Driving assistance method and driving assistance device

Abstract

A driving assistance method is used in a processor 10 and is for controlling autonomous driving of a host vehicle V1. The processor 10: acquires detection information about the environment of the host vehicle V1 by using a sensor 2; executes first driving control for changing the behavior of the host vehicle V1 when it is assessed, on the basis of the detection information, that the host vehicle V1 and other vehicles VF2, VR2 are in a first proximate state; determines that the other vehicles VF2, VR2 are committing aggressive driving when it is assessed, on the basis of the detection information acquired after the execution of the first driving control, that the host vehicle V1 and the other vehicles VF2, VR2 are in a second proximate state; and outputs the determination result.

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] 2. Description of the Related Art A technique is known in which a vehicle changes lanes to a recommended lane when it is determined that a following vehicle is rapidly approaching the vehicle based on the distance between the vehicle and the host vehicle.

[0003] Patent No. 6821705

[0004] However, even if another vehicle approaches your vehicle, it is possible that the approach is unavoidable due to driving conditions, and it is not possible to determine with high accuracy whether the other vehicle is driving with the intention of tailgating your vehicle.

[0005] The problem to be solved by the present invention is to determine with high accuracy whether or not another vehicle is being driven with the intention of tailgating the subject vehicle.

[0006] The present invention solves the above problem by executing a first driving control that changes the behavior of the vehicle when it is determined that the vehicle and another vehicle are in a first approach state, and determining that the other vehicle is tailgating when it is determined that the vehicle and another vehicle are in a second approach state based on detection information obtained after the first driving control is executed, and outputting the result of the determination.

[0007] According to the present invention, it is possible to determine with high accuracy whether another vehicle is being driven with the intention of tailgating one's own vehicle.

[0008] FIG. 1 is a block diagram showing a hardware configuration of a driving assistance system; FIG. 2 is a first flowchart showing a processing procedure of driving assistance; FIG. 3 is a second flowchart showing a processing procedure of driving assistance; FIG. 4 is a first diagram explaining the content of driving assistance; and FIG. 5 is a second diagram explaining the content of driving assistance.

[0009] FIG. 1 shows the hardware configuration of a driving assistance system 100 including 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 assistance system 100. The driving assistance 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. 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 performs 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 autonomous or manual driving control.

[0011] The driving assistance 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 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 including the lane information 51 that is referenced when performing autonomous or manual 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 is traveling. The route and target trajectory calculated by the navigation device 6 are provided to the vehicle actuator 200 and used for autonomous or manual driving control.

[0012] The driving assistance system 100 includes a vehicle actuator 200. The vehicle actuator 200 includes a steering control device 210 and a drive control device 220, 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 (hereinafter, any of the steering angle, steering speed, or steering acceleration will be collectively referred to as the steering amount) when driving the vehicle. The vehicle actuator 200 controls the behavior of the vehicle and the behavior of the wheels according to the input command value so that the host vehicle autonomously travels along a route to the destination. Based on these controls, at least one of the drive actuator and the braking actuator of the drive mechanism of the vehicle body controlled by the drive control device 220, and the steering actuator of the steering control device 210 as necessary, operate autonomously, and autonomous driving control is executed to make the vehicle autonomously travel along a target trajectory. Also, the vehicle actuator 200 can execute driving according to 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 assistance system 100 controls autonomous driving of the vehicle to travel a target trajectory or assists manual driving. The processor 10 included in the driving assistance device 1 includes a read-only memory (ROM) 12 that stores a program for controlling autonomous driving, a central processing unit (CPU) 11 that executes the program stored in the ROM 12, and a random access memory (RAM) 13 that functions as an accessible storage device. The processor 10 implements the driving assistance method using each piece of hardware in the driving assistance system 100. The processor 10 of the driving assistance device 1 executes the functions of determining a first approach state, executing first driving control, determining a second approach state, and executing second driving control in cooperation with the hardware shown in FIG. 1 to execute each function. The driving assistance device 1 includes an input device 20a and an output device 20b. The input device 20a includes a steering wheel, brakes, indicators, 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 executes communication between the driving assistance device 1 and an external device, and communication between the devices included in the driving assistance system 100.

[0014] The processor 10 determines whether the host vehicle and the other vehicle are in a first approach state based on the detection information from the sensor 2. If it is determined that the host vehicle and the other vehicle are in the first approach state, the processor 10 executes a first driving control that changes the behavior of the host vehicle. If it is determined that the host vehicle and the other vehicle are in a second approach state based on the detection information acquired after the execution of the first driving control, the processor 10 determines that the other vehicle is engaging in aggressive driving (aggressive driving, inciting driving, tailgating, road rage driving, erratic driving). The processor 10 outputs the result of the determination. In this embodiment, "inciting driving" refers to obstructive driving that disrupts traffic. Inciting driving is performed with the purpose of obstructing the travel of other vehicles. "Inciting driving" is performed with the intention of obstructing the travel of a specific vehicle (e.g., the host vehicle). Inciting driving includes driving in which a vehicle in front slows down to obstruct the travel of the host vehicle, or driving in which a vehicle behind accelerates and follows the host vehicle (tailgating). Tailgating is not something that is unavoidable due to traffic congestion or other driving conditions, but rather it incites and frightens drivers of other vehicles, preventing them from driving safely and inducing unintentional driving that they would not normally engage in. Tailgating is malicious and dangerous driving intentionally performed by the driver of another vehicle, and is driving that disrupts peaceful traffic. Tailgating also involves driving that causes violations of traffic rules, such as failure to maintain a safe distance between vehicles, violations of the prohibition on sudden braking, violations of the minimum speed limit (on expressways), parking violations on expressways, violations of traffic zones, and violations of the prohibition on changing lanes.

[0015] The control procedure of the processor 10 will be described with reference to the flowchart of FIG. 2. The processor 10 acquires detection information about the surroundings of the host vehicle 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 observation information from the radar device 22. The processor 10 acquires host vehicle information about the behavior of the host vehicle from the host vehicle information acquisition device 3 (S2). The host vehicle information includes at least one of the host vehicle's current position, movement amount, movement direction, attitude, speed, and acceleration, and changes therein. The processor 10 acquires other vehicle information about the behavior of other vehicles from the other vehicle information acquisition device 4 (S3). The other vehicle information includes at least one of the current position, movement amount, movement direction, attitude, speed, and acceleration, and changes therein, of other vehicles surrounding the host vehicle. The processor 10 references the lane information 51 in the map information 5 and identifies the lane in which the host vehicle is traveling based on the host vehicle's current position. The processor 10 determines whether other vehicles are present ahead of or behind the host vehicle in the lane in which the host vehicle is traveling (S4). If there are no other vehicles in front of or behind the host vehicle on the driving lane (NO in S4), the process ends. On the other hand, if there are other vehicles in front of or behind the host vehicle on the driving lane (YES in S4), processor 10 identifies the other vehicles traveling on the driving lane (S5). Processor 10 determines the positional relationship between the host vehicle and the other vehicles based on the detection information (S6). Processor 10 repeatedly calculates the relative distance, relative speed, relative acceleration, and relative jerk between the position of the host vehicle and the other vehicles, and continuously determines the positional relationship between the host vehicle and the other vehicles at a predetermined cycle.

[0016] The processor 10 determines whether the host vehicle and the other vehicle are in a first approach state based on the detection information (S7). The first approach state can be defined by a degree of approach based on one or more of the following: the distance in the traveling direction between the host vehicle and the other vehicle, the time-to-collision (TTC) calculated from the relative speed and relative distance between the host vehicle and the other vehicle, the relative speed between the host vehicle and the other vehicle, the distance in the road width direction between the host vehicle and the other vehicle, and whether the lanes in which the host vehicle and the other vehicle are traveling are the same or different. For example, the first approach state can be defined using one or more of the following: a state in which the distance along the traveling direction between the host vehicle and the other vehicle is less than a first longitudinal threshold (distance); a state in which the TTC (Time-To-Collision) based on the relative speed and relative distance between the host vehicle and the other vehicle is less than a first longitudinal threshold (TTC); a state in which the relative speed between the host vehicle and the other vehicle is less than a first longitudinal threshold (speed); a state in which the distance along the road width direction between the host vehicle and the other vehicle is less than a first lateral threshold; and a state in which the host vehicle and the other vehicle are traveling in the same lane. While not particularly limited, the first approach state may be determined based on a first longitudinal threshold along the traveling direction. The second approach state, which will be described later, can also be set using a method similar to that for the first approach state.

[0017] Each first longitudinal threshold and / or first lateral threshold can be set according to the attributes of the driving lane. When the driving lane is a vehicle-only road such as an expressway, the first longitudinal threshold and / or first lateral threshold are set to higher values ​​than the first longitudinal threshold and / or first lateral threshold when the driving lane is a national highway or prefectural road. When the driving lane is a national highway or prefectural road, the first longitudinal threshold and / or first lateral threshold are set to higher values ​​than the first longitudinal threshold and / or first lateral threshold when the driving lane is an urban road. Each first longitudinal threshold and / or first lateral threshold can be set according to the speed limit of the driving lane. When the speed limit of the driving lane is high, the first longitudinal threshold and / or first lateral threshold are set to higher values ​​than the first longitudinal threshold and / or first lateral threshold when the speed limit of the driving lane is low. Each first longitudinal threshold and / or first lateral threshold can be set according to the detection environment. The first vertical threshold and / or the first horizontal threshold when the detection environment is good, such as when the ambient illuminance is high (bright), the weather is clear, or before sunset, are set to values ​​higher than the first vertical threshold and / or the first horizontal threshold when the detection environment is poor, such as when the ambient illuminance is low (dark), it is raining or snowing, or after sunset. The illuminance is obtained from the illuminance meter of the sensor 2. The weather can be determined from images captured by the camera 21. The weather can be obtained from an external weather information server via the communication device 30. The time before or after sunset can be determined based on the calendar (including the sunset time) 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 obtained from an external calendar information server via the communication device 30.

[0018] A first judgment area may be set to determine whether the first approach state is present based on the positional relationship between the host vehicle and another vehicle. The processor sets the first judgment area in front of and / or behind the host vehicle based on the current position of the host vehicle. The first judgment area is set based on a first longitudinal threshold (distance, TTC, speed) and a second lateral threshold (lateral distance). If a part or all of the host vehicle enters the first judgment area, the host vehicle and another vehicle are determined to be in the first approach state. If a predetermined vehicle position, such as the center of the other vehicle or the front end of the other vehicle, enters the first judgment area, the other vehicle may be determined to be in the first approach state with the host vehicle. If a part or all of the other vehicle belongs to the first judgment area, the distance between the host vehicle and the other vehicle along the traveling direction is less than the first longitudinal threshold, and the distance between the host vehicle and the other vehicle in the road width direction is less than the second lateral threshold. The second judgment area, described later, can also be set using a method similar to that for the first judgment area. Based on the detection information from sensor 2, processor 10 determines that the subject vehicle and another vehicle traveling through the first judgment area for a predetermined judgment time are in a first proximity state. Processor 10 determines that a vehicle that is approaching the subject vehicle for a predetermined judgment time, rather than just temporarily approaching the subject vehicle, is a vehicle that may be engaging in aggressive driving and requires attention. Based on the detection information from sensor 2, processor 10 determines that the subject vehicle and another vehicle that accelerates and decelerates at a predetermined frequency in the first judgment area are in a first proximity state. Processor 10 determines that a vehicle that accelerates and decelerates unnecessarily in a first judgment area close to the subject vehicle is a vehicle that may be engaging in aggressive driving and requires attention. On the other hand, if it is determined that the subject vehicle and another vehicle are not in the first proximity state (NO in S7), the processing ends. In this way, by setting a first judgment area based on the position of the subject vehicle and using this to determine the behavior of the other vehicle relative to the subject vehicle, it is possible to accurately determine which other vehicle is in the first proximity state and is subject to aggressive driving. In addition, although the positional relationship between the subject vehicle and other vehicles changes from moment to moment, by determining the positional relationship between the two vehicles using a predetermined first judgment area, the computational load for determining other vehicles that are in the first approach state can be reduced.

[0019] When the processor 10 determines that the host vehicle and the other vehicle are in the first approach state (YES in S7), it executes a first driving control that changes the behavior of the host vehicle to adjust the distance (relative position) between the host vehicle and the other vehicle (S8). In this embodiment, the first driving control includes one or more of acceleration control, deceleration control, lateral movement control, and lane change control. When the processor 10 determines that the host vehicle and the other vehicle are in the first approach state, it causes the host vehicle to execute one or more of the first driving controls, namely, acceleration control, deceleration control, lateral movement control, and lane change control. The first driving control and the second driving control described below comply with traffic laws and regulations. The acceleration control is a control that increases the current traveling speed by a predetermined amount (acceleration). The deceleration control is a control that decreases the current traveling speed by a predetermined amount (deceleration). The lateral movement control is a control that steers the current traveling direction to the right or left by a predetermined amount (steering amount). Lane change control is a control for moving the host vehicle from the current driving lane to an adjacent lane. The adjacent lane to which the host vehicle is to change lanes can be a lane with a relatively lower speed limit. The amount of change in the host vehicle's behavior (including acceleration, deceleration, steering, and differences between driving lanes; the same applies below) in the first driving control may be preset or calculated based on the current control command values ​​(speed and steering amount). For example, the amount of change in the host vehicle's behavior may be a predetermined percentage of the speed or steering amount of the current control command value. The amount of change when the driving lane has a high speed limit is set higher than when the speed limit is low. The amount of change when the driving lane's attribute is a highway is set higher than when the attribute is a road exclusively for vehicles other than a highway. The amount of change when the attribute is a road exclusively for vehicles other than a highway is set higher than when the attribute is a city road. The first driving control is determined to be complete when the host vehicle's behavior has changed by the predetermined amount in the first driving control. The first driving control is a control for changing the behavior of the host vehicle so that the host vehicle and another vehicle, which are in the first approach state, are no longer in the first approach state. Specifically, the behavior of the host vehicle can be changed by changing (accelerating or decelerating) the speed of the host vehicle that is currently traveling.When it is determined that the host vehicle and the other vehicle are in a first proximity state, the processor 10 accelerates or decelerates the host vehicle, thereby eliminating the first proximity state between the host vehicle and the other vehicle. The behavior of the host vehicle can also be changed by changing the lateral position of the host vehicle (steering right or left) while the host vehicle is currently traveling. When it is determined that the host vehicle and the other vehicle are in a first proximity state, the processor 10 increases the inter-vehicle distance between the host vehicle and the other vehicle, thereby eliminating the first proximity state. The behavior of the host vehicle can also be changed by changing the lane of the host vehicle currently traveling (moving to an adjacent lane). When it is determined that the host vehicle and the other vehicle are in a first proximity state, the processor 10 increases the longitudinal and lateral distances between the host vehicle and the other vehicle, thereby eliminating the first proximity state. The processor 10 determines that the first driving control is complete when the behavior of the host vehicle is changed by the first driving control until the host vehicle and the other vehicle are separated from each other and no longer in the first proximity state.

[0020] When a first judgment area is set, a first driving control may be executed to move another vehicle traveling within the first judgment area out of the first judgment area. The first judgment area is set based on the position of the host vehicle and therefore follows the movement of the host vehicle. Therefore, by observing the position of the other vehicle relative to the first judgment area over time, it is possible to determine whether the other vehicle is following the host vehicle. The processor 10 moves at least a portion of the other vehicle within the first judgment area out of the first judgment area by a first driving control that accelerates or decelerates the host vehicle. The processor 10 moves at least a portion of the other vehicle within the first judgment area out of the first judgment area by a first driving control that moves the host vehicle laterally. The processor 10 moves the other vehicle within the first judgment area out of the first judgment area by a first driving control that changes lanes of the host vehicle. The processor 10 completes the first driving control when the other vehicle moves out of the first judgment area by the first driving control. By temporarily canceling the first approach state using the first driving control, it is possible to determine whether the other vehicle is intentionally approaching the host vehicle. Specifically, when the processor 10 determines that the host vehicle and another vehicle traveling ahead of the host vehicle are in the first approach state, the processor 10 executes the first driving control to decelerate the host vehicle and move the other vehicle from the inside to the outside of a first determination area set in front of the host vehicle. When the processor 10 determines that the host vehicle and another vehicle traveling behind the host vehicle are in the first approach state, the processor 10 executes the first driving control to accelerate the host vehicle and move the other vehicle from the inside to the outside of the first determination area set behind the host vehicle. In this way, the first determination area is set based on the position of the host vehicle, and the first driving control is determined to be complete when the other vehicle traveling within the first determination area moves out of the first determination area. By executing the first driving control, the first approach state can be temporarily canceled, and the subsequent behavior of the other vehicle can be monitored. Furthermore, the host vehicle is decelerated to eliminate the first approach state with respect to the other vehicle ahead, and the host vehicle is accelerated to eliminate the first approach state with respect to the other vehicle behind. The first approach state can be eliminated by executing a first driving control appropriate for the positional relationship between the host vehicle and the other vehicle. Furthermore, although the positional relationship between the host vehicle and the other vehicle changes from moment to moment, a predetermined first judgment area is used.If another vehicle is present inside the first judgment area, it is determined that the first approach state is in effect, and if another vehicle is present outside the first judgment area, it is determined that the first approach state has been resolved, thereby reducing the calculation load.

[0021] After the execution of the first driving control is completed (S9), the processor 10 acquires detection information after the first driving control (S10). Based on the detection information acquired after the execution of the first driving control, the processor 10 determines whether the host vehicle and the other vehicle are in a second approach state (S11). The second approach state can be defined using a method similar to that for the first approach state. For example, the second approach state can be defined using one or more of the following: a state in which the distance along the driving direction between the host vehicle and the other vehicle is less than a second longitudinal threshold (distance); a state in which the time-to-collision (TTC) based on the relative speed and relative distance between the host vehicle and the other vehicle is less than a second longitudinal threshold (TTC); a state in which the relative speed between the host vehicle and the other vehicle is less than a second longitudinal threshold (speed); a state in which the distance along the road width direction between the host vehicle and the other vehicle is less than a second lateral threshold; and a state in which the host vehicle and the other vehicle are traveling in the same lane. The method for setting each of the second longitudinal threshold and / or second lateral threshold is the same as the method for setting each of the first longitudinal threshold and / or first lateral threshold. To avoid repetition, the description of the first longitudinal threshold and the first lateral threshold is incorporated herein as a description of the second longitudinal threshold and the second lateral threshold. The proximity degree defining the second approach state may be the same as or different from the proximity degree defining the first approach state. Although not particularly limited, the proximity degree (inter-vehicle distance along the direction of travel, TTC, relative speed, distance along the road width direction) between the host vehicle and the other vehicle in the second approach state can be set higher (closer) than the proximity degree between the host vehicle and the other vehicle in the first approach state. The second longitudinal threshold and / or the second lateral threshold can be set to a value lower than the first longitudinal threshold and / or the first lateral threshold.

[0022] Similar to the above-described method for determining whether the first approach state exists, the second judgment area may be set based on the positional relationship between the host vehicle and another vehicle. The processor sets the second judgment area in front of and / or behind the host vehicle based on the current position of the host vehicle. The second judgment area is set based on a second longitudinal threshold (distance, TTC, speed) and a second lateral threshold. The second judgment area can be set narrower than the first judgment area. In this case, the distance along the driving lane of the second judgment area is shorter than that of the first judgment area. The distance along the driving lane of the second judgment area of ​​a lane with a higher speed limit is shorter than the distance along the driving lane of the second judgment area of ​​a lane with a lower speed limit. Based on the detection information from sensor 2, processor 10 determines that the host vehicle and another vehicle that has entered the second judgment area are in the second approach state. The processor determines that the host vehicle and another vehicle that has entered the second judgment area with all or part of their bodies in the second judgment area are in the second approach state. When a predetermined vehicle position, such as the center of gravity of the other vehicle's body or the front wheel of the other vehicle's body, enters the second judgment area, the other vehicle may be determined to be in the second proximity state with the subject vehicle. Based on the detection information from sensor 2, processor 10 determines that the other vehicle traveling in the second judgment area for a predetermined judgment time and the subject vehicle are in the second proximity state. Processor 10 determines that a vehicle approaching the subject vehicle for a predetermined judgment time, rather than just temporarily approaching the subject vehicle, is engaging in tailgating aimed at the subject vehicle. Based on the detection information from sensor 2, processor 10 determines that the other vehicle accelerating and decelerating at a predetermined frequency in the second judgment area and the subject vehicle are in the second proximity state. Processor 10 determines that a vehicle unnecessarily accelerating and decelerating in the second judgment area close to the subject vehicle is engaging in tailgating aimed at the subject vehicle. If it is determined that the subject vehicle and the other vehicle are not in the second proximity state (NO in S11), the processing ends. In this way, by setting the second judgment area based on the position of the subject vehicle and observing the positional relationship of the other vehicle with respect to the second judgment area, it is possible to determine whether the other vehicle and the subject vehicle are in the second approaching state. In other words, the behavior of the other vehicle can be evaluated using the second judgment area, and it can be determined whether the other vehicle is tailgating the subject vehicle.In addition, although the positional relationship between the subject vehicle and the other vehicle changes from moment to moment, by determining the positional relationship between the two using a predetermined second judgment area, the computational load for determining whether the subject vehicle and the other vehicle are in the second approach state can be reduced.

[0023] If it is determined that the host vehicle and the other vehicle are in the second approaching state (YES in S11), the processor 10 determines that the other vehicle is tailgating the host vehicle (S12). If it is determined that the other vehicle is tailgating the host vehicle, the processor 10 outputs the result of the determination to the outside. The processor 10 executes two processes F1 and / or F2 depending on the output destination.

[0024] In the first process F1, the processor 10 outputs the determination result of whether or not the subject vehicle is tailgating to the vehicle actuator 200 (S14). The processor 10 then creates a driving plan for a second driving control for causing the subject vehicle to avoid the tailgating vehicle (S15). The processor 10 then causes the vehicle actuator 200 to execute the second driving control based on the driving plan. The behavior of the subject vehicle also changes during the second driving control, but the second driving control is executed after the first driving control and is executed based on commands different from those of the first driving control. The timing at which the second driving control is executed is later than the timing at which the first driving control is executed, and the position at which the second driving control is executed is downstream in the traveling direction from the position at which the first driving control is executed. Furthermore, whether or not the second approach state, which is the execution condition for the second driving control, is established is determined based on detection information after the execution of the first driving control.

[0025] In the present invention, when it is determined that the host vehicle and another vehicle are in a first approach state, a first driving control is executed to change the behavior of the host vehicle. When it is determined that the host vehicle and another vehicle are in a second approach state based on detection information acquired after the execution of the first driving control, it is determined that the other vehicle is tailgating the host vehicle, and the result of the determination is output. Even if another vehicle approaches the host vehicle, this may be due to circumstances such as traffic congestion in front of or behind the host vehicle, and it cannot be determined that the other vehicle is intending to tailgate based solely on the proximity (inter-vehicle distance). A determination of tailgating based solely on the proximity (inter-vehicle distance) between the other vehicle and the host vehicle lacks reliability. In this embodiment, when it is determined that the host vehicle and another vehicle are in a first approach state, the behavior of the host vehicle is changed by a first driving control. Then, after the execution of the first driving control is completed, it is determined whether the host vehicle and another vehicle are in a second approach state. If the subject vehicle and the other vehicle are in the second approach state, it can be determined that the other vehicle is moving in accordance with the behavior (movement) of the subject vehicle, or that the other vehicle is targeting the subject vehicle and adapting to the behavior of the subject vehicle with the intent of interfering with the subject vehicle's driving. For example, if the subject vehicle accelerates or decelerates, and then the other vehicle accelerates or decelerates in the same way, or if the subject vehicle moves laterally to the right or left and then the other vehicle moves laterally in the same direction, or if the subject vehicle changes lanes to an adjacent lane and then the other vehicle moves into the same lane, these are likely to be tailgating attempts intended to interfere with the subject vehicle's driving. On the other hand, if the subject vehicle and the other vehicle do not enter the second approach state after changing the behavior of the subject vehicle using the first driving control, it can be determined that the other vehicle is approaching the subject vehicle without the intent of interfering. In this way, since the first driving control that changes the behavior of the subject vehicle is executed before determining whether the second approach state has been reached, it can be determined with high accuracy whether the other vehicle approached the subject vehicle out of necessity due to traffic congestion or the like, or whether the other vehicle approached the subject vehicle with the intent of tailgating. Because the accuracy of the judgment can be increased, the second driving control (acceleration control, deceleration control, lane change) performed to avoid approaching other vehicles by increasing the distance between other vehicles and moving to a different lane from other vehicles can be executed only when necessary. In other words, the execution of unnecessary second driving control due to low-accuracy judgment results can be suppressed. When tailgating is performed, normal driving is hindered, traffic rule violations and even undesirable driving are encouraged.For this reason, when tailgating begins, that is, when the driver of the other vehicle intends to interfere, it is important to recognize that intention early. In this embodiment, when it is determined that there is another vehicle in the first approach state that may indicate tailgating, the first driving control is executed to spontaneously change the behavior of the vehicle and test whether the driver of the other vehicle intends to tailgate. This makes it possible to determine the intention immediately after the start of tailgating and to take appropriate action early. Furthermore, even if the second driving control is not executed, the first driving control can at least resolve the first approach state, thereby maintaining an appropriate vehicle distance from the other vehicle.

[0026] By executing a first driving control, which is acceleration control, deceleration control, lateral movement control, or lane change control, on the host vehicle in the first approach state, the host vehicle can be made to behave differently from when it was traveling in the first approach state, and the first approach state can be resolved. After the first approach state is resolved, whether or not the other vehicle intends to tailgate can be tested based on whether or not the other vehicle drives in accordance with the first driving control of the host vehicle, and a highly accurate determination result can be obtained.

[0027] In the second process F2, the processor 10 outputs the determination result indicating tailgating to the output device 20b (S17). The output device 20b notifies the driver of the host vehicle of the determination result (S18). The processor 10 notifies the driver that the host vehicle is being tailgated using the display 20b1, speaker 20b2, or lamp 20b3 of the output device 20b. The processor 10 may display text such as "A tailgating vehicle has been detected." or "The vehicle behind (the vehicle ahead) is tailgating." on the display 20b1, or may output the text audibly from the speaker 20b2, or may turn on a predetermined lamp 20b3 for alerting the driver of tailgating. If multiple lamps 20b3 are provided, the lamps 20b3 in the direction (left and right) from which the tailgating vehicle is approaching are turned on. The information to be notified may include countermeasures or guidance for reporting the emergency to an external party such as the police, for example, text such as "Do you want to report the emergency to the police?" This allows the vehicle to take preventative measures early. In addition, the output device 20b outputs the determination result of aggressive driving to a drive recorder installed in the vehicle.

[0028] The processor 10 executes a second driving control according to the determination result. This control procedure is explained based on the flowchart in FIG. 3. The processor 10 executes the process shown in FIG. 2 for the steering amount. The above explanation is used for each process. The processor 10 determines whether another vehicle is present ahead of the host vehicle in the driving lane based on the positional relationship between the host vehicle and the other vehicle obtained in S6 (S20). If another vehicle is present ahead (YES in S20), the process proceeds to S21, where the positional relationship between the host vehicle and the other vehicle ahead is confirmed (S21). The positional relationship includes one or more of the relative distance, relative speed, relative acceleration, and relative lateral position between the host vehicle and the other vehicle, as well as the TTC based on these. The processor 10 sets the first determination area described above ahead of the host vehicle (S22). The processor 10 determines whether another vehicle is entering the first determination area based on the detection information (S23). The determination condition may be that the other vehicle has been traveling in the first determination area for a predetermined determination time, or that the other vehicle has accelerated or decelerated in the first determination area at a predetermined frequency.

[0029] FIG. 4 illustrates an example of the movement of the host vehicle V1 in accordance with the control procedure (S20-S31) for the forward vehicle. V3 is another vehicle behind the host vehicle. As shown in FIG. 4A, if the forward vehicle VF2 in front of the host vehicle V1 is entering the first determination area FF1 set ahead in the traveling direction of the host vehicle V1 (YES in S23), the host vehicle and the other vehicle are determined to be in a first approach state. If the forward vehicle VF2 is not entering the first determination area FF1 (NO in S23), the process ends. The processor 10 causes the host vehicle to execute deceleration control as a first driving control to resolve the first approach state with the forward vehicle VF2 shown in FIG. 4A (S24). By controlling the deceleration of the host vehicle V1, the host vehicle V1 and the first determination area FF1 can be separated from the forward vehicle VF2. 4(b), the first approach state is temporarily resolved by decelerating the host vehicle V1 (deceleration in the DL direction) so that the forward vehicle VF2 travels outside the first determination area FF1 of the host vehicle V1. When the distance between the host vehicle V1 and the forward vehicle VF2 becomes equal to or greater than a predetermined value and the forward vehicle VF2 travels outside the first determination area FF1, the processor 10 completes the execution of the first driving control (S25).

[0030] Instead of deceleration control executed as the first driving control in S24, lateral movement control or lane change control may be executed as the first driving control. When lateral movement control is executed as the first driving control, the lateral position of the forward vehicle VF2 relative to the first judgment area FF1 is shifted according to the amount of lateral movement of the host vehicle V1. When the amount of shift in the lateral position (vehicle width direction / road width direction) of the forward vehicle VF2 relative to the first judgment area FF1 becomes equal to or greater than a predetermined shift amount according to the amount of lateral movement of the host vehicle, execution of the first driving control is completed. When the first driving control is lateral movement, the lateral position of the forward vehicle VF2 relative to the first judgment area FF1 is used as a reference, taking into account the vehicle width limit. When lane change control is executed as the first driving control, the position of the forward vehicle VF2 relative to the first judgment area FF1 is shifted due to a lane change by the host vehicle V1. When the shift amount of the longitudinal and lateral position (vehicle width direction and vehicle length direction / road width direction and direction of travel) of the other vehicle VF2 in front relative to the first judgment area FF1 becomes equal to or greater than a predetermined shift amount corresponding to the lane change of the host vehicle, the execution of the first driving control is completed.

[0031] The processor 10 acquires detection information after the execution of the first driving control is completed (S26). The acquired detection information is detection information after the first close proximity state between the host vehicle V1 and the forward vehicle VF2 is alleviated or resolved, or after the forward vehicle VF2 moves out of the first determination area FF1. When executing lane change control, the processor 10 confirms whether predefined lane change conditions are met. The lane change conditions are defined from the perspective of whether space for the host vehicle to travel can be secured in the adjacent lane to which the host vehicle V1 will change lanes. The lane change conditions are defined based on the inter-vehicle distance and TTC between the host vehicle V1 and a vehicle traveling ahead of the host vehicle V1 in the adjacent lane in which the host vehicle V1 will travel after the lane change, and the inter-vehicle distance and TTC between the host vehicle V1 and a vehicle traveling behind the host vehicle V1 in the adjacent lane. The processor 10 executes lane change control only when it confirms that the predefined lane change conditions are met.

[0032] The processor 10 monitors the behavior of the forward vehicle VF2 based on the detection information after the first driving control is completed, and determines whether the forward vehicle VF2 has re-entered the first judgment area FF1 (S27). If the forward vehicle VF2 has not re-entered the first judgment area FF1 after the first driving control (S24) (NO in S27), the process ends. On the other hand, as shown in FIG. 4(c), if the forward vehicle VF2 has re-entered the first judgment area FF1 (YES in S27), the processor 10 determines that the forward vehicle VF2 is engaging in tailgating (S28) intentionally. If the forward vehicle VF2 decelerates and approaches the forward vehicle V1 again despite the host vehicle V1 having decelerated and increased the distance between the host vehicle VF2 and the forward vehicle VF2, this is likely to be tailgating, interfering with the driving of the host vehicle V1. The processor 10 outputs a determination result to the vehicle actuator 200 that the forward vehicle VF2 is tailgating the host vehicle V1 (S29). Based on this determination result, the processor 10 causes the vehicle actuator 200 to execute deceleration control of the host vehicle V1 (S30). The processor 10 causes the vehicle actuator 200 to execute deceleration control of the host vehicle V1 and then execute lane change control (S31). The processor 10 causes the host vehicle V1 to execute the deceleration control and lane change control as a series of second driving controls. Specifically, as shown in FIG. 4(d), the host vehicle V1 is decelerated again (deceleration in the DL direction) by the second driving control. As a result, the forward vehicle VF2 moves out of the first determination area FF1, and a vehicle-to-vehicle distance is formed between the host vehicle V1 and the forward vehicle VF2. Thereafter, as shown in FIG. 4(e), the host vehicle V1 is caused to change lanes to an adjacent lane by the second driving control. The adjacent lane is preferably a driving lane where the driving speed is relatively low, rather than an overtaking lane where the driving speed is relatively high. The host vehicle V1', which has moved to a lane different from the other vehicle VF2 ahead, can avoid the effects of tailgating (obstructive driving). In this way, if the other vehicle VF2 ahead of the host vehicle V1 unnecessarily decelerates and intentionally approaches the other vehicle VF2 ahead of the host vehicle V1, the processor 10 causes the host vehicle V1 to perform deceleration control and then executes lane change control.By having the vehicle V1 execute deceleration control and lane change control as second driving control against the other vehicle VF2 ahead that is tailgating, the vehicle V1 can avoid approaching the other vehicle VF2 ahead and escape tailgating against the vehicle V1.

[0033] When the processor 10 determines that the preceding vehicle VF2 is tailgating, the processor 10 may cause the host vehicle V1 to execute only deceleration control as the second driving control. Lane change control may not be executable depending on the conditions of the adjacent lanes. In such cases, the processor 10 executes only deceleration control (S30) and terminates the process (shown by the dashed line). By simply executing deceleration control, the inter-vehicle distance between the preceding vehicle VF2 and the host vehicle V1 can be increased, as shown in FIG. 4(d), thereby reducing the risk of tailgating by the preceding vehicle VF2. Furthermore, by executing deceleration control, the host vehicle V1 can be spaced away from the preceding vehicle V1 and wait for the next opportunity to change lanes. When the processor 10 determines that the preceding vehicle VF2 is tailgating, the processor 10 may cause the host vehicle V1 to execute only lane change control as the second driving control. Depending on the inter-vehicle distance and relative speed between the host vehicle and the preceding vehicle, a lane change may be possible without deceleration control. By simply performing lane change control, the host vehicle V1 can be made to travel in a different lane from the vehicle VF2 ahead, as shown in Figure 4(e), thereby reducing the risk of tailgating by the vehicle VF2 ahead.

[0034] Next, the control procedure (S20, S41-S50) when another vehicle is located behind the host vehicle will be described. If another vehicle is located behind the host vehicle (NO in S20), the processor 10 proceeds to S41 and checks the positional relationship between the other vehicle behind the host vehicle and the host vehicle (S41). The positional relationship includes one or more of the relative distance, relative speed, relative acceleration, and relative lateral position between the host vehicle and the other vehicle, as well as the TTC based on these. The processor 10 sets the first judgment area described above behind the host vehicle (S42). Based on the detection information, the processor 10 determines whether the other vehicle has entered the first judgment area (S43). The condition for this determination may be that the other vehicle has been traveling through the first judgment area for a predetermined determination time or that the other vehicle has accelerated or decelerated within the first judgment area at a predetermined frequency.

[0035] FIG. 5 illustrates an example of the movement of the host vehicle V1 in accordance with the control procedure (S41-S50) for the rear vehicle. V4 is another vehicle ahead of the host vehicle. As shown in FIG. 5(a), if the rear vehicle VR2 behind the host vehicle V1 enters the first determination area RF1 set behind the host vehicle V1 (YES in S43), the host vehicle and the other vehicle are determined to be in a first approach state. The processor 10 causes the host vehicle to execute acceleration control as the first driving control (S44). The acceleration of the host vehicle V1 causes the host vehicle V1 and the first determination area RF1 to move away from the rear vehicle VR2. As shown in FIG. 5(b), the acceleration of the host vehicle V1 (acceleration in the AL direction) causes the rear vehicle VR2 to move out of the first determination area RF1 of the host vehicle V1. When the distance between the host vehicle V1 and the rear vehicle VR2 becomes equal to or greater than a predetermined value, such as when the rear vehicle VR2 travels outside the first judgment area RF1, the execution of the first driving control is completed (S45). Here, lateral movement control or lane change control may be executed as the first driving control. The processor 10 acquires detection information after the execution of the first driving control is completed (S46). The acquired detection information includes detection information after the host vehicle V1 and the rear vehicle VR2 have separated from each other, and detection information after the rear vehicle VRF2 has moved from the inside to the outside of the first judgment area RF1. If the rear vehicle VR2 does not enter the first judgment area RF1 (NO in S43), the processing is terminated.

[0036] The processor 10 monitors the behavior of the rear vehicle VR2 based on the detection information after the first driving control is completed and determines whether the rear vehicle VR2 has re-entered the first determination area RF1 (S47). As shown in FIG. 5C, if the rear vehicle VR2 has re-entered the first determination area RF1 (YES in S47), the processor 10 determines that the rear vehicle VR2 is intentionally tailgating the host vehicle (S48). If the host vehicle V1 accelerates and increases the distance between itself and the rear vehicle VR2, but the rear vehicle VR2 accelerates and re-approaches the host vehicle V1, this is likely tailgating, interfering with the driving of the host vehicle V1. The processor 10 outputs a determination result that the rear vehicle VR2 is tailgating the host vehicle V1 to the vehicle actuator 200 (S49). The processor 10 causes the host vehicle V1 to execute lane change control (S50) as the second driving control using the vehicle actuator 200. As shown in FIG. 5(d), the host vehicle V1 is caused to change lanes to an adjacent lane by the second driving control. The host vehicle V1', which has moved to a lane different from the rear vehicle VR2, can avoid the effects of tailgating (obstructive driving). If the rear vehicle VR2 does not re-enter the first determination area RF1 after the first driving control (S44) (NO in S47), the process ends. In this manner, if the rear vehicle VR2 traveling behind the host vehicle V1 unnecessarily accelerates and intentionally approaches the host vehicle V1, the host vehicle V1 executes lane change control. By executing lane change control as the second driving control for the tailgating rear vehicle VR2, the host vehicle V1 can avoid approaching the rear vehicle VR2 and escape tailgating of the host vehicle V1. Unlike when avoiding the front vehicle VF2, when avoiding the rear vehicle VR2, lane change control is executed without deceleration control. By the lane change control, the host vehicle V1 can be separated from the rear vehicle VR2.

[0037] 100... driving assistance 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

Claims

1. A driving assistance method used in a processor to control autonomous driving of a host vehicle, wherein the processor: acquires detection information about the surroundings of the host vehicle; and, if it is determined based on the detection information that the host vehicle and another vehicle are in a first approach state, executes a first driving control that changes the behavior of the host vehicle; and, if it is determined based on the detection information acquired after executing the first driving control that the host vehicle and the other vehicle are in a second approach state, determines that the other vehicle is tailgating; and outputs the result of the determination.

2. The driving assistance method according to claim 1, wherein the processor causes the host vehicle to execute acceleration control or deceleration control as the first driving control.

3. The driving assistance method according to claim 1, wherein the processor causes the host vehicle to execute lateral movement control as the first driving control.

4. The driving assistance method according to claim 1, wherein the processor causes the host vehicle to execute lane change control as the first driving control.

5. A driving assistance method according to any one of claims 1 to 4, wherein the processor sets a first judgment area in front of and / or behind the host vehicle based on the current position of the host vehicle, and based on the detection information, detects the other vehicle that has entered the first judgment area, the other vehicle that is traveling in the first judgment area for a predetermined judgment time, or the other vehicle that accelerates or decelerates at a predetermined frequency in the first judgment area, and determines that the detected other vehicle and the host vehicle are in the first approach state.

6. A driving assistance method as described in claim 5, wherein the processor executes the first driving control to decelerate the host vehicle and move the host vehicle outside the set first judgment area when it is determined that the other vehicle traveling in front of the host vehicle and the host vehicle are in the first approach state.

7. A driving assistance method as described in claim 5, wherein the processor, when it is determined that the other vehicle traveling behind the host vehicle and the host vehicle are in the first approach state, executes the first driving control to accelerate the host vehicle and move the host vehicle outside the set first judgment area.

8. A driving assistance method as claimed in any one of claims 1 to 7, wherein the processor causes the host vehicle to execute lane change control as a second driving control when it determines that the other vehicle is tailgating.

9. A driving assistance method as described in claim 8, wherein the processor causes the host vehicle to execute deceleration control and the lane change control that is performed after the deceleration control as the second driving control when the other vehicle is traveling ahead of the host vehicle.

10. A driving assistance method according to claim 8, wherein the processor causes the host vehicle to execute the lane change control as the second driving control when the other vehicle is traveling behind the host vehicle.

11. A driving assistance method according to any one of claims 1 to 7, wherein the processor causes the host vehicle to execute deceleration control as a second driving control when the other vehicle is traveling ahead of the host vehicle.

12. A driving assistance method as claimed in any one of claims 1 to 11, wherein the processor sets a second judgment area in front of and / or behind the host vehicle based on the current position of the host vehicle, and based on the detection information, detects the other vehicle that has entered the second judgment area, the other vehicle that is traveling in the second judgment area for a predetermined judgment time, or the other vehicle that accelerates or decelerates at a predetermined frequency in the second judgment area, and determines that the detected other vehicle and the host vehicle are in the second approach state.

13. A driving assistance method according to any one of claims 1 to 12, wherein, when it is determined that the other vehicle is tailgating, the processor notifies the driver of the subject vehicle of the result of the determination.

14. A driving assistance device comprising a processor and controlling autonomous driving of a host vehicle, wherein the processor: acquires detection information about the surroundings of the host vehicle; and, if it is determined based on the detection information that the host vehicle and another vehicle are in a first approach state, executes a first driving control that changes the behavior of the host vehicle; and, if it is determined based on the detection information acquired after executing the first driving control that the host vehicle and the other vehicle are in a second approach state, determines that the other vehicle is tailgating; and outputs the result of the determination.

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