Driving assistance method and driving assistance device

Abstract

To provide a driving support method and a driving support device 19 which can suppress a vehicle V2 following an own vehicle V1 from overtaking the own vehicle V1 in an intersection C and entering the front of the own vehicle V1.SOLUTION: A driving support device memorizes, as a travel track on which a vehicle turns left at an intersection C, a predetermined first turning track T1 and a second turning track T2 on which the vehicle travels on a lane closer to the inside than the first turning track T1; when an own vehicle V1 turns left at the intersection C, determines whether a vehicle V2 following the own vehicle turns left or not at the intersection C; and when determining that the vehicle V2 turns left at the intersection C, makes the own vehicle V1 travel along the second turning track T2.SELECTED DRAWING: Figure 2C

Description

[Technical Field]

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

[0002] A vehicle control system is known that acquires a planned driving route for a vehicle, acquires a recommended area in which the vehicle should drive among intersections included in the planned driving route, and causes the vehicle to drive in the recommended area when driving through the intersection (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2019-131371 Summary of the Invention [Problem to be solved by the invention]

[0004] Consider a scenario in which a vehicle turns left at an intersection onto a two-lane road, and another vehicle is parked in the left lane of the road after the left turn. In this scenario, with the conventional technology, the vehicle travels within the recommended area and enters the right lane of the road after the left turn to avoid having to change lanes after the left turn. In this case, a vehicle following the vehicle may travel in the space created on the left side of the vehicle and attempt to overtake the vehicle in the intersection and enter ahead of the vehicle.

[0005] The following vehicle travels in an area inside the recommended area to overtake the host vehicle at the intersection. However, in the above-mentioned conventional technology, only one recommended area is set for each combination of a lane entering the intersection and a lane exiting the intersection, so the host vehicle does not travel in an area inside the recommended area. In other words, the above-mentioned conventional technology has a problem in that it cannot prevent the following vehicle traveling in an area inside the recommended area from overtaking.

[0006] The problem that the present invention aims to solve is to provide a driving assistance method and a driving assistance device that can prevent a following vehicle from overtaking the vehicle at an intersection and entering in front of the vehicle. [Means for solving the problem]

[0007] In the present invention, the travel path for turning left at an intersection is as follows: For one combination of the lane through which the vehicle enters the intersection and the lane through which the vehicle exits the intersection, a predetermined first turning trajectory; To prevent any space on the left side of your vehicle for the vehicle following your vehicle to enter Turn inside the first turning trajectory , for one combination The first turning locus and the second turning locus are stored, and when the vehicle turns left at an intersection, it is determined whether the following vehicle will turn left at the intersection, and when it is determined that the following vehicle will turn left at the intersection, the vehicle is made to travel along the second turning locus, thereby solving the above problem. [Effects of the Invention]

[0008] According to the present invention, it is possible to prevent a vehicle following the host vehicle from overtaking the host vehicle and entering in front of the host vehicle at an intersection. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing a driving assistance system including a driving assistance device according to the present invention. [Figure 2A] 2 is a plan view (part 1) showing an example of a driving scene in which driving assistance is performed by the driving assistance system shown in FIG. 1. FIG. [Figure 2B] 2 is a plan view showing an example of a driving scene in which driving assistance is performed by the driving assistance system shown in FIG. 1 (part 2). FIG. [Figure 2C] 3 is a plan view showing an example of a driving scene in which driving assistance is performed by the driving assistance system shown in FIG. 1 (part 3). FIG. [Figure 3A] 1. FIG. 4 is a plan view (part 1) showing another example of a driving scene in which driving assistance is performed by the driving assistance system shown in FIG. [Figure 3B] 1. FIG. 4 is a plan view (part 2) showing another example of a driving scene in which driving assistance is performed by the driving assistance system shown in FIG. [Figure 4A] 2 is a flowchart showing an example of a processing procedure in the driving assistance system of FIG. 1 (part 1). [Figure 4B] 2 is a flowchart showing an example of a processing procedure in the driving assistance system of FIG. 1 (part 2). [Figure 5] 10 is a flowchart showing another example of the processing procedure in the driving assistance system of FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description is based on the assumption that vehicles are driven on the left side of the road in countries with laws stipulating left-hand traffic. In countries with laws stipulating right-hand traffic, vehicles are driven on the right side of the road, so the left and right in the following description should be interpreted as symmetrical.

[0011] [Driver assistance system configuration] FIG. 1 is a block diagram showing a driving assistance system 10 according to the present invention. The driving assistance system 10 is an in-vehicle system that drives a vehicle to a destination set by the vehicle's occupants (including the driver) through autonomous driving control. Autonomous driving control refers to autonomously controlling the vehicle's driving behavior using a driving assistance device (described later), and the driving behavior includes all driving behaviors such as acceleration, deceleration, starting, stopping, steering to the right or left, changing lanes, and pulling over. Furthermore, autonomously controlling driving behavior refers to the driving assistance device controlling the driving behavior using a device in the vehicle. In other words, the driving assistance device intervenes in and controls these driving behaviors within a predetermined range. Driving behaviors that are not intervened in are manually controlled by the driver.

[0012] 1, a driving assistance system 10 includes an imaging device 11, a distance measuring device 12, a state detection device 13, map information 14, a position detection device 15, a navigation device 16, a vehicle control device 17, a display device 18, and a driving assistance device 19. The devices that make up the driving assistance system 10 are connected by a CAN (Controller Area Network) or other in-vehicle LAN, and can exchange information with each other.

[0013] The imaging device 11 is a device that recognizes objects around the vehicle using images, and is, for example, a camera equipped with an imaging element such as a CCD, an ultrasonic camera, or an infrared camera. A single vehicle can be provided with multiple imaging devices 11, and they can be located, for example, near the front grille, under the left and right door mirrors, and near the rear bumper. This reduces blind spots when recognizing objects around the vehicle.

[0014] The distance measuring device 12 is a device for calculating the relative distance and relative speed between the vehicle and an object, and is, for example, a radar device or sonar such as a laser radar, a millimeter wave radar (such as LRF), a LiDAR (light detection and ranging) unit, or an ultrasonic radar. A plurality of distance measuring devices 12 can be provided on one vehicle, and can be arranged, for example, at the front, right side, left side, and rear of the vehicle. This allows the relative distance and relative speed between the vehicle and objects around it to be accurately calculated.

[0015] The objects detected by the imaging device 11 and the distance measuring device 12 include road lane boundaries, center lines, road markings, medians, guardrails, curbs, highway sidewalls, road signs, traffic lights, crosswalks, construction sites, accident sites, traffic restrictions, etc. The objects also include obstacles that may affect the vehicle's travel, such as automobiles (other vehicles) other than the vehicle itself, motorcycles, bicycles, pedestrians, etc. The detection results of the imaging device 11 and the distance measuring device 12 are acquired by the driving assistance device 19 at predetermined time intervals as necessary.

[0016] Furthermore, the detection results of the imaging device 11 and the distance measuring device 12 can be integrated or synthesized (so-called sensor fusion) by the driving assistance device 19, thereby supplementing missing information about the detected object. For example, the driving assistance device 19 can calculate the position information of the object based on the self-position information, which is the position where the vehicle is traveling, acquired by the position detection device 15, and the relative position (distance and direction) between the vehicle and the object. The calculated position information of the object is integrated by the driving assistance device 19 with multiple pieces of information, such as the detection results of the imaging device 11 and the distance measuring device 12 and the map information 14, to become information about the driving environment around the vehicle. Furthermore, the detection results of the imaging device 11 and the distance measuring device 12 and the map information 14 can be used to recognize objects around the vehicle and predict their movements.

[0017] The state detection device 13 is a device for detecting the running state of the vehicle, and examples thereof include a vehicle speed sensor, an acceleration sensor, a yaw rate sensor (e.g., a gyro sensor), a steering angle sensor, and an inertial measurement unit. There are no particular limitations on these devices, and known devices can be used. The locations and numbers of these devices can be set appropriately within a range that allows appropriate detection of the running state of the vehicle. The detection results of each device are acquired by the driving assistance device 19 at predetermined time intervals as necessary.

[0018] Map information 14 is information used for generating driving routes, controlling driving operations, etc., and includes road information, facility information, and their attribute information. Road information and road attribute information include information such as road width, road curvature radius, road shoulder structures, road traffic regulations (speed limit, whether lane changes are permitted), road merging and branching points, and locations where the number of lanes increases or decreases. Map information 14 is high-resolution map information that allows the movement trajectory of each lane to be grasped, and includes two-dimensional position information and / or three-dimensional position information at each map coordinate, road / lane boundary information at each map coordinate, road attribute information, lane incline / decline information, lane identification information, connecting lane information, etc.

[0019] Road and lane boundary information in high-resolution map information is information that indicates the boundaries between the lane on which a vehicle travels and other roads. A lane on which a vehicle travels is a road along which the vehicle travels, and the form of the lane is not particularly limited. Boundaries exist on both the left and right sides of the vehicle's direction of travel, and the form is not particularly limited. Boundaries are, for example, road markings or road structures. Examples of road markings include lane boundaries and center lines, and examples of road structures include medians, guardrails, curbs, tunnels, and highway sidewalls. Note that at points where lane boundaries cannot be clearly identified, such as within intersections, boundaries are set for the lane in advance. These boundaries are imaginary and are not actually existing road markings or road structures.

[0020] The map information 14 is stored in a readable state in a recording medium provided in the driving assistance device 19, an in-vehicle device, or a server on a network. The driving assistance device 19 acquires the map information 14 as needed.

[0021] The position detection device 15 is a positioning system for detecting the current position of the vehicle, and is not particularly limited, and any known system can be used. The position detection device 15 calculates the current position of the vehicle, for example, from radio waves received from a satellite for the GPS (Global Positioning System). Alternatively, the position detection device 15 may estimate the current position of the vehicle from vehicle speed information and acceleration information acquired from the state detection device 13, which includes a vehicle speed sensor, an acceleration sensor, and a gyro sensor, and compare the estimated current position with the map information 14 to calculate the current position of the vehicle.

[0022] The navigation device 16 is a device that refers to map information 14 and calculates a driving route from the current position of the vehicle detected by the position detection device 15 to a destination set by the occupants (including the driver). The navigation device 16 searches for a driving route for the vehicle to reach the destination from the current position using road information, facility information, etc. in the map information 14. The driving route includes at least information on the road on which the vehicle is traveling, the driving lane, and the vehicle's traveling direction, and is displayed, for example, as a linear diagram. There may be multiple driving routes depending on the search conditions. The driving route calculated by the navigation device 16 is output to the driving assistance device 19.

[0023] The vehicle control device 17 is an on-board computer such as an electronic control unit (ECU), and electronically controls on-board devices that govern the driving of the vehicle. The vehicle control device 17 includes a vehicle speed control device 171 that controls the driving speed of the vehicle, and a steering control device 172 that controls the steering operation of the vehicle. The vehicle speed control device 171 and the steering control device 172 autonomously control the operation of these drive devices and steering devices in response to control signals input from the driving assistance device 19. This allows the vehicle to drive autonomously along a set driving route. Information required for autonomous control by the vehicle speed control device 171 and the steering control device 172, such as the vehicle's driving speed, acceleration, steering angle, and attitude, is obtained from the state detection device 13.

[0024] Examples of the drive devices controlled by the vehicle speed control device 171 include an electric motor and / or an internal combustion engine as a driving source for traveling, a power transmission device including a drive shaft and an automatic transmission that transmits the output from these driving sources for traveling to the driving wheels, and a drive device that controls the power transmission device. In addition, the braking device controlled by the vehicle speed control device 171 is, for example, a braking device that brakes the wheels. A control signal corresponding to a set traveling speed is input to the vehicle speed control device 171 from the driving assistance device 19. The vehicle speed control device 171 generates signals to control these drive devices based on the control signals input from the driving assistance device 19 and transmits the signals to the drive devices, thereby autonomously controlling the traveling speed of the vehicle.

[0025] On the other hand, the steering device controlled by the steering control device 172 is a steering device that controls the steered wheels according to the steering angle of the steering wheel, and an example of this is a steering actuator such as a motor attached to a steering column shaft. Based on a control signal input from the driving assistance device 19, the steering control device 172 autonomously controls the operation of the steering device so that the vehicle travels while maintaining a predetermined lateral position (position of the vehicle in the left-right direction) with respect to the set travel route. For this control, at least one of the detection results of the imaging device 11 and the distance measuring device 12, the vehicle travel state acquired by the state detection device 13, and information on the map information 14 and the current position of the vehicle acquired by the position detection device 15 is used.

[0026] The display device 18 is a device for providing necessary information to vehicle occupants, and is, for example, a liquid crystal display provided on the instrument panel, a projector such as a head-up display (HUD), etc. The display device 18 may also include an input device for the vehicle occupant to input instructions to the driving assistance device 19. Examples of the input device include a touch panel that receives input by the user's finger or a stylus pen, a microphone that receives instructions by the user's voice, and switches attached to the steering wheel of the vehicle. The display device 18 may also include a speaker as an output device.

[0027] The driving assistance device 19 is a device that controls the driving of the vehicle by controlling and cooperating with the devices that make up the driving assistance system 10, and drives the vehicle to a set destination. The destination is set, for example, by a vehicle occupant. The driving assistance device 19 is, for example, a computer, and includes a CPU (Central Processing Unit) 191 that is a processor, a ROM (Read Only Memory) 192 that stores programs, and a RAM (Random Access Memory) 193 that functions as an accessible storage device. The CPU 191 is an operating circuit that executes the programs stored in the ROM 192 and realizes the functions of the driving assistance device 19.

[0028] The driving assistance device 19 has a driving assistance function of driving the vehicle to a set destination by autonomous driving control. The driving assistance functions of the driving assistance device 19 include a driving environment recognition function of recognizing the driving environment around the vehicle, a determination function of determining whether the vehicle needs to turn left, a storage function of storing a driving trajectory for driving through an intersection, a driving control function of driving the vehicle along the driving trajectory, and a risk calculation function of calculating the risk of following vehicles and oncoming vehicles to the vehicle. The programs stored in the ROM 192 include programs for realizing these functions, and the CPU 191 executes the programs stored in the ROM 192 to realize these functions. FIG. 1 conveniently illustrates each function extracted as a functional block.

[0029] [Function block function] Hereinafter, the functions realized by the functional blocks of the support unit 20, the recognition unit 21, the determination unit 22, the storage unit 23, the control unit 24, and the calculation unit 25 will be described with reference to FIGS. 2A to 2C.

[0030] The assistance unit 20 has a function of driving the vehicle to a set destination by autonomous driving control (i.e., a driving assistance function). Fig. 2A is a plan view showing an example of a driving scene in which the driving assistance device 19 autonomously controls the driving of the host vehicle V1 by the driving assistance function of the assistance unit 20. In the driving scene shown in Fig. 2A, a road with two lanes on each side extends in the vertical and horizontal directions of the drawing, and an intersection C is formed where the two roads intersect. On the road extending in the vertical direction of the drawing, vehicles traveling on lanes L1 and L6 can turn left or go straight at the intersection C, and vehicles traveling on lanes L2 and L5 can turn right or go straight at the intersection C.

[0031] In the driving scene shown in FIG. 2A, the host vehicle V1 is traveling at position P1 on lane L1, and a following vehicle V2 of the host vehicle V1 is traveling at position P2 behind the host vehicle V1. Also, an oncoming vehicle V3 of the host vehicle V1 is traveling at position P3 within intersection C. Furthermore, a parked vehicle Vx is parked at position Px on lane L3. In this embodiment, a vehicle traveling in the same lane as the host vehicle V1 and traveling at a position behind the host vehicle V1 is referred to as a following vehicle, and a vehicle traveling in an oncoming lane traveling in the opposite direction to the lane in which the host vehicle V1 is traveling is referred to as an oncoming vehicle. In this driving scene, the host vehicle V1 turns left at intersection C to travel along a set driving route.

[0032] In this case, when the host vehicle V1 turns left at the intersection C, it can enter either the left lane L3 or the right lane L4. Whether the host vehicle V1 enters the left or right lane L4 is determined based on the driving environment of the host vehicle V1. In the driving scene shown in FIG. 2A , a parked vehicle Vx is parked at position Px on lane L3. Therefore, when the host vehicle V1 turns left at the intersection C and enters lane L3, the host vehicle V1 must avoid the parked vehicle Vx to continue driving. Therefore, the host vehicle V1 will overtake the parked vehicle Vx or change lanes from lane L3 to lane L4. Such overtaking and lane changes performed near the intersection C after exiting the intersection C can hinder the driving of the following vehicle V2 and the like. Therefore, to ensure smooth traffic around the intersection C, in the driving scene shown in FIG. 2A , the driving assistance device 19 sets lane L4 as the lane to enter after turning left at the intersection C.

[0033] When the host vehicle V1 turns left at the intersection C and enters the lane L4, the driving assistance device 19, using the driving assistance function, causes the host vehicle V1 to travel, for example, along a first turning trajectory T1, which is a predetermined turning path shown in FIG. 2A. When the host vehicle V1 travels along the first turning trajectory T1, the distance from when the host vehicle V1 enters the intersection C to when it starts turning is relatively long. Therefore, when the following vehicle V2 turns left at the intersection C, a space for the following vehicle V2 to enter may be created on the left side of the host vehicle V1. For example, as shown in FIG. 2B, when the host vehicle V1 travels along the first turning trajectory T1 and reaches a position P4, a space for the following vehicle V2 to enter may be created on the left side of the host vehicle V1. In this case, the following vehicle V2 turning left at the intersection C may travel along the travel trajectory Ta from a position P2 to a position P5 on the left side of the host vehicle V1 and enter the space on the left side of the host vehicle V1. Furthermore, the following vehicle V2 may travel along the travel trajectory Tb from position P5 to position P6, change lanes from lane L3 to lane L4, and enter (cut in) ahead of the host vehicle V1.

[0034] In this way, if the following vehicle V2 overtakes the host vehicle V1 at the intersection C and then enters in front of the host vehicle V1 (cuts in) when exiting the intersection C, this may result in the host vehicle V1 suddenly stopping. As a result, the occupants of the host vehicle V1 may feel discomfort and anxiety due to the significant change in the behavior of the host vehicle V1. Therefore, the driving assistance device 19 of this embodiment autonomously controls the traveling of the host vehicle V1 using a turning trajectory different from the first turning trajectory T1 in order to suppress the following vehicle V2 from overtaking and cutting in within the intersection C. This control is mainly realized by the functions of the recognition unit 21, the determination unit 22, the storage unit 23, the control unit 24, and the calculation unit 25.

[0035] The recognition unit 21 has a function of detecting objects around the host vehicle V1 and recognizing the driving environment of the host vehicle V1 (i.e., a driving environment recognition function). Objects include boundaries and signs of the road on which the host vehicle V1 is traveling, as well as obstacles that affect the driving of the host vehicle V1. Specifically, as described above, examples of such objects include lane boundaries, center lines, signs, medians, guardrails, curbs, side walls, traffic lights, crosswalks, other vehicles, motorcycles, bicycles, pedestrians, and the like. The driving assistance device 19 detects these objects using the imaging device 11 and the distance measuring device 12, and based on the detection results, recognizes the positions of obstacles around the host vehicle V1 and the conditions of the road on which the host vehicle V1 is traveling as the driving environment around the host vehicle V1.

[0036] Furthermore, the driving assistance device 19 acquires the current position of the vehicle V1 from the position detection device 15 using the driving environment recognition function of the recognition unit 21, and acquires the driving route set by the occupant of the vehicle V1 or the like from the navigation device 16. Furthermore, the driving assistance device 19 acquires road information, facility information, and attribute information thereof around the current position of the vehicle V1 from the map information 14. Specifically, from the road information and facility information, it acquires positions where lane closure is likely to occur after turning left or right at an intersection C. For example, it accumulates detection results so far and acquires positions where there is a high probability that a parked vehicle Vx will be present after turning left or right at the intersection C, positions where there is a high probability that construction work will be carried out around the intersection C, positions where the number of lanes will decrease after turning left or right at the intersection C, and the like.

[0037] In the driving scene shown in FIG. 2A, the driving assistance device 19 detects a following vehicle V2 traveling at position P2, an oncoming vehicle V3 traveling at position P3, and a parked vehicle Vx parked at position Px using the driving environment recognition function of the recognition unit 21, and recognizes each vehicle as an obstacle. In addition, the driving assistance device 19 detects a vehicle traveling parallel to the lane L2 adjacent to the lane L1 in which the host vehicle V1 is traveling. These vehicles are detected, for example, by performing known processing such as pattern matching on the detection results of the imaging device 11 and the distance measuring device 12. In addition, the driving assistance device 19 detects the lighting status of traffic lights installed at the intersection C (specifically, whether the lighting status of the traffic lights indicates a stop). The driving assistance device 19 integrates these detection results to recognize the driving environment of the host vehicle V1.

[0038] The driving assistance device 19 detects surrounding obstacles (for example, a following vehicle V2, an oncoming vehicle V3, and a parked vehicle Vx) when the vehicle V1 turns left or right at an intersection C, but this is not limited to this.

[0039] The determination unit 22 has a function (i.e., a determination function) of determining whether or not the host vehicle V1 needs to turn left in order to travel along the travel route. The driving assistance device 19 determines, by the determination function of the determination unit 22, whether or not the host vehicle V1 needs to turn left at an intersection C, based on the travel environment of the host vehicle V1 recognized by the travel environment recognition function of the recognition unit 21. For example, if the current position of the host vehicle V1 is acquired and a route is set to turn left at an intersection C located ahead of the current position of the host vehicle V1, the driving assistance device 19 determines that the host vehicle V1 needs to turn left at the intersection C. On the other hand, if a route is set to turn right or go straight at the intersection C located ahead of the current position of the host vehicle V1, the driving assistance device 19 determines that the host vehicle V1 does not need to turn left at the intersection C.

[0040] In addition, if the road on which the host vehicle V1 travels after turning left at intersection C is a road with two or more lanes on each side, the driving assistance device 19 uses the determination function of the determination unit 22 to determine whether or not to set the right lane as the exit lane for intersection C. For example, if it is recognized from the driving environment of the host vehicle V1 recognized by the driving environment recognition function of the recognition unit 21 that there is a high probability that a parked vehicle Vx will be present in the left lane of the road after turning left at intersection C, or if it is recognized that the left lane of the road after turning left at intersection C will merge into the right lane by the next intersection, the driving assistance device 19 determines to set the right lane as the exit lane for intersection C. On the other hand, if it is recognized that there is a high probability that the right lane of the road after turning left at intersection C will be a construction section, the driving assistance device 19 determines to set the left lane as the exit lane for intersection C.

[0041] In addition, when the driving assistance device 19 detects the following vehicle V2, it determines whether the following vehicle V2 will turn left at the intersection C using the determination function of the determination unit 22. Specifically, the driving assistance device 19 detects the flashing state of the left turn signal of the following vehicle V2 from the image acquired by the imaging device 11, and determines whether the following vehicle V2 is flashing the left turn signal. If the following vehicle V2 is flashing the left turn signal, it determines that the following vehicle V2 will turn left, and if the following vehicle V2 is not flashing the turn signal, it determines that the following vehicle V2 will not turn left. Alternatively or in addition to this, the driving assistance device 19 detects the vehicle attitude of the following vehicle V2 from the detection results of the imaging device 11 and the distance measuring device 12, and determines whether the following vehicle V2 is steering to the left. If the following vehicle V2 is steering to the left, it is determined that the following vehicle V2 will turn left, and if the following vehicle V2 is not steering to the left, it is determined that the following vehicle V2 will not turn left.

[0042] In addition, when an oncoming vehicle V3 is detected, the driving assistance device 19 determines, using the determination function of the determination unit 22, whether or not the oncoming vehicle V3 will turn right at the intersection C. The specific determination method is the same as that for determining whether or not the following vehicle V2 will turn left. That is, the driving assistance device 19 determines whether or not the oncoming vehicle V3 will turn right based on the flashing state of the turn signal on the right side of the oncoming vehicle V3 and / or the vehicle posture of the oncoming vehicle V3. Note that the determination of whether or not the oncoming vehicle V3 will turn right may be performed only when it is determined that the following vehicle V2 will not turn left at the intersection C. The driving assistance device 19 completes each of the above-mentioned determinations at the latest before the host vehicle V1 enters the intersection C.

[0043] The memory unit 23 has a function of storing a driving trajectory for traveling through an intersection (i.e., a storage function). The driving assistance device 19 uses the storage function of the memory unit 23 to store in advance a turning trajectory, which is a driving trajectory for turning left at an intersection C. The turning trajectory is a driving trajectory for the host vehicle V1 to enter the intersection C, turn within the intersection C, and enter a set exit lane. The turning trajectory is generated, for example, by combining a straight line for the host vehicle V1 to enter the intersection C and to exit the intersection C, and an arc for the host vehicle V1 to turn. The arc for the host vehicle V1 to turn is generated, for example, using a clothoid curve.

[0044] The driving assistance device 19 stores in advance a turning trajectory for each combination of a lane entering the intersection C and a lane exiting the intersection C. In particular, if the lane exiting the intersection C is not the leftmost lane on the road, at least two turning trajectories are stored in advance for each combination of a lane entering the intersection C and a lane exiting the intersection C. For example, the driving assistance device 19 uses the storage function of the storage unit 23 to store in advance a predetermined first turning trajectory T1 and a second turning trajectory that turns inside the first turning trajectory T1 as driving trajectories when turning left at the intersection C.

[0045] "Turning inside the first turning trajectory T1" means that the position that the host vehicle V1 passes when traveling along the second turning trajectory is closer to the turning center of the host vehicle V1 than the position that the host vehicle V1 passes when traveling along the first turning trajectory. In other words, the turning radius of the host vehicle V1 is smaller when traveling along the second turning trajectory than when traveling along the first turning trajectory. The turning center of the host vehicle V1 is, for example, the center of a circle corresponding to the arc of the traveling trajectory, and specifically, corner A of intersection C shown in FIG. 2A.

[0046] An example of the first turning trajectory T1 is shown in Fig. 2A, and an example of the second turning trajectory T2 is shown in Fig. 2C. As shown in Fig. 2C, in the second turning trajectory, the distance from when the host vehicle V1 enters the intersection C to when it starts turning is set to be shorter than that of the first turning trajectory T1. That is, in the first turning trajectory, the distance from when the host vehicle V1 enters the intersection C to when it starts turning is longer than that of the second turning trajectory T2. Furthermore, in addition to the first turning trajectory T1 and the second turning trajectory T2, the driving assistance device 19 may store a third turning trajectory that passes between the first turning trajectory T1 and the second turning trajectory T2.

[0047] These turning trajectories are stored, for example, by writing the travel trajectory data in the ROM 192. Alternatively, they may be pre-registered as road information at the position of the intersection C in the map information 14. By pre-storing a plurality of turning trajectories in this way, complex processing for generating a travel trajectory for traveling through the intersection C becomes unnecessary, and the driving assistance device 19 can control the traveling of the host vehicle V1 within the intersection C by a simple process of selecting a turning trajectory in accordance with the traveling environment around the host vehicle V1.

[0048] The control unit 24 has a function of causing the host vehicle V1 to travel along the travel trajectory (i.e., a travel control function). The driving assistance device 19 uses the travel control function of the control unit 24 to autonomously control the travel speed and steering operation of the host vehicle V1 using the vehicle control device 17 (particularly the vehicle speed control device 171 and the steering control device 172) to cause the host vehicle V1 to travel along the travel trajectory.

[0049] When the driving assistance device 19 determines through the determination function of the determination unit 22 that the following vehicle V2 will not turn left at the intersection C, it uses the driving control function of the control unit 24 to select either the first turning trajectory T1 or the second turning trajectory T2 from the stored turning trajectories, and causes the host vehicle V1 to travel along the selected turning trajectory. On the other hand, when the determination function of the determination unit 22 determines that the following vehicle V2 will turn left at the intersection C, it selects the second turning trajectory T2, and causes the host vehicle V1 to travel along the second turning trajectory T2. Note that the cases where the following vehicle V2 will not turn left at the intersection C also include cases where the following vehicle V2 is not detected.

[0050] 2C is a plan view showing an example of a driving scene in which the host vehicle V1 travels along a second turning trajectory T2 when the following vehicle V2 turns left in the driving scene shown in FIG. 2A. The second turning trajectory T2 shown in FIG. 2C is a turning trajectory in which the host vehicle V1 turns more inward than the first turning trajectory T1 shown in FIG. 2A. Therefore, when the host vehicle V1 travels along the second turning trajectory T2 from position P1 to position P7, there is no space on the left side of the host vehicle V1 for the following vehicle V2 to enter. Therefore, even if the following vehicle V2 turning left attempts to overtake the host vehicle V1 from the left side by traveling along the traveling trajectory Tc, it will stop when it reaches position P8 to avoid contact with the host vehicle V1.

[0051] In this way, when the host vehicle V1 and the following vehicle V2 turn left, by switching the turning trajectory from the predetermined first turning trajectory T1 to the second turning trajectory T2, no space is created on the left side of the host vehicle V1 for the following vehicle V2 to enter. As a result, it is possible to prevent the following vehicle V2 from overtaking or cutting in at the intersection C.

[0052] Furthermore, there is a case where the host vehicle V1 is cut in by an oncoming vehicle V3 in the traveling scene shown in Fig. 2A. This case will be described with reference to Figs. 3A and 3B.

[0053] 3A is a plan view showing an example of a driving scene in which the host vehicle V1 travels along the second turning trajectory T2 when the oncoming vehicle V3 turns right in the driving scene shown in FIG. 2A. As shown in FIG. 2C, when the host vehicle V1 travels along the second turning trajectory T2, there is no space on the left side of the host vehicle V1 for the following vehicle V2 to enter, and therefore the following vehicle V2 does not overtake the host vehicle V1 within the intersection C. However, there may be a space on the right side of the host vehicle V1 for the oncoming vehicle V3 turning right to enter. For example, as shown in FIG. 3A, when the host vehicle V1 travels from position P1 to position P9, the oncoming vehicle V3 turning right may travel along the traveling trajectory Td from position P3 to position P10 and enter the space on the right side of the host vehicle V1.

[0054] As shown in FIG. 3A, if the oncoming vehicle V3 enters lane L4 before the host vehicle V1, the oncoming vehicle V3 will enter (cut in) in front of the host vehicle V1, which may cause the host vehicle V1 to suddenly stop. As a result, the occupants of the host vehicle V1 may feel discomfort and anxiety due to the significant change in the behavior of the host vehicle V1. Therefore, if the driving assistance device 19 determines, using the determination function of the determination unit 22, that the oncoming vehicle V3 will turn right at the intersection C, the driving assistance device 19 causes the host vehicle V1 to travel along the first turning trajectory T1. However, if the following vehicle V2 turns left at the intersection C, the driving assistance device 19 may cause the host vehicle V1 to travel along the second turning trajectory T2 even if it determines that the oncoming vehicle V3 will turn right at the intersection C.

[0055] On the other hand, if it is determined that the oncoming vehicle V3 will not turn right at the intersection C, the host vehicle V1 is made to travel along the first turning trajectory T1 or the second turning trajectory T2. Specifically, if it is determined that the following vehicle V2 will turn left at the intersection C and the oncoming vehicle V3 will not turn right at the intersection C, the host vehicle V1 is made to travel along the second turning trajectory T2, and if it is determined that the following vehicle V2 will not turn left at the intersection C and the oncoming vehicle V3 will not turn right at the intersection C, the host vehicle V1 is made to travel along the selected turning trajectory as appropriate. Note that the case where the oncoming vehicle V3 will not turn right at the intersection C also includes the case where the oncoming vehicle V3 is not detected.

[0056] 3B is a plan view showing an example of a driving scene in which the host vehicle V1 travels along a first turning trajectory T1 when an oncoming vehicle V3 turns right in the driving scene shown in FIG. 3A. The first turning trajectory T1 shown in FIG. 3B is a turning trajectory in which the host vehicle V1 turns outside the second turning trajectory T2 shown in FIG. 2C. Therefore, when the host vehicle V1 travels along the first turning trajectory T1 from position P1 to position P11, no space is created on the right side of the host vehicle V1 for the oncoming vehicle V3 to enter. Therefore, even if the oncoming vehicle V3 turning right travels along the traveling trajectory Te and attempts to enter ahead of the host vehicle V1, it will stop when it reaches position P12 to avoid contact with the host vehicle V1.

[0057] Furthermore, when the driving environment recognition function of the recognition unit 21 detects a parallel running vehicle traveling in a lane adjacent to the lane in which the host vehicle V1 is traveling, the driving assistance device 19 uses the determination function of the determination unit 22 to determine whether the parallel running vehicle will proceed straight through the intersection C. The determination of whether the parallel running vehicle will proceed straight through the intersection C is made by recognizing the flashing state of the turn signal of the parallel running vehicle and / or the posture of the parallel running vehicle from the detection results of the imaging device 11 and the distance measurement device 12. For example, when it is detected that a turn signal on either side of the parallel running vehicle is flashing, it is determined that the parallel running vehicle will not proceed straight through the intersection C but will turn right or left. On the other hand, when it is not detected that the turn signal of the parallel running vehicle is flashing and it is recognized that the posture of the parallel running vehicle is not tilted with respect to the traveling direction of the road, it is determined that the parallel running vehicle will proceed straight through the intersection C.

[0058] If it is determined that the parallel running vehicle will go straight through the intersection C, the driving assistance device 19 causes the host vehicle V1 to travel along the second turning trajectory T2 regardless of whether an oncoming vehicle V3 has been detected. This is because, if the parallel running vehicle goes straight through the intersection, the oncoming vehicle V3 will stop to avoid contact with the parallel running vehicle, and therefore the oncoming vehicle V3 will not enter in front of the host vehicle V1. In contrast, if it is determined that the parallel running vehicle will not go straight through the intersection C, the driving assistance device 19 selects the first turning trajectory T1 or the second turning trajectory T2 depending on the driving environment of the host vehicle V1, and causes the host vehicle V1 to travel along the selected turning trajectory. Specifically, if the following vehicle V2 turns left, the second turning trajectory T2 is selected; if the following vehicle V2 does not turn left and the oncoming vehicle V3 turns right, the first turning trajectory T1 is selected; if the following vehicle V2 does not turn left and the oncoming vehicle V3 does not turn right, the first turning trajectory T1 or the second turning trajectory T2 is selected as appropriate.

[0059] For example, in the traveling scene shown in FIG. 3B, when a parallel traveling vehicle Vy traveling at position Py in lane L2 adjacent to lane L1 is detected, the driving assistance device 19 determines whether the parallel traveling vehicle Vy will proceed straight through the intersection C. In the traveling scene shown in FIG. 3B, no steering of the parallel traveling vehicle Vy is detected, and the parallel traveling vehicle Vy travels straight through the intersection C along the traveling trajectory Ty. In this case, the driving assistance device 19 causes the host vehicle V1 to travel along the second turning trajectory T2 regardless of whether an oncoming vehicle V3 is present. When the parallel traveling vehicle Vy travels straight through the intersection C along the traveling trajectory Ty, the oncoming vehicle V3 needs to stop within the intersection C to avoid contact with the parallel traveling vehicle Vy. Therefore, when the parallel traveling vehicle Vy is detected, the oncoming vehicle V3 turning right will not enter (cut in) ahead of the host vehicle V1.

[0060] The calculation unit 25 has a function (i.e., a risk calculation function) of calculating the risk of the following vehicle V2 and the oncoming vehicle V3 of the host vehicle V1. When the following vehicle V2 turns left and the oncoming vehicle V3 turns right, the driving assistance device 19 needs to select an appropriate turning trajectory from the first turning trajectory T1 and the second turning trajectory T2 according to the driving environment of the host vehicle V1. As one of the indices for selecting a turning trajectory, the driving assistance device 19 calculates the risk of the following vehicle V2 and the oncoming vehicle V3 relative to the host vehicle V1 using the risk calculation function of the calculation unit 25. Specifically, for each of the following vehicle V2 and the oncoming vehicle V3, it calculates the risk of approaching the host vehicle V1, overtaking the host vehicle V1, and entering ahead of the host vehicle V1.

[0061] The driving assistance device 19 calculates the above-mentioned risk according to the time from when the host vehicle V1 enters the intersection C until the following vehicle V2 and the oncoming vehicle V3 reach predetermined positions. For example, when the driving assistance device 19 determines, using the determination function of the determination unit 22, that the following vehicle V2 will turn left at the intersection C, the driving assistance device 19 calculates, using the risk calculation function of the calculation unit 25, a first risk that the following vehicle V2 will enter ahead of the host vehicle V1. The first risk is a risk calculated based on the time from when the host vehicle V1 passes the stop line at the intersection C until the following vehicle V2 reaches the center line of the lane of travel of the host vehicle V1 after turning left. Furthermore, when the driving assistance device 19 determines, using the determination function of the determination unit 22, that the oncoming vehicle V3 will turn right at the intersection C, the driving assistance device 19 calculates, using the risk calculation function of the calculation unit 25, a second risk that the oncoming vehicle V3 will enter ahead of the host vehicle V1. The second risk is a risk calculated based on the time from when the host vehicle V1 passes the stop line until the oncoming vehicle V3 reaches the center line of the lane in which the host vehicle V1 is traveling after turning left.

[0062] In the driving scene shown in FIG. 3B , if a stop line B is placed ahead of the host vehicle V1 and the center line of the lane in which the host vehicle V1 is traveling after turning left is Z, the driving assistance device 19 acquires the detection results from the distance measuring device 12 using the driving environment recognition function of the recognition unit 21, and calculates the difference in driving speed between the host vehicle V1 and the following vehicle V2 and the oncoming vehicle V3 from the acquired results. Next, the risk calculation function of the calculation unit 25 estimates the driving trajectories of the following vehicle V2 and the oncoming vehicle V3, and calculates the time from when the host vehicle V1 passes the stop line B until each of the following vehicle V2 and the oncoming vehicle V3 reaches the center line Z based on the estimated driving trajectories and the calculated difference in driving speed. Then, a first risk and a second risk are calculated based on the calculated times.

[0063] The faster the traveling speeds of the following vehicle V2 and the oncoming vehicle V3 are compared to the traveling speed of the host vehicle V1, the shorter the time it takes for the following vehicle V2 and the oncoming vehicle V3 to reach the center line Z. In other words, the shorter the time it takes for the following vehicle V2 and the oncoming vehicle V3 to reach the center line Z after the host vehicle V1 passes the stop line B, the higher the risk that these vehicles will approach the host vehicle V1 and enter in front of the host vehicle V1. Therefore, the driving assistance device 19 calculates the first risk so that the shorter the time it takes for the following vehicle V2 to reach the center line Z after the host vehicle V1 passes the stop line B, the higher the risk. Similarly, the driving assistance device 19 calculates the second risk so that the shorter the time it takes for the oncoming vehicle V3 to reach the center line Z after the host vehicle V1 passes the stop line B, the higher the risk.

[0064] The first risk and the second risk may be continuous or discrete. For example, the driving assistance device 19 calculates the first risk and the second risk in three stages: high risk, medium risk, and low risk. After calculating the first risk and the second risk using the risk calculation function of the calculation unit 25, the driving assistance device 19 compares the magnitude of the first risk with the magnitude of the second risk using the driving control function of the control unit 24. If the first risk is equal to or greater than the second risk, the driving assistance device 19 causes the host vehicle V1 to travel along the second turning trajectory T2, and if the first risk is less than the second risk, the driving assistance device 19 causes the host vehicle V1 to travel along the first turning trajectory T1. This makes it possible to select a turning trajectory that can suppress cutting in for a vehicle with a higher risk of entering (cutting in) ahead of the host vehicle V1.

[0065] [Processing in driving assistance systems] 4A and 4B, the procedure for processing information by the driving assistance device 19 will be described. FIGS. 4A and 4B are an example of a flowchart showing information processing executed in the driving assistance system 10 of this embodiment. The processing described below is executed at predetermined time intervals by the CPU 191, which is the processor of the driving assistance device 19.

[0066] 4A, the storage function of the storage unit 23 stores a predetermined first turning trajectory T1 and a second turning trajectory T2 that turns inside the first turning trajectory T1 as driving trajectories when turning left at an intersection C. Thereafter, when the host vehicle V1 is actually driven by autonomous driving control, the driving environment recognition function of the recognition unit 21 acquires the driving route of the host vehicle V1 from the navigation device 16 in step S2, and then acquires the current position of the host vehicle V1 from the position detection device 15 in step S3.

[0067] Then, in step S4, the determination function of the determination unit 22 determines whether or not the host vehicle V1 needs to turn left at the intersection C ahead, based on the travel route and the current position of the host vehicle V1. If it is determined that the host vehicle V1 does not need to turn left at the intersection C ahead, execution of the routine shown in Figures 4A and 4B is terminated, and autonomous driving control by the driving assistance function of the assistance unit 20 is continued. On the other hand, if it is determined that the host vehicle V1 needs to turn left at the intersection C ahead, the process proceeds to step S5.

[0068] In step S5, the driving environment recognition function of the recognition unit 21 uses the imaging device 11 and the distance measuring device 12 to detect obstacles (for example, parked vehicle Vx in the left lane) that exist on the road after the left turn. In addition, obstacles, signs, road conditions, and the status of traffic lights installed at intersection C around the vehicle V1 are detected, and the detection results are integrated to recognize the driving environment of the vehicle V1. In the following step S6, the determination function of the determination unit 22 obtains the lane closure risk of the road after the left turn from map information 14, etc. For example, the probability that a parked vehicle Vx will exist in the left lane of the road after the left turn is obtained from the accumulation of detection results from previous travel.

[0069] Then, in step S7, the determination function of the determination unit 22 determines whether the host vehicle V1 will enter the right lane after turning left, based on the driving environment of the host vehicle V1 and the lane closure risk of the road after turning left. If it is determined that the host vehicle V1 will not enter the right lane after turning left, the process proceeds to step S8, and the driving control function of the control unit 24 causes the host vehicle V1 to travel along a trajectory that will enter the left lane of the road after turning left. Thereafter, the execution of the routine ends, and the process transitions to autonomous driving control using the driving assistance function of the assistance unit 20. On the other hand, if it is determined that the host vehicle V1 will enter the right lane after turning left, the process proceeds to step S9 of FIG. 4B.

[0070] In step S9 of FIG. 4B, the driving environment recognition function of the recognition unit 21 detects the following vehicle V2 of the host vehicle V1, and in step S10, the determination function of the determination unit 22 determines whether the following vehicle V2 is present. In this determination, for example, the blinking state of the turn signal of the following vehicle V2 is acquired from the detection result of the imaging device 11. If it is determined that the following vehicle V2 is present, the process proceeds to step S11, where it is determined whether the following vehicle V2 will turn left at the intersection C. If it is determined that the following vehicle V2 will turn left at the intersection C, the process proceeds to step S12, where the driving control function of the control unit 24 causes the host vehicle V1 to travel along the second turning trajectory T2. Thereafter, execution of the routine ends, and the process transitions to autonomous driving control using the driving assistance function of the assistance unit 20. On the other hand, if it is determined that the following vehicle V2 is not present or that the following vehicle V2 will not turn left at the intersection C, the process proceeds to step S13.

[0071] In step S13, the traveling environment recognition function of the recognition unit 21 detects an oncoming vehicle V3 of the host vehicle V1, and in step S14, the determination function of the determination unit 22 determines whether or not the oncoming vehicle V3 exists. If it is determined that the oncoming vehicle V3 exists, the process proceeds to step S15, where it is determined whether or not the oncoming vehicle V3 will turn right at the intersection C. If it is determined that the oncoming vehicle V3 will turn right at the intersection C, the process proceeds to step S16, where the traveling control function of the control unit 24 causes the host vehicle V1 to travel along the first turning trajectory T1. Thereafter, execution of the routine ends, and the process transitions to autonomous traveling control using the driving assistance function of the assistance unit 20. On the other hand, if it is determined that the oncoming vehicle V3 does not exist or that the oncoming vehicle V3 will not turn right at the intersection C, the process proceeds to step S17.

[0072] In step S17, the driving control function of the control unit 24 appropriately selects either the first turning trajectory T1 or the second turning trajectory T2 depending on the driving environment of the host vehicle V1, and causes the host vehicle V1 to travel along the selected turning trajectory. After that, the execution of the routine ends, and the process shifts to autonomous driving control by the driving assistance function of the assistance unit 20.

[0073] Next, another example of the processing from step S9 onward shown in Figure 4B will be shown using Figure 5. The processing shown in Figure 5 differs from the processing shown in Figure 4B in that steps S21 to S27 for calculating the first risk and the second risk are added when both a following vehicle V2 and an oncoming vehicle V3 are detected. The processing described below is executed at predetermined time intervals by CPU 191, which is the processor of driving assistance device 19. Note that, hereinafter, explanations of steps that are the same as those shown in Figure 4B will be omitted.

[0074] In the process shown in FIG. 5, if it is determined in step S11 that the following vehicle V2 will turn left at the intersection C, the process proceeds to step S21, where an oncoming vehicle V3 is detected, as in step S13. In the following step S22, it is determined whether or not an oncoming vehicle V3 is present, as in step S14. If it is determined that an oncoming vehicle V3 is present, the process proceeds to step S23, where it is determined whether or not the oncoming vehicle V3 will turn right at the intersection C. If it is determined in step S22 that an oncoming vehicle V3 is not present, or if it is determined in step S23 that the oncoming vehicle V3 will not turn right at the intersection C, the process proceeds to step S12. On the other hand, if it is determined that an oncoming vehicle V3 is present and that the oncoming vehicle V3 will turn right at the intersection C, the process proceeds to step S24.

[0075] In step S24, the risk calculation function of the calculation unit calculates a first risk of the following vehicle V2 and a second risk of the oncoming vehicle V3. In the following step S25, the driving environment recognition function of the recognition unit 21 detects a parallel vehicle Vy driving in a lane adjacent to the lane in which the host vehicle V1 is driving, and in step S26, the determination function of the determination unit 22 determines whether the parallel vehicle Vy will proceed straight through the intersection C. If it is determined that the parallel vehicle Vy will proceed straight through the intersection C, the process proceeds to step S12. On the other hand, if it is determined that the parallel vehicle Vy will not proceed straight through the intersection C, the process proceeds to step S27. Note that the case in which the parallel vehicle Vy does not proceed straight through the intersection C includes the case in which the parallel vehicle Vy was not detected.

[0076] In step S27, the driving control function of the control unit 24 determines whether the first risk is equal to or greater than the second risk. If it is determined that the first risk is equal to or greater than the second risk, the process proceeds to step S12. On the other hand, if it is determined that the first risk is less than the second risk, the process proceeds to step S16.

[0077] [Embodiments of the present invention] As described above, according to the present embodiment, a driving assistance method is provided in which a processor is used to drive a host vehicle V1 through autonomous driving control, the processor stores a predetermined first turning trajectory T1 and a second turning trajectory T2 that turns inside the first turning trajectory T1 as driving trajectories for turning left at an intersection C, and when the host vehicle V1 turns left at the intersection C, the processor determines whether a following vehicle V2 will turn left at the intersection C, and if it determines that the following vehicle V2 will turn left at the intersection C, causes the host vehicle V1 to drive along the second turning trajectory T2. This prevents space from being created on the left side of the host vehicle V1 for the following vehicle V2 to enter, making it possible to prevent the following vehicle V2 from overtaking the host vehicle V1 within the intersection C and entering ahead of the host vehicle V1.

[0078] Furthermore, according to the driving assistance method of this embodiment, when it is determined that the following vehicle V2 will not turn left at the intersection C, the host vehicle V1 is caused to travel along the first turning trajectory T1 or the second turning trajectory T2. This makes it possible to select a turning trajectory according to the traveling environment of the host vehicle V1.

[0079] Furthermore, according to the driving assistance method of this embodiment, when it is determined that the following vehicle V2 will not turn left at the intersection C, the processor determines whether or not the oncoming vehicle V3 of the host vehicle V1 will turn right at the intersection C, and when it is determined that the oncoming vehicle V3 will not turn right at the intersection C, the processor causes the host vehicle V1 to travel along the first turning trajectory T1 or the second turning trajectory T2, and when it is determined that the oncoming vehicle V3 will turn right at the intersection C, the processor causes the host vehicle V1 to travel along the first turning trajectory T1. As a result, no space is created on the right side of the host vehicle V1 for the oncoming vehicle V3 to enter, and it is possible to prevent the oncoming vehicle V3 from entering ahead of the host vehicle V1.

[0080] Furthermore, according to the driving assistance method of this embodiment, when the processor determines that the following vehicle V2 will turn left at the intersection C, the processor determines whether the oncoming vehicle V3 of the host vehicle V1 will turn right at the intersection C. When the processor determines that the oncoming vehicle V3 will turn right at the intersection C, the processor calculates a first risk that the following vehicle V2 will enter ahead of the host vehicle V1 and a second risk that the oncoming vehicle V3 will enter ahead of the host vehicle V1. If the first risk is equal to or greater than the second risk, the processor causes the host vehicle V1 to travel along the second turning trajectory T2. If the first risk is less than the second risk, the processor causes the host vehicle V1 to travel along the first turning trajectory T1. This allows the processor to select an appropriate turning trajectory from the first turning trajectory T1 and the second turning trajectory T2 depending on the risk that the following vehicle V2 and the oncoming vehicle V3 will enter ahead of the host vehicle V1, thereby autonomously controlling the traveling of the host vehicle V1.

[0081] Furthermore, according to the driving assistance method of this embodiment, the processor calculates the first risk based on the time from when the host vehicle V1 passes the stop line B at the intersection C until the following vehicle V2 reaches the center line Z of the lane in which the host vehicle V1 is traveling after turning left, and calculates the second risk based on the time from when the host vehicle V1 passes the stop line B until the oncoming vehicle V3 reaches the center line Z. This makes it possible to accurately calculate the first risk and the second risk according to the driving environment of the host vehicle V1.

[0082] Furthermore, according to the driving assistance method of this embodiment, when the processor determines that a parallel vehicle Vy traveling in a lane adjacent to the lane in which the host vehicle V1 is traveling will proceed straight through the intersection C, the processor causes the host vehicle V1 to travel along the second turning trajectory T2 regardless of the presence or absence of the oncoming vehicle V3. This allows the host vehicle V1 to select an appropriate turning trajectory according to the traveling environment of the host vehicle V1 and autonomously control the traveling of the host vehicle V1. Furthermore, this eliminates the need for processing to determine the oncoming vehicle V3, thereby avoiding complex processing in the driving assistance device 19.

[0083] Furthermore, according to the driving assistance method of this embodiment, the first turning locus T1 is a traveling locus that is set such that the distance from when the host vehicle V1 enters the intersection C until it starts turning is longer than the second turning locus T2. This makes it possible to easily set the predetermined first turning locus T1 and second turning locus T2.

[0084] Furthermore, according to the present embodiment, the driving assistance device 19 that causes the host vehicle V1 to travel by autonomous travel control includes: a memory unit 23 that stores a predetermined first turning trajectory T1 and a second turning trajectory T2 that turns inside the first turning trajectory T1 as travel trajectories when turning left at an intersection C; a determination unit 22 that determines whether a following vehicle V2 will turn left at the intersection C when the host vehicle V1 turns left at the intersection C; and a control unit 24 that causes the host vehicle V1 to travel along the second turning trajectory T2 when the determination unit 22 determines that the following vehicle V2 will turn left at the intersection C. This prevents space from being created on the left side of the host vehicle V1 for the following vehicle V2 to enter, thereby preventing the following vehicle V2 from overtaking the host vehicle V1 and entering ahead of the host vehicle V1 within the intersection C. [Explanation of symbols]

[0085] 10...Driver assistance system 11...imaging device 12…Distance measuring device 13...Status detection device 14...Map information 15...Position detection device 16...Navigation device 17...Vehicle control device 171...Vehicle speed control device 172...Steering control device 18...Display device 19...Driving assistance device 191...CPU (processor) 192...ROM 193...RAM 20…Support Department 21...Recognition part 22…Judgment section 23…Storage section 24...Control unit 25...Calculation section A...Angle B…stop line C...Intersection L1, L2, L3, L4, L5, L6...lanes P1, P2, P3, P4, P5, P6, P7, P8, P9, P10, P11, P12, Px, Py...Position T1...First turning trajectory T2: Second turning trajectory Ta, Tb, Tc, Td, Te, Ty...travel trajectory V1: Your vehicle V2: Following vehicle V3: Oncoming vehicle Vx: Parked vehicle Vy...Parallel running vehicles Z…center line

Claims

1. A driving assistance method for causing a vehicle to travel under autonomous driving control using a processor, The processor: As a travel trajectory when turning left at an intersection, a predetermined first turning trajectory for one combination of a lane through which the host vehicle enters the intersection and a lane through which the host vehicle exits the intersection, and a second turning trajectory for the one combination, which turns inside the first turning trajectory so as not to create a space on the left side of the host vehicle for a vehicle following the host vehicle to enter, are stored; When the host vehicle turns left at the intersection, it is determined whether the following vehicle turns left at the intersection; When it is determined that the following vehicle will turn left at the intersection, the driving assistance method causes the host vehicle to travel along the second turning trajectory.

2. The processor: The driving assistance method according to claim 1 , wherein, when it is determined that the following vehicle will not turn left at the intersection, the host vehicle is caused to travel along the first turning trajectory or the second turning trajectory.

3. The processor: When it is determined that the following vehicle will not turn left at the intersection, it is determined whether or not an oncoming vehicle of the subject vehicle will turn right at the intersection; When it is determined that the oncoming vehicle will not turn right at the intersection, the host vehicle is caused to travel along the first turning locus or the second turning locus; The driving assistance method according to claim 1 , wherein when it is determined that the oncoming vehicle is turning right at the intersection, the host vehicle is caused to travel along the first turning trajectory.

4. The processor: When it is determined that the following vehicle will turn left at the intersection, it is determined whether or not an oncoming vehicle of the subject vehicle will turn right at the intersection; When it is determined that the oncoming vehicle will turn right at the intersection, a first risk that the following vehicle will enter in front of the host vehicle and a second risk that the oncoming vehicle will enter in front of the host vehicle are calculated; If the first risk is equal to or greater than the second risk, the host vehicle is caused to travel along the second turning trajectory; The driving assistance method according to claim 1 , wherein when the first risk is less than the second risk, the host vehicle is caused to travel along the first turning trajectory.

5. The processor: calculating the first risk based on a time from when the host vehicle passes a stop line at the intersection to when the following vehicle reaches a center line of the traveling lane of the host vehicle after turning left; The driving assistance method according to claim 4 , wherein the second risk is calculated based on a time period from when the host vehicle passes the stop line until when the oncoming vehicle reaches the center line.

6. The processor:

6. The driving assistance method according to claim 3, wherein, when it is determined that a parallel vehicle traveling in a lane adjacent to the lane in which the host vehicle is traveling will proceed straight through the intersection, the host vehicle is caused to travel along the second turning trajectory regardless of whether or not there is an oncoming vehicle.

7. 7. The driving assistance method according to claim 1, wherein the first turning trajectory is a traveling trajectory in which a distance from when the host vehicle enters the intersection to when the host vehicle starts turning is set to be longer than the second turning trajectory.

8. A driving assistance device that drives a vehicle by autonomous driving control, a storage unit that stores, as a travel trajectory when turning left at an intersection, a predetermined first turning trajectory for one combination of a lane through which the host vehicle enters the intersection and a lane through which the host vehicle exits the intersection, and a second turning trajectory for the one combination that turns inside the first turning trajectory so as not to create a space on the left side of the host vehicle for a vehicle following the host vehicle to enter; a determination unit that, when the host vehicle turns left at the intersection, determines whether the following vehicle turns left at the intersection; a control unit that, when the determination unit determines that the following vehicle will turn left at the intersection, causes the host vehicle to travel along the second turning trajectory.

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