Adaptive control system

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;
• and, wherein
• said 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.

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;
• and wherein
• said 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.

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 wherein
• said 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.

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.