JP2000326837A - Automatic brake control device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatic brake control device for a vehicle whereby when the vehicle is stopped by automatic braking, deceleration is effected without discomfort from the start of deceleration to the stop of the vehicle. SOLUTION: This control device includes an intervehicular distance sensor 14 which measures the distance to an object ahead, a vehicle speed sensor 12 for measuring the speed of a vehicle, a controller 17 for computing the acceleration and deceleration of the vehicle and the speed of the vehicle relative to the object ahead and for imparting a braking command to brake control means according to the results of detection and computations, and brake control means for controlling the braking force of the vehicle. The controller 17 includes at least the function of computing a first braking force for decelerating or stopping the traveling vehicle, the function of computing a second braking force for keeping the vehicle stopped, and the function of switching the first braking force to the second braking force on determining that the vehicle has stopped. When the vehicle is determined to be at standstill and the first braking force is switched to the second braking force, the final value of the first braking force is set as the initial value of the second braking force.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic deceleration system that automatically decelerates a vehicle when the vehicle is approaching a preceding vehicle and the inter-vehicle distance becomes less than a predetermined value.
The present invention relates to an automatic braking control device for a vehicle that automatically stops when a preceding vehicle stops and maintains an appropriate inter-vehicle distance, and continues to maintain a predetermined braking force even after stopping.

[0002]

2. Description of the Related Art In recent years, in order to protect occupants and reduce the burden on a driver while the vehicle is running, the vehicle is equipped with an inter-vehicle distance detecting means such as a radar, and the relative speed to the preceding vehicle and the inter-vehicle distance are measured. There have been proposed various devices that constantly monitor the vehicle, issue a warning when the vehicle enters a dangerous area, automatically control the vehicle speed by performing an accelerator operation or a braking operation, and constantly maintain an appropriate distance between vehicles. . For example, JP-A-59-23
The technology disclosed in Japanese Patent No. 1157 determines the degree of danger based on the output of a vehicle speed sensor and an inter-vehicle distance detecting means, issues a warning in accordance with the degree of danger, applies deceleration by throttling operation, and quickly approaches the preceding vehicle. When in the state, the brake is operated by operating the brake actuator.

The technique disclosed in Japanese Patent Laid-Open Publication No. Sho 61-77534 obtains a relative speed with respect to a preceding vehicle from a rate of change of the inter-vehicle distance measured by an inter-vehicle distance detecting means. Calculates the safe inter-vehicle distance, starts deceleration operation according to the difference between the safe inter-vehicle distance and the actual inter-vehicle distance, and the control device determines according to the ratio of the deceleration to the reference deceleration, and performs throttle operation and shift operation. A down operation, a brake operation, and an amount of these operations are selected to smoothly and safely decelerate.

Further, in the technique disclosed in Japanese Patent Application Laid-Open No. H10-147222, a forward monitoring device detects a distance to a forward obstacle and a relative speed, and a control device operates a brake actuator in accordance with these values. Deceleration operation, control from gentle braking to sudden braking while monitoring the distance to the obstacle and the relative speed, and when stopping with sudden braking, stop when the vehicle speed falls below a predetermined value. The braking force is reduced to a predetermined value upon determination, and the braking force at the time of stopping is changed according to the inclination of the road.

[0005]

As described above, JP-A-59-231157 and JP-A-61-77534 disclose only the technique relating to the braking operation during traveling. Japanese Patent Application Laid-Open No. Hei 10-147222 discloses a technique from the braking operation during traveling to the maintenance of the braking force during stopping when the vehicle is stopped by braking. Perform when the value is less than
Since the braking force is changed, there is a problem that the braking force changes and the impact is applied to the vehicle body at a low speed running state, and the braking distance is slightly changed but the riding feeling is always good. is not.

The present invention has been made to solve such a problem, and automatic braking is performed in order to maintain a safe inter-vehicle distance with a preceding vehicle. As a result, the host vehicle stops. It is an object of the present invention to obtain an automatic braking control device for a vehicle in which a stopped state is reliably maintained when the vehicle is decelerated without a sense of incongruity between the start of deceleration and the stop of the vehicle.

[0007]

An automatic braking control apparatus for a vehicle according to the present invention comprises: an inter-vehicle distance detecting means for measuring a distance to a forward object; a vehicle speed detecting means for measuring a speed of the own vehicle; Self-vehicle acceleration / deceleration detection means for measuring or calculating the acceleration / deceleration of the own vehicle, relative speed detection means for measuring or calculating the relative speed with respect to the object in front, braking control means for controlling the braking force of the own vehicle, A control device for giving a braking command to a braking control device based on a signal from each detection device, wherein the control device has at least a function of calculating a first braking force for decelerating or stopping the running own vehicle, and stopping the vehicle. It has a function of calculating a second braking force for maintaining, and a function of determining a stop and switching from the first braking force to the second braking force. When switching to the second braking force from , In which the final value of the first braking force is to be set as the initial value of the second braking force.

After the vehicle is stopped, the initial value of the second braking force is changed to a specific value or more at a predetermined time rate. Further, after the vehicle speed detecting means detects the stop, the vehicle is determined to be stopped after a predetermined time has elapsed, and the first braking force is switched to the second braking force.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a configuration diagram of an automatic braking control device for a vehicle according to a first embodiment of the present invention, and FIGS. 2 to 10 are flowcharts illustrating the flow of operation. In FIG. 1, 1 is a brake pedal of a vehicle, 2 is a brake switch for detecting that the brake pedal 1 is depressed to a predetermined depth, 3 is a booster that amplifies the depressing force of the brake pedal 1, and 4 is a brake pedal. 1 is a master cylinder that sends the brake fluid of the reservoir 5 to the brake pipe 7a by the operation of 1.
a is connected to the discharge port of the master cylinder 4 and is branched into branch pipes 7b and 7c.
The branch pipe 7c is connected to the wheel cylinder 6 via a pressurizing valve 9 and a pressurizing pump 10.

Reference numeral 11 denotes an accelerator switch for detecting that an accelerator pedal (not shown) is depressed to a predetermined depth, 12 a vehicle speed sensor for detecting the vehicle speed of the vehicle, and 13 a wheel cylinder pressure for detecting the hydraulic pressure applied to the wheel cylinder 6. A sensor, 14 an inter-vehicle distance sensor for measuring an inter-vehicle distance with a preceding vehicle traveling in front, 15 a shift range detecting switch for detecting a shift range of a transmission, and 16 a brake using the automatic braking control device for the vehicle. This is an operation switch of the automatic braking control device for selecting whether to perform braking or manual braking.

Reference numeral 17 denotes a control unit, which is a ROM 1 for storing a control program of the automatic braking control unit and necessary data.
8, a control program is read out from the ROM 18 and subjected to arithmetic processing in accordance with the procedure. The control contents are calculated and output based on information from various sensors and switches input via an interface, and the control device is totally controlled. A CPU 19, a RAM 20 for temporarily storing a calculation result in the middle of the CPU 19, an input interface 21 corresponding to various sensors and switches, and an output interface 22 corresponding to actuators such as valves and pumps; Address path / data path 2
3.

Brake switch 2 and accelerator switch 1
1, a vehicle speed sensor 12, a wheel cylinder pressure sensor 13, an inter-vehicle distance sensor 14, a shift range detection switch 15, and an operation switch 16 are connected to an input interface 21 of a control device 17 as input information. The pressurizing pump 10 is connected to the output interface 22 of the control device 17 as actuators. The shut-off valve 8 is a normally-open valve that maintains an open state when there is no command from the control device 17, and the pressurizing valve 9 is a normally-closed valve that maintains a closed state when there is no command from the control device 17.

In the thus configured automatic braking control apparatus for a vehicle according to the first embodiment of the present invention, when the braking operation is performed by the driver with the operation switch 16 turned off, first, the braking operation is performed. The pedal 1 is depressed, and the depressing force is amplified by the booster 3 so that the master cylinder 4
, The pressure in the master cylinder 4 increases, and the pressure of the master cylinder 4 is applied to the branch pipes 7b and 7c via the brake pipe 7a. Since the shutoff valve 8 is a normally open valve and the pressurizing valve 9 is a normally closed valve, the pressure is transmitted to the wheel cylinder 6 via the branch pipe 7b, and a braking force proportional to the pressure of the wheel cylinder 6 is generated. .

When performing automatic braking with the operation switch 16 turned on, first, the control device 17 closes the shut-off valve 8,
The pressurizing valve 9 is opened. When braking or deceleration is required by the input of the vehicle speed sensor 12 or the inter-vehicle distance sensor 14, the control device 17 controls the pressure of the hall cylinder 6 (hereinafter referred to as brake pressure), braking force, deceleration, A target value such as a target speed or any of the target values is set, and the pressurizing pump 10 is driven in accordance with the target value. By driving the pressurizing pump 10, the brake fluid in the reservoir 5 passes through the branch pipe 7c and is pressurized to a target value and supplied to the wheel cylinder 6, and generates a braking force proportional to this pressure. When the control device 17 holds the braking force, the brake pressure is held at the target value by stopping the pressurizing pump 10 and closing the pressurizing valve 9, and when the braking force is weakened or eliminated, the brake pressure is reduced. By opening the shutoff valve 8 until the new target value is reached, the brake fluid returns to the reservoir 5 and reduces the brake pressure.

The operation of the control device 17 at this time is as shown in the flowcharts of FIGS. In the following description, symbols provided with symbols Z and Y, such as the vehicle speed (own vehicle speed) ZVs of the own vehicle, the inter-vehicle distance ZLdis with the preceding vehicle, the relative speed ZVr with the preceding vehicle, and the brake control flag Ycntl, are stored in the RAM 20. And a rewritable / read-out variable or flag to be written. Symbols with the symbol X, such as the deceleration feedback proportional gain Xp1 and the deceleration feedback integral gain Xi1,
Indicates data that cannot be rewritten and that can only be read out.

FIG. 2 shows a main routine of the program of the control device 17, which is repeatedly executed by the CPU 19 at predetermined time intervals, for example, at intervals of 20 ms.
20 are initialized. In step 202, the control device 1
7, the state of each sensor and switches connected to the input interface 21 is read and input processing is performed. In step 203, a brake release condition determination for determining whether to operate each actuator connected to the output interface 22 is performed. The process is performed, and in step 204, a target value calculation process for calculating a target value for operating the actuators is performed. In step 205, output processing for operating the actuators is executed based on the calculation result. The processing executed in each step of the main routine is as described below with reference to the flowcharts of FIGS. is there.

FIG. 3 is a flowchart showing a routine of the input process in the above-mentioned step 202.
It is called and executed. Step 30
In step 1, the ON / OFF state of the brake switch 2 is checked to determine whether the brake pedal 1 is depressed. In step 302, the accelerator switch 11 is turned on / off.
The state is checked to determine the presence or absence of an accelerator operation. In step 303, a signal output from the vehicle speed sensor 12 is input, and the own vehicle speed ZVs is stored in the RAM 20.
In step 4, the acceleration / deceleration ZAs of the host vehicle is calculated from the temporal change rate of the host vehicle speed ZVs and stored in the RAM 20. Step 30
In step 5, the brake pressure ZPreal is detected and stored by the wheel cylinder pressure sensor 13, and in step 306, the inter-vehicle distance ZLdi from the preceding vehicle is detected by the inter-vehicle distance sensor 14.
s is detected and stored. In step 307, the following distance Z
From the rate of change of Ldis over time, the relative speed ZV with the preceding vehicle
r is calculated and stored. In step 308, the own vehicle speed ZVs
The acceleration / deceleration ZApre of the preceding vehicle is calculated and stored from the temporal change rate of the sum of the acceleration and the relative speed ZVr. Step 3
In step 09, it is detected from the ON / OFF state of the operation switch 16 whether or not the automatic braking device is in the operation required state.
At 10, the shift range position is detected from the state of the shift range detection switch 15.

The details of the brake release condition determination processing in step 203 are as shown in the flowchart of FIG. 4, and are called and executed from step 203.
In step 401, the accelerator switch 11 is determined in step 302, and if the accelerator switch 11 is in the ON state, the operation jumps to step 406 without operating the automatic braking device, clears the brake control flag Ycntl, and
If F, go to step 402. In step 402, the brake switch 2 is turned on by the determination in step 301.
If it is in the state, the flow jumps to step 406 to clear the brake control flag Ycntl, and if it is in the OFF state, the flow proceeds to step 403. In step 403, if the operation switch 16 is in the OFF state as determined in step 309, the flow jumps to step 406 to clear the brake control flag Ycntl, and if it is in the ON state, the flow proceeds to step 404. In step 404, if the shift lever position is in the parking, neutral or reverse position as determined in step 310, the routine jumps to step 406 and the brake control flag Yc
ntrl is cleared, and if it is at any other position, the process proceeds to step 405. In step 405, a brake control flag Ycntl is set to operate the automatic braking device.

FIG. 5 is a flowchart showing a processing routine of the target value calculation processing in step 204 described above. The processing is called from step 204 and executes the following processing.
In step 501, a target deceleration ZTarget is calculated by a function f1 having the above-mentioned inter-vehicle distance ZLdis, relative speed ZVr, and acceleration / deceleration ZApre of the preceding vehicle as arguments, and stored in the RAM 20. The calculation of the target deceleration ZTarget by the function f1 is as follows.

The own vehicle is positioned at a distance ZLdis
(M) It is assumed that the vehicle is following away, and the absolute position Sp of the preceding vehicle after t seconds based on the own vehicle position at a certain point in time is calculated by the following equation (1). Sp = ZVp · t + ZApre · t 2/2 + ZLdis (1) Here, ZVP: speed of the preceding vehicle (m / s) ZApre: acceleration of the preceding vehicle (m / s ^2), and the absolute of the vehicle after t seconds The position Ss is calculated by the following equation (2). Ss = ZVs · t + ZAs · t 2/2 (2) Here, ZVS: vehicle speed (m / s) ZAs: apart on the vehicle acceleration and deceleration (m / s ²⁾ the vehicle is the preceding vehicle by the target following distance ZLtarget It is necessary to satisfy the following formula: Sp-Ss = ZLtarget (3) to drive the vehicle. Therefore, by substituting the formulas (1) and (2) into the formula (3), the formula (ZApre-ZAs) / 2 · t ² + (ZVp−ZVs) · t + (ZLdis−ZLtarget) = 0 (ZApre−ZAs) / 2 · t ² + ZVr · t + ZdL = 0 (4) where ZVr: relative speed (m / s), that is, ZVp −
ZVs ZdL: Inter-vehicle distance deviation (ZLdis-ZLtarget)
t) is obtained, and when this is transformed with respect to ZAs, the following equation is obtained: ZAs = 2 / t ² · ZdL + 2 / t · ZVr + ZApre = Xk ₁ · ZdL + Xk ₂ · ZVr + ZApre = ZAtarget (5), and the target deceleration ZAtarget is obtained. Here, Xk ₁ = 2 / t ² , and Xk ₂ = 2 / t, which is data uniquely determined by giving t. The target deceleration ZTarget is a target deceleration for driving the vehicle at a target inter-vehicle distance ZLtarget with respect to the preceding vehicle.

In step 502, it is determined whether or not the vehicle speed ZVs is ≠ 0.
03, in step 503, the target deceleration ZAtar
A deceleration deviation ZdA between get and the own vehicle acceleration / deceleration ZAs is calculated and stored. In step 504, the current deceleration deviation ZdA is added to the integrated value ZdAsum (n-1) of the previous deceleration deviation and stored as ZdAsum (n). In step 505, the current target brake pressure ZPtarget (n) is calculated according to the following equation (6). ZPtarget (n) = Xp1 (ZdA + Xi1 · ZdAsum (n)) (6) where ZdA: deceleration deviation ZdAsum (n): integrated value of deceleration deviation up to this time Xp1: deceleration feedback proportional gain Xi1: deceleration feedback Integral gain Note that feedback gains Xp1 and Xi1 are RO
This is data stored in advance in M18, and is a parameter for adjusting the followability of the acceleration / deceleration ZAs with respect to the target deceleration ZTarget. In step 506, a flag Ycntl_A is set to indicate that the current time is the deceleration feedback processing. In step 507, the integral value Zd of the speed deviation used in the speed feedback processing is set.
Clear Vsum (n) to 0.

If the own vehicle speed ZVs is not ≠ 0 in step 502, the flow advances to step 508 to determine whether or not the previous time was the deceleration feedback processing, ie, Ycntl_A.
It is determined whether or not the flag is set, and the flag Y
If cntl_A is not set, step 510
To step 509 if it is set. In step 509, the previous target brake pressure ZPtarget
t (n-1), that is, the final value of the target brake pressure in the deceleration feedback processing is set as the initial value ZPinit of the target brake pressure in the speed feedback processing. In step 510, the target speed is set to 0 and the vehicle speed Z is set.
The speed deviation from Vs is calculated and stored as ZdV. In step 511, the integrated value ZdVs of the speed deviation up to the previous time
um (n-1), the speed deviation ZdV is added, and ZdVsu
m (n).

In step 512, the present target brake pressure ZPtarget (n) is calculated by the following equation. ZPtarget (n) = Xp2 (ZdV + Xi2 · ZdVsum (n)) + ZPinit (7) where ZdV: speed deviation ZdVsum (n): integral value of current speed deviation Xp2: speed feedback proportional gain Xi2: speed feedback integral gain ZPinit: initial value of target brake pressure Note that the speed feedback gains Xp2 and Xi2 are R
It is data stored in advance in the OM 18 and is a parameter for adjusting the ability of the speed ZVs to follow the target speed.

In step 513, a flag Ycnt is used to indicate that this time was not the deceleration feedback processing.
Clear rl_A. Therefore, step 509 is passed only when the operation is switched from the deceleration feedback processing to the speed feedback processing by operating the flag Ycntl_A. In step 514, the integral value Zd of the deceleration deviation used in the deceleration feedback process
Clear Asum (n) to 0.

FIGS. 6 to 10 show steps 205 in FIG.
FIG. 6 shows a processing routine of the output processing, which is called from step 205 and executed. FIG.
First, in step 601, the brake control flag Ycnt operated in the brake release condition determination process of FIG.
It is determined whether or not rl is in the set state, and if it is in the set state, the routine proceeds to step 602, where the target brake pressure ZPt
Calculate a pressure deviation ZdP from the target brake pressure ZPre and the current brake pressure ZPreal by the following equation: ZdP = ZPtarget (n) -ZPreal (8) In step 603, the absolute value | ZdP | of the pressure deviation ZdP is compared with a preset dead zone XdP to determine whether or not the condition of | ZdP | <XdP is satisfied. If | ZdP | <XdP is satisfied, the process jumps to step 605 to perform the holding operation. This holding operation is as shown in the flowchart of FIG. 7. In step 701, a command is issued to keep the shutoff valve 8 closed, and in step 702, a command is issued to keep the pressurizing valve 9 closed. In step 703, a command is issued to keep the pressure pump 10 in the OFF state.

If | ZdP | <XdP is not satisfied at step 603, the routine proceeds to step 604, where the pressure deviation Z
It is determined whether dP is positive or negative. If ZdP ≧ 0, the routine proceeds to step 606, where the pressure increasing operation is performed. In the pressure increasing operation, as shown in the flowchart of FIG. 8, a command is issued in step 801 to keep the shutoff valve 8 in the closed state, and in step 802, a command is issued to keep the pressurizing valve 9 in the open state. Command to keep the pressure pump 10 in the ON state. If ZdP ≧ 0 is not satisfied in step 604, the flow advances to step 607 to perform a pressure reducing operation. As shown in FIG. 9, the pressure reducing operation is commanded to keep the shut-off valve 8 open at step 901, commanded to keep the pressurizing valve 9 closed at step 902, and added at step 903. A command is issued to keep the pressure pump 10 in the OFF state.

If it is determined in step 601 that the brake control flag Ycntl is not set, step 608 is executed.
To release the pressure in the wheel cylinder 6. In this release operation, as shown in the flowchart of FIG. 10, a command is issued in step 1001 to keep the shutoff valve 8 open, and in step 1002, the pressure
Is kept in a closed state, and in step 1003, a command is issued to keep the pressure pump 10 in an OFF state.

As described above, according to the vehicle automatic braking control device of the first embodiment of the present invention, the brake pedal 1 is released without operating the brake pedal 1 when the vehicle is running. At times, the target deceleration ZAtarget is determined at predetermined time intervals based on the inter-vehicle distance ZLdis to the preceding vehicle, the relative speed ZVr, and the acceleration / deceleration ZApre of the preceding vehicle.
t is calculated, and the deceleration ZAs is calculated as the target deceleration ZAta.
Since the target brake pressure ZPtarget (n) calculated by the deceleration feedback processing to set rget is instructed to each actuator of the braking system, the vehicle is safely decelerated. When the vehicle comes to a stop after deceleration, the target brake pressure ZPtarget calculated by the speed feedback process to set the vehicle speed ZVs to zero.
Since t (n) is instructed to the braking system, the stopped state of the vehicle is maintained. Here, since the initial value of the target brake pressure ZPtarget (n) by the speed feedback processing is set to be the final value of the target brake pressure ZPtarget (n) by the deceleration feedback processing, the vehicle shifts from the running state to the stopped state. In this case, the target brake pressure ZPtarget does not change, and the vehicle can be stopped smoothly without applying an impact to the vehicle body, so that a good riding feeling can be obtained.

In the above description, the pressure control for braking is explained by the pressure control of the wheel cylinder 6. However, a variable pressure chamber in which the internal pressure changes by a control valve operated by operating a brake pedal or a command from a control device, a constant pressure chamber, Applicable even to a device that controls the braking force by using a master bag with two chambers and changing the pressure in the variable pressure chamber with a control valve to create a pressure difference between the variable pressure chamber and the constant pressure chamber It is. Further, using a master bag having three chambers of a variable pressure chamber in which the internal pressure changes by operation of the brake pedal, an auxiliary variable pressure chamber in which the internal pressure changes by a control valve operated by a command of the control device, and a constant pressure chamber, The present invention can also be applied to a device that controls the braking force by changing the pressure in the auxiliary variable pressure chamber by the control valve to generate a pressure difference between the auxiliary pressure changing chamber and the constant pressure chamber.

In the above description, in step 402, the operation of the brake pedal 1 is determined based on the state of the brake switch 2 in step 301, but the pressure of the master cylinder 4 is detected as shown by the dotted line in FIG. A master cylinder pressure sensor 24 is provided, and the operation of the brake pedal can be determined based on the output of the master cylinder pressure sensor 24. Further, the brake control flag Ycnt
When rl is in the set state, the pressure of the wheel cylinder 6 is compared with the pressure of the master cylinder 4 and the master cylinder 4
It can be determined that the brake pedal has been operated when the pressure is high. With this configuration, when the brake pedal 1 is depressed and the shut-off valve 8 is opened,
A reaction to the brake pedal 1 caused by a higher wheel cylinder pressure can be prevented.

In step 502, in the above description, the stopped state is determined based on whether or not the own vehicle speed ZVs is ≠ 0. However, when the own vehicle speed is smaller than a predetermined value, it can be determined that the vehicle is stopped. In step 501, the target deceleration ZTarget is calculated based on the following distance ZLdis, the relative speed ZVr, and the acceleration / deceleration ZApre of the preceding vehicle.
It is also possible to calculate based on Ldis and the relative speed ZVr. Further, in this embodiment, control for braking has been described. By combining the above calculation result with an electronically controlled throttle valve, both acceleration and deceleration control can be performed. The present invention is not limited to this and can be applied to other power sources such as electric vehicles.

Embodiment 2 FIG. FIG. 11 and FIG. 12 are a flowchart and an operation explanatory diagram illustrating a flow of an operation of the vehicle automatic braking control device according to the second embodiment of the present invention.
In this embodiment, the target value calculation processing shown in FIG. 5 of the first embodiment is changed to the processing content of FIG. 11, and the changed point is that processing of step 1115 in FIG. 11 is added to FIG. Things. Accordingly, here, the added processing content will be mainly described, and the flow up to step 1115 will be supplementarily described.

In this embodiment, as in FIG. 5 of the first embodiment, the final value of the target brake pressure in the deceleration feedback processing is set in step 1109 as the initial value of the target brake pressure in the speed feedback processing. Then, the target speed is set to 0, and the speed deviation from the own vehicle speed ZVs is calculated. In step 1111, the speed deviation ZdVsum (n−1) is added to the integral value ZdVsum (n−1) of the previous speed deviation.
In step 1112, the current target brake pressure ZPtarget (n) is calculated. In step 1113, the flag Ycntl_A is cleared.
In step 4, the integral value ZdAsum (n) of the deceleration deviation is cleared. Then, step 1 which is a feature of this embodiment is described.
Go to 115 and target brake pressure ZPtargrt (n)
Is limited to a value equal to or greater than a predetermined value of XPlimit. In this process, as shown in FIG. 12, the target brake pressure ZPtarget (n) at the time when the vehicle speed becomes 0 and it is determined that the vehicle has stopped is X.
If it is less than the value of Plimit, the target brake pressure ZPta
Until rget (n) reaches the value of XPlimit,
The brake pressure is set to XdPli every predetermined time XTlimit.
It is gradually increased by mit.

By setting the value of XPlimit as a brake pressure necessary for maintaining the stopped state,
Even when the vehicle is stopped in a state where the deceleration is low and the brake pressure is low, a stable stop state can be maintained. Also,
XPlimit is data that is stored in the ROM 18 in advance. However, it is also possible to know the road gradient by comparing it with a tilt sensor or a navigation road database, and change and select the value of XPlimit according to the gradient.

Embodiment 3 FIG. FIG. 13 is a flowchart illustrating an operation flow of the vehicle automatic braking control device according to the third embodiment of the present invention.
The target value calculation process shown in FIG. 5 is changed to the process content shown in FIG. 13, and is called from step 204 in FIG. 2 and executed as in the case of FIG. In step 1301, the inter-vehicle distance ZLdis and the relative speed ZV
function f with r and acceleration / deceleration ZApre of the preceding vehicle as arguments
Calculates the target deceleration ZTarget by 1 and RAM
20. This function f1 is the same as that described in the first embodiment. In step 1302, the own vehicle speed Z
It is determined whether or not Vs is ≠ 0. If ZVs ≠ 0, the process proceeds to step 1303, where Xtimer1 is substituted into the stopped state continuation timer Ztimer1. If ZVs ≠ 0 in step 1302, the process proceeds to step 1304. In step 1304, it is determined whether the stopped state continuation timer is Ztimer1 ≠ 0. If Ztimer1 ≠ 0, step 1305 is performed.
Proceed to.

In step 1305, the stopped state continuation timer Ztimer1 is counted down by ΔT. In step 1306, the target deceleration ZTarget and the deceleration Z
The deceleration deviation ZdA from As is calculated and stored in the RAM 20. In step 1307, the deceleration deviation ZdA is added to the integral value ZdAsum (n-1) of the previous deceleration deviation, and the result is stored as the integral value ZdAsum (n) of the current deceleration deviation. In step 1308, the target brake pressure is calculated according to the equation (6) described in the first embodiment. In step 1309, a flag Ycntl_A is set to indicate that the current time is the deceleration feedback processing. In step 1310, the integral value ZdVsum (n) of the speed deviation used in the speed feedback process is cleared to zero.

At step 1304, it is determined whether or not the stop state continuation timer is Ztimer1 ≠ 0.
If er1 ≠ 0, the process proceeds to step 1311, where it is determined whether the flag Ycntl_A was set in the previous time in the deceleration feedback process. If the flag is not set, the process jumps to step 1313; Proceed to. In step 1312, the previous target brake pressure ZPtarget (n-1), that is, the final value of the target brake pressure in the deceleration feedback processing is set as the initial value ZPinit of the target brake pressure in the speed feedback processing.

In step 1313, a speed deviation ZdV between the target speed 0 and the host vehicle speed ZVs is calculated and stored in the RAM 20. In step 1314, the speed deviation ZdV is added to the integral value ZdVsum (n-1) of the previous speed deviation,
Stored as ZdVsum (n). Step 1315
Then, the target brake pressure is calculated according to the equation (7) described in the first embodiment. In step 1316, to indicate that this time was not the deceleration feedback processing, Ycnt
Clear the rl_A flag. Therefore, step 131
2 is passed only when the deceleration feedback processing is switched to the speed feedback processing by the operation of the Ycntl_A flag. Step 1317
Then, the integral value ZdAsum (n) of the deceleration deviation used in the deceleration feedback processing is cleared.

As described above, according to the automatic braking control device for a vehicle of this embodiment, even if the vehicle speed based on the output of the vehicle speed sensor 12 becomes 0, it is determined that the vehicle is stopped after a predetermined time Xtimer1 has elapsed. Since the determination is made and the speed feedback process is started, even if the vehicle speed sensor erroneously determines that the vehicle is in a stopped state during traveling at a low speed, a predetermined time Xtimer is required.
After 1 the vehicle is stopped and the braking force can be switched after the stop, so that the control can be switched smoothly, and the vehicle can be stopped smoothly without applying any impact to the vehicle body, as in the case of the first embodiment. A good ride feeling can be obtained.

[0040]

As described above, according to the automatic braking control device for a vehicle of the present invention, when the brake pedal is released while the vehicle is running, the inter-vehicle distance and the relative distance to the preceding vehicle are determined at predetermined time intervals. A target deceleration based on the speed and the acceleration of the preceding vehicle is calculated, and the target brake pressure calculated by the deceleration feedback processing is set to the deceleration to the target deceleration, which is instructed to the braking control device, and the vehicle is stopped. In this case, the target brake pressure calculated by the speed feedback processing is set to be instructed to the brake control device so that the vehicle speed becomes zero, and the initial value of the target brake pressure obtained by the speed feedback processing is set to the target brake pressure obtained by the deceleration feedback processing. Since it was set to the final value,
At the time of running at low speed, a margin of a predetermined time was given to determine that the vehicle was stopped, so when there is an obstacle ahead,
The vehicle can be reliably decelerated or stopped, and when the vehicle shifts from the running state to the stopped state, the vehicle can be stopped smoothly without applying an impact to the vehicle body, and a good riding feeling can be obtained.

After the stoppage is determined, the braking force required for maintaining the stoppage is increased at a predetermined time rate, so that the stoppage can be reliably maintained even when the vehicle is stopped with a weak braking force or on a sloped road. You can do it.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a vehicle automatic braking control device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating a main routine of control of the vehicle automatic braking control device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing the contents of step 202 in FIG. 2;

FIG. 4 is a flowchart showing the contents of step 203 in FIG.

FIG. 5 is a flowchart showing the contents of step 204 in FIG. 2;

FIG. 6 is a flowchart showing the contents of step 205 in FIG. 2;

FIG. 7 is a flowchart showing the contents of step 605 in FIG.

FIG. 8 is a flowchart showing the contents of step 606 in FIG.

9 is a flowchart showing the contents of step 607 in FIG.

FIG. 10 is a flowchart showing the contents of step 608 in FIG. 6;

FIG. 11 is a flowchart illustrating the operation of the second embodiment of the present invention.

FIG. 12 is an explanatory diagram illustrating the operation of the second embodiment of the present invention.

FIG. 13 is a flowchart illustrating the operation of the third embodiment of the present invention.

[Explanation of symbols]

Reference Signs List 1 brake pedal, 2 brake switch, 3 booster, 4 master cylinder, 5 reservoir, 6 wheel cylinder, 7a brake pipe, 7b, 7c branch pipe, 8 shutoff valve, 9 pressurizing valve, 10 pressurizing pump, 11
Accelerator switch, 12 vehicle speed sensor, 13 wheel cylinder pressure sensor, 14 inter-vehicle distance sensor, 15 shift range detection switch, 16 operation switch, 17
Control device, 18 ROM, 19 CPU, 20 RA
M, 21 input interface, 22 output interface, 23 address path / data path, 24
Master cylinder pressure sensor.

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 3D046 BB02 BB18 EE01 HH02 HH05 HH07 HH16 HH20 HH22 HH26 HH37 JJ19 JJ21 LL05 LL23 LL37 LL43 5H180 AA01 CC14 LL01 LL04 LL09

Claims (3)

[Claims] An inter-vehicle distance detecting means for measuring a distance to an object in front; an own vehicle speed detecting means for measuring an own vehicle speed; an own vehicle acceleration / deceleration detecting means for measuring or calculating the own vehicle acceleration / deceleration; A relative speed detecting means for measuring or calculating a relative speed with respect to an object, a braking control means for controlling a braking force of the own vehicle, a control device for giving a braking command to the braking control means based on a signal from each of the detecting means, At least the device
A function for calculating a first braking force for decelerating or stopping the running vehicle, a function for calculating a second braking force for maintaining the stop, and a first braking force for determining whether the vehicle is stopped. Has a function of switching from the first braking force to the second braking force when the vehicle is determined to be in a stopped state and switched from the first braking force to the second braking force. An automatic braking control device for a vehicle, which is set as an initial value. 2. The automatic braking control device for a vehicle according to claim 1, wherein after the vehicle is stopped, the initial value of the second braking force is changed to a specific value or more at a predetermined time rate. 3. The vehicle according to claim 1, wherein after the vehicle speed detecting means detects that the vehicle is stopped, it is determined that the vehicle is stopped after a predetermined time has elapsed, and the first braking force is switched to the second braking force. Item 3. An automatic braking control device for a vehicle according to Item 2.