KR100254225B1 - Anti-lock brake system of a car - Google Patents

Abstract

PURPOSE: A slip index detecting method detects actual slip index of wheels by changing constant according to slip rate and variate of deceleration to provide braking control with responsibility. CONSTITUTION: A slip index detecting method comprises a step to calculate slip rate from the detected wheel speed dependingly on whether the braking force is generated on a driving car and determine whether the detected slip rate is lower than the critical value(S101, S102, S103), a step to set an arbitrary value detected through learning as a first constant if the slip rate is lower than the critical value(S104), a step to detect deceleration from the detected wheel speed and determine whether the absolute value of the deceleration is lower than the critical value to set up a second constant of the deceleration(S113, S111, S110) and a step to calculate the slip index from the detected slip rate, deceleration and the first and the second constant(S120). If the slip rate of the wheels and the absolute value of the detected deceleration are over the critical values, the first constant(Kp) is set to 1 and the second constant(Ki) to -0.15. If the slip rate of the wheels and the absolute value of the detected deceleration are under the critical values, Kp is set to 1 and Ki to -0.01. The slip index=Kp*the slip rate+Ki*the deceleration.

Description

Slip Index Detection Method for Vehicle Stall Control

The present invention relates to a braking device for an automobile, and more particularly, to a braking device for an automobile having an ABS (Anti-Lock Brake System) system. The braking device includes a brake pedal And to provide a reliability in braking control through a quick phase response.

Generally, when the car starts to be driven, the tone wheel 10 composed of a predetermined number, for example, 47 mountains, is rotated as shown in the accompanying figure 1 at the same time as the rotation of the road surface and the grounded wheels .

At this time, according to the rotation of the tone wheel 10, the wheel speed detector 20 outputs a predetermined pulse signal and applies the pulse signal to the controller 30. When the control unit 30 detects After analyzing the pulse signal per unit time to detect the wheel speed of the running vehicle (step 1), the slip ratio is calculated according to the set program data to detect the slip ratio required for the running control (step 2).

On the other hand, the control unit 30 computes the detected wheel speed according to the set program data, detects the wheel acceleration per unit time (Step 3), and then filters it through the low-pass filter (LPF) (Step 4).

Thereafter, the control unit 30 multiplies the slip rate of the wheel detected in the step 2 and the wheel acceleration filtered and applied in the step 4 by an arbitrary constant (K) to sum the added signals (step 5) (Step 6) and outputs a control signal for braking control (step 7).

As described above, in the slip index detecting method used in the conventional automobile, since the constant value which is multiplied with the wheel acceleration is fixed to a constant value irrespective of whether the acceleration is changed or not, the noise included in the wheel acceleration There is a problem that a normal slip index can not be detected, and a control signal for stopping control is not normally output due to detection of an abnormal slip index, so that a stable braking force and a steerability can not be secured.

SUMMARY OF THE INVENTION [0005] It is an object of the present invention to provide a vehicle stability control apparatus and a control method thereof, in which a slip index detection of a road surface and a slip wheel is changed in accordance with a depreciation rate and a slip rate, Quot ;, so that the stop control is provided to provide reliability and stability to the steering.

According to another aspect of the present invention, there is provided a method for controlling a slip ratio of a vehicle, the method comprising the steps of: calculating a slip ratio from a wheel speed detected in accordance with whether a braking force is generated in a motor vehicle; determining whether a slip ratio is below a threshold; Setting an arbitrary value detected through learning to a value of a first constant if the value is equal to or less than a threshold value; Determining a deceleration acceleration from the detected wheel speed to determine whether an absolute value of the deceleration acceleration is equal to or less than a set threshold value and setting a second constant value for the deceleration rate; 1 and a second constant to calculate a slip index.

FIG. 1 is a block diagram showing a configuration of a general wheel-speed detecting device in a car. FIG.

FIG. 2 is a flow chart of an embodiment for slip index detection in stop control in a vehicle of the present invention. FIG.

FIG. 3 is a flow chart for slip index detection in stop control used in a conventional automobile. FIG.

Hereinafter, a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As can be seen from FIG. 2, in the automobile running at a predetermined speed, the control means detects the speed of the wheel rotated by being grounded from the road surface (Step 101), and determines the speed of the detected wheel The slip ratio is calculated (step 102).

At this time, if a signal requesting the braking of the running vehicle is detected, it is determined whether the slip ratio of the wheel detected at the time when the braking demand is detected is less than a predetermined threshold value (step 103).

If the slip rate of the wheel is detected to be equal to or smaller than the preset threshold value in step 103, the control means sets a first constant value, Kp: 1, to an arbitrary value detected through learning (step 104).

On the other hand, the control means detects the depreciation rate which varies per unit time from the detected wheel speed (Step 113), and then determines whether the absolute value of the depreciation rate to be detected is equal to or smaller than a certain threshold value of the setting (Step 111).

If it is determined in step 111 that the absolute value of the depreciation speed is equal to or smaller than the set threshold value, the control unit sets the constant value to a second constant value Ki: -0.01 set to an arbitrary value detected through learning in step 104 .

If it is determined in step 103 that the slip rate of the wheel is equal to or less than the set threshold value and the absolute value of the detected depressed velocity is equal to or less than the set threshold value, the first constant value Kp: 1 , And sets the second constant value Ki to -0.01 (step 104).

If it is determined in step 103 that the slip rate of the wheel is equal to or greater than a preset threshold value and the absolute value of the detected depreciation speed is greater than or equal to a set threshold value, the first constant value Kp: 1 , And a second constant value Ki-0.15 (step 110).

If it is determined that the slip ratio detected in step 103 is equal to or greater than the set threshold value, the control unit executes step 111 to determine whether the absolute value of the depreciation speed is equal to or less than the threshold value and execute a predetermined routine therefor.

Then, the control means compares the constant, the first constant Kp, and the second constant Ki set through the slip rate detection in step 103 with the constant set by comparing the absolute value of the depression speed, the first constant KP, and the second constant The slip index is calculated through the following calculation of Ki to output a signal for braking control (step 120) (step 130).

Slip Index = Kp * Slip + Ki * Depreciation Rate.

The slip index detected as described above provides reliability in operation by controlling the steerability and the braking force through the stable slip index.

As described above, according to the present invention, since the slip index detected by the driver in order to generate the braking force is detected by varying the constant value according to the slip ratio and the change amount of the depreciation speed, Reliability is provided, and stable braking force generation provides stability in steering and running.

Claims (5)

A method for detecting a slip index during braking, the method comprising the steps of: calculating a slip ratio from a wheel speed detected according to whether a braking force is generated in a motor vehicle in operation; determining whether a slip ratio detected is equal to or less than a threshold value; Setting an arbitrary value detected through learning to a value of a first constant if the value is less than a predetermined value; Detecting a depreciation rate from the detected wheel speed to determine whether an absolute value of the depreciation rate is less than or equal to a preset threshold value and setting a value of a second value of an arbitrary value with respect to the depreciation rate; Calculating a slip index by calculating values of first and second constants of the depression rate and the arbitrary value; and calculating a slip index by calculating the first and second constants. 2. The method of claim 1, wherein if the slip rate of the wheel is equal to or greater than a predetermined threshold value and the absolute value of the detected depreciation speed is equal to or greater than a predetermined threshold value, And the second constant value Ki is set to -0,15. 2. The method according to claim 1, wherein when the slip rate of the wheel is equal to or less than a set threshold value and the absolute value of the detected depressing rate is equal to or less than a set threshold value, And the second constant value Ki is set to -0.01. The slip index detecting method according to claim 1, wherein the slip index is calculated as a first constant value, a slip ratio, a second constant value, and a depreciation rate. The method according to claim 1, wherein the first constant value Kp is set to 1, and the second constant value Ki is set to -0.01 to -0.15 according to a slip rate and a depreciation threshold value. Slip Index Detection Method.