Collision avoidance assistance device

Abstract

Collision avoidance assistance device (10), with: a road marking detection device (21b) that detects a left lane marking and a right lane marking provided on a road on which a vehicle is moving; an obstacle detection device (21) that detects obstacles in an area in front of the vehicle; an electric motor (52) which applies a steering torque to a steering mechanism comprising a steering wheel of the vehicle in order to change a steering angle of at least one steered wheel of the vehicle; and an electronic control unit (20) configured to perform emergency steering control, which includes the following processes: Determining a target steering torque, which is used to change the steering angle to avoid a collision of the vehicle with the obstacle, in order to keep the vehicle from leaving a lane defined by the left and right lane markings, when (i) the electronic control unit (20) determines that the vehicle has a high probability of colliding with the obstacle, and (ii) the lane is a straight lane; and Driving the electric motor (52) to apply the steering torque corresponding to the specified 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 electronic control unit determines that the lane is a curved lane based on only one of the left and right lane markings on an evasive side of the obstacle, which is the left or right side of the obstacle over which the vehicle is passing while the electronic control unit is executing the emergency steering control.

Description

BACKGROUND area

[0001] The invention relates to a collision avoidance assistance device that steers a vehicle in such a way as 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 assistance device disclosed in JP 2017-43262 A is configured to detect an obstacle in front of a vehicle and to steer the vehicle's steered wheels to avoid a collision of the vehicle with the obstacle when the vehicle is likely to collide with the obstacle.

[0003] The inventors of this application are considering a collision avoidance assistance device that steers the vehicle to avoid the collision of the vehicle with an obstacle, in order to prevent the vehicle from leaving a lane defined by a left white line and a right white line provided on a road on which the vehicle is moving.

[0004] The lane defined by the left and right white lines on the road, in which the vehicle is traveling, will be referred to as the "lane" in the following text. The vehicle steering control system used to prevent a collision with an obstacle and to keep the vehicle within the lane will be referred to as the "emergency steering control" in the following text.

[0005] The collision avoidance system detects the lane markings on the road and determines whether the detected lane is straight or curved. To prevent the vehicle from leaving its lane due to the execution of emergency steering control, the collision avoidance system initiates emergency steering control when the lane is straight. Furthermore, the collision avoidance system stops or aborts the execution of emergency steering control if the lane changes from straight to curved during the execution of emergency steering control.

[0006] While the emergency steering control is being executed, the collision avoidance system may fail to detect part of the white line due to the vehicle's lateral movement and the obstruction of part of the white line by the obstacle. It has been found that the reliability of the detection results performed by the collision avoidance system based on the white line on the left or right side of the obstacle, as opposed to the side of the obstacle the vehicle is passing, is low.

[0007] Therefore, the accuracy with which the collision avoidance system determines whether the lane is straight or curved may be low. Consequently, the collision avoidance system may not properly execute the emergency steering control stop process.

[0008] In other words, if the lane the vehicle is traveling in changes from the straight lane to the curved lane while the emergency steering control is being executed, the collision avoidance system may not stop executing the emergency steering control because it will incorrectly detect that the lane has changed to the straight lane, when the emergency steering control should have stopped. Conversely, if the lane the vehicle is traveling in does not change from the straight lane to the curved lane while the emergency steering control is being executed (i.e., the vehicle remains in the straight lane), the collision avoidance system may stop executing the emergency steering control because it will incorrectly detect that the lane has changed to the curved lane, when the emergency steering control should not have stopped. SUMMARY

[0009] The invention was made to solve the problems described above. One objective of the invention is to provide a collision avoidance assistance device that can eliminate the inappropriate execution of a process for stopping the execution of the emergency steering control.

[0010] A collision avoidance assistance 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 moving, (ii) an obstacle detection device (21) that detects obstacles in an area in front of the vehicle (SV), (iii) an electric motor (52) that applies a steering torque to a steering mechanism that includes a steering wheel 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) configured to perform an emergency steering control (see a process of step 610 in Fig. 6).

[0011] The emergency steering control includes processes for determining a target steering torque, which is used to change the steering angle to avoid a collision of the vehicle (SV) with the obstacle, in order to keep the vehicle (SV) from leaving a lane defined by the left and right lane markings (WL and WR) when (i) the electronic control unit (20) determines that the vehicle (SV) has a high probability of colliding with the obstacle, and (ii) the lane is a straight lane (see a case of determining 'yes' in a step 605 in Fig. 6), and driving the electric motor (52) to apply the steering torque corresponding to the specified target steering torque to the steering mechanism.

[0012] The electronic control unit (20) is configured to stop the execution of the emergency steering control (see a process of step 725 in Fig. 7) if the electronic control unit determines that the lane is a curved lane, based on only one of the left and right lane markings on an obstacle avoidance side, which is the left or right side of the obstacle that the vehicle is driving around (see a process of step 810 in Fig. 8 and a case of determining “Yes” in step 830 in Fig. 8), while the electronic control unit (20) performs the emergency steering control (see a case of determining 'Yes' in step 805 in Fig. 8).

[0013] This prevents a decrease in the accuracy of determining whether the vehicle's trajectory is straight or curved while the emergency steering control is being executed. This eliminates the inappropriate execution of the emergency steering control process.

[0014] According to one aspect of the invention, the electronic control unit (20) can be configured to, before the electronic control unit (20) begins to execute the emergency steering control (see a case of determining “No” in step 805 in Fig. 8) to calculate a reliability level or degree for lane marking detection that represents the overall detection results for the left and right lane markings (WL and WR), based on the left and right lane markings (WL and WR) (see a process of step 820 in Fig. 8), and execute the emergency steering control (see the process in step 610 in Fig. 6) if (i) the electronic control unit (20) determines that the vehicle (SV) has a high probability of colliding with the obstacle, (ii) the lane is the straight lane, and (iii) the calculated reliability level of the lane marking detection is equal to or higher than a threshold reliability level (see the case of determining ‘Yes’ in step 605 in Fig. 6) In this case, the electronic control unit (20) can be configured to perform the emergency steering control while the electronic control unit (20) is executing (see the case of determining “Yes” in step 805 in Fig. 8) to calculate the reliability level of the lane marking detection based on only one of the left and right lane markings (WL and WR) on the side of the obstacle to avoid (see the process in step 810), and to execute the emergency steering control (see the process in step 725 in Fig. 7) to stop if the calculated reliability level of the lane marking detection becomes lower than the threshold reliability level (see a case of determining “Yes” in step 815 and a process of step 825 in Fig. 8).

[0015] According to this aspect of the invention, it is possible to prevent the reliability level of lane marking detection from decreasing due to the reduced reliability level of lane marking detection on the non-evasive side compared to the evasive side of the obstacle during the execution of the emergency steering control. In this way, the unnecessary execution of the process of stopping the emergency steering control can be eliminated.

[0016] According to another aspect of the invention, the electronic control unit (20) can be configured to, before the electronic control unit (20) begins to execute the emergency steering control (see the case of determining “No” in step 805 in Fig. 8) to calculate at least one lane shape parameter representing a degree of curvature of the lane, based on the left and right lane markings (see the process in step 820 in Fig. 8), and to determine, based on the calculated lane shape parameter, whether the lane is the straight lane or the curved lane (see the process in step 830 in Fig. 8) In this case, the electronic control unit (20) can be configured to perform the emergency steering control while the electronic control unit (20) is executing (see the case of determining “Yes” in step 805 in Fig. 8) to calculate the lane shape parameter based on only one of the left and right lane markings (WL and WR) on the side of the obstacle to avoid (see the process in step 810), and to determine which of the lanes is the straight lane or the curved lane based on the calculated lane shape parameter (see the process in step 830 in Fig. 8).

[0017] According to this aspect of the invention, the lane shape parameter can be accurately calculated based on the left and right lane markings before the emergency steering control is executed. Furthermore, the lane shape parameter can be accurately calculated based on only one of the left and right lane markings while the emergency steering control is being executed. Thus, it can be accurately determined whether the lane is curved or straight both before and during the emergency steering control.

[0018] For ease of understanding, elements of the present invention corresponding to elements of a subsequently described embodiment have been designated with reference numerals used in the description of that embodiment and enclosed in brackets. However, the elements of the present invention are not limited to those of the embodiment defined by the reference numerals. The further objectives, features, and associated advantages of the present invention can be readily understood from the description of the embodiment of the present invention together with the drawings. BRIEF DESCRIPTION OF THE DRAWINGS Fig. Figure 1 is a general configuration view showing a collision avoidance assistance device according to an embodiment of the invention. Fig. Figure 2 is a general top view that serves to describe a summary of the functions of the collision avoidance assistance device. Fig. Figure 3 is a general top view, which serves to describe the summary of the functions of the collision avoidance assistance device. Fig. Figure 4 is a general top view that serves to describe the summary of the functions of the collision avoidance assistance device. Fig. Figure 5 is a general top view that serves to describe the summary of the functions of the collision avoidance assistance device. Fig. Figure 6 is a view showing a flowchart of a routine executed by a CPU of a driver assistance ECU. Fig. Figure 7 is a view showing a flowchart of a routine executed by the CPU of the driver assistance ECU. Fig. Figure 8 is a view showing a flowchart of a routine executed by the CPU of the driver assistance ECU. Fig. Figure 9 is a view showing a flowchart of a routine executed by the CPU of the driver assistance ECU. DESCRIPTION OF THE EXAMPLES OF EXECUTION <konfiguration>

[0019] As in Fig. Figure 1 shows a collision avoidance assistance device 10 according to an embodiment of the invention installed in a vehicle SV. The collision avoidance assistance device 10 comprises a driver assistance ECU 20, a machine ECU 30, a brake ECU 40, an electric power steering ECU 50, and an alarm ECU 60. Hereinafter, the driver assistance ECU 20 is referred to as the “DS-ECU” and the electric power steering ECU 50 as the “EPS-ECU 50”.

[0020] ECUs are electronic control units, each containing a microcomputer as its main component. They are also referred to as control units. These control units are electrically interconnected to exchange data or communicate with each other via a CAN 70 (Controller Area Network). The microcomputer comprises a CPU, ROM, RAM, and an interface (I / F). The CPU performs various functions by executing instructions, programs, or routines stored in the ROM. All or some of the control units can be integrated into a single control unit.

[0021] An environmental 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 from the sensors. The sensors may be electrically connected to an ECU other than the DS-ECU.

[0022] The environmental sensors 21 comprise 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 the "obstacle detection device" and the camera sensor 21b as the "lane marking detection device".

[0023] The environmental sensors 21 detect (i) an environment around the vehicle SV, which includes at least one road in front of the vehicle SV, and (ii) objects present in the environment around the vehicle SV, and acquire information about the detected objects. These objects are either moving objects, such as pedestrians and vehicles, or stationary objects, such as power poles, trees, and guardrails. Hereinafter, the present object may be referred to as an "object".

[0024] The environmental sensors 21 calculate information about the detected objects, i.e. object information including the information listed below, and send the information to the DS-ECU. i) A longitudinal distance Dfx to the object, which corresponds 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 or transverse position Dfy of the object, which corresponds 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, which corresponds 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.

[0025] It should be noted that the longitudinal distance Dfx and the transverse position Dfy are also referred to as "detected positions".

[0026] The environmental sensors 21 acquire the values ​​described above in a predetermined xy-coordinate system. An x-axis of the predetermined xy-coordinate system is a coordinate axis that extends the vehicle width center position of the front end of vehicle SV in the longitudinal direction of 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 vehicle SV (e.g., the vehicle width center position of the front end of vehicle SV).

[0027] In particular, the radar sensor 21a comprises a radar wave transmit / receive section and a processing section. The radar wave transmit / receive section, for example, transmits radio waves, each exhibiting a millimeter wave band, at least into the vicinity of the vehicle SV, including a front area in front of the vehicle SV. Hereinafter, the radio waves, each exhibiting the millimeter wave band, are referred to as "millimeter waves". In addition, the radar wave transmit / receive section receives reflected waves generated by the reflection of the transmitted millimeter waves from parts of the object present (i.e., reflection points). It should be noted that the radar sensor 21a can be a radar sensor that uses radio waves or radar waves, each exhibiting a frequency band other than the millimeter wave band.

[0028] The processing section of 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 radar sensor 21a groups the reflection points that are likely to belong to a present object and recognizes the grouped reflection points as a single object.

[0029] Additionally, the processing section of the radar sensor 21a calculates radar sensor detection information including (i) the longitudinal distance Dfx to the object, (ii) an orientation p of the object in relation to the vehicle SV and (iii) the relative velocity Vfx between the vehicle SV and the object.

[0030] The camera sensor 21b comprises a stereo camera and an image processing section. The stereo camera captures images of left and right views in front of the vehicle SV and records a pair of left and right images. The image processing section determines whether an object is within the recording area based on the recorded left and right image pair.

[0031] When the image processing section detects the presence of an object, it calculates the object's orientation (p), its longitudinal distance (Dfx), and its relative velocity (Vfx). Furthermore, the image processing section identifies the object's type, such as a person walking or a vehicle (e.g., an automobile), using a pattern matching method and determines or captures information about the object's nature. The information calculated and determined by the image processing section is referred to as "camera sensor detection information."

[0032] 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.

[0033] The object recognition section 21c determines or acquires object information about the object based on radar sensor detection information and camera sensor detection information. The object recognition section 21c sends the determined conclusive object information about the object to the DS-ECU every time a predetermined time has elapsed.

[0034] The image processing section of 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 significantly, (ii) detecting outlines defined by successive edges based on the currently detected and previously detected edges, and (iii) selecting the outlines of the white lines from among the detected outlines.

[0035] The image processing section then calculates position information on the left and right white lines that define 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.

[0036] Additionally, the image processing section calculates the detection reliability levels of the detected left and right white lines, based on characteristic parameters such as edge thickness, luminance, and detection distances derived from the images of the detected left and right white lines. These detection reliability levels represent the reliability of the detection results. For example, the white line detection reliability levels are expressed as a percentage from 0% to 100%, depending on the characteristic parameters. Higher detection reliability levels indicate higher reliability levels of the detection results.

[0037] The vehicle speed sensor 22 detects a driving speed or vehicle speed of the vehicle SV and outputs a signal that represents the detected vehicle speed Vs.

[0038] The yaw rate sensor 23 detects a yaw rate of the vehicle SV and outputs a signal representing the detected yaw rate Yr.

[0039] The longitudinal acceleration sensor 24 detects the 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.

[0040] The lateral acceleration sensor 25 detects a lateral acceleration of the vehicle SV and outputs a signal that represents the detected lateral acceleration Gy.

[0041] The machine ECU 30 is electrically connected to machine actuators 31. The machine actuators 31 include a throttle actuator that changes the opening degree of a throttle valve of a power unit 32. The machine ECU 30 can control a torque generated by the power unit 32 by controlling the machine actuators 31. The torque generated by the power unit 32 is transmitted to driven wheels of the vehicle SV via a transmission (not shown).

[0042] Thus, the machine ECU 30 can control a driving force of the vehicle SV to control an acceleration state (the longitudinal acceleration Gx) of the vehicle SV by controlling the machine actuators 31. If the vehicle SV is a hybrid vehicle, the machine ECU 30 can control the driving force(s) exerted on the vehicle SV, which are generated by one or both of the power machine and at least one electric motor as the vehicle drive source. If the vehicle SV is an electric vehicle, the machine ECU 30 can control the driving force exerted on the vehicle SV, which is generated by the electric motor as the vehicle drive source.

[0043] The brake ECU 40 is electrically connected to the brake actuators 41. The brake actuators 41 are arranged in hydraulic circuits between (i) a master cylinder (not shown) that pressurizes hydraulic oil by means of a pressure force applied to a brake pedal, and (ii) friction brake mechanisms 42 located on the left and right front wheels and the left and right rear wheels of the vehicle SV, respectively. Each friction brake mechanism 42 comprises a brake disc 42a, which is attached to the corresponding wheel of the vehicle SV, and a brake caliper 42b, which is attached to a body of the vehicle SV.

[0044] Each of the brake actuators 41 adjusts the hydraulic pressure applied to a wheel cylinder provided in the brake caliper 42b, depending on an instruction from the brake ECU 40, and actuates the wheel cylinder by means of this hydraulic pressure. This causes the brake actuators 41 to press the brake pads against the brake discs 42a to generate frictional braking forces. Thus, the brake ECU 40 can control the braking forces exerted on the vehicle SV in order to control the acceleration state (the deceleration or the negative longitudinal acceleration Gx) of the vehicle SV by actuating the brake actuators 41.

[0045] The EPS-ECU 50 is a control unit 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 rotary motor 52. The rotary motor 52 is installed in a steering mechanism comprising (i) a steering wheel SW, (ii) a steering shaft SF, and (iii) a steering gear (not shown). The rotary motor 52 is an electric motor and generates a steering torque by means of electrical energy supplied by the motor driver 51. The steering torque rotates the left and right steered wheels of the vehicle SV. In other words, the rotary motor 52 can control the steering angle of the vehicle SV or the steering angle of the steered wheels.

[0046] 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 the steering angle of the vehicle SV's steering wheel SW and outputs a signal representing the detected steering angle s. The steering torque sensor 54 detects the steering torque applied to the vehicle SV's steering shaft SF in response to steering wheel SW input 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 assume positive values ​​when the vehicle SV is steered in a left turn. Conversely, the steering angle s and the driver torque TqDr assume negative values ​​when the vehicle SV is steered in a right turn.

[0047] The EPS-ECU 50 detects the driver torque TqDr, which is input into the steering wheel SW by the driver of the vehicle SV via the steering torque sensor 54, and controls the rotary 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 (also referred to as "steering assistance torque") to the steering mechanism by driving the rotary motor 52 and thereby assisting a steering operation performed by the driver.

[0048] When the EPS-ECU 50 receives a steering instruction from the DS-ECU while an emergency steering control is in operation, the EPS-ECU 50 drives the rotary motor 52 through the motor driver 51, based on a target steering torque specified by the steering instruction. The EPS-ECU 50 generates the steering torque corresponding to this target torque. This torque differs from the power steering torque applied to assist the driver's steering wheel operation 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, via the EPS-ECU 50, can automatically change the steering angles of the vehicle's steered wheels SV to rotate the steered wheels without any steering input from the driver.

[0049] The alarm ECU 60 is electrically connected to a buzzer 61. In response to a command from the DS ECU, the alarm ECU 60 emits alarm tones via the buzzer 61. <Zusammenfassung der Operationen der Notfalllenksteuerung>

[0050] Fig. Figure 2 shows a situation in which vehicle SV is moving along lane LA1, a straight lane, and an obstacle OV1 is present, which is either an existing object or an object with which vehicle SV is likely to collide. In this case, the DS-ECU executes emergency steering control to avoid a collision between vehicle SV and obstacle OV1.

[0051] The emergency steering control is a control mechanism for the steering of vehicle SV to prevent a collision with obstacle OV1, to keep vehicle SV from leaving lane LA1, or to minimize the distance vehicle SV leaves its lane. The DS-ECU executes the emergency steering control as described below.

[0052] The DS-ECU recognizes the lane LA1, which is defined by the left white line WL and the right white line WR, based on the position information on the left white line WL and the right white line WR each time the predetermined time elapses.

[0053] 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 elapses. The lane shape parameter is a parameter that represents the shape of lane LA1 or the road. In this embodiment, the lane shape parameter is a parameter that represents the degree of curvature of lane LA1. Specifically, the lane shape parameter is a radius of curvature R, which is calculated based on the detected white lines.

[0054] Furthermore, the DS-ECU determines 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). 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 left and right white line detection reliability values ​​(WL and WR) and uses this average as the white line detection reliability value. For simplicity, the white line detection reliability level is also referred to as the "lane marking detection reliability."

[0055] The DS-ECU calculates a likely route for vehicle SV based on the steering angle s, yaw rate Yr and vehicle speed Vs of vehicle SV.

[0056] The DS-ECU determines whether the object in question is the moving or stationary object, based on the object information it possesses. If the object in question is the moving object, the DS-ECU calculates its predicted movement path based on this information. The DS-ECU determines the predicted movement path based on (i) the object's historical positions, captured at each predetermined time interval, and (ii) the object's current position.

[0057] The DS-ECU determines whether the vehicle SV will collide with the object in question, based on the predicted movement path of the vehicle SV and the predicted movement path of the object in question, assuming the object in question maintains its current state of motion (or, if the object in question is stationary, its current stopped state), and the vehicle SV maintains its current state of motion. If the DS-ECU determines that the vehicle SV will collide with the object in question, it uses a determination result to identify the object in question as the obstacle OV1 with which the vehicle SV is likely to collide.

[0058] When the DS-ECU determines that the object in question is obstacle OV1, it calculates a predicted collision time TTC with respect to obstacle OV1, based on the longitudinal distance Dfx and the relative velocity Vfx of 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 velocity Vfx (TTC = -Dfx / Vfx).

[0059] Furthermore, the DS-ECU calculates routes that allow vehicle SV to avoid collision with obstacle OV1, based on a known method, and defines as the target avoidance route the route that allows vehicle SV to avoid disturbance and collision with obstacle OV1 by driving around the route (see, for example, JP 2017-105383 A, JP 2017-43261 A, and JP 2018-106230). In this case, the target avoidance route is a route that (i) passes through an avoidance space SP1 defined on the left or right side of obstacle OV1, and (ii) does not move vehicle SV out of lane LA1, based on the object information about obstacle OV1 and the positions of the white lines.

[0060] If either the first or second condition described below is met, the DS-ECU will begin executing the emergency steering control.

[0061] 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 turned in a direction to steer the vehicle SV in order to avoid the collision of the vehicle SV with the obstacle OV1 before a predetermined time elapses, as 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 intended diversion route. (iv) A condition that the reliability level of white line detection is equal to or higher than a threshold reliability level. (v) A condition that the vehicle SV moves on the straight lane or that the radius of curvature R of the lane LA1 is equal to or greater than a threshold radius Rth.

[0062] 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 the 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, which is 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 intended diversion route. (iv) A condition that the reliability level of white line detection is equal to or higher than the threshold reliability level. (v) A condition that the vehicle SV travels on the straight lane, or that the radius of curvature R of the lane LA1 is equal to or greater than the threshold radius Rth.

[0063] If an execution start condition for the emergency steering control, i.e. the first or second condition, is met, the DS-ECU calculates a target yaw rate at which the vehicle SV is moved along the target evasive route.

[0064] The DS-ECU calculates a target steering angle for the steered wheels of vehicle SV to achieve the target yaw rate, based on the calculated target yaw rate and the vehicle speed Vs of vehicle SV. The DS-ECU then sends a collision avoidance steering instruction, representing the calculated target steering angle, to the EPS-ECU 50.

[0065] The EPS-ECU 50 calculates a target steering torque to control the actual steering angle to the target steering angle, i.e., to make the actual steering angle follow the target steering angle. The EPS-ECU 50 then drives the rotary motor 52 to output the steering torque corresponding to the calculated target steering torque in order to steer the steered wheels of the vehicle SV.

[0066] The DS-ECU executes the emergency steering control to steer the vehicle SV in order 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 arrow a1.

[0067] For the sake of simplicity, the emergency steering control that is executed in response to the fulfillment of the first condition is also referred to as "emergency steering assistance control", and the emergency steering control that is executed in response to the fulfillment of the second condition is also referred to as "automatic emergency steering control".

[0068] The DS-ECU can be configured to issue a command to the alarm ECU 60 to execute an alarm 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 alarm control is, for example, control of the output of alarm tones from the buzzer 61 to warn the driver. In this case, if the driver detects the obstacle OV1 and turns the steering wheel SW in the direction that will prevent the vehicle SV from colliding with the obstacle OV1 before the predetermined time has elapsed since the warning tones were emitted, the execution of the emergency steering control is initiated. This causes the collision avoidance assist device 10 to work to assist the driver's steering wheel SW input to prevent the vehicle SV from colliding with the obstacle OV1.If the second condition is met, the automatic emergency steering control is initiated if the steering wheel SW has not been turned before the predetermined time has elapsed since the warning tones began. In this case, the collision avoidance assist device 10 works to steer the vehicle SV in order to automatically prevent the collision of the vehicle SV with the obstacle OV1, even if the steering wheel SW is not turned by the driver. <Zusammenfassung des Stoppens oder Aufhebens bzw. Beendens der Notfalllenksteuerung >

[0069] If the lane LA1 of vehicle SV changes from the straight lane to the curved lane during the execution of the emergency steering control, there is a possibility that vehicle SV will be moved out of lane LA1 by the emergency steering control. To prevent vehicle SV from being moved out of lane LA1, the DS-ECU instructs the EPS-ECU 50 to stop the execution of the emergency steering control when lane LA1 has changed to the curved lane (i.e., the radius of curvature R is smaller than the threshold radius Rth).

[0070] If the reliability level of white line detection falls below the threshold while emergency steering control is being executed, the DS-ECU cannot execute the appropriate emergency steering control because the white lines are being incorrectly detected. To prevent the execution of the inadequate emergency steering control, the DS-ECU instructs the EPS-ECU 50 to stop executing the emergency steering control if the reliability level of white line detection falls below the specified threshold. <Zusammenfassung der Operationen der Kollisionsvermeidungsassistenzvorrichtung >

[0071] Fig. Figure 3 shows a situation in which (i) the vehicle SV is moving on lane LA1, which is the straight-ahead lane, (ii) the execution of the emergency steering control is started at time t1, and (iii) the lane LA1 of the vehicle SV changes from the straight-ahead lane to the curved lane at time t2 while the emergency steering control is being executed.

[0072] In the Fig. In the case shown in Figure 3, when the emergency steering control is initiated, lateral movements occur in vehicle SV, and part of the right white line WR is obscured by obstacle OV1 from camera sensor 21b. The right white line WR is located on the right side of obstacle OV1, which vehicle SV does not pass to avoid collision with OV1 (hereinafter, the side of obstacle OV1 that vehicle SV does not pass to avoid collision with OV1 is also referred to as the "non-avoidance side"). Therefore, the detection reliability level for the right white line WR is low. Thus, as in the comparison example, the accuracy of the calculation of the radius of curvature R of the detected lane LA1, based on the left and right white lines WL and WR, is low.

[0073] Therefore, if, as in the comparison example, the radius of curvature R is calculated as a value larger than the actual radius of curvature R (see line b1), the lane LA1, in which vehicle SV is moving, will be determined to be the straight lane, even though vehicle SV is moving in lane LA1, which is the curved lane. Consequently, in the comparison example, the execution of the emergency steering control cannot be stopped, even though it should be. In this case, as shown by the dashed arrow a2, there is a possibility that the vehicle SV will be moved out of lane LA1 by the execution of the emergency steering control, which is not desirable.

[0074] Fig. Figure 4 shows a situation in which (i) the vehicle SV is moving on lane LA1, which is the straight-ahead lane, (ii) the execution of the emergency steering control is started at time t1, and (iii) the lane LA1 of the vehicle SV does not change from the straight-ahead lane to the curved lane on which the emergency steering control is executed.

[0075] In this case, for the same reasons, the detection accuracy of the right white line WR on the non-evasive side of the obstacle decreases. Therefore, if, as in the comparison example, the radius of curvature R of the detected lane is calculated based on the left and right white lines WL and WR, the detection reliability level of the calculated radius of curvature R decreases.

[0076] Therefore, if in the comparison example the radius of curvature R is calculated as a value smaller than the actual radius of curvature R, the lane LA1, in which the vehicle SV is moving, will be determined to be the curved lane, even though the vehicle SV is moving in lane LA1, which is the straight lane. Thus, the execution of the emergency steering control may be stopped, even though it should not be.

[0077] To solve the problems described above, the DS-ECU of the collision avoidance assistance device 10, or a device of the exemplary embodiment, calculates the radius of curvature R of the lane LA1 based solely on the left white line WL on the left side of the obstacle OV1 (this side is also referred to as the "avoidance side of the obstacle"), which the vehicle SV passes to avoid collision with the obstacle OV1 while the emergency steering control is executed. This allows the DS-ECU to eliminate the reduction in the accuracy level of the detection of the calculated radius of curvature R during the execution of the emergency steering control.

[0078] Therefore, if the lane LA1 of vehicle SV changes from the straight lane to the curved lane while the emergency steering control is being executed, the radius of curvature R becomes smaller than a threshold radius Rth, as shown by a line b2 in Fig. 3 shown. Thus, the DS-ECU can appropriately terminate the execution of the emergency steering control. If the vehicle SV's lane LA1 does not change from the straight lane to the curved lane while the emergency steering control is being executed, as shown in Fig. As shown in Figure 4, the DS-ECU can eliminate the inappropriate execution of the emergency steering control.

[0079] If the reliability level for white line detection is calculated based on the left and right white lines WL and WR, as in the comparison example, in a situation that is in Fig. 5 similar to the one in Fig. As depicted in Figure 4, the calculated reliability level for white line detection decreases due to the behavior of vehicle SV, resulting from the execution of the emergency steering control and the glare on the right white line WR from the obstacle OV1, as described above. The causes for the reduction in white line detection reliability described above, such as the deterioration and reduction of the white line intensity, are not significant. Therefore, it is not necessary to terminate the emergency steering control. However, in the comparative example, the white line detection reliability level decreases, and the emergency steering control is unnecessarily stopped.

[0080] On the other hand, the DS-ECU calculates the white line detection reliability level based solely on the white line on the obstacle's evasive side (in this embodiment, the left white line WL) while the emergency steering control is being executed. For example, the left white line WL detection reliability level is used as the white line detection reliability level. The detection reliability level for the white line on the obstacle's evasive side does not readily decrease due to the vehicle SV's lateral movements, and the obstacle's evasive side white line is not obscured by the obstacle OV1. Therefore, the detection reliability level for the obstacle's evasive side white line cannot decrease while the emergency steering control is being executed.If the reliability level of white line detection is calculated solely based on the white line on the side of the obstacle avoiding the obstacle, the calculated reliability level of white line detection will not automatically decrease, even if the reliability level of white line detection on the non-side of the obstacle decreases. In this way, the DS-ECU can prevent the unnecessary execution of the process to stop the emergency steering control if the vehicle SV's lane LA1 does not change from the straight lane to the curved lane during the emergency steering control execution. <Spezifische Operationen>

[0081] The DS-ECU's CPU is configured or programmed to execute routines as shown in the flowcharts in Fig. 6 to Fig. 9 are shown, each time the specified time has elapsed.

[0082] Thus, the CPU begins executing a process at a predetermined time, starting from step 600. Fig. 6 and proceeds to step 605 to determine whether an execution start condition for initiating the emergency steering control execution is met (i.e., one of the first and second conditions described above is satisfied). It should be noted that a condition that the white line detection reliability level is equal to or higher than the threshold reliability level included in the first and second conditions is satisfied if the value of a reliability level reduction flag Xw, described later, is '0'. Furthermore, the condition that the vehicle SV is moving in the straight lane, included in the first and second conditions, is satisfied if the value of the curved lane flag Xcv, described later, is '0'.

[0083] If the execution start condition for the start of the emergency steering control execution is not met (i.e., the first and second conditions are not met), the CPU determines "No" in step 605 and proceeds to step 695 to complete the execution of this routine once.

[0084] On the other hand, if the execution start condition for the commencement of the emergency steering control execution is met (i.e., one of the first and second conditions is met), the CPU determines "Yes" in step 605, executes a process of step 610 as described below, and proceeds to step 695 to complete the execution of this routine once.

[0085] Step 610: The CPU begins executing the emergency steering control.

[0086] Furthermore, the CPU begins executing a process at a predetermined time, starting from step 700. Fig. 7 and proceeds to step 705 to determine whether the emergency steering control is executed. The CPU determines that the emergency steering control will be executed until its execution is terminated or canceled since it was initiated, or until its execution is stopped since it was initiated.

[0087] If the emergency steering control is not executed, the CPU determines "No" in step 705 and proceeds to step 795 to complete the execution of this routine once.

[0088] On the other hand, if the emergency steering control is executed, the CPU determines “Yes” in step 705 and proceeds to step 710 to determine if the value of a cancellation flag Xca is “0”.

[0089] The value of the cancellation flag Xca is set to "1" if the white line detection reliability level is low or if the lane is a curved lane. Conversely, the value of the cancellation flag Xca is set to "0" if the white line detection reliability level is not low and the lane is not a curved lane. The setting of the cancellation flag Xca will be discussed later with reference to... Fig. 9 described. It should be noted that the value of the cancellation flag Xca is set to “0” by an initialization routine (not shown) that is executed by the CPU when the vehicle SV’s ignition key switch (not shown) is turned from an OFF position to an ON position.

[0090] If the value of the cancellation flag Xca is "0", the CPU determines "Yes" in step 710 and proceeds to step 715 to determine whether a termination condition for ending the execution of the emergency steering control is met. The termination condition for ending the execution of the emergency steering control is, for example, set to a suitable predetermined condition to determine that the avoidance of the collision between vehicle SV and the obstacle by the emergency steering control is complete.

[0091] If the termination condition for ending the execution of the emergency steering control is not met, the CPU determines "No" in step 715 and proceeds to step 795 to terminate the execution of this routine once.

[0092] On the other hand, if the abort condition to terminate the execution of the emergency steering control is met, the CPU determines "Yes" in step 715, executes a process of step 720 described below, and proceeds to step 795 to terminate the execution of this routine once.

[0093] Step 720: The CPU terminates the execution of the emergency steering control.

[0094] If the value of the override flag Xca is "1" at the time of process execution in step 710, the CPU determines "No" in step 710 and proceeds to step 725 to stop the execution of the emergency steering control. The CPU then proceeds to step 795 to complete the execution of this routine once.

[0095] Furthermore, the CPU begins executing a process at a predetermined time, starting from step 800. Fig. 8 and proceeds to step 805 to determine whether the emergency steering control is executed.

[0096] When the emergency steering control is executed, the CPU determines “Yes” in step 805, proceeds to step 810 to calculate the white line detection reliability level and the radius of curvature R, based only on the white line on the side of the obstacle to avoid, and proceeds to step 815.

[0097] On the other hand, if the emergency steering control is not executed, the CPU determines "No" in step 805, proceeds to step 820 to calculate the white line detection reliability level and the radius of curvature R based on the white lines on both sides (i.e., the left and right white lines), and proceeds to step 815.

[0098] When the CPU proceeds to step 815, it determines whether the white line detection level is lower than the threshold reliability level. If the white line detection reliability level is lower than the reliability threshold, the CPU determines "Yes" in step 815, proceeds to step 825 to set the reliability level reduction flag Xw to "1", and then proceeds to step 830.

[0099] The reliability reduction flag Xw indicates that the reliability level of white line detection is relatively low when its value is "1". Conversely, the reliability reduction flag Xw represents a relatively high reliability level of white line detection when its value is "0". The value of the reliability reduction flag Xw is set to "0" by the executed initialization routine.

[0100] On the other hand, if the reliability level of white line detection is equal to or higher than the threshold reliability level, the CPU determines "No" in step 825, proceeds to step 835 to set the value of the reliability level reduction flag Xw to "0", and proceeds to step 830.

[0101] When the CPU proceeds to step 830, it determines whether the radius of curvature R is smaller than the threshold radius Rth. In other words, the CPU determines whether the vehicle SV's path is the curved path.

[0102] If the radius of curvature R is smaller than the threshold radius Rth (i.e., the vehicle SV's lane is the curved lane), the CPU determines "Yes" in step 830, executes a process of step 840 described below, and continues the process to step 895 to complete the execution of this routine once.

[0103] Step 840: The CPU sets the value of a curved lane flag Xcv to "1".

[0104] The curved lane flag Xcv indicates that the lane of vehicle SV is the curved lane when the value of the curved lane flag Xcv is "1". Conversely, the curved lane flag Xcv indicates that the lane of vehicle SV is not the curved lane (i.e., the lane of vehicle SV is the straight lane) when the value of the curved lane flag Xcv is "0".

[0105] On the other hand, if the radius of curvature R is equal to or greater than the threshold radius Rth (i.e., the vehicle SV's lane is not the curved lane), the CPU determines "No" in step 830, executes a process of step 845 described below, and proceeds to step 895 to complete the execution of this routine once.

[0106] Step 845: The CPU sets the value of the curved lane flag Xcv to "0".

[0107] Furthermore, the CPU begins executing a process at a predetermined time, starting from step 900. Fig. 9 and proceeds to step 905 to determine if the emergency steering control is executed.

[0108] If the emergency steering control is not executed, the CPU determines "No" in step 905 and proceeds to step 995 to complete the execution of this routine once.

[0109] On the other hand, if the emergency steering control is executed, the CPU determines “Yes” in step 905 and proceeds to step 910 to determine if the value of the reliability level reduction flag Xw is “0”.

[0110] If the value of the reliability level reduction flag Xw is "1", the reliability level of white line detection is relatively low, and the execution of the emergency steering control should be stopped. Accordingly, in step 910, the CPU determines "No" and proceeds to step 915 to set the value of the cancellation flag Xca to "1". As a result, the execution of the emergency steering control is stopped (see step 725).

[0111] On the other hand, if the value of the flag Xw for reducing the reliability level is “0”, the CPU determines “Yes” in step 910 and proceeds to step 920 to determine if the value of the curved lane flag Xcv is “0”.

[0112] If the value of the curved lane flag Xcv is "1", the vehicle SV is moving in the lane that is the curved lane. Therefore, the execution of the emergency steering control should be stopped. Accordingly, the CPU determines "No" in step 920, executes the process described above in step 915, and proceeds to step 995 to complete the execution of this routine once. As a result, the execution of the emergency steering control is stopped (see step 725).

[0113] On the other hand, if the value of the curved lane flag Xcv is "0", the vehicle SV is moving in the lane that is the straight lane. Therefore, the execution of the emergency steering control should not be stopped. Accordingly, in step 920, the CPU determines "Yes" and proceeds to step 915 to set the value of the cancel flag Xca to "0". Then, the CPU proceeds to step 995 to complete the execution of this routine once. <effekte>

[0114] As described above, the collision avoidance assistance device 10 can eliminate the inappropriate execution of the process of stopping the execution of the emergency steering control. Furthermore, the collision avoidance assistance device 10 can eliminate the unnecessary execution of the process of stopping the execution of the emergency steering control. <Modifizierte Beispiele>

[0115] The embodiment of the invention has been specifically described, but the invention is not limited to this embodiment. Various modified examples can be used based on the technical concepts of the invention without deviating from the scope of the invention.

[0116] In the embodiment described above, the DS-ECU can be configured to execute one or more of the processes performed by object detection section 21c instead of object detection section 21c.

[0117] Furthermore, in the above embodiment, a curvature (=1 / R) can be used instead of the radius of curvature R. In this case, the DS-ECU determines that the lane is the curved lane if the curvature is greater than a sleeper curvature, and the lane is the straight lane if the curvature is equal to or less than the sleeper curvature.

[0118] Furthermore, in the embodiment described above, the DS-ECU can be configured to stop the vehicle SV before the obstacle OV1 by performing an automatic braking control, if the vehicle SV can be stopped before the obstacle OV1 by braking the vehicle SV before the DS-ECU begins to execute the emergency steering control.

[0119] Furthermore, in the embodiment described above, the DS-ECU can be configured to calculate the reliability level of white line detection based on the white lines on both sides (i.e., the left and right white lines) while the emergency steering control is being executed. In this case, the lane shape parameter is also calculated only based on the white line on the side of the obstacle avoiding the obstacle while the emergency steering control is being executed. In this way, the collision avoidance assistance device 10 can eliminate the inappropriate execution of the process of stopping the emergency steering control.

[0120] Furthermore, in the embodiment described above, the DS-ECU can be configured to execute only one of the emergency steering control functions, from the automatic emergency steering control to the emergency steering assistance control.

[0121] A collision avoidance assistance device (10) performs emergency steering control, which includes processes to determine a target steering torque used to modify a steering angle to prevent a vehicle from colliding with an obstacle, to keep the vehicle from leaving its lane when the vehicle has a high probability of colliding with the obstacle, and the lane is a straight lane, and applies a steering torque equal to the determined target steering torque to a steering mechanism. The collision avoidance assistance device stops executing the emergency steering control if it determines that the lane is curved, based on only one of the left and right lane markings on an evasive side of the obstacle, which is the left or right side of the obstacle over which the vehicle is traveling while executing the emergency steering control.< / 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 obstacles 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 execute an emergency steering control comprising the following processes: Determining a target steering torque used to change the steering angle to avoid collision of the vehicle with the obstacle, so as not to move the vehicle out of a lane defined by the left and right lane markings when (i) the electronic control unit (20) determines that the vehicle has a high probability of colliding with the obstacle, and (ii) the lane is a straight lane; 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 electronic control unit determines that the lane is a curved lane based on only one of the left and right lane markings on an avoidance side of the obstacle, which is the left or right side of the obstacle over which the vehicle passes while the electronic control unit is executing the emergency steering control. [2] Collision avoidance assist device (10) according to claim 1, wherein the electronic control unit (20) is configured to: before the electronic control device (20) starts an execution of the emergency steering control, calculate a lane marking detection reliability level, which represents the overall detection results for the left and right lane markings, based on the left and right lane markings; and to execute the emergency steering control if (i) the electronic control unit determines that the vehicle has a high probability of colliding with the obstacle, (ii) the lane is the straight lane, and (iii) the calculated lane marking detection reliability level is greater than or equal to a threshold reliability level; and while the electronic control device (20) executes the emergency steering control, to calculate the reliability level of lane marking detection based on only one of the left and right lane markings on the avoidance side of the obstacle; and to stop the execution of the emergency steering control when the calculated reliability level of the lane marking detection becomes lower than the threshold reliability level. [3] Collision avoidance assist device (10) according to one of claims 1 and 2, wherein the electronic control unit (20) is configured to: before the electronic control device (20) starts the execution of the emergency steering control, calculate at least one lane shape parameter representing a degree of curvature of the lane based on the left and right lane markings; and to determine whether the lane is the straight lane or the curved lane based on the calculated lane shape parameter; and while the electronic control device (20) executes the emergency steering control, calculate the lane shape parameter based on only one of the left and right lane markings on the avoidance side of the obstacle; and to determine whether the lane is the straight lane or the curved lane based on the calculated lane shape parameter.

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