Feedback control of structurally radiated sound into enclosed spaces using structural sensing

Abstract

A technique is developed that addresses sensor and actuator placement and feedback control of structural/acoustic problems that can be described as a flexible structure surrounding an acoustic cavity. Specifically, this work is directed at the space launch vehicle problem, where it is assumed that it is not possible to obtain, in advance of a required control output, a coherent measurement of the disturbance or to directly measure the quantity to be controlled. These assumptions necessitate the use of structural sensing to predict the sound pressure in the cavity and of feedback control to reduce the radiated sound. A method for selecting sensor and actuator positions based on a transformation of the problem into radiation modes is covered as well as an optimal feedback control approach which allows the control of radiated pressure into a defined subvolume of the cavity using only structural actuators and sensors. Finally, an example problem is completed which draws on all of the theoretical development to suppress radiated sound within a subvolume.