An adaptive modal-based active control system

Abstract

Active control for silencing sound and vibration has recently become the subject of much investigation, and is now being enhanced by the advent of adaptive filtering techniques. On another front, modal decomposition for active control problems has been shown to offer a number of practical advantages, as independent modal control can: minimize the number of actuators, sensors, and corresponding dimensionality of the controller, as well as minimize the control energy; provide robustness to system parameter uncertainty; and, minimize the adaptive convergence time by uncoupling the modal responses. In this paper, details are sketched for a narrow-band adaptive modal-based active control system that incorporates all of these features. The major topics addressed deal with modal filters, actuator prefilters, spatial sampling effects, and design methodology. Although this work pertains only to the narrow-band disturbance problem, these techniques can be readily generalized to the wideband case by using temporal filters to separate out different spectral bands for narrow-band modal-based processing. The analytical results are illustrated by numerical example for a vibrating cantilever beam, using a graphics display that was developed for real-time interactive design.