Vehicle control method and vehicle control device

Abstract

A controller 20 determines whether the current position of an own vehicle (1) is located within a high-precision map available region (Rav) in which high-precision map information (13H) is available, and when determining that the current position of the own vehicle is located within the high-precision map available region (Rav), on the basis of specified speed information acquired by recognizing a speed sign on a captured image or specified speed information acquired from the high-precision map information (13H) on the basis of the current position of the own vehicle, executes acceleration / deceleration control for controlling acceleration / deceleration of the own vehicle and notifies a drive of the specified speed information. Further, when the own vehicle is predicted to move out from the high-precision map available region (Rav), the controller 20 finishes acceleration / deceleration control based on the specified speed information at a point (Pc) before a point (Po) at which the own vehicle moves out from the high-precision map available region (Rav), and acquires specified speed information from road map information (13N) lower in precision than the high-precision map information (13H), on the basis of the current position of the own vehicle to notify the driver of the acquired specified speed information.

Description

[Technical field]

[0001] The present invention relates to a vehicle control method and a vehicle control device. [Background technology]

[0002] The road sign recognition device described in Patent Document 1 listed below recognizes a road sign from an image captured by an imaging unit, and if the recognized road sign matches a road sign in the map information, sets the reliability of the map information to "high," holds the reliability until the next time the reliability is determined, and if the reliability is "high," determines that the road sign in the map information is the road sign corresponding to the current location. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2019-212188 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, high-precision map information has become known as a map suitable for use in autonomous driving. By using information on designated speeds (e.g., speed limits and recommended speeds) stored in the high-precision map information in combination, it is possible to obtain the designated speed information even if a state in which a speed sign is not recognized from an image captured by a camera continues. This makes it possible to control the acceleration or deceleration of the vehicle based on the appropriate designated speed information. However, the area in which high-precision map information can be used is limited, and in an area in which high-precision map information cannot be used, if a state in which a speed sign is not recognized from an image captured by a camera continues and it becomes impossible to obtain the designated speed information for the current position of the vehicle, it becomes impossible to control the acceleration or deceleration of the vehicle based on the appropriate designated speed information. An object of the present invention is to avoid control of the acceleration or deceleration of the host vehicle being performed based on inappropriate specified speed information in an area where high-precision map information is not available. [Means for solving the problem]

[0005] In a vehicle control method of one aspect of the present invention, a controller executes the following processes: acquiring a current position of the vehicle; acquiring from a camera an image representing the environment in front of the vehicle; determining whether the current position of the vehicle is within a high-precision map usable area in which high-precision map information is available; and, if it is determined that the current position of the vehicle is within the high-precision map usable area, executing acceleration / deceleration control to control the acceleration or deceleration of the vehicle based on designated speed information acquired by recognizing a speed sign on the captured image or designated speed information acquired from the high-precision map information based on the current position of the vehicle, and notifying the driver of the designated speed information; and, if it is predicted that the vehicle will go outside the high-precision map usable area, terminating the acceleration / deceleration control based on the designated speed information just before the point at which the vehicle will go outside the high-precision map usable area, and acquiring the designated speed information from road map information with a lower accuracy than the high-precision map information based on the current position of the vehicle, and notifying the driver of the designated speed information. Effect of the Invention

[0006] According to the present invention, it is possible to prevent control of the acceleration or deceleration of the host vehicle from being performed based on inappropriate specified speed information in an area where high-precision map information is not available. The objects and advantages of the invention will be realized and attained by means of the elements and combinations recited in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed. [Brief description of the drawings]

[0007] [Figure 1] 1 is a diagram showing an example of a schematic configuration of a vehicle equipped with a driving assistance device according to an embodiment; [Diagram 2] FIG. 2 is a diagram showing a part of the input device of FIG. [Figure 3A] FIG. 2 is a schematic diagram illustrating a high-precision map usable area. [Figure 3B] FIG. 2 is a schematic diagram illustrating a high-precision map usable area. [Figure 4A] 4 is a schematic diagram of an example of a first remaining distance and a second remaining distance. FIG. [Figure 4B] 4 is a schematic diagram of an example of a first remaining distance and a second remaining distance. FIG. [Diagram 5] 4 is a flowchart of an example of a vehicle control method according to an embodiment. [Figure 6] 13 is a flowchart of an example of a termination condition determination process. [Figure 7] 4 is a flowchart of an example of autonomous speed control. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] (composition) 1 is a diagram showing an example of a schematic configuration of a vehicle equipped with a driving support device according to an embodiment. The driving support device 10 equipped in the vehicle 1 includes a sensor 11, a positioning device 12, a high-precision map database (high-precision map DB) 13H, a navigation map database (navigation map DB) 13N, an in-vehicle device 14, a navigation system 15, a display device 16, a voice output device 17, an input device 18, a vehicle behavior control device 19, and a controller 20. These devices are connected to each other by, for example, a controller area network (CAN) or other in-vehicle LAN in order to transmit and receive information to and from each other. The driving support device 10 is an example of a "vehicle control device" described in the claims.

[0009] The sensor 11 detects the traveling state of the host vehicle 1. For example, the sensor 11 includes cameras such as a front camera that captures an image in front of the host vehicle 1, a rear camera that captures an image behind the host vehicle 1, and a side camera that captures an image on the left and right sides of the host vehicle 1. The sensor 11 also includes radars such as a front radar that detects an obstacle in front of the host vehicle 1, a rear radar that detects an obstacle behind the host vehicle 1, and a side radar that detects an obstacle on the left and right sides of the host vehicle 1. The sensor 11 also includes a vehicle speed sensor that detects the speed of the host vehicle 1, a touch sensor (capacitive sensor) that detects the holding of the steering wheel by an occupant (e.g., the driver), and an in-vehicle camera that captures an image of the occupant.

[0010] The positioning device 12 includes a GPS unit, a gyro sensor, a vehicle speed sensor, etc. The positioning device 12 detects radio waves transmitted from a plurality of satellite communications by the GPS unit, and periodically acquires position information of the vehicle 1. The positioning device 12 also detects the current position of the vehicle 1 based on the acquired position information of the vehicle 1, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor.

[0011] The high-precision map DB 13H is a memory that stores three-dimensional high-precision map information including position information of various facilities and specific points, and is accessible from the controller 20. The three-dimensional high-precision map information is three-dimensional map information based on road shapes detected when an actual road is traveled using a data acquisition vehicle. The three-dimensional high-precision map information is map information in which detailed and highly accurate position information such as curved roads and the magnitude of the curve (e.g., curvature or curvature radius), road junctions, branching points, toll gates, and positions where the number of lanes decreases is associated as three-dimensional information along with the map information.

[0012] The three-dimensional high-precision map information has highly detailed shape information and highly accurate position information, and therefore can estimate the own position of the vehicle 1 on the map with high accuracy. The three-dimensional high-precision map information also includes designated speed information indicating a designated speed (e.g., a speed limit such as a maximum speed or a minimum speed, or a recommended speed) designated for each lane. The designated speed information may be, for example, information associated with a road or lane and specifying a designated speed for the associated road or lane, or may be information on the installation position of a speed sign and the designated speed.

[0013] The navigation map DB 13N is a memory that stores navigation map information used by the navigation system 15 described below and is accessible from the navigation system 15 and the controller 20. The navigation map information is map information with lower accuracy than high-precision three-dimensional map information and is an example of the "road map information" described in the claims. The navigation map information includes information on a road-by-road basis. For example, the navigation map information includes, as the information on a road-by-road basis, information on road nodes indicating reference points on road reference lines, and information on road links indicating the section modes of roads between the road nodes. The road node information includes position coordinates, the number of connected road links, and identification numbers of the connected road links. The road link information includes road standards, link lengths, the number of lanes, road widths, and designated speed information. Navigation map information has lower definition of shape information and lower accuracy of position information than three-dimensional high-precision map information. Therefore, the estimation accuracy of the vehicle's own position on the map is lower than that of three-dimensional high-precision map information. In addition, the accuracy of the designated speed information of navigation map information may be lower than that of high-precision map information. For example, since the designated speed information of navigation map information is stored on a road-by-road basis, if different designated speed information is specified for each lane, it may differ from the designated speed information for the lane in which the vehicle 1 is traveling.

[0014] The in-vehicle devices 14 are various devices mounted on the vehicle 1 and are operated by the driver of the vehicle. Examples of such in-vehicle devices include a steering wheel, an accelerator pedal, a brake pedal, a turn signal, wipers, lights, a horn, and other specific switches. The navigation system 15 acquires the current position information of the vehicle 1 from the positioning device 12, and displays the position of the vehicle 1 on a display or the like by superimposing the position of the vehicle 1 on the navigation map information. In addition, when a destination is set, the navigation system 15 has a navigation function of setting a route to the destination on the map of the navigation map information and guiding the occupant along the set route. The route set by the navigation system 15 may be referred to as the "planned driving route." This navigation function displays the planned driving route on a map on the display and informs the occupants of the planned driving route by voice or the like. The planned driving route is also used by a route driving assistance function provided in the controller 20. The route driving assistance function is a function that causes the host vehicle 1 to autonomously drive to the destination based on the planned driving route.

[0015] The display device 16 includes various displays such as a display provided in the navigation system 15, a display built into a rearview mirror, a display built into a meter section, a head-up display projected on the windshield, etc. The display device 16 notifies the occupant of various pieces of presented information under the control of the controller 20. The audio output device 17 is a device that outputs auditory information such as a speaker provided in the navigation system 15, a speaker of an audio device, a buzzer, etc. Under the control of the controller 20, the audio output device 17 notifies the occupant of various pieces of presentation information.

[0016] The input device 18 is, for example, a button switch that allows the occupant to manually input information, a touch panel arranged on a display screen, or a microphone that allows the occupant to input information by voice. By operating the input device 18, the occupant can input setting information for the information presented by the display device 16 and the audio output device 17. 2 is a diagram showing a part of the input device 18 of this embodiment. The input device 18 may be, for example, a group of button switches arranged on the spokes of a steering wheel. The input device 18 is used when setting the on / off of an autonomous driving control function provided in the controller 20. The input device 18 includes a main switch 181, a resume / accelerate switch 182, a set / coast switch 183, a cancel switch 184, a vehicle distance adjustment switch 185, and a lane change assist switch 186.

[0017] The main switch 181 is a switch for turning on / off the autonomous driving control function of the controller 20. The resume / accelerate switch 182 is a switch for setting the autonomous driving control function to resume at the set speed before the autonomous driving control function was turned off after it was turned off, or for increasing the set speed. The set / coast switch 183 is a switch for starting the autonomous driving control function. To start the autonomous driving control function, for example, the autonomous driving control function is turned on by the main switch 181, and then the set / coast switch 183 is pressed. The set / coast switch 183 is also a switch for lowering the set speed. The cancel switch 184 is a switch for canceling the autonomous driving control function. The vehicle distance adjustment switch 185 is a switch for setting the vehicle distance from the preceding vehicle. The lane change assistance switch 186 is a switch for instructing (agreeing to) start lane change when the controller 20 has confirmed with the occupant that the lane change should be started. 2, a turn signal lever of a turn signal or other switches of the in-vehicle device 14 can be used as the input device 18. For example, when the controller 20 suggests whether or not to automatically change lanes, if the occupant operates the turn signal lever, the vehicle will change lanes in the direction in which the turn signal lever was operated, rather than the suggested lane change.

[0018] The vehicle behavior control device 19 controls the vehicle behavior of the host vehicle 1. For example, when the host vehicle 1 travels at a constant speed at a set speed due to the autonomous driving control function, the vehicle behavior control device 19 controls the operation of the drive mechanism and the brake operation to realize the acceleration / deceleration and traveling speed so that the host vehicle 1 reaches the set speed. In addition, the vehicle behavior control device 19 also controls the operation of the drive mechanism and the brake in the same manner when the host vehicle 1 travels following a preceding vehicle due to the autonomous driving control function. Note that the operation control of the drive mechanism includes the operation of the internal combustion engine in an engine vehicle and the operation of the driving motor in an electric vehicle system. In addition, in a hybrid vehicle, it includes the torque distribution between the internal combustion engine and the driving motor. In addition, when the vehicle behavior control device 19 uses the autonomous driving control function to execute lane keeping control, lane change assistance function, overtaking assistance function, or route driving assistance function described below, it performs steering control of the vehicle 1 by controlling the operation of the steering actuator in addition to controlling the operation of the drive mechanism and brakes.

[0019] The controller 20 is one or more electronic control units for controlling the traveling of the host vehicle 1, and includes a processor 21 and peripheral components such as a memory device 22. The processor 21 may be, for example, a central processing unit (CPU) or a micro-processing unit (MPU). The memory device 22 may include a semiconductor memory device, a magnetic memory device, an optical memory device, etc. The memory device 22 may include memories such as a register, a cache memory, a read only memory (ROM) used as a main memory device, and a random access memory (RAM). The functions of the controller 20 described below are realized, for example, by the processor 21 executing a computer program stored in the storage device 22. The controller 20 may be formed of dedicated hardware for executing each information processing described below. For example, the controller 20 may include a functional logic circuit set in a general-purpose semiconductor integrated circuit. For example, the controller 20 may include a programmable logic device (PLD) such as a field programmable gate array (FPGA).

[0020] The controller 20 realizes a driving information acquisition function for acquiring information about the driving state of the host vehicle 1, and an autonomous driving control function for autonomously controlling the driving speed and / or steering of the host vehicle 1. The driving information acquisition function of the controller 20 is a function for acquiring driving information about the driving state of the host vehicle 1. For example, the controller 20 may acquire image information of the outside of the vehicle captured by the front camera, rear camera, and side camera of the sensor 11 as the driving information. The controller 20 also acquires detection results by the front radar, rear radar, and side radar as the driving information. Furthermore, the controller 20 also acquires vehicle speed information of the host vehicle 1 detected by the vehicle speed sensor of the sensor 11 and image information of the face of the occupant captured by the in-vehicle camera as the driving information.

[0021] Furthermore, the controller 20 acquires current position information of the vehicle 1 from the positioning device 12 as the travel information. The controller 20 also acquires a set destination and a planned travel route to the destination from the navigation system 15 as the travel information. The controller 20 also acquires position information such as curved roads and the magnitude of the curve (e.g., curvature or curvature radius), merging points, branching points, toll gates, and positions where the number of lanes is reduced as the travel information from the high-precision map DB 13H and the navigation map DB 13N as the travel information. In addition, the controller 20 acquires operation information of the in-vehicle device 14 by the occupant from the in-vehicle device 14 as the travel information.

[0022] The autonomous driving control function of the controller 20 is a function that autonomously controls the driving of the host vehicle 1 without the operation of the occupant. The autonomous driving control function of the controller 20 includes an autonomous speed control function that autonomously controls the driving speed by controlling the acceleration or deceleration of the host vehicle 1, and an autonomous steering control function that autonomously controls the steering of the host vehicle 1. These autonomous controls are performed based on the high-precision map information of the high-precision map DB 13H. The autonomous control of the driving speed by the autonomous speed control function (hereinafter referred to as "autonomous speed control") is an example of "acceleration / deceleration control" described in the claims. The autonomous speed control function and the autonomous steering control function of this embodiment will be described below. Note that in the present invention, the autonomous driving control function needs to include only the autonomous speed control function, and the autonomous driving control function does not necessarily need to include the autonomous steering control function.

[0023] Autonomous speed control function The autonomous speed control function is a function that, when the vehicle 1 is located within the high-precision map available area Rav, which is an area where high-precision map information can be used, follows the vehicle ahead while performing vehicle distance control to maintain a distance according to the vehicle speed, with the upper limit set to the speed limit of the lane in which the vehicle 1 is traveling or the vehicle speed set by the occupant. When no preceding vehicle is detected, the autonomous speed control function performs constant speed driving at the speed limit of the lane in which the host vehicle 1 is traveling or at a speed set by the occupant. The former is also called inter-vehicle control, and the latter is called constant speed control. Note that, when a recommended speed is set for the lane in which the host vehicle 1 is traveling, constant speed driving may be performed at the recommended speed. In this way, the upper limit vehicle speed that is set when a preceding vehicle is detected, or the target vehicle speed for constant speed driving that is set when no preceding vehicle is detected, may be referred to as the "set vehicle speed."

[0024] 3A and 3B are schematic diagrams for explaining a high-precision map available area Rav. An example of the high-precision map available area Rav is a motorway such as an expressway. For example, the high-precision map available area Rav may include, in addition to the main line Lm of the motorway, a deceleration lane Ld from the main line Lm toward an exit Po of an interchange between the motorway and a general road, and a ramp Lr between the deceleration lane Ld and the exit Po. Furthermore, for example, the high-precision map available area Rav may include a ramp Lr from an entrance Pi of the interchange toward the main line Lm, and an acceleration lane La between the ramp Lr and the main line Lm. Below, an example of a highway as shown in Figures 3A and 3B will be described as an example of the high-precision map available area Rav. However, the high-precision map available area Rav is not limited to a highway, and may be any area where high-precision map information can be used.

[0025] When the set / coast switch 183 is pressed after the autonomous driving control function is turned on by the main switch 181, the controller 20 determines whether the current position of the vehicle 1 measured by the positioning device 12 is within the high-precision map available area Rav. When the current position of the vehicle 1 is within the high-precision map usable area Rav, the controller 20 executes the autonomous speed control. When the current position of the vehicle 1 is not within the high-precision map usable area Rav, the controller 20 does not execute the autonomous speed control. The controller 20 may start the autonomous speed control when the current position of the vehicle 1 moves from outside to inside the high-precision map usable area Rav. In the autonomous speed control, the controller 20 recognizes speed signs from the image captured by the camera of the sensor 11, obtains designated speed information of a designated speed (e.g., a speed limit or a recommended speed) designated for the lane in which the vehicle is traveling, or obtains designated speed information from high-precision map information in the high-precision map DB 13H, and sets the set vehicle speed based on the designated speed. The method of recognizing the designated speed will be described later.

[0026] The constant speed control is executed when the forward radar of the sensor 11 or the like detects that there is no preceding vehicle ahead in the own lane. In the constant speed control, the vehicle behavior control device 19 controls the operation of the drive mechanisms such as the engine and brakes while feeding back the vehicle speed data from the vehicle speed sensor so as to maintain the set vehicle speed. The vehicle distance control is executed when the forward radar of the sensor 11 detects the presence of a preceding vehicle ahead in the own lane. In the vehicle distance control, the vehicle speed is limited to a set vehicle speed or less, and the operation of the drive mechanisms such as the engine and brakes is controlled by the vehicle behavior control device 19 while feeding back the vehicle distance data detected by the forward radar so as to maintain the set vehicle distance.

[0027] Autonomous steering control function The autonomous steering control function is a function that controls the operation of a steering actuator based on high-precision map information to execute steering control of the host vehicle 1. The autonomous steering control function includes, for example, a lane keeping function, a lane change assist function, an overtaking assist function, and a route driving assist function. The lane keeping function is a function that supports the driver's steering operation by controlling the steering actuator so that the vehicle travels near the center of the lane. For example, when the set / coast switch 183 is pressed after the autonomous driving control function is turned on by the main switch 181, the controller 20 determines whether or not a predetermined autonomous driving control start condition is satisfied. When it is determined that the autonomous driving control start condition is satisfied, the controller 20 executes the lane keeping function of the autonomous steering control function.

[0028] Lane change assistance function The lane change assist function turns on the turn signal when the occupant operates the turn signal lever, and when a predetermined lane change start condition is met, starts a lane change operation, which is a series of processes for changing lanes in an automobile. The lane change assist function determines whether a predetermined lane change start condition is met based on various driving information acquired by the driving information acquisition function. The lane change assist function starts a lane change operation when the lane change start condition is met. In the lane change operation, the vehicle 1 is moved laterally to an adjacent lane, and when the movement to the adjacent lane is completed, the turn signal is turned off and the lane keeping function in the adjacent lane is started.

[0029] Overtaking Assistance Function The overtaking support function presents overtaking information to the occupant via the display device 16 when there is a preceding vehicle slower than the vehicle 1 ahead in the vehicle lane and when a predetermined overtaking suggestion condition is satisfied. Here, the overtaking information is information for suggesting to the occupant to overtake the preceding vehicle. When the occupant accepts the overtaking information presented by operating the lane change support switch 186 of the input device 18 and a preset overtaking start condition is satisfied, the overtaking support function turns on the turn signal and starts the above-mentioned lane change operation. The overtaking support function judges whether the overtaking suggestion condition and the overtaking start condition are satisfied based on various driving information acquired by the driving information acquisition function.

[0030] Route driving support function The route driving assistance function presents route driving information on the display device 16 and suggests a lane change to the driving direction change point when a branch point, junction point, exit, toll gate, or other driving direction change point exists on the planned driving route, the distance to the driving direction change point is within a predetermined distance, and predetermined route driving suggestion conditions are satisfied. In addition, the route driving assistance function starts a lane change operation when the lane change suggestion is accepted by operating the lane change assistance switch 186 and predetermined route driving start conditions are satisfied. The route driving assistance function determines whether or not the route driving suggestion conditions and the route driving start conditions are met based on various driving information acquired by the driving information acquisition function.

[0031] <How to recognize the specified speed> Next, a method of recognizing the designated speed by the controller 20 will be described. The controller 20 acquires information on the current position of the vehicle 1 measured by the positioning device 12 as driving information. Also, the controller 20 acquires an image showing the environment in front of the vehicle 1 from the camera of the sensor 11. The controller 20 judges whether or not the current position of the vehicle 1 is within the high-precision map available area Rav. For example, the controller 20 may judge that the current position of the vehicle 1 is within the high-precision map available area Rav when high-precision map information on the current position of the vehicle 1 can be acquired from the high-precision map DB 13H. Also, position information of an area for which high-precision map information is available may be stored in the high-precision map DB 13H. Whether or not the current position of the vehicle 1 is within the high-precision map available area Rav can be judged by various methods. When the current position of the vehicle 1 is within the high-precision map available area Rav, the controller 20 recognizes a speed sign on the image captured by the camera of the sensor 11 and acquires designated speed information designated for the lane in which the vehicle is traveling. Alternatively, the controller 20 acquires designated speed information for the lane in which the vehicle is traveling from high-precision map information in the high-precision map DB 13H based on the current position of the vehicle 1.

[0032] For example, when the controller 20 recognizes a speed sign on an image captured by the camera, the controller 20 may acquire the speed designated by the speed sign as designated speed information. When a speed sign is no longer recognized on an image captured by the camera, the controller 20 may use the designated speed information previously acquired from the image captured by the camera as the designated speed for the lane in which the vehicle is traveling until a predetermined time has elapsed since the speed sign was no longer recognized (or until the vehicle 1 has traveled a predetermined distance). When a predetermined time has elapsed since the speed sign was no longer recognized (or until the vehicle 1 has traveled a predetermined distance), the controller 20 may acquire the designated speed information for the lane in which the vehicle is traveling from the high-precision map information based on the current position of the vehicle 1.

[0033] As described above, when the current position of the vehicle 1 is within the high-precision map available area Rav, the designated speed information acquired from the image captured by the camera or the high-precision map information is used as a set vehicle speed for autonomous speed control by the controller 20. In addition, the controller 20 notifies the acquired designated speed information to the occupant. For example, the controller 20 may output the designated speed information via the display device 16 or the audio output device 17. On the other hand, when the current position of the vehicle 1 is outside the high-precision map usable area Rav (for example, when the vehicle 1 is traveling on a general road), the controller 20 acquires the designated speed information of the road on which the vehicle is traveling from the navigation map information of the navigation map DB 13N based on the current position of the vehicle 1. Alternatively, the controller 20 acquires the designated speed information of the road on which the vehicle is traveling by recognizing a speed sign on an image captured by the camera of the sensor 11. The controller 20 notifies the occupant of the acquired designated speed information. For example, the controller 20 may output the designated speed information via the display device 16 or the audio output device 17.

[0034] When the current position of the vehicle 1 moves from inside to outside the high-precision map usable area Rav, the controller 20 switches the map information from which the specified speed information is obtained from the high-precision map information in the high-precision map DB 13H to the navigation map information in the navigation map DB 13N, and terminates the autonomous speed control. At that time, the point where the vehicle 1 leaves the high-precision map usable area Rav (for example, 3 If the autonomous speed control is terminated at or immediately before the exit Po of A, there is a risk that inappropriate designated speed information will be set as the set speed and autonomous speed control will be performed.

[0035] For example, while the vehicle 1 is traveling on the ramp Lr on the way to the exit Po, the camera of the sensor 11 faces various directions and may erroneously recognize a speed sign of a lane different from the lane the vehicle 1 is traveling in. In this case, as described above, the controller 20 uses the designated speed information recognized from the speed sign in the captured image as the designated speed until a predetermined time has elapsed (or until the vehicle 1 has traveled a predetermined distance), so there is a risk that autonomous speed control will be performed based on the erroneous designated speed information until a predetermined time has elapsed (or until the vehicle 1 has traveled a predetermined distance). Furthermore, even when the designated speed information is obtained from the high-precision map information of the high-precision map DB 13H, there is a risk that the designated speed information for the ramp way Lr may be erroneously stored as the same designated speed information as that for the main line Lm.

[0036] Therefore, when the controller 20 predicts that the vehicle 1 will go outside the high-precision map usable area Rav, the controller 20 ends the autonomous speed control based on the specified speed information before the point where the vehicle 1 goes outside the high-precision map usable area Rav. Then, the controller 20 starts a process of acquiring the specified speed information from the navigation map information with lower accuracy than the high-precision map information based on the current position of the vehicle 1 and notifying the driver of the information. Hereinafter, the point where the vehicle 1 goes outside the high-precision map usable area Rav may be referred to as the "planned entrance point." For example, when a planned driving route is set in the navigation system 15 (i.e., when a destination is set), the controller 20 may predict that the vehicle 1 will leave the high-precision map usable area Rav if the planned driving route leaves the high-precision map usable area Rav, and may determine that the point where the planned driving route leaves the high-precision map usable area Rav is the planned entrance point. Also, for example, when a planned driving route has not been set (i.e., when a destination has not been set), the controller 20 may predict that the vehicle 1 will leave the high-precision map usable area Rav if the driving lane in which the vehicle 1 is currently traveling leaves the high-precision map usable area Rav ahead of the vehicle 1, and may determine that the point where the driving lane leaves the high-precision map usable area Rav is the planned entry point.

[0037] For example, in the example of Figure 3A, the controller 20 may predict whether the vehicle 1 will exit from an exit Po of a highway, thereby predicting whether the vehicle 1 will exit outside the high-precision map usable area Rav, and determine that the exit Po is the planned entry point. For example, when a planned driving route is set, if the planned driving route is a route that exits from an exit Po of a motorway, the controller 20 may predict that the host vehicle 1 will exit from the exit Po. When a planned driving route is not set, the controller 20 may predict that the host vehicle 1 will exit from the exit Po when the host vehicle 1 is traveling in the deceleration lane Ld toward the exit Po, or in the ramp Lr between the deceleration lane Ld and the exit Po, or when the host vehicle 1 is changing lanes to the deceleration lane Ld. In addition, even if the high-precision map information is stored in the high-precision map DB 13H, if there is a prohibited area where the use of the high-precision map information is prohibited due to construction or other reasons, it may be predicted that the planned travel route or the travel lane of the vehicle 1 will go outside the high-precision map usable area Rav when it passes through the prohibited area.

[0038] When it is predicted that the vehicle 1 will go outside the high-precision map usable area Rav, the controller 20 ends the autonomous speed control at a point Pc before the planned entry point (i.e., a point closer to the current position of the vehicle 1 than the planned entry point) and starts notifying the driver of the designated speed information acquired from the navigation map information. Hereinafter, the point Pc is referred to as a "switching point Pc." The switching point Pc may be, for example, a point a predetermined distance Dp before the point (planned entry point) where the vehicle 1 goes outside the high-precision map usable area Rav. The predetermined distance Dp may be set to, for example, a distance (for example, 100 [m]) at which a speed sign can be recognized from an image captured by the camera of the sensor 11. Also, for example, the switching point Pc may be a point at which the driving time of the vehicle 1 to the planned entry point becomes a predetermined time.

[0039] When determining whether the host vehicle 1 has reached the switching point Pc, the controller 20 of this embodiment calculates a first remaining distance D1, which is a distance that the host vehicle 1 can travel without changing lanes, by an autonomous travel control function based on high-precision map information. The controller 20 also calculates a second remaining distance D2, which is the distance between the end of the planned travel route on the high-precision map and the current position of the host vehicle 1. The controller 20 determines that the host vehicle 1 has reached the switching point Pc when the difference between the first remaining distance D1 and the second remaining distance D2 is equal to or less than a threshold value and the first remaining distance D1 or the second remaining distance D2 is equal to or less than a predetermined distance Dp. The controller 20 may determine that the host vehicle 1 has reached the switching point Pc when both the first remaining distance D1 and the second remaining distance D2 are equal to or less than the predetermined distance Dp.

[0040] 4A and 4B are schematic diagrams of an example of the first remaining distance D1 and the second remaining distance D2 when the planned travel route is a route that leaves from the exit Po. The dashed and dotted line indicates a route that the vehicle 1 can travel without changing lanes by the autonomous travel control function based on the high-precision map information. The dashed and dotted line indicates a route to the end point of the planned travel route on the high-precision map, that is, a route from the current position of the vehicle 1 to the exit Po.

[0041] 4A, when the vehicle 1 is on the main line Lm, the route that the vehicle 1 can travel without changing lanes by the autonomous driving control function based on the high-precision map information is different from the route from the current position of the vehicle 1 to the exit Po. Therefore, the difference between the first remaining distance D1 and the second remaining distance D2 becomes large. On the other hand, as shown in Fig. 4B, when the host vehicle 1 changes lanes to the deceleration lane Ld, the end point of the route that the host vehicle 1 can travel without changing lanes due to the autonomous driving control function based on the high-precision map information is the exit Po. Therefore, the first remaining distance D1 becomes almost equal to the second remaining distance D2. Therefore, the controller 20 can accurately predict that the host vehicle 1 is about to exit the exit Po when the difference between the first remaining distance D1 and the second remaining distance D2 becomes equal to or less than the threshold value.

[0042] In this manner, by making a judgment based on a comparison between the first remaining distance D1 and the second remaining distance D2, it is possible to accurately determine whether or not the vehicle 1 has reached the switching point Pc just before the planned entry point (exit Po in the example of Figure 3A) where the vehicle 1 will exit outside the high-precision map usable area Rav. For example, if it is determined that the vehicle 1 has reached the switching point Pc based solely on whether the second remaining distance D2 is less than or equal to the predetermined distance Dp, if the destination of the planned route is set to a location such as a service area on a motorway, when the vehicle 1 enters the service area, it will be erroneously determined that the vehicle 1 has reached the switching point Pc, and the autonomous speed control based on the specified speed information will be canceled. The controller 20 of this embodiment is configured to determine that the switching point Pc has been reached only if the difference between the first remaining distance D1 and the second remaining distance D2 is equal to or less than a threshold value. When the destination is set to a service area as described above, the calculation result of the first remaining distance D1 differs from the second remaining distance D2, so that it is possible to avoid erroneously determining that the switching point Pc has been reached.

[0043] Conversely, when the current position of the vehicle 1 changes from outside to inside the high-precision map available area Rav, the controller 20 stops notifying the driver of the designated speed information acquired from the navigation map information of the navigation map DB 13N at the time when the current position of the vehicle 1 changes from outside to inside the high-precision map available area Rav, and switches the map information from which the designated speed information is acquired from the navigation map information to the high-precision map information of the high-precision map DB 13H. Then, the controller 20 starts autonomous speed control based on the designated speed information, and starts processing to notify the driver of the designated speed information acquired from the image captured by the camera or the high-precision map information.

[0044] (operation) FIG. 5 is a flowchart of an example of a vehicle control method according to the embodiment. In step S1, the controller 20 acquires information on the current position of the host vehicle 1 from the positioning device 12. In step S2, the controller 20 acquires from the camera of the sensor 11 a captured image showing the environment in front of the host vehicle 1. In step S3, the controller 20 judges whether the current position of the vehicle 1 has entered the high-precision map usable area Rav from outside to inside. If the current position of the vehicle 1 has entered the high-precision map usable area Rav from outside to inside (step S3: Y), the process proceeds to step S7. If the current position of the vehicle 1 has entered the high-precision map usable area Rav from outside to inside (step S3: N), the process proceeds to step S4.

[0045] In step S4, the controller 20 acquires designated speed information from the navigation map information based on the current position of the vehicle 1. In step S5, the controller 20 notifies the occupant of the designated speed information acquired in step S4. In step S6, the controller 20 determines whether the vehicle 1 has arrived at the destination. If the vehicle 1 has not arrived at the destination (step S6: N), the process returns to step S1. If the vehicle 1 has arrived at the destination (step S6: Y), the process ends.

[0046] On the other hand, in step S7, the controller 20 executes an end condition determination process for determining whether or not an end condition for the autonomous speed control is satisfied. Fig. 6 is a flowchart of an example of the end condition determination process. In step S20, the controller 20 calculates a first remaining distance D1. In step S21, the controller 20 calculates a second remaining distance D2. In step S22, the controller 20 determines whether the difference |D2-D1| is equal to or less than the threshold. If the difference |D2-D1| is equal to or less than the threshold (step S22: Y), the process proceeds to step S24. If the difference |D2-D1| is not equal to or less than the threshold (step S22: N), the process proceeds to step S23. In step S23, the controller 20 determines that the end condition is not satisfied, and the end condition determination process then ends.

[0047] In step S24, the controller 20 determines whether the first remaining distance D1 is equal to or shorter than the predetermined distance Dp. The controller 20 may determine whether the second remaining distance D2 is equal to or shorter than the predetermined distance Dp. If the first remaining distance D1 is longer than the predetermined distance Dp or if the second remaining distance D2 is longer than the predetermined distance Dp (step S24: N), the process proceeds to step S23. If the first remaining distance D1 is equal to or shorter than the predetermined distance Dp or if the second remaining distance D2 is equal to or shorter than the predetermined distance Dp (step S24: Y), the process proceeds to step S25. In step S25, the controller 20 determines that the end condition is met, and then the end condition determination process ends.

[0048] Please refer to Fig. 5. If the termination condition is satisfied (step S8: Y), the process proceeds to step S4. If the autonomous speed control has been started, the process proceeds to step S4, whereby the autonomous speed control is terminated. If the termination condition is not satisfied (step S8: N), the process proceeds to step S9. In step S9, the controller 20 executes autonomous speed control. FIG. 7 is a flowchart of an example of the autonomous speed control. In step S30, the controller 20 judges whether or not a speed sign is recognized from the captured image of the camera. If a speed sign is not recognized from the captured image (step S30: N), the process proceeds to step S32. If a speed sign is recognized from the captured image (step S30: Y), the process proceeds to step S31.

[0049] In step S31, the controller 20 acquires designated speed information for the lane the vehicle is traveling in by recognizing a speed sign from a captured image. After that, the process proceeds to step S34. In step S32, the controller 20 determines whether a predetermined time has passed since the designated speed information was previously acquired from the captured image. Alternatively, the controller 20 may determine whether the vehicle 1 has traveled a predetermined distance since the designated speed information was previously acquired from the captured image. If the predetermined time has not passed (or the vehicle 1 has not yet traveled the predetermined distance) (step S32: N), the process proceeds to step S34. In this case, the designated speed information previously acquired from the captured image continues to be used.

[0050] When a predetermined time has elapsed (or when the vehicle 1 has traveled a predetermined distance), the process proceeds to step S33. In step S33, the controller 20 acquires designated speed information from high-precision map information based on the current position of the vehicle 1. After that, the process proceeds to step S34. In step S34, the controller 20 controls the acceleration or deceleration of the host vehicle 1 based on the specified speed information. After that, the process proceeds to step S10 in FIG. See Fig. 5. In step S10, the controller 20 notifies the occupant of the designated speed information acquired in the autonomous speed control in step S9. After that, the process returns to step S7.

[0051] (Effects of the embodiment) (1) The controller 20 executes the following processes: acquiring a current position of the vehicle 1; acquiring from the camera an image representing the environment ahead of the vehicle 1; determining whether the current position of the vehicle 1 is within the high-precision map usable area Rav in which high-precision map information is available; if it is determined that the current position of the vehicle 1 is within the high-precision map usable area Rav, executing acceleration / deceleration control to control the acceleration or deceleration of the vehicle 1 based on designated speed information acquired by recognizing a speed sign on the captured image or designated speed information acquired from the high-precision map information based on the current position of the vehicle 1, and notifying the driver of the designated speed information; if it is predicted that the vehicle 1 will go outside the high-precision map usable area Rav, terminating the acceleration / deceleration control based on the designated speed information just before the point at which the vehicle 1 goes outside the high-precision map usable area Rav, and acquiring the designated speed information from road map information with a lower accuracy than the high-precision map information based on the current position of the vehicle 1, and notifying the driver of the designated speed information. This makes it possible to avoid acceleration / deceleration control being performed based on inappropriate designated speed information in an area where high-precision map information is unavailable, such as outside the high-precision map available area Rav. For example, in an area where high-precision map information is unavailable, when a speed sign continues to be unrecognized from an image captured by a camera and designated speed information for the vehicle's current position cannot be obtained, it is possible to avoid acceleration / deceleration control being performed based on the designated speed information.

[0052] (2) When the distance to the point where the vehicle 1 exits the high-precision map usable area Rav decreases to a predetermined distance Dp, the controller 20 may terminate the acceleration / deceleration control based on the specified speed information and notify the driver of the specified speed information obtained from the road map information. This prevents the behavior of the vehicle 1 from becoming unstable immediately before the end of acceleration / deceleration control, which is caused by the camera mistakenly recognizing a speed sign in a lane different from the lane the vehicle 1 is traveling in immediately before going outside the high-precision map usable area Rav.

[0053] (3) The predetermined distance Dp may be a distance at which a speed sign can be recognized from an image captured by a camera, for example, so that it is possible to avoid acquiring specified speed information from a speed sign outside the high-precision map usable area Rav.

[0054] (4) When the current position of the vehicle 1 moves from outside to inside the high-precision map usable area Rav, the controller 20 may terminate the notification of the specified speed information obtained from the road map information and start acceleration / deceleration control based on the specified speed information obtained from the high-precision map information or the captured image. This makes it possible to obtain accurate specified speed information at an early stage when high-precision map information becomes available and use it for acceleration / deceleration control.

[0055] (5) When the controller 20 is unable to acquire the designated speed information from the captured image when the current position of the vehicle 1 is within the high-precision map usable area Rav, the controller 20 may continue to execute acceleration / deceleration control based on the designated speed information most recently acquired from the captured image while the vehicle 1 travels a specified time or a specified distance after the controller 20 is unable to acquire the designated speed information. In this way, if the specified speed information obtained immediately before is continued to be used until a predetermined time has elapsed or the vehicle 1 has traveled a predetermined distance, if incorrect specified speed information is obtained from the captured image, acceleration / deceleration control will continue based on the incorrect specified speed information until a predetermined time has elapsed or the vehicle 1 has traveled a predetermined distance. By terminating acceleration / deceleration control based on the specified speed information at a point Pc before the point where the host vehicle 1 goes outside the high-precision map usable area Rav, it is possible to avoid continuing acceleration / deceleration control based on the specified speed information obtained by recognizing, by a camera, a speed sign in a lane different from the lane in which the host vehicle 1 is traveling just before going outside the high-precision map usable area Rav.

[0056] All examples and conditional terms described herein are intended for educational purposes to help the reader understand the present invention and the concepts provided by the inventor for the advancement of technology, and should be interpreted without being limited to the above specifically described examples and conditions, and the configuration of the examples in this specification with respect to showing the advantages and disadvantages of the present invention. Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and modifications can be made thereto without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0057] 1... host vehicle, 10... driving assistance device, 11... sensor, 12... positioning device, 13H... high-precision map DB, 13N... navigation map DB, 14... in-vehicle equipment, 15... navigation system, 16... display device, 17... audio output device, 18... input device, 19... vehicle behavior control device, 20... controller, 21... processor, 22... storage device

Claims

1. A process of acquiring a current position of the vehicle; A process of acquiring an image representing an environment in front of the host vehicle from a camera; A process of determining whether or not the current position of the vehicle is within a high-precision map available area in which high-precision map information is available; a process of executing an acceleration / deceleration control for controlling an acceleration or deceleration of the host vehicle based on designated speed information acquired by recognizing a speed sign on the captured image or designated speed information acquired from the high-precision map information based on the current position of the host vehicle, when the current position of the host vehicle is determined to be within the high-precision map usable area, and notifying a driver of the designated speed information; a process of terminating the acceleration / deceleration control based on the specified speed information before a point at which the host vehicle will go outside the high-precision map usable area when it is predicted that the host vehicle will go outside the high-precision map usable area, and switching the specified speed information to specified speed information obtained from road map information having lower accuracy than the high-precision map information based on a current position of the host vehicle before a point at which the host vehicle will go outside the high-precision map usable area, and notifying the driver of the specified speed information; A vehicle control method comprising: causing a controller to execute the above steps.

2. 2. The vehicle control method according to claim 1, wherein the controller terminates the acceleration / deceleration control based on the specified speed information when a distance to a point where the vehicle exits the high-precision map usable area decreases to a predetermined distance, and notifies the driver of the specified speed information obtained from the road map information.

3. 3. The vehicle control method according to claim 2, wherein the predetermined distance is a distance at which a speed sign can be recognized from an image captured by the camera.

4. the controller terminates the notification of the designated speed information acquired from the road map information when the current position of the vehicle moves from outside to inside the high-precision map usable area, and starts the acceleration / deceleration control based on the designated speed information acquired from the high-precision map information or the captured image.

4. The vehicle control method according to claim 1, wherein the vehicle is driven in a vehicle-controlled manner.

5. The vehicle control method according to any one of claims 1 to 4, characterized in that when the specified speed information cannot be obtained from the captured image when the current position of the vehicle is within the high-precision map usable area, the acceleration / deceleration control based on the specified speed information most recently obtained from the captured image is continuously executed while the vehicle travels a predetermined time or a predetermined distance after the specified speed information can no longer be obtained.

6. A camera that captures an image of the environment in front of the vehicle; a controller that executes the following processes: acquiring a current position of the host vehicle; acquiring from the camera an image representing an environment ahead of the host vehicle; determining whether or not the current position of the host vehicle is within a high-precision map usable area in which high-precision map information is available; when it is determined that the current position of the host vehicle is within the high-precision map usable area, executing acceleration / deceleration control to control an acceleration or deceleration of the host vehicle based on designated speed information acquired by recognizing a speed sign on the captured image or designated speed information acquired from the high-precision map information based on the current position of the host vehicle, and notifying a driver of the designated speed information; and when it is predicted that the host vehicle will go outside the high-precision map usable area, ending the acceleration / deceleration control based on the designated speed information before a point at which the host vehicle goes outside the high-precision map usable area, and switching the designated speed information to designated speed information acquired from road map information having lower accuracy than the high-precision map information based on the current position of the host vehicle, before a point at which the host vehicle goes outside the high-precision map usable area, and notifying the driver of the designated speed information. A vehicle control device comprising:

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