Anti-lock control method and anti-lock control system for a braking system of a vehicle

An antilock control method for a braking system of a vehicle, the antilock control method comprising the following steps upon input of a brake request signal (S1):

• outputting a brake control signal (S2);
• building up a brake pressure (pb) via a braking medium at a wheel brake of a vehicle wheel (St1, t0);
• measuring a wheel speed (n) of the vehicle wheel to be braked (St3);
• determining at least one of the following:
• i) a wheel slip (s) of the wheel;
• and,
• ii) wheel circumferential velocity (v2) of the vehicle wheel;
• and,
• upon satisfying a first traction criterion (K1),
• i) activating a wheel drive unit;
• and,
• ii) applying a wheel drive torque (M2) to the vehicle wheel to increase the wheel circumferential velocity (v2) and to reduce the wheel slip (s) until a second traction criterion (K2) is satisfied;
• wherein a brake force (FB1) introduced in a wheel brake is still controlled as a function of the wheel slip (s);
• wherein, upon satisfying the first traction criterion (K1), the brake pressure (pb) is released;
• and,
• upon satisfying the second traction criterion (K2), the brake pressure (pb) is increased again.

An antilock control method for a braking system of a vehicle, the antilock control method comprising the following steps upon input of a brake request signal (S1):

• outputting a brake control signal (S2);
• building up a brake pressure (pb) via a braking medium at a wheel brake of a vehicle wheel (St1, t0);
• measuring a wheel speed (n) of the vehicle wheel to be braked (St3);
• determining at least one of the following:
• i) a wheel slip (s) of the wheel;
• and,
• ii) wheel circumferential velocity (v2) of the vehicle wheel;
• and,
• upon satisfying a first traction criterion (K1),
• i) activating a wheel drive unit;
• and,
• ii) applying a wheel drive torque (M2) to the vehicle wheel to increase the wheel circumferential velocity (v2) and to reduce the wheel slip (s) until a second traction criterion (K2) is satisfied;
• wherein at least one of the following applies:
• i) in the first traction criterion (K1), the determined wheel slip (s) is compared to a first slip limiting value (sg1) and the first traction criterion (K1) is satisfied when the determined wheel slip (s) exceeds the first slip limiting value (sg1);
• and,
• ii) a locking tendency of the vehicle wheel is assessed and the first traction criterion (K1) is satisfied when the locking tendency of the vehicle wheel is greater than a predefined limiting value of the locking tendency of the vehicle wheel.

An antilock control method for a braking system of a vehicle, the antilock control method comprising the following steps upon input of a brake request signal (S1):

• outputting a brake control signal (S2);
• building up a brake pressure (pb) via a braking medium at a wheel brake of a vehicle wheel (St1, t0);
• measuring a wheel speed (n) of the vehicle wheel to be braked (St3);
• determining at least one of the following:
• i) a wheel slip (s) of the wheel;
• and,
• ii) wheel circumferential velocity (v2) of the vehicle wheel;
• and,
• upon satisfying a first traction criterion (K1),
• i) activating a wheel drive unit;
• and,
• ii) applying a wheel drive torque (M2) to the vehicle wheel to increase the wheel circumferential velocity (v2) and to reduce the wheel slip (s) until a second traction criterion (K2) is satisfied;
• wherein a switchover occurs as a function of a switchover criterion (K3) between the antilock control with activation of the wheel drive unit and application of the wheel drive torque (M2) and an antilock control without wheel drive.

An antilock control system for antilock control of a vehicle wheel, the antilock control system comprising the following:

• a central brake control unit;
• a wheel brake for applying an introduced brake force (FB1) to the vehicle wheel as a function of a brake control signal (S2) output by said central brake control unit;
• a speed sensor for measuring a speed (n) of the vehicle wheel and outputting a speed signal (n) to said central brake control unit;
• a wheel drive unit for recording a drive control signal (S3) and applying a wheel drive torque (M2) to the vehicle wheel;
• said central brake control unit being configured to determine and evaluate a wheel slip (s) from at least the determined wheel speed signals (n) and an ABS reference velocity (vref) formed from a time behavior;
• and,
• upon satisfying a first traction criterion (K1) or a locking tendency of the vehicle wheel, said central brake control unit being further configured to activate the wheel drive unit to apply the wheel drive torque (M2) to reduce the wheel slip (s).

An antilock control system for antilock control of a vehicle wheel wherein the vehicle has a plurality of wheels, the antilock control system comprising:

• a central brake control unit;
• a plurality of wheel brakes for applying introduced respective brake forces (FB1) on corresponding ones of said wheels as a function of respective brake control signals (S2) outputted by said central brake control unit;
• respective speed sensors for measuring a speed (n) of said vehicle wheel and outputting respective speed signals (n) to said central brake control unit;
• wheel drive units for recording respective drive control signals and applying respective wheel drive torques (M2) on corresponding ones of vehicle wheels;
• said central brake control unit being configured to determine and evaluate a wheel slip (s) from at least the determined wheel speed signals (n) and an ABS reference velocity (vref) formed from a time behavior;
• and, upon satisfying a first traction criterion (K1) or a locking tendency of the vehicle wheels, being further configured to activate the wheel drive unit to apply the wheel drive torque (M2) to reduce the wheel slip (s);
• a central drive control unit for activating the wheel drive units of corresponding ones of said vehicle wheels using drive control signals (S3);
• and,
• said central drive control unit having a data connection to said central brake control unit or being integrated therein.