A generalized approach to modal filtering for active noise control. I. Vibration sensing

Many techniques for controlling the noise radiated by large structures require a large number of inputs to the controller to produce global attenuation. Unfortunately, processing the large number of inputs required is often beyond the capabilities of current controllers. In attempting to overcome this problem, many researchers have adopted various modal-filtering-type techniques. Such techniques involve resolving a small number of important global quantities (traditionally structural modes) from a large number of sensor measurements. However, current approaches require detailed structural information at the design stage. Determining this for complex, real-world structures may be very difficult, preventing many techniques from going beyond the laboratory. The technique presented here outlines a new sensing system strategy, where the radiated sound field is decomposed using multipole radiation patterns, thereby alleviating the need for detailed structural information. Simulation and experimental results are presented.