JP2003054394A - Brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a brake control device for a vehicle capable of inhibiting the change of deceleration generated in a self-vehicle, and surely preventing the collision without giving the feeling of incompatible to an occupant. SOLUTION: A brake staring timing TTCCOM is determined on the basis of the road surface μ, a self-vehicle speed Vc, a forward object speed Vp, an arrival time TTC is calculated by dividing a distance DIST from the self-vehicle to the forward object, by a relative speed Vr, and the braking is started with, a target braking fluid pressure α when the arrival time TTC becomes less than the brake starting timing TTCCOM. The smaller the road surface μ is, the higher the self-vehicle speed is, and the higher the forward object speed Vp is, the longer the brake starting timing TTCCOM is determined, to start the braking from a point of time separated more, whereby the change of deceleration to these factors can be reduced. The target braking fluid pressure for achieving the target braking force is determined on the basis of the road surface μ, the arrival time and the average speeds of the self-vehicle and the forward object.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a braking control device for a vehicle, which detects an object in front of the host vehicle and applies automatic braking so as to avoid a collision with the preceding object.

[0002]

2. Description of the Related Art As an example of such a vehicle braking control device, there is one described in 174 (p13) of Preprints No. 114-00, Preprints of Academic Lectures of the Automotive Engineering Society 2000 Autumn Meeting. In this vehicle braking control device, the distance between an object in front of the own vehicle and the own vehicle is detected, the distance is divided by the own vehicle speed to calculate the collision time, and the collision time is equal to or less than a predetermined value set in advance. When so, the time until the automatic braking is started, that is, the so-called braking start timing is set. According to this vehicle braking control device, the higher the speed of the host vehicle, the more the automatic braking is started at a position distant from the front object.

[0003]

However, in the above-described conventional vehicle braking control device, the braking start timing is set when the collision time becomes equal to or less than a certain predetermined value. As the speed of the host vehicle increases, the deceleration that occurs or occurs increases at an accelerated rate, which may give an occupant a strange feeling.

When the target braking deceleration to be achieved by the host vehicle is calculated and the braking fluid pressure is controlled so that the target braking deceleration is achieved, the braking fluid pressure is generally calculated from the target braking deceleration. Since the time constant of the lag system filter at the time of performing is fixed, for example, when the time constant of the filter is set large in order to request smoothness for braking, the deceleration actually achieved or generated by the host vehicle is When the time constant of the filter is set small to demand speed for braking, the deceleration actually achieved or generated by the host vehicle becomes maximum immediately after the start of braking. After that, there is also a problem that the deceleration generated by one braking suddenly changes with the passage of time, such that the deceleration decreases with the passage of time.

In order to solve the above-mentioned problems, the present invention suppresses a change in the deceleration achieved or generated in the own vehicle with respect to the running speed of the own vehicle or a rapid change with the passage of time, thereby making the occupant feel uncomfortable. It is an object of the present invention to provide a braking control device for a vehicle that does not have a vehicle.

[0006]

In order to achieve the above object, a braking control device for a vehicle according to a first aspect of the present invention is a front detecting a distance between an object existing in front of the own vehicle and the own vehicle. An object distance detecting means, a relative speed detecting means for detecting a relative speed of an object existing in front of the own vehicle with respect to the own vehicle, and a own vehicle speed detecting means for detecting a speed of the own vehicle,
A forward object velocity detecting means for detecting the velocity of an object existing in front of the own vehicle, a road surface friction coefficient state detecting means for detecting a friction coefficient state of a road surface, and a front object velocity detected by the front object distance detecting means. Arrival time calculating means for calculating the time until the own vehicle arrives at the front object by dividing the distance between the object and the own vehicle by the relative speed detected by the relative speed detecting means, and the own vehicle speed detecting means. Braking based on at least one of the speed of the own vehicle detected by the vehicle speed, the speed of the front object detected by the front object speed detection means, and the road surface friction coefficient state detected by the road surface friction coefficient state detection means. Braking start timing setting means for setting the time to start, the speed of the own vehicle detected by the own vehicle speed detecting means and the speed of the front object detected by the front object speed detecting means Target braking force calculation means for calculating the target braking force of the host vehicle based on a value obtained by dividing the average value of the times by the arrival time calculated by the arrival time calculation means, and the arrival time calculated by the arrival time calculation means Automatic braking means for generating the target braking force calculated by the target braking force calculation means when the time until the start of braking set by the braking start timing setting means becomes less than or equal to Is.

According to a second aspect of the present invention, there is provided the vehicle braking control device according to the first aspect, wherein the braking start timing setting means is the road surface friction detected by the road surface friction coefficient state detecting means. The smaller the coefficient state is, the shorter the time between braking starts is set. Further, in the vehicle braking control device according to claim 3 of the present invention, in the invention of claim 1 or 2, the braking start timing setting means is the vehicle speed detected by the vehicle speed detecting means. The larger the value, the shorter the time until the start of braking is set.

According to a fourth aspect of the present invention, there is provided a vehicle braking control device according to the first to third aspects of the invention.
The braking start timing setting means sets a shorter time until the start of braking as the front object speed detected by the front object speed detecting means increases. Further, in the vehicle braking control device according to a fifth aspect of the present invention, in the inventions according to the first to fourth aspects, the braking start timing setting means is the speed of the own vehicle detected by the own vehicle speed detecting means. The larger the average value of the speed of the front object detected by the front object speed detection means is, the shorter the time until the start of braking is set.

According to a sixth aspect of the present invention, there is provided the vehicle braking control device according to the fifth aspect, wherein the braking start timing setting means controls the own vehicle speed detected by the own vehicle speed detecting means. In a region where the average value of the speed and the speed of the front object detected by the front object speed detection means is small, the decrease rate of the time until the start of braking with respect to the decrease of the average value is set to be small. is there.

According to a seventh aspect of the present invention, there is provided the vehicle braking control device according to the fifth or sixth aspect of the invention.
The braking start timing setting means, in a region where the average value of the speed of the own vehicle detected by the own vehicle speed detecting means and the speed of the front object detected by the front object speed detecting means is large, It is characterized in that the rate of increase in the time until the start of braking with respect to the increase is set small.

Further, the vehicle braking control device according to claim 8 of the present invention exists in front of the host vehicle, and forward object distance detecting means for detecting a distance between an object existing in front of the host vehicle and the host vehicle. Relative speed detection means for detecting the relative speed of the object with respect to the own vehicle, and relative distance detected by the relative speed detection means for the distance between the object and the object existing in front of the own vehicle detected by the front object distance detection means. Arrival time calculation means for calculating the time until the own vehicle arrives at the front object divided by the speed, and the distance between the object and the own vehicle existing at the front of the own vehicle detected by at least the front object distance detection means, and Target braking deceleration calculating means for calculating the target braking deceleration of the host vehicle based on the relative speed detected by the relative speed detecting means, and the arrival time calculated by the arrival time calculating means until the start of braking. Automatic braking means for controlling the braking fluid pressure so as to generate the target braking deceleration calculated by the target braking deceleration calculating means when the target braking deceleration calculating means calculates the target braking deceleration. The method of increasing the braking fluid pressure is adjusted according to the target braking deceleration calculated by the deceleration calculating means.

According to a ninth aspect of the present invention, in the vehicle braking control device according to the eighth aspect, the automatic braking means is the target braking deceleration calculated by the target braking deceleration calculating means. The method of adjusting the braking fluid pressure is adjusted according to the above. According to a tenth aspect of the present invention, in the vehicle braking control device according to the ninth aspect, the automatic braking means achieves the target braking deceleration calculated by the target braking deceleration calculating means. In controlling the braking fluid pressure as described above, the method of reducing the braking fluid pressure is adjusted so as to be gentler than the method of increasing the pressure.

[0013]

As described above, according to the vehicle braking control device of the present invention, the distance between the object existing in front of the own vehicle and the own vehicle is divided by the relative speed of the own vehicle to obtain the own vehicle. Calculates the time it takes for the vehicle to reach the front object, and starts braking based on at least one of the detected vehicle speed, the detected front object speed, and the detected road friction coefficient state. The target braking force of the own vehicle is calculated based on the value obtained by dividing the average value of the speed of the own vehicle and the speed of the front object by the arrival time, and the arrival time is the time until the start of braking. Since the target braking force is generated when the following occurs, the time until the start of braking can be appropriately set according to the mutual running state of the own vehicle and the front object or the road surface friction coefficient state. As a result To suppress a change in deceleration raw, it does not give a sense of discomfort to the occupant.

According to the second aspect of the present invention, the braking control device for a vehicle is configured such that the time until the start of braking is set shorter as the detected road surface friction coefficient state is smaller. The automatic braking can be started at an appropriate timing according to Further, according to the vehicle braking control device of the third aspect of the present invention, the time until the start of braking is set to be shorter as the detected vehicle speed is higher. Automatic braking can be started at the timing.

Further, according to the vehicle braking control device of the fourth aspect of the present invention, since the time until the start of braking is set shorter as the detected front object velocity is larger, the vehicle braking control device according to the front object velocity is changed. Automatic braking can be started at an appropriate timing. Further, according to the vehicle braking control device of the fifth aspect of the present invention, the larger the average value of the detected vehicle speed and the detected speed of the front object is, the shorter the time until the start of braking is set. Therefore, the effect of automatic braking can be reliably exhibited.

Further, according to the vehicle braking control device of the present invention, in the region where the average value of the detected speed of the own vehicle and the speed of the front object is small, the decrease in the average value is suppressed. Since the reduction rate of the time until the start of braking is set to be small, it is possible to compensate for the response delay of the device and further to make the start timing of automatic braking appropriate.

According to the vehicle braking control device of the seventh aspect of the present invention, in the region where the detected average speed of the own vehicle and the speed of the front object is large, the increase in the average value is suppressed. Since the rate of increase in the time until the start of braking is set to a small value, the start timing of automatic braking can be made appropriate without unnecessarily advancing the timing.

Further, according to the braking control device for a vehicle of the eighth aspect of the present invention, since the way of increasing the braking fluid pressure is adjusted according to the target braking deceleration, the target braking deceleration is reduced. When the target braking deceleration is large, the braking fluid pressure is gradually increased to make the braking smooth, and when the target braking deceleration is large, the braking fluid pressure is quickly increased to enhance the response, and thus the deceleration is rapidly increased with time. Changes can be suppressed and prevented.

Further, according to the vehicle braking control apparatus of the present invention, the target braking deceleration is small because the braking fluid pressure is reduced according to the target braking deceleration. Sometimes, the pressure reduction of the braking fluid pressure after pressure increase is made gentle to make the braking smooth, and when the target braking deceleration is large, the pressure reduction of the braking fluid pressure after pressure increase is speeded up to improve the response. It is possible to suppress and prevent a rapid change in deceleration.

Further, according to the vehicle braking control apparatus of the tenth aspect of the present invention, the braking fluid pressure is adjusted so that the way of depressurizing the fluid is slower than the way of increasing the pressure. Quickly increases the braking fluid pressure to obtain the required deceleration, and then gradually reduces the braking fluid pressure to achieve smooth braking, which causes a rapid change in deceleration over time. Further suppression can be prevented.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram showing a first embodiment of a vehicle with a preceding vehicle following traveling device to which a vehicle braking control device of the present invention is applied. The outside world recognition device 1 is connected to a radar processing device 3 that extracts an object in front of the vehicle from the result of scanning by the scanning laser radar 2. The radar processing device 3 is added with a function of calculating a two-dimensional coordinate value with respect to the detected one or more frontal objects with the own vehicle as the origin, that is, the position of the frontal object.

Further, an image processing device 5 for detecting the traveling lane of the own vehicle from the image in front of the own vehicle captured by the CCD camera 4 is connected to the outside world recognition device 1. The CCD camera 4 is of a progressive scan type capable of grasping the situation in front of the vehicle at a wide angle and at high speed.
Further, the image processing device 5 is additionally provided with a function of determining whether the position of the front object detected by the radar processing device 3 is inside or outside the traveling lane of the own vehicle, and on which side. ing.

Further, a vehicle speed sensor 6 and a steering angle sensor 7 for detecting the traveling state of the own vehicle are connected to the external environment recognition device 1. The vehicle speed sensor 6 detects the traveling speed V _SP of the host vehicle from the rotational speed of the rear wheels that are driven wheels. The steering angle sensor 7 detects the steering angle θ of the steering wheel. Also,
The vehicle is provided with a road-vehicle communication device 10 that communicates information with a road environment, so-called infrastructure. The road-to-vehicle communication device 10 can acquire various kinds of traffic information, but it is used here to detect the friction coefficient state of the traveling road surface. This road surface friction coefficient state is output to the external environment recognition device 1.

Then, the external environment recognizing device 1 judges whether or not the front object is an obstacle with which the own vehicle may collide, and when it is judged that the obstacle is an obstacle, it is automatically judged. A command is output to the brake control device 8. The automatic brake control device 8 performs the arithmetic processing described later,
The negative pressure brake booster 9 is operated to apply a braking force to each wheel to avoid collision with a front object. Further, when the outside world recognition device 1 determines that the preceding object is not an obstacle but a preceding vehicle traveling at the same speed as the own vehicle, a determination result is given to a preceding vehicle following traveling control device (not shown). The preceding vehicle follow-up running control device outputs the output and controls the output of the engine and the braking force to each wheel to follow the preceding vehicle.

The outside world recognition device 1, the radar processing device 3,
The image processing device 5, the automatic brake control device 8, the road-vehicle communication device 10, and the like each include a microcomputer and its peripheral devices, a drive circuit for driving each actuator, and the like, and communicate with each other via a communication circuit. You can send and receive. Next, regarding the arithmetic processing for automatic braking performed by the automatic brake control device 8,
This will be described with reference to the flowchart of FIG. This calculation process is performed with a predetermined sampling period ΔT (for example, 10 msec.).
Each time a timer interrupt process is performed. It should be noted that, although this flowchart does not include a step for communication in particular, for example, the information obtained in the flowchart is stored in the storage device at any time, and necessary information is read from the storage device at any time.

In step S1 of this calculation processing, the vehicle speed Vc detected by the vehicle speed sensor 6, the distance DIST to the front object detected by the laser radar 2 and the radar processing device 3, and the road-vehicle communication device 10 Read the obtained road friction coefficient value μ. Next, in step S2,
From the change rate of the distance D to the front object read in step S1, the relative speed Vr between the front object and the host vehicle is calculated,
Furthermore, the relative speed Vr is added to the own vehicle speed Vc read in step S1 to calculate the front object speed Vp.

Next, in step S3, the time until the host vehicle reaches the front object by dividing the distance DIST between the front object and the host vehicle read in step S1 by the relative speed Vr, that is, The arrival time TTC is calculated. Next, the process proceeds to step S4a, and according to the control map of FIG. 3, the time until the start of braking according to the host vehicle speed Vc read in step S1, that is, the braking start timing TTC _COM is calculated. In this control map, the braking start timing TTC _COM is directly proportional to the own vehicle speed Vc, and the braking start timing TTC _COM is set longer as the own vehicle speed Vc increases.

Next, the process proceeds to step S5, and the arrival time TTC calculated in step S3 is calculated in step S4a.
It is determined whether or not the braking start timing TTC _COM calculated in step S6 is less than or equal to the braking start timing. If the arrival time TTC is less than or equal to the braking start timing TTC _COM , the process proceeds to step S6, and if not, the main program is restored. .
In step S6, the target braking fluid pressure α is calculated according to the following equation 1, and the negative pressure booster is driven so that the target braking fluid pressure α is achieved, and the braking force is applied to each wheel.

Α = K · μ · ((Vc + Vp) / 2) / TTC = K · μ · ((Vc + Vp) / 2) · Vr / DIST (1) where K is the road friction coefficient μ It is a gain that is set according to the accuracy. That is, since the road surface friction coefficient μ obtained from the infrastructure through road-to-vehicle communication is relatively accurate as in the present embodiment, the target braking fluid pressure α is relative to the road surface friction coefficient μ even if the gain K is relatively small. Will be appropriate. On the other hand, as will be described later, when the road surface friction coefficient μ is estimated from the operation of the wiper, the outside air temperature, etc., the accuracy of comparison is low.
To be large so that sufficient braking force can be obtained.

In this embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and braking is performed according to the host vehicle speed Vc. The start timing TTC _COM is set, and the arrival time TTC is equal to the braking start timing TTC.
When the pressure _falls below _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM is directly proportional to the own vehicle speed Vc, and is set longer as the own vehicle speed Vc is larger and shorter as the own vehicle speed Vc is smaller.
That is, the faster the vehicle approaches the object ahead,
Since the braking start timing TTC _COM is set long,
Braking will be started at a position separated from the front object by that amount.

Therefore, braking is started with respect to the vehicle speed Vc.
Timing TTC_COMThe slope and intercept of
Thus, as shown in FIG. 4a, the braking start timing TT
C_{CO M}Can be set equal to the arrival time TTC,
By doing so, the braking start timing is appropriate
Can occur in the vehicle as shown in Figure 4b
It is possible to suppress changes in deceleration with respect to the vehicle speed.
Therefore, the occupant does not feel uncomfortable. Against this
Then, the braking start timing is broken as shown in FIG.
If you set it to a constant value as shown by the line, the arrival time
After the braking start timing of the constant value is dropped,
The deceleration achieved or generated in the vehicle is
The bigger it is, the bigger the acceleration becomes, which is uncomfortable for passengers.
It becomes a feeling.

By setting the target braking force, that is, the target braking fluid pressure α according to the road friction coefficient μ, the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, and the arrival time TTC, When the host vehicle reaches the position of the front object, the host vehicle speed Vc can be stopped at "0", and the effect of automatic braking can be sufficiently exerted.

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the arithmetic processing of FIG. 2 constitute the forward object distance detecting means of the present invention, and the same applies to the case of FIG.
The step S2 of the arithmetic processing of FIG. 2 constitutes the relative speed detecting means, and the vehicle speed sensor 6 and the step S of the arithmetic processing of FIG.
1 constitutes the own vehicle speed detecting means, step S2 of the arithmetic processing of FIG. 2 constitutes the forward object speed detecting means, and the road-vehicle communication device 10 and step S1 of the arithmetic processing of FIG.
Constitutes a road surface friction coefficient state detecting means, step S3 of the arithmetic processing of FIG. 2 constitutes arrival time calculating means, and step S4a of the arithmetic processing of FIG. 2 constitutes braking start timing setting means. Step S6 of the calculation process of 2
Constitutes the target braking force calculating means, and steps S5 and S6 of the arithmetic processing of FIG. 2 constitute the automatic braking means.

Next, the second braking control device for a vehicle according to the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. The arithmetic processing of FIG. 5 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this arithmetic processing, step S4a of the arithmetic processing of FIG. 2 of the first embodiment is changed to step S4b.

In step S4b, according to the control map of FIG. 6, the time until the start of braking according to the road surface friction coefficient value μ read in step S1, that is, the braking start timing TTC _COM is calculated, and then step S5 is executed. Move to. In this control map, the braking start timing TTC _COM is inversely proportional to the road friction coefficient value μ, and the braking start timing TTC _COM is set shorter as the road friction coefficient value μ increases.

In this embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the braking is performed according to the road surface friction coefficient μ. The start timing TTC _COM is set, and the arrival time TTC is equal to the braking start timing TTC.
When the pressure _falls below _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM is inversely proportional to the road surface friction coefficient μ, and is set shorter as the road surface friction coefficient μ is larger and longer as the road surface friction coefficient μ is smaller.
That is, the braking start timing TTC _COM is set to be longer on a road surface that is slippery and a larger braking force cannot be applied, so that braking is started at a position further away from the front object.

Therefore, by appropriately setting the coefficient and the asymptotic value of the braking start timing TTC _{COM with} respect to the road surface friction coefficient μ, the braking start timing TTC _COM can be set to be equal to the arrival time TTC. As a result, the braking start timing can be made appropriate, and the change in deceleration that occurs in the vehicle with respect to the road surface friction coefficient can be suppressed, so that the occupant will not feel discomfort.

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the arithmetic processing of FIG. 5 constitute the forward object distance detecting means of the present invention.
The step S2 of the calculation process of 5 constitutes the relative speed detecting means, and the vehicle speed sensor 6 and the step S of the calculation process of FIG.
1 constitutes the own vehicle speed detecting means, step S2 of the arithmetic processing of FIG. 5 constitutes the forward object speed detecting means, and the road-vehicle communication device 10 and step S1 of the arithmetic processing of FIG.
Represents the road surface friction coefficient state detecting means, step S3 of the arithmetic processing of FIG. 5 constitutes arrival time calculating means, and step S4b of the arithmetic processing of FIG. 5 constitutes braking start timing setting means. Step S6 of the calculation process of 5
Constitutes the target braking force calculation means, and steps S5 and S6 of the calculation processing of FIG. 5 constitute the automatic braking means.

Next, the third embodiment of the vehicle braking control device of the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. 7. The arithmetic processing of FIG. 7 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this calculation process, step S4a of the calculation process of FIG. 2 of the first embodiment is changed to step S4c.

In step S4c, according to the control map of FIG. 8, the time until the start of braking according to the front object speed Vp calculated in step S2, that is, the braking start timing TTC _COM is calculated, and then the process proceeds to step S5. To do. In this control map, the braking start timing TTC _COM is directly proportional to the front object speed Vp, and the larger the front object speed Vp, the longer the braking start timing TTC _COM is set.

In this embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the braking is performed according to the front object speed Vp. The start timing TTC _COM is set, and the arrival time TTC is set to the braking start timing TT.
When the pressure _falls below C _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM
Is directly proportional to the front object speed Vp, and is set to be longer as the front object speed Vp is larger and shorter as the front object speed Vp is smaller. That is, the faster the front object approaches the host vehicle, the longer the braking start timing TTC _COM is set, so that braking is started at a position further away from the front object.

Therefore, by appropriately setting the slope and the intercept of the braking start timing TTC _COM with respect to the front object speed Vp, the braking start timing TTC _COM can be set to be equal to the arrival time TTC, and this is done. Thus, the braking start timing can be made appropriate, and the change of the deceleration generated in the vehicle with respect to the front object speed can be suppressed, so that the occupant does not feel uncomfortable.

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the calculation processing of FIG. 7 constitute the forward object distance detecting means of the present invention, and the same applies to FIG.
The step S2 of the calculation processing of the above constitutes a relative speed detecting means, and the vehicle speed sensor 6 and the step S of the calculation processing of FIG.
1 constitutes the own vehicle speed detecting means, step S2 of the arithmetic processing of FIG. 7 constitutes the forward object speed detecting means, and the road-vehicle communication device 10 and step S1 of the arithmetic processing of FIG.
Constitutes the road friction coefficient state detecting means, step S3 of the arithmetic processing of FIG. 7 constitutes arrival time calculating means, and step S4c of the arithmetic processing of FIG. 7 constitutes braking start timing setting means. Step S6 of the arithmetic processing of No. 7
Constitutes the target braking force calculation means, and steps S5 and S6 of the arithmetic processing of FIG. 7 constitute the automatic braking means.

Next, the fourth embodiment of the vehicle braking control device of the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. The arithmetic processing of FIG. 9 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this calculation process, step S4a of the calculation process of FIG. 2 of the first embodiment is changed to step S4d.

In this step S4d, according to the control map of FIG. 10, the braking is started in accordance with the average value (Vc + Vp) / 2 of the vehicle speed Vc read in step S1 and the forward object speed Vp calculated in step S2. Until the braking start timing TTC _COM is calculated, the process proceeds to step S5. In this control map, the braking start timing TTC _COM is directly proportional to the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, and the larger the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is. The braking start timing TTC _COM is set long.

In the present embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the speed of the host vehicle and the front object speed are calculated. The braking start timing TTC _COM is set according to the average value (Vc + Vp) / 2, and when the arrival time TTC becomes equal to or less than the braking start timing TTC _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM is directly proportional to the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, and the longer the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, the longer the own vehicle. The smaller the average value (Vc + Vp) / 2 of the speed and the front object speed, the shorter the speed is set. That is, as the own vehicle and the front object approach each other faster, the braking start timing TTC _COM is set longer, so that braking is started at a position further away from the front object.

Therefore, the braking start timing TT with respect to the average value (Vc + Vp) / 2 of the vehicle speed and the forward object speed
By properly setting the slope and intercept of C _COM , the braking start timing TTC _COM can be set to be equal to the arrival time TTC, and by doing so, the braking start timing can be made appropriate. Since the change in the deceleration that occurs in the vehicle with respect to the average value of the own vehicle speed and the front object speed can be suppressed, the occupant will not feel discomfort. Further, by setting in this way, for example, when the host vehicle is located at the front object position, at least the speed of the host vehicle can be made equal to the speed of the front object, and the effect of automatic braking can be sufficiently exerted. You can

From the above, the laser radar 2, the radar processing device 3 and step S1 of the arithmetic processing of FIG. 9 constitute the forward object distance detecting means of the present invention, and the same applies to the case of FIG.
The step S2 of the arithmetic processing of FIG. 9 constitutes relative speed detecting means, and the vehicle speed sensor 6 and the step S of the arithmetic processing of FIG.
1 constitutes the own vehicle speed detecting means, step S2 of the arithmetic processing of FIG. 9 constitutes the forward object speed detecting means, and the road-vehicle communication device 10 and step S1 of the arithmetic processing of FIG.
Constitutes the road friction coefficient state detecting means, step S3 of the arithmetic processing of FIG. 9 constitutes arrival time calculating means, and step S4d of the arithmetic processing of FIG. 9 constitutes braking start timing setting means. Step S6 of the arithmetic processing of 9
Constitutes the target braking force calculation means, and steps S5 and S6 of the arithmetic processing of FIG. 9 constitute the automatic braking means.

Next, the fifth embodiment of the vehicle braking control device of the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. The arithmetic processing of FIG. 11 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this arithmetic processing, step S4a of the arithmetic processing of FIG. 2 of the first embodiment is changed to step S4e.

In step S4e, according to the control map of FIG. 12, the average value (Vc + Vp) / 2 of the vehicle speed Vc read in step S1 and the forward object speed Vp calculated in step S2, and in step S1. After the time until the start of braking according to the read road surface friction coefficient μ, that is, the braking start timing TTC _COM is calculated, the process proceeds to step S5. This control map is a three-dimensional map in which the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed and the road surface friction coefficient μ are variables, and the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed Braking start timing TTC for increase and decrease of road friction coefficient μ
_COM increases, and the average value (V
c + Vp) / 2 is larger, the braking start timing TTC
_COM is set longer, and the braking start timing TTC _COM is set longer as the road friction coefficient μ is smaller. It corresponds to a form in which the control map of FIG. 6 of the second embodiment and the control map of FIG. 10 of the fourth embodiment are multiplied.

In this embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the speed of the host vehicle and the front object speed are calculated. Braking start timing TTC _COM according to the average value (Vc + Vp) / 2 and the road surface friction coefficient μ
And the arrival time TTC is equal to the braking start timing T
When it becomes less than TC _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC
_COM is the average value (Vc + V) of the speed of the host vehicle and the speed of the front object.
p) / 2, which is set to be longer as the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is larger, and is set shorter as the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is smaller. At the same time, it is inversely proportional to the road surface friction coefficient μ and is set to be shorter as the road surface friction coefficient μ is larger and longer as the road surface friction coefficient μ is smaller. That is, as the own vehicle and the front object approach each other faster, the more slippery the road surface on which the greater braking force cannot be applied, the more the braking start timing T.
Since TC _COM is set to be long, braking is started at a position distant from the front object by that amount.

Therefore, the braking start timing TTC _COM is made equal to the arrival time TTC by appropriately setting the braking start timing TTC _COM for the average value (Vc + Vp) / 2 of the own vehicle speed and the forward object speed and the road surface friction coefficient μ. The braking start timing can be set appropriately by doing so, and the deceleration that occurs in the vehicle with respect to the average value of the own vehicle speed and the forward object speed and the road surface friction coefficient can be set. Since the change can be suppressed, the passenger does not feel uncomfortable. Further, by setting in this way, for example, when the host vehicle is located at the front object position, at least the speed of the host vehicle can be made equal to the speed of the front object, and the effect of automatic braking can be sufficiently exerted. You can

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the arithmetic processing of FIG. 11 constitute the forward object distance detecting means of the present invention. Similarly, step S2 of the arithmetic processing of FIG. Constitutes the relative speed detecting means, the vehicle speed sensor 6 and step S1 of the arithmetic processing of FIG. 11 constitute the own vehicle speed detecting means, and step S2 of the arithmetic processing of FIG. 11 constitutes the front object speed detecting means. 11, the road-to-vehicle communication device 10 and step S1 of the calculation processing of FIG. 11 constitute road surface friction coefficient state detection means, and step S3 of the calculation processing of FIG. 11 constitutes arrival time calculation means, and the calculation of FIG. Step S4e of the processing constitutes the braking start timing setting means, step S6 of the arithmetic processing of FIG. 11 constitutes the target braking force calculating means, and the step S4e of the arithmetic processing of FIG. Step S5, step S6 constitutes the automatic braking means.

Next, the sixth embodiment of the vehicular braking control device of the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. The arithmetic processing of FIG. 13 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this calculation process, step S4a of the calculation process of FIG. 2 of the first embodiment is changed to step S4f.

In this step S4f, according to the control map of FIG. 14, braking starts according to the average value (Vc + Vp) / 2 of the vehicle speed Vc read in step S1 and the forward object speed Vp calculated in step S2. Until the braking start timing TTC _COM is calculated, the process proceeds to step S5. In this control map, the braking start timing TTC _COM increases as the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed increases, and the larger the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, the larger The braking start timing TTC _COM is set to be long, but particularly in a region where the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is small, the average value (Vc + Vp) / of the own vehicle speed and the front object speed is set. The reduction rate of the braking start timing TTC _{COM with} respect to the decrease of 2 is set to be small.

In this embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the speed of the host vehicle and the front object speed are calculated. The braking start timing TTC _COM is set according to the average value (Vc + Vp) / 2, and when the arrival time TTC becomes equal to or less than the braking start timing TTC _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM is directly proportional to the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, and the longer the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, the longer the own vehicle. The smaller the average value (Vc + Vp) / 2 of the speed and the front object speed, the shorter the speed is set. That is, as the own vehicle and the front object approach each other faster, the braking start timing TTC _COM is set longer, so that braking is started at a position further away from the front object.

Therefore, the braking start timing TT with respect to the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed
By properly setting the slope and intercept of C _COM , the braking start timing TTC _COM can be set to be equal to the arrival time TTC, and by doing so, the braking start timing can be made appropriate. Since the change in the deceleration that occurs in the vehicle with respect to the average value of the own vehicle speed and the front object speed can be suppressed, the occupant will not feel discomfort. Further, by setting in this way, for example, when the host vehicle is located at the front object position, at least the speed of the host vehicle can be made equal to the speed of the front object, and the effect of automatic braking can be sufficiently exerted. You can Further, in this embodiment, in a region where the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is small, the braking start timing TTC with respect to the decrease of the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed. _Since the reduction rate of _COM is set to be small, the response delay of the device can be compensated and the start timing of automatic braking can be made appropriate.

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the arithmetic processing of FIG. 13 constitute the forward object distance detecting means of the present invention, and hereinafter, similarly, the step S2 of the arithmetic processing of FIG. Constitutes the relative speed detecting means, the vehicle speed sensor 6 and step S1 of the arithmetic processing of FIG. 13 constitute the own vehicle speed detecting means, and step S2 of the arithmetic processing of FIG. 13 constitutes the front object speed detecting means. 13, the road-to-vehicle communication device 10 and step S1 of the calculation processing of FIG. 13 constitute road surface friction coefficient state detection means, and step S3 of the calculation processing of FIG. 13 constitutes arrival time calculation means, and the calculation of FIG. The step S4f of the processing constitutes the braking start timing setting means, the step S6 of the arithmetic processing of FIG. 13 constitutes the target braking force calculating means, and the step S4f of the arithmetic processing of FIG. Step S5, step S6 constitutes the automatic braking means.

Next, the seventh embodiment of the vehicle braking control device of the present invention will be described.
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. In this embodiment, the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is changed from that of FIG. 2 of the first embodiment to that of FIG. The arithmetic processing of FIG. 15 and the arithmetic processing of FIG. 2 are similar, and the same steps are denoted by the same reference numerals and detailed description thereof will be omitted. In this arithmetic processing, step S4a of the arithmetic processing of FIG. 2 of the first embodiment is changed to step S4g.

In this step S4g, according to the control map of FIG. 16, the braking is started in accordance with the average value (Vc + Vp) / 2 of the vehicle speed Vc read in step S1 and the forward object speed Vp calculated in step S2. Until the braking start timing TTC _COM is calculated, the process proceeds to step S5. In this control map, the braking start timing TTC _COM increases as the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed increases, and the larger the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, the larger Although the braking start timing TTC _COM is set to be long, the average value of the own vehicle speed and the front object speed (Vc + Vp) / in particular in the region where the average value of the own vehicle speed and the front object speed (Vc + Vp) / 2 is large. The increase rate of the braking start timing TTC _{COM with} respect to the increase of 2 is set to be small.

In the present embodiment, the distance DIST from the host vehicle to the front object is divided by the relative speed Vr to calculate the time TTC required for the host vehicle to reach the front object, and the speed of the host vehicle and the front object speed are calculated. The braking start timing TTC _COM is set according to the average value (Vc + Vp) / 2, and when the arrival time TTC becomes equal to or less than the braking start timing TTC _{COM, the} target braking fluid pressure α is calculated and braking is started. At this time, the braking start timing TTC _COM is directly proportional to the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, and the longer the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed, the longer the own vehicle. The smaller the average value (Vc + Vp) / 2 of the speed and the front object speed, the shorter the speed is set. That is, as the own vehicle and the front object approach each other faster, the braking start timing TTC _COM is set longer, so that braking is started at a position further away from the front object.

Therefore, the braking start timing TT with respect to the average value (Vc + Vp) / 2 of the own vehicle speed and the forward object speed
By properly setting the slope and intercept of C _COM , the braking start timing TTC _COM can be set to be equal to the arrival time TTC, and by doing so, the braking start timing can be made appropriate. Since the change in the deceleration that occurs in the vehicle with respect to the average value of the own vehicle speed and the front object speed can be suppressed, the occupant will not feel discomfort. Further, by setting in this way, for example, when the host vehicle is located at the front object position, at least the speed of the host vehicle can be made equal to the speed of the front object, and the effect of automatic braking can be sufficiently exerted. You can Further, in the present embodiment, in the region where the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed is large, the braking start timing TTC with respect to the increase of the average value (Vc + Vp) / 2 of the own vehicle speed and the front object speed. _Since the increase rate of _COM is set to be small, the start timing of automatic braking can be made more appropriate.

From the above, the laser radar 2, the radar processing device 3 and the step S1 of the arithmetic processing of FIG. 15 constitute the forward object distance detecting means of the present invention, and hereinafter, similarly, the step S2 of the arithmetic processing of FIG. Constitutes the relative speed detecting means, the vehicle speed sensor 6 and step S1 of the arithmetic processing of FIG. 15 constitute the own vehicle speed detecting means, and step S2 of the arithmetic processing of FIG. 15 constitutes the front object speed detecting means. 15, the road-to-vehicle communication device 10 and step S1 of the calculation processing of FIG. 15 constitute road surface friction coefficient state detection means, and step S3 of the calculation processing of FIG. 15 constitutes arrival time calculation means, and the calculation of FIG. Step S4g of the processing constitutes the braking start timing setting means, step S6 of the arithmetic processing of FIG. 15 constitutes the target braking force calculating means, and step S4g of the arithmetic processing of FIG. Step S5, step S6 constitutes the automatic braking means.

Next, the eighth embodiment of the vehicle braking control device of the present invention
An embodiment will be described. The vehicle schematic configuration of this embodiment is the same as that of FIG. 1 of the first embodiment. Further, in this embodiment, the outline of the arithmetic processing performed by the automatic brake control device 8 of FIG. 1 is similar to that of FIG. 2 of the first embodiment, but the target fluid pressure performed at step S6 is the same. The calculation and braking details have changed. Specifically, the arithmetic processing shown in FIG. 17 is executed as a minor program.

In this calculation process, first, step S61.
Then, the target braking deceleration g _S is calculated according to the following two equations. g _S = K ₁ · μ · ((Vc + Vp) / 2) / TTC = K ₁ · μ · ((Vc + Vp) / 2) · Vr / DIST (2) However, K ₁ is the same as the above formula 1. Like K, this is a gain set according to the accuracy of the road surface friction coefficient μ. That is, as in the present embodiment, the road surface friction coefficient μ obtained from the infrastructure through road-to-vehicle communication has relatively high accuracy, and therefore the gain K ₁
Even if is relatively small, the target braking deceleration g _S becomes appropriate for the road surface friction coefficient μ. On the other hand, as will be described later, when the road surface friction coefficient μ is estimated from the operation of the wiper, the outside temperature, etc., the accuracy of comparison is low, so the gain K ₁ is made relatively large and the target braking deceleration g _S is made large. Make sure to obtain sufficient deceleration.

Next, in step S62, the braking fluid
Whether the pressure is controlled to increase or the pressure is controlled to decrease
To detect. Specifically, let ε be a small predetermined value, and
The target braking deceleration g of the past five times calculated as described above_SNodaira
Average value g_Save0And the target braking deceleration of the past 5 times more than that
Degree g_SAverage value (hereinafter, the target braking deceleration of the past 6 to 10 times
Also referred to as the average value of degrees) g_Save1Compared with the past 5 times
Average value of target braking deceleration g_Save0Since the last 6-10 times
Average value of target braking deceleration g_Save1The value obtained by subtracting
When the value is less than the specified value (-ε), the deceleration is generally small.
Since there is a tendency to reduce the pressure,
Average of target braking deceleration 5 times g_Save0From the past 6 to 1
Average value g of zero target braking deceleration_Save1Value minus
When the value is equal to or greater than the specified value (+ ε), the speed is generally reduced.
Since there is a tendency to increase the pressure, it is judged that the pressure is in the increased state.
It The average value g of the target braking decelerations of the past five times
_{Save 0}To the average value g of the target braking deceleration from the past 6 to 10 times
_Save1Is less than the negative predetermined value (-ε)
If it is smaller than the positive predetermined value (+ ε),
It is assumed that it is in the same state as the above.

Next, in step S63, the filter time constant τ corresponding to the target braking deceleration g _S is set according to the control map of FIG. The control map of FIG. 18 is
In general, the larger the target braking deceleration g _S is, the larger the time constant τ is set.
Hysteresis is provided when the braking fluid pressure detected in step 1 is reduced and when it is increased, and the time constant τ is set to be larger when the braking fluid pressure is reduced than when it is increased. This enhances the responsiveness when the braking fluid pressure is increased so that the necessary deceleration can be quickly obtained, and the responsiveness when the braking fluid pressure is reduced is slowed down so that the braking is smooth. This is because

[0068] and then proceeds to step S64, using a filter time constant τ which is set in step S63, performs a filtering process on the target braking deceleration g _S calculated at step S61. This filtering process may be performed using a well-known first-order lag filter or second-order lag filter. Then, the process proceeds to step S65, and the following 3
According to the formula, the target braking fluid pressure α is calculated based on the filtering target braking deceleration g _Sfil . Note that K _{3 in} the formula
Is a gain for converting the filtering target braking deceleration g _Sfil into the target braking fluid pressure α.

Α = K ₃ · g _Sfil (3) Next, the process proceeds to step S66 to _generate and output a braking fluid pressure control signal that achieves the target braking fluid pressure α calculated in step S65. To return to the main program.
According to this calculation process, in step S63, the filter time constant τ corresponding to the target braking deceleration g _S is set, and the target braking deceleration g _S is filtered using the time constant τ. Here, the filter time constant τ is generally set to be smaller as the target braking deceleration g _S is larger irrespective of whether the braking fluid pressure is increased or depressurized. Therefore, for example, when the target braking deceleration g _S is small. Filter time constant τ
Is set large, and smooth braking can be achieved when a large deceleration is not required. On the contrary, when the target braking deceleration g _S is large, the filter time constant τ is set small, so that the braking force is quickly increased when a large deceleration is required, and as a result, the responsiveness is improved and the Since it suffices to maintain the braking force equal or to gradually reduce the braking force, it is possible to prevent a rapid change in the deceleration with respect to the passage of time in one braking. Further, when the braking fluid pressure is reduced, the filter time constant τ is configured to be larger than that when the braking fluid pressure is increased. Therefore, it is possible to adjust the way of reducing the braking fluid pressure to be gentler than the way of increasing pressure. As a result, after the start of braking, the braking fluid pressure can be quickly increased to obtain the required deceleration, and thereafter, the braking fluid pressure can be gently reduced to achieve smooth braking. It is possible to further prevent and prevent a sudden change in deceleration.

FIG. 19 shows changes with time in the inter-vehicle distance, the target braking deceleration, and the braking fluid pressure by the arithmetic processing of FIG. In this example, the preceding vehicle decelerates at a relatively moderate deceleration constant, and as a result, the traveling speed of the preceding vehicle decelerates with a uniform slope. It is decreasing in a curve.
As shown in FIG.
The target braking deceleration g _S calculated and set in accordance with the above-described equation 2 in step S61 of the calculation process of No. 7 is the inter-vehicle distance DI.
It increases in inverse proportion to ST. With respect to the gradually increasing target braking deceleration g _S , the filter time constant τ set in step S63 of the calculation process of FIG. 17 has a large value in the initial stage of braking, but thereafter, the target braking deceleration g It is set to a small value as _S increases. Therefore, the target braking fluid pressure α calculated in step S65 of the calculation process of FIG. 17 based on the filtering target braking deceleration g _Sfil that has been filtered using this time constant τ is
Immediately after the start of braking, the pressure increase gradient is small, but the inter-vehicle distance D
Responsiveness increases as IST increases, and the pressure is rapidly increased. As a result, the traveling speed of the host vehicle is quickly reduced, the decrease in the inter-vehicle distance DIST is moderated, and the increase in the target braking deceleration g _S is suppressed. Even after that, the traveling speed of the host vehicle continues to decrease, so that the increase in the inter-vehicle distance DIST is further suppressed, and as a result, the target braking deceleration g _S starts to decrease.

As described above, the target braking deceleration g_SDecrease of
If the direction continues, in step S62 of the arithmetic processing of FIG.
Since it is determined that the braking fluid pressure will be reduced, the same step
The filter time constant τ set in step S63 depends on the pressure reduction.
It becomes a little small value. However, the target system is still
Dynamic deceleration g_SIs still big, so fill
The value of the time constant τ itself is large, and the target braking deceleration g_SImmediately
The target braking fluid pressure α changes according to the change in the vehicle-to-vehicle distance DIST.
Change to high response. After that, the target braking deceleration g _SIs further
When it decreases, the filter time constant τ gradually increases accordingly.
Larger value and target braking deceleration g_SAgainst decrease
The target braking fluid pressure α is decreased more gradually, and
As a result, smooth braking is achieved.

As described above, according to the vehicle braking control apparatus of the present embodiment, the braking fluid pressure is controlled with high response when the target braking deceleration is large, and the smooth braking is possible when the target braking deceleration is small. To do. As a result, in the timing chart of FIG. 19, the peak of the braking fluid pressure is in the vicinity of the center of one braking, and there is no discomfort in the braking effectiveness or the relaxation effectiveness.

On the other hand, FIG. 20 is a simulation in which the time constant of the filter when calculating the target braking fluid pressure from the target braking deceleration is fixed to a large value, and the problem is clarified. Therefore, it is assumed that the preceding vehicle slows down relatively slowly. In this example, the preceding vehicle decelerates with a relatively small constant deceleration, resulting in
Since the traveling speed of the preceding vehicle is reduced with a uniform small slope,
The inter-vehicle distance DIST that appears as the integrated value gradually decreases in a quadratic curve. With respect to the inter-vehicle distance DIST thus reduced, the target braking deceleration g _S is as shown in FIG.
Similarly, the distance increases in inverse proportion to the vehicle-to-vehicle distance DIST, but the increase is slower than in FIG. With respect to this gradually increasing target braking deceleration g _S , the target braking fluid pressure α calculated by the filtering process having a large time constant does not easily increase even if the target braking deceleration g _S increases, and as a result, Since the decrease in the inter-vehicle distance DIST becomes gradual, the target braking deceleration g _S becomes even larger, and the target braking deceleration g _S does not become larger, the target braking fluid pressure α only accelerates with the passage of time. Increase. As a result, a large deceleration acts on the host vehicle during the latter half of the braking, which causes the inter-vehicle distance to decrease rapidly, which in turn reduces the target braking deceleration g _S rapidly, after which the braking fluid pressure α
Becomes smaller gradually. That is, the filter time constant when calculating the target brake fluid pressure α from the target braking deceleration g _S is large, when the target braking deceleration g _S is large, not achieved quite necessary deceleration, once The deceleration rapidly increases in the latter half of braking, and then the deceleration rapidly decreases. When the time constant of the filter is large as described above, when the target braking deceleration is large, the change in deceleration over time is large, and the occupant feels uncomfortable.

On the contrary, FIG. 21 is a simulation in the case where the time constant of the filter for calculating the target braking fluid pressure from the target braking deceleration is fixed to a small value,
In order to clarify the problem, it is assumed that the preceding vehicle decelerates relatively quickly. In this example, the preceding vehicle decelerates rapidly with a relatively large deceleration, and as a result, the traveling speed of the preceding vehicle decelerates with a large inclination. Therefore, the inter-vehicle distance DIST that appears as an integral value of the preceding vehicle is a quadratic curve. Has decreased. Inter-vehicle distance DI that decreases in this way
In contrast to ST, the target braking deceleration g _S increases in inverse proportion to the inter-vehicle distance DIST as in the case of FIG. 19, but the method of increase is faster than in FIG. 19. With respect to the gradually increasing target braking deceleration g _S , the target braking fluid pressure α calculated by the filtering process having a small time constant rapidly increases as the target braking deceleration g _S increases, and as a result, the inter-vehicle distance DIST. Decreases rapidly, the target braking deceleration g _S does not increase any more, and starts to decrease slowly. Along with the change in the target braking deceleration g _S, the target braking fluid pressure α set by the filtering process having a small time constant also changes with a similar tendency, and after the rapid increase in the initial stage of braking, It decreases with the same value. As a result, a large deceleration acts on the host vehicle in the first half of braking, and then the braking fluid pressure α gradually decreases. That is, the filter time constant when calculating the target brake fluid pressure α from the target braking deceleration g _S is small, when the target braking deceleration g _S is small, since a large deceleration suddenly will occur one The deceleration rapidly increases in the first half of each braking, and then gradually decreases. When the time constant of the filter is small in this way, when the target braking deceleration is small, the change in deceleration over time is large and the occupant feels uncomfortable.

From the above, the laser radar 2, the radar processing device 3, and step S1 of the arithmetic processing of FIG. 2 constitute the forward object distance detecting means of the present invention, and the same applies to the above-mentioned FIG.
Step S2 of the arithmetic processing of FIG. 2 constitutes relative speed detecting means, step S3 of the arithmetic processing of FIG. 2 constitutes arrival time calculating means, and step S4a of the arithmetic processing of FIG. 2 constitutes braking start timing setting means. Then, step S61 of the calculation process of FIG. 17 constitutes a target braking deceleration calculation means, and steps S5 and S of the calculation process of FIG.
6 and step S62 to step S of the arithmetic processing of FIG.
66 constitutes automatic braking means.

In each of the above-described embodiments, only one or two variables for setting the braking start timing are used, but the braking start timing may be set by appropriately combining these variables. It is also possible to do so, and by doing so, the braking start timing can be made more appropriate for various factors.

Further, in the above-described embodiment, only the case where the road surface friction coefficient state is acquired by the road-to-vehicle communication with the infrastructure has been described in detail. However, for example, the slip ratio is obtained from the own vehicle speed and the wheel speed, and it is applied to the wheels simultaneously. The braking / driving force to be calculated may be calculated, and the road surface friction coefficient state may be calculated from the relationship between the braking / driving force and the slip ratio at that time. Similarly, the outside air temperature is detected and the operating state of the wiper is monitored.When the wiper is operating, it is determined that the road surface is wet and a road surface friction coefficient state equivalent to a wet road is set. When the vehicle is below freezing, a road surface friction coefficient state corresponding to a frozen road may be set.

Further, in the above embodiment, only the case of using the laser radar which cannot directly detect the relative speed is described in detail, but the relative speed is directly detected by the Doppler effect or the like like the millimeter wave radar. With a radar that can be used, the relative speed between the front object and the vehicle can be directly detected and used. In the above embodiment,
Although a microcomputer is used for each arithmetic processing unit, various logic circuits can be used instead of the microcomputer.

[Brief description of drawings]

FIG. 1 is a vehicle configuration diagram showing an example of a vehicle with a preceding vehicle following travel control provided with a vehicle braking control device of the present invention.

FIG. 2 is a flowchart showing a first embodiment of a calculation process for automatic braking control.

FIG. 3 is a control map used in the arithmetic processing of FIG.

FIG. 4 is a diagram for explaining the operation of the arithmetic processing of FIG.

FIG. 5 is a flowchart showing a second embodiment of a calculation process for automatic braking control.

FIG. 6 is a control map used in the arithmetic processing of FIG.

FIG. 7 is a flowchart showing a third embodiment of a calculation process for automatic braking control.

8 is a control map used in the arithmetic processing of FIG.

FIG. 9 is a flowchart showing a fourth embodiment of a calculation process for automatic braking control.

10 is a control map used in the arithmetic processing of FIG.

FIG. 11 is a flowchart showing a fifth embodiment of a calculation process for automatic braking control.

12 is a control map used in the arithmetic processing of FIG.

FIG. 13 is a flowchart showing a sixth embodiment of a calculation process for automatic braking control.

14 is a control map used in the arithmetic processing of FIG.

FIG. 15 is a flowchart showing a seventh embodiment of a calculation process for automatic braking control.

16 is a control map used in the arithmetic processing of FIG.

FIG. 17 is a flowchart showing an eighth embodiment of arithmetic processing for automatic braking control.

18 is a control map used in the arithmetic processing of FIG.

19 is a timing chart showing the operation of the arithmetic processing of FIG.

FIG. 20 is a timing chart showing an operation when the filter time constant is large.

FIG. 21 is a timing chart showing an operation when the filter time constant is small.

[Explanation of symbols]

1 is an external recognition device 2 is a laser radar 3 is a laser radar processing device 4 is a CCD camera 5 is an image processing device 6 is a vehicle speed sensor 7 is a steering angle sensor 8 is an automatic brake control device 9 is a negative pressure brake booster 10 is an inter-vehicle communication device

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Taku Takahama             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Naotaka Usui             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Harahei Naito             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Ken Kimura             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation (72) Inventor Masayuki Watanabe             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F term (reference) 3D046 BB18 HH20 HH22 HH46

Claims (10)

[Claims] 1. A front object distance detecting means for detecting a distance between an object existing in front of the own vehicle and the own vehicle, and a relative speed detecting means for detecting a relative speed of an object existing in front of the own vehicle with respect to the own vehicle. Own vehicle speed detecting means for detecting the speed of the own vehicle, front object speed detecting means for detecting the speed of an object existing in front of the own vehicle, road surface friction coefficient state detecting means for detecting the friction coefficient state of the road surface, and The time taken for the host vehicle to reach the front object by dividing the distance between the host vehicle and the object existing in front of the host vehicle detected by the front object distance detection means by the relative speed detected by the relative speed detection means Arrival time calculating means for calculating, the speed of the own vehicle detected by the own vehicle speed detecting means, the speed of the front object detected by the front object speed detecting means, and the road detected by the road surface friction coefficient state detecting means Braking start timing setting means for setting the time until the braking is started based on at least one of the surface friction coefficient states, the speed of the own vehicle detected by the own vehicle speed detecting means, and the front object speed detection Target braking force calculating means for calculating a target braking force of the own vehicle based on a value obtained by dividing an average value of the speed of the front object detected by the means by the arrival time calculated by the arrival time calculating means; Automatic braking means for generating the target braking force calculated by the target braking force calculation means when the arrival time calculated by the time calculation means is equal to or less than the time until the braking start set by the braking start timing setting means And a braking control device for a vehicle. 2. The braking start timing setting means sets a shorter time to start braking as the road surface friction coefficient state detected by the road surface friction coefficient state detecting means is smaller. Vehicle braking control device. 3. The braking start timing setting means sets a shorter time until braking starts as the own vehicle speed detected by the own vehicle speed detecting means is set shorter. Vehicle braking control device. 4. The braking start timing setting means sets a shorter time until the start of braking as the front object speed detected by the front object speed detecting means increases. A braking control device for a vehicle according to claim 1. 5. The braking start timing setting means brakes as the average value of the speed of the own vehicle detected by the own vehicle speed detecting means and the speed of the front object detected by the front object speed detecting means increases. The vehicle braking control device according to any one of claims 1 to 4, wherein the time until the start is set to be short. 6. The braking start timing setting means is provided in a region where the average value of the speed of the own vehicle detected by the own vehicle speed detecting means and the speed of the front object detected by the front object speed detecting means is small. The braking control device for a vehicle according to claim 5, wherein a reduction rate of a time until the start of braking is set to be small with respect to the reduction of the average value. 7. The braking start timing setting means is provided in a region where a mean value of the speed of the own vehicle detected by the own vehicle speed detecting means and the speed of the front object detected by the front object speed detecting means is large. The braking control device for a vehicle according to claim 5 or 6, wherein the increase rate of the time until the start of braking with respect to the increase of the average value is set to be small. 8. A front object distance detecting means for detecting a distance between an object existing in front of the own vehicle and the own vehicle, and a relative speed detecting means for detecting a relative speed of an object existing in front of the own vehicle with respect to the own vehicle. Time until the own vehicle reaches the front object by dividing the distance between the own vehicle and the object existing in front of the own vehicle detected by the front object distance detecting means by the relative speed detected by the relative speed detecting means Arrival time calculating means for calculating, and at least the own vehicle based on the distance between the object existing in front of the own vehicle detected by the front object distance detecting means and the own vehicle, and the relative speed detected by the relative speed detecting means. Target braking deceleration calculation means for calculating the target braking deceleration and the target braking deceleration calculation means when the arrival time calculated by the arrival time calculation means is less than or equal to a predetermined time until the start of braking. An automatic braking unit that controls the braking fluid pressure so as to generate the calculated target braking deceleration, and the automatic braking unit, according to the target braking deceleration calculated by the target braking deceleration calculation unit, A braking control device for a vehicle, which adjusts a way of increasing a braking fluid pressure. 9. The method according to claim 8, wherein the automatic braking means adjusts the way of reducing the braking fluid pressure according to the target braking deceleration calculated by the target braking deceleration calculating means. Vehicle braking control device. 10. The automatic braking means controls the braking fluid pressure so that the target braking deceleration calculated by the target braking deceleration calculating means is achieved, and the way of reducing the braking fluid pressure is to increase the pressure. The braking control device for a vehicle according to claim 9, wherein the braking control device is adjusted so as to be gentler than the above method.