Driving support device, driving support method, and program

Abstract

To set the request deceleration of an automatic brake to the proper deceleration.SOLUTION: A drive support device comprises: a target information acquisition unit 30 which acquires target information on the front side of a vehicle; an operation amount acquisition unit 23 which acquires an operation amount of an accelerator pedal; and a control unit 10 which predicts whether a vehicle SV collides with the target on the basis of the target information acquired by the target information acquisition unit 30, and executes collision avoidance support control of decelerating the vehicle SV at a prescribed request deceleration Gp by an automatic brake for automatically actuating a brake device 71 of the vehicle SV when an execution condition in which the operation amount acquired by the operation amount acquisition unit 23 becomes a prescribed operation amount or greater is established in a case where it is predicted that the vehicle collides with the target. The control unit 10 sets the request deceleration Gp on the basis of a relative distance and a relative speed acquired by the target information acquisition unit 30 when the execution condition is established.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present disclosure relates to a driving support device, a driving support method, and a program.

Background Art

[0002] Conventionally, when an obstacle highly likely to collide with the host vehicle ahead during travel is detected, the host vehicle is decelerated at a predetermined required deceleration by an automatic brake that automatically activates the braking device, and collision avoidance support control for avoiding a collision with the obstacle is performed. An apparatus is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] When performing collision avoidance support control, if the required deceleration of the automatic brake is set to a uniform deceleration regardless of the relative distance or relative speed between the host vehicle and the obstacle, the following problems occur. For example, if the required deceleration is uniformly set to a large deceleration to surely avoid a collision with the obstacle, when the automatic brake is activated in a state where the relative distance to the obstacle is relatively long or the relative speed to the obstacle is relatively low, the host vehicle will decelerate at an excessive deceleration. As a result, there is a problem that the host vehicle stops further ahead of the obstacle than necessary, giving an unnecessary feeling to the driver.

[0005] To reduce such an unnecessary feeling of the driver, it is conceivable to set the required deceleration of the automatic brake to a small deceleration. However, if the required deceleration is uniformly set to a small deceleration, for example, when the automatic brake is activated in a state where the relative distance to the obstacle is relatively short or the relative speed to the obstacle is relatively high, there is a problem that it may not be possible to surely avoid a collision between the host vehicle and the obstacle.

[0006] The present disclosure has been made to solve the above problems. That is, when performing collision avoidance support control, it is to set the required deceleration of the automatic brake to an appropriate deceleration.

[0007] The driving support device (1) of the present disclosure a target information acquisition unit (30) that acquires target information including the relative distance (Dr) and relative speed (Vr) between the vehicle (SV) and a target in front of the vehicle; an operation amount acquisition unit (23) that acquires the operation amount of an accelerator pedal by an occupant of the vehicle (SV); Based on the target information acquired by the target information acquisition unit (30), it predicts whether the vehicle (SV) will collide with the target, and when it is predicted that the vehicle (SV) will collide with the target, and when an execution condition that the operation amount acquired by the operation amount acquisition unit (23) is equal to or greater than a predetermined operation amount is satisfied, a control unit (10) that executes collision avoidance support control for decelerating the vehicle (SV) at a predetermined required deceleration (Gp) by an automatic brake that automatically activates the brake device (71) of the vehicle (SV), The control unit (10) is characterized in that the required deceleration (Gp) is set based on the relative distance (Dr) and the relative speed (Vr) acquired by the target information acquisition unit (30) when the execution condition is satisfied.

[0008] The driving support method of the present disclosure acquires target information including the relative distance (Dr) and relative speed (Vr) between the vehicle (SV) and a target in front of the vehicle, acquires the operation amount of an accelerator pedal by an occupant of the vehicle (SV), Based on the acquired target information, it predicts whether the vehicle (SV) will collide with the target, and when it is predicted that the vehicle (SV) will collide with the target, and when an execution condition that the acquired operation amount is equal to or greater than a predetermined operation amount is satisfied, collision avoidance support control is executed to decelerate the vehicle (SV) at a predetermined required deceleration (Gp) by an automatic brake that automatically activates the brake device (71) of the vehicle (SV), The required deceleration (Gp) is set based on the relative distance (Dr) and the relative speed (Vr) acquired when the execution condition is satisfied.

[0009] The program of the present disclosure causes a computer (10) of the driving support device (1) to acquire target information including a relative distance (Dr) and a relative speed (Vr) between a vehicle (SV) and a target in front of the vehicle, to acquire an operation amount of an accelerator pedal by an occupant of the vehicle (SV), to predict whether the vehicle (SV) will collide with the target based on the acquired target information, and when it is predicted that the vehicle (SV) will collide with the target, if an execution condition that the acquired operation amount is equal to or more than a predetermined operation amount is satisfied, collision avoidance support control is executed to automatically decelerate the vehicle (SV) at a predetermined required deceleration (Gp) by an automatic brake that automatically operates a brake device (71) of the vehicle (SV), and executes a process of setting the required deceleration (Gp) based on the relative distance (Dr) and the relative speed (Vr) acquired when the execution condition is satisfied.

[0010] According to the above configuration, the required deceleration (Gp) of the automatic brake is set based on the relative distance (Dr) and the relative speed (Vr) between the host vehicle (SV) and the obstacle when the execution condition of the automatic brake is satisfied. Thereby, when executing the collision avoidance support control, it becomes possible to operate the automatic brake at an appropriate required deceleration (Gp) according to the relative distance (Dr) and the relative speed (Vr) between the host vehicle (SV) and the obstacle.

[0011] In another aspect of the present disclosure, when the execution condition is satisfied, the control unit (10) sets the target deceleration (Gp) to a larger deceleration as the relative distance (Dr) acquired by the target information acquisition unit (30) is shorter and the relative speed (Vr) acquired by the target information acquisition unit (30) is higher.

[0012] According to this aspect, the shorter the relative distance (Dr) between the host vehicle (SV) and the obstacle and the higher the relative speed (Vr), the greater the target deceleration (Gp) of the automatic brake is set to a large deceleration, so that it is possible to surely avoid a collision with the obstacle.

[0013] In another aspect of the present disclosure, when the execution condition is satisfied, the control unit (10) sets the target deceleration (Gp) to a smaller deceleration as the relative distance (Dr) acquired by the target information acquisition unit (30) is longer and the relative speed (Vr) acquired by the target information acquisition unit (30) is lower.

[0014] According to this aspect, the longer the relative distance (Dr) between the host vehicle (SV) and the obstacle and the lower the relative speed (Vr), the smaller the target deceleration (Gp) of the automatic brake is set to a smaller deceleration, so that it is possible to prevent the host vehicle (SV) from stopping further ahead of the obstacle than necessary and surely reduce the discomfort of the driver.

[0015] In the above description, for the purpose of assisting the understanding of the invention, the reference numerals used in the embodiments are attached in parentheses to the constituent elements of the invention corresponding to the embodiments. However, each constituent element of the invention is not limited to the embodiments defined by the above reference numerals.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0017] Hereinafter, a driving support device, a driving support method, and a program according to the present embodiment will be described with reference to the drawings. The same parts are denoted by the same reference numerals, and their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

[0018] [Overall Configuration] FIG. 1 is a schematic overall configuration diagram of a driving support device 1 according to the present embodiment. The driving support device 1 is mounted on a vehicle SV. The vehicle SV is also referred to as the host vehicle when it is necessary to distinguish it from other vehicles or the like. The driving support device 1 includes a driving support ECU 10, a drive source ECU 60, and a brake ECU 70.

[0019] These ECUs 10, 60, and 70 are electronic control devices (Electronic Control Unit) having a microcomputer as a main part, and are connected to be able to transmit and receive information to and from each other via a CAN (Controller Area Network) not shown. The microcomputer includes a CPU, a ROM, a RAM, an interface, etc., and the CPU realizes various functions by executing instructions (programs, routines) stored in the ROM. Some or all of these ECUs 10, 60, and 70 may be integrated into one ECU.

[0020] The driving support ECU 10 is a control device that serves as a center for performing driving support for the driver, and implements collision avoidance support control. The collision avoidance support control is to issue a warning (alert) to the driver when an obstacle highly likely to collide with the host vehicle SV is detected in front of the host vehicle SV during traveling, and to perform automatic braking when the possibility of collision further increases, thereby avoiding a collision between the host vehicle SV and the obstacle. The collision avoidance support control is generally called PCS control (Pre-Crash Safety control). Therefore, hereinafter, the collision avoidance support control will be referred to as PCS control.

[0021] The driving support ECU 10 is connected to a vehicle state acquisition device 20, a surrounding recognition device 30, a display 40, a speaker 50, etc.

[0022] The vehicle state acquisition device 20 is sensors that acquire the state of the vehicle SV. Specifically, the vehicle state acquisition device 20 includes a steering angle sensor 21, a vehicle speed sensor 22, an accelerator sensor 23, a brake sensor 24, etc.

[0023] The steering angle sensor 21 detects the steering angle of a steering wheel (or a steering shaft) (not shown). The vehicle speed sensor 22 detects the traveling speed (vehicle speed V) of the vehicle SV. The vehicle speed sensor 22 may be a wheel speed sensor. The accelerator sensor 23 detects the operation amount of an accelerator pedal (not shown). The brake sensor 24 detects the operation amount of a brake pedal (not shown). The state information of the vehicle SV acquired by the vehicle state acquisition device 20 is transmitted to the driving support ECU 10. Note that the accelerator sensor 23 may be connected to the drive source ECU 60, and the brake sensor 24 may be connected to the brake ECU 70.

[0024] The surrounding recognition device 30 is sensors that recognize target information regarding targets around the vehicle SV. Specifically, the surrounding recognition device 30 includes a front camera 31, a front millimeter wave radar 32, a front lidar 33, etc. The target information around the vehicle SV acquired by the surrounding recognition device 30 is transmitted to the driving support ECU 10 at a predetermined cycle.

[0025] The front camera 31 is disposed, for example, at the upper part of the front windshield glass of the vehicle SV. The front camera 31 is, for example, a stereo camera or a monocular camera, and a digital camera having an image sensor such as a CMOS or a CCD can be used. The front camera 31 images the front of the vehicle SV and acquires target information in front of the vehicle SV by processing the captured image data. The target information is information representing the type of an obstacle detected in front of the vehicle SV, the relative distance between the vehicle SV and the obstacle, the relative speed between the vehicle SV and the obstacle, etc. The type of the obstacle may be recognized by machine learning such as pattern matching.

[0026] The front millimeter-wave radar 32 is provided, for example, at the center position in the vehicle width direction at the front end of the vehicle SV, and detects obstacles existing in the front area of the vehicle SV. The front millimeter-wave radar 32 emits radio waves in the millimeter-wave band (hereinafter referred to as "millimeter waves"), and receives millimeter waves (i.e., reflected waves) reflected by obstacles (such as other vehicles, pedestrians, buildings, etc.) existing within the radiation range. The front millimeter-wave radar 32 acquires the relative distance between the vehicle SV and the obstacle, the relative speed between the vehicle SV and the obstacle, the relative position (direction) of the obstacle with respect to the vehicle SV, etc. based on the phase difference between the transmitted millimeter wave and the received reflected wave, the attenuation level of the reflected wave, and the time from transmitting the millimeter wave to receiving the reflected wave.

[0027] The front lidar 33 is provided, for example, at the center position in the vehicle width direction at the front end of the vehicle SV. The front lidar 33 sequentially scans in a plurality of directions with pulsed laser light having a shorter wavelength than millimeter waves, and receives the reflected light reflected by the target, thereby acquiring target information in front of the vehicle SV. The target information is information representing, for example, the shape of an obstacle detected in front of the vehicle SV, the relative distance between the vehicle SV and the obstacle, the relative speed between the vehicle SV and the obstacle, etc.

[0028] When the display device 40 receives an instruction to display a warning screen from the driving support ECU 10, it displays the warning screen. The warning screen is an image for alerting the driver. Examples of the display device 40 include a multi-information display provided in front of the driver's seat of the vehicle SV, a head-up display, etc. When the speaker 50 receives an instruction to output an alarm sound from the driving support ECU 10, it outputs an alarm sound for alerting the driver.

[0029] The vehicle SV is equipped with a drive device 61. The drive device 61 generates a driving force to be transmitted to the drive wheels of the vehicle SV. Examples of the drive device 61 include an electric motor and an engine. The vehicle SV may be any of an engine vehicle, a hybrid vehicle (HEV), a plug-in hybrid vehicle (PHEV), a fuel cell vehicle (FCEV), and a battery electric vehicle (BEV).

[0030] A drive source ECU 60 is connected to the drive device 61. The drive source ECU 60 sets a driver required torque based on the accelerator pedal operation amount detected by the accelerator sensor 23 and controls the operation of the drive device 61 so that the drive device 61 outputs the driver required torque. Further, when it is determined that there is a possibility that the own vehicle SV will collide with an obstacle ahead during traveling and the driving support ECU 10 executes PCS control, the drive source ECU 60 controls the operation of the drive device 61 so as to limit the output torque of the drive device 61. Also, when the driving support ECU 10 executes PCS control, the drive source ECU 60 controls the drive device 61 so as not to accept the accelerator operation even if the driver performs an accelerator operation.

[0031] The vehicle SV is equipped with a brake device 71. The brake device 71 is, for example, a disc type brake device that applies a braking force to the wheels of the vehicle SV. The brake device 71 includes a brake actuator 72. The brake actuator 72 is provided in a hydraulic circuit between a master cylinder (not shown) that pressurizes hydraulic oil by the stepping force of the brake pedal and a friction brake mechanism 73 provided on the left and right front and rear wheels. The friction brake mechanism 73 includes a brake disc 74 fixed to the wheel and a brake caliper 75 fixed to the vehicle body. The brake actuator 72 adjusts the hydraulic pressure supplied to a wheel cylinder built in the brake caliper 75, and operates the wheel cylinder by the hydraulic pressure to press a brake pad against the brake disc 74 to generate a frictional braking force. Note that the brake device 71 is not limited to a disc type brake device, and may be another brake device that applies a braking force to the wheels of the vehicle SV, such as a drum type brake device.

[0032] A brake ECU 70 is connected to a brake actuator 72. The brake ECU 70 sets a driver required deceleration Gd based on the amount of operation of the brake pedal detected by a brake sensor 24, and controls the operation of the brake actuator 72 so that the vehicle SV decelerates at the driver required deceleration Gd. Further, when the brake pedal is operated by the driver while the brake ECU 70 is receiving a PCS brake command from the driving support ECU 10, the brake ECU 70 adopts, as the final required deceleration, the required deceleration having the larger absolute value between the driver required deceleration Gd and a PCS required deceleration Gp, which will be described later. The brake ECU 70 controls the operation of the brake actuator 72 so that the vehicle SV decelerates at the final required deceleration. That is, the brake ECU 70 performs brake override.

[0033] [PCS Control] Next, PCS control will be described. Focusing on its functions, the driving support ECU 10 includes a collision prediction unit 12, a malfunction determination unit 14, and an automatic brake control unit 15 as some of its functional elements. Although each of these functional elements will be described as being included in the driving support ECU 10, which is an integrated hardware, any one of these elements can be provided in an ECU separate from the driving support ECU 10.

[0034] The collision prediction unit 12 extracts, as an obstacle, a target that may collide with the host vehicle SV from among the targets existing in front of the vehicle SV based on the target information in front of the vehicle SV acquired by the surrounding recognition device 30, and calculates the value of the relative distance Dr of the extracted obstacle with respect to the host vehicle SV.

[0035] Further, the collision prediction unit 12 predicts whether the host vehicle SV will collide with a forward obstacle when a misoperation due to a stepping error occurs, based on the relative distance Dr from the obstacle. Specifically, a threshold distance Dth is stored in the ROM of the driving support ECU 10. The threshold distance Dth is a distance that serves as an index for predicting that the host vehicle SV may collide with an obstacle when a misoperation due to a stepping error occurs. The collision prediction unit 12 compares the threshold distance Dth read from the ROM with the relative distance Dv that is sequentially calculated, to predict whether the host vehicle SV will collide with a forward obstacle when a misoperation due to a stepping error occurs.

[0036] When the value of the relative distance Dv of the obstacle with respect to the host vehicle SV decreases to the threshold distance Dth, the collision prediction unit 12 determines that the collision possibility level has reached a pre-collision stage where the host vehicle SV may collide with the obstacle when a misoperation due to a stepping error occurs. When it is determined that the collision possibility level has reached the pre-collision stage and it is determined that a misoperation as described later has occurred, the automatic brake control unit 15 executes the automatic brake. Note that the collision prediction is not limited to the method of comparing the relative distance Dv and the threshold distance Dth, and it can also be predicted based on the time to collision TTC. The time to collision TTC is obtained by dividing the relative distance Dr between the host vehicle SV and the obstacle at a certain point in time by the relative speed Vr (TTC = Dr / Vr). In the case based on the time to collision TTC, the time to collision TTC is compared with a threshold time that serves as an index for predicting that the host vehicle SV may collide with the obstacle. When the time to collision TTC becomes equal to or less than the threshold time, it may be determined that the pre-collision stage where the host vehicle SV may collide with the obstacle has been reached when a misoperation due to a stepping error occurs.

[0037] When the collision determination unit 12 determines that the collision possibility level has reached the pre-collision stage, the misoperation determination unit 14 determines whether the driver has made a misoperation (wrong operation) of stepping on the accelerator pedal by mistake instead of the brake pedal. For example, when the driver recognizes an obstacle ahead and performs an avoidance operation to avoid a collision with the obstacle, it is conceivable to gently accelerate the vehicle SV while performing a steering operation. On the other hand, in a situation where the host vehicle SV is approaching an obstacle ahead, generally, it is considered that the driver does not perform a large accelerator operation. When a large accelerator operation amount is detected in such a situation, it can be presumed that the accelerator operation is a misoperation due to stepping on the wrong pedal.

[0038] When the collision determination unit 12 determines that the collision possibility level has reached the pre-collision stage, if the accelerator pedal operation amount AP detected by the accelerator sensor 23 is equal to or greater than a predetermined operation amount threshold APv, the misoperation determination unit 14 determines that the accelerator operation by the driver is due to a misoperation. Note that whether the accelerator operation by the driver is a misoperation may be determined in combination with other operation states such as a steering operation or an operation of a direction indicator.

[0039] When the collision determination unit 12 determines that the collision possibility level has reached the pre-collision stage and it is determined that the accelerator operation by the driver is due to a misoperation, the automatic brake control unit 15 determines that the execution condition of the automatic brake is satisfied, and transmits a PCS brake command to the brake ECU 70. This PCS brake command includes information representing the PCS required deceleration Gp.

[0040] When receiving the PCS brake command, the brake ECU 70 controls the operation of the brake actuator 72 so that the vehicle SV decelerates at the PCS required deceleration Gp. Thereby, without requiring the driver to operate the brake pedal, frictional braking force is generated on the left and right front and rear wheels, and the vehicle SV can be forcibly decelerated. In this way, the control of generating frictional braking force on the left and right front and rear wheels by the PCS brake command to decelerate the host vehicle SV is the automatic brake.

[0041] During the execution of the automatic brake, the automatic brake control unit 15 transmits a driving force limit command to the drive source ECU 60 to limit (for example, set to zero) the output torque of the drive device 61. Therefore, even if the driver operates the accelerator pedal during the execution of the automatic brake, the driver's required torque is not accepted, and the vehicle SV does not perform an acceleration run corresponding to the accelerator pedal operation.

[0042] The automatic brake control unit 15 monitors whether the host vehicle SV has reached a state where it can avoid a collision by executing the automatic brake. Specifically, when the obstacle moves away from the host vehicle SV, or when the host vehicle SV stops in front of the obstacle by the automatic brake, or when using the collision prediction time TTC, if the collision prediction time TTC becomes greater than a predetermined end threshold time TTCb (>TTCa), the automatic brake control unit 15 determines that the host vehicle SV has reached a state where it can avoid a collision and ends the transmission of the PCS brake command. As a result, the automatic brake ends, and at the same time, the PCS control also ends.

[0043] By the way, if the PCS required deceleration Gp when executing the automatic brake is set to a uniform deceleration regardless of the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle, the following problems occur. For example, in order to surely avoid a collision with the obstacle, if the PCS required deceleration Gp is uniformly set to a large deceleration, when the automatic brake is activated in a state where the relative distance Dr to the obstacle is relatively long or the relative speed Vr to the obstacle is relatively low, the host vehicle SV will be decelerated at an excessive deceleration. For this reason, there is a problem that the host vehicle SV stops further ahead of the obstacle than necessary, giving the driver a sense of unease. On the other hand, if the PCS required deceleration Gp is uniformly set to a small deceleration in order to reduce the driver's sense of unease, for example, when the automatic brake is activated in a state where the relative distance Dr to the obstacle is relatively short or the relative speed Vr is relatively high, there is a problem that the collision with the obstacle cannot be surely avoided.

[0044] Therefore, in this embodiment, by setting the PCS required deceleration Gp to an optimal value according to the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle when the execution condition of the automatic brake is satisfied, these problems are solved. Hereinafter, the setting process of the specific PCS required deceleration Gp will be described.

[0045] FIG. 2 is a schematic diagram showing an example of the required deceleration map M according to this embodiment. The required deceleration map M is a map created, for example, by conducting experiments and simulations during the design and development stage of the vehicle SV, and is stored in advance in the ROM of the driving support ECU 10. In this required deceleration map M, a PCS required deceleration Gp (absolute value) that changes according to the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle is set.

[0046] In the required deceleration map M, the PCS required deceleration Gp is set to a larger deceleration as the relative distance Dr becomes shorter and the relative speed Vr becomes higher, and is set to a smaller deceleration as the relative distance Dr becomes longer and the relative speed Vr becomes lower. Also, in the required deceleration map M, the PCS required deceleration Gp is set to a relatively small deceleration even when the relative distance Dr is short but the relative speed Vr is low, and is set to a relatively large deceleration even when the relative distance Dr is long but the relative speed Vr is high.

[0047] When the execution condition of the automatic brake is satisfied, the automatic brake control unit 15 refers to the required deceleration map M based on the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle at that time, reads the PCS required deceleration Gp corresponding to these relative distance Dr and relative speed Vr, and outputs a PCS brake command including the read PCS required deceleration Gp to the brake ECU 70. When receiving the PCS brake command, the brake ECU 70 controls the operation of the brake actuator 72 so that the vehicle SV decelerates at the PCS required deceleration Gp.

[0048] In this way, instead of making the PCS required deceleration Gp of the automatic brake a uniform deceleration, by setting it to an appropriate value according to the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle, when the relative distance Dr is long and the relative speed Vr is low, the host vehicle SV will decelerate with a small PCS required deceleration Gp. As a result, it is possible to prevent excessive deceleration from occurring in the host vehicle SV or the host vehicle SV from stopping further ahead of the obstacle than necessary, and it becomes possible to reliably reduce the discomfort given to the driver. Also, when the relative distance Dr is short and the relative speed Vr is high, by decelerating the host vehicle SV with a large PCS required deceleration Gp, it is also possible to reliably avoid a collision with the obstacle.

[0049] Next, based on the timing chart shown in FIG. 3, the specific flow of the PCS control will be described. Here, FIG. 3(A) shows the case where the automatic brake is actuated when the relative distance Dr between the host vehicle SV and the obstacle is relatively long and the relative speed Vr is relatively low, and FIG. 3(B) shows the case where the automatic brake is actuated when the relative distance Dr between the host vehicle SV and the obstacle is relatively short and the relative speed Vr is relatively high.

[0050] At time t0 shown in FIG. 3, the vehicle SV is traveling at a predetermined speed. At time t1, when the driving support ECU 10 detects an obstacle that may collide with the vehicle SV based on the target information in front of the vehicle SV acquired by the surrounding recognition device 30, it starts calculating the relative distance Dr of the obstacle with respect to the vehicle SV.

[0051] At time t2, when the value of the relative distance Dv drops to the threshold distance Dth, the driving support ECU 10 determines whether the driver has performed a misoperation of accidentally stepping on the accelerator pedal based on the accelerator pedal operation amount AP detected by the accelerator sensor 23. At time t3, when the accelerator pedal operation amount AP becomes equal to or greater than the predetermined operation amount threshold APv, the driving support ECU 10 determines that the driver has performed a misoperation of accidentally stepping on the accelerator pedal and also determines that the execution condition of the automatic brake has been satisfied.

[0052] When it is determined at time t3 that the execution condition of the automatic brake is satisfied, the driving support ECU 10 refers to the required deceleration map M (shown in FIG. 2) based on the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle at that time, and sets a PCS required deceleration Gp corresponding to the relative distance Dr and relative speed Vr. Further, the driving support ECU 10 outputs a PCS brake command including the set PCS required deceleration Gp to the brake ECU 70, thereby starting the automatic brake.

[0053] After the start of the automatic brake, at time t4, if the obstacle moves away from the host vehicle SV, or if the host vehicle SV stops in front of the obstacle, or when using the time to collision TTC, if the time to collision TTC becomes greater than a predetermined end threshold time TTCb (>TTCa), the driving support ECU 10 determines that the host vehicle SV is in a state where it can avoid a collision with the obstacle, and ends the automatic brake, that is, ends the PCS control.

[0054] In the present embodiment, the PCS required deceleration Gp of the automatic brake executed during the period from time t3 to time t4 is set to an appropriate deceleration corresponding to the relative distance Dr and relative speed Vr between the host vehicle SV and the obstacle acquired by the surrounding recognition device 30 at time t3 when the execution condition of the automatic brake control is satisfied, by referring to the required deceleration map M.

[0055] That is, as shown in FIG. 3(A), when the relative distance Dr from the obstacle is long and the relative speed Vr with the obstacle is low at time t3 when the execution condition of the automatic brake is satisfied, the PCS required deceleration Gp of the automatic brake is set to a small deceleration. Thereby, it is possible to prevent an excessive deceleration from occurring in the host vehicle SV during the period from time t3 to time t4, and further, it is possible to effectively prevent the host vehicle SV from stopping more than necessary in front of the obstacle, and it becomes possible to surely reduce the discomfort of the driver.

[0056] On the other hand, as shown in Fig. 3(B), when the relative distance Dr to the obstacle is short and the relative speed Vr to the obstacle is high at time t3 when the execution condition of the automatic brake is satisfied, the PCS required deceleration Gp of the automatic brake is set to a large deceleration. As a result, the host vehicle SV can be decelerated at a large deceleration over the period from time t3 to time t3, and it becomes possible to surely avoid the host vehicle SV from colliding with the obstacle.

[0057] Next, based on the flowchart shown in Fig. 4, a routine of PCS control by the driving support ECU 10 will be described.

[0058] In step S100, the driving support ECU 10 determines whether or not the host vehicle SV is running based on the detection result of the vehicle speed sensor 22. If the host vehicle SV is running (Yes), the driving support ECU 10 advances its process to step S105. On the other hand, if the host vehicle SV is not running (No), that is, if the host vehicle SV is stopped, the driving support ECU 10 returns from this routine.

[0059] In step S105, the driving support ECU 10 determines whether or not an obstacle has been detected in front of the host vehicle SV based on the target information in front of the vehicle acquired by the surrounding recognition device 30. If an obstacle has been detected in front of the host vehicle SV (Yes), the driving support ECU 10 advances its process to step S110. On the other hand, if no obstacle has been detected in front of the host vehicle SV (No), the driving support ECU 10 returns from this routine.

[0060] In step S110, the driving support ECU 10 calculates the relative distance Dr between the host vehicle SV and the obstacle based on the target information in front of the vehicle acquired by the surrounding recognition device 30. Next, the driving support ECU 10 advances its process to step S115. When based on the time to collision TTC, the driving support ECU 10 calculates the time to collision TTC in step S110.

[0061] In step S115, the driving support ECU 10 determines whether the relative distance Dr has decreased to the threshold distance Dth. If the relative distance Dr has decreased to the threshold distance Dth (Yes), the driving support ECU 10 determines that the collision possibility level has reached the pre - collision stage, and proceeds with the process to step S120. On the other hand, if the relative distance Dr has not decreased to the threshold distance Dth (No), the driving support ECU 10 proceeds with the process to step S180. Note that when based on the time - to - collision TTC, the driving support ECU 10 determines in step S115 whether the time - to - collision TTC has become less than or equal to the threshold time. If it is affirmative (Yes), it proceeds to step S120, and if it is negative (No), it proceeds to step S180.

[0062] In step 120, the driving support ECU 10 warns the driver by operating the display 40 and / or the speaker 50. Then, the driving support ECU 10 proceeds with the process to step S130.

[0063] In step S130, the driving support ECU 10 determines whether an incorrect operation (mis - stepping on the accelerator pedal) has occurred where the accelerator pedal operation amount AP detected by the accelerator sensor 23 is equal to or greater than a predetermined operation amount threshold APv. If an incorrect operation has occurred (Yes), the driving support ECU 10 proceeds with the process to step S135. On the other hand, if no incorrect operation has occurred (No), the driving support ECU 10 proceeds with the process to step S180.

[0064] In step S135, the driving support ECU 10 determines that the execution condition of the automatic brake is satisfied. Next, in step S140, when the driving support ECU 10 determines that the execution condition is satisfied, it refers to the required deceleration map M (Figure 2) based on the relative distance Dr between the host vehicle SV and the obstacle and the relative speed Vr with the obstacle acquired by the surrounding recognition device 30, and sets a PCS required deceleration Gp corresponding to these relative distance Dr and relative speed Vr. Then, the driving support ECU 10 proceeds with the process to step S145.

[0065] In step S145, the driving support ECU 10 determines whether the brake pedal has been depressed (or re - depressed) by the driver. If the brake pedal has not been depressed (No), the driving support ECU 10 advances its process to step S150. On the other hand, if the brake pedal has been depressed (Yes), the driving support ECU 10 advances its process to step S160.

[0066] In step S160, it is determined whether the driver - required deceleration Gd (absolute value) corresponding to the operation amount of the brake pedal is greater than the PCS - required deceleration Gp (absolute value) set in step S140. If the driver - required deceleration Gd is less than or equal to the PCS - required deceleration Gp (No), the driving support ECU 10 advances its process to step S150. On the other hand, if the driver - required deceleration Gd is greater than the PCS - required deceleration Gp (Yes), the driving support ECU 10 advances its process to step S165 and de - activates the automatic brake. In this case, the brake ECU 70 controls the operation of the brake actuator 72 so that the host vehicle SV decelerates at the driver - required deceleration Gd.

[0067] In step S150, the driving support ECU 10 activates the automatic brake by outputting a PCS brake command including the PCS - required deceleration Gp set in step S145 to the brake ECU 70. Thereby, the brake ECU 70 controls the operation of the brake actuator 72 so that the host vehicle SV decelerates at the PCS - required deceleration Gp.

[0068] In step S170, it is determined whether the host vehicle SV has reached a state where it can avoid a collision with an obstacle. When the obstacle moves away from the host vehicle SV, or when the host vehicle SV stops in front of the obstacle, or when using the time to collision (TTC), if the TTC becomes greater than a predetermined end threshold time TTCb (>TTCa), the driving support ECU 10 determines (Yes) that the host vehicle SV has reached a state where it can avoid a collision with the obstacle, and proceeds with the process to step S180. On the other hand, if it is determined that the state where the collision with the obstacle cannot be avoided (No), the driving support ECU 10 returns the process to step S140.

[0069] In step S180, the driving support ECU 10 terminates the PCS control, and then returns from this routine. Thereafter, while the vehicle SV is running, the driving support ECU 10 repeatedly executes the processes of steps S100 to S180.

[0070] According to the present embodiment described in detail above, when the driving support ECU 10 activates the automatic brake by PCS control, based on the relative distance Dr to the obstacle and the relative speed Vr to the obstacle when the execution condition of the automatic brake is satisfied, by referring to the required deceleration map M, a PCS required deceleration Gp corresponding to these relative distance Dr and relative speed Vr is set. In the required deceleration map M, the PCS required deceleration Gp is set to a larger deceleration as the relative distance Dr is shorter and the relative speed Vr is higher, and is set to a smaller deceleration as the relative distance Dr is longer and the relative speed Vr is lower.

[0071] That is, when the execution condition of the automatic brake is satisfied, if the relative distance Dr to the obstacle is long and the relative speed Vr to the obstacle is low, the PCS required deceleration Gp of the automatic brake is configured to be set to a small deceleration. Thereby, it is possible to prevent an excessive deceleration from occurring in the host vehicle SV, and further, it is possible to effectively prevent the host vehicle SV from stopping in front of the obstacle more than necessary, and it becomes possible to surely reduce the discomfort of the driver. Further, when the execution condition of the automatic brake is satisfied, if the relative distance Dr to the obstacle is short and the relative speed Vr to the obstacle is high, the PCS required deceleration Gp of the automatic brake is configured to be set to a large deceleration. Thereby, it becomes possible to surely avoid the host vehicle SV from colliding with the obstacle.

[0072] As described above, the driving support device, the driving support method, and the program according to the present embodiment have been described. However, the present disclosure is not limited to the above embodiment, and various modifications are possible without departing from the object of the present invention.

[0073] For example, in the above embodiment, a plurality of required deceleration maps M may be provided. In this case, it may be configured to select an optimal map from a plurality of maps according to the type of obstacle (for example, automobile, bicycle, human, etc.) that may collide with the host vehicle SV. Further, although the automatic brake has been described as applying a braking force by the brake device 71, when the vehicle SV is equipped with an electric motor, it may be configured to use the regenerative braking force of the electric motor in combination.

[0074] Also, in the above-described embodiment, when collision prediction is performed based on the time to collision (TTC), it is also possible to determine the collision possibility level in two stages. Specifically, when the time to collision (TTC) drops to the first threshold time (TTCw), it is determined that the collision possibility level has reached the initial first level. When the time to collision (TTC) further drops and reaches the second threshold time (TTCa), it may be determined that the collision possibility level has reached the second level, which is higher than the first level. In this case, a warning may be issued when the collision possibility level reaches the first level, and the automatic brake may be activated when the collision possibility level reaches the second level and there is an accidental operation of the accelerator pedal. Also in this case, by referring to the required deceleration map (M) based on the relative distance (Dr) from the obstacle and the relative speed (Vr) with the obstacle when the accidental operation of the accelerator pedal is performed, the PCS required deceleration (Gp) corresponding to these relative distance (Dr) and relative speed (Vr) can be set, and the same operational effects as those of the above-described embodiment can be achieved.

Explanation of Signs

[0075] 1…Driving support device, 10…Driving support ECU, 11…Time to collision calculation unit, 12…Collision prediction unit, 13…Notification control unit, 14…Accidental operation determination unit, 15…Automatic brake control unit, 20…Vehicle state acquisition device, 21…Steering angle sensor, 22…Vehicle speed sensor, 23…Accelerator sensor, 24…Brake sensor, 30…Surrounding recognition device, 31…Front camera, 32…Front millimeter-wave radar, 33…Front lidar, 60…Drive source ECU, 70…Brake ECU, 71…Brake device, SV…Vehicle

Claims

1. A target information acquisition unit that acquires target information including the relative distance and relative speed between a vehicle and a target in front of the vehicle; An operation amount acquisition unit that acquires the operation amount of an accelerator pedal by an occupant of the vehicle; When the relative distance acquired by the target information acquisition unit drops to a predetermined threshold distance, the collision possibility level is determined to have reached a pre-collision stage where there is a possibility that the vehicle will collide with the target if a wrong operation due to the occupant stepping on the accelerator pedal by mistake occurs. And when it is determined that the collision possibility level has reached the pre-collision stage, if an execution condition that the operation amount acquired by the operation amount acquisition unit is equal to or greater than a predetermined operation amount is satisfied, a control unit that executes collision avoidance support control for decelerating the vehicle at a predetermined required deceleration by an automatic brake that automatically activates the brake device of the vehicle; The control unit sets the required deceleration based on the relative distance and the relative speed acquired by the target information acquisition unit when the execution condition is satisfied. A driving support device characterized by the above.

2. When the execution condition is satisfied, the control unit sets the required deceleration to a greater deceleration as the relative distance acquired by the target information acquisition unit is shorter and the relative speed acquired by the target information acquisition unit is higher. The driving support device according to claim 1.

3. When the execution condition is satisfied, the control unit sets the required deceleration to a smaller deceleration as the relative distance acquired by the target information acquisition unit is longer and the relative speed acquired by the target information acquisition unit is lower. The driving support device according to claim 1 or 2.

4. Acquire the relative distance and relative speed between the vehicle and a target in front of the vehicle, Acquire the operation amount of the accelerator pedal by an occupant of the vehicle, When the acquired relative distance drops to a predetermined threshold distance, the collision possibility level is determined to have reached a pre-collision stage where there is a possibility that the vehicle will collide with the target if a wrong operation due to the occupant stepping on the accelerator pedal by mistake occurs. And when it is determined that the collision possibility level has reached the pre-collision stage, if an execution condition that the acquired operation amount is equal to or greater than a predetermined operation amount is satisfied, execute collision avoidance support control for decelerating the vehicle at a predetermined required deceleration by an automatic brake that automatically activates the brake device of the vehicle. Set the required deceleration based on the relative distance and the relative speed acquired when the execution condition is satisfied. A driving support method characterized by this.

5. In the computer of a driving support device, Acquire target information including the relative distance and relative speed between the vehicle and a target in front of the vehicle, Acquire the operation amount of the accelerator pedal by the occupant of the vehicle, When the acquired relative distance decreases to a predetermined threshold distance, determine that the collision possibility level has reached a pre-collision stage where there is a possibility that the vehicle will collide with the target if a misoperation due to the occupant stepping on the accelerator pedal by mistake occurs, and when it is determined that the collision possibility level has reached the pre-collision stage, if an execution condition that the acquired operation amount is equal to or greater than a predetermined operation amount is satisfied, execute collision avoidance support control to decelerate the vehicle at a predetermined required deceleration by automatically operating the brake device of the vehicle, Execute a process of setting the required deceleration based on the relative distance and the relative speed acquired when the execution condition is satisfied. A program characterized by this.

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