Vehicle control device, vehicle control method, and program

Abstract

A vehicle control device (1A, 1B, 1C) comprises: a braking device (40) that brakes an own vehicle (100); and a control device (10) that is configured to start deceleration control for controlling the braking device (40) so that the own vehicle (100) decelerates when it is determined that the likelihood of a collision between the own vehicle (100) and a preceding object (OB), which is an object present in the traveling direction of the own vehicle (100), is high, and to end the deceleration control when a predetermined control-terminating condition is satisfied during the execution of the deceleration control. The control-terminating condition includes a margin degree condition that is satisfied when a margin degree indicating the amount of margin available to avoid a collision between the own vehicle (100) and the preceding object (OB) after the deceleration control is terminated is equal to or greater than a predetermined threshold margin degree.

Description

Vehicle control device, vehicle control method, and program

[0001] The present disclosure relates to a vehicle control device, a vehicle control method, and a program capable of executing deceleration control.

[0002] Patent Document 1 discloses a vehicle control device capable of executing deceleration control. The vehicle control device disclosed in Patent Document 1 activates a braking device to start deceleration control to decelerate the host vehicle when it determines that there is a high possibility of a collision between the host vehicle and a target (hereinafter referred to as a preceding target) present in the host vehicle's traveling direction. This deceleration control ends when a predetermined control termination condition is met. Patent Document 1 exemplifies the predetermined control termination condition as a condition in which the host vehicle's speed falls below the speed of the preceding target.

[0003] JP 2016-1498 A

[0004] The vehicle control device disclosed in Patent Document 1 starts deceleration control when it determines that there is a high possibility of a collision between the host vehicle and a preceding object, and ends the deceleration control when the speed of the host vehicle falls below the speed of the preceding object during execution of the deceleration control. In this case, the possibility of a collision between the host vehicle and the preceding object may increase again after the deceleration control ends depending on the behavior of the preceding object. The vehicle control device disclosed in Patent Document 1 does not take into consideration how to deal with the case where the possibility of a collision increases again after the deceleration control ends, so there is room for improvement in setting the control end condition for the deceleration control.

[0005] An object of the present disclosure is to provide a vehicle control device, a vehicle control method, and a program that can solve the above-mentioned problems.

[0006] A vehicle control device (1A, 1B, 1C) according to the present disclosure includes a braking device (40) that brakes a host vehicle (100), and a control device (10) configured to start deceleration control that controls the braking device (40) so that the host vehicle (100) decelerates when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB) that is an object present in the host vehicle's (100) traveling direction, and to end the deceleration control when a predetermined control end condition is satisfied during execution of the deceleration control. The control end condition includes a margin condition that is satisfied when a margin representing the size of the margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

[0007] According to the vehicle control device of the present disclosure, the deceleration control is terminated when there is a margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated. Therefore, even if the possibility of a collision between the host vehicle and the preceding object increases again after the deceleration control is terminated, it is possible to avoid a collision between the host vehicle and the preceding object with a margin of error.

[0008] The vehicle control device according to the present disclosure includes a braking device (40) that brakes a host vehicle (100), and a control device (10) configured to start deceleration control that controls the braking device (40) to decelerate the host vehicle (100) when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB) that is an object present in the host vehicle's traveling direction, and to terminate the deceleration control when a predetermined control termination condition is satisfied during the execution of the deceleration control. The control device (10) determines that the control termination condition is satisfied when, during the execution of the deceleration control, a relative speed condition is satisfied that is satisfied when a relationship between the speed of the host vehicle (100) and the speed of the preceding object (OB) is such that a collision between the host vehicle (100) and the preceding object (OB) is avoidable, and a margin condition is satisfied that is satisfied when a margin indicating a size of a margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

[0009] According to the vehicle control device of the present disclosure, the control device terminates the deceleration control when, during execution of the deceleration control, the relationship between the speed of the host vehicle and the speed of the preceding target is such that a collision between the host vehicle and the preceding target can be avoided and there is still a margin to avoid a collision between the host vehicle and the preceding target even after the deceleration control is terminated. Therefore, even if the possibility of a collision between the host vehicle and the preceding target increases again after the deceleration control is terminated, it is possible to avoid a collision between the host vehicle and the preceding target with a margin to spare.

[0010] In one aspect of the vehicle control device according to the present disclosure, the control device (10) determines that a margin condition is satisfied when an acceleration condition is satisfied when the acceleration (α0) of the preceding object (OB) is equal to or greater than a predetermined threshold acceleration (αth) during execution of deceleration control. That is, the acceleration condition is the margin condition, and the acceleration (α0) of the preceding object (OB) is the margin. Therefore, according to this aspect, the control termination condition for the deceleration control includes an acceleration condition that is satisfied when the acceleration (α0) of the preceding object (OB) is equal to or greater than the predetermined threshold acceleration (αth). In this case, the acceleration (α0) of the preceding object (OB) may be an acceleration (longitudinal acceleration) acting in the traveling direction (forward / backward direction) of the preceding object (OB).

[0011] If the acceleration (longitudinal acceleration) of the preceding object is equal to or greater than a predetermined threshold acceleration during execution of deceleration control, the preceding object moves away from the host vehicle for which deceleration control is being executed. Therefore, if the acceleration condition is met during execution of deceleration control and the deceleration control is terminated, even if the possibility of a collision between the host vehicle and the preceding object increases again due to the subsequent behavior of the preceding object, a collision between the host vehicle and the preceding object can be avoided with ample time to spare.

[0012] Furthermore, if the acceleration condition is not satisfied, for example, if the preceding target is decelerating, the control termination condition is not satisfied and the deceleration control continues. This effectively prevents a situation in which the possibility of the host vehicle colliding with the preceding target after the termination of the deceleration control increases again due to the termination of the deceleration control when the preceding target is decelerating. Furthermore, it effectively prevents a situation in which the possibility of the host vehicle colliding with the preceding target increases again after the termination of the deceleration control due to the termination of the deceleration control while the preceding target is decelerating, and the deceleration control is resumed, i.e., a situation in which the termination and start of the deceleration control are repeated.

[0013] The threshold acceleration is preferably set so that the margin condition is satisfied when the preceding target has a zero or positive acceleration. In other words, the margin condition may be a condition that is satisfied when the preceding target is not decelerating. This is because if the preceding target is not decelerating during deceleration control, it is considered that the preceding target will not approach the host vehicle that is decelerating due to deceleration control.

[0014] In another aspect of the vehicle control device according to the present disclosure, the control device (10) determines that the margin condition is satisfied when a relative distance condition is satisfied during execution of deceleration control, the relative distance condition being satisfied when the relative distance (Lr) between the host vehicle (100) and the preceding object (OB) is equal to or greater than a predetermined threshold distance (Lth). That is, the relative distance condition is the margin condition, and the relative distance (Lr) is the margin. Therefore, according to this aspect, the control termination condition for the deceleration control includes the relative distance condition being satisfied when the relative distance (Lr) between the host vehicle (100) and the preceding object (OB) is equal to or greater than the predetermined threshold distance (Lth).

[0015] If the relative distance between the host vehicle and the preceding target is equal to or greater than a predetermined threshold distance during execution of deceleration control, a sufficient distance margin is ensured to avoid a collision between the host vehicle and the preceding target even if the deceleration control is terminated. Therefore, if the relative distance condition is met during execution of deceleration control and the deceleration control is terminated, even if the possibility of a collision between the host vehicle and the preceding target increases again due to the behavior of the preceding target thereafter, a sufficient distance margin remains before the host vehicle collides with the preceding target, so a collision between the host vehicle and the preceding target can be avoided with ease.

[0016] In another aspect of the vehicle control device according to the present disclosure, the control device (10) determines that a margin condition is satisfied when a predicted time condition is satisfied during execution of deceleration control, the predicted time condition being satisfied when a predicted time (TTCv) required for the host vehicle (100) to reach the preceding object (OB) when the deceleration of the host vehicle (100) is set to 0 is equal to or greater than a threshold time (TTCvth). That is, the predicted time condition is the margin condition, and the predicted time is the margin. Therefore, according to this aspect, the control termination condition for the deceleration control includes a predicted time condition being satisfied when a predicted time (TTCv) required for the host vehicle (100) to reach the preceding object (OB) when the deceleration of the host vehicle (100) is set to 0 is equal to or greater than the threshold time (TTCvth).

[0017] If the predicted time is equal to or greater than the threshold time during execution of deceleration control, there is sufficient time to avoid a collision between the host vehicle and the preceding object even if the deceleration control is terminated. Therefore, if the predicted time condition is met during execution of deceleration control and the deceleration control is terminated, even if the possibility of a collision between the host vehicle and the preceding object increases again due to the behavior of the preceding object, there is sufficient time before the host vehicle collides with the preceding object, so it is possible to avoid a collision between the host vehicle and the preceding object with ease.

[0018] In another aspect of the vehicle control device according to the present disclosure, the control device (10) determines that the relative speed condition is met when the speed (V1) of the host vehicle (100) is lower than the speed (V0) of the preceding object (OB) by a predetermined speed during deceleration control. This makes it possible to appropriately determine whether a collision between the host vehicle and the preceding object can be avoided based on the speed of the host vehicle and the speed of the preceding object.

[0019] In another aspect of the vehicle control device according to the present disclosure, the control device (10) determines that the control termination condition is satisfied when the relative velocity condition is satisfied, the target velocity condition is satisfied when the velocity (V0) of the preceding target (OB) is equal to or greater than a predetermined lower limit velocity (Vd), and the margin condition is satisfied. According to this, the control termination condition for the deceleration control includes the target velocity condition that is satisfied when the velocity of the preceding target is equal to or greater than the lower limit velocity. Therefore, even if the relative velocity condition and the margin condition are satisfied, the deceleration control is not terminated unless the preceding target is moving at a speed equal to or greater than the lower limit velocity. In other words, the deceleration control is not continued when the relative velocity condition and the margin condition are satisfied and the preceding target is moving at a high speed equal to or greater than the lower limit velocity. Therefore, by continuing the deceleration control when the preceding target and the host vehicle are moving at a relatively high speed, it is possible to avoid the host vehicle colliding with a target (e.g., a following vehicle) moving behind the host vehicle in the same direction as the host vehicle's traveling direction.

[0020] In addition, the vehicle control method according to the present disclosure is a vehicle control method including a start step (S106) of starting deceleration control that controls a braking device (40) of the host vehicle (100) so that the host vehicle (100) decelerates when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB), which is an object present in the traveling direction of the host vehicle (100), and a termination step (S110) of terminating the deceleration control when a predetermined control termination condition is met during execution of the deceleration control, wherein the control termination condition includes a margin condition that is met when a margin representing the size of the margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

[0021] Furthermore, the vehicle control method according to the present disclosure is a vehicle control method including a start step (S106) of starting deceleration control that controls a braking device (40) of the host vehicle (100) so that the host vehicle (100) decelerates when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB), which is an object present in the traveling direction of the host vehicle (100), and a stop step (S110) of terminating the deceleration control when a predetermined control end condition is met during execution of the deceleration control, wherein the control end condition is met when, during execution of the deceleration control, a relative speed condition is met that is met when the relationship between the speed (V1) of the host vehicle (100) and the speed (V0) of the preceding object (OB) is such that a collision between the host vehicle (100) and the preceding object (OB) is avoidable, and a margin condition is met that is met when a margin representing the size of the margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is ended is equal to or greater than a predetermined threshold margin.

[0022] According to these vehicle control methods, the deceleration control is terminated when there is a margin to avoid a collision between the host vehicle and the preceding object after the deceleration control is terminated, so that even if the possibility of a collision between the host vehicle and the preceding object increases again after the deceleration control is terminated, it is possible to avoid a collision between the host vehicle and the preceding object with ample margin.

[0023] In addition, the program according to the present disclosure is a program that causes a computer provided in the host vehicle (100) to execute a start step (S106) of starting deceleration control that controls the braking device (40) of the host vehicle (100) so that the host vehicle (100) decelerates when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB), which is an object present in the traveling direction of the host vehicle (100), and an end step (S110) of ending the deceleration control when a predetermined control end condition is met during the execution of the deceleration control, wherein the control end condition includes a margin condition that is met when a margin representing the size of the margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is ended is equal to or greater than a predetermined threshold margin.

[0024] In addition, the program according to the present disclosure is a program that causes a computer provided in a host vehicle (100) to execute a start step (S106) of starting deceleration control that controls a braking device (40) of the host vehicle (100) so that the host vehicle (100) decelerates when it is determined that there is a high possibility of a collision between the host vehicle (100) and a preceding object (OB), which is an object present in the host vehicle's (100) traveling direction, and a stop step (S110) of ending the deceleration control when a predetermined control end condition is met during execution of the deceleration control. The control end condition is met when, during execution of the deceleration control, a relative speed condition is met that is met when the relationship between the speed (V1) of the host vehicle (100) and the speed (V0) of the preceding object (OB) is such that a collision between the host vehicle (100) and the preceding object (OB) is avoidable, and when a margin condition is met that is met when a margin representing the size of the margin for avoiding a collision between the host vehicle (100) and the preceding object (OB) after the deceleration control is ended is equal to or greater than a predetermined threshold margin.

[0025] By executing these programs on a computer included in the host vehicle, the deceleration control is terminated when there is a margin to avoid a collision between the host vehicle and the preceding object after the deceleration control is terminated. Therefore, even if the possibility of a collision between the host vehicle and the preceding object increases again after the deceleration control is terminated, a collision between the host vehicle and the preceding object can be avoided with ample margin.

[0026] 1 is a diagram showing a schematic configuration of a vehicle control device according to the present disclosure; FIG. 1 is a diagram showing mounting positions of a front radar sensor and a front camera sensor on a host vehicle; FIG. 2 is a diagram showing a predicted driving area of ​​the host vehicle; FIG. 3 is a graph showing an example of a speed change of the host vehicle and a speed change of a preceding target when a conventional vehicle control device executes automatic brake control; FIG. 4 is a flowchart showing an example of an automatic brake control program executed by a CPU of a vehicle control ECU to execute automatic brake control; FIG. 5 is a flowchart showing an example of a control end determination program executed by a CPU according to a first embodiment to set a control end flag F; FIG. 6 is a flowchart showing an example of a control end determination program executed by a CPU according to a second embodiment to set the control end flag F; FIG. 7 is a flowchart showing an example of a control end determination program executed by a CPU according to a third embodiment to set the control end flag F; FIG. 8 is a graph showing the relationship between y and t when the left side of equation (4) is a variable y;

[0027] (First embodiment) A vehicle control device according to the present disclosure is mounted on a vehicle. Hereinafter, a vehicle equipped with a vehicle control device according to the present disclosure is referred to as a host vehicle 100. Therefore, as shown in FIG. 1 , a vehicle control device 1A according to the first embodiment of the present disclosure is mounted on the host vehicle 100.

[0028] The vehicle control device 1A includes a vehicle control ECU 10, an on-board sensor 20, a drive device 30, a braking device 40, and a steering device 50.

[0029] The vehicle control ECU 10 is a control device that includes a microcomputer as its main component. The vehicle control ECU 10 includes a CPU 11, a ROM 12, a RAM 13, a non-volatile memory 14, and an interface 15. The CPU 11 is a processor that realizes various functions by executing instructions (programs, routines) stored in the ROM 12. ECU is an abbreviation for Electronic Control Unit.

[0030] The drive unit 30 generates a drive force and applies the drive force to the drive wheels of the vehicle 100. The drive unit 30 includes a drive ECU 31, a drive actuator 32, a drive source 33, a transmission 34, and a drive force transmission mechanism (not shown) that transmits the drive force to the drive wheels. The drive ECU 31 is electrically connected to the drive actuator 32 so as to be able to control the operation of the drive actuator 32. The drive actuator 32 is configured to be able to adjust the drive force of the drive source 33 by operating.

[0031] The drive ECU 31 controls the operation of the drive actuator 32 to control the drive force generated by the drive source 33. The drive force generated by the drive source 33 is transmitted to the drive wheels of the host vehicle 100 via a transmission 34 and a drive force transmission mechanism. Therefore, the drive ECU 31 can control the drive force of the host vehicle 100 by controlling the drive actuator 32. The drive actuator 32 is also operated by operation of an accelerator pedal 35 provided on the host vehicle 100. Therefore, the host vehicle 100 can generate a drive force according to the amount of operation of the accelerator pedal 35.

[0032] If the drive source 33 is an internal combustion engine, the drive ECU 31 controls the drive force generated by the internal combustion engine. If the vehicle 100 is a hybrid electric vehicle (HEV), the drive ECU 31 controls the drive force generated by either the internal combustion engine or an electric motor, or both, as the drive source 33. If the vehicle 100 is an electric vehicle (BEV), the drive ECU 31 controls the drive force generated by the electric motor, as the drive source 33.

[0033] The braking device 40 applies braking force to the wheels of the host vehicle 100. The braking device 40 includes a braking ECU 41, a braking actuator 42, and a braking mechanism 43. The braking ECU 41 is electrically connected to the braking actuator 42 so as to control the operation of the braking actuator 42. The braking actuator 42 includes a known hydraulic circuit, including a reservoir, an oil pump, and various valve devices (not shown). The braking mechanism 43 includes a brake disc, a caliper, a piston, and brake pads, and generates a frictional braking force when the brake pads are pressed against the brake disc by hydraulic pressure (i.e., braking pressure) supplied from the braking actuator 42. The frictional braking force generated by the braking mechanism 43 brakes the host vehicle 100.

[0034] The brake actuator 42 adjusts the hydraulic pressure (braking pressure) supplied to the brake mechanism 43 in response to instructions from the brake ECU 41. The frictional braking force generated on the wheels changes in response to the braking pressure. Therefore, the brake ECU 41 can control the braking force of the host vehicle 100 by controlling the brake actuator 42. The brake actuator 42 is also activated by operation of a brake pedal 44 provided on the host vehicle 100. Therefore, the host vehicle 100 can generate a braking force in accordance with the amount of operation of the brake pedal 44.

[0035] The steering device 50 is a device for steering the host vehicle 100. The steering device 50 includes a steering ECU 51, a steering actuator 52, and a steering mechanism 53. The steering ECU 51 is electrically connected to the steering actuator 52 so as to control the operation of the steering actuator 52. The steering mechanism 53 includes a steering wheel 53a, a steering shaft 53b, a steering gearbox (not shown), a tie rod (not shown), etc. The steering mechanism 53 is configured to steer the steered wheels by rotating the steering wheel 53a. The steering actuator 52 is, for example, an electric motor, and is connected to the steering mechanism 53 so as to apply power to the steering mechanism 53 for steering the steered wheels. The steering actuator 52 can also be configured to generate a steering assist force that assists the driver in operating the steering wheel 53a. The steering ECU 51 controls the operation of the steering actuator 52, thereby controlling the operation of the steering mechanism 53. Therefore, the steering ECU 51 can control the steering angle of the steered wheels of the host vehicle 100 by controlling the steering actuator 52.

[0036] The on-vehicle sensors 20 include an accelerator pedal operation amount sensor 21 , a brake pedal operation amount sensor 22 , a steering angle sensor 23 , a steering torque sensor 24 , a vehicle momentum detection sensor 25 , and a surrounding information detection sensor 26 .

[0037] The accelerator pedal operation amount sensor 21 detects the amount of operation of the accelerator pedal 35. The accelerator pedal operation amount sensor 21 is electrically connected to the vehicle control ECU 10. The accelerator pedal operation amount sensor 21 transmits information indicating the detected amount of operation of the accelerator pedal 35 to the vehicle control ECU 10. The vehicle control ECU 10 acquires the amount of operation of the accelerator pedal 35 as the accelerator pedal operation amount based on the information received from the accelerator pedal operation amount sensor 21.

[0038] The brake pedal operation amount sensor 22 detects the operation amount of the brake pedal 44. The brake pedal operation amount sensor 22 is electrically connected to the vehicle control ECU 10. The brake pedal operation amount sensor 22 transmits information indicating the detected operation amount of the brake pedal 44 to the vehicle control ECU 10. The vehicle control ECU 10 acquires the operation amount of the brake pedal 44 as the brake pedal operation amount based on the information received from the brake pedal operation amount sensor 22.

[0039] The steering angle sensor 23 detects the rotation angle of the steering shaft 53b relative to the neutral position. The steering angle sensor 23 is electrically connected to the vehicle control ECU 10. The steering angle sensor 23 transmits information indicating the detected rotation angle of the steering shaft 53b to the vehicle control ECU 10. The vehicle control ECU 10 obtains the rotation angle of the steering shaft 53b as the steering angle θ1 based on the information received from the steering angle sensor 23.

[0040] The steering torque sensor 24 detects the torque input by the driver to the steering shaft 53b via the steering wheel 53a. The steering torque sensor 24 is electrically connected to the vehicle control ECU 10. The steering torque sensor 24 transmits information indicating the detected torque to the vehicle control ECU 10. Based on the information received from the steering torque sensor 24, the vehicle control ECU 10 obtains the torque input by the driver to the steering shaft 53b via the steering wheel 53a as the steering torque.

[0041] The vehicle momentum detection sensor 25 detects the momentum of the host vehicle 100. The vehicle momentum detection sensor 25 includes a vehicle speed sensor 251, an acceleration sensor 252, and a yaw rate sensor 253.

[0042] The vehicle speed sensor 251 detects the traveling speed of the host vehicle 100, i.e., the host vehicle speed V1, which is the speed in the traveling direction of the host vehicle 100. The vehicle speed sensor 251 is, for example, a wheel speed sensor that detects the rotation speed of the wheels of the host vehicle 100. The vehicle speed sensor 251 is electrically connected to the vehicle control ECU 10. The vehicle speed sensor 251 transmits information indicating the detected host vehicle speed V1 to the vehicle control ECU 10. The vehicle control ECU 10 acquires the host vehicle speed V1 based on the information received from the vehicle speed sensor 251.

[0043] The acceleration sensor 252 detects acceleration (longitudinal acceleration) acting in the traveling direction (front-rear direction) of the host vehicle 100. The acceleration sensor 252 is electrically connected to the vehicle control ECU 10. The acceleration sensor 252 transmits information representing the detected acceleration to the vehicle control ECU 10. The vehicle control ECU 10 acquires acceleration α1 acting in the traveling direction (front-rear direction) of the host vehicle 100 based on the information received from the acceleration sensor 252. The acceleration sensor 252 detects acceleration of the host vehicle 100 accelerating forward as positive acceleration, and detects acceleration of the host vehicle 100 accelerating backward, i.e., deceleration, as negative acceleration. In this specification, "acceleration" refers to longitudinal acceleration unless otherwise specified.

[0044] The yaw rate sensor 253 detects the yaw rate of the host vehicle 100. The yaw rate sensor 253 is electrically connected to the vehicle control ECU 10. The yaw rate sensor 253 transmits information indicating the detected yaw rate to the vehicle control ECU 10. The vehicle control ECU 10 acquires the yaw rate Y1 of the host vehicle 100 based on the information received from the yaw rate sensor 253.

[0045] The surrounding information detection sensor 26 detects information about the environment around the host vehicle 100. In this embodiment, the surrounding information detection sensor 26 includes a radio wave sensor and an image sensor. In this embodiment, the radio wave sensor is a radar sensor 261 that detects surrounding information using radar as radio waves. In this embodiment, the image sensor is a camera sensor 262. The surrounding information detection sensor 26 may include a sonic sensor such as an ultrasonic sensor (clearance sonar) or an optical sensor such as LiDAR, or may include a ToF sensor (Time of Flight sensor).

[0046] The radar sensor 261 is electrically connected to the vehicle control ECU 10. The radar sensor 261 emits radar (e.g., millimeter-wave radar) and receives radar reflected from objects (reflected waves). The radar sensor 261 transmits object detection information obtained from the emitted radar and the received radar to the vehicle control ECU 10. The radar sensor 261 detects objects present in the vicinity of the host vehicle 100 based on, for example, the relationship between the emitted radar and the received radar, and transmits information about the detected objects to the vehicle control ECU 10 as detection information. The vehicle control ECU 10 acquires information about objects present in the vicinity of the host vehicle 100 based on the detection information received from the radar sensor 261.

[0047] The radar sensor 261 includes a forward radar sensor. FIG. 2 is a diagram showing the mounting positions of the forward radar sensor and a forward camera sensor (described later) on the host vehicle 100. As shown in FIG. 2, the forward radar sensor 261a is mounted approximately at the center of the front end (e.g., the front bumper) of the host vehicle 100, and transmits radar waves to the area ahead of the host vehicle 100 and receives reflected waves from the area ahead of the host vehicle 100. The forward radar sensor 261a detects targets present in the area ahead of the host vehicle 100 based on the relationship between the transmitted waves and the received waves, and transmits information about the detected targets to the vehicle control ECU 10. The vehicle control ECU 10 acquires information about targets present ahead of the host vehicle 100 (in the traveling direction) based on the information received from the forward radar sensor 261a. For example, based on information received from the forward radar sensor 261a, the vehicle control ECU 10 acquires the type of preceding target, which is an object located ahead of the vehicle 100 (in the direction of travel), the relative distance Lr between the vehicle 100 and the preceding target, the relative speed Vr, etc.

[0048] The camera sensor 262 is electrically connected to the vehicle control ECU 10. The camera sensor 262 includes a camera device and an image analysis device. The camera device is, for example, a digital camera incorporating an imaging element configured with a CCD (Charge Coupled Device) or a CIS (CMOS Image Sensor). The camera device captures images of the surrounding area of ​​the host vehicle 100 at a predetermined frame rate and acquires image data. The camera device transmits each image data to the image analysis device. The image analysis device analyzes the acquired image data and acquires information about targets and signs present around the host vehicle 100 from the images, and transmits the information to the vehicle control ECU 10. The vehicle control ECU 10 acquires information about targets and signs present around the host vehicle 100 based on the information received from the image analysis device.

[0049] The camera sensor 262 includes a forward camera sensor. As shown in FIG. 2 , the forward camera sensor 262a is attached to approximately the center of the upper portion of the front windshield of the host vehicle 100 and captures an image of the area ahead of the host vehicle 100 to acquire image data. The forward camera sensor 262a analyzes the acquired image data and acquires information about targets and signs present ahead of the host vehicle 100 (in the direction of travel) from the image, and transmits the information to the vehicle control ECU 10. The vehicle control ECU 10 acquires information about targets and signs present ahead of the host vehicle 100 (in the direction of travel) based on the information received from the forward camera sensor 262a. For example, the vehicle control ECU 10 acquires the lane in which the host vehicle 100 is traveling, the type of preceding target, etc. based on the information received from the forward camera sensor 262a.

[0050] The vehicle control ECU 10 may acquire information about the preceding target by integrating the information received from the front radar sensor 261a and the information received from the front camera sensor 262a.

[0051] The radar sensor 261 may include a rear radar sensor that emits radar behind the vehicle 100, a side radar sensor that emits radar to the side of the vehicle 100, etc. The camera sensor 262 may include a rear camera sensor that captures an image of the area behind the vehicle 100, a side camera sensor that captures an image of the area to the side of the vehicle 100, etc.

[0052] 1, the vehicle control ECU 10 is connected via a controller area network (CAN) to other ECUs, including a drive ECU 31, a braking ECU 41, and a steering ECU 51, so as to be able to transmit and receive information to and from each other. Therefore, each ECU can obtain information obtained by the other ECUs via the CAN.

[0053] Furthermore, the vehicle control device 1A is configured to be able to execute automatic driving control so that the host vehicle 100 performs automatic driving. For example, the vehicle control ECU 10 transmits control signals to the drive ECU 31, the brake ECU 41, and the steering ECU 51 via the CAN, based on information obtained from the on-board sensors 20. The drive ECU 31 controls the drive actuator 32 based on the control signal received from the vehicle control ECU 10. The brake ECU 41 controls the brake actuator 42 based on the control signal received from the vehicle control ECU 10. The steering ECU 51 controls the steering actuator 52 based on the control signal received from the vehicle control ECU 10. This realizes automatic driving.

[0054] (Outline of Operation of Automatic Brake Control) When the host vehicle 100 is performing automatic driving or when the driver is manually driving the host vehicle 100, the vehicle control ECU 10 starts automatic brake control if it determines that there is a high possibility of a collision between the host vehicle 100 and a preceding object OB that is an object present in the traveling direction of the host vehicle 100. This automatic brake control is deceleration control that controls the braking device 40 so that the host vehicle 100 decelerates. Furthermore, the vehicle control ECU 10 is configured to terminate the automatic brake control if a predetermined control termination condition is met during the execution of the automatic brake control. An outline of the operation of this automatic brake control will be described.

[0055] The vehicle control ECU 10 calculates a predicted driving area of ​​the host vehicle 100 while the host vehicle 100 is traveling. FIG. 3 is a diagram showing the predicted driving area of ​​the host vehicle 100. As shown in FIG. 3, the predicted driving area A100 is an area having a width equal to the vehicle width of the host vehicle 100 and centered on a predicted driving path R100 of the host vehicle 100. The predicted driving path R100 is a driving path along which the center of the host vehicle 100 in the vehicle width direction is predicted to travel when the host vehicle 100 travels while maintaining the current steering angle θ1 or yaw rate Y1. Therefore, although the predicted driving path R100 shown in FIG. 3 is linear, it may also be curved depending on the situation.

[0056] The vehicle control ECU 10 calculates a predicted driving path R100, which is a path along which the central portion of the vehicle 100 in the width direction will travel, based on the vehicle speed V1, acceleration α1, and steering angle θ1 (or yaw rate Y1). The vehicle control ECU 10 also calculates a predicted driving area A100 based on the calculated predicted driving path R100 and the vehicle width value of the vehicle 100.

[0057] Based on the information acquired from the front radar sensor 261a and the front camera sensor 262a, the vehicle control ECU 10 determines whether or not a target exists within the predicted traveling area A100, i.e., in the traveling direction of the host vehicle 100. When the vehicle control ECU 10 determines that a target exists within the predicted traveling area A100, the vehicle control ECU 10 sets the target as a preceding target OB, which is a target existing in the traveling direction of the host vehicle 100.

[0058] When a preceding object OB is present, the vehicle control ECU 10 acquires the relative distance Lr between the host vehicle 100 and the preceding object OB and the relative speed Vr, which is the difference between the speed V0 of the preceding object OB and the host vehicle speed V1, based on information acquired from the forward radar sensor 261a and the forward camera sensor 262a. The relative distance Lr and the relative speed Vr can be acquired, for example, based on the relationship between the radar (transmitted wave) emitted by the forward radar sensor 261a and the radar (reflected wave) received by the forward radar sensor 261a. At this time, the vehicle control ECU 10 may also identify the type of the preceding object OB. The preceding object OB may be a vehicle, a motorcycle, or a bicycle.

[0059] Furthermore, the vehicle control ECU 10 calculates a predicted arrival time TTC for the preceding object OB. The predicted arrival time TTC is the time that is predicted to be required for the host vehicle 100 to arrive at the preceding object OB. The predicted arrival time TTC can be calculated by dividing the relative distance Lr by the absolute value of the relative speed Vr.

[0060] When the relative speed Vr is constant, the predicted arrival time TTC becomes shorter as the host vehicle 100 approaches the preceding object OB. Therefore, the predicted arrival time TTC is an index value (collision possibility index value) that indicates the possibility that the host vehicle 100 will collide with the preceding object OB, and the shorter the predicted arrival time TTC, the higher the possibility of collision between the host vehicle 100 and the preceding object OB.

[0061] The vehicle control ECU 10 determines whether the predicted arrival time TTC is equal to or shorter than the collision determination time TTCth. If the vehicle control ECU 10 determines that the predicted arrival time TTC is equal to or shorter than the collision determination time TTCth, the vehicle control ECU 10 determines that there is a high possibility of a collision between the host vehicle 100 and the preceding object OB. If there is a high possibility of a collision between the host vehicle 100 and the preceding object OB, the vehicle control ECU 10 starts automatic brake control.

[0062] When the automatic brake control is started, the vehicle control ECU 10 outputs a command signal to the brake ECU 41 to forcibly brake the host vehicle 100. This causes the brake actuator 42 to operate and forcibly brake the host vehicle 100. In this case, the host vehicle 100 may be braked with a constant braking force, or may be braked with a braking force that varies depending on the relative distance Lr or the relative speed Vr.

[0063] The vehicle control ECU 10 determines whether a predetermined control termination condition is satisfied during execution of automatic brake control. The vehicle control ECU 10 is configured to terminate the automatic brake control when it is determined that the control termination condition is satisfied. Here, a conventional vehicle control device determines whether a relative speed condition is satisfied during execution of automatic brake control, and determines that the control termination condition is satisfied when the relative speed condition is satisfied. The relative speed condition is satisfied when the relationship between the current speed V0 of the preceding object OB and the host vehicle speed V1 is such that a collision between the host vehicle 100 and the preceding object OB can be avoided. For example, when the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by a predetermined speed, i.e., when the relative speed Vr (= V0 - V1) is positive, the preceding object OB moves away from the host vehicle 100, making it possible to avoid a collision between the host vehicle 100 and the preceding object OB. Therefore, in such a case, the relative speed condition is satisfied. If the preceding object OB is a stationary object, the relative velocity Vr is negative or 0, and therefore the relative velocity condition is not met.

[0064] However, if automatic brake control is terminated when the relative speed condition is met, it is conceivable that the effect of executing automatic brake control may not be fully realized. This will be explained. FIG. 4 is a graph showing an example of the speed change of the host vehicle 100 and the speed change of the preceding object OB when automatic brake control is executed by a conventional vehicle control device. The vertical axis of FIG. 4 represents speed, and the horizontal axis represents time. The solid line L1 in FIG. 4 represents the speed change of the host vehicle 100, and the dashed line L2 in FIG. 4 represents the speed change of the preceding object OB. As shown in FIG. 4 , between times t0 and t1, the host vehicle 100 travels at a constant speed Va. Meanwhile, the preceding object OB, which was traveling at a constant speed Va before time t0, has been decelerating at a predetermined deceleration D0 since time t0. As a result, the speed of the preceding object OB decreases from time t0.

[0065] Therefore, between times t0 and t1, the host vehicle 100 approaches the preceding object OB, the relative speed Vr increases in the negative direction, and the relative distance Lr decreases. Therefore, the predicted arrival time TTC (= Lr / |Vr|) continues to decrease between times t0 and t1. Then, at time t1, the determination condition is met that the predicted arrival time TTC is equal to or less than the collision determination time TTCth. Therefore, automatic brake control is initiated at time t1.

[0066] Between times t1 and t3, automatic brake control is executed. During execution of the automatic brake control, the preceding object OB continues to decelerate at a predetermined deceleration D0. Furthermore, the host vehicle 100 decelerates at a deceleration D1 greater than the deceleration D0 due to the automatic brake control. Therefore, between times t1 and t2, the absolute value of the relative speed Vr decreases, and at time t2, the relative speed Vr becomes 0, and the speed of the host vehicle 100 and the speed of the preceding object OB match. Thereafter, between times t2 and t3, the relative speed Vr increases in the positive direction. Then, at time t3, the speed of the host vehicle 100 falls below the speed of the preceding object OB by a predetermined speed. This establishes the relative speed condition, and execution of the automatic brake control ends.

[0067] Between times t3 and t5, automatic brake control is not executed. Therefore, the host vehicle 100 travels at a constant speed. Meanwhile, the preceding object OB continues to decelerate at deceleration D0. Therefore, between times t3 and t4, the absolute value of the relative speed Vr decreases, and at time t4, the relative speed Vr becomes 0, and the speed of the host vehicle 100 and the speed of the preceding object OB match. Thereafter, between times t4 and t5, the relative speed increases in the negative direction and the relative distance Lr decreases. Therefore, the predicted arrival time TTC (= Lr / |Vr|) continues to decrease between times t4 and t5. Then, at time t5, the determination condition that the predicted arrival time TTC is equal to or less than the collision determination time TTCth is again met. Therefore, automatic brake control is initiated again at time t5.

[0068] In this way, when the behavior of the preceding object OB is such that it continues to decelerate even after the end of the automatic brake control, if the execution of the automatic brake control is terminated solely because the relative speed condition is satisfied, there is a high possibility that the host vehicle 100 will again approach the preceding object OB and collide with it. Alternatively, the predicted arrival time TTC will again become less than the collision determination time TTCth, and the automatic brake control will be restarted. In other words, the automatic brake control will repeatedly start and end. The repeated start and end of the automatic brake control means that the control termination condition for the automatic brake control is inappropriate.

[0069] Furthermore, since the relative speed condition is satisfied when the relationship between the speed of the host vehicle 100 and the speed of the preceding object OB is a predetermined relationship, it may be satisfied even when the relative distance Lr between the host vehicle 100 and the preceding object OB is extremely short. In this case, the predicted arrival time TTC is short at the time when the automatic brake control is terminated. Therefore, if the preceding object OB continues to decelerate after the automatic brake control is terminated, the driver of the host vehicle 100 may not have enough time to perform a driving operation to avoid a collision between the host vehicle 100 and the preceding object OB.

[0070] In contrast, in this embodiment, the control termination conditions for the automatic brake control include a margin condition. Specifically, if the relative speed condition and the margin condition are both satisfied during the execution of the automatic brake control, the control termination condition is satisfied and the execution of the automatic brake control is terminated. In other words, even if the relative speed condition is satisfied during the execution of the automatic brake control, if the margin condition is not satisfied, the automatic brake control continues.

[0071] The margin condition is a condition that is met when the margin, which indicates the size of the margin for avoiding a collision between the host vehicle 100 and the preceding object OB after the automatic brake control is terminated, is equal to or greater than a predetermined threshold margin. The margin condition can also be said to be a condition that is met when the host vehicle 100 can avoid the collision with the preceding object OB with ease, even if the possibility of the host vehicle 100 colliding with the preceding object OB increases after the automatic brake control is terminated.

[0072] The margin condition is not limited to a condition that represents the relative relationship between the preceding object OB and the host vehicle 100. The margin condition may also be a condition that represents the behavior of the preceding object OB. For example, the margin condition may be set to a condition that the preceding object OB is accelerating, specifically, an acceleration condition that the acceleration (longitudinal acceleration) of the preceding object OB is equal to or greater than a predetermined threshold acceleration. If the preceding object OB is accelerating at the time the automatic brake control is terminated, even if the relative distance Lr between the host vehicle 100 and the preceding object OB at that time is short, the relative distance Lr is expected to increase thereafter. In other words, the preceding object OB moves away from the host vehicle 100. Therefore, even if the automatic brake control is terminated in this case, the possibility of a collision between the host vehicle 100 and the preceding object OB thereafter is low. Furthermore, if the behavior of the preceding object OB changes after the automatic brake control is terminated, for example, if the preceding object OB suddenly brakes, it is possible that the host vehicle 100 will approach the preceding object OB, again increasing the possibility of a collision between the host vehicle 100 and the preceding object OB. However, because the preceding object OB was accelerating at the time the automatic brake control was terminated, the preceding object OB will have temporarily moved away from the host vehicle 100. Even if the preceding object OB then suddenly brakes, there will be ample time and distance to close the distance. Therefore, even if the preceding object OB suddenly brakes after the automatic brake control is terminated, the driver of the host vehicle 100 can perform driving operations to avoid a collision with the preceding object OB, thereby allowing ample time to avoid a collision. Therefore, the acceleration of the preceding object OB is a margin that indicates the amount of margin to avoid a collision between the vehicle 100 and the preceding object OB after the end of automatic brake control, and the acceleration condition in which the acceleration of the preceding object OB is greater than or equal to a threshold acceleration can be a margin condition.

[0073] Furthermore, if the preceding object OB is not decelerating, even if the execution of the automatic brake control is terminated at that time, the host vehicle 100 will not subsequently approach the preceding object OB. Therefore, even if the automatic brake control is terminated in this case, the possibility of a collision between the host vehicle 100 and the preceding object OB is low. It is also possible that the behavior of the preceding object OB changes after the automatic brake control is terminated, for example, if the host vehicle 100 brakes suddenly, which may again increase the possibility of a collision between the host vehicle 100 and the preceding object OB. However, since the preceding object OB is not decelerating at the time the automatic brake control is terminated, there is sufficient time for the behavior of the preceding object OB to change. Therefore, even if the preceding object OB brakes suddenly after the automatic brake control is terminated, the driver of the host vehicle 100 can perform driving operations to avoid a collision with the preceding object OB, thereby allowing for a sufficient amount of time to avoid a collision. Therefore, the condition that the preceding object OB is not decelerating, i.e., the acceleration (longitudinal acceleration) of the preceding object OB is 0 m / s ２ The condition of being equal to or greater than this can be a margin condition.

[0074] In this embodiment, the margin condition is an acceleration condition that the acceleration (longitudinal acceleration) of the preceding object OB is equal to or greater than a predetermined threshold acceleration. In this case, after determining that the relative speed condition is met, the vehicle control ECU 10 calculates the acceleration (longitudinal acceleration) α0 of the preceding object OB.

[0075] After calculating the acceleration α0 of the preceding object OB, the vehicle control ECU 10 determines whether the calculated acceleration α0 is equal to or greater than a predetermined threshold acceleration αth. The threshold acceleration αth is preferably set so that the margin condition is met when the acceleration of the preceding object OB is 0 or positive. The threshold acceleration αth is, for example, 0 m / s ２ In this case, the vehicle control ECU 10 determines whether the preceding object OB is decelerating. The threshold acceleration αth may be set in consideration of the variation in the acceleration α0 of the preceding object OB or the variation in the estimation accuracy of the acceleration α0. For example, if the average value of the acceleration α0 of the preceding object OB is 0 m / s ２Even if the acceleration α0 is greater than the threshold acceleration αth, the acceleration α0 may become positive or negative depending on the variation in the acceleration α0 or the variation in the estimation accuracy of the acceleration α0. In this case, the threshold acceleration αth can be set to the lower limit of the acceleration α0 that varies within the range of variation. For example, if the variation in the estimation accuracy of the acceleration α0 is ±0.5 m / s ２ If the acceleration threshold αth is about −0.5 m / s ２ In this way, the threshold acceleration αth may be set to a negative value when the variation in the acceleration α0 of the preceding object OB or the variation in the estimation accuracy of the acceleration α0 is taken into consideration.

[0076] If the acceleration α0 of the preceding object OB is less than the threshold acceleration αth, for example, if the preceding object OB is decelerating, the vehicle control ECU 10 determines that the margin condition is not met. In this case, the vehicle control ECU 10 determines that the control termination condition for the automatic brake control is not met because the margin condition is not met even if the relative speed condition is met, and continues the automatic brake control. On the other hand, if the acceleration α0 of the preceding object OB is equal to or greater than the threshold acceleration αth, for example, if the preceding object OB is not decelerating, the vehicle control ECU 10 determines that the margin condition is met. In this case, the vehicle control ECU 10 determines that the control termination condition for the automatic brake control is met because both the relative speed condition and the margin condition are met, and terminates the execution of the automatic brake control.

[0077] 5 is a flowchart showing an example of an automatic brake control program executed by the CPU 10a (processor) of the vehicle control ECU 10. This program is repeatedly executed at predetermined short intervals while the host vehicle 100 is traveling.

[0078] When the automatic brake control program is started, the CPU 10a first determines whether or not a target object has been detected within the predicted traveling area A100 of the host vehicle 100 in step (hereinafter, step will be abbreviated as S) 101 of Fig. 5. If the CPU 10a does not detect a target object, or if the CPU 10a detects a target object but the target object is outside the predicted traveling area A100 (S101: No), the CPU 10a temporarily terminates this program. On the other hand, if the CPU 10a detects a target object within the predicted traveling area A100 of the host vehicle 100 (S101: Yes), the processing executed by the CPU 10a proceeds to S102.

[0079] In S102, the CPU 10a sets the detected object as the preceding object OB. Next, in S103, the CPU 10a acquires the relative speed Vr and the relative distance Lr. Next, in S104, the CPU 10a calculates a predicted time until the host vehicle 100 reaches the preceding object OB as a predicted arrival time TTC. Next, in S105, the CPU 10a determines whether the calculated predicted arrival time TTC is equal to or shorter than a predetermined collision determination time TTCth. If the predicted arrival time TTC is greater than the collision determination time TTCth (S105: No), the CPU 10a temporarily terminates this program. On the other hand, if the predicted arrival time TTC is equal to or shorter than the collision determination time TTCth (S105: Yes), the CPU 10a determines that there is a high possibility of a collision between the host vehicle 100 and the preceding object OB. In this case, the process proceeds to S106.

[0080] In S106, the CPU 10a starts automatic brake control (start step). Next, in S107, the CPU 10a calculates a required deceleration ΔDreq. The required deceleration ΔDreq may be a fixed value or a variable value that changes depending on the relative speed Vr or the relative distance Lr. Then, the process proceeds to S108.

[0081] In S108, the CPU 10a outputs a deceleration command signal to the brake ECU 41 to control the brake actuator 42 so that the deceleration of the host vehicle 100 coincides with the requested deceleration ΔDreq. As a result, the brake ECU 41 controls the brake actuator 42 so that the deceleration coincides with the requested deceleration ΔDreq. As a result, the host vehicle 100 decelerates. Then, the process proceeds to S109.

[0082] In S109, the CPU 10a determines whether the control end flag F is set to 1. The control end flag F is set to 1 if the control end condition for the automatic brake control is satisfied, and is set to 0 if the control end condition is not satisfied. If the control end flag F is not set to 1, i.e., if the control end flag F is set to 0 (S109: No), the CPU 10a determines that the control end condition for the automatic brake control is not satisfied, and the process returns to S107. In this case, the CPU 10a again calculates the requested deceleration ΔDreq (S107) and outputs a deceleration command signal (S108). This allows the automatic brake control to continue. On the other hand, if the control end flag F is set to 1 (S109: Yes), the CPU 10a determines that the control end condition for the automatic brake control is satisfied, and the process proceeds to S110. In S110, the CPU 10a terminates the automatic brake control (termination step). This ends the forced deceleration of the host vehicle 100. The CPU 10a then temporarily terminates this program.

[0083] By the CPU 10a executing the above-described automatic brake control program, when the predicted arrival time TTC until the host vehicle 100 reaches the preceding object OB becomes equal to or shorter than the collision determination time TTCth, i.e., when it is determined that there is a high possibility of a collision between the host vehicle 100 and the preceding object OB, automatic brake control is initiated and the host vehicle 100 decelerates. Furthermore, if the control end flag F is not set to 1 during execution of the automatic brake control, it is determined that the control end condition is not met and the automatic brake control continues. If the control end flag F is set to 1 during execution of the automatic brake control, it is determined that the control end condition is met and the execution of the automatic brake control is terminated.

[0084] 6 is a flowchart showing an example of a control end determination program executed by the CPU 10a to set the control end flag F. This control end determination program is executed when the automatic brake control is started in S106 of FIG.

[0085] When the control end determination program is started, the CPU 10a first determines whether the host vehicle speed V1 is 0 km / H, i.e., whether the host vehicle 100 is stopped, in S201 of Fig. 6. If the host vehicle 100 is stopped (S201: Yes), the process proceeds to S206. On the other hand, if the host vehicle 100 is not stopped (S201: No), the process proceeds to S202.

[0086] In S202, the CPU 10a determines whether the host vehicle speed V1 is equal to or less than the speed V0 of the preceding object OB minus a predetermined reference speed Vs. That is, in S202, the CPU 10a determines whether the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by a predetermined reference speed Vs (e.g., 4 km / H) or more. The condition shown in S202, i.e., the condition that the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by the reference speed Vs or more, is the relative speed condition. The speed V0 can be calculated by adding the relative speed Vr (= V0 - V1) to the host vehicle speed V1. If the host vehicle speed V1 is not lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S202: No), the CPU 10a determines that the relative speed condition is not met, and the process proceeds to S207. On the other hand, if the vehicle speed V1 is lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S202: Yes), the CPU 10a determines that the relative speed condition is met, and the process proceeds to S203.

[0087] In S203, the CPU 10a determines whether the speed V0 of the preceding object OB is equal to or greater than a predetermined lower limit speed Vd. The lower limit speed Vd is set in advance. The lower limit speed Vd can be set to any positive speed. The lower limit speed Vd can be set to a speed within a range of 8 km / H to 12 km / H, for example. The lower limit speed Vd can be set to 10 km / H, for example. If the speed V0 of the preceding object OB is less than the lower limit speed Vd (S203: No), the process proceeds to S207. On the other hand, if the speed V0 of the preceding object OB is equal to or greater than the lower limit speed Vd (S203: Yes), the process proceeds to S204.

[0088] In S204, the CPU 10a calculates the acceleration α0 of the preceding object OB. The acceleration α0 is the acceleration acting in the forward / backward direction (travel direction) of the preceding object OB. The acceleration α0 can be calculated, for example, based on the amount of change over time in the velocity V0 of the preceding object OB. After calculating the acceleration α0, the process proceeds to S205.

[0089] In S205, the CPU 10a determines whether the acceleration α0 is equal to or greater than a threshold acceleration αth. The threshold acceleration αth is set in advance. The threshold acceleration αth can be set to a value that results in a Yes result in S205 when the acceleration α0 is 0 or positive. The threshold acceleration αth can be set to a positive acceleration. The threshold acceleration αth is set to 0 m / s ２ The threshold acceleration αth can be set to 0 m / s ２ In this case, the judgment in S205 is to determine whether the preceding object OB is decelerating. In addition, the threshold acceleration αth can be set to a negative acceleration within a range that takes into consideration the variation in the acceleration α0 or the variation in the estimation accuracy of the acceleration α0. For example, if the variation in the estimation accuracy of the acceleration α0 is ±0.5 m / s, ２ If so, set the threshold acceleration αth to −0.5 m / s ２The condition shown in S205, i.e., the condition that the acceleration α0 of the preceding object OB is equal to or greater than the threshold acceleration αth, is an acceleration condition as a margin condition, and the acceleration α0 of the preceding object OB is a margin that indicates the amount of margin for avoiding a collision between the host vehicle 100 and the preceding object OB. If the acceleration α0 is less than the threshold acceleration αth (S205: No), the CPU 10a determines that the margin condition (acceleration condition) is not met, and the process proceeds to S207. On the other hand, if the acceleration α0 is equal to or greater than the threshold acceleration αth (S205: Yes), the CPU 10a determines that the margin condition (acceleration condition) is met, and the process proceeds to S206.

[0090] In S206, the CPU 10a determines that the control termination condition for the automatic brake control is met, and sets the control termination flag F to 1. Thereafter, the CPU 10a terminates this program. In addition, in S207, the CPU 10a determines that the control termination condition for the automatic brake control is not met, and sets the control termination flag to 0. Thereafter, the CPU 10a terminates this program.

[0091] When the host vehicle 100 stops due to the CPU 10a executing the control termination determination program, the control termination flag F is set to 1. In other words, the control termination condition is met. If the host vehicle 100 stops while the automatic brake control is being executed, there is no point in continuing the automatic brake control any further, so the automatic brake control is terminated. In this case, the stop maintenance control is continued thereafter so that the host vehicle 100 remains stopped.

[0092] Furthermore, by executing the above-described control termination determination program, the CPU 10a sets the control termination flag F to 1 and establishes the control termination condition when all of the following conditions are met during execution of the automatic brake control: the vehicle speed V1 is lower than the speed V0 of the preceding target OB by at least a reference speed Vs (relative speed condition); the speed V0 of the preceding target OB is equal to or greater than a lower limit speed Vd (target speed condition); and the acceleration α0 of the preceding target OB is equal to or greater than a threshold acceleration αth (acceleration condition). Of the above conditions, the target speed condition is established to prevent a vehicle following the host vehicle 100 from contacting the host vehicle 100 by continuing the automatic brake control when the preceding target OB is traveling at a speed equal to or greater than a predetermined speed (e.g., at a speed equal to or greater than 10 km / h). Therefore, the target speed condition may be omitted if contact between the vehicle following the host vehicle 100 and the host vehicle 100 is not a consideration, or if it is clear that no vehicle following the host vehicle 100 exists.

[0093] As described above, according to this embodiment, the control termination conditions for the automatic brake control include not only the relative velocity condition but also the margin condition. In this embodiment, the margin condition is that the acceleration α0 of the preceding object OB is equal to or greater than a predetermined threshold acceleration αth, for example, α0 is 0 m / s ２ The acceleration condition for the preceding object OB is that the acceleration is equal to or greater than 0.05°C. By including such a margin condition (acceleration condition) in the control termination condition, the preceding object OB will not move away from the host vehicle 100 or approach the host vehicle 100 after the automatic brake control is terminated. Therefore, even if the possibility of a collision between the host vehicle 100 and the preceding object OB increases again due to the host vehicle 100 suddenly braking after the automatic brake control is terminated, the driver of the host vehicle 100 can execute a driving operation to avoid a collision with the preceding object OB. This makes it possible to avoid a collision between the host vehicle 100 and the preceding object OB with ample time to spare. Therefore, the automatic brake control can be terminated appropriately and safely.

[0094] Furthermore, if the acceleration condition of the preceding object OB is not satisfied, for example, if the preceding object OB is decelerating, the control termination condition is not satisfied, and the deceleration control continues. Therefore, it is possible to effectively prevent a situation in which the possibility of the host vehicle 100 colliding with the preceding object OB after the termination of the deceleration control increases again due to the termination of the deceleration control when the preceding object OB is decelerating. Furthermore, by terminating the deceleration control while the preceding object OB is decelerating, the relative distance Lr between the host vehicle 100 and the preceding object OB decreases after the termination of the deceleration control, which effectively prevents the deceleration control from being resumed, i.e., the repeated termination and start of the deceleration control.

[0095] In the first embodiment, an example is described in which the margin condition, which is one of the control termination conditions for the automatic brake control, is the acceleration condition that the acceleration α0 of the preceding object OB is equal to or greater than the threshold acceleration αth. In the second embodiment, an example is described in which the margin condition includes the acceleration condition and a relative distance condition that the relative distance Lr between the host vehicle 100 and the preceding object OB is equal to or greater than the threshold distance Lth.

[0096] The vehicle control device according to the second embodiment is mounted on the vehicle 100, similar to the vehicle control device according to the first embodiment. The vehicle control device according to the second embodiment has the configuration shown in Fig. 1. Specifically, the vehicle control device 1B according to the second embodiment has a vehicle control ECU 10, an on-board sensor 20, a drive device 30, a braking device 40, and a steering device 50. Details of these configurations have been explained in the first embodiment, so explanations thereof will be omitted.

[0097] (Overview of Operation of Automatic Brake Control) The vehicle control ECU 10 of the vehicle control device 1B according to the second embodiment initiates automatic brake control when it determines that there is a high possibility of a collision between the host vehicle 100 and a preceding object OB present in the traveling direction of the host vehicle 100. The vehicle control ECU 10 is also configured to terminate the automatic brake control when a predetermined control termination condition is met during execution of the automatic brake control. The predetermined control termination condition includes a margin condition. Therefore, if the margin condition is not met, the control termination condition is not met, and the automatic brake control continues. On the other hand, if the margin condition and other necessary conditions (such as a relative speed condition) are met, the control termination condition is met, and the automatic brake control is terminated. The overview of the operation of this automatic brake control is basically the same as the overview of the operation of the automatic brake control executed by the vehicle control ECU 10 of the vehicle control device 1A according to the first embodiment. However, the margin condition used as the control termination condition for the automatic brake control differs from that of the first embodiment.

[0098] As described in the first embodiment, the margin condition is a condition that is met when the margin, which indicates the amount of margin for avoiding a collision between the host vehicle 100 and the leading object OB after the automatic brake control is terminated, is equal to or greater than a predetermined threshold margin. Here, if the relative distance Lr between the host vehicle 100 and the leading object OB is long, even if the automatic brake control is terminated at that time, there is a distance margin until the host vehicle 100 and the leading object OB collide. Therefore, if the relative distance Lr is long, it can be said that there is a margin for avoiding a collision between the host vehicle 100 and the leading object OB even if the automatic brake control is terminated at that time. Furthermore, even if the leading object OB suddenly brakes after the automatic brake control is terminated, if the relative distance Lr is long, the driver of the host vehicle 100 can avoid the collision with the leading object OB with ample margin by performing a driving operation to avoid a collision with the leading object OB. In this way, the relative distance Lr is a margin that represents the margin to avoid a collision between the vehicle 100 and the preceding object OB after the end of automatic brake control, and the relative distance condition that the relative distance Lr is greater than or equal to a predetermined distance can be a margin condition.

[0099] In this embodiment, the margin condition is an acceleration condition and a relative distance condition that the relative distance Lr is equal to or greater than a predetermined threshold distance Lth. In this case, the vehicle control ECU 10 determines that the margin condition is satisfied if either the acceleration condition or the relative distance condition is satisfied. Specifically, to determine whether the margin condition is satisfied, the vehicle control ECU 10 first determines whether the acceleration condition is satisfied. If the acceleration condition is satisfied, the vehicle control ECU 10 determines that the margin condition is satisfied. If the acceleration condition is not satisfied, the vehicle control ECU 10 next determines whether the relative distance condition is satisfied. In this case, the vehicle control ECU 10 determines whether the relative distance Lr is equal to or greater than the threshold distance Lth. If the relative distance Lr is less than the threshold distance Lth, the vehicle control ECU 10 determines that the relative distance condition is not satisfied. On the other hand, if the relative distance Lr is equal to or greater than the threshold distance Lth, the vehicle control ECU 10 determines that the relative distance condition is satisfied. If the relative distance condition is satisfied, the vehicle control ECU 10 determines that the margin condition is satisfied. If neither the acceleration condition nor the relative distance condition is satisfied, the vehicle control ECU 10 determines that the margin condition is not satisfied.

[0100] The threshold distance Lth can be preset as a lower limit (minimum value) of the distance that allows the driver of the host vehicle 100 to avoid a collision with the preceding object OB by performing a predetermined driving operation even if the host vehicle 100 approaches the preceding object OB after the automatic brake control is terminated, increasing the likelihood of a collision between the host vehicle 100 and the preceding object OB. The threshold distance Lth may be a fixed value or a variable value that changes depending on the host vehicle speed V1 at the time the automatic brake control is terminated. Note that the predetermined driving operation for avoiding a collision between the host vehicle 100 and the preceding object OB includes an operation in which the driver operates the brake pedal 44 to brake the host vehicle 100 and thereby stop the host vehicle 100 before colliding with the preceding object OB, and an operation in which the driver operates the steering wheel 53a to change the driving route from a route that will result in a collision with the preceding object OB to a route that will not result in a collision.

[0101] (Specific Operation) In the second embodiment, the automatic brake control program executed by the CPU 10a of the vehicle control ECU 10 to perform the automatic brake control is the same as the flowchart shown in Fig. 5. Therefore, a description of the automatic brake control program according to this embodiment will be omitted.

[0102] In the second embodiment, the CPU 10a also executes the automatic brake control program shown in Figure 5, causing the vehicle control ECU 10 to initiate automatic brake control when the predicted arrival time TTC of the host vehicle 100 to reach the preceding object OB becomes equal to or shorter than the collision determination time TTCth, i.e., when the possibility of a collision between the host vehicle 100 and the preceding object OB increases. This causes the host vehicle 100 to decelerate. Furthermore, if the control end flag F is not set to 1 during execution of the automatic brake control, the vehicle control ECU 10 determines that the control end condition is not met and continues the automatic brake control. Furthermore, if the control end flag F is set to 1 during execution of the automatic brake control, the vehicle control ECU 10 determines that the control end condition is met and ends execution of the automatic brake control.

[0103] 7 is a flowchart showing an example of a control termination condition determination program executed by the CPU 10a of the vehicle control ECU 10 to set the control termination flag F. When execution of this program starts, the CPU 10a first determines in S301 of FIG. 7 whether the host vehicle speed V1 is 0 km / H, i.e., whether the host vehicle 100 is stopped. If the host vehicle 100 is stopped (S301: Yes), the process executed by the CPU 10a proceeds to S308. On the other hand, if the host vehicle 100 is not stopped (S301: No), the process proceeds to S302.

[0104] In S302, the CPU 10a determines whether the host vehicle speed V1 is equal to or less than the speed V0 of the preceding object OB minus a predetermined reference speed Vs. That is, in S302, the CPU 10a determines whether the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by the predetermined reference speed Vs or more. The condition shown in S302 is the relative speed condition. If the host vehicle speed V1 is not lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S302: No), the CPU 10a determines that the relative speed condition is not met, and the process proceeds to S309. On the other hand, if the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S302: Yes), the CPU 10a determines that the relative speed condition is met, and the process proceeds to S303.

[0105] In S303, the CPU 10a determines whether the speed V0 of the preceding target OB is equal to or greater than a predetermined lower limit speed Vd. The lower limit speed Vd is set in advance. The lower limit speed Vd can be set to any positive speed. The lower limit speed Vd can be set to a speed within a range of 8 km / H to 12 km / H, for example. The lower limit speed Vd can be set to 10 km / H, for example. If the speed V0 of the preceding target OB is less than the lower limit speed Vd (S303: No), the process proceeds to S309. On the other hand, if the speed V0 of the preceding target OB is equal to or greater than the lower limit speed Vd (S303: Yes), the process proceeds to S304. The condition shown in S303 is the target speed condition.

[0106] In S304, the CPU 10a calculates the acceleration α0 of the preceding object OB. The acceleration α0 is the acceleration acting in the forward / backward direction (travel direction) of the preceding object OB. The acceleration α0 can be calculated based on the amount of change over time in the velocity V0 of the preceding object OB. After calculating the acceleration α0, the process proceeds to S305.

[0107] In S305, the CPU 10a determines whether the acceleration α0 is equal to or greater than a threshold acceleration αth. The threshold acceleration αth is set in advance. The threshold acceleration αth can be set to any acceleration. The threshold acceleration αth is 0 m / s ２The threshold acceleration can be set to a positive acceleration. The condition shown in S305 is the acceleration condition as the margin condition. If the acceleration α0 is less than the threshold acceleration αth (S305: No), the CPU 10a determines that the acceleration condition is not met, and the process proceeds to S306. On the other hand, if the acceleration α0 is equal to or greater than the threshold acceleration αth (S305: Yes), the CPU 10a determines that the acceleration condition is met, and the process proceeds to S308.

[0108] In S306, the CPU 10a acquires the relative distance Lr, which is the distance between the host vehicle 100 and the preceding object OB, based on information from the forward radar sensor 261a. Next, in S307, the CPU 10a determines whether the relative distance Lr is equal to or greater than a threshold distance Lth. The threshold distance Lth can be preset as a distance that allows a sufficient margin of error to be avoided even if the likelihood of a collision between the host vehicle 100 and the preceding object OB increases after the automatic brake control is terminated. The threshold distance Lth can be set, for example, within a range of 8 m to 12 m. The threshold distance Lth can be set, for example, to 10 m. Furthermore, the threshold distance Lth can be set to vary depending on the host vehicle speed V1, for example, so that the faster the host vehicle speed V1, the longer the distance. The condition shown in S307 is a relative distance condition that serves as a margin of error condition. If the relative distance Lr is less than the threshold distance Lth (S307: No), the CPU 10a determines that the relative distance condition is not met, and the process proceeds to S309. On the other hand, if the relative distance Lr is equal to or greater than the threshold distance Lth (S307: Yes), the CPU 10a determines that the relative distance condition is met, and the process proceeds to S308.

[0109] In S308, the CPU 10a determines that the control termination condition for the automatic brake control is met, and sets the control termination flag F to 1. Thereafter, the CPU 10a terminates this program. In addition, in S309, the CPU 10a determines that the control termination condition for the automatic brake control is not met, and sets the control termination flag F to 0. Thereafter, the CPU 10a terminates this program.

[0110] By executing the above-described control termination determination program, the CPU 10a sets the control termination flag F to 1 when, during execution of the automatic brake control, the relative velocity condition is satisfied (S302: Yes), the target velocity condition is satisfied (S303: Yes), and further, either the acceleration condition or the relative distance condition as the margin condition is satisfied (S305: Yes, S307: Yes). In other words, the control termination condition is satisfied.

[0111] As described above, according to this embodiment, the margin condition includes a relative distance condition that the distance (relative distance Lr) between the host vehicle 100 and the preceding object OB is equal to or greater than a predetermined threshold distance Lth, for example, the relative distance Lr is equal to or greater than 10 m. Even if the acceleration condition is not satisfied, if the relative distance condition is satisfied, the margin condition is satisfied and the automatic brake control is terminated. In this case, a sufficient distance margin is ensured to avoid a collision between the host vehicle 100 and the preceding object OB when the automatic brake control is terminated. Therefore, even if the behavior of the preceding object OB increases the possibility of the host vehicle 100 colliding with the preceding object OB again after the automatic brake control is terminated, there is still a sufficient distance margin before the host vehicle 100 collides with the preceding object OB. Therefore, the driver of the host vehicle 100 can perform a driving operation to avoid a collision with the preceding object OB during that time, thereby avoiding a collision between the host vehicle 100 and the preceding object OB with ample time to spare.

[0112] In the first embodiment, after the automatic brake control is initiated, the automatic brake control continues even if the relative velocity condition and the target velocity condition are satisfied, unless the acceleration condition is satisfied. Therefore, it is conceivable that the automatic brake control continues even if the acceleration condition is not satisfied, resulting in the automatic brake control being executed even when the host vehicle 100 is far away from the preceding target OB. In such a case, the driver of the host vehicle 100 may feel that the automatic brake control is unnecessary. In this regard, according to the present embodiment, even if the acceleration condition is not satisfied during the execution of the automatic brake control, the automatic brake control can be terminated if the relative distance Lr is equal to or greater than the threshold distance Lth (if the relative distance condition is satisfied). Therefore, it is possible to prevent the driver from feeling that the automatic brake control is unnecessary due to the automatic brake control being continued even when the relative distance Lr is large.

[0113] Third Embodiment In a third embodiment, an example will be described in which the margin condition is a prediction time condition that the hypothetical predicted arrival time TTCv is equal to or greater than a threshold predicted time TTCvth.

[0114] The vehicle control device according to the third embodiment is mounted on the vehicle 100, similar to the vehicle control device according to the first embodiment. The vehicle control device according to the third embodiment has the configuration shown in Fig. 1. Specifically, the vehicle control device 1C according to the third embodiment has a vehicle control ECU 10, an on-board sensor 20, a drive device 30, a braking device 40, and a steering device 50. Details of these configurations have been explained in the first embodiment, so explanations thereof will be omitted.

[0115] (Overview of Operation of Automatic Brake Control) The vehicle control ECU 10 of the vehicle control device 1C according to the third embodiment initiates automatic brake control when it determines that there is a high possibility of a collision between the host vehicle 100 and a preceding object OB present in the traveling direction of the host vehicle 100. The vehicle control ECU 10 is also configured to terminate the automatic brake control when a predetermined control termination condition is met during execution of the automatic brake control. The predetermined control termination condition includes a margin condition. Therefore, if the margin condition is not met, the control termination condition is not met, and the automatic brake control continues. On the other hand, if the margin condition and other necessary conditions (such as a relative speed condition) are met, the control termination condition is met, and the automatic brake control is terminated. The overview of the operation of this automatic brake control is basically the same as the overview of the operation of the automatic brake control executed by the vehicle control ECU 10 of the vehicle control device 1A according to the first embodiment. However, the margin condition used as the control termination condition for the automatic brake control differs from that of the first embodiment.

[0116] As described in the first embodiment, the margin condition is a condition that is met when the margin, which indicates the amount of margin for avoiding a collision between the host vehicle 100 and the preceding object OB after the automatic brake control is terminated, is equal to or greater than a predetermined threshold margin. Here, if the hypothetical predicted arrival time, which is the predicted arrival time calculated assuming that the automatic brake control is terminated at the current point during execution of the automatic brake control, is long, there is still time until the host vehicle 100 and the preceding object OB collide, even if the automatic brake control is terminated at that point. Therefore, if the hypothetical predicted arrival time is long, it can be said that there is still time to avoid a collision between the host vehicle 100 and the preceding object OB, even if the automatic brake control is terminated at that point. Furthermore, even if the preceding object OB suddenly brakes after the automatic brake control is terminated, if the hypothetical predicted arrival time is long, the driver of the host vehicle 100 can avoid the collision with the preceding object OB with ample margin by performing a driving operation to avoid a collision with the preceding object OB. In this way, the virtual predicted arrival time is the margin for avoiding a collision between the vehicle 100 and the preceding object OB after the end of automatic brake control, and the predicted time condition that the virtual predicted arrival time is greater than or equal to a predetermined threshold predicted time can be a margin condition.

[0117] In this embodiment, the margin condition is a prediction time condition that the hypothetical predicted arrival time TTCv is equal to or greater than a predetermined threshold prediction time TTCvth. In this case, the vehicle control ECU 10 calculates the hypothetical predicted arrival time TTCv during execution of the automatic brake control to determine whether the margin condition (prediction time condition) is met. The hypothetical predicted arrival time TTCv is a predicted time until the host vehicle 100 reaches the preceding object OB if the automatic brake control is terminated at the current time, i.e., if the deceleration (acceleration) of the host vehicle 100 is set to 0. As will be described later, the hypothetical predicted arrival time TTCv can be calculated based on the relative distance Lr and relative speed Vr between the host vehicle 100 and the preceding object OB, and the acceleration (or deceleration) of the preceding object OB.

[0118] After calculating the hypothetical predicted arrival time TTCv, the vehicle control ECU 10 determines whether the hypothetical predicted arrival time TTCv is equal to or greater than the threshold predicted time TTCvth. If the hypothetical predicted arrival time TTCv is equal to or greater than the threshold predicted time TTCvth, the vehicle control ECU 10 determines that the predicted time condition as the margin condition is satisfied. On the other hand, if the hypothetical predicted arrival time TTCv is less than the threshold predicted time TTCvth, the vehicle control ECU 10 determines that the predicted time condition as the margin condition is not satisfied.

[0119] (Specific Operation) The flowchart showing the automatic brake control program executed by the CPU 10a of the vehicle control ECU 10 to perform the automatic brake control in the third embodiment is the same as the flowchart shown in Fig. 5. Therefore, a description of the automatic brake control program according to this embodiment will be omitted.

[0120] In the third embodiment, the CPU 10a also executes the automatic brake control program shown in Figure 5, causing the vehicle control ECU 10 to initiate automatic brake control when the predicted arrival time TTC of the host vehicle 100 to reach the preceding object OB becomes equal to or shorter than the collision determination time TTCth, i.e., when the possibility of a collision between the host vehicle 100 and the preceding object OB increases. This causes the host vehicle 100 to decelerate. Furthermore, if the control end flag F is not set to 1 during execution of the automatic brake control, the vehicle control ECU 10 determines that the control end condition is not met and continues the automatic brake control. Furthermore, if the control end flag F is set to 1 during execution of the automatic brake control, the vehicle control ECU 10 determines that the control end condition is met and terminates execution of the automatic brake control.

[0121] 8 is a flowchart showing an example of a control termination condition determination program executed by the CPU 10a of the vehicle control ECU 10 to set the control termination flag F. When execution of this program is started, the CPU 10a first determines in S401 of FIG. 8 whether the host vehicle speed V1 is 0 km / H, i.e., whether the host vehicle 100 is stopped. If the host vehicle 100 is stopped (S401: Yes), the process executed by the CPU 10a proceeds to S406. On the other hand, if the host vehicle 100 is not stopped (S401: No), the process proceeds to S402.

[0122] In S402, the CPU 10a determines whether the host vehicle speed V1 is equal to or less than the speed V0 of the preceding object OB minus a predetermined reference speed Vs. That is, in S402, the CPU 10a determines whether the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by the predetermined reference speed Vs or more. The condition shown in S402 is the relative speed condition. If the host vehicle speed V1 is not lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S402: No), the CPU 10a determines that the relative speed condition is not met, and the process proceeds to S407. On the other hand, if the host vehicle speed V1 is lower than the speed V0 of the preceding object OB by the reference speed Vs or more (S402: Yes), the CPU 10a determines that the relative speed condition is met, and the process proceeds to S403.

[0123] In S403, the CPU 10a determines whether the speed V0 of the preceding target OB is equal to or greater than a predetermined lower limit speed Vd. The lower limit speed Vd is set in advance. The lower limit speed Vd can be set to any positive speed. The lower limit speed Vd can be set to a speed within a range of 8 km / H to 12 km / H, for example. The lower limit speed Vd can be set to 10 km / H, for example. If the speed V0 of the preceding target OB is less than the lower limit speed Vd (S403: No), the process proceeds to S407. On the other hand, if the speed V0 of the preceding target OB is equal to or greater than the lower limit speed Vd (S403: Yes), the process proceeds to S404. The condition shown in S403 is the target speed condition.

[0124] In S404, the CPU 10a calculates a hypothetical predicted arrival time TTCv. The hypothetical predicted arrival time TTCv is calculated, for example, as follows.

[0125] The current position of the vehicle 100 during execution of the automatic brake control is x ｅ , the current speed is v ｅ , the current acceleration (vertical acceleration) is a ｅ The current position of the preceding target OB is x ｐ , the current speed is v ｐ , the current acceleration (vertical acceleration) is a ｐ Note that the speed in the traveling direction (forward) of the host vehicle 100 and the preceding object OB is defined as a positive speed, and the acceleration acting in the traveling direction (forward) of the host vehicle 100 and the preceding object OB is defined as a positive acceleration. Also, the position is assumed to increase as the distance from the host vehicle 100 increases in the traveling direction of the host vehicle 100.

[0126] The position x of the vehicle 100 after the time t has elapsed from the present time ｅｔ is the current position x of the vehicle 100 ｅ , velocity v ｅ , acceleration a ｅ The position x of the preceding object OB after the time t has elapsed from the present time can be expressed by the following equation (1) using ｐｔ is the current position x of the preceding target OB ｐ , velocity v ｐ , acceleration a ｐ can be expressed by the following equation (2).

[0127] When the vehicle 100 collides with the preceding object OB after the time t has elapsed from the present time, the position x of the vehicle 100 after the time t has elapsed is ｅｔ and the position x of the preceding target OB ｐｔ Since these match, the following equation (3) holds.

[0128] By substituting the formulas (1) and (2) into the formula (3), the following formula (4) can be obtained.

[0129] By solving equation (4) for t, the following equation (5) can be obtained using the quadratic equation formula.

[0130] When t in equation (5) is the predicted arrival time TTC, the value of TTC is either TTC1 expressed by equation (6) or TTC2 expressed by equation (7).

[0131] In addition, when t in equation (5) is the predicted arrival time TTC, the value of the predicted arrival time TTC is positive, so the right side of equation (5) must also always be positive. In this case, first, in a scene where the host vehicle 100 collides with the preceding object OB after the execution of the automatic brake control, the acceleration a ｐ is negative (a ｐ <0), and the deceleration of the host vehicle (-a ｅ ) is the deceleration of the preceding target OB (-a ｐ ) is smaller than a ｐ -a ｅ <0. When the preceding object OB and the host vehicle 100 collide, the velocity of the preceding object OB is v ｐ is the speed v of the vehicle 100 ｅ is smaller than v ｐ -v ｅ <0. Furthermore, until the collision between the preceding object OB and the host vehicle 100, the position x ｐ is the position x of the vehicle 100 ｅ is greater than x ｐ -x ｅ> 0. When these relationships are applied to equation (5), the denominator (a ｐ -a ｅ ) is negative, and the first term in the numerator on the right side of equation (5) (-(v ｐ -v ｅ ) is positive. Naturally, the second term in the numerator on the right side of equation (5) is positive.

[0132] When the above relationship is applied to equation (6), the numerator on the right side is always positive and the denominator on the right side is negative. Therefore, TTC1 is always negative. Therefore, we will verify that TTC2 is always positive.

[0133] FIG. 9 is a graph showing the relationship between the variable y and time t when the right-hand side of equation (4) is the variable y. In FIG. 9, the horizontal axis is time t and the vertical axis is variable y. As shown in FIG. 9, the graph showing the relationship between variable y and time t draws an upwardly convex parabola. This is because the coefficient (a ｐ -a ｅ ) is negative. ｐ -x ｅ ) is positive. Therefore, one of the two solutions (TTC1, TTC2) obtained when 0 is substituted into the variable y is always negative and the other is always positive. As described above, TTC1 is always negative, so TTC2 is always positive. Therefore, the predicted arrival time TTC is expressed as in the following equation (8).

[0134] The virtual predicted arrival time TTCv is calculated by multiplying the acceleration a ｅ Since the predicted arrival time is calculated when is 0, a is added to the equation (8). ｅ = 0, the equation (9) can be obtained.

[0135] In equation (9), v ｐ -v ｅ = Vr, and x ｐ -x ｅ = Lr. Therefore, the hypothetical predicted arrival time TTCv can be expressed as in equation (10). In equation (10), Vr is the relative velocity and Lr is the relative distance. As shown in equation (10), the virtual predicted arrival time TTCv is calculated based on the relative velocity Vr, the relative distance Lr, and the acceleration a ｐ It can be calculated based on the following.

[0136] In S404, the CPU 10a calculates the hypothetical predicted arrival time TTCv using, for example, the above-mentioned formula (10). After the CPU 10a calculates the hypothetical predicted arrival time TTCv in S404, the process proceeds to S405.

[0137] In S405, the CPU 10a determines whether the virtual predicted arrival time TTCv is equal to or greater than a threshold predicted time TTCvth. The threshold predicted time TTCvth is set in advance. The threshold predicted time TTCvth can be set in advance as a time that allows a collision to be avoided with a margin even if the possibility of a collision between the host vehicle 100 and the preceding object OB increases after the end of automatic brake control. The threshold predicted time TTCvth can be set to, for example, 4 seconds or more. The threshold predicted time TTCvth can be set to, for example, a time between 4 seconds and 10 seconds. The threshold predicted time TTCvth can be set to, for example, 4 seconds. The condition shown in S405 is a prediction time condition that serves as a margin condition. If the hypothetical predicted arrival time TTCv is less than the threshold predicted time TTCvth (S405: No), the CPU 10a determines that the predicted time condition as the margin condition is not met, and the process proceeds to S407. On the other hand, if the hypothetical predicted arrival time TTCv is equal to or greater than the threshold predicted time TTCvth (S405: Yes), the CPU 10a determines that the predicted time condition as the margin condition is met, and the process proceeds to S406.

[0138] In S406, the CPU 10a determines that the control termination condition for the automatic brake control is met, and sets the control termination flag F to 1. Thereafter, the CPU 10a terminates this program. In addition, in S407, the CPU 10a determines that the control termination condition for the automatic brake control is not met, and sets the control termination flag F to 0. Thereafter, the CPU 10a terminates this program.

[0139] By executing the above-described control termination determination program, the CPU 10a sets the control termination flag F to 1 when all of the following conditions are satisfied during execution of the automatic brake control: the relative speed condition is satisfied (S402: Yes), the target speed condition is satisfied (S403: Yes), and further the prediction time condition as the margin condition, i.e., the condition that the virtual predicted arrival time TTCv is equal to or greater than the threshold predicted time TTCvth (S405). In other words, the control termination condition is satisfied.

[0140] Thus, according to this embodiment, the margin condition is a prediction time condition in which the virtual predicted arrival time TTCv is equal to or greater than the threshold prediction time TTCvth, for example, the virtual predicted arrival time TTCv is equal to or greater than 4 seconds. By including such a margin condition (prediction time condition) in the control termination condition, a time margin is ensured for avoiding a collision between the host vehicle 100 and the preceding object OB when the automatic brake control is terminated. Therefore, even if the behavior of the preceding object OB increases the likelihood of the host vehicle 100 colliding with the preceding object OB again after the automatic brake control is terminated, there is still a time margin before the host vehicle 100 collides with the preceding object OB. Therefore, by allowing the driver of the host vehicle 100 to perform a driving operation to avoid a collision with the preceding object OB during that time, the collision between the host vehicle 100 and the preceding object OB can be avoided with ample time.

[0141] Although the embodiments of the present disclosure have been described above, the technical concept of the present disclosure is not limited to the above-described embodiments. For example, the following modifications are possible.

[0142] (Variation 1) In the above embodiment, the control termination condition includes the target velocity condition. However, the target velocity condition may be excluded from the control termination condition, and the control termination condition may be satisfied when the relative velocity condition and the margin condition are satisfied.

[0143] (Variation 2) In the second embodiment, the margin condition is satisfied when either the acceleration condition or the relative distance condition is satisfied. However, only the relative distance condition may be set as the margin condition. In this case, the CPU 10a of the vehicle control ECU 10 can execute a control termination determination program shown in FIG. 10 instead of the control termination determination program shown in FIG. 7. According to the control termination determination program shown in FIG. 10, the CPU 10a first determines whether the host vehicle speed V1 is 0 km / H (S501), and if the host vehicle speed V1 is not 0 km / H, determines whether the relative speed condition is satisfied (S502), and if the relative speed condition is satisfied, determines whether the target speed condition is satisfied (S503), and if the target speed condition is satisfied, determines whether the relative distance condition is satisfied (S504). Then, if the relative distance condition is met, the CPU 10a determines that the control end condition is met and sets the control end flag F to 1, and if the relative distance condition is not met, it determines that the control end condition is not met and sets the control end flag F to 0.

[0144] (Variation 3) The margin condition may be configured to be satisfied when any one of the acceleration condition, the relative distance condition, and the predicted time condition is satisfied. Also, the margin condition may be configured to be satisfied when two of the acceleration condition, the relative distance condition, and the predicted time condition are satisfied, or when all of the conditions are satisfied.

[0145] (Variation 4) The control termination condition may be configured to be satisfied only when the relative velocity condition and the target velocity condition are excluded from the control termination condition and only the margin condition is satisfied. For example, the control termination condition may be satisfied when the acceleration condition as the margin condition is satisfied, regardless of whether the relative velocity condition is satisfied. Also, the control termination condition may be satisfied when the relative distance condition as the margin condition is satisfied, regardless of whether the relative velocity condition is satisfied. Furthermore, the control termination condition may be satisfied when the prediction time condition as the margin condition is satisfied, regardless of whether the relative velocity condition is satisfied.

[0146] (Variant 5) In the above third embodiment, an example was shown in which the margin condition (prediction time condition) is met when the hypothetical predicted arrival time TTCv, which is an example of a collision likelihood index between the vehicle 100 and the preceding object OB, is equal to or greater than the threshold predicted time TTCvth. However, the fulfillment of the margin condition may also be determined based on the result of a comparison between a collision likelihood index calculated by other methods and a predetermined threshold value.

[0147] In this way, the technical idea of ​​the present disclosure can be modified without departing from the spirit thereof.

[0148] DESCRIPTION OF THE REFERENCE NUMERALS 1A, 1B, 1C...vehicle control device, 10...vehicle control ECU, 10a...CPU, 20...on-vehicle sensor, 25...vehicle momentum detection sensor, 251...vehicle speed sensor, 252...acceleration sensor, 26...surrounding information detection sensor, 261...radar sensor, 261a...front radar sensor, 262...camera sensor, 262a...front camera sensor, 30...drive device, 31...drive ECU, 41...brake ECU, 40...brake device, 50...steering device, 51...steering ECU, 100...host vehicle, OB...preceding object

Claims

1. A vehicle control device comprising: a braking device for braking a host vehicle; and a control device configured to initiate deceleration control for controlling the braking device so as to decelerate the host vehicle when it is determined that there is a high possibility of a collision between the host vehicle and a preceding object that is an object present in the host vehicle's direction of travel, and to terminate the deceleration control when a predetermined control termination condition is satisfied during execution of the deceleration control, wherein the control termination condition includes a margin condition that is satisfied when a margin indicating the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

2. A vehicle control device as described in claim 1, wherein the control device determines that the margin condition is satisfied when an acceleration condition is satisfied that is satisfied when the acceleration of the preceding object is equal to or greater than a predetermined threshold acceleration during execution of the deceleration control.

3. A vehicle control device as described in claim 1, wherein the control device determines that the margin condition is satisfied when a relative distance condition is satisfied that is satisfied when the relative distance between the vehicle and the preceding object is equal to or greater than a predetermined threshold distance during execution of the deceleration control.

4. A vehicle control device as described in claim 1, wherein the control device determines that the margin condition is satisfied when a predicted time condition is satisfied during execution of the deceleration control, the predicted time being satisfied when the predicted time required for the host vehicle to reach the preceding target when the deceleration of the host vehicle is set to zero is equal to or longer than a threshold time.

5. A vehicle control device comprising: a braking device for braking a host vehicle; and a control device configured to initiate deceleration control for controlling the braking device so as to decelerate the host vehicle when it is determined that there is a high possibility of a collision between the host vehicle and a preceding object that is an object present in the host vehicle's direction of travel, and to terminate the deceleration control when a predetermined control termination condition is satisfied during execution of the deceleration control, wherein the control device determines that the control termination condition is satisfied when, during execution of the deceleration control, a relative speed condition is satisfied that is satisfied when a relationship between the speed of the host vehicle and the speed of the preceding object is such that a collision between the host vehicle and the preceding object is avoidable, and a margin condition is satisfied that is satisfied when a margin indicating the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

6. A vehicle control device as claimed in claim 5, wherein the control device determines that the margin condition is satisfied when an acceleration condition is satisfied that is satisfied when the acceleration of the preceding object is equal to or greater than a predetermined threshold acceleration during execution of the deceleration control.

7. A vehicle control device as described in claim 5, wherein the control device determines that the margin condition is satisfied when a relative distance condition is satisfied that is satisfied when the relative distance between the vehicle and the preceding object is equal to or greater than a predetermined threshold distance during execution of the deceleration control.

8. A vehicle control device as described in claim 5, wherein the control device determines that the margin condition is satisfied when a predicted time condition is satisfied during execution of the deceleration control, the predicted time being satisfied when the predicted time required for the host vehicle to reach the preceding target when the deceleration of the host vehicle is set to 0 is equal to or longer than a threshold time.

9. A vehicle control device according to any one of claims 5 to 8, wherein the control device determines that the relative speed condition is satisfied when the speed of the host vehicle is slower than the speed of the preceding target by a predetermined speed or more during execution of the deceleration control.

10. A vehicle control device as claimed in any one of claims 5 to 9, wherein the control device determines that the control termination condition is satisfied when the relative speed condition is satisfied, a target speed condition is satisfied that is satisfied when the speed of the preceding target is equal to or greater than a predetermined lower limit speed, and the margin condition is satisfied.

11. A vehicle control method including: an initiation step of initiating deceleration control for controlling a braking device of the host vehicle so as to decelerate the host vehicle when it is determined that there is a high possibility of a collision between the host vehicle and a preceding object that is an object present in the traveling direction of the host vehicle; and an end step of terminating the deceleration control when a predetermined control end condition is satisfied during execution of the deceleration control, wherein the control end condition includes a margin condition that is satisfied when a margin representing the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

12. A vehicle control method including: a starting step of starting deceleration control that controls a braking device of the host vehicle so that the host vehicle decelerates when it is determined that there is a high possibility of the host vehicle colliding with a preceding object that is an object present in the traveling direction of the host vehicle; and a terminating step of terminating the deceleration control when a predetermined control terminating condition is satisfied during execution of the deceleration control, wherein the control terminating condition is satisfied when a relative speed condition is satisfied during execution of the deceleration control, the relative speed condition being satisfied when the relationship between the speed of the host vehicle and the speed of the preceding object is such that a collision between the host vehicle and the preceding object can be avoided, and a margin condition being satisfied when a margin indicating the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

13. A program that causes a computer included in a host vehicle to execute the following steps: a start step of starting deceleration control that controls the braking device of the host vehicle so that the host vehicle decelerates when it is determined that there is a high possibility of a collision between the host vehicle and a preceding object that is an object present in the host vehicle's traveling direction; and a termination step of terminating the deceleration control when a predetermined control termination condition is satisfied during execution of the deceleration control, wherein the control termination condition includes a margin condition that is satisfied when a margin indicating the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

14. A program that causes a computer included in a host vehicle to execute the following steps: a start step of starting deceleration control that controls the braking device of the host vehicle so that the host vehicle decelerates when it is determined that there is a high possibility of a collision between the host vehicle and a preceding object that is an object present in the host vehicle's direction of travel; and a termination step of terminating the deceleration control when a predetermined control termination condition is satisfied during execution of the deceleration control, wherein the control termination condition is satisfied when a relative speed condition that is satisfied when the relationship between the speed of the host vehicle and the speed of the preceding object is such that a collision between the host vehicle and the preceding object is avoidable during execution of the deceleration control, and a margin condition that is satisfied when a margin indicating the amount of margin for avoiding a collision between the host vehicle and the preceding object after the deceleration control is terminated is equal to or greater than a predetermined threshold margin.

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