Active Control of Low Frequency Modes in an Aircraft Fuselage Using Spatially Weighted Arrays

Abstract

Acoustic enclosures such as aircraft cabins often display lightly damped modal behavior at low frequencies where passive treatments are impractical due to mass and volume constraints. This work presents a feedback control approach using dynamic H2 controllers implemented with spatially weighted arrays of collocated pressure sensors and constant volume-velocity actuators. The open-loop system is shaped using spatially weighted transducer arrays to yield increased pole-zero separation, which results in better closed-loop performance. The transducer arrays are weighted to emphasize coupling to a particular acoustic mode or modes, which facilitates global control of the targeted dynamics. This work presents a method to determine the spatial weighting vectors for the transducer arrays from frequency response measurements. The development and implementation of low-order, dynamic H2 control laws is also discussed. Experimental results are presented for a single-mode and a multiple-mode controller implemented on an aircraft fuselage section, and demonstrate significant reduction of the targeted acoustic modes. To the best of the authors’ knowledge, this is the first experimental implementation of a feedback controller of this type capable of achieving such levels of global reduction in a three-dimensional acoustic system. [S0739-3717(00)02303-5]