Adaptive control system
First Claim
1. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
adapting means operative to adjust said at least one secondary signal using said at least one residual signal to reduce said at least on residual signal; and
adapting fault detection means to detect erroneous or faulty operation of the system and provide an indication of a fault;
whereinsaid adapting fault detection means comprises test means to periodically increase or decrease said at least one secondary signal by a predetermined amount; and
monitoring means to monitor said at least one residual signal and indicate a fault if during an increase or decrease in said at least one secondary signal there is, respectively, no decrease or increase by a predetermined amount in said at least one residual signal.
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Accused Products
Abstract
An adaptive control system for reducing undesired signals comprises a processor (36) to generate secondary signals which are provided to secondary sources (37). Sensors (42) provide at least one residual signal to said processor (36) which is indicative of the interference between the undesired and secondary signals. The processor (36) is operative to adjust the secondary signals using the residual signals to reduce the residual signals. If the adaptive control system operates erroneously or there is a fault this is indicated. Such faults can be detected by increasing and decreasing the secondary signals and detecting whether there is a corresponding increase and decrease in the residual signals. Also, the rate of change of the amplitude of the secondary signals and the rate of change of the frequency of the reference signal can be monitored to determine whether a fault condition exists. Also the impulse response or transfer function of the system can be monitored to determine a fault condition.
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Citations
29 Claims
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1. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
adapting means operative to adjust said at least one secondary signal using said at least one residual signal to reduce said at least on residual signal; and
adapting fault detection means to detect erroneous or faulty operation of the system and provide an indication of a fault;
whereinsaid adapting fault detection means comprises test means to periodically increase or decrease said at least one secondary signal by a predetermined amount; and monitoring means to monitor said at least one residual signal and indicate a fault if during an increase or decrease in said at least one secondary signal there is, respectively, no decrease or increase by a predetermined amount in said at least one residual signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- interference means to provide at least one secondary signal for interference with said undesired signals;
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16. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
adapting means operative to adjust said at least one secondary signal using said at least one residual signal to reduce said at least one residual signal; and
adapting fault detection means to detect erroneous or faulty operation of the system and provide an indication of a fault;
whereinsaid adapting means comprises adaptive response filter means having filter coefficients and adjusts said at least one secondary signal using said filter coefficients; and
, whereinsaid adapting fault detection means comprises filter coefficient change monitoring means to monitor the rate of change of the filter coefficients during adapting and to indicate a fault if the rate of change exceeds a predetermined value. - View Dependent Claims (17)
- interference means to provide at least one secondary signal for interference with said undesired signals;
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18. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
adapting means operative to adjust said at least one secondary signal using said at least one residual signal to reduce said at least one residual signal; and
adapting fault detection means to detect erroneous or faulty operation of the system and provide an indication of a fault;
whereinsaid adapting means comprises adaptive response filter means having filter coefficients and adjusts said at least one secondary signal using said filter coefficients; and
whereinsaid adapting fault detection means monitors the rate of change of said at least one secondary signal and indicates a fault if the rate of change exceeds a predetermined amount.
- interference means to provide at least one secondary signal for interference with said undesired signals;
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19. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
adapting means operative to adjust said at least one secondary signal using said at least one residual signal to reduce said at least one residual signal; and
adapting fault detection means to detect erroneous or faulty operation of the system and provide an indication of a fault;
wherein;said adapting means comprises adaptive response filter means having filter coefficients and adjusts said at least one secondary signal using said filter coefficients; wherein said adaptive response filter means has second filter coefficients which model the response of the or each residual signal to the respective secondary signal; and
whereinsaid system includes memory means adapted to store predetermined second filter coefficient data;
second adapting means operative to adaptively learn second filter coefficient data; and
filter comparison means to compare said learned second filter coefficient data with said predetermined second coefficient data and indicate a fault if any difference is greater than a predetermined amount;said interference means provides a plurality of secondary signals and said residual means provides a plurality of residual signals; said memory means is adapted to store at least one first preset vector containing for each secondary signal the sum of the contribution of the secondary signal received at each residual signal, and at least one second preset vector containing for each residual signal the sum of the contribution of each secondary signal received at the residual signal; said second adapting means is operative to learn values for the second filter coefficients; and said filter comparison means is operative to generate at least one first estimated vector containing for each secondary signal the sum of the contribution of the secondary signal received at each residual signal, and at least one second estimated vector containing for each residual signal the sum of the contribution of each secondary signal received at the residual signal, and to compare said first and second preset vectors with said first and second estimated vectors and indicate a fault if any difference is greater than a predetermined amount. - View Dependent Claims (20, 21, 22, 23, 24, 25)
- interference means to provide at least one secondary signal for interference with said undesired signals;
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26. An adaptive control system for reducing undesired signals comprising:
- interference means to provide at least one secondary signal for interference with said undesired signals;
residual means to provide at least one residual signal indicative of the interference between said undesired and secondary signals;
first adapting means comprising adaptive response filter means having first filter coefficients to adjust said at least one secondary signal, and second filter coefficients which model the response of each residual signal to respective each secondary signal;
second adapting means operative to learn the values of the second filter coefficients; and
memory means for storing a preset convergence coefficient;
said second adapting means generating at least one vector containing for each secondary signal the sum of the contribution of the secondary signal received at each residual signal;
the system including convergence coefficient normalization means to normalize said preset convergence coefficient with respect to said vector;
said adaptive response means being operative to use said normalized convergence coefficient to adjust said at least one secondary signal. - View Dependent Claims (27, 28, 29)
- interference means to provide at least one secondary signal for interference with said undesired signals;
Specification