Collision avoidance aid

Abstract

The collision avoidance assist device starts the collision avoidance control (step 445) when it is determined that there is a control object target with which the host vehicle can collide (step 420) and the collision index value of the control object target satisfies a prescribed control start condition (step 435). However, the collision avoidance assist device does not start the collision avoidance control performed when the collision index value satisfies the control start condition when it is determined that the host vehicle is turning (step 455: No) and the duration for which the control object target is continuously detected, i.e., the continuous recognition time, is shorter than a prescribed threshold recognition time (step 455: No).

Description

Technical Field

[0001] This invention relates to a collision avoidance assist device that performs collision avoidance control based on information (target information) of a target located in front of the vehicle output by a target sensor device. Background Technology

[0002] Existing collision avoidance assist devices perform collision avoidance control to prevent a collision between the vehicle and the target when the time before the collision occurs (hereinafter referred to as "collision time") falls below a threshold time. Collision avoidance control includes alarm control that alerts the driver of the vehicle, and automatic braking control that activates the automatic brakes to bring the vehicle to a stop.

[0003] Furthermore, one of the existing collision avoidance assist devices (hereinafter referred to as the "existing device") changes the aforementioned threshold time to a shorter time when it detects a curved continuous structure such as a guardrail. As a result, the existing device can reduce the "possibility that collision avoidance control is still executed even if the driver intends to make a steering operation along the curve." Consequently, the existing device can reduce the possibility that the execution of collision avoidance control will annoy the driver (for example, see Patent Document 1).

[0004] Patent Document 1: Japanese Patent Application Publication No. 2018-149901 Summary of the Invention

[0005] However, as described below, it has been found that when the vehicle is turning, especially at intersections, there are still instances where collision avoidance controls are unnecessarily activated.

[0006] More specifically, such as Figure 2 As shown in Case A, when the vehicle SV is traveling on a curve Cur and the preceding vehicle PV is traveling at a lower speed than the vehicle SV, it is preferable to perform collision avoidance control when the collision time becomes less than the threshold time.

[0007] In contrast, such as Figure 2 As shown in Situations B and C, when vehicle SV is turning right at intersection Int and other vehicles in the opposite lane of the road it is entering through the right turn are stopped for waiting at a signal, it is not preferable to apply collision avoidance control to these other vehicles. This is because: generally, vehicle SV will proceed straight after completing the right turn, and therefore the probability of a collision with other vehicles is extremely low.

[0008] However, if the vehicle path (the area the vehicle passes through) inferred from the turning motion of the vehicle SV overlaps with the position of any of the other vehicles OV1-OV3, the existing device may identify the other vehicle as the object to be controlled and perform collision avoidance control.

[0009] For example, in Figure 2 In the situation shown in (Case B), the vehicle's path overlaps with the position of the first other vehicle OV1 (the foremost vehicle among multiple other vehicles waiting at a signal), thus it is possible that collision avoidance control will be executed while the vehicle SV is turning. However, in this case, the inventors discovered that by "changing the aforementioned threshold time to a shorter time when the vehicle SV is determined to be turning compared to when the vehicle SV is determined not to be turning," unnecessary collision avoidance control execution can be avoided.

[0010] However, the following situation was also found: Figure 2 In the situation shown in (Case C), the vehicle's path overlaps with the position of a second other vehicle, OV2, potentially triggering collision avoidance control against OV2. In this case, simply changing the aforementioned threshold time to a shorter time is unlikely to prevent unnecessary collision avoidance control. This is because the vehicle's target sensor device identifies the second other vehicle, OV2, later than it identifies the first other vehicle, OV1, and the time required for a collision at the point when the second other vehicle, OV2, is determined to be on the vehicle's path becomes considerably shorter (e.g., shorter than the threshold time set to the aforementioned shorter time).

[0011] The present invention was made to address the problems described above, and one of its objectives is to provide a collision avoidance assist device that can reduce the likelihood of "performing unnecessary collision avoidance controls" when the vehicle is turning.

[0012] One embodiment of the anti-collision auxiliary device of the present invention includes:

[0013] The target sensor device (40) detects a target existing in front of the vehicle and outputs target information containing information related to the position of the detected target;

[0014] Information acquisition devices (50, 60, 80) acquire vehicle action information representing the actions of the vehicle; and

[0015] Control unit (10, 20, 30).

[0016] If the control unit determines, based on the target information and the vehicle's motion information, that there is a controlled target that the vehicle may collide with (step 420: Yes), it generates a collision index (TTC) value representing the probability of a collision between the vehicle and the controlled target, based at least on the target information related to the controlled target.

[0017] When the collision index value meets the specified control start conditions, the vehicle's actuators (21, 31, 70) are used to initiate collision avoidance control to prevent a collision between the vehicle and the controlled target (step 435: Yes, step 445).

[0018] As stated above, in areas with traffic regulations that allow vehicles to travel on the left, when this vehicle needs to make a right turn at an intersection, the time at which it begins to identify the second or subsequent other vehicles stopped in the oncoming lane after the vehicle's right turn is later than the time at which it begins to identify the first other vehicle. The same situation occurs in areas with traffic regulations that allow vehicles to travel on the right when this vehicle needs to make a left turn at an intersection.

[0019] Therefore, the control unit is configured as follows:

[0020] If the vehicle is determined to be turning based on the vehicle's motion information (step 425: Yes), if the duration of continuous detection of the controlled target by the target sensor device, i.e., the continuous recognition time (Trcg), is shorter than the predetermined threshold recognition time (Trth), the collision avoidance control that was executed when the collision index value met the control start condition will not be started (step 455: No).

[0021] The continuous recognition time for the second and subsequent vehicles among multiple other vehicles in the opposite lane of the road after this vehicle has turned right or left is relatively short. Therefore, according to the above method, since the aforementioned collision avoidance control is not initiated when the continuous recognition time is shorter than the prescribed threshold recognition time, the possibility of performing unnecessary collision avoidance control on the aforementioned multiple other vehicles, especially the second and subsequent vehicles, can be reduced.

[0022] In one embodiment of the anti-collision auxiliary device of the present invention

[0023] When the control unit determines that the vehicle is turning based on the vehicle's motion information (step 425: Yes), it changes the control start condition so that the control start condition is more difficult to meet than when the control unit determines that the vehicle is not turning based on the vehicle's motion information (step 425: No) (steps 450, 430).

[0024] More specifically,

[0025] The control unit calculates the time required until the vehicle collides with the controlled object, i.e., the time required for collision (TTC), as the collision index value (step 435).

[0026] When the control unit determines that the time required for the collision is below the collision avoidance threshold (TTCth), it determines that the control start condition is met (step 435: Yes).

[0027] The control unit is further configured to: when it is determined that the vehicle is turning based on the vehicle's motion information (step 425: Yes), compared to when it is determined that the vehicle is not turning based on the vehicle's motion information, make the control start condition more difficult to meet by setting the collision avoidance threshold to a smaller value (Tshort) (steps 450, 430). In other words, when the control unit determines that the vehicle is not turning based on the vehicle's motion information, it sets the collision avoidance threshold to a first value (threshold time Tlong for straight driving) (step 430); when it determines that the vehicle is turning based on the vehicle's motion information, it sets the collision avoidance threshold to a second value (threshold time Tshort for turning, which is shorter than the threshold time Tlong for straight driving) (step 450).

[0028] According to this method, when the vehicle is turning, collision avoidance control is not initiated before the vehicle gets closer to the object being controlled (before the probability of a collision becomes higher), compared to when the vehicle is not turning. Therefore, it is possible to reduce the likelihood of unnecessarily performing collision avoidance control on the first other vehicle among multiple other vehicles in the oncoming lane that has stopped after the vehicle has turned right or left.

[0029] Furthermore, the present invention is also a program for enabling a computer (e.g., a processor of a microcomputer) to perform the functions for implementing the above-described control.

[0030] In the foregoing description, to aid in understanding the invention, the constituent elements of the invention corresponding to the embodiments have been enclosed in parentheses with reference numerals used in the embodiments. However, the constituent elements of the invention are not limited to the embodiments specified by the reference numerals. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the anti-collision auxiliary device according to an embodiment of the present invention.

[0032] Figure 2 It is used for explanation Figure 1 The diagram shows how the anti-collision auxiliary device works.

[0033] Figure 3 This is a diagram illustrating situations where existing devices are performing unnecessary collision avoidance controls.

[0034] Figure 4 It shows Figure 1The flowchart shown is a routine executed by the CPU of the driving assistance ECU.

[0035] Figure 5 It shows Figure 1 The flowchart shows the routine executed by the CPU of the modified driving assistance ECU, Example 1.

[0036] Figure 6 This is a top view of "this vehicle and the target" used to illustrate the overlap ratio. Detailed Implementation

[0037] (constitute)

[0038] Figure 1 The "collision avoidance assist device 1 according to the embodiment of the present invention" shown is mounted on a vehicle. Hereinafter, the vehicle equipped with the collision avoidance assist device 1 will be referred to as "this vehicle" in order to distinguish it from other vehicles.

[0039] The collision avoidance assist device 1 includes a driver assistance ECU 10, an instrument ECU 20, a brake ECU 30, a target sensor device 40, a vehicle status sensor 50, a driving operation status sensor 60, a sound-emitting device 70 including a buzzer, and a communication device 80.

[0040] The driver assistance ECU 10, instrument cluster ECU 20, and brake ECU 30 are each electronic control devices with a microcomputer as their main component. ECU is short for Electronic Control Unit, also known as a controller. The microcomputer includes a CPU, ROM, RAM, non-volatile memory, and interface I / F, etc. The CPU performs various functions by executing instructions (i.e., programs or routines) stored in the ROM. These ECUs, and several or all of the target detection ECU 43 described later, can also be integrated into a single ECU. Moreover, these ECUs are connected to each other via a CAN (Controller Area Network) (not shown) in a manner that allows them to exchange information. Hereinafter, the driver assistance ECU 10 will be referred to as "DSECU".

[0041] The DSECU is connected to the target sensor device 40, the vehicle status sensor 50, and the driving operation status sensor 60, and receives signals from them.

[0042] The target sensor device 40 detects a target present in front of the vehicle (within a detection range extending forward from the vehicle at a predetermined angle) and outputs target information containing information related to 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.

[0043] The radar sensor 41 is fixed to the front end of the vehicle body and at approximately the center position in the vehicle width direction (hereinafter, sometimes referred to as the "front center part"). The radar sensor 41 includes a "radar transceiver unit and a radar processing unit" which are not shown in the figure.

[0044] The radar transceiver transmits radio waves (e.g., millimeter-wave radio waves) to a detection area extending from the center of the front of the vehicle at a first angle. The radio waves transmitted from the radar transceiver are reflected by a target present within the detection area. The radar transceiver receives this reflected wave. The radar processing unit detects a target present in front of the vehicle based on the transmitted radio waves and the received reflected wave. Furthermore, the radar processing unit generates information about the detected target (hereinafter sometimes referred to as "radar target information") every predetermined time interval. The radar sensor 41 (radar processing unit) outputs the radar target information to the target detection ECU 43.

[0045] Radar target information includes the target ID of the detected target, information about the target's position relative to the vehicle (e.g., the distance between the vehicle and the target in the front and rear axle directions, and the target's orientation), the target's relative speed (relative to the vehicle), and the duration for which the target with the target ID has been continuously detected (hereinafter, sometimes referred to as "radar identification time TR").

[0046] The camera sensor 42 includes a "stereo camera and image processing unit" which are not shown in the figure.

[0047] The stereo camera captures images of the area centered on the left side of the vehicle in front of it and the area centered on the right side of the vehicle in front of it from a specified angle, thereby acquiring a pair of left and right image data at specified intervals.

[0048] The image processing unit detects targets in front of the vehicle based on a pair of left and right image data captured by a stereo camera. Furthermore, the image processing unit generates information about the detected target (hereinafter sometimes referred to as "camera target information") at predetermined intervals. The camera sensor 42 (image processing unit) outputs the camera target information to the target detection ECU 43.

[0049] The camera target information includes the target ID of 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 front and rear axle directions, the position of the target relative to the vehicle in the width direction), and the duration for which the target with the target ID has been continuously detected (hereinafter, sometimes referred to as "camera recognition time TC").

[0050] In addition, the camera sensor 42 identifies the lane markings (typically "white lines" or "yellow lines", hereinafter referred to as "white lines") on the left and right sides of the road on which the vehicle is traveling based on the aforementioned left and right pair of image data, obtains the position of the vehicle relative to the white lines (position in the lane width direction), and obtains parameters related to the shape of the road (e.g., the curvature of the road).

[0051] The target detection ECU 43 ultimately identifies targets ahead of the vehicle by synthesizing (integrating, i.e., fusing) radar target information from radar sensor 41 and camera target information from camera sensor 42, and generates target information for the finally identified targets. Furthermore, the target detection ECU 43 assigns a target ID to each finally identified target, and calculates the duration (hereinafter sometimes referred to as "continuous identification time Trcg") for which the target with a specific target ID is continuously identified by the target detection ECU 43 based on the radar identification time TR and the camera identification time TC. The target detection ECU 43 outputs this information (i.e., the integrated target information, target ID, and continuous identification time Trcg, etc.) to the DSECU as integrated target information every predetermined time interval.

[0052] Even if a target is detected by either the radar sensor 41 or the camera sensor 42, the target detection ECU 43 will output the target information of that target (i.e., either the radar target information or the camera target information) to the DSECU as the final identified target information. However, the target detection ECU 43 may also output the combined target information of a target to the DSECU only if both the radar sensor 41 and the camera sensor 42 detect it.

[0053] Furthermore, the target detection ECU 43 can also be integrated into the DSECU. In other words, the functions described above implemented by the target detection ECU 43 can also be implemented by the DSECU. Moreover, the target sensor device 40 may include only either the radar sensor 41 or the camera sensor 42, or it may include other types of target sensor devices (e.g., LiDAR = Laser Imaging Detection and Ranging).

[0054] The DSECU performs collision avoidance control as a driver assistance control, assisting the driver's driving operations. Collision avoidance control is sometimes referred to as Pre-Collision Safety Control (PCS control). As described below, collision avoidance control includes warning control and automatic braking control. Warning control is as follows: when the probability of a collision between the vehicle and a target is determined to be at stage 1, an alarm sound is emitted from the audible device 70 or an attention arousal sign is displayed on the display 21, thereby prompting the driver to pay attention to the target. Automatic braking control is as follows: when the probability of a collision between the vehicle and a target is determined to be at stage 2, which is higher than stage 1, the vehicle is brought to a stop by applying braking force to the vehicle via the brake ECU 30, thereby avoiding a collision between the vehicle and the target.

[0055] The vehicle status sensor 50 includes, for example, several "sensors that detect parameters representing the vehicle status".

[0056] Yaw rate sensor 51 detects the yaw rate Yr of this vehicle.

[0057] The vehicle speed sensor 52 detects the vehicle's speed (vehicle speed) using the SPD.

[0058] The front and rear acceleration sensor 53 detects the front and rear acceleration of this vehicle, i.e., the front and rear acceleration Gx.

[0059] The lateral acceleration sensor 54 detects the lateral acceleration (vehicle width direction) of this vehicle, i.e., the lateral acceleration Gy.

[0060] The driving operation status sensor 60 includes, for example, several "sensors that detect parameters representing the driver's driving operation status".

[0061] Accelerator operation sensor 61 detects the accelerator pedal operation amount Ap of this vehicle.

[0062] Brake operation amount sensor 62 detects the amount of brake pedal operation Bp of this vehicle.

[0063] Steering angle sensor 63 detects the steering angle θ of the vehicle's steering wheel.

[0064] Furthermore, the information obtained by the DSECU from the vehicle status sensor 50 and the driving operation status sensor 60 is sometimes referred to as "vehicle operation information." Some or all of the sensors included in the vehicle status sensor 50 and the driving operation status sensor 60 can also be connected to an ECU other than the DSECU. In this case, the DSECU receives the sensor's output signal from the ECU connected to the sensor via CAN.

[0065] The DSECU is connected to the instrument ECU 20, the brake ECU 30, the sound device 70, and the communication device 80.

[0066] The instrument cluster ECU 20 is connected to a display 21 located in front of the driver's seat. The instrument cluster ECU 20 controls the images displayed on the display 21 according to display commands sent from the DSECU. Furthermore, the display 21 can be referred to as an actuator that performs the function of "displaying certain information".

[0067] The brake ECU 30 is connected to the brake actuator 31. The brake actuator 31 is located in the hydraulic circuit between the master cylinder (not shown) and the friction brake mechanism 32. The friction brake mechanism 32 is located on each of the left and right front and rear wheels (i.e., each of all wheels). The brake actuator 31 operates the wheel cylinders by adjusting the hydraulic pressure supplied to the "wheel cylinders built into the brake calipers" according to instructions from the brake ECU 30, thereby pushing the brake pads against the brake disc and generating friction braking force. Therefore, the brake ECU 30 can control the braking force of the vehicle by controlling the brake actuator 31.

[0068] The sound-generating device 70 is driven according to the beeping command sent from the DSECU, and generates an alarm sound in a specific manner according to the beeping command. In addition, the sound-generating device 70 can be referred to as an actuator that realizes the function of "generating certain alarm sounds".

[0069] The communication device 80 is able to communicate between the DSECU and external equipment (e.g., roadside equipment, other vehicles, and traffic centers) to obtain information related to the vehicle's actions (vehicle action information) and information related to targets existing in front of or around the vehicle, and provides the obtained information to the DSECU every predetermined time interval.

[0070] (Overview of collision avoidance control)

[0071] The DSECU performs collision avoidance control (alarm control and automatic braking control). Collision avoidance control itself is a well-known control mechanism, so it will be briefly explained here.

[0072] like Figure 2 As shown in Case A, the DSECU estimates the area (the strip-shaped area between the dashed lines SL and SR) through which the vehicle SV passes during the period "from the current time point to a pre-defined time point later (estimated period)". Hereinafter, this area SP through which the vehicle SV passes is sometimes referred to as "the vehicle path SP" or "the vehicle passage area SP". Specific examples of the method for estimating the vehicle passage area SP will be described later.

[0073] Similarly, the DSECU estimates the target detected by the target sensor device 40 during the estimation period based on the integrated target information.Figure 2 In case A, the target is the area PP (the strip between the dashed lines PL and PR) that the vehicle PV is traveling ahead of (other vehicles). The target detected by the target sensor device 40 is not limited to other vehicles, but is assumed to be other vehicle PV for the sake of simplicity in the following description.

[0074] The transit area PP of other vehicles (PV) is the area traversed by the "rear end of other vehicles" during the estimated period, and is sometimes referred to as the "path PP of other vehicles" or the transit area PP of other vehicles. Specific examples of the estimation method for the transit area PP of other vehicles will be described later.

[0075] Next, the DSECU determines whether the vehicle's passage zone SP intersects with other vehicles' passage zones PP. If the DSECU determines that the vehicle's passage zone SP intersects with other vehicles' passage zones PP, it identifies the other vehicle (target) corresponding to that other vehicle's passage zone PP as the target to be controlled (i.e., the target or obstacle that the vehicle may collide with).

[0076] When the DSECU identifies a target being controlled, it calculates the collision time (TTC) related to that target. The collision time (TTC) is the time required for the vehicle SV to move from its current position to the point where it first intersects with other vehicles in the passage area SP and the passage area PP (intersection position), assuming the vehicle SV is maintaining its current state while traveling. For example, if the vehicle SV is traveling straight at speed V at the current time and the distance between the vehicle SV and the intersection position is L, the collision time (TTC) is calculated by dividing the distance L by the speed V (TTC = L / V). Alternatively, assuming the vehicle SV travels along an arc of radius r, the collision time (TTC) can also be calculated using the arc r and the vehicle speed V using standard calculations (e.g., when the central angle of the arc is θ, TTC = r·θ / V).

[0077] The Time Required to Collision (TTC) is an indicator of the probability of a collision between the vehicle's SV and the controlled target (hereinafter, sometimes referred to as the "collision index value"). A shorter TTC indicates a higher probability of a collision between the vehicle's SV and the controlled target. However, the collision index value is not limited to the TTC. For example, the DSECU can also calculate the collision index value by applying the vehicle's SV's current speed (SPD), steering angle (θ), and the position of the intersection point relative to the vehicle's SV (e.g., the distance between the vehicle's SV and the intersection point) to a prescribed lookup table. In this case, the collision index value can also be a value where a larger value indicates a higher probability of a collision between the vehicle's SV and the controlled target. That is, the collision index value only needs to have a correlation (monotonically increasing or monotonically decreasing) with the probability of a collision between the vehicle's SV and the controlled target.

[0078] If the probability of the vehicle SV colliding with the controlled target (i.e., the collision index value) reaches the alarm threshold (e.g., if the collision time TTC is below the alarm threshold time TWth), the DSECU identifies the controlled target as an obstacle for the alarm. Furthermore, if the DSECU identifies an obstacle for the alarm, it sends an alarm command to the audible device 70 to cause the audible device 70 to sound intermittently, and sends a display command to the display 21 to restrict the display of the word "Brake!". In other words, the DSECU generates an alarm for the driver. The series of controls that trigger this alarm constitutes alarm control.

[0079] Subsequently, if the probability of a collision between the vehicle SV and the controlled target becomes higher and the collision index value reaches the braking threshold (e.g., if the collision time TTC becomes "a braking threshold time TBth shorter than the warning threshold time TWth"), the DSECU sends a command (automatic braking command) to the brake ECU 30 to generate friction braking force and stop the vehicle SV. The series of controls that perform this braking is automatic braking control.

[0080] (Summary of the operation of collision avoidance assist device 1)

[0081] Existing devices also perform the aforementioned collision avoidance control. Therefore, as... Figure 2 As shown in Case A, when the vehicle SV is traveling on a curve (Cur) and the vehicle PV traveling ahead is traveling at a lower speed than the vehicle SV, if the collision time TTC is less than or equal to the warning threshold time TWth, then warning control is executed; if the collision time TTC is less than or equal to the braking threshold time TBth, then automatic braking control is executed. Therefore, a collision between the vehicle SV and the target (in this case, the vehicle PV) can be avoided.

[0082] However, in suchFigure 2 As shown in Case B, if vehicle SV is turning right at intersection Int and another vehicle OV1 is stopped in the oncoming lane of the road it is entering through the right turn, collision avoidance control may be performed against such other vehicle OV1. More specifically, there is a situation where the vehicle's path (the area the vehicle is passing through) intersects with the location of another vehicle OV1 that is stopped waiting for a signal at the point when the vehicle has already begun turning right. In this case, the other vehicle OV1 will be identified as the target for control. Furthermore, if vehicle SV continues to turn right, the collision time TTC will fall below the warning threshold time TWth, or even below the braking threshold time TBth. In this case, unnecessary collision avoidance control (warning control, automatic braking control) will be performed.

[0083] Furthermore, there exist such as Figure 2 In case (C), after vehicle SV begins to turn right, the vehicle's path (the area the vehicle passes through) intersects with the position of "other vehicle OV2, the second from the front among multiple other vehicles that are stopped while waiting for a signal". In this case, other vehicle OV2 is also identified as a control target, thus creating a situation where unnecessary collision avoidance controls (warning control, automatic braking control) are performed on other vehicle OV2.

[0084] Figure 3 This is a graph illustrating the situation where the existing device performs alarm control as an unnecessary collision avoidance control as described above. The inventors derived Finding 1 and Finding 2 below from this graph. Furthermore, the existing device modifies the alarm using a threshold time TWth as follows.

[0085] TWth=f(LR)·TTCbth

[0086] Here, the function f(LR) represents the overlap ratio LR between the vehicle and the controlled target (the degree of overlap at the time of collision). Figure 6 The value LR (=LL / (2·d)) shown is a coefficient that varies accordingly, ranging from 0 to 1. The value of the function f(LR) is "1" when the overlap ratio LR is near "1", and the closer the overlap ratio LR is to "1", the larger it becomes towards "1" (see reference). Figure 5 (The curve in the box). TTCbth is a constant baseline value.

[0087] (Discovery 1) As from Figure 3 As understood from the plotted points within the ellipse Y1, regarding the first other vehicle OV1, the collision time TTC required for the alarm control to operate at that point is relatively long (i.e., in...). Figure 3In the example, TTC is longer than "approximately t0 + 4tc". Therefore, if the warning threshold time TWth (collision avoidance threshold TTCth for warning control) is set to a smaller value compared to the situation where the vehicle is traveling straight, the possibility of the warning control, which is a collision avoidance control, unnecessarily activating due to OV1 of other vehicles can be reduced. Similarly, if the braking threshold time TBth (collision avoidance threshold TTCth for automatic braking control) is set to a smaller value compared to the situation where the vehicle is traveling straight, the possibility of the automatic braking control, which is a collision avoidance control, unnecessarily activating due to OV1 of other vehicles can be reduced.

[0088] (Discovery 2) As from Figure 3 As understood from the points plotted within ellipse Y2, the collision time TTC for the second other vehicle OV2 is relatively short at the point when the alarm control operates. Therefore, even if the alarm threshold time TWth (collision avoidance threshold TTCth for alarm control) is set to a smaller value compared to the case where the vehicle is traveling straight, it is difficult to avoid the execution of alarm control for the second other vehicle OV2, which is an unnecessary collision avoidance control. On the other hand, the time (i.e., the continuous recognition time Trcg) for the other vehicle OV2 continuously detected by the target sensor device 40 up to the point when the alarm control for the second other vehicle OV2 is executed is shorter than the continuous recognition time Trcg for the first other vehicle OV1. This is believed to be because the target sensor device 40 has a detection area that extends forward from the vehicle at a predetermined angle. Therefore, it fails to detect the other vehicle OV2 at the moment when the vehicle SV begins to turn right, but if the vehicle SV moves forward for a short time from the start of the right turn, it begins to detect the other vehicle OV2.

[0089] Based on the above, the inventors made the discovery that "if the target does not perform (start) the alarm control as a collision avoidance control if the target does not reach the specified threshold recognition time Trth relative to the continuous recognition time Trcg, the possibility of unnecessarily performing collision avoidance control for other vehicles OV2 can be reduced."

[0090] Therefore, the collision avoidance assist device 1 is configured as described below based on the above findings 1 and 2.

[0091] (1) The collision avoidance threshold TTCth when the vehicle is turning is changed to a smaller value than the collision avoidance threshold TTCth when the vehicle is not turning. More specifically, the warning threshold time TWth when the vehicle is turning is set to a smaller value compared to the warning threshold time TWth when the vehicle is not turning. Similarly, the braking threshold time TBth when the vehicle is turning is set to a smaller value compared to the braking threshold time TBth when the vehicle is not turning.

[0092] (2) If the vehicle is turning, and the target threshold recognition time Trth is not reached relative to the continuous recognition time Trcg, the "collision avoidance control activated because the collision avoidance threshold TTCth is below the collision avoidance threshold TTCth" will not be started (executed).

[0093] (Specific actions)

[0094] The DSECU's CPU (hereinafter referred to as "CPU") executes at specified intervals. Figure 4 The example shown in the flowchart is a routine used for the aforementioned alarm control as a collision avoidance control. However, an equivalent routine can also be used to perform the aforementioned automatic braking control as a collision avoidance control.

[0095] If it becomes a specified time, then the CPU will... Figure 4 Step 400 is processed and proceeds to step 405, where the value of the PCS operation flag XPCS is determined to be "0". This flag XPCS indicates that collision avoidance control (in this case, alarm control) is not activated when its value is "0", and that collision avoidance control is activated when its value is "1" (see step 440 described later). Therefore, in step 405, the CPU determines whether the state of the vehicle SV is that collision avoidance control is not activated. Furthermore, in the initialization routine executed by the CPU when the ignition key switch (not shown) of the vehicle SV is moved from the off position to the on position, the flag XPCS is set to "0".

[0096] Now, assuming the value of the flag XPCS is "0", the CPU determines "yes" in step 405 and executes the processes described below in steps 410 and 415, proceeding to step 420.

[0097] Step 410: The CPU obtains integrated target information from the target sensor device 40 (target detection ECU 43).

[0098] Step 415: The CPU obtains the vehicle's action information from the "vehicle status sensor 50 and driving operation status sensor 60".

[0099] After the CPU enters step 420, it uses the vehicle's motion information to estimate (obtain) the area the vehicle has passed through, and uses the vehicle's motion information and integrated target information to estimate (obtain) the areas the other vehicles have passed through.

[0100] <<Estimated Area Through which This Vehicle Passed>>

[0101] The DSECU determines the turning radius R1 and turning center point of the vehicle's SV at the current time point based on the vehicle's yaw rate Yr, lateral acceleration Gy, vehicle speed SPD, and steering angle θ. Then, as... Figure 2 As shown in Case A, the DSECU, assuming that the vehicle SV maintains its current state while driving during a certain estimated period of time, determines the center movement path SC of the front center of the vehicle SV during the estimated period based on the turning radius R1 and the turning center point.

[0102] Next, the DSECU calculates the line obtained by moving the center movement path SC a distance d to the left in the vehicle width direction (strictly speaking, if the vehicle SV is turning right, it is an arc with a radius of (R1+d) from the center of the turn; if the vehicle SV is turning left, it is an arc with a radius of (R1-d) from the center of the turn) as the left front end movement path SL. Similarly, the DSECU calculates the line obtained by moving the center movement path SC a distance d to the right in the vehicle width direction (strictly speaking, if the vehicle SV is turning right, it is an arc with a radius of (R1-d) from the center of the turn; if the vehicle SV is turning left, it is an arc with a radius of (R1+d) from the center of the turn) as the right front end movement path SR. Based on the above, the strip-shaped passage area SP of the vehicle determined by the left front end movement path SL and the right front end movement path SR is estimated. In addition, the distance d is a value obtained by adding a specified margin Mg to half of the width (W) of the vehicle SV (=(W / 2)+Mg). However, the margin Mg can also be "0".

[0103] <<Presumption of Areas Passed Through by Other Vehicles>>

[0104] The DSECU uses the "integrated target information" of other vehicles' current and past time points and the "vehicle action information" of its own vehicle (SV)'s current and past time points to determine the turning radius R2 and turning center point of other vehicles' PVs at the current time point. Then, assuming that the other vehicles' PVs are maintaining their current state while driving during the estimated period, the DSECU determines the center movement path PC that the front center of the other vehicles' PVs should move during the estimated period based on the turning radius R2 and turning center point.

[0105] Next, the DSECU calculates the line obtained by moving the center movement path PC a distance dp to the left of the other vehicle PV in the width direction (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 calculates the line obtained by moving the center movement path PC a distance dp to the right of the other vehicle PV in the width direction (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 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 the strip-shaped area defined by these two extended paths is presumed as the other vehicle passage area PP. Furthermore, the distance dp is a value obtained by adding a specified margin Mgp to half the width (Wp) of other vehicles' PVs (=(Wp / 2)+Mgp). However, the margin Mgp can also be "0". Even if the detected target is a target other than a vehicle, the DSECU estimates the target's passage area as the target passage area using essentially the same method as described above.

[0106] In step 420, the CPU determines whether the vehicle's passage area SP intersects with other vehicle passage areas (target passage areas) PP. In other words, the CPU determines whether there exists a target (i.e., the target to be controlled) that intersects with the vehicle's passage area SP in another vehicle passage area PP. If no target to be controlled exists, the CPU determines "no" in step 420 and directly proceeds to step 495, temporarily ending the current routine. Therefore, in this case, the alarm control as a collision avoidance control is not executed.

[0107] In contrast, if there is a target object to be controlled, the CPU determines "yes" in step 420 and proceeds to step 425.

[0108] In step 425, the CPU determines whether the vehicle SV is turning. More specifically, the CPU determines whether the turning radius R1 calculated in step 420 to estimate that the vehicle has passed through area SP is below a predetermined threshold radius (R1th). Furthermore, the determination of whether the vehicle SV is turning can also be performed using other methods. For example, the CPU can also determine that the vehicle SV is turning when any one or more of the yaw rate Yr, lateral acceleration Gy, and steering angle θ are above their respective turning thresholds.

[0109] If the vehicle is not turning (i.e., if the turning radius R1 is larger than the threshold radius R1th), the CPU determines "no" in step 425 and proceeds to step 430.

[0110] In step 430, the CPU sets the collision avoidance threshold TTCth (in this example, the alarm threshold time TWth) to the straight-ahead threshold time Tlong, and proceeds to step 435.

[0111] In step 435, the CPU calculates the "time required for collision with the controlled target (TTC)". Furthermore, the CPU determines whether the "time required for collision with the controlled target (TTC)" is below the collision avoidance threshold TTCth (in this example, the alarm threshold time TWth). If the "time required for collision with the controlled target (TTC)" is greater than the collision avoidance threshold TTCth, the CPU determines "no" in step 435 and directly proceeds to step 495, temporarily ending the current routine. Therefore, in this case, alarm control as a collision avoidance control is not executed.

[0112] Conversely, if the "Time To Call Collision to Controlled Object (TTC)" is below the collision avoidance threshold TTCth, the CPU determines "Yes" in step 435 and proceeds to steps 440 and 445 as described below. Afterward, the CPU enters step 495 and temporarily terminates the routine.

[0113] Step 440: The CPU sets the value of the XPCS flag to "1".

[0114] Step 445: The CPU executes the aforementioned alarm control as a collision avoidance control mechanism. That is, the CPU sends a display command to the instrument cluster ECU 20 and a beep command to the sound-emitting device 70.

[0115] Additionally, if the vehicle is turning when the CPU enters step 425 (i.e., if the turning radius R1 calculated to estimate that the vehicle has passed through area SP is below the threshold radius R1th), the CPU determines "yes" in step 425 and proceeds to step 450.

[0116] In step 450, the CPU sets the collision avoidance threshold TTCth (in this example, the alarm 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.

[0117] In step 455, the CPU determines whether the continuous recognition time Trcg of the controlled object target is greater than or equal to the threshold recognition time Trth.

[0118] When the continuous recognition time Trcg is shorter than the threshold recognition time Trth, the CPU determines "No" in step 455 and directly proceeds to step 495 to temporarily end this routine. Thus, in this case (Trcg < Trth), the alarm control as the anti-collision control is not started (is prohibited).

[0119] In contrast, when the continuous recognition time Trcg is equal to or longer than the threshold recognition time Trth, the CPU determines "Yes" in step 455 and proceeds to step 435. Therefore, if the "time to collision TTC of the control target object" is below the anti-collision threshold TTCth (in this example, the alarm threshold time TWth set to the threshold time Tshort during turning), the CPU executes the anti-collision control (alarm control) by sequentially executing the above-mentioned processes of "step 440 and step 445". After that, the CPU proceeds to step 495 to temporarily end this routine.

[0120] As described above, when it is determined that the own vehicle SV is turning, when the continuous recognition time Trcg of the control target object is less than the threshold recognition time Trth, for example, even if it is assumed that the time to collision TTC is below the "anti-collision threshold TTCth set to a smaller value compared to when not turning", the anti-collision control does not start. Moreover, when the continuous recognition time Trcg of the control target object is equal to or longer than the threshold recognition time Trth, the timing of starting the anti-collision control is substantially delayed compared to the case where the own vehicle SV is not turning. Through the above, it is possible to reduce "the possibility of unnecessarily executing the anti-collision control when the own vehicle SV turns right (or left) at an intersection".

[0121] In addition, the DSECU can execute the automatic braking control as the anti-collision control as follows.

[0122] · The CPU sets the anti-collision threshold TTCth to the "straight-ahead threshold time Tlongbk for automatic braking" in step 430. In addition, the straight-ahead threshold time Tlongbk is shorter than the straight-ahead threshold time Tlong.

[0123] · The CPU sets the anti-collision threshold TTCth to the "turning threshold time Tshortbk for automatic braking" in step 450. The turning threshold time Tshortbk is shorter than the straight-ahead threshold time Tlongbk. In addition, the turning threshold time Tshortbk is shorter than the turning threshold time Tshort.

[0124] · The CPU executes the above-mentioned automatic braking control in step 445. That is, the CPU sends an automatic braking command to the brake ECU 30.

[0125] (Variant Example 1)

[0126] The first modification example of the collision avoidance assist device 1 differs from the collision avoidance assist device 1 only in that the collision avoidance threshold TTCth is changed corresponding to the overlap ratio LR.

[0127] The CPU of the DSECU in the first modification example (hereinafter simply referred to as "CPU1") executes, every predetermined time, a routine Figure 4 instead of Figure 5 shown by the flowchart in. This routine is a routine for performing the above-described warning control as collision avoidance control. However, a routine equivalent to this routine can also be used to execute the above-described automatic braking control as collision avoidance control.

[0128] Figure 5 The routine shown only differs from the routine shown in that step 430 is replaced with step 530, step 450 is replaced with step 550, and step 570 is added to Figure 4 the routine shown in. Hereinafter, the description will be centered on these differences. Figure 4 shown in.

[0129] When the host vehicle SV is not turning, the CPU1 determines "No" in step 425 and proceeds to step 530. In step 530, the CPU1 sets the collision avoidance reference threshold TTCbth (in this example, the warning reference threshold time TWbth) to the straight-ahead threshold time Tlong, and proceeds to step 570.

[0130] On the other hand, when the host vehicle SV is turning, the CPU1 determines "Yes" in step 425 and proceeds to step 550. In step 550, the CPU1 sets the collision avoidance reference threshold TTCbth (in this example, the warning reference threshold time TWbth) to "the turning threshold time Tshort shorter than the straight-ahead threshold time Tlong". Then, the CPU proceeds to step 455.

[0131] When the continuous recognition time Trcg is shorter than the threshold recognition time Trth, the CPU determines "No" in step 455 and directly proceeds to step 495 to temporarily end this routine. Thus, 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.

[0132] On the other hand, when the continuous recognition time Trcg is equal to or longer than the threshold recognition time Trth, the CPU determines "Yes" in step 455 and proceeds to step 570.

[0133] In step 570, the CPU1 calculates the above-described overlap ratio LR, and calculates the value of the above-described function f(LR) based on the overlap ratio LR (see Figure 5(The curve in the box). Furthermore, as mentioned above, the overlap ratio LR is a value representing the degree of overlap between the vehicle SV and the controlled target OV during collision (LR = LL / (2·d)) (refer to...). Figure 6 Furthermore, CPU1 determines the collision avoidance threshold TTCth (which is the alarm threshold time TWth in this case) by multiplying the value of the function f(LR) by the collision avoidance baseline threshold TTCbth (which is the alarm baseline threshold time TWbth in this example).

[0134] Therefore, the collision avoidance threshold TTCth (which is the warning threshold time TWth in this case) when the overlap ratio LR is an arbitrary value LR1 becomes smaller compared to when the vehicle SV is not turning. Thus, the likelihood of performing unnecessary collision avoidance controls is reduced.

[0135] (Variation Example 2)

[0136] The variation 2 of the collision avoidance assist device 1 differs from the collision avoidance assist device 1 only in that it obtains the vehicle's movement information used to estimate the vehicle's passage through the area SP and / or the vehicle's movement information used to determine whether the vehicle SV is turning from a device outside the vehicle SV via the communication device 80. Therefore, it is possible to estimate the vehicle's passage through the area SP with high accuracy and to determine whether the vehicle SV is turning with high accuracy.

[0137] As explained above, according to the embodiments and modifications of the present invention, the possibility of performing unnecessary collision avoidance control when the vehicle is making a SV turn can be reduced. The present invention is not limited to the above embodiments and modifications, and various modifications can be further employed within the scope of the present invention.

[0138] For example, the collision avoidance assist device 1 can also obtain information about other targets existing in front of or around the vehicle SV via the communication device 80. This information, in addition to the target information obtained by the target sensor device 40, can also be used for collision avoidance control.

[0139] The collision avoidance assist device 1 can also execute either alarm control or automatic braking control as collision avoidance control, or it can execute PCS control other than alarm control and automatic braking control in place of alarm control and automatic braking control, or execute PCS control in addition to alarm control and automatic braking control. Representative examples of PCS control other than alarm control and automatic braking control are seat belt wrapping control and collision avoidance steering control.

[0140] In embodiments and variations of the present invention, when the vehicle is turning, collision avoidance control is not initiated "because the collision avoidance threshold TTCth is below the collision avoidance threshold TTCth" for targets whose continuous recognition time Trcg has not reached the threshold recognition time Trth. However, collision avoidance control may also be performed if other conditions for the target are met, in addition to the collision avoidance threshold TTCth being below the collision avoidance threshold TTCth.

[0141] Explanation of reference signs

[0142] 1… Collision avoidance assist device, 10… Driving assistance ECU (DSECU), 40… Target sensor device, 41… Radar sensor, 42… Camera sensor, 43… Target detection ECU, 50… Vehicle status sensor, 60… Driving operation status sensor, 70… Sound device.

Claims

1. A collision avoidance auxiliary device, comprising: The target sensor device detects targets present in front of the vehicle and outputs target information containing information related to the position of the detected target; The information acquisition device acquires vehicle action information representing the actions of the vehicle. as well as The control unit, upon determining, based on the target information and the vehicle's motion information, that there exists a controlled target that the vehicle may collide with, generates a collision index value representing the probability of a collision between the vehicle and the controlled target, at least based on the target information related to the controlled target. When the collision index value meets predetermined control initiation conditions, the control unit uses the vehicle's actuators to initiate collision avoidance control to prevent a collision between the vehicle and the controlled target. The control unit is configured as follows: If, based on the vehicle's motion information, it is determined that the vehicle is turning, and the duration for which the target sensor continuously detects the controlled object (i.e., the continuous identification time) is shorter than a predetermined threshold identification time, the collision avoidance control that was executed when the collision index value met the control initiation condition will not begin. If, based on the vehicle's motion information, it is determined that the vehicle is turning, the control initiation condition is modified so that it is more difficult to meet the control initiation condition compared to when, based on the vehicle's motion information, it is determined that the vehicle is not turning. If, based on the vehicle's motion information, it is determined that the vehicle is not turning, the collision avoidance control is initiated when the collision index value meets the control initiation condition, without relying on the continuous recognition time. The control unit is also configured to, The time required until the vehicle collides with the controlled object is calculated, i.e., the collision time, and is used as the collision index value. If the time required for a collision is determined to be less than the collision avoidance threshold, then the control start condition is deemed to be met. If, based on the vehicle's motion information, it is determined that the vehicle is turning, the control start condition is changed so that, compared to the case where, based on the vehicle's motion information, it is determined that the vehicle is not turning, the control start condition is made more difficult to meet by setting the collision avoidance threshold to a value smaller than the time required for a collision, and the timing delay of the collision avoidance control start is increased when the vehicle is turning compared to the case where the vehicle is not turning.

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