Driving assistance method and driving assistance device

Abstract

A processor 10: acquires a first current position of a host vehicle V1; identifies a first lane L1 in which the host vehicle V1 travels; acquires a second current position of another vehicle V2 traveling in a second lane L2 intersecting at an intersection SB present ahead in the first lane L1 in the travel direction of the host vehicle V1; calculates a first approach angle AG1 formed by the first lane L1 and a reference line BL connecting the first current position and the second current position; calculates a second approach angle AG2 formed by the reference line AG1 and the second lane L2; and, in cases where it is determined that the difference between the first approach angle AG1 and the second approach angle AG2 is less than a prescribed threshold value, accelerates or decelerates the host vehicle V1 so that the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than the prescribed threshold value.

Description

Driving assistance method and driving assistance device

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

[0002] A technology is known that notifies the driver of a first vehicle traveling in a first driving lane of the possibility of a collision when it is estimated that there is a possibility of a collision between the first vehicle traveling in a first driving lane and the second vehicle traveling in a second driving lane, and the first driving lane is a non-priority road relative to the second driving lane.

[0003] Japanese Patent Application Laid-Open No. 2022-104086

[0004] However, even if a driver is notified of the possibility of a collision at an intersection, it is difficult for the driver to escape from the situation where a collision is possible by operating the vehicle.

[0005] The problem to be solved by the present invention is to control the driving of the vehicle so as to escape from a situation where a collision is possible, even if the possibility of a collision at an intersection is predicted.

[0006] The present invention solves the above problem by obtaining a second current position of another vehicle traveling in a second lane that intersects with a first lane in which the vehicle is traveling at an intersection, and if it is determined that the difference between a first approach angle formed by a reference line connecting the first current position of the vehicle and the second current position of the other vehicle and the first lane, and a second approach angle formed by the reference line and the second lane, is less than a predetermined threshold, accelerating or decelerating the vehicle so that the difference becomes greater than or equal to the predetermined threshold.

[0007] According to the present invention, even if the possibility of a collision at an intersection is predicted, the driving of the vehicle can be controlled so as to escape from a situation in which a collision is possible.

[0008] 2A is a block diagram showing the hardware configuration of a driving control system. FIG. 2B is a diagram explaining a first approach angle and a second approach angle on a collision course. FIG. 2C is a diagram explaining an example when an obstacle is present in FIG. 2A. FIG. 2D is a flowchart showing a processing procedure for driving control. FIG. 1 is a diagram explaining an example of driving control at an intersection including a priority road. FIG. 2E is a diagram explaining an example of driving control at an intersection including a priority road. FIG. 1 is a diagram explaining an example of driving control taking into account the distance to the intersection. FIG. 2F is a diagram explaining an example of driving control taking into account the distance to the intersection. FIG. 1 is a diagram explaining an example of driving control taking into account a plurality of other vehicles. FIG. 2G is a diagram explaining an example of driving control taking into account a plurality of other vehicles.

[0009] First Embodiment FIG. 1 shows the hardware configuration of a driving control system 100 equipped with a driving assistance device 1 according to this embodiment. The driving assistance method is implemented by a processor 10 of the driving assistance device 1 using the hardware components of the driving control system 100. The driving control system 100 includes one or more sensors 2, a host vehicle information acquisition device 3, a vehicle information acquisition device 4, map information 5, and a navigation device 6. A plurality of sensors 2 are provided in the vehicle, forming a sensor group that cooperates with each other. The sensors 2 detect the presence or absence of objects, including other vehicles, around the host vehicle, the distance to the objects, and the relative speed and relative acceleration of the objects. The sensors 2 detect other vehicles traveling in front, behind, left, right, and right lateral directions (oncoming lanes, adjacent lanes, and adjacent lanes) of the host vehicle. The detection information acquired by the sensors 2 is provided to the processor 10. The processor 10 determines the behavior of the object, including at least one of the position, movement amount, movement direction, attitude, speed, and acceleration, and changes therein, based on the detection information, and executes driving control of the host vehicle using the determination result. The sensor 2 includes one or more cameras 21 arranged on the vehicle. The cameras 21 include image sensors with imaging elements such as CCDs, ultrasonic cameras, and infrared cameras. The cameras 21 include at least a front camera that captures images in front of the vehicle, a rear camera that captures images behind or on the rear sides of the vehicle, and left and right side cameras that capture images of the left and right sides, and the front and rear of the vehicle. The cameras 21 capture images of the surroundings of the vehicle in all directions. The type of camera 21 is not limited as long as it can capture images of the vehicle in all directions. The sensor 2 includes a radar device 22 that detects (ranges) the presence, position, and position changes of objects around the vehicle. The radar device 22 emits electromagnetic waves toward the objects and measures the reflected waves to measure the distance and direction from the vehicle to the objects and the distance between the objects. The radar device 22 includes laser radar, millimeter-wave radar (LRF), a light detection and ranging (LiDAR) unit, ultrasonic radar, and sonar. The sensor 2 includes a position detection device 23 that includes a receiver for signals from a Global Navigation Satellite System (GNSS), a gyro sensor, and a vehicle speed sensor, and that uses these to detect the position of the vehicle.In the position detection device 23, the sensor 2 detects the position of other vehicles (relative position to the host vehicle) based on detection information. The sensor 2 is equipped with an illuminance meter and acquires information on external brightness. The sensor 2 is equipped with a clock and acquires the current time. The sensor 2 can acquire detection information from an in-vehicle device and an external device via the communication device 30 depending on their respective functions. The external device includes a server that provides weather information. The sensor 2 acquires weather information from the server. The external device includes a server that provides calendar information including the sunset time at each location. The sensor 2 acquires calendar information including the sunset time at the current location of the host vehicle from the server. Each sensor 2 sends the acquired detection information to the host vehicle information acquisition device 3, the other vehicle information acquisition device 4, or the processor 10 in response to a request or command. The processor 10 may acquire the detection information directly from the camera 21, the radar device 22, or the position detection device 23, or may acquire the detection information via the host vehicle information acquisition device 3 or the other vehicle information acquisition device 4.

[0010] The host vehicle information acquisition device 3 calculates behaviors of the host vehicle, including at least one of the current position, amount of movement, direction of movement, attitude, speed, and acceleration, and changes therein, based on the detection information acquired from the sensor 2, and provides the calculated information to the processor 10. The other vehicle information acquisition device 4 calculates behaviors of objects, including other vehicles, around the host vehicle, including at least one of the current position, amount of movement, direction of movement, attitude, speed, and acceleration, and changes therein, based on the detection information acquired from the sensor 2, and provides the calculated information to the processor 10. This information is used for driving control.

[0011] The driving control system 100 further includes map information 5. The map information 5 is stored in one or more of the ROM 12, the storage device of the navigation device 6, and the storage device (not shown) of an external server accessible by the processor 10 via the communication device 30. The map information 5 includes lane information 51. The map information 5 is high-precision map information that includes the lane information 51 referenced in the execution of autonomous lane change control. The lane information 51 includes identification information that identifies each of multiple lanes belonging to a road. The navigation device 6 references the map information 5 and calculates a route to a set destination. This route includes a target trajectory that identifies the lane in which the host vehicle will travel. The route and target trajectory calculated by the navigation device 6 are provided to the vehicle actuator 200 and used for autonomous driving control.

[0012] The driving control system 100 includes a vehicle actuator 200. The vehicle actuator 200 includes a steering control device 210, a drive control device 220, and a braking control device 230, and executes autonomous driving control according to a driving plan formulated by the processor 10 of the driving assistance device 1. The autonomous driving control includes acceleration control, deceleration control, lateral movement control, and lane change control. The driving plan for each driving control includes a command value for causing the host vehicle to travel along a target trajectory. The command value for the driving control is generated by the vehicle actuator 200 or the processor 10. The command value is a vehicle control command value for causing the host vehicle to travel along the target trajectory. The command value includes a set speed (including an upper limit speed and an applied speed), acceleration, deceleration, steering angle, steering speed, or steering acceleration when driving the vehicle. The vehicle actuator 200 controls the vehicle behavior and wheel behavior according to the input so that the host vehicle autonomously travels along a route to the destination. Based on these controls, at least one of the drive actuator of the drive mechanism of the vehicle body controlled by the drive control device 220 and the brake actuator controlled by the brake control device 230, and the steering actuator of the steering control device 210, if necessary, operate autonomously, thereby executing autonomous driving control that causes the vehicle to autonomously travel along a target trajectory. Also, the vehicle actuator 200 can perform driving in accordance with command values ​​based on manual operation by the driver input via the input device 20a.

[0013] The driving assistance device 1 included in the driving control system 100 controls autonomous driving of the vehicle to travel along a target trajectory. The processor 10 included in the driving assistance device 1 includes a read-only memory (ROM) 12 storing a program for controlling autonomous driving, a central processing unit (CPU) 11 executing the program stored in the ROM 12, and a random access memory (RAM) 13 functioning as an accessible storage device. The processor 10 implements the driving assistance method using the various hardware components of the driving control system 100. The processor 10 of the driving assistance device 1 executes the functions of calculating a first approach angle and a second approach angle and executing driving control based on the difference between the first approach angle and the second approach angle by cooperating with the various hardware components shown in FIG. 1 to execute the respective functions. The driving assistance device 1 includes an input device 20a and an output device 20b. The input device 20a includes a steering wheel, brakes, indicator lights, and a touch-panel display 20b1 that accepts inputs from the driver of the vehicle. The output device 20b includes one or more of a display 20b1, a speaker 20b2, and a lamp 20b3 for presenting information to the driver of the vehicle. The driving assistance device 1 includes a communication device 30. The communication device 30 performs communication between the driving assistance device 1 and an external device, and communication between the devices included in the driving control system 100.

[0014] FIG. 2A shows an example of a scenario in which this driving assistance method is implemented. In this example, only one lane of a road is shown for clarity of explanation. The first lane L1 and the second lane L2 intersect at an intersection SB. The intersection SB is located ahead of the host vehicle V1 in the traveling direction (Y direction). The host vehicle V1 travels in the first lane L1, and the other vehicle V2 travels in the second lane L2. The host vehicle V1 travels along the Y direction in the figure, passes a point (host vehicle V1(t0)) on the first lane L1 at time t0, and then passes a point (host vehicle V1(t1)) at time t1. The other vehicle V2 travels along the X direction in the figure, passes a point (other vehicle V2(t0)) on the second lane L2 at time t0, and then passes a point (other vehicle V2(t1)) at time t1. The dashed lines indicate the detection area VW(t0) of sensor 2 of host vehicle V1 at time t0 and the detection area VW(t1) at time t1. The position of the other vehicle detected at time t0 is closer to the left and right perimeter of the detection area in the X direction than the position of the other vehicle detected at time t1. In other words, the detection position of the other vehicle at time t1 is close to the center of the detection area, but the detection position of the other vehicle at time t0 is closer to the perimeter of the detection area (farther from the center). Depending on the settings of sensor 2, it may even fall outside the detection area. Furthermore, other vehicles (xv2t1, yv2t1) at time t1 are visible in the driver's central vision, while other vehicles (xv2t0, yv2t0) at time t0 are visible in the driver's peripheral vision. While humans can accurately recognize the characteristics (shape, color, and movement) of objects captured in their central vision, it is difficult to accurately recognize the characteristics of objects captured in their peripheral vision. For this reason, it is difficult for the driver of the host vehicle V1 to recognize the other vehicle V2 at position t0 and accurately recognize its movements, and the driver may only become aware of the other vehicle V2 after the host vehicle V1 approaches the other vehicle V2. Figure 2A shows a reference line BL(t0) connecting the current position V1(t0) of the host vehicle V1 at time t0 and the current position V2(t0) of the other vehicle V2 at time t0, and a reference line BL(t1) connecting the current position V1(t1) of the host vehicle V1 at time t1 and the current position V2(t1) of the other vehicle V2 at time t1.2A shows the first approach angle AG1(t0) between the reference line BL(t0) and the first lane L1 at time t0, the first approach angle AG1(t1) between the reference line BL(t1) and the first lane L1 at time t1, the second approach angle AG2(t0) between the reference line BL(t0) and the second lane L2 at time t0, and the second approach angle AG2(t1) between the reference line BL(t1) and the second lane L2 at time t1. For example, if the position of another vehicle V2 at time t0 is (xvt0, yvto), the angle θ(to) of the second approach angle AG2(t0) can be calculated using the following equation (1). The same applies to the other approach angles. In the example of FIG. 2A , the first lane L1 and the second lane L2 intersect at right angles at intersection SB, and the first approach angle AG1(t0), the first approach angle AG1(t1), the second approach angle AG2(t0), and the second approach angle AG2(t1) are 45 degrees. If the distances of the host vehicle V1 and the other vehicle V2 from intersection SB are approximately equal at times t0 and t1, and the speeds of the host vehicle V1 and the other vehicle V2 are approximately equal from time t0 to t1, and this state is maintained over time, the host vehicle V1 and the other vehicle V2 are predicted to arrive at intersection SB at approximately the same time and potentially become too close to each other at intersection SB. A road structure that creates this situation is sometimes called a collision course. Because other vehicles far from the host vehicle V1 are detected by the driver's peripheral vision, the driver may not notice the other vehicle V2 approaching the host vehicle V1 or may be misled into thinking that the other vehicle V2 is stationary due to the aforementioned visual characteristics of the human eye. For this reason, there have been reported cases of collision accidents (also called collision phenomena) caused by driver illusions at intersections on roads with good visibility and no buildings or other structures in the surrounding area, where fields and farmland are widespread. The driving assistance method of this embodiment predicts a situation in which the host vehicle V1 and the other vehicle V2 will come too close to each other at an intersection on a collision course when the first approach angle AG1 (t0, t1) and the second approach angle AG2 (t0, t1) are substantially equal (the difference is less than a predetermined value), and resolves the situation (positional relationship) by executing autonomous acceleration control or deceleration control.

[0015] 2B, if an obstacle BD such as a building is present and the other vehicle V2 traveling in the second lane L2 cannot be detected by the sensor 2 that detects the outside world due to this obstacle BD, even the occupants (humans) of the vehicle V1 cannot see the other vehicle V2 hidden by the obstacle BD, and this does not correspond to the collision course phenomenon caused by a human optical illusion. In such a situation, the driving assistance control of this embodiment is not performed, and driving is carried out based on the driver's judgment.

[0016] The control procedure of this embodiment will be described with reference to the flowchart of FIG. 3. The processor 10 acquires detection information about the surroundings of the host vehicle V1 using the sensor 2 (S1). The detection information includes detection information based on image capture information from the camera 21 and detection information based on measurement information from the radar device 22. The processor 10 acquires host vehicle information related to the behavior of the host vehicle V1 from the host vehicle information acquisition device 3 or the sensor 2 (S2). The host vehicle information includes at least one of the host vehicle's first current position, movement amount, movement direction, attitude, speed, and acceleration, and changes therein. The processor 10 acquires the first current position of the host vehicle V1 from the host vehicle information (S3). The processor 10 references the lane information 51 in the map information 5 (S4) and identifies the lane in which the host vehicle V1 is traveling, to which the first current position belongs, as the first lane L1 (S5).

[0017] The processor 10 refers to the map information 5 and identifies an intersection SB located ahead of the host vehicle V1 in the first lane L1 in the traveling direction (S6). The processor 10 identifies a second lane L2 that intersects with the first lane L1 at the intersection SB (S7). The processor 10 acquires other vehicle information from the other vehicle information acquisition device 4 or the sensor 2 (S8). The other vehicle information includes at least one of the second current position, movement amount, movement direction, attitude, speed, and acceleration of the other vehicle V2, and changes therein. The processor 10 identifies the other vehicle V2 traveling in the second lane L2 based on the other vehicle information (S9) and acquires the second current position of the other vehicle V2 (S10). The processor 10 repeatedly calculates the relative distance, relative speed, relative acceleration, and relative jerk between the position of the host vehicle V1 and the position of the other vehicle V2, and continuously determines the positional relationship between the host vehicle V1 and the other vehicle V2 at a predetermined period. The processor 10 calculates a reference line BL connecting the first current position and the second current position (S11). The processor 10 repeatedly calculates a first approach angle AG1 between the reference line BL and the first lane L1 at a predetermined period (S12). The processor 10 repeatedly calculates a second approach angle AG2 between the reference line BL and the second lane L2 at a predetermined period (S13).

[0018] The processor 10 repeatedly calculates the difference between the first approach angle AG1 and the second approach angle AG2 at a predetermined interval. The processor 10 determines whether the difference between the first approach angle AG1 and the second approach angle AG2 is less than a predetermined threshold (S14). In the difference calculation process, the processor 10 may calculate the difference between the distance of the host vehicle V1 to the intersection SB and the distance of the other vehicle V2 to the intersection SB, and the difference between the speed of the host vehicle V1 and the speed of the other vehicle V2, and determine whether each difference is less than a predetermined difference threshold. This determination is continuously performed at a predetermined interval while the host vehicle V1 is approaching the intersection SB. The processor 10 monitors the positional relationship between the host vehicle V1 and the other vehicle V2 relative to the intersection SB over time. If the difference between the first approach angle AG1 and the second approach angle AG2 is not less than the predetermined threshold (NO in S14), the process from S1 onward is repeated until the host vehicle V1 has passed the intersection (NO in S15). Once the host vehicle V1 has passed the intersection (YES in S15), the process is completed. If the difference between the first approach angle AG1 and the second approach angle AG2 is less than the predetermined threshold (YES in S14), the process proceeds to S16. When the host vehicle V1 and the other vehicle V2 arrive at the intersection SB at approximately the same time and it is determined that the host vehicle V1 may come too close to the other vehicle V2 at the intersection SB, the processor 10 formulates a driving plan for acceleration or deceleration (S16).

[0019] The predetermined threshold for evaluating the difference between the first approach angle AG1 and the second approach angle AG2 (hereinafter, sometimes collectively referred to as "approach angle") can be set in advance. The predetermined threshold is not limited to 0 and may be any value between 0° and 20°. The predetermined threshold may be any value between 30% and 1% of the first approach angle AG1 and / or the second approach angle AG2 (e.g., 45°) when the first lane L1 and the second lane L2 are perpendicular to each other. The predetermined threshold may be set based on the vehicle performance, such as the braking performance, of each vehicle. The predetermined threshold when the vehicle performance, including the detection performance, of the host vehicle V1 is high can be set to a lower value than the predetermined threshold when the vehicle performance is low. The predetermined threshold can be set according to the traveling speed. The predetermined threshold when the speed limit is high and the traveling speed is high is set to a higher value than the predetermined threshold when the traveling speed is low. Since the range of change in the approach angle tends to be large when the traveling speed (speed limit) is high, the driving control is executed even when the difference in the approach angle is large, taking into account the difference in the arrival time at the intersection SB. The driving speed is obtained from the sensor 2, and the speed limit of each lane is obtained from the map information 5. From a similar perspective, the predetermined threshold can be set according to the attributes of the first lane L1 or the second lane L2. The predetermined threshold when the driving lane is a road for vehicles only with high driving speeds, such as an expressway, is set to a higher value than the predetermined threshold when the driving lane is a national highway or a prefectural road. The predetermined threshold when the driving lane is a national highway or a prefectural road is set to a higher value than the predetermined threshold when the driving lane is an urban road. The predetermined threshold can also be set according to the detection environment. Since calculation errors in the approach angle tend to occur when the detection environment is poor, it is necessary to take into account the delay in the arrival time at the intersection SB. When the detection environment is poor, this driving control is executed even if the difference in approach angle is large. For example, the predetermined threshold when the detection environment is poor, such as after sunset, when the ambient illuminance is low (dark), or when it is raining or snowing, is set to a higher value than the predetermined threshold when the detection environment is good, such as before sunset, when the ambient illuminance is high (bright), or when it is sunny or cloudy. Illuminance is obtained from the illuminance meter of the sensor 2. Weather can be determined from images captured by the camera 21. Weather can be obtained from an external weather information server via the communication device 30. Whether it is before or after sunset can be determined based on the calendar (including the time of sunset) obtained via the communication device 30 and the current time obtained from the clock of the sensor 2.The calendar information including the sunset time can be acquired from an external calendar information providing server via the communication device 30. By setting the predetermined threshold in this manner taking into account the influence of the detection environment, the processor 10 can predict with high accuracy the approach between the host vehicle V1 and the other vehicle V2 at the intersection SB.

[0020] In S16 of FIG. 3, the processor 10 formulates a driving plan for driving control to accelerate or decelerate the host vehicle V1 so that the difference between the first approach angle AG1 and the second approach angle AG2 is equal to or greater than a predetermined threshold. Based on the first current position of the host vehicle V1, the second current position of the other vehicle V2, and the position of the intersection SB, the processor 10 calculates a target position and target timing for the host vehicle V1 so that the geometric difference between the first approach angle AG1 and the second approach angle AG2 is equal to or greater than the predetermined threshold, and calculates a target speed for the host vehicle V1 to reach the target position at the target timing before reaching the intersection SB. The processor 10 causes the host vehicle V1 to execute acceleration or deceleration control to set the current traveling speed to the target speed. When the host vehicle V1 reaches the target position at the target timing, the processor 10 terminates the acceleration or deceleration control and performs constant-speed driving at the set speed.

[0021] In step S16, the processor 10 formulates three driving plans according to the situation (S16). FIG. 3 shows processing procedures F1, F2, and F3 corresponding to each plan. In step F1, the processor 10 controls the host vehicle V1 to execute acceleration control or deceleration control in accordance with the driving plan formulated in S16 (S17). The acceleration or deceleration amount, or an upper limit thereof, can be set in advance. The acceleration or deceleration amount can be set according to the current vehicle speed. The acceleration or deceleration may be a predetermined percentage of the current vehicle speed, for example, 1 to 20% of the vehicle speed. This predetermined percentage may be set according to the current vehicle speed or vehicle performance. The processor 10 executes acceleration or deceleration control based on the set acceleration or deceleration until the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than a predetermined threshold (YES in S18) (S17). When the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than a predetermined threshold (NO in S18), the acceleration control or deceleration control is terminated (S19). After passing the intersection is confirmed (YES in S15), the process is terminated. In this driving control, when it is determined that the difference between the first approach angle AG1 and the second approach angle AG2 is less than the predetermined threshold, the host vehicle V1 is autonomously accelerated or decelerated so that the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than the predetermined threshold. This allows the timing at which the host vehicle V1 passes through the intersection SB to be shifted from the timing at which the other vehicle V2 passes through the intersection SB. As a result, the host vehicle V1 and the other vehicle V2 do not arrive at the intersection SB at approximately the same time on a so-called collision course, preventing the two vehicles from getting too close, and suppressing the occurrence of a collision phenomenon due to the driver's illusion.

[0022] When the processor 10 determines that the difference between the first approach angle AG1 and the second approach angle AG2 is less than a predetermined threshold, the processor 10 may set a virtual target passing position ahead of or behind the second current position of the second other vehicle V2 and control the host vehicle V1 so that the host vehicle V1 intersects with this target passing position at the intersection SB. The processor 10 calculates a first target approach angle formed by a target reference line connecting the first current position of the host vehicle V1 and the target passing position and the first lane L1, and a second target approach angle formed by the target reference line and the second lane. The processor 10 accelerates or decelerates the host vehicle V1 so that the difference between the first target approach angle and the second target approach angle becomes less than a predetermined threshold. The target passing position is a position where no object, such as a vehicle, is present. The host vehicle V1, accelerated or decelerated so that the difference between the first target approach angle and the second target approach angle becomes less than the predetermined threshold, passes the virtual target passing position, where no object actually exists, at the intersection SB. In other words, the host vehicle V1 does not come too close to another vehicle V2 that actually exists before or after the target passing position at the intersection SB. By accelerating or decelerating the host vehicle V1 so that the difference between the first target approach angle and the second target approach angle becomes less than a predetermined threshold, the difference between the first approach angle AG1 and the second approach angle AG2 can be made equal to or greater than the predetermined threshold. In this way, by accelerating or decelerating the host vehicle V1 so that the target passing position set before or after the other vehicle V2 and the host vehicle V1 intersect at the intersection SB, the host vehicle V1 and the other vehicle V2 that actually exists before or after the target passing position can be prevented from coming too close to each other at the intersection SB.

[0023] Furthermore, when processor 10 starts or completes the execution of driving control to accelerate or decelerate host vehicle V1 in S17, processor 10 outputs information indicating that the execution of driving control has started or completed via output device 20b. For example, processor 10 may display text such as "Acceleration (or deceleration) begins," "Acceleration (or deceleration) begins to avoid a collision at the intersection," "Acceleration (or deceleration) completed," or "Acceleration (or deceleration) completed to avoid a collision at the intersection" on display 20b1, output a voice message via speaker 20b2, or turn on a predetermined lamp 20b3. This allows the driver to recognize that there was a possibility of a collision with another vehicle V2 at intersection SB on the collision course and that this was avoided by autonomous driving.

[0024] The processor 10 formulates a driving plan according to the priority relationship between the first lane L1 and the second lane L2 in accordance with process F2 of FIG. 3 and executes driving control in accordance with the plan. The processor 10 determines the relative priority of the first lane L1 and the second lane L2 by referring to the map information 5 (S20). The priority of each lane at the intersection SB is stored in the map information 5 or the lane information 51. The priority may be defined based on the attribute of each lane (national highway, prefectural road, farm road, urban road), the road width of each lane, or the traffic rule (priority / non-priority driving) associated with the identification information of each lane. The priority of a lane whose attribute is a national highway or prefectural road with heavy traffic volume is set higher than the priority of a lane whose attribute is a farm road or urban road with low traffic volume. The priority of a lane whose road width is wide is set higher than the priority of a lane whose road width is narrow. 4A shows a situation at intersection SB where the first lane L1 in which host vehicle V1 is traveling has priority over the second lane L2. Figure 4A shows a reference line BL connecting the current position of host vehicle V1 and the current position of another vehicle V2, a first approach angle AG1 between the first lane L1 and the reference line BL, a second approach angle AG2 between the second lane L2 and the reference line BL, a target passing position TV (Target Vehicle Position), a target reference line TBL connecting host vehicle V1 and the target passing position TV, a safety margin field MF (Safety Margin Field), a target passing field TVF (Target Vehicle Field), a target approach angle TAG (Target Angle), and an angle TAG' between the second lane L2 and the target reference line TBL(t1) at time t1. These symbols are commonly used in Figures 4B, 5A, 5B, 6A, and 6B. At timing t0, the processor 10 calculates a first approach angle AG1(t0) formed by a reference line BL(t0) connecting the first current position V1(t0) of the host vehicle V1 and the second current position V2(t0) of the other vehicle V2 and the first lane L1, and a second approach angle AG2(t0) formed by the reference line BL(t0) and the second lane L2. The second current position of the other vehicle V2 may be the center of the body of the other vehicle V2, the center of the vehicle length or width, a reference position of an other vehicle area occupied or predicted to be occupied by the other vehicle V2, or a reference position of a safety margin area MF set before and after the other vehicle area in the traveling direction.The size of the other vehicle area or safety margin area MF (length in the direction of travel and length in the road width direction) is set according to the lane attributes, the lane speed limit, the length of the other vehicle V2, and the vehicle attributes of the other vehicle V2 (truck, passenger car, etc.). If the lane is a vehicle-exclusive lane such as an expressway, the other vehicle area or safety margin area MF is set longer along the direction of travel than in other cases. If the lane speed limit is high, the other vehicle area or safety margin area MF is set longer along the direction of travel than in cases where the speed limit is low. If the vehicle attribute of the other vehicle V2 is a special vehicle such as a truck, the other vehicle area or safety margin area MF is set longer along the direction of travel than in cases where the vehicle attribute of the other vehicle V2 is a passenger car. If the vehicle length of the other vehicle V2 is long, the other vehicle area or safety margin area MF is set longer along the direction of travel than in cases where the vehicle length of the other vehicle V2 is short. The method for setting the other vehicle area or the safety margin area MF is the same as the examples in Figures 4B, 5A, 5B, 6A, and 6B. Returning to Figure 3, if the processor 10 determines that the difference between the first approach angle AG1 and the second approach angle AG2 is less than a predetermined threshold (YES in S14) and determines in the F2 process of creating a driving plan (S16) that traveling in the first lane L1 has priority over traveling in the second lane L2 (YES in S20), the processor 10 causes the host vehicle V1 to execute acceleration control in the traveling direction (+Y) (S21). At time t1 after acceleration control, for example, the first approach angle AG1(t1) between the first lane L1 and the reference line BL(t1) connecting the first current position V1(t1) of the host vehicle V1 and the second current position V2(t1) of the other vehicle V2 increases (for example, from 45° to 50°), and the second approach angle AG2(t1) between the reference line BL(t1) and the second lane L2 decreases (for example, from 45° to 40°). The difference between the first approach angle AG1(t1) and the second approach angle AG2(t1) becomes equal to or greater than a predetermined value. When the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than a predetermined threshold, the difference between the first approach angle AG1(t1) and the second approach angle AG2(t1) of the host vehicle V1 is made equal to or greater than the predetermined threshold by accelerating the host vehicle V1 traveling on the first lane L1, which is a priority road, and the positional relationship between the host vehicle V1 and the other vehicle V2 with respect to the intersection SB can be changed. As a result, the host vehicle V1 passes through the intersection SB before the other vehicle V2, and the other vehicle V2 passes through the intersection SB after the host vehicle V1.When it is predicted that the host vehicle V1 will come too close to another vehicle V2 at the intersection SB, the host vehicle V1 traveling on the priority road can be caused to execute acceleration control to resolve the situation. In this driving control, as shown in FIG. 4A , the processor 10 sets a target passing position TV in front of the other vehicle V2 and calculates a first target approach angle TAG1 between a target reference line TBL connecting the first current position of the host vehicle V1 and the target passing position TV and the first lane L1, and a second target approach angle TAG2 between the target reference line TBL and the second lane L2. The processor 10 accelerates or decelerates the host vehicle V1 so that the difference between the first target approach angle TAG1 and the second target approach angle TAG2 is less than a predetermined threshold. By accelerating the host vehicle V1 so that the host vehicle V1 and the target passing position TV intersect at the intersection SB, the host vehicle V1 and the other vehicles V2 before and after the target passing position TV can be prevented from coming too close to each other at the intersection SB. This method can also be applied to the acceleration control or deceleration control of S17, the deceleration control of S22, the acceleration control of S31, and the deceleration control of S32. The above description will be applied to each control to avoid redundant explanation. In this example, the target passing position TV is set in front of the other vehicle V2, but it may also be set behind the other vehicle V2.

[0025] In such a situation, as an example of processing, but not limited to, the processor 10 (1) acquires the position coordinates (xV2(t0), yV2(t0)) of the other vehicle V2(t0), (2) calculates the first approach angle AG1(t0) and the second approach angle AG2(t0) from the relationship between the position coordinates of the host vehicle V1(t0) and the other vehicle V2(t0), and determines whether a collision course phenomenon is occurring. For example, the processor 10 determines whether the first approach angle AG1(t0) and the second approach angle AG2(t0) are both near 45 degrees, or whether the difference between them is less than a predetermined value. The processor 10 (3) adds a safety margin area MF ahead of the other vehicle V2(t0) and sets a target passing position TV ahead of the safety margin area MF, taking into account the size of the host vehicle V1, when a collision course phenomenon is occurring and the first lane L1 on which the host vehicle V1 is traveling is a priority road. The processor 10 (4) draws a target reference line TBL(t0) connecting a target passing position TV(xTV(t0), yTV(t0)), such as the center of the target setting region TVF, with the position coordinates (xV1(t0), yV1(t0)) of the host vehicle V1(t0), and determines the angle between the second lane L2 and the target reference line TBL(t0) as the target approach angle TAG. The processor 10 then uses the vehicle actuator 200 to (5) accelerate the host vehicle V1 so that the first approach angle AG1 becomes the target approach angle TAG. If the first approach angle AG1 becomes the target approach angle TAG, the host vehicle V1 can pass through the intersection SB earlier than the other vehicle V2 (the host vehicle V1 is closer to the intersection SB than the other vehicle V2), and therefore determines that the host vehicle V1 has escaped the collision course phenomenon.

[0026] FIG. 4B illustrates a situation in which the second lane L2, on which the other vehicle V2 is traveling, has priority over the first lane L1 at the intersection SB. The first lane L1 is a non-priority road. If the processor 10 determines that the difference between the first approach angle AG1 and the second approach angle AG2 is less than a predetermined threshold (YES in S14), and if the processor 10 determines, by referring to the map information 5, that the second lane L2 has priority over the first lane L1 (NO in S20), it causes the host vehicle V1 to execute deceleration control (S22). The deceleration control of the host vehicle V1 changes the positional relationship between the host vehicle V1 and the other vehicle V2 with respect to the intersection SB. After the deceleration control, for example, at timing t1, the first approach angle AG1(t1) between the reference line BL(t1) and the first lane L1 decreases (e.g., from 45° to 40°), and the second approach angle AG2(t1) increases (e.g., from 45° to 50°), so that the difference between the two becomes equal to or greater than a predetermined value. When the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than a predetermined threshold, the host vehicle V1 traveling on the first lane L1, which is a non-priority road, is decelerated to make the difference between the first approach angle AG1(t1) and the second approach angle AG2(t1) of the host vehicle V1 equal to or greater than the predetermined threshold, thereby changing the positional relationship between the host vehicle V1 and the other vehicle V2 with respect to the intersection SB. As a result, the other vehicle V2 passes through the intersection SB before the host vehicle V1, and the host vehicle V1 passes through the intersection SB after the other vehicle V2. When it is predicted that the host vehicle V1 will come too close to the other vehicle V2 at the intersection SB, the host vehicle V1 traveling on the non-priority road can be caused to execute deceleration control to resolve the situation. The processor 10 executes acceleration control (S21) or deceleration control (S22) until the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than the predetermined threshold (YES in S23). When the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than a predetermined threshold value (NO in S23), the acceleration control or deceleration control is terminated (S19) and the process proceeds to S15.

[0027] In such a situation, processor 10 performs (1) and (2) in a manner similar to the example of the above processing, although not particularly limited thereto. Processor 10 then (3) adds a safety margin area MF behind vehicle V2(t0) if the collision course phenomenon occurs and the first line L1 on which the host vehicle is traveling is a non-priority road, and sets a target passing position TV behind the other vehicle V2(t0) taking into account the size of the host vehicle. Processor 10 then (4) draws a target reference line TBL(t0) connecting the target passing position TV(xTV(t0), yTV(t0)), such as the center of the target setting area TVF(t0), to the position coordinates (xV1(t0), yV1(t0)) of the host vehicle V1(t0), and sets the angle between second lane L2 and target reference line TBL(t0) as the target approach angle TAG. Processor 10 then (5) uses vehicle actuator 200 to decelerate vehicle V1 so that first approach angle AG1 becomes the target approach angle TAG. If the first approach angle AG1 becomes the target approach angle TAG, the timing at which the host vehicle V1 passes through the intersection SB can be delayed compared to the other vehicle V2 (the host vehicle V1 is farther from the intersection SB than the other vehicle V2), and it is determined that the host vehicle V1 has escaped the collision course phenomenon.

[0028] According to process F3 of Fig. 3, processor 10 formulates a driving plan according to the distance between the first current position of host vehicle V1 and intersection SB, and executes driving control in accordance with the plan. Fig. 5A shows an example of a situation in which process F3 taking into account the distance to intersection SB is executed. At timing t0, processor 10 calculates a first approach angle AG1(t0) formed by a reference line BL(t0) connecting the first current position V1(t0) of host vehicle V1 and the second current position V2(t0) of another vehicle V2, and a first lane L1, and a second approach angle AG2(t0) formed by the reference line BL(t0) and a second lane L2. At timing t0, processor 10 acquires a distance D1 between the first current position and intersection SB. If the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than a predetermined threshold and the distance D1 is equal to or greater than a predetermined distance TH1, the processor 10 causes the host vehicle V1 to execute acceleration control in the traveling direction (+Y). After the acceleration control, for example, at timing t1, the first approach angle AG1(t1) increases (e.g., from 45° to 50°) and the second approach angle AG2(t1) decreases (e.g., from 45° to 40°). As a result, the difference between the first approach angle AG1(t1) and the second approach angle AG2(t1) becomes equal to or greater than a predetermined value. The predetermined distance TH1, which serves as the threshold in this processing example, can be set in advance. The predetermined distance TH1 is set to a value equal to or less than the detectable distance of the sensor 2. For example, if the detectable distance of the sensor 2 is approximately 300 m, the predetermined distance TH1 can be set to approximately 200 m to 280 m. Explaining this with reference to the flowchart of FIG. 3 , the processor 10 acquires the distance between the first current position and the intersection SB using the sensor 2. If the difference between the first approach angle AG1 and the second approach angle AG2 is less than a predetermined threshold (YES in S14) and, in process F3 of creating a driving plan (S16), the acquired distance between the first current position and the intersection SB is equal to or greater than a predetermined distance TH1 (YES in S30), the processor 10 causes the host vehicle V1 to execute acceleration control (S31). If the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than the predetermined threshold and the distance from the first current position of the host vehicle V1 to the intersection SB is equal to or greater than the predetermined distance TH1, the processor 10 causes the host vehicle V1 to execute acceleration control, thereby increasing the first approach angle AG1 and changing the positional relationship between the host vehicle V1 and the other vehicle V2 with respect to the intersection SB.As a result, the host vehicle V1 passes through the intersection SB earlier (at an earlier timing) than the other vehicle V2, thereby avoiding close contact with the other vehicle V2 at the intersection SB. By utilizing the long distance to the intersection SB, the host vehicle V1 can be prevented from close contact with the other vehicle V2 by performing acceleration driving control with a low acceleration / acceleration amount.

[0029] In such a situation, processor 10 performs steps (1) and (2) in the same manner as in the example of the above processing, although this is not particularly limited. Processor 10 then (3) adds a safety margin area MF ahead of vehicle V2(t0) if the collision course phenomenon is occurring, there is no road type (priority / non-priority), and the vehicle V1 and vehicle V2 are traveling at least the distance from intersection SB. Processor 10 then (4) draws a target reference line TBL(t0) connecting the target passing position TV(xTV(t0), yTV(t0)), such as the center of target setting area TVF(t0), with the position coordinates (xV1(t0), yV1(t0)) of vehicle V1(t0), and determines the angle between second lane L2 and target reference line TBL(t0) as the target approach angle TAG. The processor 10 (5) uses the vehicle actuator 200 to accelerate the host vehicle V1 so that the first contact angle AG1 becomes the target approach angle TAG. When the first approach angle AG1 becomes the target approach angle TAG, the host vehicle V1 can pass through the intersection SB earlier than the other vehicle V2 (the host vehicle V1 is closer to the intersection SB than the other vehicle V2), and therefore determines that the host vehicle V1 has escaped from the collision course phenomenon. In this way, the host vehicle V1 can determine the situation from a distance from the intersection SB, determine that it is on a collision course, and resolve the situation.

[0030] 5B shows a situation in which the distance D1 between the first current position V1(t0) and the intersection SB is less than the predetermined distance TH1. At timing t0, the processor 10 calculates a first approach angle AG1(t0) between the reference line BL(t0) and the first lane L1 and a second approach angle AG2(t0) between the reference line BL(t0) and the second lane L2. If the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than the predetermined threshold (YES in S14), and if the distance D1 from the first current position V1(t0) of the host vehicle V1 to the intersection SB is less than the predetermined distance TH1 in step F3 of the driving plan development (S16) (NO in S30), the processor 10 causes the host vehicle V1 to execute deceleration control (S32). After the deceleration control, for example, at timing t1, the first approach angle AG1(t1) decreases (e.g., from 45° to 40°), and the second approach angle AG2(t1) increases (e.g., from 45° to 50°). As a result, the difference between the first approach angle AG1(t1) and the second approach angle AG2(t1) becomes equal to or greater than a predetermined value. Note that if the distance D1 between the first current position of the host vehicle V1 and the intersection SB is less than a predetermined distance TH2 (TH2<TH1), the host vehicle V1 may be determined to be approaching the intersection SB, and the host vehicle V1 may be stopped. As an example, TH1 is 230 m to 280 m, and TH2 is 1 m to 5 m. The distance D1 may be measured using the stop line at the intersection SB as a reference point. When the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than a predetermined threshold and the distance D1 from the first current position of the host vehicle V1 to the intersection SB is less than a predetermined distance TH1, the host vehicle V1 is caused to execute deceleration control to reduce the first approach angle AG1 and change the positional relationship between the host vehicle V1 and the other vehicle V2 with respect to the intersection SB. As a result, the host vehicle V1 is caused to pass the intersection SB later (at a later timing) than the other vehicle V2, thereby avoiding close contact with the other vehicle V2 at the intersection SB. When the distance D1 to the intersection SB is short, the arrival of the host vehicle V1 at the intersection SB is delayed, thereby avoiding close contact with the other vehicle V2 at the intersection SB. Referring to the flowchart of FIG. 3 , the processor 10 continues executing the acceleration control (S31) or the deceleration control (S32) until the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than a predetermined threshold (YES in S33).When the difference between the first approach angle AG1 and the second approach angle AG2 becomes equal to or greater than a predetermined threshold value (NO in S33), the acceleration control or deceleration control is terminated (S19) and the process proceeds to S15.

[0031] In such a situation, as in one example of processing, but not limited to, processor 10 performs (1) and (2), and (3) if the collision course phenomenon is occurring, there is no road type (priority / non-priority), and the traveling positions of host vehicle V1 and other vehicle V2 are within a predetermined distance from intersection SB and outside intersection SB, processor 10 adds a safety margin area MF behind other vehicle V2(t0) and sets a target passing position TV further behind that, taking into account the size of host vehicle V1. Processor 10 then (4) draws a target reference line TBL(t0) connecting the target passing position TV(xTV(t0), yTV(t0)), such as the center of the target setting area TVF(t0), and the position coordinates (xV1(t0), yV1(t0)) of host vehicle V1(t0), and sets the angle between lane L2 and target reference line TBL(t0) as the target approach angle TAG. Processor 10 (5) uses vehicle actuator 200 to decelerate host vehicle V1 so that first approach angle AG1 becomes target approach angle TAG. When first approach angle AG1 becomes target approach angle TAG, host vehicle V1 can pass intersection SB later than other vehicle V2 (host vehicle V1 is farther from intersection SB than other vehicle V2), and therefore determines that the host vehicle V1 has escaped the collision course phenomenon. Here, at time t1, the angle TAG' between second lane L2 and target reference line TBL(t1) is 45 degrees.

[0032] Second Embodiment In the second embodiment, driving control when multiple other vehicles V2 are traveling in the second lane L2 will be considered. Fig. 6A shows a situation in which two other vehicles V2 and V3 are present in the second lane L2, and shows a second current position V2(t0) of the other vehicle V2 and a second current position V3(t0) of the other vehicle V3 at timing t0. A safety margin area MF1(t0) is set along the rear direction of the leading other vehicle V2, a target setting area TVA(t0) including a target passing position TV(t0), and a safety margin area MF2(t0) is set along the traveling direction of the other vehicle V3 following the other vehicle V2. At timing t0, the processor 10 calculates a first approach angle AG1(t0) formed by a reference line BL2 connecting a first current position V1(t0) of the host vehicle V1 and a second current position V2(t0) of the other vehicle V2 and the first lane L1, and a second approach angle AG2(t0) formed by the reference line BL2 and the second lane L2. The processor 10 acquires the current positions of multiple other vehicles, including a first other vehicle V2 and a second other vehicle V3, traveling on the second lane L2. The processor 10 calculates a reference line BL connecting the first current position V1(t0) of the host vehicle V1 and the second current position V2(t0) of the first other vehicle V2. The processor 10 calculates a first approach angle AG1(t0) formed by the reference line BL2(t0) and the first lane L1, and a second approach angle AG2(t0) formed by the reference line BL and the second lane L2. When the difference between the first approach angle AG1(t0) and the second approach angle AG2(t0) is less than a predetermined threshold, the processor 10 sets a target passing position TV(t0) between the first other vehicle V2 and the second other vehicle V3. The target passing position TV(t0) is a virtual control point where the other vehicles V2 and V3 are not present. The processor 10 formulates a driving plan for accelerating or decelerating the host vehicle V1 so that the difference between the target approach angle TAG and the approach angle AG1 is less than the predetermined threshold, and causes the host vehicle V1 to execute driving control based on the plan. In the situation shown in FIG. 6A, the processor 10 may perform similar processing by replacing the position of the second other vehicle V3 with the position of the second other vehicle V2. According to the driving control of this embodiment, even when multiple other vehicles V2 and V3 are traveling in a line on the second lane L2 of the collision course, the host vehicle V1 is controlled to pass the virtual target passing position TV set between the other vehicles V2 and V3 at the intersection SB.This allows the host vehicle V1 to pass through the intersection SB after the other vehicle V2 has passed through the intersection SB, slipping between the other vehicles V2 and V3 before the other vehicle V3 has passed through the intersection SB. In other words, the host vehicle V1 can be prevented from getting too close to the other vehicles V2 and V3 at the intersection SB. In order for the host vehicle V1 to pass through the intersection SB at a different timing than the other vehicles V2 and V3 traveling in the second lane L2, the processor 10 calculates a target position and target timing for the host vehicle V1 that satisfy both a condition regarding the other vehicles V2 and V3 that the difference between the first approach angle AG1 and the second approach angle AG2 is equal to or greater than a predetermined threshold, and a condition that the difference from the target approach angle TAG is less than a predetermined threshold. The processor 10 calculates a target speed for reaching the target position at the target timing, and executes acceleration or deceleration control to set the current vehicle speed to the target speed.

[0033] In such a situation, as an example of processing, but not limited to, processor 10 (1) acquires the position coordinates (xV2(t0), yV2(t0)) and (xV3(t0), yV3(t0)) of other vehicles V2(t0) and V3(t0), respectively. Processor 10 (2) calculates the first approach angle AG1(t0), the second approach angle AG2(t0), and the AG3(t0) from the relationship between the position coordinates of host vehicle V1(t0) and other vehicles V2(t0) and V3(t0), and determines whether a collision course phenomenon is occurring. For example, processor 10 determines whether the first approach angle AG1(t0) and the second approach angles AG2(t0), and AG3(t0) are both near 45 degrees, or whether the difference between them is less than a predetermined value. In the case of a collision course phenomenon with another vehicle V2(t0), when another vehicle V3(t0) is traveling behind the other vehicle V2(t0), the processor 10 (3) sets a target passing position TV between the other vehicles V2(t0) and V3(t0) taking into consideration the size of the own vehicle V1 so that the own vehicle V1 can pass safely between the other vehicles V2(t0). The target passing position TV may be midway between the other vehicles V2(t0) and V3(t0). Alternatively, a safety margin area MF1(t0) may be set behind the leading vehicle V2(t0), a safety margin area MF2(t0) may be set in front of the following vehicle V3(t0), and a target setting area TVA(t0) including the target passing position TV(t0) may be set between the two safety margin areas MF1(t0), MF2(t0). The processor 10 (4) draws a target reference line TBL connecting the target passing position TV(xTV(t0), yTV(t0)) included in the target setting area TVA(t0) with the position coordinates (xV1(t0), yV1(t0)) of the host vehicle V1(t0), and sets the angle between the second lane L2 and the target reference line TBL to the target approach angle TAG. The processor 10 uses the vehicle actuator 200 to (5) decelerate the host vehicle V1 so that the first approach angle AG1 becomes the target approach angle TAG. If the first approach angle AG1 becomes the target approach angle TAG, the host vehicle V1 can pass the intersection SB later than the other vehicle V2 and pass the intersection SB before the other vehicle V3, thereby avoiding the collision course phenomenon.

[0034] FIG. 6B shows an example in which the distance between the other vehicle V2 and the other vehicle V3 in the situation of FIG. 6A is shorter than a predetermined inter-vehicle distance. The processing for the other vehicle V2 is the same as in FIG. 6A. As in the example of FIG. 6A, the processor 10 calculates the difference between the second approach angle AG2(t0) and the first approach angle AG1(t0). If the difference is less than a predetermined threshold and the inter-vehicle distance between the other vehicle V2 and the other vehicle V3 is less than the predetermined inter-vehicle distance, the processor 10 sets a target passing position TV(t0), which is a virtual control point, behind the current position V2(t0) of the first other vehicle V2 and the current position V3(t0) of the second other vehicle V3. A target passing region TVF including the target passing position TV(t0) may be set. The processor 10 calculates a first target approach angle TAG1 between a target reference line TBL connecting a first current position V1(t0) of the host vehicle V1 and a target passing position TV(t0) and a first lane L1, and a second target approach angle TAG2 between the target reference line TBL(t0) and a second lane L2. The processor 10 continuously calculates the difference between the first target approach angle TAG1 and the second target approach angle TAG2 at a predetermined period. The processor 10 formulates a driving plan for accelerating or decelerating the host vehicle V1 so that the difference between the first target approach angle TAG1 and the second target approach angle TAG2 becomes less than a predetermined threshold at a timing t1 after the timing t0, and causes the host vehicle V1 to execute driving control based on the plan.

[0035] In such a situation, as an example of processing, and not limited to this, the processor 10 (1) acquires the position coordinates (xV2(t0), yV2(t0)) and (xV3(t0), yV3(t0)) of the other vehicles V2(t0) and V3(t0), respectively, and (2) calculates the approach angles AG1(t0), AG2(t0), and AG3(t0) from the relationship between the position coordinates of the subject vehicle V1(t0) and the other vehicles V2(t0) and V3(t0), and determines whether or not a collision course phenomenon is occurring. For example, it is determined whether AG1(t0) and AG2(t0) are both near 45 degrees, or whether the difference between them is less than a predetermined value. (3) When the vehicle is on a collision course with another vehicle V2(t0), but another vehicle V3(t0) is traveling behind the other vehicle V2(t0), and the inter-vehicle distance between the other vehicle V2(t0) and the other vehicle V3(t0) is less than a predetermined distance, the processor 10 sets a target passing position TV behind the other vehicle V3(t0) even though the other vehicle V2(t0) is on a collision course. In this case, a safety margin area MF is set behind the other vehicle V3(t0), and a target passing position TV is set further behind that, taking into account the size of the host vehicle V1. (4) The processor 10 compares the target passing position TV(xTV(t0), yTV(t0)), such as the center of the target setting area TVF(t0), with the position coordinates (xV1(t0), yTV(t0)) of the host vehicle V1(t0). A target reference line TBL(t0) is drawn connecting the second lane L2 and the target reference line TBL(t0), and the angle between the second lane L2 and the target reference line TBL(t0) is set as the target approach angle TAG. (5) The processor 10 uses the vehicle actuator 200 to decelerate the host vehicle V1 so that the first approach angle AG1 becomes the target approach angle TAG. If the first approach angle AG1 approximates the target approach angle TAG, the host vehicle V1 is determined to have passed the intersection SB later than the other vehicles V2 and V3, and thus has escaped the collision course phenomenon. According to the driving control of this embodiment, even if multiple other vehicles V2 and V3 are traveling in a line on the second lane L2 of the collision course, the host vehicle V1 is controlled to pass the virtual target passing position TV set behind the other vehicles V2 and V3 at the intersection SB. This allows the host vehicle V1 to pass the intersection SB after the other vehicles V2 and V3 have passed the intersection SB.At the intersection SB, the host vehicle V1 can be prevented from getting too close to the other vehicles V2 and V3. While the examples in FIGS. 6A and 6B show multiple other vehicles traveling in only one lane of the second lane L2, this driving control method for setting a target passing position can also be applied to situations where multiple other vehicles are traveling in lanes of the second lane L2 in other directions. The processor 10 calculates a target position and target timing for the host vehicle V1 that satisfy multiple conditions under which the difference between the second target approach angle TAG2 and the first target approach angle TAG1 for the target passing position in the second lane in one or two directions is less than a predetermined threshold. If a solution to the multiple conditions cannot be obtained, the host vehicle V1 is decelerated or stopped.

[0036] Third Embodiment In the driving control of the first and second embodiments, the processor 10 executes acceleration or deceleration control of the host vehicle V1 (S17, S21, S22, S31, and S32 in FIG. 3 ) when it determines that no obstacles exist in a predetermined range between the first lane L1 and the second lane L2, which is a predetermined range based on the intersection SB. In the example shown in FIG. 2 , the predetermined range is a triangular area surrounded by the first lane L1, the second lane L2, and the reference line BL(t0), or a triangular area surrounded by the first lane L1, the second lane L2, and the reference line BL(t1). As shown in FIG. 2B , if an obstacle BD, such as a building or other structure, exists in the predetermined range surrounded by the first lane L1, the second lane L2, and the reference line BL(t0 / t1), the obstacle BD may block the acquisition of image information and measurement information by the sensor 2 of the host vehicle V1. In such a case, the first approach angle AG1, the second approach angle AG2, and the like cannot be accurately calculated. It cannot be recognized even by a person in the host vehicle V1. Such a situation is determined not to be a collision course phenomenon caused by a human optical illusion, and driving assistance control is not performed, with driving remaining at the driver's discretion. Driving control of acceleration or deceleration is performed only when there is no obstacle BD that blocks the transmission and reception of a detection signal from the host vehicle V1 traveling in the first lane L1 to another vehicle V2 traveling in the second lane L2, and when an obstacle BD is present, acceleration or deceleration control is not performed, thereby ensuring the execution of appropriate driving control.

[0037] Fourth Embodiment In the driving control of the first and second embodiments, the processor 10 executes driving control to accelerate or decelerate the vehicle V1 when it determines that the evaluation value of the detected environment around the vehicle V1 is equal to or greater than a predetermined evaluation value. The detected environment includes the ambient illuminance (brightness), weather (sunny, cloudy, rainy, or snowy), or time of day (around sunset). If the detected environment is poor, the accuracy of the detection information from the sensor 2 decreases, making it difficult to accurately calculate the first approach angle AG1, the second approach angle AG2, and so on. The processor 10 executes driving control when the illuminance acquired using the illuminance meter of the sensor 2 is equal to or greater than a predetermined value, and does not execute driving control when the illuminance is less than the predetermined value. The processor 10 executes driving control when the weather is sunny or cloudy, and does not execute driving control when the weather is rainy or snowy. The processor 10 executes driving control when the time is before sunset, and does not execute driving control when the time is after sunset. The processor 10 may acquire the sunset time for the current location by referring to calendar information in which locations and sunset times are previously associated with each other, or may acquire the sunset time for the current location by referring to calendar information in an external server via the communication device 30. Since the driving control is executed when the detection environment is good, it is possible to ensure that the driving control is executed appropriately.

[0038] 100... driving control system, 1... driving assistance device, 10... processor, 11... CPU, 12... ROM, 13... RAM, 20a... input device, 20b... output device, 20b1... display, 20b2... speaker, 20b3... lamp, 30... communication device, 2... sensor, 21... camera, 22... radar device, 3... vehicle information acquisition device, 4... other vehicle information acquisition device, 5... map information, 51... lane information, 6... navigation device, 200... vehicle actuator, 210... steering control device, 220... drive control device, 230... braking control device

Claims

1. A driving assistance method used in a processor to control autonomous driving of a host vehicle, wherein the processor: acquires a first current position of the host vehicle; identifies a first lane in which the host vehicle is traveling; acquires a second current position of another vehicle traveling in a second lane that intersects the first lane at an intersection ahead of the host vehicle in the traveling direction; calculates a first approach angle between the first lane and a reference line connecting the first current position and the second current position, and a second approach angle between the reference line and the second lane; and, if it is determined that the difference between the first approach angle and the second approach angle is less than a predetermined threshold, accelerates or decelerates the host vehicle so that the difference between the first approach angle and the second approach angle is equal to or greater than the predetermined threshold.

2. The driving assistance method according to claim 1, wherein the processor determines the relative priority of the first lane and the second lane by referring to map information, and accelerates the host vehicle if it determines that the first lane has priority over the second lane.

3. The driving assistance method according to claim 1, wherein the processor determines the relative priority of the first lane and the second lane by referring to map information, and decelerates the host vehicle if it determines that the second lane has priority over the first lane.

4. The driving assistance method according to claim 1, wherein the processor accelerates the host vehicle when the distance between the first current position and the intersection is equal to or greater than a predetermined distance.

5. The driving assistance method according to claim 1, wherein the processor decelerates the host vehicle when the distance between the first current position and the intersection is less than a predetermined distance.

6. A driving assistance method according to any one of claims 1 to 5, wherein, when it is determined that the difference between the first approach angle and the second approach angle is less than a predetermined threshold, the processor sets a target passing position in front of or behind the second current position of the other vehicle, calculates a first target approach angle formed by a target reference line connecting the first current position and the target passing position of the host vehicle and the first lane, and a second target approach angle formed by the target reference line and the second lane, and accelerates or decelerates the host vehicle so that the difference between the first target approach angle and the second target approach angle is less than a predetermined threshold.

7. A driving assistance method according to any one of claims 1 to 5, wherein, when a plurality of other vehicles including a first other vehicle and a second other vehicle are traveling on the second lane and it is determined that the difference between the first approach angle and the second approach angle is less than a predetermined threshold, the processor sets a target passing position between the first other vehicle and the second other vehicle, calculates a first target approach angle between a target reference line connecting the first current position of the host vehicle and the target passing position and the first lane, and a second target approach angle between the target reference line and the second lane, and accelerates or decelerates the host vehicle so that the difference between the first target approach angle and the second target approach angle is less than a predetermined threshold.

8. A driving assistance method according to any one of claims 1 to 7, wherein the processor outputs a signal via an output device when execution of driving control to accelerate or decelerate the vehicle has started or completed.

9. A driving assistance method according to any one of claims 1 to 8, wherein the processor accelerates or decelerates the host vehicle when it determines that no obstacles exist in an area between the first lane and the second lane, which is a predetermined range based on the intersection.

10. A driving assistance method according to any one of claims 1 to 9, wherein the processor accelerates or decelerates the vehicle when it determines that the evaluation value of the detected environment around the vehicle is equal to or greater than a predetermined evaluation value.

11. A driving assistance device comprising a processor for controlling autonomous driving of a host vehicle, wherein the processor: acquires a first current position of the host vehicle; identifies a first lane in which the host vehicle is traveling; determines a second current position of another vehicle traveling in a second lane that intersects the first lane at an intersection ahead of the host vehicle in the traveling direction; calculates a first approach angle between the first lane and a reference line connecting the first current position and the second current position, and a second approach angle between the reference line and the second lane; and, when it is determined that the difference between the first approach angle and the second approach angle is less than a predetermined threshold, accelerates or decelerates the host vehicle so that the difference between the first approach angle and the second approach angle is equal to or greater than the predetermined threshold.

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