Driving control method and driving control device

Abstract

Provided is an autonomous driving control method, wherein, in lane change control for autonomously moving a host vehicle (V1) to an adjacent lane from a target lane where the host vehicle (V1) is traveling in a case in which a preset lane change condition is satisfied, characteristics of the target lane where the host vehicle (V1) travels are determined on the basis of lane information of a route, lane change control is executed if it has been determined, on the basis of the characteristics thereof, that the target lane is a first lane, and execution of lane change control is prohibited such that the host vehicle is caused to continue traveling in a second lane other than the first lane if it has been determined that the target lane is the second lane.

Description

Operation control method and operation control device

[0001] The present invention relates to a driving control method and a driving control device including autonomous lane change control.

[0002] A technique is known in which, when a preceding vehicle traveling at a second vehicle speed slower than a first vehicle speed, which is the control speed of the subject vehicle, the subject vehicle is made to follow the preceding vehicle at the second vehicle speed, and when a request to change lanes from an overtaking lane to a driving lane is detected while following the preceding vehicle, the control speed of the subject vehicle is made to be equal to or lower than the second vehicle speed.

[0003] Japanese Patent Application Laid-Open No. 2020-015480

[0004] However, if a vehicle changes lanes without taking into consideration the characteristics of the lane in which it is traveling, it may detect a slow-moving vehicle ahead again and repeatedly change lanes, or if it continues traveling in the same lane without changing lanes, it may slow down other vehicles behind it.

[0005] The problem to be solved by the present invention is to provide a driving control method and a driving control device including lane change control that prevents repeated lane changes by the vehicle and deceleration by other following vehicles.

[0006] The present invention solves the above problem by, in autonomous lane change control, executing a lane change when the target lane in which the vehicle is traveling is the first lane located at the very end of the route to be traveled, and prohibiting a lane change when the target lane is a second lane other than the first lane.

[0007] According to the present invention, by performing lane change control according to the characteristics of the lane in which the vehicle is traveling, it is possible to suppress repeated lane changes by the vehicle itself while suppressing deceleration by following vehicles, thereby maintaining smooth traffic flow.

[0008] It is a block diagram showing the hardware configuration of the driving control system. It is a first flowchart showing the driving control process. It is a second flowchart showing the driving control process. It is a plan view for explaining lane change control.

[0009] Figure 1 shows the configuration of a vehicle driving control system 100 according to this embodiment. The processor 10 of the driving control device 1 shown in Figure 1 includes a ROM (Read Only Memory) 12 that stores programs for controlling autonomous driving, including lane change control, a CPU (Central Processing Unit) 11 that executes the programs stored in this ROM 12, and a RAM (Random Access Memory) 13 that functions as an accessible storage device. The driving control method is implemented using each piece of hardware in the driving control system 100, including at least the processor 10.

[0010] The processor 10 executes at least the lane determination function, lane change function, and autonomous driving function through cooperation of software for realizing the above functions and the hardware components shown in FIG. 1 . The lane determination function determines the characteristics of the target lane on which the vehicle is traveling. The "characteristics" of the target lane include information on the relative position (extreme position, non-extreme position) of the lane along the road width direction on the route. This function determines whether the target lane on the route (road) is at the extreme position along the road width direction. The "characteristics" of the target lane include lane attributes such as an overtaking lane or a special lane. This function determines the characteristics of the target lane based on the attributes of the lanes on the route. The lane attributes can be obtained from lane identification information 31 included in the map information 3 or from lane identification information 31 included in a transportation system server accessible via the communication device 30. The lane change function has a function of autonomously moving the vehicle from the target lane in which the vehicle is traveling to an adjacent lane when preset lane change conditions are met based on detection information from the sensor. The lane change function also determines and controls whether to execute or prohibit lane change control based on the characteristics of the target lane. The autonomous driving function is a function of causing the vehicle to autonomously drive a route to a destination based on a driving plan via the vehicle controller 200. The driving plan includes a plan for lane changes and is a group of control commands for autonomously moving the vehicle to the destination.

[0011] The processor 10 receives commands from the user via the input / output device 20 and presents the control content as the calculation result to the user. User operations, text, voice, and image data can be used for input and output of information. The processor 10 is connected to a CAN (Controller Area Network) or other in-vehicle LAN, and exchanges information with each device inside the driving control system 100. The processor 10 exchanges information with devices external to the driving control system 100, such as a map information server, a traffic information server, and communication devices provided in roadside devices installed on roads, via a wired communication network and / or a wireless communication network.

[0012] A plurality of sensors 2 are provided on the vehicle, forming a sensor group. Each sensor 2 acquires external information according to its respective function and transmits the acquired detection information to the processor 10. The sensor 2 includes one or more cameras. The cameras include an image sensor equipped with an imaging element such as a CCD, an ultrasonic camera, and an infrared camera mounted on the vehicle. Each camera captures images of lane patterns around the vehicle (forward, backward, and to the sides), lane-related signs on the road surface, and signs installed in a position recognizable by the onboard camera. Information about the lane (attributes, traffic rules, and changes in traffic rules) can be obtained from the captured images of the signs. The sensor 2 includes a ranging sensor that detects objects and their positions around the vehicle. The sensor 2 detects the presence or absence of other vehicles traveling in front of or in adjacent lanes, as well as their relative speed and relative acceleration. Examples of ranging sensors that can be used include laser radar, millimeter-wave radar (e.g., LRF), a LiDAR (light detection and ranging) unit, and ultrasonic radar.

[0013] The map information 3 includes high-precision map information referenced in the execution of autonomous lane change control and location information for an area (area R shown in FIG. 4 , described later) in which the vehicle can use the map information. The area is defined by the start and end positions or boundary line positions (coordinates) of each road or lane. The map information 3 also includes lane identification information 31 for lanes belonging to the route (road). The lane identification information 31 includes one or more of the following: the position of the lane on the road (route) (information on the relative position, such as the extreme end along the road width), the attribute of whether the lane is an overtaking lane, and the attribute of whether the lane is a special lane. An irregular lane is a lane to which special, irregular, or irregular handling is applied to the traffic of vehicles traveling there. Special lanes include dedicated lanes where only certain vehicles are specifically permitted to travel, and variable-rule lanes where traffic rules change depending on the time of day. Special vehicles include vehicles with a certain number of occupants (e.g., two or more), public transportation vehicles such as buses, vehicles with reduced emissions, and clean energy vehicles, and are subject to special permission to drive preferentially in special lanes. Variable-rule lanes are bidirectional or reversible lanes whose rules regarding driving direction change depending on the time of day (uphill / downhill directions are reversed) in accordance with traffic plans, or lanes whose rules regarding turning right and left / entering change depending on the time of day. Assuming that traffic rules are consistent as a general rule, these lanes can be considered lanes to which irregular or unusual traffic rules apply.

[0014] The host vehicle information acquisition device 4 acquires information about the host vehicle while it is being driven, such as the current position, speed, and driving direction of the host vehicle. The host vehicle information acquisition device 4 is equipped with a GPS (Global Positioning System) unit, a gyro sensor, a vehicle speed sensor, etc., and recognizes the position of the host vehicle at each timing. The preceding vehicle recognition device 5 recognizes the current or future relative speed and relative distance to other vehicles ahead in the host vehicle's driving lane and adjacent lanes based on the detection information from the sensor 2, and provides this information to the processor 10. The navigation device 6 refers to the map information 3 and calculates a route to the set destination. The calculated route is used for autonomous driving control.

[0015] The vehicle controller 200 includes a steering control device 210 and a drive control device 220. The vehicle controller 200 acquires command values ​​for autonomous driving control according to a driving plan formulated by the processor 10 of the driving control device 1, and controls the host vehicle to travel along a route to a destination. The command values ​​include a set speed for driving the vehicle. The vehicle controller 200 drives the host vehicle according to the set speed. The set speed may be set by the driver or may be automatically set according to a predetermined standard based on detection information from the sensor 2, such as the distance to a preceding vehicle, and the relative speed and relative acceleration to the preceding vehicle. The set speed may be set for each lane. The predetermined standard is based on legal regulations. The set speed in autonomous driving control is required to be less than the legal speed limit for that lane. The upper limit of the set speed may be set according to traffic regulations related to autonomous driving and vehicle performance. The upper limit of the set speed can also be set appropriately by the vehicle operator or the driver. The command values ​​for driving control are generated by the vehicle controller 200 or the processor 10. The vehicle controller 200 inputs longitudinal and lateral forces that control the traveling position of the host vehicle V1 based on command values. In accordance with these inputs, the behavior of the vehicle body and the behavior of the wheels are controlled so that the host vehicle autonomously travels along a route to the destination. Based on these controls, at least one of the drive actuator and the brake actuator of the vehicle body drive mechanism controlled by the drive control device 220 and the steering actuator of the steering control device 210, which is activated as needed, operate autonomously, thereby executing autonomous driving control that causes the vehicle to autonomously travel along a route to the destination. Of course, the vehicle controller 200 can also perform driving according to command values ​​based on manual operation by the driver.

[0016] Based on the flowchart in FIG. 2, driving control including autonomous lane change control will be described. Lane change control is performed when the vehicle moves to an adjacent lane to follow a route to a destination or to overtake a preceding vehicle traveling in the same lane as the vehicle. The processor 10 acquires the current position of the vehicle from the vehicle information acquisition device 4 as needed (S1a) and acquires lane information related to the lanes on the route to the destination from the sensor 2 (S1b). The route to the destination is obtained from the navigation device 6. The processor 10 references map information to collect information necessary for lane change control, which is an advanced driving control (e.g., information on area Q where high-precision map information is available) (S1c). The processor 10 may also reference map information 3 to acquire lane information (S1b to S1c). The lane information includes information identifying lane characteristics, specifically, the lane's position along the road width direction and lane attributes (e.g., passing lane, special lane, reserved lane, variable lane rule). Based on the lane information, the processor 10 can determine the characteristics of the target lane in which the vehicle is traveling. Next, the processor 10 acquires information from the sensor 2, such as the presence or absence of a preceding vehicle, its position (distance), relative speed, and relative acceleration (S2). Each piece of information is acquired at a predetermined interval. The processor 10 sequentially determines whether the autonomous lane change control function has been activated (S3). One example of this determination method is to refer to the level of detail for each position in the map information 3 and determine whether the current position of the vehicle is within an "area" in which autonomous lane change control can be performed (see area R in FIG. 4 , described later). This "area" is an area in which lane identification information 31, which can identify each of multiple lanes included in the route, is available. Specifically, the "area" is an area in which a high-precision map containing lane identification information for each lane is available, and the lane identification information 31 in the map information 3 is available to the driving control device 1. The "area" may also be an area in which a system is available in which lane identification information 31 for each lane is provided from an external server, such as a roadside device. The processor 10 determines whether the vehicle is inside or outside an area based on the position information and boundary information that define the area stored in the map information 3 and the current position of the vehicle. The processor 10 detects the current position of the vehicle, and determines that autonomous lane change control can be performed when the vehicle enters an area where autonomous lane change control can be performed.In response to this determination, the processor 10 activates the autonomous lane change control function. When the autonomous lane change control function is activated, the processor 10 starts executing the lane change control process according to the characteristics of the target lane.

[0017] The processor 10 acquires lane information for the route including the target lane on which the host vehicle is traveling (S4). Based on the acquired lane information, the processor 10 determines the characteristics of the target lane on which the host vehicle is traveling. In this control example, the characteristics of the target lane are the relative lateral position of the target lane on the route. Specifically, the processor 10 determines whether the target lane is at the extreme right or left in the road width direction.

[0018] The processor 10 determines whether the target lane in which the vehicle is traveling is the first lane, which is the most extreme lane of the lanes on the route. If the target lane is not the first lane, the target lane is determined to be the second lane. The lane information includes images captured by a camera serving as the sensor 2. Images captured by the onboard camera (sensor 2) while traveling include images of lane markers that separate the left and right edges of the lane along the vehicle width direction. The lane marker images can identify the appearance of the left and right lane markers of the target lane (solid line, dashed line, color, shoulder structure, curb, etc.). The processor 10 determines the relative position of the target lane among multiple lanes included in the route based on the appearance of the left and right lane markers of the target lane, or a combination of the appearances of the left and right lane markers. For example, if it is recognized that the lane to the left of the target lane is a solid line and the lane to the right is a dashed line, the target lane can be determined to be the first lane, which is the leftmost lane of the route. If a pattern matching method based on camera images is used to determine that a curb or road shoulder structure such as a guardrail or a tree strip is located on the left side of the target lane, the target lane can be determined to be the first lane at the left end of the route. On the other hand, if it is recognized that the lanes on both sides of the target lane are dashed lines, it can be determined that the target lane is not the first lane at the end of the route. Furthermore, by extracting from the captured image the figures and text of signs displayed on the road surface and signs installed above the road or on the shoulder, the meaning of the signs can be recognized and the target lane can be determined to be an overtaking lane or a special lane.

[0019] The processor 10 also determines whether the target lane is located at the extreme end of the route by referring to the lane identification information 31 in the map information 3. The lane identification information 31 in the map information 3 includes the position of each lane included in each route (information on whether it is the extreme end lane, information indicating that it is the Nth lane from the extreme end), and lane attributes (identification information for an overtaking lane, identification information for a driving lane, and identification information for a special lane). Generally, an overtaking lane is located at the extreme left or right end of a route (road), so it is possible to determine whether the target lane is at the extreme left or right end based on the lane identification information 31 indicating that it is an overtaking lane.

[0020] Based on the lane information for the route, processor 10 determines whether a lane exists to the left of the target lane (S5). If a lane exists to the left (YES in S5), processor 10 determines whether a lane exists to the right of the target lane (S6). If lanes exist only to the left of the target lane (YES in S5 and NO in S6), processor 10 determines that the target lane is the rightmost lane of the multiple lanes on the route and determines that the target lane is the first lane (S8). Returning to S5, if no lane exists to the left (NO in S5), processor 10 determines whether a lane exists to the right of the target lane (S7). If other lanes exist only to the right of the target lane (NO in S5 and YES in S7), processor 10 determines that the target lane is the leftmost lane of the multiple lanes on the route along the road width direction and determines that the target lane is the first lane (S8). The first lane is the lane located at the farthest end of the multiple lanes on the route.

[0021] On the other hand, if there are other lanes on both the left and right sides (YES in S5 and YES in S6), the target lane is not located at the rightmost / leftmost end. If there are no other lanes on either the left or right sides (NO in S5 and NO in S7), the route has a single lane and does not have multiple lanes. In either case, the processor 10 determines that the target lane is the second lane (S13). The second lane is a lane other than the first lane. If the processor 10 determines in step S13 that the target lane in which the host vehicle is traveling is the second lane other than the first lane, it prohibits the execution of lane change control and causes the host vehicle to continue traveling in the second lane (S15). Before processing step S15, the processor 10 may notify or suggest to the driver the control content of traveling in the current lane without changing lanes, and execute lane change control after obtaining approval.

[0022] If it is determined that the target lane in which the host vehicle is traveling is the first lane (S8), the process proceeds to step S9. The processor 10 reads the lane change conditions (S9) and determines whether the lane change conditions are met or not based on information acquired from the sensor 2, the host vehicle information acquisition device 4, and the preceding vehicle recognition device 5. The determination result of whether the lane change conditions are met or not can be presented to the occupants via the input / output device 20. The occupants include the driver. The presented information informs the occupants of the possibility of lane change control execution. The processor 10 detects a preceding vehicle traveling in the lane to which the host vehicle is to change lanes (S10). If no preceding vehicle is present in the specified detection area (NO in S10), a travel space after the lane change is secured, and the process proceeds to step S14. The processor 10 determines whether the distance between the host vehicle and the preceding vehicle detected in the lane to which the host vehicle is to change lanes is within a predetermined range (greater than or equal to the first distance and less than the second distance (> the first distance)) (YES in S10, S11). The presence of a preceding vehicle traveling far enough away (greater than the second distance) that it does not affect the execution of the lane change by the host vehicle V1 can be ignored. The distance threshold is set from the perspective of whether a driving space necessary for the host vehicle V1 to execute a lane change is formed in the destination lane. The threshold distance between the preceding vehicle and the host vehicle can be defined according to the relative speed between the preceding vehicle and the host vehicle. If no preceding vehicle is present within the set predetermined range (NO in S11), a driving space after the lane change is secured, and the process proceeds to step S14. Even if a preceding vehicle is present within the set range (YES in S11), if the vehicle speed of the preceding vehicle at the lane change destination is higher than the set speed of the host vehicle (NO in S12), it is expected that a driving space for the host vehicle V1 will be formed eventually, and the process proceeds to step S14. In step S14, the processor 10 starts lane change control and moves the host vehicle from the target lane to an adjacent lane. Note that the processor 10 may notify or suggest a lane change to the driver before processing step S14 and execute lane change control after obtaining approval.

[0023] On the other hand, even if a preceding vehicle is present within the predetermined range (YES in S10 and S11), if the vehicle speed of the preceding vehicle to which the vehicle V1 is to change lanes is lower than the set speed of the vehicle V1 (YES in S12), the vehicle V1 is unlikely to have sufficient space to change lanes, and the process proceeds to step S15. In S15, as described above, driving control is performed to maintain the current lane without changing lanes. Although it is currently difficult to change lanes (YES in S12), if the vehicle continues traveling in the first lane, where the vehicle speed is relatively high, it is likely that the vehicle V1 will eventually be able to overtake the preceding vehicle that was the subject of consideration in S12. At that time, the vehicle V1 can reconsider whether to change lanes from the first lane. By waiting for the next opportunity, the vehicle V1 can change lanes without disrupting traffic flow in the target lane. Note that the threshold value may be given hysteresis (width) to prevent the determination result in S12 from fluctuating near the threshold boundary.

[0024] The lane change conditions may also include a condition as to whether or not there is space for the host vehicle to enter a lane adjacent to the destination lane after the lane change. The lane adjacent to the destination lane after the lane change includes the original lane (target lane) on which the host vehicle was traveling before the lane change. After processing steps S10, S11, and S12, and before processing step S14, processor 10 checks whether or not there is space for the host vehicle to move into a lane adjacent to the lane into which the host vehicle will travel after the lane change. That is, as a lane change condition for executing a lane change from the target lane, processor 10 checks in advance whether there is space for the host vehicle to move into an adjacent lane from the lane into which the host vehicle will travel after the lane change. If it is confirmed that there is space for the host vehicle to move into a lane adjacent to the lane into which the host vehicle will travel after the lane change, the process proceeds to step S14. On the other hand, if the existence of such space is not confirmed, the process proceeds to step S15, even if the determinations in S10, S11, and S12 are YES, S13, and NO, respectively.

[0025] The first lane at the rightmost or leftmost end of the route is likely to be an overtaking lane. The first lane at the rightmost or leftmost end of the route is predicted to have a relatively higher travel speed than other lanes. When the processor 10 determines that the attribute of the target lane is an overtaking lane based on the acquired lane information, it determines that the target lane is the first lane. If the map information 3 includes attribute information that enables identification of whether or not a lane is an overtaking lane as lane identification information 31, this information is used. Furthermore, if such lane identification information 31 is obtained from a traffic information server or an external device of the traffic system via the communication device 30, this information is used. By using the information indicating an overtaking lane to determine whether the target lane is the first lane or the second lane, the processing load can be reduced and a more rapid determination can be made compared to making the above determination by analyzing the captured image acquired by the sensor 2.

[0026] In addition, the processor 10 does not determine that a special lane belongs to the first lane. When determining whether a special lane is the first lane, the processor 10 excludes the special lane regardless of its location. If the processor 10 determines, based on the lane information, that the characteristic attributes of all lanes to the right or left of the target lane are special lanes (dedicated lanes or variable-rule lanes), the processor 10 determines that the target lane is the first lane. In other words, the processor 10 excludes the special lane from the determination and determines the lane adjacent to the special lane as the first lane. Generally, a special lane is located at the rightmost or leftmost end of a route. Although multiple lanes may be considered special lanes, they are located consecutively from the rightmost or leftmost end. Therefore, a lane located next to one or more special lanes, i.e., an adjacent lane to a special lane, can be determined to be the first lane.

[0027] In a different determination method, if the attribute characteristic of the target lane is determined to be a special lane based on lane information, the target lane is determined to be the second lane, not the first lane. In this control, a lane change is performed when traveling in the first lane. In other words, determining whether or not a lane is the first lane is an important factor in determining the content of lane change control. In this example, special lanes on which only certain vehicles are permitted to travel or whose traffic rules change depending on the time of day are not determined to be the first lane. This allows for appropriate determination of whether or not a lane is the first lane, and lane change control is performed in line with the goal of maintaining smooth traffic flow.

[0028] FIG. 3 shows a procedure for determining whether a target lane is the first lane, taking into account lane attributes such as an overtaking lane and / or a special lane. Lane attributes are one aspect of a lane's characteristics. Since steps S1a, S1b, S1c, S2-S4, S8-S15, and S13-S15 shown in FIG. 2 are common processes, the above-mentioned explanations are incorporated herein. In FIG. 3, steps S1a, S1b, S1c, and S2-S4 of FIG. 2 are performed, and the explanation begins with step S4, in which lane information for the target lane is acquired. In the lane determination process shown in FIG. 3, it is determined whether lane information related to lane attributes such as "overtaking lane" or "special lane" can be acquired from the lane identification information 31 in the map information 3. The processor 10 reads the identification information (version information and function identification information) of the map information 3 to be referenced and determines whether the map information 3 has lane identification information 31 including the "overtaking lane" attribute (S101). If lane information identifying an overtaking lane can be obtained from the lane identification information 31 of the map information 3 (YES in S101) and the target lane is an overtaking lane (YES in S102), the processor 10 determines that the host vehicle is traveling in the overtaking lane (first lane) (S105). Then, the processor 10 executes the processing from S8 onward in FIG. 2. On the other hand, if the target lane is not an overtaking lane (NO in S102), the processor 10 determines that the host vehicle is traveling in a lane other than the overtaking lane (second lane) (S103). Then, the processor 10 shifts to S13 in FIG. 2 and executes the processing of S15.

[0029] If the identification information of the passing lane cannot be obtained from the lane information (NO in S101), the process proceeds to S107. The processor 10 reads the specific information (version information) of the map information 3 to be referenced and determines whether the map information 3 has lane identification information 31 including the attribute of a "special lane" (S107). If the processor 10 obtains information indicating that the target lane is a special lane (YES in S107), the processor 10 determines that the target lane is the second lane (S103). If the target lane is not a special lane (NO in S107), the processor 10 refers to traffic rules (S108). Traffic rules include a rule that the passing lane is the leftmost lane (or the rightmost lane) for multiple lanes on a route (road). In the United States, the leftmost lane (excluding special lanes) is the passing lane, while in Japan, the rightmost lane (excluding special lanes) is the passing lane. The processor 10 refers to a traffic rule (S108) and determines whether the traffic rule stipulating that the leftmost lane is an overtaking lane applies to the target lane (S109). The processor 10 can determine the traffic rule that applies to the host vehicle based on the destination of each vehicle written in the ROM 12. The processor 10 may also refer to traffic rules associated with a region or location and determine the traffic rule that applies to the host vehicle based on the current position of the host vehicle acquired by the host vehicle information acquisition device 4. If the traffic rule stipulating that the leftmost lane is an overtaking lane applies (YES in S109), and if there is no lane to the left of the target lane (NO in S110) and there is a lane to the right of the target lane (YES in S111), the processor 10 determines that the host vehicle is traveling in the first lane, which is an overtaking lane (S105). If there are no lanes to the right or left of the target lane (NO in S110, NO in S111), the system determines that the vehicle is traveling in a driving lane (second lane) that is not an overtaking lane (S103). On the other hand, if there is a lane to the left of the target lane (YES in S110) but none of the lanes on the left are special lanes (NO in S112), that is, if there is a lane other than a special lane on the left, the system determines that the target lane is a driving lane (second lane) (S103). Also, if all lanes on the left are special lanes (YES in S110 and YES in S112) but there is no lane on the right (NO in S113), there are no lanes through which the vehicle can change lanes, so the system determines that the target lane is a driving lane (second lane) (S103).If all lanes on the left side are special lanes (YES in S110 and YES in S112) and there is also a lane on the right side (YES in S113), the target lane is determined to be an overtaking lane (first lane) (S105).

[0030] Note that S101 and S107 may be skipped and the process may proceed from S4 to S108 (shown by the dashed line in FIG. 3). Even if information about passing lanes or special lanes is not available, the position of the target lane along the road width direction can be determined using, for example, images captured by the camera of sensor 2, as described above. That is, processor 10 can determine whether the target lane is the first lane at the right or left edge by referring to traffic rules. This allows for highly accurate determination of whether the target lane is the first lane, which is an overtaking lane, even if lane attribute information is not available from map information 3. As a result, lane change control can be performed that does not interfere with the smooth travel of the vehicle itself or other vehicles.

[0031] Returning to S109, consider the case where the traffic rule stipulating that the passing lane is the leftmost lane does not apply, i.e., the traffic rule stipulating that the passing lane is the rightmost lane applies (NO in S109). If there is no lane to the right of the target lane (NO in S114) and there is a lane to the left of the target lane (YES in S117), the host vehicle is determined to be traveling in the first lane, which is the passing lane (S105). If there are no lanes to the right or left of the target lane (NO in S114, NO in S117), the host vehicle is determined to be traveling in the second lane (S103). On the other hand, if there is a lane to the right of the target lane (YES in S114) but none of the lanes on the right are special lanes (NO in S115), i.e., if there is a lane other than a special lane on the right, the host vehicle is determined to be the driving lane (second lane) (S103). Furthermore, if all lanes on the right side are special lanes (YES in S114 and YES in S115) but there are no lanes on the left side (NO in S116), there are no multiple lanes into which a lane change is possible, so the target lane is determined to be a driving lane (second lane) (S103). If all lanes on the right side are special lanes (YES in S114 and YES in S115) and there is also a lane on the left side (YES in S116), the target lane is determined to be an overtaking lane (first lane) (S105). The driving lane is a lane that is not an overtaking lane and is classified as a second lane. In the above process, if it is determined that the target lane in which the vehicle is traveling is the first lane, which is an overtaking lane (S105), the process shifts to S8 in FIG. 2 and the processes of S9-15 are performed. On the other hand, if it is determined that the target lane in which the vehicle is traveling is the second lane, which is a driving lane (non-passing lane) (S103), the process shifts to S13 in FIG. 2 and the process of S15 is performed.

[0032] FIG. 4( a) shows an example of lane change control when the target lane is the first lane, and FIG. 4( b) shows an example of lane change control when the target lane is the second lane. The processor 10 starts lane change control processing when the autonomous lane change control function is activated. The processor 10 determines when the host vehicle V1 enters a range Q (indicated by a dashed line) within which autonomous lane change control can be performed, and starts execution of lane change control at that time. The region Q is an area within which the autonomously traveling host vehicle V1 can use information necessary for autonomous lane change control, such as lane identification information 31 for identifying each lane belonging to the route. The map information 3 includes boundary information in which the boundaries of the region Q are defined by position information. The region Q is defined for each lane or route (road), and may be defined by position information for the start point Q1 and the end point Q2 of each of the lanes L1 to L4. The processor 10 refers to the boundary information of the area Q in the map information 3, compares it with the current position of the vehicle V1 acquired from the vehicle information acquisition device 4, and determines that the vehicle V1 has entered the area Q. When the vehicle V1 enters the area Q, the processor 10 activates an autonomous lane change control function and switches the lane change control from manual control mode to autonomous control mode. A notice of and execution of the switching of the lane change control mode are presented to the occupant via the input / output device 20. Note that before the vehicle V1 enters the area Q, autonomous driving control other than lane changing (such as lane keeping control) is performed, and lane change control is performed manually by the driver.

[0033] After the autonomous lane change control function is activated, the processor 10 periodically acquires lane information for the target lane in which the host vehicle V1 is traveling and determines whether the target lane is the first lane or the second lane. This determination may be made in parallel with, or before or after, the determination of whether the lane change condition is satisfied or not. In this example, the leftmost lane L1 is the first lane. Lane L1 is also an overtaking lane. The traveling speed in lane L1 (first lane) is higher than the traveling speed in the other lanes L2-L4 (second lane). The traveling speed is the vehicle speed in actual traffic. The traveling speed may be the set speed of the autonomously driven vehicle or the speed limit to which autonomously driven and manually driven vehicles must comply. Note that the autonomous driving control is performed at a predefined set speed. The set speed specified for autonomous driving in the first lane is lower than the legal speed limit in the first lane. The traveling speed of the host vehicle V1 traveling in the first lane at a set speed below the speed limit under autonomous driving control is predicted to be relatively slower than that of a manually driven vehicle traveling at the speed limit.

[0034] At timing T1 shown in FIG. 4A, the host vehicle V1 (T1) travels outside of area Q. The driver manually changes lanes, causing the host vehicle V1 (T1) to move from lane L2 to lane L1 (first lane), which is the leftmost passing lane. When the processor 10 determines that the host vehicle V1 has entered area Q, it activates the autonomous lane change control function. At subsequent timing T2, the host vehicle V1 (T2) travels on lane L1 within area Q. Based on the lane information, the processor 10 determines that lane L1 is the first lane, which is the farthest lane of the route. When the processor 10 determines that the target lane in which the host vehicle V1 is traveling is the first lane, the processor 10 executes lane change control, triggered by the determination that the lane change condition has been satisfied, to autonomously move the host vehicle V1 (T2) to the adjacent lane L2. Lane L2 is the second lane, not the first lane.

[0035] Incidentally, within the region Q where autonomous lane change control is possible, autonomously driven vehicles, including those that can change lanes, and manually driven vehicles travel together. The set speed of the host vehicle V1, which is autonomously driven in the first lane, is lower than the legal speed limit for the first lane. The set speed of the host vehicle V1 tends to be set lower than the speed limit for the first lane, taking into account vehicle performance, autonomous driving control performance, traffic volume, and the driving environment. On the other hand, since the speed limit is set based on the road environment, past performance, and experience, manually driven vehicles are predicted to travel in the first lane at a speed close to the speed limit, while keeping the speed limit as an upper limit. In other words, the traveling speed (set speed) of the host vehicle V1 in the first lane is predicted to be lower than the traveling speed of manually driven vehicles. Therefore, if the host vehicle V1, which is autonomously driven, continues to travel in the first lane at a relatively low speed, following vehicles, particularly manually driven vehicles, may be forced to decelerate or prevented from accelerating. If a vehicle is forced to decelerate in the first lane, which has a relatively higher travel speed than the second lane, the smoothness of traffic flow in the entire first lane is disrupted. Furthermore, drivers of manually driven vehicles traveling in the first lane, which has a relatively higher travel speed, expect to be able to freely accelerate or maintain speed depending on the situation. It is undesirable for an autonomously driven vehicle to interfere with this expectation. When the processor 10 determines that the lane change condition is met, if the target lane is the first lane, it moves the host vehicle V1 from the first lane to an adjacent lane. This prevents other vehicles, such as the manually driven vehicle V3 following the host vehicle V1, which is predicted to have a slower travel speed than the manually driven vehicle V3, from being forced to decelerate or suppress their speed (abandon acceleration), thereby maintaining the smoothness of traffic flow.

[0036] At timing T1 shown in FIG. 4(b), the host vehicle V1 (T1) travels outside the area Q. The host vehicle V1 (T1) moves from lane L3 to lane L2 (second lane) due to a manual lane change by the driver. Although not shown, the host vehicle V1 (T1) may also manually change lanes from the leftmost lane L1 to lane L2. When it is determined that the host vehicle V1 has entered the area Q, the processor 10 activates the autonomous lane change control function. At timing T2, the host vehicle V1 (T2) enters the area Q and travels on lane L2 within the area Q. Based on the lane information, the processor 10 determines that lane L2 is not the first lane. The processor 10 determines that the target lane L2 in which the host vehicle V1 (T2) is traveling is the second lane. Based on this determination, the processor 10 prohibits the execution of autonomous lane change control from the lane L2 to the adjacent lanes L1 and L3, even if it determines that the lane change conditions are satisfied within the region Q. The processor 10 causes the host vehicle V1 (T2) to continue traveling in the target lane L2, which is determined to be the second lane. If a driver is present to manage the driving of the host vehicle V1, the processor 10 can propose control content to the driver before executing each autonomous control, including the autonomous lane change control. The driver may be physically present in the host vehicle V1, or may remotely manage the driving of the host vehicle V1 via communication. The driver can decide whether to adopt or reject the control content proposed by the processor 10 and instruct the processor 10 to that effect via the input / output device 20. The processor 10 executes the control content in accordance with the instructions input by the driver. If the processor 10 determines to prohibit the execution of autonomous lane change control, it prohibits the autonomous lane change control proposal process. By prohibiting the proposal process, the execution of autonomous lane change control is essentially prohibited. The processor 10 can also skip the process of proposing control content. In the figure, the prohibition control of proposing a lane change for the vehicle V1 is indicated by the letters [NG]. Of course, even if the processor 10 determines to prohibit the execution of autonomous lane change control, the autonomous lane change based on the driver's instruction, or the autonomous lane change to merge toward a destination or exit is still executed.

[0037] Assume that at time T2, the host vehicle V1 (T2) traveling in the second lane L2 accelerates and changes lanes from lane L2 to lane L1 to overtake the preceding vehicle V2 (T2) detected at the same time T2. As described above, autonomously driven vehicles and manually driven vehicles coexist within area Q, and the traveling speed of the manually driven vehicles in lane 1 of area Q is predicted to be higher than the set speed of the autonomously driven vehicles. Therefore, the host vehicle V1 traveling in lane 1 may hinder the acceleration or decelerate the following manually driven vehicle. By prohibiting the host vehicle V1 from changing lanes from lane 2 to lane 1, it is possible to prevent other vehicles following the host vehicle V1 from decelerating or abandoning their acceleration operations. Deceleration control by other vehicles includes autonomous control by a control device and manual control by a driver. As a result, lane change control can be performed without disrupting the smooth flow of traffic in lane 1.

[0038] Also, suppose that at time T2, the host vehicle V1 (T2) traveling in the second lane L2 accelerates and changes lanes from lane L2 (second lane) to lane L3 (second lane) to overtake the preceding vehicle V2 (T2) detected at the same time T2. Even when the host vehicle V1 moves from lane L2 to lane L2, neither the speed limit nor the host vehicle's set speed changes, so the situation is unlikely to change. Furthermore, the traveling speed of lane L3, which is farther away from lane L1, which is predicted to have the highest traveling speed, than lane L2, may be lower than the traveling speed of lane L2. Therefore, even if the host vehicle V1 changes lanes to lane L3, there is a high possibility that the host vehicle V1 will again detect the slow preceding vehicle V2 in lane L3. When the host vehicle V1 is traveling in the second lane, the processor 10 prohibits the host vehicle V1 from changing lanes to other lanes, particularly the second lane. This prevents the vehicle from detecting a low-speed preceding vehicle again after changing lanes and repeatedly changing lanes, thereby realizing stable driving of the vehicle V1.

[0039] In addition, when the processor 10 determines that the target lane is the second lane, it prohibits execution of lane change control to move the host vehicle V1 back to the original lane that the host vehicle V1 was traveling in before traveling to the target lane. At timing T1 in FIG. 4B , the host vehicle V1 (T1) was traveling in lane L3 but then changed lanes to lane L2. Based on the fact (history) that a lane change was performed at timing T1, it is predicted that the traveling speed of the original lane L3, which the host vehicle V1 was traveling in before moving to lane L2, was low. In other words, even if the host vehicle V1 returns to the original lane L3, a low-speed preceding vehicle may be detected again. If no control is performed, the detection of a low-speed preceding vehicle may trigger lane change control to be performed again, and depending on the situation, lane change control may be repeated. Therefore, even if the lane change condition is satisfied, when the target lane is determined to be the second lane, the host vehicle V1 (T1) is prohibited from changing lanes to the original lane L3 that the host vehicle V1 was traveling in. This prevents repeated lane changes.

[0040] Furthermore, in this example, control is performed to delay the execution of lane change control by a predetermined time. Specifically, the processor 10 executes lane change control when a predetermined time has elapsed since a trigger point for executing the lane change control. Specifically, the processor 10 executes lane change control when a predetermined time has elapsed since any of the following points: 1) when it is determined that the target lane in which the host vehicle V1 is traveling is the first lane, 2) when it is determined that the lane change condition is satisfied, 3) when the autonomous lane change control function is activated, 4) when it is determined that the host vehicle V1 has entered an area Q where autonomous lane change control can be executed, and 5) when a lane change was executed before the timing when it was determined that the lane change condition was satisfied (the most recent lane change was executed). Incidentally, while executing autonomous driving control, the processor 10 manages the state and operation of the host vehicle in chronological order and can acquire any of the points 1 to 5 stored in the RAM 13. Even if the lane change conditions are satisfied, the processor 10 does not immediately change lanes, but waits for a predetermined time to elapse before executing lane change control. In other words, even if the lane change conditions are satisfied during the predetermined time, the processor 10 invalidates the determination and waits for a determination that the lane change conditions are satisfied after the predetermined time has elapsed. This allows at least a predetermined pause time to be set between the previous execution of lane change control and the current execution of lane change control, thereby preventing frequent lane changes. The predetermined time does not need to be uniformly specified, and different times can be set depending on the starting point of the predetermined time listed in 1 to 5 above. The times listed in 1 to 4 above are after the autonomous lane change control function is activated. When the autonomous lane change control function is activated and the driving control content changes, immediate lane changes can be prevented. The time listed in 5 above is a time before the autonomous lane change control function is activated. Even before the autonomous lane change control function is activated, the processor 10 stores and manages the operation of the vehicle over time in the RAM 13, so it can obtain the timing of the previous manual lane change from the RAM 13. In this control, two lane changes, one before and one after the activation of the autonomous lane change control, are performed with a predetermined time interval between them. The autonomous lane change is performed after a predetermined time has elapsed since the manual lane change.If autonomous lane change control were enabled immediately after activation, an autonomous lane change that invalidates a lane change executed by manual control may be executed. By waiting for a predetermined time to elapse, autonomous driving that respects the driver's driving intentions expressed in the immediately preceding manual driving can be executed, and the driver will not be confused.

[0041] 100... driving control system, 1... driving control device, 10... processor, 11... CPU, 12... ROM, 13... RAM, 20... input / output device, 30... communication device, 2... sensor, 3... map information, 31... lane identification information, 4... vehicle information acquisition device, 5... preceding vehicle recognition device, 6... navigation device, 200... vehicle controller, 210... steering control device, 220... drive control device

Claims

1. A driving control method used in a processor to control autonomous driving that causes the vehicle to travel along a route, The processor, when pre-set lane change conditions are met, executes lane change control to autonomously move the vehicle from the target lane in which it is traveling to an adjacent lane. In the lane change control described above, the processor, Based on the lane information of the aforementioned route, the characteristics of the target lane in which the vehicle is traveling are determined. Based on the above characteristics, if it is determined that the target lane is the first lane located at the very edge of the multiple lanes of the route, the lane change control is executed. A driving control method that, when it is determined that the target lane is a second lane other than the first lane, prohibits the execution of the lane change control and causes the vehicle to continue driving in the second lane.

2. The driving control method according to claim 1, wherein the processor determines, based on the lane information, that the attribute of the target lane is an overtaking lane, and then determines that the target lane is a first lane.

3. The driving control method according to claim 1, wherein the processor determines, based on the lane information, that all lanes located to the right or left of the target lane are either dedicated lanes where only specific vehicles are permitted to travel, or lane with variable traffic rules where traffic rules change depending on the time of day, and the processor determines that the target lane is the first lane.

4. The driving control method according to claim 1, wherein the processor determines, based on the lane information, that the target lane is the second lane if it determines that the attributes of the target lane are a dedicated lane in which only specific vehicles are permitted to travel, or a lane with variable traffic rules in which traffic rules are changed according to the time of day.

5. The driving control method according to claim 1, wherein the processor determines that the vehicle has entered an area in which the autonomous lane change control can be performed, and initiates the autonomous lane change control.

6. The driving control method according to claim 1, wherein the lane change control is executed when a predetermined time has elapsed from any of the following points in time: when it is determined that the target lane in which the vehicle is traveling is the first lane; when it is determined that the lane change conditions have been met; when the autonomous lane change control function is activated; when it is determined that the vehicle has entered an area in which the autonomous lane change control can be executed; and when the lane change control was executed manually immediately before.

7. The driving control method according to any one of claims 1 to 6, wherein the processor, when it is determined that the target lane is the second lane, prohibits the execution of the lane change control that moves the vehicle to the lane it was traveling in before traveling in the target lane.

8. It is equipped with a processor that controls autonomous driving, which makes the vehicle follow the route. The processor, when pre-set lane change conditions are met, executes lane change control to autonomously move the vehicle from the target lane in which it is traveling to an adjacent lane. In the lane change control described above, the processor, Based on the lane information of the aforementioned route, the characteristics of the target lane in which the vehicle is traveling are determined. Based on the above characteristics, if it is determined that the characteristics of the target lane are those of the first lane located at the very edge of the route, the lane change control is executed. If it is determined that the target lane is a second lane other than the first lane, the driving control device prohibits the execution of the lane change control and causes the vehicle to continue driving in the second lane.