Simulation and experiment on active vibration isolation with an adaptive method

An adaptive controller for active vibration isolation is proposed on the basis of the filtered-x least-mean-squares method and enhanced with an anti-saturation scheme. In this method, vibration responses induced by a multi-tonal disturbance are decomposed into harmonic components with in-parallel tracking filters and attenuated independently. The centre frequencies of the tracking filters are adjusted by the recursively estimated frequencies of signal components. The anti-saturation scheme is derived on the basis of the normalized least-mean-squares algorithm, which is adopted to prevent excessive adaptation of weights in the presence of strong disturbances. Simulation and experiment on an active vibration isolation system consisting of a cylindrical shell and four actuators are conducted to examine the performance of the given adaptive control algorithm. Results have demonstrated that the adaptive method is effective in vibration isolation as well as saturation suppression, and the performance of active vibration isolation is related closely to structural vibration modes when control channels in multi-channel active isolation are strongly coupled.