Vehicle travel assistance method and vehicle travel assistance device

Abstract

This vehicle travel assistance method reduces the risk of collision with a moving object that exists in the vicinity of an edge of a road on which a vehicle is travelling. The method detects a moving object in a region in the vicinity of one road edge that is among left-right road edges of a road on which a vehicle is travelling and that is closer to the vehicle (S2); calculates the density of moving objects in the region in the vicinity of said one road edge (S3); and controls travel of the vehicle so as to further reduce the risk of collision with a moving object when the calculated density is high, as compared to a case where the calculated density is low (S4, S5).

Description

Vehicle driving support method and vehicle driving support device

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

[0002] The driving control device of Patent Document 1 listed below suppresses the vehicle speed to below a set vehicle speed when the vehicle is traveling in an area where the risk on the road is above a set value and when there is sparse traffic on the road including the lane in which the vehicle is traveling or when there is congestion on the road including the lane in which the vehicle is traveling.

[0003] Japanese Patent Application Laid-Open No. 2022-030241

[0004] However, the risk of collision with a moving object near the edge of the road on which the vehicle is traveling varies depending on the density of moving objects. An object of the present invention is to reduce the risk of collision with a moving object near the edge of the road on which the vehicle is traveling.

[0005] In one aspect of the vehicle driving assistance method of the present invention, moving objects are detected in an area near one of the left and right road edges of the road on which the vehicle is driving, the density of moving objects in the area near the one road edge is calculated, and the vehicle's driving is controlled so as to reduce the risk of collision with the moving object more when the calculated density is higher than when it is low.

[0006] According to the present invention, the risk of collision with a moving object near the edge of a road on which a vehicle is traveling can be reduced. The objects and advantages of the present invention are realized and attained by using the elements and combinations set forth in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not intended to limit the invention as claimed.

[0007] FIG. 1 is a schematic diagram of an example of a vehicle driving assistance device according to an embodiment; FIG. 2 is a block diagram of an example of the functional configuration of a controller; (a) and (b) are explanatory diagrams of an example of a method for calculating the density of pedestrians in an area near one road edge; (a) to (c) are schematic diagrams of an example of setting a lateral position target value when an oncoming vehicle is present on a two-way road having a center line; (a) and (b) are schematic diagrams of an example of setting a lateral position target value when no oncoming vehicle is present on a two-way road having a center line; (a) and (b) are schematic diagrams of an example of setting a lateral position target value on a one-way road; (a) and (b) are schematic diagrams of an example of setting a vehicle speed target value; and (a) is a flowchart of an example of a vehicle driving assistance method according to an embodiment.

[0008] (Configuration) FIG. 1 is a schematic diagram of an example of a vehicle driving assistance device according to an embodiment. The host vehicle 1 is equipped with a vehicle driving assistance device 10. The vehicle driving assistance device 10 executes driving assistance control to assist the host vehicle 1 in driving according to the driving environment around the host vehicle 1. In the driving assistance control, the vehicle driving assistance device 10 detects objects around the host vehicle 1, sets a target value for the lateral position (position in the road width direction) of the host vehicle 1 on the road on which the host vehicle 1 is traveling so as to avoid the surrounding objects, and controls the lateral position of the host vehicle 1 to the target lateral position value. Alternatively, the vehicle driving assistance device 10 sets a target vehicle speed value for the host vehicle 1 so as to reduce the risk of collision with surrounding objects, and controls the vehicle speed of the host vehicle 1 to the target vehicle speed value. In the following description, the lateral position (position in the road width direction) of the host vehicle 1 on the road on which the host vehicle 1 is traveling will be simply referred to as the "lateral position."

[0009] For example, the driving assistance control by the vehicle driving assistance device 10 may be autonomous driving control that causes the host vehicle 1 to autonomously drive to a set destination. Also, the driving assistance control by the vehicle driving assistance device 10 may be obstacle avoidance control that controls the steering and vehicle speed of the host vehicle 1 to avoid an obstacle ahead in the path of the host vehicle 1. In the following explanation, an example will be described in which the driving control by the vehicle driving assistance device 10 is autonomous driving control that causes the host vehicle 1 to autonomously drive to a set destination.

[0010] The vehicle driving assistance device 10 includes an object sensor 11, a vehicle sensor 12, a positioning device 13, a map database (map DB) 14, a navigation device 15, an actuator 16, and a controller 17. The object sensor 11 detects objects within a predetermined distance range from the host vehicle 1. The object sensor 11 detects the surrounding environment of the host vehicle 1, such as the relative position between the host vehicle 1 and an object present around the host vehicle 1, the distance between the host vehicle 1 and the object, and the direction in which the object is present. The object sensor 11 may include, for example, a camera that captures the surrounding environment of the host vehicle 1. The object sensor 11 may also include a ranging device such as a laser range finder, radar, LiDAR (Light Detection and Ranging), or sonar. The object sensor 11 outputs surrounding environment information, which is information on the detected surrounding environment of the host vehicle 1, to the controller 17.

[0011] The vehicle sensors 12 are mounted on the host vehicle 1, detect various pieces of information obtained from the host vehicle 1 (hereinafter sometimes referred to as "host vehicle information"), and output the information to the controller 17. The vehicle sensors 12 include, for example, a vehicle speed sensor that detects the vehicle speed of the host vehicle 1, a wheel speed sensor that detects the rotational speed of the tires of the host vehicle 1, a three-axis acceleration sensor that detects the acceleration and deceleration in three axial directions of the host vehicle 1, a steering angle sensor that detects the steering angle of the steering wheel, a turning angle sensor that detects the turning angle of the steered wheels, a gyro sensor that detects the angular velocity of the host vehicle 1, a yaw rate sensor that detects the yaw rate, an accelerator sensor that detects the accelerator opening of the host vehicle, and a brake sensor that detects the amount of brake operation by the driver.

[0012] The positioning device 13 is equipped with a Global Navigation System (GNSS) receiver and receives radio waves from multiple navigation satellites to measure the current position of the vehicle 1. The GNSS receiver may be, for example, a Global Positioning System (GPS) receiver. The positioning device 13 may be, for example, an inertial navigation system. The map database 14 stores road map data. The map database 14 may store map data for navigation (hereinafter sometimes referred to as "navigation map data") as the road map data. The navigation map data includes information on a road unit basis. The road unit information includes, for example, information on road nodes indicating reference points on road reference lines and information on road links indicating the section configurations of roads between the road nodes. The road node information includes position coordinates, the number of connected road links, and identification information of the connected road links.

[0013] The map database 14 may store high-precision map data as road map data. High-precision map data is map data suitable as map information for automated driving, and includes more detailed lane-by-lane information than road-by-road information. Lane-by-lane information includes, for example, lane node information indicating reference points on lane reference lines (e.g., the center line within a lane) and lane link information indicating the lane section configuration between lane nodes. Lane node information includes position coordinates of the lane node, the number of connected lane links, and identification information of the connected lane links. Lane link information includes position coordinates of the lane link, lane type, lane width, lane boundary line type, lane shape, lane marking shape, and lane reference line shape.

[0014] The navigation device 15 recognizes the current position of the vehicle using the positioning device 13 and obtains navigation map data for the current position from the map database 14. The navigation device 15 sets a target driving route to the destination input by the occupant and provides route guidance to the occupant along the target driving route. The navigation device 15 also outputs information about the set target driving route to the controller 17. During autonomous driving control, the controller 17 automatically drives the vehicle 1 so that it travels along the target driving route set by the navigation device 15.

[0015] The actuator 16 operates the steering device, accelerator opening, and brake device of the host vehicle 1 in response to control signals from the controller 17 to generate vehicle behavior of the host vehicle 1. The actuator 16 includes a steering actuator, an accelerator opening actuator, and a brake control actuator. The steering actuator controls the steering direction and steering amount of the steering device of the host vehicle 1. The accelerator opening actuator controls the accelerator opening of the host vehicle 1. The brake control actuator controls the braking operation of the brake device of the host vehicle.

[0016] The controller 17 is an electronic control unit that performs driving assistance control of the host vehicle 1. The controller 17 includes a processor 17a and peripheral components such as a storage device 17b. The processor 17a may be, for example, a CPU or an MPU. The storage device 17b may include a semiconductor storage device, a magnetic storage device, an optical storage device, etc. The storage device 17b may include memories such as a register, a cache memory, and a ROM and RAM used as a main storage device. The functions of the controller 17 described below are realized, for example, by the processor 17a executing a computer program stored in the storage device 17b. Note that the controller 17 may also be formed by dedicated hardware for executing the information processing described below. For example, the controller 17 may include a functional logic circuit configured in a general-purpose semiconductor integrated circuit. For example, the controller 17 may include a PLD such as an FPGA.

[0017] 2 is a block diagram of an example of the functional configuration of the controller 17. The controller 17 includes a pedestrian information acquisition unit 20, an other vehicle information acquisition unit 21, a road information acquisition unit 22, an autonomous driving control unit 23, a steering control unit 24, a drive control unit 25, and a braking control unit 26. The pedestrian information acquisition unit 20 acquires pedestrian information about pedestrians in an area near one of the left and right road edges of the road on which the host vehicle 1 is traveling, which is closer to the host vehicle 1, based on the surrounding environment information output from the object sensor 11. For example, the pedestrian information may include position information of the pedestrian.

[0018] 3(a) , reference symbol Rd indicates the road on which the host vehicle 1 is traveling, reference symbols EL and ER indicate the left and right road edges of the road Rd, respectively, reference symbol L1 indicates the driving lane on the road Rd in which the host vehicle 1 is traveling, reference symbol L2 indicates the oncoming lane of the driving lane L1, and reference symbol M indicates the center line of the roadway separating the driving lane L1 from the oncoming lane L2. In the following description, of the left and right road edges EL and ER of the road Rd, the road edge EL closest to the host vehicle 1 will be referred to as the "first road edge," and of the road edges EL and ER, the road edge ER closest to the host vehicle 1 will be referred to as the "second road edge." For example, if driving on the left side of the road is mandatory, the left road edge EL will be the "first road edge," and the right road edge ER will be the "second road edge." When driving on the right side is mandatory, the right road edge ER is the "first road edge" and the left road edge EL is the "second road edge."

[0019] In the following description, an example in which driving on the left side of the road is mandatory will be described, but the present invention can also be applied to cases in which driving on the right side of the road is mandatory. Furthermore, a pedestrian in this embodiment is an example of a "moving object" in the claims. However, this embodiment does not intend to limit the "moving object" of the present invention to a pedestrian. The "moving object" of the present invention can be applied to various road users present in an area near a fireplace on the road on which the vehicle 1 is traveling.

[0020] 2 , the other vehicle information acquisition unit 21 acquires other vehicle information about other vehicles present around the host vehicle 1 based on the surrounding environment information output from the object sensor 11. For example, the other vehicle information may include information about the presence or absence of other vehicles (such as oncoming vehicles) traveling on the road Rd. The road information acquisition unit 22 acquires road information about the road Rd on which the host vehicle 1 is traveling based on the current position of the host vehicle 1 measured by the positioning device 13, the road map data in the map database 14, and the surrounding environment information output from the object sensor 11.

[0021] The autonomous driving control unit 23 executes autonomous driving control to cause the host vehicle 1 to autonomously drive along a target driving route set by the navigation device 15. The autonomous driving control unit 23 includes a driving control unit 30, a collision risk mitigation support unit 31, and an arbitration unit 32. The driving control unit 30 calculates a target driving trajectory for the host vehicle 1 to drive based on the current position of the host vehicle 1, the target driving route set by the navigation device 15, road map data in the map database 14, surrounding environment information output from the object sensor 11, and host vehicle information output from the vehicle sensor 12. For example, the driving control unit 30 generates a route space map that represents the route around the host vehicle 1 and the presence or absence of objects, and a risk map that quantifies the risk of the driving environment, and generates a target driving trajectory and a target vehicle speed profile for the host vehicle 1 to drive based on the motion characteristics of the host vehicle 1, vehicle state information, the route space map, and the risk map.

[0022] The collision risk mitigation support unit 31 sets a target lateral position value for the host vehicle 1 so as to reduce the risk of collision with a pedestrian in the area near the first road edge EL, based on the pedestrian information acquired by the pedestrian information acquisition unit 20, the other vehicle information acquired by the other vehicle information acquisition unit 21, and the road information acquired by the road information acquisition unit 22. Additionally or alternatively, the collision risk mitigation support unit 31 may set a target vehicle speed value for the host vehicle 1 so as to reduce the risk of collision with a pedestrian in the area near the first road edge EL. Details of the collision risk mitigation support unit 31 will be described later.

[0023] The arbitration unit 32 determines an arbitrated lateral position target value by arbitrating the target driving trajectory generated by the driving control unit 30 and the lateral position target value set by the collision risk mitigation support unit 31. For example, the arbitration unit 32 may determine, as the arbitrated lateral position target value, the lateral position that has the lowest risk of collision with a pedestrian in an area near the first road edge EL (for example, a lateral position farther from the first road edge EL) from among the lateral positions of the target driving trajectory generated by the driving control unit 30 and the lateral position target values ​​set by the collision risk mitigation support unit 31.

[0024] The arbitration unit 32 arbitrates between the target vehicle speed profile generated by the driving control unit 30 and the vehicle speed target value set by the collision risk mitigation support unit 31, and determines the arbitrated vehicle speed target value. For example, the arbitration unit 32 may determine, as the arbitrated vehicle speed target value, the speed (e.g., the lower speed) that results in a smaller risk of collision with a pedestrian in the area near the first road edge EL, from among the vehicle speed of the target vehicle speed profile generated by the driving control unit 30 and the vehicle speed target value set by the collision risk mitigation support unit 31. The steering control unit 24 controls the steering actuator of the actuator 16 so that the lateral position of the host vehicle 1 approaches the arbitrated lateral position target value. For example, the steering actuator is controlled so that the lateral position of the host vehicle 1 becomes the arbitrated lateral position target value. The drive control unit 25 and the braking control unit 26 control the accelerator opening actuator and the brake control actuator of the actuator 16, respectively, so that the vehicle speed of the host vehicle 1 approaches the arbitrated vehicle speed target value. For example, the accelerator opening actuator and the brake control actuator are controlled so that the speed of the host vehicle 1 reaches the adjusted vehicle speed target value.

[0025] Next, the configuration and operation of the collision risk mitigation support unit 31 will be described. The collision risk mitigation support unit 31 includes a pedestrian density calculation unit 31a, a road type determination unit 31b, a target lateral position setting unit 31c, and a target vehicle speed setting unit 31d. The pedestrian density calculation unit 31a calculates the pedestrian density Dp in the area near the first road edge EL. FIGS. 3(a) and 3(b) are explanatory diagrams of an example of a method for calculating the pedestrian density in the area near the first road edge EL. In FIGS. 3(a) and 3(b), each of the multiple circular plots schematically represents a single pedestrian. The vertical direction of the road Rd (i.e., the direction in which the road Rd extends) is defined as the x-direction, and the horizontal direction of the road Rd (i.e., the road width direction of the road Rd) is defined as the y-direction. This also applies to FIGS. 4(a) to 4(c), 5, 6(a) and 6(b), 7, and 8(a).

[0026] For example, the pedestrian density calculation unit 31a may set a region Rn having a lateral width Ws along the road boundary of the first road edge EL as the region near the first road edge EL. In the following description, the region Rn will be referred to as the "neighborhood region Rn." For example, the lateral position of the neighborhood region Rn on the first road edge EL side may coincide with the lateral position of the road boundary of the first road edge EL, and the lateral position of the neighborhood region Rn on the second road edge ER side may be a distance Ws away from the road boundary of the first road edge EL toward the center of the road Rd. The distance Ws may be, for example, approximately 1.5 m. See FIG. 3(b). For example, the pedestrian density calculation unit 31a may divide the neighborhood region Rn into divided sections S each having a predetermined length Ls in the vertical direction. The predetermined length Ls may be, for example, approximately 3 m. The pedestrian density calculation unit 31a may calculate the pedestrian density Dp = (number of pedestrians) / (Ws × Ls) in each divided section S by dividing the number of pedestrians present in each divided section S by the area of ​​the divided section S, as the pedestrian density in the area near the first road end EL.

[0027] 2 , the road type determination unit 31b determines the type of road Rd based on the road information acquired by the road information acquisition unit 22. For example, the road type determination unit 31b may determine whether the type of road Rd is a two-way traffic road with a center line M, a two-way traffic road without a center line M, or a one-way road. The target lateral position setting unit 31c sets a target value for the lateral position of the host vehicle 1 on the road Rd based on the pedestrian density Dp calculated by the pedestrian density calculation unit 31a, the type of road Rd determined by the road type determination unit 31b, and other vehicle information acquired by the other vehicle information acquisition unit 21.

[0028] 4( a) to 4(c) are schematic diagrams illustrating an example of setting a lateral position target value when road Rd is a two-way road with a roadway centerline M and an oncoming vehicle 2 is present. When road Rd is a two-way road with a roadway centerline M and an oncoming vehicle 2 is present, the target lateral position setting unit 31c sets a driving restriction region RmR on the second road edge ER side of road Rd. The lateral position yR1 of the boundary of the driving restriction region RmR on the first road edge EL side may be, for example, the position of the roadway centerline M. Note that the lateral positions yR1, yR2, yL1, and yL2 in each drawing are illustratively expressed based on the road boundary of the first road edge EL, but the reference for these lateral positions is not limited to the road boundary of the first road edge EL. For example, the lateral positions may be expressed based on the center of road Rd or the road boundary of the second road edge ER.

[0029] Furthermore, when a pedestrian is detected in the vicinity region Rn of the first road edge EL, the target lateral position setting unit 31c sets the driving restriction region RmL on the first road edge EL side of the road Rd. For example, the far end Pmf of the driving restriction region RmL in the longitudinal direction (x direction) of the road Rd, which is far from the host vehicle 1, may be set to a point where the host vehicle 1 has passed around the pedestrian. Furthermore, the near end Pmn of the driving restriction region RmL, which is close to the host vehicle 1, may be set to a position where the host vehicle 1 can start decelerating from the current vehicle speed at a predetermined allowable deceleration (e.g., 0.3 G) and stop just before the pedestrian closest to the host vehicle 1.

[0030] For example, the target lateral position setting unit 31c may set the driving restriction region RmL when a pedestrian is detected in the divided section S of the vicinity region Rn of the first road edge EL. For example, the position of the far end Pmf of the driving restriction region RmL may be set to the far end Psf of the divided section S in the longitudinal direction of the road Rd, which is the farthest from the host vehicle 1. Furthermore, the position of the near end Pmn of the driving restriction region RmL may be set to a position at which the host vehicle 1 can stop at the near end Psn of the divided section S by starting to decelerate from the current vehicle speed at a predetermined allowable deceleration. Furthermore, the target lateral position setting unit 31c sets the lateral position yL1 of the boundary of the driving restriction region RmL on the side of the second road edge ER according to the pedestrian density Dp calculated by the pedestrian density calculation unit 31a.

[0031] For example, the target lateral position setting unit 31c may set the lateral position yL1 of the boundary on the second road edge ER side to be farther away from the first road edge EL (in other words, closer to the second road edge ER) as the pedestrian density Dp increases. For example, if the pedestrian density Dp in the divided section S in Fig. 4(b) is higher than the pedestrian density Dp in the divided section S in Fig. 4(a), the lateral position yL2 of the boundary on the second road edge ER side of the driving restriction region RmL in Fig. 4(b) may be set to be farther away from the first road edge EL than the lateral position yL1 in Fig. 4(a).

[0032] The target lateral position setting unit 31c sets the target lateral position of the host vehicle 1 so as to restrict or prohibit the host vehicle 1 from traveling (entering) within the travel restriction areas RmL and RmR. For example, the target lateral position of the host vehicle 1 is set so as to travel within the area between the left and right road boundaries of the road Rd, except for the travel restriction areas RmL and RmR. This reduces the risk of a collision with a pedestrian in the vicinity area Rn of the first road edge EL. See FIG. 4(c). If a pedestrian is detected in multiple different divided sections S1 and S2 of the vicinity area Rn of the first road edge EL, the target lateral position setting unit 31c may set the travel restriction areas RmL1 and RmL2 on the first road edge EL side for these divided sections S1 and S2, respectively, in the same manner as described above. The target lateral position setting unit 31c sets the target lateral position of the host vehicle 1 so as to restrict or prohibit the host vehicle 1 from traveling (entering) within the travel restriction areas RmL1, RmL2, and RmR. For example, the target lateral position value of the vehicle 1 is set so that the vehicle 1 travels within the range between the left and right road boundaries of the road Rd, excluding the travel restriction areas RmL1, RmL2, and RmR.

[0033] FIG. 5 is a schematic diagram illustrating an example of setting the lateral position target value when the road Rd is a two-way road with a roadway centerline M and no oncoming vehicle 2 is present. When no oncoming vehicle 2 is present, the method of setting the travel restriction region RmL on the first road edge EL side is the same as when an oncoming vehicle 2 is present. Meanwhile, the lateral position yR2 of the boundary of the travel restriction region RmR on the second road edge ER side on the first road edge EL side may be set to be farther from the first road edge EL than the lateral position yR1 when an oncoming vehicle 2 is present (see, for example, FIG. 4A ). For example, the lateral position yR2 may be set to a position farther from the first road edge EL than the roadway centerline M (in other words, a position closer to the second road edge ER). This allows the lateral position target value to be set closer to the second road edge ER (the road edge farthest from the host vehicle 1 out of the left and right road edges EL and ER) when no oncoming vehicle 2 is present than when an oncoming vehicle 2 is present.

[0034] 6( a) and 6(b) are schematic diagrams illustrating an example of setting the lateral position target value when the road Rd is a two-way road without a roadway centerline M. The method of setting the driving restriction region RmL on the first road edge EL side may be the same as when it is a two-way road with a roadway centerline M. On the other hand, the lateral position yR1 of the boundary on the first road edge EL side of the driving restriction region RmR on the second road edge ER side may be set, for example, to a position in the center of the road Rd (e.g., a position separated from the road boundary of the first road edge EL or the second road edge ER by a distance half the road width WR of the road Rd), or may be set to a position separated from the road boundary of the second road edge ER by a predetermined length L. The predetermined length L may be, for example, the width of a typical lane, or the width of a typical vehicle plus a predetermined margin.

[0035] If the road Rd is a two-way road without a roadway centerline M, the lateral position yR1 of the boundary of the driving restriction region RmR on the first road edge EL side may be set regardless of whether or not an oncoming vehicle 2 is present. That is, the method for setting the lateral position yR1 when an oncoming vehicle 2 is present may be the same as the method for setting the lateral position yR1 when an oncoming vehicle 2 is not present. FIG. 7 is a schematic diagram of an example of setting the lateral position target value when the road Rd is a one-way road. The method for setting the driving restriction region RmL on the first road edge EL side may be the same as when the road Rd is a two-way road with a roadway centerline M. If the road Rd is a one-way road, the target lateral position setting unit 31c does not need to set the driving restriction region RmR on the second road edge ER side.

[0036] See Fig. 2. The target vehicle speed setting unit 31d sets a target vehicle speed for passing around a pedestrian based on the pedestrian density Dp calculated by the pedestrian density calculation unit 31a. For example, the target vehicle speed setting unit 31d sets a lower target vehicle speed for passing around a pedestrian when the density Dp is high than when it is low. Figs. 8(a) and 8(b) are schematic diagrams of setting examples of target vehicle speeds. When a pedestrian is detected in the vicinity region Rn of the first road edge EL, the target vehicle speed setting unit 31d sets a vehicle speed limit section Sv.

[0037] For example, the position of the far end Pvf of the speed limit section Sv in the longitudinal direction of the road Rd, which is far from the host vehicle 1, may be set to a point where the pedestrian has passed. Furthermore, the near end Pvn of the speed limit section Sv, which is close to the host vehicle 1, may be set to a position in front of the pedestrian. For example, the target vehicle speed setting unit 31d may set the speed limit section Sv when a pedestrian is detected in the divided section S of the vicinity region Rn of the first road edge EL. For example, the position of the far end Pvf of the speed limit section Sv may be set to the position of the far end Psf of the divided section S. Furthermore, the position of the near end Pvn of the speed limit section Sv may be set to the position of the near end Psn of the divided section S, or may be set to a position closer to the near end Psn.

[0038] The target vehicle speed setting unit 31d sets a target vehicle speed value for the host vehicle 1 in the vehicle speed limit section Sv. For example, the target vehicle speed setting unit 31d may set a lower target vehicle speed value in the vehicle speed limit section Sv when the pedestrian density Dp calculated by the pedestrian density calculation unit 31a is high rather than when it is low. For example, as shown in FIG. 8(b), the target vehicle speed setting unit 31d may set the target vehicle speed value (Vc × K) in the vehicle speed limit section Sv by multiplying the current vehicle speed Vc by a gain K smaller than 1. The target vehicle speed setting unit 31d may set a smaller gain K when the density Dp is high rather than when it is low. The target vehicle speed setting unit 31d sets the target vehicle speed value so that the host vehicle 1 decelerates from the current vehicle speed Vc to the vehicle speed (Vc × K) while traveling from the current traveling position to the near end Pvn of the vehicle speed limit section Sv. Furthermore, the target vehicle speed setting unit 31d sets the target vehicle speed value so that the vehicle accelerates from the vehicle speed Vc×K to the original vehicle speed Vc after passing the far end Pvf of the vehicle speed limit section Sv.

[0039] (Operation) Figure 9 is a flowchart of an example of a vehicle driving assistance method according to an embodiment. In step S1, the controller 17 acquires surrounding environment information output from the object sensor 11 and host vehicle information output from the vehicle sensor 12. In step S2, the pedestrian density calculation unit 31a of the collision risk mitigation assistance unit 31 determines whether or not a pedestrian is present in the area near the first road edge EL. If no pedestrian is present (step S2: N), the processing ends. In this case, the steering control unit 24 controls the steering actuator of the actuator 16 based on the target driving trajectory generated by the driving control unit 30. The drive control unit 25 and the braking control unit 26 control the accelerator opening actuator and the brake control actuator, respectively, based on the target vehicle speed profile generated by the driving control unit 30.

[0040] If a pedestrian is present (step S2: Y), the process proceeds to step S3. In step S3, the pedestrian density calculation unit 31a calculates the density Dp of pedestrians in the area near the first road edge EL. In step S4, the target lateral position setting unit 31c sets a target value for the lateral position of the host vehicle 1 on the road Rd in accordance with the density Dp. The target vehicle speed setting unit 31d sets a target vehicle speed value for passing around the pedestrian in accordance with the density Dp. In step S5, the steering control unit 24 controls the steering actuator in accordance with the target lateral position value set by the target lateral position setting unit 31c. The drive control unit 25 and the braking control unit 26 control the accelerator opening actuator and the brake control actuator, respectively, in accordance with the target vehicle speed value set by the target vehicle speed setting unit 31d. The process then ends.

[0041] (Effects of the embodiment) (1) The object sensor 11 detects moving objects in an area near one of the left and right road edges of the road on which the vehicle 1 is traveling, which is closer to the vehicle 1. The controller 17 calculates the density of moving objects in the area near one road edge, and controls the traveling of the vehicle 1 so as to further reduce the risk of collision with the moving object when the calculated density is high rather than when it is low. This reduces the risk of collision with a moving object that exists near the road edge of the road on which the vehicle 1 is traveling. As a result, it is possible to reduce the discomfort felt by occupants when, for example, a moving object suddenly appears.

[0042] (2) The controller 17 may set a target value for the lateral position of the vehicle 1 on the road on which the vehicle 1 is traveling according to the calculated density, and control the lateral position of the vehicle 1 so that the target value approaches the target value. For example, the controller 17 may set the target value for the lateral position to a lateral position farther away from one road edge when the calculated density is high than when the calculated density is low. By changing the lateral position according to the density of moving objects in this way, an appropriate distance from the moving objects can be ensured.

[0043] (3) The controller 17 may set the target value of the lateral position depending on whether the road on which the host vehicle 1 is traveling is a one-way road or a two-way road. For example, if the road on which the host vehicle 1 is traveling is a two-way road, the controller 17 may set the target value of the lateral position depending on the calculated density and the presence or absence of an oncoming vehicle. This makes it possible to ensure an appropriate distance from the moving object depending on the type of road on which the host vehicle 1 is traveling.

[0044] (4) The controller 17 may set a target vehicle speed for passing around the moving object according to the calculated density, and control the vehicle speed of the host vehicle 1 so that the vehicle speed approaches the target vehicle speed. For example, the controller 17 may set the vehicle speed lower than the target vehicle speed when the calculated density is high rather than when it is low. This makes it easier to appropriately activate the collision avoidance function in response to a moving object suddenly appearing.

[0045] All examples and conditional terms described herein are intended for educational purposes to aid the reader in understanding the present invention and the concepts provided by the inventor for the advancement of technology, and should be construed without limitation to the specifically described examples and conditions above, and the configuration of examples herein for illustrating the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions, and alterations can be made thereto without departing from the spirit and scope of the present invention.

[0046] 1...Own vehicle, 10...Vehicle driving assistance device, 11...Object sensor, 12...Vehicle sensor, 13...Positioning device, 14...Map database, 15...Navigation device, 16...Actuator, 17...Controller, 17a...Processor, 17b...Storage device, 20...Pedestrian information acquisition unit, 21...Other vehicle information acquisition unit, 22...Road information acquisition unit, 23...Autonomous driving control unit, 24...Steering control unit, 25...Drive control unit, 26...Braking control unit, 30...Driving control unit, 31...Collision risk mitigation support unit, 31a...Pedestrian density calculation unit, 31b...Road type determination unit, 31c...Target lateral position setting unit, 31d...Target vehicle speed setting unit, 32...Arbitration unit

Claims

1. A vehicle driving assistance method comprising: detecting moving objects in an area near one of the left and right road edges of a road on which a vehicle is driving, which is closer to the vehicle; calculating the density of the moving objects in the area near the one road edge; and controlling the driving of the vehicle so as to reduce the risk of collision with the moving object more when the calculated density is higher than when it is lower.

2. The vehicle driving assistance method according to claim 1, further comprising: setting a target value for the lateral position of the vehicle on the road on which the vehicle is traveling in accordance with the calculated density; and controlling the lateral position of the vehicle so as to approach the target value for the lateral position.

3. The vehicle driving assistance method according to claim 2, wherein the target value of the lateral position is set to a lateral position farther from the one road edge when the calculated density is high than when the calculated density is low.

4. A vehicle driving support method according to claim 2 or 3, characterized in that the target value of the lateral position is set depending on whether the road on which the vehicle is traveling is a one-way road or a two-way road.

5. The vehicle driving assistance method according to claim 4, characterized in that when the road on which the vehicle is traveling is a road with two-way traffic, the target value of the lateral position is set according to the calculated density and the presence or absence of an oncoming vehicle.

6. The vehicle driving assistance method according to claim 5, characterized in that the target value of the lateral position is set so that when there is no oncoming vehicle, the target value of the lateral position is closer to the other of the left and right road edges that is farther from the vehicle than when there is an oncoming vehicle.

7. A vehicle driving assistance method according to any one of claims 1 to 6, characterized in that a target value of the vehicle speed passing around the moving object is set in accordance with the calculated density, and the vehicle speed of the vehicle is controlled so as to approach the target value of the vehicle speed.

8. The vehicle driving support method according to claim 7, wherein the target vehicle speed is set lower when the calculated density is high than when it is low.

9. A vehicle driving assistance device comprising: a sensor that detects moving objects in an area near one of the left and right road edges of a road on which a vehicle is driving, which is closer to the vehicle; and a controller that calculates the density of the moving objects in the area near the one road edge, and controls the driving of the vehicle so that the risk of collision with the moving object is reduced more when the calculated density is high than when it is low.

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