JP2015134584A - Driving support device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving support device that can be improved in collision avoidance performance and collision damage relieving performance by adding correction corresponding to a gravity acceleration component corresponding to a slope of a road face to deceleration of an automatic brake when actuating the automatic brake on a downslope.SOLUTION: In actuating an automatic brake on a downslope, when a predicted collision time derived based on a distance and relative speed between its own vehicle 1 and an obstacle B is found to be equal to a reference time or less, the automatic brake is actuated at large deceleration Ar (=A +α) determined by adding corrected deceleration α (=g.sinθ), detected by a G sensor 5, corresponding to a gravity acceleration components parallel with a road face with a downslope θ on which the vehicle is running to predetermined deceleration A.

Description

  The present invention relates to a driving support device that supports collision avoidance and damage reduction with an obstacle ahead of a host vehicle by automatic braking at a predetermined deceleration.

  Conventionally, there has been proposed a driving support device that avoids a collision with an obstacle existing in the traveling direction of the own vehicle by the operation of an automatic brake, and more specifically, the distance from the front obstacle, In order to calculate the collision arrival time TTC, which is an allowance time until the vehicle collides with the front obstacle when traveling at the same speed from the relative speed with the front obstacle, and to avoid collision with the front obstacle The collision avoidance time TTB required for the vehicle, that is, the time required for the host vehicle to make the relative speed with the front obstacle zero by braking operation at a position where the host vehicle and the front obstacle are separated by a predetermined distance. Then, when the collision arrival time TTC becomes the collision avoidance time TTB, a braking operation for avoiding the collision is considered (for example, Patent Document 1).

JP 2008-132867 A (see paragraph 0020 and others)

  However, since the gradient of the running road changes, especially when the automatic brake is operated on a downhill road, a gravitational acceleration component corresponding to the inclination of the road surface is added to the own vehicle. As described, even when the automatic brake is operated so that the collision arrival time TTC becomes the collision avoidance time TTB and stops before a predetermined distance of the obstacle, it stops at a distance shorter than the predetermined distance, In such a case, there is a risk that inconveniences such as collision with an obstacle cannot be avoided.

  The present invention improves the performance of collision avoidance and collision damage reduction by adding a correction according to the gravitational acceleration component according to the slope of the road surface to the deceleration of the automatic brake when the automatic brake is operated at a downward slope. The purpose is to be able to plan.

  In order to achieve the above object, the driving support device of the present invention is a driving support device that supports collision avoidance and damage reduction with an obstacle ahead of the host vehicle by automatic braking at a predetermined deceleration set in advance. A distance detecting means for detecting a distance between the host vehicle and the obstacle, a relative speed detecting means for detecting a relative speed between the host vehicle and the obstacle, and a distance and a relative speed between the host vehicle and the obstacle. Based on a collision prediction time calculation means for calculating a collision prediction time until the own vehicle collides with the obstacle based on the above, a gradient detection means for detecting a down gradient of the traveling road mounted on the own vehicle, and detected by the gradient detection means Deriving means for deriving a corrected deceleration based on a gravitational acceleration component parallel to the road surface of the downhill traveling road, and when the predicted collision time is equal to or less than a preset reference time, the predetermined deceleration is obtained. It is characterized in that it comprises a brake control means for actuating the automatic brake at the correction deceleration added deceleration by serial derivation means (claim 1).

  According to the first aspect of the present invention, when the predicted collision time derived based on the distance between the host vehicle and the obstacle and the relative speed is equal to or less than the reference time, the traveling descent derived by the deriving unit The automatic brake is operated with a large deceleration obtained by adding the corrected deceleration based on the gravitational acceleration component parallel to the road surface of the gradient to the predetermined deceleration.

  Therefore, when the automatic brake is operated on a downward slope, it is only necessary to add a correction according to the gravitational acceleration component due to the inclination of the road surface to the deceleration of the automatic brake. Support performance can be improved.

It is a block block diagram of one Embodiment of the driving assistance device which concerns on this invention. It is operation | movement explanatory drawing of FIG. It is operation | movement explanatory drawing of FIG.

  An embodiment of the present invention will be described in detail with reference to the block diagram of FIG. 1 and the operation explanatory diagrams of FIGS.

  As shown in FIG. 1, a front monitoring sensor 2 composed of a radar such as a laser radar or a millimeter wave radar is provided at the front of the own vehicle 1, and the front monitoring sensor 2 is transmitted from the own vehicle 1 to a preceding vehicle by transmitting and receiving pulse waves. The distance to the front obstacle B is detected, and an output signal corresponding to transmission / reception of a pulse wave from the front monitoring sensor 2 is sent to the control unit 3 having a microcomputer configuration.

  When the front monitoring sensor 2 is a radar, a plurality of pulse waves are transmitted from the front monitoring sensor 2 toward the front of the host vehicle 1 in the vehicle width direction, and reflected from the obstacle B by the front monitoring sensor 2. The obstacle B is detected by receiving the wave. Further, based on the output signal from the forward monitoring sensor 2, the distance D between the host vehicle 1 and the obstacle B is calculated from the time from the transmission of the pulse wave to the reception of the reflected wave by the control unit 3, and the calculated distance From the time change, the control unit 3 detects the relative speed Vr between the host vehicle 1 and the obstacle B.

  Thus, the function for calculating the distance D between the host vehicle 1 and the obstacle B by the front monitoring sensor 2 and the control unit 3 corresponds to the distance detecting means in the present invention, and the host vehicle by the front monitoring sensor 2 and the control unit 3. The function of calculating the relative speed Vr between 1 and the obstacle B corresponds to the relative speed detecting means in the present invention.

  Further, the controller 3 calculates the predicted collision time TTCe until the own vehicle 1 collides with the obstacle B by dividing the calculated distance D between the own vehicle 1 and the obstacle B by the relative speed Vr. . The function of calculating the predicted collision time TTCe by the control unit 3 corresponds to the predicted collision time calculation means in the present invention.

  In addition, the control unit 3 is provided with a memory (not shown) that stores a reference time TTCs that is a criterion for determining whether or not the automatic brake start condition is satisfied, and the calculated collision predicted time TTCe is shorter than the reference time TTCs. At this time, the brake actuator 4 is controlled by the control unit 3, and automatic braking at a deceleration commanded by the control unit 3 is operated by the brake actuator 4.

Here, as will be described later, even if the corrected deceleration α (m / s ² ) is added (added), the maximum deceleration (for example, 1G) that can be generated by the own vehicle 1 is not exceeded. A value slightly smaller than the maximum deceleration that can be generated is preset as the predetermined deceleration A (m / s ² ), and the reference time TTCs stops without colliding with the obstacle B when decelerated at the predetermined deceleration. It is set to a time (a constant value) required until it is stored and stored in the memory.

  By the way, as shown in FIG. 2, when the host vehicle 1 is traveling on a downhill road, the predicted collision time TTCe derived based on the distance D to the host vehicle 1 obstacle B and the relative speed Vr is If the time is equal to or shorter than the reference time TTCs, the collision avoidance condition is satisfied and the automatic braking is started. At this time, if the G sensor 5 that is the gradient detection sensor detects the downward gradient θ of the traveling road, the vehicle moves forward. A gravity acceleration component (g · sin θ) parallel to the road surface is applied to the host vehicle 1 in the downward direction. Here, g represents gravitational acceleration.

  Therefore, a corrected deceleration α (= g · sin θ) corresponding to the gravitational acceleration component in the downward direction applied to the host vehicle 1 is derived by the control unit 3, and the derived corrected deceleration α is a predetermined deceleration for automatic braking. The automatic brake is started at a large deceleration Ar (= A + α) added to A. As a result, the acceleration due to the gravitational acceleration component in the downward direction related to the host vehicle 1 is canceled by the corrected deceleration rate α, and the host vehicle 1 stops at a predetermined distance before the obstacle B as set in advance. Note that the function of deriving the corrected deceleration rate α by the control unit 3 corresponds to deriving means in the present invention.

  Incidentally, in addition to feedback control of the output of the G sensor 5, the control unit 3 also performs feedforward control for correcting the deceleration as described above, and the automatic braking of the host vehicle 1 while traveling on a flat road is performed. The deceleration command value changes so as to rise at a predetermined deceleration A at the start time t1 of the automatic brake and continue the predetermined deceleration A until the stop time t2 of the host vehicle 1, for example, as shown by the solid line in FIG. However, the deceleration actually detected by the G sensor 5 of the host vehicle 1 by the control according to this command value is delayed from the start of deceleration as indicated by the broken line in FIG. It changes so as to follow.

  Further, the command value for the deceleration of the automatic brake while the host vehicle 1 is traveling on a downhill road is corrected to a predetermined deceleration A at the start time t1 of the automatic brake, as indicated by the one-dot chain line in FIG. It rises at a deceleration Ar to which the speed α (= g · sin θ) is added. On the other hand, the deceleration actually detected by the G sensor 5 of the host vehicle 1 by the control according to this command value is the start of deceleration start as shown by the two-dot chain line in FIG. Is delayed and changes so as to follow the corrected deceleration rate Ar after a while.

  In the present embodiment, from the viewpoint of improving the follow-up performance at the start of deceleration of the automatic brake, the corrected acceleration detected by the actual G sensor 5 indicated by the two-dot difference line in FIG. 3 is a command value. When the speed coincides with the deceleration Ar, the command value for the deceleration of the automatic brake is returned to the original predetermined deceleration A. From the viewpoint of avoiding a collision, the automatic braking at the corrected deceleration Ar may be continued until the host vehicle stops.

  Therefore, according to the above-described embodiment, when the automatic brake is operated on a downward slope, the predicted collision time TTCe derived based on the distance D between the host vehicle 1 and the obstacle B and the relative speed Vr is the reference time TTCs. The corrected deceleration rate α (= g · sin θ) corresponding to the gravitational acceleration component parallel to the road surface of the traveling downward gradient θ detected by the G sensor 5 was added to the predetermined deceleration A when Since the automatic brake is operated at a large deceleration Ar (= A + α), a correction deceleration α corresponding to the gravitational acceleration component due to the road surface inclination θ is added to the predetermined deceleration A as a command value for the automatic brake deceleration. The driving support performance for avoiding collision can be improved with a simple configuration.

  By the way, when the traveling road is uphill, gravity acceleration is applied to the vehicle 1 that moves forward in a downward direction. Therefore, when the automatic brake is operated at a preset predetermined deceleration A, a predetermined decrease is applied. Even if the automatic brake is operated at a predetermined deceleration A that acts to increase the speed, the host vehicle 1 stops before the predetermined distance of the obstacle is long, and the predetermined deceleration A is not corrected. But there is no risk of collision.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the above-described embodiment, the example in which the own vehicle is stopped in front of the obstacle B in front of the own vehicle 1 by the automatic brake and the collision is avoided is described. In addition to the collision avoidance with the front obstacle by the automatic brake, Even if a collision with a front obstacle cannot be avoided, the present invention can be applied to a case where assistance for reducing damage at the time of collision is performed as much as possible.

  In the above-described embodiment, the case where the G sensor 5 is used as the gradient detection means for detecting the downward gradient of the traveling road has been described. However, the G sensor is not necessarily limited as long as it is a means capable of detecting the downward gradient. Absent.

DESCRIPTION OF SYMBOLS 1 ... Own vehicle 2 ... Forward monitoring sensor (distance detection means, relative speed detection means)
3. Control unit (distance detection means, relative speed detection means, collision prediction time calculation means, derivation means, brake control means)
4. Brake actuator (brake control means)
5 G sensor (gradient detection means)
B ... Obstacle

Claims (1)

In a driving assistance device that supports collision avoidance with an obstacle ahead of the host vehicle and damage reduction by automatic braking at a predetermined deceleration set in advance,
Distance detecting means for detecting the distance between the host vehicle and the obstacle;
A relative speed detecting means for detecting a relative speed between the host vehicle and the obstacle;
A collision prediction time calculation means for calculating a collision prediction time until the host vehicle collides with the obstacle based on a distance and a relative speed between the host vehicle and the obstacle;
A gradient detecting means mounted on the host vehicle for detecting the downward gradient of the traveling road;
Derivation means for deriving a corrected deceleration based on a gravitational acceleration component parallel to the road surface of the downhill traveling road detected by the gradient detection means;
Brake control means for operating an automatic brake at a deceleration obtained by adding the corrected deceleration by the deriving means to the predetermined deceleration when the predicted collision time is equal to or less than a preset reference time. A featured driving support device.

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