Driving assistance method and driving assistance device

Abstract

To provide a driving assistance method and a driving assistance device to estimate existence of oncoming vehicles regardless of a positional relation of an own vehicle and other vehicles or a detection performance of sensors.SOLUTION: A processor 10 acquires a first vehicle number of vehicles traveling on an oncoming lane L2 adjacent to a traveling lane L1 from a vehicle detection system 200 via a communication function when an own vehicle V1 enters the traveling lane L1 in a target section OL where there is no branch between two roadside sensors 210, calculates a second vehicle number of oncoming vehicles OV traveling on the oncoming lane L2 that the own vehicle V1 has passed by using a vehicle-mounted sensor 2 of the own vehicle V1 during traveling on the traveling lane L1 of the target section OL, determines that there are no oncoming vehicles OV traveling in the target section OL ahead of the own vehicle V1 when a difference between the first vehicle number and the second vehicle number is zero, and outputs the determination result to the outside.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] When a closed area is formed by the detection results and detectable area information transmitted from other vehicles via vehicle-to-vehicle communication, the detectable area of ​​the vehicle itself, and the non-travelable area, a device is known that estimates the presence of an obstacle within the closed area by managing the closed area and the detection results of the obstacle detection means installed in the vehicle itself and other vehicles in a chronological order (Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4412337 Summary of the Invention [Problem to be solved by the invention]

[0004] However, depending on the relative positions of the host vehicle and other vehicles and the detection performance of the sensors, a closed area may not be formed between the host vehicle and other vehicles, making it impossible to determine whether an obstacle exists.

[0005] The problem to be solved by the present invention is to determine whether or not an oncoming vehicle is present, regardless of the relative positions of the vehicle and other vehicles or the detection performance of the sensors. [Means for solving the problem]

[0006] The present invention solves the above problem by obtaining a first number of oncoming vehicles traveling in an oncoming lane adjacent to the traveling lane from a vehicle detection system when the vehicle enters a traveling lane in a target section where there is no branch between two roadside sensors, calculating a second number of oncoming vehicles that the vehicle has passed while traveling in the target section using a sensor mounted on the vehicle, and determining that there are no oncoming vehicles ahead of the vehicle if the difference between the first number of vehicles and the second number of vehicles is zero. [Effects of the Invention]

[0007] According to the present invention, it is possible to determine whether or not an oncoming vehicle is present, regardless of the relative positions of the vehicle and other vehicles or the detection performance of the sensors. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a block diagram illustrating an example of a hardware configuration of a driving assistance device. [Figure 2] 1 is a first flowchart showing an example of a driving assistance processing procedure. [Figure 3] 3(a), (b), and (c) are first diagrams for explaining the driving assistance function. [Figure 4] 10 is a second flowchart showing an example of a driving assistance processing procedure. [Figure 5] 5(a), (b), and (c) are second diagrams for explaining the driving assistance function. DETAILED DESCRIPTION OF THE INVENTION

[0009] 1 shows the hardware configuration of a driving assistance system 100. A driving assistance device 1 of the driving assistance system 100 exchanges information with a vehicle detection system 200 via a communication device 40.

[0010] First, the vehicle detection system 200, which is road-side infrastructure, will be described. The vehicle detection system 200 includes a plurality of roadside sensors 210 installed on the road, a computing device 220, and map information 230, which exchange information via a communication system 240. The communication system 240 communicates with internal devices of the vehicle detection system 200 and external devices. Each roadside sensor 210 has a sensor function, a storage function (memory), and a communication function. The roadside sensor 210 has a detection function using a camera and / or a radar device. The camera includes an image sensor with an image pickup element such as a CCD, an ultrasonic camera, and an infrared camera. The radar device includes a laser radar, a millimeter-wave radar, a LiDAR (light detection and ranging) unit, and an ultrasonic radar. The roadside sensor 210 detects vehicles, such as cars, motorcycles, and bicycles, that enter a detection area. Each roadside sensor 210 provides its detection results, with its own identifier attached, to the calculation device 220 via the communication system 240. The detection functions and detection processes of the multiple roadside sensors 210 are synchronized, and the detection results at each time on a common time axis are provided to the calculation device 220. The map information 230 includes the positions of the multiple roadside sensors 210, and the positions and characteristics of the section of the road sandwiched between two roadside sensors 210. The section characteristics include whether or not there is a branch in the section. Roads that constitute a branch include branching roads, merging roads, and intersecting roads. The map information 230 defines a section where there is no branch between two roadside sensors 210 as a "target section." The target section can be identified by the installation positions of the two roadside sensors 210. Because roadside sensors 210 are often installed at points where roads intersect, the position of the target section may be identified by the position of the node on the map information that is closest to the position of the roadside sensor 210. The "target section" does not have any branch points, junctions, or intersections. The "target section" is set to a road where an inbound lane and an outbound lane, which are traveling in opposite directions, meet. The "target section" can be set to a road with one lane in each direction. The map information 230 stores information specifying the location of the target section in association with an identifier that identifies the target section so that it can be read out. The calculation device 220 refers to the map information 230 and identifies two roadside sensors 210 that make up the target section. Although not particularly limited, one of the two roadside sensors 210 is a first roadside sensor installed at one end of the target section, and the other is a second roadside sensor installed at the other end of the target section. The target section includes an uphill lane and an downhill lane. When the host vehicle is used as a reference, the target section has an oncoming lane that is traveling in the opposite direction to the lane in which the host vehicle is traveling. The arithmetic device 220 calculates the number of entering vehicles entering one lane (e.g., an oncoming lane) of the target section based on first detection information acquired from a first roadside sensor installed at one end of the target section, and calculates the number of exiting vehicles exiting one lane (e.g., an oncoming lane) of the target section based on second detection information acquired from a second roadside sensor installed at the other end of the target section. Of course, the numbers of entering and exiting vehicles can also be calculated similarly for other lanes, i.e., driving lanes. The arithmetic device 220 identifies one lane of the target section and manages the numbers of entering and exiting vehicles. Although not particularly limited, in this embodiment, adjacent uphill and downhill lanes are subject to management of the number of entering / exiting vehicles. The calculation device 220 acquires the detection information and the detection time of the roadside sensor 210, and calculates the first number of vehicles traveling in each lane of the target section by subtracting the number of vehicles exiting one lane from the number of vehicles entering one lane of the target section at a common detection time. The calculation device 220 sequentially and continuously monitors vehicles entering and exiting the target section, and calculates the first number of vehicles traveling in each lane of the target section at every moment. The arithmetic device 220 transmits the first vehicle count to the outside via the communication system 240. The arithmetic device 220 may be installed in a distributed manner adjacent to each roadside sensor 210, or may be installed in a centralized manner to centrally manage multiple roadside sensors 210, provided that information exchange and control via the communication system 240 are possible. Furthermore, if one vehicle detection system 200 cannot manage the entire target area, multiple vehicle detection systems 200 can be installed for each divided area of ​​the target area. The multiple vehicle detection systems 200 that manage the divided areas cooperate by exchanging information with each other. The communication system 240 outputs the first vehicle number to the outside via dedicated short-range communication (DSRC) every time the first vehicle number is calculated. This allows the first vehicle number to be provided only to vehicles present within the short-range communication area. The vehicle side is equipped with a communication application for acquiring the first lane number as needed. Furthermore, in response to receiving a request from the vehicle side via wireless communication, the communication system 240 may transmit the first vehicle number at the time the request was issued to the communication address of the vehicle that issued the request.

[0011] Next, a driving assistance system 100 will be described. The driving assistance system 100 of this embodiment includes a driving assistance device 1, an on-board sensor 2, a host vehicle information acquisition device 3, an information acquisition device 4, a navigation device 5, and a vehicle controller 6. The processor 10 of the driving assistance device 1 and these devices are connected via a communication device 40 such as a CAN (Controller Area Network) or other on-board LAN, and exchange information with each other to cooperate. These devices may be mounted on the vehicle, or may be brought into the vehicle as portable devices and connected to the on-board devices.

[0012] The on-board sensors 2 include a camera 21 and / or a radar device 22. The on-board sensors 2 transmit detected information acquired according to their respective functions to the processor 10. The single or multiple cameras 21 capture omnidirectional images, including the area in front of the vehicle. The cameras 21 include an image sensor with an imaging element such as a CCD, an ultrasonic camera, and an infrared camera. 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 to the rear sides of the vehicle, and side cameras that capture images on the left and right sides and the front and rear of the vehicle. The cameras 21 capture images of "objects" in front of, behind, left and right sides of the vehicle. Objects include obstacles. Obstacles include other vehicles around the vehicle, such as another vehicle ahead of the vehicle, parked vehicles in the vehicle's lane, and oncoming vehicles passing the vehicle in the oncoming lane. Objects are not limited to vehicles, but also include objects such as motorcycles, pedestrians, animals, signs, billboards, and fallen objects. Objects include construction sites and restricted access areas. The captured image or detection result of the object is provided to the processor 10 . The radar device 22 detects the presence of an object around the vehicle, the position and change of the position of the object, the size (width and height) of the object, and the area occupied by the object. The on-board sensor 2 includes a laser radar, a millimeter wave radar, a LiDAR (light detection and ranging) unit, and an ultrasonic radar as the radar device 22. Measurement information measured by the radar device 22 is provided to the processor 10. If an object or area detected by the camera 21 and / or radar device 22 approaches or interferes with the route on which the vehicle is traveling, it is determined to be an obstacle.

[0013] The host vehicle information acquisition device 3 acquires position information and driving information of the host vehicle. The host vehicle information acquisition device 3 is equipped with a position detection device 31. The position detection device 31 is equipped with a GPS (Global Positioning System) unit and a gyro sensor and detects the current position of the host vehicle. The driving information includes steering information (including steering amount, steering speed, and steering acceleration), driving information (including braking amount and acceleration amount), speed information (including acceleration and jerk), traveling direction information, attitude information, and behavior information. The host vehicle information acquisition device 3 is capable of exchanging information with any one or more of the host vehicle's steering sensor, vehicle speed sensor, acceleration sensor, braking sensor, traveling direction sensor, attitude sensor, and behavior sensor, and acquires necessary information over time and provides it to the processor 10. This information may be acquired from the navigation device 5 or the vehicle controller 6.

[0014] The information acquisition device 4 acquires information output by the vehicle detection system 200. The information acquisition device 4 may send an information output request to the vehicle detection system 200 and acquire the requested information. The information acquisition device 4 acquires the detection results of the on-board sensor 2. The on-board sensor 2 detects the presence and position of an oncoming vehicle (other vehicle) traveling in an oncoming lane adjacent to the traveling lane in which the host vehicle is traveling. The detection results of the onboard sensor 2 include whether or not an oncoming vehicle has passed the host vehicle and the number of oncoming vehicles. The information acquisition device 4 acquires the position of the host vehicle from the position detection device 31, acquires the position of the oncoming vehicle from the onboard sensor 2, and compares the position of the host vehicle with the position of the oncoming vehicle. The information acquisition device 4 determines that the oncoming vehicle will pass the host vehicle when part of the region of the host vehicle in the vehicle length direction overlaps part of the region of the oncoming vehicle in the vehicle length direction, i.e., when the positions along the direction of travel are the same. The information acquisition device 4 may determine that the oncoming vehicle and the host vehicle have started to pass each other when the leading edge of the oncoming vehicle coincides with the leading edge of the host vehicle, and that the oncoming vehicle and the host vehicle have completed passing each other, i.e., have passed each other, when the trailing edge of the oncoming vehicle coincides with the trailing edge of the host vehicle. The information acquisition device 4 counts the number of oncoming vehicles that the host vehicle has passed in the target section. The counted number of oncoming vehicles is provided to the processor 10 at a predetermined interval. The detection results of the on-board sensor 2 include whether or not there is an obstacle, such as a parked vehicle, in front of the vehicle. The detection results of the obstacle in front are provided to the processor 10. The processing of the information acquisition device 4 may be executed by the processor 10 or may be executed under the control of the processor 10.

[0015] The navigation device 5 includes map information 51. The navigation device 5 refers to the map information 51 and calculates a route to a destination. This route includes a target trajectory in which the lanes to travel on are identified. The route and target trajectory calculated by the navigation device 5 are provided to the vehicle controller 6 and used for autonomous driving control. The map information 51 includes lane information 511 including identification information for each lane. The lane information 511 includes information on each road belonging to the route, such as the total number of lanes on each road, the number of inbound lanes, the number of outbound lanes, and the positional relationship between the inbound and outbound lanes (including their adjacent positional relationship). The lane information 511 includes information that each road is a one-lane road with a single inbound and outbound lane. The lane information 511 includes identification information that identifies each lane's adjacent lanes. The lane information 511 also includes identification information that indicates whether each lane is adjacent to an oncoming lane (a lane traveling in the opposite direction). The navigation device 5 refers to the lane information 511, and based on the detected current position and traveling direction of the host vehicle, identifies the lane in which the host vehicle is traveling, and obtains identification information that identifies the oncoming lane adjacent to the identified lane in which the host vehicle is traveling. The map information 51 includes information common to the map information 230 of the vehicle detection system 200. The map information 51 is information for identifying the "target section" included in the map information 230 of the vehicle detection system 200, and includes location information of the target section and information for identifying the target section. Here, redundant description will be avoided and the explanation regarding the map information 230 will be used. The navigation device 5 refers to the map information 51 and determines the relationship between the traveling position of the vehicle and the position of the target section based on the detected current position and traveling direction of the vehicle. The navigation device 5 refers to the map information 51 and identifies the position of a "target section" where there is no branch between two roadside sensors 210. The navigation device 5 identifies the position of a roadside sensor 210 provided upstream of the target section (relatively close to the vehicle), compares the position of the roadside sensor 210 with the current position of the vehicle, and determines that the vehicle has approached the entrance of the target section within a predetermined distance and entered the target section. The navigation device 5 also identifies the position of a roadside sensor 210 provided downstream of the target section (relatively far from the vehicle), and compares the position of this roadside sensor 210 with the current position of the vehicle to determine whether the vehicle has exited the target section. The navigation device 5 determines that the vehicle is traveling in the target section from the time the vehicle enters the target section until it exits it. The navigation device 5 provides the acquired information and the judgment result to the processor 10. The processor 10 acquires the current position of the vehicle, identifies the vehicle's traveling position and traveling lane by referring to map information 51 including lane information and position information of the target section, and determines whether the identified traveling lane is adjacent to an oncoming lane and whether the vehicle has approached the target section within a predetermined distance. This makes it possible to acquire the timing when the vehicle will enter the target section.

[0016] The driving assistance system 100 includes a vehicle controller 6. The vehicle controller 6 executes driving control of the vehicle. The vehicle controller 6 executes driving control both when autonomous driving control is being executed and when manual driving is being executed. The vehicle controller 6 includes a steering control device 61 and a drive control device 62. The vehicle controller 6 acquires command values ​​for autonomous driving control according to a driving plan formulated by the processor 10 of the driving assistance device 1, and drives the host vehicle along a predetermined route to the destination. The predetermined route is composed of a plurality of consecutive target trajectories to which command values ​​are associated. The command values ​​for autonomous driving control are generated by the processor 10 or the vehicle controller 6. The command values ​​are control command values ​​corresponding to the steering amount, driving amount, and braking amount required for the host vehicle to travel along each target trajectory. When an obstacle is detected near the target trajectory of the host vehicle, the target trajectory is corrected so that the target trajectory does not interfere with the obstacle's existence area or is located a predetermined distance away from the obstacle's existence area. The vehicle controller 6 causes the host vehicle to travel along the corrected target trajectory, thereby causing the host vehicle to perform avoidance driving to avoid approaching an obstacle. Based on the command values, the vehicle controller 6 inputs longitudinal and lateral forces that control the traveling position of the vehicle to the steering control device 61 and the drive control device 62. In accordance with these inputs, the behavior of the vehicle body and the behavior of the wheels are controlled so that the vehicle autonomously travels along a predetermined route consisting of multiple target trajectories (including modified target trajectories for avoidance) leading to the destination. Based on these controls, at least one of the drive actuator and the brake actuator of the vehicle body drive mechanism controlled by the drive control device 62 and the steering actuator of the steering control device 61, which is activated as needed, operate autonomously, thereby executing autonomous driving control that causes the vehicle to autonomously travel along the target trajectory. The vehicle controller 6 can perform driving in accordance with command values ​​based on manual operation by the driver input via the input device 30.

[0017] The driving assistance device 1 includes a processor 10, an output device 20, an input device 30, and a communication device 40. The processor 10 of the driving assistance device 1 executes a driving assistance method for assisting the driving of the vehicle. The processor 10 includes a ROM (Read Only Memory) 12 that stores programs for realizing a function of determining whether or not there is an oncoming vehicle traveling in a target section ahead of the vehicle and a function of executing driving control in accordance with the determination result, a CPU (Central Processing Unit) 11 that executes the program stored in the ROM 12, and a RAM (Random Access Memory) 13 that functions as an accessible storage device. The processor 10 exchanges information with a vehicle detection system 200 and executes the above functions through software that calculates the number of oncoming vehicles traveling ahead in the target section and in cooperation with the hardware components shown in FIG. 1 . The driving assistance method of this embodiment is used by the processor 10.

[0018] The output device 20 includes a speaker 201 and a display 202. Under the control of the processor 10, the output device 20 outputs audio information or display information including the determination result of the processor 10. The speaker 201 outputs a warning sound such as a siren or beep corresponding to the determination result of the processor 10, or a voice reading of text. The display 202 presents text or image information corresponding to the determination result of the processor 10. The output device 20 may also include a lamp that lights up to notify information corresponding to the determination result of the processor 10. The input device 30 receives input information from the occupant and sends it to the processor 10. The input device 30 may be configured as a switch, a button, or the like. The input device 30 may be configured as a touch panel display 202. The communication device 40 has a wireless communication function including short-range communication, and connects to a communication network such as the vehicle's CAN or other in-vehicle LAN to exchange information. The communication device 40 connects to a communication network of the communication system 240 of the vehicle detection system 200, which is a roadside infrastructure device, to exchange information.

[0019] The control procedure of the driving assistance system 100 of this embodiment will be described with reference to the flowchart of Fig. 2 and Fig. 3. In Fig. 2, the main routine flow is indicated by a solid line, and the subroutine flow is indicated by a dashed line. A flow in which multiple processes are possible is also indicated by a dashed line. The subroutine flow can be skipped. First, the control process of the vehicle detection system 200 will be described. The control process of the vehicle detection system 200 is performed by the calculation device 220. The calculation device 220 sets a detection area for each roadside sensor 210 (S1). As shown in FIGS. 3(a), (b), and (c), each roadside sensor 210 (211, 212) has a predetermined detection area A211, A212. The detection areas A211, A212 are set according to the installation position of each roadside sensor 210. The positions of the detection areas A211, A212 may be stored in advance in a memory (not shown) of the calculation device 220. The calculation device 220 refers to accessible map information 230 and sets a "target section OL" that is to be used to calculate the first number of lanes (S2). The target section OL is defined between two roadside sensors 210 (211, 212) and is a section that does not have any branching roads, merging roads, intersections, or other forks. The location of the target section OL is specified by the installation locations of the two roadside sensors 210 and the route start points (nodes) corresponding to the installation locations. The map information 230 includes information on the installation locations of each roadside sensor 210, the identifiers of each roadside sensor 210, and whether or not there are any branching roads between the two roadside sensors 210. Furthermore, the map information 230 includes information on the location of the target section OL (start point, end point, and each point between the start point and end point), the lane ID (identification information) of the target section OL, and the traveling direction (uphill / downhill) of each lane belonging to the target section OL. The calculation device 220 refers to the map information 230 to identify a first roadside sensor 211 installed at a first predetermined position at one end of each target section OL (S3), and identify a second roadside sensor 212 installed at a second predetermined position at the other end of the target section OL (S4).

[0020] The calculation device 220 calculates the first number of vehicles present in each lane of the target section OL based on the number of entering vehicles that have entered each lane of the target section OL and the number of exiting vehicles that have exited the target section OL. In this calculation process, the calculation device 220 estimates the initial number (initial value) (S5). The calculation device 220 can set the first number of vehicles calculated at a predetermined timing as the initial number. Preferably, the calculation device 220 determines that the first number of vehicles is zero and estimates that the initial number is zero at that timing. Specifically, if no entering vehicle entering a lane (a driving lane or an oncoming lane) of the target section OL is detected within a reference time, the calculation device 220 sets the first number of vehicles to zero (S101). According to this method, a situation in which there are no entering vehicles in the target section OL at the reference time can be inferred as no vehicles being present in the target section OL, and the initial number of the first number of vehicles can be reset to zero at that timing. If no entering vehicles are detected for a reference time, it is assumed that the vehicles traveling in the target section have also exited. By setting the initial number of vehicles to zero, it is possible to calculate the accurate number of vehicles that subsequently enter and travel in each lane of the target section OL. Note that the processing of S101, represented by the dashed line, can be skipped. A method for setting the reference time will be described. The longer the distance of the target section OL, the longer the time it takes for the last vehicle to enter and exit the target section OL. Therefore, the longer the distance of the target section OL, the longer the reference time is set. Furthermore, the higher the speed limit of the target section OL, the shorter the time it takes for the last vehicle to enter and exit the target section OL. Therefore, the higher the speed limit of the target section OL, the shorter the reference time is set. This makes it possible to accurately determine a state in which no vehicles are present in the target section OL and appropriately set the reference time for resetting the number of vehicles to zero according to the distance or speed limit of the target section. The time required for a vehicle to enter and exit the target section OL may be calculated based on both the distance of the target section OL and the speed limit of the target section OL, and the reference time may be set based on the calculated required passage time. Although not particularly limited, the reference time may also be set to a time obtained by adding a large margin to the required passage time or a time several times (e.g., 10 times) the calculated time.

[0021] After setting the initial number of vehicles in the target section OL, the calculation device 220 detects entering vehicles entering the target section OL (S6). The detection process is repeated until an entering vehicle is detected (NO in S6). If an entering vehicle is detected (YES in S6), the calculation device 220 acquires detection information of the entering vehicle from the first roadside sensor 211 (S7) and increments (counts up) the first number of vehicles traveling in the target section OL (S8). In this process, if the detection of the entering vehicle is delayed, the first number of vehicles in the target section OL cannot be accurately calculated. The calculation device 220 predicts, as an entering vehicle, another vehicle that is likely to enter the target section OL (S102). The calculation device 220 predicts that a vehicle entering the target section OL detected by the roadside sensor 210 and facing the target section OL is an entering vehicle, and counts it as an entering vehicle. The calculation device 220 increases the first vehicle number based on the number of vehicles predicted to enter (S8). The process of S102 indicated by the dashed line can be skipped. The arithmetic device 220 also acquires the position of the blinker of a vehicle entering the target section OL, which is detected by the roadside sensor 210. The arithmetic device 220 predicts that a vehicle that is lighting the blinker indicating an intention to proceed (turn right or left) in the direction of the target section OL is an entering vehicle, and counts the vehicle as a vehicle entering the target section OL. For example, as shown in FIG. 3(a), assume that a vehicle OV0 is present just before (upstream of) the entrance to the oncoming lane L2 of the target section OL. Although the vehicle OV0 has not yet entered the target section OL, it can be determined that the vehicle OV0 is heading toward the target section OL. It can also be determined that the left turn signal of the vehicle OV0 is flashing toward the target section OL. In such a case, the calculation device 220 predicts the vehicle OV0 as an entering vehicle before it enters the target section OL, and increases the number of first vehicles traveling in the target section OL (S8). The vehicle direction can be determined based on the captured image acquired by the camera of the roadside sensor 210 or the change in the vehicle's external shape observed by the radar device. The turn signal lighting position (left or right) can be determined based on the information (brightness) of the captured image acquired by the camera of the roadside sensor 210. In this way, by counting a vehicle as an entering vehicle and adding it to the first vehicle count at the timing when it is predicted that the vehicle will proceed into the target section OL before the vehicle actually enters the target section OL, it is possible to eliminate the influence of delays due to the time required to process detection information on the calculation results of the number of entering vehicles and to determine the number of entering vehicles that is in line with the real-time situation.The accurate number of entering vehicles allows the accurate calculation of the first vehicle count.

[0022] In addition to the process of detecting entering vehicles (S6-S8, S101, S102), the calculation device 220 also detects exiting vehicles exiting the target section OL (S9). The process of detecting exiting vehicles is repeated (NO in S9). When an exiting vehicle is detected (YES in S9), the calculation device 220 acquires detection information of the exiting vehicle from the second roadside sensor 212 (S10) and decreases (counts down) the first number of vehicles traveling in the target section OL (S11). The calculation device 220 calculates the first number of vehicles traveling in the oncoming lane L2 of the target section OL based on the number of entering vehicles that have entered one of the oncoming lanes L2 of the target section OL and the number of exiting vehicles that have exited the oncoming lane L2 of the target section OL (S12). For example, the calculation device 220 counts up the detected entering vehicles (S6-S8, S101, S102), counts down the detected exiting vehicles (S9-S11), and calculates the first number of vehicles present in the target section OL by subtracting the number of exiting vehicles from the number of entering vehicles (S12). If the initial number is not zero, the initial number is added. Note that Figure 2 shows an example in which the exiting vehicle detection process (S9-S11) is executed after the entering vehicle detection process (S6-S8, S101, S102), but as shown by the dashed dotted line, the exiting vehicle detection process (S9-S11) may be executed first, followed by the entering vehicle detection process (S6-S8, S101, S102), and the first vehicle number may be calculated (S12), or the exiting vehicle detection process (S9-S11) and the entering vehicle detection process (S6-S8, S101, S102) may be executed in parallel, and the first vehicle number may be calculated (S12).

[0023] In the first vehicle number calculation process (S12), the arithmetic device 220 can correct the first vehicle number calculated from the number of entering vehicles and exiting vehicles traveling in the target section OL (S103). The arithmetic device 220 corrects the number of entering vehicles based on the time from when the first roadside sensor 211 detects an entering vehicle to when the first vehicle number is calculated, and corrects the number of exiting vehicles based on the time from when the second roadside sensor 212 detects an exiting vehicle to when the first vehicle number is calculated (S103). Then, the arithmetic device 220 calculates the first vehicle number as the difference between the corrected number of entering vehicles and the corrected number of exiting vehicles (S12). This calculation result has been corrected to eliminate the influence of the processing time from when the entering / exiting vehicles are detected to when the first vehicle number is calculated. When the roadside sensor 210 (211, 212) detects an object, the calculation device 220 determines the object's attributes (vehicle, construction site, etc.) based on the image or measurement data, measures the object's speed and the distance between the object and the target section OL, determines that the vehicle has entered or exited the target section OL, and calculates the first vehicle number from the number of entering and exiting vehicles. In this way, the calculation process from obtaining the detection information to calculating the first vehicle number takes time. The calculation device 220 corrects the number of entering vehicles and the number of exiting vehicles taking this processing time into consideration, and calculates a first number of vehicles that is appropriate to the actual situation. The calculation device 220 corrects the number of entering vehicles by counting vehicles that are predicted to enter the target section OL after the processing time as entering vehicles, and corrects the number of exiting vehicles by counting vehicles that are predicted to exit the target section OL after the processing time as exiting vehicles, taking into consideration the impact of delays in processing time. By setting the difference between the corrected number of entering vehicles and the number of exiting vehicles as the first number of vehicles, the impact of delays in processing time can be eliminated. Furthermore, communication time is required to send the calculated first number of vehicles from the vehicle detection system 200 to the driving assistance device 1. The arithmetic device 220 corrects the number of entering vehicles and the number of exiting vehicles, taking into account the communication time required for communication between the vehicle detection system 200 and the driving assistance device 1 (S103), and calculates the first number of vehicles that is appropriate for the actual situation (S12). The arithmetic device 220 corrects the number of entering vehicles by counting vehicles predicted to enter the target section OL after the communication time as entering vehicles, and corrects the number of exiting vehicles by counting vehicles predicted to exit the target section OL after the communication time as exiting vehicles, taking into account delays according to the required communication time. The difference between the corrected number of entering vehicles and the number of exiting vehicles is used as the first number of vehicles, thereby eliminating the effect of delays in communication time. The correction may take into account both delays due to processing time and delays due to communication time, or may take into account delays due to either one of the delays. In this way, by counting entering vehicles entering the target section OL and exiting vehicles exiting the target section OL while taking into account delays due to processing time and / or communication time, the first number of vehicles can be calculated with high accuracy based on the actual situation. Both the host vehicle V1 and the oncoming vehicle OV approach each other while moving, and the rate at which the relative distance changes is high. For this reason, it is preferable that the first number of vehicles used for driving assistance for the host vehicle V1 is accurate information that indicates the real-time situation. Although the processing time and / or communication time is extremely short, by calculating the first number of vehicles while eliminating the effects of delays and using this, highly accurate driving assistance can be performed. Note that the process of S103 in the flow related to the correction process represented by the dashed line can be skipped.

[0024] Once the first vehicle number is calculated (S12), the calculation device 220 transmits the first vehicle number to the outside of the vehicle detection system 200 or to the driving assistance device 1 via the communication system 240 (S13). The communication system 240 may identify the communication address of the communication device 40 of the driving assistance device 1 and transmit the first vehicle number, or may transmit the first vehicle number to the outside via a short-range communication network. The first vehicle number transmitted via the short-range communication network is received only by vehicles approaching the target section OL (entering the short-range communication range). The driving assistance device 1 is equipped with an application and a communication device 40 required to receive information transmitted from the vehicle detection system 200.

[0025] The processing procedure of the driving assistance device 1 will now be described with reference to FIGS. The processor 10 sets a predetermined route to the destination calculated by the navigation device 5 (S21). The processor 10 refers to the map information 51 to acquire the positions of one or more target sections OL that exist on the predetermined route of the host vehicle V1 (S22), and refers to the lane information 511 to identify the travel lane of the host vehicle V1 on the predetermined route (S23). FIG. 3(a) shows the target section OL that is set between point P1 where the first roadside sensor 211 is installed and point P2 where the second roadside sensor 212 is installed, and the host vehicle V1 approaching this target section OL. The processor 10 identifies the nearest target section OL that the host vehicle V1 is approaching. The processor 10 confirms that the travel lane L1 of the host vehicle in the target section OL is adjacent to the oncoming lane L2. The processor 10 may also confirm that the travel lane L1 including the target section OL belongs to a road with one lane in each direction. The processor 10 compares the current position of the host vehicle V1 with the position of the target section OL, and continuously determines whether the host vehicle V1 has entered the target section OL (NO in S24). If it is determined that the host vehicle V1 is entering the target section OL (YES in S24), the processor 10 identifies an oncoming lane L2 in the target section OL that is adjacent to the driving lane L1 and in which the vehicle is traveling in the opposite direction, and acquires the first number of vehicles in the oncoming lane L2 from the vehicle detection system 200 via the communication device 40 (S25). Specifically, the processor 10 refers to the roadside sensor information 512 in the map information 51, and identifies a roadside sensor 210 provided in the target section OL that the host vehicle V1 has approached within a predetermined distance, and identifies an address for communicating with the calculation device 220 that controls the roadside sensor 210. The processor 10 sends request information requesting the first number of vehicles in the oncoming lane L2 to the identified arithmetic device 220, and acquires the first number of vehicles in the oncoming lane L2 calculated by the vehicle detection system 200 (S25). The processor 10 also acquires the first number of vehicles sent every moment by the arithmetic device 220 that controls the vehicle detection system 200 in the target section OL to which the host vehicle V1 is approaching, using the short-range communication function (S25). The processor 10 can acquire the first number of vehicles only when the distance between the host vehicle V1 and the target section OL falls below a predetermined distance (the distance at which short-range communication is possible). Moreover, because the first number of vehicles is sent every moment, the first number of vehicles received by the host vehicle V1 is the most recently calculated result.

[0026] As shown in FIG. 3(b), when the host vehicle V1 enters the target section OL, the processor 10 uses the on-board sensor 2 mounted on the host vehicle V1 to calculate the number of oncoming vehicles OV3, OV2, and OV1 traveling in the oncoming lane L2 that the host vehicle V1 has passed while traveling in the target section OL as the second vehicle number (S26). The on-board sensor 2 of the host vehicle V1 monitors the detection range SV1 and detects oncoming vehicles OV that the host vehicle V1 has passed. The processor 10 counts up the number of oncoming vehicles OV each time the host vehicle V1 passes an oncoming vehicle OV, and calculates this as the second vehicle number. Although not limited thereto, the processor 10 compares the position of the host vehicle with the position of the oncoming vehicle, and determines that the oncoming vehicle has passed the host vehicle when the rear end position of the oncoming vehicle coincides with the rear end position of the host vehicle. For example, in the situation shown in Fig. 3(c), the processor 10 determines that the host vehicle V1, which entered the target section OL, has passed oncoming vehicles OV3 and OV2, and calculates the second number of oncoming vehicles that the host vehicle V1 has passed since entering the target section OL shown in Fig. 3(b) as "2." The oncoming vehicle OV1 is a vehicle traveling in the target section OL ahead of the host vehicle V1.

[0027] The processor 10 subtracts the second number of oncoming vehicles that the host vehicle V1 has passed after entering the target section OL from the first number of vehicles acquired when the host vehicle V1 enters the target section OL (S27). The difference (number of vehicles) between the first number of oncoming vehicles in the target section OL detected by the vehicle detection system 200 and the second number of oncoming vehicles that the host vehicle V1 has passed is the number of oncoming vehicles OV traveling in the target section OL ahead of the host vehicle V1 that the host vehicle V1 has not yet passed. The processor 10 determines whether the difference between the first vehicle count and the second vehicle count is 1 or more (S28). If the difference is less than 1, i.e., zero (number of vehicles) (NO in S28), the processor 10 determines that there are no oncoming vehicles ahead of the host vehicle V1 (S29). On the other hand, if the difference is 1 or more (YES in S28), the processor 10 determines that there are one or more oncoming vehicles ahead of the host vehicle V1 (S30). The processor 10 outputs the result of the determination to the outside (S31). The processor 10 may output the determination that there is no oncoming vehicle ahead of the host vehicle V1 or that an oncoming vehicle is approaching to the vehicle controller 6 as information for planning autonomous driving such as evasive driving. The processor 10 may also output the result of the determination to the occupant via the output device 20 as information for assisting the occupant in driving. For example, information such as "There are no oncoming vehicles until the next fork" or "An oncoming vehicle is approaching" may be output as audio via the speaker 201 or as a display via the display 202.

[0028] In this way, the processor 10 acquires the current position of the host vehicle V1, and identifies the driving position and driving lane of the host vehicle V1 by referring to map information including lane information and position information of the target section.If it determines that the identified driving lane is adjacent to the oncoming lane and that the host vehicle V1 has approached the target section OL within a predetermined distance, it acquires from the vehicle detection system 200 the first number of oncoming vehicles traveling in the oncoming lane of the target section OL into which the host vehicle V1 is entering, calculates the second number of oncoming vehicles traveling in the oncoming lane that the host vehicle V1 has passed in the target section OL based on the detection information acquired by the onboard sensor 2 of the host vehicle V1, calculates the difference between the first number of vehicles and the second number of vehicles, and if the difference is zero, it determines that there are no oncoming vehicles traveling in the oncoming lane of the target section OL ahead of the host vehicle, and outputs the determination result. According to the method of this embodiment, it is possible to determine whether there is an oncoming vehicle for the host vehicle V1 even if the entire area of ​​the target section OL has not been detected by the roadside sensor 210. The onboard sensor 2 of the host vehicle V1 detects approaching oncoming vehicles and counts the number of vehicles, so it is not necessary to detect the entire area of ​​the target section OL. In other words, according to the driving assistance method of this embodiment, it is possible to determine the presence of an oncoming vehicle regardless of the positional relationship between the host vehicle V1 and the other vehicle OV or the detection performance of the onboard sensor 2 and the roadside sensor 210. In particular, as shown in the examples of Figures 3(a), (b), and (c), when parked vehicles PV1, PV2, and PV3 that are obstacles are present in the traveling direction of the target section OL in which the host vehicle V1 is traveling, the host vehicle V1 needs to overtake them. In order to overtake the parked vehicles PV1, PV2, and PV3, the host vehicle V1 needs to move laterally (in the +X direction in the figure) from the traveling lane L1 toward the oncoming lane L2 and approach or enter the oncoming lane L2 adjacent to the traveling lane L1 to avoid the parked vehicles PV1, PV2, and PV3. In such a situation, information on whether or not an oncoming vehicle OV is present in the traveling direction is important information for the autonomous driving control of the host vehicle V1 or for the driving operation of the occupant to avoid approaching the oncoming vehicle OV. In this embodiment, the driving of the host vehicle V1 can be assisted by outputting a determination that there is or is not an oncoming vehicle ahead during the period from when the host vehicle enters the target section OL until when the host vehicle passes through the target section OL.

[0029] Next, an embodiment in which the driving assistance method is applied to autonomous driving will be described with reference to FIGS. The driving assistance system 100 of this embodiment includes a vehicle controller 6 having an autonomous driving function. The processor 10 uses the vehicle controller 6 to cause the host vehicle V1 to autonomously drive a predetermined route to a destination. The predetermined route includes the target trajectory described above. The target trajectory includes an avoidance trajectory for avoiding an obstacle ahead. When an obstacle is detected ahead of the host vehicle V1, the processor 10 uses the vehicle controller 6 to cause the host vehicle to drive on an avoidance trajectory that avoids approaching the obstacle. The predetermined route includes the avoidance trajectory.

[0030] The processor 10 uses the determination of whether there is or is not an oncoming vehicle ahead in the autonomous driving function. Specifically, the processor 10 of the driving assistance device 1 starts executing evasive driving when an obstacle is detected ahead of the host vehicle V1 that has entered the target section OL and it is determined that there is no oncoming vehicle OV ahead of the host vehicle V1. Figure 4 shows the processing of the driving assistance device 1 when executing the autonomous driving function. Naturally, the driving assistance device 1 also executes the processing shown in Figure 2. To avoid redundant explanation, the above explanation using Figures 1-3 is incorporated herein by reference. Also, although not shown in Figure 4, the vehicle detection system 200 executes processing S1 to S13 shown in Figure 2 to calculate the first vehicle number. As shown in FIG. 4, the processor 10 of the driving assistance device 1 cooperates with the vehicle controller 6 to activate the autonomous driving function (S40). The autonomous driving function may be activated when driving starts (S21 in FIG. 2). The processor 10 continuously determines whether there is an obstacle ahead of the host vehicle V1 based on detection information from the on-board sensor 2 (S41, NO in S41). In this processing example, as shown in FIG. 5(a), a case is taken as an example in which parked vehicles PV1, PV2, and PV3 are detected as obstacles ahead of the host vehicle V1. FIG. 5(a) corresponds to FIG. 3(a).

[0031] When an obstacle is detected ahead of the host vehicle V1 (YES in S41), the processor 10 calculates the difference between the first vehicle number and the second vehicle number, and determines whether the difference is equal to or greater than 1 (S42). To execute the process of S42, the processor 10 of the driving assistance device 1 executes the processes of S21-S27 shown in Fig. 2 in parallel, and the vehicle detection system 200 executes the processes of S1 to S13 shown in Fig. 2 in parallel. In S42, if the difference obtained by subtracting the second number of vehicles from the first number of vehicles is not 1 or more, that is, if the difference is zero (NO in S42), it is determined that there is no oncoming vehicle OV traveling in the oncoming lane L2 in the target section OL ahead of the host vehicle V1 (S43). S42 in Figure 4 corresponds to S28 in Figure 2, and S43 in Figure 4 corresponds to S29 in Figure 2. FIG. 5(a) shows a situation in which the host vehicle V1 has already passed oncoming vehicles OV2 and OV3, and the oncoming vehicle OV1 will approach the host vehicle V1 in the future. FIG. 5(b) shows a situation at a later timing than that shown in FIG. 5(a). FIG. 5(b) shows a situation in which the host vehicle V1 has also passed oncoming vehicle OV1, and there is no oncoming vehicle OV in the oncoming lane L2 ahead of the host vehicle V1. In this situation, the difference between the first vehicle number and the second vehicle number is calculated to be zero. When it is determined that there is no oncoming vehicle OV ahead of the host vehicle V1 (S43), the processor 10 uses the vehicle controller 6 to start the execution of evasive maneuvering by the host vehicle V1 (S44). The processor 10 sends an evasive maneuver start command (GO command) to the vehicle controller 6 to cause the host vehicle V1 to travel along the evasive trajectory. 5(b) schematically shows an avoidance trajectory AVL for the avoidance driving. The processor 10 drives the host vehicle V1 along the avoidance trajectory AVL. During the avoidance driving, the host vehicle V1 moves laterally from the driving lane L1 to the oncoming lane L2 (+X direction in the figure) while moving forward (+Y direction in the figure), overtakes the parked vehicles PV1, PV2, and PV3, moves laterally to the driving lane L1 (-X direction in the figure), and returns to the original driving lane L1. Because the driving lane L1 and the oncoming lane L2 are adjacent lanes, the host vehicle V1 may approach or enter the oncoming lane L2 when passing by the parked vehicles PV1, PV2, and PV3. Even in such a situation, according to the driving assistance method, the host vehicle V1 can confirm that there is no oncoming vehicle OV ahead in the oncoming lane L2, avoid (overtake) the parked vehicles PV1, PV2, and PV3, and return to the driving lane L1. Furthermore, even if an obstacle (parked vehicles PV1, PV2, PV3) is detected ahead of the host vehicle V1 that has entered the target section OL (YES in S41), if it is determined that an oncoming vehicle OV is present ahead of the host vehicle V1 (S47), as shown in Figure 5(a), a command (NO-GO) to prohibit the execution of evasive maneuvering is sent to the vehicle controller 6 (S48), and the host vehicle V1 is stopped (S49).

[0032] According to this driving assistance method, even if the roadside sensor 210 has not detected the entire area of ​​the target section OL, it is possible to determine whether or not there is an oncoming vehicle OV that the host vehicle V1 is about to encounter. Furthermore, because the host vehicle V1 counts the number of oncoming vehicles OV that it has approached and passed, it is possible to determine whether or not there is an oncoming vehicle OV that it will encounter even if the onboard sensor 2 cannot detect the entire area of ​​the target section OL. In other words, the driving assistance device 1 of this embodiment can determine the presence of an oncoming vehicle regardless of the positional relationship between the host vehicle V1 and the oncoming vehicle OV or the detection performance of the onboard sensor 2 and the roadside sensor 210. Therefore, after confirming that there is no oncoming vehicle OV, the host vehicle V1 can be made to perform evasive maneuvering to approach or enter the oncoming lane L2. On the other hand, if it is confirmed that there is an oncoming vehicle OV ahead of the host vehicle V1, the evasive maneuvering is not performed. It is possible to prohibit the host vehicle V1 from performing evasive maneuvering to approach the oncoming lane L2 when an oncoming vehicle OV is approaching the host vehicle V1. 5(a) and 5(b), when parked vehicles PV1, PV2, and PV3 are present ahead of the host vehicle V1 in the traveling direction in a target section OL where the traveling lane L1 and the oncoming lane L2 are adjacent to each other, the host vehicle V1 must move laterally from the traveling lane L1 toward the oncoming lane L2 and approach or enter the oncoming lane L2 to avoid the parked vehicles PV1, PV2, and PV3. In such a situation, the host vehicle V1 can be made to perform evasive maneuvering while maintaining a distance from the oncoming vehicle OV by starting to perform evasive maneuvering involving lateral movement toward the oncoming lane L2 only when there is no oncoming vehicle OV with which the host vehicle V1 may pass. Furthermore, as shown in Figure 5(a), when the target section OL is a road with one lane in each direction, if the host vehicle V1 approaches or enters the oncoming lane L2 to avoid the parked vehicles PV1, PV2, and PV3, the oncoming vehicle OV1 in the oncoming lane L2 must stop or slow down because there is no space (adjacent lane) to avoid the host vehicle V1. As in this embodiment, by starting evasive maneuvering after determining that there is no oncoming vehicle OV, it is possible to prevent the oncoming vehicle OV1 traveling in the oncoming lane L2, which is a single lane (a lane with no other lane to pull over into), from being forced to stop or slow down while the host vehicle V1 is performing evasive maneuvering.

[0033] In this embodiment, as shown in the example of FIG. 5(c), even if the difference between the first vehicle count and the second vehicle count is zero (NO in S42) and it is determined that there is no oncoming vehicle OV ahead of the host vehicle V1 (S43), there is a possibility that there is an oncoming vehicle OV0 that is about to enter the target section OL immediately thereafter. Also, even if an oncoming vehicle OV0 has entered the target section OL, it may not be counted as an oncoming vehicle OV0 due to a delay caused by the detection processing time. The processor 10 takes measures against the newly entering oncoming vehicle OV0 immediately after it is determined that there is no oncoming vehicle OV. Processor 10 monitors for an incoming vehicle entering the target section OL for a first predetermined time after it is determined that no oncoming vehicle OV exists ahead of host vehicle V1 (S45). If roadside sensor 210 detects an oncoming vehicle OV, another vehicle, entering the oncoming lane L2 of the target section OL, within the first predetermined time after it is determined that no oncoming vehicle OV exists ahead of host vehicle V1 (YES in S46), processor 10 prohibits the execution of evasive maneuvering (S48) and stops host vehicle V1 (S49). On the other hand, if no oncoming vehicle entering the target section OL is detected within the first predetermined time (NO in S46), processor 10 starts the execution of evasive maneuvering in accordance with the determination in S43 (S44). Note that the processes S45-S46 indicated by dashed lines in FIG. 2 are auxiliary processes and can be skipped. In this embodiment, even if it is determined that there is no oncoming vehicle OV traveling in the target section OL ahead of the host vehicle V1, the avoidance driving is not started immediately, but the detection result for the first predetermined time is confirmed before the avoidance driving is started. This prevents a vehicle that has not been determined (counted) as an entering vehicle from suddenly appearing and becoming an oncoming vehicle OV, which could affect the avoidance driving of the host vehicle V1. Here, the first predetermined time can be set based on the time from when the roadside sensor 210 detects another vehicle to when the processor 10 acquires the first vehicle number information. In reality, an oncoming OV vehicle may be approaching the target section OL. However, even if the oncoming OV vehicle has entered the target section OL, it may not be recognized due to a delay associated with the detection processing time. In this embodiment, the first predetermined time is defined based on the delay time due to the processing of the driving assistance system 100, thereby enabling driving assistance to be performed that takes into account the presence of an oncoming OV vehicle that is recognized late. As a result, even if a delay occurs in determining the presence of an oncoming OV vehicle, waiting for the first predetermined time eliminates the influence of the delay and allows the start timing of avoidance driving to be appropriately controlled. For example, the influence of delays due to any one or more of the detection processing by the roadside sensor 210 of the vehicle detection system 200, the recognition processing by the arithmetic device 220, the transmission processing by the communication system 240, the reception processing by the communication device 40 of the driving assistance device 1, and the information processing by the processor 10 can be eliminated. Furthermore, the first predetermined time may be calculated by calculating the time required for another vehicle to pass the host vehicle V1 after entering the target section OL based on the distance from the host vehicle V1, which has stopped or decelerated in front of the parked vehicles PV1, PV2, and PV3, to the first roadside sensor 211 (the exit of the target section OL) ahead and the vehicle speed limit of the target section OL, and adding a large margin to the calculated time, or by setting the first predetermined time to several times (e.g., 10 times) the calculated time. If the oncoming vehicle OV does not pass the host vehicle V1 for longer than the first predetermined time defined in this way, it is determined that the oncoming vehicle OV has parked on the upstream side of the target section OL (the side closer to the first roadside sensor 211), and the host vehicle V1 is not forced to wait unnecessarily. The distance from the host vehicle V1 to the first roadside sensor 211 ahead can be calculated based on the current position of the host vehicle V1 by referring to the map information 51. In addition, it is preferable to set the first predetermined time period shorter than the time it takes for the host vehicle V1, which has stopped or slowed down in front of the parked vehicles PV1, PV2, and PV3, to start moving laterally and completely drift into the oncoming lane L2. Even if the oncoming vehicle OV is recognized late, the host vehicle V1 can stop before it completely drifts into the oncoming lane L2, ensuring space for the oncoming vehicle OV to pass the host vehicle V1.

[0034] In this embodiment, if the difference between the first vehicle number and the second vehicle number is 1 or more (YES in S42) and it is determined that an oncoming vehicle OV is present in front of the host vehicle V1 (S47), the execution of evasive maneuvering is prohibited (S48) and the host vehicle V1 is stopped (S49). In the driving assistance method of this embodiment, the timing for starting evasive maneuvering of the stopped host vehicle V1 is calculated. Specifically, the processor 10 uses the on-board sensor 2 to monitor the presence and number of oncoming vehicles OV that the host vehicle will pass over for a second predetermined time period (S50). If the processor 10 does not detect any oncoming vehicles OV that the host vehicle V1 has passed over during the second predetermined time period after the host vehicle V1 has entered the target section OL (NO in S51), the processor 10 starts evasive maneuvering (S44). On the other hand, if the processor 10 detects any oncoming vehicles OV that the host vehicle V1 has passed over during the second predetermined time period (YES in S51), the processor 10 prohibits evasive maneuvering (S48) and maintains the stopped state of the host vehicle V1 (S49). Then, as shown by the dashed line, the processing of S21-S27 is performed again, followed by the processing of S50-S51, and a state in which the vehicle does not pass the oncoming vehicle OV for a second predetermined time is detected (NO in S51), and evasive driving is initiated at the time this state is detected (S44). In this driving assistance method, if an oncoming OV that the host vehicle V1 is about to pass is not detected for a second predetermined time, it is determined that there is a high possibility that no oncoming OV has newly entered. Even if it is determined that the difference between the first vehicle number and the second vehicle number is 1 or more (YES in S42), or if an entering vehicle is detected (YES in S46), if the oncoming vehicle V1 does not pass the host vehicle V1 for the second predetermined time, it can be predicted that the oncoming vehicle V1 has parked in a parking section provided in the oncoming lane L2 before passing the host vehicle V1. In such a case, the driving assistance method starts evasive maneuvering without waiting for an oncoming vehicle OV that is unlikely to pass. As a result, even if there is a possibility that an oncoming vehicle OV is present ahead of the host vehicle V1 (YES in S42, YES in S46), the method determines that there is little possibility of passing the oncoming vehicle OV and finds an opportunity to perform evasive maneuvering. In other words, if the oncoming vehicle OV does not pass the host vehicle V1 after waiting for the second predetermined time, the method assumes that the oncoming vehicle OV has parked along the way, and starts evasive maneuvering to overtake the parked vehicles PV1, PV2, and PV3 of the host vehicle V1. In this process, it is preferable that the second predetermined time be set longer as the distance between the host vehicle V1 and the first roadside sensor 211 ahead is longer. FIG. 5(c) shows the distance D1 of the target section OL defined between the position P1 of the first roadside sensor 211 and the position P2 of the second roadside sensor 212, and the distance D2 between the host vehicle V1 that has entered the target section OL and the first roadside sensor 211 ahead. The distance D2 corresponds to the distance from when the oncoming vehicle OV0 enters the target section OL until it passes the host vehicle V1. The longer the distance D2, the longer the time required for the oncoming vehicle OV0 that has newly entered the target section OL to pass the host vehicle V1. Since the second predetermined time is set according to the length of time required for the oncoming vehicle OV0 that has newly entered the target section OL and the host vehicle V1 to pass each other, the time for observing whether or not there is an oncoming vehicle OV0 can be set appropriately. By waiting for the approach of the oncoming vehicle OV0 for the second predetermined time, it is possible to prevent the host vehicle V1 from performing evasive maneuvering before the oncoming vehicle OV0 approaching the host vehicle V1 and the oncoming vehicle OV0 passing each other. It is also possible to avoid stopping the host vehicle V1 for a long period of time that exceeds the time required for the newly entering oncoming vehicle OV0 and the host vehicle V1 to pass each other. Furthermore, in this process, the higher the speed limit of the oncoming lane L2 in the target section OL, the shorter the second predetermined time is set. The higher the speed limit of the oncoming lane L2 in which the oncoming vehicle OV is traveling, the shorter the time required for the oncoming vehicle OV that has entered the target section OL to pass the host vehicle V1. Since the second predetermined time is set according to the speed limit of the oncoming lane L2, which is a factor in this required time, it is possible to set the second predetermined time as an appropriate observation time. In other words, it is possible to avoid starting evasive maneuvering before the host vehicle V1 and the oncoming vehicle OV pass each other, and to avoid stopping the host vehicle V1 for an unnecessarily long period of time. [Explanation of symbols]

[0035] 100... driving assistance system, 1... driving assistance device, 10... processor, 11... CPU, 12... ROM, 13... RAM, 20... output device, 201... speaker, 202... display, 30... input device, 40... communication device, 2... on-board sensor, 21... camera, 22... radar device, 3... vehicle information acquisition device, 31... position detection device, 4... information acquisition device, 5... navigation device, 51... map information, 511... lane information, 512... roadside sensor information, 6... vehicle controller, 61... steering control device, 62... drive control device, 200... vehicle detection system, 210... roadside sensor, 211... first roadside sensor, 212... second roadside sensor, 220... arithmetic device, 230... map information, 240... communication system

Claims

1. A driving assistance method for assisting driving of a vehicle, which is used in a processor of a driving assistance device capable of communicating with a vehicle detection system including a plurality of roadside sensors installed on a road, comprising: The vehicle detection system Identifying a target section where no branch exists between the two roadside sensors; calculating a first number of vehicles traveling on each lane of the target section based on the number of entering vehicles that have entered each lane of the target section detected by the roadside sensor and the number of exiting vehicles that have exited the target section; The processor of the driving assistance device When the vehicle enters the driving lane of the target section, the first vehicle number of oncoming vehicles that are the vehicles traveling in an oncoming lane adjacent to the driving lane is acquired from the vehicle detection system; calculating a second number of oncoming vehicles that the host vehicle has passed while the host vehicle is traveling in the travel lane of the target section, using a sensor mounted on the host vehicle; Calculating a difference between the first number of vehicles and the second number of vehicles; If the difference is zero, it is determined that there is no oncoming vehicle traveling in the target section ahead of the host vehicle; A driving assistance method in which the result of the determination is output to an external device.

2. The driving assistance device further includes a vehicle controller that causes the host vehicle to autonomously drive a predetermined route, The processor: when an obstacle ahead of the host vehicle is detected using the sensor, causing the host vehicle to drive along the predetermined route to avoid the obstacle using the vehicle controller; 2. The driving assistance method according to claim 1, wherein, when the obstacle is detected ahead of the vehicle that has entered the target section and it is determined that there is no oncoming vehicle traveling in the target section ahead of the vehicle, the method starts executing evasive driving that causes the vehicle to drive along the predetermined route that avoids the obstacle.

3. 3. The driving assistance method according to claim 2, wherein the processor prohibits the execution of the evasive maneuver when it determines that an oncoming vehicle traveling in the target section is present in front of the vehicle, even if the obstacle is detected in front of the vehicle that has entered the target section.

4. 3. The driving assistance method according to claim 2, wherein the processor prohibits the execution of the evasive maneuver when the roadside sensor detects another vehicle entering the oncoming lane of the target section within a first predetermined time after it is determined that there is no oncoming vehicle traveling in the target section ahead of the vehicle.

5. The driving assistance method according to claim 4 , wherein the first predetermined time is set based on a time from when the roadside sensor detects the other vehicle to when the processor acquires the first number of vehicles.

6. 3. The driving assistance method according to claim 2, wherein, even if the difference between the first number of vehicles and the second number of vehicles is 1 or more, if the oncoming vehicle that the host vehicle has passed is not detected within a second predetermined time since the host vehicle entered the target section, the processor determines that there is no oncoming vehicle traveling in the target section ahead of the host vehicle, and executes the evasive driving.

7. The driving assistance method according to claim 6 , wherein the second predetermined time is set to be longer as the distance between the host vehicle traveling in the target section and the roadside sensor ahead increases.

8. The driving assistance method according to claim 6 , wherein the second predetermined time is set to be shorter as the vehicle speed limit of the oncoming lane in the target section increases.

9. 2. The driving assistance method according to claim 1, wherein the vehicle detection system sets the first number of vehicles present in the target section to zero if the entering vehicle entering the oncoming lane of the target section is not detected within a reference time.

10. The driving assistance method according to claim 9 , wherein the reference time is set to be longer as the distance of the target section is longer.

11. The driving assistance method according to claim 9 , wherein the reference time is set to be shorter as the vehicle speed limit in the target section is higher.

12. The driving assistance method according to claim 1, wherein the vehicle detection system acquires the direction of the vehicle entering the target section detected by the roadside sensor and / or the position of the vehicle's blinker, determines that the vehicle facing the direction of the target section and / or the vehicle with its blinker turned on in the direction of the target section is the entering vehicle, and counts up the number of the entering vehicles.

13. 2. The driving assistance method according to claim 1, wherein the vehicle detection system corrects the number of entering vehicles and the number of exiting vehicles based on the time from when the roadside sensor detects the entering vehicle or the exiting vehicle to when the first number of vehicles is calculated and / or the communication time required for communication between the vehicle detection system and the driving assistance device, and calculates the difference between the corrected number of entering vehicles and the corrected number of exiting vehicles as the first number of vehicles.

14. 2. The driving assistance method of claim 1, wherein the vehicle detection system calculates the number of entering vehicles entering the oncoming lane of the target section based on first detection information acquired from a first roadside sensor among the roadside sensors, the first roadside sensor being installed at one end of the target section, calculates the number of exiting vehicles exiting the target section based on detection information acquired from a second roadside sensor being installed at the other end of the target section, and calculates the first number of vehicles traveling in each of the lanes of the target section by subtracting the number of exiting vehicles from the number of entering vehicles.

15. The driving assistance method according to claim 1 , wherein the target section is set to be a road with one lane in each direction.

16. A driving assistance device capable of communicating with a vehicle detection system including a plurality of roadside sensors installed on a road, the driving assistance device assisting driving of a vehicle, The vehicle detection system Identifying a target section where no branch exists between the two roadside sensors; calculating a first number of vehicles traveling on each lane of the target section based on the number of entering vehicles that have entered each lane of the target section detected by the roadside sensor and the number of exiting vehicles that have exited the target section; The processor of the driving assistance device When the vehicle enters the driving lane of the target section, the first vehicle number of oncoming vehicles that are the vehicles traveling in an oncoming lane adjacent to the driving lane is acquired from the vehicle detection system; calculating a second number of oncoming vehicles that the host vehicle has passed while the host vehicle is traveling in the travel lane of the target section, using a sensor mounted on the host vehicle; Calculating a difference between the first number of vehicles and the second number of vehicles; If the difference is zero, it is determined that there is no oncoming vehicle traveling in the target section ahead of the host vehicle; A driving assistance device that outputs the result of the judgment to the outside.

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