Driving assistance method and driving assistance device

Abstract

Provided are a driving assistance method and a driving assistance device (14), wherein the steering direction of a steering-controlled wheel of a vehicle (V) is acquired, a left threshold value for when a steering wheel is turned in the left direction and a right threshold value for when the steering wheel is turned in the right direction are set as threshold values for releasing autonomous steering control of the vehicle (V), the autonomous steering control is released when the absolute value of a torque inputted to the steering wheel surpasses the left threshold value or the right threshold value, if the steering direction is in the left direction, then the right threshold value is greater than the left threshold value, and if the steering direction is in the right direction, then the left threshold value is greater than the right threshold value.

Description

Driving assistance method and driving assistance device

[0001] The present invention relates to a driving assistance method and a driving assistance device.

[0002] A steering assist device is known that stops lane change assist control when it is determined that an input value based on a driver's steering operation exceeds an override threshold during execution of the lane change assist control (Patent Document 1). In this steering assist device, a forward threshold in the direction in which the vehicle is changing lanes and a reverse threshold in the direction opposite to the forward direction are set as override thresholds, and the magnitude of the reverse threshold is set smaller than the magnitude of the forward threshold until the end of the vehicle on the lane-changing side crosses the boundary between the original lane and the target lane.

[0003] Patent No. 6819876

[0004] In a system that rotates the steering wheel according to the steering angle, a force that resists the movement of the steering wheel is generated in the steering system including the steering wheel. When the steering actuator controls the steered wheels to turn, this resistance force is detected by the torque sensor as a torque in the opposite direction to the turning direction of the vehicle. Therefore, even though the driver is not operating the steering wheel, it is recognized as a torque in the opposite direction to the turning direction of the vehicle being input from the steering wheel.

[0005] In the above-mentioned conventional technology, the reverse direction threshold is set smaller than the forward direction threshold. Therefore, if the forward direction threshold is set small to allow a smooth transition to manual driving by the driver, the absolute value of the torque due to the resistance force in the above-mentioned steering system will exceed the reverse direction threshold, resulting in the problem that the autonomous steering control will be erroneously released regardless of the driver's steering operation.

[0006] The problem to be solved by the present invention is to provide a driving assistance method and a driving assistance device that can prevent autonomous steering control from being erroneously released without being caused by a steering operation by the driver.

[0007] The present invention solves the above problem by setting a left threshold when the vehicle's steering wheel is rotated to the left and a right threshold when the vehicle's steering wheel is rotated to the right as thresholds for releasing the vehicle's autonomous steering control, and by making the right threshold larger than the left threshold when the steering direction of the vehicle's steered wheels is to the left, and making the left threshold larger than the right threshold when the steering direction is to the right.

[0008] According to the present invention, it is possible to prevent autonomous steering control from being erroneously released without being caused by the driver's steering operation.

[0009] Fig. 1 is a block diagram showing an example of a driving assistance system including a driving assistance device of the present invention. Fig. 2 is a diagram showing a plan view showing an example of a driving scene in which driving assistance is performed using the driving assistance system of Fig. 1, and a steering torque detected in the driving scene. Fig. 3 is a diagram showing an example of a resistance force generated in a steering system when a vehicle turns. Fig. 4 is a flowchart showing an example of a processing procedure in the driving assistance system of Fig. 1. Fig. 5 is a flowchart showing another example of the processing procedure in the driving assistance system of Fig. 1.

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] [Configuration of Driving Assistance System] FIG. 1 is a block diagram showing a driving assistance system 1 according to the present invention. The driving assistance system 1 is an in-vehicle system that drives a vehicle to a destination set by the vehicle's occupants through autonomous driving control. Autonomous driving control refers to autonomously controlling the vehicle's driving operations using a driving assistance device (described later), and the driving operations include all driving operations such as acceleration, deceleration, starting, stopping, and turning right or left. Autonomously controlling driving operations refers to the driving assistance device controlling the driving operations using a device in the vehicle. The driving assistance device controls these driving operations within a predetermined range, and driving operations that are not controlled by the driving assistance device are manually operated by the driver.

[0012] 1, the driving assistance system 1 includes an imaging device 11, a vehicle state detection device 12, a steering control device 13, and a driving assistance device 14. In addition, the driving assistance system 1 may include a distance measuring device, map information, a vehicle position detection device, a navigation device, a display device, and a speed control device (not shown) in order to perform autonomous driving control. The devices that make up the driving assistance system 1 are connected by a CAN (Controller Area Network) or other in-vehicle LAN and can exchange information with each other.

[0013] The imaging device 11 is a device that recognizes objects around the vehicle using images, and is, for example, a camera equipped with an imaging element such as a CCD, an ultrasonic camera, an infrared camera, etc. In order to reduce blind spots when recognizing objects, multiple imaging devices 11 can be installed on one vehicle, and can be placed, for example, near the front grille, under the left and right door mirrors, and near the rear bumper of the vehicle.

[0014] The objects detected by the imaging device 11 include road lane boundaries, center lines, road markings, medians, guardrails, curbs, highway sidewalls, road signs, traffic signals, crosswalks, construction sites, accident sites, traffic restrictions, etc. The objects also include obstacles that may affect the travel of the vehicle, such as automobiles (other vehicles) other than the subject vehicle, motorcycles, bicycles, pedestrians, etc.

[0015] The detection results of the imaging devices 11 are acquired at predetermined time intervals by the driving assistance device 14 as needed. This predetermined time interval can be set to an appropriate value depending on the processing capacity of the driving assistance device 14. Furthermore, the detection results of the multiple imaging devices 11 and a distance measuring device (not shown) can be integrated or synthesized (sensor fusion) in the driving assistance device 14 to supplement missing information about the detected object.

[0016] The vehicle state detection device 12 is a device for detecting the vehicle's running state, and examples thereof include a speed sensor, an acceleration sensor, a yaw rate sensor (e.g., a gyro sensor), a steering angle sensor, and an inertial measurement unit. There are no particular limitations on these devices, and known devices can be used. The locations and numbers of these devices can be set appropriately within a range that allows appropriate detection of the vehicle's running state. The detection results of each device are acquired by the driving assistance device 14 at predetermined time intervals as necessary.

[0017] The steering control device 13 is an on-board computer for electronically controlling the steering device, such as an electronic control unit (ECU). Information necessary for steering control by the steering control device 13, such as the vehicle's traveling speed, acceleration, steering angle (rotation angle of the steering wheel), and attitude, is obtained from the vehicle state detection device 12. The steering device may be, for example, a steering actuator (motor) attached to a steering column shaft that steers the steered wheels according to the steering angle. Alternatively, the steering actuator may be attached to a steering rack or pinion gear of a mechanism that steers the steered wheels. Furthermore, as a steer-by-wire system in which the mechanism that steers the steered wheels and the steering wheel are mechanically separated, both a steering actuator attached to a steering rack or pinion gear of a mechanism that steers the steered wheels and a steering actuator attached to a steering column shaft may be provided.

[0018] The driving assistance device 14 controls the driving of the vehicle by controlling and cooperating with the devices that make up the driving assistance system 1, and drives the vehicle to a set destination using autonomous driving control. The driving assistance device 14 also monitors the driving state of the vehicle as steered by the driver and performs steering control to prevent the vehicle from leaving its lane. A steering operation is, for example, the driver turning the steering wheel. The driving state of the vehicle is a parameter detected by the host vehicle state detection device 12, and examples of the vehicle include the vehicle's driving speed, acceleration, lateral speed, lateral acceleration, yaw rate, and steering angle.

[0019] A vehicle deviating from a lane means that the vehicle crosses a boundary that defines a lane and, in a plan view, part or all of the vehicle body is outside the lane. For example, if a vehicle is traveling in a lane defined by a boundary line such as a white line and crosses the boundary line to enter an adjacent lane, the vehicle is determined to have deviated from the lane. The boundary that defines a lane is not limited to a boundary line such as a white line, but may also be a boundary between a drivable area and an impassable area. For example, a guardrail, a curb on the shoulder of the road, a median strip, or the boundary between a paved road and an unpaved road (e.g., a gravel road) is also included in the boundary that defines a lane.

[0020] The driving assistance device 14 is, for example, a computer, and includes a CPU (Central Processing Unit) as a processor, a ROM (Read Only Memory) in which programs are stored, and a RAM (Random Access Memory) that functions as an accessible storage device. The CPU is an operating circuit that executes the programs stored in the ROM to monitor the driving state and perform steering control.

[0021] Regarding devices not shown, the distance measuring device is a device for calculating the relative distance and relative speed between the vehicle and an object, such as a radar device or sonar, such as a laser radar, a millimeter-wave radar (e.g., LRF), a LiDAR (light detection and ranging) unit, or an ultrasonic radar. The map information is particularly high-definition map information, including road information, facility information, and attribute information thereof, which are used for generating a driving route and controlling driving operations. The vehicle position detecting device is a positioning system, such as a GPS (Global Positioning System), for detecting the current position of the vehicle. The navigation device is a device that refers to map information and calculates a driving route from the current position of the vehicle detected by the vehicle position detecting device to a destination set by the occupant. The speed control device is a device that autonomously controls the vehicle's driving speed by generating a signal for controlling the drive unit and transmitting the signal to the drive unit in accordance with a control signal input from the driving assistance device 14. The display device is, for example, a liquid crystal display, and may also include an input device and a speaker.

[0022] [Functions of Each Functional Block] In addition to a driving assistance function that causes the vehicle to drive under autonomous driving control, the driving assistance device 14 also has a monitoring function that monitors the vehicle's driving state and a steering control function that executes steering control, and these functions are realized by the CPU of the driving assistance device 14 executing a program stored in the ROM. Figure 1 shows functional blocks that realize each function, extracted for convenience. Below, the functions of each functional block of the assistance unit 2, recognition unit 21, acquisition unit 22, setting unit 23, and control unit 24 shown in Figure 1 will be described.

[0023] The assistance unit 2 has the function of acquiring information from each device constituting the driving assistance system 1, processing the acquired information, outputting instructions to each device, and executing autonomous driving control by having the devices constituting the driving assistance system 1 cooperate with each other. Figure 2 is a plan view showing an example of a driving scene in which the driving assistance device 14 executes autonomous driving control using the driving assistance function, monitoring using the monitoring function, and steering control using the steering control function.

[0024] The driving scene shown on the left side of Figure 2 is a driving scene in which vehicle V travels from current position P1 to position P2 along a driving trajectory T in a lane L defined by boundary line B1 on the left side of the vehicle V's direction of travel and boundary line B2 on the right side of the vehicle V's direction of travel. In this driving scene, normal autonomous steering control is performed by the assistance unit 2, and the vehicle V turns left by turning the steered wheels of the vehicle V leftward using the steering actuator. In this case, the driving assistance device 14 performs the autonomous steering control of this embodiment using the steering control function.

[0025] The autonomous steering control refers to autonomously controlling the steering of the vehicle V using the driving assistance device 14, and includes, for example, controlling the rotation of the steering wheel using a steering actuator of the vehicle V, and controlling the rotation of the steered wheels using a steering actuator attached to a steering rack or pinion gear of a mechanism for rotating the steered wheels. The autonomous steering control of this embodiment also includes lane departure prevention control that prevents the vehicle V from deviating from the lane L in which it is traveling. The lane departure prevention control is initiated when it is determined that the vehicle V will deviate from the lane L during monitoring of the driving state, and the steering control function is used to execute steering control that prevents the vehicle V from deviating from the lane L.

[0026] In a steering system in which the steering wheel and steered wheels are mechanically connected via a shaft or the like, when the vehicle V turns, a force is generated in the steering system that resists the movement of the vehicle attempting to turn. Specifically, when the steered wheels are rotated to turn the vehicle V, a force is generated that resists the change in the movement of the steered wheels (i.e., a resistance force that rotates the steered wheels and the steering wheel connected to the steered wheels in opposite directions). Furthermore, in a steer-by-wire steering system in which the mechanism for steering the steered wheels is not mechanically connected to the steering wheel, a force that resists the rotation of the steering wheel is generated when the steering wheel is rotated in accordance with the steering angle. When the vehicle V is turned by autonomous steering control using a steering actuator, as in the driving scene shown on the left side of Figure 2, this resistance force is detected as a steering torque that rotates the steering wheel. The relationship between the resistance force and the steering torque will be explained using Figure 3.

[0027] Fig. 3 is a timing diagram showing an example of the relationship between the steering angle and steering torque when the vehicle V turns under autonomous steering control. The upper diagram in Fig. 3 shows the steering angle of the vehicle V rotated by the steering actuator (i.e., the rotation angle of the steered wheels), and the lower diagram in Fig. 3 shows the steering torque detected by the torque sensor. In both diagrams, the horizontal axis represents time, and the time in the upper diagram corresponds to the time in the lower diagram. In addition, in the timing diagram shown in Fig. 3, when the steered wheels are rotated to the right, the steering angle and steering torque take positive values, and when the steered wheels are rotated to the left, the steering angle and steering torque take negative values.

[0028] In the example shown in Fig. 3, as shown in the upper diagram of Fig. 3, the steered wheels are rotated to the right at a constant angular velocity from the start of rotation of the steered wheels to time t1, the steered wheels are rotated to the left at a constant angular velocity from time t1 to time t2, and the steered wheels are rotated to the right at a constant angular velocity from time t2 to time t3. In this case, even though the driver is not operating the steering wheel, the torque sensor detects leftward steering torque from the start of rotation of the steered wheels to time t1, detects rightward steering torque from time t1 to time t2, and detects leftward steering torque from time t2 to time t3, as shown in the lower diagram of Fig. 3.

[0029] Returning to Fig. 2, in the driving scene shown in the diagram on the left side of Fig. 2, it is assumed that the steering torque shown in the diagram on the right side of Fig. 2 is detected when the steered wheels are turned leftward (i.e., when the steered wheels are turned leftward in the direction of travel) in order for the vehicle V to travel along the driving trajectory T. The diagram on the right side of Fig. 2 shows the steering torque detected by the torque sensor, and when the steering wheel is turned rightward with respect to the center origin, it takes a positive value, and when the steering wheel is turned leftward it takes a negative value.

[0030] In this case, if the threshold for disabling the autonomous steering control of vehicle V is set to the same value as the left threshold when the steering wheel is rotated to the left and the right threshold when the steering wheel is rotated to the right, the magnitude of the detected steering torque will exceed the magnitude of the right threshold (comparison example) shown in the diagram on the right side of Figure 2, and the autonomous steering control will be erroneously disabling even though the driver is not operating the steering wheel.

[0031] Therefore, in the present invention, when the steered wheels are rotating leftward (i.e., when the steered wheels are turning leftward), the right threshold value is set to a value larger than the left threshold value, and conversely, when the steered wheels are rotating rightward (i.e., when the steered wheels are turning rightward), the left threshold value is set to a value larger than the right threshold value. Also, when the rotation direction is expressed as a positive or negative rotation angle, when the steered wheels are rotating leftward, the absolute value of the right threshold value is set to a value larger than the absolute value of the left threshold value, and conversely, when the steered wheels are rotating rightward, the absolute value of the left threshold value is set to a value larger than the absolute value of the right threshold value.

[0032] The autonomous steering control of this embodiment will be described in detail below. In the following description, unless otherwise specified, the rotation direction of the steering wheel and steered wheels is not expressed in terms of positive or negative threshold values, and both the right threshold value and the left threshold value are assumed to be positive values. In addition, the steered wheels will also be referred to as steered wheels.

[0033] The recognition unit 21 has a function of recognizing the driving environment around the vehicle V. The driving assistance device 14 recognizes the driving environment around the vehicle V using the imaging device 11 through the function of the recognition unit 21. The driving environment is information for determining whether the vehicle V can maintain its current driving state or whether it needs to change its driving state, and includes information such as the type and position of an object, the type and position of an obstacle if one exists, and road conditions. The driving assistance device 14 recognizes the driving environment by performing appropriate processing such as pattern matching on the detection results of the imaging device 11.

[0034] In the driving scene shown on the left side of FIG. 2, the driving assistance device 14 performs edge extraction processing on the detection results of the imaging device 11 and recognizes boundary lines B1 and B2.

[0035] The acquisition unit 22 has a function of acquiring the steering direction of the steered wheels of the vehicle V. The driving assistance device 14 uses the function of the acquisition unit 22 to acquire the rotation direction of the steered wheels from the detection results of the imaging device 11, the yaw rate sensor, the steering angle sensor, etc.

[0036] In the driving scene shown in the diagram on the left side of Figure 2, the driving assistance device 14 recognizes that the rotation direction of the steered wheels is to the left (i.e., the steering direction of the steered wheels is to the left) because the yaw rate detected by the yaw rate sensor is a negative value.

[0037] The setting unit 23 has a function of setting, as thresholds for canceling autonomous steering control of the vehicle V, a left threshold for canceling autonomous steering control when the steering wheel is turned leftward, and a right threshold for canceling autonomous steering control when the steering wheel is turned rightward. When the steering direction acquired by the function of the acquisition unit 22 is leftward, the driving assistance device 14 of this embodiment sets the right threshold to be higher than the left threshold by the function of the setting unit 23. On the other hand, when the steering direction acquired is rightward, the left threshold is set to be higher than the right threshold. For example, when the turning direction is leftward, the driving assistance device 14 sets the right threshold to a value obtained by multiplying the left threshold by a predetermined coefficient (e.g., 1.5 to 3), and when the turning direction is rightward, the driving assistance device 14 sets the left threshold to a value obtained by adding a predetermined value (e.g., 0.5 to 2 [Nm]) to the right threshold.

[0038] In the driving scene shown in the diagram on the left side of Figure 2, the rotation direction of the steered wheels is to the left (i.e., the steering direction of the steered wheels is to the left), so the driving assistance device 14 sets the right threshold value to a value that is twice the left threshold value, for example.

[0039] The control unit 24 has a function of canceling autonomous steering control when the absolute value of the torque input to the steering wheel exceeds a left threshold or a right threshold. The driving assistance device 14 uses the function of the control unit 24 to determine whether the absolute value of the torque input to the steering wheel exceeds a left threshold or a right threshold, and continues autonomous steering control if the absolute value of the torque does not exceed the left threshold or the right threshold. On the other hand, if the absolute value of the torque exceeds the left threshold or the right threshold, the autonomous steering control is canceled and the driver is prompted to switch to manual driving.

[0040] The driving assistance device 14 may operate the steering actuator via the steering control device 13 to rotate the steered wheels left or right to adjust the steering angle. In the case of a steer-by-wire system in which the mechanism for steering the steered wheels is mechanically separated from the steering wheel, one or both of the steering angle of the steering actuator attached to the steering rack or pinion gear of the mechanism for steering the steered wheels and the steering angle of the steering actuator attached to the steering column shaft can be adjusted. Note that releasing the autonomous steering control means ending the execution of autonomous steering control by the driving assistance device 14. Also, manual driving means that the driving assistance device 14 does not perform autonomous driving control of the driving operation, and the driving of the vehicle is controlled by operation of the driver.

[0041] In the driving scene shown in the diagram on the left side of Figure 2, the steering torque detected by the torque sensor does not exceed the right threshold value, so the driving assistance device 14 continues autonomous steering control and drives from current position P1 to position P2.

[0042] The driving assistance device 14 of this embodiment may use the function of the acquisition unit 22 to determine whether the vehicle V will turn under autonomous steering control, and if it determines that the vehicle V will turn under autonomous steering control, acquire the steering direction of the steered wheels. In this case, if the steering direction is leftward, the right threshold is set to be greater than the left threshold, and if the steering direction is rightward, the left threshold is set to be greater than the right threshold. For example, the driving assistance device 14 acquires the steering direction of the steered wheels and sets the left threshold and the right threshold according to the steering direction before the autonomous steering control starts. Then, it determines the end of the turn of the vehicle V and maintains the left threshold and the right threshold until it is determined that the turn has ended. This prevents the thresholds from being switched while the vehicle V is turning, and prevents the autonomous steering control from being released at a time unintended by the driver.

[0043] The autonomous steering control of this embodiment may be performed in combination with monitoring by the monitoring function of the driving assistance device 14. For example, when the vehicle V is traveling due to a steering operation by the driver, the driving assistance device 14 may use the function of the control unit 24 to determine whether the vehicle V will deviate from the lane L in which it is traveling, and when it is determined that the vehicle V will deviate from the lane L in which it is traveling, start lane departure prevention control to prevent the vehicle V from deviating from the lane L instead of the driver's steering operation. On the other hand, when it is determined that the vehicle V will not deviate from the lane L in which it is traveling, the lane departure prevention control is not started and the driver's steering operation is allowed to continue.

[0044] When determining whether the vehicle V will deviate from the lane L, the driving assistance device 14, for example, acquires the traveling direction of the vehicle V and determines whether, if the vehicle V continues to travel along the traveling direction, it will cross the boundary that defines the lane L and deviate from the lane L. The traveling direction of the vehicle V is recognized from the yaw rate acquired from a yaw rate sensor, the steering angle acquired from a steering angle sensor, etc.

[0045] As an example of a method for determining deviation of the vehicle V, the driving assistance device 14 detects the boundary of the lane L on which the vehicle V is traveling and recognizes the positional relationship between the boundary and the vehicle V (for example, the distance between the vehicle V and the boundary). Then, it determines whether the vehicle V will cross the boundary that defines the lane L if it travels while maintaining a yaw angle relative to the boundary. The driving assistance device 14, for example, calculates a lane-to-lane yaw angle, which is the angle between the traveling direction of the vehicle V and the tangent direction of the lane L at the vehicle V's traveling position on the lane L. The driving assistance device 14 also calculates the distance in the width direction between the vehicle V and the boundary line B1. Then, deviation of the vehicle V is predicted from the lane-to-lane yaw angle and the distance in the width direction. As an example, if the lane-to-lane yaw angle is within a range in which the vehicle V can travel along the lane L and the distance between the vehicle V and the boundary line B1 is long (i.e., the vehicle V is farther away from the boundary line B1), it is predicted that the vehicle V will not deviate from the lane L. On the other hand, when the lane-to-lane yaw angle of the vehicle V is larger or smaller than the range in which the vehicle V can travel along the lane L (i.e., when the steering angle is too large or too small for the required lane-to-lane yaw angle), or when the distance between the vehicle V and the boundary line B1 is shortened (i.e., when the vehicle V and the boundary line B1 are approaching each other), it is predicted that the vehicle V will deviate from the lane L. Note that the tangent to the boundary line B1 is, for example, the tangent to the point on the boundary line B1 that is closest to the body of the vehicle V.

[0046] When lane departure prevention control is initiated in place of a steering operation by the driver, the driving assistance device 14 of this embodiment acquires the departure direction in which the vehicle V deviates from the lane L. The departure direction of the vehicle V is the direction in which the vehicle V will head if it deviates from the lane L on which the vehicle V is traveling, and indicates whether the vehicle V will deviate to the right or left with respect to the direction of travel. In other words, the departure direction indicates whether the vehicle V will cross the boundary on the right side or the left side of the direction of travel among the boundaries defining the lane L when it is predicted that the vehicle V will deviate from the lane L on which the vehicle V is traveling. If the departure direction is to the left, the vehicle V will deviate from the lane L by crossing the boundary on the left side of the direction of travel, and if the departure direction is to the right, the vehicle V will deviate from the lane L by crossing the boundary on the right side of the direction of travel.

[0047] The driving assistance device 14 acquires the departure direction in which the vehicle V will depart from the lane L from the information on the traveling direction of the vehicle V that was used when predicting the departure of the vehicle V from the lane L. For example, when it is predicted that the vehicle V will depart from the lane L, if the traveling direction of the vehicle V is to the left front or to the left side of the vehicle V, the departure direction is the leftward direction, and if the traveling direction of the vehicle V is to the right front or to the right side of the vehicle V, the departure direction is the rightward direction.

[0048] Furthermore, the driving assistance device 14 sets the left threshold value larger than the right threshold value when the direction in which the vehicle V deviates from the lane L is to the left of the vehicle V's traveling direction. This is because the steered wheels are rotated to the right when the vehicle V deviates to the left of the vehicle V's traveling direction. On the other hand, when the direction in which the vehicle V deviates from the lane L is to the right of the vehicle V's traveling direction, the driving assistance device 14 sets the right threshold value larger than the left threshold value. This is because the steered wheels are rotated to the left when the vehicle V deviates to the right of the vehicle V's traveling direction.

[0049] For example, in the driving scene shown on the left side of Figure 2, if the driver's steering wheel operation is delayed and it is determined that the vehicle V will deviate from the lane L to the right of the traveling direction, the driving assistance device 14 recognizes from the traveling direction of the vehicle V that the vehicle V is deviating to the right of the traveling direction and sets the right threshold value to a value 1.5 times the left threshold value. In this way, by setting the values ​​of the right threshold value and the left threshold value according to the direction in which the vehicle V deviates, it is possible to set a threshold value for canceling the autonomous steering control (lane departure prevention control) without obtaining the rotation direction of the steering wheel.

[0050] The process of determining whether the vehicle V deviates from the lane L, the process of starting lane departure prevention control to prevent the vehicle V from deviating from the lane L, and the process of acquiring the departure direction in which the vehicle V deviates from the lane L are not essential components of the present invention and may be provided as needed. Furthermore, the process of setting the values ​​of the right threshold and the left threshold according to the departure direction is not essential components of the present invention and may be provided as needed.

[0051] Furthermore, the driving assistance device 14 may set the difference between the right and left threshold values ​​to a larger value as the rotation speed of the steering wheel increases. This is because the greater the rate of change in the steering angle, the greater the resistance force generated in the steering system. Note that the process of setting the right and left threshold values ​​according to the rotation speed of the steering wheel is not essential to the present invention, and may be added or omitted as necessary.

[0052] [Processing in Driving Assistance System] The procedure for information processing by the driving assistance device 14 will be described with reference to Figures 4 and 5. Figure 4 is an example of a flowchart showing information processing executed in the driving assistance system 1 of this embodiment. The driving scene in which the processing in Figure 4 is performed is assumed to be a driving scene in which the vehicle V is traveling in lane L under autonomous steering control. The processing described below is executed at predetermined time intervals by the CPU, which is the processor of the driving assistance device 14.

[0053] First, in step S1, the function of the acquisition unit 22 is used to determine whether the vehicle V will turn under autonomous steering control. If it is determined that the vehicle V will not turn under autonomous steering control, the process proceeds to step S2, where normal autonomous steering control is executed using the function of the assistance unit 2, and the process proceeds to step S1. On the other hand, if it is determined that the vehicle V will turn under autonomous steering control, the process proceeds to step S3, where the function of the setting unit 23 is used to set a right threshold and a left threshold as thresholds for canceling the autonomous steering control. In the following step S4, the function of the acquisition unit 22 is used to acquire the turning direction of the steered wheels of the vehicle V, and in step S5, the function of the control unit 24 is used to determine whether the turning direction is leftward. If the turning direction is leftward, the process proceeds to step S6, where the right threshold is set larger than the left threshold, and if the turning direction is rightward, the process proceeds to step S7, where the left threshold is set larger than the right threshold.

[0054] In step S8, it is determined whether the absolute value of the input steering torque exceeds the left threshold or the right threshold. If it is determined that the absolute value of the input steering torque does not exceed the left threshold or the right threshold, the process proceeds to step S9, where autonomous steering control continues. In the following step S10, it is determined whether steering of the vehicle V has been completed, and if it is determined that steering of the vehicle V has not been completed, the process proceeds to step S8. On the other hand, if it is determined that steering of the vehicle V has been completed, the process proceeds to step S11, where it is determined whether the vehicle V has reached the destination. If it is determined that the vehicle V has reached the destination, execution of the routine is terminated and the process transitions to manual driving by the driver. On the other hand, if it is determined that the vehicle V has not reached the destination, the process proceeds to step S1.

[0055] On the other hand, if it is determined in step S8 that the absolute value of the input steering torque exceeds the left threshold value or the right threshold value, the process proceeds to step S12, where the autonomous steering control is released and the vehicle is shifted to manual driving by the driver. Note that steps S1, S2, S10, and S11 are not essential steps for the present invention, and may be added or omitted as necessary.

[0056] Next, Fig. 5 is another example of a flowchart showing information processing executed in the driving assistance system 1 of this embodiment. The driving scene in which the processing in Fig. 5 is performed is a driving scene in which the vehicle V is traveling due to steering operation by the driver, while monitoring of the driving state of the vehicle V is being performed by the monitoring function of the driving assistance device 14. The processing described below is executed at predetermined time intervals by the CPU, which is the processor of the driving assistance device 14.

[0057] First, in step S21, the direction of travel of the vehicle V is acquired using the function of the acquisition unit 22, and then in the following step S22, the function of the control unit 24 is used to determine whether or not the vehicle V will deviate from the lane L. If it is determined in step S22 that the vehicle V will not deviate from the lane L, the process proceeds to step S21, where monitoring of the traveling state continues. On the other hand, if it is determined that the vehicle V will deviate from the lane L, the process proceeds to step S23.

[0058] In step S23, lane departure prevention control is started by the function of the control unit 24. In step S24, the setting unit 23 sets a right threshold value and a left threshold value for canceling the autonomous steering control (lane departure prevention control), and in the subsequent step S25, the acquisition unit 22 acquires the direction in which the vehicle V will depart. In step S26, the control unit 24 determines whether the direction in which the vehicle V will depart is to the left in the traveling direction. If the direction in which the vehicle V will depart is to the left in the traveling direction, the process proceeds to step S27, where the left threshold value is set larger than the right threshold value. On the other hand, if the direction in which the vehicle V will depart is to the right in the traveling direction, the process proceeds to step S28, where the right threshold value is set larger than the left threshold value.

[0059] In step S29, the steering direction of the steered wheels is controlled using the steering actuator so that the vehicle V does not deviate from the lane L, and in the following step S30, it is determined whether the absolute value of the input steering torque exceeds a left threshold or a right threshold. If it is determined that the absolute value of the input steering torque does not exceed the left threshold or the right threshold, the process proceeds to step S31, where autonomous steering control (lane departure prevention control) is continued. In the following step S32, it is determined whether the vehicle V will deviate from the lane L. If it is determined that the vehicle V will deviate from the lane L, the process proceeds to step S29. On the other hand, if it is determined that the vehicle V will not deviate from the lane L, the process proceeds to step S33, where the lane departure prevention control is terminated and monitoring of the driving state is continued.

[0060] On the other hand, if it is determined in step S30 that the absolute value of the input steering torque exceeds the left threshold or the right threshold, the process proceeds to step S34, where the autonomous steering control (lane departure prevention control) is cancelled, and the execution of the routine is then terminated, and the vehicle transitions to driving under the steering operation of the driver while continuing to monitor the driving state.

[0061] [Embodiment of the Invention] As described above, according to this embodiment, in a driving assistance method executed by a processor, the processor acquires the steering direction of steered wheels of a vehicle, sets a left threshold when the steering wheel is turned left and a right threshold when the steering wheel is turned right as thresholds for canceling autonomous steering control of the vehicle V, and cancels the autonomous steering control when the absolute value of the torque input to the steering wheel exceeds the left threshold or the right threshold, and when the steering direction is the left direction, the right threshold is greater than the left threshold, and when the steering direction is the right direction, the left threshold is greater than the right threshold. This makes it possible to smoothly transition to manual driving by the driver while preventing the autonomous steering control from being erroneously canceled without being due to a steering operation by the driver.

[0062] Furthermore, according to the driving assistance method of this embodiment, the processor determines whether the vehicle V will turn under the autonomous steering control, and if it determines that the vehicle V will turn under the autonomous steering control, acquires the turning direction, and if the turning direction is to the left, sets the right threshold value larger than the left threshold value, and if the turning direction is to the right, sets the left threshold value larger than the right threshold value. This makes it possible to prevent the turning direction from frequently switching during autonomous steering control, and to avoid canceling the autonomous steering control at a timing unintended by the driver.

[0063] Furthermore, according to the driving assistance method of this embodiment, the processor determines whether the vehicle V, which is traveling due to a steering operation by the driver, will deviate from the lane L in which it is traveling, and if it determines that the vehicle V will deviate from the lane L, obtains the direction in which the vehicle V will deviate from the lane L, and if the vehicle deviates to the left of its direction of travel, sets the left threshold value larger than the right threshold value, and if the vehicle deviates to the right of its direction of travel, sets the right threshold value larger than the left threshold value. This makes it possible to set a threshold value for canceling autonomous steering control without obtaining the direction of rotation of the steering wheel, thereby simplifying the processing in the driving assistance device 14.

[0064] According to the driving assistance method of the present embodiment, the processor sets a larger difference between the right threshold value and the left threshold value as the rotation speed of the steering wheel increases, thereby enabling the threshold value to be set in accordance with the rate of change of the steering angle.

[0065] Furthermore, according to this embodiment, a driving assistance device 14 is provided that includes an acquisition unit 22 that acquires the steering direction of the steered wheels of the vehicle V, a setting unit 23 that sets a left threshold value when the steering wheel is turned left and a right threshold value when the steering wheel is turned right as threshold values ​​for canceling autonomous steering control of the vehicle V, and a control unit 24 that cancels the autonomous steering control when the absolute value of the torque input to the steering wheel exceeds the left threshold value or the right threshold value, wherein if the steering direction is the left direction, the right threshold value is greater than the left threshold value, and if the steering direction is the right direction, the left threshold value is greater than the right threshold value. This makes it possible to smoothly transition to manual driving by the driver while preventing the autonomous steering control from being erroneously canceled without being caused by the driver's steering operation.

[0066] 1... Driving assistance system 11... Imaging device, 12... Vehicle state detection device, 13... Steering control device, 14... Driving assistance device 2... Assistance unit 21... Recognition unit, 22... Acquisition unit, 23... Setting unit, 24... Control unit B1, B2... Boundary line, L... Lane, P1... Current position, P2... Position, T... Traveling trajectory, V... Vehicle

Claims

1. When the vehicle is running under the driver's steering operation, obtain the traveling direction of the vehicle, Determine whether the vehicle deviates from the lane in which it is traveling, When it is determined that the vehicle deviates from the lane, execute, by a processor, lane departure suppression control for suppressing the vehicle from deviating from the lane, in a driving support method, The processor, obtains the direction in which the vehicle deviates from the lane, sets, as a threshold for releasing the lane departure suppression control, a left threshold when the steering wheel is rotated in the left direction and a right threshold when the steering wheel is rotated in the right direction, when the vehicle deviates in a direction to the left with respect to the traveling direction, set the left threshold to be greater than the right threshold, when the vehicle deviates in a direction to the right with respect to the traveling direction, set the right threshold to be greater than the left threshold, when the absolute value of the torque input to the steering wheel does not exceed the left threshold or the right threshold, continue the lane departure suppression control, when the absolute value of the torque input to the steering wheel exceeds the left threshold or the right threshold, release the lane departure suppression control, a driving support method.

2. The processor, when the vehicle is running under autonomous steering control, determines whether the vehicle steers by the autonomous steering control, when it is determined that the vehicle steers by the autonomous steering control, obtains the steering direction of the steered wheels of the vehicle, sets, as a threshold for releasing the autonomous steering control, the left threshold and the right threshold, when the steering direction is the left direction, set the right threshold to be greater than the left threshold, when the steering direction is the right direction, set the left threshold to be greater than the right threshold, the driving support method according to claim 1.

3. (Deleted)

4. The operation support method according to claim 1 or 2, wherein the processor sets a larger difference between the right threshold value and the left threshold value as the rotation speed of the steering wheel is higher.

5. When the vehicle is traveling by the driver's steering operation, an acquisition unit that acquires the traveling direction of the vehicle, determining whether the vehicle deviates from the lane during travel, a control unit that executes lane departure suppression control for suppressing the vehicle from deviating from the lane when it is determined that the vehicle deviates from the lane; a setting unit that sets a left threshold value when the steering wheel is rotated in the left direction and a right threshold value when the steering wheel is rotated in the right direction as threshold values for canceling the lane departure suppression control; the acquisition unit acquires the direction in which the vehicle deviates from the lane, the setting unit sets the left threshold value to be larger than the right threshold value when the vehicle deviates in a direction to the left with respect to the traveling direction, the setting unit sets the right threshold value to be larger than the left threshold value when the vehicle deviates in a direction to the right with respect to the traveling direction, the control unit continues the lane departure suppression control when the absolute value of the torque input to the steering wheel does not exceed the left threshold value or the right threshold value, a driving support device that cancels the lane departure suppression control when the absolute value of the torque input to the steering wheel exceeds the left threshold value or the right threshold value.