US 5,691,893 AGranted

Adaptive control system

AssigneeLotus Cars Limited

InventorIan MacGregor Stothers

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Abstract

An adaptive control system for reducing undesired signals comprises a processor (36) which provides secondary signals for sources (37) for interference with the undesired signals. Sensors (42) measure the residual Vibration which is indicative of the interference between the undesired and secondary signals. The processor (36) uses the residual signal to adjust the secondary signals to reduce the residual signals. Noise generation means (48) is provided to add a low level noise signal to the secondary signal and to provide a low level noise signal to the processor (36). The processor (36) is adapted to transform the low level noise signal and the residual signal from sensors (42) to provide the amplitude and phase of spectral components of the signals. The processor (36) modifies the secondary signals using these spectral components to obtain better reduction of the undesired signals.

Claims38

Dependent claims

An adaptive control system for reducing undesired signals comprising processing means adapted to provide at least one secondary signal to interfere with the undesired signals;

and residual means to provide for said processing means at least one residual signal indicative of the interference between said undesired and secondary signals;
wherein said processing means is adapted to use said at least one residual signal to adjust the or each secondary signal to reduce said at least one residual signal;
wherein;
noise generation means is provided which adds at least one low level noise signal to said at least one secondary signal and provides said at least one low level noise signal to said processing means;
said processing means is adapted to transform said at least one low level noise signal and said at least one residual signal to provide the amplitude and phase of spectral components of said signals;
signal means is provided which provides at least one first signal indicative of at least selected undesired signals;
said processing means filters the at least one first signal indicative of at least selected undesired signals using adaptive response filter means having first and second filter coefficients;
said processing means adapts said first filter coefficients using the spectral components of said at least one low level noise signal and said at least one residual signal;
said processing means uses the first filter coefficients to filter one of the at least first signal indicative of at least selected undesired signals and the at least one residual signal;
said processing means adapts said second filter coefficients in response to the at least first signal indicative of at least selected undesired signals and the at least one residual signal, one of said signals having been filtered using the first filter coefficients;
said processing means in producing the at least one secondary signal uses the second filter coefficients to filter the at least first signal indicative of at least selected undesired signals;
and
the processing means adapts said first and second filter coefficients to reduce said at least one residual signal.

10 more elements

A method of actively reducing undesired signals comprising the steps of:

providing at least one secondary signal which interferes with said undesired signals;
providing at least one residual signal indicative of the interference between said undesired and secondary signals;
adjusting the or each secondary signal using said at least one residual signal to reduce the or each residual signal;
generating at least one low level noise signal;
adding said at least one low level noise signal to said at least one secondary signal;
transforming said at least one low level noise signal and said at least one residual signal to provide the amplitude and phase of spectral components of said signals;
providing at least one first signal indicative of at least selected undesired signals;
filtering the at least one first signal indicative of at least selected undesired signals using adaptive response filter means having adaptable first and second filter coefficients;
adapting the first filter coefficients using said spectral components of said at least one low level noise signal and said at least one residual signal;
filtering one of said at least one first signal indicative of at least selected undesired signals and said at least one residual signal using the first filter coefficients;
adapting the second filter coefficients in response to said at least one first signal indicative of at least selected undesired signals and said at least one residual signal after having filtered one of said signals using the first filter coefficients;
filtering the at least one first signal indicative of at least selected undesired signals using the second filter coefficients in the production of the at least one secondary signal;
and
adapting said first and second filter coefficients to reduce said at least one residual signal.

11 more elements

Dependencies are inferred from the claim text.

Facts

Application: 08/416,765Filed 2 Jun 1995
Priority: GB 922210421 Oct 1992
Granted: 25 Nov 1997
Term ends: Not estimatedThe source records don’t support an estimate.

Classification11 codes

G10K 11/17883
Using both a reference signal and an error signal: the reference signal being derived from a machine operating condition, e.g. engine RPM or…
G10K 11/17854
Of the filter: the filter being an adaptive filter
G10K 2210/1082
Communication systems, e.g. where useful sound is kept and noise is cancelled: microphones, e.g. systems using "virtual" microphones
G10K 2210/3011
Computational: single acoustic input