JP2024060411A - Collision avoidance support device, collision avoidance support method, and collision avoidance support program - Google Patents

Abstract

[Problem] To provide a collision avoidance support device, collision avoidance support method, and collision avoidance support program that are improved so that even when a target trajectory is set so that the vehicle deviates from the lane, the driver does not feel uneasy because the steering angle is greater than the intended steering angle. [Solution] A collision avoidance support device including a control unit (driving support ECU) configured to set a target trajectory for traveling while avoiding a collision with an obstacle (S40) when it is determined that it is necessary to avoid a collision with an obstacle (S20), and to control an automatic steering device so that the vehicle travels along the target trajectory (S80 to S100), in which, when the control unit determines that the maximum value (θamax) of the magnitude of the steering angle by the automatic steering for traveling along the target trajectory is equal to or greater than a reference value (θc) (S50), it suspends the execution of control of the automatic steering device (S120, S130) until it is determined that the driver has started steering back (S150). [Selected Figure] Figure 2

Description

The present invention relates to a collision avoidance support device, a collision avoidance support method, and a collision avoidance support program for vehicles such as automobiles.

When it is necessary to avoid a collision with an obstacle in front of the vehicle, the collision avoidance assistance device sets a target trajectory for avoiding the collision with the obstacle, calculates a target steering angle for driving the vehicle along the target trajectory, and controls the automatic steering device so that the steering angle becomes the target steering angle.

For example, the following Patent Document 1 describes a collision avoidance support device that, if the driver steers the vehicle away from an obstacle and it is estimated that the vehicle will not depart from the lane, stops automatic steering to keep the vehicle on a target trajectory even after the steering operation ends.

JP 2021-126935 A

[Problem to be solved by the invention]
In a conventional collision avoidance support device such as the collision avoidance support device described in the above Patent Document 1, the target trajectory is set so that the vehicle does not deviate from the lane. In order to improve the performance of collision avoidance with an obstacle, for example, when the obstacle is large, it is possible to set the target trajectory so that the vehicle deviates from the lane as necessary.

However, when the target trajectory is set so that the vehicle deviates from the lane, the inclination angle of the vehicle with respect to the lane becomes larger compared to when the target trajectory is set so that the vehicle does not deviate from the lane, and the steering angle of the automatic steering also becomes larger. As a result, the driver may feel that the steering is being performed at a greater angle than he or she intends, which may make the driver feel uneasy.

The present invention provides a collision avoidance support device, a collision avoidance support method, and a collision avoidance support program that are improved so that the driver does not feel uneasy due to the steering angle being greater than the intended steering angle, even when a target trajectory is set such that the vehicle deviates from the lane.

[Means for solving the problems and effects of the invention]
According to the present invention, there is provided a collision avoidance assistance device (100) including: a target information acquisition device (16) that acquires information on targets ahead of a vehicle (102); an automatic steering device (46) that automatically steers a steering wheel (44); and a control unit (driving assistance ECU 10) configured to, when it is determined that it is necessary to avoid a collision with an obstacle (108) based on the target information acquired by the target information acquisition device (S20, S30), set a target trajectory (110) for traveling while avoiding a collision with the obstacle (S40), and control the automatic steering device (46) so that the vehicle travels along the target trajectory (S80 to S100).

The control unit (driving assistance ECU 10) is configured to estimate the maximum value (θamax) of the steering angle (θa) by automatic steering for driving the vehicle along the target trajectory (S50), and when it is determined that the maximum value is equal to or greater than the reference value (θc) (S50), to suspend execution of control of the automatic steering device (S150) until it is determined that the driver has started reversal steering (S120, S130), and when it is determined that the driver has started reversal steering, to control the automatic steering device to assist the driver in reversal steering (S170).

The present invention also provides a collision avoidance method that includes at least the steps of acquiring information about a target ahead of the vehicle (102) (S20), and when it is determined that it is necessary to avoid a collision with an obstacle (108) (S20, S30), setting a target trajectory (110) for traveling while avoiding a collision with the obstacle (108), and controlling an automatic steering device (46) so that the vehicle travels along the target trajectory (S80 to S100).

The collision avoidance method includes a step (S50) of estimating the maximum value (θamax) of the magnitude of the steering angle (θa) by automatic steering for driving the vehicle along the target trajectory, a step (S150) of suspending execution of control of the automatic steering device until it is determined that the driver has started reversal steering (S120, S130) if it is determined that the maximum value is equal to or greater than the reference value (θc), and a step (S170) of controlling the automatic steering device to assist the driver in reversal steering if it is determined that the driver has started reversal steering.

Furthermore, according to the present invention, there is provided a collision avoidance support program that causes an electronic control device (driving support ECU 10) mounted on a vehicle to execute at least the steps of: acquiring information on a target object ahead of the vehicle (102) (S20); when it is determined that it is necessary to avoid a collision with an obstacle (108) (S20, S30), setting a target trajectory (110) for traveling while avoiding a collision with the obstacle (108); and controlling an automatic steering device (46) so that the vehicle travels along the target trajectory (S80 to S100).

The collision avoidance assistance program includes a step (S50) of estimating the maximum value (θamax) of the magnitude of the steering angle (θa) by automatic steering for driving the vehicle along the target trajectory, a step (S150) of suspending execution of control of the automatic steering device when it is determined that the maximum value is equal to or greater than the reference value (θc) until it is determined that the driver has started reversal steering (S120, S130), and a step (S170) of controlling the automatic steering device to assist the driver in reversal steering when it is determined that the driver has started reversal steering.

According to the above-mentioned collision avoidance support device, collision avoidance support method, and collision avoidance support program, the maximum value of the steering angle by automatic steering for driving the vehicle along the target trajectory is estimated. If it is determined that the maximum value is equal to or greater than a reference value, execution of control of the automatic steering device, i.e., automatic steering, is suspended until it is determined that the driver has started back-steer steering. Furthermore, if it is determined that the driver has started back-steer steering, the automatic steering device is controlled to assist the driver in back-steer steering.

Therefore, when a target trajectory is set so that the vehicle deviates from the lane, and the vehicle's inclination angle with respect to the lane increases and the maximum value exceeds a reference value, automatic steering by the automatic steering device is not performed until it is determined that the driver has started steering back. This prevents the driver from feeling uneasy when they feel that steering is being performed beyond the steering angle they intended.

In addition, when it is determined that the driver has started steering back, the automatic steering device is controlled to assist the driver in steering back. Therefore, when the driver starts steering back, the automatic steering can assist the driver in steering back.

If the maximum value does not exceed the reference value, a target trajectory for driving while avoiding collision with obstacles is set, and the automatic steering device is controlled so that the vehicle drives along the target trajectory. Therefore, collision avoidance assistance is provided by automatic steering by the automatic steering device so that the vehicle drives while avoiding collision with obstacles.

[Mode of the invention]
In one aspect of the present invention, the control unit (driving assistance ECU 10) is configured to determine that the driver has started return steering when it determines that the product of the current steering angular velocity (θd) and the steering angular velocity (θdf) from a predetermined time ago or the product of the current steering torque (Ts) and the steering torque from a predetermined time ago (Tsf) is a negative value (S120, S130) while regarding the steering angular velocity and steering torque by the driver to either the left or right as positive values.

According to the above aspect, it is possible to reliably determine whether or not the driver has started steering back, compared to when it is determined whether or not the driver has started steering back based only on the product of the steering angular speed or only on the product of the steering torque.

In another aspect of the present invention, when the control unit (driving assistance ECU 10) determines that the maximum value (θamax) is equal to or greater than the reference value (θc) (S50), it is configured to issue a warning (S150) to the effect that automatic steering by the automatic steering device will not be performed until it is determined that the driver has started steering back.

According to the above aspect, an alarm is issued to inform the driver that automatic steering will not be performed by the automatic steering device until it is determined that the driver has started steering back. This allows the driver to recognize that he or she must use his or her own steering to avoid a collision with an obstacle.

In the above description, in order to aid in understanding the present invention, the names and/or symbols used in the embodiments described below are added in parentheses to the configuration of the invention corresponding to the embodiments. However, each component of the present invention is not limited to the components of the embodiments corresponding to the names and/or symbols added in parentheses. Other objects, other features, and associated advantages of the present invention will be easily understood from the description of the embodiments of the present invention described below with reference to the drawings.

1 is a schematic configuration diagram showing a collision avoidance assistance device according to an embodiment; 4 is a flowchart showing a collision avoidance assistance control routine according to the embodiment. FIG. 13 is a diagram showing a map for calculating a reference value θc based on a vehicle speed V. 11 is a diagram showing an example of the operation of the embodiment when the maximum value θamax of the absolute value of the steering angle θa of the steering assist when turning by automatic steering is performed is less than a reference value θc. 11 is a diagram showing an example of the operation of the embodiment when the maximum value θamax of the absolute value of the steering angle θa of the steering assist when turning by automatic steering is performed is equal to or greater than a reference value θc. 11A and 11B are diagrams illustrating an example of changes in steering angle θ, steering angular velocity θd, and steering torque Ts when a driver's steering operation changes from turning to returning.

The collision avoidance support device according to an embodiment of the present invention will be described in detail below with reference to the attached drawings.

As shown in FIG. 1, a collision avoidance support device 100 according to the first to third embodiments of the present invention is applied to a vehicle 102 and includes a driving support ECU 10. The vehicle 102 may be an autonomous vehicle, and includes a drive ECU 20, a braking ECU 30, an electric power steering ECU 40, and a meter ECU 50. ECU refers to an electronic control unit that includes a microcomputer as its main component. In the following description, the vehicle 102 will be referred to as the host vehicle 102 as necessary to distinguish it from other vehicles, and the electric power steering will be referred to as EPS.

The microcomputer of each ECU includes a CPU, ROM, RAM, a readable/writable non-volatile memory (N/M), and an interface (I/F). The CPU performs various functions by executing instructions (programs, routines) stored in the ROM. Furthermore, these ECUs are connected to each other via a Controller Area Network (CAN) 104 to enable data exchange (communication). Therefore, the detection values of sensors (including switches) connected to a specific ECU are also sent to other ECUs.

The driving assistance ECU 10 is a central control device that performs driving assistance control for the vehicle, such as collision avoidance assistance control and lane keeping control. In an embodiment, the driving assistance ECU 10 performs collision avoidance assistance control in cooperation with other ECUs, as will be described in detail later.

A camera sensor 12 and a radar sensor 14 are connected to the driving assistance ECU 10. The camera sensor 12 and the radar sensor 14 each include multiple camera devices and multiple radar devices. The camera sensor 12 and the radar sensor 14 function as a target information acquisition device 16 that acquires information about targets around the vehicle 102.

Although not shown in the figure, each camera device of the camera sensor 12 includes a camera unit that captures images of the surroundings of the vehicle 102, and a recognition unit that analyzes image data captured by the camera unit to recognize landmarks such as white lines on the road and other vehicles. The recognition unit supplies information about the recognized landmarks to the driving assistance ECU 10 at predetermined time intervals.

Each radar device of the radar sensor 14 includes a radar transmission/reception unit and a signal processing unit (not shown). The radar transmission/reception unit emits millimeter wave band radio waves (hereinafter referred to as "millimeter waves") and receives millimeter waves (i.e., reflected waves) reflected by a three-dimensional object (e.g., another vehicle, bicycle, etc.) within the emission range. The signal processing unit acquires information indicating the relative distance and relative speed between the vehicle and the three-dimensional object, the relative position (direction) of the three-dimensional object with respect to the vehicle, etc. at predetermined time intervals based on the phase difference between the emitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from emitting the millimeter wave to receiving the reflected wave, and supplies the information to the driving assistance ECU 10. Note that a LiDAR (Light Detection And Ranging) may be used instead of or in addition to the radar sensor 14.

Furthermore, a setting operation device 18 is connected to the driving assistance ECU 10, and the setting operation device 18 is provided in a position where it can be operated by the driver. Although not shown in FIG. 1, the setting operation device 18 includes a collision avoidance switch, and the driving assistance ECU 10 executes collision avoidance assistance control when the collision avoidance switch is on. Note that the collision avoidance assistance control may be executed regardless of whether the collision avoidance switch is on or not.

The drive ECU 20 is connected to a drive device 22 that accelerates the vehicle 102 by applying a driving force to drive wheels not shown in FIG. 1. Under normal circumstances, the drive ECU 20 controls the drive device so that the driving force generated by the drive device 22 changes according to the driving operation by the driver, and when a command signal is received from the driving assistance ECU 10, the drive ECU 20 controls the drive device 22 based on the command signal.

The brake ECU 30 is connected to a brake device 32 that applies a braking force to wheels (not shown in FIG. 1) to decelerate the vehicle 102. Under normal circumstances, the brake ECU 30 controls the brake device so that the braking force generated by the brake device 32 changes according to the braking operation by the driver, and when it receives a command signal from the driving assistance ECU 10, it performs automatic braking by controlling the brake device 32 based on the command signal.

The EPS device 42 is connected to the EPS ECU 40. The EPS ECU 40 controls the steering assist torque and reduces the steering burden on the driver by controlling the EPS device 42 in a manner known in the art based on the steering torque Ts and vehicle speed V detected by the driving operation sensor 60 and vehicle state sensor 70 described below. In addition, the EPS ECU 40 can steer the steering wheels 44 as necessary by controlling the EPS device 42. Thus, the EPS ECU 40 and the EPS device 42 function as an automatic steering device 46 that automatically steers the steering wheels 44 as necessary.

An alarm device 52 is connected to the meter ECU 50. The alarm device 52 is activated when it is determined that the vehicle 102 needs to steer to avoid an obstacle ahead, and issues an alarm that steering to avoid the obstacle is necessary and that automatic steering will not be performed. The alarm device 52 may be an alarm device that issues a visual alarm such as a display or an alarm lamp, an alarm device that issues an auditory alarm such as an alarm buzzer, or an alarm device that issues a tactile alarm such as seat vibration, or any combination thereof.

The driving operation sensor 70 and the vehicle condition sensor 80 are connected to the CAN 104. Information detected by the driving operation sensor 70 and the vehicle condition sensor 80 (called sensor information) is transmitted to the CAN 104. The sensor information transmitted to the CAN 104 can be used appropriately in each ECU. Note that the sensor information may be information of a sensor connected to a specific ECU and transmitted to the CAN 104 from that specific ECU.

The driving operation sensor 70 includes a driving operation amount sensor and a braking operation amount sensor. The driving operation sensor 70 further includes a steering angle sensor, a steering torque sensor, etc. The vehicle state sensor 80 includes a vehicle speed sensor, a longitudinal acceleration sensor, a lateral acceleration sensor, a yaw rate sensor, etc. In the embodiment, the steering angle sensor and the steering torque sensor respectively detect the steering angle θ and the steering torque Ts, with the values being positive when the vehicle 102 is turning left.

In this embodiment, the ROM of the driving assistance ECU 10 stores a program for collision avoidance assistance control corresponding to the flowchart shown in FIG. 2. The CPU executes the collision avoidance assistance control according to this embodiment in accordance with this program.

<Collision avoidance support control routine>
Next, a collision avoidance assist control routine in this embodiment will be described with reference to the flowchart shown in Fig. 2. The collision avoidance assist control according to the flowchart shown in Fig. 2 is executed by the CPU of the driving assist ECU 10 when a collision avoidance switch (not shown in Fig. 1) of the setting operation device 18 is on. Note that when this control is started, flags Fa, Fb, and Fc are initialized to 0.

First, in step S10, the CPU determines whether flag Fa is 1, that is, whether the setting of a target trajectory for the vehicle 102 to travel while avoiding collision with an obstacle has already been completed. If the CPU makes a positive determination, it advances this control to step S70, and if the CPU makes a negative determination, it advances this control to step S20.

In step S20, the CPU determines, in a manner known in the art, whether an obstacle has been detected in front of the vehicle 102 by the target information acquisition device 16 and whether steering is necessary to avoid a collision with the obstacle. If the CPU determines that the obstacle is not present, it temporarily terminates this control, and if the CPU determines that the obstacle is present, it advances this control to step S30.

In step S30, the CPU determines whether the driver has performed a steering operation to avoid a collision with an obstacle, in a manner known in the art, based on the detection results of the steering angle sensor and steering torque sensor of the driving operation sensor 70. If the CPU determines that the driver has performed a steering operation to avoid a collision with an obstacle, it temporarily terminates this control, and if the CPU determines that the driver has performed a steering operation to avoid a collision with an obstacle, it advances this control to step S40.

Although not shown in FIG. 2, when the CPU makes a positive determination in step S20, it outputs a command signal to the meter ECU 50 to activate the alarm device 52, thereby issuing an alarm, until it makes a positive determination in step S30. The alarm may include a display or sound indicating that there is an obstacle ahead of the vehicle and that steering is required to avoid a collision.

In step S40, the CPU sets a target trajectory for the vehicle 102 to travel while avoiding collision with the obstacle, based on the relative positional relationship and relative speed between the vehicle 102 and the obstacle, in a manner known in the art. Furthermore, the CPU sets flag Fa to 1.

When a target trajectory cannot be set, such as when the target trajectory is forced to deviate from the lane in a lane where deviation is prohibited, the warning device 52 may be activated to issue a warning that there is an obstacle ahead, but that the target trajectory cannot be set and automatic steering to avoid a collision will not be performed. Furthermore, this control may be temporarily terminated.

In step S50, the CPU estimates the maximum absolute value θamax of the steering angle θa of the steering assist when turning is performed by automatic steering, based on the target trajectory. Furthermore, the CPU determines whether the magnitude of the steering angle θa of the steering assist is large by determining whether the maximum value θamax is equal to or greater than the reference value θc. If the CPU makes a negative determination, it advances this control to step S70, and if it makes a positive determination, it sets flag Fb to 1 in step S60.

The maximum value θamax may be estimated as the steering angle θa of the steering assistance when the angle that the target trajectory makes with the lane is at its maximum in the region of turning by automatic steering, in other words, as the steering angle θa when the magnitude of the steering angle θa changes from increasing to decreasing. The maximum value θamax is larger as the displacement of the target trajectory in the direction perpendicular to the lane is larger. Furthermore, even if the displacement of the target trajectory in the direction perpendicular to the lane is the same, the shorter the time from when a positive determination is made in step S20 to when a positive determination is made in step S30, the smaller the maximum value θamax.

The reference value θc may be a positive constant, but in this embodiment, it is variably set according to the vehicle speed V, for example, by calculation using the map shown in FIG. 3. As shown in FIG. 3, the reference value θc is calculated to be smaller as the vehicle speed V increases, except in the low-speed region where the vehicle speed V is equal to or less than the reference value V1 (a positive constant) and in the high-speed region where the vehicle speed V is equal to or more than the reference value V2 (a positive constant greater than V1).

In step S70, the CPU determines whether flag Fb is 1, i.e., whether the maximum value θamax has already been determined to be equal to or greater than the reference value θc. If the CPU determines yes, the control proceeds to step S110, and if the CPU determines no, the control proceeds to step S80.

In step S80, the CPU calculates a target steering angle θt for driving the vehicle 102 along the target trajectory from the present until a predetermined time later. For example, the CPU calculates the turning radius of the target trajectory from the present until a predetermined time later as the target turning radius, and calculates the target steering angle θt as the steering angle for making the turning radius of the vehicle 102 the target turning radius.

In step S90, the CPU determines whether or not to end the automatic steering control for driving the vehicle along the target trajectory, for example, by determining whether or not the vehicle 102 is now in a situation where it is actually driving along the lane. If the CPU determines yes, it advances this control to step S180, and if the CPU determines no, it advances this control to step S100.

In step S100, the CPU outputs a command signal to the EPS ECU 40 to control the EPS device 42 so that the steering angle θ becomes the target steering angle θt. That is, the CPU executes automatic steering control to make the vehicle travel along the target trajectory. When executing automatic steering control, the CPU may output a command signal to the meter ECU 50 to activate the display of the warning device 52, thereby displaying that automatic steering control is being executed to make the vehicle travel along the target trajectory.

In step S110, the CPU determines whether flag Fc is 1, that is, whether it has already been determined in step 120 or 130 described below that the driver's steering operation has changed from further turning to returning. If the CPU makes a positive determination, it advances this control to step S160, and if the CPU makes a negative determination, it advances this control to step S120.

In step S120, the CPU calculates the time differential value of the steering angle θ as the steering angular velocity θd, and determines whether the product θd·θdf of the current steering angular velocity θd and the steering angular velocity θdf Nc cycles ago (a positive constant integer) is a negative value. If the CPU makes a positive determination, it advances this control to step S140, and if the CPU makes a negative determination, it advances this control to step S130.

In step S130, the CPU determines whether the product Ts·Tsf of the current steering torque Ts and the steering torque Tsf Nc cycles ago is a negative value. If the CPU determines that the product is negative, the CPU advances the control to step S150, and if the CPU determines that the product is positive, the CPU sets flag Fc to 1 in step S140.

Steps S120 and S130 are steps for judging whether the driver's steering operation has changed from further turning or holding the steering wheel to turning back. When a negative judgment is made in steps S120 and S130, and it is judged that the driver's steering operation has not changed from further turning or holding the steering wheel to turning back, this control is temporarily terminated. In contrast, when a positive judgment is made in step S120 or S130, and it is judged that the driver's steering operation has changed from further turning or holding the steering wheel to turning back, flag Fc is set to 1.

In step S150, the CPU suspends the execution of automatic steering to avoid a collision with an obstacle, and issues a warning by outputting a command signal to the meter ECU 50 to activate the warning device 52. The warning may include a display or sound indicating that automatic steering to avoid a collision with an obstacle will not be performed. Note that this warning may continue to be issued until a positive determination is made in step S120 or S130.

In step S160, the CPU determines whether the driver's steering operation to return to the original position has ended, for example, by determining whether the vehicle 102 is now traveling substantially along the lane. If the CPU determines yes, it resets flags Fa, Fb, and Fc to 0 in step S180, and if the CPU determines no, it advances the control to step S170.

In step S170, the CPU calculates an auxiliary return torque Tr that assists the driver's return steering operation based on the steering torque Ts. The auxiliary return torque Tr is calculated to be larger as the magnitude of the steering torque Ts increases. Furthermore, the CPU outputs a command signal to the EPS ECU 40 to control the EPS device 42 so that the assist torque Ta becomes the auxiliary return torque Tr. In other words, the CPU executes control to assist the driver's return steering operation.

<Operation of the embodiment>
Next, the operation of the embodiment will be described with reference to Figures 4 and 5. As shown in Figures 4 and 5, it is assumed that a vehicle 102 is traveling on a lane 106, an obstacle 108 such as a motorcycle is present in the lane 106 to the left front of the vehicle, and a target trajectory 110 is set so that the vehicle can travel without colliding with the obstacle.

4 and 5, at time t1, the target information acquisition device 16 detects an obstacle ahead of the vehicle 102 and starts issuing an alarm (S20), and at time t2, it is determined that the driver has performed a steering operation to avoid a collision with the obstacle (S30). Furthermore, at time t3, the angle that the target trajectory makes with the lane 106 becomes maximum, and the absolute value of the steering angle θa of the steering assistance when turning by automatic steering becomes maximum value θamax.

<When the maximum value θamax is less than the reference value θc (FIG. 4)>
4, when the target trajectory 110 does not deviate from the lane 106 or when the degree of deviation from the lane 106 into the adjacent lane 112 is small, the angle that the target trajectory makes with respect to the lane does not become large. Therefore, the maximum value θamax does not become large and does not become less than the reference value θc.

If the maximum value θamax is less than the reference value θc, a negative determination is made in step S50 and flag Fb is not set to 1, so a negative determination is made in step S70. Therefore, steps S80 to S100 are repeatedly executed, and automatic steering control is performed to make the vehicle travel along the target trajectory 110, for example, until time t5 when it is determined that the vehicle 102 is in lane 106 and travels along that lane. Therefore, as shown in the bottom row of FIG. 4, automatic steering control is performed from time t2 to time t5 to make the vehicle travel along the target trajectory 110.

<When the maximum value θamax is equal to or greater than the reference value θc (FIG. 5)>
5, when the degree to which the target trajectory 110 protrudes from the lane 106 into the adjacent lane 112 is large, the angle that the target trajectory makes with the lane becomes large. Therefore, the maximum value θamax becomes large so as to be equal to or larger than the reference value θc.

If the maximum value θamax is equal to or greater than the reference value θc, a positive determination is made in step S50 and flag Fb is set to 1, so a positive determination is made in step S70. Therefore, steps S80 to S100 are not executed, and automatic steering control for driving the vehicle along the target trajectory 110 is not executed.

For example, assume that at time t4, the driver's steering operation changes from turning the vehicle further to turning it back. In the section from time t2 to t4, negative determinations are made in steps S120 and S130. Therefore, in step S150, a warning is issued to the effect that automatic steering to avoid a collision with an obstacle will not be performed.

At time t4, a positive determination is made in step S120 or S130. Therefore, from time t4 onwards, control is executed in step S170 to assist the driver's steering operation back until time t5, at which it is determined in step S160 that the driver's steering operation back is completed.

As can be seen from the above explanation, according to the embodiment, for example, when the target trajectory 110 is set so that the vehicle 102 deviates from the lane 106, and the inclination angle of the vehicle with respect to the lane increases and the maximum value θamax becomes equal to or greater than the reference value θc, automatic steering by the automatic steering device is not performed until it is determined that the driver has started steering back. This makes it possible to prevent the driver from feeling uneasy when they sense that steering is being performed beyond the steering angle they intend.

In addition, when it is determined that the driver has started steering back, the automatic steering device is controlled to assist the driver in steering back. Therefore, when the driver starts steering back, the automatic steering can assist the driver in steering back.

If the maximum value θamax does not become equal to or greater than the reference value θc, a target trajectory for avoiding collision with an obstacle is set (S40), and the automatic steering device is controlled so that the vehicle travels along the target trajectory (S80 to S100). Therefore, collision avoidance assistance is provided by automatic steering by the automatic steering device so that the vehicle travels while avoiding collision with an obstacle.

In addition, according to the embodiment, it is possible to reliably determine whether or not the driver has started steering back, compared to when it is determined whether or not the driver has started steering back based only on the product of the steering angular velocities θd·θdf or only on the product of the steering torques Ts·Tsf.

For example, as shown in FIG. 6, when steering and steering back is performed at a large steering angle, the steering torque Ts fluctuates irregularly due to tire slip. Therefore, it is difficult to determine the start of steering back based on the product Ts·Tsf of the steering torque, but it is possible to determine the start of steering back based on the product θd·θdf of the steering angular speeds.

In addition, according to the embodiment, an alarm is issued to inform the driver that automatic steering will not be performed by the automatic steering device until it is determined that the driver has started steering back (S150). This allows the driver to recognize that he or she must use his or her own steering to avoid a collision with an obstacle.

Although the present invention has been described in detail above with respect to a specific embodiment, the present invention is not limited to the above-described embodiment, and it will be apparent to those skilled in the art that various other embodiments are possible within the scope of the present invention.

For example, in the embodiment, the target steering angle θt is calculated as a target control amount for driving the vehicle along a target trajectory to avoid an obstacle. However, the target control amount may be a target steering angle of the steering wheels, and the steering angle of the steering wheels may be controlled to become the target steering angle in step S110.

In addition, in this embodiment, in step S30, it is determined whether the driver has performed a steering operation to avoid a collision with an obstacle. However, this step may be omitted.

Furthermore, in the embodiment, in steps S120 and S130, a determination is made as to whether the driver's steering operation has changed from further steering to steering back, and if a negative determination is made, control proceeds to step S150. However, if a negative determination is made in steps S120 and S130, a determination is made as to whether the driver's steering operation has changed from holding the steering wheel to steering back, and if a negative determination is made, control proceeds to step S150, but if a positive determination is made, control may be modified to proceed to step S140. Also, one of steps S120 and S130 may be omitted.

10... Driving assistance ECU, 12... Camera sensor, 14... Radar sensor, 16... Target information acquisition device, 40... EPS ECU, 60... Driving operation sensor, 70... Vehicle state sensor, 100... Collision avoidance assistance device, 102... Vehicle, 108... Obstacle, 110... Target trajectory

Claims (5)

A collision avoidance support device including: a target information acquisition device that acquires information on at least a target ahead of a vehicle; an automatic steering device that automatically steers a steering wheel; and a control unit that, when it is determined based on the target information acquired by the target information acquisition device that it is necessary to avoid a collision with an obstacle, sets a target trajectory for traveling while avoiding a collision with the obstacle, and controls the automatic steering device so that the vehicle travels along the target trajectory,
A collision avoidance assistance device configured such that the control unit estimates a maximum value of the magnitude of the steering angle by automatic steering for driving the vehicle along the target trajectory, and when it determines that the maximum value is equal to or greater than a reference value, suspends execution of control of the automatic steering device until it determines that the driver has started reversal steering, and when it determines that the driver has started reversal steering, controls the automatic steering device to assist the driver in reversal steering. In the collision avoidance support device according to claim 1, the control unit is configured to determine that the driver has started turning back steering when it determines that the steering angular velocity and steering torque of the driver's steering operation to the left or right are positive, and the product of the current steering angular velocity and the steering angular velocity a predetermined time ago and the product of the current steering torque and the steering torque a predetermined time ago are negative. In the collision avoidance support device according to claim 1, the control unit is configured to issue a warning to the effect that automatic steering by the automatic steering device will not be performed until it is determined that the driver has started steering back when the maximum value is determined to be equal to or greater than a reference value. A collision avoidance support method including the steps of: acquiring information on at least a target object ahead of a vehicle; setting a target trajectory for traveling while avoiding a collision with the obstacle when it is determined that it is necessary to avoid a collision with the obstacle; and controlling an automatic steering device so that the vehicle travels along the target trajectory,
A collision avoidance assistance method including the steps of: estimating a maximum value of a steering angle by automatic steering for driving a vehicle along the target trajectory; suspending execution of control of the automatic steering device when it is determined that the maximum value is equal to or greater than a reference value, until it is determined that the driver has started reversal steering; and controlling the automatic steering device to assist the driver in reversal steering when it is determined that the driver has started reversal steering. 1. A collision avoidance support program that causes an electronic control device mounted on a vehicle to execute the following steps: acquiring information on at least a target object ahead of the vehicle; when it is determined that it is necessary to avoid a collision with an obstacle, setting a target trajectory along which the vehicle will travel while avoiding a collision with the obstacle; and controlling an automatic steering device so that the vehicle travels along the target trajectory,
A collision avoidance assistance program including: a step of estimating a maximum value of a steering angle by automatic steering for driving a vehicle along the target trajectory; a step of suspending execution of control of the automatic steering device when it is determined that the maximum value is equal to or greater than a reference value, until it is determined that the driver has started reversal steering; and a step of controlling the automatic steering device to assist the driver in reversal steering when it is determined that the driver has started reversal steering.

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