JP2002274345A - Automatic brake control device - Google Patents

Abstract

(57) [Summary] [Problem] When a steering wheel is operated in a state where an automatic brake is operated, an automatic brake adapted to a driver's feeling is adopted by adopting a braking force reduction control giving priority to a steering wheel operation of a driver. To provide an automatic brake control device capable of realizing the above. An automatic brake fluid pressure command value generation unit of a control controller includes a braking deceleration α required for the vehicle to avoid an obstacle and a vehicle slip calculated by a vehicle slip angle calculation unit. The target braking deceleration αr for reducing the braking force is calculated based on the gain K for avoiding the obstacle calculated based on the angle θ ^* , and when the own vehicle slip angle θ ^* is generated by operating the steering wheel, the obstacle is determined. In order to avoid the problem, the brake fluid pressure for obtaining the braking deceleration α required is gradually reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects an obstacle in front of a host vehicle and judges the degree of approach between the host vehicle and the obstacle.
It belongs to the technical field of an automatic brake control device for automatically applying a brake so as to avoid an obstacle.

[0002]

2. Description of the Related Art Conventionally, as an automatic brake control device,
For example, one described in JP-A-11-203598 is known.

This publication aims at effectively avoiding contact while adapting to the driver's intention or sensation, and at the same time, preventing interference with the driver's steering operation. When the vehicle falls below a distance that can be avoided by operating the steering wheel, the automatic braking device is immediately activated and the deceleration is set to a relatively small value.

That is, when the relative distance is smaller than a relative distance threshold Ls at which the obstacle can be avoided by operating the steering wheel, the braking deceleration is performed according to the relative distance X and the relative distance Lb relating to the automatic braking operation. Is calculated (0.2G when Lb <X <Ls, 0.8G when X ≦ Lb), and the brake fluid pressure at which this braking deceleration is obtained is applied to the vehicle.

[0005]

However, in the conventional automatic brake control device, the relative distance threshold Ls and the hydraulic pressure applied by the automatic brake are uniquely determined independently of the driver's steering operation. I can decide.
Therefore, even if the driver operates the steering wheel to avoid an obstacle during the automatic braking operation, the automatic braking operates regardless of the operation of the steering wheel, and the instant when the relative distance X exceeds the relative distance threshold Ls. Brake operation OF
Since it is F, it becomes difficult for the driver to predict the behavior of the vehicle, and the driver feels uncomfortable in operating the steering wheel.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a brake which gives priority to a driver's steering operation when the steering wheel is operated while an automatic brake is operating. An object of the present invention is to provide an automatic brake control device capable of realizing an automatic brake suited to a driver's feeling by employing force reduction control.

[0007]

In order to achieve the above object, according to the first aspect of the present invention, an obstacle detecting means for detecting an obstacle in front of a host vehicle, and an obstacle detecting means for detecting an obstacle based on a result of the obstacle detecting means. Distance detecting means for detecting a distance to an obstacle;
Relative speed detection means for detecting a relative speed with respect to an obstacle based on the result of the obstacle detection means, vehicle behavior state detection means for detecting a vehicle behavior state of the own vehicle, Automatic braking means for automatically applying a brake based on the results of the distance detecting means and the relative speed detecting means, and a lateral motion state of the vehicle detected by the vehicle behavior state detecting means when a braking force is generated by the automatic braking. Braking force reducing means for reducing the braking force based on the amount.

According to a second aspect of the present invention, in the automatic brake control device according to the first aspect, the braking force reducing means is means for reducing a braking force based on a slip angle of the host vehicle. Features.

According to a third aspect of the present invention, in the automatic brake control device according to the second aspect, the braking force reducing means is configured to control the self-vehicle with respect to a slip angle necessary for the self-vehicle to avoid an obstacle. This is a means for greatly reducing the braking force as the ratio of the slip angle becomes larger.

[0010]

According to the first aspect of the present invention, the obstacle detecting means detects an obstacle ahead of the host vehicle, and the distance detecting means detects the obstacle based on the result of the obstacle detecting means. The relative speed detecting means detects the relative speed with respect to the obstacle based on the result of the obstacle detecting means, and the vehicle behavior state detecting means detects the vehicle behavior state of the own vehicle. The braking means automatically applies a brake to the host vehicle based on the results of the distance detecting means and the relative speed detecting means. Then, even when the braking force is generated, the braking force reduction unit determines that the driver has performed the avoidance operation based on the lateral motion state amount of the own vehicle detected by the vehicle behavior state detection unit. Thus, the braking force generated by the automatic braking means is reduced.

That is, the conditions for starting the automatic braking and the contents of the control are determined based on the relative distance and relative speed to the own vehicle and the vehicle behavior state of the own vehicle, and based on the amount of lateral movement of the own vehicle. Is reduced. In other words, the braking force is reduced according to the operation of the steering wheel.

Therefore, when the steering wheel is operated while the automatic brake is operating, the automatic braking adapted to the driver's feeling can be realized by adopting the braking force reduction control which gives priority to the driver's steering wheel operation. Can be.

According to the second aspect of the present invention, in the braking force reducing means, the braking force is reduced based on the slip angle of the host vehicle.

That is, when the driver operates the steering wheel, if a slip angle for turning the host vehicle occurs according to the amount of operation and the operation speed, the driver feels that the steering feeling is good and matches the steering operation of the driver. evaluate.

Therefore, by reducing the braking force in the automatic braking based on the slip angle of the own vehicle,
It is possible to realize automatic braking appropriate for the driver's steering feeling.

According to the third aspect of the present invention, in the braking force reducing means, the greater the ratio of the slip angle of the host vehicle to the slip angle required for the host vehicle to avoid an obstacle, the greater the braking force. Reduced.

Therefore, a more appropriate braking force can be obtained in accordance with the obstacle avoidance situation due to the driver's operation of the steering wheel, and an automatic brake more suited to the driver's feeling can be realized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment for realizing an automatic brake control device according to the present invention will be described below based on a first embodiment corresponding to claims 1 to 3.

(First Embodiment) First, the configuration will be described. FIG. 1 is an overall system showing an automatic brake control device according to a first embodiment, in which 1 is a laser radar (obstacle detection means), 2 is a steering angle sensor, 3 is a yaw rate sensor, and 4 is a distance information unit ( (A distance detecting means and a relative speed detecting means), 5 is a controller, 6 is a brake unit, and 7 is a wheel speed sensor.

The laser radar 1 is an outside world recognizing device that detects an obstacle (a preceding vehicle, a building on the road, etc.) in front of the own vehicle.

The steering angle sensor 2 detects the amount of operation of the steering wheel by the driver.

The yaw rate sensor 3 detects the yaw rate of the host vehicle.

The distance information unit 4 calculates an inter-vehicle distance to an obstacle and a relative speed to the obstacle based on information from the laser radar 1.

The controller 5 receives signals from the steering angle sensor 2, the yaw rate sensor 3, the distance information unit 4, and the wheel speed sensor 7, and sends a command hydraulic signal to a brake hydraulic control actuator of the brake unit 6. Output.

The brake unit 6 receives a command hydraulic pressure signal from the controller 5 and sends a brake hydraulic pressure corresponding to the command hydraulic pressure to the wheel cylinder of each wheel.

The wheel speed sensor 7 is attached to each wheel to calculate the vehicle speed of the vehicle, and detects the wheel speed of each wheel.

FIG. 2 is a control block diagram showing an automatic braking system centered on the controller 5.

The control controller 5 includes a host vehicle body speed estimating unit 101, a vehicle slip angle calculating unit 102 (vehicle behavior state detecting means), an obstacle vehicle speed estimating unit 103, and an automatic brake fluid pressure command value generating unit. 104 (automatic braking means and braking force reducing means).

The host vehicle body speed estimating section 101 estimates the host vehicle body speed Vc based on the average value of the wheel speed values from the wheel speed sensors 7 of the respective wheels.

In the vehicle slip angle calculation unit 102,
The steering angle from the steering angle sensor 2 and the yaw
The yaw rate γ from the late sensor 3 and the vehicle speed
The vehicle body speed Vc from the constant unit 101 is input, and the following equation is used.
Vehicle's slip angle θ^*Is calculated. θ^*= ｛(-M / 2) Yg- (γ / Vc) (L_fCP_f-L_rCP_r) +
CP_fδ｝ / (CP_f+ CP_r) M: Body weight Vc: Body speed γ: Yaw rate L_f: Distance from center of gravity to front tire  L_r: Distance from center of gravity to rear tire  CP_f: Front tire cornering power  CP_r: Cornering power of rear tire δ: Actual steering angle = steering wheel steering angle * N (N: gear ratio) Yg: lateral acceleration
1992-5 9833263. The obstacle vehicle speed estimating unit 103 includes the own vehicle body speed estimating unit 1.
01 and the distance information unit 4
The relative speed Vr is input and the obstacle vehicle
The speed Vp (preceding vehicle speed) is estimated. Vp = Vc + Vr In the automatic brake fluid pressure command value generation unit 104,
The own vehicle slip angle θ from the slip angle calculation unit 102
^*And the host vehicle body speed V from the host vehicle body speed estimation unit 101
c and the obstacle vehicle speed Vp from the obstacle vehicle speed estimation unit 103
And the distance d from the distance information unit 4 are input.
After the brake deceleration calculation process described later
The automatic brake fluid pressure command value Pr to the key unit 6 is generated.
It is.

Next, the operation will be described.

[Automatic Brake Control Process] FIG. 3 is a flowchart showing the flow of the process of calculating the braking deceleration required for the own vehicle to avoid an obstacle by the automatic brake fluid pressure command value generating section 104. .

In step 30, the own vehicle body speed estimating section 1
01 and the vehicle speed estimating unit 10
3 and an inter-vehicle distance d from the distance information unit 4 are input.

In step 31, the braking deceleration α required for the own vehicle to avoid the obstacle is calculated by the following equation. α = (１ ／) · (Vp ² −Vc ² ) / d (1) That is, for example, when (Vp ² −Vc ² ) is called the degree of approach to an obstacle, the distance between the own vehicle and the obstacle is When the inter-vehicle distance d is constant, the greater the degree of approach to the obstacle, the greater the braking deceleration α. When the degree of approach to the obstacle is constant, the shorter the inter-vehicle distance d, the greater the braking deceleration α. It is said.

FIG. 4 shows an automatic brake fluid pressure command value generator 10.
6 is a flowchart illustrating a flow of a process of calculating a gain K necessary for the host vehicle to avoid an obstacle, which is executed in Step 4.

In step 40, the vertical distance y to the edge of the obstacle by the sensor such as the laser radar 1, the horizontal distance x to the edge of the obstacle by the sensor such as the laser radar 1, and the slip angle θ ^{* of the} vehicle are input. Is done.

In step 41, the angle θ between the edge of the obstacle and the center line of the vehicle and the slip angle θw at which the own vehicle slips through are calculated. θ = sin ⁻¹ (x / y) (2) θw = sin ⁻¹ (w / y) (3) where w is the vehicle width step 42 from the own vehicle center line, Gain K required to avoid
Is calculated by the following equation. K = k ｛{1−θ ^* / (θ + θw)} (4) Here, k is an adjustment parameter indicating the priority of the driver, and as shown in FIG. 6, according to the size of the adjustment parameter k. The manner in which the gain K changes is adjusted. In addition,
The adjustment parameter k may be determined experimentally, or may be set arbitrarily by the driver according to his / her preference by an input device provided on an instrument panel or the like in the vehicle compartment.

FIG. 5 shows an automatic brake fluid pressure command value generator 10.
6 is a flowchart illustrating a flow of a calculation process of a braking force reduction target braking deceleration αr necessary for the host vehicle to avoid an obstacle, which is executed in Step 4.

In step 50, the braking deceleration α required for the own vehicle to avoid the obstacle calculated in step 30 and the own vehicle calculated in step 42 for avoiding the obstacle are calculated. Is input.

In step 51, the braking force reduction target deceleration αr is calculated by the following equation using the braking deceleration α and the gain K.
Is calculated. αr = K · α (5) FIG. 7 shows the target braking deceleration αr for reducing the braking force required by the automatic brake fluid pressure command value generation unit 104 to avoid the obstacle for the host vehicle, and the automatic brake fluid. Pressure command value Pr
The automatic brake fluid pressure command value Pr is determined according to the magnitude of the target braking deceleration αr for braking force reduction calculated in step 51, and the determined automatic brake fluid pressure command value Pr is Output to the brake unit 6.

[Automatic Brake Control Operation] When an obstacle such as a preceding vehicle is detected by the laser radar 1 during traveling, the inter-vehicle distance d to the obstacle is determined in the distance information unit 4 based on the information of the laser radar 1. The calculated vehicle body speed estimating unit 101 estimates the own vehicle body speed Vc, the obstacle vehicle speed estimating unit 103 estimates the obstacle vehicle speed Vp, and the automatic brake fluid pressure command value generating unit 104 Based on the calculated value (estimated value), a braking deceleration α required for the host vehicle to avoid an obstacle is calculated in a manner similar to the conventional automatic braking device.

On the other hand, when the vehicle slip angle θ ^* is calculated by the vehicle slip angle calculation unit 102, the self-vehicle slip angle θ ^* is input to the automatic brake fluid pressure command value generation unit 104 for inputting the vehicle slip angle θ ^*. A gain K necessary for avoiding an obstacle is calculated, and a target braking deceleration αr for braking force reduction is calculated by multiplying the gain K by the braking deceleration α, and the target braking deceleration for braking force reduction is calculated. By outputting the automatic brake fluid pressure command value Pr determined according to the magnitude of the speed αr to the brake unit 6, each wheel is automatically braked.

That is, since the gain K is applied to the braking deceleration α to obtain the braking force reduction target braking deceleration αr, the vehicle slip angle θ ^* becomes almost zero when the driver does not operate the steering wheel. Becomes
From the above equation (4), K = k. However, the own vehicle slip angle θ ^* approaches (θ + θw) by operating the steering wheel, and moves from K → 0. That is, as shown in FIG. 6, the value of the gain K decreases toward 0 as θ ^* / (θ + θw) approaches 1, and therefore, is determined according to the magnitude of the target braking deceleration αr for reducing the braking force. The automatic brake fluid pressure command value Pr also decreases by operating the steering wheel, and when K = 0, the brake fluid pressure is released.

Thus, the brake fluid pressure can be gradually released in accordance with the obstacle avoidance situation due to the driver's operation of the steering wheel, and the automatic brake control suited to the driver's feeling is realized.

FIG. 8 shows (a) → (b) →
(C), the vehicle slip angle θ ^* becomes (θ + θ).
This indicates a situation in which the vehicle approaches an obstacle while approaching w) and gradually releasing the brake fluid pressure. FIG. 8 (a)
In the case of, the obstacle exists almost in front of the own vehicle, and the lateral distance x to the edge of the obstacle is large.
The angle θ between the edge of the obstacle and the vehicle center line calculated by the equation becomes large. In the case of FIG. 8B, the lateral distance x to the edge of the obstacle becomes smaller than that of FIG. 8A by operating the steering wheel to avoid the obstacle, so that the distance between the edge of the obstacle and the vehicle center line is reduced. The angle θ is smaller than that shown in FIG. In the case of FIG. 8C, the lateral distance x to the edge of the obstacle is changed by operating the handle to avoid the obstacle.
8B, the angle θ between the edge of the obstacle and the vehicle center line becomes smaller than that in FIG. 8B.

That is, assuming that the own vehicle slip angle θ ^* is a constant value, the slip angle θw at which the own vehicle slips through hardly changes in FIGS. 8A, 8B and 8C. However, the angle θ between the edge of the obstacle and the vehicle center line is changed by the steering wheel operation to avoid the obstacle as shown in FIG.
(A)> FIG. 8 (b)> FIG. 8 (c), so that the own vehicle slip angle θ ^* becomes (θ + θw) in the order of (a) → (b) → (c) in FIG. ).

Next, the effects will be described.

(1) In the automatic brake fluid pressure command value generation unit 104 of the controller 5, the own vehicle avoids obstacles based on the amount of lateral movement of the own vehicle (own vehicle slip angle θ ^* ). In order to reduce the braking force to obtain the braking deceleration α required for the vehicle, if the driver operates the steering wheel that generates lateral movement in the vehicle while the automatic brake is operating, the driver's steering wheel operation By employing the braking force reduction control which is given priority, it is possible to realize automatic braking that matches the driver's feeling.

(2) In the automatic brake fluid pressure command value generation unit 104 of the controller 5, the braking deceleration α required for the own vehicle to avoid the obstacle and the self-calculation calculated by the vehicle slip angle calculation unit 102 are calculated. When the target braking deceleration αr for braking force reduction is calculated based on the gain K for avoiding an obstacle calculated based on the vehicle slip angle θ ^* , and the own vehicle slip angle θ ^* is generated by operating the steering wheel. ,
Since the configuration is such that the brake fluid pressure for obtaining the braking deceleration α required to avoid the obstacle is gradually released, it is possible to realize an appropriate automatic brake that matches the steering feeling of the driver.

(3) In the automatic brake fluid pressure command value generation unit 104 of the controller 5, the braking deceleration α required for the own vehicle to avoid the obstacle and the own vehicle slip angle θ
^The target braking deceleration αr for reducing the braking force is calculated by ^* , the slip angle θw required for the own vehicle to avoid the obstacle, and the gain K calculated based on the angle θ between the edge of the obstacle and the vehicle center line. Calculation, that is, the brake fluid pressure is gradually released as the vehicle slip angle θ ^* approaches (θ + θw),
When [theta] ^* / ([theta] + [theta] w) becomes 1, the brake fluid pressure is completely released to release the automatic brake, so that a more appropriate braking force can be obtained according to the obstacle avoidance situation by the driver's steering wheel operation. Automatic braking that matches the driver's feeling can be realized.

(Other Embodiments) The automatic brake control device according to the present invention has been described based on the first embodiment. However, the specific structure is not limited to these embodiments, and claims are not limited thereto. Changes, additions, and the like in the design are permitted without departing from the gist of the invention according to each claim of the scope of the invention.

For example, in the first embodiment, an example has been shown in which the braking force applied by the automatic brake is reduced by using the own vehicle slip angle θ ^* as the amount of lateral movement state of the own vehicle. As the lateral motion state amount, a lateral acceleration, a yaw rate, or a combination thereof may be used in addition to the vehicle slip angle θ ^* .

In the first embodiment, an example has been shown in which the braking deceleration (braking force) is reduced when the driver operates the steering wheel by using the gain K that changes from K = k to K = 0. The amount of reduction or reduction ratio of the braking deceleration (braking force) may be obtained from the amount of lateral movement of the host vehicle such as θ ^*, and the braking force may be reduced when the driver operates the steering wheel.

[Brief description of the drawings]

FIG. 1 is an overall system diagram showing an automatic brake control device according to a first embodiment.

FIG. 2 is a control block diagram illustrating a control controller of the automatic brake control device according to the first embodiment.

FIG. 3 is a flowchart illustrating a flow of a calculation process of a braking deceleration required for the host vehicle to avoid an obstacle, which is executed by the automatic brake fluid pressure command value generation unit of the first embodiment.

FIG. 4 is a flowchart illustrating a flow of a process of calculating a gain K necessary for the own vehicle to avoid an obstacle, which is executed by the automatic brake fluid pressure command value generation unit of the first embodiment.

FIG. 5 is a flowchart showing a flow of a calculation process of a target braking deceleration αr for reducing a braking force required for the own vehicle to avoid an obstacle, which is executed by the automatic brake fluid pressure command value generation unit of the first embodiment. It is.

FIG. 6 is a characteristic diagram showing how to change a gain K for avoiding an obstacle.

FIG. 7 is a conversion characteristic diagram for replacing a braking force reduction target braking deceleration with an automatic brake fluid pressure command value.

FIG. 8 is an operation explanatory diagram illustrating a situation where the host vehicle avoids an obstacle.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 laser radar (obstacle detecting means) 2 steering wheel steering angle sensor 3 yaw rate sensor 4 distance information unit (distance detecting means and relative speed detecting means) 5 controller 6 brake unit 7 wheel speed sensor 101 own vehicle body speed estimating unit 102 vehicle Slip angle calculation unit (vehicle behavior state detection means) 103 Obstacle vehicle speed estimation unit 103 104 Automatic brake fluid pressure command value generation unit (automatic brake means and brake force reduction means)

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Hiromitsu Toyota Toyota 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture Nissan Motor Co., Ltd. Terms (reference) 3D046 BB18 HH08 HH20 HH21 HH22 HH36 JJ11

Claims (3)

[Claims] 1. An obstacle detecting means for detecting an obstacle in front of a host vehicle, a distance detecting means for detecting a distance to an obstacle based on a result of the obstacle detecting means, and a result of the obstacle detecting means Relative speed detecting means for detecting a relative speed with respect to an obstacle based on the vehicle behavior state detecting means for detecting a vehicle behavior state of the own vehicle; and for the own vehicle, the distance detecting means and relative speed detection. Automatic braking means for automatically applying a brake based on the result of the means, and the braking force based on a lateral motion state amount of the own vehicle detected by the vehicle behavior state detecting means when the braking force is generated by the automatic braking. An automatic brake control device comprising: a braking force reduction unit configured to reduce a brake force. 2. The automatic brake control device according to claim 1, wherein said braking force reduction means is means for reducing a braking force based on a slip angle of said host vehicle. . 3. The automatic brake control device according to claim 2, wherein the braking force reducing unit has a large ratio of the slip angle of the host vehicle to a slip angle required for the host vehicle to avoid an obstacle. An automatic brake control device, characterized in that it is means for greatly reducing the braking force.