Reconfigurable actuator-sensor arrays for the active control of sound

A reconfigurable actuator-sensor array is demonstrated for the active control of sound and vibration. The concept is motivated by applications in which shaped polyvinylidene fluoride films are used as error sensors for feedforward and feedback noise control. The advantage of the present concept, as compared to a fixed-shape sensor, is that the reconfigurable array can be adapted on line to account for uncertain structural dynamics, making it a more effective error sensor for applications in which the structural dynamics are not accurately known a priori. The array developed for this work consists of twenty-two polyvinylidene fluoride film sensors and four multilayer piezoceramic actuators connected to a set of reprogrammable electronics. The reprogrammable electronics consist of two 16 by 1 digitally programmable gain boards and a digital signal processor with two analog inputs and outputs. The gains on the sensor array are set via the digital I/O of the digital signal processor. An off-line, frequency domain technique is used to design modal filters with the array of film sensors. Feedback and feedforward control algorithms are then implemented to demonstrate the use of the actuator-sensor array for noise and vibration suppression. The results indicate that the reconfigurable array technique has merit for noise and vibration control, although a fully adaptive, on-line algorithm has yet to be implemented.