Method and apparatus for actively reducing multiple-source repetitive vibrations

Abstract

A method and apparatus for reducing multiple-source repetitive vibrations in a region or structure (12) by applying control vibrations to the region or structure via actuators (18), frequently recalculating the control vibrations based on source elements to accommodate for varying phase differences between the sources of the repetitive vibrations (14) and (16), and cyclically updating the source elements of the control vibrations is disclosed. The repetitive vibrations are sensed (20) synchronously with the repetitive vibration source chosen as the reference source and decomposed into a number of frequency components corresponding to the reference source. The control vibrations are formed of the same frequency components and applied synchronously with the reference source. Each frequency component of the control vibrations is defined by source elements, one for cancelling vibrations produced by each of the repetitive vibration sources. A first estimate of the source elements of the frequency components, defining control vibrations that will reduce the sensed vibrations, is made. The source elements of the frequency components and the phase differences between the reference source and the other repetitive vibration sources are used to calculate control signals that drive the actuators ( 18) that produce the control vibrations. The control signals are frequently recalculated using the instantaneous phase differences. Cyclically, the source elements of the frequency components of the control vibrations are updated to improve the reduction of the sensed vibrations. The updated source elements are used to frequently recalculate the control signals driving the actuators based upon the instantaneous phase differences between the reference source and the other repetitive vibration sources.

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