Driving assistance device, driving assistance method, and recording medium

Abstract

The present invention provides a driving assistance device that assists driving of a vehicle capable of performing following control, the driving assistance device executing: an acquisition process for acquiring vehicle characteristic information pertaining to a characteristic of other vehicles traveling around the vehicle; and a preceding vehicle proposing process for assuming any one or more first other vehicles from among the other vehicles as preceding vehicles, identifying a second other vehicle that is a following vehicle of the vehicle when the first other vehicles are assumed to be the preceding vehicles, and proposing the preceding vehicle on the basis of preference information regarding surrounding vehicles of a driver of the vehicle and the vehicle characteristic information pertaining to the first other vehicles and the second other vehicle.

Description

[Technical Field]

[0001] The present disclosure relates to a driving assistance device, a driving assistance method, and a recording medium. [Background technology]

[0002] In recent years, vehicles equipped with adaptive cruise control (ACC) functions that allow a vehicle to follow a preceding vehicle have been put into practical use. Adaptive cruise control is a control that allows a vehicle to automatically follow a preceding vehicle while maintaining a target inter-vehicle distance that is set according to the vehicle's speed, etc.

[0003] Regarding such a tracking control function, for example, Patent Document 1 discloses a leading vehicle selection assistance device that acquires host vehicle information including information that can identify the vehicle's current position and planned driving route, acquires other vehicle information including information that can identify the current position, speed, and planned driving route of other vehicles that are candidates for preceding vehicles, calculates a merging cost that represents the amount of burden on the driver until the host vehicle merges with the other vehicles based on the host vehicle information and the other vehicle information, and narrows down the candidates for preceding vehicles.

[0004] Furthermore, Patent Document 2 discloses a tracking control device that sets an inter-vehicle distance according to the characteristics of the driver, calculates an inter-vehicle distance according to the driving conditions of surrounding vehicles, and calculates a target inter-vehicle distance between a vehicle and a preceding vehicle based on the inter-vehicle distance according to the characteristics of the driver and the inter-vehicle distance according to the driving conditions of surrounding vehicles, thereby controlling the speed of the vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 170635 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-189055 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the technologies disclosed in Patent Documents 1 and 2 select a leading vehicle and set the distance from the leading vehicle based on predetermined conditions, and neither technology takes into consideration the following vehicle when the vehicle is made to follow the leading vehicle. Therefore, there is a risk that a situation may arise in which the following vehicle may cause the following control function to be halted even after the leading vehicle has been determined and following has begun, for example, when the safety of the following vehicle is low due to a short distance between the vehicles, or when the vehicle does not want to be followed by the same following vehicle for a long period of time.

[0007] The present disclosure has been made in consideration of the above-mentioned problems, and an object of the present disclosure is to provide a driving assistance device, a driving assistance method, and a recording medium that are capable of suggesting a preceding vehicle when performing following control, taking into consideration not only the preceding vehicle but also vehicles that could become following vehicles. [Means for solving the problem]

[0008] In order to solve the above problem, according to one aspect of the present disclosure, there is provided a driving assistance device that assists driving of a vehicle capable of performing following control to cause the vehicle to follow a preceding vehicle, the driving assistance device comprising one or more processors and one or more memories communicatively connected to the one or more processors, wherein the one or more processors perform an acquisition process to acquire vehicle characteristic information regarding the characteristics of other vehicles traveling around the vehicle, and a preceding vehicle suggestion process to assume one or more first other vehicles among the other vehicles as the preceding vehicle, identify a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and suggest the preceding vehicle based on preference information regarding the surrounding vehicles of the driver of the vehicle and the vehicle characteristic information of the first other vehicle and the second other vehicle.

[0009] In addition, according to another aspect of the present disclosure to solve the above problem, there is provided a driving assistance method for assisting the driving of a vehicle capable of performing following control to cause the vehicle to follow a preceding vehicle, wherein the one or more processors perform processing including acquiring vehicle characteristic information regarding the characteristics of other vehicles traveling around the vehicle, assuming any one or more first other vehicles among the other vehicles as the preceding vehicle, identifying a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and suggesting the preceding vehicle based on preference information of the driver of the vehicle regarding surrounding vehicles and the vehicle characteristic information of the first other vehicle and the second other vehicle.

[0010] In addition, according to another aspect of the present disclosure, in order to solve the above problem, a non-transitory tangible recording medium is provided that causes one or more processors to execute the following computer programs: an acquisition process for acquiring vehicle characteristic information regarding the characteristics of other vehicles traveling around the vehicle; and a preceding vehicle suggestion process for assuming any one or more first other vehicles among the other vehicles as preceding vehicles, and identifying a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and suggesting the preceding vehicle when performing following control based on preference information regarding surrounding vehicles of the driver of the vehicle and the vehicle characteristic information of the first other vehicle and the second other vehicle. [Effects of the Invention]

[0011] As described above, according to the present disclosure, when performing tracking control, it is possible to suggest a leading vehicle by taking into consideration not only the leading vehicle but also vehicles that could potentially become following vehicles. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a schematic diagram illustrating a configuration example of a vehicle equipped with a driving assistance device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing a configuration example of a driving assistance device according to the embodiment; [Figure 3]4 is a flowchart showing a main routine of a control process performed by the driving assistance device according to the embodiment. [Figure 4] 4 is a flowchart of a host vehicle-based preceding vehicle proposing process performed by the driving assistance device according to the first embodiment. [Figure 5] 3 is an explanatory diagram showing an example of setting a preceding vehicle by the driving assistance device according to the embodiment; FIG. [Figure 6] FIG. 10 is an explanatory diagram showing another example of setting a preceding vehicle by the driving assistance device according to the embodiment. [Figure 7] FIG. 10 is an explanatory diagram showing an example in which a preceding vehicle is set in consideration of only the preceding vehicle matching degree. [Figure 8] 10 is an explanatory diagram showing an example in which a preceding vehicle is set by the driving assistance device according to the embodiment, taking into account a preceding vehicle match degree and a following vehicle match degree. FIG. [Figure 9] 4 is an explanatory diagram showing an example of setting a target inter-vehicle distance according to a preceding vehicle matching degree by the driving assistance device according to the embodiment; FIG. [Figure 10] 10 is an explanatory diagram showing an example in which the driving assistance device according to the embodiment sets the target inter-vehicle distance to a value smaller than the reference inter-vehicle distance when the preceding vehicle coincidence degree of the preceding vehicle is "high." FIG. [Figure 11] 10 is an explanatory diagram showing an example in which the driving assistance device according to the embodiment sets the target inter-vehicle distance to a value greater than the reference inter-vehicle distance when the preceding vehicle coincidence degree of the preceding vehicle is "low." FIG. [Figure 12] FIG. 10 is an explanatory diagram showing a setting example in which the driving assistance device according to the embodiment adjusts the target inter-vehicle distance according to the visibility (vehicle size) of the driver of the vehicle; [Figure 13] 4 is an explanatory diagram showing an example in which a target inter-vehicle distance is set based on a preceding vehicle match degree and a following vehicle match degree by the driving assistance device according to the embodiment; FIG. [Figure 14] 10A and 10B are diagrams shown to explain an example of a situation in which a preceding vehicle is re-suggested by the driving assistance device according to the embodiment; [Figure 15] 10 is an explanatory diagram showing an area in which a preceding vehicle is re-proposed by the driving assistance device according to the embodiment based on the duration of following or the duration of being followed. FIG. [Figure 16] 10 is a flowchart illustrating an example of a process of determining whether to re-propose a preceding vehicle by the driving assistance device according to the embodiment. [Figure 17] 10 is a flowchart of a process for suggesting a leading vehicle in consideration of the comfort of a following vehicle, performed by a driving assistance device according to a second embodiment. [Figure 18] 10 is an explanatory diagram showing an example in which a preceding vehicle is set based on a preceding vehicle match degree and a following vehicle reference match degree by the driving assistance device according to the embodiment; FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, preferred embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In this specification and drawings, components having substantially the same functional configurations are designated by the same reference numerals, and redundant description will be omitted.

[0014] In this specification, a vehicle that executes tracking control and follows a preceding vehicle is referred to as a "subject vehicle." Also, a vehicle that the subject vehicle follows when executing tracking control is referred to as a "preceding vehicle." Also, a vehicle that travels behind the subject vehicle when executing tracking control is referred to as a "following vehicle."

[0015] <1. First embodiment> (1-1. Overall configuration of the vehicle) First, an example of the overall configuration of a vehicle equipped with a driving assistance device according to an embodiment of the present disclosure will be described.

[0016] FIG. 1 is a schematic diagram showing an example of the configuration of a vehicle 1. As shown in FIG. The vehicle 1 is configured as a two-wheel drive four-wheel vehicle in which a driving torque output from a driving force source 9 that generates driving torque is transmitted to the left front wheel and the right front wheel. The driving force source 9 may be an internal combustion engine such as a gasoline engine or a diesel engine, a driving motor, or may be equipped with both an internal combustion engine and a driving motor.

[0017] Vehicle 1 may be a four-wheel drive vehicle that transmits drive torque to the front and rear wheels. Vehicle 1 may also be an electric vehicle equipped with two drive motors, for example, a front-wheel drive motor and a rear-wheel drive motor, or an electric vehicle equipped with drive motors corresponding to the respective wheels. If vehicle 1 is an electric vehicle or hybrid electric vehicle, vehicle 1 is equipped with a secondary battery that stores power supplied to the drive motors, and a motor or fuel cell or other generator that generates power to charge the battery.

[0018] The vehicle 1 is equipped with a driving force source 9, an electric steering device 15, and brake devices 17LF, 17RF, 17LR, and 17RR (hereinafter collectively referred to as "brake devices 17" unless a distinction is required) as devices used to control the operation of the vehicle 1. The driving force source 9 outputs driving torque that is transmitted to the front wheel drive shaft 5F via a transmission and a differential mechanism 7 (not shown). The operation of the driving force source 9 and the transmission is controlled by a vehicle control unit 41 that includes one or more electronic control units (ECUs: Electronic Control Units).

[0019] The front-wheel drive shaft 5F is provided with an electric steering device 15. The electric steering device 15 includes an electric motor and a gear mechanism (not shown), and is controlled by a vehicle control unit 41 to adjust the steering angle of the front wheels. During manual driving, the vehicle control unit 41 controls the electric steering device 15 based on the steering angle of the steering wheel 13 by the driver. During automatic driving, the vehicle control unit 41 controls the electric steering device 15 based on the set steering angle or steering angular velocity.

[0020] Brake devices 17LF, 17RF, 17LR, and 17RR apply braking force to the respective wheels. Brake devices 17 are configured as, for example, hydraulic brake devices, and vehicle control unit 41 adjusts the hydraulic pressure supplied to each brake device 17 by controlling the drive of hydraulic unit 16. If vehicle 1 is an electric vehicle or a hybrid electric vehicle, brake devices 17 are used in combination with regenerative braking using a drive motor.

[0021] The vehicle control unit 41 includes one or more electronic control devices that control the driving of the driving force source 9, the electric steering device 15, and the hydraulic unit 16. If the vehicle 1 is equipped with a transmission that changes the speed of the output from the driving force source 9 and transmits it to the wheels 3, the vehicle control unit 41 has a function to control the driving of the transmission. The vehicle control unit 41 is configured to be able to acquire information transmitted from the driving assistance device 50, and is configured to be able to execute automatic driving control of the vehicle 1.

[0022] The vehicle 1 also includes front imaging cameras 31LF and 31RF, a rear imaging camera 31R, a vehicle state sensor 33, a GNSS (Global Navigation Satellite System) sensor 35, an inter-vehicle communication unit 37, and a notification device 43.

[0023] The front photographing cameras 31LF, 31RF and the rear photographing camera 31R constitute a surrounding environment sensor for acquiring information about the surrounding environment of the vehicle 1. The front photographing cameras 31LF, 31RF capture images in front of the vehicle 1 and generate image data. The rear photographing camera 31R captures images behind the vehicle 1 and generates image data. The front photographing cameras 31LF, 31RF and the rear photographing camera 31R are equipped with imaging elements such as CCDs (Charged Coupled Devices) or CMOS (Complementary Metal Oxide Semiconductors), and transmit the generated image data to the driving assistance device 50. In the vehicle 1 shown in FIG. 1, the front photographing cameras 31LF, 31RF are configured as stereo cameras including a pair of left and right cameras, but the front photographing cameras may also be monocular cameras.

[0024] The surrounding environment sensor may include, in addition to the front-view cameras 31LF and 31RF, a camera mounted on a side mirror for capturing images of the left rear or right rear. Additionally, the surrounding environment sensor may include one or more of a LiDAR (Light Detection and Ranging) sensor, a radar sensor such as a millimeter-wave radar, and an ultrasonic sensor.

[0025] The vehicle state sensor 33 is composed of at least one sensor that detects the operating state and behavior of the vehicle 1. The vehicle state sensor 33 includes, for example, at least one of a steering angle sensor, an accelerator position sensor, a brake stroke sensor, a brake pressure sensor, or an engine rotation speed sensor. The vehicle state sensor 33 also includes, for example, at least one of a vehicle speed sensor, an acceleration sensor, or an angular velocity sensor. The vehicle state sensor 33 transmits a sensor signal indicating the detected information to the driving assistance device 50.

[0026] The GNSS sensor 35 receives satellite signals from positioning satellites such as GPS (Global Positioning System) satellites. The GNSS sensor 35 transmits position information of the vehicle 1 contained in the received satellite signals to the driving assistance device 50. Note that the GNSS sensor 35 may be provided with an antenna, in addition to the GPS sensor, that receives satellite signals from other satellite systems that identify the position of the vehicle 1.

[0027] The vehicle-to-vehicle communication unit 37 is an interface for communicating with other vehicles that are present within a predetermined distance from the vehicle 1. The driving assistance device 50 transmits and receives information to and from other vehicles via the vehicle-to-vehicle communication unit 37.

[0028] The notification device 43 is driven by the driving assistance device 50 and notifies the driver of various information by means of image display, audio output, etc. The notification device 43 includes, for example, a display device provided in the instrument panel and a speaker provided in the vehicle 1. The display device may be a display device of a navigation system. The notification device 43 may also include a HUD (head-up display) that displays information on the front window superimposed on the scenery around the vehicle 1.

[0029] (1-2. Driving assistance devices) Next, the driving assistance device 50 according to this embodiment will be described in detail.

[0030] (1-2-1. Configuration example) The driving assistance device 50 functions as a device that assists in driving a vehicle by having one or more processors, such as CPUs (Central Processing Units), execute a computer program. The computer program is a computer program that causes the processor to execute the operations, described below, that should be performed by the driving assistance device 50. The computer program executed by the processor may be recorded on a recording medium that functions as a storage unit (memory) 53 provided in the driving assistance device 50, or may be recorded on a recording medium built into the driving assistance device 50 or any recording medium that can be externally attached to the driving assistance device 50.

[0031] Recording media for recording computer programs may include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical recording media such as CD-ROMs, DVDs, and Blu-ray (registered trademark), magneto-optical media such as floptical disks, memory elements such as RAMs and ROMs, flash memories such as USB memories and SSDs, and other media capable of storing programs.

[0032] FIG. 2 is a block diagram showing an example of the configuration of the driving assistance device 50 according to this embodiment. The driving assistance device 50 is connected to an ambient environment sensor 31, a vehicle state sensor 33, a GNSS sensor 35, and an inter-vehicle communication unit 37 via a dedicated line or communication means such as a CAN (Controller Area Network) or a LIN (Local Inter Net). Also connected to the driving assistance device 50 are a vehicle control unit 41 and a notification device 43. Note that the driving assistance device 50 is not limited to an electronic control device mounted on the vehicle 1, and may be a terminal device such as a smartphone or a wearable device.

[0033] The driving assistance device 50 includes a processing unit 51, a memory unit 53, a map data memory unit 55, and a vehicle characteristic information memory unit 57. The processing unit 51 is configured with one or more processors such as a CPU and various peripheral components. Part or all of the processing unit 51 may be configured with updatable firmware or the like, or may be a program module or the like executed by commands from the CPU or the like.

[0034] (Storage part) The storage unit 53 is configured with one or more storage elements such as RAM or ROM connected to the processing unit 51 so as to be able to communicate with it. However, there is no particular limitation on the type or number of storage units 53. The storage unit 53 stores information such as computer programs executed by the processing unit 51, various parameters used in arithmetic processing, detection data, and arithmetic results.

[0035] (Map data storage unit) The map data storage unit 55 is configured by a storage element such as RAM or ROM communicably connected to the processing unit 51, or a storage medium such as an HDD, CD, DVD, SSD, USB flash, or storage device. The map data stored in the map data storage unit 55 is configured to be able to identify the position of the vehicle 1 based on position information detected by the GNSS sensor 35. For example, the map data is associated with latitude and longitude information, and the processing unit 51 can identify the position of the vehicle 1 on the map data based on the latitude and longitude information of the vehicle 1 detected by the GNSS sensor 35.

[0036] (Vehicle characteristic information storage unit) The vehicle characteristic information storage unit 57 is configured by a storage element such as RAM or ROM communicably connected to the processing unit 51, or a storage medium such as an HDD, CD, DVD, SSD, USB flash, or storage device. The vehicle characteristic information storage unit 57 stores vehicle characteristic information relating to the characteristics of the vehicle along with identification information of the driver of the vehicle 1. The vehicle characteristic information includes at least one of information on safety, comfort, environmental friendliness, or driving characteristics when the vehicle 1 is a preceding vehicle of the vehicle that executes tracking control. The vehicle characteristic information also includes at least one of information on safety, comfort, and driving characteristics when the vehicle 1 is a following vehicle of the vehicle that executes tracking control.

[0037] The safety information when a vehicle is a leading vehicle is information that evaluates whether the vehicle can safely use the tracking control function when the vehicle is the leading vehicle. The safety information when a vehicle is a leading vehicle includes, for example, information on compliance with traffic rules, the installation status of the vehicle's safety equipment or safety functions, and vehicle size. Examples of compliance with traffic rules include whether the vehicle returns from the overtaking lane to the normal lane after overtaking another vehicle, whether the headlights are turned on at night, whether the speed limit is observed, and whether traffic signal signs are observed. Examples of the installation status of the vehicle's safety equipment or safety functions include whether the vehicle is equipped with an emergency braking function, whether the vehicle is equipped with a sensor that senses the rear, and whether the vehicle is equipped with a system that acquires driving information from an external server. Examples of vehicle size information include whether the vehicle is large enough to significantly obstruct visibility. Each piece of information may be presented as a value evaluated on a multiple-level scale (e.g., five levels) or as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0038] The information on comfort when a vehicle is a leading vehicle is information that evaluates whether the host vehicle can comfortably use the tracking control function with the vehicle as the leading vehicle. The information on comfort when a vehicle is a leading vehicle includes, for example, information on whether the exhaust gas is clean, whether the running noise is low, whether the model or function of the vehicle is similar to that of the host vehicle, and whether the destination is close to the destination of the host vehicle. The cleanliness of the exhaust gas is a factor that affects the dirtiness of the host vehicle and the odor inside the vehicle, and the cleanliness increases in the order of engine vehicles, hybrid electric vehicles, pure electric vehicles, and fuel cell vehicles. The running noise is a factor that affects the noise heard inside the vehicle. The model or function of the vehicle is a factor that affects whether the host vehicle can continue to follow a vehicle comfortably. The destination is a factor that affects the amount of time that tracking control can be continued without changing the leading vehicle. Each piece of information may be shown as a value evaluated on multiple levels (e.g., five levels) or as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0039] The environmental friendliness information when a vehicle is a preceding vehicle is information that evaluates whether the host vehicle can use the tracking control function with consideration for the environment when the vehicle is a preceding vehicle. The environmental friendliness information when a vehicle is a preceding vehicle includes, for example, vehicle size information. Vehicle size information is a factor that affects whether the preceding vehicle can act as a windbreak for the host vehicle and reduce fuel consumption or power consumption. Each piece of information may be shown as a value evaluated on multiple levels (for example, five levels) or as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0040] The information on driving characteristics when a vehicle is a leading vehicle is information for evaluating whether the driving characteristics of the leading vehicle are similar to the driving characteristics of the vehicle itself. The information on driving characteristics when a vehicle is a leading vehicle includes, for example, information on the following distance when manually driving, the average vehicle speed relative to the speed limit or legal speed, the rate of deceleration when entering a curve or intersection, the speed when passing through a curve, the acceleration / deceleration rate when performing acceleration / deceleration operations, or the steering angular velocity when operating the steering wheel. Each piece of information may be shown as a value evaluated on a multiple-level scale (e.g., five levels) or may be shown as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0041] Furthermore, the safety information when a vehicle is a following vehicle of the own vehicle is information that evaluates whether the own vehicle can safely use the tracking control function when being followed by the vehicle. The safety information when a vehicle is a following vehicle of the own vehicle includes, for example, information on compliance with traffic rules, the vehicle's safety equipment or safety functions, vehicle size, and vehicle design. Examples of compliance with traffic rules include whether the vehicle returns from the passing lane to the normal lane after overtaking another vehicle, whether the headlights are turned on at night, and whether an appropriate following distance is maintained. Examples of the vehicle's safety equipment or safety functions include whether the vehicle is equipped with an emergency brake function or a system that acquires driving information from an external server. Examples of vehicle size information include whether the vehicle is large, significantly obstructing rear visibility, or whether the vehicle is large enough to cause significant damage in the event of a rear-end collision. Examples of vehicle design information include whether the headlights are positioned high enough to cause glare when turned on. Each piece of information may be shown as a value evaluated on multiple levels (e.g., five levels) or as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0042] The information on comfort when a vehicle is a following vehicle of the own vehicle is information that evaluates whether the own vehicle can comfortably use the tracking control function when being followed by the vehicle. The information on comfort when a vehicle is a following vehicle of the own vehicle includes, for example, information on whether the running noise is quiet. The running noise is a factor that affects the noise heard inside the vehicle cabin. Each piece of information may be shown as a value evaluated on multiple levels (for example, five levels) or may be shown as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0043] The information on driving characteristics when a vehicle is a following vehicle of the own vehicle is information for evaluating whether the own vehicle will be tailgated when using the tracking control function while being followed by the vehicle. The information on driving characteristics when a vehicle is a following vehicle of the own vehicle includes, for example, information on the distance between vehicles during manual driving, steering operation, and whether the driving is taking other vehicles into consideration. Each piece of information may be shown as a value evaluated on a multiple-level scale (e.g., five levels) or as information on classified items, but the content and method of evaluation are not limited to the above examples.

[0044] (Preference information storage unit) The preference information storage unit 59 is configured by a storage element such as RAM or ROM communicably connected to the processing unit 51, or a storage medium such as an HDD, CD, DVD, SSD, USB flash, or storage device. The preference information storage unit 59 stores identification information of the driver of the vehicle 1 as well as preference information about surrounding vehicles traveling in the vicinity. The preference information about surrounding vehicles includes at least one of information about safety, comfort, environmental friendliness, and driving characteristics desired of the surrounding vehicles. The preference information about surrounding vehicles may be information about vehicle characteristics stored in the vehicle characteristic information storage unit 57 when the vehicle 1 is a preceding vehicle and when the vehicle 1 is a following vehicle of the vehicle being followed.

[0045] In this embodiment, the preference information regarding surrounding vehicles further includes information on an allowable following duration, which is the maximum continuous time allowed for vehicle 1 to follow the same preceding vehicle, and information on an allowable followed duration, which is the maximum continuous time allowed for vehicle 1 to be followed by the same following vehicle. The allowable following duration and the allowable followed duration may each be set by the driver of vehicle 1, or may be learned based on the driver's past driving conditions.

[0046] (1-2-2. Functional configuration of the processing unit) Next, the functional configuration of the processing unit 51 of the driving assistance device 50 will be described. The processing unit 51 includes an acquisition unit 61, a leading vehicle proposing unit 63, an inter-vehicle distance setting unit 67, a following control unit 69, and a notification processing unit 65. These units are functions realized by the execution of a computer program by one or more processors such as a CPU. However, some or all of the acquisition unit 61, leading vehicle proposing unit 63, inter-vehicle distance setting unit 67, a following control unit 69, and a notification processing unit 65 may be configured using analog circuits.

[0047] (Acquisition Department) The acquisition unit 61 acquires vehicle characteristic information of other vehicles traveling around the host vehicle 1. In this embodiment, the acquisition unit 61 communicates with other vehicles located within a predetermined distance from the host vehicle 1 via the vehicle-to-vehicle communication unit 37 and acquires information about the other vehicles from the other vehicles. The information about the other vehicles includes the position of the other vehicles on the map data, the direction of movement and speed of the other vehicles, and vehicle characteristic information stored in the control device. Information about the position of the other vehicles on the map data can be detected by a GNSS sensor in the other vehicles. Information about the direction of movement of the other vehicles can be detected based on changes in the position information over time in the other vehicles. Information about the speed of the other vehicles can be detected by a speed sensor in the other vehicles. The vehicle characteristic information of the other vehicles may be information stored in a vehicle characteristic information storage unit of the other vehicles.

[0048] (Advancing Vehicle Proposal Department) The preceding vehicle proposing unit 63 sets a preceding vehicle when the host vehicle 1 performs follow-up control. The preceding vehicle proposing unit 63 assumes one or more first other vehicles from among the other vehicles about which information has been acquired by the acquiring unit 61 as preceding vehicles, and identifies a second other vehicle that will be a following vehicle for the host vehicle 1 when the first other vehicle is assumed to be the preceding vehicle. In addition, the preceding vehicle proposing unit 63 sets a preceding vehicle based on preference information about surrounding vehicles of the driver of the host vehicle 1 and vehicle characteristic information of the first other vehicle and the second other vehicle.

[0049] In this embodiment, the preceding vehicle suggestion unit 63 sets a preceding vehicle in accordance with the preferences of the driver of the host vehicle 1. Specifically, for each assumed combination of a first other vehicle and a second other vehicle, the preceding vehicle suggestion unit 63 calculates the degree of match between the vehicle characteristic information of the first other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles (hereinafter also referred to as the "preceding vehicle match degree") and the degree of match between the vehicle characteristic information of the second other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles (hereinafter also referred to as the "following vehicle match degree"). Furthermore, the preceding vehicle suggestion unit 63 sets a preceding vehicle based on the preceding vehicle match degree and the following vehicle match degree.

[0050] (Notification processing unit) The notification processing unit 65 issues predetermined notifications to the user by controlling the driving of the notification device 43. In this embodiment, the notification processing unit 65 issues notifications of at least the proposal for the leading vehicle determined by the leading vehicle proposal unit 63, the proposal for changing the leading vehicle, and the start of control to follow the leading vehicle. The notification processing unit 65 issues predetermined notifications to the user by outputting sound or voice, or by displaying an image or text.

[0051] (Vehicle distance setting unit) The inter-vehicle distance setting unit 67 sets a target inter-vehicle distance between the preceding vehicle and the subject vehicle 1 during tracking control, in accordance with the degree of match (preceding vehicle match degree) of the vehicle characteristic information of the preceding vehicle to the preference information of the driver of the subject vehicle 1 regarding the surrounding vehicles. The inter-vehicle distance setting unit 67 may set the target inter-vehicle distance in accordance with the degree of match (following vehicle match degree) of the vehicle characteristic information of the following vehicle to the preference information of the driver of the vehicle 1 regarding the surrounding vehicles, in addition to the preceding vehicle match degree.

[0052] (Follow-up control unit) The following control unit 69 sets driving conditions for causing the vehicle 1 to follow the preceding vehicle at the following distance set by the following distance setting unit 67, and transmits the conditions to the vehicle control unit 41. For example, the following control unit 69 detects the surrounding environment of the vehicle 1 based on detection data transmitted from the surrounding environment sensor 31 at a predetermined sampling period, and sets a target acceleration / deceleration for causing the vehicle 1 to follow the preceding vehicle while maintaining the target following distance and avoiding collision with obstacles or other vehicles. The following control unit 69 may also set a target steering angle for causing the vehicle 1 to follow the preceding vehicle along the driving lane. The following control unit 69 transmits the set target steering angle and target acceleration / deceleration to the vehicle control unit 41. The vehicle control unit 41 controls the traveling of the host vehicle 1 based on the acquired information on the target steering angle and target acceleration / deceleration.

[0053] (1-2-3. Operation of driving assistance device) Next, an example of the processing operation by the processing unit 51 of the driving support device 50 according to this embodiment will be described with reference to a flowchart.

[0054] FIG. 3 is a flowchart showing the main routine of the processing operation of the processing unit 51. First, the processing unit 51 starts the execution of a process for suggesting a preceding vehicle (step S11). The processing unit 51 may start the execution of the process for suggesting a preceding vehicle based on an instruction input by a user, or may start the execution of the process for suggesting a preceding vehicle when the vehicle starts traveling on a predetermined road such as an expressway or a traveling area.

[0055] Next, the acquisition unit 61 of the processing unit 51 acquires information about other vehicles traveling around the host vehicle 1 (step S13). Specifically, the acquisition unit 61 communicates with one or more other vehicles present within a predetermined distance from the host vehicle 1 via the vehicle-to-vehicle communication unit 37, and acquires from each other vehicle the position of the other vehicle on the map data, the direction of movement and speed of the other vehicle, and vehicle characteristic information of the other vehicle. The vehicle characteristic information of each other vehicle includes at least any one of information on safety, comfort, environmental friendliness, or driving characteristics when the other vehicle is a preceding vehicle and a following vehicle of the vehicle executing tracking control.

[0056] Next, the preceding vehicle suggestion unit 63 sets a preceding vehicle to be suggested to the driver. In this embodiment, the preceding vehicle suggestion unit 63 executes a process of setting a preceding vehicle to be suggested in accordance with the preference of the driver of the host vehicle 1 (hereinafter also referred to as "host vehicle-based preceding vehicle suggestion process").

[0057] FIG. 4 shows a flowchart of the host vehicle-based preceding vehicle proposing process. The preceding vehicle proposing unit 63 selects any first other vehicle from the other vehicles acquired by the acquiring unit 61 and assumes it as the preceding vehicle (step S31). The preceding vehicle proposing unit 63 selects, for example, from other vehicles traveling in the same direction as the host vehicle 1 on the road on which the host vehicle 1 is traveling, a vehicle that is close to the host vehicle 1 as the first other vehicle. However, the method for selecting the first other vehicle is not particularly limited.

[0058] Next, the preceding vehicle proposing unit 63 identifies a second other vehicle that will be the following vehicle of the host vehicle 1 when the selected first other vehicle is assumed to be the preceding vehicle (step S33). For example, the preceding vehicle proposing unit 63 identifies a vehicle traveling within a predetermined distance behind the first other vehicle on the driving lane in which the first other vehicle is traveling as the second other vehicle. In this case, the predetermined distance may be set within a range of 5 to 30 meters depending on the vehicle speed of the first other vehicle or the second other vehicle, for example. If there is no corresponding second other vehicle, the preceding vehicle proposing unit 63 records that there is no vehicle that corresponds to the second other vehicle.

[0059] Next, the preceding vehicle suggestion unit 63 calculates the degree of match between the vehicle characteristic information of the first other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles (preceding vehicle match degree), and the degree of match between the vehicle characteristic information of the second other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles (following vehicle match degree) (step S35). The preceding vehicle match degree is indicated as the degree of match between each item of the preference information of the driver of the host vehicle 1 regarding the preceding vehicle stored in the preference information storage unit 59 and each item of the vehicle characteristic when the first other vehicle is the preceding vehicle, acquired from the first other vehicle. Similarly, the following vehicle match degree is indicated as the degree of match between each item of the preference information of the driver of the host vehicle 1 regarding the following vehicle stored in the preference information storage unit 59 and each item of the vehicle characteristic when the second other vehicle is the following vehicle, acquired from the second other vehicle.

[0060] The degree of match may be, for example, the ratio of the number of items with matching evaluations to the total number of items. When each item is expressed as a value evaluated on a multi-level scale, the degree of match may be determined not only based on whether the evaluated values ​​match, but also by weighting the number of levels by which the evaluated values ​​differ. Note that when a first other vehicle is selected and there is no other vehicle equivalent to a second other vehicle, the degree of match between the following vehicle of the second other vehicle is set to a preset specified value. The specified value may be, for example, 100(%), but may also be set to any other value.

[0061] Next, the preceding vehicle proposal unit 63 determines whether or not to end the calculation of the preceding vehicle match degree and the following vehicle match degree (step S37). Specifically, the preceding vehicle proposal unit 63 determines whether or not there remains a combination of a first other vehicle and a second other vehicle for which the preceding vehicle match degree and the following vehicle match degree have not been calculated, among the other vehicles traveling in the same traveling direction on the road on which the host vehicle 1 is traveling and acquired by the acquisition unit 61. The preceding vehicle proposal unit 63 may continue to calculate the preceding vehicle match degree and the following vehicle match degree until it has calculated the preceding vehicle match degree and the following vehicle match degree by assuming all other vehicles traveling in the same traveling direction on the road on which the host vehicle 1 is traveling as the first other vehicles. Furthermore, the preceding vehicle proposal unit 63 may continue to calculate the preceding vehicle match degree and the following vehicle match degree until it has calculated the preceding vehicle match degree and the following vehicle match degree by assuming a predetermined number of other vehicles traveling in the same traveling direction on the road on which the host vehicle 1 is traveling as the first other vehicles, in descending order of distance from the host vehicle 1.

[0062] When the preceding vehicle proposal unit 63 does not determine that the calculation of the preceding vehicle match degree and the following vehicle match degree is to be ended (S37 / No), it returns to step S31 and repeats the selection of the next first other vehicle, the identification of the second other vehicle, and the calculation of the preceding vehicle match degree and the following vehicle match degree. On the other hand, when the preceding vehicle proposal unit 63 determines that the calculation of the preceding vehicle match degree and the following vehicle match degree is to be ended (S37 / Yes), it sets an optimal preceding vehicle based on the calculated preceding vehicle match degree and following vehicle match degree (step S39). For example, the preceding vehicle proposal unit 63 sets the first other vehicle of the combination of the first other vehicle and the second other vehicle that maximizes the sum of the preceding vehicle match degree and the following vehicle match degree as the preceding vehicle.

[0063] In this case, the first other vehicle may be set by excluding combinations of the first other vehicle and the second other vehicle for which the preceding vehicle match degree of the first other vehicle is less than a predetermined reference minimum value. Alternatively, the first other vehicle may be set by excluding combinations of the first other vehicle and the second other vehicle for which at least one of the preceding vehicle match degree of the first other vehicle and the following vehicle match degree of the second other vehicle is less than a predetermined reference minimum value. This makes it possible to prevent either the preceding vehicle or the following vehicle from being a vehicle that does not match the preferences of the driver of the host vehicle 1, even if the sum of the preceding vehicle match degree and the following vehicle match degree is large.

[0064] 5 is an explanatory diagram showing an example of setting a preceding vehicle based on the preceding vehicle match degree and the following vehicle match degree. Fig. 5 shows the preceding vehicle match degree and the following vehicle match degree (preceding vehicle match degree / following vehicle match degree) of each of other vehicles 81, 83, 85, and 87 traveling in the same direction on the same driving lane. Furthermore, the preceding vehicle suggestion unit 63 is configured to set a preceding vehicle from among combinations of first other vehicles and second other vehicles in which the preceding vehicle match degree and the following vehicle match degree are both 50% or higher.

[0065] When only the degree of match between the vehicle characteristic information of the other vehicle that may be the preceding vehicle and the preference information of the driver of the own vehicle 1 is taken into consideration, the other vehicle 85 with the highest preceding vehicle match degree is selected as the preceding vehicle. However, in this case, the following vehicle match degree of the other vehicle 87 that will be the following vehicle is 20%, and if the other vehicle 85 is selected as the preceding vehicle, the safety or comfort of the driver of the own vehicle 1 will be reduced by the other vehicle 87 that will be the following vehicle.

[0066] In response to this, the preceding vehicle suggestion unit 63 of the driving assistance device 50 according to this embodiment selects, as the preceding vehicle, the first other vehicle having the largest sum of the preceding vehicle match degree and the following vehicle match degree from among combinations of the first other vehicle and the second other vehicle in which the preceding vehicle match degree and the following vehicle match degree are both 50% or higher. In the example shown in Fig. 5, the preceding vehicle suggestion unit 63 sets the other vehicle 81 as the preceding vehicle. This allows the driver of the host vehicle 1 to travel between a preceding vehicle that meets the driver's preferences and a following vehicle that meets the driver's preferences, thereby reducing anxiety and stress during tracking control.

[0067] 6 is an explanatory diagram showing another example of setting a preceding vehicle based on the preceding vehicle matching degree and the following vehicle matching degree. FIG. 6 shows the preceding vehicle matching degree and the following vehicle matching degree (preceding vehicle matching degree / following vehicle matching degree) of each of other vehicles 91, 92, 93, 94, and 95 traveling in the same direction in the same traveling lane into which the host vehicle 1 merges. Another vehicle 96 is traveling in a traveling lane adjacent to the traveling lane into which the host vehicle 1 merges. The preceding vehicle suggestion unit 63 is configured to set a preceding vehicle from among combinations of a first other vehicle and a second other vehicle in which the preceding vehicle matching degree and the following vehicle matching degree are both 50% or higher.

[0068] When only the degree of match between the vehicle characteristic information of other vehicles that may be the preceding vehicle and the preference information of the driver of the host vehicle 1 is taken into consideration, the other vehicle 94 with the highest preceding vehicle match degree is selected as the preceding vehicle. However, in this case, the following vehicle match degree of the other vehicle 87 that will be the following vehicle is 20%, and if the other vehicle 85 is selected as the preceding vehicle, the following vehicle 87 will reduce the safety or comfort of the driver of the host vehicle 1. For this reason, as shown in FIG. 7 , if the other vehicle 96 traveling in the adjacent driving lane cuts in front of the other vehicle 94 that will be the preceding vehicle for the host vehicle 1, when the other vehicle 94 suddenly brakes, the following vehicle 95 may brake late, resulting in a rear-end collision with the host vehicle 1.

[0069] In response to this, the preceding vehicle suggestion unit 63 of the driving assistance device 50 according to this embodiment selects the first other vehicle having the largest sum of the preceding vehicle match degree and the following vehicle match degree as the preceding vehicle from among combinations of the first other vehicle and the second other vehicle in which the preceding vehicle match degree and the following vehicle match degree are both 50% or higher. In the example shown in FIG. 6, the preceding vehicle suggestion unit 63 selects the other vehicle 93 as the preceding vehicle. This allows the driver of the host vehicle 1 to travel between the preceding vehicle and the following vehicle that match his / her preferences, thereby reducing anxiety and stress during tracking control. Therefore, as shown in FIG. 8, when another vehicle 96 traveling in an adjacent driving lane cuts in front of the host vehicle 1, the host vehicle 1 applies sudden braking, and the following vehicle 94 also applies sudden braking appropriately, thereby avoiding a rear-end collision with the host vehicle 1. Note that the other vehicle 94 may be rear-ended by the following vehicle 95.

[0070] Note that the method of setting the leading vehicle based on the preceding vehicle match degree and the following vehicle match degree is not limited to the method of setting the leading vehicle from among combinations of first and second other vehicles for which the preceding vehicle match degree and the following vehicle match degree are both 50% or higher. For example, the leading vehicle suggestion unit 63 may select, from among the identified first and second other vehicles, the first other vehicle for which the following vehicle match degree of the second other vehicle is the highest, from among first other vehicles for which the preceding vehicle match degree is a preset minimum value (e.g., 70%) or higher. This allows the host vehicle to travel between the first and second other vehicles for which the following vehicle match degree is the highest, while ensuring a match degree equal to or higher than a predetermined standard for the leading vehicle.

[0071] Returning to FIG. 3, after the preceding vehicle suggestion unit 63 sets the preceding vehicle in step S15, the notification processing unit 65 notifies the driver of the set preceding vehicle (step S17). Specifically, the notification processing unit 65 controls the driving of the notification device 43 to notify the driver of information that enables identification of the preceding vehicle that is recommended to be followed. For example, the notification processing unit 65 may display the position of the other vehicle recommended as the preceding vehicle on map data, or may notify the driver by displaying text or outputting audio. Alternatively, the notification processing unit 65 may notify the driver of information such as the model, color, and license plate number of the other vehicle recommended as the preceding vehicle.

[0072] Next, the following control unit 69 determines whether to start executing following control to make the host vehicle 1 follow the preceding vehicle that is present in front of the host vehicle 1 (step S19). The following control unit 69 may start executing following control, for example, in accordance with an operation input by the driver instructing the start of execution of following control, or may automatically start executing following control when it detects that the host vehicle 1 has moved behind the preceding vehicle proposed in step S17. Note that when starting execution of following control in accordance with an operation input by the driver, the preceding vehicle that the host vehicle 1 is to follow may be the preceding vehicle proposed in step S17, or may be a preceding vehicle different from the proposed preceding vehicle.

[0073] If the following control unit 69 does not determine to start the execution of following control (S19 / No), the process returns to step S13, and each unit of the processing unit 51 repeats the process of each step described above. On the other hand, if the following control unit 69 determines to start the execution of following control (S19 / Yes), the inter-vehicle distance setting unit 67 sets a target inter-vehicle distance between the preceding vehicle and the host vehicle 1 during following control in accordance with the preceding vehicle matching degree (step S21). In this embodiment, the inter-vehicle distance setting unit 67 corrects a previously set reference inter-vehicle distance based on predetermined conditions to set the target inter-vehicle distance. The reference inter-vehicle distance is set to a value that varies depending on, for example, the vehicle speed of the host vehicle 1.

[0074] FIG. 9 is an explanatory diagram showing the target inter-vehicle distance that is set according to the preceding vehicle coincidence degree. In the example shown in Fig. 9, the inter-vehicle distance setting unit 67 divides the preceding vehicle matching degree into three levels: "low," "medium," and "high." When the preceding vehicle matching degree of the preceding vehicle is "medium," the inter-vehicle distance setting unit 67 sets the reference inter-vehicle distance to the target inter-vehicle distance. When the preceding vehicle matching degree of the preceding vehicle is "high," the inter-vehicle distance setting unit 67 sets the target inter-vehicle distance to a value smaller than the reference inter-vehicle distance. This creates a situation in which it is difficult for another vehicle 103, whose preceding vehicle matching degree is lower than that of the current preceding vehicle 101, to enter between the preceding vehicle 101 and the subject vehicle 1, as shown in Fig. 10, and tracking control can be continued without changing the preceding vehicle 101.

[0075] On the other hand, when the preceding vehicle matching degree of the preceding vehicle is "low," the inter-vehicle distance setting unit 67 sets the target inter-vehicle distance to a value greater than the reference inter-vehicle distance. This reduces the influence that the preceding vehicle has on the host vehicle 1. Also, as shown in FIG. 11 , a situation is created in which another vehicle 103 with a higher preceding vehicle matching degree than the current preceding vehicle 101 is likely to enter between the preceding vehicle 101 and the host vehicle 1, and the host vehicle 1 can change to the other vehicle 103 with the higher preceding vehicle matching degree without changing lanes.

[0076] Furthermore, the inter-vehicle distance setting unit 67 may correct the target inter-vehicle distance according to the vehicle size, which is related to the forward visibility of the driver of the host vehicle 1, among the items of the preceding vehicle coincidence degree of the preceding vehicle. FIG. 12 is an explanatory diagram showing a setting example in which the target inter-vehicle distance is adjusted according to the visibility (vehicle size) of the driver of the host vehicle 1. The inter-vehicle distance setting unit 67 increases the target inter-vehicle distance the more likely it is that the visibility of the driver of the host vehicle 1 will decrease, that is, the larger the vehicle size of the preceding vehicle. However, an upper limit value of the target inter-vehicle distance is set so that the inter-vehicle distance between the preceding vehicle and the host vehicle 1 does not become too large. This reduces the range in which the driver of the host vehicle 1's view beyond the preceding vehicle is blocked, thereby ensuring the safety of the host vehicle 1.

[0077] Furthermore, the inter-vehicle distance setting unit 67 may set the target inter-vehicle distance taking into consideration the following vehicle match degree of the following vehicle as well as the preceding vehicle match degree. Fig. 13 is an explanatory diagram showing an example of setting the target inter-vehicle distance based on the preceding vehicle match degree and the following vehicle match degree. It is assumed that the preceding vehicle match degree of the preceding vehicle 105 is 40% and the following vehicle match degree of the following vehicle 107 is 80%.

[0078] 13, the distance from the preceding vehicle 105 that the host vehicle 1 is following to the following vehicle 107 of the host vehicle 1 is 200 m. The reference inter-vehicle distance according to the current vehicle speed of the host vehicle 1 is 60 m, and the setting range of the target inter-vehicle distance that is adjusted according to the preceding vehicle match degree and the following vehicle match degree is set to plus or minus 15 m. If the preceding vehicle match degree of the preceding vehicle 105 is 40% and the following vehicle match degree of the following vehicle 107 is 80%, the inter-vehicle distance setting unit 67 corrects the target inter-vehicle distance according to the ratio of the match degrees.

[0079] Specifically, since the ratio of the preceding vehicle match degree to the following vehicle match degree is 1:2, the inter-vehicle distance setting unit 67 increases the inter-vehicle distance with the preceding vehicle 105, which has a low match degree, and sets the target inter-vehicle distance so that the position of the front of the host vehicle 1 is at a position that divides the setting range of the target inter-vehicle distance (45 to 75 m) into a ratio of 2:1. In this way, the inter-vehicle distance is set taking into consideration the safety, comfort, etc. of the driver of the host vehicle 1 with respect to each of the preceding vehicle 105 and the following vehicle 107, according to the preceding vehicle match degree of the preceding vehicle 105 and the following vehicle match degree of the following vehicle 107.

[0080] Next, the following control unit 69 sets driving conditions for the host vehicle 1 so that the inter-vehicle distance from the preceding vehicle becomes the target inter-vehicle distance, and outputs the set driving conditions to the vehicle control unit 41 (step S23). Specifically, the following control unit 69 obtains the inter-vehicle distance from the preceding vehicle detected by the surrounding environment sensor 31, and sets a target acceleration / deceleration speed for the host vehicle 1 so that the inter-vehicle distance becomes the target inter-vehicle distance set in step S21. The following control unit 69 may further detect the left and right boundaries of the driving lane, and set a target steering angle or target steering angular velocity for driving the host vehicle 1 within the driving lane to follow the preceding vehicle. In this way, the vehicle control unit 41, which has received the information on the driving conditions, controls the driving of the driving force source 9, the electric steering device 15, and the hydraulic unit 16, thereby causing the host vehicle 1 to follow the preceding vehicle.

[0081] Next, the following control unit 69 determines whether or not to stop the execution of the following control (step S25). For example, the following control unit 69 determines to stop the execution of the following control in accordance with an operation input by the driver of the host vehicle 1 to stop the execution of the following control. When the following control unit 69 does not determine to stop the execution of the following control (S25 / No), the preceding vehicle proposing unit 63 determines whether or not to re-propose the preceding vehicle (step S27). For example, the preceding vehicle proposing unit 63 may determine whether or not the driver of the host vehicle 1 has performed an operation input to change the preceding vehicle. Furthermore, the preceding vehicle proposing unit 63 may determine whether or not to re-propose the preceding vehicle depending on whether a predetermined condition is established.

[0082] 14 and 15 are diagrams shown to explain examples of situations in which a preceding vehicle is re-proposed. As shown in FIG. 14, in a situation in which the host vehicle 1 is traveling following another vehicle 113 and another vehicle 115 is traveling following the host vehicle 1, if the host vehicle 1 continues to follow the other vehicle 113 for a long period of time, the driver of the other vehicle 113 may feel uneasy. Similarly, if the other vehicle 115 continues to follow the host vehicle 1 for a long period of time, the driver of the host vehicle 1 may feel uneasy. For this reason, the preceding vehicle proposing unit 63 may re-propose a preceding vehicle if the duration during which the host vehicle 1 is following the same preceding vehicle (following duration) exceeds a predetermined time, or if the duration during which the host vehicle 1 is being followed by the same following vehicle (followed duration) exceeds a predetermined time.

[0083] 15, when the following duration or the followed duration is both within a predetermined time, the preceding vehicle proposing unit 63 continues the following control without re-proposing a preceding vehicle. Also, when at least one of the following duration or the followed duration exceeds a predetermined time, the preceding vehicle proposing unit 63 re-proposes a preceding vehicle.

[0084] 16 is a flowchart showing an example of a process for determining whether or not to re-propose a preceding vehicle. The preceding vehicle proposing unit 63 determines whether or not the duration since the host vehicle 1 started following the current preceding vehicle (following duration) has exceeded a predetermined allowable following duration (step S41). When the preceding vehicle proposing unit 63 determines that the following duration has exceeded the predetermined allowable following duration (S41 / Yes), it determines that it is necessary to re-propose a preceding vehicle (step S45).

[0085] On the other hand, when the preceding vehicle proposal unit 63 does not determine that the following duration has exceeded the predetermined allowable following duration (S41 / No), it determines whether the duration since the host vehicle 1 began to be followed by the current following vehicle (followed duration) has exceeded the predetermined allowable followed duration (step S43). When the preceding vehicle proposal unit 63 determines that the followed duration has exceeded the predetermined allowable followed duration (S43 / Yes), it determines that it is necessary to re-propose the preceding vehicle (step S45). On the other hand, when the preceding vehicle proposal unit 63 does not determine that the followed duration has exceeded the predetermined allowable followed duration (S43 / No), it determines that it is unnecessary to re-propose the preceding vehicle (step S47).

[0086] The allowable following duration and the allowable followed duration may be set to the same time, or may be set to different times. The allowable following duration and the allowable followed duration may be set to any time by the driver, or may be automatically set by the processor based on the following duration and the followed duration during the driver's past driving. Note that the conditions for determining whether to re-propose a leading vehicle are not limited to the above example.

[0087] 3, if the preceding vehicle proposing unit 63 determines to re-propose the preceding vehicle (S27 / Yes), the process returns to step S13, and each unit of the processing unit 51 repeatedly executes the process of each step described above. On the other hand, if the preceding vehicle proposing unit 63 does not determine to re-propose the preceding vehicle (S27 / No), the following control unit 69 returns to step S23, and sets the driving conditions of the host vehicle 1 so that the inter-vehicle distance from the preceding vehicle becomes the target inter-vehicle distance, and repeats the process of outputting the set driving conditions to the vehicle control unit 41. Then, if the following control unit 69 determines in step S25 to stop the execution of the following control (S25 / Yes), it ends the following control (step S29).

[0088] As described above, the driving assistance device 50 according to this embodiment acquires vehicle characteristic information relating to the characteristics of other vehicles traveling around the host vehicle 1, assumes at least one of the other vehicles, a first other vehicle, as a preceding vehicle, and identifies a second other vehicle that will follow the host vehicle 1 when the first other vehicle is assumed to be the preceding vehicle. Furthermore, the driving assistance device 50 suggests a preceding vehicle that matches the preferences of the driver of the host vehicle 1, based on preference information about the surrounding vehicles of the driver of the host vehicle 1 and vehicle characteristic information about the first other vehicle and the second other vehicle. Therefore, the driving assistance device 50 can suggest to the driver not only a preceding vehicle to be followed by the host vehicle 1, but also other vehicles that could potentially become following vehicles that are in line with the preferences of the driver of the host vehicle 1. This makes it possible to perform tracking control of the host vehicle 1 at a driving position that is in line with the driver's safety, comfort, environmental friendliness, and driving characteristics.

[0089] Furthermore, the driving assistance device 50 according to this embodiment sets the suggested preceding vehicle based on the degree of match between the vehicle characteristic information of the first other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles, and the degree of match between the vehicle characteristic information of the second other vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles. Therefore, it is possible to suggest to the driver a preceding vehicle with which the host vehicle 1 can travel between a preceding vehicle and a following vehicle that have many items that match the driver's preferences.

[0090] Furthermore, the driving assistance device 50 according to this embodiment is further configured to be able to execute a vehicle distance setting process for setting a target vehicle distance between the preceding vehicle and the host vehicle 1 during follow-up control, depending on the degree of match between the vehicle characteristic information of the preceding vehicle and preference information of the driver of the host vehicle 1 regarding surrounding vehicles. Therefore, when the host vehicle is made to follow a preceding vehicle with a relatively low degree of match, the vehicle distance is increased, thereby making it possible to suppress a decrease in the safety, comfort, etc. of the driver.

[0091] Furthermore, the driving assistance device 50 according to this embodiment is configured to set a target inter-vehicle distance between the host vehicle 1 and the preceding vehicle in accordance with the degree of match between the vehicle characteristic information of the preceding vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles, and the degree of match between the vehicle characteristic information of the following vehicle and the preference information of the driver of the host vehicle 1 regarding the surrounding vehicles. Therefore, the inter-vehicle distance between the host vehicle 1 and the preceding vehicle can be set in consideration of the inter-vehicle distance between the host vehicle 1 and the following vehicle in accordance with the degree of match between not only the preceding vehicle but also the following vehicle.

[0092] Furthermore, in the driving assistance device 50 according to this embodiment, the preference information of the driver of the host vehicle 1 regarding surrounding vehicles includes information on the allowable following duration, which is the maximum continuous time allowed for the host vehicle 1 to follow the same preceding vehicle, and information on the allowable followed duration, which is the maximum continuous time allowed for the host vehicle 1 to be followed by the same following vehicle. The driving assistance device 50 is configured to execute the host vehicle-based preceding vehicle suggestion process again to suggest a preceding vehicle to be followed when the following duration exceeds the allowable following duration or the followed duration exceeds the allowable followed duration. Therefore, it is possible to maintain the privacy of the preceding vehicle and the host vehicle 1 and perform following control while changing the preceding vehicle.

[0093] <2. Second Embodiment> Next, a driving assistance device according to a second embodiment of the present disclosure will be described. The driving assistance device according to the first embodiment is configured to set and suggest to the driver a preceding vehicle that the host vehicle 1 will travel between, in accordance with the preferences of the driver of the host vehicle 1. In the second embodiment, the host vehicle 1 is further configured to suggest a preceding vehicle for the host vehicle 1 to follow, taking into consideration the preferences of the driver of the potential following vehicle with respect to the preceding vehicle.

[0094] The driving support device according to this embodiment will be described below in terms of differences from the driving support device according to the first embodiment.

[0095] Fig. 17 is a flowchart showing the preceding vehicle suggestion process in this embodiment, specifically showing the process executed in step S15 of the flowchart in Fig. 3. In this embodiment, the preceding vehicle suggestion unit 63 executes a process of setting a suggested preceding vehicle so that the preceding vehicle matching degree of the host vehicle 1 is equal to or higher than a predetermined standard not only for the preferences of the driver of the host vehicle 1 but also for other vehicles that may be following the host vehicle 1 (hereinafter also referred to as "leading vehicle suggestion process taking into consideration the comfort of following vehicles").

[0096] Similar to steps S31 to S33 of the flowchart in Figure 4, the preceding vehicle suggestion unit 63 selects any first other vehicle from the other vehicles acquired by the acquisition unit 61 and assumes it to be the preceding vehicle (step S51), and further identifies a second other vehicle that will be the following vehicle of the vehicle 1 when the selected first other vehicle is assumed to be the preceding vehicle (step S53).

[0097] Next, the preceding vehicle suggestion unit 63 calculates the degree of match between the vehicle characteristic information of the first other vehicle and the preference information of the driver of the host vehicle 1 regarding the preceding vehicle (preceding vehicle match degree), and the degree of match between the vehicle characteristic information of the host vehicle 1 and the preference information of the driver of the second other vehicle regarding the preceding vehicle (following vehicle reference match degree) (step S55). The preceding vehicle match degree is indicated as the degree of match between each item of the preference information of the driver of the host vehicle 1 regarding the preceding vehicle stored in the preference information storage unit 59 and each item of the vehicle characteristic when the first other vehicle is the preceding vehicle, acquired from the first other vehicle. The following vehicle reference match degree is indicated as the degree of match between each item of the preference information of the driver of the second other vehicle regarding the preceding vehicle, acquired from the second other vehicle, and each item of the vehicle characteristic when the host vehicle 1 is the preceding vehicle. The preceding vehicle match degree and the following vehicle reference match degree may be values ​​calculated in the same way as the preceding vehicle match degree described in the first embodiment.

[0098] Next, the preceding vehicle proposing unit 63 determines whether or not to end the calculation of the preceding vehicle matching degree and the following vehicle reference matching degree (step S57). Specifically, similar to step S37 of the flowchart in Fig. 4, the preceding vehicle proposing unit 63 determines whether or not there remains a combination of a first other vehicle and a second other vehicle for which the preceding vehicle matching degree and the following vehicle reference matching degree have not been calculated, among the other vehicles traveling in the same direction on the road on which the host vehicle 1 is traveling and which have been acquired by the acquiring unit 61.

[0099] When the preceding vehicle proposal unit 63 does not determine that the calculation of the preceding vehicle match degree and the following vehicle reference match degree is to be terminated (S57 / No), it returns to step S51 and repeats the selection of the next first other vehicle, the identification of the second other vehicle, and the calculation of the preceding vehicle match degree and the following vehicle reference match degree.On the other hand, when the preceding vehicle proposal unit 63 determines that the calculation of the preceding vehicle match degree and the following vehicle reference match degree is to be terminated (S57 / Yes), it sets an optimal preceding vehicle based on the calculated preceding vehicle match degree and following vehicle reference match degree (step S59).

[0100] In this embodiment, the preceding vehicle suggestion unit 63 excludes combinations of a first other vehicle and a second other vehicle for which the following vehicle reference conformance degree is less than a preset minimum reference value. The preceding vehicle suggestion unit 63 sets any combination of first other vehicles as a preceding vehicle from among combinations of first other vehicles and second other vehicles for which the following vehicle reference conformance degree is equal to or greater than the minimum reference value. This makes it possible to increase the comfort of the second other vehicle, which may be a following vehicle of the host vehicle 1, when following the host vehicle 1.

[0101] 18 is an explanatory diagram showing an example of setting a preceding vehicle based on the preceding vehicle matching degree and the following vehicle reference matching degree. FIG. 18 shows the preceding vehicle matching degree (A) and the following vehicle reference matching degree (B) of each of other vehicles 121, 123, 125, and 127 traveling in the same direction on the same driving lane. In other words, the preceding vehicle matching degree (A) indicates the matching degree of the other vehicle as a preceding vehicle from the perspective of the host vehicle 1, and the following vehicle reference matching degree (B) indicates the matching degree of the host vehicle 1 as a preceding vehicle from the perspective of the other vehicles. In addition, the preceding vehicle suggestion unit 63 is configured to set a preceding vehicle from among combinations of a first other vehicle and a second other vehicle in which the preceding vehicle matching degree and the following vehicle reference matching degree are both 50% or higher.

[0102] 18, the preceding vehicle proposing unit 63 excludes the other vehicle 127 whose preceding vehicle matching rate is less than 50% from the preceding vehicle candidates. Furthermore, although the other vehicle 125 has the highest preceding vehicle matching rate (100%), the other vehicle 127, which will be the following vehicle of the host vehicle 1 when the other vehicle 125 is the preceding vehicle of the host vehicle 1, has a following vehicle criteria matching rate of less than 50%, so the preceding vehicle proposing unit 63 excludes the other vehicle 125 from the preceding vehicle candidates.

[0103] On the other hand, when the other vehicles 121 and 123 are assumed to be the preceding vehicles of the host vehicle 1, the following vehicle reference match degrees (50%, 70%) of the other vehicles 123 and 125, which are the following vehicles of the host vehicle 1 when the other vehicles 121 and 123 are assumed to be the preceding vehicles of the host vehicle 1, are 50% or more, and therefore the preceding vehicle suggestion unit 63 sets one of the other vehicles 121 and 123 as the preceding vehicle to be suggested. In the example shown in FIG. 18 , when the other vehicle 121 is assumed to be the preceding vehicle, the sum of the preceding vehicle match degree (90%) of the first other vehicle 121 and the following vehicle reference match degree (50%) of the second other vehicle 123 is 140%. Furthermore, when the other vehicle 123 is assumed to be the preceding vehicle, the sum of the preceding vehicle match degree (80%) of the first other vehicle 123 and the following vehicle reference match degree (70%) of the second other vehicle 125 is 140%. The preceding vehicle proposing unit 63 sets the other vehicle 123 that maximizes the sum of the preceding vehicle coincidence degree of the first other vehicle and the following vehicle reference coincidence degree of the second other vehicle as the preceding vehicle to be proposed.

[0104] However, the preceding vehicle proposing unit 63 may set the preceding vehicle so that the following vehicle reference matching degree is the highest, or may set the preceding vehicle so that the preceding vehicle matching degree is the highest.

[0105] Apart from the process of setting the preceding vehicle to be proposed to the driver as described above (step S15), the driving assistance device according to this embodiment executes the tracking control function in accordance with the flowchart shown in Fig. 3. Therefore, the driving assistance device according to this embodiment can not only set a preceding vehicle that meets the preferences of the driver of the host vehicle 1, but also set a preceding vehicle that ensures the comfort of the driver of the vehicle following the host vehicle 1.

[0106] Although the preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, the present disclosure is not limited to such examples. It is clear that a person skilled in the art to which the present disclosure pertains can conceive of various modifications or alterations within the scope of the technical ideas set forth in the claims, and it is understood that these also naturally fall within the technical scope of the present disclosure. [Explanation of symbols]

[0107] 1: vehicle (host vehicle), 31: surrounding environment sensor, 31LF·31RF: front-viewing camera, 31R: rear-viewing camera, 33: vehicle state sensor, 35: GNSS sensor, 37: vehicle-to-vehicle communication unit, 41: vehicle control unit, 43: notification device, 50: driving assistance device, 51: processing unit, 53: storage unit, 55: map data storage unit, 57: vehicle characteristic information storage unit, 59: preference information storage unit, 61: acquisition unit, 63: preceding vehicle suggestion unit, 65: notification processing unit, 67: inter-vehicle distance setting unit, 69: following control unit

Claims

1. A driving assistance device that assists driving of a vehicle capable of performing follow-up control to cause the vehicle to follow a preceding vehicle, one or more processors; and one or more memories communicatively coupled to the one or more processors; the one or more processors: an acquisition process for acquiring vehicle characteristic information relating to characteristics of other vehicles traveling around the vehicle; a preceding vehicle suggestion process for assuming one or more first other vehicles among the other vehicles as the preceding vehicle, identifying a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and suggesting the preceding vehicle based on preference information regarding surrounding vehicles of the driver of the vehicle and the vehicle characteristic information of the first other vehicle and the second other vehicle; A driving assistance device that performs the following:

2. the one or more processors: setting the preceding vehicle to be proposed based on a degree of match between the vehicle characteristic information of the first other vehicle and preference information of the driver of the vehicle regarding the surrounding vehicles, and a degree of match between the vehicle characteristic information of the second other vehicle and preference information of the driver of the vehicle regarding the surrounding vehicles; The driving assistance device according to claim 1 .

3. the one or more processors: and further executing a vehicle distance setting process for setting a target vehicle distance between the preceding vehicle and the vehicle during the following control, in accordance with a degree of match between the vehicle characteristic information of the preceding vehicle and preference information of the driver of the vehicle regarding the surrounding vehicles. The driving assistance device according to claim 1 .

4. the one or more processors: setting the target inter-vehicle distance between the preceding vehicle and the vehicle in accordance with a degree of match between the vehicle characteristic information of the preceding vehicle and preference information of the driver of the vehicle regarding the surrounding vehicles, and a degree of match between the vehicle characteristic information of the following vehicle and preference information of the driver of the vehicle regarding the surrounding vehicles; The driving assistance device according to claim 3 .

5. The preference information of the driver of the vehicle regarding the surrounding vehicles includes information on an allowable following duration, which is a maximum continuous time that the vehicle is allowed to follow the same leading vehicle, and information on an allowable followed duration, which is a maximum continuous time that the vehicle is allowed to be followed by the same following vehicle, the one or more processors: When the following duration exceeds the allowable following duration or the followed duration exceeds the allowable followed duration, the preceding vehicle proposing process is executed again to propose the preceding vehicle to be followed. The driving assistance device according to claim 1 .

6. the vehicle characteristic information of the other vehicle further includes preference information of the driver of the other vehicle regarding the surrounding vehicle; the one or more processors:

2. The driving assistance device according to claim 1, wherein the first other vehicle is proposed as the preceding vehicle from among the other vehicles such that the degree of match between the vehicle characteristic information of the first other vehicle and the preference information of the driver of the vehicle regarding the surrounding vehicles is equal to or greater than a predetermined standard, and the degree of match between the vehicle characteristic information of the second other vehicle and the preference information of the driver of the vehicle regarding the surrounding vehicles is equal to or greater than a predetermined standard.

7. A driving assistance method for assisting driving of a vehicle capable of performing follow-up control to cause the vehicle to follow a preceding vehicle, comprising: the one or more processors: acquiring vehicle characteristic information relating to characteristics of other vehicles traveling around the vehicle; Assuming one or more first other vehicles among the other vehicles as the preceding vehicle, and identifying a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and proposing the preceding vehicle based on preference information regarding surrounding vehicles of the driver of the vehicle and the vehicle characteristic information of the first other vehicle and the second other vehicle; A driving assistance method comprising:

8. one or more processors, An acquisition process of acquiring vehicle characteristic information relating to the characteristics of other vehicles traveling around the vehicle; a preceding vehicle suggestion process for assuming one or more first other vehicles among the other vehicles as preceding vehicles, identifying a second other vehicle that will be a following vehicle of the vehicle when the first other vehicle is assumed to be the preceding vehicle, and suggesting the preceding vehicle when performing follow-up control based on preference information regarding surrounding vehicles of the driver of the vehicle and the vehicle characteristic information of the first other vehicle and the second other vehicle; A non-transitory tangible recording medium on which a computer program that executes the above is recorded.

Images