based on the occupant's approval. When the controller 20 detects a preceding vehicle traveling at a speed relatively slower than the vehicle speed of the host vehicle 1, if it determines that a first distance, which is the distance between the host vehicle 1 and another vehicle on a first adjacent lane, is equal to or greater than a first threshold, the controller 20 performs the following processes: start proposing a lane change to the first adjacent lane; continue proposing a lane change to the first adjacent lane on the condition that the first distance is equal to or greater than a second threshold that is smaller than the first threshold; and activate a turn signal on the first adjacent lane side if the occupant approves the lane change proposal while the controller 20 is proposing a lane change to the first adjacent lane. In this way, by setting a first spacing condition for continuing a lane change proposal that is more lenient than the first spacing condition for initiating a lane change proposal and combining it with the condition for activating a turn signal, the lane change proposal can be continued even if the distance to another vehicle in an adjacent lane changes after the lane change proposal. Furthermore, because the turn signal can be activated upon acceptance, the distance to another vehicle in an adjacent lane is less likely to change after the turn signal is activated. This reduces the frequency of lane change proposal cancellations after a lane change proposal is made. It also reduces the possibility that the driver will mistakenly accept a lane change proposal even though the proposal has been canceled immediately after it was proposed.

[0052] (2) If the occupant accepts the proposal to change lanes to the first adjacent lane, the controller 20 may start the lateral movement of the host vehicle 1 toward the first adjacent lane, provided that the first distance is equal to or greater than the second threshold. By matching the condition for continuing the proposal to change lanes with the condition for starting the lateral movement in this way, if the occupant accepts the proposal but does not start the lateral movement, the occupant can easily recognize that the situation in the first adjacent lane has changed since the time of the acceptance.

[0053] (3) The controller 20 may perform the following operations: setting a proposed point based on a preset target driving route, where the vehicle 1 proposes a lane change to the second adjacent lane; proposing a lane change to the second adjacent lane when the vehicle 1 reaches the proposed point; determining whether the occupant has approved the proposal to change to the second adjacent lane; activating a turn signal for the second adjacent lane if the second distance between the vehicle 1 and another vehicle on the second adjacent lane is determined to be equal to or greater than a second threshold value when the proposal to change to the second adjacent lane has been approved; and starting lateral movement of the vehicle 1 toward the second adjacent lane, provided that the second distance is equal to or greater than the second threshold value. This allows the proposal to be made at the desired timing (i.e., the occupant's intention can be confirmed at an early stage) when proposing a lane change based on the preset target driving route, without determining whether there is free space in the second adjacent lane at the time of the proposal. This allows the travel distance to be secured before the lateral movement begins after the approval. It is also possible to prevent a proposal from being immediately canceled due to changes in the surrounding environment after the proposal is made. Furthermore, by using the same second threshold to determine whether there is free space in the adjacent lane after a proposal is accepted, for a lane change proposal based on the target driving route of the vehicle 1 and a lane change proposal due to a preceding vehicle that is slower than the vehicle 1, the series of system decisions regarding lane changes after the action of acceptance can be unified, making it easier for occupants to predict the vehicle's movements after acceptance.

[0054] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0055] 1... Vehicle, 10... Driving assistance device, 11... Sensor, 12... Positioning device, 13... Map DB, 14... In-vehicle equipment, 15... Navigation system, 16... Display device, 17... Audio output device, 18... Input device, 19... Vehicle behavior control device, 20... Controller

Claims

1. A driving assistance method for suggesting a lane change and executing the lane change by autonomous driving control based on an occupant's approval, a process of starting a proposal to change lanes to the first adjacent lane when a preceding vehicle traveling at a speed relatively slower than the vehicle speed of the own vehicle is detected and a first interval between the own vehicle and another vehicle on a first adjacent lane is determined to be equal to or greater than a first threshold value; a process of continuing to propose a lane change to the first adjacent lane on the condition that the first distance is equal to or greater than a second threshold value that is smaller than the first threshold value; a process of activating a turn signal on the first adjacent lane side when an occupant performs an approval action while the lane change proposal to the first adjacent lane is being made; A driving assistance method characterized by causing a controller to execute the above.

2. The driving assistance method described in claim 1, characterized in that if the occupant performs an approval action while the controller is proposing a lane change to the first adjacent lane, the controller starts lateral movement of the vehicle toward the first adjacent lane, provided that the first distance is greater than or equal to the second threshold value.

3. A process of setting a proposed point, which is a point where a lane change to the second adjacent lane is proposed, based on a preset target driving route; a process of proposing a lane change to the second adjacent lane when the host vehicle reaches the proposed point; a process of determining whether or not the occupant has accepted the proposal to change lanes to the second adjacent lane; a process of activating a turn signal on the second adjacent lane side when it is determined that a second gap between the vehicle and another vehicle on the second adjacent lane is equal to or greater than the second threshold value when the approval action for the proposal to change lanes to the second adjacent lane has been performed; a process of starting lateral movement of the host vehicle toward the second adjacent lane side on condition that the second distance is equal to or greater than the second threshold value; 3. The driving assistance method according to claim 1, wherein the driving assistance method further comprises:

4. A driving assistance device that proposes a lane change and executes the lane change by autonomous driving control based on the approval of an occupant, a process of starting a proposal to change lanes to the first adjacent lane when a preceding vehicle traveling at a speed relatively slower than the vehicle speed of the own vehicle is detected and a first interval between the own vehicle and another vehicle on a first adjacent lane is determined to be equal to or greater than a first threshold value; a process of continuing to propose a lane change to the first adjacent lane on the condition that the first distance is equal to or greater than a second threshold value that is smaller than the first threshold value; a process of activating a turn signal on the first adjacent lane side when an occupant performs an approval action while the lane change proposal to the first adjacent lane is being made; A driving assistance device comprising a controller that executes the above.

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