Adaptive control system
AssigneeLotus Cars Limited
InventorIan MacGregor Stothers
Life of this patent
Estimating the term…
Abstract
An adaptive control system for reducing undesired signals comprises sensors (31) to provide signals indicative of the undesired signals, and a processor (36) which processes the first signal to provide a secondary signal for output to sources (37) to interfere with the undesired signals. Sensors (42) are provided to detect the residual signals which are indicative of the interference between the undesired and secondary signals. Within the processor the signals indicative of the undesired signals and the residual signals are transformed into the frequency domain and collated. The outcome of the collation is inverse transformed and the processor adjusts the secondary signal using this inverse transform to reduce the residual signal from the sensors (42).
Claims40
An adaptive control system for reducing undesired signals, comprising signal means to provide at least one first signal indicative of at least some of the undesired signals;
- processing means which processes said at least one first signal 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 comprises:
- means for transforming said at least one first signal and said at least one residual signal to provide the amplitude and phase of spectral components of said signal;
- means for collating the transformed signals;
- means for inverse transforming of the outcome of said collation;
- adaptive response filter means having filter coefficients which filters the at least one first signal in providing the at least one secondary signal;
- means for adapting said filter coefficients to reduce each residual signal, which means for adapting adapts said filter coefficients using said inverse transform of the outcome of the collation;
- wherein:
- said means for collating said transformed signals has means for forming at least one cross spectral estimate;
- said means for inverse transforming of the outcome of the collation inverse transforms said at least one cross spectral estimate to form at least one cross correlation estimate;
- and said means for adapting the filter coefficients of said adaptive response filter means uses said at least one cross correlation estimate when adapting the filter coefficients.
A method of actively reducing undesired signals comprising the steps of:
- providing at least one first signal indicative of at least some of the undesired signals;
- using said at least one first signal to provide at least one secondary signal to interfere with said undesired signals;
- providing at least one residual signal indicative of the interference between said undesired and secondary signals;
- transforming said at least one first signal and said at least one residual signal to provide the amplitude and phase of spectral components of said signals;
- collating the transformed signals;
- inverse transforming the outcome of the collation;
- filtering said at least one secondary signal using filter coefficients in an adaptive response filter means to reduce the residual signals;
- adapting the filter coefficients using said inverse transform of the outcome of the collation;
- wherein the transformed signals are collated by forming at least one cross spectral estimate;
- said at least one cross spectral estimate is inverse transformed to form at least one cross correlation estimate;
- and said means for adapting said filter coefficients uses said at least one cross correlation.
An adaptive control system for reducing undesired signals, comprising signal means to provide at least one first signal indicative of at least some of the undesired signals;
- processing means which processes said at least one first signal to produce 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 comprises means for digitally sampling said at least one first signal and said at least one residual signal;
- means for storing a first plurality of digits for each said signal to form first signal and residual signal data blocks respectively;
- means for setting a second plurality of said digits at the end of each first signal data block to zero to form a modified first signal data block;
- means for transforming the modified first signal data block and the residual signal data block to provide the amplitude and phase of spectral components of said signals;
- means for transforming the at least one first signal to provide the amplitude and phase of spectral components of said signal;
- adaptive response filter means which filters the transformed first signal using complex filter coefficients in the provision of each secondary signal;
- and means for inverse transforming the filtered transformed first signal in the provision of said at least one secondary signal;
- wherein said processing means has means for forming at least one cross spectral estimate using the transforms of said at least one modified first signal data block and said at least one residual signal data block;
- and means for adapting the filter coefficients using said at least one cross spectral estimate.
A method of actively reducing undesired signals comprising the steps of using sensor means to sense undesired signals and to provide at least one first signal indicative of at least some of the undesired signals;
- using said at least one first signal to provide at least one secondary signal to interfere with said undesired signals;
- using residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
- digitally sampling said at least one first signal and said at least one residual signal;
- storing a first plurality of digits for each said signal to form first signal and residual signal data blocks;
- time aligning said first signal and residual signal data blocks;
- setting a second plurality of said digits at the end of each first signal data block to zero to form a modified first signal data block;
- transforming the modified first signal data block to provide the amplitude and phase of spectral components of said signals;
- transforming the at least one first signal to provide the amplitude and phase of spectral components of said signal;
- filtering the transformed at least one first signal using complex filter coefficients in an adaptive response filter means;
- inverse transforming the filtered transform of the at least one first signal in provision of said at least one secondary signal;
- wherein at least one cross spectral estimate is formed using the transform of said at least one modified first signal data block and said at least one residual signal data block;
- and the complex filter coefficients are adapted using said at least one cross spectral estimate.
Dependencies are inferred from the claim text.