JP2983711B2 - Vehicle contact prevention device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects a distance and a relative speed between an own vehicle and an obstacle, judges a possibility of contact from the detection result, and automatically performs a contact avoidance measure such as automatic braking. The present invention relates to a vehicle contact prevention device used in a vehicle.

[0002]

2. Description of the Related Art Conventionally, as a contact prevention device for a vehicle of this kind, for example, Japanese Patent Publication No. 39-2565 and Japanese Patent Publication No.
As disclosed in Japanese Patent Application Laid-Open No. 9-5668 and the like, the distance and the relative speed between the vehicle and an obstacle in front are continuously detected by using an optical method or ultrasonic waves, and the detected speed is detected. Judgment is made based on the distance and relative speed between the host vehicle and the obstacle in front, and if it is judged that there is a possibility of contact, the actuator is actuated to automatically brake each wheel. It is known to prevent a collision or a collision. In addition to this automatic braking, there is also known a system in which when it is determined that there is a possibility of contact, the steering is automatically performed to avoid the contact (see JP-A-1-124008). ).

In such a contact prevention device, for example, when automatic braking is applied as a contact avoidance measure,
The braking distance required for the vehicle not to come into contact with the obstacle ahead due to the braking is affected by road conditions such as a road surface friction coefficient. Therefore, for example, Japanese Patent Laid-Open No. 52-1212
No. 38 discloses that the braking force is corrected and controlled in accordance with the difference between the actual deceleration and the set deceleration at the time of automatic braking, regardless of the friction coefficient of the road surface or the engagement state between the wheel and the road surface. It is disclosed that contact with an obstacle ahead can be reliably prevented. Also, Japanese Patent Application Laid-Open No. 54-34343 discloses that the possibility of contact with an obstacle ahead is determined based on road condition information sent from a ground-side transmission device.

[0004]

However, in the former case, the so-called feedback control is used to correct the braking in accordance with the difference between the actual deceleration and the set deceleration. I hate not being able to. In the latter case, in order to obtain from the ground-side transmitting device information on the road conditions that change with the traveling of the vehicle, a large number of transmitting devices must be provided along the road. There are many difficulties in doing so.

SUMMARY OF THE INVENTION The present invention has been made in view of the foregoing, and it is an object of the present invention that the road condition in which the own vehicle travels has the most direct and early effect on the vehicle ahead of the own vehicle. The present invention is directed to providing a vehicle contact prevention device that can more reliably prevent contact by obtaining information on road conditions and the like from the preceding vehicle and determining the possibility of contact.

[0006]

In order to achieve the above-mentioned object, a solution of the present invention comprises a detecting means for detecting a distance and a relative speed between an own vehicle and an obstacle. When the distance between the subject vehicle and the obstacle becomes smaller than a predetermined value, the contact prevention device for a vehicle that automatically takes measures to avoid contact with the obstacle is provided in a vehicle in front of the subject vehicle. A receiver for receiving the friction coefficient information of the traveling road surface and the turning radius information of the road, which are sent from the transmitter, and based on the friction coefficient information and the turning radius information obtained by the receiver, A predetermined value setting means for setting the predetermined value as a threshold value for performing the contact avoidance measure to a larger value as the coefficient is smaller and the turning radius is smaller.

[0007]

According to the present invention, according to the present invention, in addition to the distance and the relative speed between the own vehicle and the preceding vehicle, the friction coefficient of the traveling road surface obtained from the transmitter of the preceding vehicle and obtained by the receiver, and the road surface Based on the information of the turning radius, as the coefficient of friction is smaller and the turning radius is smaller, the threshold value for performing the contact avoidance measure is set to a larger value. The possibility of contact with the vehicle ahead is appropriately determined, and contact avoidance measures such as automatic braking are taken based on this determination.

[0008]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 3 show an automatic braking device for a vehicle according to an embodiment of the present invention, FIGS. 1 and 2 show a hydraulic circuit configuration of the automatic braking device, and FIG. 3 is a block configuration of the automatic braking device. Is shown.

In FIGS. 1 and 2, reference numeral 1 denotes a master back for increasing the depression force of the brake pedal 2 by the driver;
Reference numeral 3 denotes a master cylinder that generates a braking pressure corresponding to the stepping force increased by the master back 1. The braking pressure generated by the master cylinder 3 is first sent to the automatic braking valve unit 4, and thereafter, , And ABS (anti-skid brake device) valve unit 5 to be supplied to brake devices 6 of the respective wheels.

The automatic brake valve unit 4 includes a shutter valve 11, a pressure increasing valve 12, and a pressure reducing valve 1 for interrupting communication between the master cylinder 3 and the brake device 6.
The three valves 11 to 13 are all electromagnetic two-port two-position switching valves. A motor-driven oil pump 14 and an accumulator 15 for storing pressure oil discharged from the oil pump 14 and maintaining the oil at a constant pressure are interposed between the pressure increasing valve 12 and the master cylinder 3. Has been established. When the shutter valve 11 is in the open position, the brake pedal 2
Is applied by the brake device 6 of each wheel according to the stepping force of the vehicle. On the other hand, when the shutter valve 11 is in the closed position,
When the pressure-increasing valve 12 is switched to the open position and the pressure-reducing valve 13 is switched to the closed position, the pressure oil from the accumulator 15 is supplied to the brake device 6 of each wheel to apply braking, and the pressure-increasing valve 12 is moved to the closed position. When the pressure reducing valve 13 is switched to the open position, the pressure oil is returned from the brake device 6 and the braking is weakened. The switching of the three valves 11 to 13 is performed by an actuator 16 including a voltage source for applying a voltage to each of the valves, and the actuator 16 is controlled by receiving a signal from a control box 17.

The ABS valve unit 5 has a three-port two-position switching valve 21 provided for each wheel, and a braking pressure applied to each brake device 6 by switching the valve 21 during braking. Is controlled so that each wheel does not lock. Although the configuration of the ABS is not described in detail, it includes a motor-driven oil pump 22 and accumulators 23 and 24 in addition to the switching valve 21.
The brake device 6 for each wheel includes a disk 26 that rotates integrally with the wheels, and a caliper 27 that receives the braking pressure from the master cylinder 3 and clamps the disk 26.

On the other hand, in FIG. 3, reference numeral 31 denotes an ultrasonic radar unit provided at the front of the vehicle body. The ultrasonic radar unit 31, which is not shown in detail in the drawing, transmits an ultrasonic wave from a transmitting unit as is well known. An operation for transmitting to an obstacle such as a vehicle ahead of the own vehicle and receiving a reflected wave reflected from the front obstacle at a receiving unit, and receiving a signal from the radar unit 31 The unit 32 calculates the distance and the relative speed between the host vehicle and the obstacle ahead of the vehicle based on the delay time (Doppler shift) from the transmission time of the radar reception wave. 33 and 3
Reference numeral 4 denotes a pair of radar head units provided on the left and right of the front part of the vehicle body, respectively.
The transmitting unit 34 transmits the pulsed laser light from the transmitting unit to the obstacle in front of the own vehicle, and receives the reflected light reflected on the front obstacle by the receiving unit. A signal processing unit 35 converts signals from the radar head units 33 and 34 into a signal processing unit 35.
And calculates the distance and the relative speed between the host vehicle and the obstacle ahead based on the delay time from the transmission time of the laser reception light. And the arithmetic unit 32
Gives priority to the calculation result of the distance and relative speed by the system of the radar head units 33 and 34, and uses the calculation result of the distance and relative speed by the system of the ultrasonic radar unit 31 in an auxiliary manner. These constitute a distance / relative speed detecting means 36 for detecting the distance and the relative speed between the own vehicle and the obstacle ahead.

The transmitting and receiving directions of the pulse laser light by the two radar head units 33 and 34 are provided so as to be changeable in the left and right horizontal directions by a motor 37, and the operation of the motor 37 is controlled by an arithmetic unit 32. 38
Is an angle sensor for detecting the transmission / reception direction of the pulse laser light from the rotation angle of the motor 37.
Is input to the arithmetic unit 32, and the radar head units 33 and 34 in the arithmetic unit 32
The transmission / reception direction of the pulsed laser light is added to the calculation of the distance and the relative speed by the system.

Reference numeral 40 denotes a turning radius detecting means for detecting a turning radius of a road on which the vehicle travels. The turning radius detecting means 40 indirectly determines a turning radius from the lateral acceleration of the vehicle detected by a sensor. There are conventionally known ones to be determined and ones for directly detecting the turning radius by image processing using a projection device, but any of them may be used. 41 is a steering angle sensor for detecting a steering angle, 42 is a vehicle speed sensor for detecting a vehicle speed, 4
Reference numeral 3 denotes a front-rear G sensor for detecting the front-rear acceleration (front-rear G) of the vehicle, reference numeral 44 denotes a road surface μ sensor for detecting a road surface friction coefficient (μ), and detection signals of these various sensors 40 to 44 are:
It is input to a control unit 45 that controls the actuator 16. The control unit 45 also receives signals of the distance and the relative speed between the own vehicle and the obstacle ahead obtained by the arithmetic unit 32.
5 and 32 are housed in the control box 17 (see FIG. 2). Reference numeral 46 denotes an alarm display unit provided on an instrument panel in the vehicle compartment. The alarm display unit 46 is provided with an alarm buzzer 47 for receiving signals from the control unit 45 and a distance display unit 48.

Reference numeral 51 denotes a receiver for receiving information transmitted from a transmitter 52 provided in a vehicle in front of the vehicle. The information exchanged between the transmitter / receivers 51 and 52 is as follows.
In the case of the present embodiment, the turning radius of the road detected by the turning radius detecting means 40 provided in the preceding vehicle in the same manner as the own vehicle,
And the friction coefficient of the road surface detected by the road surface μ sensor 44. The information obtained by the receiver 51 is input to the control unit 45.

FIG. 4 shows a control flow of automatic braking by the control unit 45 for preventing contact. In this control flow, first, after starting, various signals are read in step S1, and various threshold values L0 are read in step S2.
, L2, L3 are calculated. The threshold value L0 is the distance between the host vehicle and the obstacle in front of which there is a possibility of contact between the host vehicle and the obstacle ahead and automatic braking is started to prevent contact. The threshold L2 is the distance between the host vehicle and the obstacle ahead, which issues an alarm prior to the start of automatic braking. The threshold value L3 is the distance between the host vehicle and the obstacle ahead of the vehicle where the possibility of contact after the start of the automatic braking is eliminated and the automatic braking is released. These threshold values L0, L2, L3 are calculated according to a subroutine shown in FIG. 5, and the calculation method will be described later.

After the calculation of the various threshold values L0, L2, L3, at step S3, the relative speed V1 between the host vehicle and the obstacle ahead is determined.
Is greater than or equal to zero, that is, whether or not both are approaching. If this determination is YES, it is further determined in step S4 whether or not the distance L1 between the host vehicle and the obstacle in front (hereinafter, referred to as an inter-vehicle distance) is smaller than the threshold value L2 for generating an alarm. If the determination is YES, step S
5 sounds the alarm buzzer 47. Subsequently, in step S6, it is determined whether or not the inter-vehicle distance L1 is smaller than a threshold value L0 for starting automatic braking. If the determination is YES, the actuator 16 is set in step S7 to apply automatic braking with full braking. And then return. If the determination in step S4 or S6 is NO, the process immediately returns.

On the other hand, when the determination in step S3 is NO, that is, when the own vehicle and the front obstacle (front vehicle) are moving away from each other, in step S8, the inter-vehicle distance L1 becomes larger than the threshold value L3 for releasing automatic braking. It is determined whether it is small. If the determination is YES, the process returns in step S9 with the automatic braking applied, while if the determination is NO, the process returns after releasing the automatic braking in step S10.

Next, a method of calculating various threshold values L0, L2, L3 according to a subroutine shown in FIG. 5 will be described. In this subroutine, after starting, first, in step S21, the transmitter 52 of the vehicle ahead is transmitted to the receiver 51.
It is determined whether or not the information of the road condition (specifically, the turning radius r1 of the road and the friction coefficient μ1 of the road surface) has been input from. If the determination is YES, a step S22 compares the road turning radius r1 of the preceding vehicle with the road turning radius r0 of the own vehicle detected by the turning radius detecting means 40 of the own vehicle, and then proceeds to step S22. The smaller one in S23 or S24 is set as the road turning radius r on the threshold value calculation. continue,
In step S25, after comparing the road surface friction coefficient μ1 on the front vehicle side with the road surface friction coefficient μ0 on the host vehicle detected by the road surface μ sensor 44 of the own vehicle, a comparison is made in step S26 or S27.
The smaller one is set as the road surface friction coefficient μ in the calculation of the threshold value, and the routine goes to Step S29. If the determination in step S21 is NO, in step S28, the road turning radius r0 and the road surface friction coefficient μ0 of the own vehicle are respectively set to the road turning radius r and the road surface friction coefficient μ in the calculation of the threshold value, and then in step S29. Move to.

In step S29, the lateral acceleration α of the vehicle is estimated from the road turning radius r and the vehicle speed v0 detected by the vehicle speed sensor 42 by the following equation.

[0022] α = v0 ² / r Then, the force limit which can tire takes charge in Step S30, estimates a front-rear are permissible acceleration β by the following equation.

Β = ｛(μg) ² −α ² ｝ ^1/2 The first term in this equation indicates the slip limit of the tire and is affected by the road surface friction coefficient μ.

Thereafter, in step S30, a threshold value L0 for starting automatic braking is calculated using the allowable longitudinal acceleration β. The calculation formula at that time includes the following formula or formula.

[0025] ^{L0 = v0 2 / 2β ... L0} = V1 2 / 2β ... Formula shows a vehicle distance necessary to prevent contact between the vehicle when the preceding vehicle has stopped to collide with the front obstacle Irrespective of the magnitude of the relative speed V1, when the obstacle in front is a stationary object (that is, the relative speed V1).
(When 1 is the same as the own vehicle speed v0). The formula indicates an inter-vehicle distance required to prevent contact with a preceding vehicle when the preceding vehicle maintains a constant vehicle speed.

After calculating the threshold value L0 for starting automatic braking, a threshold value L2 for generating an alarm and a threshold value L3 for releasing automatic braking are calculated in step S32. The threshold value L2 for generating an alarm is set to a value larger by a predetermined amount than the threshold value L0 for starting automatic braking. Also, the threshold value L3 of the automatic braking release
Is set to a value larger by a predetermined amount than the threshold value L0 for starting automatic braking, and in some cases, to a value smaller by a predetermined amount.

According to the control flow shown in FIGS. 4 and 5,
In addition to the information obtained by various sensors of the vehicle, the receiver 5
The threshold L0 is set to a larger value as the road friction coefficient μ is smaller and the road turning radius r is smaller, based on the information on the road friction coefficient μ from the preceding vehicle and the road turning radius r obtained in step 1. Value setting means 53,
The predetermined value setting means 53 is housed in the control unit 45.

Next, the operation of the above embodiment, in particular, the control of automatic braking for preventing contact by the control unit 45 in the control box 17 will be described. Is smaller than the threshold value L0 for starting automatic braking, the control unit 45 activates the actuator 16,
The automatic braking is performed by switching the opening and closing of the valve in the automatic braking valve unit 4 via the voltage generated in the above. That is, while closing the shutter valve 11,
The pressure increasing valve 12 is switched to the open position, and the pressure reducing valve 13 is switched to the closed position. As a result, the pressure oil from the accumulator 15 is supplied to the brake devices 6 (calipers 27) of the respective wheels, and a full braking force is applied to the respective wheels by the operation of the brake devices 6, thereby resulting in a forward obstacle. Contact with an object can be prevented.

In this case, the obstacle ahead is a vehicle running on the same lane as the own vehicle, and information about the turning radius r1 of the road and the coefficient of friction μ1 of the road surface is input from the preceding vehicle through the receiver 51 as road conditions. When this is done, the turning radius r1 of the road in front of the vehicle and the friction coefficient μ1 of the road surface, the turning radius r1 of the road detected by the sensors (turning radius detecting means 40 and the road surface μ sensor 44) of the own vehicle, and the road surface Are compared with each other, and the smaller value, that is, the one with the worse road condition, is used as the road turning radius r and the road surface friction coefficient μ in the calculation of the threshold value. The threshold value L0 and the like are calculated and determined. For this reason, it is possible to quickly respond to a sudden change in the road condition based on information from the preceding vehicle, such as increasing the automatic braking start distance, and to reliably prevent contact.
In addition, in order to implement this, transmitters / receivers 51 and 52 for exchanging information may be mounted only on the vehicle, so that implementation can be achieved relatively easily.

In the above embodiment, the case where the automatic braking is employed as the contact avoidance measure has been described. However, the present invention is similarly applicable to the case where the automatic steering is employed instead of or in combination with the automatic braking. Of course.

Further, in the above embodiment, the information exchanged between the preceding vehicle and the own vehicle has been described in the case of the road condition such as the turning radius of the road and the coefficient of friction of the road surface. It goes without saying that the present invention can also be applied to driving information such as deceleration of the preceding vehicle in addition to the above information.

[0032]

As described above, according to the vehicle contact prevention device of the present invention, in addition to the distance and the relative speed between the host vehicle and the preceding vehicle, the vehicle is transmitted from the transmitter provided in the preceding vehicle. Based on the information of the road surface friction coefficient and the road turning radius, the threshold value for performing the contact avoidance measure is set to a larger value as the road surface friction coefficient is smaller and the road turning radius is smaller. It is possible to appropriately judge the possibility of contact with the vehicle ahead in response to a rapid change in the vehicle speed, and it is possible to more reliably prevent contact with the vehicle ahead. In addition, since it is sufficient to mount a transmitter / receiver for information exchange only on the vehicle, implementation can be easily achieved.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of an automatic braking device for a vehicle according to an embodiment of the present invention.

FIG. 2 is a layout diagram of components of a hydraulic circuit of the automatic braking device.

FIG. 3 is a block diagram of the automatic braking device.

FIG. 4 is a flowchart showing a control flow of automatic braking by a control unit for preventing contact.

FIG. 5 is a flowchart illustrating a subroutine for calculating a threshold.

[Explanation of symbols]

 6 Brake device 16 Actuator 36 Distance / relative speed detecting means 51 Receiver 52 Transmitter 53 Predetermined value setting means

Continued on the front page (72) Inventor Yasunori Yamamoto 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Inventor Tomohiko Adachi 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda (56) References JP-A-54-33443 (JP, A) JP-A-48-24438 (JP, A) JP-A-4-241100 (JP, A) Japanese Utility Model Laid-Open No. 52-1554838 (JP, U) ( 58) Field surveyed (Int.Cl. ⁶ , DB name) B60R 21/00 G08G 1/16

Claims (1)

(57) [Claims] A detecting means for detecting a distance and a relative speed between the own vehicle and an obstacle;
The distance between the car and the obstacle has dropped below a certain value
In the vehicle contact prevention device that automatically takes measures to avoid contact with the obstacle, the information on the coefficient of friction of the traveling road surface and the turning of the road sent from the transmitter provided in the vehicle ahead of the own vehicle. A receiver for receiving radius information ; the friction coefficient information and the turning radius obtained by the receiver;
Based on the information, the smaller the friction coefficient is,
The smaller the turning radius, the more
A predetermined value that sets the above predetermined value as a threshold value to a large value
A contact prevention device for a vehicle, comprising: a setting unit .