JP2002002461A - Travel safety device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a vehicle behavior from being unstabilized by slippage of wheels, when automatic braking is conducted to avoid contact with a front side obstacle. SOLUTION: When the automatic braking is conducted to prevent an own vehicle from contacting with a body, braking forces in left and right front wheels are reduced evenly in a step S9 when the front wheels are slipped in a step S7, braking forces in the left and right rear wheels are reduced evenly in a step S11 when the rear wheels are slipped in a step S10, and the braking forces in the left and right wheels are thereby equalized to prevent turbulence of the vihicle behavior accompanied to the slippage. When a prescribed time elapses after the left and right braking forces are reduced evenly, or when a braking operation or a steering operation by a driver is detected, the braking forces in the left and right wheels are secured to the maximum to shorten a braking distance, by controlling the braking forces in the left and right wheels independently by an ABS.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking device for detecting an object by means of an object detecting means such as a radar device and for avoiding the contact when it is estimated that the vehicle may come into contact with the object. The present invention relates to a driving safety device for a vehicle that automatically operates a vehicle.

[0002]

2. Description of the Related Art A radar device detects a relative distance and a relative speed of a forward obstacle such as a preceding vehicle, and when there is a possibility that the own vehicle may come into contact with the forward obstacle, an automatic braking device is operated to move forward. A traveling safety device for a vehicle that avoids contact with an obstacle or minimizes damage when contact occurs is known, for example, from Japanese Patent Application Laid-Open No. H11-227582.

[0003]

By the way, when a vehicle equipped with such a driving safety device performs automatic braking in order to avoid contact with an obstacle in front of the vehicle, one of the right and left on a road surface having a partially different friction coefficient. When the wheel slips, the vehicle behavior in the yaw direction becomes unstable, and a sufficient contact avoidance effect may not be obtained.

[0004] The present invention has been made in view of the above circumstances, and prevents the vehicle behavior from becoming unstable due to wheel slip when automatic braking is performed to avoid contact with a forward obstacle. The purpose is to:

[0005]

According to the first aspect of the present invention, there is provided an object detecting means for detecting an object in a traveling direction of an own vehicle, and an object detecting means for detecting an object in the own vehicle. Contact possibility estimating means for estimating the possibility of contact with an object detected by the control means, and braking control means for executing automatic braking when the possibility of contact is estimated by the contact possibility estimating means. The vehicle driving safety device includes a slip detecting unit that detects a slip of a wheel, and a braking control unit controls the left and right wheels including the slipped wheel when the slip detecting unit detects a slip of the wheel during automatic braking. A driving safety device for a vehicle is proposed, which includes left and right braking force equalizing means for controlling power to be equal.

According to the above configuration, when the slip detecting means detects a slip of the wheel, the left and right braking force equalizing means of the braking control means controls the braking force of the left and right wheels including the slipped wheel so as to be equal. In addition, it is possible to prevent the left or right wheel from slipping during automatic braking, thereby making the vehicle behavior wheel unstable.

According to the second aspect of the present invention,
In addition to the configuration of claim 1, the braking control means includes left and right braking force independent control means for independently controlling the braking force of the left and right wheels, and switches between the left and right braking force equalizing means and the left and right braking force independent control means. A driving safety device for a vehicle, characterized in that the driving safety device is actuated.

According to the above construction, the braking control means includes the left and right braking force equalizing means and the left and right braking force independent control means,
The left and right braking force equalizing means controls the left and right wheels including the slipped wheel to equalize the braking force, and the left and right braking force independent control means of the braking control means independently controls the left and right wheel braking forces. Thus, both the stabilization of the vehicle behavior and the shortening of the braking distance can be achieved.

According to the third aspect of the present invention,
In addition to the constitution of claim 1 or 2, the brake control means activates the left and right braking force equalizing means for a predetermined period from the time when the slip detecting means detects the slip of the wheel during the automatic braking. A driving safety device for a vehicle is proposed.

According to the above construction, since the left and right braking force equalizing means operates for a predetermined period from the time when the slip of the wheel is detected, the difference between the braking force of the left and right wheels caused by the slip is required and sufficiently reduced to reduce the vehicle. Behavior can be stabilized.

According to the invention described in claim 4,
In addition to the configuration of claim 1 or 2, further comprising driver operation detecting means for detecting a driver's braking operation or steering operation, wherein the braking control means equalizes the left and right braking force based on the detection result of the driver operation detecting means. A driving safety device for a vehicle, characterized by switching and independently operating the left and right braking force independent control means, is proposed.

According to the above configuration, when the driver's braking operation or steering operation is detected, the operation of the left and right braking force equalizing means and the operation of the left and right braking force independent control means are switched, so that the driver's braking operation or steering operation is performed. It is possible to achieve both the effect of stabilizing the vehicle behavior by the left and right braking force equalizing means and the effect of shortening the braking distance by the left and right braking force independent control means while ensuring the operation effect.

According to the invention described in claim 5,
In addition to the configuration of claim 4, the braking control means activates the left and right braking force independent control means when the driver operation detecting means detects a braking operation or a steering operation of the driver. Is proposed.

According to the above configuration, when the braking operation or the steering operation of the driver is detected, the left and right braking force independent control means operates, so that the interference of the automatic braking with the braking operation or the steering operation of the driver is minimized. While suppressing, it is possible to shorten the braking distance and avoid contact with an object.

According to the invention described in claim 6,
In addition to the configuration according to any one of claims 1 to 5, the slip detecting means detects a slip based on the rotation speed of the wheel, and the left and right braking force equalizing means detects the slip of the left or right wheel. A driving safety device for a vehicle, characterized in that the braking force is controlled based on the rotation speed of the vehicle.

According to the above configuration, the braking force is controlled based on the lower rotation speed of the left and right wheels. Therefore, when one of the left and right wheels slips due to automatic braking and the rotation speed decreases, the left and right wheels are immediately turned off. The vehicle behavior can be stabilized by controlling the braking force of the wheels, and the braking distance can be shortened by generating the maximum braking force in a range where the slip can be suppressed.

According to the invention described in claim 7,
In addition to the configuration of any one of claims 1 to 5, the left and right braking force equalizing means determines a target braking force based on the slip state of each wheel, and among these target braking forces, A driving safety device for a vehicle is proposed in which the braking force is controlled based on a target braking force of a lower wheel.

According to the above configuration, the target braking force is determined based on the slip state of each wheel, and the braking force is controlled based on the lower target braking force of the left and right wheels among the target braking forces. When one of the left and right wheels slips due to automatic braking and the rotation speed drops, the braking force of the left and right wheels can be controlled immediately to stabilize the vehicle behavior and maximize the range in which slip can be suppressed. A braking force can be generated to shorten a braking distance.

According to the invention described in claim 8,
In addition to the configuration according to any one of claims 1 to 7, the brake control means activates the left and right braking force equalizing means for a predetermined period from the start of automatic braking by the brake control means. A driving safety device is proposed.

According to the above configuration, since the left and right braking force equalizing means operates only for a predetermined period from the start of automatic braking by the braking control means, disturbance of the vehicle behavior can be effectively stabilized immediately after the occurrence of a slip. After the vehicle behavior is stabilized, the maximum braking force can be generated while suppressing wheel slip.

The radar device Sa of the embodiment corresponds to the object detecting means of the present invention, and the brake operation sensor S of the embodiment
c and the steering operation sensor Sd correspond to the driver operation detecting means of the present invention.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described based on embodiments of the present invention shown in the accompanying drawings.

FIGS. 1 to 7 show a first embodiment of the present invention. FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving safety device, FIG. 2 is a block diagram of a braking system, and FIG. FIG. 4 is a flowchart of an automatic braking execution determination routine, FIG. 5 is a flowchart of a target brake pressure determination routine, FIG. 6 is a map for searching for the possibility of contact from the relative speed and relative distance, FIG.
Is a time chart showing changes in reference brake pressure.

As shown in FIGS. 1 and 2, a four-wheeled vehicle equipped with the driving safety device of the present invention has left and right front wheels WFL, which are driving wheels to which the driving force of an engine E is transmitted via a transmission T. The vehicle includes a WFR and left and right rear wheels WRL and WRR, which are driven wheels that rotate as the vehicle travels. A brake pedal 1 operated by a driver is connected to a master cylinder 3 via an electronic control negative pressure booster 2. The electronic control negative pressure booster 2 includes a brake pedal 1
The master cylinder 3 is actuated by mechanically boosting the pedaling force of the master cylinder 3, and the master cylinder 3 is actuated by a braking command signal from the electronic control unit U without operating the brake pedal 1 during automatic braking. When a depression force is input to the brake pedal 1 and a braking command signal is input from the electronic control unit U, the electronic control negative pressure booster 2 outputs the brake pressure having a predetermined value by taking the sum of the two.
The input rod of the electronic control negative pressure booster 2 is connected to the brake pedal 1 via a lost motion mechanism, and the electronic control negative pressure booster 2 is operated by a signal from the electronic control unit U to move the input rod forward. , The brake pedal 1 remains at the initial position.

A pair of output ports 7 of the master cylinder 3
Reference numeral 8 is connected via a hydraulic control device 4 to brake calipers 5FL, 5FR, 5RL, 5RR provided on the front wheels WFL, WFR and the rear wheels WRL, WRR, respectively. The hydraulic control device 4 includes four brake calipers 5FL and 5F.
R, 5RL, 5RR, four pressure regulators 6 are provided, and each pressure regulator 6 is connected to the electronic control unit U to be connected to the front wheels WFL, WFR and the rear wheels WR.
B, brake calipers 5FL, 5F provided on L, WRR
The operations of R, 5RL, and 5RR are individually controlled. Therefore,
Each of the brake calipers 5FL, 5
If the brake pressures transmitted to FR, 5RL, and 5RR are independently controlled, anti-lock brake control for suppressing wheel lock during braking can be performed.

The electronic control unit U transmits an electromagnetic wave such as a laser or a millimeter wave toward the front of the vehicle body, and, based on the reflected wave, a relative distance ΔL and a relative speed ΔV between an object such as a preceding vehicle and the host vehicle. Device Sa for detecting the front wheel and the front wheel WF
L, WFR and wheel speeds of the rear wheels WRL, WRR, that is, wheel speed sensors Sb for detecting the wheel speeds Vw of the respective wheels.
And a brake operation sensor Sc for detecting the operation of the brake pedal 1 by the driver, a steering operation sensor Sd for detecting the operation of the steering wheel 9 by the driver, and a yaw rate sensor Se for detecting the yaw rate Y of the vehicle. The brake operation sensor Sc and the steering operation sensor Sd constitute a driver operation detecting means of the present invention. Note that, instead of the radar device Sa, the relative distance Δ
Any means capable of detecting L and the relative speed ΔV can be employed.

The electronic control unit U controls the electronic control negative pressure booster 2 and the hydraulic control device 4 on the basis of the signal from the radar device Sa and the signals from the sensors Sb to Se constituting the object detecting means of the present invention. The operation is controlled, and the operation of the alarm device 10 including a buzzer, a speaker, a chime, a lamp, a head-up display, and the like is controlled.

As shown in FIG. 3, the electronic control unit U is provided with a contact possibility estimating means M1, a braking control means M2, and a slip detecting means M3. Equalizing means M4 and left and right braking force independent control means M5 are included.

The contact possibility estimating means M1 estimates the contact possibility between the own vehicle and the object based on the relative distance ΔL and the relative speed ΔV between the own vehicle and the object detected by the radar device Sa. When the contact possibility estimating means M1 estimates that there is a possibility that the vehicle and the object will come into contact with each other, the alarm device 10 prompts the driver to avoid voluntary contact by voice or image, and the braking control means M2 performs the electronic control negative operation. The pressure booster 2 is operated to generate a brake pressure in the master cylinder 3, and the brake pressure is applied to the brake caliper 5 F via the hydraulic control device 4.
L, 5FR, 5RL, and 5RR to perform automatic braking.

The slip detecting means M3 includes left and right front wheels WFL, WFR and left and right rear wheels WR generated during braking.
Slip (skid) of the road surface of L, WRR is detected. Specifically, the vehicle speed Vv is calculated from the average value of the wheel speeds Vw output from the four wheel speed sensors Sb.
The slip ratio of each wheel is calculated by (Vv-Vw) / Vv.

The left and right braking force equalizing means M4 provided in the braking control means M2 reduces the braking force of the left and right wheels when the slip is detected while maintaining the same magnitude, and the vehicle is caused by the slip of one of the right and left wheels. Prevent disturbance of behavior.
The left and right braking force independent control means M5 provided in the braking control means M2 independently controls the braking force of the left and right wheels when a slip is detected, and minimizes the damage of contact with each wheel. The braking distance is shortened by generating the maximum braking force while suppressing the lock.

Next, the operation of the first embodiment will be described with reference to FIGS.
This will be described with reference to the flowchart of FIG.

First, step S in the flowchart of FIG.
1 detects the relative distance ΔL and the relative speed ΔV of an object serving as an obstacle based on the output of the radar device Sa. In step S2, the front wheels WFL, WFR are detected by the wheel speed sensors Sb.
, The wheel speeds Vw of the rear wheels WRL, WRR, and the like, the brake operation sensor Sc detects the driver's brake operation, the steering operation sensor Sd detects the driver's steering operation, and the yaw rate sensor Se.
To detect the yaw rate Y of the vehicle. Subsequent step S
In 3, the possibility of the vehicle coming into contact with the object is estimated by the contact possibility estimation means M1 based on a search of the map shown in FIG. In this map, the horizontal axis represents the relative speed ΔV, and the vertical axis represents the relative distance ΔL. If the relative distance ΔL and the relative speed ΔV are in an area below the threshold line, it is estimated that there is a possibility of contact, and the threshold line It is estimated that there is no possibility of contact if it is in the upper area of. When estimating the possibility of contact, if the vehicle speed Vv or the positive acceleration of the own vehicle is large, it is difficult to avoid contact by braking or contact by steering operation. If the correction is made based on the magnitude of the vehicle speed Vv of the vehicle or the magnitude of the acceleration calculated by differentiating the vehicle speed Vv with time, more accurate estimation can be performed. Further, the amount of overlap between the vehicle and the object in the left-right direction detected by the radar device Sa, the yaw rate sensor Se
It is also possible to take into account the turning state of the own vehicle detected by the above.

If it is estimated in step S3 that there is no possibility of contact, the target brake pressure PB for automatic braking transmitted from the hydraulic control device 4 to the brake calipers 5FL, 5FR, 5RL, 5RR is set to 0 in step S4. . on the other hand,
If it is estimated in step S3 that there is a possibility of contact, the target brake pressure PB for automatic braking is set to the reference brake pressure P1 in step S5. As is clear from FIG. 7, the reference brake pressure P1 for automatic braking increases linearly from 0 simultaneously with the start of automatic braking, then linearly decreases to 0 after being kept at a constant value.

If the target brake pressure PB is a positive value in step S6 of the flow chart of FIG. 5, the process proceeds to step S7 to execute automatic braking, and if the target brake pressure PB is 0, the process proceeds to step S8 to perform automatic braking. To stop. When the target brake pressure PB is a positive value in step S6 and the automatic braking by the reference brake pressure P1 is executed, step S7
If the slip of the left and right front wheels WFL and WFR is not detected in step S9, the left and right front wheels WFL and WFR are automatically braked at step S9 at the reference brake pressure P1 in FIG. On the other hand, if the slip of any of the left and right front wheels WFL, WFR is detected in step S7, the left and right front wheels WFL, WFL, WFL, WFR are suppressed in step S10 in order to suppress the slip and prevent disturbance of the vehicle behavior.
The target brake pressure PB is reduced from the reference brake pressure P1 while keeping the WFR brake pressure equal.

In step S11, the left and right rear wheels WRL,
If no WRR slip is detected, step S
At 12, the left and right rear wheels WRL, WRR are automatically braked at the reference brake pressure P1 in FIG. On the other hand, when the slip of any of the left and right rear wheels WRL, WRR is detected in step S11,
In step S13, the target brake pressure PB is reduced from the reference brake pressure P1 while keeping the brake pressures of the left and right rear wheels WRL and WRR equal to suppress the slip and prevent disturbance of the vehicle behavior.

As described above, when one of the left and right wheels slips, the target brake pressure PB is reduced so that the braking forces of the left and right wheels become equal. The vehicle behavior can be stabilized by reducing the difference, and the amount of pressure reduction from the reference brake pressure P1 at that time is kept as small as possible, so that the total braking force is maximized and the braking distance is prevented from increasing. can do.

Next, a second embodiment of the present invention will be described with reference to the flowchart of FIG.

First, at step S21, the target brake pressure P
If B is 0, the automatic braking is stopped in step S22, and the automatic braking timer is cleared in step S23. In step S21, the target brake pressure PB is a positive value,
If slippage of the left and right front wheels WFL, WFR is not detected in step S24F, the left and right front wheels WFL, WFR are automatically braked in step S25F with the reference brake pressure P1 in FIG. On the other hand, in step S24F, slip of either the left or right front wheel WFL, WFR is detected, and step S24F is executed.
If the count value of the automatic braking timer has not reached the preset predetermined value Tf at 26F, the braking forces of the left and right front wheels WFL and WFR are made equal in step S27F to suppress the slip and prevent disturbance of the vehicle behavior. The target brake pressure PB is reduced from the reference brake pressure P1 while maintaining it. If the count value of the automatic braking timer reaches the predetermined value Tf in step S26F, the left and right front wheels W
FL and WFR are individually subjected to anti-lock brake control to generate a maximum braking force while suppressing slippage, thereby shortening a braking distance.

In step S24R, the left and right rear wheels WR
If the slip of L, WRR is not detected, the left and right rear wheels WRL, WRR are automatically braked at the reference brake pressure P1 in FIG. 7 in step S25R. On the other hand, step S24R
If the slip of either of the left and right rear wheels WRL, WRR is detected and if the count value of the automatic braking timer has not reached the predetermined value Tr set in step S26R, the slip is suppressed in step S27R and the vehicle behavior The target brake pressure PB is set to the reference brake pressure P while keeping the braking forces of the left and right rear wheels WRL, WRR equal, in order to prevent the
Reduce pressure from 1. If the count value of the automatic braking timer reaches the predetermined value Tr in step S26R, step S2
In 8r, the left and right rear wheels WRL, WRR are individually subjected to anti-lock brake control to generate a maximum braking force while suppressing a slip, thereby shortening a braking distance. Then, in the following step S29, the count value of the automatic braking timer is added.

As described above, the left and right braking force equalizing means M4 continues until the time of the automatic braking timer, which has started counting when any one of the wheels is detected as slipping, expires.
Operates to effectively stabilize the disturbance of the vehicle behavior caused by the slip. By the time the automatic braking timer times out, the vehicle behavior will be stable,
Thereafter, the left and right braking force independent braking means M5 operates to generate maximum braking force while suppressing wheel slip, thereby shortening the braking distance to avoid contact or reduce contact damage. .

Next, a third embodiment of the present invention will be described with reference to the flowchart of FIG.

In the above-described second embodiment (see FIG. 8), the operation of the left / right braking force equalizing means M4 and the left / right braking force independent control means M5 are performed based on the output of the automatic braking timer which counts the time from the start of the automatic braking. In the third embodiment, the left and right braking force equalizing means M4 is switched based on the output of the brake operation sensor Sc or the steering operation sensor Sd instead of the output of the automatic braking timer.
And the operation of the left and right braking force independent control means M5 are switched.

That is, if there is no brake operation or steering operation by the driver in steps S26F 'and S26R', the target brake pressure PB is reduced from the reference brake pressure P1 in steps S27F and S27R while keeping the left and right wheel brake pressures equal. If there is a driver's brake operation or steering operation, step S28
In F and S28R, the left and right wheels are individually subjected to antilock brake control.

As described above, when there is no brake operation or steering operation by the driver, the vehicle behavior caused by the slip is suppressed by setting the braking force of the left and right wheels to the same value by the left and right braking force equalizing means M4. When the driver's braking operation or steering operation is detected, the left and right braking forces are independently controlled by the left and right braking force independent control means M5, so that automatic braking can be performed. The braking distance can be shortened as much as possible while avoiding interference with the driver's contact avoidance operation.

Next, a fourth embodiment of the present invention will be described with reference to the flowchart of FIG.

First, at step S31, the left and right front wheels WFL,
The wheel slip ratio and the wheel acceleration are calculated based on the lower wheel speed Ww of WFR. The wheel acceleration can be calculated as a time differential value of the wheel speed Ww. If the target brake pressure PB is 0 in the subsequent step S32, the automatic braking is stopped in step S33, and a braking mode described later is set to "0". If the target brake pressure PB is a positive value in step S32, the previous braking mode is referred to in step S34. In this embodiment, four types of braking modes are set. The braking mode "0" is a non-slip prevention control mode in which no slip prevention control is performed, the braking mode "1" is a pressure increasing mode for increasing the brake pressure, and a braking mode. “2” is a holding mode for holding the brake pressure, and “3” is a pressure reduction mode for reducing the brake pressure.

If the previous braking mode is "0" (non-slip prevention control mode) in step S34, in step S35 the wheel slip ratio calculated in step S31 is compared with 5%. If the slip ratio of the wheels is 5% or less, that is, if the slip ratio is small, the target brake pressure PB of the left and right front wheels WFL, WFR is set to the reference brake pressure P1 in step S36, and the automatic braking is executed. , The braking mode is set to “0” (non-slip prevention control mode). On the other hand, the step S
If the wheel slip rate exceeds 5% at 35, that is, if the slip rate is large, at step S37, the target brake pressure PB of the left and right front wheels WFL, WFR is adjusted from the reference brake pressure P1 to suppress the slip. The pressure is reduced by a fixed amount, and the braking mode is set to “3” (pressure reduction mode).

When the braking mode is set to "3" (decompression mode), the answer to both steps S34 and S38 of the next loop is YES, so that the routine proceeds to step S39.
If the slip ratio is less than 1% or the wheel acceleration becomes a positive value in step S39, that is, if the slip is approaching convergence, the left and right front wheels WF in step S40.
The target brake pressure PB of L and WFR is held at the previous value, and the braking mode is set to “2” (holding mode). On the other hand, if the slip ratio is still 1% or more and the wheel acceleration is not a positive value in step S39, that is, if the slip is not converging, the reduction of the target brake pressure PB is continued in step S37.

In step S40, the braking mode is "2".
When (hold mode) is set, the answer to step S38 in the next loop is NO, and the answer to step S41 is Y
The process moves to step S42 to become ES. If the slip ratio again exceeds 5% in step S42 and the wheel acceleration becomes a negative value, that is, if slippage occurs again, the target brake pressure PB is reduced again in step S37 and the braking mode is set to "3". ”(Decompression mode).
On the other hand, if the slip ratio becomes 5% or less or the wheel acceleration becomes a non-negative value in step S42, the process proceeds to step S43. If the slip ratio still exceeds 1% in step S43, the brake mode is set to "2" (hold mode) by holding the target brake pressure PB in step S40, and the slip ratio decreases to 1% or less. If the slip has sufficiently converged, the target brake pressure PB is increased in step S44 to increase the braking force, and the braking mode is set to "1" (pressure increase mode). Set the pressure control duration timer.

In step S44, the braking mode is "1".
When the mode is set to (pressure increase mode), the answer to both the steps S38 and S41 of the next loop is NO, so that the process proceeds to the step S45. If the slip ratio again exceeds 5% in step S45, the process proceeds to step S37 to reduce the target brake pressure PB. If the slip ratio is 5% or less, the pressure increase control duration timer is set in step S46. After waiting for the time to elapse, the process proceeds to step S36, in which the target brake pressure PB is returned to the set brake pressure P1, and the braking mode is set to "0" (non-slip prevention control mode). The set time Tin of the pressure increase control duration timer is
When the target brake pressure PB is reduced from the reduced pressure, the set brake pressure P1
Is set as the time to almost return to.

The control of the target brake pressure PB for the left and right rear wheels WRL, WRR is performed in the same manner as the control of the target brake pressure PB for the left and right front wheels WFL, WFR described above in step S47.

The above-described reduction of the target brake pressure PB,
The holding and pressure increasing control is performed collectively for the left and right front wheels WFL, WFR, and the left and right rear wheels WRL, WR.
It is assumed that R is performed collectively.

As described above, the front wheels WFL, WFR are determined based on the lower one of the wheel speeds Vw of the left and right front wheels WFL, WFR.
It controls the target brake pressure PB of FR, and the right and left rear wheels W
Since the target brake pressure PB of the rear wheels WRL and WRR is controlled based on the lower one of the wheel speeds Vw of RL and WRR, the target brake pressure PB is reduced early even if one of the right and left wheels slips. In addition to stabilizing the behavior of the vehicle, the braking distance can be shortened by securing the maximum braking force in a range where the slip of each wheel can be suppressed.

Next, a fifth embodiment of the present invention will be described with reference to the flowcharts of FIGS.

First, in step S51, the left and right front wheels WFL,
The WFR and the slip ratios and wheel accelerations of the left and right rear wheels WRL, WRR are calculated. If the target brake pressures PB of all the wheels are 0 in subsequent step S52, step S5
In 3, stop the slip prevention control and set the braking mode to "0".
(Non-slip prevention control mode). If the target brake pressure PB of any one of the wheels is a positive value in step S52, the process proceeds to steps S34 to S46 'to calculate the target brake pressure PB of the right front wheel WFR. Steps S34 to S46 'of the fifth embodiment are almost the same as steps SS34 to S46 of the above-described fourth embodiment (see FIG. 10), except for step S46'. That is, in step S46 of the fourth embodiment, when the pressure-increasing control duration timer has timed out, the slip prevention control is stopped and the braking mode "0" (non-slip prevention control mode).
However, in step S46 'of the fifth embodiment, when the target brake pressure PB reaches the reference brake pressure P1 due to the pressure increase, the brake mode returns to "0" (non-slip prevention control mode). Only in that they differ.

In the same manner as in the case of the right front wheel WFR described above, the target brake pressure PB of the left front wheel WFL is set in step S54, the target brake pressure PB of the right rear wheel WRR is set in step S55, and the left rear wheel is set in step S56. The target brake pressure PB of WRL is calculated. And step S57
To collectively brake the left and right front wheels WFL, WFR with the smaller of the target brake pressures PB of the left and right front wheels WFL, WFR, and at step S58, the left and right rear wheels WR.
The left and right rear wheels WRL, WRR are collectively braked by the smaller of the target brake pressures PB of L, WRR.

As described above, the target brake pressure PB of each wheel
Are respectively calculated, and the left and right front wheels WFL, WFR are collectively braked based on the smaller target brake pressure PB of the left and right front wheels WFL, WFR.
Since the left and right rear wheels WRL, WRR are collectively braked based on the smaller of the target brake pressure PB of L and WRR, the target brake pressure PB is reduced as soon as possible even when one of the left and right wheels slips. As a result, not only can the vehicle behavior be stabilized, but also the braking distance can be shortened by securing the maximum braking force in a range where the slip of each wheel can be suppressed.

Although the embodiments of the present invention have been described above, various design changes can be made in the present invention without departing from the gist thereof.

For example, the second embodiment shown in FIG.
In the third embodiment shown in FIG. 5, the left and right braking force equalization control and the left and right braking force independent control are switched for both the front wheels WFL and WFR and the rear wheels WRL and WRR.
L and WRR may always perform only the left and right braking force equalization control.

The hydraulic control device 4 of the embodiment can individually control the left and right braking forces. In the left and right braking force equalization control, one actuator controls the left and right braking forces collectively, and the left and right braking forces are controlled. In the power independent control, the left and right braking forces may be individually controlled by different actuators.

[0062]

As described above, according to the first aspect of the present invention, when the slip detecting means detects the slip of the wheel, the left and right braking force equalizing means of the braking control means sets the left and right braking force including the slipped wheel. Since the control is performed so that the braking forces of the wheels are equal, it is possible to prevent the left or right wheel from slipping during automatic braking and the vehicle behavior wheels from becoming unstable.

According to the second aspect of the present invention,
The braking control means includes left and right braking force equalizing means and left and right braking force independent control means, and the left and right braking force equalizing means controls the left and right wheels including the slipped wheel to have the same braking force. Since the left and right braking force independent control means independently controls the braking forces of the left and right wheels, it is possible to achieve both a stable vehicle behavior and a short braking distance.

According to the third aspect of the present invention,
Since the left and right braking force equalizing means operates for a predetermined period from the time when the slip of the wheel is detected, the difference in braking force between the left and right wheels caused by the slip can be reduced sufficiently and stably to stabilize the vehicle behavior.

According to the fourth aspect of the present invention,
When the driver's braking or steering operation is detected,
Since the operation of the left and right braking force equalizing means and the operation of the left and right braking force independent control means are switched, the vehicle behavior stabilizing effect by the left and right braking force equalizing means while securing the effect of the driver's braking operation or steering operation is improved. It is possible to achieve both the effect of shortening the braking distance by the braking force independent control means.

According to the invention described in claim 5,
When the driver's braking operation or steering operation is detected, the left and right braking force independent control means operates, so that the braking distance can be shortened while minimizing the interference of automatic braking with the driver's braking operation or steering operation. Contact with an object can be avoided.

According to the invention described in claim 6,
Since the braking force is controlled based on the lower rotation speed of the left and right wheels, when one of the left and right wheels slips due to automatic braking and the rotation speed decreases, the vehicle immediately controls the braking force of the left and right wheels. The behavior can be stabilized, and the maximum braking force can be generated within a range in which the slip can be suppressed, so that the braking distance can be reduced.

According to the invention described in claim 7,
Determine the target braking force based on the slip state of each wheel,
Of these target braking forces, the braking force is controlled based on the lower target braking force of the left and right wheels, so when one of the left and right wheels slips due to automatic braking and the rotation speed decreases, the left and right wheels are immediately By controlling the braking force, the vehicle behavior can be stabilized, and the braking distance can be shortened by generating the maximum braking force in a range where the slip can be suppressed.

According to the invention described in claim 8,
Since the left and right braking force equalizing means operates only for a predetermined period from the start of automatic braking by the braking control means, the disturbance of the vehicle behavior can be effectively stabilized immediately after the occurrence of the slip, and after the vehicle behavior is stabilized. A maximum braking force can be generated while suppressing wheel slip.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle equipped with a driving safety device.

FIG. 2 is a block diagram of a braking system.

FIG. 3 is a block diagram showing a circuit configuration of an electronic control unit.

FIG. 4 is a flowchart of an automatic braking execution determination routine;

FIG. 5 is a flowchart of a target brake pressure determination routine.

FIG. 6 is a map for searching for the possibility of contact based on relative speed and relative distance.

FIG. 7 is a time chart showing a change in reference brake pressure.

FIG. 8 is a flowchart of a target brake pressure determination routine according to a second embodiment.

FIG. 9 is a flowchart of a target brake pressure determination routine according to a third embodiment.

FIG. 10 is a flowchart of a target brake pressure determination routine according to a fourth embodiment.

FIG. 11 is a first partial diagram of a flowchart of a target brake pressure determination routine according to a fifth embodiment.

FIG. 12 is a second diagram of the flowchart of the target brake pressure determination routine according to the fifth embodiment.

[Explanation of symbols]

M1 Contact possibility estimating means M2 Brake control device M3 Slip detecting means M4 Left and right braking force equalizing means M5 Left and right braking force independent control means WFL Left front wheel (wheel) WFR Right front wheel (wheel) WRL Left rear wheel (wheel) WRR Left rear Wheel (wheel) Sa Radar device (object detection means) Sc Brake operation sensor (driver operation detection means) Sd Steering operation sensor (driver operation detection means)

 ──────────────────────────────────────────────────の Continuing from the front page (72) Inventor Kenji Odaka 1-4-1 Chuo, Wako-shi, Saitama F-term in Honda R & D Co., Ltd. (Reference) 3D046 BB18 BB28 EE01 FF09 HH02 HH08 HH20 HH23 HH36 JJ06 JJ08 KK02 KK11 5H180 AA01 CC14 LL01 LL07 LL09

Claims (8)

[Claims] 1. An object detecting means (Sa) for detecting an object in a traveling direction of the own vehicle, and a contact possibility estimating means for estimating a possibility that the own vehicle comes into contact with an object detected by the object detecting means (Sa). (M1)
And a braking control means (M2) for executing automatic braking when the possibility of contact is estimated by the contact possibility estimating means (M1). WFR, WRL, WRR) is provided with a slip detecting means (M3) for detecting a slip. The braking control means (M2) is configured such that the slip detecting means (M3) controls the wheels (WFL, WFR, WRL, WRR) during automatic braking.
When the slip of the wheel (WF) is detected,
L, WFR, WRL, WRR)
A driving safety device for a vehicle, comprising left and right braking force equalizing means (M4) for controlling the braking forces of L, WFR, WRL, WRR) to be equal. 2. The braking control means (M2) includes a left and right braking force independent control means (M5) for independently controlling the braking force of the left and right wheels (WFL, WFR, WRL, WRR). The driving safety device for a vehicle according to claim 1, wherein the switching means (M4) and the left and right braking force independent control means (M5) are switched to operate. 3. A slip detecting means (M3) during automatic braking.
The braking control means (M2) activates the left and right braking force equalizing means (M4) for a predetermined period from when the vehicle detects a slip of the wheels (WFL, WFR, WRL, WRR). The vehicle safety device according to claim 2. 4. A driver operation detecting means (Sc, Sd) for detecting a driver's braking operation or steering operation, and a braking control means (M2) performs left and right operations based on the detection result of the driver operation detecting means (Sc, Sd). The vehicle safety device according to claim 1 or 2, wherein the braking force equalizing means (M4) and the left and right braking force independent control means (M5) are switched to operate. 5. The braking control means (M2) activates the left and right braking force independent control means (M5) when the driver operation detecting means (Sc, Sd) detects the driver's braking operation or steering operation. The travel safety device for a vehicle according to claim 4, wherein 6. A slip detecting means (M3) is provided for a wheel (WF).
L, WFR, WRL, WRR) to detect slip based on the rotation speed of the left and right wheels (WFL, WFR, WRL, WR).
The driving safety device for a vehicle according to any one of claims 1 to 5, wherein the braking force is controlled based on a lower rotation speed of R). 7. A left / right braking force equalizing means (M4) determines a target braking force based on a slip state of each wheel (WFL, WFR, WRL, WRR), and, among these target braking forces, a left and right wheel. The driving safety device for a vehicle according to any one of claims 1 to 5, wherein the braking force is controlled based on a lower target braking force of (WFL, WFR, WRL, WRR). . 8. The braking control means (M2) activates the left and right braking force equalizing means (M4) for a predetermined period from the start of automatic braking by the braking control means (M2). Item 8. The traveling safety device for a vehicle according to any one of items 7.