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US 7,688,984 B2Granted
Active noise control method and apparatus including feedforward and feedback controllers
AssigneeThe Regents of the University of California
InventorRaymond De Callafon
Life of this patent
Estimating the term…
Abstract
An active noise control apparatus for reducing noise from a noise source includes a microphone for detecting noise produced by the noise source, and a generalized finite impulse response (FIR) filter for receiving noise signals of the detected noise from the microphone and generating control signals for reducing the noise from the noise source. A speaker produces sound based on the control signals from the generalized FIR filter for substantially canceling the noise from the noise source.
Claims12
An active noise control apparatus for reducing noise from a noise source, comprising:
- a first detector for detecting noise produced by the noise source;
- a generalized finite impulse response (FIR) filter for receiving noise signals of the detected noise from said first detector, and generating control signals for reducing the noise from the noise source;
- and
- a sound generator for producing sound based on said control signals from said generalized FIR filter for substantially canceling the noise from the noise source;
- wherein said generalized FIR filter is described by
- F
-
- (
- q
- ,
- θ
- )
- =
- θ
- 0
- +
- ∑
- k
- =
- 1
- N
-
- θ
- k
-
- f
- k
-
- (
- q
- )
- ,
- θ
- =
- [
- θ
- 0
- ,
- θ
- 1
- ,
- …
-
- ,
- θ
- N
- ]
- where ƒk(q) are generalized (orthonormal) basis functions including information on a desired dynamic behavior of said generalized FIR filter, θ0 is the direct feedthrough term of said generalized FIR filter and θk are optimal filter coefficients of said generalized FIR filter;
- wherein said generalized FIR filter is constructed by initializing said basis function ƒk(q), and recursively estimating said θk based on said initialized basis function ƒk(q);
- and
- wherein said basis function ƒk(q) are initialized by a predetermined dynamical model that includes initial approximate information dynamics of said generalized FIR filter.
48 more elements
An active noise control apparatus for reducing noise from a noise source, comprising:
- a first detector for detecting noise produced by the noise source;
- a generalized finite impulse response (FIR) filter for receiving noise signals of the detected noise from said first detector, and generating control signals for reducing the noise from the noise source;
- a sound generator for producing sound based on said control signals from said generalized FIR filter for substantially canceling the noise from the noise source;
- and
- a second detector for detecting noise downstream of said sound generator;
- wherein a signal of the noise detected by the second detector is described by
- e
-
- (
- t
- )
- =
- W
-
- (
- q
- )
-
- [
- H
-
- (
- q
- )
- +
- G
-
- (
- q
- )
-
- F
-
- (
- q
- )
- 1
- -
- G
- c
-
- (
- q
- )
-
- F
-
- (
- q
- )
- ]
-
- n
-
- (
- t
- )
- where, W(q) is a stable and stable invertible noise filter for a white noise signal n(t);
- H(q) characterizes a dynamic relationship between the input signal u(t) from said first detector and said signal e(t) detected by said second detector;
- G(q) characterizes the relationship between said control signal from said generalized FIR filter F(q) and said signal e(t) detected by said second detector;
- and Gc(q) indicates an acoustic coupling from said sound generator signal back to said signal u(t)from said first detector that creates a positive feedback loop with said generalized FIR filter F(q).
58 more elements
A method for reducing noise from a noise source in an active noise control system, comprising:
- detecting first noise produced by the noise source;
- generating control signals from a generalized finite impulse response (FIR) filter for reducing the first noise from the noise source based on a first signal of said detected noise;
- and
- producing sound based on said control signals for substantially canceling said first noise from the noise source;
- wherein said generalized FIR filter is described by
- F
-
- (
- q
- ,
- θ
- )
- =
- θ
- 0
- +
- ∑
- k
- =
- 1
- N
-
- θ
- k
-
- f
- k
-
- (
- q
- )
- ,
- θ
- =
- [
- θ
- 0
- ,
- θ
- 1
- ,
- …
-
- ,
- θ
- N
- ]
- where ƒk(q) are generalized (orthonormal) basis functions containing information on a desired dynamic behavior of said generalized FIR filter, θ0 is a direct feedthrough term of said generalized FIR filter and θk are optimal filter coefficients of said generalized FIR filter;
- wherein said generalized FIR filter is constructed by initializing said basis function ƒk(q), and recursively estimating said θk based on said initialized basis function ƒk(q);
- and
- wherein said basis function ƒk(q) is initialized by a predetermined dynamical model tat includes initial approximate information dynamics of said generalized FIR filter.
48 more elements
A method for reducing noise from a noise source in an active noise control system, comprising:
- detecting first noise produced by the noise source;
- generating control signals from a generalized finite impulse response (FIR) filter for reducing the first noise from the noise source based on a first signal of said detected noise;
- producing sound based on said control signals for substantially canceling said first noise from the noise source;
- and
- detecting second noise after said sound based on said control signals has been produced by a second detector;
- wherein a second signal of the second noise detected after said sound based on said control signals has been produced by the second detector is described by
- e
-
- (
- t
- )
- =
- W
-
- (
- q
- )
-
- [
- H
-
- (
- q
- )
- +
- G
-
- (
- q
- )
-
- F
-
- (
- q
- )
- 1
- -
- G
- c
-
- (
- q
- )
-
- F
-
- (
- q
- )
- ]
-
- n
-
- (
- t
- )
- where, W(q) is a stable and stable invertible noise filter for a white noise signal n(t);
- H(q) characterizes a dynamic relationship between the first signal u(t) and said second signal e(t);
- G(q) characterizes the relationship between said control signal from said generalized FIR filter F(q) and said first signal e(t);
- and Gc(q) indicates an acoustic coupling from said sound generator signal back to said first signal u(t) that creates a positive feedback loop with said generalized FIR filter F(q).
58 more elements
An active noise control apparatus for reducing periodic noise from a noise source, comprising:
- a detector for detecting noise produced by the noise source;
- a controller for generating control signals for compensating the periodic noise detected in the noise;
- and
- a sound generator for producing sound based on said control signals from said controller for substantially canceling the periodic noise from the noise source;
- wherein said control signal is generated based on an equation,
- K
-
- (
- q
- )
- =
- arg
-
-
- min
- K
-
-
- α
-
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
-
- H
- n
-
- (
- q
- )
- 1
- -
- G
-
- (
- q
- )
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
- W
- i
-
-
- (
- q
- )
-
- H
- n
-
- (
- q
- )
- 1
- -
- G
-
- (
- q
- )
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
-
- 2
- where, Wi(q) is a discrete time internal dynamical model for reducing periodic disturbances, Hn(q) is a discrete time filter used to model the spectrum of the non-periodic noise disturbances, G(q) is a discrete time filter that models the dynamics between sound generator and said detector and α is a scalar real-valued constant.
94 more elements
A method for reducing periodic noise from a noise source, comprising:
- detecting noise produced by me noise source;
- generating control signals from a controller for compensating the periodic noise detected in the noise;
- and
- producing sound based on said control signals from said controller for substantially canceling the periodic noise from the noise source;
- wherein said control signal is generated based on an equation,
- K
-
- (
- q
- )
- =
- arg
-
-
- min
- K
-
-
- α
-
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
-
- H
- n
-
- (
- q
- )
- 1
- -
- G
-
- (
- q
- )
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
- W
- i
-
-
- (
- q
- )
-
- H
- n
-
- (
- q
- )
- 1
- -
- G
-
- (
- q
- )
-
- W
- i
-
- (
- q
- )
-
- K
-
- (
- q
- )
-
- 2
- where, Wi(q) is a discrete time internal dynamical model for reducing periodic disturbances, Hn(q) is a discrete time filter used to model a spectrum of the non-periodic noise disturbances, G(q) is a discrete time filter that models the dynamics between a sound generator for producing said sound based on said control signals and a detector for detecting the noise produced by the noise source, and α is a scalar real-valued constant.
94 more elements
Dependencies are inferred from the claim text.