ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3pEA4. Active control of acoustic impedance with a multi-element system.

Brian H. Houston

Douglas M. Photiadis

J. A. Bucaro

Robert D. Corsaro

Naval Res. Lab., Washington, DC 20375-5350

Larry A. Kraus

SFA, Inc., Landover, MD 20785

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[sub (infinity)] control engineering techniques and the physics involved.