Vehicle travel control method and vehicle travel control device

Abstract

A vehicle driving control method, based on map information representing lane shapes by nodes and links, enables a vehicle to travel along a lane by automatic steering, wherein the controller performs the following processes: determining whether the target driving path of a vehicle traveling on a first road is a path leading into a second road branching off from the first road (S1); if the target driving path is a path leading into the second road, calculating a first trajectory connecting the branch point of the link representing the lane shape of the second lane on the second road (i.e., the second link) from the branch point of the link representing the lane shape of the first lane on the first road (i.e., the first link), and a point on the second link that moves away from the branch point by only a predetermined distance along the second link, and setting a target driving trajectory based on the first trajectory; and controlling the vehicle to travel along the target driving trajectory (S3, S8).

Description

Technical Field

[0001] This invention relates to a vehicle driving control method and a vehicle driving control device. Background Technology

[0002] Patent Document 1 describes a technique for estimating the centerline of a lane using sensor information from cameras, etc., and navigating an autonomous vehicle along a lowest-cost path generated based on the centerline.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2020-66428

[0006] The problem that the invention aims to solve

[0007] Within the branching section where the second road branches off from the first road, the driving path from the first road to the second road is sometimes not clearly indicated by lane boundary lines. Therefore, it is sometimes impossible to properly generate the target driving trajectory for vehicles entering the second road branching off from the first road based on sensor information. In this case, if the target driving trajectory is set based on map information representing lane shapes using nodes and links, abrupt steering may occur depending on the lane shape of the second road branching off from the first road, potentially causing discomfort to the occupants. Summary of the Invention

[0008] The purpose of this invention is to suppress occupant discomfort when a vehicle enters a second road branching from a first road based on map information representing lane shapes by nodes and links and through automatic steering control.

[0009] According to one aspect of the present invention, a vehicle driving control method is provided, which enables a vehicle to travel along a lane by automatic steering based on map information representing lane shapes by nodes and links. In this vehicle driving control method, a controller performs the following processes: determining whether the target driving path of a vehicle traveling on a first road is a path leading into a second road branching off from the first road; if the target driving path is a path into the second road, calculating a first trajectory connecting the branch points of the links representing the lane shape of a second lane on the second road (i.e., the second link) from the branch points of the links representing the lane shape of the first lane on the first road (i.e., the first link), and points on the second link that are only a predetermined distance away from the branch points along the second link, and setting a target driving trajectory based on the first trajectory; and controlling the vehicle to travel along the target driving trajectory.

[0010] Invention Effects

[0011] According to the present invention, it is possible to suppress the discomfort of occupants when a vehicle enters a second road branching from a first road by automatic steering control based on map information representing the lane shape by nodes and links.

[0012] The objects and advantages of this invention are embodied and realized by utilizing the elements and combinations thereof shown in the claims. The above general description and the following detailed description are merely examples and illustrations and should not be construed as limiting the invention as the scope of the claims suggests. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of the general structure of a vehicle equipped with a driving assistance device according to an embodiment.

[0014] Figure 2 It is stored in Figure 1 An illustration of high-precision map information in a map database.

[0015] Figure 3 It means Figure 1 A diagram of a portion of the input device.

[0016] Figure 4 This is an explanatory diagram of an example of a vehicle driving control method according to an implementation method.

[0017] Figure 5 yes Figure 1 A block diagram of an example of the functional structure of the controller in the example.

[0018] Figure 6 This is an illustrative diagram illustrating an example of correction to the shortest route trajectory.

[0019] Figure 7 This is an illustrative diagram illustrating an example of not using the shortest route trajectory.

[0020] Figure 8 This is a flowchart of an example of a vehicle driving control method implemented in this way. Detailed Implementation

[0021] (structure)

[0022] Figure 1This diagram illustrates an example of the schematic structure of a vehicle equipped with a driver assistance device according to the embodiments. The driver assistance device 10 mounted on this vehicle 1 includes: a sensor 11, a positioning device 12, a map database (map DB) 13, an in-vehicle device 14, a navigation system 15, a display device 16, a voice output device 17, an input device 18, a vehicle behavior control device 19, and a controller 20. These devices are connected to each other for receiving and transmitting information, for example, via CAN (Controller Area Network) and other in-vehicle LANs. The driver assistance device 10 is an example of a "vehicle driving control device" described in the claims.

[0023] Sensor 11 detects the driving status of vehicle 1. For example, sensor 11 includes cameras that capture images of the front, rear, and sides of vehicle 1. Additionally, sensor 11 includes radar that detects obstacles in front, rear, and sides of vehicle 1. Sensor 11 includes a vehicle speed sensor that detects the vehicle speed, a touch sensor that detects the occupant's holding of the steering wheel, and an occupant monitor that captures images of the occupants. Positioning device 12 includes a GPS unit, a gyroscope sensor, etc. Positioning device 12 periodically acquires the position information of vehicle 1 via the GPS unit. Furthermore, positioning device 12 detects the current position of vehicle 1 based on the position information of vehicle 1, angle change information acquired from the gyroscope sensor, and vehicle speed acquired from the vehicle speed sensor.

[0024] Map database 13 is a memory that stores high-precision map information containing location information of various facilities and specific locations, and is accessible from controller 20. The high-precision map information is map information that associates detailed and high-precision location information such as curved roads and the size of their curves (e.g., curvature or radius of curvature), merging points of roads, branching points, toll booths, and reduction locations of lane numbers with map information to form three-dimensional information.

[0025] Figure 2 It is stored in Figure 1 The diagram illustrates the high-precision map information in map database 13. High-precision map information, as information per lane unit (i.e., lane information), includes information about nodes representing reference points on lane baselines (e.g., the center line within a lane) and information about links representing the morphology of lane sections between nodes. In other words, high-precision map information represents lane shape through multiple nodes and multiple links connecting them (in other words, lane shape is represented by the connection of multiple links).

[0026] Figure 2The example illustrates a high-precision map showing the lane shapes of lanes on a first road R1 and a second road R2. Lanes TL1 and TL3 are provided on the first road R1, and lane TL2 is provided on the second road R2. In the following description, lane TL1 and lane TL2 will be referred to as "first lane TL1" and "second lane TL2," respectively.

[0027] The second road R2 is a branch road from the first road R1. The interval from the starting point Ps of the branch from the first road R1 to the ending point Pe of the branch is described as the "branch interval Sj". For example, the first road R1 can be a main road of a motor vehicle-only road such as a highway, and the second road R2 can be a branch road that branches from the main road.

[0028] The high-precision map information includes node ND1 and links LK11, LK12, LK2, and LK3, represented by dashed lines, which serve as information representing the lane shapes of the first road R1 and the second road R2. In the following description, link LK11 is referred to as "first link LK11", link LK12 as "first link LK12", and link LK2 as "second link LK2". Each link is formed by a point sequence PL, which arranges the link constituent points CP representing reference points on the lane baseline (e.g., the center line within the lane). Therefore, the point sequence PL, which consists of link constituent points CP, can represent not only straight links but also curved links.

[0029] First links LK11 and LK12 represent the lane shape of the first lane TL1 on the first road R1 by representing the lane centerline. Link LK3 represents the lane shape of lane TL3 on the first road R1 by representing the lane centerline. Second link LK2 represents the lane shape of the second lane TL2 on the second road R2 by representing the lane centerline. Furthermore, by connecting the second link LK2 to node ND1, which connects the first links LK11 and LK12, the second lane TL2 of the second road branching from the first road R1 takes on a shape that connects to the first lane TL1 of the first road R1.

[0030] Reference Figure 1 The vehicle-mounted equipment 14 refers to various devices mounted on the vehicle 1 that are operated by an occupant (e.g., the driver). Examples of such vehicle-mounted equipment include a steering wheel, accelerator pedal, brake pedal, turn indicators, windshield wipers, lights, horn, and other specific switches.

[0031] The navigation system 15 acquires the current location information of the vehicle 1 from the positioning device 12, overlays the vehicle 1's location onto the navigation map information, and displays it on a display or similar device. Furthermore, when a destination is set, the navigation system 15 sets the path from the vehicle 1's current location to the destination as the target driving route and executes navigation control to guide the occupants along this target driving route. In this navigation control, the navigation system 15 displays the target driving route on the map on the display and informs the occupants of the target driving route via voice or other means. The target driving route set in the navigation system 15 is also used for the route driving assistance control of the controller 20. Route driving assistance control enables the vehicle 1 to autonomously drive along the target driving route.

[0032] Display device 16 includes various displays positioned in a location visually accessible to the occupants. Display device 16 provides various prompts to the occupants under the control of controller 20. Sound output device 17 is a device that outputs auditory information from speakers, audio devices, buzzers, etc., provided by navigation system 15. Sound output device 17 provides various prompts to the occupants under the control of controller 20.

[0033] The input device 18 may be a push-button switch that can be manually operated by the occupant, a touchpad on the display screen, or a microphone that allows voice input by the occupant. The occupant can use the input device 18 to input setting information for prompts displayed by the display device 16 or the audio output device 17.

[0034] Figure 3 This diagram shows a portion of the input device 18 according to this embodiment. The input device 18 may be, for example, a set of push-button switches disposed on the spokes of a steering wheel. The input device 18 is used to set the on / off state of autonomous driving control based on the controller 20. The input device 18 includes: a main switch 181, a resume / accelerate switch 182, a set / coast switch 183, a cancel switch 184, a lane adjustment switch 185, and a lane change assist switch 186. The main switch 181 is used to switch the autonomous driving control of the controller 20 on / off. The resume / accelerate switch 182 is used to set the autonomous driving control to restart at the set speed before disconnection, or to increase the set speed, after the autonomous driving control is disconnected. The set / coast switch 183 is used to start the autonomous driving control. To start the autonomous driving control, after the autonomous driving control is activated via the main switch 181, the set / coast switch 183 is pressed. Additionally, the set / coast switch 183 is used to decrease the set speed. The cancel switch 184 is used to deactivate the autonomous driving control. Lane change adjustment switch 185 is used to set the lane distance to the vehicle ahead. Lane change assist switch 186 is used to indicate (confirm) the start of a lane change when the controller 20 confirms the start of a lane change to the occupants. In addition, besides... Figure 3 In addition to the button switch group shown, the direction indicator stick of the direction indicator or other vehicle equipment 14 can also be used as input device 18.

[0035] Reference Figure 1 The vehicle behavior control device 19 controls the vehicle behavior of the vehicle 1. For example, when the vehicle 1 is traveling at a constant speed through autonomous driving control, the vehicle behavior control device 19 controls the operation of the drive mechanism and the brakes used to achieve acceleration, deceleration, and speed, so that the vehicle 1 reaches the set speed. Furthermore, when the vehicle 1 is following a vehicle ahead through autonomous driving control, the vehicle behavior control device 19 also controls the operation of the drive mechanism and the brakes. In addition, the control of the drive mechanism's operation includes the operation of the internal combustion engine in engine-powered vehicles, and the operation of the electric motor in electric vehicle systems. Furthermore, in hybrid vehicles, the control includes the torque distribution between the internal combustion engine and the electric motor.

[0036] In addition, when the vehicle behavior control device 19 performs autonomous steering control as described later through autonomous driving control, in addition to controlling the movement of the drive mechanism and brakes, it also performs steering control of the vehicle 1 by controlling the movement of the steering actuator.

[0037] The controller 20 is one or more electronic control units (ECUs) for controlling the movement of the vehicle 1, and includes peripheral components such as a processor 21 and a storage device 22. The processor 21 may be, for example, a CPU or an MPU. The storage device 22 may be a semiconductor storage device, a magnetic storage device, an optical storage device, etc. The storage device 22 may include registers, cache memory, ROM and RAM used as main storage, etc. The functions of the controller 20 described below are implemented, for example, by causing the processor 21 to execute a computer program stored in the storage device 22.

[0038] The controller 20 performs a driving information acquisition function, which acquires information related to the driving state of the vehicle 1, and performs autonomous driving control, which autonomously controls the driving speed and / or steering of the vehicle 1. The driving information acquisition function is the function of acquiring driving information related to the driving state of the vehicle 1. For example, the controller 20 also acquires image information of the vehicle's exterior captured by the camera of sensor 11, radar detection results, and vehicle speed information from the vehicle speed sensor as driving information. In the following description, the driving information acquired from sensor 11 will sometimes be referred to as "sensor information".

[0039] Furthermore, the controller 20 obtains the current location information of the vehicle 1 from the positioning device 12 as driving information. The controller 20 obtains the set destination and the target driving route to the destination from the navigation system 15 as driving information. The controller 20 obtains map information such as location information and lane information, including curved roads and their curvature (e.g., curvature or radius of curvature), merging points, branching points, toll stations, and lane reduction locations from the map database 13 as driving information. The controller 20 obtains the occupant's operation information on the on-board device 14 as driving information.

[0040] In autonomous driving control, the controller 20 autonomously controls the driving of the vehicle 1 without relying on the operation of the occupants. Autonomous driving control includes autonomous speed control, which autonomously controls the driving speed of the vehicle 1, and autonomous steering control, which autonomously controls the steering of the vehicle 1.

[0041] In autonomous speed control, when a vehicle ahead is detected, the controller 20 follows the vehicle while maintaining a vehicle-to-vehicle distance corresponding to the speed set by the occupants, using the speed set or a speed limit as the upper limit. Conversely, when no vehicle ahead is detected, the controller maintains a constant speed at the speed set by the occupants or a speed limit. The former is also known as vehicle-to-vehicle control, and the latter is also known as constant speed control.

[0042] If, when the forward radar or other sensors (such as sensor 11) detect that there is no vehicle traveling ahead in the lane in which vehicle 1 is traveling, cruise control is executed. In cruise control, while feeding back vehicle speed data from the speed sensor, the vehicle behavior control device 19 controls the operation of the drive mechanism, such as the engine or brakes, to maintain the set driving speed. If, when the forward radar or other sensors (such as sensor 11) detects that there is a vehicle traveling ahead in the lane in which vehicle 1 is traveling, lane departure control is executed. In lane departure control, with the set driving speed as the upper limit, while feeding back the lane departure distance data detected by the forward radar, the vehicle behavior control device 19 controls the operation of the drive mechanism, such as the engine or brakes, to maintain the set lane departure distance.

[0043] In autonomous steering control, the controller 20 controls the movement of the steering actuator based on driving information acquired through the driving information acquisition function, thereby performing steering control of the vehicle 1. Autonomous steering control includes lane keeping control, lane change assist control, overtaking assist control, and route driving assist control.

[0044] In lane keeping control, the controller 20 controls, for example, the steering actuator to move near the center of the lane, thereby assisting the occupant in steering wheel operation.

[0045] In lane change assist control, the controller 20 illuminates the direction indicator when the occupant operates the direction indicator stalk, and determines whether the prescribed lane change initiation conditions are met based on various driving information obtained through the driving information acquisition function. If the lane change initiation conditions are met, the lane change operation begins.

[0046] During a lane change operation, the controller 20 performs a lane change maneuver that moves the vehicle 1 laterally to the adjacent lane of the lane change destination. While performing the lane change operation, the controller 20 displays a message indicating that a lane change is being performed automatically via the display device 16. Once the lane change operation is complete, the controller 20 turns off the direction indicator and begins lane keeping function in the new lane. The lane change operation ends, for example, when the vehicle 1 reaches within a predetermined distance of the center of the new lane.

[0047] In overtaking assist control, when the controller 20 detects a slower vehicle ahead of the vehicle 1 in the lane in which the vehicle 1 is traveling, and the prescribed overtaking proposal conditions are met, it proposes to the occupants to perform a lane change based on autonomous driving control to overtake the vehicle ahead. Hereinafter, the lane change proposal to overtake the vehicle ahead is sometimes referred to as an "overtaking proposal." Upon confirmation of the overtaking proposal by the lane change assist switch 186 on the occupant operation input device 18 and the prescribed overtaking execution conditions being met, the controller 20 performs an automatic lane change. In the automatic lane change, the controller 20 performs a lane change operation to move the vehicle 1 to the adjacent lane of the lane change destination.

[0048] In route driving assistance control, when the controller 20 moves a predetermined distance from a branch point, merging point, exit, toll station, or other direction-changing point on the target driving path set by the navigation system 15, and meets the predetermined route driving proposal conditions, it proposes to the occupant to perform a lane change using autonomous driving control to allow the vehicle 1 to travel along the target driving path. Hereinafter, the lane change proposal for allowing the vehicle 1 to travel along the target driving path will sometimes be referred to as a "route driving proposal." Upon confirmation of the route driving proposal by the lane change assistance switch 186 on the occupant operation input device 18 and the fulfillment of the predetermined route driving execution conditions, the controller 20 executes an automatic lane change. In the automatic lane change, the controller 20 performs a lane change operation to move the vehicle 1 to the adjacent lane of the lane change destination.

[0049] In the aforementioned autonomous steering control, the controller 20 generates a target driving trajectory based on sensor information obtained by the sensor 11 detecting the lane boundary line in front of the vehicle 1, and lane information around the current position of the vehicle 1 read from the map database 13 according to the measurement results of the positioning device 12, and controls the vehicle 1 to drive along the target driving trajectory. For example, the controller 20 performs image recognition processing on the image of the front of the vehicle 1 captured by the camera of the sensor 11 to detect the lane boundary line.

[0050] However, within the branch section Sj where the second road R2 branches off from the first road R1, the road leading from the first road R1 to the second road R2 is sometimes not clearly indicated by the lane boundary lines.

[0051] For example, in Figure 2 In the example, within the branch interval Sj, the lane boundary lines on the left and right sides of the second lane TL2 are configured such that the spacing between the boundary lines gradually increases towards the branch exit. Therefore, until the spacing between the boundary lines increases to at least the width of the vehicle, the lane boundary lines on the left and right sides of the second lane TL2 do not correctly indicate the travel path of vehicles entering the second road R2 from the first road R1. Alternatively, within the branch interval Sj, the lane boundary line between the second lane TL2 and the first lane TL1 can also be omitted.

[0052] Therefore, when controlling the vehicle 1 via autonomous steering to enter the second road R2 from the first road R1, the controller 20 sometimes fails to properly generate the target driving trajectory based on sensor information. In this case, if the target driving trajectory is set based on the shape of the link according to the high-precision map information stored in the map database 13, abrupt steering may occur based on the lane shape of the second lane TL2 of the second road R2 branching from the first road R1, causing discomfort to the occupants.

[0053] Therefore, the controller 20 generates a target driving trajectory in such a way that the curvature change is slower than that of the second lane TL2, from the branch point of the first lane TL1 and the second lane TL2 to a point on the second lane TL that is far away from the predetermined distance.

[0054] Reference Figure 4A specific example of the target driving trajectory is explained. Controller 20 calculates the trajectory (hereinafter referred to as the "shortest route trajectory") ST1 between the branch point (i.e., node ND1) of the second link LK2, which connects the lane shape of the second lane TL2 on the second road R2, from the branch point of the first link LK11 and LK12, which represent the lane shape of the first lane TL1 on the first road R1, and the link constituting point CP1 on the second link LK2, which is only a specified distance away from node ND1. Additionally, if the point on the second link LK2, which is only a specified distance away from node ND1, is another node ND2, the shortest route trajectory ST1 connecting node ND1 and node ND2 can also be calculated.

[0055] The controller 20 calculates the shortest route trajectory ST1, for example, in a manner with a straight-line portion, and smooths the connections between the shortest route trajectory ST1 and the first link LK11 or LK12, and between the shortest route trajectory ST1 and the second link LK2, respectively, to mitigate the curvature changes of the shortest route trajectory ST1 at these connections. For example, the shortest route trajectory ST1 may be a trajectory comprising a straight-line portion, a first transition curve portion formed between the straight-line portion and the first link LK11 or LK12, and a second transition curve portion formed between the straight-line portion and the second link LK2. The same applies to the shortest route trajectory ST2, which will be described later.

[0056] like Figure 4 As shown, the shortest route trajectory ST1 is calculated by passing through at least a portion of the range on the left and right sides of the second link LK2 along the first link LK11. By generating the target driving trajectory based on this shortest route trajectory ST1, the curvature change of the target driving trajectory based on the shape of the second link LK2 is smaller, compared to the curvature change in the case where the target driving trajectory is generated based on the shape of the second link LK2, thereby suppressing abrupt steering. As a result, discomfort to the occupants can be reduced. Furthermore, the shortest route trajectory ST1 is an example of the "first trajectory" described in the scope of the claim.

[0057] Next, refer to Figure 5 An example of the functional structure of the controller 20 will be described. The controller 20 includes: a map information acquisition unit 30, a self-position information acquisition unit 31, a surrounding condition recognition unit 32, a navigation information acquisition unit 33, and an autonomous driving control unit 34.

[0058] The map information acquisition unit 30 acquires high-precision map information through the map database 13 or a communication device not shown. The self-position information acquisition unit 31 acquires current position information related to the current position of the vehicle 1 from the positioning device 12. The surrounding condition recognition unit 32 recognizes the surrounding conditions of the vehicle 1 based on driving information. The surrounding condition recognition unit 32 identifies other vehicles around the vehicle 1 and the lane boundary lines in front of the vehicle 1 based on sensor information from the sensor 11. The navigation information acquisition unit 33 acquires route information related to the target driving path to the destination from the navigation system 15.

[0059] The autonomous driving control unit 34 executes the aforementioned autonomous speed control (constant speed control, distance control) and autonomous steering control (lane keeping control, lane change control, overtaking assist control, route driving assist control) based on the high-precision map information acquired by the map information acquisition unit 30, the current position information acquired by the self-position information acquisition unit 31, the recognition result of the surrounding situation recognition unit 32, and the route information acquired by the navigation information acquisition unit 33.

[0060] For example, in cruise control, the autonomous driving control unit 34 controls the vehicle behavior control device 19 to maintain the set driving speed. In lane control, the autonomous driving control unit 34 controls the vehicle behavior control device 19 to maintain the set lane distance, with the set driving speed as the upper limit.

[0061] In lane keeping control, the autonomous driving control unit 34 controls the vehicle behavior control device 19 to keep the vehicle 1 near the center of the lane. In lane change assist control, the autonomous driving control unit 34 illuminates the direction indicator when the occupant operates the direction indicator stalk and determines whether the prescribed lane change initiation conditions are met. If the lane change initiation conditions are met, the vehicle behavior control device 19 is controlled to move the vehicle 1 laterally towards the adjacent lane of the lane change destination.

[0062] Furthermore, in overtaking assist control, the autonomous driving control unit 34 prompts the occupant with an overtaking proposal if the prescribed overtaking proposal conditions are met. When the lane change assist switch 186 of the occupant operation input device 18 confirms the overtaking proposal and the prescribed overtaking execution conditions are met, the vehicle behavior control device 19 is controlled to cause the vehicle 1 to change lanes.

[0063] Furthermore, in route driving assistance control, the autonomous driving control unit 34 selects the lane (target lane) that the vehicle 1 should currently be traveling in in order to follow the target driving path, at a point a predetermined distance away from branch points, merging points, exits, toll stations, and other points of change of driving direction located on the target driving path set by the navigation system 15. If the vehicle's current lane (current lane) is different from the target lane, a route driving proposal is proposed to the occupants if the predetermined route driving proposal conditions are met. If the lane change assistance switch 186 of the occupant operation input device 18 confirms the route driving proposal and the predetermined route driving execution conditions are met, the vehicle behavior control device 19 is controlled to cause the vehicle 1 to change lanes to the target lane.

[0064] In these autonomous steering controls, the autonomous driving control unit 34 generates a target driving trajectory and controls the vehicle behavior control device 19 to drive along the target driving trajectory. Therefore, the autonomous driving control unit 34 includes a trajectory generation unit 34a and a vehicle control unit 34b.

[0065] The trajectory generation unit 34a generates a target driving trajectory based on high-precision map information, current location information, and the recognition results of the surrounding conditions recognition unit 32. The vehicle control unit 34b controls the vehicle behavior control device 19 to make the vehicle 1 drive along the target driving trajectory generated by the trajectory generation unit 34a. For example, the steering actuator can be controlled to make the vehicle 1 drive along the target driving trajectory, or a driving force difference or braking force difference can be applied between the left and right wheels.

[0066] For example, if the lane boundary lines are difficult to identify based on the sensor information from sensor 11, the trajectory generation unit 34a can generate a target driving trajectory based on the link shape of the high-precision map information acquired by the map information acquisition unit 30. Furthermore, when the vehicle 1 enters the second road R2 from the first road R1, a target driving trajectory can also be generated based on the link shape of the high-precision map information acquired by the map information acquisition unit 30.

[0067] Furthermore, for example, when the trajectory generation unit 34a is able to detect lane boundary lines based on sensor information and the vehicle 1 continues to travel on the first road R1, it can generate a target driving trajectory based on the lane boundary line recognition result based on the sensor information of sensor 11. Additionally, for example, after the vehicle 1 enters the second road R2 from the first road R1, if the vehicle 1's driving path can be identified based on the recognition result of the left and right lane boundary lines of the second lane TL2 of the second road R2, the trajectory generation unit 34a can also generate a target driving trajectory based on the lane boundary line recognition result based on the sensor information of sensor 11.

[0068] For example, the trajectory generation unit 34a may determine whether a lane change from the first lane TL1 of the first road R1 to the second lane TL2 of the second road R2 can be performed by lane change assist control or route driving assist control.

[0069] In a case where a lane change from the first lane TL1 to the second lane TL2 can be performed, for example, at a time point when the host vehicle 1 reaches a location that is a first predetermined distance L1 closer to the branch start point Ps where the second lane TL2 branches from the first lane TL1, the trajectory generation unit 34a starts generating a target travel trajectory based on the link shape of the high-precision map information.

[0070] The vehicle control unit 34b may also control the vehicle behavior control device 19 to travel along a target travel trajectory generated based on the recognition result of the lane boundary line of the sensor 11 before the host vehicle 1 reaches a location that is a second predetermined distance L2 (<L1) closer to the branch start point Ps. After passing through the location that is a second predetermined distance L2 closer to the branch start point Ps, the vehicle behavior control device 19 may be controlled to travel along a target travel trajectory generated based on the link shape of the high-precision map information. That is, at the moment when the host vehicle 1 reaches a location that is a second predetermined distance L2 closer to the branch start point Ps, the target travel trajectory for autonomous steering control may be switched from the target travel trajectory generated based on the recognition result of the lane boundary line of the sensor 11 to the target travel trajectory generated based on the link shape of the high-precision map information.

[0071] When the host vehicle 1 reaches a location that is a first predetermined distance L1 closer to the branch start point Ps, the trajectory generation unit 34a calculates the reference Figure 4 shortest route trajectory ST1 described above. That is, the shortest route trajectory ST1 connecting the node ND1 where the second link LK2 representing the lane shape of the second lane TL2 on the second road R2 branches from the first links LK11 and LK12 representing the lane shape of the first lane TL1 on the first road R1, and the link composition point CP1 on the second link LK2 that is a predetermined distance away from the node ND1 along the second link LK2 is calculated.

[0072] Next, the trajectory generation unit 34a determines whether the shortest route trajectory ST1 should be corrected.

[0073] For example Figure 6As shown, if the first link LK12 and the second link LK2 bend in the same direction (i.e., the first lane TL1 and the second lane TL2 bend in the same direction), then the shortest route trajectory ST1 sometimes becomes a trajectory that crosses the first link LK12. If the vehicle 1 travels along the target travel trajectory generated based on such a shortest route trajectory ST1, the vehicle 1 will temporarily move laterally in the opposite direction to the branch direction of the second lane TL2, which may cause discomfort to the occupants.

[0074] Therefore, the trajectory generation unit 34a determines whether the shortest route trajectory ST1 crosses the first link LK12. If the shortest route trajectory ST1 does not cross the first link LK12, the trajectory generation unit 34a does not modify the shortest route trajectory ST1.

[0075] When the shortest path trajectory ST1 crosses the first link LK12, the trajectory generation unit 34a calculates the trajectory of the link constituting point CP1 and node ND1, which is the intersection of the tangent of the first link LK11 and LK12 at node ND1 and the second link LK2, as the corrected shortest path trajectory ST2. When the intersection of the tangent of the first link LK11 and LK12 at node ND1 and the second link LK2 is another node ND2, the corrected shortest path trajectory ST2 connecting node ND1 and node ND2 can be calculated.

[0076] Next, the trajectory generation unit 34a determines whether to generate the target driving trajectory based on the shortest route trajectory ST1 or the modified shortest route trajectory ST2.

[0077] For example, if the curvature change of the second link LK2 (i.e., the curvature change of the second lane TL2) is small, if vehicle 1 travels along the target trajectory based on the shortest route trajectory ST1 or the modified shortest route trajectory ST2, the movement from the first road R1 to the second road R2 will be slower, which may cause discomfort to the occupants.

[0078] Therefore, the trajectory generation unit 34a calculates the curvature difference between the curvature of the first link LK11 and the curvature of the second link LK12 (i.e., the curvature difference between the curvature of the first lane TL1 and the curvature of the second lane TL2). If the curvature difference is above a predetermined threshold, a target driving trajectory is generated based on the shortest route trajectory ST1 or the modified shortest route trajectory ST2. In this case, if the shortest route trajectory ST1 is a trajectory that crosses the first link LK12, the target driving trajectory is generated based on the modified shortest route trajectory ST2; if the shortest route trajectory ST1 is a trajectory that does not cross the first link LK12, the target driving trajectory is generated based on the shortest route trajectory ST1.

[0079] When the curvature difference is less than a specified threshold, the trajectory generation unit 34a generates the target driving trajectory based on the shape of the second link LK2.

[0080] Additionally, for example, the shortest route trajectory ST1 or the modified shortest route trajectory ST2 may become the trajectory by which vehicle 1 extends beyond the second lane TL2. That is, when vehicle 1 is traveling along the target travel trajectory based on the shortest route trajectory ST1 or the modified shortest route trajectory ST2, vehicle 1 may exceed the lane boundary of the second lane TL2 on the opposite side of the first lane TL1.

[0081] exist Figure 7 In the example of the shortest route trajectory ST1, within interval S, the shortest route trajectory ST1 passes a position further away from the first link LK12 than the second link LK12. Therefore, when traveling along the shortest route trajectory ST1, within interval S, vehicle 1 may cross the lane boundary of the second lane TL2 on the opposite side of the first lane TL1.

[0082] Therefore, when the shortest route trajectory ST1 is a trajectory that does not cross the first link LK12, when the vehicle 1 travels along the target travel trajectory based on the shortest route trajectory ST1, the trajectory generation unit 34a determines whether the vehicle 1 has exceeded the lane boundary of the second lane TL2 on the opposite side of the first lane TL1. When the shortest route trajectory ST1 is a trajectory that crosses the first link LK12, when the vehicle 1 travels along the target travel trajectory based on the modified shortest route trajectory ST2, it determines whether the vehicle 1 has exceeded the lane boundary of the second lane TL2 on the opposite side of the first lane TL1.

[0083] When the vehicle 1 travels along the target travel trajectory based on the shortest route trajectory ST1 or the modified shortest route trajectory ST2, if it is determined that the vehicle 1 has exceeded the lane boundary on the opposite side of the first lane TL1 in the lane boundary of the second lane TL2, the trajectory generation unit 34a generates the target travel trajectory based on the shape of the second link LK2.

[0084] If the shortest route trajectory ST1 is a trajectory that does not cross the first link LK12, and even if vehicle 1 travels along the target travel trajectory based on the shortest route trajectory ST1, vehicle 1 does not exceed the lane boundary of the second lane TL2 on the opposite side of the first lane TL1, then the trajectory generation unit 34a generates the target travel trajectory based on the shortest route trajectory ST1. If the shortest route trajectory ST1 is a trajectory that crosses the first link LK12, and even if vehicle 1 travels along the target travel trajectory based on the modified shortest route trajectory ST2, vehicle 1 does not exceed the lane boundary of the second lane TL2 on the opposite side of the first lane TL1, then the trajectory generation unit 34a generates the target travel trajectory based on the modified shortest route trajectory ST1.

[0085] (action)

[0086] Figure 8 This is a flowchart of an example of a vehicle driving control method implemented in this way.

[0087] In step S1, the trajectory generation unit 34a determines whether the target driving path of the vehicle 1 is a path leading to a branch road. If the target driving path is a path leading to a branch road (step S1: Yes (Y)), the process proceeds to step S3. If the target driving path is not a path leading to a branch road (step S1: No (N)), the process proceeds to step S2.

[0088] In step S2, the trajectory generation unit 34a generates a target driving trajectory based on the lane boundary line recognition result based on sensor information from sensor 11. The vehicle control unit 34b controls the vehicle behavior control device 19 to make the vehicle 1 drive along the target driving trajectory generated by the trajectory generation unit 34b. Then the process ends.

[0089] In step S3, the trajectory generation unit 34a calculates the shortest route trajectory ST1 between node ND1, which branches from the first links LK11 and LK12 of the second link LK2, and a point on the second link LK2 that is only a specified distance away from node ND1 along the second link LK2.

[0090] In step S4, the trajectory generation unit 34a determines whether the shortest route trajectory ST1 crosses the first link LK12. If the shortest route trajectory ST1 crosses the first link LK12 (step S4: Yes), the process proceeds to step S5. If the shortest route trajectory ST1 does not cross the first link LK12 (step S4: No), the process proceeds to step S6.

[0091] In step S5, the trajectory generation unit 34a calculates the intersection of the tangents of the first links LK11 and LK12 at node ND1 with the second link LK2, and the trajectory of node ND1, as the corrected shortest route trajectory ST2. Then, the process proceeds to step S6.

[0092] In step S6, the trajectory generation unit 34a determines whether the curvature difference between the curvature of the first lane TL and the curvature of the second lane TL2 is greater than or equal to a threshold. If the curvature difference is greater than or equal to the threshold (step S6: Yes), the process proceeds to step S7. If the curvature difference is not greater than or equal to the threshold (step S6: No), the process proceeds to step S9.

[0093] In step S7, when vehicle 1 travels along the target trajectory based on the shortest route trajectory ST1 (or the corrected shortest route trajectory ST2 if a corrected shortest route trajectory ST2 is calculated), the trajectory generation unit 34a determines whether vehicle 1 has exceeded the lane boundary of the second lane TL2 on the opposite side of the first lane TL1. If vehicle 1 has exceeded the lane boundary (step S7: Yes), the process proceeds to step S9. If vehicle 1 has not exceeded the lane boundary (step S7: No), the process proceeds to step S8.

[0094] In step S8, the trajectory generation unit 34a generates a target driving trajectory based on the shortest route trajectory ST1 (or the corrected shortest route trajectory ST2 if a corrected shortest route trajectory ST2 is calculated). The vehicle control unit 34b controls the vehicle behavior control device 19 to make the vehicle 1 drive along the target driving trajectory generated by the trajectory generation unit 34b. Then the process ends.

[0095] In step S9, the trajectory generation unit 34a generates a target driving trajectory based on the link shape of the second link LK2. The vehicle control unit 34b controls the vehicle behavior control device 19 to make the vehicle 1 drive along the target driving trajectory generated by the trajectory generation unit 34b. Then the process ends.

[0096] (Effects of the implementation method)

[0097] (1) The controller 20, based on map information representing the lane shape by nodes and links, makes the vehicle 1 travel along the lane by automatic steering. The controller 20 performs the following processes: determining whether the target travel path of the vehicle 1 traveling on the first road is a path that enters the second road branching from the first road ahead of the vehicle 1; if the target travel path is a path that enters the second road, calculating the first trajectory connecting the link representing the lane shape of the second lane on the second road (i.e., the branch point of the link representing the lane shape of the first lane on the first road, i.e., the branch point of the link representing the lane shape of the first lane on the first road), and the point on the second link that leaves the branch point by only a specified distance along the second link, and setting the target travel trajectory based on the first trajectory; and controlling the vehicle 1 to travel along the target travel trajectory.

[0098] Therefore, compared to the curvature change when the target trajectory is generated based on the shape of the second link, the curvature change of the target trajectory based on the first trajectory can be reduced, thus suppressing abrupt steering. As a result, discomfort to the occupants can be reduced.

[0099] (2) The controller 20 determines whether the first trajectory crosses the first link. If the first trajectory does not cross the first link, the target driving trajectory is set based on the first trajectory. If the first trajectory crosses the first link, the target driving trajectory can also be set based on the intersection of the tangent of the first link at the branch point and the second link and the second trajectory at the branch point.

[0100] Therefore, when the vehicle 1 travels along the target travel trajectory based on the first trajectory, it is possible to suppress the discomfort of the occupants caused by the lateral movement of the vehicle 1 in the direction opposite to the branch direction of the second lane.

[0101] (3) The controller 20 can control the vehicle 1 to travel along the target driving trajectory when the curvature difference between the curvature of the first lane and the curvature of the second lane is above a predetermined threshold, and control the vehicle 1 to travel along the driving trajectory generated based on the second link when the curvature difference is less than the threshold.

[0102] Therefore, it is possible to suppress the discomfort of the occupants caused by the slowing of movement from the first road R1 to the second road R2 when the vehicle 1 is traveling along a target travel trajectory based on the first trajectory or the second trajectory.

[0103] (4) When the controller 20 is traveling along the target driving trajectory, it can presume whether the vehicle 1 has exceeded the lane boundary of the second lane on the opposite side of the first lane. If it is presumed that the vehicle 1 has exceeded the lane boundary, it can control the vehicle 1 to travel along the driving trajectory generated based on the second link.

[0104] Therefore, when the vehicle 1 is traveling along a target travel trajectory based on the first trajectory or the second trajectory, it is possible to prevent the vehicle 1 from going beyond the second lane to the side opposite to the first lane.

[0105] All examples and conditional terms recorded herein are intended for illustrative purposes to aid the reader's understanding of the invention and the concepts provided by the inventors for technological advancement, and should not be construed as limiting to the specific examples and conditions described above and the structures of the examples in this specification relating to the superiority and inferiority of the invention. While embodiments of the invention have been described in detail, it should be understood that various changes, substitutions, and modifications can be made thereto without departing from the spirit and scope of the invention.

[0106] Symbol Explanation

[0107] 1: This vehicle; 10: Driving assistance device; 11: Sensor; 12: Positioning device; 13: Map database; 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 vehicle driving control method, based on map information representing lane shapes by nodes and links, using automatic steering to make the vehicle travel along the lane, characterized in that, The controller should perform the following processing: The process of determining whether the target travel path of the vehicle traveling on the first road is a path that enters the second road branching off from the first road in front of the vehicle; In the case that the target driving path is a path to the second road, the process of determining the point on the second link that leaves the branch point of the link representing the lane shape of the second lane on the second road, i.e. the second link, from the branch point of the link representing the lane shape of the first lane on the first road, i.e. the first link, is to be determined along the second link by a specified distance from the branch point. The process of calculating a first trajectory connecting the branch point and the points on the determined second link, and setting a target driving trajectory based on the first trajectory; The vehicle is controlled to travel along the target trajectory. The controller performs the following processing: Determine whether the first trajectory crosses the first link. If the first trajectory does not cross the first link, the target driving trajectory is set based on the first trajectory. When the first trajectory crosses the first link, the target driving trajectory is set based on the intersection of the tangent of the first link at the branch point and the second link, and the second trajectory of the branch point.

2. The vehicle driving control method as described in claim 1, characterized in that, The controller performs the following processing: When the curvature difference between the curvature of the first lane and the curvature of the second lane is above a predetermined threshold, the vehicle is controlled to travel along the target driving trajectory. When the curvature difference is less than the threshold, the vehicle is controlled to travel along a driving trajectory generated based on the second link.

3. The vehicle driving control method as described in claim 1 or 2, characterized in that, The controller performs the following processing: When traveling along the target trajectory, it is presumed whether the vehicle has exceeded the lane boundary of the second lane on the opposite side of the first lane. If it is presumed that the vehicle has exceeded the lane boundary, the vehicle is controlled to travel along a driving trajectory generated based on the second link.

4. A vehicle driving control device, based on map information representing lane shapes by nodes and links, enables a vehicle to travel along a lane via automatic steering, characterized in that, The system includes a controller that performs the following processing: The process of determining whether the target travel path of the vehicle traveling on the first road is a path that enters the second road branching off from the first road in front of the vehicle; In the case that the target driving path is a path to the second road, the process of determining the point on the second link that leaves the branch point of the link representing the lane shape of the second lane on the second road, i.e. the second link, from the branch point of the link representing the lane shape of the first lane on the first road, i.e. the first link, is to be determined along the second link by a specified distance from the branch point. The process of calculating a first trajectory connecting the branch point and the points on the determined second link, and setting a target driving trajectory based on the first trajectory; The vehicle is controlled to travel along the target trajectory. The controller performs the following processing: Determine whether the first trajectory crosses the first link. If the first trajectory does not cross the first link, the target driving trajectory is set based on the first trajectory. When the first trajectory crosses the first link, the target driving trajectory is set based on the intersection of the tangent of the first link at the branch point and the second link, and the second trajectory of the branch point.

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