Structural sensing of interior sound for active control of noise in structural-acoustic cavities

Abstract

This paper proposes a method for structural sensing of acoustic potential energy for active control of noise in a structural-acoustic cavity. The sensing strategy aims at global control and works with a fewer number of sensors. It is based on the established concept of radiation modes and hence does not add too many states to the order of the system. Acoustic potential energy is sensed using a combination of a Kalman filter and a frequency weighting filter with the structural response measurements as the inputs. The use of Kalman filter also makes the system robust against measurement noise. The formulation of the strategy is presented using finite element models of the system including that of sensors and actuators so that it can be easily applied to practical systems. The sensing strategy is numerically evaluated in the framework of Linear Quadratic Gaussian based feedback control of interior noise in a rectangular box cavity with a flexible plate with single and multiple pairs of piezoelectric sensor-actuator patches when broadband disturbances act on the plate. The performance is compared with an "acoustic filter" that models the complete transfer function from the structure to the acoustic domain. The sensing performance is also compared with a direct estimation strategy.

Frequency-independent radiation modes of interior sound radiation: An analytical study

“…Although a similarity in the numerical results of the singular vectors for different frequencies is observed, an independence of frequency is not conclusively proven. The concept of interior radiation modes is also used by Bagha et al in [13] for structural sensing of the acoustic potential energy. In order to reduce the number of sensors necessary, a numerical study is conducted, using the modal interaction approach.…”