An indirect adaptive feedback attenuation strategy for active vibration control

From a control point of view, active vibration control requires attenuation of unknown and/or time varying multiple narrow band disturbances. Internal Model Principle (IMP) is currently used for building adaptive active vibration control systems. IMP leads to asymptotic suppression of the disturbances but often introduces in the case of multiple narrow band disturbances a strong ”water bed” effect on the output sensitivity function (unwanted amplification). In this paper, an indirect adaptive control methodology for attenuation of multiple unknown time varying narrow-band disturbances is proposed. The method is based on the real time estimation of the frequency of narrow-band disturbances using adaptive notch filters (ANF) followed by the design of a controller using adjustable band-stop filters (BSF) for the appropriate shaping of the output sensitivity function. A Youla-Kučera parametrization of the controller is used for reducing the computation load. This approach is compared on an active vibration control (AVC) system with the direct adaptive control scheme based on the internal model principle (IMP) proposed in [1]. Real time experimental results are provided.