Active noise control of acoustic enclosures using an approximate constant volume velocity source

This work focuses on the development and realization of dissipative feedback control of acoustic modes within three-dimensional enclosures. Loudspeakers are commonly used in active noise control applications, but introduce dynamics that are detrimental to controller performance. In this work, a method is presented to compensate a loudspeaker so that it approximates a constant volume velocity actuator over the piston-mode bandwidth. This effectively moves the speaker dynamics out of the control bandwidth of typical active control applications (50 Hz–600 Hz), and improves the actuator performance in feedback control applications.; The advantages offered by the compensated actuator are demonstrated by control experiments on a one-dimensional enclosure. A single-channel dissipative controller is realized using a collocated sensor microphone and constant volume velocity actuator, with a constant gain feedback control law. The results are compared to the performance achieved by static and dynamic controllers using uncompensated actuators. The results demonstrate that in addition to better actuator response afforded by the compensated speaker, accomplished by removing the transducer dynamics from the control bandwidth, a dissipative controller is more readily realized.; An array of collocated sensors and constant volume velocity actuators is used to control the low-frequency acoustic modes in a fuselage section. By spatially weighting the transducer arrays and using the sensors and actuators collectively, global dissipative control is achieved. Spatial weighting of the sensor and actuator arrays increases the controllability and observability of the target modes. This facilitates the design and implementation of dissipative controllers. Spatial weighting of the transducer arrays allows coupling to the desired modes and prevents coupling to other modes. This prevents spillover and increases the controller robustness. Test results from single-mode and multiple-mode controllers indicate significant reductions in the response of the target modes.