CONTROL METHOD FOR AUTOMATIC HOLDING, A VEHICLE'S BRAKE SYSTEM AND A BRAKE CONTROL MODULE THEREOF

1 . A control method for automatic holding applied to a brake system of a vehicle with two brake control modules, wherein the vehicle further comprises a drive motor, and a drive motor controller for controlling the drive motor to provide a drive torque, the brake system further comprises electromechanical brakes controlled by the brake control modules to provide braking force to each wheel, the control method comprising:

after the vehicle transitions from moving to stationary,

a) controlling the electromechanical brakes to continuously provide a brake torque, wherein the brake torque is a sum of an effective brake torque and a margin brake torque; and

b) continuously outputting a drive-off signal to the drive motor controller to control the drive motor not to provide drive torque;

until a driver requested drive torque is continuously increased to a critical torque which is close to the effective brake torque.

2 . The control method according to claim 1 , the control method further comprising: when the vehicle is transitioning from moving to stationary,

a) estimating a slope value of a road slope; and

b) estimating the effective brake torque at least based on the slope value.

3 . The control method according to claim 2 , wherein estimating the slope value further comprises:

estimating the slope value based on one or more of:

i) acceleration sensor information of the two brake control modules;

ii) a received inclination sensor signal;

iii) a received global positioning system signal and/or topographical information;

iv) a received wheel speed information of the vehicle;

v) inertial sensor information of the two brake control modules; and

vi) torsional load sensor.

4 . The control method according to claim 3 , the control method further comprising:

when a plurality of slope values are estimated by a plurality of methods, determining a confidence of the road slope based on similarity among the plurality of slope values.

5 . The control method according to claim 4 , the control method further comprising: determining the critical torque based on the confidence of the road slope; wherein the higher the confidence of the road slope is, the more the critical torque is in proximity to the effective brake torque.

6 . The control method according to claim 2 , wherein estimating the effective brake torque further comprises:

estimating the effective brake torque based on a mass of the vehicle.

7 . The control method according to claim 6 , the control method further comprising at least one of:

i) estimating the mass of the vehicle according to driving data; and

ii) obtaining the mass of the vehicle from the suspension system.

8 . The control method according to claim 1 , the control method further comprising:

when the vehicle is transitioning from moving to stationary,

a) obtaining a request brake torque from a brake pedal to stop the vehicle; and

b) estimating the effective brake torque based on the requested brake torque.

9 . The control method according to claim 1 , the control method further comprising:

determining the margin brake torque based on a preset fixed value.

10 . The control method according to claim 1 , the control method further comprising:

determining the margin brake torque based on a slope value of a road slope and/or a mass of the vehicle, wherein the greater the slope value and/or the mass is, the greater the margin brake torque is.

11 . The control method according to claim 1 , the control method further comprising:

determining the margin brake torque based on a confidence of a road slope, wherein the lower the confidence of the road slope is, the greater the margin brake torque is.

12 . The control method according to claim 9 , the control method further comprising:

when a rotation signal of motor axles and/or a wheel speed signal of the drive motor is received, increasing the braking force.

13 . The control method according to claim 10 , the control method further comprising:

when a rotation signal of motor axles and/or a wheel speed signal of the drive motor is received, increasing the braking force.

14 . The control method according to claim 11 , the control method further comprising:

when a rotation signal of motor axles and/or a wheel speed signal of the drive motor is received, increasing the braking force.

15 . The control method according to claim 1 , the control method further comprising:

when the driver requested drive torque increases to the critical torque, decreasing the brake torque to the effective brake torque.

16 . The control method according to claim 1 , the control method further comprising:

when the driver requested drive torque is continuously increasing after being greater than the critical torque but is less than the effective brake torque,

a) gradually decreasing the brake torque; and

b) outputting a driving enable signal to the drive motor controller to control the drive motor to gradually output the drive torque, wherein a sum of the brake torque and the drive torque is equal to the effective brake torque;

until the driver requested drive torque is increased to the effective brake torque.

17 . The control method according to claim 15 , the control method further comprising:

when the driver requested drive torque is continuously increasing after being greater than the critical torque but is less than the effective brake torque,

a) gradually decreasing the brake torque; and

b) outputting a driving enable signal to the drive motor controller to control the drive motor to gradually output the drive torque, wherein a sum of the brake torque and the drive torque is equal to the effective brake torque;

until the driver requested drive torque is increased to the effective brake torque.

18 . The control method according to claim 1 , the control method further comprising:

when the driver requested drive torque is continuously increased to be greater than the effective brake torque, stopping supplying the brake torque.

19 . The control method according to claim 15 , the control method further comprising:

when the driver requested drive torque is continuously increased to be greater than the effective brake torque, stopping supplying the brake torque.

20 . A brake control module of a vehicle's brake system comprising a memory and a processor; wherein the processor is configured to implement the steps of the control method for automatic holding according to claim 1 .

21 . A vehicle's brake system comprising two brake control modules according to claim 20 and electromechanical brakes controlled by the brake control modules to provide braking force to each wheel.