US 5,745,580 A · Reduction of computational burden of adaptively updating control filter(s) in active systems

Abstract

An active control method and apparatus for controlling vibration or sound wherein the computational burden to adaptively update the control filter within the update model is reduced. The apparatus includes means for producing an input signal for input to the update model and the reduction block, means for generating an error sensor, and an output device for canceling sound and/or vibration at a selected location. The method uses a gradient descent algorithm such as the filtered-x LMS algorithm and replaces the long filter model with a shortened length filter model. Error signal information together with the output information from the shortened length filter model are used to update the coefficients of the control filter according to an update calculation method. The shortened filter model only contains frequency response information at the L frequencies of interest. Because of the reduced amount of information contained in the shortened filter model, more updates per unit of time can be performed on the control filter(s) or a smaller or fewer processors or CPU's may be utilized. The method has applicability to feed-forward and feed-back type systems and also to systems using a waveform generator for supplying the input signal. The reduction method may be implemented on-line or off-line.

Claims20

Dependent claims

A method of reducing the computational burden of an active system, comprising the steps of:

(a) obtaining an input signal indicative of characteristics of a source of disturbance, said input signal having dominant tones present therein to be canceled;
(b) extracting an error signal indicative of a residual disturbance at a selected location;
(c) inputting said input signal into an update model having a control filter for generating a control signal, said control filter having a plurality of control filter weights which are adaptively updated according to an update calculation method;
(d) determining coefficients of a long filter model which represents a frequency response of said system;
(e) transforming said long filter model into a shortened filter model;
(f) inputting said input signal into said shortened filter model to generate a shortened filter output;
(g) adaptively calculating said control filter weights of said control filter according to said update calculation method based upon said shortened filter output and said error signal;
and
(h) driving an output device responsive to said control signal in order to reduce at least one of vibration and sound at said selected location.

6 more elements

A method of reducing the computational burden of an active system, comprising the steps of:

(a) obtaining an input signal indicative of characteristics of a source of disturbance, said input signal having dominant tones present therein;
(b) obtaining an error signal indicative of a residual disturbance at a selected location;
(c) inputting said input signal into an update model having at least one control filter therein for generating a control signal, said at least one control filter having a plurality of control filter weights which are adaptively updated according to an update calculation method;
(d) determining a long filter model which represents a frequency response of said system, said long filter model being obtained in one selected from an on-line and off-line fashion;
(e) transforming said long filter model into a reduced filter model within a reduction block;
(f) inputting said input signal into said reduced filter model to generate a reduced filter output within said update model;
(g) adaptively calculating said control filter weights of said control filter within said update model according to said update calculation method based upon said shortened filter output and said error signal;
and
(h) driving an output device responsive to said control signal in order to reduce at least one of vibration and sound.

6 more elements

Dependencies are inferred from the claim text.

Reduction of computational burden of adaptively updating control filter(s) in active systems

Life of this patent

Reduction of computational burden of adaptively updating control filter(s) in active systems

Life of this patent

Abstract

Claims20