Multi-mode vibration control of a flexible cantilever beam using adaptive resonant control

In this paper, an adaptive resonant controller is used to attenuate multi-mode vibrations in a flexible cantilever beam structure with varying loading conditions. This controller is particularly designed for structures that are exposed to previously unmodelled dynamics. On-line estimation of the structure's natural frequencies is used to update the adaptive resonant controller's parameters. The estimation of the natural frequencies is achieved using a parallel set of second-order recursive least squares estimators, each of which is designed for a specific vibration mode of concern. To achieve the desired estimation accuracy for each mode frequency, a different sampling rate suitable for that mode is used for the corresponding estimator. Experiment results show that the proposed adaptive strategy can achieve better performance, as measured by attenuation level, over its fixed-parameter counterpart for a range of unmodelled dynamics.