Control of Broadband Acoustic Radiation with Adaptive Structures

Active Structural Acoustic Control has been demonstrated for harmonic disturbances on various structures. This paper presents an extension of this work to the attenuation of acoustic radiation from planar structures subject to broadband disturbances. An adaptive, multiinput multi-output (MIMO), feedforward broadband acoustic control system has been developed. The control approach is the least mean squares (LMS) algorithm. The compensators are adaptive finite impulse response (FIR) filters. The control inputs are implemented with piezoceramic actuators. Both far-field microphones and polyvinylidene fluoride (PVDF) distributed structural sensors are used as error sensors. Both the actuator locations and the PVDF sensor configurations were optimally chosen to minimize radiated sound power assuming multiple frequency excitation. The disturbance is band-limited zero mean white noise and is implemented with a point force shaker. In the control of harmonically excited systems, satisfactory attenuation is possible with a single-input single-output (SISO) controller. In contrast, for systems excited with broadband disturbances, a MIMO controller is necessary for significant acoustic attenuation. Experimental results for the control of a simply supported plate are presented.