JP5957822B2 - Braking assist device for vehicle - Google Patents

Description

  The present invention relates to a technology for supporting driving.

As a technique for assisting driving, there is a conventional technique described in Patent Document 1, for example.
In this prior art, the inter-vehicle distance from the preceding vehicle is determined. In this prior art, when it is determined that the inter-vehicle distance with the preceding vehicle is larger than the inter-vehicle distance at the time of stopping during automatic braking, the braking force of automatic braking is released.

JP 2000-43618

By the way, in the prior art, if the braking force of automatic braking is simply released on a slope, the operation of the host vehicle suddenly accelerates or reverses, and the driver does not intend. There is a risk.
An object of the present invention is to prevent the operation of the host vehicle from becoming unintended by the driver when the braking force of automatic braking is released while the host vehicle is stopped on a slope.

In order to solve the above-described problem, one aspect of the present invention detects a downhill road on which the host vehicle travels.
According to one aspect of the present invention, when the host vehicle is stopped, the braking force is applied when the braking force applied to the host vehicle is released based on the approach risk potential of the host vehicle to an obstacle present in front of the host vehicle. The rate of change for decreasing is changed based on the approach risk potential and the detection result of the road gradient. Furthermore, the higher the approach risk potential, the lower the rate of change for decreasing the braking force at the time of release.

  According to the present invention, it is possible to prevent the operation of the host vehicle from becoming unintended by the driver when the braking force by automatic braking is released on a slope.

It is a block diagram which shows the structural example of the collision avoidance braking assistance apparatus for vehicles of this embodiment. It is a block diagram which shows the structural example of the own vehicle and obstruction information acquisition part. It is a block diagram which shows the structural example of a support information calculating part. It is a block diagram which shows the structural example of a braking force calculating part. It is a flowchart which shows the specific example of the setting process of a braking force cancellation | release setting calculating part. It is a characteristic view which shows an example of the relationship between disturbance estimated value SUB2 and the decreasing side change rate ΔDEC_0 when the accelerator is fully closed. It is a characteristic view which shows an example of the relationship between disturbance estimated value SUB2 and the decreasing side change rate ΔDEC_1 when the accelerator is fully opened. It is a characteristic view which shows an example of the relationship between disturbance estimated value SUB2 and accelerator opening gain α_0. It is a characteristic view which shows an example of the relationship between a risk potential and the risk potential decreasing side change amount gain α_1. It is a block diagram which shows the structural example of an accelerator pedal reaction force calculating part. It is a figure which shows an example of the relationship between the road gradient at the time of accelerator full closure, and the cancellation | release state of the braking force of automatic braking. It is a figure which shows an example of the relationship between the road gradient at the time of an accelerator full open, and the cancellation | release state of the braking force of automatic braking. It is a figure which shows an example of the relationship between the distance between vehicles with a preceding vehicle, and the cancellation | release state of the braking force of automatic braking. It is a figure which shows the state which the own vehicle has stopped by the automatic braking on the uphill road, and another vehicle exists before and behind the own vehicle. It is a figure which shows the state which the own vehicle has stopped by the automatic braking on the downhill road, and another vehicle exists before and behind the own vehicle.

The present embodiment will be described with reference to the drawings.
The present embodiment is a vehicle collision avoidance braking support device mounted on a vehicle.
(Constitution)
FIG. 1 is a block diagram illustrating a configuration example of a vehicle collision avoidance braking support device 1.
As shown in FIG. 1, the vehicle collision avoidance braking support device 1 includes a wheel speed sensor 2, an obstacle information detection sensor 3, an accelerator opening sensor 4, a throttle opening sensor 5, a shift position sensor 6, a controller 7, A power application device 8 and an accelerator pedal reaction force application device 9 are provided.

  Here, for example, the controller 7 includes a microcomputer and its peripheral circuits. That is, for example, the controller 7 is configured by a CPU, a ROM, a RAM, and the like as in a general ECU (Electronic Control Unit). The ROM stores one or more programs for realizing various processes. The CPU executes various processes according to one or more programs stored in the ROM.

As shown in FIG. 1, the controller 7 includes a host vehicle / obstacle information acquisition unit 20, a support information calculation unit 30, a braking force calculation unit 40, and an accelerator pedal reaction force calculation unit 50. Here, the own vehicle / obstacle information acquisition unit 20, the support information calculation unit 30, the braking force calculation unit 40, and the accelerator pedal reaction force calculation unit 50 are configured by a program.
The wheel speed sensor 2, the obstacle information detection sensor 3, the accelerator opening sensor 4, the throttle opening sensor 5, and the shift position sensor 6 output the detected detection values (sensor values) to the own vehicle / obstacle information acquisition unit 20. To do.

The own vehicle / obstacle information acquisition unit 20 receives sensor values from various sensors, and acquires various information based on the input sensor values. Then, the host vehicle / obstacle information acquisition unit 20 outputs the acquired various types of information to the support information calculation unit 30.
FIG. 2 is a block diagram illustrating a configuration example of the own vehicle / obstacle information acquisition unit 20.
As shown in FIG. 2, the host vehicle / obstacle information acquisition unit 20 includes a host vehicle speed calculation unit 21, a host vehicle acceleration / deceleration calculation unit 22, an obstacle information calculation unit 23, an accelerator opening detection unit 24, and an engine torque detection unit. 25, a shift position detection unit 26, and a host vehicle / obstacle information output unit 27.

The own vehicle speed calculation unit 21 calculates the own vehicle speed based on the wheel speed sensor value from the wheel speed sensor 2. Then, the host vehicle speed calculation unit 21 outputs the calculated host vehicle speed to the host vehicle / obstacle information output unit 27.
The own vehicle acceleration / deceleration calculation unit 22 calculates the own vehicle acceleration / deceleration based on the wheel speed sensor value from the wheel speed sensor 2. Then, the host vehicle acceleration / deceleration calculation unit 22 outputs the calculated host vehicle acceleration / deceleration to the host vehicle / obstacle information output unit 27.

The obstacle information calculation unit 23 calculates obstacle information based on the obstacle information detection value from the obstacle information detection sensor 3. Then, the obstacle information calculation unit 23 outputs the calculated obstacle information to the own vehicle / obstacle information output unit 27.
Here, the obstacle information detection sensor 3 is, for example, a laser radar, a millimeter wave radar, a stereo camera, or the like. The obstacle information is a distance from the obstacle, a relative speed with the obstacle, and a relative acceleration / deceleration with the obstacle. For example, the relative speed with the obstacle may be obtained by performing an operation such as time differentiation of the distance from the obstacle detected by the obstacle information detection sensor 3. Further, the relative acceleration / deceleration with the obstacle may be obtained by performing an operation such as time differentiation of the relative speed with the obstacle detected by the obstacle information detection sensor 3.

The accelerator opening detector 24 calculates the accelerator opening based on the accelerator opening sensor value from the accelerator opening sensor 4. Then, the accelerator opening detection unit 24 outputs the calculated accelerator opening to the own vehicle / obstacle information output unit 27.
The engine torque detector 25 calculates the engine torque based on the throttle opening sensor value from the throttle opening sensor 5. Then, the engine torque detector 25 outputs the calculated engine torque to the host vehicle / obstacle information output unit 27.

The shift position detector 26 detects the shift position based on the shift position sensor value from the shift position sensor 6. Then, the shift position detection unit 26 outputs the detected shift position to the host vehicle / obstacle information output unit 27.
The own vehicle / obstacle information output unit 27 includes an own vehicle speed calculation unit 21, an own vehicle acceleration / deceleration calculation unit 22, an obstacle information calculation unit 23, an accelerator opening detection unit 24, an engine torque detection unit 25, and a shift position detection. The own vehicle / obstacle information from the unit 26 is input. Then, the host vehicle / obstacle information output unit 27 outputs the input host vehicle / obstacle information to the support information calculation unit 30.

The own vehicle / obstacle information here is information on own vehicle speed, own vehicle acceleration / deceleration, obstacle information, accelerator opening, engine torque, and shift position.
The support information calculation unit 30 calculates support information based on the host vehicle / obstacle information from the host vehicle / obstacle information acquisition unit 20. Then, the support information calculation unit 30 outputs the calculated support information to the braking force calculation unit 40 and the accelerator pedal reaction force calculation unit 50.

FIG. 3 is a block diagram illustrating a configuration example of the support information calculation unit 30.
As shown in FIG. 3, the support information calculation unit 30 includes a risk potential calculation unit 31, a disturbance estimation unit 32, and a support information output unit 33.
The risk potential calculation unit 31 calculates a risk potential (approach risk potential) related to the approach to the obstacle based on the own vehicle / obstacle information from the own vehicle / obstacle information acquisition unit 20. Then, the risk potential calculation unit 31 outputs the calculated risk potential to the support information output unit 33.

Specifically, first, the risk potential calculation unit 31 uses the following equation (1) to calculate the distance D_tar (m) from the own vehicle / obstacle information acquisition unit 20 to the obstacle, The arrival time TTC is calculated based on the relative speed V_tar (m / s).
TTC = D_tar / V_tar (1)
The risk potential calculation unit 31 calculates a risk potential that increases as the calculated arrival time TTC decreases and decreases as the arrival time TTC increases. For this reason, for example, the risk potential may be the reciprocal of the arrival time TTC.

Thus, the risk potential is a value having variables such as the distance to the obstacle, the relative speed with the obstacle, the arrival time, and the like, and can be said to be an index of the risk of approaching the obstacle to the own vehicle.
The disturbance estimation unit 32 calculates a disturbance estimated value based on the host vehicle / obstacle information from the host vehicle / obstacle information acquisition unit 20 and the braking force calculation processing result of the braking force calculation unit 40. Then, the disturbance estimation unit 32 outputs the calculated disturbance estimated value to the support information output unit 33.

Specifically, the disturbance estimation unit 32 determines that the disturbance is calculated when the braking force command value calculated by the braking force calculation unit 40 determining that the braking force is applied to the host vehicle during the previous processing is equal to or greater than a preset value. Calculate an estimate. In this case, the disturbance estimation unit 32 uses the following equation (2) to determine the acceleration / deceleration A (m / s ² ) of the host vehicle from the host vehicle / obstacle information acquisition unit 4 and the braking force command value at the previous processing. A disturbance estimated value SUB is calculated based on P_brk.

SUB = | (A / P_brk) × ARMYU | (2)
Here, ARMYU is a braking amount braking force conversion coefficient used by the braking force command value calculation unit 44 to calculate the braking force command value P_brk. Moreover, the preset value is 0.5 (MPa), for example.
On the other hand, when the disturbance estimated value SUB is not calculated by the above calculation, the disturbance estimating unit 32 sets the disturbance estimated value SUB to 1.

Further, the disturbance estimation unit 32 calculates a disturbance estimated value even when braking assistance is not performed (when it is not determined to apply braking force to the host vehicle). In this case, the disturbance estimation unit 32 calculates a disturbance estimated value based on the engine torque and the shift position.
Specifically, first, the disturbance estimation unit 32 sets the gear ratio GP of the currently selected transmission gear based on the shift position. Here, when the transmission of the vehicle is a continuously variable transmission, the input / output rotation of the transmission may be detected to calculate and set the gear ratio.

Further, the disturbance estimation unit 32 calculates an acceleration estimated value A_tar based on the set gear ratio using the following equation (3).
A_tar = (engine torque × transmission gear ratio × torque ratio × diff gear ratio / vehicle weight) / tire radius (3)
Here, the engine torque is a value acquired from the own vehicle / obstacle information acquisition unit 20. Further, the torque ratio, the differential gear ratio, the vehicle weight, and the tire radius are values set in advance based on vehicle specifications.

And when the disturbance estimation part 32 detects that the driver | operator is operating accelerator operation based on the accelerator opening degree acquired from the own vehicle and the obstruction information acquisition part 20, using the following (4) Formula, A disturbance estimated value SUB2 is calculated based on the estimated acceleration value A_tar and the own vehicle acceleration A (m / s ² ) from the own vehicle / obstacle information acquisition unit 20.
SUB2 = A_tar−A (4)
Here, the disturbance estimated value SUB2 is a value for estimating the road gradient for the following reason.

First, the acceleration / deceleration A and the acceleration estimated value A_tar used in the equation (4) both show positive values in the acceleration direction and negative values in the deceleration direction. That is, the acceleration in the forward direction is a positive value. In addition, the deceleration in the forward direction has a negative value, and the acceleration in the backward direction also corresponds to the deceleration and thus has a negative value.
Then, when the actual acceleration / deceleration A of the vehicle moving forward becomes larger than the estimated acceleration value A_tar when the driving force in the forward direction is applied on the downhill road, the estimated disturbance value SUB2 becomes smaller (negative value). To a smaller value).

Further, when the actual acceleration / deceleration A becomes smaller than the acceleration estimated value A_tar when the driving force in the forward direction is applied on the uphill road (when the acceleration / deceleration A becomes a positive value (the forward direction becomes smaller) When the acceleration becomes small) or when the acceleration / deceleration A becomes a negative value (when the acceleration (deceleration) in the backward direction becomes large)), the estimated disturbance value SUB2 becomes large.
For this reason, when the driving force in the forward direction is applied, it is estimated that the gradient of the downhill road is large as the disturbance estimated value SUB2 is small, and the gradient of the uphill road is large as the disturbance estimated value SUB2 is large. It is estimated to be large.

The support information output unit 33 outputs information from the own vehicle / obstacle information acquisition unit 20, the risk potential calculation unit 31, and the disturbance estimation unit 32 to the braking force calculation unit 40 and the accelerator pedal reaction force calculation unit 50.
The braking force calculation unit 40 calculates a braking force command value of the braking force application device 8 based on information from the support information calculation unit 30. Then, the braking force calculation unit 40 outputs the calculated braking force command value to the braking force applying device 8.

FIG. 4 is a block diagram illustrating a configuration example of the braking force calculation unit 40.
As shown in FIG. 4, the braking force calculation unit 40 includes a threshold setting unit 41, a braking force application determination unit 42, a braking amount calculation unit 43, a braking force command value calculation unit 44, and a braking force release setting calculation unit 45. doing.
The threshold setting unit 41 sets a threshold for determining whether to apply braking force. Then, the threshold setting unit 41 outputs the set threshold (hereinafter referred to as a braking force application determination threshold) to the braking force application determination unit 42.

  Specifically, first, the threshold value setting unit 41 sets a preset arrival time TTC_0 (for example, the initial value of the threshold for determining the arrival time, for example) so that the estimated disturbance value SUB calculated by the disturbance estimation unit 32 increases. Value) is corrected, and the arrival time determination threshold value TTC_th is set. Then, the threshold setting unit 41 sets a risk potential corresponding to the arrival time TTC when the set arrival time determination threshold TTC_th is set as a braking force application determination threshold. Here, for example, the arrival time TTC_0 is 1. The arrival time determination threshold value TTC_th is set in the range of 0.8 to 1.2 by the correction process.

The braking force application determination unit 42 determines whether to apply braking force to the host vehicle. Then, the braking force application determination unit 42 outputs the determination result of the braking force application to the braking amount calculation unit 43 and the support information calculation unit 30.
Specifically, the braking force application determination unit 42 determines that the risk potential acquired from the support information calculation unit 30 is greater than the braking force application determination threshold set by the threshold setting unit 41 (risk potential> braking force). (Threshold for determination of application), it is determined that a braking force is applied to the host vehicle. In other cases (the risk potential ≦ the threshold for determining the braking force), the braking force application determination unit 42 determines that the braking force is not applied to the host vehicle.

  Alternatively, the braking force application determination unit 42 does not apply the braking force (releases the braking force) when a preset time has elapsed since the braking force by automatic braking was applied by the device 1 and the host vehicle stopped. ). Here, the preset time is the time for ending automatic braking, for example, the time for ending automatic braking when it is recognized that the effect of applying braking force has been enjoyed. For example, this time is set experimentally, empirically, or theoretically.

Alternatively, the braking force application determination unit 42 applies the braking force by the automatic braking by the device 1 to stop the own vehicle, and when the driver depresses the accelerator pedal, the brake force is applied. It may be determined not to apply (release the braking force).
Alternatively, the braking force application determination unit 42 applies the braking force by the automatic braking by the device 1, and does not apply the braking force when a preset time has elapsed since the host vehicle stopped. If the accelerator pedal is depressed, it may be determined that the braking force is not applied preferentially.

The braking amount calculation unit 43 calculates the braking amount of the braking applying force device 8. Then, the braking amount calculation unit 43 outputs the calculated braking amount to the braking force command value calculation unit 44.
Here, specifically, the braking amount calculation unit 43 sets the braking amount based on the braking force application determination result of the braking force application determination unit 42. More specifically, when the braking amount calculation unit 43 determines that the braking force application determination unit 42 applies the braking force (risk potential> braking force application determination threshold), a preset braking amount (deceleration) DEC_0 (m / S ² ) is set to the braking amount (deceleration) DEC (m / s ² ). At this time, the braking amount calculation unit 43 limits the increase in the braking amount DEC up to DEC_0 (m / s ² ) with a preset increase rate. Here, for example, the increase rate is 10.0 (m / s ³ ), and the braking amount DEC_0 is 5.0 (m / s ² ).

  Further, the braking amount calculation unit 43 sets the braking amount DEC to zero when the braking force application determination unit 42 determines that the braking force is not applied. Thereby, if the braking amount calculation unit 43 determines that the braking force is not applied after the braking force application determination unit 42 determines that the braking force is applied, the braking amount calculation unit 43 sets the braking amount DEC to zero. In this case, the braking amount calculation unit 43 limits the decrease in the braking amount DEC until it reaches zero by a preset reduction rate.

The case where it is determined that the braking force is not applied here means that when the risk potential is equal to or less than the threshold for determining the braking force, a preset time has elapsed since the braking force was applied and the host vehicle stopped. Or when the host vehicle is stopped by applying braking force and the driver steps on the accelerator pedal from a state where the driver does not step on the accelerator pedal.
The braking force release setting calculation unit 45 performs setting for releasing the braking force applied by the device 1. Specifically, the braking force release setting calculation unit 45 sets a decrease-side change rate that limits a decrease when releasing the braking force. Then, the braking force release setting calculation unit 45 outputs the set decrease side change rate to the braking amount calculation unit 43.

Here, FIG. 5 is a flowchart showing a specific example of the setting process of the braking force release setting calculation unit 45.
As shown in FIG. 5, the braking force release setting calculation unit 45 first acquires support information from the support information calculation unit 30 in step S1.
Next, in step S <b> 2, the braking force release setting calculation unit 45 does not apply the braking force after the braking force is applied according to the determination of the braking force application determination unit 42 and the host vehicle stops. It is determined whether or not it is determined that the braking force is released. The braking force release setting calculation unit 45 does not apply the braking force (releases the braking force) after the braking force is applied by the determination of the braking force application determination unit 42 and the host vehicle stops. If it is determined that it is determined, the process proceeds to step 3. Otherwise, the braking force release setting calculation unit 45 proceeds to step S10.

In step S3, the braking force release setting calculation unit 45 determines the rate of change when the braking force is reduced when the accelerator is fully closed (hereinafter, when the accelerator is fully closed) based on the disturbance estimated value SUB2 acquired as the support information in step S1. Calculated as the decreasing rate of change).
FIG. 6 is a characteristic diagram showing an example of the relationship between the estimated disturbance value SUB2 and the decrease side change rate ΔDEC_0 when the accelerator is fully closed. As shown in FIG. 6, the positive value of the estimated disturbance value SUB2 is a value obtained for the uphill road, and the negative value of the estimated disturbance value SUB2 is a value obtained for the downhill road.

As shown in FIG. 6, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is a maximum value ΔDEC_0max when the estimated disturbance value SUB2 is near zero (a range set in advance with respect to zero).
Further, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed becomes smaller as the estimated disturbance value SUB2 is larger when the estimated disturbance value SUB2 is larger than a value near zero (larger positive value). Then, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed becomes the minimum value ΔDEC_0min (<maximum value ΔDEC_0max) when the estimated disturbance value SUB2 increases to a preset value.

Further, if the estimated disturbance value SUB2 is smaller than the value near zero (smaller negative value) if the estimated value SUB2 is decreased when the accelerator is fully closed, the smaller the estimated disturbance value SUB2. Then, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed becomes the minimum value ΔDEC_0min (<maximum value ΔDEC_0max) when the estimated disturbance value SUB2 decreases to a preset value.
In other words, in this case, if the braking force release setting calculation unit 45 determines that it is equivalent to an uphill road and a downhill road, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is smaller than in other cases (in the case of flat ground). Value.

  Next, in step S4, the braking force release setting computing unit 45 determines the rate of change (hereinafter referred to as accelerator full opening) when the braking force is reduced when the accelerator is fully open based on the disturbance estimated value SUB2 acquired as support information in step S1. Calculated as the time-decreasing rate of change). The accelerator is not limited to the fully open state, but may be the case where the accelerator is not fully opened but is open.

FIG. 7 is a characteristic diagram showing an example of the relationship between the estimated disturbance value SUB2 and the decrease side change rate ΔDEC_1 when the accelerator is fully opened.
As shown in FIG. 7, the decrease rate change rate ΔDEC_1 when the accelerator is fully opened is a preset value (minimum value Δ) when the estimated disturbance value SUB2 is a value near zero (a range set in advance with respect to zero). DEC_1min <preset value <maximum value ΔDEC_1max).

Further, if the accelerator estimated value SUB2 is larger than a value near zero (larger positive value), the larger the estimated disturbance value SUB2 is, the larger the decrease estimated change rate ΔDEC_1 when the accelerator is fully opened. Then, when the estimated acceleration value SUB2 increases to a preset value, the decrease side change rate ΔDEC_1 when the accelerator is fully opened becomes a maximum value ΔDEC_1max after that value.
Further, when the accelerator is fully opened, the decrease side change rate ΔDEC_1 is smaller as the estimated disturbance value SUB2 is smaller than the value near the zero (larger in the negative value) and smaller as the estimated disturbance value SUB2. Then, when the estimated disturbance value SUB2 decreases to a preset value when the accelerator is fully open, the decrease side change rate ΔDEC_1 becomes a minimum value ΔDEC_1min (<ΔDEC_1max) after that value.

In other words, in this case, when the braking force release setting calculation unit 45 determines that it is equivalent to a downhill road, the accelerator side full decrease rate change rate ΔDEC_1 is smaller than in other cases (a flat road equivalent or an uphill road equivalent). To.
Further, the minimum value ΔDEC — 1min set in the decrease side change rate ΔDEC — 1 when the accelerator is fully open is sufficiently smaller than the minimum value ΔDEC — 0 min set in the decrease side change rate ΔDEC — 0 when the accelerator is fully closed. Accordingly, the braking force release setting calculation unit 45 is configured such that, for example, on a downhill road, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is greater than the decrease rate change rate ΔDEC_1 when the accelerator is fully open.

  Further, the maximum value ΔDEC_1max set to the decrease side change rate ΔDEC_1 when the accelerator is fully opened is equivalent to the minimum value ΔDEC_0max set to the decrease side change rate ΔDEC_0 when the accelerator is fully closed. Thereby, the braking force release setting calculation unit 45 is configured such that, for example, on an uphill road, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is smaller than the decrease rate change rate ΔDEC_1 when the accelerator is fully open.

Next, in step S5, the braking force release setting calculation unit 45 calculates an accelerator opening gain based on the estimated disturbance value SUB2 acquired as support information in step S1.
FIG. 8 is a characteristic diagram showing an example of the relationship between the estimated disturbance value SUB2 and the accelerator opening gain α_0.
As shown in FIG. 8, the accelerator opening gain α_0 is the maximum value α_0max when the estimated disturbance value SUB2 is a value near zero (a range set in advance with respect to zero).

Further, the accelerator opening gain α_0 becomes smaller as the estimated disturbance value SUB2 is larger when the estimated disturbance value SUB2 is larger than a value near zero (larger positive value). Then, when the estimated disturbance value SUB2 increases to a preset value, the accelerator opening gain α_0 becomes a minimum value α_0min (<maximum value α_0max) after that value.
Further, the accelerator opening gain α_0 becomes smaller as the estimated disturbance value SUB2 is smaller when the estimated disturbance value SUB2 is smaller than a value near zero (smaller negative value). When the estimated disturbance value SUB2 decreases to a preset value, the accelerator opening gain α_0 becomes the minimum value Δα_0min (<maximum value α_0max) after that value.

Next, in step S6, the braking force release setting calculation unit 45 obtains a gain (change rate) gain (hereinafter referred to as risk) for reducing the braking force based on the risk potential acquired as support information in step S1. (Referred to as potential decrease side change amount gain).
FIG. 9 is a characteristic diagram showing an example of the relationship between the risk potential and the risk potential decrease side change gain α_1.

  As shown in FIG. 9, the risk potential decrease side change amount gain α_1 decreases as the risk potential increases. More specifically, in the region where the risk potential is low, the risk potential decrease side change amount gain α_1 is maintained at the maximum value α_1max. The risk potential decrease side change amount gain α_1 becomes smaller as the risk potential is higher in the medium risk potential region. Further, in the region where the risk potential is high, the risk potential decrease side change amount gain α_1 is maintained at the minimum value α_1min. That is, the risk potential decrease side change amount gain α_1 changes from the maximum value α_1max to the minimum value α_1min when the risk potential becomes higher (α_1min ≦ α_1 ≦ α_1max).

  Here, for example, when setting the decrease rate change rate ΔDEC — 0 when the accelerator is fully closed and the decrease rate change rate ΔDEC — 1 when the accelerator is fully open on the assumption of a scene with a high risk potential, the braking force release setting calculation unit 45 sets α_1max Is set to 1 (α_1max = 1). Also, when setting the decrease rate change rate ΔDEC_0 when the accelerator is fully closed and the decrease rate change rate ΔDEC_1 when the accelerator is fully open on the assumption that the scene has a low risk potential, the braking force release setting calculation unit 45 sets 1 to α_1min. Set (α_1min = 1).

Next, in step S7, the braking force release setting calculation unit 45 calculates the decrease side change rate ΔDEC based on the calculation results of steps S3 to S6 using the following equation (5).
ΔDEC = (ΔDEC_0 × (100−α_0 × θ) / 100 + ΔDEC_1 × α_0 × θ) × α_1 (5)
Here, θ is the accelerator opening degree acquired as support information in step S1.

According to the equation (5), for example, the decrease side change rate ΔDEC increases as the accelerator fully closed decrease side change rate ΔDEC_0 increases. Also, for example, the decrease side change rate ΔDEC increases as the accelerator fully open decrease side change rate ΔDEC_1 increases. For example, the decrease side change rate ΔDEC increases as the risk potential decrease side change amount gain α_1 increases.
Further, the shorter the arrival time TTC, the higher the risk potential, and the higher the risk potential, the smaller the potential decrease side change gain α_1. Therefore, the shorter the arrival time TTC, the smaller the potential decrease side change gain α_1. Therefore, the shorter the distance from the obstacle, the shorter the arrival time TTC. Therefore, the shorter the distance from the obstacle, the smaller the decrease side change rate ΔDEC.

Next, in step S <b> 8, the braking force release setting calculation unit 45 outputs the decrease side change rate ΔDEC calculated in step S <b> 7 to the braking amount calculation unit 43. Accordingly, the braking force release setting calculation unit 45 limits the decrease in the braking amount DEC until it reaches zero in the calculation of the braking amount calculation unit 43 by the decrease side change rate ΔDEC.
Next, in step S9, the braking force release setting calculation unit 45 determines whether or not the braking amount DEC calculated by the braking amount calculation unit 43 is zero. When determining that the braking amount DEC calculated by the braking amount calculating unit 43 is zero, the braking force release setting calculating unit 45 ends the process shown in FIG. 5 (starts the process again from step S1). Moreover, the braking force cancellation | release setting calculating part 45 starts a process again from said step S3 other than that.

On the other hand, in step S10, the braking force release setting calculation unit 45 maintains a preset decrease side change rate ΔDEC. And the braking force cancellation | release setting calculating part 45 complete | finishes the process shown in this FIG. 5 (a process is started again from said step S1).
The braking force command value calculation unit 44 calculates a braking force command value of the braking force application device 11. Then, the braking force command value calculation unit 44 outputs the calculated braking force command value to the support information calculation unit 30 and the braking force application device 11.

Here, specifically, the braking force command value calculation unit 44 calculates the braking force command value P_brk (MPa) using the following equation (6).
P_brk = DEC × ARMYU × α_armyu1 (6)
Here, DEC is a value calculated by the braking amount calculation unit 43. ARMYU is a braking amount braking force conversion coefficient, which is a preset value. For example, the braking amount braking force conversion coefficient ARMYU is 0.811. Α_armyu1 is a braking amount braking force conversion coefficient correction gain.

  Here, the braking amount braking force conversion coefficient correction gain α_armyu1 is set based on the estimated disturbance value SUB calculated by the disturbance estimation unit 32. Specifically, the braking amount braking force conversion coefficient correction gain α_armyu1 increases as the disturbance estimated value SUB hinders braking, that is, as the disturbance estimated value SUB decreases. For this reason, for example, the braking amount braking force conversion coefficient correction gain α_armyu1 may be the reciprocal of the estimated disturbance value SUB. Further, for example, the braking amount braking force conversion coefficient correction gain α_armyu1 takes a value within a range in which 0.8 is the lower limit and 1.2 is the upper limit.

The braking force application device 11 applies a braking force based on the braking force command value from the braking force calculation unit 40. For example, the braking force application device 11 applies a hydraulic pressure to the hydraulic brake actuator.
The accelerator pedal reaction force calculation unit 50 calculates an accelerator pedal reaction force command value based on information from the support information calculation unit 30. Then, the accelerator pedal reaction force calculation unit 50 outputs the calculated accelerator pedal reaction force command value to the accelerator pedal reaction force applying device 9.

FIG. 10 is a block diagram illustrating a configuration example of the accelerator pedal reaction force calculation unit 50.
As shown in FIG. 10, the accelerator pedal reaction force calculation unit 50 includes a threshold setting unit 51, an accelerator pedal reaction force application determination unit 52, an accelerator pedal reaction force amount calculation unit 53, and an accelerator pedal reaction force command value calculation unit 54. doing.
The threshold setting unit 51 sets a threshold for performing accelerator pedal reaction force application determination. Then, the threshold value setting unit 51 outputs the set threshold value (hereinafter referred to as an accelerator pedal reaction force application determination threshold value) to the accelerator pedal reaction force application determination unit 52.

Specifically, the threshold value setting unit 51 sets the accelerator pedal reaction force application determination threshold value such that the estimated disturbance value acquired from the support information calculation unit 30 is small enough to prevent braking of the host vehicle.
The accelerator pedal reaction force application determination unit 52 determines whether to apply an accelerator pedal reaction force. Then, the accelerator pedal reaction force application determination unit 52 outputs the determination result of the accelerator pedal reaction force application to the accelerator pedal reaction force amount calculation unit 53.

  Specifically, the accelerator pedal reaction force application determination unit 52 determines that the risk potential acquired from the support information calculation unit 30 is greater than the accelerator pedal reaction force application determination threshold set by the threshold setting unit 51 (risk Potential> threshold for accelerator pedal reaction force application determination), it is determined that the accelerator pedal reaction force is applied. In other cases (risk potential ≦ accelerator reaction force application threshold value), the accelerator pedal reaction force application determination unit 52 determines that the accelerator pedal reaction force is not applied.

The accelerator pedal reaction force calculator 53 calculates an accelerator pedal reaction force amount. Then, the accelerator pedal reaction force calculation unit 53 outputs the calculated accelerator pedal reaction force amount to the accelerator pedal reaction force command value calculation unit 54.
Specifically, the accelerator pedal reaction force amount calculation unit 53 calculates the accelerator pedal reaction force amount based on the determination result of the accelerator pedal reaction force application by the accelerator pedal reaction force application determination unit 52. That is, the accelerator pedal reaction force amount calculation unit 53 calculates the accelerator pedal reaction force amount when the accelerator pedal reaction force application determination unit 52 determines that the accelerator pedal reaction force is applied. Here, the accelerator pedal reaction force amount calculation unit 53 sets the accelerator pedal reaction force amount to a larger value as the accelerator opening degree is larger, that is, as the accelerator pedal depression amount (accelerator pedal opening amount) is larger. At this time, for example, the accelerator pedal reaction force amount calculation unit 53 calculates the accelerator pedal reaction force amount within a range of 20 (N) to 25 (N).

The accelerator pedal reaction force command value calculation unit 54 calculates an accelerator pedal reaction force command value. Then, the accelerator pedal reaction force command value calculator 54 outputs the calculated accelerator pedal reaction force command value to the accelerator pedal reaction force applying device 9.
Specifically, the accelerator pedal reaction force command value calculation unit 54 determines that the accelerator pedal reaction force application determination unit 52 applies the accelerator pedal reaction force, and then calculates the accelerator pedal operation force calculation unit 53 calculates. The accelerator pedal reaction force command value is increased to the pedal reaction force amount. At this time, the accelerator pedal reaction force command value calculation unit 54 increases the accelerator pedal reaction force command value at a preset increase rate. Here, for example, the preset increase rate is 7.5 (N / sec).

Then, when the accelerator pedal reaction force command value reaches the accelerator pedal reaction force amount, the accelerator pedal reaction force command value calculation unit 54 thereafter accelerates the accelerator pedal reaction force until the accelerator opening obtained from the support information calculation unit 30 becomes zero. Maintain the command value.
Then, when the accelerator pedal reaction force application determination unit 52 determines that the accelerator pedal reaction force is not applied, and the accelerator pedal reaction force command value is a value other than zero during the previous process, the accelerator pedal reaction force command value is determined. The calculation unit 54 decreases the accelerator pedal reaction force command value to zero. At this time, the accelerator pedal reaction force command value calculation unit 54 decreases the accelerator pedal reaction force command value at a preset decrease rate. Here, for example, the preset reduction rate is 30 (N / sec).

Then, after the accelerator pedal reaction force command value becomes zero, the accelerator pedal reaction force command value calculation unit 54 determines that the accelerator pedal reaction force application determination unit 52 determines to apply the accelerator pedal reaction force. Maintain the command value at zero.
The accelerator pedal reaction force applying device 9 applies a reaction force to the accelerator pedal based on the accelerator pedal reaction force command value from the accelerator pedal reaction force calculation unit 50.

(Operation etc.)
An example of the operation of the vehicle collision avoidance braking assistance device 1 will be described.
When the risk potential with an obstacle is larger than the braking force application determination threshold set based on the estimated disturbance value, the vehicle collision avoidance braking support device 1 causes the braking force application device 11 to apply the braking force by automatic braking to the host vehicle. Grant.

Further, the vehicle collision avoidance braking support device 1 applies the accelerator pedal reaction force applying device 9 to the accelerator pedal when the risk potential with the obstacle is larger than the threshold value for determining the accelerator pedal reaction force applied based on the estimated disturbance value. Give reaction force.
And the collision avoidance braking assistance apparatus 1 for vehicles cancels | releases the braking force by automatic braking as follows.

When the vehicle collision avoidance braking support device 1 determines that the braking force is released after the braking force is applied by the automatic braking and the vehicle stops, the braking amount (the braking amount of the automatic braking) is determined using the decrease side change rate ΔDEC. Power) Decrease DEC to zero.
Here, when it is determined that the braking force is to be released, when the risk potential is equal to or less than the threshold for determining the braking force, when a predetermined time has elapsed since the braking force was applied and the host vehicle stopped, Alternatively, this may be the case when the braking force is applied and the host vehicle stops and the driver depresses the accelerator pedal from a state where the accelerator pedal is not depressed.

Next, the operation of the host vehicle when the braking force of automatic braking is released as described above will be described.
FIG. 11 is a diagram illustrating an example of a relationship between a road gradient when the accelerator is fully closed and a braking force release state of automatic braking. FIG. 12 is a diagram showing an example of the relationship between the road gradient when the accelerator is fully opened and the state of release of the braking force of automatic braking. FIG. 13 is a diagram illustrating an example of the relationship between the inter-vehicle distance from the preceding vehicle and the release state of the braking force for automatic braking.
FIG. 14 is a diagram illustrating a state where the host vehicle 100 is stopped by automatic braking on an uphill road, and other vehicles 201 and 202 exist before and after the host vehicle 100. FIG. 15 is a diagram illustrating a state where the host vehicle 100 is stopped by automatic braking on a downhill road and other vehicles 201 and 202 exist before and after the host vehicle 100.

When the driver does not step on the accelerator pedal, the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is calculated according to the relationship shown in FIG. 6, and the braking force is released as shown in FIG. 11. That is, as shown in FIG. 11, the release of the braking force is roughly slower in the case of the uphill road and the downhill road than in other cases (in the case of flat ground (normal)).
As a result, when the host vehicle 100 is stopped on a slope as shown in FIGS. 14 and 15, if the braking force is simply released, the release will be slower than in the case of flat ground. As a result, the host vehicle 100 starts more slowly on the slope than on a flat ground.

In addition, when the driver is stepping on the accelerator pedal, the decrease rate ΔDEC_1 when the accelerator is fully opened is calculated according to the relationship shown in FIG. 7, so that the braking force is released as shown in FIG. That is, as shown in FIG. 12, the release of the braking force is generally slower in the case of a downhill road than in other cases (in the case of a flat ground or an uphill road).
Thus, as shown in FIG. 15, when the host vehicle 100 is stopped on a downhill road, when the accelerator pedal is depressed and the braking force is released, the release is delayed as compared with the case of a flat ground or an uphill road. As a result, when the accelerator pedal is depressed, the host vehicle 100 starts slowly on the downhill road.

  As for the difference in the depressed state of the accelerator pedal, on the downhill road, the braking force is released when the accelerator pedal is depressed rather than when the accelerator pedal is not depressed, as shown in FIG. Become slow. On the uphill road, on the other hand, the release of the braking force is slower when the accelerator pedal is not depressed than when the accelerator pedal is depressed, as shown in FIG. As a result, the host vehicle 100 starts slowly on the downhill road when the accelerator pedal is depressed. In addition, the host vehicle 100 starts quickly on an uphill road in response to the accelerator pedal being depressed.

Further, as a result of calculating the risk potential decrease side change gain α_1 according to the relationship shown in FIG. 9, the release of the braking force becomes slower as the distance from the preceding vehicle is shorter, as shown in FIG.
Accordingly, when the host vehicle 100 releases the braking force when the preceding vehicle 201 exists as shown in FIGS. 14 and 15, the release is delayed. As a result, the host vehicle 100 starts slowly when the preceding vehicle 201 exists.

  Here, in this embodiment, the risk potential calculation part 31 comprises an approach risk potential detection means, for example. Further, the braking force calculation unit 40 and the braking force applying device 11 constitute, for example, a braking force applying unit and a braking force releasing unit. Moreover, the disturbance estimation part 32 comprises a travel path gradient detection means, for example. Moreover, the braking force cancellation | release setting calculating part 45 comprises a change means, for example.

(Effect of this embodiment)
This embodiment has the following effects.
(1) The disturbance estimation unit 32 detects the gradient of the travel path. Then, the braking force release setting calculation unit 45 changes the degree of decrease when releasing the braking force applied to the host vehicle based on the risk potential while the host vehicle is stopped based on the risk potential and the gradient of the travel path. To do.
Thus, the vehicle collision avoidance braking support device 1 prevents the operation of the host vehicle from becoming unintended by the driver when the braking force by the automatic braking is released while the host vehicle is stopped on a slope. be able to.

For example, as described above, the vehicle collision avoidance braking assistance device 1 applies the braking force by automatic braking by the device 1 and releases the braking force after a preset time has elapsed since the host vehicle stopped. There is a case. Further, the vehicle collision avoidance braking assistance device 1 applies a braking force by automatic braking by the device 1 to stop the host vehicle, and when the driver steps on the accelerator pedal from a state where the driver does not step on the accelerator pedal, the braking force May be canceled. In this case, if such a braking force is released on a slope, the start of the host vehicle may become something that the driver does not intend (for example, that involves a large acceleration).
On the other hand, the vehicle collision avoidance braking assistance device 1 of the present embodiment changes the degree of decrease when the braking force is released based on the gradient of the traveling path, so that the driver can start the vehicle. It can prevent becoming unintentional.

(2) The braking force release setting calculation unit 45 decreases the risk potential decrease side change amount gain α_1 as the risk potential is higher. In this case, the higher the risk potential, the smaller the decrease side change rate ΔDEC, so that the release of the braking force for automatic braking becomes gentler.
Further, the braking force release setting calculation unit 45 decreases the decreasing rate ΔDEC_0 when the accelerator is fully closed as the slope of the slope increases. In this case, since the decrease side change rate ΔDEC decreases as the slope of the slope increases, the release of the braking force for automatic braking becomes gentler.

As a result, the vehicle collision avoidance braking support apparatus 1 gradually releases the braking force of the automatic braking even when the risk potential with the obstacle is low on the downhill road by following the decreasing side change rate ΔDEC_0 when the accelerator is fully closed. Can be done.
Therefore, the vehicle collision avoidance braking assistance device 1 can suppress an increase in the acceleration of the host vehicle when the braking force of the automatic braking is released on the downhill road.
Further, the vehicle collision avoidance braking assistance device 1 can gently release the braking force of the automatic braking even on the uphill road by following the decrease side change rate ΔDEC_0 when the accelerator is fully closed.

Therefore, the vehicle collision avoidance braking assistance device 1 can suppress the host vehicle from retreating suddenly when the braking force of automatic braking is released while the vehicle is stopped on an uphill road.
As described above, the vehicle collision avoidance braking support device 1 can prevent the operation of the host vehicle from becoming unintended by the driver when the braking force of automatic braking is released on a slope.

(3) On the uphill road, the braking force release setting calculation unit 45 is configured such that the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is smaller than the decrease rate change rate ΔDEC_1 when the accelerator is fully open. In this case, on the uphill road, the degree of decrease in the braking force when releasing when the accelerator pedal is not depressed is lower than when releasing when the accelerator pedal is depressed. In other words, on the uphill road, the degree of decrease in the braking force is higher when it is released while the accelerator pedal is depressed.

Thus, the vehicle collision avoidance braking support device 1 prevents the host vehicle from abruptly retreating when the braking force of the automatic braking is canceled on the uphill road, and advances by the driver depressing the accelerator pedal. The braking force can be quickly released in accordance with the intention.
Thus, the vehicle collision avoidance braking assistance device 1 can prevent the operation of the host vehicle from becoming unintended by the driver when the braking force of automatic braking is released on a slope.

(4) On the downhill road, the braking force release setting calculation unit 45 is configured so that the decrease rate change rate ΔDEC_0 when the accelerator is fully closed is larger than the decrease rate change rate ΔDEC_1 when the accelerator is fully open. In this case, on the downhill road, the degree of decrease in the braking force when releasing with the accelerator pedal depressed is lower than when releasing with the accelerator pedal not depressed.
Thereby, the collision avoidance braking support device 1 for a vehicle can prevent the acceleration from exceeding the driver's intention to advance when the accelerator pedal is depressed when the braking force of the automatic braking is released on the downhill road.
Thus, the vehicle collision avoidance braking assistance device 1 can prevent the operation of the host vehicle from becoming unintended by the driver when the braking force of automatic braking is released on a slope.

(5) The disturbance estimation unit 32 acquires the acceleration A of the host vehicle calculated based on the wheel speed detected by the wheel speed sensor 2, and calculates based on the throttle opening sensor value detected by the accelerator opening sensor 5. The acceleration A_tar of the host vehicle is calculated from the engine torque and the preset vehicle specifications. Then, the disturbance estimation unit 32 detects the gradient of the travel path from the acceleration A of the host vehicle and the acceleration A_tar of the host vehicle.
Thereby, the collision avoidance braking assistance device 1 for a vehicle can detect the gradient of the travel path without newly providing a special configuration such as a device.

(Modification of this embodiment)
In this embodiment, the risk potential related to the approach of the host vehicle to the obstacle is calculated based on the distance to the obstacle and the relative speed with the obstacle, but the present invention is not limited to this. For example, in this embodiment, the risk is based on information originating from the driver such as the driver's attention level, information originating from the vehicle such as the own speed, information originating from the surroundings of the vehicle such as the degree of congestion on the road, and the like. The potential may be calculated.

Moreover, in this embodiment, although the gradient of a traveling path is calculated using (4) Formula, it is not limited to this. For example, in the present embodiment, the gradient of the traveling road may be calculated by another arithmetic expression, or the gradient information of the traveling road may be acquired by road-to-vehicle communication.
Further, the present embodiment is not limited to the setting of the release of the braking force of the automatic braking, but is not limited to the release of the braking force after the host vehicle is stopped by the automatic braking. Needless to say, the present invention can also be applied to release of the braking force during the operation. That is, in the present embodiment, it is possible to prevent the operation of the host vehicle from becoming unintended by the driver even when releasing the braking force while the host vehicle is decelerating by automatic braking. It is possible to exert such effects.

In the present embodiment, the disturbance estimation unit 32 calculates the acceleration A of the host vehicle based on the wheel speed detected by the wheel speed sensor 2 or based on the throttle opening sensor value detected by the accelerator opening sensor 5. The engine torque may be calculated.
Although the embodiments of the present invention have been specifically described above, the scope of the present invention is not limited to the illustrated and described exemplary embodiments, and effects equivalent to those intended by the present invention. All embodiments that provide are also included. Further, the scope of the present invention is not limited to the combination of features of the invention defined by claim 1 but can be defined by any desired combination of specific features among all the disclosed features. .

DESCRIPTION OF SYMBOLS 1 Vehicle collision avoidance braking assistance device, 11 Brake application force device, 12 Accel pedal reaction force application device, 30 Support information calculation unit, 31 Risk potential calculation unit, 32 Disturbance estimation unit, 40 Brake force calculation unit, 45 Brake force release Setting calculation unit, 50 accelerator pedal reaction force calculation unit

Claims (5)

An approach risk potential detecting means for detecting an approach risk potential of the host vehicle to an obstacle existing in front of the host vehicle;
Braking force applying means for applying braking force to the host vehicle when the approach risk potential detected by the approach risk potential detecting means is greater than a preset threshold;
When it is determined that a preset release condition is satisfied when the host vehicle is stopped, a braking force releasing unit that releases the braking force applied by the braking force applying unit;
Traveling road gradient detecting means for detecting a downhill road on which the vehicle travels;
Based on the approach risk potential detected by the approach risk potential detection means and the slope detection result of the travel road detected by the travel road slope detection means, the braking force is reduced when the braking force release means releases the brake. A change means for changing the rate of change of
With
The vehicular braking assistance device according to claim 1, wherein the changing means lowers the rate of change for decreasing the braking force when the release is performed, as the approach risk potential becomes higher. The traveling road gradient detecting means detects an uphill road on which the host vehicle travels,
2. The change means according to claim 1, wherein the change means further lowers the rate of change for decreasing the braking force at the time of release as the gradient detection value that is the gradient detection result of the travel path increases. The vehicle braking assistance device described. Said changing means, when the traveling road gradient detecting means detects the uphill road, since we reduce the braking force when the release when not depressed the accelerator pedal than when the accelerator pedal is depressed brake assist apparatus for a vehicle according to 請 Motomeko 2 you, characterized in that to lower the rate of change. The changing means detects a downhill road is the travel path gradient detecting means, for gradually reducing the braking force when the release when the accelerator pedal is stepped on than when not depressed the accelerator pedal The braking support device for a vehicle according to any one of claims 1 to 3, wherein a rate of change of the vehicle is reduced. Wheel speed detecting means for detecting the wheel speed of the host vehicle;
An accelerator pedal opening amount detecting means for detecting the opening amount of the accelerator pedal by the operation of the driver, and further comprising:
The traveling road gradient detecting unit calculates a first acceleration estimated value that is an acceleration of the host vehicle based on the wheel speed detected by the wheel speed detecting unit, and calculates an engine torque based on the accelerator pedal opening amount. And calculating a second acceleration estimated value from the engine torque and preset vehicle specifications, and detecting a gradient of a traveling road from the first acceleration estimated value and the second acceleration estimated value. The vehicle braking assistance device according to any one of claims 1 to 4.

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