Collision avoidance assistance device

Abstract

The present application relates to a collision avoidance support device. A drive support ECU implements automatic brake control in a case where a collision avoidance object is a pedestrian or a bicycle. In this case, accelerator override is not possible. In a case where the collision avoidance object is a motor vehicle, if an accelerator operation amount AP is equal to or greater than a first operation amount threshold value AP1, the drive support ECU prohibits implementation of the automatic brake control. In this case, accelerator override is possible. If the accelerator operation amount AP is less than the first operation amount threshold value AP1, the drive support ECU implements the automatic brake control.

Description

[0001] This application is a divisional application of patent application 202010882631.6, filed in the China Patent Office on August 28, 2020 and entitled "Collision Avoidance Support Device". TECHNICAL FIELD

[0002] The present application relates to a collision avoidance support device that implements automatic brake control to avoid a collision of a host vehicle with an obstacle. BACKGROUND

[0003] There is known a collision avoidance support device that implements automatic brake control to avoid a collision of a host vehicle with an obstacle in a case where an obstacle is detected by a front sensor such as a camera sensor and a radar sensor as a high possibility of collision of the host vehicle with the obstacle. The automatic brake control is control that causes the host vehicle to generate a braking force without a brake operation by a driver so as to decelerate the host vehicle at a predetermined deceleration.

[0004] Sometimes, a driver performs a depression operation of an accelerator pedal while the automatic brake control is being implemented. For example, a device proposed in Japanese Patent Application Publication No. 2017-114430 implements the automatic brake control in a case where it is predicted that the host vehicle will collide with an obstacle, but gives priority to an accelerator operation by the driver and cancels the automatic brake control (that is, prohibits implementation of the automatic brake control) in a case where an accelerator operation amount by the driver becomes larger than a predetermined value. Thereby, it is possible to accelerate the host vehicle at an acceleration corresponding to the accelerator operation. Hereinafter, the cancellation of the automatic brake control and the acceleration of the host vehicle at the acceleration corresponding to the accelerator operation will be referred to as accelerator override.

[0005] The device is configured to, in a case where a gear change operation is detected while the driver is performing the accelerator operation, presume that the accelerator operation is caused by a misoperation by the driver and not cancel the automatic brake control. Therefore, in this case, the accelerator override cannot be performed.

[0006] In addition, a device proposed in Japanese Patent Application Publication No. 2012-121534 determines whether an operation by the driver is a proper collision avoidance operation or a misoperation, does not implement the automatic brake control in a case where it is determined that the operation is the proper collision avoidance operation, and implements the automatic brake control in a case where it is determined that the operation is the misoperation. The device determines that the accelerator operation by the driver is the misoperation in a case where it is predicted that the host vehicle will collide with an obstacle, a case where an accelerator operation amount is larger than a predetermined value, or a case where an accelerator operation speed is larger than a predetermined value, and implements the automatic brake control. SUMMARY

[0007] All of the above-described devices make the automatic brake control not be canceled (that is, implement the automatic brake control) in a case where the accelerator operation presumed to be that of the driver is an operation that is against the intention of the driver (an operation of mistakenly stepping on the accelerator pedal when intending to step on the brake pedal). Hereinafter, the operation of the driver of mistakenly stepping on the accelerator pedal when intending to step on the brake pedal is referred to as a mistaken stepping operation.

[0008] However, it is difficult to accurately determine whether the accelerator operation by the driver is an operation by the intention of the driver or a mistaken stepping operation.

[0009] For example, the device proposed in Japanese Patent Application Publication No. 2017-114430 determines the accelerator stepping operation accompanying a gear change operation as a mistaken stepping operation, but even in a case where a gear change operation is not performed, a case where the driver mistakenly steps on the accelerator pedal greatly can be imagined. For example, in a situation where the host vehicle is approaching a pedestrian, the driver does not normally step on the accelerator pedal greatly, but in a case where the driver is anxious due to a delay in the detection of the pedestrian, a case where the driver intends to step on the brake pedal but mistakenly steps on the accelerator pedal greatly can be imagined. In this case, since a gear change operation is not performed, the accelerator stepping operation is not determined as a mistaken stepping operation. Thus, even in a situation where the automatic brake control for collision avoidance should be implemented, the automatic brake control is not implemented.

[0010] For example, the device proposed in Japanese Patent Application Publication No. 2012-121534 determines the accelerator operation as a mistaken stepping operation in a case where the accelerator operation amount is greater than a predetermined value or in a case where the accelerator operation speed is greater than a predetermined value. However, in a case where the driver intentionally steps on the accelerator pedal greatly or quickly, the accelerator operation by the driver is determined as a mistaken stepping operation, and the automatic brake control is implemented. For example, as shown in FIG. 1, in a case where the driver intends to overtake a preceding vehicle C2 traveling in front of the host vehicle C1 and accelerate the host vehicle C1, the preceding vehicle C2 is sometimes determined as an obstacle due to the quick approach of the host vehicle C1 to the preceding vehicle C2 during the process, and the automatic brake control is implemented. If the automatic brake control starts, the accelerator override cannot be performed, and thus the host vehicle cannot be made to travel in a trajectory desired by the driver. In addition, the following vehicle can excessively approach the host vehicle due to the implementation of the automatic brake control. Figure 6

[0011] The present application provides a technique of implementing the automatic brake control in an appropriate situation.

[0012] ​The collision avoidance support device of the aspect of the present invention includes: a braking device that causes the host vehicle to generate a braking force corresponding to a brake operation by a driver; an obstacle detection unit that detects an obstacle present in the vicinity of the host vehicle; an automatic braking control unit that, in a case where it is determined that there is a high possibility that the host vehicle will collide with the obstacle, implements automatic braking control for causing the braking device to generate a braking force in a manner that does not require a brake operation by the driver so as to avoid the host vehicle from colliding with the obstacle; and an automatic braking prohibition unit that, in a case where it is determined that an accelerator operation index value that is correlated with an accelerator operation by the driver is equal to or greater than an operation threshold value, prohibits implementation of the automatic braking control, wherein the collision avoidance support device includes: a specific type determination unit that determines whether or not a type of the obstacle is a specific type that is set in advance; and a restriction unit that, in a case where it is determined that the type of the obstacle is the specific type, restricts the operation of the automatic braking prohibition unit so that the automatic braking prohibition unit does not prohibit implementation of the automatic braking control.

[0013] The collision avoidance support device includes a braking device, an obstacle detection unit, an automatic braking control unit, and an automatic braking prohibition unit. The braking device causes the host vehicle to generate a braking force (e.g., a braking torque that stops the rotation of a wheel) corresponding to a brake operation by a driver. For example, the braking device can generate a braking force corresponding to a brake operation by means of brake hydraulic pressure.

[0014] The obstacle detection unit detects an obstacle present in the vicinity of the host vehicle.

[0015] The automatic braking control unit, in a case where it is determined that there is a high possibility that the host vehicle will collide with the obstacle, implements automatic braking control for causing the braking device to generate a braking force in a manner that does not require a brake operation by the driver so as to avoid the host vehicle from colliding with the obstacle.

[0016] The automatic braking prohibition unit, in a case where it is determined that an accelerator operation index value that is correlated with an accelerator operation by the driver is equal to or greater than an operation threshold value, prohibits implementation of the automatic braking control. The accelerator operation index value can be, for example, at least one of an accelerator operation amount (e.g., an accelerator opening degree) and an accelerator operation speed. In a case where implementation of the automatic braking control is prohibited by the automatic braking prohibition unit, if the automatic braking control is implemented, the automatic braking control is ended, if the automatic braking control is not implemented, the start of the automatic braking control is prohibited.

[0017] Thus, for example, in a case where the driver intentionally performs a large accelerator operation in order to avoid the obstacle, the automatic braking control is no longer implemented, and collision avoidance can be performed while accelerating the host vehicle in accordance with the intention of the driver by means of accelerator override.

[0018] However, accelerator operation is not necessarily performed as the driver intends. For example, if the host vehicle is approaching a traffic weak person such as a pedestrian or a bicycle driver, the driver does not usually perform a large accelerator operation. Therefore, in a case where a large accelerator operation is detected in such a situation, it can be presumed that the driver performed a misstep operation, and the accelerator override is prohibited.

[0019] Therefore, in the present application, a specific type determination unit and a restriction unit are provided. The specific type determination unit determines whether the type of the obstacle is a specific type that is set in advance. The restriction unit restricts the operation of the automatic brake prohibition unit (deactivates the automatic brake prohibition unit) so that the automatic brake control is not prohibited by the automatic brake prohibition unit, in a case where it is determined that the type of the obstacle is the specific type. Thus, the automatic brake control unit no longer prohibits the implementation of the automatic brake control.

[0020] As a result, according to the present application, since it is determined whether to prohibit the implementation of the automatic brake control depending on the type of the obstacle, the automatic brake control can be implemented in an appropriate situation.

[0021] The automatic brake control unit recognizes at least a pedestrian, a bicycle, and a motor vehicle as obstacles that are set as targets of the implementation of the automatic brake control, and the specific type determination unit can be configured to determine at least the pedestrian and the bicycle as obstacles of the specific type and at least the motor vehicle as an obstacle that is not of the specific type.

[0022] According to this configuration, the automatic brake control unit recognizes at least a pedestrian, a bicycle, and a motor vehicle as obstacles that are set as targets of the implementation of the automatic brake control.

[0023] If the host vehicle is approaching a pedestrian or a bicycle, the driver does not usually perform a large accelerator operation. On the other hand, in a situation where the host vehicle is approaching another vehicle, the driver sometimes intentionally performs a large accelerator operation. For example, it is conceivable that the driver accelerates the host vehicle in order to overtake a preceding vehicle that is traveling in front of the host vehicle. In such a case, the preceding vehicle is sometimes determined to be an obstacle due to the rapid approach of the host vehicle to the preceding vehicle during the overtaking process, and the automatic brake control is started. In this case, the following vehicle can excessively approach the host vehicle due to the implementation of the automatic brake control.

[0024] Therefore, the specific type determination unit determines at least a pedestrian and a bicycle as obstacles of the specific type and at least a motor vehicle as an obstacle that is not of the specific type. In this case, the "bicycle" can be a bicycle that the driver rides, and as for a bicycle that is placed on a road (a bicycle that the driver does not ride), it can not be set as an obstacle that is a target of collision avoidance.

[0025] Thus, in a case where the obstacle is a pedestrian or a bicycle, implementation of the automatic brake control is not prohibited. That is, implementation of the automatic brake control is permitted. Therefore, in a case where the possibility of collision with the pedestrian or the bicycle is high, even if the driver erroneously steps on the accelerator pedal greatly, the accelerator operation is set to be invalid, and the automatic brake control is implemented. Thus, collision avoidance assistance can be favorably performed.

[0026] On the other hand, in a case where the obstacle is a motor vehicle, the specific category determination unit determines that the obstacle is not a specific category obstacle. Thus, in a case where the accelerator operation index value is equal to or greater than the operation threshold value, implementation of the automatic brake control is prohibited. Therefore, accelerator override can be performed, and the driver can perform collision avoidance by his or her own operation.

[0027] The accelerator operation can be an operation of an accelerator pedal of the host vehicle. The collision avoidance assistance device can include a re-stamping determination unit that determines whether a re-stamping operation of the accelerator pedal is performed in the implementation of the automatic brake control, and a re-stamping time control end unit that causes the automatic brake control unit to end the automatic brake control in a case where the re-stamping determination unit determines that the re-stamping operation of the accelerator pedal is performed in the implementation of the automatic brake control.

[0028] In a case where the driver performs a re-stamping operation of the accelerator pedal (an operation of moving a foot from a stepped-on accelerator pedal and then stepping on the accelerator pedal again) in the implementation of the automatic brake control, it can be presumed that the operation is an operation in accordance with the driver's intention to accelerate the host vehicle. In this case, accelerator override can be enabled.

[0029] Thus, the re-stamping determination unit can determine whether a re-stamping operation of the accelerator pedal is performed in the implementation of the automatic brake control. The re-stamping time control end unit can cause the automatic brake control unit to end the automatic brake control in a case where the re-stamping determination unit determines that the re-stamping operation of the accelerator pedal is performed in the implementation of the automatic brake control.

[0030] Therefore, according to this structure, in a situation where the driver intends to accelerate the host vehicle, the automatic brake control can be caused not to be implemented.

[0031] The accelerator operation is an operation of an accelerator pedal of the host vehicle, and the automatic brake prohibition unit can be configured to acquire an accelerator pedal operation amount and an accelerator pedal operation speed of the driver as the accelerator operation index value, and determine that the accelerator operation index value is the operation threshold value or more in a case where a condition of at least one of a first condition and a second condition is established, the first condition being that the accelerator pedal operation amount is a first operation amount threshold value or more, and the second condition being that the accelerator pedal operation amount is a second operation amount threshold value or more that is less than the first operation amount threshold value and the accelerator pedal operation speed is an operation speed threshold value or more.

[0032] According to this structure, the accelerator pedal operation condition in which the implementation of the automatic brake control is prohibited can be appropriately set. Thus, the case where the automatic brake control is implemented due to the accelerator pedal operation in accordance with the driver's own idea can be reduced. BRIEF DESCRIPTION OF DRAWINGS

[0033] The features, advantages, and technical and industrial significance of exemplary embodiments of the application will be described in the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which like numerals denote like elements, and wherein:

[0034] Figure 1 is a schematic configuration view of a collision avoidance support device of an embodiment of the application.

[0035] Figure 2 is a flowchart showing an automatic brake permission / prohibition switching control routine.

[0036] Figure 3 is a flowchart showing a modification example 1 of the automatic brake permission / prohibition switching control routine.

[0037] Figure 4 is a flowchart showing a modification example 2 of the automatic brake permission / prohibition switching control routine.

[0038] Figure 5 is a flowchart showing a modification example 3 of the automatic brake permission / prohibition switching control routine.

[0039] Figure 6 is a plan view showing a situation in which the host vehicle approaches and overtakes a vehicle traveling ahead. DETAILED DESCRIPTION

[0040] Hereinafter, with reference to the accompanying drawings, a collision avoidance support device of an embodiment of the application will be described. Figure 1

[0041] The collision avoidance support device of the embodiment of the application is applied to a vehicle (hereinafter, referred to as "host vehicle" in order to distinguish from other vehicles) such as an automobile. Figure 1 ​As shown, the vehicle is provided with a drive assist ECU 10, a brake ECU 20, an engine ECU 30, and an instrument ECU 40.

[0042] These ECUs are electric control units (ECUs) each of which is provided with a microcomputer as a main part, and are connected to each other via a CAN (Controller Area Network) not shown so as to be able to transmit and receive information to and from each other. In the present specification, the microcomputer includes a CPU, a ROM, a RAM, a nonvolatile memory, an interface I / F, and the like. The CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. These ECUs can also be integrated into one ECU in some or all of them.

[0043] The drive assist ECU 10 is a control device that becomes the center of driving support for the driver, and implements collision avoidance support control. The collision avoidance support control is control that, in the case where an obstacle is detected in front of the host vehicle, arouses the driver's attention, and in the case where the possibility of collision further increases, avoids collision of the host vehicle with the obstacle by automatic brake control. The collision avoidance support control is generally called PCS control (Pre-Crash Safety control), and therefore, the collision avoidance support control will be referred to as PCS control hereinafter.

[0044] The drive assist ECU 10 is connected to a front camera sensor 50, a front radar sensor 60, a vehicle state sensor 70, an operation state sensor 80, and a buzzer 90.

[0045] The front camera sensor 50 is disposed at the upper portion of the front window in the vehicle cabin, and captures the scenery in front of the host vehicle. The front camera sensor 50 recognizes the white line of the road and the three-dimensional object present in front of the host vehicle on the basis of the captured image, and supplies the information thereof (white line information, three-dimensional object information) to the drive assist ECU 10 at a predetermined cycle. The white line information is information indicating the shape of the white line, the relative positional relationship of the host vehicle to the white line, and the like. The three-dimensional object information is information indicating the kind of the three-dimensional object detected in front of the host vehicle, the size of the three-dimensional object, the relative positional relationship of the three-dimensional object to the host vehicle, and the like. Furthermore, the recognition of the kind of the three-dimensional object is realized by, for example, machine learning such as pattern matching.

[0046] The front radar sensor 60 is provided at a front central portion of the vehicle body and detects a three-dimensional object present in a front region of the host vehicle. The front radar sensor 60 radiates an electric wave in a millimeter wave band (hereinafter referred to as "millimeter wave") and receives a millimeter wave (i.e., reflected wave) reflected by a three-dimensional object (e.g., other vehicle, pedestrian, bicycle, structure, etc.) present in a radiating range. The front radar sensor 60 calculates a distance between the host vehicle and the three-dimensional object, a relative speed between the host vehicle and the three-dimensional object, a relative position (direction) of the three-dimensional object with respect to the host vehicle, etc., based on a phase difference between the transmitted millimeter wave and the received reflected wave, an attenuation level of the reflected wave, a time from the transmission of the millimeter wave to the reception of the reflected wave, etc., and supplies information (three-dimensional object information) indicating these calculation results to the driving support ECU 10 at a predetermined cycle.

[0047] The driving support ECU 10 synthesizes the three-dimensional object information supplied from the front camera sensor 50 and the three-dimensional object information supplied from the front radar sensor 60 to obtain three-dimensional object information with high precision.

[0048] Hereinafter, the front camera sensor 50 and the front radar sensor 60 will be collectively referred to as front sensor, and information about the front of the host vehicle obtained from the front camera sensor 50 and the front radar sensor 60 will be referred to as front sensor information.

[0049] The vehicle state sensor 70 is, for example, a vehicle speed sensor that detects a travel speed of the vehicle, a front-rear acceleration sensor that detects a front-rear direction acceleration of the vehicle, a lateral acceleration sensor that detects a lateral direction acceleration of the vehicle, a yaw rate sensor that detects a yaw rate of the vehicle, etc.

[0050] The operation state sensor 80 is a sensor or switch that detects an operation performed by the driver. The operation state sensor 80 is, for example, an accelerator operation amount sensor that detects an operation amount of an accelerator pedal, a brake operation amount sensor that detects an operation amount of a brake pedal, a brake switch that detects the presence or absence of an operation of the brake pedal, a steering angle sensor that detects a steering angle, a steering torque sensor that detects a steering torque, a gear position sensor that detects a gear position of a transmission, etc.

[0051] Information detected by the vehicle state sensor 70 and the operation state sensor 80 (referred to as sensor information) is supplied to the driving support ECU 10 at a predetermined cycle via a CAN not shown.

[0052] The buzzer 90 sounds in accordance with an instruction from the driving support ECU 10. The driving support ECU 10 causes the buzzer 90 to sound by sending a sound instruction to the buzzer 90 in a case where attention is to be called to the driver. Thus, attention calling to the driver can be performed.

[0053] The brake ECU 20 is connected to a brake actuator 21. The brake actuator 21 is provided in a hydraulic circuit between a master cylinder, not shown, which pressurizes working oil by a depression force of a brake pedal, and friction brake mechanisms 22 provided to the front and rear wheels. The friction brake mechanisms 22 are provided with brake discs 22a fixed to the wheels and brake calipers 22b fixed to the vehicle body. The brake actuator 21 adjusts hydraulic pressure supplied to wheel cylinders built in the brake calipers 22b in accordance with an instruction from the brake ECU 20, and generates a friction braking force by working the wheel cylinders using the hydraulic pressure to press brake pads against the brake discs 22a. The brake ECU 20 sets a driver required deceleration based on an operation amount of the brake pedal detected by a brake operation amount sensor, and controls the operation of the brake actuator 21 so that the host vehicle decelerates at the driver required deceleration. In addition, the brake ECU 20 controls the operation of the brake actuator 21 so that the host vehicle decelerates at a PCS required deceleration included in the PCS brake instruction when the PCS brake instruction is received from the drive assist ECU 10.

[0054] Further, the brake ECU 20 adopts a required deceleration of which absolute value is larger between the driver required deceleration and the PCS required deceleration as a final required deceleration when the PCS brake instruction is being received and the brake pedal is operated. The brake ECU 20 controls the operation of the brake actuator 21 so that the host vehicle decelerates at the final required deceleration. That is, the brake ECU 20 implements brake override.

[0055] The engine ECU 30 is connected to an engine actuator 31. The engine actuator 31 is an actuator for changing an operation state of an engine 32 (internal combustion engine), and includes, for example, a throttle actuator which changes an opening degree of a throttle valve. The engine ECU 30 sets a driver required torque based on an accelerator pedal operation amount detected by an accelerator operation amount sensor and a vehicle speed detected by a vehicle speed sensor, and controls the operation of the engine actuator 31 so that the engine 32 outputs the driver required torque. In addition, the engine ECU 30 controls the operation of the engine actuator 31 so as to limit an output torque generated by the engine 32 when a drive power limitation instruction is received from the drive assist ECU 10. Further, in the case where the vehicle is an electric motor vehicle, the engine actuator 31 is a drive device of an electric motor, and in the case where the vehicle is a hybrid vehicle, the engine actuator 31 is a drive device of the above-described engine actuator and electric motor.

[0056] The instrument ECU 40 is connected to the display 41 and the stop lamp 42. The instrument ECU 40 is capable of causing the display 41 to display a display related to the driving support in accordance with an instruction from the driving support ECU 10. In addition, the instrument ECU 40 is capable of causing the stop lamp 42 to be lit in accordance with an instruction from the driving support ECU 10 or the brake ECU 20.

[0057] <PCS control>

[0058] Next, the PCS control will be described. The driving support ECU 10, if looking at its function, is provided with a collision determination section 11, an informing section 12, an automatic brake control section 13, a prohibition section 14, a prohibition restriction section 15, and a specific kind determination section 16.

[0059] The collision determination section 11 determines whether or not the host vehicle will collide with a three-dimensional object ahead based on the front sensor information supplied from the front sensor and the vehicle state detected by the vehicle state sensor 70. For example, the collision determination section 11 determines whether or not the possibility of collision of the host vehicle with a three-dimensional object is high in the case where the three-dimensional object maintains a moving state (in the case where the three-dimensional object is a stationary object, a stopped state) as it is and the host vehicle maintains a running state as it is. The collision determination section 11 recognizes the three-dimensional object as an obstacle in the case where it is determined based on the determination result that the possibility of collision of the host vehicle with the three-dimensional object is high.

[0060] However, the collision determination section 11 limits to the case where the kind of the three-dimensional object is a pedestrian, a bicycle, and a motor vehicle, and sets them as the object of collision avoidance (the object of implementation of the automatic brake control). The "bicycle" is a bicycle ridden by a driver, and does not include a bicycle placed on a road (a bicycle not ridden by a driver). Therefore, the front camera sensor 50 is only required to be able to detect at least the pedestrian, the bicycle, and the motor vehicle existing in the three-dimensional object ahead of the host vehicle in such a manner as to recognize the kind thereof.

[0061] The collision determination section 11 determines whether or not the possibility of collision with the host vehicle is high with the three kinds (the pedestrian, the bicycle, and the motor vehicle) as the object, and recognizes them as obstacles in the case where the possibility of collision is high. On the other hand, with respect to a three-dimensional object different from the three kinds, the collision determination section 11 does not set as the object of collision avoidance, and thus does not recognize as an obstacle. Hereinafter, the pedestrian, the bicycle, and the motor vehicle will be referred to as the collision avoidance object.

[0062] More specifically, the collision determination section 11, in the case where an obstacle is detected, calculates a prediction time until the host vehicle collides with the obstacle, that is, a collision prediction time TTC. The collision prediction time TTC is calculated based on the distance d between the obstacle and the host vehicle and the relative speed Vr of the host vehicle with respect to the obstacle by the following formula (1).

[0063] TTC = d / Vr... (1)

[0064] The collision prediction time TTC is used as an index indicating how high the possibility is that the host vehicle collides with the obstacle, and the smaller the value is, the higher the possibility (danger) is that the host vehicle collides with the obstacle.

[0065] In the PCS control in the present embodiment, based on the collision prediction time TTC, the level of the possibility that the host vehicle collides with the obstacle is divided into 2 stages, and in the initial 1st stage, the notification section 12 provides a warning to the driver using the buzzer 90 and the display 41. In the 2nd stage in which the level of the possibility that the host vehicle collides with the obstacle becomes higher than the 1st stage, the automatic brake control section 13 implements automatic brake control, and collision avoidance support is performed.

[0066] In this case, the collision determination section 11 determines that the level of the possibility that the host vehicle collides with the obstacle reaches the 1st stage when the collision prediction time TTC falls below the alarm threshold TTCw. If the collision prediction time TTC further falls to become below the work threshold TTCa (< TTCw), the collision determination section 11 determines that the level of the possibility that the host vehicle collides with the obstacle reaches the 2nd stage. Further, the notification section 12 is not limited to the collision avoidance object, and can cause the buzzer 90 and the display 41 to work in a case where a solid object is detected for which the level of the possibility that the host vehicle collides is determined to have reached the 1st stage.

[0067] The automatic brake control section 13 sends a PCS brake command to the brake ECU 20 in a case where it is determined that the level of the possibility that the host vehicle collides with the obstacle (collision avoidance object) reaches the 2nd stage. The PCS brake command includes information indicating a PCS required deceleration Gpcs.

[0068] The PCS required deceleration Gpcs can be calculated as follows. For example, in a case where the obstacle is at a stop, if the speed (= relative speed) of the host vehicle at the current time point is set to V, the deceleration of the host vehicle is set to a (< 0), and the time until the vehicle stops is set to t, the travel distance X until the host vehicle stops can be expressed by the following equation (2).

[0069] X = V · t + (1 / 2) · a · t 2 …(2)

[0070] Further, the time t until the vehicle stops can be expressed by the following equation (3).

[0071] t = -V / a …(3)

[0072] Therefore, the running distance X until the host vehicle stops can be expressed by the following equation (4) by substituting the time t calculated by equation (3) into the time t of equation (2).

[0073] X = -V 2 / 2a... (4)

[0074] In order to stop the vehicle in front of the obstacle at a distance β, the running distance X is set to a distance (d-β) obtained by subtracting the distance β (>0) from the distance d detected by the front sensor, and the deceleration a is calculated. Further, in the case where the obstacle is running, the running distance X is calculated using the relative speed and the relative deceleration of the obstacle.

[0075] The deceleration a thus calculated is adopted as the PCS required deceleration Gpcs. Further, the PCS required deceleration Gpcs is set to have an upper limit value Gmax (>0), and in the case where the magnitude (absolute value) of the calculated PCS required deceleration Gpcs exceeds the upper limit value Gmax, the magnitude of the PCS required deceleration Gpcs is set to the upper limit value Gmax.

[0076] The brake ECU 20 controls the brake actuator 21 in such a manner that the PCS required deceleration Gpcs is obtained upon receipt of the PCS brake command. Thereby, the host vehicle can be forcibly decelerated by generating the frictional braking force at the left and right front and rear wheels without the driver's brake pedal operation.

[0077] The control of forcibly decelerating the host vehicle by generating the frictional braking force at the left and right front and rear wheels using the PCS brake command is automatic brake control.

[0078] The automatic brake control section 13 determines whether the collision prediction time TTC becomes larger than an end threshold TTCb (which is set to a value larger than the working threshold TTCa) by the automatic brake control (TTC > TTCb). That is, the automatic brake control section 13 monitors whether the possibility of collision of the host vehicle with the obstacle becomes low (whether the collision is successfully avoided). The automatic brake control section 13 ends the transmission of the PCS brake command if it is determined that the possibility of collision of the host vehicle with the obstacle becomes low. Thereby, the automatic brake control ends, and the PCS control ends. Further, the end threshold TTCb is set to a value larger than the working threshold TTCa.

[0079] Alternatively, the automatic brake control section 13 ends the transmission of the PCS brake command in a case where the host vehicle has stopped by the automatic brake control. Thus, the automatic brake control ends. Further, the automatic brake control section 13 transmits the stop maintenance command to the brake ECU 20 at a predetermined time (for example, 2 seconds) after the automatic brake control ends. The brake ECU 20 supplies the hydraulic pressure set for the stop maintenance to the wheel cylinders of the friction brake mechanisms 22 of the left and right front and rear wheels by controlling the brake actuator 21 during the reception of the stop maintenance command. Thus, the stop state of the host vehicle is maintained for a predetermined time. The PCS control ends after the stop state of the host vehicle is maintained for the predetermined time. In addition, the brake ECU 20 transmits the illumination command of the stop lamp 42 to the instrument ECU 40 during the implementation of the automatic brake control and the maintenance of the stop of the host vehicle.

[0080] The automatic brake control section 13 transmits the drive force limitation command for limiting the engine output torque (for example, making the engine output torque zero) to the engine ECU 30 during the implementation of the automatic brake control and the maintenance of the stop state of the host vehicle. Thus, even if the driver performs the accelerator pedal operation during the implementation of the automatic brake control, the driver demand torque is ignored, and thus the host vehicle does not perform the acceleration movement corresponding to the accelerator pedal operation.

[0081] There is a case where the driver recognizes an obstacle and wants to avoid the collision by the driver's own accelerator operation. In such a case, if the automatic brake control is implemented, the driver demand torque is ignored, and the accelerator override cannot be performed. Thus, the host vehicle cannot be made to travel in the driver's intended trajectory. On the other hand, in a case where the driver mistakenly steps on the accelerator pedal and the host vehicle abnormally approaches the obstacle, the automatic brake control needs to be implemented with the accelerator override prohibited.

[0082] Thus, the drive assist ECU 10 has the prohibition section 14, the prohibition limitation section 15, and the specific type determination section 16 in order to be able to appropriately perform the accelerator override depending on the situation, that is, in order to be able to appropriately limit the implementation of the automatic brake control.

[0083] The prohibition section 14 determines whether the accelerator operation amount AP (accelerator opening degree) is equal to or greater than the first operation amount threshold value AP1, and prohibits the implementation of the automatic brake control by the automatic brake control section 13 in a case where the accelerator operation amount AP is determined to be equal to or greater than the first operation amount threshold value AP1. The automatic brake control section 13 does not start the automatic brake control in a case where the implementation of the automatic brake control is prohibited from before the implementation of the automatic brake control (that is, in a case where AP is equal to or greater than AP1). The automatic brake control section 13 ends the automatic brake control at the time point in a case where the implementation of the automatic brake control is prohibited during the implementation of the automatic brake control (that is, in a case where AP increases to be equal to or greater than AP1).

[0084] Thus, for example, as shown in FIG. 6, in a case where the driver greatly depresses the accelerator pedal in order to overtake the preceding vehicle C2, even if the host vehicle Cl rapidly approaches the preceding vehicle C2, the automatic brake control is not implemented. Thus, the host vehicle Cl can be caused to travel along the trajectory intended by the driver. Figure 6

[0085] On the other hand, if the host vehicle is approaching a pedestrian or a bicycle, the driver does not usually perform a large accelerator operation. In a case where a large accelerator operation amount (accelerator opening degree) is detected in such a situation, it can be presumed that the accelerator operation is a misdepression operation.

[0086] Thus, the specific type determination section 16 discriminates whether the detected obstacle is "any one of a pedestrian and a bicycle (a bicycle being driven by the driver)" or a motor vehicle. The prohibition restriction section 15 restricts the operation of the prohibition section 14 in a case where the detected obstacle is determined by the specific type determination section 16 to be "any one of a pedestrian and a bicycle". Thereby, the automatic brake control section 13 is not prohibited from implementing the automatic brake control. Thus, in a case where the obstacle is "any one of a pedestrian and a bicycle", the automatic brake control is implemented by the automatic brake control section 13 regardless of the size of the accelerator operation amount AP. As a result, the accelerator override is not permitted.

[0087] In other words, the prohibition restriction section 15 does not restrict the operation of the prohibition section 14 in a case where the detected obstacle is determined by the specific type determination section 16 to be "a motor vehicle". Thereby, as described above, the prohibition section 14 prohibits the implementation of the automatic brake control by the automatic brake control section 13 in a case where the accelerator operation amount AP is determined to be the first operation amount threshold value AP1 or more. As a result, the accelerator override is permitted.

[0088] <Automatic brake permission / prohibition switching control routine>

[0089] Next, a specific automatic brake permission / prohibition switching process implemented by the drive assist ECU 10 (corresponding to the functional sections of the prohibition section 14, the prohibition restriction section 15, and the specific type determination section 16) will be described. Figure 2 The flowchart of FIG. 7 shows an automatic brake permission / prohibition switching control routine implemented by the drive assist ECU 10. The drive assist ECU 10 repeatedly implements the automatic brake permission / prohibition switching control routine at a predetermined calculation cycle. Hereinafter, the automatic brake permission / prohibition switching control routine will be referred to as a switching control routine.

[0090] The switching control routine is executed during a period (execution period) from when the following execution start condition is satisfied to when the following execution end condition is satisfied.

[0091] ​Execution start condition: The execution start condition is a condition that is established when it is determined that the possibility of collision of the host vehicle with the obstacle is high (i.e., when the collision prediction time TTC reaches the work threshold TTCa or less). However, as described later, in a case where the implementation of automatic brake control is prohibited by the prohibition section 14 (see S14), the execution start condition is not established until the collision prediction time TTC with respect to an obstacle different from the obstacle at the point in time reaches the work threshold TTCa or less.

[0092] Execution end condition: The execution end condition is a condition that is established at an earlier point in time of either when it is determined that collision of the host vehicle with the obstacle is avoided (i.e., when the collision prediction time TTC becomes larger than the end threshold TTCb) or when it is determined that the host vehicle has stopped.

[0093] When the switching control routine is started, the drive assist ECU 10 determines in step S11 whether the collision avoidance object is "either of a pedestrian and a bicycle (a bicycle on which a driver is riding)". In a case where the collision avoidance object is "either of a pedestrian and a bicycle" (S11: YES), the drive assist ECU 10 causes its process to proceed to step S12, and implements automatic brake control. That is, the implementation of automatic brake control is permitted by the prohibition section 14 being restricted by the restriction section 15. In this case, the drive assist ECU 10 transmits a PCS brake command to the brake ECU 20, and transmits a drive force restriction command to the engine ECU 30.

[0094] Thus, the host vehicle becomes a state in which accelerator override cannot be performed, and decelerates at the PCS required deceleration Gpcs. Therefore, for example, even in a case where the driver performs a mis-pedaling operation, the host vehicle can be reliably decelerated.

[0095] On the other hand, in a case where the collision avoidance object is neither a pedestrian nor a bicycle (S11: NO), that is, in a case where the collision avoidance object is a motor vehicle, the drive assist ECU 10 causes its process to proceed to step S13. The drive assist ECU 10 reads in the detection signal of the accelerator operation amount sensor in step S13, and determines whether the accelerator operation amount AP is the 1st operation amount threshold AP1 or more. The accelerator operation amount AP is, for example, an accelerator opening degree (%). In a case where the accelerator operation amount AP is less than the 1st operation amount threshold AP1 (S13: NO), the process is caused to proceed to step S12. Therefore, automatic brake control is implemented.

[0096] The 1st operation amount threshold AP1 is set to a value that can be considered to be very large for the accelerator operation amount AP.

[0097] The drive assist ECU 10 repeatedly performs such processing, and ends the switching control routine if collision of the host vehicle with the obstacle is avoided, or if the host vehicle stops.

[0098] In the case where the collision avoidance object is a motor vehicle, if the accelerator operation amount AP becomes the first operation amount threshold value AP1 or more in the middle of the repeated execution of the switching control routine, or in the case where the accelerator operation amount AP is the first operation amount threshold value AP1 or more at the time point at which the execution start condition of the switching control routine is satisfied, it is determined as "Yes" in step S13. In this case, the drive assist ECU 10 causes its process to proceed to step S14 without implementing the automatic brake control. That is, the implementation of the automatic brake control is prohibited by the prohibition portion 14 by prohibiting the restriction portion 15 from restricting the operation of the prohibition portion 14. In this case, the engine 32 outputs the above-described driver required torque.

[0099] For example, in the case where the collision avoidance object is a motor vehicle and the accelerator operation amount AP is the first operation amount threshold value AP1 or more at the time point at which the execution start condition of the switching control routine is satisfied, the drive assist ECU 10 does not start the automatic brake control. Therefore, the drive assist ECU 10 does not transmit the PCS brake command to the brake ECU 20 and does not transmit the drive force restriction command to the engine ECU 30.

[0100] Further, in the case where the collision avoidance object is a motor vehicle and the accelerator operation amount AP becomes the first operation amount threshold value AP1 or more during the execution of the switching control routine, the drive assist ECU 10 ends the automatic brake control implemented up to that time point. Therefore, the drive assist ECU 10 stops the transmission of the PCS brake command to the brake ECU 20 and stops the transmission of the drive force restriction command to the engine ECU 30.

[0101] Thus, the host vehicle becomes a state in which the accelerator override is possible. Therefore, the driver can accelerate the host vehicle while using the accelerator operation to perform the collision avoidance.

[0102] As described above, according to the collision avoidance support device of the present embodiment, if the collision avoidance object is "either of a pedestrian and a bicycle", the automatic brake control is implemented regardless of the accelerator operation amount (the automatic brake control is permitted). On the other hand, if the collision avoidance object is a motor vehicle, the automatic brake control is prohibited in the case where the accelerator operation amount is greater than the first operation amount threshold value. Therefore, the automatic brake control can be implemented in an appropriate situation.

[0103] For example, when the vehicle is approaching either a pedestrian or a cyclist, the driver usually does not forcefully depress the accelerator pedal. However, if the driver becomes anxious due to a delay in approaching the pedestrian or cyclist, they might intend to depress the brake pedal but mistakenly depress the accelerator pedal forcefully. According to this embodiment, in such situations, automatic braking control is implemented, preventing accelerator overshoot. Therefore, even if a mistaken pedal operation occurs, appropriate collision avoidance support can be provided.

[0104] For example, if a driver accelerates to overtake a vehicle (another motor vehicle) traveling ahead, it is conceivable that the vehicle might be perceived as an obstacle due to its rapid approach. According to this embodiment, when the collision avoidance target is a motor vehicle and a large acceleration operation is performed, automatic braking control is prohibited, and overtaking control is possible. Therefore, undesirable automatic braking control is avoided, allowing the driver to overtake the vehicle on the desired trajectory. Furthermore, it prevents following vehicles from excessively approaching the vehicle.

[0105] <Variation Example 1>

[0106] Next, a variation of the switching control routine, Example 1, will be explained. Figure 3 This represents the switching control routine of Modification 1. The switching control routine of Modification 1 is a modification of the switching control routine of the implementation embodiment (…). Figure 2 The switching control routine obtained by adding step S15 is the same as the switching control routine in the embodiment. For processes identical to those in the embodiment, common step numbers are used in the accompanying drawings and descriptions are omitted.

[0107] If the driving support ECU 10 determines in step S13 that the accelerator operation amount AP is less than the first operation amount threshold AP1 (S13: No), it proceeds to step S15. In step S15, the driving support ECU 10 determines whether the accelerator operation amount AP is greater than or equal to the second operation amount threshold AP2 and whether the accelerator operation speed AS is greater than or equal to the operation speed threshold AS1. The second operation amount threshold AP2 is a value smaller than the first operation amount threshold AP1, but is set to a value that the accelerator operation amount AP would reach only when an accelerator operation that can be considered a relatively large accelerator operation is performed. The accelerator operation speed AS is the change in the accelerator operation amount AP per unit time. The operation speed threshold AS1 is set to a value that the accelerator operation speed AS would reach only when an accelerator operation that can be considered a relatively fast accelerator operation is performed.

[0108] Therefore, the process of this step S15 is a process of determining whether the accelerator operation is performed with a large operation amount and a fast operation speed although the accelerator operation amount AP is smaller than the first operation amount threshold value AP1.

[0109] The drive assist ECU 10 causes the process to proceed to step S14 in a case where it is determined that the accelerator operation amount AP is the second operation amount threshold value AP2 or more and the accelerator operation speed AS is the operation speed threshold value AS1 or more (S15: YES), and causes the process to proceed to step S12 in a case where it is not determined as above (S15: NO).

[0110] Therefore, according to this modified example 1, the accelerator operation condition in which the implementation of the automatic brake control is prohibited can be more appropriately set. Thus, the case where the automatic brake control is implemented by the accelerator operation by the driver's own intention can be reduced.

[0111] <Modified Example 2>

[0112] Next, a modified example 2 of the switching control routine will be described. Figure 4 The switching control routine of the modified example 2 is a switching control routine obtained by adding a determination process of step S16 to the switching control routine of the embodiment ( Figure 2 ) and is the same as the switching control routine of the embodiment in other processes. As for the processes common to the switching control routine of the embodiment, the common step numbers are marked in the drawings and the description is omitted.

[0113] In the switching control routine of the embodiment, the automatic brake control is necessarily implemented in a case where the collision avoidance object is "either of the pedestrian and the bicycle". In contrast to this, in the modified example 2, the automatic brake control is ended in a case where the intentional accelerator operation of the driver is detected in the implementation of the automatic brake control.

[0114] The drive assist ECU 10 causes the process to proceed to step S16 in a case where it is determined that the collision avoidance object is "either of the pedestrian and the bicycle" in step Sll (Sll: YES). The drive assist ECU 10 determines whether the re-pedaling operation of the accelerator pedal is performed in step S16. The re-pedaling operation of the accelerator pedal is an operation of moving the foot from the pedaled accelerator pedal and then pedaling the accelerator pedal again. The determination is a determination as to whether there is a history that the re-pedaling operation of the accelerator pedal is performed in the implementation of the automatic brake control.

[0115] The drive assist ECU 10 reads in the detection signal of the accelerator operation amount sensor to determine whether or not a re-pedaling operation of the accelerator pedal has been performed. For example, in a case where the accelerator operation amount (accelerator opening degree) decreases from a value that can be regarded as the accelerator pedal being pedaled to a value that can be regarded as the accelerator pedal not being pedaled and then increases to a value that can be regarded as the accelerator pedal being pedaled, it is determined that a re-pedaling operation of the accelerator pedal has been performed.

[0116] The re-pedaling operation of the accelerator pedal can be presumed to be an intentional operation by the driver to accelerate the host vehicle. In this case, it is preferable that accelerator override be enabled. Thus, the drive assist ECU 10, in a case where it is determined that a re-pedaling operation of the accelerator pedal has been performed in the automatic brake control (S16: YES), causes its processing to proceed to Step S14. As a result, the automatic brake control ends. In addition, accelerator override is enabled. Thereby, the driver can perform collision avoidance by his or her own driving operation.

[0117] Further, the determination processing of Step S16 in the above-described Modification 2 is implemented only in a case where the collision avoidance target is "either of a pedestrian and a bicycle". However, it is also possible to implement the determination processing of Step S16 also in a case where the collision avoidance target is a motor vehicle, as in the switching control routine of Modification 3 shown below. Figure 5 That is, in a case where it is determined "NO" in Step Sll and in a case where it is determined "NO" in Step S13, the presence or absence of a re-pedaling operation of the accelerator pedal is determined. And, in a case where it is determined that a re-pedaling operation of the accelerator pedal has been performed (S16: YES), its processing proceeds to Step S14.

[0118] The above, although the collision avoidance support device of the present embodiment has been described, the present application is not limited to the above-described embodiment, and various modifications can be made without departing from the object of the present application.

[0119] For example, in the present embodiment, the collision avoidance target is set to a pedestrian, a bicycle (a bicycle ridden by a driver), and a motor vehicle, but is not necessarily limited to these three types.

[0120] Further, for example, a routine obtained by combining the switching control routine of Modification 1 with the switching control routine of Modification 2 (or Modification 3) can also be employed. In addition to this, Figure 3 The determination of Step S13 can also be a determination of whether or not the accelerator operation speed AS is the operation speed threshold value AS1 or more.

[0121] Further, for example, the order of Step Sll and Step S13 of the switching control routine can be reversed. That is, it is also possible to implement the determination processing of Step S13 first, and in a case where it is determined "YES" in Step S13, implement the processing of Step Sll.

Claims

1. A collision avoidance support device, characterized in that, have: The braking device generates braking force in the vehicle in accordance with the driver's braking operation. An obstacle detection unit detects obstacles present around the vehicle. The automatic braking control unit implements automatic braking control when it determines that there is a high probability of the vehicle colliding with the obstacle. The automatic braking control is used to generate braking force by the braking device to avoid the vehicle colliding with the obstacle. and The automatic braking prohibition unit prohibits the implementation of automatic braking control based on the driver's predetermined accelerator operation. The collision avoidance support device includes: The limiting unit, at least when the obstacle is determined to be a pedestrian or bicycle, restricts the operation of the automatic braking prohibition unit so that the automatic braking prohibition unit does not prohibit the implementation of the automatic braking control.

2. The collision avoidance support device according to claim 1, characterized in that, The automatic braking control unit identifies pedestrians, bicycles, and motor vehicles as obstacles targeted by the automatic braking control. The collision avoidance support device also includes a specific type determination unit configured to determine whether the obstacle is at least the pedestrian or the bicycle, and whether the obstacle is the motor vehicle.

3. The collision avoidance support device according to claim 1 or 2, characterized in that, The predetermined accelerator operation refers to the operation of the accelerator pedal of the vehicle. The collision avoidance support device includes: The re-depressing determination unit determines whether the accelerator pedal has been re-depressed during the implementation of the automatic braking control; and When the accelerator pedal is re-pressed, the automatic braking control unit terminates the automatic braking control if the re-pressing determination unit determines that the accelerator pedal has been re-pressed during the implementation of the automatic braking control.

4. The collision avoidance support device according to claim 1 or 2, characterized in that, The predetermined accelerator operation refers to the operation of the accelerator pedal of the vehicle. The automatic braking prohibition unit is configured as follows: The driver's accelerator pedal input and accelerator pedal input speed are obtained as the predetermined accelerator operation. The automatic braking control is disabled if at least one of the first and second conditions is met, wherein the first condition is that the accelerator pedal operation amount is above a first operation amount threshold, and the second condition is that the accelerator pedal operation amount is above a second operation amount threshold that is less than the first operation amount threshold and the accelerator pedal operation speed is above an operation speed threshold.

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