Collision avoidance assistance device

Abstract

Collision avoidance assistance device (10), comprising: a lane marking detecting device (21b) that detects a left lane marking and a right lane marking provided on a road on which a vehicle is traveling; an obstacle detection device (21) which detects an obstacle in an area ahead of the vehicle; an electric motor (52) that applies a steering torque to a steering mechanism comprising a steering wheel of the vehicle to change a steering angle of at least one steered wheel of the vehicle; and an electronic control unit (20) configured to: to calculate a lane marking detection reliability level, which represents a reliability level of an overall detection result of the left and right lane markings; and to carry out emergency steering control, including processes for: Determining a target steering torque that changes the steering angle to avoid a collision of the vehicle with the obstacle without moving the vehicle out of the lane when (i) the electronic control unit (20) determines that the vehicle has a high probability of colliding with the obstacle, (ii) a lane defined by the left and right lane markings is a straight lane, and (iii) the calculated lane marking detection reliability level is greater than or equal to a first threshold reliability level; and Driving the electric motor (52) to apply the steering torque corresponding to the determined target steering torque to the steering mechanism, wherein the electronic control unit (20) is configured to stop the execution of the emergency steering control when the reliability level of the lane marking detection becomes lower than a second threshold reliability level set to a value lower than the first threshold reliability level.

Description

BACKGROUND area

[0001] The invention relates to a collision avoidance assist device that guides a vehicle to avoid a collision of the vehicle with an obstacle when the vehicle is likely to collide with the obstacle. Description of the state of the art

[0002] The collision avoidance assist device disclosed in JP 2017-43262 A is configured to detect an obstacle in front of a vehicle and steer steered wheels of the vehicle to avoid collision of the vehicle with the obstacle when the vehicle is likely to collide with the obstacle.

[0003] The inventors of this application consider a collision avoidance assist device that steers the vehicle to avoid the collision of the vehicle with an obstacle so as not to move the vehicle out of a lane defined by a left white line and a right white line provided on a road on which the vehicle is moving.

[0004] Hereinafter, the lane defined by the left and right white lines on the road in which the vehicle is traveling is referred to as the "lane." The control of the vehicle's steering to avoid a collision with an obstacle and prevent the vehicle from moving out of the lane is referred to as "emergency steering control."

[0005] The collision avoidance assist device detects the lane based on the left and right white lines present on the road. If the white lines are incorrectly detected, the corresponding emergency steering control cannot be executed. Therefore, the collision avoidance assist device executes the emergency steering control as long as the overall reliability of the left and right white lines is relatively high.

[0006] For the same reasons, the collision avoidance assist device stops or cancels the execution of the emergency steering control when the reliability level of the overall detection results of the left and right white lines is relatively low while the emergency steering control is being executed.

[0007] During the emergency steering control, the collision avoidance assist device may fail to detect part of the white line due to the lateral movement of the vehicle and the obstruction of part of the white line. It has been found that the reliability of the detection results of the white line on the left or right side of the obstacle is low compared to the side of the obstacle the vehicle is passing. Therefore, the overall reliability of the detection results of the left and right white lines by the collision avoidance assist device may be low while the emergency steering control is being executed. Therefore, the collision avoidance assist device may unnecessarily abort the execution of the emergency steering control. SUMMARY

[0008] The invention was made to solve the problems described above. An object of the invention is to provide a collision avoidance assist device that can eliminate unnecessary execution of a process for stopping the execution of emergency steering control.

[0009] A collision avoidance assist device (10) according to the invention comprises (i) a lane marking detection device (21b) that detects a left lane marking (WL) and a right lane marking (WR) provided on a road on which a vehicle (SV) is traveling, (ii) an obstacle detection device (21) that detects an obstacle in an area in front of the vehicle (SV), (iii) an electric motor (52) that applies a steering torque to a steering mechanism including a steering wheel (SW) of the vehicle (SV) to change a steering angle of at least one steered wheel of the vehicle (SV), and (iv) an electronic control unit (20).

[0010] The electronic control unit (20) is configured to calculate a lane marking recognition reliability level, which represents a reliability level of an overall recognition result of the left and right lane markings (WL and WR) (see step 510 in Fig. 5). Furthermore, the electronic control unit (20) is configured to execute an emergency steering control (see step 520 in Fig. 5). The emergency steering control includes a process for determining a target steering torque that changes the steering angle to avoid a collision of the vehicle (SV) with the obstacle so as not to move the vehicle (SV) out of the lane when (i) the electronic control unit (20) determines that the vehicle (SV) has a high probability of colliding with the obstacle, (ii) a lane defined by the left and right lane markings (WL and WR) is a straight lane, and (iii) the calculated reliability level of the lane marking detection is equal to or higher than a first threshold reliability level (see cases of determining "Yes" at steps 505 and 515 in Fig. 5). Furthermore, the emergency steering control includes a process for controlling the electric motor (52) to apply the steering torque corresponding to the determined target steering torque to the steering mechanism.

[0011] The electronic control unit (20) is configured to stop the execution of the emergency steering control (see a step 620 in Fig. 6), when the reliability level of the lane marking detection becomes lower than a second threshold reliability level set to a value lower than the first threshold reliability level (see a case of determining “No” in a step 615 in Fig. 6).

[0012] As a result, the lane marking detection reliability level will not readily fall below the second threshold reliability level, even if the lane marking detection reliability level is lowered due to (i) the lateral movement of the vehicle resulting from the execution of the emergency steering control and (ii) the obscuration of the white line by the obstacle. Thus, the unnecessary execution of the operation of stopping the execution of the emergency steering control can be avoided.

[0013] According to one aspect of the invention, the electronic control unit (20) may be configured to calculate the reliability level of lane marking detection based on the left and right lane markings (WL and WR) before the electronic control unit (20) begins executing the emergency steering control. In this case, the electronic control unit (20) may be configured to calculate the reliability level of lane marking detection based on only one of the left and right lane markings (WL and WR) on the side of the obstacle that the vehicle (SV) is passing while the electronic control unit (20) is executing the emergency steering control.

[0014] According to this aspect of the invention, the reliability level of lane marking detection is calculated based only on the lane marking having the reliability level of the detection results that has not been lowered due to vehicle behaviors derived from the execution of the emergency steering control. In this way, the reliability level of lane marking detection can be maintained at a high level while the emergency steering control is being executed. It can thus be ensured that the reliability of lane detection is maintained at a higher level than the second threshold reliability level during the execution of the emergency steering control. Thus, the unnecessary execution of the process for stopping the execution of the emergency steering control can be safely eliminated.

[0015] In the above description, to facilitate understanding of the present invention, elements of the present invention that correspond to elements of a later-described embodiment have been designated by reference numerals used in the description of the embodiment and enclosed in parentheses. However, the elements of the present invention are not limited to the elements of the embodiment defined by the reference numerals. The other objects, features, and accompanying advantages of the present invention can be easily understood from the description of the embodiment of the present invention together with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a general configuration view showing a collision avoidance assist device according to an embodiment of the invention. Fig. 2 is a general plan view used to describe a summary of the functions of the collision avoidance assist device. Fig. 3 is a general plan view used to describe the summary of functions of the collision avoidance assist device. Fig. 4 is a view showing a diagram used to describe the summary of the functions of the collision avoidance assist device. Fig. 5 is a view showing a flowchart of a routine executed by a CPU of a driving assistance ECU. Fig. 6 is a view showing a flowchart of a routine executed by the CPU of the driving assistance ECU. DESCRIPTION OF THE EMBODIMENTS <konfiguration>

[0016] As in Fig. As shown in Figure 1, a collision avoidance assist device 10 according to an embodiment of the invention is installed in a vehicle SV. The collision avoidance assist device 10 includes a driving assistance ECU 20, an engine ECU 30, a braking ECU 40, an electric power steering ECU 50, and an alarm ECU 60. Hereinafter, the driving assistance ECU 20 is referred to as the "DS-ECU," and the electric power steering ECU 50 is referred to as the "EPS-ECU 50."

[0017] ECUs are electronic control units, each containing a microcomputer as its main component. ECUs are also referred to as control units. The control units are electrically connected to each other to exchange data or communicate via a CAN 70 (Controller Area Network). The microcomputer includes a CPU, a ROM, a RAM, and an interface (I / F). The CPU implements various functions by executing instructions, programs, or routines stored in the ROM. All or some of the control units can be integrated into a control unit.

[0018] An ambient sensor 21, a vehicle speed sensor 22, a yaw rate sensor 23, a longitudinal acceleration sensor 24, and a lateral acceleration sensor 25 are electrically connected to the DS-ECU. The DS-ECU receives detection signals or output signals output from the sensors. The sensors may be electrically connected to an ECU other than the DS-ECU.

[0019] The environmental sensors 21 include at least one radar sensor 21a, one camera sensor 21b, and one object detection section 21c. For simplicity, the environmental sensors 21 are also referred to as an "obstacle detection device," and the camera sensor 21b is also referred to as a "lane marking detection device."

[0020] The environmental sensors 21 detect (i) an environment around the vehicle SV, including at least one road in front of the vehicle SV, and (ii) existing objects in the environment around the vehicle SV, and collect information about the detected existing objects. The existing objects are moving objects, such as walking people and vehicles, or stationary objects, such as power poles, trees, and guardrails. Hereinafter, the existing object may be referred to as an "object."

[0021] The environmental sensors 21 calculate information regarding the detected objects, ie, object information including the information listed below, and send the information to the DS-ECU. i) A longitudinal distance Dfx to the object corresponding to a signed distance in a central axis direction or x-axis direction of the vehicle SV between a front end of the vehicle SV and the object. (ii) a lateral position Dfy of the object corresponding to a signed distance between a central position of the object and a central axis of the vehicle SV in a direction or a y-axis direction orthogonal to the direction of the central axis of the vehicle SV. iii) A relative velocity Vfx of the object corresponding to a difference between a velocity Vb of the object and a vehicle velocity Vs of the vehicle SV (Vfx = Vb - Vs). iv) Information about a type of object. v) A width W of the object (a transverse width of the object). vi) A length L of the object.

[0022] It should be noted that the longitudinal distance Dfx and the transverse position Dfy of the object are also called "detected positions".

[0023] The environmental sensors 21 detect the above-described values ​​in a predetermined xy coordinate system. An x-axis of the predetermined xy coordinate system is a coordinate axis extending a vehicle width center position of the front end of the vehicle SV in the longitudinal direction of the vehicle SV. A forward direction along the x-axis is a positive direction. A y-axis of the predetermined xy coordinate system is a coordinate axis orthogonal to the x-axis. A leftward direction along the y-axis is a positive direction. An origin of the xy coordinate system is located at a predetermined position of the vehicle SV (e.g., the position of the vehicle width center of the front end of the vehicle SV).

[0024] Specifically, the radar sensor 21a includes a radar wave transmitting / receiving section and a processing section. The radar wave transmitting / receiving section transmits, for example, radio waves, each having a millimeter wave band, at least to the surrounding area of ​​the vehicle SV, including a front area in front of the vehicle SV. Hereinafter, the radio waves, each having the millimeter wave band, will be referred to as "millimeter waves." Furthermore, the radar wave transmitting / receiving section receives reflected waves generated by the transmitted millimeter waves being reflected by parts of the existing object (i.e., reflection points). Note that the radar sensor 21a may be a radar sensor using radio waves or radar waves, each having a frequency band other than the millimeter wave band.

[0025] The processing section of the radar sensor 21a determines whether an object is present based on reflection point information, including (i) a phase difference between the transmitted millimeter wave and the received reflected wave, (ii) an attenuation level of the reflected wave, and (iii) the time elapsed from the transmission of the millimeter wave to the reception of the reflected wave. The processing section of the radar sensor 21a groups the reflection points that are likely to belong to an existing object and recognizes the grouped reflection points as an object.

[0026] In addition, the radar sensor processing section 21a calculates radar sensor detection information including (i) the longitudinal distance Dfx to the object, (ii) an orientation p of the object with respect to the vehicle SV, and (iii) the relative speed Vfx between the vehicle SV and the object.

[0027] The camera sensor 21b includes a stereo camera and an image processing section. The stereo camera captures images of views of a left area and a right area in front of the vehicle SV and acquires a pair of left and right images. The image processing section determines whether an object is located in the capture area based on the pair of captured left and right images.

[0028] When the image processing section determines that an object is present, the image processing section calculates the orientation p of the object, the longitudinal distance Dfx of the object, and the relative speed Vfx between the vehicle SV and the object. Furthermore, the image processing section identifies the type of object, such as a walking person or a vehicle (an automobile), through a pattern matching method and determines or acquires the information about the type of object. The information calculated and acquired by the image processing section is referred to as "camera sensor detection information."

[0029] The object detection section 21c is electrically connected to and communicates with the processing section of the radar sensor 21a and the image processing section of the camera sensor 21b. The object detection section 21c receives the detection information from the radar sensor and the detection information from the camera sensor.

[0030] The object detection section 21c determines or acquires the object information about the object based on the radar sensor detection information and the camera sensor detection information. The object detection section 21c sends the determined conclusive object information about the object to the DS-ECU every time a predetermined time elapses.

[0031] The image processing section of the camera sensor 21b detects a left lane marking (or a left white line) and a right lane marking (or a right white line) present on the road using a known technique. For example, the image processing section detects the left and right white lines by (i) detecting edges where the luminance of the image changes dramatically, (ii) detecting outlines defined by the consecutive edges based on the currently detected and previously detected edges, and (iii) selecting the outlines of the white lines from among the detected outlines.

[0032] Then, the image processing section calculates position information on the left and right white lines defining a lane on which the vehicle SV is moving (x-coordinate positions and y-coordinate positions in the xy coordinate system) and sends the position information to the DS-ECU every time the predetermined time elapses.

[0033] In addition, the image processing section calculates detection reliability levels for the detected left and right white lines, each based on characteristic quantities such as edge strengths, luminance, and detection distances obtained from the images of the detected left and right white lines. The detection reliability levels of the detected left and right white lines are parameters that represent the reliability levels of the detection results of the detected left and right white lines. Detection reliability levels of the white lines are expressed as a percentage from 0 percent to 100 percent, depending on the characteristic values. The higher the detection reliability levels of the white lines indicate the higher reliability levels of the detection results.

[0034] The vehicle speed sensor 22 detects a traveling speed or a vehicle speed of the vehicle SV and outputs a signal representing the detected vehicle speed Vs.

[0035] The yaw rate sensor 23 detects a yaw rate of the vehicle SV and outputs a signal representing the detected yaw rate Yr.

[0036] The longitudinal acceleration sensor 24 detects a longitudinal acceleration of the vehicle SV and outputs a signal representing the detected longitudinal acceleration Gx. If the longitudinal acceleration Gx is negative, a magnitude or absolute value of the longitudinal acceleration Gx represents a deceleration.

[0037] The lateral acceleration sensor 25 detects a lateral acceleration of the vehicle SV and outputs a signal representing the detected lateral acceleration Gy.

[0038] The engine ECU 30 is electrically connected to engine actuators 31. The engine actuators 31 include a throttle actuator that changes the opening degree of a throttle valve of an engine 32. The engine ECU 30 can control the torque generated by the engine 32 by controlling the engine actuators 31. The torque generated by the engine 32 is transmitted to driven wheels of the vehicle SV via a transmission (not shown).

[0039] Thus, the engine ECU 30 can control a driving force of the vehicle SV to maintain an accelerated state (the longitudinal acceleration Gx) of the vehicle SV by controlling the engine actuators 31. If the vehicle SV is a hybrid vehicle, the engine ECU 30 can control the driving force(s) applied to the vehicle SV, which are generated by one or both of the engine and at least one electric motor as a vehicle drive source. If the vehicle SV is an electric vehicle, the engine ECU 30 can control the driving force applied to the vehicle SV, which is generated by the electric motor as a vehicle drive source.

[0040] The brake ECU 40 is electrically connected to the brake actuators 41. The brake actuators 41 are provided in hydraulic circuits between (i) a master cylinder (not shown) that pressurizes hydraulic oil by a pressing force applied to a brake pedal, and (ii) friction brake mechanisms 42 provided on the left and right front wheels and the left and right rear wheels of the vehicle SV, respectively. Each of the friction brake mechanisms 42 includes a brake disc 42a fixed to the corresponding wheel of the vehicle SV and a brake caliper 42b fixed to a body of the vehicle SV.

[0041] Each of the brake actuators 41 adjusts the hydraulic pressure applied to a wheel cylinder provided in the brake caliper 42b in response to an instruction from the brake ECU 40 and actuates the wheel cylinder with the hydraulic pressure. As a result, the brake actuators 41 press the brake pads against the brake discs 42a to generate frictional braking forces.

[0042] Thus, the brake ECU 40 can control the braking forces applied to the vehicle SV to regulate the accelerated state (the deceleration or the negative longitudinal acceleration Gx) of the vehicle SV by controlling the brake actuators 41.

[0043] The EPS-ECU 50 is a control device of a known electric power steering system. The EPS-ECU 50 is electrically connected to a motor driver 51. The motor driver 51 is electrically connected to a rotation motor 52. The rotation motor 52 is installed in a steering mechanism including (i) a steering wheel SW, (ii) a steering shaft SF, and (iii) a steering gear (not shown). The rotation motor 52 is an electric motor and generates a steering torque using electrical power supplied from the motor driver 51. The steering torque rotates the left and right steered wheels of the vehicle SV. In other words, the rotation motor 52 can control a steering angle of the vehicle SV or steering angles of the steered wheels.

[0044] The EPS-ECU 50 is electrically connected to a steering angle sensor 53 and a steering torque sensor 54. The steering angle sensor 53 detects a steering angle of the steering wheel SW of the vehicle SV and outputs a signal representing the detected steering angle s. The steering torque sensor 54 detects a steering torque applied to the steering shaft SF of the vehicle SV in response to an operation of the steering wheel SW and outputs a signal representing the detected steering torque TqDr. Hereinafter, the steering torque TqDr is referred to as "driver torque TqDr." The steering angle s and the driver torque TqDr each take positive values ​​when the vehicle SV is steered in a left-turn direction. On the other hand, the steering angle s and the driver torque TqDr each take negative values ​​when the vehicle SV is steered in a right-turn direction.

[0045] The EPS-ECU 50 detects the driver torque TqDr input to the steering wheel SW by a driver of the vehicle SV through the steering torque sensor 54 and controls the turning motor 52 based on the driver torque TqDr, the steering angle s, and the vehicle speed Vs. The EPS-ECU 50 applies the steering torque (a steering assist torque) to the steering mechanism by driving the turning motor 52, thereby assisting a steering operation performed by the driver.

[0046] When the EPS-ECU 50 receives a steering instruction from the DS-ECU while executing emergency steering control, the EPS-ECU 50 drives the turning motor 52 through the motor driver 51 based on a target steering torque predetermined by the steering instruction. At this time, the EPS-ECU 50 generates the steering torque corresponding to the target steering torque. This torque is different from the steering assist torque applied to assist the driver's operation of the steering wheel SW and is a torque applied to the steering mechanism based on the steering instruction from the DS-ECU. In this way, the DS-ECU can automatically change the steering angles of the steered wheels of the vehicle SV through the EPS-ECU 50 to turn the steered wheels without the driver's steering operation.

[0047] The alarm ECU 60 is electrically connected to a buzzer 61. The alarm ECU 60 emits alarm sounds via the buzzer 61 in response to an instruction from the DS-ECU. <Zusammenfassung der Funktionen der Notfalllenksteuerung>

[0048] Fig. Figure 2 shows a situation where the vehicle SV is traveling in lane LA1, a straight lane, and there is an obstacle OV1, which is an existing object or an object with which the vehicle SV is likely to collide. In this case, the DS-ECU executes emergency steering control to prevent the vehicle SV from colliding with the obstacle OV1.

[0049] Emergency steering control is a steering control of the SV vehicle to avoid collision of the SV vehicle with the obstacle OV1, to prevent the SV vehicle from moving out of the lane LA1, or to minimize the SV vehicle from moving out of the lane. The DS-ECU executes emergency steering control as described below.

[0050] The DS-ECU detects the lane LA1 defined 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 every time the predetermined time has elapsed.

[0051] The DS-ECU calculates at least one lane shape parameter based on the position information of the left and right white lines WL and WR each time the predetermined time has elapsed. The lane shape parameter is a parameter representing a shape of the lane LA1 or the road. In this embodiment, the lane shape parameter is a parameter representing a degree of curvature of the lane LA1. Specifically, the lane shape parameter is a curvature radius R calculated based on the detected white lines.

[0052] In addition, the DS-ECU acquires or calculates the overall white line detection reliability level based on the left white line detection reliability level WL and the right white line detection reliability level WR. The overall white line detection reliability level represents the overall reliability level of the detection results for the left and right white lines WL and WR. Hereinafter, the overall white line detection reliability level is referred to as the "white line detection reliability level." For example, the DS-ECU calculates an average of the detection reliability levels of the left and right white lines WL and WR and adopts the calculated average as the white line detection reliability level. For convenience, the white line detection reliability is also referred to as the "lane marking detection reliability."

[0053] The DS-ECU calculates a predicted route of the vehicle SV based on the steering angle s, the yaw rate Yr and the vehicle speed Vs of the vehicle SV.

[0054] The DS-ECU determines whether the present object is a moving object or a stationary object based on the object information about the present object. If the present object is a moving object, the DS-ECU calculates the predicted movement route of the present object based on the object information. The DS-ECU determines the predicted movement route of the present object based on (i) the detection positions of the present object detected in the past each time the predetermined time elapses and (ii) the detection position of the present object at the current time.

[0055] The DS-ECU determines whether the SV vehicle will collide with the existing object based on the predicted movement route of the SV vehicle and the predicted movement route of the existing object when the existing object maintains the current moving state (when the existing object is the non-moving object, the current stopped state) and the SV vehicle maintains the current moving state. If the DS-ECU determines that the SV vehicle will collide with the existing object, the DS-ECU determines, based on a determination result, that the existing object is the obstacle OV1 with which the SV vehicle is likely to collide.

[0056] If the DS-ECU determines that the existing object is the obstacle OV1, the DS-ECU calculates a predicted collision time (TTC) with respect to the obstacle OV1 based on the longitudinal distance Dfx and the relative speed Vfx of the obstacle OV1. Specifically, the DS-ECU calculates the predicted collision time (TTC) by reversing the sign of a value obtained by dividing the longitudinal distance Dfx by the relative speed Vfx (TTC = -Dfx / Vfx).

[0057] In addition, the DS-ECU calculates routes that allow the SV vehicle to avoid collision with the obstacle OV1 based on a known method, and sets the route that allows the SV vehicle to avoid interference and collision with the obstacle OV1 by turning the SV vehicle along the route as the target avoidance route (see, for example, JP 2017-105383 A, JP 2017-43261 A, and JP 2018-106230 A). In this case, the target avoidance route is a route that (i) passes through an avoidance space SP1 set on the left or right side of the obstacle OV1 and (ii) does not move the SV vehicle out of the travel lane LA1, based on the object information about the obstacle OV1 and the positions of the white lines.

[0058] When a first or second condition described below is met, the DS-ECU starts executing the emergency steering control.

[0059] The first condition is met if all the conditions described below are met. (i) A condition that the predicted collision time TTC is equal to or shorter than a first threshold time TTC1. (ii) A condition that the steering wheel SW is operated in a direction to turn the vehicle SV to avoid the collision of the vehicle SV with the obstacle OV1 before a predetermined time elapses, since the predicted collision time TTC is determined to be equal to or shorter than the first threshold time TTC1. The DS-ECU determines whether this condition is met based on the driver torque TqDr. Hereinafter, the time at which the predicted collision time TTC is determined to be equal to or shorter than the first threshold time TTC1 is referred to as the "first determination time." (iii) A condition that there are no objects other than the obstacle OV1 on the target avoidance route. (iv) A condition that the white line detection reliability level is equal to or higher than a first threshold reliability level. This condition is also referred to as the "white line detection reliability level condition." (v) A condition that the vehicle SV is moving in the straight lane or the radius of curvature R of the lane LA1 is equal to or greater than a threshold radius Rth.

[0060] The second condition is met if all the conditions described below are met. (i) A condition that the steering wheel SW is not operated in the direction in which the vehicle SV avoids collision with the obstacle OV1 before the predetermined time has elapsed since the first determination time. (ii) A condition that the predicted collision time TTC is equal to or shorter than a second threshold time TTC2 set to a time shorter than the first threshold time TTC1. (iii) A condition that there are no objects other than the obstacle OV1 on the target avoidance route. (iv) A condition that the reliability level of white line detection is equal to or higher than the first threshold reliability level. (v) A condition that the vehicle SV is traveling on the straight lane or the radius of curvature R of the lane LA1 is equal to or greater than the threshold radius Rth.

[0061] When an execution start condition for starting the execution of the emergency steering control, that is, the first or second condition, is satisfied, the DS-ECU calculates a target yaw rate at which the vehicle SV is moved along the target avoidance route.

[0062] The DS-ECU calculates a target steering angle of the steered wheels of the vehicle SV to achieve the target yaw rate based on the calculated target yaw rate and the vehicle speed Vs of the vehicle SV. The DS-ECU then sends a collision avoidance steering command representing the calculated target turning angle to the EPS-ECU 50.

[0063] The EPS-ECU 50 calculates a target steering torque to adjust the actual steering angle to the target steering angle, that is, to make the actual steering angle follow the target steering angle. The EPS-ECU 50 then drives the rotation motor 52 to output the steering torque corresponding to the calculated target steering torque to rotate the steered wheels of the vehicle SV.

[0064] At this time, the DS-ECU executes the emergency steering control to steer the vehicle SV to avoid the collision of the vehicle SV with the obstacle OV1 via the EPS-ECU 50 without moving the vehicle SV out of the lane LA1, as shown by an arrow a1.

[0065] For convenience, the emergency steering control executed in response to the first condition being satisfied is also called "emergency steering assist control," and the emergency steering control executed in response to the second condition being satisfied is also called "automatic emergency steering control."

[0066] The DS-ECU may be configured to issue an instruction to the alerting ECU 60 to execute alerting control at the first determination time (i.e., at the time when the predicted collision time TTC is determined to be equal to or shorter than the first threshold time TTC1). The alerting control is, for example, a control of the output of alarm sounds from the buzzer 61 to warn the driver. In this case, when the driver knows the obstacle OV1 and operates the steering wheel SW in the direction in which the vehicle SV avoids collision with the obstacle OV1 before the predetermined time has elapsed since the output of the warning sounds, execution of the emergency steering control is started. Thereby, the collision avoidance assist device 10 operates to assist the driver's operation on the steering wheel SW to avoid the collision of the vehicle SV with the obstacle OV1.When the second condition is met, the execution of the emergency automatic steering control is started if the steering wheel SW has not been operated before the predetermined time has elapsed since the start of the warning sounds. In this case, the collision avoidance assist device 10 operates to steer the vehicle SV to automatically avoid the collision of the vehicle SV with the obstacle OV1, even if the steering wheel SW is not operated by the driver. <Zusammenfassung des Stoppens oder Aufhebens bzw. Beendens der Notfalllenksteuerung >

[0067] If the overall reliability level of the left and right white line detection results decreases while the emergency steering control is being executed, the DS-ECU may not adequately execute the emergency steering control due to incorrect white line detection. To prevent the execution of inadequate emergency steering control, the DS-ECU instructs the EPS-ECU 50 to stop the execution of the emergency steering control when the reliability level of the white line detection becomes lower than a predetermined threshold (ie, a second reliability threshold described later). <Zusammenfassung der Operationen der Kollisionsvermeidungsassistenzvorrichtung>

[0068] Fig. 3 shows a situation in which (i) the vehicle SV is moving on the lane LA1, which is a straight lane, and (ii) the execution of the emergency steering control is started at a time t1.

[0069] In the Fig. In the case shown in Figure 3, when the execution of the emergency steering control is started, a lateral movement occurs in the vehicle SV, and a part of the right white line WR is obscured by the obstacle OV1 from the camera sensor 21b. The right white line WR is located on the right side of the obstacle OV1, which the vehicle SV does not pass to avoid collision with the obstacle OV1 (hereinafter, the side of the obstacle OV1 that the vehicle SV does not pass to avoid collision with the obstacle OV1 is also referred to as the "non-avoidance side"). As a result, the detection reliability level of the right white line WR is low. As shown in Fig. As shown in Figure 4, the white line detection reliability level, calculated based on the left and right white lines WL and WR, is low while the emergency steering control is being executed. The causes for the reduction in white line detection reliability, as described above, are not significant, such as the deterioration of the white lines and the decrease in the intensity of the white lines. Therefore, it is not necessary to stop the execution of the emergency steering control.However, as shown in a comparative example, when a process for determining the reliability level of white line detection based on the first threshold reliability level is performed while the emergency steering control is being executed, the reliability level of white line detection becomes lower than the first threshold reliability level, and the execution of the emergency steering control is unnecessarily stopped.

[0070] In this regard, the DS-ECU of the collision avoidance assist device 10 or the execution device sets a threshold value used for determining the reliability level for white line detection to the first threshold reliability level before the DS-ECU starts executing the emergency steering control (that is, when the DS-ECU is not executing the emergency steering control). This case is the same as the comparative example. When the DS-ECU is executing the emergency steering control, the DS-ECU sets the threshold value used for determining the reliability level of white line detection to the second threshold reliability level. The second threshold reliability level is set to a value that is lower in percentage terms than the first detection reliability level.

[0071] As in Fig. As shown in Figure 4, the probability that the white line detection reliability level drops below the second threshold is lower even when the white line detection reliability level drops due to the above-described causes resulting from the execution of the emergency steering control. Thus, the DS-ECU can avoid unnecessary execution of a process for stopping the execution of the emergency steering control even when the above-described causes resulting from the execution of the emergency steering control occur. <Spezifische Operationen>

[0072] The DS-ECU CPU is configured or programmed to execute routines described in the flowcharts in Fig. 5 and Fig. 6, each time the predetermined time has elapsed.

[0073] Thus, at a predetermined time, the CPU begins executing a process from a step 500 in Fig. 5 and the process proceeds to a step 505 to determine whether one of the following conditions is met: (i) the first condition, which is different from the white line detection reliability level condition, that the white line detection reliability level is equal to or higher than the first threshold reliability level, and (ii) the second condition, which is different from the white line detection reliability level condition.

[0074] If the first and second conditions except for the condition for the reliability level of white line detection are not satisfied, the CPU determines "No" in step 505 and advances the process to step 595 to terminate the execution of this routine once.

[0075] On the other hand, when any of the first and second conditions other than the condition of the reliability level of white line detection is satisfied, the CPU determines "Yes" in step 505, executes a process of step 510 described below, and proceeds the process to step 515.

[0076] Step 510: The CPU calculates the confidence level of white line detection based on the left and right white lines.

[0077] When the CPU proceeds to a step 515, the CPU determines whether the reliability level of the white line detection is equal to or higher than the first threshold reliability level.

[0078] If the reliability level of white line detection is lower than the first threshold reliability level, the CPU determines "No" in step 515 and proceeds to step 595 to terminate the execution of this routine once.

[0079] On the other hand, if the reliability level of the white line detection is equal to or higher than the first threshold reliability level, the CPU determines "Yes" in step 515, executes a process of step 520 described below, and proceeds to step 595 to terminate the execution of this routine once.

[0080] Step 520: The CPU starts executing the emergency steering control.

[0081] In addition, the CPU starts the execution of a process from a step 600 in Fig. 6 and proceeds to step 605 to determine whether the emergency steering control is being executed. The CPU determines that the emergency steering control is being executed until the execution of the emergency steering control is terminated from the time since the execution of the emergency steering control was started, or until the execution of the emergency steering control is stopped from the time since the execution of the emergency steering control was started.

[0082] If the emergency steering control is not executed, the CPU determines "No" in step 605 and advances the process to step 695 to terminate the execution of this routine once.

[0083] On the other hand, when the emergency steering control is executed, the CPU determines "Yes" in step 605, executes a process of a step 610 described below, and proceeds the process to a step 615.

[0084] Step 610: The CPU calculates the confidence level of white line detection based on the left and right white lines.

[0085] When the CPU proceeds to step 615, the CPU determines whether the white line detection reliability level is equal to or higher than the second threshold reliability level. As described above, the second threshold reliability level is set to a value lower than the first threshold reliability level.

[0086] If the reliability level of white line detection is lower than the second threshold reliability level, the CPU determines "No" in step 615, executes a process of step 620 described below, and proceeds to step 695 to terminate the execution of this routine once.

[0087] Step 620: The CPU stops executing the emergency steering control.

[0088] On the other hand, if the reliability level of the white line detection is equal to or higher than the second threshold reliability level, the CPU determines "Yes" in step 615 and proceeds to step 625 to determine whether a termination condition for terminating the execution of the emergency steering control is satisfied. The termination condition for terminating the execution of the emergency steering control is set, for example, to an appropriate predetermined condition to determine that the avoidance of the collision of the vehicle SV with the obstacle by the emergency steering control is completed.

[0089] If the termination condition for terminating the execution of the emergency steering control is not satisfied, the CPU determines "No" in step 625 and advances the process to step 695 to terminate the execution of this routine once.

[0090] On the other hand, when the termination condition for terminating the execution of the emergency steering control is satisfied, the CPU determines "Yes" in step 625, executes a process of step 630 described below, and advances the process to step 695 to terminate the execution of this routine once.

[0091] Step 630: The CPU stops executing the emergency steering control. <effekte>

[0092] As described above, the collision avoidance assist device 10 can eliminate the unnecessary execution of the process of stopping the execution of the emergency steering control. <Modifizierte Beispiele>

[0093] The embodiment of the invention has been specifically described, but the invention is not limited to the embodiment. Various modified examples may be used based on technical concepts of the invention without departing from the scope of the invention.

[0094] In the above-described embodiment, the DS-ECU may be configured to execute at least one of the processes executed by the object detection section 21c instead of the object detection section 21c.

[0095] Furthermore, in the above-described embodiment, a curvature (= 1 / R) may be used instead of the curvature radius R. In this case, the DS-ECU determines that the lane is a curved lane when the curvature is greater than a threshold curvature, and the lane is a straight lane when the curvature is equal to or smaller than the threshold curvature.

[0096] Furthermore, in the above-described embodiment, the DS-ECU may be configured to calculate the reliability level of white line detection while executing the emergency steering control based only on the white line on an avoidance side, which is either the left or right side of the obstacle OV1 that the vehicle SV passes to avoid the collision with the obstacle OV1. That is, in step 610 in Fig. 6, the CPU can calculate the reliability level of white line detection based only on the white line on the avoidance side.

[0097] According to this modified example, the white line detection reliability level is calculated based on only the white line detection reliability level that is not easily lowered due to behaviors of the vehicle SV derived from the execution of the emergency steering control. For example, the detection reliability level of the white line detection on the avoidance side is used as the white line detection reliability level. Therefore, the white line detection reliability does not easily decrease while the emergency steering is being executed. Thus, the white line detection reliability level does not easily become lower than the second threshold reliability level while the emergency steering control is being executed. This can reliably prevent unnecessary execution of the emergency steering control stop process.

[0098] Furthermore, in the embodiment described above, the DS-ECU may be configured to stop the vehicle SV in front of the obstacle OV1 by executing automatic braking control when the vehicle SV can be stopped in front of the obstacle OV1 by braking the vehicle SV before the DS-ECU starts executing the emergency steering control.

[0099] Furthermore, in the above-described embodiment, the DS-ECU may be configured to execute only one of the emergency automatic steering control and the emergency steering assist control as the emergency steering control.

[0100] A collision avoidance assist device (10) calculates a reliability level of lane marking detection and executes emergency steering control. The emergency steering control includes processes for determining a target steering torque to avoid a collision of a vehicle with an obstacle when it is determined that the vehicle has a high probability of colliding with the obstacle, a lane defined by the left and right lane markings is a straight lane, and the calculated reliability level of lane marking detection is equal to or higher than a first threshold reliability level, and for applying a steering torque corresponding to the target steering torque to a steering mechanism.The collision avoidance assist device stops executing the emergency steering control when the reliability level of the lane marking detection becomes lower than a second threshold reliability level set to a value lower than the first threshold reliability level.< / effekte> < / konfiguration>

Claims

[1] Collision avoidance assistance device (10), comprising: a lane marking detecting device (21b) that detects a left lane marking and a right lane marking provided on a road on which a vehicle is traveling; an obstacle detection device (21) which detects an obstacle in an area ahead of the vehicle; an electric motor (52) that applies a steering torque to a steering mechanism comprising a steering wheel of the vehicle to change a steering angle of at least one steered wheel of the vehicle; and an electronic control unit (20) configured to: to calculate a lane marking detection reliability level, which represents a reliability level of an overall detection result of the left and right lane markings; and to carry out emergency steering control, including processes for: Determining a target steering torque that changes the steering angle to avoid a collision of the vehicle with the obstacle without moving the vehicle out of the lane when (i) the electronic control unit (20) determines that the vehicle has a high probability of colliding with the obstacle, (ii) a lane defined by the left and right lane markings is a straight lane, and (iii) the calculated lane marking detection reliability level is greater than or equal to a first threshold reliability level; and Driving the electric motor (52) to apply the steering torque corresponding to the determined target steering torque to the steering mechanism, wherein the electronic control unit (20) is configured to stop the execution of the emergency steering control when the reliability level of the lane marking detection becomes lower than a second threshold reliability level set to a value lower than the first threshold reliability level. [2] Collision avoidance assist device (10) according to claim 1, wherein the electronic control unit (20) is configured to: to calculate the reliability level of lane marking detection based on the left and right lane markings before the electronic control unit (20) starts executing the emergency steering control; and calculating the reliability level of lane marking detection based on only one of the left and right lane markings on the side of the obstacle that the vehicle is passing while the electronic control unit (20) is executing the emergency steering control.

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