JP7571471B2 - Vehicle driving control method and driving control device - Google Patents

Description

The present invention relates to a vehicle driving control method and a driving control device.

A vehicle driving control device is known that, when performing lane change control using autonomous driving control, if it is determined that it would be better to cancel the lane change due to a sudden change in the driving conditions of other vehicles, cancels the lane change control and regenerates a target route for returning to the original lane (Patent Document 1).

JP 2018-158684 A

However, when regenerating a target route to return to the original lane while lane change control is being performed, it is necessary to detect and calculate the situation of other vehicles traveling in the original lane at that time again. As a result, there may be situations that are difficult to handle with autonomous driving control, such as when it is not possible to maintain a sufficient distance from other vehicles.

The problem that this invention aims to solve is to provide a vehicle driving control method and driving control device that can maintain a sufficient distance from other vehicles when changing lanes using autonomous driving control and then stopping the lane change and returning to the original lane.

The present invention solves the above problem by estimating the distance between the vehicle and another vehicle traveling in the original lane before starting a lane change, assuming that the vehicle stops changing lanes midway and returns to the original lane, and prohibits the vehicle from changing lanes when this distance falls below a predetermined value.

According to the present invention, when the vehicle stops changing lanes and returns to the original lane, the vehicle can maintain a safe distance from other vehicles.

1 is a block diagram showing an embodiment of a vehicle cruise control device according to the present invention; FIG. 2 is a front view showing a part of the input device of FIG. 1 . 2 is a plan view showing an example of lane change control of the driving control device of FIG. 1; FIG. 2 is a plan view (part 1) showing an example of lane change control of the control device of FIG. 1 . FIG. 2 is a plan view (part 2) showing an example of lane change control of the control device of FIG. 1 . FIG. 2 is a plan view (part 3) showing an example of lane change control of the control device of FIG. 1 . FIG. 4 is a plan view (part 4) showing an example of lane change control of the control device of FIG. 1 . 4 is a time chart showing an example of a speed profile when the control device of FIG. 1 performs lane change control. FIG. 2 is a block diagram showing state transitions of the control device of FIG. 1 . 4 is a flowchart showing an example of a driving control process executed by the control device of FIG. 1 (part 1); 4 is a flowchart showing an example of a driving control process executed by the control device of FIG. 1 (part 2); 10 is a flowchart showing an example of a driving control process executed by the control device of FIG. 1 (part 3);

Configuration of the driving control device
An embodiment of the present invention will now be described with reference to the drawings. Fig. 1 is a block diagram showing the configuration of a vehicle cruise control device 1 according to this embodiment. The cruise control device 1 of this embodiment is also an embodiment for carrying out a vehicle cruise control method according to the present invention.

As shown in FIG. 1, the driving control device 1 of this embodiment includes a sensor 11, a vehicle position detection device 12, a map database 13, in-vehicle equipment 14, a navigation device 15, a presentation device 16, an input device 17, a drive control device 18, and a control device 19. These devices are connected, for example, by a CAN (Controller Area Network) or other in-vehicle LAN, and can send and receive information between them.

The sensor 11 detects the driving state of the vehicle. For example, the sensor 11 may be a forward camera that captures an image in front of the vehicle, a rearward camera that captures an image behind the vehicle, a forward radar that detects obstacles in front of the vehicle, a rearward radar that detects obstacles behind the vehicle, a side radar that detects obstacles on the left and right sides of the vehicle, a vehicle speed sensor that detects the vehicle speed, a touch sensor (capacitive sensor) that detects whether the driver is holding the steering wheel, and an in-vehicle camera that captures an image of the driver. The sensor 11 may be configured to use one of the above-mentioned multiple sensors, or may be configured to use a combination of two or more types of sensors. The detection results of the sensor 11 are output to the control device 19 at predetermined time intervals.

The vehicle position detection device 12 includes a GPS unit, a gyro sensor, a vehicle speed sensor, and the like. The vehicle position detection device 12 detects radio waves transmitted from multiple satellite communications by the GPS unit, and periodically acquires position information of the target vehicle (the vehicle itself). The vehicle position detection device 12 also detects the current position of the target vehicle based on the acquired position information of the target vehicle, angle change information acquired from the gyro sensor, and vehicle speed acquired from the vehicle speed sensor. The position information of the target vehicle detected by the vehicle position detection device 12 is output to the control device 19 at predetermined time intervals.

The map database 13 is a memory that stores three-dimensional high-precision map information including the position information of various facilities and specific points, and is accessible from the control device 19. The three-dimensional high-precision map information is three-dimensional map information based on the road shape detected when an actual road is driven on using a data acquisition vehicle. The three-dimensional high-precision map information is map information that associates 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, as well as map information, as three-dimensional information.

The in-vehicle devices 14 are various devices mounted on the vehicle and are operated by the driver. Such in-vehicle devices include the steering wheel, accelerator pedal, brake pedal, turn signals, wipers, lights, the horn, and other specific switches. When the in-vehicle devices 14 are operated by the driver, they output operation information to the control device 19.

The navigation device 15 obtains the current position information of the vehicle from the vehicle position detection device 12, and displays the vehicle's position on a display or the like by overlaying it on map information for guidance. The navigation device 15 also has a navigation function that, when the driver inputs a destination, calculates a route to the destination and guides the driver along the set route. With this navigation function, the navigation device 15 displays the route to the destination on the map on the display, and notifies the driver of recommended driving behavior along the route by voice or the like.

The presentation device 16 includes various displays such as a display provided in the navigation device 15, a display built into the rearview mirror, a display built into the meter section, and a head-up display projected on the windshield. The presentation device 16 also includes devices other than displays, such as speakers in an audio device and a seat device with an embedded vibrator. The presentation device 16 notifies the driver of various presentation information according to the control of the control device 19.

The input device 17 is, for example, a button switch that allows input by manual operation by the driver, a touch panel arranged on a display screen, or a microphone that allows input by the driver's voice. In this embodiment, the driver can input setting information for the presentation information presented by the presentation device 16 by operating the input device 17. Figure 2 is a front view showing a part of the input device 17 of this embodiment, and shows an example consisting of a group of button switches arranged on the spokes of a steering wheel, etc.

The illustrated input device 17 is a button switch used to set the ON/OFF of the autonomous driving control function (autonomous speed control function and autonomous steering control function) of the control device 19. The input device 17 in this embodiment includes a main switch 171, a resume/accelerate switch 172, a set/coast switch 173, a cancel switch 174, a vehicle distance adjustment switch 175, and a lane change assistance switch 176.

The main switch 171 is a switch for turning on/off the power supply of the system that realizes the autonomous speed control function and the autonomous steering control function of the control device 19. The resume/accelerate switch 172 is a switch for restarting the autonomous speed control function at the set speed before the autonomous speed control function was stopped (OFF), increasing the set speed, or following the preceding vehicle and stopping, and then restarting it by the control device 19. The set/coast switch 173 is a switch for starting the autonomous speed control function at the traveling speed, or for lowering the set speed. The cancel switch 174 is a switch for turning off the autonomous speed control function. The vehicle distance adjustment switch 175 is a switch for setting the distance between the preceding vehicle and the preceding vehicle, and is a switch for selecting one of multiple settings such as short distance, medium distance, and long distance. The lane change support switch 176 is a switch for instructing (agreeing to) the start of lane change when the control device 19 confirms with the driver that the lane change should be started. After agreeing to start a lane change, the driver can cancel the agreement to the lane change suggestion made by the control device 19 by pressing the lane change assistance switch 176 for longer than a specified period of time.

In addition to the button switches shown in FIG. 2, the turn signal lever of the turn signal or other switches of the in-vehicle equipment 14 can be used as the input device 17. For example, when the control device 19 suggests whether to change lanes through autonomous control, the driver can turn on the turn signal switch to input consent or permission to the lane change. Also, when the control device 19 suggests whether to change lanes through autonomous control, the driver can operate the turn signal lever to change lanes in the direction in which the turn signal lever is operated, rather than the proposed lane change. The setting information input by the input device 17 is output to the control device 19.

The drive control device 18 controls the running of the host vehicle. For example, when the host vehicle runs at a constant speed at a set speed due to the autonomous speed control function, the drive control device 18 controls the operation of the drive mechanism (including the operation of the internal combustion engine in an engine vehicle, the operation of the driving motor in an electric vehicle system, and the torque distribution between the internal combustion engine and the driving motor in a hybrid vehicle) and the brake operation in order to accelerate and decelerate the host vehicle to the set speed, and to maintain the running speed. In addition, when the host vehicle runs following a preceding vehicle due to the autonomous speed control function, the drive control device 18 controls the operation of the drive mechanism and the brake operation to achieve the acceleration/deceleration and running speed so that the distance between the host vehicle and the preceding vehicle is constant.

The drive control device 18 also controls the operation of the steering actuator in addition to the operation control of the drive mechanism and brakes described above using the autonomous steering control function, thereby performing steering control of the host vehicle. For example, when performing lane keeping control using the autonomous steering control function, the drive control device 18 detects lane markers of the host vehicle's lane and controls the host vehicle's running position in the width direction so that the host vehicle runs at a predetermined position within the host lane. When performing lane change assistance using the lane change assistance function described later, the drive control device 18 controls the host vehicle's running position in the width direction so that the host vehicle changes lanes. Furthermore, when performing right/left turn assistance using the autonomous steering control function, the drive control device 18 performs running control to turn right or left at an intersection or the like. The drive control device 18 controls the running of the host vehicle according to instructions from the control device 19 described later. Other known methods can also be used as running control methods by the drive control device 18.

The control device 19 includes a ROM (Read Only Memory) that stores a program for controlling the traveling of the vehicle, a CPU (Central Processing Unit) that executes the program stored in the ROM, and a RAM (Random Access Memory) that functions as an accessible storage device. Note that, as the operating circuit, an MPU (Micro Processing Unit), a DSP (Digital Signal Processor), an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), etc. can be used instead of or in addition to the CPU (Central Processing Unit).

<Functions Realized by the Control Device 19>
The control device 19 executes a program stored in the ROM by the CPU, thereby realizing a driving information acquisition function for acquiring information regarding the driving state of the vehicle, a driving scene determination function for determining the driving scene of the vehicle, and an autonomous driving control function for autonomously controlling the driving speed and/or steering of the vehicle. Each function of the control device 19 will be described below.

The driving information acquisition function of the control device 19 is a function that allows the control device 19 to acquire driving information related to the driving state of the vehicle. For example, the control device 19 acquires image information of the outside of the vehicle captured by the front camera, rear camera, and side camera of the sensor 11 as driving information. The control device 19 also acquires the detection results of the front radar, rear radar, and side radar as driving information. Furthermore, the control device 19 also acquires vehicle speed information of the vehicle detected by the vehicle speed sensor of the sensor 11 and image information of the driver's face captured by the in-vehicle camera as driving information.

Furthermore, the control device 19 acquires the current position information of the vehicle from the vehicle position detection device 12 as driving information. The control device 19 also acquires the set destination and the route to the destination from the navigation device 15 as driving information. The control device 19 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 booths, and positions where the number of lanes decreases as driving information from the map database 13. In addition, the control device 19 acquires information on the operation of the in-vehicle device 14 by the driver from the in-vehicle device 14 as driving information. The above is the driving information acquisition function realized by the control device 19.

The driving scene determination function of the control device 19 is a function that determines the driving scene in which the host vehicle is traveling by referring to a table stored in the ROM of the control device 19. The table stored in the ROM of the control device 19 stores, for each driving scene, driving scenes suitable for, for example, lane changing or overtaking, and the determination conditions for such scenes. The control device 19 refers to the table stored in the ROM to determine whether the driving scene in which the host vehicle is traveling is suitable for, for example, lane changing or overtaking.

For example, the following four conditions are set as conditions for determining a "scene of catching up with a preceding vehicle": "there is a preceding vehicle ahead," "the speed of the preceding vehicle is less than the set speed of the vehicle itself," "the preceding vehicle is reached within a specified time," and "the direction of the lane change does not satisfy a lane change prohibition condition." In this case, the control device 19 determines whether the vehicle itself satisfies the above conditions based on, for example, the detection results of the forward camera and forward radar included in the sensor 11, the vehicle speed of the vehicle itself detected by the vehicle speed sensor, and the position information of the vehicle itself from the vehicle position detection device 12. If the above conditions are met, the control device 19 determines that the vehicle itself is in a "scene of catching up with a preceding vehicle." This is the driving scene determination function realized by the control device 19.

The autonomous driving control function of the control device 19 is a function that allows the control device 19 to autonomously control the driving of the vehicle without relying on the driver's operation. The autonomous driving control function of the control device 19 includes an autonomous speed control function that autonomously controls the driving speed of the vehicle, and an autonomous steering control function that autonomously controls the steering of the vehicle. The autonomous speed control function and the autonomous steering control function of this embodiment are described below.

The autonomous speed control function is a function that, when a preceding vehicle is detected, follows the preceding vehicle while controlling the distance between the vehicles to maintain a distance according to the vehicle speed, with the upper limit set by the driver, and when a preceding vehicle is not detected, drives at a constant speed at the vehicle speed set by the driver. The former is also called distance control, and the latter is called constant speed control. The autonomous speed control function may also include a function that detects the speed limit of the road being traveled from road signs using the sensor 11, or obtains the speed limit from the map information in the map database 13, and automatically sets the set vehicle speed to that speed limit.

To activate the autonomous speed control function, the driver first operates the resume/accelerate switch 172 or the set/coast switch 173 of the input device 17 shown in FIG. 2 to input the desired driving speed. For example, if the driver presses the set/coast switch 173 while the vehicle is traveling at 70 km/h, the current driving speed is set as is. However, if the driver's desired speed is 80 km/h, the driver can simply press the resume/accelerate switch 172 multiple times to increase the set speed. This is because the "+" mark on the resume/accelerate switch 172 indicates that this is a switch that increases the set value. Conversely, if the driver's desired speed is 60 km/h, the driver can simply press the set/coast switch 173 multiple times to decrease the set speed. This is because the "-" mark on the set/coast switch 173 indicates that this is a switch that decreases the set value. The driver can adjust the desired distance by operating the distance adjustment switch 175 of the input device 17 shown in FIG. 2 and selecting one of several settings, such as short distance, medium distance, or long distance.

Constant speed control, which drives the vehicle at a constant speed set by the driver, is executed when the forward radar of the sensor 11 or the like detects that there is no preceding vehicle ahead in the vehicle's lane. In constant speed control, the drive control device 18 controls the operation of the drive mechanisms, such as the engine and brakes, while feeding back vehicle speed data from the vehicle speed sensor so as to maintain the set driving speed.

The vehicle distance control, which follows the preceding vehicle while performing vehicle distance control, is executed when the forward radar of the sensor 11 detects the presence of a preceding vehicle ahead in the vehicle's lane. In vehicle distance control, the drive control device 18 controls the operation of the engine, brakes, and other drive mechanisms while feeding back the vehicle distance data detected by the forward radar so as to maintain the set vehicle distance with the set travel speed as the upper limit. If the preceding vehicle stops while traveling under vehicle distance control, the vehicle stops following the preceding vehicle. Also, if the preceding vehicle starts moving within, for example, 30 seconds after the vehicle stops, the vehicle also starts moving and starts following the preceding vehicle under vehicle distance control again. If the vehicle has been stopped for more than 30 seconds, the vehicle does not start automatically even if the preceding vehicle starts moving, and if the resume/accelerate switch 172 is pressed or the accelerator pedal is depressed after the preceding vehicle starts moving, the vehicle starts following the preceding vehicle under vehicle distance control again.

On the other hand, the autonomous steering control function is a function for controlling the operation of the steering actuator to execute steering control of the vehicle. The autonomous steering control function of this embodiment includes: (1) a lane keeping function (lane width direction maintaining function) that controls the steering to drive, for example, near the center of the lane and assists the driver in steering; (2) a lane change assist function that controls the steering when the driver operates the turn signal lever and assists the steering operation required for lane change; (3) an overtaking assist function that, when a vehicle slower than a set vehicle speed is detected ahead, asks the driver by a display whether to perform an overtaking operation, and when the driver operates an acceptance switch, controls the steering and assists the overtaking operation; and (4) a route driving assist function that, when the driver has set a destination in a navigation device or the like, asks the driver by a display whether to perform a lane change when a lane change point required for driving along the route is reached, and controls the steering and assists the lane change when the driver operates an acceptance switch.

Here, the lane change assistance function of the autonomous steering control function will be described. Figure 3 is a plan view showing an example of lane change control (lane change assistance function) executed by the control device 19 of this embodiment. As shown in Figure 3, when the driver operates the turn signal lever of the vehicle V1, the control device 19 turns on the turn signal, and when a preset lane change start condition is met, starts a lane change operation (a series of processes for autonomous lane change, hereinafter also referred to as LCP). The control device 19 determines whether the lane change start condition is met based on various driving information acquired by the sensor 11. The lane change start conditions are not particularly limited, but examples include the following: (1) the vehicle is in lane keeping mode in hands-on mode; (2) a hands-on determination is in progress; (3) the vehicle is traveling at a speed of 60 km/h or more; (4) there is a lane in the direction of the lane change; (5) there is space in the lane to which the lane change is to be made that allows the vehicle to change lanes; (6) the type of lane marker indicates that the lane change is possible; (7) the curvature radius of the road is 250 m or more; and (8) the driver has operated the turn signal lever within one second. Note that when the control device 19 determines that the lane change start conditions are met by the lane change assistance function, even without a driver's instruction, the control device 19 may suggest to the driver to change lanes by informing the driver through the presentation device 16.

The lane keeping mode of the hands-on mode, which will be described in more detail later, refers to a state in which the autonomous speed control function and the lane keeping function of the autonomous steering control function are being executed and the driver is detected as holding the steering wheel. Also, "hands-on determination in progress" refers to a state in which the driver continues to hold the steering wheel.

When the lane change start condition is satisfied, the control device 19 starts the lane change operation LCP. As shown in FIG. 3, the lane change operation LCP in this embodiment includes a lateral movement of the vehicle V1 to the adjacent lane L2 and a lane change maneuver (hereinafter also referred to as LCM) to actually move to the adjacent lane L2. While executing the lane change operation LCP, the control device 19 presents information indicating that the lane change is being performed by autonomous control to the driver via the presentation device 16 to call attention to the surroundings. When the lane change maneuver LCM is completed, the control device 19 turns off the turn signal and starts executing the lane keeping function in the adjacent lane L2. The lane change operation LCP refers to the period from when the turn signal is turned on by operating the turn signal lever to when it is turned off, and the lane change maneuver LCM refers to the period from when the vehicle V1 starts to step on the boundary line between the vehicle V1 and the adjacent lane L2 to when it finishes stepping on it.

Now, in the control device 19 of this embodiment, the lane change shown in FIG. 3 is realized by the autonomous driving control by using the lane change assistance function. However, as shown in the figure, from the time the turn signal lever is operated to start the lane change operation LCP until the turn signal is turned off and the lane change operation LCP ends, the control device 19 continues to scan the driving environment around the vehicle V1 using the sensor 11, etc., and continuously determines whether the conditions for lane change are maintained. Therefore, if the driving state of the other vehicle suddenly changes and an unexpected other vehicle or obstacle appears in the lane to which the lane is to be changed, the lane change operation by the autonomous driving control may have to be stopped. When the lane change operation by the autonomous driving control is stopped in this way, it becomes necessary to transition from the autonomous control by the control device 19 to manual operation by the driver, which increases the driving load on the driver.

The lane change assist function of the control device 19 in this embodiment includes a function that, before starting a lane change operation using the lane change assist function, estimates the distance between the vehicle and another vehicle traveling in the original lane in advance, assuming that the vehicle stops changing lanes and returns to the original lane, and prohibits lane change when the distance is less than a predetermined value (positive value), and permits lane change only when the distance is equal to or greater than the predetermined value. This function is described below. Note that "in the middle of a lane change" refers to the period from the start of the lane change operation LCP shown in FIG. 3 to the end of the lane change operation LCP, and "stopping a lane change" refers to the cancellation or interruption of the lane change control that had been scheduled up to that point.

Figures 4A to 4D are plan views showing an example of lane change control in which a lane change is stopped midway and the vehicle returns to the original lane. Figure 4A shows a driving scene when a lane change operation is started. In Figure 4A, another vehicle V2 is traveling in front of the vehicle V1 in the lane L1 in which the vehicle V1 is traveling, and another vehicle V3 is traveling behind the vehicle V2 in the adjacent lane L2 to the right, but there is space for the vehicle V1 to change lanes to the adjacent lane L2. Note that another vehicle V4 is traveling in the adjacent adjacent lane L3 to the right of the adjacent lane L2, but is hidden by the other vehicle V3 and cannot be detected by the vehicle V1. When a predetermined lane change condition is met in this state, the direction indicator is turned on as shown in Figure 4A, and the vehicle starts moving laterally as shown by the arrow to cross the boundary between the vehicle L1 and the adjacent lane L2 and change lanes to the front of the other vehicle V3 traveling in the adjacent lane L2.

However, when another vehicle V4, which was not detectable because it was hidden by another vehicle V3 before the lane change was started, starts to change lanes into adjacent lane L2 to which the vehicle V1 is about to change lanes, as shown in FIG. 4B, the vehicle V1 is forced to stop or interrupt the lane change operation by the autonomous driving control. However, when it is determined that the lane change operation shown in FIG. 4B must be stopped or interrupted, if there is a space S in which the vehicle V1 can return to the original lane L1 without suddenly decelerating, as shown in FIG. 4C, the lane change control (lane change toward adjacent lane L2) that had been scheduled up until that point by the autonomous driving control is stopped, but it is possible to subsequently set a new lane change control to return to the original lane L1 (lane change toward the original lane L1).

Therefore, the control device 19 of this embodiment estimates the inter-vehicle distance D2 between the host vehicle V1 and another vehicle V2 traveling in the original lane L1 when it is assumed that the host vehicle V1, which has started a lane change operation as shown in Figures 4A and 4B, stops or interrupts the lane change as shown in Figure 4C, and returns to the original lane L1 as shown in Figure 4D. This inter-vehicle distance D2 can be calculated from the inter-vehicle distance D1 between the host vehicle V1 and the other vehicle V2 traveling in the original lane L1 shown in Figure 4A, the traveling speed of the host vehicle V1, the traveling speed of the other vehicle V2, the average traveling speed of the vehicle traveling in the lane L2 to which the lane is to be changed, the time required to change lanes, etc. The vehicle distance D2 shown in FIG. 4D can be determined from the average travel speed of the vehicle traveling in lane L1, and by calculating backwards from this vehicle distance D2, it is possible to calculate the required value for the vehicle distance D1 immediately before starting the lane change operation, that is, the vehicle distance D1 between the vehicle V1 shown in FIG. 4A and the other vehicle V2 traveling in the original lane L1.

The control device 19 of this embodiment prohibits a lane change operation if the following distance D1 immediately before the start of a lane change operation shown in FIG. 4A is calculated backward from the value determined by the following distance D2 shown in FIG. 4D using the traveling speed of the vehicle V1, the traveling speed of the other vehicle V2, the average traveling speed of the vehicles traveling in the lane L2 to which the lane is to be changed, the time required for the lane change, etc., and is less than a predetermined threshold value. On the other hand, if the following distance D1 immediately before the start of a lane change operation shown in FIG. 4A is calculated backward from the predetermined threshold value or more, the control device 19 permits a lane change operation.

The final inter-vehicle distance D2 shown in FIG. 4D can be determined from the average travel speed of the vehicles traveling on lane L1, and threshold values for inter-vehicle distance D2 for various average travel speeds are generated in advance using a control map or the like, and stored in the memory of the control device 19. In contrast, the inter-vehicle distance D1 before the start of a lane change operation shown in FIG. 4A is a value calculated backwards from the threshold value for inter-vehicle distance D2, and the inter-vehicle distance D1 increases, for example, the higher the average travel speed of the vehicles traveling on lane L1, the higher the average travel speed of the vehicles traveling on lane L2, and the greater the difference in average travel speeds between the two lanes L1 and L2.

Therefore, when the average traveling speed of the vehicle traveling in lane L2 is greater than the average traveling speed of the vehicle traveling in lane L1 and the speed difference is large, a relatively long distance is required for the following distance D1 before starting the lane change operation shown in FIG. 4A. Therefore, as shown in FIG. 4A, when the lane change condition is met and the host vehicle V1 starts the lane change operation, the host vehicle V1 can perform sufficient acceleration control in the original lane L1 before starting steering control to the adjacent lane L2. As a result, when the host vehicle V1 moves laterally to change lanes to the adjacent lane L2, the host vehicle V1 has already reached the average traveling speed of the vehicle traveling in the adjacent lane L2, and therefore is prevented from interfering with the traveling of the other vehicle V3 traveling in the adjacent lane L2.

Figure 5 is a time chart showing an example of a speed profile of lane change control in which a lane change caused by the lane change assist function is stopped in the middle of the lane change and the lane change is returned to the original lane L1. For example, before time t1, the vehicle V1 is traveling at a speed approximately equal to the average traveling speed VE1 of the lane L1 in which the vehicle is currently traveling. When the conditions for lane change are met at time t1, the turn signal is turned on and the lane change operation LCP is started. From time t1, acceleration control is started in the same lane L1 toward the average traveling speed VE2 of the adjacent lane L2, and after the vehicle V1 reaches the traveling speed VE2, the vehicle V1 starts to move laterally at time t2 and starts to cross the boundary between the vehicle L1 and the adjacent lane L2. If there is no change in the situation of the adjacent lane L2 and lane change can be continued, the vehicle V1 ends the lane change operation to the adjacent lane L2 while maintaining the traveling speed VE2, as shown by the dotted line in Figure 5.

In contrast, if it is determined that the lane change to the adjacent lane L2 is not possible at time t3 during the lane change, the lane change control to the adjacent lane L2 is stopped, and instead lane change control to the original lane L1 is started. In this lane change control to the original lane L1, the direction of the turn signal is changed, and the vehicle starts moving laterally in the opposite direction while decelerating toward the average driving speed VE1 of the original lane L1. As described above, in the lane change control executed by the control device 19 of this embodiment, the lane change permission conditions include the cancellation or interruption of the lane change and the securing of the inter-vehicle distance D2 when returning to the original lane L1. Therefore, the vehicle can return to the original lane L1 by a smooth deceleration operation without performing a sudden deceleration such as sudden braking. The above is the autonomous driving control when the lane change is stopped midway, which is included in the lane change assistance function of the control device 19 of this embodiment.

Incidentally, the driving assistance mode realized by the lane change assistance function of this embodiment has multiple levels. The driving assistance mode means a form or style of assistance in assisting driving operations. In this embodiment, the level of assistance is referred to as an assistance level. Each assistance level of the driving assistance mode defines the extent to which the control device 19 intervenes in the control of the vehicle's driving operations, in other words, the extent to which the driver's manual operation intervenes. The control device 19 combines autonomous control of the driving speed using the autonomous speed control function and autonomous control of the steering operation using the autonomous steering control function to realize the driving operation assistance defined by each assistance level when autonomously controlling the driving of the host vehicle.

The assistance level of this embodiment can be set based on the driving automation level defined in, for example, SAE J3016: SEP2016, Taxonomy and Definitions for Terms Related to Driving Automation Systems for On-Road Motor Vehicles published by the Society of Automotive Engineers (SAE). For example, assistance level 0 defined by the SAE is a level at which the driver performs all driving tasks required for driving operations. Similarly, assistance level 1 is a level at which the control device 19 continuously performs either autonomous speed control or autonomous steering control (not both simultaneously) in a specific limited area, and the driver performs either the running speed of the host vehicle or steering of the host vehicle by steering (not both simultaneously). Similarly, assistance level 2 is a level at which the control device 19 continuously performs autonomous speed control and autonomous steering control in a specific limited area, and the driver performs either the running speed of the host vehicle or steering of the host vehicle by steering (not both simultaneously). Similarly, assistance level 3 is a level at which the control device 19 continuously performs all driving tasks in a limited area. Similarly, support level 4 is a level at which the control device 19 executes all driving tasks and responds to cases where it is difficult to continue control continuously in a limited area. Similarly, support level 5 is a level at which the control device 19 executes all driving tasks and responds to cases where it is difficult to continue control continuously and indefinitely.

Assistance level 1 set in this embodiment corresponds to, but is not limited to, the control device 19 controlling the traveling speed of the vehicle by autonomous speed control. Similarly, assistance level 2 corresponds to the control device 19 executing lane change in hands-on mode by autonomous steering control. Therefore, for example, when the vehicle V1 shown in FIG. 3 attempts to change lanes from the vehicle's own lane L1 to the adjacent lane L2, the driving environment of the vehicle V1 changes, the conditions for continuing the lane change control in the hands-on mode are no longer satisfied, and the vehicle moves to autonomous speed control, etc., in a situation in which the assistance level of the driving assistance mode is reduced. In other words, a situation in which the initiative in driving operations is transferred from the control device 19 to the driver is a situation in which the assistance level is reduced, and the driving load on the driver increases.

<<State transition of driving control device>>
Fig. 6 is a block diagram showing state transitions of each function established in the control device 19. The system shown in Fig. 6 means an autonomous driving control system realized by the control device 19. When the main switch 171 in Fig. 2 is turned on from the system OFF state shown in Fig. 6, the system goes into a standby state. When the set/coast switch 173 or the resume/accelerate switch 172 in Fig. 2 is turned on from this standby state, the autonomous speed control is started. This starts the constant speed control or vehicle distance control described above, and the driver can drive the vehicle by simply operating the steering wheel without stepping on the accelerator or brake.

When the condition (1) in FIG. 6 is satisfied while the autonomous speed control is being performed, the autonomous steering control transitions to lane keeping mode in hands-on mode. This condition (1) is not particularly limited, but examples of the condition (1) include the following: lane markers are detected on both sides of the vehicle; the driver is holding the steering wheel; the vehicle is traveling near the center of the lane; the turn signals are not activated; the windshield wipers are not activated at high speed (HI); and, if there is a high-precision map, there are no toll booths, exits, junctions, intersections, or points where the number of lanes is reduced within approximately 200 m ahead. The hands-on mode refers to a mode in which the autonomous steering control does not operate unless the driver is holding the steering wheel, and the hands-off mode refers to a mode in which the autonomous steering control operates even if the driver takes his or her hands off the steering wheel.

When the condition (2) in FIG. 6 is satisfied while the lane keeping mode of the autonomous steering control hands-on mode is being executed, the autonomous steering control hands-off mode transitions to the lane keeping mode. This condition (2) is not particularly limited, but examples thereof include the following: the vehicle is traveling on a highway, the vehicle is traveling on a road that is structurally separated from the oncoming lane, the vehicle is traveling on a road with a high-precision map, the vehicle is traveling at a speed below the speed limit, the GPS signal is valid, the driver is holding the steering wheel, the driver is facing forward, there are no toll booths, exits, junctions, intersections, or points where the number of lanes is reduced within approximately 800 m ahead, there are no sharp curves of 100R or less within approximately 500 m ahead, the vehicle is not traveling in a tunnel more than 500 m from the tunnel entrance, and the accelerator pedal is not being depressed.

Conversely, when the lane keeping mode of the autonomous steering control/hands-off mode is being executed, if condition (3) in Figure 6 is satisfied, the mode will transition to the lane keeping mode of the autonomous steering control/hands-on mode. Examples of this condition (3) include, but are not limited to, the vehicle is traveling on a road other than a freeway, traveling in a two-way traffic zone, traveling on a road without a high-precision map, traveling at a speed exceeding the speed limit, being unable to receive a GPS signal, the driver not facing forward within 5 seconds after a forward gaze warning is activated, the driver cannot be detected by the driver monitor camera, there is a toll booth, an exit, a merging, or a reduction in the number of lanes approximately 800 meters ahead, if the vehicle is traveling at a speed of less than approximately 40 km/h, there is a sharp curve of 100 R or less within approximately 200 meters ahead, if the vehicle is traveling at a speed of approximately 40 km/h or more, there is a sharp curve of 170 R or less within approximately 200 meters ahead, the vehicle is traveling in a tunnel more than 500 m from the tunnel entrance, the driver is holding the steering wheel and depressing the accelerator pedal, and the approach warning is activated.

If condition (4) in FIG. 6 is satisfied while the lane keeping mode of the autonomous steering control/hands-off mode is being executed, the autonomous steering control is stopped and a transition to autonomous speed control is made. This condition (4) is not particularly limited, but examples thereof include the satisfaction of any of the following conditions: lane markers on both sides of the vehicle are not detected for a certain period of time; the driver operates the steering wheel; and the wipers are operated at high speed (HI). In addition, if condition (5) in FIG. 6 is satisfied while the lane keeping mode of the autonomous steering control/hands-off mode is being executed, the autonomous steering control and autonomous speed control are stopped and a transition to a standby state is made. Examples of this condition (5) include, but are not limited to, the establishment of any of the following conditions: the driver operates the brake, the driver operates the cancel switch 174 in FIG. 2, the door of the vehicle is opened, the driver's seat belt is released, the seat sensor detects that the driver has left the driver's seat, the select lever is in a position other than "D" or "M", the parking brake is activated, the vehicle's anti-skid device is turned off, the anti-skid device is activated, the snow mode is turned on, the emergency brake is activated, the vehicle is stopped for about three minutes after being stopped by vehicle speed control, the front camera detects poor visibility such as dirt, backlight, rain, fog, etc., the front radar detects obstruction or radio interference, the front radar detects axis misalignment, the side radar detects obstruction or radio interference, or the side radar detects axis misalignment.

When the autonomous steering control/hands-on mode is being executed, if the condition (6) in FIG. 6 is satisfied, the autonomous steering control is stopped and the autonomous speed control is started. This condition (6) is not particularly limited, but examples thereof include the following: lane markers on both sides of the vehicle are no longer detected; the driver has operated the steering wheel; the driver has operated the turn signal; the windshield wipers have been operated at high speed (HI); the vehicle has entered a toll booth area when a high-precision map is available; and the front camera has detected poor visibility due to dirt, backlight, rain, fog, etc., which makes it impossible to correctly recognize objects. In addition, when the condition (7) in FIG. 4 is satisfied while the autonomous steering control/hands-on mode is being executed, the autonomous steering control and the autonomous speed control are stopped and the autonomous speed control is started and the autonomous speed control is started. Condition (7) is not particularly limited, but examples include the following: the driver operates the brakes; the driver operates the cancel switch 174 in FIG. 2; the door of the vehicle is opened; the driver's seat belt is released; the seat sensor detects that the driver has left the driver's seat; the selector lever is in a position other than "D" or "M"; the parking brake is activated; the vehicle's anti-skid device is turned off; the anti-skid device is activated; the snow mode is turned on; the emergency brake is activated; the vehicle remains stopped for about three minutes after being stopped by vehicle speed control; the front radar detects obstruction or radio interference; and the front radar detects an axis deviation.

If condition (8) in FIG. 6 is satisfied while autonomous speed control is being performed, the system transitions to a standby state. Condition (8) is not particularly limited, but examples of the condition (8) include the following: the driver operates the brakes; the driver operates the cancel switch 174 in FIG. 2; the door of the vehicle is opened; the driver's seat belt is released; the seat sensor detects that the driver has left the driver's seat; the selector lever is in a position other than "D" or "M"; the parking brake is activated; the vehicle's anti-skid device is turned off; the anti-skid device is activated; the snow mode is turned on; the emergency brake is activated; the vehicle remains stopped for about three minutes after being stopped by vehicle speed control; the front radar detects obstruction or radio interference; and the front radar detects an axis deviation.

When the condition (9) in FIG. 6 is satisfied while the lane keep mode of the autonomous steering control hands-off mode is being executed, the system transitions to the lane change mode of the autonomous steering control hands-on mode. This condition (8) is not particularly limited, but examples thereof include the satisfaction of any of the following conditions when the system suggests a lane change: the driver presses the lane change assistance switch 176 in FIG. 2, or the driver operates the blinker.

4 is satisfied while executing the lane change mode of the autonomous steering control hands-on mode, the vehicle transitions to the lane keep mode of the autonomous steering control hands-on mode. This condition (10) is not particularly limited, but may be, for example, the speed limit being exceeded before the lane change operation LCP is started, the driver holds the steering wheel and depresses the accelerator pedal before the lane change operation LCP is started, the lane change operation LCP is not started within 10 seconds after the lane change assistance switch 176 is pressed during a lane change proposal in case of a slow vehicle ahead, the lane change operation LCP is not started within 10 seconds after the lane change assistance switch 176 is pressed during a lane change proposal to travel along a route, and the lane change operation LCP is not started and the vehicle gets too close to a branch after the lane change assistance switch 176 is pressed. The actual lane change maneuver LCM could not be started within 5 seconds after the CP was activated; the lane change maneuver LCM was started and the vehicle speed fell below approximately 50 km/h before the lane change maneuver LCM was started; after the lane change maneuver LCP was activated, the space in the adjacent lane necessary for lane change was no longer available before the lane change maneuver LCM was started; the driver performed a cancel operation before the lane change maneuver LCM was started; the lane markers were not detected before the lane change maneuver LCM was started; and there was no adjacent lane L2 in the direction of lane change before the lane change maneuver LCM was started. Or, it has been determined that the adjacent lane L2 no longer exists within a certain distance ahead, it has been determined that there is a curve with a curvature radius of 250 m or less within a certain distance ahead before the start of the lane change maneuver LCM, it has been determined that there is a section within a certain distance ahead where the type of dividing line prohibits lane changing to the adjacent lane L2 before the start of the lane change maneuver LCM, the side radar has detected obstruction or radio interference before the start of the lane change maneuver LCM, the side radar has detected an axis misalignment before the start of the lane change maneuver LCM, or a hands-on warning has been activated (the lane change maneuver LCM Examples of conditions that can be met include the driver not holding the steering wheel within about 2 seconds after activation, the driver not holding the steering wheel within about 2 seconds after pressing the lane change assistance switch 176 while a lane change is being suggested in case of a slower vehicle ahead, or the driver not holding the steering wheel within about 2 seconds after pressing the lane change assistance switch 176 while a lane change is being suggested to travel along a route), the driver turning off the blinker, or the lane change operation LCP being completed.

When the main switch 171 is turned off in any of the following states: autonomous steering control/hands-off mode, autonomous steering control/hands-on mode, autonomous speed control, or standby mode, the system is turned off.

<<Drive control processing>>
Next, the driving control process according to this embodiment will be described with reference to Figures 7A to 7C. Figures 7A to 7C are flowcharts showing an example of the driving control process executed by the control device 19 of this embodiment. Figures 7A and 7B show the basic driving control process, and Figure 7C shows a subroutine of step S10 in Figure 7A.

The driving control process described below is executed at a predetermined time interval by the control device 19. In the following, it is assumed that the autonomous driving control function of the control device 19 executes autonomous speed control and autonomous steering control, and performs lane keeping control to control the driving position of the host vehicle in the width direction so that the host vehicle drives within the lane at a speed set by the driver.

In step S1 of FIG. 7A, the control device 19 determines whether the main switch 171 is ON. If the main switch 171 is OFF, the control device 19 repeats step S1 until the main switch 171 is ON. On the other hand, if the main switch 171 is ON, the control device 19 proceeds to step S2.

In step S2, the control device 19 determines whether or not the driver has set the driving speed. If the driving speed has not been set, the process returns to step S1, and steps S1 and S2 are repeated until the driving speed is set. On the other hand, if the driving speed has been set, the process proceeds to step S3. The driver sets the driving speed by operating the resume/accelerate switch 172 or the set/coast switch 173 of the input device 17 shown in FIG. 2 to input the desired driving speed.

When the driver sets the driving speed, autonomous speed control is initiated. In step S3, the control device 19 uses a forward radar (sensor 11) that detects obstacles ahead of the vehicle to detect whether or not there is a preceding vehicle ahead in the lane in which the vehicle is traveling. If a preceding vehicle is detected, the process proceeds to step S4, where vehicle distance control is performed. On the other hand, if a preceding vehicle is not detected, the process proceeds to step S5, where constant speed control is performed. This allows the driver to drive the vehicle at the desired speed simply by operating the steering wheel, without stepping on the accelerator or brake.

While the vehicle distance control in step S4 or the constant speed control in step S5 is being performed, in step S6, the control device 19 determines whether or not condition (1) for transitioning to the lane keeping mode of the autonomous steering control/hands-on mode shown in FIG. 6 is satisfied. If condition (1) shown in FIG. 6 is not satisfied, the process returns to step S3 and vehicle distance control or constant speed control is continued. On the other hand, if condition (1) shown in FIG. 6 is satisfied, the process proceeds to step S7.

In step S7, the control device 19 uses a forward radar (sensor 11) that detects obstacles ahead of the vehicle to detect whether or not there is a preceding vehicle ahead in the lane in which the vehicle is traveling. If a preceding vehicle is detected, the process proceeds to step S8 and executes distance control/lane keeping mode. On the other hand, if a preceding vehicle is not detected, the process proceeds to step S9 and executes constant speed control/lane keeping mode. In this state, the lane change assist function and overtaking assist function are executed in step S10. Details of step S10 will be described later.

While the vehicle distance control/lane keeping mode of step S8 or the constant speed control/lane keeping mode of step S9 is being executed, in the next step S11 of FIG. 7B, the control device 19 determines whether or not condition (2) for transitioning to the automatic steering control/hands-off mode shown in FIG. 6 is satisfied. If condition (2) shown in FIG. 6 is satisfied, the process proceeds to step S12. On the other hand, if condition (2) shown in FIG. 6 is not satisfied, the process proceeds to step S15, which will be described later.

In step S12, when the condition (2) for transitioning to the automatic steering control/hands-off mode is met, the control device 19 uses the forward radar (sensor 11) that detects obstacles ahead of the vehicle to detect whether or not there is a preceding vehicle ahead in the lane in which the vehicle is traveling. If a preceding vehicle is detected, the process proceeds to step S13, where vehicle distance control/lane keeping mode/hands-off is executed. On the other hand, if a preceding vehicle is not detected, the process proceeds to step S14, where constant speed control/lane keeping mode/hands-off is executed.

In step S15, the control device 19 uses a forward radar (sensor 11) that detects obstacles ahead of the vehicle to detect whether or not a leading vehicle is present ahead in the lane in which the vehicle is traveling. If no leading vehicle is detected, the process returns to step S1 and continues with subsequent processing. On the other hand, if a leading vehicle is detected, the process proceeds to step S16.

In step S16, the control device 19 determines whether or not the condition (1) for transitioning to the lane keeping mode of the autonomous steering control/hands-on mode is satisfied, similar to step S6. If the condition (1) shown in FIG. 6 is not satisfied, the process returns to step S1 and continues with the subsequent processing. On the other hand, if the condition (1) shown in FIG. 6 is satisfied, the process proceeds to step S17.

In step S17, the control device 19 determines whether or not the condition (2) for transitioning to the automatic steering control/hands-off mode is satisfied, similar to step S11. If the condition (2) shown in FIG. 6 is satisfied, the process returns to step S12 and continues from there. On the other hand, if the condition (2) shown in FIG. 6 is not satisfied, the process returns to step S1 and continues from there.

In step S10 of FIG. 7A, the process shown in FIG. 7C is executed as the execution process of the lane change assistance function. First, in step S101 of FIG. 7C, the control device 19 determines whether or not the host vehicle V1 needs to change lanes. For this determination, the route to the destination set by the navigation device 15 is used, and the lane currently being traveled is compared with the lanes set on the route to the destination. If it is determined that a lane change is not necessary, the process proceeds to step S11 of FIG. 7C without executing lane change assistance, and the driving control process continues thereafter. On the other hand, if it is determined that a lane change is necessary, the process proceeds to step S102 of FIG. 7C.

In step S102, the control device 19 uses the forward radar and forward camera (sensor 11) that detect obstacles ahead of the host vehicle V1 to detect whether or not there is a preceding vehicle V5 (see FIG. 4A) traveling ahead of the host vehicle V1 in the adjacent lane L2. If a preceding vehicle V5 traveling in the adjacent lane L2 is detected, the process proceeds to step S103. On the other hand, if a preceding vehicle V5 traveling in the adjacent lane L2 is not detected, the process proceeds to step S104.

In step S103, the control device 19 determines whether the host vehicle V1 can follow the preceding vehicle V5 detected in step S102. Whether or not the host vehicle V1 can follow the preceding vehicle V5 can be determined based on, for example, a condition such as whether the relative speed between the preceding vehicle V5 and the host vehicle V1 is less than a predetermined value. If it is determined that the host vehicle V1 can follow the preceding vehicle V5, the process proceeds to step S105. On the other hand, if it is determined that the host vehicle V1 cannot follow the preceding vehicle V5, for example because the preceding vehicle V5 traveling in the adjacent lane L2 is traveling too fast, the process proceeds to step S104.

In step S104, the control device 19 determines whether the traveling speed of the host vehicle V1 is equal to or lower than a predetermined traveling speed at which the assistance level of the host vehicle V1 does not decrease before and after a lane change from the host lane L2 to the adjacent lane L2. The traveling speed of the host vehicle V1 is detected using a vehicle speed sensor (sensor 11). If it is determined that the traveling speed of the host vehicle V1 is equal to or lower than the predetermined traveling speed, the process proceeds to step S105. In contrast, if it is determined that the traveling speed of the host vehicle V1 exceeds the predetermined traveling speed, the process proceeds to step S11 in FIG. 7C without executing lane change assistance, and the subsequent driving control processing is continued.

In step S105, the control device 19 uses the lane change assistance function to estimate the inter-vehicle distance D2 (see FIG. 4D) between the host vehicle V1 and the other vehicle V2 traveling in the original lane L1 when it is assumed that the host vehicle V1 has stopped changing lanes and returned to the original lane L1, and determines whether the inter-vehicle distance D2 is less than a predetermined value. If the estimated inter-vehicle distance D2 is less than a predetermined value (No in step S105), lane change control is prohibited and the process proceeds to step S11 in FIG. 7B, and the driving control process thereafter is continued. On the other hand, if the estimated inter-vehicle distance D2 is equal to or greater than the predetermined value (Yes in step S105), the process proceeds to step S106.

In step S106, the control device 19 starts a lane change operation as shown in FIG. 3 using the lane change assistance function, but until the lane change operation is completed in step S108, in step S107, the control device 19 continues to scan the situation around the vehicle V1 using the sensor 11 and the like to determine whether the lane change conditions are satisfied. Then, as shown in FIG. 4B, if an unexpected vehicle V4 appears in the lane L2, which is the lane to be changed to, during the lane change operation, and the lane change conditions are no longer satisfied, the process proceeds to step S109.

In step S109, the control device 19 uses the lane change assistance function to stop the lane change control from lane L1 to lane L2 set in step S106, and instead, as shown in FIG. 4C, sets lane change control from the current position to the original lane L1. Then, in step S110, this is continued until the lane change to the original lane L1 is completed, as shown in FIG. 4D.

As described above, according to the vehicle driving control method and driving control device 1 of this embodiment, before starting a lane change from lane L1 to lane L2, the vehicle distance D2 between the host vehicle V1 and another vehicle V2 traveling in the original lane L1 is estimated assuming that the lane change is stopped midway and the vehicle returns to the original lane L1, and the lane change is prohibited if the vehicle distance D2 falls below a predetermined value. This prevents a situation in which a sufficient vehicle distance cannot be secured when the vehicle is forced to cancel the lane change due to a change in the driving environment and is forced to return to the original lane. As a result, it is possible to suppress an increase in the driver's driving load when changing lanes under autonomous driving control.

In addition, according to the vehicle driving control method and driving control device 1 of this embodiment, when the above-mentioned inter-vehicle distance D2 becomes equal to or greater than a predetermined value, the lane change is permitted. Therefore, even if the lane change is stopped midway and the vehicle returns to the original lane L1, the inter-vehicle distance D2 between the vehicle V1 and the other vehicle V2 traveling in the original lane L1 is sufficiently secured to be equal to or greater than the predetermined value. Therefore, the vehicle can return to the original lane L1 by smoothly decelerating without performing a sudden deceleration such as hard braking.

In addition, according to the vehicle cruise control method and cruise control device 1 of this embodiment, the average travel speed of vehicles traveling in the adjacent lane L2 is faster than the average travel speed of vehicles traveling in the own lane L1. Therefore, since the lane is changed to a lane with a relatively faster travel speed, if the lane change is stopped midway and the vehicle returns to the original lane L1, a large amount of deceleration is required. However, according to this embodiment, the vehicle can return to the original lane L1 by smoothly decelerating without having to perform a sudden deceleration such as hard braking, so the effect is even more pronounced.

In addition, according to the vehicle driving control method and driving control device 1 of this embodiment, acceleration control is executed in the original lane L1 after autonomous lane change control is started and before steering control to the adjacent lane L2 is started, so that when the host vehicle V1 moves laterally to the adjacent lane L2 to change lanes, it has reached the average driving speed of the vehicles traveling in the adjacent lane L2. Therefore, interference with the driving of another vehicle V3 traveling in the adjacent lane L2 is suppressed.

In addition, according to the vehicle driving control method and driving control device 1 of this embodiment, multiple assistance levels are set in the driving assistance mode that uses autonomous driving control to assist the driver's driving operation, and the assistance level does not decrease while the vehicle is changing lanes using autonomous driving control. Therefore, even if the vehicle stops changing lanes in the middle of a lane change and returns to the original lane L1, the assistance level does not decrease, and an increase in the driver's driving load can be suppressed.

REFERENCE SIGNS LIST 1...cruising control device 11...sensor 12...own vehicle position detection device 13...map database 14...in-vehicle equipment 15...navigation device 16...presentation device 17...input device 171...main switch 172...resume/accelerate switch 173...set/coast switch 174...cancel switch 175...distance adjustment switch 176...lane change assistance switch 18...drive control device 19...control device V1...own vehicle V2, V3, V4...other vehicles V5...preceding vehicle L1...original lane (first lane)
L2: adjacent lane (second lane)
L3: adjacent lanes D1, D2: distance between vehicles

Claims (6)

A method for controlling driving of a vehicle, the method comprising: autonomous speed control for autonomously controlling a driving speed of the vehicle; and autonomous steering control for autonomously controlling steering of the vehicle, the method comprising the steps of: changing lanes from a first lane in which the vehicle is currently traveling to an adjacent second lane;
estimating a vehicle-to-vehicle distance between the host vehicle and the other vehicle in a case where the host vehicle stops the lane change midway and returns to the rear of the other vehicle traveling in the first lane before starting the lane change;
A vehicle travel control method which prohibits the lane change when the inter-vehicle distance is less than a predetermined value. The vehicle driving control method according to claim 1, wherein the lane change is permitted when the vehicle-to-vehicle distance is equal to or greater than the predetermined value. A vehicle driving control method, comprising: an autonomous driving control including an autonomous speed control for autonomously controlling a driving speed of a vehicle; and an autonomous steering control for autonomously controlling steering of the vehicle, for changing lanes from a first lane in which the vehicle is currently traveling to an adjacent second lane; and an average driving speed of the vehicle traveling in the second lane is faster than an average driving speed of the vehicle traveling in the first lane ,
estimating a vehicle-to-vehicle distance between the host vehicle and another vehicle traveling on the first lane in a case where the host vehicle stops the lane change midway and returns to the first lane before starting the lane change;
A vehicle travel control method which prohibits the lane change when the vehicle-to-vehicle distance falls below a predetermined value . A method for controlling driving of a vehicle, the method comprising: autonomous speed control for autonomously controlling a driving speed of the vehicle; and autonomous steering control for autonomously controlling steering of the vehicle, the method comprising the steps of: changing lanes from a first lane in which the vehicle is currently traveling to an adjacent second lane;
estimating a vehicle-to-vehicle distance between the host vehicle and another vehicle traveling on the first lane in a case where the host vehicle stops the lane change midway and returns to the first lane before starting the lane change;
When the vehicle-to-vehicle distance is less than a predetermined value, the lane change is prohibited.
A vehicle driving control method that executes acceleration control in the first lane after starting the autonomous lane change control and before starting steering control to the second lane. A method for controlling driving of a vehicle, the method comprising: autonomous speed control for autonomously controlling a driving speed of the vehicle; and autonomous steering control for autonomously controlling steering of the vehicle, the method comprising the steps of: changing lanes from a first lane in which the vehicle is currently traveling to an adjacent second lane;
estimating a vehicle-to-vehicle distance between the host vehicle and another vehicle traveling on the first lane in a case where the host vehicle stops the lane change midway and returns to the first lane before starting the lane change;
When the vehicle-to-vehicle distance is less than a predetermined value, the lane change is prohibited.
A driving assistance mode that assists a driver in driving operation using the autonomous driving control is set to a plurality of assistance levels,
The vehicle driving control method, wherein the assistance level is not decreased while the host vehicle is changing lanes through autonomous driving control. A vehicle driving control device including a processor for executing autonomous driving control including an autonomous speed control for autonomously controlling a driving speed of a host vehicle and an autonomous steering control for autonomously controlling a steering of the host vehicle,
When changing lanes from the currently traveling first lane to the adjacent second lane by autonomous driving control,
The processor,
estimating a vehicle-to-vehicle distance between the host vehicle and the other vehicle in a case where the host vehicle stops the lane change midway and returns to the rear of the other vehicle traveling in the first lane before starting the lane change;
A vehicle travel control device that prohibits the lane change when the vehicle-to-vehicle distance falls below a predetermined value.

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