Load feedback braking force distribution system and distribution method based on I curve

Abstract

The invention discloses a load feedback braking force distribution system and a distribution method based on an I curve, and mainly relates to the field of vehicle engineering technology; the system comprises: a first load sensor, a second load sensor, a third load sensor, and a fourth load sensor; a DC measuring amplifier; a first brake wheel cylinder, a first pressure sensor, a second brake wheel cylinder, a second pressure sensor, a third brake wheel cylinder, a third pressure sensor, a fourth brake wheel cylinder, and a fourth pressure sensor; an A / D converter, a D / A converter, an ECU, a brake pedal position sensor, and a hydraulic pump motor; a first controllable proportional solenoid valve, a second controllable proportional solenoid valve, a third controllable proportional solenoid valve, and a fourth controllable proportional solenoid valve; the invention determines the braking force ratio of front and rear brakes through feedback control calculation, so that the braking force distribution of front and rear brakes satisfies an ideal I curve, can ensure braking stability, and improve braking efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle engineering, and in particular to a load feedback braking force distribution system and a distribution method based on an I curve. Background Art

[0002] Automobile braking performance is an important evaluation index of automobile active safety. The distribution ratio of the front and rear brake forces will affect the locking order of the front and rear wheels during braking, thereby affecting the directional stability and the degree of utilization of adhesion conditions during braking. At present, the existing front and rear brake braking force distribution is achieved by using a braking force adjustment device such as a proportional valve or a load proportional valve. According to factors such as braking intensity and load, the ratio of the front and rear brake forces is changed to make it close to the ideal braking force distribution curve and meet the requirements of braking regulations. The selection of the turning point of the adjustment device is particularly important for braking stability. If there is an unstable interval, there will be safety hazards. Generally, the turning point is selected lower than the I curve, but this will reduce the braking efficiency. Summary of the invention

[0003] The purpose of the present invention is to solve the problems existing in the prior art. Through load feedback control, a load feedback braking force distribution system and distribution method based on the I curve are provided, which can monitor the distribution of the vertical load on the left front axle, the right front axle, the left rear axle and the right rear axle in real time, and determine the braking force ratio of the front and rear brakes through feedback control calculation, so that the braking force distribution of the front and rear brakes meets the ideal I curve, which can ensure braking stability and improve braking efficiency.

[0004] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0005] The load feedback braking force distribution system based on I curve includes:

[0006] A first load sensor installed on the left front axle, a second load sensor installed on the right front axle, a third load sensor installed on the left rear axle, and a fourth load sensor installed on the right rear axle;

[0007] DC measuring amplifier;

[0008] A first wheel-brake cylinder installed on the left front wheel and a first pressure sensor for sensing the pressure of the first wheel-brake cylinder, a second wheel-brake cylinder installed on the right front wheel and a second pressure sensor for sensing the pressure of the second wheel-brake cylinder, a third wheel-brake cylinder installed on the left rear wheel and a third pressure sensor for sensing the pressure of the third wheel-brake cylinder, a fourth wheel-brake cylinder installed on the right rear wheel and a fourth pressure sensor for sensing the pressure of the fourth wheel-brake cylinder;

[0009] A / D converter, D / A converter, ECU, brake pedal position sensor, hydraulic pump motor;

[0010] a first controllable proportional solenoid valve for regulating the brake fluid pressure in the first brake wheel cylinder, a second controllable proportional solenoid valve for regulating the brake fluid pressure in the second brake wheel cylinder, a third controllable proportional solenoid valve for regulating the brake fluid pressure in the third brake wheel cylinder, and a fourth controllable proportional solenoid valve for regulating the brake fluid pressure in the fourth brake wheel cylinder;

[0011] The first load sensor, the second load sensor, the third load sensor, and the fourth load sensor are all connected to the input end of the DC measuring amplifier, and the output ends of the DC measuring amplifier, the first pressure sensor, the second pressure sensor, the third pressure sensor, the fourth pressure sensor, and the brake pedal position sensor are all connected to the input end of the ECU through the A / D converter, and the first controllable proportional solenoid valve, the second controllable proportional solenoid valve, the third controllable proportional solenoid valve, the fourth controllable proportional solenoid valve, and the hydraulic pump motor are all connected to the output end of the ECU through the D / A converter.

[0012] Preferably, the load feedback braking force distribution system based on the I curve includes a first wheel speed sensor installed on the left front wheel, a second wheel speed sensor installed on the right front wheel, a third wheel speed sensor installed on the left rear wheel, and a fourth wheel speed sensor installed on the right rear wheel. The output ends of the first wheel speed sensor, the second wheel speed sensor, the third wheel speed sensor, and the fourth wheel speed sensor are all connected to the input end of the ECU through an A / D converter, and the ECU is provided with an ABS system.

[0013] Preferably, the load feedback braking force distribution system based on the I curve includes a vehicle-mounted battery and a DC regulated power supply. The vehicle-mounted battery supplies power to the ECU, the hydraulic pump motor, and the DC regulated power supply. The DC regulated power supply supplies power to the first load sensor, the second load sensor, the third load sensor, the fourth load sensor, and the DC measuring amplifier.

[0014] A method for distributing a load feedback braking force distribution system based on an I curve comprises the following steps:

[0015] Step 1: monitor the vertical load on the left front axle in real time through the first load sensor and send the monitoring result to the DC measuring amplifier, monitor the vertical load on the right front axle in real time through the second load sensor and send the monitoring result to the DC measuring amplifier; monitor the vertical load on the left rear axle in real time through the third load sensor and send the monitoring result to the DC measuring amplifier; monitor the vertical load on the right rear axle in real time through the fourth load sensor and send the monitoring result to the DC measuring amplifier;

[0016] Step 2: The DC measuring amplifier converts the monitoring information transmitted by the first load sensor, the second load sensor, the third load sensor, and the fourth load sensor through an A / D converter and sends it to the ECU;

[0017] Step 3: ECU follows the formula Determine the braking force distribution ratio, where F u1 is the value of the left front wheel braking force, F u2 is the value of the right rear wheel braking force, F u3 is the value of the right front wheel braking force, F u4 is the value of the left rear wheel braking force, G1 is the vertical load on the left front axle monitored in real time by the first load sensor, G2 is the vertical load on the right rear axle monitored in real time by the fourth load sensor, G3 is the vertical load on the right front axle monitored in real time by the second load sensor, and G4 is the vertical load on the left rear axle monitored in real time by the third load sensor;

[0018] Step 4: The ECU distributes the braking force through the first controllable proportional solenoid valve, the second controllable proportional solenoid valve, the third controllable proportional solenoid valve, and the fourth controllable proportional solenoid valve according to the braking force distribution ratio obtained in step 3 and the pressure value of the first brake wheel cylinder sensed by the first pressure sensor, the pressure value of the second brake wheel cylinder sensed by the second pressure sensor, the pressure value of the third brake wheel cylinder sensed by the third pressure sensor, and the pressure value of the fourth brake wheel cylinder sensed by the fourth pressure sensor.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] The first load sensor, the second load sensor, the third load sensor and the fourth load sensor of the present invention are used for real-time monitoring of the distribution of the vertical load on the axle; the ECU distributes the braking force by controlling the first controllable proportional solenoid valve, the second controllable proportional solenoid valve, the third controllable proportional solenoid valve and the fourth controllable proportional solenoid valve according to the feedback signals of the first load sensor, the second load sensor, the third load sensor and the fourth load sensor; the brake pedal position sensor is used for sensing the position of the brake pedal and providing a trigger and a braking force size signal for the ECU to distribute the braking force; through load feedback control, the distribution of the vertical load on the left front axle, the right front axle, the left rear axle and the right rear axle is monitored in real time, and the braking force ratio of the front and rear brakes is determined through feedback control calculation, so that the braking force distribution of the front and rear brakes meets the ideal I curve, which can ensure braking stability and improve braking efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Attached Figure 1 It is a block diagram of the left front wheel and right rear wheel braking force distribution system;

[0022] Attached Figure 2It is a block diagram of the right front wheel and left rear wheel braking force distribution system;

[0023] Attached Figure 3 It is the control program flow chart in ECU.

[0024] Numbers in the accompanying drawings: 1, first load sensor; 2, second load sensor; 3, third load sensor; 4, fourth load sensor; 5, DC measuring amplifier; 6, first brake wheel cylinder; 7, first pressure sensor; 8, second brake wheel cylinder; 9, second pressure sensor; 10, third brake wheel cylinder; 11, third pressure sensor; 12, fourth brake wheel cylinder; 13, fourth pressure sensor; 14, ECU; 15, brake pedal position sensor; 16, hydraulic pump motor; 17, first controllable proportional solenoid valve; 18, second controllable proportional solenoid valve; 19, first wheel speed sensor; 20, second wheel speed sensor; 21, third wheel speed sensor; 22, fourth wheel speed sensor; 23, on-board battery; 24, DC regulated power supply; 25, brake pedal; 26, brake master cylinder; 27, reservoir; 28, hydraulic pump; 29, third controllable proportional solenoid valve; 30, fourth controllable proportional solenoid valve. DETAILED DESCRIPTION

[0025] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the application equally.

[0026] Example: As shown in the attached Figure 1-3 As shown, the present invention is a load feedback braking force distribution system based on the I curve, comprising:

[0027] A first load sensor 1 installed on the left front axle, a second load sensor 2 installed on the right front axle, a third load sensor 3 installed on the left rear axle, and a fourth load sensor 4 installed on the right rear axle. The first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4 are used to monitor the distribution of the vertical load on the axle in real time. The first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4 can all be weighing sensors;

[0028] A DC measuring amplifier 5, which uses a bridge to amplify the load signals of the first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4;

[0029] A first wheel-brake cylinder 6 installed on the left front wheel and a first pressure sensor 7 for sensing the pressure of the first wheel-brake cylinder 6, a second wheel-brake cylinder 8 installed on the right front wheel and a second pressure sensor 9 for sensing the pressure of the second wheel-brake cylinder 8, a third wheel-brake cylinder 10 installed on the left rear wheel and a third pressure sensor 11 for sensing the pressure of the third wheel-brake cylinder 10, a fourth wheel-brake cylinder 12 installed on the right rear wheel and a fourth pressure sensor 13 for sensing the pressure of the fourth wheel-brake cylinder 12;

[0030] A / D converter, D / A converter, ECU14, brake pedal position sensor 15, hydraulic pump motor 16, ECU14 controls the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, the fourth controllable proportional solenoid valve 30 according to the feedback signals of the first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4 to distribute the braking force; the brake pedal position sensor 15 senses the position of the brake pedal 25, and provides a trigger and a braking force size signal for the braking force distribution ECU14;

[0031] a first controllable proportional solenoid valve 17 for regulating the brake fluid pressure in the first brake wheel cylinder 6, a second controllable proportional solenoid valve 18 for regulating the brake fluid pressure in the second brake wheel cylinder 8, a third controllable proportional solenoid valve 29 for regulating the brake fluid pressure in the third brake wheel cylinder 10, and a fourth controllable proportional solenoid valve 30 for regulating the brake fluid pressure in the fourth brake wheel cylinder 12. The first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30 can output different brake fluid pressures according to different input currents. When the input current is changed, the output pressure of the solenoid valve can be changed, so as to control the brake fluid pressures in the first brake wheel cylinder 6, the second brake wheel cylinder 8, the third brake wheel cylinder 10, and the fourth brake wheel cylinder 12;

[0032] The first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4 are all connected to the input end of the DC measuring amplifier 5, and the output ends of the DC measuring amplifier 5, the first pressure sensor 7, the second pressure sensor 9, the third pressure sensor 11, the fourth pressure sensor 13, and the brake pedal position sensor 15 are all connected to the input end of the ECU 14 through an A / D converter, and the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, the fourth controllable proportional solenoid valve 30, and the hydraulic pump motor 16 are all connected to the output end of the ECU 14 through a D / A converter.

[0033] When the brake pedal 25 is stepped on, the brake pedal position sensor 15 transmits the brake pedal 25 position electrical signal to the ECU 14, triggering the ECU 14 to start the hydraulic pump motor 16. The hydraulic pump motor 16 starts, so that the hydraulic pump 28 works, and the brake fluid is sucked from the reservoir 27 to the master brake cylinder 26; the brake fluid in the master brake cylinder 26 is sent to the first brake wheel cylinder 6 through the first controllable proportional solenoid valve 17, to the second brake wheel cylinder 8 through the second controllable proportional solenoid valve 18, to the third brake wheel cylinder 10 through the third controllable proportional solenoid valve 29, and to the fourth brake wheel cylinder 12 through the fourth controllable proportional solenoid valve 30, so that the brakes on each wheel work and the vehicle braking process is completed. Through load feedback control, the distribution of vertical loads on the left front axle, the right front axle, the left rear axle, and the right rear axle can be monitored in real time. Through feedback control calculation, the braking force ratio of the front and rear brakes is determined, so that the braking force distribution of each front and rear brake meets the ideal I curve, which can ensure braking stability and improve braking efficiency.

[0034] Preferably, the load feedback braking force distribution system based on the I curve includes a first wheel speed sensor 19 installed on the left front wheel, a second wheel speed sensor 20 installed on the right front wheel, a third wheel speed sensor 21 installed on the left rear wheel, and a fourth wheel speed sensor 22 installed on the right rear wheel. The output ends of the first wheel speed sensor 19, the second wheel speed sensor 20, the third wheel speed sensor 21, and the fourth wheel speed sensor 22 are all connected to the input end of the ECU 14 through an A / D converter. The ECU 14 is provided with an ABS system. The first wheel speed sensor 19, the second wheel speed sensor 20, the third wheel speed sensor 21, and the fourth wheel speed sensor 22 are used to sense the rotation speed of the corresponding wheels and provide feedback signals for the ABS to prevent safety accidents during braking.

[0035] Preferably, in order to provide a stable power supply, the load feedback braking force distribution system based on the I curve includes a vehicle-mounted battery 23 and a DC regulated power supply 24. The vehicle-mounted battery 23 supplies power to the ECU 14, the hydraulic pump motor 16, and the DC regulated power supply 24. The DC regulated power supply 24 supplies power to the first load sensor 1, the second load sensor 2, the third load sensor 3, the fourth load sensor 4, and the DC measuring amplifier 5.

[0036] The control program flow in the ECU is described as follows:

[0037] 1. The brake pedal position sensor 15 senses the position of the brake pedal 25 and provides a trigger and a braking force magnitude signal to the braking force distribution ECU 14;

[0038] 2. The front and rear wheels (front wheels include the left front wheel and the right front wheel, and rear wheels include the left rear wheel and the right rear wheel) are locked and slipped at the same time, resulting in poor utilization of adhesion conditions, longer braking distance, and loss of steering ability of the vehicle, which poses a safety hazard. In the ECU14 load feedback braking force distribution electronic control unit, an ABS (anti-lock braking) subroutine is added, and the ABS (anti-lock braking) subroutine is triggered when the wheel speed is zero;

[0039] 3. When the wheel speed is not zero, only the load feedback braking force distribution subroutine in ECU14 runs, outputting the front (rear) braking force signal to the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30.

[0040] 4. When the wheel speed is zero, the load feedback braking force distribution subroutine and the ABS (anti-lock braking) subroutine run simultaneously, outputting the front (rear) braking force signal to the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30;

[0041] 5. The first wheel speed sensor 19, the second wheel speed sensor 20, the third wheel speed sensor 21, and the fourth wheel speed sensor 22 are used to sense the rotation speed of the corresponding wheels, and the ECU calculates the slip rate of the front and rear wheels in real time, and the ABS (anti-lock braking) subroutine uses the peak adhesion coefficient Shorten braking distance and ensure vehicle safety;

[0042] 6. The load feedback braking force distribution subroutine mainly compares and judges the ratio of the front (rear) wheel cylinder pressure signal and the ratio of the front (rear) axle load signal;

[0043] 7. When the ratio of the front and rear wheel cylinder pressure signals is consistent with the ratio of the front and rear axle load signals, the ratio of the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30 remains unchanged.

[0044] 8. When the ratio of the front and rear wheel cylinder pressure signals is inconsistent with the ratio of the front and rear axle load signals, adjust the ratio of the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30.

[0045] A method for distributing a load feedback braking force distribution system based on an I curve comprises the following steps:

[0046] Step 1: monitor the vertical load on the left front axle in real time through the first load sensor 1 and send the monitoring result to the DC measuring amplifier 5; monitor the vertical load on the right front axle in real time through the second load sensor 2 and send the monitoring result to the DC measuring amplifier 5; monitor the vertical load on the left rear axle in real time through the third load sensor 3 and send the monitoring result to the DC measuring amplifier 5; monitor the vertical load on the right rear axle in real time through the fourth load sensor 4 and send the monitoring result to the DC measuring amplifier 5;

[0047] Step 2: The DC measuring amplifier 5 converts the monitoring information transmitted by the first load sensor 1, the second load sensor 2, the third load sensor 3, and the fourth load sensor 4 through an A / D converter and sends it to the ECU 14;

[0048] Step 3: ECU14 follows the formula Determine the braking force distribution ratio, where F u1 is the value of the left front wheel braking force, F u2 is the value of the right rear wheel braking force, F u3 is the value of the right front wheel braking force, F u4 is the value of the left rear wheel braking force, G1 is the vertical load on the left front axle monitored in real time by the first load sensor 1, G2 is the vertical load on the right rear axle monitored in real time by the fourth load sensor 4, G3 is the vertical load on the right front axle monitored in real time by the second load sensor 2, and G4 is the vertical load on the left rear axle monitored in real time by the third load sensor 3;

[0049] Step 4: ECU14 distributes the braking force by controlling the first controllable proportional solenoid valve 17, the second controllable proportional solenoid valve 18, the third controllable proportional solenoid valve 29, and the fourth controllable proportional solenoid valve 30 according to the braking force distribution ratio obtained in step 3 and the pressure value of the first brake wheel cylinder 6 sensed by the first pressure sensor 7, the pressure value of the second brake wheel cylinder 8 sensed by the second pressure sensor 9, the pressure value of the third brake wheel cylinder 10 sensed by the third pressure sensor 11, and the pressure value of the fourth brake wheel cylinder 12 sensed by the fourth pressure sensor 13.

Claims

1. A load feedback braking force distribution system based on I curve, characterized in that: include: A first load sensor (1) installed on the left front axle, a second load sensor (2) installed on the right front axle, a third load sensor (3) installed on the left rear axle, and a fourth load sensor (4) installed on the right rear axle; DC measuring amplifier (5); A first brake wheel cylinder (6) installed on the left front wheel and a first pressure sensor (7) for sensing the pressure of the first brake wheel cylinder (6), a second brake wheel cylinder (8) installed on the right front wheel and a second pressure sensor (9) for sensing the pressure of the second brake wheel cylinder (8), a third brake wheel cylinder (10) installed on the left rear wheel and a third pressure sensor (11) for sensing the pressure of the third brake wheel cylinder (10), a fourth brake wheel cylinder (12) installed on the right rear wheel and a fourth pressure sensor (13) for sensing the pressure of the fourth brake wheel cylinder (12); A / D converter, D / A converter, ECU (14), brake pedal position sensor (15), hydraulic pump motor (16); A first controllable proportional solenoid valve (17) for regulating the brake fluid pressure in the first brake wheel cylinder (6), a second controllable proportional solenoid valve (18) for regulating the brake fluid pressure in the second brake wheel cylinder (8), a third controllable proportional solenoid valve (29) for regulating the brake fluid pressure in the third brake wheel cylinder (10), and a fourth controllable proportional solenoid valve (30) for regulating the brake fluid pressure in the fourth brake wheel cylinder (12); The first load sensor (1), the second load sensor (2), the third load sensor (3), and the fourth load sensor (4) are all connected to the input end of a DC measuring amplifier (5); the output ends of the DC measuring amplifier (5), the first pressure sensor (7), the second pressure sensor (9), the third pressure sensor (11), the fourth pressure sensor (13), and the brake pedal position sensor (15) are all connected to the input end of an ECU (14) via an A / D converter; and the first controllable proportional solenoid valve (17), the second controllable proportional solenoid valve (18), the third controllable proportional solenoid valve (29), the fourth controllable proportional solenoid valve (30), and the hydraulic pump motor (16) are all connected to the output end of the ECU (14) via a D / A converter.

2. The load feedback braking force distribution system based on I curve according to claim 1, characterized in that: The load feedback braking force distribution system based on the I curve comprises a first wheel speed sensor (19) installed on the left front wheel, a second wheel speed sensor (20) installed on the right front wheel, a third wheel speed sensor (21) installed on the left rear wheel, and a fourth wheel speed sensor (22) installed on the right rear wheel, wherein the output ends of the first wheel speed sensor (19), the second wheel speed sensor (20), the third wheel speed sensor (21), and the fourth wheel speed sensor (22) are all connected to the input end of an ECU (14) through an A / D converter, and an ABS system is provided in the ECU (14).

3. The load feedback braking force distribution system based on I curve according to claim 1, characterized in that: The load feedback braking force distribution system based on the I curve comprises an on-board battery (23) and a DC regulated power supply (24); the on-board battery (23) supplies power to an ECU (14), a hydraulic pump motor (16), and a DC regulated power supply (24); and the DC regulated power supply (24) supplies power to a first load sensor (1), a second load sensor (2), a third load sensor (3), a fourth load sensor (4), and a DC measuring amplifier (5).

4. A method for distributing a load feedback braking force distribution system based on an I curve according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step 1: The vertical load on the left front axle is monitored in real time by the first load sensor (1) and the monitoring result is sent to the DC measuring amplifier (5); the vertical load on the right front axle is monitored in real time by the second load sensor (2) and the monitoring result is sent to the DC measuring amplifier (5); the vertical load on the left rear axle is monitored in real time by the third load sensor (3) and the monitoring result is sent to the DC measuring amplifier (5); the vertical load on the right rear axle is monitored in real time by the fourth load sensor (4) and the monitoring result is sent to the DC measuring amplifier (5); Step 2: The DC measuring amplifier (5) converts the monitoring information transmitted by the first load sensor (1), the second load sensor (2), the third load sensor (3), and the fourth load sensor (4) through an A / D converter and sends the converted information to the ECU (14); Step 3: ECU (14) according to the formula Determine the braking force distribution ratio, where F u1 is the value of the left front wheel braking force, F u2 is the value of the right rear wheel braking force, F u3 is the value of the right front wheel braking force, F u4 is the value of the braking force of the left rear wheel, G1 is the vertical load on the left front axle monitored in real time by the first load sensor (1), G2 is the vertical load on the right rear axle monitored in real time by the fourth load sensor (4), G3 is the vertical load on the right front axle monitored in real time by the second load sensor (2), and G4 is the vertical load on the left rear axle monitored in real time by the third load sensor (3); Step 4: The ECU (14) distributes the braking force by controlling the first controllable proportional solenoid valve (17), the second controllable proportional solenoid valve (18), the third controllable proportional solenoid valve (29), and the fourth controllable proportional solenoid valve (30) according to the braking force distribution ratio obtained in step 3 and the pressure value of the first brake wheel cylinder (6) sensed by the first pressure sensor (7), the pressure value of the second brake wheel cylinder (8) sensed by the second pressure sensor (9), the pressure value of the third brake wheel cylinder (10) sensed by the third pressure sensor (11), and the pressure value of the fourth brake wheel cylinder (12) sensed by the fourth pressure sensor (13).

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