JP7439413B2 - automatic braking device - Google Patents

Description

TECHNICAL FIELD The present invention relates to an automatic braking device.

Automatic braking (AEB, automatic emergency braking) has been put into practical use to reduce damage when a collision with an obstacle in front of the vehicle or a preceding vehicle is predicted. Patent Document 1 discloses changing the braking force distribution between the front wheels and the rear wheels when automatic braking is activated.

JP2018-62273A

By the way, this kind of automatic braking applies strong braking by boosting brakes, so for example, if a light truck or other small vehicle has a tendency to have an uneven load on the left or right side, it may be a slight uneven load tendency that does not interfere with normal driving. Even if there is, there is a risk that deflection will occur when the automatic brake is activated, the behavior of the vehicle will become unstable, and the desired braking effect may not be obtained.

The present invention has been made in view of the above-mentioned circumstances, and its purpose is to provide an automatic braking system that is advantageous in suppressing the deflection of a vehicle when there is a tendency for unbalanced loads to the left and right, and ensuring braking effectiveness. Our goal is to provide the following.

In order to solve the above problems, the present invention
means for detecting obstacles ahead in the direction of travel;
an automatic brake control unit that issues a brake request when a collision with the obstacle is predicted;
a brake actuator that operates an automatic brake according to the brake request;
In automatic braking systems for vehicles equipped with
Further comprising a yaw rate detection unit that detects a yaw rate of the vehicle,
When the yaw rate detection unit detects that the deflection of the vehicle is equal to or greater than a threshold value during the automatic brake operation based on the brake request, the value of the brake request is smaller than when the deflection is less than the threshold value. The automatic braking device is characterized in that the automatic braking device is configured to be changed to a value.

According to the present invention, when the deflection of the vehicle exceeds a threshold value while the automatic brake is operating, the value of the brake request is changed to a small value and the braking force is limited. ) is suppressed, which is advantageous in ensuring overall emergency braking performance due to the braking effect achieved by maintaining the vehicle posture.

1 is a block diagram showing a vehicle equipped with a system according to an embodiment of the present invention. It is a control map of the brake demand value based on embodiment of this invention. 5 is a control map of brake request values before and after application of control according to an embodiment of the present invention. It is a control map of the yaw rate threshold based on the yaw rate change speed. It is a control map of the yaw rate threshold based on the amount of course deflection. It is a flow chart which shows control concerning a 1st embodiment of the present invention. It is a flow chart which shows control concerning a 2nd embodiment of the present invention. It is a flow chart which shows control concerning a 3rd embodiment of the present invention. It is a flow chart which shows control concerning a 4th embodiment of the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings.
In FIG. 1, the vehicle 1 includes a brake control unit 20 (brake controller (ECU) and brake actuator (hydraulic actuator)) that can individually control the braking force of the brakes 33 on the left and right front wheels 3 and the brakes 44 on the left and right rear wheels 4. , a brake system that constitutes an ABS/vehicle behavior stabilization device including a steering angle sensor 21, a yaw rate detection section 22, a wheel speed sensor 23 for the left and right front wheels 3, and a wheel speed sensor 24 for the left and right rear wheels 4. There is.

The automatic braking device is constructed by adding an AEB control unit 10 (AEB controller) and a front detection means (AEB sensor) consisting of a front camera 11 or a millimeter wave radar (not shown) to the above-mentioned brake system as a base. be done.

If a stereo camera having a function of measuring the inter-vehicle distance to the preceding vehicle in front of the host vehicle is used as the front camera 11, the millimeter wave radar may be omitted. Further, the forward detection means (AEB sensor) can be configured with a monocular camera that detects the preceding vehicle and obstacles, and a millimeter wave radar that measures the distance between vehicles.

That is, either or both of the front camera 11 (stereo camera) and the millimeter wave radar constitute a distance measuring means that measures the inter-vehicle distance to the preceding vehicle in front of the host vehicle. Measurement of the inter-vehicle distance by the distance measuring means is performed dynamically at a predetermined time rate, and the relative speed of the preceding vehicle with respect to the own vehicle is determined as a change in the inter-vehicle distance per unit time. From this relative speed and inter-vehicle distance, a predicted collision time (TTC) is determined as a value obtained by dividing the inter-vehicle distance by the relative speed.

The AEB control unit 10 (AEB controller) is a control unit (ECU) that constitutes an automatic brake system (AEBS) together with a forward detection means (AEB sensor) and a brake control unit 20 (brake actuator), and it stores control programs, setting data, etc. ROM that stores the control program and setting data, RAM that stores dynamic data and arithmetic processing results, a CPU that performs arithmetic processing, and a microcontroller (MCU) and input/output circuits that are equipped with communication I/F, etc. The brake actuator is controlled based on the detection information of the AEB sensor.

Specifically, the AEB control unit 10 collects information (vehicle distance, relative speed) of the preceding vehicle (or obstacle) detected by the AEB sensor (front camera 11, millimeter wave radar) and vehicle information (vehicle speed) of the own vehicle. ), and when it is determined that there is a high possibility of a collision, such as when the predicted collision time is less than a predetermined value, the brake control unit 20 (brake actuator, hydraulic actuator) applies the brakes. It issues a request and activates the brake equipment on each wheel to perform automatic braking (automatic emergency braking). Note that the AEB control unit 10 may be implemented in the AEB sensor (front camera 11) instead of a separate controller.

By the way, as mentioned at the beginning, in light trucks and other small vehicles, the weight of the cargo is relatively large compared to large cargo vehicles, and this can lead to weight imbalances in the cargo itself or to overloading the cargo bed. If there is a weight imbalance between the left and right sides (unbalanced load tendency) depending on the loading position, even if it is a slight unbalanced load tendency that does not interfere with normal driving, if strong braking is applied by the boost brake when the automatic brake is activated, the unbalanced load tendency will occur. This causes deflection around the vertical axis (yaw axis), which makes the behavior of the vehicle unstable, and there is a possibility that the desired braking effect may not be obtained.

Therefore, in the automatic braking device according to the present invention, the detection information of the yaw rate detection unit 22 (and the steering sensor 21) is acquired by the AEB control unit 10, and the amount of deflection (deflection speed) of the vehicle is equal to or higher than the set threshold. is detected, the brake request value (control map) output from the AEB control unit 10 to the brake control unit 20 is configured to be changed to a value advantageous for deflection suppression.

The control map change for the brake request value includes (i) a form in which control maps with different characteristics are set, (ii) a form in which the maximum required deceleration is limited, and a combination thereof. Furthermore, there is an embodiment (third embodiment) in which image processing by the course detection section 12 and the inclination detection section 13 is used in conjunction with vehicle deflection detection, and these will be described later.

(First embodiment)
FIG. 2 shows a control map of the brake request value (deceleration) that is set when deflection is detected during automatic brake operation. In this example, the maximum deceleration Gx is limited to 60 to 70% of the maximum deceleration before deflection detection (Gx' shown in FIG. 3, for example 1G), and also depends on the distance X to the obstacle and the vehicle speed V. The brake request value (deceleration) is further limited to around 30% of the maximum deceleration before deflection detection. % range).

Furthermore, in FIG. 2, V1 indicates the brake request value (deceleration) when traveling at low speed, V2 when traveling at relatively medium speed, and V3 indicating the brake demand value (deceleration) when traveling at relatively high speed. For example, V1 = 30 km/h , V2=40km/h, V3=50km/h, the distance X to the obstacle is, for example, X1=5m, X2=7m, X3=10m, X4=15m, and the horizontal axis is not a linear scale but a logarithmic scale. It has become.

According to the control map in FIG. 2, for example, in the case of low speed V1 (30 km/h) shown by the solid line in the figure, the deceleration is limited to Gn until the distance to the obstacle is X=X2 (7 m); ~X1 (5 m), the deceleration increases as the distance to the obstacle approaches, and is set to the maximum deceleration Gx after deflection detection within the distance to the obstacle X=X1 (5 m).

In addition, in the case of medium speed V2 (40 km/h) shown by the solid line and broken line in the figure, the deceleration is limited to Gn until the distance to the obstacle X = X3 (10 m), but from X3 to X2 (7 m) , the deceleration increases as the distance to the obstacle approaches, and within the distance X=X2 (7 m), the deceleration is set to the maximum deceleration Gx after deflection detection.

On the other hand, in the case of the relatively high speed V3 (50 km/h) shown by the dashed line in the figure, the distance to the obstacle approaches X=X4 (15 m) to X3 (10 m). The deceleration increases accordingly, and within the distance X=X3 (10 m), the deceleration is set to the maximum deceleration Gx after the deflection is detected.

That is, on the low speed V1 side where the braking distance is relatively short, the deceleration is limited to a relatively small deceleration Gn until the short distance X2, and the maximum deceleration Gx is reached on the closest approach side, whereas the braking distance is relatively long On the required high speed V3 side, the deceleration Gn to Gx is limited depending on the distance in X4 to X3, which are long distances, but within that range, the deceleration is set to the maximum deceleration Gx.

By setting a control map of the brake request value according to the distance to the obstacle ) is suppressed and the vehicle posture is maintained, thereby ensuring overall emergency braking performance, and is also advantageous in avoiding lane deviations caused by increased deflection when automatic braking is activated. be.

Next, FIG. 3 shows the setting of the brake request value over time before and after the deflection is detected when the automatic brake is activated. In this example, before the deflection is detected, as shown by the broken line in the figure, the brake request value related to automatic braking is temporarily held at deceleration Gx immediately after automatic braking starts ta, and then reaches the maximum deceleration at time tb. It is raised to Gx'.

On the other hand, after the deflection is detected, as shown by the solid line in the figure, immediately after the automatic braking starts ta, it is temporarily held at a value lower than the maximum deceleration Gx, and then is increased to the maximum deceleration Gx at time tb. . This example shows a case where the brake request value is limited to a maximum deceleration Gx that is 60 to 70% of the maximum deceleration Gx' before deflection detection.

Above, we have described how to change the brake request value when vehicle deflection is detected during automatic braking. It can also be set dynamically based on the yaw rate change rate, angular acceleration around the yaw axis. The amount of deflection of the vehicle is detected as a yaw rate by the yaw rate detection section 22, the integral value thereof becomes the amount of deflection (yaw angle), and the differential value of the yaw rate becomes the yaw rate change speed.

Therefore, in the example shown in FIG. 4, in a region where the yaw rate change speed is small, a relatively large threshold value (γa) is set to ensure the maximum braking force of the automatic brake, while the yaw rate change speed is (γ 'a) In the above range, the threshold value is set to be smaller as the yaw rate change speed increases, and furthermore, in the range where the yaw rate change speed is (γ'b) or above, the threshold value is set to the minimum value (γb). If the deflection is expected to increase after the detection time, the brake request value (control map) is changed as early as possible to ensure deflection suppression.

FIG. 6 is a flowchart showing deflection suppression control according to the first embodiment. In the figure, when the AEB control unit 10 and the front camera 11 (AEB sensor) are in operation (step 100), when an obstacle is detected by the front camera 11 (AEB sensor) and the automatic brake is activated (step 110), first, The amount of deflection of the vehicle is measured based on the detection information of the yaw rate detection section 22 (step 120).

Next, the AEB control unit 10 determines whether the deflection amount is equal to or greater than the threshold (step 130), and if the deflection amount is equal to or greater than the threshold, the brake request value is changed to the control map for vehicle deflection ( Step 140). If the deflection amount is less than the threshold value, the brake request value is not changed and the normal brake request value is maintained.

(Second embodiment)
In the above embodiment, the threshold value of the deflection amount is dynamically set based on the rate of change of the yaw rate (FIG. 4). It is also possible to dynamically set the deflection amount threshold based on the steering amount.

For example, as shown in the flowchart of FIG. 7, when an obstacle is detected by the front camera 11 (AEB sensor) in the operating state of the system (step 200) and the automatic brake is activated (step 210), first, the steering angle sensor The amount of steering detected in step 21 is acquired by the AEB control unit 10 (step 211), and it is determined whether the amount of steering is greater than or equal to the threshold (step 212). If the amount of steering is less than the threshold, A relatively large deflection amount threshold (γa) is maintained to ensure a large automatic brake braking force (step 213), but if the steering amount is equal to or greater than the threshold, a relatively small deflection amount threshold is maintained. (γb) (214).

Next, the amount of deflection of the vehicle is measured based on the detection information of the yaw rate detection unit 22 (steps 220, 221), and the amount of deflection is compared with each threshold value (γa, γb), and it is determined whether the amount of deflection is greater than or equal to the threshold value. (steps 230, 231).

If the amount of deflection is equal to or greater than the threshold value in either case, the brake request value is changed to the control map for vehicle deflection (step 240). If the deflection amount is less than the threshold value, the brake request value is not changed and the normal brake request value is maintained.

In the second embodiment, a case has been described in which the deflection amount threshold value is switched based on the steering amount detected by the steering angle sensor 21. The detected lateral G can also be used in conjunction with the steering amount or in place of the steering amount to switch the deflection amount threshold.

(Third embodiment)
In each of the embodiments described above, the deflection speed, steering amount, lateral G, etc. during automatic braking are detected, and the deflection amount threshold value for determining whether to change the brake request value (control map) is adjusted based on the detected deflection speed, steering amount, lateral G, etc. However, by detecting the unbalanced load tendency of the vehicle from the course deflection and lateral inclination of the vehicle based on the image of the front camera 11, the brake request value (control map) can be set before the automatic brake is activated. It is also possible to perform switching.

As shown in FIG. 1, in the automatic braking system of this embodiment, a course detection section 12 and a tilt detection section 13 are arranged in parallel to an AEB control section 10. These are stored as program modules that perform image processing in the AEB control unit 10 (ECU).

The course detection unit 12 performs image processing such as edge extraction and optical flow extraction from the image taken by the front camera 11 to recognize marking lines (white lines, etc.) on the road, detect the course of the vehicle, and detect the course of the vehicle. The amount of deflection of the vehicle with respect to the direction (the amount of course deflection ψ) is estimated. The tilt detection unit 13 estimates the lateral tilt of the vehicle from the relationship between the angle of view of the front camera 11 fixed to the vehicle and the road surface.

FIG. 5 shows the setting of the deflection amount threshold (yaw rate) based on the course deflection amount (ψ) estimated by the course detection unit 12. When the course deflection amount ψ is less than the threshold value (ψc), the deflection amount Maintain a relatively large threshold value (γa: initial value), and change the deflection amount threshold to a relatively small threshold value (γc) when the course deflection amount (ψ) is greater than or equal to the threshold value (ψc). This allows the system to understand the tendency of the vehicle's unbalanced load before applying the automatic brakes, and use this information to control the unbalanced load.

FIG. 8 is a flowchart showing deflection suppression control according to the third embodiment. In the operating state of the system (step 300), the tilt detection unit 13 estimates the lateral tilt of the vehicle based on the image of the front camera 11. , is compared with a predetermined threshold (step 301), and if it is less than the predetermined threshold, a relatively large threshold (γa: initial value) is maintained.

On the other hand, if it is determined that the estimated value of the lateral inclination is larger than the predetermined threshold, the deflection amount threshold is changed to a relatively small threshold (γc) (step 303).

In such a state, when an obstacle is detected by the front camera 11 (AEB sensor) and the automatic brake is activated (steps 310, 311), if the lateral tilt of the vehicle is not detected, the yaw rate detection unit 22 detects the obstacle. The amount of deflection of the vehicle is measured based on the information (step 320), and if the amount of deflection is equal to or greater than the threshold value (γa) (step 330), the brake request value (control map) is changed to the brake request value (control map) when the vehicle is deflected (step 340). If the deflection amount is less than the threshold value (γa), the normal brake request value is maintained.

On the other hand, if the lateral tilt of the vehicle is detected, the amount of deflection of the vehicle is measured based on the detection information of the yaw rate detection unit 22 (step 321), and if the amount of deflection is equal to or greater than a relatively small threshold (γc), (Step 331), the brake request value (control map) is changed to the one when the vehicle is deflected (Step 340), and if the amount of deflection is less than the threshold value (γc), the normal brake request value is maintained.

In the above embodiment, the deflection amount threshold is changed to a relatively small threshold (γc) in step 303, but at this point, the brake request value when the automatic brake is activated is changed to It may be changed to the required value (control map).

Further, the determination of lateral inclination in step 301 is performed when the deflection amount is less than the respective threshold value in steps 330 and 331 during automatic brake operation, and when lateral inclination is detected, step 340 and 341 are performed, respectively. It is also possible to configure the brake request value (control map) to be changed back to the brake request value (control map) when the vehicle is deflected.

(Fourth embodiment)
In the above embodiment, a case has been described in which the course deflection and lateral inclination estimated from image processing by the course detection unit 12 and the inclination detection unit 13 are used to change the deflection amount threshold before automatic brake activation. It can also be used to change the deflection amount threshold value or brake request value (control map) in .

For example, as shown in the flowchart of FIG. 9, when an obstacle is detected by the front camera 11 (AEB sensor) in the operating state of the system (step 400) and the automatic brake is activated (step 410), the image of the front camera 11 is Based on the image processing such as optical flow extraction, the course detection unit 12 detects the course deflection amount (ψ) (step 411), and it is determined whether the course deflection amount is equal to or greater than the threshold (ψc) (step 411). 412).

When the amount of course deflection detected by the course detection unit 12 is less than the threshold value (ψc), a relatively large deflection amount threshold value (γa) is maintained to ensure the maximum braking force of the automatic brake. (Step 413), but if the amount of course deflection is equal to or greater than the threshold (ψc), it is changed to a relatively small deflection amount threshold (γb) (414).

Next, the amount of deflection of the vehicle is measured based on the detection information of the yaw rate detection unit 22 (steps 420, 421), and the amount of deflection is compared with each threshold value (γa, γb), and it is determined whether the amount of deflection is greater than or equal to the threshold value. (steps 430, 431).

If the amount of deflection is equal to or greater than the threshold value in either case, the brake request value is changed to the control map for vehicle deflection (step 440). If the deflection amount is less than the threshold value, the brake request value is not changed and the normal brake request value is maintained (step 450).

In the second embodiment, a case has been described in which the deflection amount threshold value is switched based on the amount of course deflection detected by the course detection section 12. It can also be used in combination with the course deflection amount or in place of the course deflection amount to switch the deflection amount threshold.

Although several embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and it is understood that various modifications and changes can be made based on the technical idea of the present invention. I would like to add.

1 Vehicle 3 Front wheels 4 Rear wheels 10 AEB control section (automatic brake control section)
11 Front camera 12 Course detection section 13 Tilt detection section 20 Brake control section 21 Steering angle sensor 22 Yaw rate detection section 23, 24 Wheel speed sensor

Claims (4)

means for detecting obstacles ahead in the direction of travel;
an automatic brake control unit that issues a brake request when a collision with the obstacle is predicted;
a brake actuator that operates an automatic brake according to the brake request;
In automatic braking systems for vehicles equipped with
Further comprising a yaw rate detection unit that detects a yaw rate of the vehicle,
When the yaw rate detection unit detects that the deflection of the vehicle is equal to or greater than a threshold value during the automatic brake operation based on the brake request, the value of the brake request is smaller than when the deflection is less than the threshold value. is configured to be changed to a value , and
An automatic braking device characterized in that the threshold value becomes smaller as the yaw rate detected by the yaw rate detection section or the rate of change thereof increases . means for detecting obstacles ahead in the direction of travel;
an automatic brake control unit that issues a brake request when a collision with the obstacle is predicted;
a brake actuator that operates an automatic brake according to the brake request;
In automatic braking systems for vehicles equipped with
further comprising a yaw rate detection unit that detects a yaw rate of the vehicle , a steering angle sensor and/or a lateral acceleration sensor ,
When the yaw rate detection unit detects that the deflection of the vehicle is equal to or greater than a threshold value during the automatic brake operation based on the brake request, the value of the brake request is smaller than when the deflection is less than the threshold value. is configured to be changed to a value , and
The threshold value is configured to be changed to a smaller value when the steering angle and/or lateral acceleration detected by the steering angle sensor and/or lateral acceleration sensor is equal to or greater than a predetermined value. automatic braking device. means for detecting obstacles ahead in the direction of travel;
an automatic brake control unit that issues a brake request when a collision with the obstacle is predicted;
a brake actuator that operates an automatic brake according to the brake request;
In automatic braking systems for vehicles equipped with
The vehicle further includes: a yaw rate detection unit that detects a yaw rate of the vehicle; a front camera that captures an image in front of the vehicle in the traveling direction; and an image processing unit that detects the course of the vehicle from the image of the front camera ;
When the yaw rate detection unit detects that the deflection of the vehicle is equal to or greater than a threshold value during the automatic brake operation based on the brake request, the value of the brake request is smaller than when the deflection is less than the threshold value. is configured to be changed to a value , and
An automatic braking device characterized in that the threshold value is changed to a smaller value when the course deflection with respect to the straight-ahead direction detected by the image processing means is greater than or equal to a predetermined value . means for detecting obstacles ahead in the direction of travel;
an automatic brake control unit that issues a brake request when a collision with the obstacle is predicted;
a brake actuator that operates an automatic brake according to the brake request;
In automatic braking systems for vehicles equipped with
The vehicle further includes: a yaw rate detection unit that detects a yaw rate of the vehicle; a front camera that captures an image in front of the vehicle in a traveling direction; and an image processing unit that detects a lateral inclination of the vehicle with respect to a road surface from an image of the front camera ;
When the yaw rate detection unit detects that the deflection of the vehicle is equal to or greater than a threshold value during the automatic brake operation based on the brake request, the value of the brake request is smaller than when the deflection is less than the threshold value. is configured to be changed to a value , and
An automatic braking device characterized in that the threshold value is changed to a smaller value when the lateral slope is equal to or greater than a predetermined value .

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