Driving control method and driving control device

Abstract

The processor (10) of the drive control device (100) compares the vehicle speed (V1) of the host vehicle (1) traveling on the first lane (L1) with the vehicle speed of the adjacent other vehicle traveling on the second lane (L2), and determines whether the relative speed of the adjacent other vehicle (3) with respect to the host vehicle (1) is below a prescribed speed difference threshold value, and relaxes the travel condition for allowing the host vehicle (1) to travel at a prescribed drive assist level in the case where the relative speed is below the speed difference threshold value.

Description

TECHNICAL FIELD

[0001] The present application relates to a driving control method and a driving control device. BACKGROUND

[0002] In the driving control method described in Patent Literature 1, the driving of the host vehicle is controlled to follow the preceding vehicle at a prescribed driving assistance level, and in a case where the lateral movement amount of the preceding vehicle is greater than a prescribed value, the driving assistance level is lowered.

[0003] PRIOR ART DOCUMENTS

[0004] PATENT LITERATURE

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2020-104802

[0006] PROBLEMS TO BE SOLVED BY THE INVENTION

[0007] However, in the driving control method described in Patent Literature 1, since the driving assistance level corresponding only to the driving environment of the host lane is set, there is a problem that the timing of setting the prescribed driving assistance level is limited. SUMMARY

[0008] The present application relates to a driving control method and a driving control device.

[0009] The present application solves the above problem by comparing the vehicle speed of the host vehicle and the vehicle speed of the adjacent other vehicle traveling on the adjacent lane, and relaxing (mitigating) the driving condition for allowing the host vehicle to travel at the prescribed driving assistance level in a case where the relative speed of the adjacent other vehicle with respect to the host vehicle is below a prescribed speed difference threshold.

[0010] EFFECTS OF THE INVENTION

[0011] According to the present application, the driving condition is relaxed in a case where the relative speed of the adjacent other vehicle with respect to the host vehicle is below the speed difference threshold, and thus an effect of being able to increase the timing of setting the prescribed driving assistance level is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a block diagram showing the structure of the driving control device of the present embodiment.

[0013] Figure 2 is a diagram showing an example of the host vehicle avoiding an obstacle in front.

[0014] Figure 3 is a diagram showing an example of the positional relationship between the host vehicle, the preceding vehicle, and the adjacent other vehicle.

[0015] Figure 4 is a diagram indicating an example of positional relationship among the host vehicle, the adjacent other vehicle, and the rear other vehicle.

[0016] Figure 5 is a flowchart indicating the order of a driving control method executed by the driving control device shown in Figure 1 DETAILED DESCRIPTION

[0017] Hereinafter, an embodiment of the present application will be described based on the drawings.

[0018] Figure 1 is a block diagram indicating the structure of the host vehicle 1 and the driving control device 100 that controls autonomous driving of the host vehicle 1. The host vehicle 1 is provided with: the driving control device 100, a detection device 101, a host vehicle position acquisition section 102, a map database 103, an in-vehicle device 104, an input device 105, and a drive control device 106.

[0019] The driving control device 100 autonomously controls the vehicle speed and the steering of the host vehicle 1 by the autonomous travel control function by executing a program stored in a ROM by a CPU. The driving control device 100 can set a driving mode corresponding to a driving assistance level, and can assist the travel of the host vehicle by the set driving mode. The driving assistance level is a level indicating the degree of intervention when the driving control device 100 assists the driving of the vehicle by the autonomous travel control function. The higher the driving assistance level, the lower the contribution of the driver to the driving of the vehicle. Specifically, the driving assistance level can be set to levels 0 to 5 using the definition based on SAE J3016 of the Society of Automotive Engineers (SAE) or the like. In level 0, the driving operation of the host vehicle is performed entirely manually by the driver. In level 1, the driving operation of the host vehicle is mainly performed manually by the driver, but the driving control device 100 appropriately assists the manual driving of the driver by any one of the functions of automatic braking, following, lane keeping, and the like. In level 2, the driving operation of the host vehicle is mainly performed manually by the driver, but in a specific condition, the driving control device 100 can execute driving assistance by combining a plurality of functions among the functions of automatic braking, following, lane keeping, and the like. In level 3, the driving control device 100 performs all driving tasks, but the driver needs to take back the control in the case where there is a request from the driving control device 100, and performs preparation for driving by manual driving. In level 4, manual driving by the driver is not required, the driving control device 100 can perform all driving tasks in a specific condition, and monitors the surrounding situation of the host vehicle. In level 5, the driving control device 100 can perform all driving tasks in all conditions. ​

[0020] In addition, the driving mode corresponding to Level 2 is an eyes-on mode. That is, in a case where the driving assistance level is set to Level 2, the driver needs to monitor the surrounding situation of the host vehicle 1 by vision. In a case where the driving assistance level is set to Level 2, the orientation of the face and the movement of the eyes of the driver are monitored by a camera in the vehicle or the like, and in a case where the driver visually confirms the front, the running of the host vehicle 1 is permitted. In addition, the driving mode corresponding to Level 2 is a hands-on mode. The hands-on mode is a mode in which the autonomous steering control of the processor 10 does not act in a case where the driver does not hold the steering wheel 104a. In addition, whether or not the driver holds the steering wheel 104a is detected by a touch sensor (not shown) provided on the steering wheel 104a or a steering torque sensor (not shown) of the EPS.

[0021] In addition, "the driver holds the steering wheel 104a" includes not only a state in which the driver tightly holds the steering wheel 104a but also a state in which the driver lightly holds the steering wheel 104a with a hand.

[0022] On the other hand, the driving mode corresponding to Level 3 is an eyes-off mode. That is, in a case where the driving assistance level is set to Level 3, the processor 10 controls the driving of the host vehicle 1 by the eyes-off mode in which the running of the host vehicle 1 is permitted in a state where the driver does not visually confirm the front. At this time, the system of the driving control device 100 autonomously monitors the surrounding situation of the host vehicle using a camera, a radar, or the like. In addition, the driving mode corresponding to Level 3 is a hands-off mode. The hands-off mode is a mode in which the steering control of the processor 10 acts even if the driver moves the hand from the steering wheel 104a. That is, in a case where the driving assistance level is set to Level 3, the processor 10 controls the driving of the host vehicle 1 by the hands-off mode in which the running of the host vehicle 1 is permitted in a state where the driver releases the hand from the steering wheel of the host vehicle 1.

[0023] In addition, the classification of the driving assistance level is not limited to the classification according to the definition of the Society of Automotive Engineers of America, and the driving assistance level can be defined based on the ISO / TC204 of the International Organization for Standardization (ISO). In addition, the classification of the driving assistance level can be defined according to other standards as long as it is appropriately classified according to the degree of intervention of the driving control device 100.

[0024] The detection device 101 has either one or both of a vehicle-mounted camera that takes a picture of the surroundings of the host vehicle 1 or a radar that detects other vehicles or obstacles in the surroundings of the host vehicle. The detection result of the detection device 101 is output to the driving control device 100 at a prescribed time interval.

[0025] The host vehicle position acquisition section 102 is constituted by a GPS unit, a gyro sensor, a vehicle speed sensor, and the like. The host vehicle position acquisition section 102 detects radio waves transmitted from a plurality of communication satellites by the GPS unit, acquires position information of the host vehicle 1 periodically, and detects the current position of the host vehicle 1 based on the acquired position information of the host vehicle 1, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor. The position information of the host vehicle 1 detected by the host vehicle position acquisition section 102 is output to the driving control device 100 at a prescribed time interval.

[0026] The map database 103 is a storage that stores three-dimensional high-precision map information including position information of various facilities and specific locations, and is accessible from the driving control device 100. The map database 103 stores high-precision digital map information (high-precision map, dynamic map). The high-precision map information includes identification information of a plurality of lanes that a road has. The map information of the map database 103 includes three-dimensional position information about roads and / or curved roads and the size (e.g., curvature or radius of curvature) of the curved roads, merging locations, branching locations, and positions where the number of lanes is reduced. The high-precision map information also includes information about facilities such as service areas and parking areas.

[0027] The on-vehicle device 104 is various devices mounted on the vehicle and actuated by operation by the driver. The on-vehicle device 104 includes a steering wheel 104a. As other on-vehicle devices 104, there are listed an accelerator pedal, a brake pedal, a navigation device, a direction indicator, a wiper, a lamp, a horn, or other specific switches, and the like. In a case where the driver operates the on-vehicle device 104, the information is output to the driving control device 100.

[0028] The input device 105 is, for example, a button switch that enables input by manual operation by the driver, a touch panel provided on a display screen, or a microphone that enables input by the voice of the driver, or the like.

[0029] The drive control device 106 controls the driving of the host vehicle 1 based on the control command of the driving control device 100. For example, the drive control device 106 controls the operation of a drive mechanism (including the operation of an internal combustion engine in an engine vehicle, the operation of a traveling electric motor in an electric vehicle system, and the torque distribution of an internal combustion engine and a traveling electric motor in a hybrid vehicle) for adjusting the acceleration / deceleration and the vehicle speed and the operation of a brake by an autonomous speed control function. In addition, the drive control device 106 performs steering control of the host vehicle by controlling the operation of a steering wheel actuator by an autonomous steering control function. For example, the drive control device 106 detects a lane marker on a lane in which the host vehicle is traveling, and controls the travel position (lateral position) of the host vehicle in the width direction so that the host vehicle travels in the center of the lane. In addition, the drive control device 106 controls the host vehicle to overtake a preceding vehicle, change the travel direction, and the like. Furthermore, the drive control device 106 performs travel control for right or left turning at an intersection or the like. In addition, as the travel control method of the drive control device 106, other publicly known methods can be used. In addition, as shown in Figure 2 The drive control device 106 performs steering control of the host vehicle 1 to avoid the obstacle X in front of the host vehicle 1 according to the control command of the processor 10. That is, the driving control device 100 controls the driving of the host vehicle 1 to avoid the obstacle X in front of the host vehicle 1 using the processor 10.

[0030] Next, the use of the driving control device 100 will be described. Figures 1 to 4 The structure of the driving control device 100 will be described in detail.

[0031] In addition, in the following description, the "predetermined driving assistance level" is set to level 3, but is not limited thereto. The processor 10 can set a driving mode corresponding to another driving assistance level in addition to level 3.

[0032] As shown in Figure 1As shown, the drive control device 100 is provided with a processor 10. The processor 10 is constituted by a ROM (Read Only Memory) in which a program for controlling driving of the host vehicle is stored, a CPU (Central Processing Unit) that executes the program stored in the ROM, and a RAM (Random Access Memory) that functions as an accessible storage device. In addition, as an action circuit, instead of or in addition to the CPU (Central Processing Unit), an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or the like can be used. The processor 10 is provided with an evaluation value calculation section 11, a relative speed determination section 12, a travel condition setting section 13, an evaluation value determination section 14, and a vehicle control section 15. The evaluation value calculation section 11, the relative speed determination section 12, the travel condition setting section 13, the evaluation value determination section 14, and the vehicle control section 15 execute programs for realizing the respective functions of the processor 10.

[0033] In addition, in Figure 1 The drive control device 100 is mounted on the host vehicle 1, but is not limited thereto, and the drive control device 100 can be a device that remotely operates the host vehicle 1.

[0034] The evaluation value calculation section 11 calculates an evaluation value that indicates the sufficiency (satisfaction) of a travel condition for allowing the host vehicle 1 to travel at a prescribed driving assistance level (for example, Level 3). The travel condition is, for example, that the host vehicle 1 travels at or below a prescribed set speed. In this example, the evaluation value calculation section 11 calculates the evaluation value in such a manner that the evaluation value corresponding to a second vehicle speed lower than a first vehicle speed is higher than the evaluation value corresponding to the first vehicle speed of the host vehicle 1. That is, the lower the vehicle speed VI of the host vehicle 1, the higher evaluation value the evaluation value calculation section 11 calculates.

[0035] In addition, the travel condition for allowing the host vehicle 1 to travel at a prescribed driving assistance level is, for example, as Figure 3As shown, the host vehicle 1 can also be traveling behind the preceding vehicle 2. In this example, the evaluation value calculation portion 11 calculates the evaluation value in such a manner that the evaluation value corresponding to a second inter-vehicle distance shorter than a first inter-vehicle distance is higher than the evaluation value corresponding to the first inter-vehicle distance, based on the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2. That is, the shorter the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2, the higher the evaluation value calculated by the evaluation value calculation portion 11. In addition, the evaluation value calculation portion 11 can also calculate the evaluation value in such a manner that the evaluation value corresponding to a second elapsed time shorter than a first elapsed time is higher than the evaluation value corresponding to the first elapsed time, based on the elapsed time since the preceding vehicle 2 was detected. That is, the shorter the elapsed time since the preceding vehicle 2 was detected, the less likely it is that there is an obstacle on the path traveled by the preceding vehicle 2, and thus the higher the evaluation value calculated by the evaluation value calculation portion 11.

[0036] In addition, "the host vehicle 1 traveling behind the preceding vehicle 2" includes not only the host vehicle 1 following the preceding vehicle 2, but also the host vehicle 1 not following the preceding vehicle 2, but traveling behind the preceding vehicle 2 on the travel path traveled by the preceding vehicle 2.

[0037] In addition, the travel conditions for allowing the host vehicle 1 to travel at a prescribed level of driving assistance include, in addition to the above conditions, the host vehicle 1 traveling on a road where high-precision map information is effectively used, a signal of a Global Navigation Satellite System (GNSS) being effective, the driver visually confirming the front, there being no tollbooth, exit of an expressway, merge, intersection, or location where the number of lanes decreases within a certain distance (e.g., within about 800 m ahead) of the current position, and there being no sharp curve of 100 R or less within a certain distance (e.g., within about 500 m ahead) of the current position. The evaluation value calculation portion 11 calculates the evaluation value indicating the sufficiency of the travel conditions for allowing the host vehicle 1 to travel at a prescribed level of driving assistance, based on one or more of the above conditions. For example, the evaluation value calculation portion 11 can calculate the sufficiency (degree of satisfaction) for each of the above conditions separately, and calculate the evaluation value by aggregating the calculated sufficiencies.

[0038] In addition, as Figure 3As shown, when the detection device 101 detects an adjacent vehicle 3 traveling in the second lane L2, the relative speed determination unit 12 compares the speed V1 of the host vehicle 1 with the speed V3 of the adjacent vehicle 3 to determine whether the relative speed of the adjacent vehicle 3 relative to the host vehicle 1 is below a predetermined speed difference threshold. The relative speed of the adjacent vehicle 3 relative to the host vehicle 1 is the absolute value of the speed difference between the speed V1 of the host vehicle 1 and the speed V3 of the adjacent vehicle 3. The speed difference threshold is set based on whether, when the host vehicle 1 changes lanes to the second lane L2, acceleration and deceleration control allows the host vehicle 1 to maintain a predetermined inter-vehicle distance behind the adjacent vehicle 3 within a predetermined time. Furthermore, when multiple adjacent vehicles 3 are detected, the relative speed determination unit 12 may calculate the average speed of the multiple adjacent vehicles 3 as the speed V3 of the adjacent vehicles 3. In addition, when there are adjacent lanes (second lanes) on both the left and right sides of the first lane L1, the relative speed determination unit 12 selects the speed V3 of the adjacent other vehicles 3 traveling at a speed closer to the speed V1 of the own vehicle 1 from among the adjacent other vehicles 3 traveling in the multiple second lanes L2, and calculates the relative speed.

[0039] In addition, if Figure 4 As shown, when another vehicle 4 is located within a predetermined distance behind the host vehicle 1, the relative speed determination unit 12 selects a second speed difference threshold value, which is lower than the first speed difference threshold value when no other vehicle 4 is located behind the host vehicle 1, and sets the second speed difference threshold value as the speed difference threshold value. Specifically, when another vehicle 4 is located within a predetermined distance behind the host vehicle 1, the relative speed determination unit 12 sets the speed difference threshold value lower than when no other vehicle 4 is located behind the host vehicle 1. The predetermined distance is the upper limit of the inter-vehicle distance at which acceleration or deceleration of the host vehicle 1 is predicted to affect the other vehicle 4 located behind the host vehicle 1.

[0040] Further, the travel condition setting portion 13 sets a travel condition for allowing the host vehicle 1 to travel at a prescribed level of driving assistance, depending on whether the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below a prescribed speed difference threshold. The travel condition setting portion 13 has an evaluation threshold setting portion 13a. The evaluation threshold setting portion 13a sets an evaluation threshold that is a criterion for determining whether the host vehicle 1 is in a state in which the host vehicle 1 is able to perform a lane change from the first lane LI to the second lane L2 at a prescribed level of driving assistance. That is, the evaluation threshold setting portion 13a sets a condition under which the host vehicle 1 is able to perform a lane change from the first lane LI to the second lane L2 at a prescribed level of driving assistance, and sets a value corresponding to the set condition as the evaluation threshold. The evaluation threshold setting portion 13a sets a second evaluation threshold that is lower than a first evaluation threshold in a case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the speed difference threshold, as the evaluation threshold in a case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the speed difference threshold. That is, the evaluation threshold setting portion 13a relaxes the travel condition for allowing the host vehicle 1 to travel at a prescribed level of driving assistance in a case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the speed difference threshold, as compared to a case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is above the speed difference threshold. Specifically, in a case where the evaluation threshold setting portion 13a sets a vehicle speed VI of the host vehicle 1 below a prescribed set speed as the travel condition for allowing the host vehicle 1 to travel at a prescribed level of driving assistance, the evaluation threshold setting portion 13a sets the set speed in a case where the relative speed is below the speed difference threshold (for example, 65 km / h) to be higher than the set speed in a case where the relative speed is above the speed difference threshold (for example, 60 km / h). That is, the travel condition setting portion 13 relaxes the travel condition for allowing the host vehicle 1 to travel at a prescribed level of driving assistance in a case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the speed difference threshold.

[0041] Further, the state in which the host vehicle 1 is able to perform a lane change from the first lane LI to the second lane L2 at a prescribed level of driving assistance means that the driving control device 100 controls driving of the host vehicle 1 traveling on the first lane LI at a prescribed level of driving assistance, and causes the host vehicle 1 to perform a lane change from the first lane LI to the second lane L2 in a state in which the driving is maintained at a prescribed level of driving assistance in a case where a lane change is required.

[0042] Further, the evaluation value determination portion 14 compares the evaluation value calculated by the evaluation value calculation portion 11 and the evaluation threshold set by the evaluation threshold setting portion 13a, and determines whether the evaluation value is higher than the evaluation threshold. Specifically, in a case where the evaluation threshold setting portion 13a sets a condition that the vehicle speed VI of the host vehicle 1 is below a prescribed set speed as a condition for allowing the host vehicle 1 to make a lane change at a prescribed driving assist level, the evaluation value determination portion 14 determines that the evaluation value is higher than the evaluation threshold when the vehicle speed VI of the host vehicle 1 becomes below the set speed.

[0043] Further, the evaluation value determination portion 14 can also determine whether the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2 is below a prescribed set inter-vehicle distance, and determine that the evaluation value is higher than the evaluation threshold in a case where the inter-vehicle distance is below the prescribed set inter-vehicle distance. Further, the evaluation threshold setting portion 13a sets the set inter-vehicle distance in a case where the relative speed is below the speed difference threshold to be longer than the set inter-vehicle distance in a case where the relative speed is higher than the speed difference threshold.

[0044] Further, the evaluation value determination portion 14 can also determine whether the elapsed time since the detection device 101 detected the preceding vehicle 2 is longer than a prescribed set elapsed time, and determine that the evaluation value is higher than the evaluation threshold in a case where the elapsed time is longer than the set elapsed time. Further, the evaluation threshold setting portion 13a sets the set elapsed time in a case where the relative speed is below the speed difference threshold to be shorter than the set elapsed time in a case where the relative speed is higher than the speed difference threshold.

[0045] Figure 1 The vehicle control portion 15 illustrated allows the host vehicle 1 to travel at a prescribed driving assist level in a case where the evaluation value is higher than the evaluation threshold. That is, the vehicle control portion 15 makes the host vehicle 1 a state in which the host vehicle 1 can make a lane change from the first lane LI to the second lane L2 at a prescribed driving assist level in a case where the evaluation value is higher than the evaluation threshold. Specifically, the vehicle control portion 15 controls the driving of the host vehicle 1 traveling on the first lane LI at a prescribed driving assist level regardless of the presence or absence of the preceding vehicle 2 in a case where the evaluation value is higher than the evaluation threshold. Then, as described above, the vehicle control portion 15 controls the driving of the host vehicle 1 traveling on the first lane LI at a prescribed driving assist level regardless of the presence or absence of the preceding vehicle 2 in a case where the evaluation value is higher than the evaluation threshold. Figure 2As shown, the vehicle control section 15 causes the host vehicle 1 to make a lane change from the first lane LI to the second lane L2 while maintaining the prescribed level of driving assistance, in the case where an obstacle X is detected in front of the host vehicle 1, and the like. Thereby, the host vehicle 1 can avoid the obstacle X while maintaining the prescribed level of driving assistance. In addition, the vehicle control section 15 performs the lane change control of the host vehicle 1 so that the host vehicle 1 after the lane change travels behind the adjacent other vehicle 3, but is not limited thereto, and can also control the host vehicle 1 to travel in front of the adjacent other vehicle 3. In addition, the vehicle control section 15 can also cause the host vehicle 1 to make a lane change from the second lane L2 to the first lane LI again after performing the lane change control of the host vehicle 1. On the other hand, in the case where the evaluation value is below the evaluation threshold value, the vehicle control section 15 does not allow the host vehicle 1 to travel at the prescribed level of driving assistance. Therefore, in the case where an obstacle X is detected in front, the host vehicle 1 avoids the obstacle X at a lower level of driving assistance (e.g., level 2) than the prescribed level of driving assistance.

[0046] In addition, as shown in Figure 3 , Figure 4 , in the case where the adjacent other vehicle 3 travels in front of the host vehicle 1, the vehicle control section 15 controls the vehicle speed VI of the host vehicle 1 traveling on the first lane LI so that the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 becomes below the speed difference threshold value. That is, the vehicle control section 15 controls the vehicle speed VI of the host vehicle 1 so as to maintain the state in which the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the speed difference threshold value. In addition, the vehicle control section 15 controls the driving of the host vehicle 1 so that there is no other vehicle in parallel in the lateral direction (side direction) of the host vehicle 1, in the case where the vehicle speed VI is controlled so that the relative speed becomes below the speed difference threshold value.

[0047] In addition, the processor 10 can not set the evaluation threshold value, but can set the travel condition according to whether or not the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is below the prescribed speed difference threshold value. In addition, the processor 10 can not perform the calculation of the evaluation value, but can determine whether or not the travel environment of the host vehicle 1 satisfies the travel condition.

[0048] Next, the sequence of the driving control method performed by the driving control device 100 will be described using the flowchart shown in Figure 5 .

[0049] As shown in Figure 5 , in step S1, the evaluation value calculation section 11 of the processor 10 calculates an evaluation value indicating the sufficiency of the travel condition for allowing the host vehicle 1 to travel at the prescribed level of driving assistance.

[0050] Next, in step S2, the relative speed determination section 12 calculates the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 based on the vehicle speed V3 of the adjacent other vehicle 3 acquired by the detection device 101.

[0051] Next, in step S3, the relative speed determination section 12 determines whether or not the relative speed calculated in step S2 is equal to or lower than the speed difference threshold value. In a case where it is determined in step S3 that the relative speed is not equal to or lower than the speed difference threshold value, i.e., the relative speed is higher than the speed difference threshold value, in step S4, the evaluation threshold value setting section 13a selects and sets the first evaluation threshold value as the evaluation threshold value. On the other hand, in a case where it is determined in step S3 that the relative speed is equal to or lower than the speed difference threshold value, in step S5, the evaluation threshold value setting section 13a selects and sets the second evaluation threshold value, which is lower than the first evaluation threshold value, as the evaluation threshold value.

[0052] Next, in step S6, the evaluation value determination section 14 determines whether or not the evaluation value is higher than the evaluation threshold value. In a case where the evaluation value is higher than the evaluation threshold value, in step S7, the vehicle control section 15 allows the host vehicle 1 to travel at the prescribed level of driving assistance. That is, in step S7, the vehicle control section 15 makes the host vehicle 1 into a state in which the host vehicle 1 is able to perform a lane change from the first lane LI to the second lane L2 at the prescribed level of driving assistance. On the other hand, in a case where the evaluation value is equal to or lower than the evaluation threshold value, in step S8, the vehicle control section 15 does not allow the host vehicle 1 to travel at the prescribed level of driving assistance. That is, in a case where the evaluation value is equal to or lower than the evaluation threshold value, when the host vehicle 1 performs a lane change from the first lane LI to the second lane L2, the driving control device 100 controls the driving of the host vehicle 1 at a level (e.g., level 2) lower than the prescribed level of driving assistance.

[0053] As described above, the processor 10 of the driving control device 100 of the present embodiment compares the vehicle speed VI of the host vehicle 1 traveling on the first lane LI with the vehicle speed V3 of the adjacent other vehicle 3 traveling on the second lane L2, and determines whether or not the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is equal to or lower than the prescribed speed difference threshold value. Then, the processor 10 relaxes the traveling condition for allowing the host vehicle 1 to travel at the prescribed level of driving assistance in a case where the relative speed is equal to or lower than the speed difference threshold value. Thereby, the driving control device 100 is able to perform the driving control of the host vehicle 1 at the level of driving assistance corresponding to the traveling environment of the second lane L2, which is the adjacent lane. That is, the driving control device 100 is able to increase the timing at which the prescribed level of driving assistance is set. For example, as described above, in a case where the adjacent other vehicle 3 is traveling at a high speed on the second lane L2, the driving control device 100 is able to perform the driving control of the host vehicle 1 at a level of driving assistance higher than the prescribed level of driving assistance. Figure 2As shown, in the case where an obstacle X exists in front of the host vehicle 1 traveling on the first lane LI, and the like, in an emergency situation, the driving control device 100 is able to perform the lane change control of the host vehicle 1 in accordance with the driving environment of the second lane L2 (the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1) at a prescribed driving assistance level, and thus is able to smoothly travel while avoiding the obstacle X.

[0054] In addition, the processor 10 of the driving control device 100 calculates an evaluation value of the sufficiency of the driving condition for allowing the host vehicle 1 to travel at the prescribed driving assistance level. In addition, the processor 10 selects, as the evaluation threshold, a second evaluation threshold lower than the first evaluation threshold in the case where the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 is higher than the speed difference threshold, and allows the host vehicle 1 to travel at the prescribed driving assistance level in the case where the evaluation value is higher than the evaluation threshold. Thus, the driving control device 100 is able to cause the host vehicle 1 to be in a state where the host vehicle 1 is able to change lanes from the first lane LI to the second lane L2 at the prescribed driving assistance level in the case where the evaluation value is higher than the evaluation threshold. Thus, as shown, in the case where an obstacle X exists in front of the host vehicle 1 traveling on the first lane LI, and the like, in an emergency situation, the driving control device 100 is able to perform the lane change control of the host vehicle 1 in accordance with the driving environment of the second lane L2 (the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1) at a prescribed driving assistance level, and thus is able to smoothly travel while avoiding the obstacle X. Figure 2 As shown, in the case where an obstacle X exists in front of the host vehicle 1 traveling on the first lane LI, the host vehicle 1 is able to maintain the prescribed driving assistance level and smoothly travel while avoiding the obstacle X. In addition, the driving control device 100 is able to determine whether to allow the host vehicle 1 to travel at the prescribed driving assistance level on the basis of the comparison between the specific evaluation value and the evaluation threshold.

[0055] In addition, the processor 10 of the driving control device 100 selects, as the speed difference threshold, a second speed difference threshold lower than the first speed difference threshold in the case where the rear other vehicle 4 is present within the prescribed distance Dx rearward of the host vehicle 1. Thus, the driving control device 100 makes the condition for determining that the relative speed is below the speed difference threshold strict when the rear other vehicle 4 is likely to be affected by the acceleration and deceleration of the host vehicle 1, and thus is able to suppress the travel of the host vehicle 1 at the prescribed driving assistance level.

[0056] In addition, the processor 10 of the driving control device 100 controls the vehicle speed VI of the host vehicle 1 so that the relative speed of the adjacent other vehicle 3 with respect to the host vehicle 1 becomes below the speed difference threshold in the case where the adjacent other vehicle 3 is traveling in front of the host vehicle 1. Thus, the driving control device 100 maintains the state where the relative speed is below the speed difference threshold and controls the vehicle speed VI of the host vehicle 1, and thus the host vehicle 1 is able to change lanes to the second lane L2 without performing a large acceleration and deceleration in the case where an obstacle X is detected in front, and the like.

[0057] Further, the processor 10 of the driving control device 100 calculates the evaluation value in such a manner that the evaluation value corresponding to a second vehicle speed of the host vehicle 1 lower than a first vehicle speed of the host vehicle 1 is higher than the evaluation value corresponding to the first vehicle speed of the host vehicle 1. Thus, the lower the vehicle speed V1 of the host vehicle 1, the more easily the driving control device 100 allows the host vehicle 1 to travel at the prescribed driving assist level. That is, the lower the vehicle speed V1 of the host vehicle 1, the more easily the host vehicle 1 performs the lane change at the prescribed driving assist level in the case where the host vehicle 1 detects the obstacle X ahead, and the like.

[0058] Further, the processor 10 of the driving control device 100 can calculate the evaluation value in such a manner that the evaluation value corresponding to a second inter-vehicle distance shorter than a first inter-vehicle distance is higher than the evaluation value corresponding to the first inter-vehicle distance, on the basis of the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2. Thus, the shorter the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2, the more easily the driving control device 100 allows the host vehicle 1 to travel at the prescribed driving assist level. That is, the shorter the inter-vehicle distance between the host vehicle 1 and the preceding vehicle 2, the more easily the host vehicle 1 performs the lane change at the prescribed driving assist level in the case where the host vehicle 1 detects the obstacle X ahead, and the like.

[0059] Further, the processor 10 of the driving control device 100 can calculate the evaluation value in such a manner that the evaluation value corresponding to a second inter-vehicle distance shorter than a first inter-vehicle distance is higher than the evaluation value corresponding to the first inter-vehicle distance, on the basis of the elapsed time after the preceding vehicle 2 is detected ahead of the host vehicle 1. Thus, the shorter the elapsed time after the preceding vehicle 2 is detected, the more easily the driving control device 100 allows the host vehicle 1 to travel at the prescribed driving assist level. That is, the shorter the elapsed time after the preceding vehicle 2 is detected, the more easily the host vehicle 1 performs the lane change at the prescribed driving assist level in the case where the host vehicle 1 detects the obstacle X ahead, and the like.

[0060] Further, the processor 10 of the driving control device 100 calculates the average vehicle speed of the plurality of adjacent other vehicles 3 as the vehicle speed of the adjacent other vehicles 3 in the case where the plurality of adjacent other vehicles 3 is detected. Thus, the driving control device 100 can perform the driving control of the host vehicle 1 at the driving assist level corresponding to the travel environment of the second lane L2 on the basis of the vehicle speed of the plurality of adjacent other vehicles 3.

[0061] The processor 10 of the driving control device 100 controls the driving of the host vehicle 1 in the hand release mode in which the host vehicle 1 is allowed to travel in a state where the driver releases the hands from the steering wheel of the host vehicle 1 when the driving of the host vehicle 1 is controlled at the prescribed driving assist level. Thus, the driving control device 100 controls the driving of the host vehicle 1 in the hand release mode when the driving of the host vehicle 1 is controlled at the prescribed driving assist level, and thus can reduce the driving burden of the driver.

[0062] The processor 10 of the driving control device 100 controls the driving of the host vehicle 1 when controlling the driving of the host vehicle 1 at a prescribed driving assist level, by the eye-off mode that allows the host vehicle 1 to travel in a state where the driver does not visually confirm the front. Thus, the driving control device 100 controls the driving of the host vehicle 1 in the eye-off mode when controlling the driving of the host vehicle 1 at a prescribed driving assist level, and thus it is possible to reduce the driving burden on the driver.

[0063] Symbol explanation

[0064] 1: Host vehicle

[0065] 3: Adjacent other vehicle

[0066] 4: Rear other vehicle

[0067] 100: Driving control device

[0068] 10: Processor

[0069] 11: Evaluation value calculation section

[0070] 12: Relative speed determination section

[0071] 13: Traveling condition setting section

[0072] 15: Vehicle control section

[0073] L1: First lane

[0074] L2: Second lane

Claims

1. A driving control method of controlling driving of a host vehicle using a processor so that the host vehicle avoids an obstacle ahead, wherein the processor performs processing of: comparing a vehicle speed of the host vehicle traveling on a first lane and a vehicle speed of an adjacent other vehicle traveling on a second lane adjacent to the first lane, and determining whether a relative speed of the adjacent other vehicle with respect to the host vehicle is below a prescribed speed difference threshold, relaxing a driving condition for allowing the host vehicle to travel at a prescribed driving assistance level when traveling on the first lane, in a case where the relative speed is below the speed difference threshold.

2. The driving control method according to claim 1, wherein the processor performs processing of: calculating an evaluation value indicating sufficiency of the driving condition, selecting a second evaluation threshold lower than a first evaluation threshold in a case where the relative speed is higher than the speed difference threshold, as an evaluation threshold, allowing the host vehicle to travel at the driving assistance level, in a case where the evaluation value is higher than the evaluation threshold.

3. The driving control method according to claim 2, wherein the processor selects a second speed difference threshold lower than a first speed difference threshold in a case where there is a rear other vehicle within a prescribed distance rearward of the host vehicle, as the speed difference threshold.

4. The driving control method according to claim 2 or 3, wherein the processor controls the vehicle speed of the host vehicle so that the relative speed of the adjacent other vehicle with respect to the host vehicle becomes below the speed difference threshold, in a case where the adjacent other vehicle travels ahead of the host vehicle.

5. The driving control method according to claim 2 or 3, wherein the processor calculates the evaluation value in such a manner that the evaluation value corresponding to a second vehicle speed of the host vehicle lower than a first vehicle speed is higher than the evaluation value corresponding to the first vehicle speed of the host vehicle.

6. The driving control method according to claim 2 or 3, wherein the processor calculates the evaluation value based on a vehicle-to-vehicle distance between the host vehicle and a preceding vehicle traveling on the first lane, in such a manner that the evaluation value corresponding to a second vehicle-to-vehicle distance shorter than a first vehicle-to-vehicle distance is higher than the evaluation value corresponding to the first vehicle-to-vehicle distance.

7. The driving control method according to claim 2 or 3, wherein the processor calculates the evaluation value in such a manner that the evaluation value corresponding to a second elapsed time shorter than a first elapsed time is higher than the evaluation value corresponding to the first elapsed time, in a case where a preceding vehicle is detected ahead of the host vehicle on the first lane.

8. The driving control method according to any one of claims 1 to 3, wherein the processor calculates an average vehicle speed of a plurality of the adjacent other vehicles as the vehicle speed of the adjacent other vehicle, in a case where a plurality of the adjacent other vehicles are detected.

9. The driving control method according to any one of claims 1 to 3, wherein ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The processor controls driving of the host vehicle by a hand-off mode that allows the host vehicle to travel in a state where a driver has his hands off a steering wheel of the host vehicle, when driving of the host vehicle is controlled at the driving assistance level.

10. The driving control method according to any one of claims 1 to 3, wherein The processor controls driving of the host vehicle by an eye-off mode that allows the host vehicle to travel in a state where a driver does not visually confirm a front, when driving of the host vehicle is controlled at the driving assistance level.

11. A driving control device that controls driving of a host vehicle using a processor to cause the host vehicle to avoid an obstacle ahead, wherein The processor includes: a relative speed determination section that compares a vehicle speed of the host vehicle traveling on a first lane and a vehicle speed of an adjacent other vehicle traveling on a second lane adjacent to the first lane, and determines whether a relative speed of the adjacent other vehicle with respect to the host vehicle is below a prescribed speed difference threshold value; a travel condition setting section that relaxes a travel condition for allowing the host vehicle to travel on the first lane at a prescribed driving assistance level, in a case where the relative speed is below the speed difference threshold value.

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