Active control of acoustic impedance with a multi‐element system

Abstract

The use of active control of acoustic impedance is of general interest due to a variety of potential defense and civilian applications. These include control systems to minimize aircraft and rocket payload section interior acoustic levels. Control of impedance at a boundary is one of the most challenging in active control due to the collocation of sensors and actuators (implicit in this is feedback control). Some of the technical issues include—the selection of the appropriate physical control law, the degree of inter‐connectivity (local versus global control), device linearity, component and processor delays, system identification, nonminimal phase‐zero constraints the coupling matrix, and performance versus robustness tradeoffs. Recently, new active boundary control (ABC) experiments were carried out at NRL’s Laboratory for Structural Acoustics on a 15‐tile array system. The results of these experiments will be discussed with a focus on the application of H∞ control engineering techniques and the physics involved.