Method for estimating the locking pressure in the brake system of a multi-axle vehicle
In a method for estimating the locking pressure in the brake system of a multi-axle vehicle during a dynamic axle-load transfer, the locking pressure is ascertained during the axle-load transfer and the wheel normal force is ascertained at two points in time during the axle-load transfer and the locking pressure is ascertained therefrom at the later point in time.
1. A method for estimating a locking pressure in a brake system of a multi-axle vehicle in a dynamic axle-load transfer, the method comprising the following steps:
determining, during a braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer;
determining, at the first point in time, a wheel normal force at the vehicle wheel; and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time.
2. The method as recited in claim 1 , wherein the locking pressure during the dynamic axle-load transfer at the first point in time is ascertained during a brake pressure control process in the brake system.
3. The method as recited in claim 1 , wherein the locking pressure at the second point in time (T 2 ) during the axle-load transfer is ascertained from the relationship
p
bl
,
T
2
=
F
N
,
T
2
F
N
,
T
1
·
p
bl
,
T
1
wherein:
T 1 indicates a first point in time during the axle-load transfer;
T 2 indicates a second point in time during the axle-load transfer;
p b1,T1 indicates the locking pressure at time T 1 ;
p b1,T2 indicates the locking pressure at time T 2 ;
F N,T1 indicates the wheel normal force at time T 1 ; and
F N,T2 indicates the wheel normal force at time T 2 .
4. The method as recited in claim 3 , wherein in an adjustment of the brake pressure, a gradient of the locking pressure is taken into account in accordance with the following:
dp
bl
(
t
)
dt
=
p
bl
,
T
1
F
N
,
T
1
·
dF
N
(
t
)
dt
.
wherein
dp
bl
(
t
)
dt
is the gradient of the locking pressure at time t, and
dF
N
(
t
)
dt
is a gradient of the wheel normal force at the time t.
5. The method as recited in claim 1 , wherein the wheel normal forces are ascertained using a ride-height sensor, which measures body movements between a vehicle axle and a road surface.
6. The method as recited in claim 1 , wherein the axle-load transfer is ascertained by a ride-height sensor from a body movement or from the wheel normal forces.
7. The method as recited in claim 1 , wherein the method is performed during an ongoing brake pressure control process.
8. A method for improving a braking process, comprising the following steps:
estimating a locking pressure in a brake system of a multi-axle vehicle in a dynamic axle-load transfer, by:
determining, during the braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer,
determining, at the first point in time, a wheel normal force at the vehicle wheel, and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time, and
providing the locking pressure ascertained at the second point in time as a locking pressure prediction to a brake pressure control system as an input variable.
9. A control unit for controlling adjustable components of a hydraulic brake system in a vehicle, the control unit configured to:
estimate a locking pressure in the brake system of a multi-axle vehicle in a dynamic axle-load transfer, by:
determining, during a braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer,
determining, at the first point in time, a wheel normal force at the vehicle wheel, and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time, and
provide the locking pressure ascertained at the second point in time as a locking pressure prediction to a brake pressure control system as an input variable.
10. An hydraulic brake system in a vehicle, comprising:
a control unit for controlling adjustable components of the hydraulic brake system in a vehicle, the control unit configured to:
estimate a locking pressure in a brake system of a multi-axle vehicle in a dynamic axle-load transfer, by:
determining, during a braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer,
determining, at the first point in time, a wheel normal force at the vehicle wheel, and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time, and
provide the locking pressure ascertained at the second point in time as a locking pressure prediction to a brake pressure control system as an input variable.
11. A vehicle, comprising a hydraulic brake system including a control unit for controlling adjustable components of the hydraulic brake system in the vehicle, the control unit configured to:
estimate a locking pressure in the brake system of a multi-axle vehicle in a dynamic axle-load transfer, by:
determining, during a braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer,
determining, at the first point in time, a wheel normal force at the vehicle wheel, and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time, and
provide the locking pressure ascertained at the second point in time as a locking pressure prediction to a brake pressure control system as an input variable.
12. A non-transitory computer-readable storage medium on which is stored a computer program including program code for improving a braking process, the program code, when executed by a computer, causing the computer to perform the following steps:
estimating a locking pressure in a brake system of a multi-axle vehicle in a dynamic axle-load transfer, by:
determining, during a braking process, the locking pressure in a wheel brake device of a vehicle wheel at the vehicle wheel, at a first point in time during the axle-load transfer,
determining, at the first point in time, a wheel normal force at the vehicle wheel, and
ascertaining, at a second point in time subsequent to the first point in time, the locking pressure in the braking process, from the locking pressure determined at the first point in time, and from a relationship of a wheel normal force at the second point in time to the wheel normal force at the first point in time, and
providing the locking pressure ascertained at the second point in time as a locking pressure prediction to a brake pressure control system as an input variable.