Travel control device and travel control method

Abstract

The purpose of the present invention is to provide a technology that makes it possible to accurately predict that an adjacent vehicle will change lanes into the area in front of a host vehicle. A travel control device comprises: a probability prediction unit (13) for predicting, on the basis of peripheral vehicle information and road information, the probability of an adjacent vehicle of changing lanes into the area in front of a host vehicle; a tracking candidate selection unit (14) for selecting a tracking candidate vehicle on the basis of a current probability and at least one of a future probability and the presence of acceleration or deceleration by the adjacent vehicle; and a tracking target selection unit (15) for selecting a tracking target vehicle from among vehicles ahead and the tracking candidate vehicle.

Description

Driving control device and driving control method

[0001] The present disclosure relates to a cruise control device and a cruise control method.

[0002] Various technologies have been proposed for cruise control devices that control the travel of a host vehicle so that the host vehicle follows another vehicle, taking into account the lane change of the other vehicle. For example, a vehicle behavior estimation device described in Patent Document 1 predicts, based on a speed profile, whether the speed of the other vehicle will be equal to or less than a threshold within a predetermined time from the point at which a decrease in the absolute value of the relative speed of the other vehicle begins to be detected, and accumulates the prediction results to calculate a confidence factor. Then, when the confidence factor exceeds the threshold, the vehicle behavior estimation device estimates that the other vehicle will change lanes ahead of the host vehicle.

[0003] International Publication No. 2021 / 205192

[0004] However, in the above technology, the confidence level is calculated by accumulating the prediction results of whether the speed of the other vehicle will be equal to or less than a threshold, which takes a long time. As a result, the other vehicle may change lanes before the calculation is completed. In such a case, depending on the speed difference between the other vehicle and the subject vehicle, the subject vehicle and the other vehicle may get too close to each other, which may cause a dangerous situation or a sudden deceleration of the subject vehicle, resulting in a deterioration of ride comfort.

[0005] Therefore, the present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a technology that can appropriately predict when an adjacent vehicle will change lanes in front of the vehicle.

[0006] The driving control device according to the present disclosure includes a surrounding vehicle information acquisition unit that acquires surrounding vehicle information including the positions and speeds of surrounding vehicles that are vehicles around the host vehicle; a road information acquisition unit that acquires road information around the host vehicle; a probability prediction unit that predicts the probability that an adjacent vehicle that is a surrounding vehicle and is located in an adjacent lane of the host vehicle will change lanes in front of the host vehicle based on the surrounding vehicle information and the road information; a following candidate selection unit that selects a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from among the adjacent vehicles based on at least one of the future probability and whether or not the adjacent vehicle will decelerate, and the current probability; a following target selection unit that selects a following target vehicle that the host vehicle should follow from among the preceding vehicles that are surrounding vehicles that are located in the same lane in front of the host vehicle and in the same lane as the host vehicle, and the following candidate vehicles; a target trajectory generation unit that generates a target trajectory along which the host vehicle should travel based on the following target vehicle; and a driving control unit that controls the travel of the host vehicle based on the target trajectory.

[0007] According to the present disclosure, the probability that an adjacent vehicle will change lanes ahead of the host vehicle is predicted based on surrounding vehicle information and road information, and a candidate vehicle to be followed is selected based on the future probability, at least one of whether the adjacent vehicle is decelerating, and the current probability, and a target vehicle to be followed is selected from the leading vehicle and the candidate vehicles to be followed. With this configuration, it is possible to appropriately predict that an adjacent vehicle will change lanes ahead of the host vehicle. Objects, features, aspects, and advantages of the present disclosure will become more apparent from the following detailed description and the accompanying drawings.

[0008] 1 is a block diagram showing the configuration of a cruise control device according to a first embodiment. FIG. 2 is a diagram for explaining a prediction by a probability prediction unit according to the first embodiment. FIG. 3 is a diagram for explaining a prediction by the probability prediction unit according to the first embodiment. FIG. 4 is a diagram for explaining a prediction by the probability prediction unit according to the first embodiment. FIG. 5 is a contour diagram showing an example of a lane change probability. FIG. 6 is a contour diagram showing an example of a lane change probability. FIG. 7 is a flowchart showing the operation of the probability prediction unit according to the first embodiment. FIG. 8 is a flowchart showing the operation of a following candidate selection unit according to the first embodiment. FIG. 9 is a diagram for explaining the operation of a cruise control device according to the first embodiment. FIG. 10 is a diagram for explaining the operation of a cruise control device according to the first embodiment. FIG. 11 is a diagram for explaining the operation of a cruise control device according to the first embodiment. FIG. 12 is a diagram for explaining the operation of a cruise control device according to the first embodiment. FIG. 13 is a flowchart showing the operation of a following candidate selection unit according to the second embodiment. FIG. 14 is a diagram for explaining the operation of a cruise control device according to the second embodiment. FIG. 15 is a flowchart showing the operation of a following candidate selection unit according to a modified example. FIG. 16 is a block diagram showing the configuration of a cruise control device according to a third embodiment. FIG. 17 is a diagram for explaining the determination by a lane change determination unit according to the third embodiment. FIG. 18 is a flowchart showing the operation of a following candidate selection unit according to the third embodiment. FIG. 19 is a diagram for explaining the operation of a cruise control device according to the third embodiment. Fig. 10 is a diagram for explaining the operation of the cruise control device according to Embodiment 3. Fig. 11 is a block diagram showing the hardware configuration of the cruise control device according to another modified example. Fig. 12 is a block diagram showing the hardware configuration of the cruise control device according to another modified example.

[0009] <Embodiment 1> Fig. 1 is a block diagram showing the configuration of a cruise control device 1 according to Embodiment 1. The cruise control device 1 in Fig. 1 is connected to a vehicle state detection device 2, a surroundings monitoring device 3, a host vehicle position detection device 4, a map information acquisition device 5, and an actuator 8.

[0010] The vehicle state detection device 2 includes, for example, an acceleration sensor, a gyro sensor, a wheel speed sensor, a steering angle sensor, and a torque sensor, and detects the state of the host vehicle, such as its speed, acceleration, yaw rate, steering angle, etc. The vehicle state detection device 2 outputs the detection results to the cruise control device 1.

[0011] The periphery monitoring device 3 includes, for example, a camera, radar, LiDAR (Light Detection and Ranging), sonar, etc., and detects surrounding vehicles around the host vehicle, stationary objects, road markings, road shoulders, side walls, etc. The periphery monitoring device 3 outputs the detection results to the cruise control device 1.

[0012] The vehicle position detection device 4 includes, for example, a Global Navigation Satellite System (GNSS) antenna and LiDAR, and detects the position of the vehicle in map information. The vehicle position detection device 4 outputs the detection result to the cruise control device 1.

[0013] The map information acquisition device 5 acquires map information including, for example, the number of lanes, the position and shape of each lane and dividing line, the type of each lane, the road type, the speed limit, information on signs and traffic lights, and the positions of merging sections, branching sections, and construction sections. The map information acquisition device 5 may acquire the map information from a map stored in a car navigation system or a high-precision locator within the vehicle, or may acquire the map information via wireless communication from a server outside the vehicle. The map information acquisition device 5 outputs the map information to the driving control device 1.

[0014] The cruise control device 1 generates a command value for controlling the travel of the host vehicle so that the host vehicle follows the target vehicle, which is the vehicle that the host vehicle should follow, based on information output from the vehicle state detection device 2, the surroundings monitoring device 3, the host vehicle position detection device 4, and the map information acquisition device 5. The cruise control device 1 then outputs the command value to the actuator 8. This cruise control device 1 will be described in detail later.

[0015] The actuators 8 include, for example, a power train such as an engine and a motor of the host vehicle (not shown), brakes, and electric power steering, and operate based on command values ​​output from the cruise control device 1. The cruise control device 1 controls the actuators 8 based on the command values ​​to control the traveling of the host vehicle.

[0016] <Cruise Control Device 1> Next, a detailed description will be given of the cruise control device 1. The cruise control device 1 includes a surrounding vehicle information acquisition unit 11, a road information acquisition unit 12, a probability prediction unit 13, a follow-up candidate selection unit 14, a follow-up target selection unit 15, a target trajectory generation unit 16, and a cruise control unit 17.

[0017] 1 , the vehicle state detection device 2, the periphery monitoring device 3, the host vehicle position detection device 4, the map information acquisition device 5, and the actuator 8 are provided outside the cruise control device 1. However, the cruise control device 1 may include at least one of the vehicle state detection device 2, the periphery monitoring device 3, the host vehicle position detection device 4, the map information acquisition device 5, and the actuator 8. In this specification, for example, "at least one of A, B, C, ..., and Z" means any one of all combinations of one or more types extracted from the group of A, B, C, ..., and Z.

[0018] The surrounding vehicle information acquisition unit 11 acquires surrounding vehicle information indicating the status of surrounding vehicles, which are vehicles surrounding the host vehicle, based on the detection results of the periphery monitoring device 3. The surrounding vehicles are, for example, vehicles located within a range detectable by the host vehicle. The surrounding vehicle information includes, for example, information such as the position, speed, acceleration, moving direction, size, and type of the surrounding vehicles. The surrounding vehicle information acquisition unit 11 may generate surrounding vehicle information including the relative position and relative speed of the surrounding vehicles with respect to the host vehicle based on the detection results of the vehicle state detection device 2, the periphery monitoring device 3, and the host vehicle position detection device 4. Furthermore, for example, if the surrounding vehicle information is generated outside the driving control device 1, the surrounding vehicle information acquisition unit 11 may acquire the surrounding vehicle information from an external source.

[0019] The road information acquisition unit 12 acquires road information about the vicinity of the vehicle based on the detection results of the periphery monitoring device 3 and the vehicle position detection device 4, and the map information of the map information acquisition device 5. The road information includes, for example, position information of road dividing lines, road shoulders, side walls, merging sections, branching sections, construction sections, etc. detected by the periphery monitoring device 3, and information about the vicinity of the vehicle position detected by the vehicle position detection device 4 from the map information acquired by the map information acquisition device. Note that the road information acquisition unit 12 is not limited to the above, as long as it can acquire road information.

[0020] The probability prediction unit 13 predicts the probability that an adjacent vehicle, which is a nearby vehicle located in an adjacent lane to the host vehicle, will change lanes ahead of the host vehicle, based on surrounding vehicle information including the relative positions and relative speeds of the surrounding vehicles relative to the host vehicle and road information. In the following description, this probability may also be referred to as "lane change probability." Note that if the surrounding vehicle information includes the positions and speeds of the surrounding vehicles rather than the relative positions and relative speeds of the surrounding vehicles relative to the host vehicle, the probability prediction unit 13 may predict the lane change probability based on the position and speed of the host vehicle, the surrounding vehicle information, and road information.

[0021] 2 is a diagram illustrating the prediction of the lane-change probability by the probability prediction unit 13 according to the first embodiment. Fig. 2 shows a first coordinate plane defined by a horizontal axis, which is a first coordinate axis indicating the relative position of an adjacent vehicle, and a vertical axis, which is a second coordinate axis indicating the relative speed of the adjacent vehicle. Using a boundary line L1 on the first coordinate plane, the probability prediction unit 13 calculates a position component D, which is the distance in the horizontal axis direction between the boundary line L1 and a point on the first coordinate plane indicating the relative position and relative speed of the adjacent vehicle, and predicts the lane-change probability based on the position component D.

[0022] Here, assume that the point indicating the relative position and relative speed of the adjacent vehicle approaches the boundary line L1 from above (positive relative speed side) or to the right (positive relative position side) of the boundary line L1, and the absolute value of the position component D becomes small. If the absolute value of the position component D is small, the relative position and relative speed of the adjacent vehicle are not large enough for the adjacent vehicle to overtake the host vehicle. Therefore, if the point indicating the relative position and relative speed of the adjacent vehicle is located above or to the right of the boundary line L1 and the absolute value of the position component D is small, the probability prediction unit 13 predicts a small value as the lane change probability that the adjacent vehicle will change lanes ahead of the host vehicle.

[0023] On the other hand, if the point indicating the relative position and relative speed of the adjacent vehicle is located above or to the right of the boundary line L1 and the absolute value of the position component D is large, the probability prediction unit 13 predicts a large value as the lane change probability that the adjacent vehicle will change lanes ahead of the own vehicle.

[0024] When the point indicating the relative position and relative speed of the adjacent vehicle is located below (negative relative speed side) or to the left (negative relative position side) of boundary line L1, position component D corresponds to the probability that the adjacent vehicle will change lanes to the rear of the host vehicle rather than in front of it. In the first embodiment, the probability prediction unit 13 calculates a positive value as position component D when the point indicating the relative position and relative speed of the adjacent vehicle is located above or to the right of boundary line L1, and calculates a negative value as position component D when the point is located below or to the left of boundary line L1.

[0025] In the first embodiment, the boundary line L1 is expressed by the following equation (1). Note that xr and vr respectively represent the relative position and relative speed of the adjacent vehicle relative to the host vehicle in the traveling direction, and w is a coefficient that takes a positive value. sign(vr) is a sign function that takes +1 if vr is positive and takes -1 if vr is negative. d is a value that reflects the front-to-rear width of the host vehicle's body, but in the following description it will be assumed to be 0.

[0026]

[0027] The probability prediction unit 13 may estimate factor information including at least one of the distance to and the arrival time to a lane change factor based on at least one of surrounding vehicle information and road information. The lane change factor here includes locations and events that may cause an adjacent vehicle to change lanes ahead of the host vehicle, such as a merging section, a branching section, a construction section, and a stopped or slow-moving vehicle ahead of the adjacent vehicle. For example, the probability prediction unit 13 may estimate factor information including at least one of the distance to and the arrival time to a lane change factor, such as a stopped vehicle, based on the position and speed of the host vehicle and surrounding vehicle information. Furthermore, for example, the probability prediction unit 13 may estimate factor information including at least one of the distance to and the arrival time to a lane change factor, such as a merging section, based on the position and speed of the host vehicle and location information of a merging section, a branching section, a construction section, etc. included in the road information.

[0028] Based on the factor information, the probability prediction unit 13 may move the portion of the boundary line L1 around the origin closer to the vertical axis (i.e., the coordinate axis of the relative speed) as shown by the dotted line in Fig. 2. For example, as shown in Fig. 3, the probability prediction unit 13 may move the portion of the boundary line L1 around the origin closer to the vertical axis as shown by the dotted line in Fig. 2 by decreasing the coefficient w in equation (1) as the distance to the lane change factor or the arrival time to the lane change factor becomes shorter.

[0029] With this configuration, when the distance to the lane-change factor or the arrival time to the lane-change factor is short, the position component D between points A and B, which have roughly the same relative position but different relative speeds, and the dotted boundary line L1 is substantially the same, as shown in Figure 2. Therefore, when the distance to the lane-change factor or the arrival time to the lane-change factor is short, it is possible to place more importance on the relative position than the relative speed in predicting the lane-change probability. Note that the probability prediction unit 13 may change the value of the coefficient w depending on whether the relative speed vr is positive or negative.

[0030] 4 is a diagram for explaining the prediction of the lane change probability by the probability prediction unit 13 according to the first embodiment. Fig. 4 shows a second coordinate plane defined by the horizontal axis, which is the third coordinate axis indicating the position component D, and the vertical axis, which is the fourth coordinate axis indicating the lane change probability. The probability prediction unit 13 predicts the lane change probability from the position component D using a line L2 on the second coordinate plane.

[0031] In the first embodiment, the line L2 is expressed by the following equation (2): where K is a coefficient that takes a positive value.

[0032]

[0033] Based on the factor information, the probability prediction unit 13 may bring the lane change probability closer to 1 in a portion of the line L2 where the position component D is greater than 0, which is a threshold, as shown by the dotted line in Fig. 4 , and may bring the lane change probability closer to 0 in a portion of the line L2 where the position component D is less than 0, which is a threshold. For example, as shown in Fig. 5 , the probability prediction unit 13 may increase the coefficient K in equation (2) as the distance or arrival time to the lane change factor decreases, thereby bringing the portion of the line L2 that is greater than 0 closer to 1, as shown by the dotted line in Fig. 4 , and the portion of the line L2 that is less than 0 closer to 1. With this configuration, when the distance or arrival time to the lane change factor is short, the ambiguity of the lane change probability near the boundary line L1 can be reduced.

[0034] Fig. 6 is a contour diagram showing an example of the distribution of lane change probability when the distance or arrival time to the lane change factor is large. The shape of the boundary line in Fig. 6 where the distance or arrival time to the lane change factor is large corresponds to the shape of the solid line boundary line L1 in Fig. 2, and the lane change probability near the boundary line in Fig. 6 changes slowly as shown by the solid line in Fig. 4.

[0035] Fig. 7 is a contour diagram showing an example of the distribution of lane change probability when the distance or arrival time to the lane change factor is short. The shape of the boundary line in Fig. 7 where the distance or arrival time to the lane change factor is short corresponds to the shape of the dotted boundary line L1 in Fig. 2, and the lane change probability near the boundary line in Fig. 7 changes suddenly as shown by the dotted line in Fig. 4.

[0036] As described above, the probability prediction unit 13 predicts the lane change probability based on the surrounding vehicle information and road information. Note that the boundary line L1 in Fig. 2 and the line L2 in Fig. 4 that define the distribution of lane change probability are not limited to the curves expressed by the above equations, and may be, for example, curves expressed by other equations or curved straight lines such as stepped lines.

[0037] In the first embodiment, the probability prediction unit 13 not only predicts the current lane change probability based on current surrounding vehicle information and road information, but also predicts future surrounding vehicle information and road information for a certain time period from the present. For example, the probability prediction unit 13 predicts the future state of the adjacent vehicle, such as the position and speed, by assuming that the adjacent vehicle will move at a constant velocity or constant acceleration at the speed or acceleration detected for the adjacent vehicle. Note that the probability prediction unit 13 may also predict the future state of the adjacent vehicle by taking into consideration that the host vehicle will move along a target trajectory generated by the target trajectory generation unit 16 (described later) in a previous process. The probability prediction unit 13 predicts the future state of the host vehicle in the same way as predicting the future state of the adjacent vehicle.

[0038] The probability prediction unit 13 predicts future surrounding vehicle information and road information (e.g., future relative positions, relative speeds, and factor information) based on the prediction results of the future states of the vehicle and adjacent vehicles. Then, the probability prediction unit 13 predicts the future lane change probability based on the future surrounding vehicle information and road information.

[0039] The following candidate selection unit 14 selects a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from the adjacent vehicles based on the current lane change probability and the future lane change probability. In the first embodiment, the following candidate selection unit 14 selects, as a following candidate vehicle, an adjacent vehicle whose current relative position is equal to or greater than a first threshold, whose current lane change probability is equal to or greater than a second threshold, and whose future lane change probability is equal to or greater than a third threshold.

[0040] The following candidate selection unit 14 may select, as a following candidate vehicle, an adjacent vehicle whose current lane change probability is equal to or greater than the second threshold and whose future lane change probability is equal to or greater than the third threshold, without taking into account the current relative position. The second threshold and the third threshold may be the same value or different values. Furthermore, if there are multiple adjacent vehicles that satisfy all of the above conditions, the following candidate selection unit 14 may select, as a following candidate vehicle, the vehicle that is closest to the vehicle among the multiple adjacent vehicles. For convenience, in the following description, the first threshold, the second threshold, and the third threshold may not be distinguished.

[0041] The target vehicle selection unit 15 selects a target vehicle to be followed by the host vehicle from a preceding vehicle, which is a nearby vehicle located in the same lane ahead of the host vehicle, and the candidate vehicles to be followed selected by the candidate vehicle selection unit 14. In the first embodiment, the target vehicle selection unit 15 selects the vehicle closest to the host vehicle from the preceding vehicle and the candidate vehicles to be followed as the target vehicle to be followed. However, this is not limited to this. For example, the target vehicle selection unit 15 may calculate a time to collision between the host vehicle and each of the preceding vehicle and the candidate vehicle to be followed, and select the vehicle with the shortest time to collision between the preceding vehicle and the candidate vehicle to be followed as the target vehicle to be followed. The time to collision between the preceding vehicle or the candidate vehicle to be followed and the host vehicle is calculated based on, for example, the relative position and relative speed of the preceding vehicle or the candidate vehicle to be followed, and is the time from the current time until the preceding vehicle or the candidate vehicle to be followed collides with the host vehicle.

[0042] The target trajectory generating unit 16 generates a target trajectory along which the host vehicle should travel, based on the vehicle to be followed selected by the vehicle to be followed selecting unit 15. In the first embodiment, the target trajectory generating unit 16 generates at least one trajectory from among the target acceleration, the target speed, the target position, and the target inter-vehicle distance as the target trajectory.

[0043] For example, when a vehicle to be followed is selected by the vehicle to be followed selection unit 15, the target trajectory generation unit 16 may generate, as the target trajectory, a trajectory for the host vehicle to travel at the same speed as the vehicle to be followed, at a position separated by a target inter-vehicle distance from the vehicle to be followed. Also, for example, when there is no adjacent vehicle and no vehicle to be followed is selected, that is, when there are neither adjacent vehicles nor preceding vehicles, the target trajectory generation unit 16 may generate, as the target trajectory, a trajectory for the host vehicle to travel at a target speed set by the driver or the like.

[0044] Furthermore, for example, if an adjacent vehicle exists but a vehicle to be followed has not been selected, the target trajectory generating unit 16 may generate, as a tentative trajectory, a trajectory that would be generated if neither an adjacent vehicle nor a preceding vehicle exists, i.e., a trajectory in which the host vehicle travels at the target speed. Note that, as a case in which an adjacent vehicle exists but a vehicle to be followed has not been selected, for example, a case in which an adjacent vehicle exists whose relative position, current lane change probability, or future lane change probability is smaller than the threshold value, but no preceding vehicle exists.

[0045] The target trajectory generating unit 16 that generated the tentative trajectory may then generate a trajectory that allows the host vehicle to travel at an acceleration equal to or less than that which would occur if the host vehicle were to virtually travel along the tentative trajectory. This configuration makes it possible to generate a target trajectory that does not result in a positive acceleration, or to generate a target trajectory that involves a certain degree of deceleration. In other words, since the host vehicle can be decelerated in advance, it can safely decelerate when an adjacent vehicle that was not selected as a vehicle to be followed changes lanes.

[0046] Furthermore, for example, in a case where an adjacent vehicle exists but a preceding vehicle is selected as the vehicle to be followed, the target trajectory generating unit 16 may generate a tentative trajectory that would be generated if no adjacent vehicle exists and the preceding vehicle is selected as the vehicle to be followed.The target trajectory generating unit 16 that generated the tentative trajectory may then generate, as the target trajectory, a trajectory that can be traveled at an acceleration equal to or lower than that which would occur if the host vehicle were to virtually travel along the tentative trajectory.With this configuration, as with the above, the host vehicle can be decelerated in advance, and therefore can be safely decelerated when an adjacent vehicle not selected as the vehicle to be followed changes lanes.

[0047] The driving control unit 17 controls the driving of the host vehicle based on the target trajectory. In the first embodiment, the driving control unit 17 calculates command values ​​for the host vehicle to drive along the target trajectory, and outputs the command values ​​to the actuator 8. For example, the driving control unit 17 calculates a target acceleration, a target deceleration, a target torque, and the like as command values ​​to be output to the actuator 8 by performing feedback control or the like so that the actual speed approaches the target speed.

[0048] <Operation> Fig. 8 is a flowchart showing the operation of the probability prediction unit 13 according to the present embodiment 1. The operation in Fig. 8 is repeatedly performed as appropriate while the host vehicle is traveling.

[0049] In step S1, the probability prediction unit 13 recognizes an adjacent vehicle based on surrounding vehicle information. The processing from step S2 onwards is performed for the adjacent vehicle recognized in step S1. In step S2, the probability prediction unit 13 predicts the current lane change probability of the adjacent vehicle based on the current surrounding vehicle information and road information. In step S3, the probability prediction unit 13 predicts future surrounding vehicle information and road information based on the current surrounding vehicle information and road information. In step S4, the probability prediction unit 13 predicts the future lane change probability of the adjacent vehicle based on the future surrounding vehicle information and road information. Thereafter, the operation of FIG. 8 ends.

[0050] 9 is a flowchart showing the operation of the follow-up candidate selection unit 14 according to the present embodiment 1. The operation in FIG. 9 is repeatedly performed as appropriate while the host vehicle is traveling.

[0051] In step S11, the following candidate selector 14 determines whether the relative position of the adjacent vehicle is equal to or greater than a first threshold value. If it is determined that the relative position is equal to or greater than the first threshold value, the process proceeds to step S12. If it is determined that the relative position is smaller than the first threshold value, the process proceeds to step S14.

[0052] In step S12, the following candidate selector 14 determines whether the current lane change probability of the adjacent vehicle is equal to or greater than a second threshold value. If it is determined that the current lane change probability is equal to or greater than the second threshold value, the process proceeds to step S13. If it is determined that the current lane change probability is smaller than the second threshold value, the process proceeds to step S14.

[0053] In step S13, the following candidate selection unit 14 determines whether the probability of a future lane change of the adjacent vehicle is equal to or greater than a third threshold value. If it is determined that the probability of a future lane change is equal to or greater than the third threshold value, the process proceeds to step S14. If it is determined that the probability of a future lane change is smaller than the third threshold value, the process proceeds to step S14.

[0054] In step S14, the following candidate selection unit 14 determines whether or not the processes of steps S11 to S13 have been performed for all adjacent vehicles recognized by the probability prediction unit 13. If it is determined that the processes have been performed, the process proceeds to step S15, and if it is determined that the processes have not been performed, the process proceeds to step S11.

[0055] In step S15, the follow-up candidate selection unit 14 selects an adjacent vehicle that satisfies all of the conditions of steps S11 to S13 as a follow-up candidate vehicle. If there are multiple adjacent vehicles that satisfy all of the conditions of steps S11 to S13, the follow-up candidate selection unit 14 selects the vehicle closest to the host vehicle as a follow-up candidate vehicle. The operation of FIG. 9 then ends. If there are no multiple adjacent vehicles that satisfy all of the conditions of steps S11 to S13, the follow-up candidate selection unit 14 does not select a follow-up candidate vehicle, and the operation of FIG. 9 ends. The follow-up candidate selection unit 14 may also apply hysteresis to the first to third threshold values ​​in the current process so as to lower the first to third threshold values ​​for adjacent vehicles selected as follow-up candidate vehicles in the previous process. This configuration allows the follow-up candidate vehicle to be kept at a single vehicle as much as possible, thereby suppressing the hunting phenomenon of follow-up candidate vehicles.

[0056] Similar to the hysteresis in the selection of the candidate vehicle to be followed, the selection of the target vehicle to be followed may also have hysteresis. For example, the distance between the target vehicle selected in the previous process and the subject vehicle may be greater than the distance between the vehicle closest to the subject vehicle in the current process by a value equal to or less than a threshold, and the distances between the two may be substantially the same. In such a case, the target vehicle selection unit 15 may select the target vehicle selected in the previous process as the target vehicle to be followed in the current process. This configuration allows the target vehicle to be kept at one vehicle as much as possible, thereby suppressing the hunting phenomenon of the target vehicle to be followed.

[0057] 10 to 14 are diagrams illustrating the operation of the cruise control device 1 according to the first embodiment. In the cases of FIGS. 10 to 13, the current and future lane change probabilities of adjacent vehicle 21a are both equal to or greater than a threshold, but at least one of the current and future lane change probabilities of adjacent vehicle 21b is smaller than the threshold. In this case, the following candidate selection unit 14 does not select adjacent vehicle 21b as a following candidate vehicle, but selects adjacent vehicle 21a as a following candidate vehicle.

[0058] 10 to 12, the target to be followed selection unit 15 selects, as the target vehicle to be followed, the preceding vehicle 22 and the adjacent vehicles 21a which are candidate vehicles to be followed, whichever is closest to the own vehicle 23. On the other hand, in the case of Fig. 13, the target to be followed selection unit 15 selects, as the target vehicle to be followed, the preceding vehicle 22 which is closest to the own vehicle 23, from the preceding vehicle 22 and the adjacent vehicles 21a which are candidate vehicles to be followed.

[0059] 14, the current and future lane change probabilities of adjacent vehicle 21a are both equal to or greater than a threshold, and the current and future lane change probabilities of adjacent vehicle 21b are both equal to or greater than a threshold. In this case, of adjacent vehicles 21a and 21b, the following candidate selection unit 14 selects adjacent vehicle 21b, which is closest to the host vehicle 23, as the following candidate vehicle. In the case of FIG. 14, the following target selection unit 15 selects, as the following target vehicle, the adjacent vehicle 21b, which is closest to the host vehicle 23, of the preceding vehicle 22 and the following candidate vehicles, 21b.

[0060] Summary of First Embodiment According to the cruise control device 1 of the first embodiment described above, the probability prediction unit 13 predicts the lane change probability based on surrounding vehicle information and road information, the candidate vehicle selection unit 14 selects a candidate vehicle to be followed based on the current lane change probability and the future lane change probability, and the target vehicle selection unit 15 selects a target vehicle to be followed from the preceding vehicle and the candidate vehicles to be followed. This configuration makes it possible to accurately predict in a short time that an adjacent vehicle will change lanes ahead of the host vehicle. This reduces the possibility of the host vehicle and another vehicle getting too close to each other, resulting in a dangerous situation or the host vehicle suddenly decelerating, resulting in a deterioration in ride comfort.

[0061] In the first embodiment, the probability prediction unit 13 moves the portion of the boundary line L1 used to predict the lane change probability around the origin closer to the coordinate axis of the relative speed based on the factor information. With this configuration, when the distance to the lane change factor or the arrival time is short, it is possible to place more importance on the relative position than the relative speed in predicting the lane change probability.

[0062] Furthermore, in the first embodiment, the probability prediction unit 13, based on the factor information, brings the probability of a portion of the line L2 where the position component D is greater than the threshold closer to 1, and brings the probability of a portion of the line L2 where the position component D is smaller than the threshold closer to 0. With this configuration, when the distance or arrival time to the lane change factor is short, it is possible to reduce the ambiguity of the lane change probability near the boundary line L1.

[0063] Furthermore, in the first embodiment, when an adjacent vehicle exists but a vehicle to be followed has not been selected, the target trajectory generation unit 16 generates, as a target trajectory, a trajectory that can be traveled at an acceleration rate equal to or lower than that which would occur if the host vehicle were to travel on the tentative trajectory. Furthermore, in the first embodiment, when an adjacent vehicle exists but a preceding vehicle has been selected as a vehicle to be followed, the target trajectory generation unit 16 generates, as a target trajectory, a trajectory that can be traveled at an acceleration rate equal to or lower than that which would occur if the host vehicle were to travel on the tentative trajectory. With this configuration, the host vehicle can be decelerated in advance, so that it can safely decelerate when an adjacent vehicle that has not been selected as a vehicle to be followed changes lanes.

[0064] <Embodiment 2> A block diagram showing the configuration of a driving control device 1 according to Embodiment 2 is similar to the block diagram in Fig. 1. Hereinafter, among the components according to Embodiment 2, components that are the same as or similar to the components described above will be assigned the same or similar reference numerals, and different components will be mainly described.

[0065] Fig. 15 is a flowchart showing the operation of the following candidate selection unit 14 according to the second embodiment. The operation in Fig. 15 is the same as the operation in Fig. 9 with steps S21 and S22 added, and therefore steps S21 and S22 will be mainly described below. As in the operation in Fig. 15, the following candidate selection unit 14 selects a following candidate vehicle based on the probability of a future lane change, the probability of a current lane change, and whether or not an adjacent vehicle is decelerating.

[0066] In step S21 after step S15, the follow-up candidate selection unit 14 determines whether the adjacent vehicle selected as the follow-up candidate vehicle is decelerating. As a first example, the follow-up candidate selection unit 14 determines that the adjacent vehicle has decelerated if the decrease in speed of the adjacent vehicle is equal to or greater than a threshold. As a second example, the follow-up candidate selection unit 14 determines that the adjacent vehicle has decelerated if the decrease in speed of the adjacent vehicle is equal to or greater than the threshold for a predetermined period of time or longer. As a third example, the follow-up candidate selection unit 14 determines that the adjacent vehicle has decelerated if the inter-vehicle distance between the adjacent vehicle selected as the vehicle to be followed and the subject vehicle is smaller than the target inter-vehicle distance used in the target trajectory by equal to or greater than a threshold.

[0067] The following candidate selection unit 14 may perform the determination in step S21 not only for the adjacent vehicle selected as the following candidate vehicle in the previous process but also for the adjacent vehicle selected in the current process.The following candidate selection unit 14 may perform the determination in step S21 using the maximum speed of the adjacent vehicle from the time it was selected as the following candidate vehicle until the current process as the speed of the adjacent vehicle.

[0068] If it is determined in step S21 that the adjacent vehicle selected as the follow-up candidate vehicle is decelerating, processing proceeds to step S22, and if it is determined that the adjacent vehicle is not decelerating, the operation of Figure 15 ends.

[0069] In step S22, the following candidate selection unit 14 excludes the adjacent vehicle determined to be decelerating in step S21 from the following candidate vehicles. The process then proceeds to step S15. In step S15 after step S22, the following candidate selection unit 14 selects the vehicle closest to the host vehicle as the following candidate vehicle from the adjacent vehicles that can be selected as the following candidate vehicles, excluding the adjacent vehicle determined to be decelerating in step S21. Although not shown, if there are no adjacent vehicles that can be selected as the following candidate vehicles after excluding the adjacent vehicle determined to be decelerating in step S21, the operation of FIG. 15 ends.

[0070] FIG. 16 is a diagram illustrating the operation of the cruise control device 1 according to the second embodiment. In the example shown in FIG. 16, the current and future lane change probabilities of the adjacent vehicle 21a are both equal to or greater than a threshold, and the current and future lane change probabilities of the adjacent vehicle 21b are both equal to or greater than a threshold, and it is determined that the adjacent vehicle 21b is decelerating. In the first embodiment, even if it is determined that the adjacent vehicle 21b is decelerating, the candidate to be followed selection unit 14 selects the adjacent vehicle 21b as the vehicle to be followed. In contrast, in the second embodiment, the candidate to be followed selection unit 14 excludes the adjacent vehicle 21b determined to be decelerating from the candidates to be followed, and therefore selects the adjacent vehicle 21a as the vehicle to be followed. Then, the target to be followed selection unit 15 selects the adjacent vehicle 21a closest to the vehicle 23 as the vehicle to be followed from among the leading vehicle 22 and the adjacent vehicle 21a, which is a candidate vehicle to be followed.

[0071] Summary of Second Embodiment According to the cruise control device 1 of the second embodiment described above, the following candidate selection unit 14 selects a following candidate vehicle based on the probability of a future lane change, the probability of a current lane change, and whether or not the adjacent vehicle is decelerating. This configuration makes it possible to accurately predict in a short time that the adjacent vehicle will change lanes ahead of the host vehicle.

[0072] <Modification> When an adjacent vehicle decelerates, the future relative speed of the adjacent vehicle decreases, and therefore the probability of the adjacent vehicle changing lanes in the future decreases. In other words, there is a certain correspondence between the deceleration of the adjacent vehicle and the probability of the adjacent vehicle changing lanes in the future. Therefore, the following candidate selection unit 14 may select a following candidate vehicle based on the current lane change probability and whether or not the adjacent vehicle is decelerating, without using the probability of the future lane change.

[0073] 17 is a flowchart showing the operation of the follow-up candidate selection unit 14 according to this modification. The operation of FIG. 17 is the same as the operation of FIG. 15 except that step S13 is deleted and step S15 is changed to step S15a. In step S15a, the follow-up candidate selection unit 14 selects an adjacent vehicle that satisfies all of the conditions of steps S11 and S12 as a follow-up candidate vehicle. The processing of step S15a after step S22 is the same as the processing of step S15 after step S22 described in the second embodiment.

[0074] According to this modification, it is possible to accurately predict in a short time that an adjacent vehicle will change lanes ahead of the host vehicle. From the descriptions of the first and second embodiments and this modification, it is understood that the following candidate selection unit 14 may select a following candidate vehicle based on at least one of the probability of a future lane change and whether or not the adjacent vehicle is decelerating, and the current probability of a lane change. This also applies to the third embodiment.

[0075] 18 is a block diagram showing the configuration of a driving control device 1 according to a third embodiment. In the following, of the components according to the third embodiment, components that are the same as or similar to the components described above are given the same or similar reference numerals, and different components will be mainly described.

[0076] The configuration of Fig. 18 is the same as the configuration of Fig. 1 with the addition of a lane change determination unit 18. The lane change determination unit 18 determines whether the adjacent vehicle will change lanes ahead of the host vehicle based on at least one of the position of the adjacent vehicle in the adjacent lane, the lateral speed of the adjacent vehicle, and whether or not the turn signal of the adjacent vehicle is on.

[0077] As a first example, the lane change determination unit 18 determines whether or not the adjacent vehicle will change lanes based on the lateral position, which is the position of the adjacent vehicle in the adjacent lane, and the lateral speed, which is the lateral speed of the adjacent vehicle. For example, as shown in Fig. 19 , the lane change determination unit 18 determines whether or not the adjacent vehicle will change lanes using a boundary line L3 on a coordinate plane between the lateral position and the lateral speed. In the example of Fig. 19 , the lane change determination unit 18 determines that the adjacent vehicle will not change lanes if the adjacent vehicle is located near the center of the lane (i.e., the lateral position is small) and the lateral speed of the adjacent vehicle is small, and determines that the adjacent vehicle will change lanes in other cases.

[0078] As a second example, the lane change determination unit 18 determines whether the adjacent vehicle is changing lanes based on whether the turn signal of the adjacent vehicle is on. For example, the lane change determination unit 18 determines that the adjacent vehicle is changing lanes when the turn signal of the adjacent vehicle is flashing.

[0079] As a third example, the lane change determination unit 18 determines whether or not the adjacent vehicle has changed lanes by combining the first and second examples. For example, when the direction indicator on the host vehicle side of the adjacent vehicle is flashing, the lane change determination unit 18 may change the boundary line L3 in FIG. 19 so as to approach the origin.

[0080] The following candidate selection unit 14 selects a following candidate vehicle from the adjacent vehicles based on the future lane change probability, the current lane change probability, whether the adjacent vehicle is decelerating, and the determination result of the lane change determination unit 18.

[0081] Fig. 20 is a flowchart showing the operation of the tracking candidate selection unit 14 according to the present embodiment 3. The operation in Fig. 20 is the same as the operation in Fig. 15 except that steps S31 and S32 are added and step S15 is changed to step S15b, so steps S31, S32, and S15b will be mainly described below.

[0082] If it is determined in step S11 that the relative position is equal to or greater than the first threshold, the process proceeds to step S31. In step S31, the lane change determination unit 18 determines whether the adjacent vehicle will change lanes ahead of the host vehicle based on at least one of the position of the adjacent vehicle in the adjacent lane, the lateral speed of the adjacent vehicle, and whether the turn signal of the adjacent vehicle is on. If it is determined that the adjacent vehicle will change lanes ahead of the host vehicle, the process proceeds to step S14. If it is determined that the adjacent vehicle will not change lanes ahead of the host vehicle, the process proceeds to step S12.

[0083] In step S15b, the following candidate selection unit 14 selects the vehicle closest to the vehicle as the following candidate vehicle from among the adjacent vehicles that satisfy all of the conditions in steps S11 to S13 and the adjacent vehicles that the lane change determination unit 18 has determined will change lanes ahead of the vehicle.

[0084] If it is determined in step S21 that the adjacent vehicle selected as the vehicle to be followed is decelerating, the process proceeds to step S32. In step S32, the vehicle to be followed selector 14 determines whether the adjacent vehicle determined in step S21 to be decelerating is the adjacent vehicle determined in step S31 by the lane change determiner 18 to be changing lanes ahead of the host vehicle. If it is determined that the decelerating adjacent vehicle is the adjacent vehicle determined by the lane change determiner 18 to be changing lanes, the operation of Fig. 20 ends. If it is determined that the decelerating adjacent vehicle is not the adjacent vehicle determined by the lane change determiner 18 to be changing lanes, the process proceeds to step S22.

[0085] 20 described above, the following candidate selection unit 14 may add the adjacent vehicle determined by the lane change determination unit 18 to be changing lanes to the options for the following candidate vehicle in step S15, regardless of the lane change probability determined by the probability prediction unit 13. Then, if the adjacent vehicle determined to be decelerating in step S21 is the adjacent vehicle determined by the lane change determination unit 18 to be changing lanes ahead of the host vehicle in step S31, the following candidate selection unit 14 may select the adjacent vehicle as the following candidate vehicle.

[0086] 21 and 22 are diagrams for explaining the operation of the cruise control device 1 according to the third embodiment. In the case of FIG. 21 , the current and future lane change probabilities of adjacent vehicle 21a are both equal to or greater than a threshold, and the current and future lane change probabilities of adjacent vehicle 21b are both equal to or greater than a threshold, and the lane change determination unit 18 has determined that adjacent vehicle 21a will change lanes. In this case, the following candidate selection unit 14 selects adjacent vehicle 21b, which is closest to the host vehicle 23, as the following candidate vehicle. Then, the following target selection unit 15 selects, as the following target vehicle, the adjacent vehicle 21b, which is closest to the host vehicle 23, from the leading vehicle 22 and the adjacent vehicle 21b, which is a following candidate vehicle.

[0087] 22 , the current and future lane change probabilities of adjacent vehicle 21a are both equal to or greater than the threshold, and the current and future lane change probabilities of adjacent vehicle 21b are both smaller than the threshold, but adjacent vehicle 21b has been determined to change lanes by lane change determination unit 18. In this case, of adjacent vehicles 21a and 21b, the following candidate selection unit 14 selects adjacent vehicle 21b that is closest to host vehicle 23 as the following candidate vehicle. Then, of the preceding vehicle 22 and adjacent vehicles 21b that are following candidate vehicles, the following target selection unit 15 selects adjacent vehicle 21b that is closest to host vehicle 23 as the following target vehicle.

[0088] Summary of Third Embodiment According to the cruise control device 1 of the third embodiment described above, the following candidate selection unit 14 selects a following candidate vehicle from among adjacent vehicles based on the future lane change probability, the current lane change probability, whether the adjacent vehicle is decelerating, and the determination result of the lane change determination unit 18. With this configuration, even if the lane change probability of the adjacent vehicle is low, if the lane change determination unit 18 determines that the adjacent vehicle will change lanes, the adjacent vehicle can be selected as a vehicle to be followed. This reduces the possibility of the host vehicle and another vehicle getting too close to each other, resulting in a dangerous situation, or the host vehicle suddenly decelerating, resulting in a deterioration in ride comfort.

[0089] <Modification> The probability prediction unit 13 may predict the lane change probability as a first lane change probability, and the lane change determination unit 18 may calculate a second lane change probability. For example, similar to the position component D of the probability prediction unit 13, the lane change determination unit 18 may set a coordinate plane of the lateral position and lateral velocity and calculate the second lane change probability based on the distance between the boundary line L3 and a point indicating the lateral position and lateral velocity. With this configuration, the lane change determination unit 18 can determine whether the adjacent vehicle will change lanes by comparing the second lane change probability with a threshold. Furthermore, when the lane change determination unit 18 calculates the second lane change probability, the following candidate selection unit 14 may perform processing by replacing the current and future first lane change probabilities calculated by the probability prediction unit 13 with the second lane change probability calculated by the lane change determination unit 18.

[0090] <Other Modifications> The surrounding vehicle information acquisition unit 11, road information acquisition unit 12, probability prediction unit 13, follow-up candidate selection unit 14, follow-up target selection unit 15, target trajectory generation unit 16, and driving control unit 17 shown in Fig. 1 described above will be referred to as the "surrounding vehicle information acquisition unit 11, etc." The surrounding vehicle information acquisition unit 11, etc. is realized by a processing circuit 81 shown in Fig. 23. That is, the processing circuit 81 includes a surrounding vehicle information acquisition unit 11 that acquires surrounding vehicle information including the positions and speeds of surrounding vehicles that are vehicles around the host vehicle, a road information acquisition unit 12 that acquires road information around the host vehicle, a probability prediction unit 13 that predicts the probability that an adjacent vehicle that is a surrounding vehicle located in an adjacent lane of the host vehicle will change lanes ahead of the host vehicle based on the surrounding vehicle information and the road information, a following candidate selection unit 14 that selects a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from the adjacent vehicles based on at least one of a future probability and whether the adjacent vehicle is decelerating and a current probability, a following target selection unit 15 that selects a following target vehicle that the host vehicle should follow from a preceding vehicle that is a surrounding vehicle located in the same lane ahead of the host vehicle and the following candidate vehicles, a target trajectory generation unit 16 that generates a target trajectory along which the host vehicle should travel based on the following target vehicle, and a driving control unit 17 that controls the driving of the host vehicle based on the target trajectory. The processing circuit 81 may be implemented by dedicated hardware or a processor that executes a program stored in memory. Examples of processors include central processing units, processing units, arithmetic units, microprocessors, microcomputers, and DSPs (Digital Signal Processors).

[0091] When the processing circuit 81 is dedicated hardware, the processing circuit 81 corresponds to, for example, a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The functions of each unit such as the surrounding vehicle information acquisition unit 11 may be realized by a circuit in which the processing circuits are distributed, or the functions of each unit may be realized together by a single processing circuit.

[0092] When the processing circuit 81 is a processor, the functions of the surrounding vehicle information acquisition unit 11 and the like are realized in combination with software, etc. Note that the software, etc., includes, for example, software, firmware, or software and firmware. The software, etc., is written as a program and stored in memory. As shown in FIG. 24 , the processor 82 applied to the processing circuit 81 realizes the functions of each unit by reading and executing the program stored in the memory 83. That is, the driving control device 1 includes a memory 83 for storing a program that, when executed by the processing circuit 81, results in the following steps: acquiring surrounding vehicle information including the positions and speeds of surrounding vehicles that are vehicles around the host vehicle; acquiring road information about the host vehicle; predicting the probability that an adjacent vehicle that is a surrounding vehicle located in an adjacent lane of the host vehicle will change lanes ahead of the host vehicle based on the surrounding vehicle information and the road information; selecting a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from the adjacent vehicles based on at least one of a future probability, whether or not the adjacent vehicle is decelerating, and a current probability; selecting a following target vehicle that the host vehicle should follow from a preceding vehicle that is a surrounding vehicle located in the same lane ahead of the host vehicle and the following candidate vehicles; generating a target trajectory along which the host vehicle should travel based on the following target vehicle; and controlling the travel of the host vehicle based on the target trajectory. In other words, this program can be said to cause a computer to execute the procedures and methods of the surrounding vehicle information acquisition unit 11, etc.Here, the memory 83 may be, for example, a non-volatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), or an EEPROM (Electrically Erasable Programmable Read Only Memory), a HDD (Hard Disk Drive), a magnetic disk, a flexible disk, an optical disk, a compact disk, a mini disk, a DVD (Digital Versatile Disc), a drive device for any of these, or any storage medium to be used in the future.

[0093] The above describes a configuration in which each function of the surrounding vehicle information acquisition unit 11 and the like is realized either by hardware or software, etc. However, the present invention is not limited to this, and a configuration in which a part of the surrounding vehicle information acquisition unit 11 and the like is realized by dedicated hardware and another part is realized by software, etc. For example, the function of the surrounding vehicle information acquisition unit 11 can be realized by a processing circuit 81 as dedicated hardware, and the other functions can be realized by the processing circuit 81 as a processor 82 reading and executing a program stored in a memory 83.

[0094] As described above, the processing circuitry 81 can realize the above-described functions by hardware, software, or a combination of these.

[0095] The driving control device described above can also be applied to a driving control system constructed as a system by appropriately combining a processing device, a communication terminal, the functions of an application installed on at least one of the processing device and the communication terminal, and a server. Communication terminals include, for example, mobile phones, smartphones, and tablets. The functions or components of the driving control device described above may be distributed among the devices that make up the system, or may be centrally located in one of the devices.

[0096] In this disclosure, 'a' and 'an' mean one or more. Therefore, 'a', 'an', 'one or more', and 'at least one' can be used interchangeably.

[0097] It should be noted that the embodiments (and their modifications) can be freely combined, and the embodiments and modifications can be modified or omitted as appropriate. The above description is illustrative in all respects and is not limiting. It is understood that countless modifications not illustrated can be envisioned.

[0098] Various aspects of the present disclosure are summarized below as appendices.

[0099] a road information acquisition unit that acquires road information about the vicinity of the host vehicle; a probability prediction unit that predicts the probability that an adjacent vehicle, which is a peripheral vehicle and located in an adjacent lane of the host vehicle, will change lanes in front of the host vehicle based on the surrounding vehicle information and the road information; a candidate to be followed selection unit that selects a candidate to be followed from the adjacent vehicles, which is a candidate vehicle that the host vehicle should follow, based on at least one of the future probability and whether or not the adjacent vehicle will decelerate, and the current probability; a target to be followed selection unit that selects a target to be followed from the host vehicle, which is a vehicle that the host vehicle should follow, from among the preceding vehicles, which are peripheral vehicles located in the same lane in front of the host vehicle and in front of the host vehicle, and the candidate to be followed vehicles; a target trajectory generation unit that generates a target trajectory along which the host vehicle should travel, based on the target to be followed vehicle; and a travel control unit that controls the travel of the host vehicle based on the target trajectory.

[0100] (Supplementary Note 2) A driving control device according to Supplementary Note 1, wherein the probability prediction unit estimates factor information including at least one of the distance to and arrival time of a lane change factor based on at least one of the surrounding vehicle information and the road information, predicts the probability using a boundary line on a first coordinate plane defined by a first coordinate axis indicating the position of the adjacent vehicle and a second coordinate axis indicating the speed of the adjacent vehicle, and moves a portion of the boundary line around the origin closer to the second coordinate axis based on the factor information.

[0101] (Supplementary Note 3) A driving control device according to Supplementary Note 2, wherein the probability prediction unit predicts the probability using a line on a second coordinate plane defined by a third coordinate axis indicating a position component between the boundary line and a point on the first coordinate plane indicating the position and speed of the adjacent vehicle, and a fourth coordinate axis indicating the probability, and based on the factor information, brings the probability of a portion of the line where the position component is greater than a threshold closer to 1, and brings the probability of a portion of the line where the position component is smaller than the threshold closer to 0.

[0102] (Supplementary Note 4) A driving control device described in any one of Supplementary Note 1 to Supplementary Note 3, further comprising a lane change determination unit that determines whether the adjacent vehicle will change lanes ahead of the host vehicle based on at least one of the position of the adjacent vehicle in the adjacent lane, the lateral speed of the adjacent vehicle, and whether or not the turn signal of the adjacent vehicle is on, and the following candidate selection unit selects the following candidate vehicle from the adjacent vehicles based on at least one of the future probability and whether or not the adjacent vehicle is decelerating, the current probability, and the determination result of the lane change determination unit.

[0103] (Appendix 5) A driving control device described in any one of Appendices 1 to 4, wherein the following candidate selection unit determines that the adjacent vehicle has decelerated when the decrease in speed of the adjacent vehicle is equal to or greater than a threshold, and selects the following candidate vehicle from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

[0104] (Appendix 6) A driving control device described in any one of Appendices 1 to 5, wherein the following candidate selection unit determines that the adjacent vehicle has decelerated when the decrease in speed of the adjacent vehicle remains equal to or greater than a threshold for a predetermined period of time or longer, and selects the following candidate vehicle from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

[0105] (Supplementary Note 7) A driving control device described in any one of Supplementary Notes 1 to 6, wherein the following candidate selection unit determines that the adjacent vehicle has decelerated when the inter-vehicle distance between the adjacent vehicle selected as the vehicle to be followed and the subject vehicle is smaller than the target inter-vehicle distance used in the target trajectory by a threshold or more, and selects the following candidate vehicle from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

[0106] (Appendix 8) A driving control device according to any one of appendices 1 to 7, wherein the target trajectory generation unit, when the adjacent vehicle is present but the vehicle to be followed is not selected, generates a tentative trajectory that is generated when neither the adjacent vehicle nor the preceding vehicle is present, and generates as the target trajectory a trajectory that can be traveled at an acceleration equal to or less than that which would occur if the host vehicle were to travel on the tentative trajectory.

[0107] (Supplementary Note 9) A driving control device according to any one of Supplementary Note 1 to Supplementary Note 8, wherein the target trajectory generation unit generates a tentative trajectory that would be generated if the adjacent vehicle does not exist and the preceding vehicle is selected as the vehicle to be followed, when the adjacent vehicle exists but the preceding vehicle is selected as the vehicle to be followed, and generates as the target trajectory a trajectory that can be traveled at an acceleration equal to or less than that which would occur if the host vehicle were to travel on the tentative trajectory.

[0108] (Supplementary Note 10) A driving control method comprising: acquiring surrounding vehicle information including positions and speeds of surrounding vehicles that are vehicles around the host vehicle; acquiring road information around the host vehicle; predicting the probability that an adjacent vehicle that is a surrounding vehicle and located in an adjacent lane of the host vehicle will change lanes in front of the host vehicle based on the surrounding vehicle information and the road information; selecting a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from the adjacent vehicles based on at least one of the future probability and whether the adjacent vehicle is decelerating and the current probability; selecting a following target vehicle that the host vehicle should follow from the following candidate vehicles and a preceding vehicle that is a surrounding vehicle located in the same lane in front of the host vehicle and

[0109] 1 Driving control device, 11 Surrounding vehicle information acquisition unit, 12 Road information acquisition unit, 13 Probability prediction unit, 14 Following candidate selection unit, 15 Following target selection unit, 16 Target trajectory generation unit, 17 Driving control unit, 18 Lane change determination unit, L1 Boundary line, L2 Line.

Claims

1. A driving control device comprising: a surrounding vehicle information acquisition unit that acquires surrounding vehicle information including positions and speeds of surrounding vehicles that are vehicles around the host vehicle; a road information acquisition unit that acquires road information around the host vehicle; a probability prediction unit that predicts the probability that an adjacent vehicle that is a surrounding vehicle and located in an adjacent lane of the host vehicle will change lanes in front of the host vehicle based on the surrounding vehicle information and the road information; a following candidate selection unit that selects a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from among the adjacent vehicles based on at least one of the future probability, whether or not the adjacent vehicle is decelerating, and the current probability; a following target selection unit that selects a following target vehicle that the host vehicle should follow from among the preceding vehicles that are surrounding vehicles located in the same lane in front of the host vehicle and the following candidate vehicles; a target trajectory generation unit that generates a target trajectory along which the host vehicle should travel based on the following target vehicle; and a driving control unit that controls the travel of the host vehicle based on the target trajectory.

2. A driving control device as described in claim 1, wherein the probability prediction unit estimates factor information including at least one of the distance to and arrival time of a lane change factor based on at least one of the surrounding vehicle information and the road information, predicts the probability using a boundary line on a first coordinate plane defined by a first coordinate axis indicating the position of the adjacent vehicle and a second coordinate axis indicating the speed of the adjacent vehicle, and brings a portion of the boundary line around the origin closer to the second coordinate axis based on the factor information.

3. A driving control device as described in claim 2, wherein the probability prediction unit predicts the probability using a line on a second coordinate plane defined by a third coordinate axis indicating the position component between the boundary line and a point on the first coordinate plane indicating the position and speed of the adjacent vehicle, and a fourth coordinate axis indicating the probability, and based on the factor information, brings the probability of the part of the line where the position component is greater than a threshold closer to 1, and brings the probability of the part of the line where the position component is smaller than the threshold closer to 0.

4. A driving control device as claimed in any one of claims 1 to 3, further comprising a lane change determination unit that determines whether the adjacent vehicle will change lanes ahead of the host vehicle based on at least one of the position of the adjacent vehicle in the adjacent lane, the lateral speed of the adjacent vehicle, and whether or not the turn signal of the adjacent vehicle is on, and the following candidate selection unit selects the following candidate vehicle from the adjacent vehicles based on at least one of the future probability and whether or not the adjacent vehicle is decelerating, the current probability, and the determination result of the lane change determination unit.

5. A driving control device as described in any one of claims 1 to 4, wherein the following candidate selection unit determines that the adjacent vehicle has decelerated when the decrease in speed of the adjacent vehicle is equal to or greater than a threshold, and selects the following candidate vehicle from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

6. A driving control device as claimed in any one of claims 1 to 5, wherein the following candidate selection unit determines that the adjacent vehicle has decelerated when the decrease in speed of the adjacent vehicle remains at or above a threshold for a predetermined period of time or longer, and selects the following candidate vehicle from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

7. A driving control device as described in any one of claims 1 to 6, wherein the candidate vehicle to be followed selection unit determines that the adjacent vehicle has decelerated when the inter-vehicle distance between the adjacent vehicle selected as the vehicle to be followed and the subject vehicle is smaller than the target inter-vehicle distance used in the target trajectory by a threshold or more, and selects the candidate vehicle to be followed from the adjacent vehicles based on whether the adjacent vehicle has decelerated and the current probability.

8. A driving control device according to any one of claims 1 to 7, wherein the target trajectory generation unit, when the adjacent vehicle is present but the vehicle to be followed is not selected, generates a tentative trajectory that is generated when neither the adjacent vehicle nor the preceding vehicle is present, and generates as the target trajectory a trajectory that can be traveled at an acceleration equal to or less than that which would occur if the host vehicle were to travel on the tentative trajectory.

9. A driving control device according to any one of claims 1 to 8, wherein the target trajectory generation unit generates a tentative trajectory that would be generated if the adjacent vehicle does not exist and the preceding vehicle is selected as the vehicle to be followed, when the adjacent vehicle exists but the preceding vehicle is selected as the vehicle to be followed, and generates as the target trajectory a trajectory that can be traveled at an acceleration equal to or less than that which would occur if the host vehicle were to travel on the tentative trajectory.

10. A driving control method comprising: acquiring surrounding vehicle information including positions and speeds of surrounding vehicles that are vehicles around the host vehicle; acquiring road information around the host vehicle; predicting the probability that an adjacent vehicle that is a surrounding vehicle and located in an adjacent lane of the host vehicle will change lanes in front of the host vehicle based on the surrounding vehicle information and the road information; selecting a following candidate vehicle that is a candidate vehicle that the host vehicle should follow from the adjacent vehicles based on at least one of the future probability and whether the adjacent vehicle is decelerating and the current probability; selecting a following target vehicle that the host vehicle should follow from the following candidate vehicles and the preceding vehicles that are surrounding vehicles located in the same lane in front of the host vehicle; generating a target trajectory for the host vehicle to travel based on the following target vehicle; and controlling the travel of the host vehicle based on the target trajectory.

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