Feedforward noise cancellation in an airduct using generalized FIR filter estimation

Abstract

Absfrac-A feedforward control algorithm for active noise control based on the recursive estimation of a generalized finite impulse response (F'IR) filter is presented in this paper.The feedforward control algorithm is applied to a commercial air ventilation silencer to provide active noise compensation in an airduct A generalized FIR filter has the same linear parameter S~N C~U R as a taped delay FIR filter that is favorable for (recursive) estimation purposes. However, the advantage of the generalized FIR fiten lies in the possibility to include prior knowledge of system dynamics in the tapped delay line of the filter. By comparison with a conventional FIR filter implementation it is shnwo that a significant improvement in noise cancellation is obtained.

Filtered-error RLS for self-tuning disturbance feedforward control with application to a multi-axis vibration isolator

“…Similar to the steepest-descent method in (15), some step-size 𝜇(𝑘) and cost function 𝐽 = 1 2 E[𝒆 𝑇 (𝑘)𝒆(𝑘)] are used. In contrast to (15), the method in (20) contains an additional scaling with the inverse of 𝐀, representing the Hessian matrix of 𝐽 with respect to 𝒘.…”

“…Similar to the steepest-descent method in (15), some step-size 𝜇(𝑘) and cost function 𝐽 = 1 2 E[𝒆 𝑇 (𝑘)𝒆(𝑘)] are used. In contrast to (15), the method in (20) contains an additional scaling with the inverse of 𝐀, representing the Hessian matrix of 𝐽 with respect to 𝒘. This is useful because it compensates for eigenvalue spread in the autocorrelation matrix of the regressors, which is known to be a main cause for non-uniform convergence speeds of the parameters in LMS algorithms [14].…”

“…However, convergence speed is typically low, which can be attributed to large eigenvalue spread in the so-called covariance matrix. Various methods have been proposed to reduce this issue; Pre-whitened LMS [8] and normalized LMS (NLMS, [12]) reduce the eigenvalue spread for colored input signals, while eigenvalue spread due to plant dynamics can be reduced with modified FxLMS [8,13] and generalized filters with pre-defined controller poles stored in orthonormal basis functions [14,15]. Residual noise shaping was proposed multi-axis vibration isolation system.…”

“…𝑚𝑠 2 +𝑑𝑠+𝑘 is added to compensate the change in magnitude characteristics induced by P−1 𝟐 . LMS algorithms use an instantaneous approximation of the gradient in (15) by minimizing the instantaneous squared error, i.e. 𝐽 (𝑘) = 1 2 𝒆 𝑇 (𝑘)𝒆(𝑘).…”

Research on Active Noise Control in Power Transformer

“…In order to analyze the design of a feedforward compensator [4] F for active noise cancellation, consider the signal ) (t e that reflects the combined effect of sound due to external disturbance and control speaker. The dynamic relationship between the control input, the sound disturbance, and the error signal is shown in Fig.…”