Adaptive control method for cyclic signal

An adaptive control method for a cyclic signal comprising the step of:

• adding an adaptive signal y(n) to a cyclic signal f(n) in an inverted phase at a measurement point by way of a transfer system having a predetermined transfer characteristic, thereby actively eliminating an influence of specific components of the cyclic signal f(n) to the measurement point, and suppressing an error signal e(n) detected at the measurement point to which the cyclic signal f(n) is input;
• the cyclic signal f(n) including at least one angular frequency ωk* (1≦k≦K′, k and K′ are natural numbers.);
• the adaptive signal y(n) being a linear combination of at least one sinusoidal signal whose angular frequencies ωk (1≦k≦K≦K′, K is also a natural number.) are K pieces of measurements or estimations of the angular frequencies ωk*;
• wherein the adaptive control method employing:
• an adaptive signal generation algorithm for generating the adaptive signal y(n) at each time n in a discrete time;
• and
• an adaptive coefficient vector renewing algorithm for carrying out a quasi-normalized gradient method;
• the quasi-normalized gradient method comprising the step of:
• subtracting a vector from an adaptive coefficient vector W(n), thereby renewing the adaptive coefficient vector W(n);
• the adaptive coefficient vector W(n) including components defining at least amplitudes and phases of the sinusoidal components of the adaptive signal y(n);
• the vector being prepared by multiplying components of a gradient vector ∇(n)=∂e2(n)/∂W(n) with appropriate step size parameters, and by dividing the resulting products with a sum (Ak+γk);
• Ak being gain measurements or gain estimations of the transfer characteristic corresponding to the angular frequencies ωk;
• γk (0≦γk) being appropriate divergence prevention constants;
• whereby at least the amplitudes and phases of the sinusoidal components of the adaptive signal y(n) are replaced with components of the renewed adaptive coefficient vector W(n).