Abstract
Active Noise Control (ANC) of noise transmitted through a vibrating plate
causes many problems not observed in classical ANC using loudspeakers.
They are mainly due to vibrations of a not ideally clamped plate and use
of nonlinear actuators, like MFC patches. In case of noise transmission
though a plate, nonlinerities exist in both primary and secondary paths.
Existence of nonlinerities in the system may degrade performance of a linear
feedforward control system usually used for ANC. The performance
degradation is especially visible for simple deterministic noise, such as
tonal noise, where very high reduction is expected. Linear feedforward
systems in such cases are unable to cope with higher harmonics generated
by the nonlinearities. Moreover, nonlinearities, if not properly tackled
with, may cause divergence of an adaptive control system.
In this paper a feedforward ANC system reducing sound transmitted through a
vibrating plate is presented. The ANC system uses nonlinear control
filters to suppress negative effects of nonlinearies in the system.
Filtered-error LMS algorithm, found more suitable than usually used
Filtered-reference LMS algorithm, is employed for updating parameters of
the nonlinear filters. The control system is experimentally verified and
obtained results are discussed.
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