Practical active control of cavity noise using loop shaping: Two case studies

Abstract

A simple loop shaping technique is applied to design an optimal, robust feedback controller to reduce the interior noise of an acoustic cavity. It is a data-based technique that uses the measured plant response to tune the parameters of a fixed-structure controller in a graphical way. The two cases studied are narrowband noise control in a small cavity and broadband noise control in a long duct. Each control system consists of a microphone, a loudspeaker, and a controller connecting the two transducers that are further collocated. The fixed-structure of each controller should be chosen ahead of loop shaping and is determined in this paper solely based on the Nyquist plot of each plant measured. It turns out that a single band (high) pass filter of second order is suitable for the narrowband (broadband) noise control case considered. It is finally demonstrated with experiments that the technique is practical and a second order filter can be effectively used for active control of cavity noise in a single narrow or broad frequency band.

Optimal Filter Design of a Virtual Mechanical Impedance Control System for Multifrequency Active Sound Power Reduction of Enclosure Panels

“…j is the function for negative feedback control, and j is the inverse of the optimal mechanical impedance function in N s m . The biggest difference between the feedback controller for VMI control and the feedback controller for disturbance rejection control [15], such as ANC and AVC, is the presence of an additional feedback loop in the feedback controller. VMI control requires an additional feedback loop in the controller to obtain an error signal between the control mechanical impedance and the optimal mechanical impedance at the target frequency.…”

“…Therefore, the degree of robustness can be expressed as a circle of radius and for j and j , respectively, as shown in Fig. 3(a) [15]. Their inequalities are expressed in ( 10) and (11).…”

Robust H∞ Loop Shaping Controller Synthesis for SISO Systems by Complex Modular Functions

“…The loop shaping design procedure and synthesis for several kinds of single-input and single-output (SISO) systems have been implemented during recent years due to the selection of the frequency domain characteristics of the open and the closed-loop systems, this means, designing the control strategy based on the gain and phase margin specifications of the open-loop plant and the specifications of the closed-loop system [1][2][3][4][5][6]. The H ∞ loop shaping robust controller design was studied in recent years to synthesize controllers for SISO plants with unmodeled dynamics and/or uncertainties due to the importance of the controller synthesis in the process control field.…”