Conflict Avoidance Support Device

Abstract

To provide a collision avoidance support device capable of reducing a "possibility to perform unnecessary collision avoidance control" during turning of a self vehicle.SOLUTION: A collision avoidance support device starts collision avoidance control (step 445) in a case where it is determined that there is a control object target having the risk of collision with a self vehicle (step 420), and in a case where a collision index value of the control object target satisfies a predetermined control start condition (step 435). When a continuation recognition time being the time when the control object target is continuously detected is shorter than a predetermined threshold recognition time when it is determined that the self vehicle is turning (step 455: No), the collision avoidance support device does not start the collision avoidance control to be performed in a case where the collision index value satisfies the control start condition.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a collision avoidance assistance device that executes collision avoidance control based on information about a target present in front of a vehicle (target information) outputted by a target sensor device.

[0002] A conventionally known collision avoidance support device executes collision avoidance control to avoid a collision between the vehicle and a target when the time until the vehicle collides with the target (hereinafter referred to as "time required for collision") becomes equal to or less than a threshold time. The collision avoidance control includes an alarm control that issues an alarm to the driver of the vehicle, and an automatic brake control that activates an automatic brake to stop the vehicle.

[0003] Furthermore, one of the conventional collision avoidance assistance devices (hereinafter referred to as the "conventional device") changes the threshold time to a shorter time when a curved continuous structure such as a guardrail is detected. This enables the conventional device to reduce the "possibility that collision avoidance control will be executed even though the driver is attempting to steer along a curve." As a result, the conventional device can reduce the possibility that the execution of collision avoidance control will be annoying to the driver (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-149901 A Summary of the Invention

[0005] However, as described below, it has been found that when the host vehicle is turning, particularly at an intersection, there are still cases where collision avoidance control is unnecessarily executed.

[0006] More specifically, as shown in (Case A) of Figure 2, when the host vehicle SV is traveling around a curve Cur and the preceding vehicle PV is traveling at a slower speed than the host vehicle SV, it is preferable that collision avoidance control be executed when the time required for collision becomes equal to or less than a threshold time.

[0007] In contrast, as shown in (Case B) and (Case C) of Fig. 2, when the host vehicle SV is turning to turn right at the intersection Int and another vehicle is stopped waiting for a traffic light in the oncoming lane of the road into which the host vehicle SV is to turn right, it is not desirable to execute collision avoidance control for such another vehicle. This is because the host vehicle SV generally travels straight after completing the right turn, and therefore the possibility of colliding with the other vehicle is extremely low.

[0008] However, when the vehicle path (vehicle passing area) estimated based on the turning movement of the vehicle SV overlaps with the position of any of the other vehicles OV1-OV3, the conventional device may recognize the other vehicle as an object to be controlled and execute collision avoidance control.

[0009] For example, in the situation shown in Fig. 2 (Case B), the host vehicle route overlaps with the position of the first other vehicle OV1 (the leading vehicle among multiple other vehicles waiting at a traffic light), so collision avoidance control may be executed while the host vehicle SV is turning. However, in this case, the inventor has found that it is possible to avoid unnecessary execution of collision avoidance control by "changing the above-mentioned threshold time to a shorter time when it is determined that the host vehicle SV is turning compared to when it is determined that the host vehicle SV is not turning."

[0010] However, in the situation shown in FIG. 2 (Case C), it has been found that the host vehicle path overlaps with the position of the second vehicle OV2, and collision avoidance control may be executed for this vehicle OV2. In this case, it is often impossible to avoid unnecessary collision avoidance control by simply changing the above-mentioned threshold time to a shorter time. This is because the target sensor device of the host vehicle recognizes the second vehicle OV2 later than the first vehicle OV1, and the collision time may be considerably short (for example, shorter than the threshold time set to the above-mentioned short time) at the time when it is determined that the second vehicle OV2 is on the host vehicle path.

[0011] The present invention has been made to address the problems described above, and one of its objectives is to provide a collision avoidance assistance device that can reduce the "possibility of unnecessary collision avoidance control being executed" while the vehicle is turning.

[0012] One aspect of the collision avoidance support device of the present invention is to a target sensor device (40) that detects a target present in front of the host vehicle and outputs target information including information regarding the position of the detected target; An information acquisition device (50, 60, 80) that acquires host vehicle behavior information indicating a behavior of the host vehicle; A control unit (10, 20, 30); Includes.

[0013] The control unit When it is determined based on the target information and the host vehicle behavior information that there is a control target with which the host vehicle may collide (step 420: Yes), a collision index value (TTC) indicating a possibility that the host vehicle will collide with the control target is generated based on at least the target information related to the control target; When the collision index value satisfies a predetermined control start condition, collision avoidance control for avoiding a collision between the host vehicle and the control target is started using the actuators (21, 31, 70) of the host vehicle (step 435: Yes, step 445).

[0014] As described above, when the vehicle is about to turn right at an intersection in an area where traffic laws stipulate that vehicles should drive on the left side of the road, the time when the vehicle starts to recognize the second and subsequent vehicles among multiple vehicles stopped in the oncoming lane of the road after the vehicle makes the right turn is later than the time when the vehicle starts to recognize the first vehicle. This phenomenon also occurs when the vehicle is about to turn left at an intersection in an area where traffic laws stipulate that vehicles should drive on the right side of the road.

[0015] Then, the control unit: When it is determined that the host vehicle is turning based on the host vehicle behavior information (step 425: Yes), if a continuous recognition time (Trcg), which is the time during which the control target object continues to be detected by the target sensor device, is shorter than a predetermined threshold recognition time (Trth), the collision avoidance control, which is executed when the collision index value satisfies the control start condition, is not started (step 455: No).

[0016] The continuous recognition time of the second and subsequent vehicles among a plurality of other vehicles stopped in the oncoming lane of the road after the vehicle turns right or left is relatively short. Therefore, according to the above aspect, the collision avoidance control is not started when the continuous recognition time is shorter than the predetermined threshold recognition time, so that it is possible to reduce the possibility that unnecessary collision avoidance control is executed for the second and subsequent vehicles among the plurality of other vehicles.

[0017] In one aspect of the collision avoidance support device of the present invention, The control unit When it is determined that the host vehicle is turning based on the host vehicle behavior information (step 425: Yes), the control start condition is changed (step 450, step 430) so that the control start condition is less likely to be satisfied compared to when it is determined that the host vehicle is not turning based on the host vehicle behavior information (step 425: No).

[0018] More specifically, The control unit A time to collision (TTC), which is the time required for the host vehicle to collide with the control object, is calculated as the collision index value (step 435); When it is determined that the time to collision is equal to or less than the collision avoidance threshold (TTCth), it is determined that the control start condition is satisfied (step 435: Yes).

[0019] The control unit further comprises: When it is determined that the host vehicle is turning based on the host vehicle behavior information (step 425: Yes), the collision avoidance threshold is set to a smaller value (Tshоrt) compared to when it is determined that the host vehicle is not turning based on the host vehicle behavior information, so that the control start condition is less likely to be satisfied (steps 450, 430). In other words, when it is determined that the host vehicle is not turning based on the host vehicle behavior information, the control unit sets the collision avoidance threshold to a first value (straight-traveling threshold time Tlоng) (step 430), and when it is determined that the host vehicle is turning based on the host vehicle behavior information, the control unit sets the collision avoidance threshold to a second value (turning threshold time Tshоrt shorter than the straight-traveling threshold time Tlоng) (step 450).

[0020] According to this aspect, when the host vehicle is turning, the collision avoidance control is not started until the host vehicle approaches the control object (until the possibility of collision becomes higher) compared to when the host vehicle is not turning. Therefore, it is possible to reduce the possibility that the collision avoidance control is unnecessarily executed for the first other vehicle among multiple other vehicles stopped in the oncoming lane of the road after the host vehicle turns right or left.

[0021] The present invention also provides a program for causing a computer (for example, a processor of a microcomputer) to realize the functions for carrying out the above-mentioned control.

[0022] In the above description, in order to facilitate understanding of the invention, the reference symbols used in the embodiments are enclosed in parentheses with respect to the constituent elements of the invention corresponding to the embodiments. However, each constituent element of the present invention is not limited to the embodiments defined by the reference symbols. [Brief description of the drawings]

[0023] [Figure 1] 1 is a schematic configuration diagram of a collision avoidance assistance device according to an embodiment of the present invention; [Diagram 2] 2 is a diagram for explaining the operation of the collision avoidance assistance device shown in FIG. 1. [Diagram 3] 11 is a graph showing a situation in which a conventional device executes unnecessary collision avoidance control. [Figure 4] 2 is a flowchart showing a routine executed by a CPU of the driving assistance ECU shown in FIG. 1. [Diagram 5] 4 is a flowchart showing a routine executed by a CPU of a first modified example of the driving assistance ECU shown in FIG. [Figure 6] FIG. 2 is a plan view of the host vehicle and a target for explaining an overlap ratio. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] (composition) A collision avoidance support device 1 according to an embodiment of the present invention shown in Fig. 1 is mounted on a vehicle. Hereinafter, the vehicle on which the collision avoidance support device 1 is mounted will be referred to as a "host vehicle" in order to distinguish it from other vehicles.

[0025] The collision avoidance support device 1 includes a driving support ECU 10, a meter ECU 20, a brake ECU 30, a target sensor device 40, a vehicle state sensor 50, a driving operation state sensor 60, a sound generation device 70 including a buzzer, and a communication device 80.

[0026] Each of the driving assistance ECU 10, the meter ECU 20, and the brake ECU 30 is an electronic control device having a microcomputer as a main part. ECU is an abbreviation of Electronic Control Unit, and is also called a controller. The microcomputer includes a CPU, a ROM, a RAM, a non-volatile memory, and an interface I / F. The CPU realizes various functions by executing instructions (i.e., programs or routines) stored in the ROM. Some or all of these ECUs and a target detection ECU 43 described later may be integrated into one ECU. Furthermore, these ECUs are connected to each other via a CAN (Controller Area Network) (not shown) so as to be able to exchange information with each other. In the following, the driving assistance ECU 10 is simply called a "DSECU".

[0027] The DSECU is connected to the target sensor device 40, the vehicle state sensor 50 and the driving operation state sensor 60, and is adapted to receive signals therefrom.

[0028] The target sensor device 40 detects a target present in front of the vehicle (a detection range extending forward from the vehicle at a predetermined angle) and outputs target information including information on the position of the detected target. More specifically, the target sensor device 40 includes a radar sensor 41, a camera sensor 42, and a target detection ECU 43.

[0029] The radar sensor 41 is fixed to the front end of the vehicle body at a substantially central position in the vehicle width direction (hereinafter, may be referred to as the “front end central portion”). The radar sensor 41 includes a “radar transmitting / receiving unit and a radar processing unit”, neither of which are shown in the figure.

[0030] The radar transmitting and receiving unit transmits radio waves (e.g., millimeter wave band radio waves) to a detection area that spreads from the front end center of the vehicle at a first angle in front of the vehicle. The radio waves transmitted from the radar transmitting and receiving unit are reflected by targets present in the detection area. The radar transmitting and receiving unit receives the reflected waves. The radar processing unit detects targets present in front of the vehicle based on the transmitted radio waves and the received reflected waves. Furthermore, the radar processing unit generates information about the detected targets (hereinafter, sometimes referred to as "radar target information") every time a predetermined time elapses. The radar sensor 41 (radar processing unit) outputs the radar target information to the target detection ECU 43.

[0031] The radar target information includes a target ID that identifies the detected target, information about the position of the target relative to the vehicle (e.g., the distance between the vehicle and the target in the longitudinal direction of the vehicle, and the direction of the target), the relative speed of the target (relative to the vehicle), and the time during which the target with the target ID continues to be detected (hereinafter sometimes referred to as the "radar recognition time TR").

[0032] The camera sensor 42 includes a stereo camera and an image processing unit, neither of which is shown.

[0033] The stereo camera captures an image of an area in front of the vehicle, centered on the left side of the vehicle, and an area in front of the vehicle, centered on the right side of the vehicle, with a predetermined angle of view, thereby acquiring a pair of left and right image data every time a predetermined time has elapsed.

[0034] The image processing unit detects a target object existing in front of the vehicle based on a pair of left and right image data captured by the stereo camera. Furthermore, the image processing unit generates information on the detected target object (hereinafter, sometimes referred to as "camera target object information") every time a predetermined time has elapsed. The camera sensor 42 (image processing unit) outputs the camera target object information to the target object detection ECU 43.

[0035] The camera target information includes a target ID that identifies the detected target, information about the position of the target relative to the vehicle (e.g., the distance between the vehicle and the target in the longitudinal direction of the vehicle, and the position of the target in the width direction of the vehicle relative to the vehicle), and the time during which the target with the target ID continues to be detected (hereinafter sometimes referred to as the "camera recognition time TC").

[0036] Based on the pair of left and right image data, the camera sensor 42 recognizes the left and right lane markers (typically "white lines" or "yellow lines", hereinafter simply referred to as "white lines") on the road on which the vehicle is traveling, obtains the position of the vehicle relative to the white lines (position in the lane width direction) and also obtains parameters related to the shape of the road (e.g., the curvature of the road).

[0037] The target detection ECU 43 finally recognizes targets ahead of the vehicle by synthesizing (integrating, i.e., fusing) the radar target information from the radar sensor 41 and the camera target information from the camera sensor 42, and generates target information for the finally recognized targets. Furthermore, the target detection ECU 43 assigns a target ID to each finally recognized target, and calculates the time during which the target assigned with a specific target ID continues to be recognized by the target detection ECU 43 (hereinafter, sometimes referred to as "continuous recognition time Trcg") based on the radar recognition time TR and the camera recognition time TC. The target detection ECU 43 outputs this information (i.e., the integrated target information, the target ID, and the continuous recognition time Trcg, etc.) to the DSECU as integrated target information every time a predetermined time elapses.

[0038] The target detection ECU 43 outputs the target information of a certain target (i.e., either the radar target information or the camera target information) to the DSECU as the target information of the finally recognized target even when the certain target is detected by only one of the radar sensor 41 and the camera sensor 42. However, the target detection ECU 43 may output the integrated target information of the certain target to the DSECU only when the certain target is detected by both the radar sensor 41 and the camera sensor 42.

[0039] The target detection ECU 43 may be integrated into the DSECU. In other words, the above functions realized by the target detection ECU 43 may be realized by the DSECU. Furthermore, the target sensor device 40 may include only one of the radar sensor 41 and the camera sensor 42, or may include another type of target sensor device (for example, LiDAR = Laser Imaging Detection and Ranging).

[0040] The DSECU executes collision avoidance control as driving assistance control that assists the driver in driving operations. The collision avoidance control may be referred to as pre-crash safety control (PCS control). As described later, the collision avoidance control includes warning control and automatic brake control. The warning control is a control that calls the driver's attention to the target by generating a warning sound from the sounding device 70 and displaying a warning mark on the display 21 when it is determined that the possibility of the host vehicle colliding with the target has reached a first stage. The automatic brake control is a control that stops the host vehicle by applying a braking force to the host vehicle via the brake ECU 30 when it is determined that the possibility of the host vehicle colliding with the target has reached a second stage that is higher than the first stage, thereby avoiding a collision between the host vehicle and the target.

[0041] The vehicle condition sensor 50 includes, for example, a plurality of "sensors for detecting parameters representative of the vehicle condition" listed below. A yaw rate sensor 51 detects the yaw rate Yr of the host vehicle. A vehicle speed sensor 52 that detects the vehicle's running speed (vehicle speed) SPD A longitudinal acceleration sensor 53 detects longitudinal acceleration Gx, which is the acceleration of the host vehicle in the longitudinal direction. A lateral acceleration sensor 54 detects a lateral acceleration Gy, which is the acceleration of the host vehicle in the lateral direction (vehicle width direction).

[0042] The driving operation state sensor 60 includes, for example, a plurality of "sensors for detecting parameters indicative of the driving operation state of the driver" as listed below. An accelerator operation amount sensor 61 detects an operation amount Ap of an accelerator pedal of the host vehicle. A brake operation amount sensor 62 detects an operation amount Bp of a brake pedal of the host vehicle. A steering angle sensor 63 detects the steering angle θ of the steering wheel of the host vehicle.

[0043] The information acquired by the DSECU from the vehicle state sensor 50 and the driving operation state sensor 60 may be referred to as "subject vehicle behavior information." Some or all of the sensors included in the vehicle state sensor 50 and the driving operation state sensor 60 may be connected to an ECU other than the DSECU. In that case, the DSECU receives an output signal of the sensor from the ECU to which the sensor is connected via the CAN.

[0044] The DSECU is connected to the meter ECU 20 , the brake ECU 30 , the sound generation device 70 and the communication device 80 .

[0045] The meter ECU 20 is connected to a display 21 provided in front of the driver's seat. The meter ECU 20 controls an image displayed on the display 21 in accordance with a display command transmitted from the DSECU. The display 21 can be said to be an actuator that realizes the function of "displaying some kind of information."

[0046] The brake ECU 30 is connected to a brake actuator 31. The brake actuator 31 is provided in a hydraulic circuit between a master cylinder (not shown) and a friction brake mechanism 32. The friction brake mechanisms 32 are provided on the left, right, front and rear wheels (i.e., on each of all the wheels). The brake actuator 31 operates the wheel cylinders by adjusting the hydraulic pressure supplied to the "wheel cylinders built into the brake calipers" in response to an instruction from the brake ECU 30, thereby pressing the brake pads against the brake discs to generate a friction braking force. Therefore, the brake ECU 30 can control the braking force of the vehicle by controlling the brake actuator 31.

[0047] The sound generating device 70 is driven according to a sound command transmitted from the DSECU, and generates an alarm sound in a manner specified by the sound command. It can be said that the sound generating device 70 is an actuator that realizes the function of "generating some kind of alarm sound."

[0048] The communication device 80 communicates between the DSECU and equipment external to the vehicle (e.g., roadside units, other vehicles, traffic centers, etc.) to obtain information regarding the behavior of the vehicle (vehicle behavior information) and information regarding targets in front of or around the vehicle, and is capable of providing the obtained information to the DSECU every time a predetermined time has elapsed.

[0049] (Collision avoidance control overview) The DSECU executes collision avoidance control (warning control and automatic brake control). Since the collision avoidance control itself is a well-known control, it will be described briefly here.

[0050] As shown in (Case A) of Fig. 2, the DSECU estimates a passing area SP of the host vehicle SV (a strip-shaped area between the dashed lines SL and SR) during a "period from the present time to a time point after a predetermined fixed time (estimation period)". Hereinafter, this passing area SP of the host vehicle SV may be referred to as "host vehicle path SP or host vehicle passing area SP". A specific example of a method for estimating the host vehicle passing area SP will be described later.

[0051] Similarly, the DSECU estimates a passing area (a belt-like area between the dashed lines PL and PR) PP of the "target detected by the target sensor device 40 (the preceding vehicle PV which is another vehicle in (Case A) of FIG. 2)" during the estimation period based on the integrated target information. The target detected by the target sensor device 40 is not necessarily another vehicle, but in the following, it is assumed to be the other vehicle PV for the sake of simplicity of explanation.

[0052] The passing area PP of the other vehicle PV is an area through which the "rear end of the other vehicle" passes during the estimation period, and may be referred to as the "other vehicle path PP or other vehicle passing area PP" below. A specific example of a method for estimating the other vehicle passing area PP will be described later.

[0053] Next, the DSECU judges whether the host vehicle pass area SP and the other vehicle pass area PP intersect. When the DSECU judges that the host vehicle pass area SP and the other vehicle pass area PP intersect, the DSECU recognizes the other vehicle (target) corresponding to the other vehicle pass area PP as a control target (i.e., a target or an obstacle with which the host vehicle may collide).

[0054] When the DSECU recognizes a control target, it calculates the time to collision TTC for the control target. The time to collision TTC is the time required for the host vehicle SV to move from the "current position of the host vehicle SV" to the "position where the host vehicle passing area SP and the other vehicle passing area PP first intersect (intersection position)" under the assumption that the host vehicle SV runs while maintaining the current state. For example, if the host vehicle SV is currently moving straight at a vehicle speed V and the distance between the host vehicle SV and the intersection position is L, the time to collision TTC is calculated by dividing the distance L by the vehicle speed V (TTC = L / V). Also, even if it is assumed that the host vehicle SV moves along an arc of radius r, the time to collision TTC can be calculated by the usual calculation using the arc r and the vehicle speed V of the host vehicle (for example, when the central angle of the arc is θ, TTC = r θ / V).

[0055] The time to collision TTC is an index value (hereinafter, may be referred to as a "collision index value") that indicates the likelihood that the host vehicle SV will collide with the controlled object. The shorter the time to collision TTC, the higher the likelihood that the host vehicle SV will collide with the controlled object. The collision index value is not limited to the time to collision TTC. For example, the DSECU may obtain the collision index value by applying the current "vehicle speed SPD, steering angle θ, and position of the intersection position relative to the host vehicle SV (e.g., the distance between the host vehicle SV and the intersection position)" of the host vehicle SV to a predetermined lookup table. In this case, the collision index value may be a value that indicates that the larger the value, the higher the likelihood that the host vehicle SV will collide with the controlled object. In other words, the collision index value may have a correlation (monotonically increasing or decreasing) with the likelihood that the host vehicle SV will collide with the controlled object.

[0056] When the possibility of the host vehicle SV colliding with the control object (i.e., the collision index value) reaches the warning threshold (for example, when the time to collision TTC falls below the warning threshold time TWth), the DSECU recognizes the control object as an obstacle that requires a warning. When the DSECU recognizes an obstacle that requires a warning, it transmits a sound command to the sound device 70 to cause the sound device 70 to sound intermittently, and transmits a display command to the display device 21 to display the words "Brake!" on the display device 21. In other words, the DSECU issues a warning to the driver. This series of controls for issuing a warning is the warning control.

[0057] Thereafter, when the possibility of the host vehicle SV colliding with the control target becomes higher and the collision index value reaches the braking threshold (for example, when the time to collision TTC becomes equal to or less than the "braking threshold time TBth shorter than the warning threshold time TWth"), the DSECU transmits a command (automatic brake command) to the brake ECU 30 to generate a friction braking force and stop the host vehicle SV. This series of controls for performing braking is the automatic brake control.

[0058] (Outline of operation of collision avoidance support device 1) The conventional device also executes the above-mentioned collision avoidance control. Therefore, as shown in (Case A) of Fig. 2, when the host vehicle SV is traveling on a curve Cur and the preceding vehicle PV is traveling slower than the host vehicle SV, the warning control is executed when the time to collision TTC becomes equal to or less than the warning threshold time TWth, and the automatic brake control is executed when the time to collision TTC becomes equal to or less than the braking threshold time TBth. Therefore, it is possible to avoid the host vehicle SV from colliding with the target (in this case, the preceding vehicle PV).

[0059] However, as shown in (Case B) of FIG. 2, when the host vehicle SV is turning to turn right at the intersection Int and another vehicle OV1 is stopped in the oncoming lane of the road into which the host vehicle SV is to turn right because it is waiting for a traffic light, there is a possibility that collision avoidance control will be executed for such another vehicle OV1. More specifically, when the host vehicle starts to turn right, the host vehicle path (host vehicle passing area) may intersect with the position of the other vehicle OV1 that is stopped because it is waiting for a traffic light, and in this case, the other vehicle OV1 will be recognized as a target to be controlled. Then, if the host vehicle SV continues to turn right, the time to collision TTC will become equal to or less than the warning threshold time TWth, or even equal to or less than the braking threshold time TBth. In this case, unnecessary collision avoidance control (warning control, automatic brake control) will be executed.

[0060] In addition, as shown in (Case C) of Fig. 2, after the host vehicle SV starts to turn right, the host vehicle route (host vehicle passing area) may intersect with the position of "other vehicle OV2, which is the second vehicle from the front among multiple other vehicles stopped at a traffic light." Even in this case, the other vehicle OV2 is recognized as a control target, and therefore a situation occurs in which unnecessary collision avoidance control (warning control, automatic brake control) is executed for the other vehicle OV2.

[0061] Fig. 3 is a graph showing a situation in which the conventional device executes warning control as the above-mentioned unnecessary collision avoidance control. The inventor derived the following findings 1 and 2 from this graph. Note that this conventional device changes the warning threshold time TWth as follows: TWth = f(LR) TTCbth Here, the function f(LR) indicates a coefficient that changes according to the overlap ratio LR between the host vehicle and the controlled object (the degree of overlap at the time of collision between the two, the value LR (=LL / (2 d)) shown in Fig. 6), and varies within the range greater than 0 and less than or equal to 1. The value of the function f(LR) is "1" when the overlap ratio LR is close to "1", and increases towards "1" as the overlap ratio LR approaches a value close to "1" (see the block map in Fig. 5). TTCbth is a constant reference value.

[0062] (Finding 1) As can be seen from the plot in the ellipse Y1 in FIG. 3, the time to collision TTC at the time when the warning control is activated for the first other vehicle OV1 is relatively long (i.e., in the example of FIG. 3, TTC is longer than "a time of about t0+4tc"). Therefore, if the warning threshold time TWth (collision avoidance threshold TTCth for warning control) is set to a smaller value compared to when the host vehicle is traveling straight, it is possible to reduce the possibility that warning control as collision avoidance control will be unnecessarily activated for the other vehicle OV1. Similarly, if the braking threshold time TBth (collision avoidance threshold TTCth for automatic brake control) is set to a smaller value compared to when the host vehicle is traveling straight, it is possible to reduce the possibility that automatic brake control as collision avoidance control will be unnecessarily activated for the other vehicle OV1.

[0063] (Finding 2) As can be seen from the plot in the ellipse Y2 in FIG. 3, the time to collision TTC at the time when the warning control is activated for the second other vehicle OV2 is relatively short. Therefore, even if the warning threshold time TWth (collision avoidance threshold TTCth for warning control) is set to a smaller value compared to when the host vehicle is traveling straight, it is difficult to avoid the execution of warning control as unnecessary collision avoidance control for the second other vehicle OV2. On the other hand, the time during which the other vehicle OV2 continues to be recognized by the target sensor device 40 until the warning control for the second other vehicle OV2 is executed (i.e., the continuous recognition time Trcg) is shorter than the continuous recognition time Trcg of the first other vehicle OV1. This is considered to be due to the fact that the target sensor device 40 has a detection area that spreads forward from the host vehicle at a predetermined angle, so that the other vehicle OV2 cannot be detected immediately after the host vehicle SV starts to turn right, but the other vehicle OV2 begins to be detected after the host vehicle SV advances for a while from the start of the right turn.

[0064] From the above, the inventor has come to the insight that "if warning control as collision avoidance control is not executed (started) for a target whose continuing recognition time Trcg has not reached a predetermined threshold recognition time Trth, the possibility of collision avoidance control being unnecessarily executed for another vehicle OV2 can be reduced."

[0065] Therefore, the collision avoidance assistance device 1 is configured as follows based on the above findings 1 and 2. (1) The collision avoidance threshold TTCth when the host vehicle is turning is changed to a value smaller than the collision avoidance threshold TTCth when the host vehicle is not turning. More specifically, the warning threshold time TWth when the host vehicle is turning is set to a value smaller than the warning threshold time TWth when the host vehicle is not turning. Similarly, the braking threshold time TBth when the host vehicle is turning is set to a value smaller than the braking threshold time TBth when the host vehicle is not turning. (2) When the host vehicle is turning, the “collision avoidance control activated when the collision avoidance threshold TTCth is equal to or less than the collision avoidance threshold TTCth” is not started (executed) for a target whose continuous recognition time Trcg has not reached the threshold recognition time Trth.

[0066] (Specific operation) The CPU of the DSECU (hereinafter simply referred to as "CPU") executes a routine shown in the flowchart of Fig. 4 every time a predetermined time has elapsed. This routine is a routine for carrying out the above-mentioned warning control as collision avoidance control. However, it is also possible to execute the above-mentioned automatic brake control as collision avoidance control using a routine equivalent to this routine.

[0067] At a predetermined timing, the CPU starts the process from step 400 in FIG. 4 and proceeds to step 405 to determine whether or not the value of the PCS operation flag XPCS is "0". When the flag XPCS has a value of "0", it indicates that collision avoidance control (warning control in this case) is not being executed, and when the flag XPCS has a value of "1", it indicates that collision avoidance control is being executed (see step 440 described later). Therefore, in step 405, the CPU determines whether or not the state of the host vehicle SV is a state in which collision avoidance control is not being executed. The flag XPCS is set to "0" in an initialization routine executed by the CPU when an ignition key switch (not shown) of the host vehicle SV is moved from the OFF position to the ON position.

[0068] Assuming that the value of the flag XPCS is “0”, the CPU judges “Yes” in step 405 , sequentially executes the processes of steps 410 and 415 described below, and proceeds to step 420 .

[0069] Step 410: The CPU acquires integrated target information from the target sensor device 40 (target detection ECU 43). Step 415: The CPU acquires host vehicle behavior information from the vehicle state sensor 50 and the driving operation state sensor 60.

[0070] When the CPU proceeds to step 420, it estimates (obtains) the host vehicle passing area using the host vehicle behavior information, and estimates (obtains) the other vehicle passing area using the host vehicle behavior information and the integrated target information, according to the method described below.

[0071] <<Estimation of vehicle passing area>> The DSECU determines the current turning radius R1 and turning center point of the host vehicle SV based on the current "yaw rate Yr, lateral acceleration Gy, vehicle speed SPD, steering angle θ, etc." of the host vehicle SV. Then, as shown in (Case A) of Fig. 2, the DSECU determines a center movement path SC along which the front end center of the host vehicle SV will move during the estimation period, based on the turning radius R1 and the turning center point, under the assumption that the host vehicle SV will travel while maintaining the current state during an estimation period having a certain time.

[0072] Next, the DSECU obtains a line that is moved from the center movement path SC to the left in the vehicle width direction by a distance d (strictly speaking, an arc with a radius of (R1+d) from the turning center point when the host vehicle SV is turning right, and an arc with a radius of (R1-d) from the turning center point when the host vehicle SV is turning left) as the left front end movement path SL. Similarly, the DSECU obtains a line that is moved from the center movement path SC to the right in the vehicle width direction by a distance d (strictly speaking, an arc with a radius of (R1-d) from the turning center point when the host vehicle SV is turning right, and an arc with a radius of (R1+d) from the turning center point when the host vehicle SV is turning left) as the right front end movement path SR. As a result of the above, a band-shaped host vehicle passing area SP determined by the left front end movement path SL and the right front end movement path SR is estimated. The distance d is a value obtained by adding a predetermined margin Mg to half the vehicle width (W) of the host vehicle SV (=(W / 2)+Mg). However, the margin Mg may be "0".

[0073] <<Estimation of areas passing other vehicles>> The DSECU determines the turning radius R2 and turning center point of the other vehicle PV at the current time point by using the "integrated target information" of the other vehicle at the current time point and the past time point and the "host vehicle behavior information" of the host vehicle SV at the current time point and the past time point. Then, under the assumption that the other vehicle PV will travel while maintaining the current state during the estimation period, the DSECU determines the center movement path PC along which the front end center of the other vehicle PV will move during the estimation period based on the turning radius R2 and the turning center point.

[0074] Next, the DSECU obtains a line obtained by moving the center movement path PC by a distance dp to the left in the vehicle width direction of the other vehicle PV (strictly speaking, an arc with a radius of (R2+dp) from the turning center point when the other vehicle PV is turning right, and an arc with a radius of (R2-dp) from the turning center point when the other vehicle PV is turning left) as the left end movement path PL. Similarly, the DSECU obtains a line obtained by moving the center movement path PC by a distance dp to the right in the vehicle width direction of the other vehicle PV (strictly speaking, an arc with a radius of (R2-dp) from the turning center point when the other vehicle PV is turning right, and an arc with a radius of (R2+dp) from the turning center point when the other vehicle PV is turning left) as the right front end movement path PR. The DSECU extends each of the left front end movement path PL and the right front end movement path PR to the rear end of the other vehicle PV, and estimates a band-shaped area determined by the two extended paths as the other vehicle passing area PP. The distance dp is a value obtained by adding a predetermined margin Mgp to half the vehicle width (Wp) of the other vehicle PV (=(Wp / 2)+Mgp). However, the margin Mgp may be "0". Even if the detected target is an object other than a vehicle, the DSECU basically estimates the passing area of ​​the target as the target passing area using the same method as described above.

[0075] In step 420, the CPU determines whether the host vehicle passing area SP intersects with the other vehicle passing area (target passing area) PP. In other words, the CPU determines whether there is a target (i.e., a control target) having the other vehicle passing area PP intersecting with the host vehicle passing area SP. If there is no control target, the CPU determines "No" in step 420 and proceeds directly to step 495 to temporarily end this routine. Therefore, in this case, warning control as collision avoidance control is not executed.

[0076] On the other hand, if a control target is present, the CPU judges “Yes” in step 420 and proceeds to step 425 .

[0077] In step 425, the CPU determines whether the host vehicle SV is turning. More specifically, the CPU determines whether the turning radius R1 calculated in step 420 to estimate the host vehicle passing area SP is equal to or smaller than a predetermined threshold radius (R1th). Note that the determination of whether the host vehicle SV is turning may be performed by other methods. For example, the CPU may determine that the host vehicle SV is turning when any one or more of the magnitude of the yaw rate Yr, the magnitude of the lateral acceleration Gy, and the magnitude of the steering angle θ is equal to or larger than the "respectively corresponding turning threshold value."

[0078] If the host vehicle is not turning (ie, if the turning radius R1 is greater than the threshold radius R1th), the CPU determines “No” in step 425 and proceeds to step 430.

[0079] In step 430 , the CPU sets the collision avoidance threshold value TTCth (in this example, the warning threshold time TWth) to the straight-line driving threshold time Tlong, and then proceeds to step 435 .

[0080] In step 435, the CPU calculates the "time required for collision of the control object TTC." Furthermore, the CPU determines whether the "time required for collision of the control object TTC" is equal to or less than the collision avoidance threshold TTCth (in this example, the warning threshold time TWth). If the "time required for collision of the control object TTC" is greater than the collision avoidance threshold TTCth, the CPU determines "No" in step 435 and proceeds directly to step 495 to temporarily end this routine. Therefore, in this case, warning control as collision avoidance control is not executed.

[0081] On the other hand, if the "time required for collision of the control target object TTC" is equal to or less than the collision avoidance threshold TTCth, the CPU judges "Yes" in step 435 and sequentially performs the processes of steps 440 and 445 described below. After that, the CPU proceeds to step 495 and temporarily ends this routine.

[0082] Step 440: The CPU sets the value of the flag XPCS to “1”. Step 445: The CPU executes the warning control described above as collision avoidance control. That is, the CPU sends a display command to the meter ECU 20 and a sounding command to the sounding device 70.

[0083] Incidentally, if the host vehicle is turning when the CPU advances to 425 (that is, if the turning radius R1 calculated to estimate the host vehicle passing area SP is less than or equal to the threshold radius R1th), the CPU determines "Yes" at step 425 and proceeds to step 450.

[0084] At step 450, the CPU sets the collision avoidance threshold TTCth (in this example, the warning threshold time TWth) to the turning threshold time Tshort, which is shorter than the straight-ahead threshold time Tlong. Then, the CPU proceeds to step 455.

[0085] At step 455, the CPU determines whether the continuous recognition time Trcg of the control target object is greater than or equal to the threshold recognition time Trth.

[0086] If the continuous recognition time Trcg is shorter than the threshold recognition time Trth, the CPU determines "No" at step 455 and proceeds directly to step 495 to temporarily end this routine. Therefore, in this case (Trcg < Trth), the warning control as collision avoidance control is not started (is prohibited).

[0087] On the other hand, if the continuous recognition time Trcg is greater than or equal to the threshold recognition time Trth, the CPU determines "Yes" at step 455 and proceeds to step 435. Therefore, if the collision required time TTC of the control target object is less than or equal to the collision avoidance threshold TTCth (in this example, the warning threshold time TWth set to the turning threshold time Tshort), the CPU executes the collision avoidance control (warning control) by performing the processes of "step 440 and step 445" described above in order. Then, the CPU proceeds to step 495 to temporarily end this routine.

[0088] As described above, when it is determined that the host vehicle SV is turning, if the continuous recognition time Trcg of the control object is less than the threshold recognition time Trth, collision avoidance control is not started even if the collision time TTC is less than the "collision avoidance threshold TTCth set to a smaller value than when the host vehicle SV is not turning." Furthermore, when the continuous recognition time Trcg of the control object is greater than or equal to the threshold recognition time Trth, the timing at which collision avoidance control is started is substantially delayed compared to when the host vehicle SV is not turning. As a result, it is possible to reduce the "possibility of collision avoidance control being unnecessarily executed when the host vehicle SV makes a right turn (or left turn) at an intersection."

[0089] In addition, the DSECU can execute automatic brake control as collision avoidance control as follows. In step 430, the CPU sets the collision avoidance threshold TTCth to the "straight-traveling threshold time Tlоngbk for automatic braking." Note that the straight-traveling threshold time Tlоngbk is shorter than the straight-traveling threshold time Tlоng. In step 450, the CPU sets the collision avoidance threshold TTCth to the "turning threshold time Tshоrtbk for automatic braking." The turning threshold time Tshоrtbk is shorter than the straight-traveling threshold time Tlоngbk. Note that the turning threshold time Tshоrtbk is shorter than the turning threshold time Tshоrt. The CPU executes the above-mentioned automatic brake control in step 445. That is, the CPU transmits an automatic brake command to the brake ECU 30.

[0090] (Variation 1) The first modification of the collision avoidance assistance device 1 differs from the collision avoidance assistance device 1 only in that the collision avoidance threshold TTCth is changed in accordance with the overlap ratio LR.

[0091] The CPU of the DSECU in Modification Example 1 (hereinafter simply referred to as "CPU1") is configured to execute the routine shown by the flowchart in FIG. 5 instead of FIG. 4 every time a predetermined time elapses. This routine is a routine for performing the warning control described above as collision avoidance control. However, it is also possible to execute the automatic braking control described above as collision avoidance control using a routine equivalent to this routine.

[0092] The routine shown in FIG. 5 differs from the routine shown in FIG. 4 only in that step 430 is replaced with step 530, step 450 is replaced with step 550, and further, step 570 is added to the routine shown in FIG. 4. Hereinafter, the description will focus on these differences.

[0093] When the host vehicle SV is not turning, CPU1 determines "No" at step 425 and proceeds to step 530. At step 530, CPU1 sets the collision avoidance reference threshold TTCbth (in this example, the warning reference threshold time TWbth) to the straight-ahead threshold time Tlоng and proceeds to step 570.

[0094] On the other hand, when the host vehicle SV is turning, CPU1 determines "Yes" at step 425 and proceeds to step 550. At step 550, CPU1 sets the collision avoidance reference threshold TTCbth (in this example, the warning reference threshold time TWbth) to "the turning threshold time Tshоrt, which is shorter than the straight-ahead threshold time Tlоng". Then, the CPU proceeds to step 455.

[0095] When the continuous recognition time Trcg is shorter than the threshold recognition time Trth, the CPU determines "No" at step 455 and proceeds directly to step 495 to temporarily end this routine. Therefore, in this case (Trcg < Trth), the warning control as collision avoidance control is not started (is prohibited). Therefore, the possibility of executing unnecessary collision avoidance control is reduced.

[0096] On the other hand, if the continuous recognition time Trcg is equal to or greater than the threshold recognition time Trth, the CPU determines “Yes” in step 455 and proceeds to step 570 .

[0097] In step 570, the CPU 1 obtains the overlap ratio LR described above, and obtains the value of the above-mentioned function f(LR) based on the overlap ratio LR (see the block map in FIG. 5). As described above, the overlap ratio LR is a value (LR=LL / (2·d)) indicating the degree of overlap between the host vehicle SV and the control object OV at the time of collision (see FIG. 6). Then, the CPU 1 determines the collision avoidance threshold value TTCth (warning threshold time TWth in this case) by multiplying the value of the function f(LR) by the collision avoidance reference threshold value TTCbth (warning reference threshold time TWbth in this example).

[0098] Therefore, when the overlap ratio LR is an arbitrary value LR1, the collision avoidance threshold TTCth (in this case, the warning threshold time TWth) is smaller when the host vehicle SV is turning than when the host vehicle SV is not turning, and therefore the possibility of unnecessary collision avoidance control being executed is reduced.

[0099] (Variation 2) Variation 2 of collision avoidance support device 1 differs from collision avoidance support device 1 only in that host vehicle behavior information for estimating host vehicle passing area SP and / or host vehicle behavior information used when determining whether host vehicle SV is turning or not is acquired from an external device of host vehicle SV via communication device 80. This makes it possible to accurately estimate host vehicle passing area SP and to accurately determine whether host vehicle SV is turning or not.

[0100] As described above, according to the embodiment and modified examples of the present invention, it is possible to reduce the possibility that unnecessary collision avoidance control is executed when the host vehicle SV is turning. The present invention is not limited to the above embodiment and modified examples, and various modified examples can be adopted within the scope of the present invention.

[0101] For example, the collision avoidance assistance device 1 may acquire information about other targets present in front of or around the vehicle SV via the communication device 80, and use this information in addition to the target information acquired by the target sensor device 40 for collision avoidance control.

[0102] The collision avoidance support device 1 may execute only one of the warning control and the automatic brake control as the collision avoidance control, or may execute PCS control other than the warning control and the automatic brake control instead of or in addition to the warning control and the automatic brake control. Representative examples of PCS control other than the warning control and the automatic brake control are seat belt retraction control and collision avoidance steering control.

[0103] In the embodiment and the modified example of the present invention, when the host vehicle is turning, the "collision avoidance control activated when the collision avoidance threshold TTCth is equal to or less than the collision avoidance threshold TTCth" is not started for a target whose continuous recognition time Trcg has not yet reached the threshold recognition time Trth. However, when the collision avoidance threshold TTCth of the target is equal to or less than the collision avoidance threshold TTCth and another condition is satisfied for the target, the collision avoidance control may be executed. [Explanation of symbols]

[0104] 1... collision avoidance assistance device, 10... driving assistance ECU (DSECU), 40... target sensor device, 41... radar sensor, 42... camera sensor, 43... target detection ECU, 50... vehicle state sensor, 60... driving operation state sensor, 70... sound generation device.

Claims

[Claim 1] a target sensor device that detects a target present in front of the host vehicle and outputs target information including information regarding a position of the detected target; An information acquisition device that acquires host vehicle behavior information indicating a behavior of the host vehicle; a control unit that, when determining based on the target information and the host vehicle behavior information that there is a control target with which the host vehicle may collide, generates a collision index value indicating a possibility of the host vehicle colliding with the control target based on at least the target information related to the control target, and starts collision avoidance control for avoiding a collision between the host vehicle and the control target by using an actuator of the host vehicle when the collision index value satisfies a predetermined control start condition; Including, The control unit When it is determined that the vehicle is turning based on the vehicle behavior information, if a continuous recognition time, which is a time during which the control target object is continuously detected by the target object sensor device, is shorter than a predetermined threshold recognition time, the collision avoidance control that is executed when the collision index value satisfies the control start condition is not started, and When it is determined that the host vehicle is turning based on the host vehicle behavior information, the control start condition is changed so that the control start condition is less likely to be satisfied than when it is determined that the host vehicle is not turning based on the host vehicle behavior information, When it is determined that the host vehicle is not turning based on the host vehicle behavior information, the collision avoidance control is started when the collision index value satisfies the control start condition regardless of the continuous recognition time, Furthermore, The control unit calculating a collision time required for the host vehicle to collide with the control target as the collision index value; comparing the time required for collision with a collision avoidance threshold and determining that the control start condition is satisfied when it is determined that the time required for collision is equal to or less than the collision avoidance threshold; and When it is determined based on the host vehicle behavior information that the host vehicle is turning, the collision avoidance threshold value to be compared with the collision required time is set to a smaller value, making it more difficult for the control start condition to be satisfied, as compared to when it is determined based on the host vehicle behavior information that the host vehicle is not turning, and the control start condition is changed so that when the host vehicle is turning, the timing at which the collision avoidance control is started is delayed compared to when the host vehicle is not turning. It was configured as follows: Collision avoidance support device.

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