ASA 127th Meeting M.I.T. 1994 June 6-10

5aNS13. Active damping of enclosed sound fields through direct rate feedback control.

Robert L. Clark

Dept. of Mech. Eng. and Mater. Sci., Duke Univ., Durham, NC 27708-0300

Daniel G. Cole

Virginia Polytech. Inst. and State Univ., Blacksburg, VA 24061

A new method of controlling enclosed sound fields subjected to impulsive or broadband disturbances is presented based upon direct rate-feedback control. Results from this preliminary study suggest that if a pressure transducer is collocated with a volumetric source in an enclosed sound field and rate-feedback control is employed, then the global properties of the sound field can be modified, specifically the modal damping ratio of the acoustic modes. Asymptotic stability of the control approach was demonstrated for positive feedback gains (neglecting specific sensor and actuator dynamics), making it model insensitive and thus ideal for actively tuning the transient characteristics and thus the reverberation time of the enclosure. Significant levels of global reduction in the acoustic potential energy can be achieved with the proposed control approach for stationary random disturbances or impulsive disturbances.