Parameter estimation method for self-energized brake mechanism
AssigneeKNORR-BREMSE Systeme fuer Nutzfahrzeuge GmbH
InventorsLevente Balogh, Huba Nemeth
Life of this patent
Estimating the term…
Abstract
A method estimates parameters for a self-energized brake mechanism having a moving part, a brake pad, a brake disc, a caliper, and a wedge profile. The method includes the following acts: applying the same actuator force to the brake mechanism and simultaneously to a dynamical model of the brake mechanism; calculating deviations based on measured state variables of the brake mechanism and simulated state variables of the dynamical model; and producing the estimated parameters by online minimization. A device is provided for executing the method.
Claims8
A method for estimating parameters for a self-energized brake mechanism having a moving part, a brake pad, a brake disc, a caliper, and a wedge profile, the method comprising the acts of:
- applying a same actuator force to the brake mechanism and simultaneously to a dynamical model of the brake mechanism;
- calculating deviations based on measured state variables of the brake mechanism and simulated state variables of the dynamical model;
- and
- producing the estimated parameters by online minimization,
- wherein
- the parameters are a friction coefficient and an air gap of the brake pad and the brake disc,
- the act of calculating deviations comprises the acts of:
- calculating relative deviations:
- ɛ
- v
- a
- =
- v
- a
- mes
- -
- v
- a
- sim
- v
- a
- max
- ,
-
- ɛ
- x
- a
- =
- x
- a
- mes
- -
- x
- a
- sim
- x
- a
- max
- ,
- and calculating a summed weighted deviation:
- εc=(wxaεxa+wvaεva),
- the dynamical model is:
- [
- x
- .
- a
- v
- .
- a
- ]
- =
- [
- f
- 1
-
- (
- x
- )
- f
- 2
-
- (
- x
- ,
- d
- )
- ]
- +
- [
- g
- 1
- g
- 2
- ]
-
- u
- where state and input coordinate functions are as follows:
- f
- 1
-
- (
- x
- )
- =
- v
- a
- ,
-
- f
- 2
-
- (
- x
- ,
- d
- )
- =
- (
- k
- 0
-
- v
- a
-
- tan
-
-
- φ
- w
- +
- s
- 0
-
- (
- x
- a
-
- tan
-
-
- φ
- w
- -
- δ
- )
- )
-
- (
- μ
-
-
- cos
-
-
- φ
- w
- -
- sin
-
-
- φ
- w
- )
- m
- 1
- ,
-
- g
- 1
- =
- 0
- ,
-
- g
- 2
- =
- 1
- m
- 1
-
- cos
-
-
- φ
- a
- the online minimization is provided by a proportional and an
- integral portion of the sum deviation:
- μn+1=(Pμεc+Iμ∫εcdt)+μ,
- δn+1=−(Pδδc+Iδ∫εcdt)+δn,
- where P and I are minimization parameters, and
- the estimated parameters are adjusted alternately in time.
A device for parameter estimation for a self-energized brake mechanism having a moving part, a brake pad, a brake disc, a caliper, and a wedge profile, the device comprising:
- a brake mechanism with one or more measuring devices for state variables;
- a dynamical model for calculating one or more simulated state variables, wherein the dynamical model is based on the equations:
- [
- x
- .
- a
- v
- .
- a
- ]
- =
- [
- f
- 1
-
- (
- x
- )
- f
- 2
-
- (
- x
- ,
- d
- )
- ]
- +
- [
- g
- 1
- g
- 2
- ]
-
- u
- where state and input coordinate functions are as follows:
- f
- 1
-
- (
- x
- )
- =
- v
- a
- ,
- f
- 2
-
- (
- x
- ,
- d
- )
- =
- (
- k
- 0
-
- v
- a
-
- tan
-
-
- φ
- w
- +
- s
- 0
-
- (
- x
- a
-
- tan
-
-
- φ
- w
- -
- δ
- )
- )
-
- (
- μcos
-
-
- φ
- w
- -
- sin
-
-
- φ
- w
- )
- m
- 1
- ,
- g
- 1
- =
- 0
- ,
- g
- 2
- =
- 1
- m
- 1
-
- cos
-
-
- φ
- a
- ;
- a deviation unit for comparing the one or more measured state variables and the one or more simulated state variables, wherein calculated relative deviations are determined in accordance with the equations:
- ɛ
- v
- a
- =
- v
- a
- mes
- -
- v
- a
- sim
- v
- a
- max
- ,
-
- ɛ
- x
- a
- =
- x
- a
- mes
- -
- x
- a
- sim
- x
- a
- max
- ,
- and a summed weighted deviation is calculated in accordance with the equation:
- εc=(wxaεxa+wvaεva);
- and
- a minimization unit for providing estimated parameter values, wherein minimization is provided by a proportional and an integral portion of the sum deviation:
- μn+1=(Pμεc+Iμ∫εcdt)+μn,
- δn+1=−(Pδεc+Iδ∫εcdt)+δn,
- where P and I are minimization parameters, and estimated parameters are adjusted alternately in time,
- wherein inputs of the brake mechanism and the dynamical model are connected in parallel and outputs of the minimization unit are connected with the dynamical model for feed back,
- wherein the parameters are a friction coefficient and an air gap of the brake pad and the brake disc.
Dependencies are inferred from the claim text.