Driving assistance method and driving assistance device

Abstract

A driving assistance method and a driving assistance device (14) predict whether or not a vehicle (V) traveling by a steering operation of a driver deviates from a lane (L) in which the vehicle (V) is traveling, and if it is predicted that the vehicle (V) deviates from the lane (L), acquire a deviation direction in which the vehicle (V) deviates from the lane (L) and a turning direction of the vehicle (V). The steering control unit determines whether or not the deviation direction and the turning direction are the same direction, and if it is determined that the deviation direction and the turning direction are the same direction, performs steering control in which the steering wheel of the vehicle (V) is not rotated in the deviation direction and the vehicle (V) is not deviated from the lane (L).

Description

Technical Field

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

[0002] Lane departure prevention control for preventing a vehicle from deviating from a lane in which it is traveling is known (Patent Document 1). In the lane departure prevention control, as target yaw rates for the vehicle to travel along a target route, a target yaw rate for a departure suppression control for suppressing a vehicle from deviating from a lane and a target yaw rate for a posture determination control for controlling the posture of the vehicle after the departure suppression control are calculated. The target yaw rate for the posture determination control is a value calculated by multiplying the deviation between the target lane yaw angle at the end of the control and the lane yaw angle in the posture determination control by a predetermined feedback gain and dividing it by a target time until the target lane yaw angle is reached.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 6637952

[0006] Problems to be solved by the invention

[0007] In the above-mentioned prior art, when the absolute value of the target lane yaw angle at the end of the control is greater than the absolute value of the lane yaw angle in the posture determination control, the steering wheel rotates in the turning direction in the posture determination control. In this case, the steering wheel rotates in the turning direction after being rotated in the direction opposite to the turning direction by the deviation suppression control, and rotates in the direction opposite to the turning direction again by the automatic self-aligning torque after the posture determination control ends.

[0008] As described above, if the steering wheel is turned in the turning direction before the attitude determination control ends, the driver will mistakenly recognize the steering wheel rotation based on the self-aligning torque after the attitude determination control ends as a series of steering controls that continue the attitude determination control. Therefore, after the attitude determination control ends, the driver starts to operate the steering wheel at a later time, and the vehicle behavior will change significantly in order to avoid leaving the lane. Summary of the invention

[0009] An object of the present invention is to provide a driving assistance method and a driving assistance device that can suppress a driver from erroneously recognizing the end of steering control and switching to a steering operation by the driver.

[0010] The present invention solves the above-mentioned problem by not rotating the steering wheel of the vehicle in the deviation direction when it is determined that the deviation direction of the vehicle from the lane is the same as the turning direction of the vehicle, when the vehicle is predicted to deviate from the lane by the driver's steering operation.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to suppress the driver from erroneously recognizing the end of the steering control and switching to the timing based on the driver's steering operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a block diagram showing an example of a driving assistance system including the driving assistance device of the present invention.

[0014] Figure 2 It means use Figure 1 The illustrated driving assistance system shows an example of a driving scenario in which a steering control as driving assistance is executed, and a diagram showing a timing chart of the movement of a steering wheel during the steering control and before and after the steering control.

[0015] Figure 3 It means in Figure 2 FIG. 1 is a diagram of a timing diagram for a driving scenario in which the vehicle is traveling at a faster speed.

[0016] Figure 4 It is the curvature ratio of the curve. Figure 2 FIG. 1 is a diagram showing an example of steering control executed in a large driving scene and a timing chart of the movement of the steering wheel during the steering control and before and after the steering control.

[0017] Figure 5A Yes means Figure 1 Flowchart (part 1) of an example of a processing sequence in a driving assistance system.

[0018] Figure 5B Yes means Figure 1 Flowchart of an example of the processing sequence in the driving assistance system (part 2).

[0019] Figure 5C Yes means Figure 1 Flowchart of an example of the processing sequence in the driving assistance system (part 3).

[0020] Figure 6 It is a diagram showing an example of steering control according to a comparative example of the present invention and a timing chart showing the operation of a steering wheel in the steering control according to the comparative example. DETAILED DESCRIPTION

[0021] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0022] (Driver assistance system structure)

[0023] Figure 1 : is a block diagram representing the driving assistance system 1 of the present invention. The driving assistance system 1 is a vehicle-mounted system that monitors the driving state of a vehicle driven by a driver's steering operation, and when it is predicted that the vehicle deviates from the lane in which it is traveling, steers the steering wheel of the vehicle so as not to cause the vehicle to deviate from the lane. A steering wheel refers to a wheel that changes the direction of travel of the vehicle, and is also called a steering wheel. A steering operation refers to, for example, the driver turning the steering wheel. In addition, the driving state of the vehicle refers to a parameter detected by a vehicle state detection device described later, and examples thereof include: the vehicle's driving speed, acceleration, lateral speed, lateral acceleration, yaw rate, and steering wheel rotation angle (hereinafter also referred to as "steering angle"), etc.

[0024] Vehicle deviation from the lane means that the vehicle crosses the boundary of the lane, and part or all of the vehicle body is included in the range outside the lane when viewed from above. For example, when a vehicle is traveling on a lane demarcated by boundary lines such as white lines, if it crosses the boundary line and enters the adjacent lane of the lane, it is determined that the vehicle has deviated from the lane. In addition, the boundary of the lane is not limited to boundary lines such as white lines, but can also be the boundary between a drivable area and a non-drivable area. For example, guardrails, curbs on shoulders, central dividers, and the dividing line between paved roads and unpaved roads (such as gravel roads) are also included in the boundary of the lane.

[0025] like Figure 1 As shown, the driving support system 1 includes an imaging device 11, a vehicle state detection device 12, a steering control device 13, and a driving support device 14. The devices constituting the driving support system 1 are connected via a CAN (Controller Area Network) or other vehicle-mounted LAN and can transmit and receive information to each other.

[0026] The imaging device 11 is a device for recognizing objects around the vehicle through images, and is, for example, a camera having an imaging element such as a CCD, an ultrasonic camera, etc. A plurality of imaging devices 11 may be provided on a single vehicle, for example, disposed at the front grille of the vehicle, the lower part of the left and right door mirrors, and near the rear bumper.

[0027] As the objects detected by the camera device 11, in addition to the above-mentioned lane boundaries, there are also the following: lane boundaries, center lines, road surface markings, central dividers, guardrails, curbs, side walls of highways, road signs, traffic lights, crosswalks, construction sites, accident sites, traffic restrictions, etc. In addition, the objects include obstacles that may affect the driving of the vehicle, such as cars (other vehicles) other than the vehicle, two-wheeled automatic vehicles (motorcycles), bicycles, pedestrians, etc.

[0028] The driving assistance device 14 acquires the detection results of the camera 11 at a predetermined time interval as needed. The predetermined time interval can be set to an appropriate value according to the processing capability of the driving assistance device 14. In addition, the detection results of a plurality of cameras 11 may be integrated or synthesized in the driving assistance device 14 to supplement the missing information of the detected object.

[0029] The vehicle state detection device 12 is a device for detecting the driving state of the vehicle, and can include: a speed sensor, an acceleration sensor, a yaw rate sensor (such as a gyro sensor), a steering angle sensor, an inertial measurement unit, etc. These devices are not particularly limited, and known devices can be used. In addition, the configuration and number of these devices can be appropriately set within the range that the driving state of the vehicle can be appropriately detected. The detection results of each device are obtained by the driving assistance device 14 at a specified time interval as needed.

[0030] The steering control device 13 is an on-board computer for electronically controlling the steering device, such as an electronic control unit (ECU). The information required for the steering control device 13 to perform steering control, such as the vehicle's running speed, acceleration, steering angle, and posture, is obtained from the vehicle state detection device 12. As a steering device, for example, a steering gear actuator (electric motor) mounted on the column shaft of the steering gear that steers the steering wheel according to the steering angle can be listed. In addition, it can also be a steering gear actuator mounted on the steering rack or pinion of the mechanism for steering the steering wheel. Furthermore, as a wire control steering method that mechanically separates the mechanism for steering the steering wheel from the steering wheel, it is also possible to have both a steering gear actuator mounted on the steering rack or pinion of the mechanism for steering the steering wheel and a steering gear actuator mounted on the column shaft of the steering gear.

[0031] The driving assistance device 14 is a device that monitors the driving state of the vehicle that the driver is steering by controlling and cooperating the devices that constitute the driving assistance system 1, and performs steering control to suppress the vehicle from deviating from the lane. The driving assistance device 14 is, for example, a computer, and includes a CPU (Central Processing Unit) 141 as a processor, a ROM (Read Only Memory) 142 storing a program, and a RAM (Random Access Memory) 143 that functions as an accessible storage device. The CPU 141 is an action circuit that executes the program stored in the ROM 142 to perform the above-mentioned monitoring and steering control.

[0032] The driving assistance device 14 has a monitoring function for monitoring the driving state and a steering control function for performing steering control, and these functions are realized by causing the CPU 141 to execute a program stored in the ROM 142. Figure 1 In the example above, for convenience, the functional modules that implement each function are extracted and represented. Figure 1 The functions of the functional blocks of the auxiliary unit 2, the identification unit 21, the prediction unit 22, the acquisition unit 23 and the control unit 24 shown in the figure will be described.

[0033] (Function of each functional block)

[0034] The support unit 2 has a function of acquiring information from each device constituting the driving support system 1 , processing the acquired information, and outputting instructions to each device to cause the devices constituting the driving support system 1 to cooperate. Figure 2 It is a plan view showing an example of a driving scene in which the driving assistance device 14 performs monitoring by the monitoring function and steering control by the steering control function.

[0035] Figure 2 The driving scene shown is a driving scene in which a vehicle V is driving in a lane L in the direction of an arrow X. That is, Figure 2 The illustrated vehicle V is traveling in a lane L defined by a boundary line B1 on the left side of the vehicle V in the traveling direction and a boundary line B2 on the right side of the vehicle V in the traveling direction, and is traveling from the left side to the right side of the drawing.

[0036] exist Figure 2 In the driving scenario, it is assumed that the driver performs steering operation of vehicle V, such as Figure 2 As shown in FIG. 1 , the vehicle V enters a left curve that turns to the left and is currently traveling at position P1. In addition, if the steering angle after entering the left curve is large and the steering wheel is not turned by the driving assistance device 14, the vehicle V turns to the left in the traveling direction from position P1, crosses the boundary line B1, and deviates from the lane L. In this case, the driving assistance device 14 predicts the deviation of the vehicle V from the lane L through the monitoring function, and performs steering control through the steering control function as needed.

[0037] The recognition unit 21 has a function of recognizing the driving environment around the vehicle V in order to predict the deviation of the vehicle V from the lane L. The driving assistance device 14 recognizes the driving environment around the vehicle V using the camera device 11 through the function of the recognition unit 21. The driving environment refers to information used to determine whether the vehicle V can maintain the current driving state and whether it is necessary to change the driving state, for example, information including the type and position of the object, the type and position of the obstacle when there is an obstacle, the road condition, etc. The driving assistance device 14 performs appropriate processing such as pattern matching on the detection result of the camera device 11 to recognize the driving environment.

[0038] exist Figure 2 In the driving scene shown, the driving assistance device 14 performs edge extraction processing and the like on the detection result of the camera device 11 through the function of the recognition unit 21 to recognize the boundary lines B1 and B2 .

[0039] In addition, the driving assistance device 14 may also obtain the distance in the width direction between the vehicle V and the boundary lines B1 and B2 according to the rotation direction of the steering wheel or the turning direction of the vehicle V. Figure 2 In the driving scene shown, the driver inputs a left-direction rotation torque to the steering wheel, and the vehicle V turns left. Therefore, when the torque is detected, the width direction distance D between the vehicle V and the boundary line B1 on the left side of the traveling direction is obtained. In addition, the process of obtaining the width direction distance D is not a necessary configuration of the present invention, and can also be provided as needed.

[0040] The prediction unit 22 has a function of predicting whether the vehicle V traveling by the driver's steering operation deviates from the traveling lane L. The driving assistance device 14 acquires the traveling direction of the vehicle V through the function of the prediction unit 22, and predicts whether the vehicle V crosses the boundary defining the lane L and deviates from the lane L when the vehicle V continues traveling in the traveling direction. The traveling direction of the vehicle V is identified based on the yaw rate acquired from the yaw rate sensor, the steering angle acquired from the steering angle sensor, and the like.

[0041] As an example of a method for predicting the deviation of the vehicle V, the driving assistance device 14 detects the boundary of the lane L in which the vehicle V is traveling based on the image data obtained from the camera device 11, and recognizes the positional relationship between the boundary and the vehicle V. That is, based on the distance D in the width direction, etc., it is recognized whether the vehicle V is far from the boundary, whether the vehicle V is close to the boundary, how far the vehicle V is from the boundary, etc. In addition, the driving assistance device 14 calculates the lane deviation angle (lane deviation angle) which is the angle formed by the traveling direction of the vehicle V and the tangent direction of the lane L at the position where the vehicle V is traveling on the lane L. Then, when the vehicle V is traveling while maintaining the calculated lane deviation angle, it is predicted whether it crosses the boundary that demarcates the lane L. In addition, the tangent direction of the lane L is calculated based on the positional relationship between the boundary and the vehicle V.

[0042] The driving assistance device 14 calculates, for example, Figure 2 The lane deviation angle formed by the line C1 parallel to the traveling direction of the vehicle V and the tangent line C2 of the boundary line B1 at the driving position of the vehicle V is obtained to obtain the distance D in the width direction between the vehicle V and the boundary line B1. An example of the lane deviation angle is Figure 2Indicated as α in the figure. Then, the deviation of the vehicle V is predicted based on the lane deviation angle and the distance D. The lane deviation angle is an angle within the range in which the vehicle V can travel along the lane L. When the distance D becomes longer (that is, the vehicle V is away from the boundary line B1), the driving assistance device 14 predicts that the vehicle V will not deviate from the lane L. In contrast, when the lane deviation angle of the vehicle V is greater than or less than the range in which the vehicle V can travel along the lane L (that is, when the lane deviation angle required for the steering angle is too large or too small), when the distance D becomes shorter, etc. (that is, when the vehicle V is close to the boundary line B1), it is predicted that the vehicle V will deviate from the lane L. In addition, the tangent C2 to the boundary line B1 is, for example, set to the tangent at the point on the boundary line B1 that is closest to the body of the vehicle V.

[0043] In addition, the driving assistance device 14 may also determine whether the vehicle V enters a curve, and predict the deviation of the vehicle V if it is determined that the vehicle V enters a curve. For example, when the vehicle V is traveling straight, when the boundary line of the lane L in front of the vehicle V is curved, it is determined that the vehicle V enters a curve, and when the boundary line is not curved, it is determined that the vehicle V does not enter a curve. As an alternative or in addition to this, the driving assistance device 14 may also obtain the current position of the vehicle V from a GPS unit not shown in the figure, obtain the road information around the vehicle V from the map information not shown in the figure, and determine whether the vehicle V enters a curve based on the road information in front of the vehicle V. In addition, the determination of entering a curve is not a necessary configuration of the present invention, and may be set as needed.

[0044] exist Figure 2 In the driving scenario shown, the driver turns the steering wheel too far to the left, so the lane deviation angle of the vehicle V is larger than the range in which the vehicle V can travel along the lane L. Therefore, when the vehicle V travels while maintaining the lane deviation angle, it crosses the boundary line B1 that delimits the lane L and heads outside the lane L, so the driving assistance device 14 predicts that the vehicle V deviates from the lane L. Then, when it is predicted that the vehicle V deviates from the lane L, the steering control function of the driving assistance device 14 is activated to perform steering control.

[0045] The acquisition unit 23 has a function of acquiring a deviation direction of the vehicle V from the lane L. The deviation direction of the vehicle V refers to the direction in which the vehicle V is directed when the vehicle V deviates from the lane L in which it is traveling, and indicates that the vehicle V deviates to the right or left side relative to the traveling direction. That is, the deviation direction indicates that, when it is predicted that the vehicle V deviates from the lane L in which it is traveling, the vehicle V crosses over one of the boundaries on the right side of the traveling direction and the boundaries on the left side of the traveling direction among the boundaries defining the lane L. When the deviation direction is the left direction, the vehicle V deviates from the lane L by crossing the boundary on the left side of the traveling direction, and when the deviation direction is the right direction, the vehicle V deviates from the lane L by crossing the boundary on the right side of the traveling direction.

[0046] The driving assistance device 14 acquires the deviation direction of the vehicle V from the lane L based on the information of the traveling direction of the vehicle V used when the vehicle V is predicted to deviate from the lane L. For example, when the vehicle V is predicted to deviate from the lane L, if the traveling direction of the vehicle V is to the left front or left side of the vehicle V, the deviation direction is the left direction, and if the traveling direction of the vehicle V is to the right front or right side of the vehicle V, the deviation direction is the right direction.

[0047] The control unit 24 has a function of performing steering control so that the vehicle V does not deviate from the lane L. The steering control so that the vehicle V does not deviate from the lane L means that the steering wheel is rotated by the steering mechanism to increase or decrease the steering angle in order to make the traveling direction of the vehicle V along the lane L. The driving assistance device 14 ensures the width direction distance between the vehicle V and the boundary of the lane L, and activates the steering actuator via the steering control device 13 so that the lane yaw angle of the vehicle V becomes an angle within the range in which the vehicle V can travel along the lane L, and adjusts the steering angle by rotating the steering wheel to the left or right (that is, turning the steering wheel toward the target direction). The above range is set to an appropriate range based on the travel speed of the vehicle V and the curvature of the lane L.

[0048] In addition, the driving assistance device 14 may also control the travel speed of the vehicle V using a speed control device not shown in the figure during the execution of the steering control. In the case where the travel speed control is not performed, the travel speed of the vehicle V is controlled by the driver's operation. In addition, the steering angle may be adjusted by operating the steering actuator via the steering control device 13 to rotate the steering wheel to the left or right. In the case of a steer-by-wire system in which the mechanism for steering the steering wheel is mechanically separated from the steering wheel, it is possible to adjust one or both of the steering angle of the steering actuator mounted on the steering rack or pinion of the mechanism for steering the steering wheel and the steering angle of the steering actuator mounted on the column shaft of the steering wheel.

[0049] exist Figure 2 In the driving scenario shown, it is assumed that when the vehicle V is traveling at the position P1, it is predicted that the vehicle V will deviate to the left from the lane L. In this case, the driving assistance device 14 acquires the deviation direction through the function of the acquisition unit 23, and performs steering control through the function of the control unit 24 to avoid deviation from the lane L. Specifically, since the deviation direction is the left direction, an instruction to rotate the steering wheel to the right direction is output to the steering control device 13.

[0050] Use the timing diagram to explain in detail Figure 2 Steering control performed in the driving scenario shown. Figure 2Five timing diagrams are shown in FIG. 1 , which are, from top to bottom: (1) a diagram showing the state of the steering control, (2) a diagram showing the deviation direction of the vehicle V, (3) a diagram showing the steering angle command value in the steering control, (4) a diagram showing the steering angle, and (5) a diagram showing the distance D in the width direction between the vehicle V and the boundary line B1. The horizontal axis of each diagram represents time, which corresponds to Figure 2 Elapsed time in the driving scenario shown above.

[0051] The diagram of the state of the steering control is a diagram showing whether the steering control is in an effective (ON) state or an ineffective (OFF) state, and takes a value of "effective (ON)" if the steering control is in an effective state, and takes a value of "ineffective (OFF)" if the steering control is in an ineffective state. In the diagram of the deviation direction of the vehicle V, a value of "left deviation" or "right deviation" is taken according to the deviation direction of the vehicle V, and a value of "no deviation" is taken when it is predicted that the vehicle V will not deviate from the lane L.

[0052] The diagram of the steering angle command value is a diagram showing the command value of the steering angle output from the driving assistance device 14 to the steering control device 13 during the steering control. In the diagram of the steering angle command value and the diagram of the steering angle, rotation in the left direction is represented by a positive value, and rotation in the right direction is represented by a negative value. Figure 2 In the driving scenario shown, the steering wheel is connected to the steering wheel, and the steering angle also changes with the steering angle. The following describes the processing in the steering control using a timing chart.

[0053] exist Figure 2 In the driving scenario shown, it is predicted that the vehicle V will deviate from the lane L to the left when the vehicle V is traveling at the position P1. Therefore, as shown in the figure of the steering control state, the steering control becomes effective (ON) at the position P1. Figure 2 In the driving scene shown, since the vehicle V is heading to the left front, the deviation direction is determined to be the left direction as shown in the figure of the deviation direction of the vehicle V. The driving assistance device 14 obtains information indicating that the deviation direction is the left direction.

[0054] Since the deviation direction of the vehicle V is to the left, the driving assistance device 14 outputs an instruction to the steering control device 13 to rotate the steering wheel to the right so that the vehicle V can travel along the lane L. Specifically, as shown in the figure of the steering angle instruction value, an instruction having an instruction value for reducing the steering angle in the left direction is output. As a result, the steering wheel is rotated to the right direction, and the steering angle in the left direction becomes smaller as shown in the figure of the steering angle. In addition, in the case of a wire steering method, the steering angle instruction value becomes a steering angle instruction value, and the steering wheel is rotated by the steering mechanism according to the instruction value. At the same time, the target steering angle is set, and the steering wheel is rotated by the steering gear actuator installed on the steering gear column shaft.

[0055] exist Figure 2 In the driving scenario, the steering wheel is rotated to the right at a certain angular velocity by the steering control device 13. When the vehicle V is traveling at position P2, the lane yaw angle of the vehicle V becomes an angle within the range where the vehicle V can travel along the lane L. In this case, when the driving position of the vehicle V reaches position P2, the driving assistance device 14 outputs an instruction to the steering control device 13 to stop the rotation of the steering wheel and maintain the steering angle. As a result, the rotation of the steering wheel to the right is stopped, and the steering angle is maintained as shown in the figure of the steering angle. The vehicle V maintains Figure 2 At the steering angle shown, the lane deviation angle of the vehicle V changes from decreasing to increasing, and the vehicle V travels to a position P3 where the lane deviation angle starts to increase. The position P3 is also the position where the vehicle V is closest to the boundary line B1 defining the lane L.

[0056] As shown in the diagram of the distance D in the width direction, the distance between the vehicle V and the boundary line B1 gradually decreases while the vehicle V travels from the position P1 to the position P3, so the driving assistance device 14 continues to repeatedly perform the deviation determination of the vehicle V. During the deviation determination, as shown in the diagram of the deviation direction of the vehicle V, the deviation direction takes a value of deviation to the left. In addition, the steering wheel rotation does not necessarily need to be stopped at the position P2.

[0057] After passing the position P3 where the lane deviation angle of the vehicle V starts to increase, the distance D between the vehicle V and the boundary line B1 gradually increases. When the vehicle V continues to travel away from the boundary line B1 after passing the position P3 and determines that the vehicle V has left the driving state of deviating from the lane L, the driving assistance device 14 predicts that the vehicle V will not deviate from the lane L. For example, when the vehicle V travels to the position P4 after a predetermined time has passed after passing the position P3, the driving assistance device 14 predicts that the vehicle V will not deviate from the lane L. In this case, the driving assistance device 14 ends the steering control at the position P4 and switches to driving based on the steering operation of the driver.

[0058] As before passing through the position P3 , if the lane deviation angle of the vehicle V is controlled to be maintained within the range in which the vehicle V can travel along the lane L, the steering wheel may be turned to the left after passing through the position P3 . Figure 6 is a diagram showing a steering control according to a comparative example of the present invention, Figure 6 The driving scenario shown is Figure 2 In the driving scenario shown, control is performed so that the lane deviation angle of the vehicle V is maintained within the above-mentioned range even after the vehicle V passes the position P3.

[0059] like Figure 6As shown in the figure of the steering angle command value, in the steering control of the comparative example, after passing the position P3, an instruction to rotate the steering wheel to the left is output to the steering control device 13, and the steering angle in the left direction is increased according to the command value. Moreover, at position Px, which has passed a predetermined time after passing the position P3, the distance D between the vehicle V and the boundary line B1 is increased, and it is predicted that the vehicle V does not deviate from the lane L. In this case, the steering control is ended at the position Px, and as shown in the figure of the state of the steering control, the state of the steering control becomes invalid (OFF). In addition, the deviation direction takes a value that does not deviate. In the case where the driver does not start the steering operation after the steering control is ended at the position Px, as shown in Figure 6 As shown in FIG. 1 , the steering wheel is rotated to the right by the self-aligning torque. If the vehicle continues to travel in this state, the steering angle becomes 0° when the vehicle V is traveling at the position Py, and the rotation of the steering wheel stops.

[0060] exist Figure 6 In the steering control shown, the steering wheel rotates to the left direction during the period from the position P3 to the position Px, and the steering wheel rotates to the right direction during the period from the position Px to the position Py. In this way, if the left direction rotation based on the steering control is performed before the right direction rotation based on the automatic self-aligning torque, the driver will mistakenly believe that the right direction rotation based on the automatic self-aligning torque is a series of steering controls that are continuous after the left direction rotation based on the steering control. In addition, the driver continues to perform the steering control after a predetermined time has passed after passing the position P3, and even after the steering wheel stops rotating after passing the position Py, the driver expects the steering wheel to rotate automatically again. Therefore, even if the vehicle V passes the position Py, the driver will not start the steering operation, but will start the steering operation after the vehicle V approaches the boundary line B2. In this case, since the vehicle V is turned to the left direction in a relatively short time, the behavior of the vehicle V will change significantly.

[0061] Therefore, the driving assistance device 14 of the present embodiment acquires the turning direction of the vehicle V through the function of the acquisition unit 23, and determines whether the deviation direction of the vehicle V and the turning direction are the same direction through the function of the control unit 24. Then, when it is determined that the deviation direction and the turning direction are the same direction, the steering control is performed so that the steering wheel is not rotated in the deviation direction. That is, when the vehicle V deviates in the turning direction, the steering wheel is not rotated in the deviation direction but only in the direction opposite to the deviation direction from the start to the end of the steering control.

[0062] In contrast, when it is determined that the deviation direction and the turning direction are not the same direction, normal steering control is performed to suppress deviation from lane L. When vehicle V deviates in the direction opposite to the turning direction, since the steering angle is not sufficient to turn along lane L, vehicle V increases the steering angle in a manner opposite to the predicted deviation direction. At the moment when the lane yaw angle begins to increase, the steering angle of vehicle V becomes an angle larger than the range in which vehicle V can travel along lane L. Therefore, the steering angle is reduced to allow vehicle V to travel along lane L. That is, in a driving scenario where the deviation direction and the turning direction are different, the steering angle is increased only once and then reduced, and steering control to increase the steering angle again after reducing the steering angle is not performed, so that the driver does not mistakenly recognize the rotation of the steering wheel based on the automatic self-aligning torque as the rotation based on the steering control.

[0063] The driving assistance device 14 obtains whether the turning direction of the vehicle V is the left direction or the right direction based on the detection result of the steering angle sensor. The driving assistance device 14 may obtain the deviation direction and the turning direction at the same time, or may obtain one of the deviation direction and the turning direction first. In addition, the turning direction of the vehicle V may be identified based on the yaw rate obtained from the yaw rate sensor, the lane deviation angle obtained from the detection result of the camera device 11, the lateral acceleration obtained from the acceleration sensor, and the like.

[0064] exist Figure 2 In the driving scenario shown in FIG. 1 , as shown in the diagram of the steering angle command value, after the vehicle V passes through position P3, the same steering angle command value is output as the command value. Therefore, the steering wheel does not rotate and the steering angle is maintained. Then, at position P4 after a predetermined time has passed after passing position P3, the steering control ends and the state of the steering control becomes invalid (OFF). If the driver does not start the steering operation after the steering control ends at position P4, as shown in FIG. Figure 2 As shown in FIG. 1 , the steering wheel is rotated to the right by the self-aligning torque. If the vehicle continues to travel in this state, the steering angle becomes 0° when the vehicle V is traveling at the position P5, and the rotation of the steering wheel stops.

[0065] Figure 2 In the steering control shown, the steering wheel does not rotate in the left direction which is the same as the deviation direction during the period from the position P3 to the position P4. Therefore, the driver recognizes that the steering control has been completed when the right rotation based on the automatic self-aligning torque is started, and can start the steering operation. In addition, even if the driver does not notice that the steering control has been completed and the vehicle V travels to the position P5, the driver does not expect the steering wheel to rotate automatically again, unlike the steering control of the comparative example. Therefore, the steering operation can be quickly started when the vehicle V passes the position P5.

[0066] In addition, the driving assistance device 14 may also stop the rotation of the steering wheel and maintain the steering angle at a certain time from the time when the lane deviation angle starts to increase until the increment of the lane deviation angle reaches a specified angle. In this case, the steering control ends with the steering wheel stopped. The specified angle is, for example, 0.05 to 0.2°. Alternatively, the driving assistance device 14 may stop the rotation of the steering wheel and maintain the steering angle at a certain time from the time when the lane deviation angle starts to increase until a certain time has passed. In this case, the steering control ends with the steering wheel stopped. The certain time is, for example, 0.1 to 1 [seconds].

[0067] In addition, Figure 2 In the driving scene shown, the steering angle is maintained from the position P2 where the lane deviation angle of the vehicle V becomes an angle within the range where the vehicle V can travel along the lane L to the position P3 where the lane deviation angle of the vehicle V starts to increase, but the steering angle does not necessarily need to be maintained between the position P2 and the position P3, and the steering angle may be changed between the position P2 and the position P3. In addition, these exemplified steering controls are not essential structures of the present invention, and may be provided as needed.

[0068] Next, use Figure 3 , yes Figure 2 The steering control in the case where the vehicle V is traveling at a faster speed in the illustrated driving scenario will be described. Figure 3 The driving scenario shown is similar to Figure 2 The driving scenario shown is the same, except that the vehicle V is traveling at a faster speed than Figure 2 The driving scene shown is fast. When tracking a certain driving trajectory, the faster the driving speed, the larger the steering angle needs to be. Figure 3 In the driving scenario shown, the steering angle is Figure 2 The driving scene shown is large. When the steering control is terminated in the state where the steering angle is large, the rotation speed of the steering wheel becomes faster due to the self-aligning torque, and the behavior of the vehicle V changes significantly.

[0069] Then, the driving assistance device 14 obtains the running speed of the vehicle V, and when the running speed of the vehicle V is equal to or lower than a predetermined speed, the steering wheel is rotated in the direction opposite to the deviation direction, and the lane deviation angle of the vehicle V is calculated. Then, at a certain time point from when the lane deviation angle starts to increase until the increase in the lane deviation angle reaches a predetermined angle, the steering control is terminated by stopping the rotation of the steering wheel while maintaining the steering angle.

[0070] On the other hand, when the running speed of the vehicle V is faster than the prescribed speed, the steering wheel is rotated in the direction opposite to the deviation direction, and the lane deviation angle of the vehicle V is calculated. Then, at a certain time from when the lane deviation angle starts to increase until the increment of the lane deviation angle reaches the prescribed angle, the rotation of the steering wheel is stopped, and the steering angle is maintained. Furthermore, at a prescribed time after the maintenance of the steering angle begins, the steering wheel is rotated in the direction opposite to the deviation direction, and the steering control is ended in the state where the steering wheel is rotated in the direction opposite to the deviation direction. As a result, the steering angle can be reduced before the steering control ends, so that the behavior of the vehicle V can be suppressed from being greatly changed by the self-aligning torque.

[0071] The prescribed speed may be set to an appropriate value within a range where the change in movement due to the self-aligning torque does not cause discomfort to the occupants of the vehicle V. In addition, the prescribed time is a time from the start of maintaining the steering angle to the end of the steering control, for example, a time when the vehicle V passes a position where the lane deviation angle starts to increase. In addition, the driving assistance device 14 may set the speed of rotating the steering wheel in the direction opposite to the deviation direction to be greater as the driving speed is faster than the prescribed speed.

[0072] exist Figure 3 In the driving scenario shown, the driving assistance device 14 performs the same operation as Figure 2 The same steering control as shown in FIG. 1 is used for the steering control. After the vehicle V passes position P3, as shown in the figure of the steering angle command value, a command value for reducing the left steering angle is output. Therefore, the steering wheel rotates in the right direction at a constant angular speed until it reaches position P4, which is a predetermined time after passing position P3. If the driver does not start the steering operation after the steering control ends at position P4 and the state of the steering control becomes invalid (OFF), as shown in FIG. Figure 3 As shown in FIG. 1 , the steering wheel is rotated to the right by the self-aligning torque. If the vehicle continues to travel in this state, the steering angle becomes 0° when the vehicle V is traveling at the position P5, and the rotation of the steering wheel stops.

[0073] Next, use Figure 4 The curvature ratio Figure 2 The shown curve is a steering control when driving on a large curve. Figure 4 The driving scenario shown is similar to Figure 2 The driving scenario shown is the same, except that the curvature of the curve is Figure 2 The curve shown is different in that it is larger. Figure 4 In the driving scene shown, the vehicle V is traveling in a lane La in the direction of arrow Xa, and the lane La is defined by a boundary line B1a on the left side of the vehicle V in the traveling direction and a boundary line B2a on the right side of the vehicle V in the traveling direction.

[0074] exist Figure 4 In the driving scenario shown, due to the curvature of the curve Figure 2 The driving scene shown is large, so if Figure 2 If the driving speed is the same as the driving scenario shown in the figure, the steering angle needs to be greater than Figure 2 Therefore, in Figure 4 In the driving scenario shown, the steering angle is Figure 2 The driving scene shown is large. In this case, Figure 3 Similarly to the driving scenario shown, if the steering control is terminated with the steering angle being large, the behavior of the vehicle V will be greatly changed due to the self-aligning torque.

[0075] Then, the driving assistance device 14 obtains the curvature of the lane La, and when the curvature of the lane La is less than a predetermined value, the steering wheel is rotated in the direction opposite to the departure direction, and the lane deviation angle of the vehicle V is calculated. Then, at a certain time from when the lane deviation angle starts to increase until the increase in the lane deviation angle reaches a predetermined angle, the steering control is terminated while the steering angle is maintained.

[0076] On the other hand, when the curvature of the lane La is greater than a predetermined value, the steering wheel is rotated in the direction opposite to the departure direction, and the lane deviation angle of the vehicle V is calculated. Then, at a certain time from when the lane deviation angle starts to increase until the increment of the lane deviation angle reaches a predetermined angle, the rotation of the steering wheel is stopped and the steering angle is maintained. Furthermore, at a predetermined time after the start of maintaining the steering angle, the steering wheel is rotated in the direction opposite to the departure direction, and the steering control is ended in a state where the steering wheel is rotated in the direction opposite to the departure direction. As a result, the steering angle can be reduced before the steering control ends, so that the behavior of the vehicle V can be suppressed from being greatly changed by the self-aligning torque.

[0077] The predetermined value may be set to an appropriate value within a range where the change in movement due to the self-aligning torque does not cause discomfort to the occupants of the vehicle V. As described above, the predetermined time is a time during the period from the time when the steering angle is maintained to the time when the steering control is terminated, for example, the time when the vehicle V passes the position where the lane yaw angle begins to increase. In addition, when the curvature of the lane La is greater than the predetermined value, the driving assistance device 14 may set the speed of rotating the steering wheel in the direction opposite to the departure direction to be greater as the curvature is greater.

[0078] exist Figure 4 In the driving scenario shown, the driving assistance device 14 performs the same operation as Figure 2The same steering control as shown in FIG. 1 is used for the steering control. After the vehicle V passes position P3a, as shown in the figure of the steering angle command value, a command value for reducing the left steering angle is output. Therefore, the steering wheel rotates to the right and continues to rotate at a certain angular speed to position P4a after a predetermined time has passed through position P3a. If the driver does not start the steering operation after the steering control ends at position P4a and the state of the steering control becomes invalid (OFF), as shown in FIG. Figure 4 As shown in FIG. 1 , the steering wheel is rotated to the right by the self-aligning torque. If the vehicle continues to travel in this state, the steering angle becomes 0° when the vehicle V is traveling at the position P5a, and the rotation of the steering wheel stops.

[0079] In addition, obtaining the curvature of lane La, obtaining the driving speed of vehicle V, rotating the steering wheel in the direction opposite to the departure direction from a specified time after starting to maintain the steering angle, ending the steering control with the steering wheel rotating in the direction opposite to the departure direction, ending the steering control while maintaining the steering angle, rotating the steering wheel in the direction opposite to the departure direction, and stopping the rotation of the steering wheel to maintain the steering angle at a certain time from the start of the increase in the lane deviation angle until the increment of the lane deviation angle becomes a specified angle. These are not necessary components of the present invention and may be added as needed.

[0080] (Processing in driver assistance systems)

[0081] Reference Figures 5A to 5C , describing the order in which the driving assistance device 14 processes information. Figures 5A to 5C This is an example of a flowchart showing information processing executed in the driving assistance system 1 of the present embodiment. The processing described below is executed by the CPU 141 as a processor of the driving assistance system 14 at predetermined time intervals.

[0082] First, in Figure 5A In step S1, the boundary of the lane L in which the vehicle V is traveling is detected based on the detection result of the camera 11 by the function of the recognition unit 21, and in the following step S2, it is determined whether the vehicle has entered a curve by the function of the prediction unit 22. If it is determined that the vehicle V has not entered a curve, the program proceeds to step S6, and the function of the assistance unit 2 is used to determine whether the vehicle V has arrived at the destination. If it is determined that the vehicle has arrived at the destination, the program execution is terminated, and if it is determined that the vehicle V has not arrived at the destination, the program proceeds to step S1.

[0083] In step S2, if it is determined that the vehicle V has entered a curve, the process proceeds to step S3, and the function of the prediction unit 22 is used to obtain the traveling direction of the vehicle V. In the following step S4, it is predicted whether the vehicle V has deviated from the lane L. If it is predicted that the vehicle V has not deviated from the lane L, the process proceeds to step S5, and it is determined whether the vehicle V has passed the curve. If the vehicle V is traveling straight and the boundary of the lane L is not curved, it is determined that the vehicle has passed the curve, and the process proceeds to step S6. If it is determined that the vehicle has not passed the curve, the process proceeds to step S3.

[0084] In step S4, if it is predicted that the vehicle V deviates from the lane L, the vehicle enters the lane L. Figure 5B In step S11, the steering control is started by using the function of the control unit 24. In the following step S12, the deviation direction of the vehicle is obtained by using the function of the acquisition unit 23. In step S13, the turning direction of the vehicle V is obtained. In the following step S14, it is determined whether the deviation direction and the turning direction are the same direction. If the deviation direction and the turning direction are different directions, the process proceeds to step S15. In step S15, the normal steering control for suppressing deviation from the lane L is performed, and the process proceeds to step S14. Figure 5A Step S6.

[0085] On the other hand, when the deviation direction and the turning direction are the same, the process proceeds to step S16, and the steering actuator is actuated via the steering control device 13 to rotate the steering wheel in the direction opposite to the deviation direction. In the following step S17, the lane deviation angle is calculated, and in step S18, it is determined whether the lane deviation angle has increased. When it is determined that the lane deviation angle has not increased, the process proceeds to step S16, and the steering control device 13 is used to rotate the steering wheel in the direction opposite to the deviation direction. On the other hand, when it is determined that the lane deviation angle has increased (or has begun to increase), the process proceeds to step S19, and the steering wheel is stopped from rotating until the increment of the lane deviation angle reaches a predetermined angle, and the steering angle is maintained.

[0086] Enter Figure 5C In step S20, the curvature of the lane L is acquired by the function of the acquisition unit 23, and in the following step S21, the function of the control unit 24 determines whether the curvature is below the prescribed value. If the curvature is below the prescribed value, the process proceeds to step S22, and if the curvature is greater than the prescribed value, the process proceeds to step S24. In step S22, the driving speed of the vehicle V is acquired, and in step S23, it is determined whether the driving speed of the vehicle V is below the prescribed speed. If the driving speed is below the prescribed speed, the process proceeds to step S26, and if the driving speed is faster than the prescribed speed, the process proceeds to step S24.

[0087] In step S24, the function of the control unit 24 determines whether the specified time has been reached. If it is determined that the specified time has not been reached, step S24 is repeated until the specified time has been reached. In contrast, if it is determined that the specified time has been reached, the process proceeds to step S25, and the steering actuator is activated via the steering control device 13 to start rotating the steering wheel in the direction opposite to the deviation direction. In the following step S26, it is determined whether a specified time has passed since the lane yaw angle began to increase. If it is determined that the specified time has not passed, step S26 is repeated. If it is determined that the specified time has passed, the process proceeds to step S27 to end the steering control. Then, the process proceeds to step S26. Figure 5A Step S6.

[0088] In addition, each step of step S20 to step S25 is not a necessary step, and can be added or omitted as needed. Specifically, only steps S20 and S21 can be omitted, only steps S22 and S23 can be omitted, or all steps S20 to S25 can be omitted.

[0089] (Embodiment of the present invention)

[0090] As described above, according to the present embodiment, there is provided a driving assistance method, in which, in the driving assistance method executed by a processor, the processor predicts whether a vehicle V traveling by a steering operation of a driver deviates from a lane L in which the vehicle V is traveling, and when it is predicted that the vehicle V deviates from the lane L, the processor acquires a deviation direction of the vehicle V from the lane L and a turning direction of the vehicle V, and determines whether the deviation direction and the turning direction are the same direction, and when it is determined that the deviation direction and the turning direction are the same direction, performs steering control so as not to rotate the steering wheel of the vehicle V in the deviation direction and not to deviate the vehicle V from the lane L. This can suppress a situation in which the driver mistakenly recognizes the end of the steering control and switches the timing based on the steering operation of the driver.

[0091] In addition, according to the driving assistance method of the present embodiment, when the processor determines that the deviation direction and the turning direction are the same direction, the processor rotates the steering wheel in the direction opposite to the deviation direction, and maintains the rotation angle of the steering wheel from a certain time point during the period from when the lane deviation angle, which is an angle formed by the traveling direction of the vehicle V and the tangent direction of the lane L at the position where the vehicle V is traveling on the lane L, starts to increase until the increase in the lane deviation angle reaches a predetermined angle. In this way, it is possible to suppress the vehicle V from deviating in the direction opposite to the deviation direction.

[0092] In addition, according to the driving assistance method of the present embodiment, the processor acquires the curvature of the lane L, rotates the steering wheel in the direction opposite to the departure direction when the curvature is less than a predetermined value, maintains the rotation angle of the steering wheel from a certain time during the period from when the lane deviation angle, which is an angle formed by the traveling direction of the vehicle V and the tangent direction of the lane L at the position of the vehicle V traveling on the lane L, starts to increase until the increase in the lane deviation angle reaches a predetermined angle, and terminates the steering control with the rotation angle maintained, rotates the steering wheel in the direction opposite to the departure direction when the curvature is greater than the predetermined value, maintains the rotation angle of the steering wheel from a certain time during the period from when the lane deviation angle starts to increase until the increase in the lane deviation angle reaches the predetermined angle, rotates the steering wheel in the direction opposite to the departure direction from a predetermined time after the rotation angle starts to be maintained, and terminates the steering control with the steering wheel rotated in the direction opposite to the departure direction. In this way, the rotation speed of the steering wheel based on the self-aligning torque can be controlled, and the behavior change of the vehicle V can be suppressed.

[0093] In addition, according to the driving assistance method of this embodiment, when the curvature is greater than the predetermined value, the processor sets the speed of rotating the steering wheel in the direction opposite to the deviation direction to be greater as the curvature is greater. Thus, the rotation speed of the steering wheel based on the self-aligning torque can be controlled, and the behavior change of the vehicle V can be suppressed.

[0094] In addition, according to the driving assistance method of the present embodiment, the processor acquires the traveling speed of the vehicle V, rotates the steering wheel in the direction opposite to the deviation direction when the traveling speed is equal to or lower than a predetermined speed, maintains the rotation angle of the steering wheel from a certain time during a period from when a lane deviation angle, which is an angle formed by a traveling direction of the vehicle V and a tangent direction of the lane La at a position on the lane La where the vehicle V is traveling, starts to increase until an increase in the lane deviation angle becomes a predetermined angle, and terminates the steering control with the rotation angle maintained; when the traveling speed is faster than the predetermined speed, rotates the steering wheel in the direction opposite to the deviation direction, maintains the rotation angle of the steering wheel from a certain time during a period from when the lane deviation angle starts to increase until an increase in the lane deviation angle becomes the predetermined angle, and rotates the steering wheel in the direction opposite to the deviation direction from a predetermined time after the rotation angle starts to be maintained, and terminates the steering control with the steering wheel rotated in the direction opposite to the deviation direction. As a result, the rotation speed of the steering wheel based on the self-aligning torque can be controlled, and changes in the behavior of the vehicle V can be suppressed.

[0095] In addition, according to the driving assistance method of this embodiment, when the driving speed is faster than the predetermined speed, the processor sets the speed of rotating the steering wheel in the direction opposite to the deviation direction to be greater as the driving speed is faster. Thus, the rotation speed of the steering wheel based on the self-aligning torque can be controlled, and the behavior change of the vehicle V can be suppressed.

[0096] In addition, according to the present embodiment, there is provided a driving assistance device 14, comprising: a prediction unit 22 that predicts whether a vehicle V traveling by a driver's steering operation deviates from a lane L in which the vehicle V is traveling; an acquisition unit 23 that, when the prediction unit 22 predicts that the vehicle V deviates from the lane L, acquires a deviation direction of the vehicle V from the lane L and a turning direction of the vehicle V; and a control unit 24 that determines whether the deviation direction and the turning direction are the same direction, and, when it is determined that the deviation direction and the turning direction are the same direction, performs steering control that does not rotate the steering wheel of the vehicle V in the deviation direction and does not deviate the vehicle V from the lane L. This can prevent the driver from erroneously recognizing the timing of the end of the steering control and switching to the timing based on the driver's steering operation.

[0097] Explanation of symbols

[0098] 1: Driving assistance system, 11: Camera device, 12: Vehicle status detection device, 13: Steering control device, 14: Driving assistance device, 141: CPU (processor), 142: ROM, 143: RAM

[0099] 2: auxiliary unit, 21: identification unit, 22: prediction unit, 23: acquisition unit, 24: control unit

[0100] B1, B2, B1a, B2a: boundary line, C1: line parallel to the front-rear direction of the vehicle, C2: tangent line of the boundary, D: distance, L, La: lane, P1~P5, P1a~P5a, Px, Py: position, V: vehicle, X, Xa: arrows, α: lane yaw angle.

Claims

1. A driving assistance method, executed by a processor, wherein: The processor performs the following processing: Predicting whether the vehicle will deviate from the lane it is traveling in due to the driver's steering operation. When it is predicted that the vehicle deviates from the lane, obtaining a deviation direction of the vehicle from the lane and a turning direction of the vehicle, determining whether the deviation direction and the turning direction are the same direction, When it is determined that the deviation direction and the turning direction are the same direction, steering control is performed so as not to rotate the steering wheel of the vehicle in the deviation direction and to prevent the vehicle from deviating from the lane.

2. The driving assistance method according to claim 1, wherein: The processor performs the following processing: When it is determined that the deviation direction and the turning direction are the same direction, the steering wheel is rotated in a direction opposite to the deviation direction. The steering wheel rotation angle is maintained from a certain point in time during a period from when a lane yaw angle, which is an angle formed by a traveling direction of the vehicle and a tangent direction of the lane at a position on the lane where the vehicle is traveling, starts to increase until an increase in the lane yaw angle reaches a predetermined angle.

3. The driving assistance method according to claim 1 or 2, wherein: The processor performs the following processing: Get the curvature of the lane, When the curvature is less than a predetermined value, rotating the steering wheel in a direction opposite to the deviation direction, maintaining the steering wheel rotation angle from a certain point in time during a period from when a lane yaw angle, which is an angle formed by a traveling direction of the vehicle and a tangent direction of the lane at a position on the lane where the vehicle is traveling, starts to increase until an increase in the lane yaw angle reaches a predetermined angle, ending the steering control while maintaining the rotation angle, When the curvature is greater than the specified value, rotating the steering wheel in a direction opposite to the deviation direction, maintaining the rotation angle of the steering wheel from a certain point in time from when the lane deviation angle starts to increase until the increase in the lane deviation angle reaches the predetermined angle, From a predetermined time after the start of maintaining the rotation angle, the steering wheel is rotated in a direction opposite to the deviation direction; The steering control is ended in a state where the steering wheel is rotated in a direction opposite to the deviation direction.

4. The driving assistance method according to claim 3, wherein: When the curvature is greater than the predetermined value, the processor sets a higher speed at which the steering wheel is rotated in a direction opposite to the deviation direction as the curvature increases.

5. The driving assistance method according to any one of claims 1 to 4, wherein: The processor performs the following processing: Obtain the driving speed of the vehicle, When the travel speed is below a predetermined speed, rotating the steering wheel in a direction opposite to the deviation direction, maintaining the steering wheel rotation angle from a certain point in time during a period from when a lane yaw angle, which is an angle formed by a traveling direction of the vehicle and a tangent direction of the lane at a position on the lane where the vehicle is traveling, starts to increase until an increase in the lane yaw angle reaches a predetermined angle, ending the steering control while maintaining the rotation angle, When the travel speed is faster than the prescribed speed, rotating the steering wheel in a direction opposite to the deviation direction, maintaining the rotation angle of the steering wheel from a certain point in time from when the lane deviation angle starts to increase until the increase in the lane deviation angle reaches the predetermined angle, From a predetermined time after the start of maintaining the rotation angle, the steering wheel is rotated in a direction opposite to the deviation direction; The steering control is ended in a state where the steering wheel is rotated in a direction opposite to the deviation direction.

6. The driving assistance method according to claim 5, wherein: When the traveling speed is faster than the predetermined speed, the processor sets a speed at which the steering wheel is rotated in a direction opposite to the deviation direction to be greater as the traveling speed is higher.

7. A driving assistance device comprising: a prediction unit that predicts whether the vehicle traveling by the driver's steering operation deviates from the lane in which it is traveling; an acquisition unit configured to acquire a deviation direction of the vehicle from the lane and a turning direction of the vehicle when the prediction unit predicts that the vehicle deviates from the lane; A control unit determines whether the deviation direction and the turning direction are the same direction, and when it is determined that the deviation direction and the turning direction are the same direction, performs steering control so as not to rotate the steering wheel of the vehicle in the deviation direction and prevent the vehicle from deviating from the lane.

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