Collision avoidance assist device

Abstract

The collision avoidance assist device includes a driving assist ECU. When the steering avoidance control start condition is satisfied, the driving assist ECU starts the steering avoidance control to avoid a collision between the host vehicle and a preceding vehicle. When the indicated direction indicated by the direction indicator of the preceding vehicle is the same as the avoidance planned direction based on the steering avoidance control, the driving assist ECU prohibits the execution of the steering avoidance control. When the state of the direction indicator of the preceding vehicle is not the direction indicating state, the driving assist ECU sets the steering avoidance control start condition as the first start condition. When the indicated direction is different from the avoidance planned direction, the driving assist ECU sets the steering avoidance control start condition as the second start condition. The first start condition and the second start condition are determined such that the inter-vehicle distance between the host vehicle and the preceding vehicle at the time point when the second start condition can be satisfied becomes shorter than the inter-vehicle distance at the time point when the first start condition can be satisfied.

Description

Technical Field

[0001] The present invention relates to a collision avoidance assist device that performs a steering avoidance control for controlling the steering of a vehicle (host vehicle) to avoid a collision between the host vehicle and another vehicle (front vehicle) located in front of the host vehicle. Background Art

[0002] One of the conventional collision avoidance assistance devices automatically steers the vehicle so that the vehicle moves along an avoidance path when there is a possibility that the vehicle will collide with an obstacle in front of the vehicle and when there is an avoidance path that can avoid the collision between the vehicle and the obstacle and will not collide with other objects (see Patent Document 1).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2017-43262

[0006] Furthermore, sometimes the obstacle in front of the vehicle is the vehicle in front, and the direction indicator of the vehicle in front is working (flashing) in a manner indicating either the left direction or the right direction (hereinafter sometimes referred to as the "indicated direction"). In this case, a situation may arise in which the indicated direction is different from the direction in which the vehicle in front wants to avoid the vehicle in front by steering avoidance control (either the left direction or the right direction, hereinafter also referred to as the "predetermined avoidance direction"). In this situation, after the vehicle in front starts traveling along the avoidance path (i.e., after the steering avoidance control starts), there is a high possibility that the vehicle in front will move in a direction away from the vehicle in front. If the steering avoidance control is started in advance and the vehicle in front moves in the indicated direction afterwards, there will be a situation in which the amount of lateral movement of the vehicle in front based on the steering avoidance control becomes excessive, or the steering avoidance control is not required in the first place. As a result, there is a possibility that the driver will get annoyed with the steering avoidance control.

[0007] On the other hand, if the indicated direction of the vehicle ahead is the same as the predetermined avoidance direction of the host vehicle, there is a possibility that the vehicle ahead will gradually approach the avoidance path. In this case, the vehicle ahead may get too close to the host vehicle that wants to avoid a collision with the vehicle ahead by steering avoidance control, or the vehicle ahead may collide with the host vehicle that wants to avoid a collision with the vehicle ahead by steering avoidance control. Summary of the invention

[0008] The present disclosure is made to address the above problems. That is, one of the objects of the present disclosure is to provide a collision avoidance assistance device in which, when the collision avoidance assistance device performs steering avoidance control, the host vehicle does not approach the preceding vehicle excessively, and the collision avoidance assistance device can reduce the possibility of the driver getting bored with the steering avoidance control. Hereinafter, the collision avoidance assistance device of the present disclosure is sometimes referred to as the "present disclosure assistance device".

[0009] The present disclosure assistance device (10) includes: a surrounding sensor (21) including a camera sensor (21b) that captures an area in front of the host vehicle (SV) to obtain image data representing the area, and obtains information about a preceding vehicle (OV1) based at least on the image data, where the preceding vehicle (OV1) is another vehicle present in the front area of the host vehicle; a steering angle actuator (52) configured to be able to change the steering angle of the host vehicle; and a control unit (20) that, when it is determined that a collision possibility condition is satisfied based on information from the surrounding sensor (steps 710, step 715, step 720), obtains a target trajectory for avoiding a collision between the host vehicle and the preceding vehicle through an operation using the image data (step 815), and starts steering avoidance control for controlling the steering angle actuator so that the host vehicle travels along the target trajectory when it is determined that a prescribed steering avoidance control start condition is satisfied (step 850), where the collision possibility condition is satisfied when there is a possibility of a collision between the host vehicle and the preceding vehicle.

[0010] Moreover, the control unit is configured to: obtain avoidance predetermined direction information regarding an avoidance predetermined direction indicating in which direction, among the left direction and the right direction, the target lane changes the route of the host vehicle (step 830), determine whether the state of the direction indicator of the preceding vehicle is a direction indication state indicating the predetermined moving direction of the preceding vehicle based on the image data (step 835), and when it is determined that the state of the direction indicator is the direction indication state, obtain information regarding the indicated direction indicating in which direction, among the left direction and the right direction, the predetermined moving direction of the preceding vehicle indicated by the direction indicator is based on the image data (step 860), when it is determined that the state of the direction indicator is not the direction indication state, set the steering avoidance control start condition to a first start condition that can be satisfied when the inter-vehicle distance between the host vehicle and the preceding vehicle becomes a first distance (steps 840 and 845), when it is determined that the state of the direction indicator is the direction indication state, determine whether the predetermined moving direction of the preceding vehicle is the same as the avoidance predetermined direction based on the information regarding the indicated direction and the avoidance predetermined direction information (step 865), when it is determined that the predetermined moving direction of the preceding vehicle is the same as the avoidance predetermined direction, prohibit the execution of the steering avoidance control (step 865: No, step 825), and when it is determined that the predetermined moving direction of the preceding vehicle is different from the avoidance predetermined direction, set the steering avoidance control start condition to a second start condition that can be satisfied at a time point when the inter-vehicle distance becomes a distance shorter than the first distance at the time point when the first start condition can be satisfied (step 865: Yes, steps 870 and 875).

[0011] According to the auxiliary device of the present disclosure, it is determined whether the state of the direction indicator of the preceding vehicle is "a direction indication state showing that the predetermined moving direction of the preceding vehicle is either the left direction or the right direction". Moreover, according to the auxiliary device of the present disclosure, when it is determined that the state of the direction indicator of the preceding vehicle is the direction indication state and the predetermined moving direction of the preceding vehicle is the same as the avoidance predetermined direction, the execution of the steering avoidance control is prohibited. Thereby, the auxiliary device of the present disclosure can reduce the possibility of collision between the host vehicle and the preceding vehicle.

[0012] Moreover, according to the assist device of the present disclosure, when it is determined that the state of the direction indicator is not the direction indication state, the steering avoidance control start condition is set to "a first start condition that can be established when the inter-vehicle distance between the host vehicle and the preceding vehicle becomes a first distance". In contrast, when it is determined that the state of the direction indicator of the preceding vehicle is the direction indication state and the predicted moving direction of the preceding vehicle is different from the avoidance predicted direction, the steering avoidance control start condition is set to a second start condition. This second start condition is a condition that can be established at a time point when the inter-vehicle distance between the vehicle and the preceding vehicle becomes a distance shorter than the inter-vehicle distance at the time point when the first start condition is established. In other words, the second start condition is a condition that is established at a timing later than the timing when the first start condition is established. Therefore, the assist device of the present disclosure can reduce the possibility that the lateral movement amount of the host vehicle based on the steering avoidance control becomes excessive when the predicted moving direction of the preceding vehicle is different from the avoidance predicted direction. As a result, the possibility that the driver gets bored with the steering avoidance control can be reduced.

[0013] In one aspect of the assist device of the present disclosure, the steering avoidance control start condition at least includes a condition that a collision index value (TTC) indicating the possibility of collision between the host vehicle and the preceding vehicle has reached a collision possibility threshold value (TTCth), and the control unit sets the collision possibility threshold value (TTC2) used under the second start condition to a value different from the collision possibility threshold value (TTC1) used under the first start condition.

[0014] More specifically, the steering avoidance control start condition at least includes a condition that a collision prediction time (TTC), which is a predicted value of the time until collision between the host vehicle and the preceding vehicle, is shorter than a specified collision determination threshold time (TTCth). The control unit sets the collision determination threshold time (TTCth) used under the first start condition to a first time (TTC1), and the control unit sets the collision determination threshold time (TTCth) used under the second start condition to a second time (TTC2) shorter than the first time.

[0015] According to the above aspect, when it is determined that the state of the direction indicator of the preceding vehicle is the direction indication state and the predicted moving direction of the preceding vehicle is different from the avoidance predicted direction, the collision determination threshold is set to a value different from the collision determination threshold when the state of the direction indicator of the preceding vehicle is not the direction indication state. Thereby, the steering avoidance control start condition when it is determined that the predicted moving direction of the preceding vehicle is different from the avoidance predicted direction can be set to a second start condition, and this second start condition can be established at a time point when the inter-vehicle distance becomes a distance shorter than the inter-vehicle distance at the time point when the first start condition can be established.

[0016] In the above description, in order to facilitate the understanding of the present invention, names and / or reference numerals used in the following embodiments 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 embodiments defined by the above names and / or reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic configuration diagram of a collision avoidance assistance device according to an embodiment of the present disclosure.

[0018] Figure 2 is a diagram for explaining the outline of steering avoidance control.

[0019] Figure 3 is a diagram for explaining a first map Map1.

[0020] Figure 4 is a diagram for explaining the outline of the operation of the collision avoidance assistance device.

[0021] Figure 5 is a diagram for explaining the outline of the operation of the collision avoidance assistance device.

[0022] Figure 6 is a diagram for explaining a second map Map2.

[0023] Figure 7 is a flowchart showing a routine executed by the CPU of the driving assistance ECU.

[0024] Figure 8 is a flowchart showing a routine executed by the CPU of the driving assistance ECU.

[0025] Figure 9 is a flowchart showing a routine executed by the CPU of the driving assistance ECU.

[0026] Figure 10 is a diagram for explaining the outline of the operation of a modified example of the collision avoidance assistance device.

[0027] REFERENCE NUMERAL DESCRIPTION

[0028] 10: Collision avoidance assistance device, 20: Driving assistance ECU, 21: Surrounding sensor, 21a: Radar sensor, 21b: Camera sensor, 21c: Target recognition unit, 22: Vehicle speed sensor, 23: Yaw rate sensor, 24: Longitudinal acceleration sensor, 25: Lateral acceleration sensor, 50: EPS·ECU, 51: Motor driver, 52: Steering motor, SV: Vehicle. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0029] <Configuration>

[0030] As shown Figure 1 in FIG. Figure 1 , the collision avoidance assistance device 10 of an embodiment of the present invention is applied to a vehicle SV. To distinguish it from other vehicles, the vehicle SV is sometimes referred to as the host vehicle SV. The collision avoidance assistance device 10 includes a driving assistance ECU 20, an engine ECU 30, a brake ECU 40, and an electric power steering ECU 50. It should be noted that hereinafter, the driving assistance ECU 20 is referred to as the "DS (Driving Support) ECU", and the electric power steering ECU 50 is referred to as the "EPS (Electric Power Steering) · ECU 50".

[0031] These ECUs are control units (electronic control devices (Electronic / Electric Control Unit)) having a microcomputer as a main part, and are also referred to as controllers. These ECUs are connected to each other via a CAN 70 (Controller Area Network) in such a way that data can be exchanged (communication is possible). The microcomputer includes a CPU, a ROM, a RAM, and an interface (I / F), etc. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Several or all of these ECUs can be integrated into one ECU.

[0032] A surrounding sensor 21, a vehicle speed sensor 22, a yaw rate sensor 23, a longitudinal and lateral acceleration sensor 24, and a lateral acceleration sensor 25 are connected to the DS ECU. The DS ECU receives detection signals or output signals from these sensors. Several or all of these sensors can also be connected to an ECU other than the DS ECU. In this case, the DS ECU receives the detection signals or output signals of these sensors from other ECUs via the CAN.

[0033] The surrounding sensor 21 includes a radar sensor 21a, a camera sensor 21b, and a target recognition unit 21c. It should be noted that from a functional perspective, the surrounding sensor 21 constitutes an "obstacle recognition device". From a functional perspective, the camera sensor 21b constitutes a "direction indication acquisition device". It should be noted that the target recognition unit 21c includes an ECU, and this ECU includes a microcomputer.

[0034] The surrounding sensor 21 recognizes a three-dimensional object existing in the "peripheral area of the host vehicle SV" that at least includes a "predetermined area (front area) in front of the host vehicle SV", and acquires information related to the recognized three-dimensional object. The three-dimensional object is a moving object (e.g., a pedestrian and a vehicle, etc.) or a stationary object (e.g., a utility pole, a tree, and a guardrail, etc.). Hereinafter, the three-dimensional object is sometimes referred to as a "target".

[0035] The surrounding sensor 21 obtains information related to the identified target (hereinafter sometimes referred to as "target information") through calculation and sends it to the DSECU. The target information includes the information listed below.

[0036] · Longitudinal distance Dfx of the target: The longitudinal distance Dfx of the target is the signed distance in the direction of the central axis (x-axis direction) extending in the front-rear direction of the host vehicle SV between the front end of the host vehicle SV and the target.

[0037] · Lateral position Dfy of the target: The lateral position Dfy of the target is the signed distance in the direction (y-axis direction) orthogonal to the central axis extending in the front-rear direction of the host vehicle SV between the central position of the target and the central axis in the vehicle width direction of the host vehicle SV.

[0038] · Relative speed Vfx of the target: The relative speed Vfx of the target is the difference between the speed Vb of the target in the x-axis direction and the vehicle speed (speed in the x-axis direction) Vs of the host vehicle SV (= Vb - Vs).

[0039] · Information indicating the type of the target (for example, information indicating whether the target is a vehicle, a pedestrian, or a stationary object)

[0040] · Width (left-right width) W of the target

[0041] · Length L of the target

[0042] It should be noted that the longitudinal distance Dfx and the lateral position Dfy are also referred to as "detection positions of the target".

[0043] The surrounding sensor 21 obtains target information based on a predefined x-y coordinate system. The x-axis extends in such a way as to pass through the center position in the vehicle width direction at the front end of the host vehicle SV along the front-rear direction of the host vehicle SV and has the front as the positive value. The y-axis is orthogonal to the x-axis and has the left direction of the host vehicle SV as the positive value. The origin of the x-axis and the origin of the y-axis are predefined positions of the host vehicle SV (for example, the center position in the vehicle width direction at the front end of the host vehicle SV).

[0044] More specifically, the radar sensor 21a includes a radar wave transmitting / receiving unit and a processing unit. The radar wave transmitting / receiving unit radiates an electric wave (hereinafter referred to as "millimeter wave") in the millimeter wave band, for example, to the peripheral area of the host vehicle SV including at least the front area of the host vehicle SV, and receives the reflected wave generated by the reflection of the radiated millimeter wave by a part of the three-dimensional object (i.e., the reflection point). It should be noted that the radar sensor 21a may also be a radar sensor that uses an electric wave (radar wave) in a frequency band other than the millimeter wave band.

[0045] The processing unit of the radar sensor 21a determines the presence or absence of a target based on the reflection point information, which includes the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from the transmission of the millimeter wave to the reception of the reflected wave, etc. The processing unit of the radar sensor 21a groups "multiple reflection points" with a high possibility of detecting a three-dimensional object, and identifies the group of reflection points obtained by grouping as one target (for example, refer to Japanese Unexamined Patent Application Publication No. 2019-003235, Japanese Unexamined Patent Application Publication No. 2019-002691, and Japanese Unexamined Patent Application Publication No. 2019-002690, etc.).

[0046] Moreover, the processing unit of the radar sensor 21a calculates the longitudinal distance Dfx of the target, the lateral position Dfy of the target, the azimuth θp of the target relative to the host vehicle SV, and the relative speed Vfx between the host vehicle SV and the target, etc. based on the reflection point information of the reflection points belonging to the identified target. Hereinafter, the information including these values obtained by the radar sensor 21a is sometimes referred to as "radar sensor detection information".

[0047] The camera sensor 21b includes a stereo camera and an image processing unit. The stereo camera captures the scenery of the "left area and right area" in front of the host vehicle SV (i.e., the front area of the host vehicle SV) to obtain a pair of left and right images (i.e., image data representing the front area). The image processing unit determines whether there is a target in the front area of the host vehicle SV based on the image data.

[0048] When the image processing unit determines that there is a target in the front area of the host vehicle SV, it calculates and obtains the azimuth θp of the target, the longitudinal distance Dfx of the target, and the relative speed Vfx between the host vehicle SV and the target, etc. based on the image data. Moreover, the image processing unit determines the type of the above-mentioned target by pattern matching based on the image data, and obtains information representing the type of the target. These information obtained by the image processing unit are sometimes referred to as "camera sensor detection information".

[0049] The target recognition unit 21c receives "radar sensor detection information" and "camera sensor detection information" from the processing unit of the radar sensor 21a and the image processing unit of the camera sensor 21b, respectively.

[0050] The target recognition unit 21c determines (obtains) the final target information of the above-mentioned target based on the "radar sensor detection information" and the "camera sensor detection information". Whenever a predetermined time has elapsed, the target recognition unit 21c transmits the determined final target information of the target to the DSECU.

[0051] The image processing unit of the camera sensor 21b identifies the left and right lane dividing lines of the road (hereinafter also simply referred to as "white lines") from the acquired image data by a well-known method. For example, the image processing unit detects edge points where the brightness of the image changes sharply, and extracts the contour lines of the white lines based on the detected edge points, thereby identifying the left white line and the right white line.

[0052] Then, every time a predetermined time elapses, the image processing unit obtains the position information (the x-coordinate position and the y-coordinate position on the above x-y coordinates) of the left white line and the right white line of the lane (travel lane) in which the vehicle SV is traveling through calculation and sends it to the DSECU.

[0053] Moreover, when the type of the object recognized as being in front of the vehicle SV by the surrounding sensor 21 (the image processing unit of the camera sensor 21b) is a vehicle (hereinafter also referred to as "the vehicle in front"), the following described turn signal information is obtained based on the current and past image data, and the obtained turn signal information is sent to the DSECU. The turn signal information includes the following information.

[0054] · Information on whether the turn signal of the vehicle in front is blinking (operating).

[0055] · Information on whether only one of the "left turn signal and right turn signal" of the vehicle in front is blinking when the turn signal of the vehicle in front is blinking.

[0056] · Information indicating which of the left turn signal and the right turn signal is blinking when only one of the "left turn signal and right turn signal" of the vehicle in front is blinking (hereinafter sometimes referred to as "information on the indicating direction or indicating direction information").

[0057] Specifically, when only the left turn signal among the left turn signal and the right turn signal is blinking, the image processing unit obtains "information indicating that the indicating direction is the left direction" as the information on the indicating direction. When only the right turn signal among the left turn signal and the right turn signal is blinking, the image processing unit obtains "information indicating that the indicating direction is the right direction" as the information on the indicating direction. It should be noted that in the case where both the left turn signal and the right turn signal are not blinking and in the case where both the left turn signal and the right turn signal are blinking, the indicating direction is not determined. Thus, in these cases, the image processing unit sends "information indicating that the state of the turn signal is not the turn signal state (that is, the meaning of being unable to determine the indicating direction)" to the DSECU as the information on the indicating direction.

[0058] The vehicle speed sensor 22 detects the running speed (vehicle speed) of the host vehicle SV, and outputs a signal indicating the detected vehicle speed Vs.

[0059] The yaw rate sensor 23 detects the yaw rate of the host vehicle SV, and outputs a signal indicating the yaw rate Yr.

[0060] The longitudinal acceleration sensor 24 detects the longitudinal acceleration of the host vehicle SV and outputs a signal indicating the detected longitudinal acceleration Gx. When the longitudinal acceleration Gx is a negative value, the magnitude (absolute value) of the longitudinal acceleration Gx indicates deceleration.

[0061] The lateral acceleration sensor 25 detects the lateral acceleration of the host vehicle SV, and outputs a signal indicating the detected lateral acceleration Gy.

[0062] The engine ECU 30 is connected to the engine actuator 31. The engine actuator 31 includes a throttle actuator that changes the opening of the throttle of the engine 32. The engine ECU 30 can change the torque generated by the engine 32 by driving the engine actuator 31. The torque generated by the engine 32 is transmitted to the drive wheels via a transmission (not shown).

[0063] Therefore, the engine ECU 30 can control the driving force of the vehicle SV by controlling the engine actuator 31 to change the acceleration state (front and rear acceleration Gx) of the vehicle SV. It should be noted that, in the case where the vehicle SV is a hybrid vehicle, the engine ECU 30 can control the driving force of the vehicle SV generated by either or both of the "engine and motor" as the vehicle drive source. Moreover, in the case where the vehicle SV is an electric car, the engine ECU 30 can control the driving force of the vehicle SV generated by the motor as the vehicle drive source.

[0064] The brake ECU 40 is connected to a brake actuator 41. The brake actuator 41 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes the hydraulic oil by the pedal force of the brake pedal and a friction brake mechanism 42 provided at the left and right front and rear wheels. The friction brake mechanism 42 includes a brake disc 42a fixed to the wheel and a brake caliper 42b fixed to the vehicle body.

[0065] The brake actuator 41 adjusts the hydraulic pressure supplied to the wheel cylinder built into the brake caliper 42b according to the instruction from the brake ECU 40, and operates the wheel cylinder by the hydraulic pressure. As a result, the brake actuator 41 presses the brake pad to the brake disc 42a to generate friction braking force. Therefore, the brake ECU 40 can control the braking force of the vehicle SV by controlling the brake actuator 41 to change the acceleration state of the vehicle SV (negative front and rear acceleration Gx).

[0066] The EPS·ECU 50 is a well-known control device for an electric power steering system. The EPS·ECU 50 is connected to the motor driver 51. The motor driver 51 is connected to the steering motor 52. The steering motor 52 is incorporated into a "steering mechanism including a steering wheel SW, a steering shaft SF, and a steering gear mechanism (not shown)". The steering motor 52 is an electric motor that generates a steering torque by the electric power supplied from the motor driver 51. The steering motor 52 can steer the left and right steering wheels of the vehicle SV by this steering torque. That is, the steering motor 52 functions as a steering angle actuator that changes the steering angle (the steering angle of the steering wheels) of the vehicle SV.

[0067] The EPS·ECU 50 is connected to a steering angle sensor 53 and a steering torque sensor 54. The steering angle sensor 53 detects the steering angle of the steering wheel SW of the vehicle SV and outputs a signal representing the steering angle θs. The steering torque sensor 54 detects the steering torque (hereinafter referred to as "driving torque TqDr") applied to the steering shaft SF of the vehicle SV by the operation of the steering wheel SW and outputs a signal representing the driving torque TqDr. The steering angle θs and the driving torque TqDr are defined as positive values when the vehicle SV is steered in the left turn direction and negative values when the vehicle SV is steered in the right turn direction.

[0068] The EPS·ECU 50 drives the steering motor 52 based on the detected "driving torque TqDr, steering angle θs, and vehicle speed Vs". Thereby, the EPS·ECU 50 generates a steering assist torque to assist the driver's steering operation.

[0069] When the EPS·ECU 50 receives a steering command from the DSECU during the execution of the steering avoidance control described later, it drives the steering motor 52 via the motor driver 51 based on the target steering angle (or target steering torque) determined by the steering command. Thereby, the DSECU can automatically change the steering angle of the vehicle SV (steer the steering wheels) via the EPS·ECU 50.

[0070] <Summary of the basic steering avoidance control>

[0071] As Figure 2 shown, it is assumed that the following situation has occurred: When the vehicle SV is traveling in the driving lane LA1 which is a straight road, there is a preceding vehicle OV1 as a three-dimensional object (target) in the front area of the vehicle SV.

[0072] Whenever a predetermined time has elapsed, the DSECU identifies the driving lane LA1 divided by the left white line WL and the right white line WR based on the position information of the left white line WL and the right white line WR.

[0073] Moreover, on the basis of assuming to maintain the current driving state of the own vehicle SV, DSECU calculates the predicted driving trajectory of the own vehicle SV through operations based on the steering angle θs, yaw rate Yr, and vehicle speed Vs of the own vehicle SV.

[0074] On the basis of assuming to maintain the current driving state of the preceding vehicle OV1, DSECU calculates the predicted movement trajectory of the preceding vehicle OV1 through operations based on the target information of the preceding vehicle OV1. The predicted movement trajectory of the preceding vehicle OV1 is the path that is predicted to be traveled by the preceding vehicle OV1. More specifically, DSECU obtains the predicted movement trajectory based on the multiple detection positions of the preceding vehicle OV1 acquired every time a predetermined time has elapsed in the past and the detection position of the preceding vehicle OV1 at the current location.

[0075] DSECU determines whether the collision possibility condition is satisfied based on the predicted driving trajectory of the own vehicle SV and the predicted movement trajectory of the preceding vehicle OV1. The collision possibility condition is a condition that is satisfied when there is a possibility of the own vehicle SV colliding with the preceding vehicle OV1 (the two predicted driving trajectories intersect) under the condition that the preceding vehicle OV1 maintains the current movement state and the own vehicle SV maintains the current driving state. When DSECU determines that the collision possibility condition is satisfied, it determines that there is a possibility of the own vehicle SV colliding with the preceding vehicle OV1 (that is, there is a preceding vehicle OV1 that has a possibility of colliding with the own vehicle SV).

[0076] When DSECU determines that there is a possibility of the own vehicle SV colliding with the preceding vehicle OV1, it calculates the time to collision TTC for the preceding vehicle OV1 based on the longitudinal distance Dfx and relative speed Vfx of the preceding vehicle OV1. More specifically, DSECU calculates the time to collision TTC by inverting the sign of the value obtained by dividing the longitudinal distance Dfx by the relative speed Vfx (that is, TTC = -Dfx / Vfx). It should be noted that DSECU can also calculate the time to collision TTC by dividing the distance between the predicted collision point of the own vehicle SV and the preceding vehicle OV1 (the intersection point of the two predicted driving trajectories) and the own vehicle SV by the vehicle speed Vs of the own vehicle SV at the current time point.

[0077] Moreover, the DSECU calculates the trajectory that can be taken to avoid a collision between the own vehicle SV and the preceding vehicle OV1 by a well-known method. More specifically, the DSECU sets the trajectory that can avoid interference (collision) with the preceding vehicle OV1 by turning (changing the route direction) the own vehicle SV as the avoidance target trajectory a1 (for example, for the determination of the avoidance target trajectory a1, refer to Japanese Patent Application Laid-Open No. 2017-105383, Japanese Patent Application Laid-Open No. 2017-43262, Japanese Patent Application Laid-Open No. 2018-106230, etc.).

[0078] In this example, the avoidance target trajectory a1 is determined to satisfy at least all of the following conditions (Condition A1 to Condition A3) based on the target information of the preceding vehicle OV1 and the position information of the left white line and the right white line, etc.

[0079] · Condition A1: There is an avoidance space SP1 through which the own vehicle SV can pass on either the left or the right side of the preceding vehicle OV1 at a location where a collision between the own vehicle SV and the preceding vehicle OV1 is predicted.

[0080] · Condition A2: When the own vehicle SV travels along the avoidance target trajectory a1 from the current driving state, the own vehicle SV does not deviate from the driving lane LA1 defined by the left white line and the right white line.

[0081] · Condition A3: When the own vehicle SV travels along the avoidance target trajectory a1 from the current driving state, the magnitudes of the lateral acceleration Gy and the yaw rate Yr can be maintained below their respective threshold values, and the vehicle can pass through the avoidance space SP1.

[0082] After that, the DSECU determines whether the specified steering avoidance control start condition is satisfied. The steering avoidance control start condition is a condition that is satisfied when both the first condition and the second condition described below are satisfied.

[0083] First condition: The first condition is satisfied when the time to collision TTC is shorter than the threshold time TTCth. For convenience, the threshold time TTCth is also referred to as the "collision determination threshold time". The time to collision TTC is a value whose smaller value indicates a higher possibility of collision, and can also be referred to as a collision index value. Therefore, it can be said that the first condition is satisfied when the possibility of collision indicated by the collision index value becomes equal to or higher than the collision possibility threshold.

[0084] Second condition: The second condition is satisfied when there is no "other target other than the preceding vehicle OV1" that collides with the own vehicle SV or whose distance from the own vehicle SV becomes equal to or less than the specified minimum distance, assuming that the own vehicle SV travels along the avoidance target trajectory a1.

[0085] When the steering avoidance control start condition is satisfied, the DSECU calculates the target yaw rate for the host vehicle SV to travel along the avoidance target trajectory a1.

[0086] The DSECU calculates the target steering angle of the steering wheel of the host vehicle SV for the target yaw rate based on the calculated target yaw rate and the vehicle speed Vs of the host vehicle SV, and sends a steering command for collision avoidance representing the target steering angle to the EPS·ECU50.

[0087] The EPS·ECU50 calculates the target steering torque required to make the actual steering angle coincide with the target steering angle. The EPS·ECU50 drives the steering motor 52 to steer the steering wheel of the host vehicle SV in such a way as to output a steering torque corresponding to the calculated target steering torque. Accordingly, the DSECU makes the host vehicle SV travel along the avoidance target trajectory a1 by changing the steering angle of the host vehicle SV via the EPS·ECU50. In this case, the host vehicle SV does not deviate from the driving lane LA1, does not collide with other objects, and can avoid a collision with the preceding vehicle OV1. The above is an outline of the basic steering avoidance control.

[0088] <Outline of Steering Avoidance Control Corresponding to the State of the Direction Indicator>

[0089] When the DSECU determines that there is a possibility of a collision between the host vehicle SV and the preceding vehicle OV1, it acquires the above-described "direction indicator information including direction indication information" from the surrounding sensor 21.

[0090] Furthermore, the DSECU acquires information on the avoidance planned direction of the host vehicle SV based on the avoidance target trajectory a1. For example, when the avoidance target trajectory a1 bends to the right (i.e., when the avoidance target trajectory a1 is a trajectory that moves the position of the host vehicle SV in the lane width direction to the right), the DSECU acquires information indicating "the meaning that the avoidance planned direction is the right direction" as the information on the avoidance planned direction. Similarly, when the avoidance target trajectory a1 bends to the left (i.e., when the avoidance target trajectory a1 is a trajectory that moves the position of the host vehicle SV in the lane width direction to the left), the DSECU acquires information indicating "the meaning that the avoidance planned direction is the left direction" as the information on the avoidance planned direction.

[0091] (When the state of the direction indicator is not the direction indication state)

[0092] When the state of the direction indicator is not the aforementioned direction indication state, the DSECU sets the threshold time TTCth used in the first condition of the steering avoidance control start condition to the first time TTC1. It should be noted that for convenience, the steering avoidance control start condition in which the threshold time TTCth used in the first condition is set to the first time TTC1 is also referred to as the "first start condition". It can be said that setting the threshold time TTCth to the first time TTC1 is synonymous with setting the collision possibility threshold to the first possibility threshold.

[0093] More specifically described, the DSECU determines the first time TTC1 by applying the absolute value (|Vfx|) of the relative speed Vfx of the preceding vehicle OV1 to Figure 3 the first mapping Map1 shown as a look-up table. According to the first mapping Map1, as shown by the dashed line Ln1, the first time TTC1 is set such that the larger the absolute value of the relative speed Vfx of the preceding vehicle OV1, the longer the first time TTC1.

[0094] (When the indication direction of the direction indicator of the preceding vehicle OV1 is the same as the avoidance planned direction of the own vehicle SV)

[0095] In Figure 4 the example shown, the right direction indicator of the preceding vehicle OV1 is operating (i.e., the indication direction of the direction indicator is the right direction), and the avoidance planned direction of the own vehicle SV is the right direction. Therefore, the indication direction of the direction indicator is the same as the avoidance planned direction of the own vehicle SV.

[0096] In such a case where the indication direction of the direction indicator of the preceding vehicle OV1 is the same as the avoidance planned direction of the own vehicle SV, there is a possibility that the preceding vehicle OV1 starts to move in the indication direction after the start of the steering avoidance control. In the case where the preceding vehicle OV1 starts to move in the indication direction after the start of the steering avoidance control, although the steering avoidance control is intended to avoid a collision between the own vehicle SV and the preceding vehicle OV1, a collision between the own vehicle SV and the preceding vehicle OV1 may occur. Therefore, in this case, the DSECU prohibits the execution of the steering avoidance control. Thereby, the DSECU can reduce the possibility of a collision between the own vehicle SV and the preceding vehicle OV1 although the steering avoidance control is executed. It should be noted that the DSECU can also execute a collision avoidance control achieved by well-known automatic braking control. Thereby, in this case, a collision between the own vehicle SV and the preceding vehicle OV1 is avoided by the automatic braking control.

[0097] (When the indication direction of the preceding vehicle OV1 is different from the avoidance planned direction of the own vehicle SV)

[0098] In Figure 5In the example shown, the left turn indicator of the preceding vehicle OV1 is operating (i.e., the indicated direction of the turn indicator is the left direction), and the avoidance predetermined direction of the host vehicle SV is the right direction. Therefore, the indicated direction of the turn indicator is different from the avoidance predetermined direction of the host vehicle SV (they are opposite to each other). When the indicated direction of the turn indicator of the preceding vehicle OV1 is different from the avoidance predetermined direction of the host vehicle SV, after the host vehicle SV starts to travel along the avoidance path (i.e., after the steering avoidance control starts), there is a high possibility that the preceding vehicle OV1 will move away from the host vehicle SV. Thus, if the steering avoidance control is started in advance and then the preceding vehicle OV1 moves in the indicated direction, the lateral movement amount of the host vehicle SV based on the steering avoidance control will become excessive. As a result, there is a possibility that the driver will be bored with the steering avoidance control. In other words, there is a possibility that, although it is expected that the preceding vehicle OV1 will move away from the host vehicle SV and the driver has determined that avoidance by steering is not required or a slight steering is sufficient, the steering avoidance control that does not consider the movement of such a preceding vehicle OV1 will still be performed. As a result, there is a possibility that the driver will be bored with the steering avoidance control.

[0099] Therefore, in this case, the DSECU sets the first condition such that the inter-vehicle distance between the host vehicle SV and the preceding vehicle OV1 at the time point when the first condition (TTC < TTCth) is satisfied is shorter than the inter-vehicle distance at the time point when the first condition is satisfied in the case where the state of the turn indicator is not the turn-indicating state. Specifically stated, in this case, the DSECU sets the threshold time TTCth of the first condition to a second time TTC2 that is shorter than the first time TTC1. It should be noted that, for convenience, the steering avoidance control start condition in which the threshold time TTCth used in the first condition is set to the second time TTC2 is also referred to as the "second start condition". It can be said that setting the threshold time TTCth to the second time TTC2 is synonymous with setting the collision possibility threshold to "a second possibility threshold greater than the first possibility threshold".

[0100] More specifically stated, the DSECU determines the second time TTC2 by applying the absolute value (|Vfx|) of the relative speed Vfx of the preceding vehicle OV1 to Figure 6 the second mapping Map2 shown as a look-up table. According to the second mapping Map2, as shown by the solid line Ln2, the second time TTC2 is set such that the greater the absolute value of the relative speed Vfx of the preceding vehicle OV1, the longer the second time TTC2. Moreover, according to the second mapping Map2, the second time TTC2 is set such that, for any absolute value (|Vfx|) of the relative speed Vfx of the preceding vehicle OV1, the second time TTC2 is shorter than the first time TTC1 shown by the dashed line Ln1.

[0101] Therefore, when the relative speed Vfx of the preceding vehicle OV1 is a certain value (any value), the timing at which the steering avoidance control start condition is satisfied when the threshold time TTCth is set to the second time TTC2 is later than the timing at which the steering avoidance control start condition is satisfied when the threshold time TTCth is set to the first time TTC1. In other words, the second start condition is a condition that can be satisfied when the inter-vehicle distance between the host vehicle SV and the preceding vehicle OV1 is shorter than the inter-vehicle distance between the host vehicle SV and the preceding vehicle OV1 at the time when the first start condition is satisfied. Thereby, the DSECU can reduce the possibility that the driver gets bored with the steering avoidance control.

[0102] <Specific operations>

[0103] Whenever a predetermined time elapses, the CPU of the DSECU (hereinafter, simply referred to as "CPU") executes Figures 7 to 9 each of the routines illustrated by the flowcharts.

[0104] Therefore, when a predetermined timing is reached, the CPU starts processing from Figure 7 step 700 of and proceeds to step 705 to determine whether the value of the determination flag (collision possibility flag) Xf is "0". When the value of the flag Xf is "0", it indicates that there is no preceding vehicle OV1 that may collide with the host vehicle SV. When the value of the flag Xf is "1", it indicates that there is a preceding vehicle OV1 that may collide with the host vehicle SV. The value of the flag Xf is set to "0" in the initialization routine executed by the CPU when an ignition key switch (not shown) of the host vehicle SV is changed from the off position to the on position.

[0105] When the value of the flag Xf is "0", the CPU determines "Yes" in step 705 and proceeds to step 710 to determine whether there is a preceding vehicle OV1 in a predetermined front area of the host vehicle SV based on the target information acquired from the surrounding sensor 21. For example, the front area is a range within a predetermined distance from the host vehicle SV in the traveling direction of the host vehicle SV and has a width wider than the vehicle width of the host vehicle SV by a predetermined distance in the vehicle width direction of the host vehicle SV.

[0106] When there is no preceding vehicle OV1 in the front area of the host vehicle SV, the CPU determines "No" in step 710 and proceeds to step 795 to temporarily end this routine.

[0107] When there is a preceding vehicle OV1 in the front area of the host vehicle SV, the CPU determines "Yes" in step 710 and proceeds to step 715 to determine whether there is a possibility of collision between the host vehicle SV and the preceding vehicle OV1 by the above method. That is, the CPU determines whether the above-described collision possibility condition has been satisfied.

[0108] When there is no possibility of the own vehicle SV colliding with the preceding vehicle OV1, the CPU determines "No" in step 715 and proceeds to step 795, temporarily ending this routine.

[0109] On the contrary, when there is a possibility of the own vehicle SV colliding with the preceding vehicle OV1, the CPU determines "Yes" in step 715 and proceeds to step 720, setting the value of the flag Xf to "1". After that, the CPU proceeds to step 795 and temporarily ends this routine.

[0110] It should be noted that when the value of the flag Xf is "1" at the time point when the CPU executes the process of step 705, the CPU determines "No" in step 705 and proceeds to step 795, temporarily ending this routine.

[0111] When a prescribed timing is reached, the CPU starts processing from Figure 8 step 800 and proceeds to step 805 to determine whether the steering avoidance control is not in execution (whether the steering avoidance control is not being executed). More specifically, at the current time point, during the control execution period from the start of the steering avoidance control to the end of the steering avoidance control (or until the steering avoidance control stops), the CPU determines that the steering avoidance control is in execution (refer to step 910 described later. Figure 9 ). When the current time point is within a period outside the control execution period, the CPU determines that the steering avoidance control is not in execution. When the current time point is within the control execution period, that is, when the steering avoidance control is in execution, the CPU determines "No" in step 805 and proceeds to step 895, temporarily ending this routine.

[0112] On the contrary, when the steering avoidance control is not in execution, the CPU determines "Yes" in step 805 and proceeds to step 810 to determine whether the value of the flag Xf is "1".

[0113] When the value of the flag Xf is "0", the CPU determines "No" in step 810 and proceeds to step 895, temporarily ending this routine.

[0114] On the contrary, when the value of the flag Xf is "1", the CPU determines "Yes" in step 810 and proceeds to step 815 to calculate the avoidance target trajectory a1 for the preceding vehicle OV1 that was determined to have a possibility of colliding with the own vehicle SV in step 715. After that, the CPU proceeds to step 820 to determine whether there is an avoidance target trajectory a1 (that is, whether there is a trajectory that satisfies all the conditions of the above-mentioned conditions A1 to A3).

[0115] In the case where there is no avoidance target trajectory a1, the CPU determines "No" in step 820 and proceeds to step 825. After setting the value of flag Xf to "0", the CPU enters step 895 and temporarily ends this routine. Therefore, in this case, the steering avoidance control for the preceding vehicle OV1 is not performed (steering avoidance control is prohibited). However, in this case, the automatic braking control is generally executed.

[0116] On the other hand, in the case where there is an avoidance target trajectory a1, the CPU determines "Yes" in step 820 and proceeds to step 830 to obtain the avoidance planned direction of the host vehicle SV based on the information about the avoidance planned direction. After that, the CPU enters step 835 and determines whether the state of the direction indicator is the aforementioned direction indication state (whether the indication direction of the direction indicator of the preceding vehicle OV1 is obtained) based on the information about the indication direction.

[0117] In the case where the state of the direction indicator is not the aforementioned direction indication state, the CPU determines "No" in step 835. After sequentially executing the processes of steps 840 and 845 described below, the CPU enters step 850.

[0118] Step 840: The CPU obtains the first time TTC1 by applying the absolute value (|Vfx|) of the relative speed Vfx of the preceding vehicle OV1 to the first map Map1.

[0119] Step 845: The CPU sets the threshold time TTCth to the first time TTC1.

[0120] After that, for the CPU, when entering step 850, it determines whether the above-mentioned steering avoidance control start conditions (i.e., the conditions of both the first condition and the second condition) are satisfied. It should be noted that in this case, the first time TTC1 is set as the threshold time TTCth of the first condition.

[0121] In the case where the steering avoidance control start conditions are not satisfied, the CPU determines "No" in step 850 and enters step 895 to temporarily end this routine.

[0122] In the case where the steering avoidance control start conditions are satisfied, the CPU determines "Yes" in step 850 and enters step 855 to start the execution of the steering avoidance control. That is, the CPU starts to drive the host vehicle SV along the avoidance target trajectory a1. After that, the CPU enters step 895 and temporarily ends this routine.

[0123] At the time point when the CPU executes the process of step 835, when the state of the direction indicator is the aforementioned direction indication state, the CPU determines "yes" in step 835 and enters step 860. The CPU obtains the indicated direction based on the information about the indicated direction in step 860. Then, the CPU enters step 865 to determine whether the indicated direction of the direction indicator is different from the avoidance predetermined direction.

[0124] When the indicated direction of the direction indicator is the same as the avoidance predetermined direction, the CPU determines "no" in step 865 and enters step 825. After setting the value of the flag Xf to "0", it enters step 895 and temporarily ends this routine. Therefore, in this case, the steering avoidance control for the preceding vehicle OV1 is not performed (the steering avoidance control is prohibited.).

[0125] When the indicated direction of the direction indicator is different from the avoidance predetermined direction, the CPU determines "yes" in step 865. After sequentially executing the processes of "step 870 and step 875" described below, it enters step 850.

[0126] Step 870: The CPU obtains the second time TTC2 by applying the absolute value (|Vfx|) of the relative speed Vfx of the preceding vehicle OV1 to the second map Map2.

[0127] Step 875: The CPU sets the threshold time TTCth to the second time TTC2. As described above, the second time TTC2 for any absolute value (|Vfx|) is shorter than the first time TTC1 for that any absolute value (|Vfx|).

[0128] For the CPU, when entering step 850, it determines whether the above-mentioned steering avoidance control start conditions (that is, the conditions of both the first condition and the second condition) are satisfied. It should be noted that in this case, the second time TTC2 is set as the threshold time TTCth of the first condition.

[0129] When the steering avoidance control start conditions are not satisfied, the CPU determines "no" in step 850 and enters step 895 to temporarily end this routine.

[0130] In contrast, when the conditions for starting the steering avoidance control are met, the CPU determines "yes" in step 850 and proceeds to step 855 to start the execution of the steering avoidance control. In this case, the steering avoidance control is started at a later timing than when the threshold time TTCth of the steering avoidance control start condition is set to the first time TTC1. In other words, since the threshold time TTCth of the steering avoidance control start condition is set to the second time TTC2, the steering avoidance control is started at a time point when the distance between the vehicle SV and the vehicle ahead OV1 at the time of starting the steering avoidance control becomes smaller than when the threshold time TTCth of the steering avoidance control start condition is set to the first time TTC1. Thereafter, the CPU proceeds to step 895 and temporarily ends this routine.

[0131] When the specified timing is reached, the CPU Figure 9 The process starts at step 900 and proceeds to step 905 to determine whether the steering avoidance control is being executed.

[0132] When the turn avoidance control is not being executed, the CPU makes a "NO" determination in step 905 and proceeds to step 995 to temporarily terminate this routine.

[0133] When the steering avoidance control is being executed, the CPU determines "yes" in step 905 and proceeds to step 910 to determine whether a predetermined end condition of the steering avoidance control has been satisfied. For example, the end condition of the steering avoidance control is satisfied when the host vehicle SV travels along the avoidance target track a1 and is aligned with the front vehicle OV1 in the lane width direction.

[0134] When the termination condition of the turn avoidance control is not satisfied, the CPU makes a “NO” determination in step 910 and proceeds to step 995 to temporarily terminate the present routine.

[0135] When the termination condition of the turn avoidance control is satisfied, the CPU makes a “Yes” determination in step 910 , and after sequentially executing the processes of “step 915 and step 920 ” described below, proceeds to step 995 and temporarily terminates this routine.

[0136] Step 915: The CPU ends the steering avoidance control.

[0137] Step 920: The CPU sets the value of flag Xf to "0".

[0138] The present disclosure is not limited to the above-described embodiments, and various modifications based on the technical idea of ​​the present disclosure can be adopted within the scope of the present disclosure.

[0139] For example, in the above-described embodiment, each of the first time TTC1 and the second time TTC2 may also be changed according to the overlap ratio LR. In this case, the overlap ratio LR is an index indicating the "degree of overlap in the vehicle width direction between the host vehicle SV and the preceding vehicle OV1" at the time point when it is predicted that the host vehicle SV will collide with the preceding vehicle OV1. The overlap ratio LR is calculated by dividing the length of the overlap between the host vehicle SV and the preceding vehicle OV1 in the vehicle width direction by the vehicle width of the host vehicle SV. In this case, the first time TTC1 is set such that the larger the overlap ratio LR, the longer the first time TTC1. The second time TTC2 is set such that the larger the overlap ratio LR, the longer the second time TTC2, and is shorter than the first time TTC1 corresponding to the same absolute value (|Vfx|) and the same overlap ratio LR.

[0140] In the above-described embodiment, at least a part of the processing performed by the target recognition unit 21c and / or the surrounding sensors 21 may also be performed by the DSECU. Moreover, the collision index value is not limited to the collision prediction time TTC. For example, it may be obtained by applying the relative relationship between the positions of the host vehicle SV and the preceding vehicle OV1, the motion state of the host vehicle SV, the motion state of the preceding vehicle OV1, etc. to a prestored look-up table.

[0141] <Modified Example>

[0142] Moreover, as another modified example of the present disclosure, the following-described modified example may also be adopted. In this modified example, an avoidance target trajectory and a limit index value (steering avoidance limit index value) TTS are obtained as described later, and steering avoidance control is started when the limit index value TTS becomes "0". That is, the limit index value TTS is the time from the current time point until the time point when steering avoidance control needs to be started. It can be said that the condition that the limit index value TTS is "0" is a condition that replaces the first condition (i.e., TTC < TTCth) of the above-described steering avoidance control start condition.

[0143] Hereinafter, with reference to Figure 10 the operation of the modified example will be specifically described. Figure 10 The vertical axis of the coordinate axes represents the lateral (vehicle width direction) position of the host vehicle SV (hereinafter referred to as "lateral position"). The origin of this vertical axis is the center position in the vehicle width direction of the front end of the host vehicle SV. This vertical axis is defined such that the left direction of the host vehicle SV is the positive direction of the vertical axis. Figure 10 The horizontal axis of the coordinate axes is the time (elapsed time) from the current time point.

[0144] First, the DSECU calculates the collision prediction time TTC as described above using the target information of the preceding vehicle OV1.

[0145] Next, the DSECU uses the target information of the preceding vehicle OV1 to obtain a first position P1a at a time point tc1 that is the collision prediction time TTC after the current time point. The first position P1a is a position where the lateral position P1 of the left rear end of the preceding vehicle OV1 at the time point tc1 is moved in the positive direction along the Figure 10 longitudinal axis direction by a specified first distance d1 (margin).

[0146] Similarly, the DSECU obtains a second position P2a at the time point tc1. The second position P2a is a position where the lateral position P2 of the right rear end of the preceding vehicle OV1 at the time point tc1 is moved in the negative direction along the Figure 10 longitudinal axis direction by a specified second distance d2 (margin).

[0147] The DSECU calculates the target trajectory of the left front end LFr of the host vehicle SV through operations based on the curve of the lateral acceleration of the host vehicle SV (the relationship between the elapsed time from the start time point of the steering avoidance control and the lateral acceleration) stored in the ROM. This curve of the lateral acceleration is, for example, the following curve: from the start time point of the steering avoidance control, as time elapses, the lateral acceleration increases from "0" to "the lateral acceleration of magnitude A" in a manner proportional to time, and then the lateral acceleration is maintained at "the lateral acceleration of magnitude A". It should be noted that when the DSECU calculates the target trajectory of the left front end LFr, it uses the value obtained by adding a negative sign to "the magnitude of the lateral acceleration specified by the curve of the lateral acceleration" as the lateral acceleration. For the DSECU, in such a way that the starting point (starting point) of the calculated target trajectory is located on the path LLFr that the left front end LFr of the host vehicle SV will pass through, and the target trajectory is moved in such a way that it passes through the second position P2a, thereby obtaining the collision avoidance prediction trajectory LO1 of the left front end LFr of the host vehicle SV.

[0148] Next, the DSECU determines the "time point when steering should start (time point when steering start is required) TS1" required for the left front end LFr of the host vehicle SV to move on the collision avoidance prediction trajectory LO1. Moreover, the DSECU calculates the time from the current time point to the time point when steering start is required TS1 as the first steering start margin time T1. It should be noted that the DSECU can also calculate the first steering start margin time T1 by dividing the distance from the position of the current time point of the host vehicle SV to the starting point PSL of the collision avoidance prediction trajectory LO1 by the vehicle speed Vs of the current time point of the host vehicle SV.

[0149] Similarly, the DSECU calculates the target trajectory of the right front end RFr of the vehicle SV through operations based on the above-mentioned lateral acceleration curve. When the DSECU calculates the target trajectory of the right front end RFr, it uses the value obtained by adding a positive sign to "the magnitude of the lateral acceleration defined by the lateral acceleration curve" as the lateral acceleration. For the DSECU, the starting point (starting point) of the target trajectory calculated in this way is located on the path LRFr that the right front end RFr of the vehicle SV will pass through, and the target trajectory moves in such a way that it passes through the first position P1a, thereby calculating the collision avoidance prediction trajectory RO1 of the right front end RFr of the vehicle SV.

[0150] Next, the DSECU determines the "time point when steering should start (time point when steering start is required) TS2" required for the right front end RFr of the vehicle SV to move on the collision avoidance prediction trajectory RO1. Moreover, the DSECU calculates the time from the current time point to the time point TS2 when steering start is required as the second steering start margin time T2. It should be noted that the DSECU can also calculate the second steering start margin time T2 by dividing the distance from the position of the current time point of the vehicle SV to the starting point PSR of the collision avoidance prediction trajectory RO1 by the vehicle speed Vs of the current time point of the vehicle SV.

[0151] Next, an overview of the steering avoidance control performed for this modification example will be described.

[0152] The DSECU of the modification example determines whether the above-mentioned collision possibility condition is satisfied. When it is determined that the collision possibility condition is satisfied (that is, when it is determined that there is a preceding vehicle OV1 that may collide with the vehicle SV), the following processing is performed.

[0153] (1) The DSECU calculates the collision avoidance prediction trajectory LO1, the first steering start margin time T1, the collision avoidance prediction trajectory RO1, and the second steering start margin time T2 by the above-mentioned method.

[0154] (2) The DSECU determines whether the right-direction steering avoidance condition is satisfied. The right-direction steering avoidance condition is satisfied when the following two conditions are satisfied.

[0155] · To the right of the preceding vehicle OV1 at the time point when it is predicted that the vehicle SV will collide with the preceding vehicle OV1 (the time point tc1 after the collision prediction time TTC has elapsed from the current time point), there is an avoidance space where the vehicle SV will not deviate from the driving lane and the vehicle SV can pass through.

[0156] · When the host vehicle SV travels in such a manner that the left front end LFr of the host vehicle SV moves on the collision avoidance prediction trajectory LO1, there is no "object other than the preceding vehicle OV1" that collides with the host vehicle SV or has a distance from the host vehicle SV that becomes equal to or less than the specified minimum distance.

[0157] (3) The DSECU determines whether the left - hand turn avoidance condition is satisfied. The left - hand turn avoidance condition is satisfied when the following two conditions are satisfied.

[0158] · On the left side of the preceding vehicle OV1 at the time point tc1 when it is predicted that the host vehicle SV will collide with the preceding vehicle OV1, there is an avoidance space through which the host vehicle SV can pass without deviating from the driving lane.

[0159] · When the host vehicle SV travels in such a manner that the right front end RFr of the host vehicle SV moves on the collision avoidance prediction trajectory RO1, there is no "object other than the preceding vehicle OV1" that collides with the host vehicle SV or has a distance from the host vehicle SV that becomes equal to or less than the specified minimum distance.

[0160] (4) When neither the right - hand turn avoidance condition nor the left - hand turn avoidance condition is satisfied, the DSECU prohibits the steering avoidance control. At this time, the DSECU sets the limit index value TTS to a time that is substantially infinite.

[0161] (5) When the right - hand turn avoidance condition is satisfied but the left - hand turn avoidance condition is not satisfied, the DSECU uses the collision avoidance prediction trajectory LO1 as the avoidance target trajectory for the left front end LFr of the host vehicle SV, and uses the first steering start margin time T1 as the limit index value TTS.

[0162] (6) When the left - hand turn avoidance condition is satisfied but the right - hand turn avoidance condition is not satisfied, the DSECU uses the collision avoidance prediction trajectory RO1 as the avoidance target trajectory for the right front end RFr of the host vehicle SV, and uses the second steering start margin time T2 as the limit index value TTS.

[0163] (7) When both the right - hand turn avoidance condition and the left - hand turn avoidance condition are satisfied, the DSECU uses the longer of the first steering start margin time T1 and the second steering start margin time T2 as the limit index value TTS. Moreover, the DSECU uses the collision avoidance prediction trajectory corresponding to the longer of the first steering start margin time T1 and the second steering start margin time T2 as the avoidance target trajectory for the front end (left front end LFr or right front end RFr) of the corresponding host vehicle SV.

[0164] (8) Whenever the specified time has elapsed, the DSECU repeatedly executes the processes (1) to (7) above and determines whether the limit index value TTS has become 0. When the limit index value TTS becomes 0, the DSECU further performs the following process.

[0165] (9) The DSECU determines whether the state of the direction indicator is the direction indication state based on the direction indicator information. When the DSECU determines that the state of the direction indicator is not the direction indication state, it changes the steering angle of the own vehicle SV so that "one of the right front end RFr and the left front end LFr of the own vehicle SV" suitable for the collision avoidance prediction trajectory set as the avoidance target trajectory moves on the avoidance target trajectory. That is, the steering avoidance control is started. For convenience, the start time point of this steering avoidance control when the collision avoidance prediction trajectory LO1 is adopted as the avoidance target trajectory is referred to as the "right direction normal time point". For convenience, the start time point of this steering avoidance control when the collision avoidance prediction trajectory RO1 is adopted as the avoidance target trajectory is referred to as the "left direction normal time point".

[0166] (10) When the DSECU determines that the state of the direction indicator of the preceding vehicle OV1 is the direction indication state based on the direction indicator information and the avoidance target trajectory, it determines whether the indication direction of the direction indicator of the preceding vehicle OV1 is different from the avoidance scheduled direction of the own vehicle SV. When the DSECU determines that the indication direction of the direction indicator is the same as the avoidance scheduled direction of the own vehicle SV, it prohibits (does not start) the steering avoidance control.

[0167] (11) In contrast, when the DSECU determines that the state of the direction indicator of the preceding vehicle OV1 is the direction indication state based on the direction indicator information and the avoidance target trajectory, and when it determines that the indication direction of the direction indicator of the preceding vehicle OV1 is different from the avoidance scheduled direction of the own vehicle SV, it does not immediately start the steering avoidance control but further performs the following process.

[0168] (11-1) The case where the avoidance scheduled direction is the right direction (that is, the right direction steering avoidance condition is established, but the left direction steering avoidance condition is not established, and the collision avoidance prediction trajectory LO1 is adopted as the avoidance target trajectory)

[0169] In this case, the DSECU obtains the second position P2a by moving the lateral position P2 of the right rear end of the preceding vehicle OV1 at the time point tc1 along the Figure 10 longitudinal axis of the coordinate axis in the negative direction by a "specified correction second distance smaller than the aforementioned second distance d2".

[0170] Then, every time a predetermined time elapses, the DSECU repeatedly performs the following process: Using the second position P2a, the collision avoidance prediction trajectory LO1 of the left front end LFr is recalculated as the avoidance target trajectory, and further, the first steering start margin time T1 (the time until the steering start time point TS1) as the limit index value TTS is recalculated. From the time point when the first steering start margin time T1 obtained in this way becomes "0" (hereinafter, for convenience, referred to as the "right direction delay time point"), the steering angle of the own vehicle SV is changed so that the left front end LFr moves on the avoidance target trajectory (collision avoidance prediction trajectory LO1). That is, the steering avoidance control is started. This right direction delay time point is later in time than the aforementioned right direction normal time point. In other words, the inter-vehicle distance between the own vehicle SV at the right direction delay time point and the preceding vehicle OV1 is shorter than the inter-vehicle distance between the own vehicle SV at the right direction normal time point and the preceding vehicle OV1. Thus, similarly to the embodiment, this modification can reduce the possibility that the driver gets bored with the steering avoidance control.

[0171] (11 - 2) Case where the avoidance predetermined direction is the left direction (that is, the left direction steering avoidance condition is satisfied, but the right direction steering avoidance condition is not satisfied, and the collision avoidance prediction trajectory RO1 is adopted as the avoidance target trajectory)

[0172] In this case, the DSECU calculates the position obtained by moving the lateral position P1 of the left rear end of the preceding vehicle OV1 at the time point tc1 along the Figure 10 positive direction of the longitudinal axis of the coordinate axis by a "predetermined corrected first distance smaller than the aforementioned first distance d1" as the first position P1a.

[0173] Then, every time a predetermined time elapses, the DSECU repeatedly performs the following process: Using the first position P1a, the collision avoidance prediction trajectory RO1 of the right front end RFr is recalculated as the avoidance target trajectory, and further, the second steering start margin time T2 (the time until the steering start time point TS2) as the limit index value TTS is recalculated. From the time point when the second steering start margin time T2 obtained in this way becomes "0" (hereinafter, for convenience, referred to as the "left direction delay time point"), the steering angle of the own vehicle SV is changed so that the right front end RFr moves on the avoidance target trajectory (collision avoidance prediction trajectory RO1). That is, the steering avoidance control is started. This left direction delay time point is later in time than the aforementioned left direction normal time point. In other words, the inter-vehicle distance between the own vehicle SV at the left direction delay time point and the preceding vehicle OV1 is shorter than the inter-vehicle distance between the own vehicle SV at the left direction normal time point and the preceding vehicle OV1. Thus, similarly to the embodiment, this modification can reduce the possibility that the driver gets bored with the steering avoidance control.

Claims

1. A collision avoidance assistance device, comprising: A surrounding sensor, including a camera sensor that captures an area in front of the own vehicle to acquire image data representing the area, and acquires information about a preceding vehicle based at least on the image data, wherein, The leading vehicle is another vehicle present in the front area of the host vehicle; A steering angle actuator configured to be able to change the steering angle of the host vehicle; And A control unit, when it is determined that the collision possibility condition is satisfied based on the information from the surrounding sensors, obtains a target trajectory for avoiding a collision between the host vehicle and the leading vehicle through an operation using the image data, and when it is determined that a prescribed steering avoidance control start condition is satisfied, starts a steering avoidance control for controlling the steering angle actuator so that the host vehicle travels along the target trajectory, wherein the collision possibility condition is satisfied when there is a possibility of a collision between the host vehicle and the leading vehicle. The control unit is configured to: Obtain avoidance predetermined direction information regarding which direction, left or right, the target trajectory changes the route of the host vehicle; Based on the image data, determine whether the state of the direction indicator of the leading vehicle is a direction indication state indicating the predetermined moving direction of the leading vehicle, and when it is determined that the state of the direction indicator is the direction indication state, obtain information regarding the indicated direction indicating which direction, left or right, the predetermined moving direction of the leading vehicle indicated by the direction indicator is based on the image data; When it is determined that the state of the direction indicator is not the direction indication state, set the steering avoidance control start condition as a first start condition, which can be satisfied when the inter-vehicle distance between the host vehicle and the leading vehicle becomes a first distance; When it is determined that the state of the direction indicator is the direction indication state, determine whether the predetermined moving direction of the leading vehicle is the same as the avoidance predetermined direction based on the information regarding the indicated direction and the avoidance predetermined direction information; When it is determined that the predetermined moving direction of the leading vehicle is the same as the avoidance predetermined direction, prohibit the execution of the steering avoidance control; When it is determined that the predetermined moving direction of the leading vehicle is different from the avoidance predetermined direction, set the steering avoidance control start condition as a second start condition, which can be satisfied at a time point when the inter-vehicle distance becomes a distance shorter than the first distance at the time point when the first start condition can be satisfied.

2. The collision avoidance assistance device according to claim 1, wherein The steering avoidance control start condition at least includes a condition that a collision prediction time, which is a predicted value of the time until a collision between the host vehicle and the leading vehicle, is shorter than a prescribed collision determination threshold time; The control unit sets the collision determination threshold time used under the first start condition as a first time; The control unit sets the collision determination threshold time used under the second start condition as a second time shorter than the first time.

Images